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	* doc/gccint/target-macros/adding-support-for-named-address-spaces.rst: Use tm.rst.in file.
	* doc/gccint/target-macros/addressing-modes.rst: Likewise.
	* doc/gccint/target-macros/adjusting-the-instruction-scheduler.rst: Likewise.
	* doc/gccint/target-macros/anchored-addresses.rst: Likewise.
	* doc/gccint/target-macros/c++-abi-parameters.rst: Likewise.
	* doc/gccint/target-macros/condition-code-status.rst: Likewise.
	* doc/gccint/target-macros/controlling-debugging-information-format.rst: Likewise.
	* doc/gccint/target-macros/controlling-the-compilation-driver-gcc.rst: Likewise.
	* doc/gccint/target-macros/d-abi-parameters.rst: Likewise.
	* doc/gccint/target-macros/defining-target-specific-uses-of-attribute.rst: Likewise.
	* doc/gccint/target-macros/defining-the-output-assembler-language/assembler-commands-for-exception-regions.rst:
	Likewise.
	* doc/gccint/target-macros/defining-the-output-assembler-language/macros-controlling-initialization-routines.rst:
	Likewise.
	* doc/gccint/target-macros/defining-the-output-assembler-language/output-and-generation-of-labels.rst:
	Likewise.
	* doc/gccint/target-macros/defining-the-output-assembler-language/output-of-assembler-instructions.rst:
	Likewise.
	* doc/gccint/target-macros/defining-the-output-assembler-language/output-of-data.rst:
	Likewise.
	* doc/gccint/target-macros/defining-the-output-assembler-language/output-of-dispatch-tables.rst:
	Likewise.
	* doc/gccint/target-macros/defining-the-output-assembler-language/the-overall-framework-of-an-assembler-file.rst:
	Likewise.
	* doc/gccint/target-macros/describing-relative-costs-of-operations.rst: Likewise.
	* doc/gccint/target-macros/dividing-the-output-into-sections-texts-data.rst: Likewise.
	* doc/gccint/target-macros/emulating-tls.rst: Likewise.
	* doc/gccint/target-macros/implementing-the-varargs-macros.rst: Likewise.
	* doc/gccint/target-macros/implicit-calls-to-library-routines.rst: Likewise.
	* doc/gccint/target-macros/layout-of-source-language-data-types.rst: Likewise.
	* doc/gccint/target-macros/miscellaneous-parameters.rst: Likewise.
	* doc/gccint/target-macros/mode-switching-instructions.rst: Likewise.
	* doc/gccint/target-macros/parameters-for-precompiled-header-validity-checking.rst:
	Likewise.
	* doc/gccint/target-macros/register-classes.rst: Likewise.
	* doc/gccint/target-macros/register-usage.rst: Likewise.
	* doc/gccint/target-macros/run-time-target-specification.rst: Likewise.
	* doc/gccint/target-macros/stack-layout-and-calling-conventions/basic-stack-layout.rst:
	Likewise.
	* doc/gccint/target-macros/stack-layout-and-calling-conventions/eliminating-frame-pointer-and-arg-pointer.rst:
	Likewise.
	* doc/gccint/target-macros/stack-layout-and-calling-conventions/function-entry-and-exit.rst:
	Likewise.
	* doc/gccint/target-macros/stack-layout-and-calling-conventions/generating-code-for-profiling.rst:
	Likewise.
	* doc/gccint/target-macros/stack-layout-and-calling-conventions/how-large-values-are-returned.rst:
	Likewise.
	* doc/gccint/target-macros/stack-layout-and-calling-conventions/how-scalar-function-values-are-returned.rst:
	Likewise.
	* doc/gccint/target-macros/stack-layout-and-calling-conventions/miscellaneous-register-hooks.rst:
	Likewise.
	* doc/gccint/target-macros/stack-layout-and-calling-conventions/passing-arguments-in-registers.rst:
	Likewise.
	* doc/gccint/target-macros/stack-layout-and-calling-conventions/passing-function-arguments-on-the-stack.rst:
	Likewise.
	* doc/gccint/target-macros/stack-layout-and-calling-conventions/permitting-tail-calls.rst:
	Likewise.
	* doc/gccint/target-macros/stack-layout-and-calling-conventions/registers-that-address-the-stack-frame.rst:
	Likewise.
	* doc/gccint/target-macros/stack-layout-and-calling-conventions/shrink-wrapping-separate-components.rst:
	Likewise.
	* doc/gccint/target-macros/stack-layout-and-calling-conventions/specifying-how-stack-checking-is-done.rst:
	Likewise.
	* doc/gccint/target-macros/stack-layout-and-calling-conventions/stack-smashing-protection.rst:
	Likewise.
	* doc/gccint/target-macros/storage-layout.rst: Likewise.
	* doc/gccint/target-macros/support-for-nested-functions.rst: Likewise.
This commit is contained in:
Martin Liska 2022-11-07 13:13:56 +01:00
parent c8874c5e8a
commit 8f2b513c28
45 changed files with 1488 additions and 6473 deletions
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128
gcc/doc/gccint/target-macros/adding-support-for-named-address-spaces.rst
View File

@ -45,119 +45,51 @@ named address space #1:
#define ADDR_SPACE_EA 1
c_register_addr_space ("__ea", ADDR_SPACE_EA);
.. function:: scalar_int_mode TARGET_ADDR_SPACE_POINTER_MODE (addr_space_t address_space)
.. include:: tm.rst.in
:start-after: [TARGET_ADDR_SPACE_POINTER_MODE]
:end-before: [TARGET_ADDR_SPACE_POINTER_MODE]
.. hook-start:TARGET_ADDR_SPACE_POINTER_MODE
Define this to return the machine mode to use for pointers to
:samp:`{address_space}` if the target supports named address spaces.
The default version of this hook returns ``ptr_mode``.
.. include:: tm.rst.in
:start-after: [TARGET_ADDR_SPACE_ADDRESS_MODE]
:end-before: [TARGET_ADDR_SPACE_ADDRESS_MODE]
.. hook-end
.. function:: scalar_int_mode TARGET_ADDR_SPACE_ADDRESS_MODE (addr_space_t address_space)
.. include:: tm.rst.in
:start-after: [TARGET_ADDR_SPACE_VALID_POINTER_MODE]
:end-before: [TARGET_ADDR_SPACE_VALID_POINTER_MODE]
.. hook-start:TARGET_ADDR_SPACE_ADDRESS_MODE
Define this to return the machine mode to use for addresses in
:samp:`{address_space}` if the target supports named address spaces.
The default version of this hook returns ``Pmode``.
.. include:: tm.rst.in
:start-after: [TARGET_ADDR_SPACE_LEGITIMATE_ADDRESS_P]
:end-before: [TARGET_ADDR_SPACE_LEGITIMATE_ADDRESS_P]
.. hook-end
.. function:: bool TARGET_ADDR_SPACE_VALID_POINTER_MODE (scalar_int_mode mode, addr_space_t as)
.. include:: tm.rst.in
:start-after: [TARGET_ADDR_SPACE_LEGITIMIZE_ADDRESS]
:end-before: [TARGET_ADDR_SPACE_LEGITIMIZE_ADDRESS]
.. hook-start:TARGET_ADDR_SPACE_VALID_POINTER_MODE
Define this to return nonzero if the port can handle pointers
with machine mode :samp:`{mode}` to address space :samp:`{as}`. This target
hook is the same as the ``TARGET_VALID_POINTER_MODE`` target hook,
except that it includes explicit named address space support. The default
version of this hook returns true for the modes returned by either the
``TARGET_ADDR_SPACE_POINTER_MODE`` or ``TARGET_ADDR_SPACE_ADDRESS_MODE``
target hooks for the given address space.
.. include:: tm.rst.in
:start-after: [TARGET_ADDR_SPACE_SUBSET_P]
:end-before: [TARGET_ADDR_SPACE_SUBSET_P]
.. hook-end
.. function:: bool TARGET_ADDR_SPACE_LEGITIMATE_ADDRESS_P (machine_mode mode, rtx exp, bool strict, addr_space_t as)
.. include:: tm.rst.in
:start-after: [TARGET_ADDR_SPACE_ZERO_ADDRESS_VALID]
:end-before: [TARGET_ADDR_SPACE_ZERO_ADDRESS_VALID]
.. hook-start:TARGET_ADDR_SPACE_LEGITIMATE_ADDRESS_P
Define this to return true if :samp:`{exp}` is a valid address for mode
:samp:`{mode}` in the named address space :samp:`{as}`. The :samp:`{strict}`
parameter says whether strict addressing is in effect after reload has
finished. This target hook is the same as the
``TARGET_LEGITIMATE_ADDRESS_P`` target hook, except that it includes
explicit named address space support.
.. include:: tm.rst.in
:start-after: [TARGET_ADDR_SPACE_CONVERT]
:end-before: [TARGET_ADDR_SPACE_CONVERT]
.. hook-end
.. function:: rtx TARGET_ADDR_SPACE_LEGITIMIZE_ADDRESS (rtx x, rtx oldx, machine_mode mode, addr_space_t as)
.. include:: tm.rst.in
:start-after: [TARGET_ADDR_SPACE_DEBUG]
:end-before: [TARGET_ADDR_SPACE_DEBUG]
.. hook-start:TARGET_ADDR_SPACE_LEGITIMIZE_ADDRESS
Define this to modify an invalid address :samp:`{x}` to be a valid address
with mode :samp:`{mode}` in the named address space :samp:`{as}`. This target
hook is the same as the ``TARGET_LEGITIMIZE_ADDRESS`` target hook,
except that it includes explicit named address space support.
.. hook-end
.. function:: bool TARGET_ADDR_SPACE_SUBSET_P (addr_space_t subset, addr_space_t superset)
.. hook-start:TARGET_ADDR_SPACE_SUBSET_P
Define this to return whether the :samp:`{subset}` named address space is
contained within the :samp:`{superset}` named address space. Pointers to
a named address space that is a subset of another named address space
will be converted automatically without a cast if used together in
arithmetic operations. Pointers to a superset address space can be
converted to pointers to a subset address space via explicit casts.
.. hook-end
.. function:: bool TARGET_ADDR_SPACE_ZERO_ADDRESS_VALID (addr_space_t as)
.. hook-start:TARGET_ADDR_SPACE_ZERO_ADDRESS_VALID
Define this to modify the default handling of address 0 for the
address space. Return true if 0 should be considered a valid address.
.. hook-end
.. function:: rtx TARGET_ADDR_SPACE_CONVERT (rtx op, tree from_type, tree to_type)
.. hook-start:TARGET_ADDR_SPACE_CONVERT
Define this to convert the pointer expression represented by the RTL
:samp:`{op}` with type :samp:`{from_type}` that points to a named address
space to a new pointer expression with type :samp:`{to_type}` that points
to a different named address space. When this hook it called, it is
guaranteed that one of the two address spaces is a subset of the other,
as determined by the ``TARGET_ADDR_SPACE_SUBSET_P`` target hook.
.. hook-end
.. function:: int TARGET_ADDR_SPACE_DEBUG (addr_space_t as)
.. hook-start:TARGET_ADDR_SPACE_DEBUG
Define this to define how the address space is encoded in dwarf.
The result is the value to be used with ``DW_AT_address_class``.
.. hook-end
.. function:: void TARGET_ADDR_SPACE_DIAGNOSE_USAGE (addr_space_t as, location_t loc)
.. hook-start:TARGET_ADDR_SPACE_DIAGNOSE_USAGE
Define this hook if the availability of an address space depends on
command line options and some diagnostics should be printed when the
address space is used. This hook is called during parsing and allows
to emit a better diagnostic compared to the case where the address space
was not registered with ``c_register_addr_space``. :samp:`{as}` is
the address space as registered with ``c_register_addr_space``.
:samp:`{loc}` is the location of the address space qualifier token.
The default implementation does nothing.
.. hook-end
.. include:: tm.rst.in
:start-after: [TARGET_ADDR_SPACE_DIAGNOSE_USAGE]
:end-before: [TARGET_ADDR_SPACE_DIAGNOSE_USAGE]

728
gcc/doc/gccint/target-macros/addressing-modes.rst
View File

@ -58,75 +58,10 @@ This is about addressing modes.
the maximum number that ``TARGET_LEGITIMATE_ADDRESS_P`` would ever
accept.
.. function:: bool TARGET_LEGITIMATE_ADDRESS_P (machine_mode mode, rtx x, bool strict)
.. include:: tm.rst.in
:start-after: [TARGET_LEGITIMATE_ADDRESS_P]
:end-before: [TARGET_LEGITIMATE_ADDRESS_P]
.. hook-start:TARGET_LEGITIMATE_ADDRESS_P
A function that returns whether :samp:`{x}` (an RTX) is a legitimate memory
address on the target machine for a memory operand of mode :samp:`{mode}`.
Legitimate addresses are defined in two variants: a strict variant and a
non-strict one. The :samp:`{strict}` parameter chooses which variant is
desired by the caller.
The strict variant is used in the reload pass. It must be defined so
that any pseudo-register that has not been allocated a hard register is
considered a memory reference. This is because in contexts where some
kind of register is required, a pseudo-register with no hard register
must be rejected. For non-hard registers, the strict variant should look
up the ``reg_renumber`` array; it should then proceed using the hard
register number in the array, or treat the pseudo as a memory reference
if the array holds ``-1``.
The non-strict variant is used in other passes. It must be defined to
accept all pseudo-registers in every context where some kind of
register is required.
Normally, constant addresses which are the sum of a ``symbol_ref``
and an integer are stored inside a ``const`` RTX to mark them as
constant. Therefore, there is no need to recognize such sums
specifically as legitimate addresses. Normally you would simply
recognize any ``const`` as legitimate.
Usually ``PRINT_OPERAND_ADDRESS`` is not prepared to handle constant
sums that are not marked with ``const``. It assumes that a naked
``plus`` indicates indexing. If so, then you *must* reject such
naked constant sums as illegitimate addresses, so that none of them will
be given to ``PRINT_OPERAND_ADDRESS``.
.. index:: TARGET_ENCODE_SECTION_INFO and address validation
On some machines, whether a symbolic address is legitimate depends on
the section that the address refers to. On these machines, define the
target hook ``TARGET_ENCODE_SECTION_INFO`` to store the information
into the ``symbol_ref``, and then check for it here. When you see a
``const``, you will have to look inside it to find the
``symbol_ref`` in order to determine the section. See :ref:`assembler-format`.
.. index:: GO_IF_LEGITIMATE_ADDRESS
Some ports are still using a deprecated legacy substitute for
this hook, the ``GO_IF_LEGITIMATE_ADDRESS`` macro. This macro
has this syntax:
.. code-block:: c++
#define GO_IF_LEGITIMATE_ADDRESS (mode, x, label)
and should ``goto label`` if the address :samp:`{x}` is a valid
address on the target machine for a memory operand of mode :samp:`{mode}`.
.. index:: REG_OK_STRICT
Compiler source files that want to use the strict variant of this
macro define the macro ``REG_OK_STRICT``. You should use an
``#ifdef REG_OK_STRICT`` conditional to define the strict variant in
that case and the non-strict variant otherwise.
Using the hook is usually simpler because it limits the number of
files that are recompiled when changes are made.
.. hook-end
.. c:macro:: TARGET_MEM_CONSTRAINT
@ -152,33 +87,10 @@ This is about addressing modes.
The typical use of this macro is to handle addresses containing
a label_ref or symbol_ref within an UNSPEC.
.. function:: rtx TARGET_LEGITIMIZE_ADDRESS (rtx x, rtx oldx, machine_mode mode)
.. include:: tm.rst.in
:start-after: [TARGET_LEGITIMIZE_ADDRESS]
:end-before: [TARGET_LEGITIMIZE_ADDRESS]
.. hook-start:TARGET_LEGITIMIZE_ADDRESS
This hook is given an invalid memory address :samp:`{x}` for an
operand of mode :samp:`{mode}` and should try to return a valid memory
address.
.. index:: break_out_memory_refs
:samp:`{x}` will always be the result of a call to ``break_out_memory_refs``,
and :samp:`{oldx}` will be the operand that was given to that function to produce
:samp:`{x}`.
The code of the hook should not alter the substructure of
:samp:`{x}`. If it transforms :samp:`{x}` into a more legitimate form, it
should return the new :samp:`{x}`.
It is not necessary for this hook to come up with a legitimate address,
with the exception of native TLS addresses (see :ref:`emulated-tls`).
The compiler has standard ways of doing so in all cases. In fact, if
the target supports only emulated TLS, it
is safe to omit this hook or make it return :samp:`{x}` if it cannot find
a valid way to legitimize the address. But often a machine-dependent
strategy can generate better code.
.. hook-end
.. c:macro:: LEGITIMIZE_RELOAD_ADDRESS (x, mode, opnum, type, ind_levels, win)
@ -236,589 +148,201 @@ This is about addressing modes.
It is not necessary for this macro to come up with a legitimate
address; but often a machine-dependent strategy can generate better code.
.. function:: bool TARGET_MODE_DEPENDENT_ADDRESS_P (const_rtx addr, addr_space_t addrspace)
.. include:: tm.rst.in
:start-after: [TARGET_MODE_DEPENDENT_ADDRESS_P]
:end-before: [TARGET_MODE_DEPENDENT_ADDRESS_P]
.. hook-start:TARGET_MODE_DEPENDENT_ADDRESS_P
This hook returns ``true`` if memory address :samp:`{addr}` in address
space :samp:`{addrspace}` can have
different meanings depending on the machine mode of the memory
reference it is used for or if the address is valid for some modes
but not others.
.. include:: tm.rst.in
:start-after: [TARGET_LEGITIMATE_CONSTANT_P]
:end-before: [TARGET_LEGITIMATE_CONSTANT_P]
Autoincrement and autodecrement addresses typically have mode-dependent
effects because the amount of the increment or decrement is the size
of the operand being addressed. Some machines have other mode-dependent
addresses. Many RISC machines have no mode-dependent addresses.
You may assume that :samp:`{addr}` is a valid address for the machine.
.. include:: tm.rst.in
:start-after: [TARGET_PRECOMPUTE_TLS_P]
:end-before: [TARGET_PRECOMPUTE_TLS_P]
The default version of this hook returns ``false``.
.. hook-end
.. include:: tm.rst.in
:start-after: [TARGET_DELEGITIMIZE_ADDRESS]
:end-before: [TARGET_DELEGITIMIZE_ADDRESS]
.. function:: bool TARGET_LEGITIMATE_CONSTANT_P (machine_mode mode, rtx x)
.. hook-start:TARGET_LEGITIMATE_CONSTANT_P
.. include:: tm.rst.in
:start-after: [TARGET_CONST_NOT_OK_FOR_DEBUG_P]
:end-before: [TARGET_CONST_NOT_OK_FOR_DEBUG_P]
This hook returns true if :samp:`{x}` is a legitimate constant for a
:samp:`{mode}` -mode immediate operand on the target machine. You can assume that
:samp:`{x}` satisfies ``CONSTANT_P``, so you need not check this.
The default definition returns true.
.. include:: tm.rst.in
:start-after: [TARGET_CANNOT_FORCE_CONST_MEM]
:end-before: [TARGET_CANNOT_FORCE_CONST_MEM]
.. hook-end
.. function:: bool TARGET_PRECOMPUTE_TLS_P (machine_mode mode, rtx x)
.. include:: tm.rst.in
:start-after: [TARGET_USE_BLOCKS_FOR_CONSTANT_P]
:end-before: [TARGET_USE_BLOCKS_FOR_CONSTANT_P]
.. hook-start:TARGET_PRECOMPUTE_TLS_P
This hook returns true if :samp:`{x}` is a TLS operand on the target
machine that should be pre-computed when used as the argument in a call.
You can assume that :samp:`{x}` satisfies ``CONSTANT_P``, so you need not
check this.
.. include:: tm.rst.in
:start-after: [TARGET_USE_BLOCKS_FOR_DECL_P]
:end-before: [TARGET_USE_BLOCKS_FOR_DECL_P]
The default definition returns false.
.. hook-end
.. include:: tm.rst.in
:start-after: [TARGET_BUILTIN_RECIPROCAL]
:end-before: [TARGET_BUILTIN_RECIPROCAL]
.. function:: rtx TARGET_DELEGITIMIZE_ADDRESS (rtx x)
.. hook-start:TARGET_DELEGITIMIZE_ADDRESS
.. include:: tm.rst.in
:start-after: [TARGET_VECTORIZE_BUILTIN_MASK_FOR_LOAD]
:end-before: [TARGET_VECTORIZE_BUILTIN_MASK_FOR_LOAD]
This hook is used to undo the possibly obfuscating effects of the
``LEGITIMIZE_ADDRESS`` and ``LEGITIMIZE_RELOAD_ADDRESS`` target
macros. Some backend implementations of these macros wrap symbol
references inside an ``UNSPEC`` rtx to represent PIC or similar
addressing modes. This target hook allows GCC's optimizers to understand
the semantics of these opaque ``UNSPEC`` s by converting them back
into their original form.
.. hook-end
.. include:: tm.rst.in
:start-after: [TARGET_VECTORIZE_BUILTIN_VECTORIZATION_COST]
:end-before: [TARGET_VECTORIZE_BUILTIN_VECTORIZATION_COST]
.. function:: bool TARGET_CONST_NOT_OK_FOR_DEBUG_P (rtx x)
.. hook-start:TARGET_CONST_NOT_OK_FOR_DEBUG_P
.. include:: tm.rst.in
:start-after: [TARGET_VECTORIZE_PREFERRED_VECTOR_ALIGNMENT]
:end-before: [TARGET_VECTORIZE_PREFERRED_VECTOR_ALIGNMENT]
This hook should return true if :samp:`{x}` should not be emitted into
debug sections.
.. hook-end
.. include:: tm.rst.in
:start-after: [TARGET_VECTORIZE_VECTOR_ALIGNMENT_REACHABLE]
:end-before: [TARGET_VECTORIZE_VECTOR_ALIGNMENT_REACHABLE]
.. function:: bool TARGET_CANNOT_FORCE_CONST_MEM (machine_mode mode, rtx x)
.. hook-start:TARGET_CANNOT_FORCE_CONST_MEM
.. include:: tm.rst.in
:start-after: [TARGET_VECTORIZE_VEC_PERM_CONST]
:end-before: [TARGET_VECTORIZE_VEC_PERM_CONST]
This hook should return true if :samp:`{x}` is of a form that cannot (or
should not) be spilled to the constant pool. :samp:`{mode}` is the mode
of :samp:`{x}`.
The default version of this hook returns false.
.. include:: tm.rst.in
:start-after: [TARGET_VECTORIZE_BUILTIN_VECTORIZED_FUNCTION]
:end-before: [TARGET_VECTORIZE_BUILTIN_VECTORIZED_FUNCTION]
The primary reason to define this hook is to prevent reload from
deciding that a non-legitimate constant would be better reloaded
from the constant pool instead of spilling and reloading a register
holding the constant. This restriction is often true of addresses
of TLS symbols for various targets.
.. hook-end
.. include:: tm.rst.in
:start-after: [TARGET_VECTORIZE_BUILTIN_MD_VECTORIZED_FUNCTION]
:end-before: [TARGET_VECTORIZE_BUILTIN_MD_VECTORIZED_FUNCTION]
.. function:: bool TARGET_USE_BLOCKS_FOR_CONSTANT_P (machine_mode mode, const_rtx x)
.. hook-start:TARGET_USE_BLOCKS_FOR_CONSTANT_P
.. include:: tm.rst.in
:start-after: [TARGET_VECTORIZE_SUPPORT_VECTOR_MISALIGNMENT]
:end-before: [TARGET_VECTORIZE_SUPPORT_VECTOR_MISALIGNMENT]
This hook should return true if pool entries for constant :samp:`{x}` can
be placed in an ``object_block`` structure. :samp:`{mode}` is the mode
of :samp:`{x}`.
The default version returns false for all constants.
.. include:: tm.rst.in
:start-after: [TARGET_VECTORIZE_PREFERRED_SIMD_MODE]
:end-before: [TARGET_VECTORIZE_PREFERRED_SIMD_MODE]
.. hook-end
.. function:: bool TARGET_USE_BLOCKS_FOR_DECL_P (const_tree decl)
.. include:: tm.rst.in
:start-after: [TARGET_VECTORIZE_SPLIT_REDUCTION]
:end-before: [TARGET_VECTORIZE_SPLIT_REDUCTION]
.. hook-start:TARGET_USE_BLOCKS_FOR_DECL_P
This hook should return true if pool entries for :samp:`{decl}` should
be placed in an ``object_block`` structure.
.. include:: tm.rst.in
:start-after: [TARGET_VECTORIZE_AUTOVECTORIZE_VECTOR_MODES]
:end-before: [TARGET_VECTORIZE_AUTOVECTORIZE_VECTOR_MODES]
The default version returns true for all decls.
.. hook-end
.. include:: tm.rst.in
:start-after: [TARGET_VECTORIZE_RELATED_MODE]
:end-before: [TARGET_VECTORIZE_RELATED_MODE]
.. function:: tree TARGET_BUILTIN_RECIPROCAL (tree fndecl)
.. hook-start:TARGET_BUILTIN_RECIPROCAL
.. include:: tm.rst.in
:start-after: [TARGET_VECTORIZE_GET_MASK_MODE]
:end-before: [TARGET_VECTORIZE_GET_MASK_MODE]
This hook should return the DECL of a function that implements the
reciprocal of the machine-specific builtin function :samp:`{fndecl}`, or
``NULL_TREE`` if such a function is not available.
.. hook-end
.. include:: tm.rst.in
:start-after: [TARGET_VECTORIZE_EMPTY_MASK_IS_EXPENSIVE]
:end-before: [TARGET_VECTORIZE_EMPTY_MASK_IS_EXPENSIVE]
.. function:: tree TARGET_VECTORIZE_BUILTIN_MASK_FOR_LOAD (void)
.. hook-start:TARGET_VECTORIZE_BUILTIN_MASK_FOR_LOAD
.. include:: tm.rst.in
:start-after: [TARGET_VECTORIZE_CREATE_COSTS]
:end-before: [TARGET_VECTORIZE_CREATE_COSTS]
This hook should return the DECL of a function :samp:`{f}` that given an
address :samp:`{addr}` as an argument returns a mask :samp:`{m}` that can be
used to extract from two vectors the relevant data that resides in
:samp:`{addr}` in case :samp:`{addr}` is not properly aligned.
The autovectorizer, when vectorizing a load operation from an address
:samp:`{addr}` that may be unaligned, will generate two vector loads from
the two aligned addresses around :samp:`{addr}`. It then generates a
``REALIGN_LOAD`` operation to extract the relevant data from the
two loaded vectors. The first two arguments to ``REALIGN_LOAD``,
:samp:`{v1}` and :samp:`{v2}`, are the two vectors, each of size :samp:`{VS}`, and
the third argument, :samp:`{OFF}`, defines how the data will be extracted
from these two vectors: if :samp:`{OFF}` is 0, then the returned vector is
:samp:`{v2}` ; otherwise, the returned vector is composed from the last
:samp:`{VS}` - :samp:`{OFF}` elements of :samp:`{v1}` concatenated to the first
:samp:`{OFF}` elements of :samp:`{v2}`.
.. include:: tm.rst.in
:start-after: [TARGET_VECTORIZE_BUILTIN_GATHER]
:end-before: [TARGET_VECTORIZE_BUILTIN_GATHER]
If this hook is defined, the autovectorizer will generate a call
to :samp:`{f}` (using the DECL tree that this hook returns) and will
use the return value of :samp:`{f}` as the argument :samp:`{OFF}` to
``REALIGN_LOAD``. Therefore, the mask :samp:`{m}` returned by :samp:`{f}`
should comply with the semantics expected by ``REALIGN_LOAD``
described above.
If this hook is not defined, then :samp:`{addr}` will be used as
the argument :samp:`{OFF}` to ``REALIGN_LOAD``, in which case the low
log2(:samp:`{VS}`) - 1 bits of :samp:`{addr}` will be considered.
.. hook-end
.. include:: tm.rst.in
:start-after: [TARGET_VECTORIZE_BUILTIN_SCATTER]
:end-before: [TARGET_VECTORIZE_BUILTIN_SCATTER]
.. function:: int TARGET_VECTORIZE_BUILTIN_VECTORIZATION_COST (enum vect_cost_for_stmt type_of_cost, tree vectype, int misalign)
.. hook-start:TARGET_VECTORIZE_BUILTIN_VECTORIZATION_COST
.. include:: tm.rst.in
:start-after: [TARGET_SIMD_CLONE_COMPUTE_VECSIZE_AND_SIMDLEN]
:end-before: [TARGET_SIMD_CLONE_COMPUTE_VECSIZE_AND_SIMDLEN]
Returns cost of different scalar or vector statements for vectorization cost model.
For vector memory operations the cost may depend on type (:samp:`{vectype}`) and
misalignment value (:samp:`{misalign}`).
.. hook-end
.. include:: tm.rst.in
:start-after: [TARGET_SIMD_CLONE_ADJUST]
:end-before: [TARGET_SIMD_CLONE_ADJUST]
.. function:: poly_uint64 TARGET_VECTORIZE_PREFERRED_VECTOR_ALIGNMENT (const_tree type)
.. hook-start:TARGET_VECTORIZE_PREFERRED_VECTOR_ALIGNMENT
.. include:: tm.rst.in
:start-after: [TARGET_SIMD_CLONE_USABLE]
:end-before: [TARGET_SIMD_CLONE_USABLE]
This hook returns the preferred alignment in bits for accesses to
vectors of type :samp:`{type}` in vectorized code. This might be less than
or greater than the ABI-defined value returned by
``TARGET_VECTOR_ALIGNMENT``. It can be equal to the alignment of
a single element, in which case the vectorizer will not try to optimize
for alignment.
The default hook returns ``TYPE_ALIGN (type)``, which is
correct for most targets.
.. include:: tm.rst.in
:start-after: [TARGET_SIMT_VF]
:end-before: [TARGET_SIMT_VF]
.. hook-end
.. function:: bool TARGET_VECTORIZE_VECTOR_ALIGNMENT_REACHABLE (const_tree type, bool is_packed)
.. include:: tm.rst.in
:start-after: [TARGET_OMP_DEVICE_KIND_ARCH_ISA]
:end-before: [TARGET_OMP_DEVICE_KIND_ARCH_ISA]
.. hook-start:TARGET_VECTORIZE_VECTOR_ALIGNMENT_REACHABLE
Return true if vector alignment is reachable (by peeling N iterations)
for the given scalar type :samp:`{type}`. :samp:`{is_packed}` is false if the scalar
access using :samp:`{type}` is known to be naturally aligned.
.. include:: tm.rst.in
:start-after: [TARGET_GOACC_VALIDATE_DIMS]
:end-before: [TARGET_GOACC_VALIDATE_DIMS]
.. hook-end
.. function:: bool TARGET_VECTORIZE_VEC_PERM_CONST (machine_mode mode, machine_mode op_mode, rtx output, rtx in0, rtx in1, const vec_perm_indices &sel)
.. include:: tm.rst.in
:start-after: [TARGET_GOACC_DIM_LIMIT]
:end-before: [TARGET_GOACC_DIM_LIMIT]
.. hook-start:TARGET_VECTORIZE_VEC_PERM_CONST
This hook is used to test whether the target can permute up to two
vectors of mode :samp:`{op_mode}` using the permutation vector ``sel``,
producing a vector of mode :samp:`{mode}`. The hook is also used to emit such
a permutation.
.. include:: tm.rst.in
:start-after: [TARGET_GOACC_FORK_JOIN]
:end-before: [TARGET_GOACC_FORK_JOIN]
When the hook is being used to test whether the target supports a permutation,
:samp:`{in0}`, :samp:`{in1}`, and :samp:`{out}` are all null. When the hook is being used
to emit a permutation, :samp:`{in0}` and :samp:`{in1}` are the source vectors of mode
:samp:`{op_mode}` and :samp:`{out}` is the destination vector of mode :samp:`{mode}`.
:samp:`{in1}` is the same as :samp:`{in0}` if :samp:`{sel}` describes a permutation on one
vector instead of two.
Return true if the operation is possible, emitting instructions for it
if rtxes are provided.
.. include:: tm.rst.in
:start-after: [TARGET_GOACC_REDUCTION]
:end-before: [TARGET_GOACC_REDUCTION]
.. index:: vec_permm instruction pattern
If the hook returns false for a mode with multibyte elements, GCC will
try the equivalent byte operation. If that also fails, it will try forcing
the selector into a register and using the :samp:`{vec_perm {mode} }`
instruction pattern. There is no need for the hook to handle these two
implementation approaches itself.
.. include:: tm.rst.in
:start-after: [TARGET_PREFERRED_ELSE_VALUE]
:end-before: [TARGET_PREFERRED_ELSE_VALUE]
.. hook-end
.. function:: tree TARGET_VECTORIZE_BUILTIN_VECTORIZED_FUNCTION (unsigned code, tree vec_type_out, tree vec_type_in)
.. include:: tm.rst.in
:start-after: [TARGET_GOACC_ADJUST_PRIVATE_DECL]
:end-before: [TARGET_GOACC_ADJUST_PRIVATE_DECL]
.. hook-start:TARGET_VECTORIZE_BUILTIN_VECTORIZED_FUNCTION
This hook should return the decl of a function that implements the
vectorized variant of the function with the ``combined_fn`` code
:samp:`{code}` or ``NULL_TREE`` if such a function is not available.
The return type of the vectorized function shall be of vector type
:samp:`{vec_type_out}` and the argument types should be :samp:`{vec_type_in}`.
.. include:: tm.rst.in
:start-after: [TARGET_GOACC_EXPAND_VAR_DECL]
:end-before: [TARGET_GOACC_EXPAND_VAR_DECL]
.. hook-end
.. function:: tree TARGET_VECTORIZE_BUILTIN_MD_VECTORIZED_FUNCTION (tree fndecl, tree vec_type_out, tree vec_type_in)
.. include:: tm.rst.in
:start-after: [TARGET_GOACC_CREATE_WORKER_BROADCAST_RECORD]
:end-before: [TARGET_GOACC_CREATE_WORKER_BROADCAST_RECORD]
.. hook-start:TARGET_VECTORIZE_BUILTIN_MD_VECTORIZED_FUNCTION
This hook should return the decl of a function that implements the
vectorized variant of target built-in function ``fndecl``. The
return type of the vectorized function shall be of vector type
:samp:`{vec_type_out}` and the argument types should be :samp:`{vec_type_in}`.
.. hook-end
.. function:: bool TARGET_VECTORIZE_SUPPORT_VECTOR_MISALIGNMENT (machine_mode mode, const_tree type, int misalignment, bool is_packed)
.. hook-start:TARGET_VECTORIZE_SUPPORT_VECTOR_MISALIGNMENT
This hook should return true if the target supports misaligned vector
store/load of a specific factor denoted in the :samp:`{misalignment}`
parameter. The vector store/load should be of machine mode :samp:`{mode}` and
the elements in the vectors should be of type :samp:`{type}`. :samp:`{is_packed}`
parameter is true if the memory access is defined in a packed struct.
.. hook-end
.. function:: machine_mode TARGET_VECTORIZE_PREFERRED_SIMD_MODE (scalar_mode mode)
.. hook-start:TARGET_VECTORIZE_PREFERRED_SIMD_MODE
This hook should return the preferred mode for vectorizing scalar
mode :samp:`{mode}`. The default is
equal to ``word_mode``, because the vectorizer can do some
transformations even in absence of specialized SIMD hardware.
.. hook-end
.. function:: machine_mode TARGET_VECTORIZE_SPLIT_REDUCTION (machine_mode)
.. hook-start:TARGET_VECTORIZE_SPLIT_REDUCTION
This hook should return the preferred mode to split the final reduction
step on :samp:`{mode}` to. The reduction is then carried out reducing upper
against lower halves of vectors recursively until the specified mode is
reached. The default is :samp:`{mode}` which means no splitting.
.. hook-end
.. function:: unsigned int TARGET_VECTORIZE_AUTOVECTORIZE_VECTOR_MODES (vector_modes *modes, bool all)
.. hook-start:TARGET_VECTORIZE_AUTOVECTORIZE_VECTOR_MODES
If using the mode returned by ``TARGET_VECTORIZE_PREFERRED_SIMD_MODE``
is not the only approach worth considering, this hook should add one mode to
:samp:`{modes}` for each useful alternative approach. These modes are then
passed to ``TARGET_VECTORIZE_RELATED_MODE`` to obtain the vector mode
for a given element mode.
The modes returned in :samp:`{modes}` should use the smallest element mode
possible for the vectorization approach that they represent, preferring
integer modes over floating-poing modes in the event of a tie. The first
mode should be the ``TARGET_VECTORIZE_PREFERRED_SIMD_MODE`` for its
element mode.
If :samp:`{all}` is true, add suitable vector modes even when they are generally
not expected to be worthwhile.
The hook returns a bitmask of flags that control how the modes in
:samp:`{modes}` are used. The flags are:
.. envvar:: VECT_COMPARE_COSTS
Tells the loop vectorizer to try all the provided modes and pick the one
with the lowest cost. By default the vectorizer will choose the first
mode that works.
The hook does not need to do anything if the vector returned by
``TARGET_VECTORIZE_PREFERRED_SIMD_MODE`` is the only one relevant
for autovectorization. The default implementation adds no modes and
returns 0.
.. hook-end
.. function:: opt_machine_mode TARGET_VECTORIZE_RELATED_MODE (machine_mode vector_mode, scalar_mode element_mode, poly_uint64 nunits)
.. hook-start:TARGET_VECTORIZE_RELATED_MODE
If a piece of code is using vector mode :samp:`{vector_mode}` and also wants
to operate on elements of mode :samp:`{element_mode}`, return the vector mode
it should use for those elements. If :samp:`{nunits}` is nonzero, ensure that
the mode has exactly :samp:`{nunits}` elements, otherwise pick whichever vector
size pairs the most naturally with :samp:`{vector_mode}`. Return an empty
``opt_machine_mode`` if there is no supported vector mode with the
required properties.
There is no prescribed way of handling the case in which :samp:`{nunits}`
is zero. One common choice is to pick a vector mode with the same size
as :samp:`{vector_mode}` ; this is the natural choice if the target has a
fixed vector size. Another option is to choose a vector mode with the
same number of elements as :samp:`{vector_mode}` ; this is the natural choice
if the target has a fixed number of elements. Alternatively, the hook
might choose a middle ground, such as trying to keep the number of
elements as similar as possible while applying maximum and minimum
vector sizes.
The default implementation uses ``mode_for_vector`` to find the
requested mode, returning a mode with the same size as :samp:`{vector_mode}`
when :samp:`{nunits}` is zero. This is the correct behavior for most targets.
.. hook-end
.. function:: opt_machine_mode TARGET_VECTORIZE_GET_MASK_MODE (machine_mode mode)
.. hook-start:TARGET_VECTORIZE_GET_MASK_MODE
Return the mode to use for a vector mask that holds one boolean
result for each element of vector mode :samp:`{mode}`. The returned mask mode
can be a vector of integers (class ``MODE_VECTOR_INT``), a vector of
booleans (class ``MODE_VECTOR_BOOL``) or a scalar integer (class
``MODE_INT``). Return an empty ``opt_machine_mode`` if no such
mask mode exists.
The default implementation returns a ``MODE_VECTOR_INT`` with the
same size and number of elements as :samp:`{mode}`, if such a mode exists.
.. hook-end
.. function:: bool TARGET_VECTORIZE_EMPTY_MASK_IS_EXPENSIVE (unsigned ifn)
.. hook-start:TARGET_VECTORIZE_EMPTY_MASK_IS_EXPENSIVE
This hook returns true if masked internal function :samp:`{ifn}` (really of
type ``internal_fn``) should be considered expensive when the mask is
all zeros. GCC can then try to branch around the instruction instead.
.. hook-end
.. function:: class vector_costs * TARGET_VECTORIZE_CREATE_COSTS (vec_info *vinfo, bool costing_for_scalar)
.. hook-start:TARGET_VECTORIZE_CREATE_COSTS
This hook should initialize target-specific data structures in preparation
for modeling the costs of vectorizing a loop or basic block. The default
allocates three unsigned integers for accumulating costs for the prologue,
body, and epilogue of the loop or basic block. If :samp:`{loop_info}` is
non-NULL, it identifies the loop being vectorized; otherwise a single block
is being vectorized. If :samp:`{costing_for_scalar}` is true, it indicates the
current cost model is for the scalar version of a loop or block; otherwise
it is for the vector version.
.. hook-end
.. function:: tree TARGET_VECTORIZE_BUILTIN_GATHER (const_tree mem_vectype, const_tree index_type, int scale)
.. hook-start:TARGET_VECTORIZE_BUILTIN_GATHER
Target builtin that implements vector gather operation. :samp:`{mem_vectype}`
is the vector type of the load and :samp:`{index_type}` is scalar type of
the index, scaled by :samp:`{scale}`.
The default is ``NULL_TREE`` which means to not vectorize gather
loads.
.. hook-end
.. function:: tree TARGET_VECTORIZE_BUILTIN_SCATTER (const_tree vectype, const_tree index_type, int scale)
.. hook-start:TARGET_VECTORIZE_BUILTIN_SCATTER
Target builtin that implements vector scatter operation. :samp:`{vectype}`
is the vector type of the store and :samp:`{index_type}` is scalar type of
the index, scaled by :samp:`{scale}`.
The default is ``NULL_TREE`` which means to not vectorize scatter
stores.
.. hook-end
.. function:: int TARGET_SIMD_CLONE_COMPUTE_VECSIZE_AND_SIMDLEN (struct cgraph_node *, struct cgraph_simd_clone *, tree, int)
.. hook-start:TARGET_SIMD_CLONE_COMPUTE_VECSIZE_AND_SIMDLEN
This hook should set :samp:`{vecsize_mangle}`, :samp:`{vecsize_int}`, :samp:`{vecsize_float}`
fields in :samp:`{simd_clone}` structure pointed by :samp:`{clone_info}` argument and also
:samp:`{simdlen}` field if it was previously 0.
:samp:`{vecsize_mangle}` is a marker for the backend only. :samp:`{vecsize_int}` and
:samp:`{vecsize_float}` should be left zero on targets where the number of lanes is
not determined by the bitsize (in which case :samp:`{simdlen}` is always used).
The hook should return 0 if SIMD clones shouldn't be emitted,
or number of :samp:`{vecsize_mangle}` variants that should be emitted.
.. hook-end
.. function:: void TARGET_SIMD_CLONE_ADJUST (struct cgraph_node *)
.. hook-start:TARGET_SIMD_CLONE_ADJUST
This hook should add implicit ``attribute(target("..."))`` attribute
to SIMD clone :samp:`{node}` if needed.
.. hook-end
.. function:: int TARGET_SIMD_CLONE_USABLE (struct cgraph_node *)
.. hook-start:TARGET_SIMD_CLONE_USABLE
This hook should return -1 if SIMD clone :samp:`{node}` shouldn't be used
in vectorized loops in current function, or non-negative number if it is
usable. In that case, the smaller the number is, the more desirable it is
to use it.
.. hook-end
.. function:: int TARGET_SIMT_VF (void)
.. hook-start:TARGET_SIMT_VF
Return number of threads in SIMT thread group on the target.
.. hook-end
.. function:: int TARGET_OMP_DEVICE_KIND_ARCH_ISA (enum omp_device_kind_arch_isa trait, const char *name)
.. hook-start:TARGET_OMP_DEVICE_KIND_ARCH_ISA
Return 1 if :samp:`{trait}` :samp:`{name}` is present in the OpenMP context's
device trait set, return 0 if not present in any OpenMP context in the
whole translation unit, or -1 if not present in the current OpenMP context
but might be present in another OpenMP context in the same TU.
.. hook-end
.. function:: bool TARGET_GOACC_VALIDATE_DIMS (tree decl, int *dims, int fn_level, unsigned used)
.. hook-start:TARGET_GOACC_VALIDATE_DIMS
This hook should check the launch dimensions provided for an OpenACC
compute region, or routine. Defaulted values are represented as -1
and non-constant values as 0. The :samp:`{fn_level}` is negative for the
function corresponding to the compute region. For a routine it is the
outermost level at which partitioned execution may be spawned. The hook
should verify non-default values. If DECL is NULL, global defaults
are being validated and unspecified defaults should be filled in.
Diagnostics should be issued as appropriate. Return
true, if changes have been made. You must override this hook to
provide dimensions larger than 1.
.. hook-end
.. function:: int TARGET_GOACC_DIM_LIMIT (int axis)
.. hook-start:TARGET_GOACC_DIM_LIMIT
This hook should return the maximum size of a particular dimension,
or zero if unbounded.
.. hook-end
.. function:: bool TARGET_GOACC_FORK_JOIN (gcall *call, const int *dims, bool is_fork)
.. hook-start:TARGET_GOACC_FORK_JOIN
This hook can be used to convert IFN_GOACC_FORK and IFN_GOACC_JOIN
function calls to target-specific gimple, or indicate whether they
should be retained. It is executed during the oacc_device_lower pass.
It should return true, if the call should be retained. It should
return false, if it is to be deleted (either because target-specific
gimple has been inserted before it, or there is no need for it).
The default hook returns false, if there are no RTL expanders for them.
.. hook-end
.. function:: void TARGET_GOACC_REDUCTION (gcall *call)
.. hook-start:TARGET_GOACC_REDUCTION
This hook is used by the oacc_transform pass to expand calls to the
:samp:`{GOACC_REDUCTION}` internal function, into a sequence of gimple
instructions. :samp:`{call}` is gimple statement containing the call to
the function. This hook removes statement :samp:`{call}` after the
expanded sequence has been inserted. This hook is also responsible
for allocating any storage for reductions when necessary.
.. hook-end
.. function:: tree TARGET_PREFERRED_ELSE_VALUE (unsigned ifn, tree type, unsigned nops, tree *ops)
.. hook-start:TARGET_PREFERRED_ELSE_VALUE
This hook returns the target's preferred final argument for a call
to conditional internal function :samp:`{ifn}` (really of type
``internal_fn``). :samp:`{type}` specifies the return type of the
function and :samp:`{ops}` are the operands to the conditional operation,
of which there are :samp:`{nops}`.
For example, if :samp:`{ifn}` is ``IFN_COND_ADD``, the hook returns
a value of type :samp:`{type}` that should be used when :samp:`{ops}[0]`
and :samp:`{ops}[1]` are conditionally added together.
This hook is only relevant if the target supports conditional patterns
like ``cond_addm``. The default implementation returns a zero
constant of type :samp:`{type}`.
.. hook-end
.. function:: tree TARGET_GOACC_ADJUST_PRIVATE_DECL (location_t loc, tree var, int level)
.. hook-start:TARGET_GOACC_ADJUST_PRIVATE_DECL
This hook, if defined, is used by accelerator target back-ends to adjust
OpenACC variable declarations that should be made private to the given
parallelism level (i.e. ``GOMP_DIM_GANG``, ``GOMP_DIM_WORKER`` or
``GOMP_DIM_VECTOR``). A typical use for this hook is to force variable
declarations at the ``gang`` level to reside in GPU shared memory.
:samp:`{loc}` may be used for diagnostic purposes.
You may also use the ``TARGET_GOACC_EXPAND_VAR_DECL`` hook if the
adjusted variable declaration needs to be expanded to RTL in a non-standard
way.
.. hook-end
.. function:: rtx TARGET_GOACC_EXPAND_VAR_DECL (tree var)
.. hook-start:TARGET_GOACC_EXPAND_VAR_DECL
This hook, if defined, is used by accelerator target back-ends to expand
specially handled kinds of ``VAR_DECL`` expressions. A particular use is
to place variables with specific attributes inside special accelarator
memories. A return value of ``NULL`` indicates that the target does not
handle this ``VAR_DECL``, and normal RTL expanding is resumed.
Only define this hook if your accelerator target needs to expand certain
``VAR_DECL`` nodes in a way that differs from the default. You can also adjust
private variables at OpenACC device-lowering time using the
``TARGET_GOACC_ADJUST_PRIVATE_DECL`` target hook.
.. hook-end
.. function:: tree TARGET_GOACC_CREATE_WORKER_BROADCAST_RECORD (tree rec, bool sender, const char *name, unsigned HOST_WIDE_INT offset)
.. hook-start:TARGET_GOACC_CREATE_WORKER_BROADCAST_RECORD
Create a record used to propagate local-variable state from an active
worker to other workers. A possible implementation might adjust the type
of REC to place the new variable in shared GPU memory.
Presence of this target hook indicates that middle end neutering/broadcasting
be used.
.. hook-end
.. function:: void TARGET_GOACC_SHARED_MEM_LAYOUT (unsigned HOST_WIDE_INT *, unsigned HOST_WIDE_INT *, int[], unsigned HOST_WIDE_INT[], unsigned HOST_WIDE_INT[])
.. hook-start:TARGET_GOACC_SHARED_MEM_LAYOUT
Lay out a fixed shared-memory region on the target. The LO and HI
arguments should be set to a range of addresses that can be used for worker
broadcasting. The dimensions, reduction size and gang-private size
arguments are for the current offload region.
.. hook-end
.. include:: tm.rst.in
:start-after: [TARGET_GOACC_SHARED_MEM_LAYOUT]
:end-before: [TARGET_GOACC_SHARED_MEM_LAYOUT]

694
gcc/doc/gccint/target-macros/adjusting-the-instruction-scheduler.rst
View File

@ -13,648 +13,236 @@ adjustment in order to produce good code. GCC provides several target
hooks for this purpose. It is usually enough to define just a few of
them: try the first ones in this list first.
.. function:: int TARGET_SCHED_ISSUE_RATE (void)
.. hook-start:TARGET_SCHED_ISSUE_RATE
This hook returns the maximum number of instructions that can ever
issue at the same time on the target machine. The default is one.
Although the insn scheduler can define itself the possibility of issue
an insn on the same cycle, the value can serve as an additional
constraint to issue insns on the same simulated processor cycle (see
hooks :samp:`TARGET_SCHED_REORDER` and :samp:`TARGET_SCHED_REORDER2`).
This value must be constant over the entire compilation. If you need
it to vary depending on what the instructions are, you must use
:samp:`TARGET_SCHED_VARIABLE_ISSUE`.
.. include:: tm.rst.in
:start-after: [TARGET_SCHED_ISSUE_RATE]
:end-before: [TARGET_SCHED_ISSUE_RATE]
.. hook-end
.. function:: int TARGET_SCHED_VARIABLE_ISSUE (FILE *file, int verbose, rtx_insn *insn, int more)
.. include:: tm.rst.in
:start-after: [TARGET_SCHED_VARIABLE_ISSUE]
:end-before: [TARGET_SCHED_VARIABLE_ISSUE]
.. hook-start:TARGET_SCHED_VARIABLE_ISSUE
This hook is executed by the scheduler after it has scheduled an insn
from the ready list. It should return the number of insns which can
still be issued in the current cycle. The default is
:samp:`{more} - 1` for insns other than ``CLOBBER`` and
``USE``, which normally are not counted against the issue rate.
You should define this hook if some insns take more machine resources
than others, so that fewer insns can follow them in the same cycle.
:samp:`{file}` is either a null pointer, or a stdio stream to write any
debug output to. :samp:`{verbose}` is the verbose level provided by
:option:`-fsched-verbose-n`. :samp:`{insn}` is the instruction that
was scheduled.
.. include:: tm.rst.in
:start-after: [TARGET_SCHED_ADJUST_COST]
:end-before: [TARGET_SCHED_ADJUST_COST]
.. hook-end
.. function:: int TARGET_SCHED_ADJUST_COST (rtx_insn *insn, int dep_type1, rtx_insn *dep_insn, int cost, unsigned int dw)
.. include:: tm.rst.in
:start-after: [TARGET_SCHED_ADJUST_PRIORITY]
:end-before: [TARGET_SCHED_ADJUST_PRIORITY]
.. hook-start:TARGET_SCHED_ADJUST_COST
This function corrects the value of :samp:`{cost}` based on the
relationship between :samp:`{insn}` and :samp:`{dep_insn}` through a
dependence of type dep_type, and strength :samp:`{dw}`. It should return the new
value. The default is to make no adjustment to :samp:`{cost}`. This can be
used for example to specify to the scheduler using the traditional pipeline
description that an output- or anti-dependence does not incur the same cost
as a data-dependence. If the scheduler using the automaton based pipeline
description, the cost of anti-dependence is zero and the cost of
output-dependence is maximum of one and the difference of latency
times of the first and the second insns. If these values are not
acceptable, you could use the hook to modify them too. See also
see :ref:`processor-pipeline-description`.
.. include:: tm.rst.in
:start-after: [TARGET_SCHED_REORDER]
:end-before: [TARGET_SCHED_REORDER]
.. hook-end
.. function:: int TARGET_SCHED_ADJUST_PRIORITY (rtx_insn *insn, int priority)
.. include:: tm.rst.in
:start-after: [TARGET_SCHED_REORDER2]
:end-before: [TARGET_SCHED_REORDER2]
.. hook-start:TARGET_SCHED_ADJUST_PRIORITY
This hook adjusts the integer scheduling priority :samp:`{priority}` of
:samp:`{insn}`. It should return the new priority. Increase the priority to
execute :samp:`{insn}` earlier, reduce the priority to execute :samp:`{insn}`
later. Do not define this hook if you do not need to adjust the
scheduling priorities of insns.
.. include:: tm.rst.in
:start-after: [TARGET_SCHED_MACRO_FUSION_P]
:end-before: [TARGET_SCHED_MACRO_FUSION_P]
.. hook-end
.. function:: int TARGET_SCHED_REORDER (FILE *file, int verbose, rtx_insn **ready, int *n_readyp, int clock)
.. include:: tm.rst.in
:start-after: [TARGET_SCHED_MACRO_FUSION_PAIR_P]
:end-before: [TARGET_SCHED_MACRO_FUSION_PAIR_P]
.. hook-start:TARGET_SCHED_REORDER
This hook is executed by the scheduler after it has scheduled the ready
list, to allow the machine description to reorder it (for example to
combine two small instructions together on :samp:`VLIW` machines).
:samp:`{file}` is either a null pointer, or a stdio stream to write any
debug output to. :samp:`{verbose}` is the verbose level provided by
:option:`-fsched-verbose-n`. :samp:`{ready}` is a pointer to the ready
list of instructions that are ready to be scheduled. :samp:`{n_readyp}` is
a pointer to the number of elements in the ready list. The scheduler
reads the ready list in reverse order, starting with
:samp:`{ready}` [ :samp:`{*n_readyp}` - 1] and going to :samp:`{ready}` [0]. :samp:`{clock}`
is the timer tick of the scheduler. You may modify the ready list and
the number of ready insns. The return value is the number of insns that
can issue this cycle; normally this is just ``issue_rate``. See also
:samp:`TARGET_SCHED_REORDER2`.
.. include:: tm.rst.in
:start-after: [TARGET_SCHED_DEPENDENCIES_EVALUATION_HOOK]
:end-before: [TARGET_SCHED_DEPENDENCIES_EVALUATION_HOOK]
.. hook-end
.. function:: int TARGET_SCHED_REORDER2 (FILE *file, int verbose, rtx_insn **ready, int *n_readyp, int clock)
.. include:: tm.rst.in
:start-after: [TARGET_SCHED_INIT]
:end-before: [TARGET_SCHED_INIT]
.. hook-start:TARGET_SCHED_REORDER2
Like :samp:`TARGET_SCHED_REORDER`, but called at a different time. That
function is called whenever the scheduler starts a new cycle. This one
is called once per iteration over a cycle, immediately after
:samp:`TARGET_SCHED_VARIABLE_ISSUE`; it can reorder the ready list and
return the number of insns to be scheduled in the same cycle. Defining
this hook can be useful if there are frequent situations where
scheduling one insn causes other insns to become ready in the same
cycle. These other insns can then be taken into account properly.
.. include:: tm.rst.in
:start-after: [TARGET_SCHED_FINISH]
:end-before: [TARGET_SCHED_FINISH]
.. hook-end
.. function:: bool TARGET_SCHED_MACRO_FUSION_P (void)
.. include:: tm.rst.in
:start-after: [TARGET_SCHED_INIT_GLOBAL]
:end-before: [TARGET_SCHED_INIT_GLOBAL]
.. hook-start:TARGET_SCHED_MACRO_FUSION_P
This hook is used to check whether target platform supports macro fusion.
.. include:: tm.rst.in
:start-after: [TARGET_SCHED_FINISH_GLOBAL]
:end-before: [TARGET_SCHED_FINISH_GLOBAL]
.. hook-end
.. function:: bool TARGET_SCHED_MACRO_FUSION_PAIR_P (rtx_insn *prev, rtx_insn *curr)
.. include:: tm.rst.in
:start-after: [TARGET_SCHED_DFA_PRE_CYCLE_INSN]
:end-before: [TARGET_SCHED_DFA_PRE_CYCLE_INSN]
.. hook-start:TARGET_SCHED_MACRO_FUSION_PAIR_P
This hook is used to check whether two insns should be macro fused for
a target microarchitecture. If this hook returns true for the given insn pair
(:samp:`{prev}` and :samp:`{curr}`), the scheduler will put them into a sched
group, and they will not be scheduled apart. The two insns will be either
two SET insns or a compare and a conditional jump and this hook should
validate any dependencies needed to fuse the two insns together.
.. include:: tm.rst.in
:start-after: [TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN]
:end-before: [TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN]
.. hook-end
.. function:: void TARGET_SCHED_DEPENDENCIES_EVALUATION_HOOK (rtx_insn *head, rtx_insn *tail)
.. include:: tm.rst.in
:start-after: [TARGET_SCHED_DFA_POST_CYCLE_INSN]
:end-before: [TARGET_SCHED_DFA_POST_CYCLE_INSN]
.. hook-start:TARGET_SCHED_DEPENDENCIES_EVALUATION_HOOK
This hook is called after evaluation forward dependencies of insns in
chain given by two parameter values (:samp:`{head}` and :samp:`{tail}`
correspondingly) but before insns scheduling of the insn chain. For
example, it can be used for better insn classification if it requires
analysis of dependencies. This hook can use backward and forward
dependencies of the insn scheduler because they are already
calculated.
.. include:: tm.rst.in
:start-after: [TARGET_SCHED_INIT_DFA_POST_CYCLE_INSN]
:end-before: [TARGET_SCHED_INIT_DFA_POST_CYCLE_INSN]
.. hook-end
.. function:: void TARGET_SCHED_INIT (FILE *file, int verbose, int max_ready)
.. include:: tm.rst.in
:start-after: [TARGET_SCHED_DFA_PRE_ADVANCE_CYCLE]
:end-before: [TARGET_SCHED_DFA_PRE_ADVANCE_CYCLE]
.. hook-start:TARGET_SCHED_INIT
This hook is executed by the scheduler at the beginning of each block of
instructions that are to be scheduled. :samp:`{file}` is either a null
pointer, or a stdio stream to write any debug output to. :samp:`{verbose}`
is the verbose level provided by :option:`-fsched-verbose-n`.
:samp:`{max_ready}` is the maximum number of insns in the current scheduling
region that can be live at the same time. This can be used to allocate
scratch space if it is needed, e.g. by :samp:`TARGET_SCHED_REORDER`.
.. include:: tm.rst.in
:start-after: [TARGET_SCHED_DFA_POST_ADVANCE_CYCLE]
:end-before: [TARGET_SCHED_DFA_POST_ADVANCE_CYCLE]
.. hook-end
.. function:: void TARGET_SCHED_FINISH (FILE *file, int verbose)
.. include:: tm.rst.in
:start-after: [TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD]
:end-before: [TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD]
.. hook-start:TARGET_SCHED_FINISH
This hook is executed by the scheduler at the end of each block of
instructions that are to be scheduled. It can be used to perform
cleanup of any actions done by the other scheduling hooks. :samp:`{file}`
is either a null pointer, or a stdio stream to write any debug output
to. :samp:`{verbose}` is the verbose level provided by
:option:`-fsched-verbose-n`.
.. include:: tm.rst.in
:start-after: [TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD]
:end-before: [TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD]
.. hook-end
.. function:: void TARGET_SCHED_INIT_GLOBAL (FILE *file, int verbose, int old_max_uid)
.. include:: tm.rst.in
:start-after: [TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BEGIN]
:end-before: [TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BEGIN]
.. hook-start:TARGET_SCHED_INIT_GLOBAL
This hook is executed by the scheduler after function level initializations.
:samp:`{file}` is either a null pointer, or a stdio stream to write any debug output to.
:samp:`{verbose}` is the verbose level provided by :option:`-fsched-verbose-n`.
:samp:`{old_max_uid}` is the maximum insn uid when scheduling begins.
.. include:: tm.rst.in
:start-after: [TARGET_SCHED_FIRST_CYCLE_MULTIPASS_ISSUE]
:end-before: [TARGET_SCHED_FIRST_CYCLE_MULTIPASS_ISSUE]
.. hook-end
.. function:: void TARGET_SCHED_FINISH_GLOBAL (FILE *file, int verbose)
.. include:: tm.rst.in
:start-after: [TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BACKTRACK]
:end-before: [TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BACKTRACK]
.. hook-start:TARGET_SCHED_FINISH_GLOBAL
This is the cleanup hook corresponding to ``TARGET_SCHED_INIT_GLOBAL``.
:samp:`{file}` is either a null pointer, or a stdio stream to write any debug output to.
:samp:`{verbose}` is the verbose level provided by :option:`-fsched-verbose-n`.
.. include:: tm.rst.in
:start-after: [TARGET_SCHED_FIRST_CYCLE_MULTIPASS_END]
:end-before: [TARGET_SCHED_FIRST_CYCLE_MULTIPASS_END]
.. hook-end
.. function:: rtx TARGET_SCHED_DFA_PRE_CYCLE_INSN (void)
.. include:: tm.rst.in
:start-after: [TARGET_SCHED_FIRST_CYCLE_MULTIPASS_INIT]
:end-before: [TARGET_SCHED_FIRST_CYCLE_MULTIPASS_INIT]
.. hook-start:TARGET_SCHED_DFA_PRE_CYCLE_INSN
The hook returns an RTL insn. The automaton state used in the
pipeline hazard recognizer is changed as if the insn were scheduled
when the new simulated processor cycle starts. Usage of the hook may
simplify the automaton pipeline description for some VLIW
processors. If the hook is defined, it is used only for the automaton
based pipeline description. The default is not to change the state
when the new simulated processor cycle starts.
.. include:: tm.rst.in
:start-after: [TARGET_SCHED_FIRST_CYCLE_MULTIPASS_FINI]
:end-before: [TARGET_SCHED_FIRST_CYCLE_MULTIPASS_FINI]
.. hook-end
.. function:: void TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN (void)
.. include:: tm.rst.in
:start-after: [TARGET_SCHED_DFA_NEW_CYCLE]
:end-before: [TARGET_SCHED_DFA_NEW_CYCLE]
.. hook-start:TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN
The hook can be used to initialize data used by the previous hook.
.. include:: tm.rst.in
:start-after: [TARGET_SCHED_IS_COSTLY_DEPENDENCE]
:end-before: [TARGET_SCHED_IS_COSTLY_DEPENDENCE]
.. hook-end
.. function:: rtx_insn * TARGET_SCHED_DFA_POST_CYCLE_INSN (void)
.. include:: tm.rst.in
:start-after: [TARGET_SCHED_H_I_D_EXTENDED]
:end-before: [TARGET_SCHED_H_I_D_EXTENDED]
.. hook-start:TARGET_SCHED_DFA_POST_CYCLE_INSN
The hook is analogous to :samp:`TARGET_SCHED_DFA_PRE_CYCLE_INSN` but used
to changed the state as if the insn were scheduled when the new
simulated processor cycle finishes.
.. include:: tm.rst.in
:start-after: [TARGET_SCHED_ALLOC_SCHED_CONTEXT]
:end-before: [TARGET_SCHED_ALLOC_SCHED_CONTEXT]
.. hook-end
.. function:: void TARGET_SCHED_INIT_DFA_POST_CYCLE_INSN (void)
.. include:: tm.rst.in
:start-after: [TARGET_SCHED_INIT_SCHED_CONTEXT]
:end-before: [TARGET_SCHED_INIT_SCHED_CONTEXT]
.. hook-start:TARGET_SCHED_INIT_DFA_POST_CYCLE_INSN
The hook is analogous to :samp:`TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN` but
used to initialize data used by the previous hook.
.. include:: tm.rst.in
:start-after: [TARGET_SCHED_SET_SCHED_CONTEXT]
:end-before: [TARGET_SCHED_SET_SCHED_CONTEXT]
.. hook-end
.. function:: void TARGET_SCHED_DFA_PRE_ADVANCE_CYCLE (void)
.. include:: tm.rst.in
:start-after: [TARGET_SCHED_CLEAR_SCHED_CONTEXT]
:end-before: [TARGET_SCHED_CLEAR_SCHED_CONTEXT]
.. hook-start:TARGET_SCHED_DFA_PRE_ADVANCE_CYCLE
The hook to notify target that the current simulated cycle is about to finish.
The hook is analogous to :samp:`TARGET_SCHED_DFA_PRE_CYCLE_INSN` but used
to change the state in more complicated situations - e.g., when advancing
state on a single insn is not enough.
.. include:: tm.rst.in
:start-after: [TARGET_SCHED_FREE_SCHED_CONTEXT]
:end-before: [TARGET_SCHED_FREE_SCHED_CONTEXT]
.. hook-end
.. function:: void TARGET_SCHED_DFA_POST_ADVANCE_CYCLE (void)
.. include:: tm.rst.in
:start-after: [TARGET_SCHED_SPECULATE_INSN]
:end-before: [TARGET_SCHED_SPECULATE_INSN]
.. hook-start:TARGET_SCHED_DFA_POST_ADVANCE_CYCLE
The hook to notify target that new simulated cycle has just started.
The hook is analogous to :samp:`TARGET_SCHED_DFA_POST_CYCLE_INSN` but used
to change the state in more complicated situations - e.g., when advancing
state on a single insn is not enough.
.. include:: tm.rst.in
:start-after: [TARGET_SCHED_NEEDS_BLOCK_P]
:end-before: [TARGET_SCHED_NEEDS_BLOCK_P]
.. hook-end
.. function:: int TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD (void)
.. include:: tm.rst.in
:start-after: [TARGET_SCHED_GEN_SPEC_CHECK]
:end-before: [TARGET_SCHED_GEN_SPEC_CHECK]
.. hook-start:TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD
This hook controls better choosing an insn from the ready insn queue
for the DFA-based insn scheduler. Usually the scheduler
chooses the first insn from the queue. If the hook returns a positive
value, an additional scheduler code tries all permutations of
:samp:`TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD ()`
subsequent ready insns to choose an insn whose issue will result in
maximal number of issued insns on the same cycle. For the
VLIW processor, the code could actually solve the problem of
packing simple insns into the VLIW insn. Of course, if the
rules of VLIW packing are described in the automaton.
.. include:: tm.rst.in
:start-after: [TARGET_SCHED_SET_SCHED_FLAGS]
:end-before: [TARGET_SCHED_SET_SCHED_FLAGS]
This code also could be used for superscalar RISC
processors. Let us consider a superscalar RISC processor
with 3 pipelines. Some insns can be executed in pipelines :samp:`{A}` or
:samp:`{B}`, some insns can be executed only in pipelines :samp:`{B}` or
:samp:`{C}`, and one insn can be executed in pipeline :samp:`{B}`. The
processor may issue the 1st insn into :samp:`{A}` and the 2nd one into
:samp:`{B}`. In this case, the 3rd insn will wait for freeing :samp:`{B}`
until the next cycle. If the scheduler issues the 3rd insn the first,
the processor could issue all 3 insns per cycle.
Actually this code demonstrates advantages of the automaton based
pipeline hazard recognizer. We try quickly and easy many insn
schedules to choose the best one.
.. include:: tm.rst.in
:start-after: [TARGET_SCHED_CAN_SPECULATE_INSN]
:end-before: [TARGET_SCHED_CAN_SPECULATE_INSN]
The default is no multipass scheduling.
.. hook-end
.. include:: tm.rst.in
:start-after: [TARGET_SCHED_SMS_RES_MII]
:end-before: [TARGET_SCHED_SMS_RES_MII]
.. function:: int TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD (rtx_insn *insn, int ready_index)
.. hook-start:TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD
.. include:: tm.rst.in
:start-after: [TARGET_SCHED_DISPATCH]
:end-before: [TARGET_SCHED_DISPATCH]
This hook controls what insns from the ready insn queue will be
considered for the multipass insn scheduling. If the hook returns
zero for :samp:`{insn}`, the insn will be considered in multipass scheduling.
Positive return values will remove :samp:`{insn}` from consideration on
the current round of multipass scheduling.
Negative return values will remove :samp:`{insn}` from consideration for given
number of cycles.
Backends should be careful about returning non-zero for highest priority
instruction at position 0 in the ready list. :samp:`{ready_index}` is passed
to allow backends make correct judgements.
The default is that any ready insns can be chosen to be issued.
.. include:: tm.rst.in
:start-after: [TARGET_SCHED_DISPATCH_DO]
:end-before: [TARGET_SCHED_DISPATCH_DO]
.. hook-end
.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BEGIN (void *data, signed char *ready_try, int n_ready, bool first_cycle_insn_p)
.. include:: tm.rst.in
:start-after: [TARGET_SCHED_EXPOSED_PIPELINE]
:end-before: [TARGET_SCHED_EXPOSED_PIPELINE]
.. hook-start:TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BEGIN
This hook prepares the target backend for a new round of multipass
scheduling.
.. include:: tm.rst.in
:start-after: [TARGET_SCHED_REASSOCIATION_WIDTH]
:end-before: [TARGET_SCHED_REASSOCIATION_WIDTH]
.. hook-end
.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_ISSUE (void *data, signed char *ready_try, int n_ready, rtx_insn *insn, const void *prev_data)
.. include:: tm.rst.in
:start-after: [TARGET_SCHED_FUSION_PRIORITY]
:end-before: [TARGET_SCHED_FUSION_PRIORITY]
.. hook-start:TARGET_SCHED_FIRST_CYCLE_MULTIPASS_ISSUE
This hook is called when multipass scheduling evaluates instruction INSN.
.. hook-end
.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BACKTRACK (const void *data, signed char *ready_try, int n_ready)
.. hook-start:TARGET_SCHED_FIRST_CYCLE_MULTIPASS_BACKTRACK
This is called when multipass scheduling backtracks from evaluation of
an instruction.
.. hook-end
.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_END (const void *data)
.. hook-start:TARGET_SCHED_FIRST_CYCLE_MULTIPASS_END
This hook notifies the target about the result of the concluded current
round of multipass scheduling.
.. hook-end
.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_INIT (void *data)
.. hook-start:TARGET_SCHED_FIRST_CYCLE_MULTIPASS_INIT
This hook initializes target-specific data used in multipass scheduling.
.. hook-end
.. function:: void TARGET_SCHED_FIRST_CYCLE_MULTIPASS_FINI (void *data)
.. hook-start:TARGET_SCHED_FIRST_CYCLE_MULTIPASS_FINI
This hook finalizes target-specific data used in multipass scheduling.
.. hook-end
.. function:: int TARGET_SCHED_DFA_NEW_CYCLE (FILE *dump, int verbose, rtx_insn *insn, int last_clock, int clock, int *sort_p)
.. hook-start:TARGET_SCHED_DFA_NEW_CYCLE
This hook is called by the insn scheduler before issuing :samp:`{insn}`
on cycle :samp:`{clock}`. If the hook returns nonzero,
:samp:`{insn}` is not issued on this processor cycle. Instead,
the processor cycle is advanced. If \* :samp:`{sort_p}`
is zero, the insn ready queue is not sorted on the new cycle
start as usually. :samp:`{dump}` and :samp:`{verbose}` specify the file and
verbosity level to use for debugging output.
:samp:`{last_clock}` and :samp:`{clock}` are, respectively, the
processor cycle on which the previous insn has been issued,
and the current processor cycle.
.. hook-end
.. function:: bool TARGET_SCHED_IS_COSTLY_DEPENDENCE (struct _dep *_dep, int cost, int distance)
.. hook-start:TARGET_SCHED_IS_COSTLY_DEPENDENCE
This hook is used to define which dependences are considered costly by
the target, so costly that it is not advisable to schedule the insns that
are involved in the dependence too close to one another. The parameters
to this hook are as follows: The first parameter :samp:`{_dep}` is the dependence
being evaluated. The second parameter :samp:`{cost}` is the cost of the
dependence as estimated by the scheduler, and the third
parameter :samp:`{distance}` is the distance in cycles between the two insns.
The hook returns ``true`` if considering the distance between the two
insns the dependence between them is considered costly by the target,
and ``false`` otherwise.
Defining this hook can be useful in multiple-issue out-of-order machines,
where (a) it's practically hopeless to predict the actual data/resource
delays, however: (b) there's a better chance to predict the actual grouping
that will be formed, and (c) correctly emulating the grouping can be very
important. In such targets one may want to allow issuing dependent insns
closer to one another---i.e., closer than the dependence distance; however,
not in cases of 'costly dependences', which this hooks allows to define.
.. hook-end
.. function:: void TARGET_SCHED_H_I_D_EXTENDED (void)
.. hook-start:TARGET_SCHED_H_I_D_EXTENDED
This hook is called by the insn scheduler after emitting a new instruction to
the instruction stream. The hook notifies a target backend to extend its
per instruction data structures.
.. hook-end
.. function:: void * TARGET_SCHED_ALLOC_SCHED_CONTEXT (void)
.. hook-start:TARGET_SCHED_ALLOC_SCHED_CONTEXT
Return a pointer to a store large enough to hold target scheduling context.
.. hook-end
.. function:: void TARGET_SCHED_INIT_SCHED_CONTEXT (void *tc, bool clean_p)
.. hook-start:TARGET_SCHED_INIT_SCHED_CONTEXT
Initialize store pointed to by :samp:`{tc}` to hold target scheduling context.
It :samp:`{clean_p}` is true then initialize :samp:`{tc}` as if scheduler is at the
beginning of the block. Otherwise, copy the current context into :samp:`{tc}`.
.. hook-end
.. function:: void TARGET_SCHED_SET_SCHED_CONTEXT (void *tc)
.. hook-start:TARGET_SCHED_SET_SCHED_CONTEXT
Copy target scheduling context pointed to by :samp:`{tc}` to the current context.
.. hook-end
.. function:: void TARGET_SCHED_CLEAR_SCHED_CONTEXT (void *tc)
.. hook-start:TARGET_SCHED_CLEAR_SCHED_CONTEXT
Deallocate internal data in target scheduling context pointed to by :samp:`{tc}`.
.. hook-end
.. function:: void TARGET_SCHED_FREE_SCHED_CONTEXT (void *tc)
.. hook-start:TARGET_SCHED_FREE_SCHED_CONTEXT
Deallocate a store for target scheduling context pointed to by :samp:`{tc}`.
.. hook-end
.. function:: int TARGET_SCHED_SPECULATE_INSN (rtx_insn *insn, unsigned int dep_status, rtx *new_pat)
.. hook-start:TARGET_SCHED_SPECULATE_INSN
This hook is called by the insn scheduler when :samp:`{insn}` has only
speculative dependencies and therefore can be scheduled speculatively.
The hook is used to check if the pattern of :samp:`{insn}` has a speculative
version and, in case of successful check, to generate that speculative
pattern. The hook should return 1, if the instruction has a speculative form,
or -1, if it doesn't. :samp:`{request}` describes the type of requested
speculation. If the return value equals 1 then :samp:`{new_pat}` is assigned
the generated speculative pattern.
.. hook-end
.. function:: bool TARGET_SCHED_NEEDS_BLOCK_P (unsigned int dep_status)
.. hook-start:TARGET_SCHED_NEEDS_BLOCK_P
This hook is called by the insn scheduler during generation of recovery code
for :samp:`{insn}`. It should return ``true``, if the corresponding check
instruction should branch to recovery code, or ``false`` otherwise.
.. hook-end
.. function:: rtx TARGET_SCHED_GEN_SPEC_CHECK (rtx_insn *insn, rtx_insn *label, unsigned int ds)
.. hook-start:TARGET_SCHED_GEN_SPEC_CHECK
This hook is called by the insn scheduler to generate a pattern for recovery
check instruction. If :samp:`{mutate_p}` is zero, then :samp:`{insn}` is a
speculative instruction for which the check should be generated.
:samp:`{label}` is either a label of a basic block, where recovery code should
be emitted, or a null pointer, when requested check doesn't branch to
recovery code (a simple check). If :samp:`{mutate_p}` is nonzero, then
a pattern for a branchy check corresponding to a simple check denoted by
:samp:`{insn}` should be generated. In this case :samp:`{label}` can't be null.
.. hook-end
.. function:: void TARGET_SCHED_SET_SCHED_FLAGS (struct spec_info_def *spec_info)
.. hook-start:TARGET_SCHED_SET_SCHED_FLAGS
This hook is used by the insn scheduler to find out what features should be
enabled/used.
The structure \* :samp:`{spec_info}` should be filled in by the target.
The structure describes speculation types that can be used in the scheduler.
.. hook-end
.. function:: bool TARGET_SCHED_CAN_SPECULATE_INSN (rtx_insn *insn)
.. hook-start:TARGET_SCHED_CAN_SPECULATE_INSN
Some instructions should never be speculated by the schedulers, usually
because the instruction is too expensive to get this wrong. Often such
instructions have long latency, and often they are not fully modeled in the
pipeline descriptions. This hook should return ``false`` if :samp:`{insn}`
should not be speculated.
.. hook-end
.. function:: int TARGET_SCHED_SMS_RES_MII (struct ddg *g)
.. hook-start:TARGET_SCHED_SMS_RES_MII
This hook is called by the swing modulo scheduler to calculate a
resource-based lower bound which is based on the resources available in
the machine and the resources required by each instruction. The target
backend can use :samp:`{g}` to calculate such bound. A very simple lower
bound will be used in case this hook is not implemented: the total number
of instructions divided by the issue rate.
.. hook-end
.. function:: bool TARGET_SCHED_DISPATCH (rtx_insn *insn, int x)
.. hook-start:TARGET_SCHED_DISPATCH
This hook is called by Haifa Scheduler. It returns true if dispatch scheduling
is supported in hardware and the condition specified in the parameter is true.
.. hook-end
.. function:: void TARGET_SCHED_DISPATCH_DO (rtx_insn *insn, int x)
.. hook-start:TARGET_SCHED_DISPATCH_DO
This hook is called by Haifa Scheduler. It performs the operation specified
in its second parameter.
.. hook-end
.. c:var:: bool TARGET_SCHED_EXPOSED_PIPELINE
.. hook-start:TARGET_SCHED_EXPOSED_PIPELINE
True if the processor has an exposed pipeline, which means that not just
the order of instructions is important for correctness when scheduling, but
also the latencies of operations.
.. hook-end
.. function:: int TARGET_SCHED_REASSOCIATION_WIDTH (unsigned int opc, machine_mode mode)
.. hook-start:TARGET_SCHED_REASSOCIATION_WIDTH
This hook is called by tree reassociator to determine a level of
parallelism required in output calculations chain.
.. hook-end
.. function:: void TARGET_SCHED_FUSION_PRIORITY (rtx_insn *insn, int max_pri, int *fusion_pri, int *pri)
.. hook-start:TARGET_SCHED_FUSION_PRIORITY
This hook is called by scheduling fusion pass. It calculates fusion
priorities for each instruction passed in by parameter. The priorities
are returned via pointer parameters.
:samp:`{insn}` is the instruction whose priorities need to be calculated.
:samp:`{max_pri}` is the maximum priority can be returned in any cases.
:samp:`{fusion_pri}` is the pointer parameter through which :samp:`{insn}` 's
fusion priority should be calculated and returned.
:samp:`{pri}` is the pointer parameter through which :samp:`{insn}` 's priority
should be calculated and returned.
Same :samp:`{fusion_pri}` should be returned for instructions which should
be scheduled together. Different :samp:`{pri}` should be returned for
instructions with same :samp:`{fusion_pri}`. :samp:`{fusion_pri}` is the major
sort key, :samp:`{pri}` is the minor sort key. All instructions will be
scheduled according to the two priorities. All priorities calculated
should be between 0 (exclusive) and :samp:`{max_pri}` (inclusive). To avoid
false dependencies, :samp:`{fusion_pri}` of instructions which need to be
scheduled together should be smaller than :samp:`{fusion_pri}` of irrelevant
instructions.
Given below example:
.. code-block:: c++
ldr r10, [r1, 4]
add r4, r4, r10
ldr r15, [r2, 8]
sub r5, r5, r15
ldr r11, [r1, 0]
add r4, r4, r11
ldr r16, [r2, 12]
sub r5, r5, r16
On targets like ARM/AArch64, the two pairs of consecutive loads should be
merged. Since peephole2 pass can't help in this case unless consecutive
loads are actually next to each other in instruction flow. That's where
this scheduling fusion pass works. This hook calculates priority for each
instruction based on its fustion type, like:
.. code-block:: c++
ldr r10, [r1, 4] ; fusion_pri=99, pri=96
add r4, r4, r10 ; fusion_pri=100, pri=100
ldr r15, [r2, 8] ; fusion_pri=98, pri=92
sub r5, r5, r15 ; fusion_pri=100, pri=100
ldr r11, [r1, 0] ; fusion_pri=99, pri=100
add r4, r4, r11 ; fusion_pri=100, pri=100
ldr r16, [r2, 12] ; fusion_pri=98, pri=88
sub r5, r5, r16 ; fusion_pri=100, pri=100
Scheduling fusion pass then sorts all ready to issue instructions according
to the priorities. As a result, instructions of same fusion type will be
pushed together in instruction flow, like:
.. code-block:: c++
ldr r11, [r1, 0]
ldr r10, [r1, 4]
ldr r15, [r2, 8]
ldr r16, [r2, 12]
add r4, r4, r10
sub r5, r5, r15
add r4, r4, r11
sub r5, r5, r16
Now peephole2 pass can simply merge the two pairs of loads.
Since scheduling fusion pass relies on peephole2 to do real fusion
work, it is only enabled by default when peephole2 is in effect.
This is firstly introduced on ARM/AArch64 targets, please refer to
the hook implementation for how different fusion types are supported.
.. hook-end
.. function:: void TARGET_EXPAND_DIVMOD_LIBFUNC (rtx libfunc, machine_mode mode, rtx op0, rtx op1, rtx *quot, rtx *rem)
.. hook-start:TARGET_EXPAND_DIVMOD_LIBFUNC
Define this hook for enabling divmod transform if the port does not have
hardware divmod insn but defines target-specific divmod libfuncs.
.. hook-end
.. include:: tm.rst.in
:start-after: [TARGET_EXPAND_DIVMOD_LIBFUNC]
:end-before: [TARGET_EXPAND_DIVMOD_LIBFUNC]

56
gcc/doc/gccint/target-macros/anchored-addresses.rst
View File

@ -40,53 +40,21 @@ in order to make effective use of section anchors. It won't use
section anchors at all unless either ``TARGET_MIN_ANCHOR_OFFSET``
or ``TARGET_MAX_ANCHOR_OFFSET`` is set to a nonzero value.
.. c:var:: HOST_WIDE_INT TARGET_MIN_ANCHOR_OFFSET
.. include:: tm.rst.in
:start-after: [TARGET_MIN_ANCHOR_OFFSET]
:end-before: [TARGET_MIN_ANCHOR_OFFSET]
.. hook-start:TARGET_MIN_ANCHOR_OFFSET
The minimum offset that should be applied to a section anchor.
On most targets, it should be the smallest offset that can be
applied to a base register while still giving a legitimate address
for every mode. The default value is 0.
.. include:: tm.rst.in
:start-after: [TARGET_MAX_ANCHOR_OFFSET]
:end-before: [TARGET_MAX_ANCHOR_OFFSET]
.. hook-end
.. c:var:: HOST_WIDE_INT TARGET_MAX_ANCHOR_OFFSET
.. include:: tm.rst.in
:start-after: [TARGET_ASM_OUTPUT_ANCHOR]
:end-before: [TARGET_ASM_OUTPUT_ANCHOR]
.. hook-start:TARGET_MAX_ANCHOR_OFFSET
Like ``TARGET_MIN_ANCHOR_OFFSET``, but the maximum (inclusive)
offset that should be applied to section anchors. The default
value is 0.
.. hook-end
.. function:: void TARGET_ASM_OUTPUT_ANCHOR (rtx x)
.. hook-start:TARGET_ASM_OUTPUT_ANCHOR
Write the assembly code to define section anchor :samp:`{x}`, which is a
``SYMBOL_REF`` for which :samp:`SYMBOL_REF_ANCHOR_P ({x})` is true.
The hook is called with the assembly output position set to the beginning
of ``SYMBOL_REF_BLOCK (x)``.
If ``ASM_OUTPUT_DEF`` is available, the hook's default definition uses
it to define the symbol as :samp:`. + SYMBOL_REF_BLOCK_OFFSET ({x})`.
If ``ASM_OUTPUT_DEF`` is not available, the hook's default definition
is ``NULL``, which disables the use of section anchors altogether.
.. hook-end
.. function:: bool TARGET_USE_ANCHORS_FOR_SYMBOL_P (const_rtx x)
.. hook-start:TARGET_USE_ANCHORS_FOR_SYMBOL_P
Return true if GCC should attempt to use anchors to access ``SYMBOL_REF``
:samp:`{x}`. You can assume :samp:`SYMBOL_REF_HAS_BLOCK_INFO_P ({x})` and
:samp:`!SYMBOL_REF_ANCHOR_P ({x})`.
The default version is correct for most targets, but you might need to
intercept this hook to handle things like target-specific attributes
or target-specific sections.
.. hook-end
.. include:: tm.rst.in
:start-after: [TARGET_USE_ANCHORS_FOR_SYMBOL_P]
:end-before: [TARGET_USE_ANCHORS_FOR_SYMBOL_P]

168
gcc/doc/gccint/target-macros/c++-abi-parameters.rst
View File

@ -10,155 +10,71 @@
C++ ABI parameters
******************
.. function:: tree TARGET_CXX_GUARD_TYPE (void)
.. include:: tm.rst.in
:start-after: [TARGET_CXX_GUARD_TYPE]
:end-before: [TARGET_CXX_GUARD_TYPE]
.. hook-start:TARGET_CXX_GUARD_TYPE
Define this hook to override the integer type used for guard variables.
These are used to implement one-time construction of static objects. The
default is long_long_integer_type_node.
.. include:: tm.rst.in
:start-after: [TARGET_CXX_GUARD_MASK_BIT]
:end-before: [TARGET_CXX_GUARD_MASK_BIT]
.. hook-end
.. function:: bool TARGET_CXX_GUARD_MASK_BIT (void)
.. include:: tm.rst.in
:start-after: [TARGET_CXX_GET_COOKIE_SIZE]
:end-before: [TARGET_CXX_GET_COOKIE_SIZE]
.. hook-start:TARGET_CXX_GUARD_MASK_BIT
This hook determines how guard variables are used. It should return
``false`` (the default) if the first byte should be used. A return value of
``true`` indicates that only the least significant bit should be used.
.. include:: tm.rst.in
:start-after: [TARGET_CXX_COOKIE_HAS_SIZE]
:end-before: [TARGET_CXX_COOKIE_HAS_SIZE]
.. hook-end
.. function:: tree TARGET_CXX_GET_COOKIE_SIZE (tree type)
.. include:: tm.rst.in
:start-after: [TARGET_CXX_IMPORT_EXPORT_CLASS]
:end-before: [TARGET_CXX_IMPORT_EXPORT_CLASS]
.. hook-start:TARGET_CXX_GET_COOKIE_SIZE
This hook returns the size of the cookie to use when allocating an array
whose elements have the indicated :samp:`{type}`. Assumes that it is already
known that a cookie is needed. The default is
``max(sizeof (size_t), alignof(type))``, as defined in section 2.7 of the
IA64/Generic C++ ABI.
.. include:: tm.rst.in
:start-after: [TARGET_CXX_CDTOR_RETURNS_THIS]
:end-before: [TARGET_CXX_CDTOR_RETURNS_THIS]
.. hook-end
.. function:: bool TARGET_CXX_COOKIE_HAS_SIZE (void)
.. include:: tm.rst.in
:start-after: [TARGET_CXX_KEY_METHOD_MAY_BE_INLINE]
:end-before: [TARGET_CXX_KEY_METHOD_MAY_BE_INLINE]
.. hook-start:TARGET_CXX_COOKIE_HAS_SIZE
This hook should return ``true`` if the element size should be stored in
array cookies. The default is to return ``false``.
.. include:: tm.rst.in
:start-after: [TARGET_CXX_DETERMINE_CLASS_DATA_VISIBILITY]
:end-before: [TARGET_CXX_DETERMINE_CLASS_DATA_VISIBILITY]
.. hook-end
.. function:: int TARGET_CXX_IMPORT_EXPORT_CLASS (tree type, int import_export)
.. include:: tm.rst.in
:start-after: [TARGET_CXX_CLASS_DATA_ALWAYS_COMDAT]
:end-before: [TARGET_CXX_CLASS_DATA_ALWAYS_COMDAT]
.. hook-start:TARGET_CXX_IMPORT_EXPORT_CLASS
If defined by a backend this hook allows the decision made to export
class :samp:`{type}` to be overruled. Upon entry :samp:`{import_export}`
will contain 1 if the class is going to be exported, -1 if it is going
to be imported and 0 otherwise. This function should return the
modified value and perform any other actions necessary to support the
backend's targeted operating system.
.. include:: tm.rst.in
:start-after: [TARGET_CXX_LIBRARY_RTTI_COMDAT]
:end-before: [TARGET_CXX_LIBRARY_RTTI_COMDAT]
.. hook-end
.. function:: bool TARGET_CXX_CDTOR_RETURNS_THIS (void)
.. include:: tm.rst.in
:start-after: [TARGET_CXX_USE_AEABI_ATEXIT]
:end-before: [TARGET_CXX_USE_AEABI_ATEXIT]
.. hook-start:TARGET_CXX_CDTOR_RETURNS_THIS
This hook should return ``true`` if constructors and destructors return
the address of the object created/destroyed. The default is to return
``false``.
.. include:: tm.rst.in
:start-after: [TARGET_CXX_USE_ATEXIT_FOR_CXA_ATEXIT]
:end-before: [TARGET_CXX_USE_ATEXIT_FOR_CXA_ATEXIT]
.. hook-end
.. function:: bool TARGET_CXX_KEY_METHOD_MAY_BE_INLINE (void)
.. include:: tm.rst.in
:start-after: [TARGET_CXX_ADJUST_CLASS_AT_DEFINITION]
:end-before: [TARGET_CXX_ADJUST_CLASS_AT_DEFINITION]
.. hook-start:TARGET_CXX_KEY_METHOD_MAY_BE_INLINE
This hook returns true if the key method for a class (i.e., the method
which, if defined in the current translation unit, causes the virtual
table to be emitted) may be an inline function. Under the standard
Itanium C++ ABI the key method may be an inline function so long as
the function is not declared inline in the class definition. Under
some variants of the ABI, an inline function can never be the key
method. The default is to return ``true``.
.. hook-end
.. function:: void TARGET_CXX_DETERMINE_CLASS_DATA_VISIBILITY (tree decl)
.. hook-start:TARGET_CXX_DETERMINE_CLASS_DATA_VISIBILITY
:samp:`{decl}` is a virtual table, virtual table table, typeinfo object,
or other similar implicit class data object that will be emitted with
external linkage in this translation unit. No ELF visibility has been
explicitly specified. If the target needs to specify a visibility
other than that of the containing class, use this hook to set
``DECL_VISIBILITY`` and ``DECL_VISIBILITY_SPECIFIED``.
.. hook-end
.. function:: bool TARGET_CXX_CLASS_DATA_ALWAYS_COMDAT (void)
.. hook-start:TARGET_CXX_CLASS_DATA_ALWAYS_COMDAT
This hook returns true (the default) if virtual tables and other
similar implicit class data objects are always COMDAT if they have
external linkage. If this hook returns false, then class data for
classes whose virtual table will be emitted in only one translation
unit will not be COMDAT.
.. hook-end
.. function:: bool TARGET_CXX_LIBRARY_RTTI_COMDAT (void)
.. hook-start:TARGET_CXX_LIBRARY_RTTI_COMDAT
This hook returns true (the default) if the RTTI information for
the basic types which is defined in the C++ runtime should always
be COMDAT, false if it should not be COMDAT.
.. hook-end
.. function:: bool TARGET_CXX_USE_AEABI_ATEXIT (void)
.. hook-start:TARGET_CXX_USE_AEABI_ATEXIT
This hook returns true if ``__aeabi_atexit`` (as defined by the ARM EABI)
should be used to register static destructors when :option:`-fuse-cxa-atexit`
is in effect. The default is to return false to use ``__cxa_atexit``.
.. hook-end
.. function:: bool TARGET_CXX_USE_ATEXIT_FOR_CXA_ATEXIT (void)
.. hook-start:TARGET_CXX_USE_ATEXIT_FOR_CXA_ATEXIT
This hook returns true if the target ``atexit`` function can be used
in the same manner as ``__cxa_atexit`` to register C++ static
destructors. This requires that ``atexit`` -registered functions in
shared libraries are run in the correct order when the libraries are
unloaded. The default is to return false.
.. hook-end
.. function:: void TARGET_CXX_ADJUST_CLASS_AT_DEFINITION (tree type)
.. hook-start:TARGET_CXX_ADJUST_CLASS_AT_DEFINITION
:samp:`{type}` is a C++ class (i.e., RECORD_TYPE or UNION_TYPE) that has just
been defined. Use this hook to make adjustments to the class (eg, tweak
visibility or perform any other required target modifications).
.. hook-end
.. function:: tree TARGET_CXX_DECL_MANGLING_CONTEXT (const_tree decl)
.. hook-start:TARGET_CXX_DECL_MANGLING_CONTEXT
Return target-specific mangling context of :samp:`{decl}` or ``NULL_TREE``.
.. hook-end
.. include:: tm.rst.in
:start-after: [TARGET_CXX_DECL_MANGLING_CONTEXT]
:end-before: [TARGET_CXX_DECL_MANGLING_CONTEXT]

77
gcc/doc/gccint/target-macros/condition-code-status.rst
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@ -104,31 +104,10 @@ Representation of condition codes using registers
You should define this macro if and only if you define extra CC modes
in :samp:`{machine}-modes.def`.
.. function:: void TARGET_CANONICALIZE_COMPARISON (int *code, rtx *op0, rtx *op1, bool op0_preserve_value)
.. include:: tm.rst.in
:start-after: [TARGET_CANONICALIZE_COMPARISON]
:end-before: [TARGET_CANONICALIZE_COMPARISON]
.. hook-start:TARGET_CANONICALIZE_COMPARISON
On some machines not all possible comparisons are defined, but you can
convert an invalid comparison into a valid one. For example, the Alpha
does not have a ``GT`` comparison, but you can use an ``LT``
comparison instead and swap the order of the operands.
On such machines, implement this hook to do any required conversions.
:samp:`{code}` is the initial comparison code and :samp:`{op0}` and :samp:`{op1}`
are the left and right operands of the comparison, respectively. If
:samp:`{op0_preserve_value}` is ``true`` the implementation is not
allowed to change the value of :samp:`{op0}` since the value might be used
in RTXs which aren't comparisons. E.g. the implementation is not
allowed to swap operands in that case.
GCC will not assume that the comparison resulting from this macro is
valid but will see if the resulting insn matches a pattern in the
:samp:`md` file.
You need not to implement this hook if it would never change the
comparison code or operands.
.. hook-end
.. c:macro:: REVERSIBLE_CC_MODE (mode)
@ -163,48 +142,16 @@ Representation of condition codes using registers
((MODE) != CCFPmode ? reverse_condition (CODE) \
: reverse_condition_maybe_unordered (CODE))
.. function:: bool TARGET_FIXED_CONDITION_CODE_REGS (unsigned int *p1, unsigned int *p2)
.. include:: tm.rst.in
:start-after: [TARGET_FIXED_CONDITION_CODE_REGS]
:end-before: [TARGET_FIXED_CONDITION_CODE_REGS]
.. hook-start:TARGET_FIXED_CONDITION_CODE_REGS
On targets which use a hard
register rather than a pseudo-register to hold condition codes, the
regular CSE passes are often not able to identify cases in which the
hard register is set to a common value. Use this hook to enable a
small pass which optimizes such cases. This hook should return true
to enable this pass, and it should set the integers to which its
arguments point to the hard register numbers used for condition codes.
When there is only one such register, as is true on most systems, the
integer pointed to by :samp:`{p2}` should be set to
``INVALID_REGNUM``.
.. include:: tm.rst.in
:start-after: [TARGET_CC_MODES_COMPATIBLE]
:end-before: [TARGET_CC_MODES_COMPATIBLE]
The default version of this hook returns false.
.. hook-end
.. function:: machine_mode TARGET_CC_MODES_COMPATIBLE (machine_mode m1, machine_mode m2)
.. hook-start:TARGET_CC_MODES_COMPATIBLE
On targets which use multiple condition code modes in class
``MODE_CC``, it is sometimes the case that a comparison can be
validly done in more than one mode. On such a system, define this
target hook to take two mode arguments and to return a mode in which
both comparisons may be validly done. If there is no such mode,
return ``VOIDmode``.
The default version of this hook checks whether the modes are the
same. If they are, it returns that mode. If they are different, it
returns ``VOIDmode``.
.. hook-end
.. c:var:: unsigned int TARGET_FLAGS_REGNUM
.. hook-start:TARGET_FLAGS_REGNUM
If the target has a dedicated flags register, and it needs to use the
post-reload comparison elimination pass, or the delay slot filler pass,
then this value should be set appropriately.
.. hook-end
.. include:: tm.rst.in
:start-after: [TARGET_FLAGS_REGNUM]
:end-before: [TARGET_FLAGS_REGNUM]

102
gcc/doc/gccint/target-macros/controlling-debugging-information-format.rst
View File

@ -103,15 +103,10 @@ Here are macros for DWARF output.
prologue, or call ``dwarf2out_def_cfa`` and ``dwarf2out_reg_save``
as appropriate from ``TARGET_ASM_FUNCTION_PROLOGUE`` if you don't.
.. function:: int TARGET_DWARF_CALLING_CONVENTION (const_tree function)
.. include:: tm.rst.in
:start-after: [TARGET_DWARF_CALLING_CONVENTION]
:end-before: [TARGET_DWARF_CALLING_CONVENTION]
.. hook-start:TARGET_DWARF_CALLING_CONVENTION
Define this to enable the dwarf attribute ``DW_AT_calling_convention`` to
be emitted for each function. Instead of an integer return the enum
value for the ``DW_CC_`` tag.
.. hook-end
.. function:: int TARGET_DWARF_CALLING_CONVENTION (const_tree function)
@ -127,22 +122,10 @@ Here are macros for DWARF output.
exceptions are enabled, GCC will output this information not matter
how you define ``DWARF2_FRAME_INFO``.
.. function:: enum unwind_info_type TARGET_DEBUG_UNWIND_INFO (void)
.. include:: tm.rst.in
:start-after: [TARGET_DEBUG_UNWIND_INFO]
:end-before: [TARGET_DEBUG_UNWIND_INFO]
.. hook-start:TARGET_DEBUG_UNWIND_INFO
This hook defines the mechanism that will be used for describing frame
unwind information to the debugger. Normally the hook will return
``UI_DWARF2`` if DWARF 2 debug information is enabled, and
return ``UI_NONE`` otherwise.
A target may return ``UI_DWARF2`` even when DWARF 2 debug information
is disabled in order to always output DWARF 2 frame information.
A target may return ``UI_TARGET`` if it has ABI specified unwind tables.
This will suppress generation of the normal debug frame unwind information.
.. hook-end
.. c:macro:: DWARF2_ASM_LINE_DEBUG_INFO
@ -157,63 +140,30 @@ Here are macros for DWARF output.
user enables location views, the compiler may have to fallback to
internal line number tables.
.. function:: int TARGET_RESET_LOCATION_VIEW (rtx_insn *)
.. include:: tm.rst.in
:start-after: [TARGET_RESET_LOCATION_VIEW]
:end-before: [TARGET_RESET_LOCATION_VIEW]
.. hook-start:TARGET_RESET_LOCATION_VIEW
This hook, if defined, enables -ginternal-reset-location-views, and
uses its result to override cases in which the estimated min insn
length might be nonzero even when a PC advance (i.e., a view reset)
cannot be taken for granted.
.. include:: tm.rst.in
:start-after: [TARGET_WANT_DEBUG_PUB_SECTIONS]
:end-before: [TARGET_WANT_DEBUG_PUB_SECTIONS]
If the hook is defined, it must return a positive value to indicate
the insn definitely advances the PC, and so the view number can be
safely assumed to be reset; a negative value to mean the insn
definitely does not advance the PC, and os the view number must not
be reset; or zero to decide based on the estimated insn length.
If insn length is to be regarded as reliable, set the hook to
``hook_int_rtx_insn_0``.
.. include:: tm.rst.in
:start-after: [TARGET_DELAY_SCHED2]
:end-before: [TARGET_DELAY_SCHED2]
.. hook-end
.. c:var:: bool TARGET_WANT_DEBUG_PUB_SECTIONS
.. include:: tm.rst.in
:start-after: [TARGET_DELAY_VARTRACK]
:end-before: [TARGET_DELAY_VARTRACK]
.. hook-start:TARGET_WANT_DEBUG_PUB_SECTIONS
True if the ``.debug_pubtypes`` and ``.debug_pubnames`` sections
should be emitted. These sections are not used on most platforms, and
in particular GDB does not use them.
.. include:: tm.rst.in
:start-after: [TARGET_NO_REGISTER_ALLOCATION]
:end-before: [TARGET_NO_REGISTER_ALLOCATION]
.. hook-end
.. c:var:: bool TARGET_DELAY_SCHED2
.. hook-start:TARGET_DELAY_SCHED2
True if sched2 is not to be run at its normal place.
This usually means it will be run as part of machine-specific reorg.
.. hook-end
.. c:var:: bool TARGET_DELAY_VARTRACK
.. hook-start:TARGET_DELAY_VARTRACK
True if vartrack is not to be run at its normal place.
This usually means it will be run as part of machine-specific reorg.
.. hook-end
.. c:var:: bool TARGET_NO_REGISTER_ALLOCATION
.. hook-start:TARGET_NO_REGISTER_ALLOCATION
True if register allocation and the passes
following it should not be run. Usually true only for virtual assembler
targets.
.. hook-end
.. c:macro:: ASM_OUTPUT_DWARF_DELTA (stream, size, label1, label2)
@ -250,14 +200,10 @@ Here are macros for DWARF output.
is used on some systems to avoid garbage collecting a DWARF table which
is referenced by a function.
.. function:: void TARGET_ASM_OUTPUT_DWARF_DTPREL (FILE *file, int size, rtx x)
.. include:: tm.rst.in
:start-after: [TARGET_ASM_OUTPUT_DWARF_DTPREL]
:end-before: [TARGET_ASM_OUTPUT_DWARF_DTPREL]
.. hook-start:TARGET_ASM_OUTPUT_DWARF_DTPREL
If defined, this target hook is a function which outputs a DTP-relative
reference to the given TLS symbol of the specified size.
.. hook-end
.. _vms-debug:

12
gcc/doc/gccint/target-macros/controlling-the-compilation-driver-gcc.rst
View File

@ -291,16 +291,10 @@ You can control the compilation driver.
the effect you need. Overriding this macro may be avoidable by overriding
``LINK_GCC_C_SEQUENCE_SPEC`` instead.
.. c:var:: bool TARGET_ALWAYS_STRIP_DOTDOT
.. include:: tm.rst.in
:start-after: [TARGET_ALWAYS_STRIP_DOTDOT]
:end-before: [TARGET_ALWAYS_STRIP_DOTDOT]
.. hook-start:TARGET_ALWAYS_STRIP_DOTDOT
True if :samp:`..` components should always be removed from directory names
computed relative to GCC's internal directories, false (default) if such
components should be preserved and directory names containing them passed
to other tools such as the linker.
.. hook-end
.. c:macro:: MULTILIB_DEFAULTS

110
gcc/doc/gccint/target-macros/d-abi-parameters.rst
View File

@ -10,102 +10,46 @@
D ABI parameters
****************
.. function:: void TARGET_D_CPU_VERSIONS (void)
.. include:: tm.rst.in
:start-after: [TARGET_D_CPU_VERSIONS]
:end-before: [TARGET_D_CPU_VERSIONS]
.. hook-start:TARGET_D_CPU_VERSIONS
Declare all environmental version identifiers relating to the target CPU
using the function ``builtin_version``, which takes a string representing
the name of the version. Version identifiers predefined by this hook apply
to all modules that are being compiled and imported.
.. include:: tm.rst.in
:start-after: [TARGET_D_OS_VERSIONS]
:end-before: [TARGET_D_OS_VERSIONS]
.. hook-end
.. function:: void TARGET_D_OS_VERSIONS (void)
.. include:: tm.rst.in
:start-after: [TARGET_D_REGISTER_CPU_TARGET_INFO]
:end-before: [TARGET_D_REGISTER_CPU_TARGET_INFO]
.. hook-start:TARGET_D_OS_VERSIONS
Similarly to ``TARGET_D_CPU_VERSIONS``, but is used for versions
relating to the target operating system.
.. include:: tm.rst.in
:start-after: [TARGET_D_REGISTER_OS_TARGET_INFO]
:end-before: [TARGET_D_REGISTER_OS_TARGET_INFO]
.. hook-end
.. function:: void TARGET_D_REGISTER_CPU_TARGET_INFO (void)
.. include:: tm.rst.in
:start-after: [TARGET_D_MINFO_SECTION]
:end-before: [TARGET_D_MINFO_SECTION]
.. hook-start:TARGET_D_REGISTER_CPU_TARGET_INFO
Register all target information keys relating to the target CPU using the
function ``d_add_target_info_handlers``, which takes a
:samp:`struct d_target_info_spec` (defined in :samp:`d/d-target.h`). The keys
added by this hook are made available at compile time by the
``__traits(getTargetInfo)`` extension, the result is an expression
describing the requested target information.
.. include:: tm.rst.in
:start-after: [TARGET_D_MINFO_SECTION_START]
:end-before: [TARGET_D_MINFO_SECTION_START]
.. hook-end
.. function:: void TARGET_D_REGISTER_OS_TARGET_INFO (void)
.. include:: tm.rst.in
:start-after: [TARGET_D_MINFO_SECTION_END]
:end-before: [TARGET_D_MINFO_SECTION_END]
.. hook-start:TARGET_D_REGISTER_OS_TARGET_INFO
Same as ``TARGET_D_CPU_TARGET_INFO``, but is used for keys relating to
the target operating system.
.. include:: tm.rst.in
:start-after: [TARGET_D_HAS_STDCALL_CONVENTION]
:end-before: [TARGET_D_HAS_STDCALL_CONVENTION]
.. hook-end
.. c:var:: const char * TARGET_D_MINFO_SECTION
.. hook-start:TARGET_D_MINFO_SECTION
Contains the name of the section in which module info references should be
placed. By default, the compiler puts all module info symbols in the
``"minfo"`` section. Define this macro to override the string if a
different section name should be used. This section is expected to be
bracketed by two symbols ``TARGET_D_MINFO_SECTION_START`` and
``TARGET_D_MINFO_SECTION_END`` to indicate the start and end address of
the section, so that the runtime library can collect all modules for each
loaded shared library and executable. Setting the value to ``NULL``
disables the use of sections for storing module info altogether.
.. hook-end
.. c:var:: const char * TARGET_D_MINFO_SECTION_START
.. hook-start:TARGET_D_MINFO_SECTION_START
If ``TARGET_D_MINFO_SECTION`` is defined, then this must also be defined
as the name of the symbol indicating the start address of the module info
section
.. hook-end
.. c:var:: const char * TARGET_D_MINFO_SECTION_END
.. hook-start:TARGET_D_MINFO_SECTION_END
If ``TARGET_D_MINFO_SECTION`` is defined, then this must also be defined
as the name of the symbol indicating the end address of the module info
section
.. hook-end
.. function:: bool TARGET_D_HAS_STDCALL_CONVENTION (unsigned int *link_system, unsigned int *link_windows)
.. hook-start:TARGET_D_HAS_STDCALL_CONVENTION
Returns ``true`` if the target supports the stdcall calling convention.
The hook should also set :samp:`{link_system}` to ``1`` if the ``stdcall``
attribute should be applied to functions with ``extern(System)`` linkage,
and :samp:`{link_windows}` to ``1`` to apply ``stdcall`` to functions with
``extern(Windows)`` linkage.
.. hook-end
.. c:var:: bool TARGET_D_TEMPLATES_ALWAYS_COMDAT
.. hook-start:TARGET_D_TEMPLATES_ALWAYS_COMDAT
This flag is true if instantiated functions and variables are always COMDAT
if they have external linkage. If this flag is false, then instantiated
decls will be emitted as weak symbols. The default is ``false``.
.. hook-end
.. include:: tm.rst.in
:start-after: [TARGET_D_TEMPLATES_ALWAYS_COMDAT]
:end-before: [TARGET_D_TEMPLATES_ALWAYS_COMDAT]

318
gcc/doc/gccint/target-macros/defining-target-specific-uses-of-attribute.rst
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@ -14,100 +14,40 @@ Target-specific attributes may be defined for functions, data and types.
These are described using the following target hooks; they also need to
be documented in :samp:`extend.texi`.
.. c:var:: const struct attribute_spec * TARGET_ATTRIBUTE_TABLE
.. include:: tm.rst.in
:start-after: [TARGET_ATTRIBUTE_TABLE]
:end-before: [TARGET_ATTRIBUTE_TABLE]
.. hook-start:TARGET_ATTRIBUTE_TABLE
If defined, this target hook points to an array of :samp:`struct
attribute_spec` (defined in :samp:`tree-core.h`) specifying the machine
specific attributes for this target and some of the restrictions on the
entities to which these attributes are applied and the arguments they
take.
.. include:: tm.rst.in
:start-after: [TARGET_ATTRIBUTE_TAKES_IDENTIFIER_P]
:end-before: [TARGET_ATTRIBUTE_TAKES_IDENTIFIER_P]
.. hook-end
.. function:: bool TARGET_ATTRIBUTE_TAKES_IDENTIFIER_P (const_tree name)
.. include:: tm.rst.in
:start-after: [TARGET_COMP_TYPE_ATTRIBUTES]
:end-before: [TARGET_COMP_TYPE_ATTRIBUTES]
.. hook-start:TARGET_ATTRIBUTE_TAKES_IDENTIFIER_P
If defined, this target hook is a function which returns true if the
machine-specific attribute named :samp:`{name}` expects an identifier
given as its first argument to be passed on as a plain identifier, not
subjected to name lookup. If this is not defined, the default is
false for all machine-specific attributes.
.. include:: tm.rst.in
:start-after: [TARGET_SET_DEFAULT_TYPE_ATTRIBUTES]
:end-before: [TARGET_SET_DEFAULT_TYPE_ATTRIBUTES]
.. hook-end
.. function:: int TARGET_COMP_TYPE_ATTRIBUTES (const_tree type1, const_tree type2)
.. include:: tm.rst.in
:start-after: [TARGET_MERGE_TYPE_ATTRIBUTES]
:end-before: [TARGET_MERGE_TYPE_ATTRIBUTES]
.. hook-start:TARGET_COMP_TYPE_ATTRIBUTES
If defined, this target hook is a function which returns zero if the attributes on
:samp:`{type1}` and :samp:`{type2}` are incompatible, one if they are compatible,
and two if they are nearly compatible (which causes a warning to be
generated). If this is not defined, machine-specific attributes are
supposed always to be compatible.
.. include:: tm.rst.in
:start-after: [TARGET_MERGE_DECL_ATTRIBUTES]
:end-before: [TARGET_MERGE_DECL_ATTRIBUTES]
.. hook-end
.. function:: void TARGET_SET_DEFAULT_TYPE_ATTRIBUTES (tree type)
.. include:: tm.rst.in
:start-after: [TARGET_VALID_DLLIMPORT_ATTRIBUTE_P]
:end-before: [TARGET_VALID_DLLIMPORT_ATTRIBUTE_P]
.. hook-start:TARGET_SET_DEFAULT_TYPE_ATTRIBUTES
If defined, this target hook is a function which assigns default attributes to
the newly defined :samp:`{type}`.
.. hook-end
.. function:: tree TARGET_MERGE_TYPE_ATTRIBUTES (tree type1, tree type2)
.. hook-start:TARGET_MERGE_TYPE_ATTRIBUTES
Define this target hook if the merging of type attributes needs special
handling. If defined, the result is a list of the combined
``TYPE_ATTRIBUTES`` of :samp:`{type1}` and :samp:`{type2}`. It is assumed
that ``comptypes`` has already been called and returned 1. This
function may call ``merge_attributes`` to handle machine-independent
merging.
.. hook-end
.. function:: tree TARGET_MERGE_DECL_ATTRIBUTES (tree olddecl, tree newdecl)
.. hook-start:TARGET_MERGE_DECL_ATTRIBUTES
Define this target hook if the merging of decl attributes needs special
handling. If defined, the result is a list of the combined
``DECL_ATTRIBUTES`` of :samp:`{olddecl}` and :samp:`{newdecl}`.
:samp:`{newdecl}` is a duplicate declaration of :samp:`{olddecl}`. Examples of
when this is needed are when one attribute overrides another, or when an
attribute is nullified by a subsequent definition. This function may
call ``merge_attributes`` to handle machine-independent merging.
.. index:: TARGET_DLLIMPORT_DECL_ATTRIBUTES
If the only target-specific handling you require is :samp:`dllimport`
for Microsoft Windows targets, you should define the macro
``TARGET_DLLIMPORT_DECL_ATTRIBUTES`` to ``1``. The compiler
will then define a function called
``merge_dllimport_decl_attributes`` which can then be defined as
the expansion of ``TARGET_MERGE_DECL_ATTRIBUTES``. You can also
add ``handle_dll_attribute`` in the attribute table for your port
to perform initial processing of the :samp:`dllimport` and
:samp:`dllexport` attributes. This is done in :samp:`i386/cygwin.h` and
:samp:`i386/i386.cc`, for example.
.. hook-end
.. function:: bool TARGET_VALID_DLLIMPORT_ATTRIBUTE_P (const_tree decl)
.. hook-start:TARGET_VALID_DLLIMPORT_ATTRIBUTE_P
:samp:`{decl}` is a variable or function with ``__attribute__((dllimport))``
specified. Use this hook if the target needs to add extra validation
checks to ``handle_dll_attribute``.
.. hook-end
.. c:macro:: TARGET_DECLSPEC
@ -118,202 +58,76 @@ be documented in :samp:`extend.texi`.
of ``__declspec`` is via a built-in macro, but you should not rely
on this implementation detail.
.. function:: void TARGET_INSERT_ATTRIBUTES (tree node, tree *attr_ptr)
.. include:: tm.rst.in
:start-after: [TARGET_INSERT_ATTRIBUTES]
:end-before: [TARGET_INSERT_ATTRIBUTES]
.. hook-start:TARGET_INSERT_ATTRIBUTES
Define this target hook if you want to be able to add attributes to a decl
when it is being created. This is normally useful for back ends which
wish to implement a pragma by using the attributes which correspond to
the pragma's effect. The :samp:`{node}` argument is the decl which is being
created. The :samp:`{attr_ptr}` argument is a pointer to the attribute list
for this decl. The list itself should not be modified, since it may be
shared with other decls, but attributes may be chained on the head of
the list and ``*attr_ptr`` modified to point to the new
attributes, or a copy of the list may be made if further changes are
needed.
.. include:: tm.rst.in
:start-after: [TARGET_HANDLE_GENERIC_ATTRIBUTE]
:end-before: [TARGET_HANDLE_GENERIC_ATTRIBUTE]
.. hook-end
.. function:: tree TARGET_HANDLE_GENERIC_ATTRIBUTE (tree *node, tree name, tree args, int flags, bool *no_add_attrs)
.. include:: tm.rst.in
:start-after: [TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P]
:end-before: [TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P]
.. hook-start:TARGET_HANDLE_GENERIC_ATTRIBUTE
Define this target hook if you want to be able to perform additional
target-specific processing of an attribute which is handled generically
by a front end. The arguments are the same as those which are passed to
attribute handlers. So far this only affects the :samp:`{noinit}` and
:samp:`{section}` attribute.
.. include:: tm.rst.in
:start-after: [TARGET_OPTION_VALID_ATTRIBUTE_P]
:end-before: [TARGET_OPTION_VALID_ATTRIBUTE_P]
.. hook-end
.. function:: bool TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P (const_tree fndecl)
.. include:: tm.rst.in
:start-after: [TARGET_OPTION_SAVE]
:end-before: [TARGET_OPTION_SAVE]
.. hook-start:TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P
.. index:: inlining
.. include:: tm.rst.in
:start-after: [TARGET_OPTION_RESTORE]
:end-before: [TARGET_OPTION_RESTORE]
This target hook returns ``true`` if it is OK to inline :samp:`{fndecl}`
into the current function, despite its having target-specific
attributes, ``false`` otherwise. By default, if a function has a
target specific attribute attached to it, it will not be inlined.
.. hook-end
.. include:: tm.rst.in
:start-after: [TARGET_OPTION_POST_STREAM_IN]
:end-before: [TARGET_OPTION_POST_STREAM_IN]
.. function:: bool TARGET_OPTION_VALID_ATTRIBUTE_P (tree fndecl, tree name, tree args, int flags)
.. hook-start:TARGET_OPTION_VALID_ATTRIBUTE_P
.. include:: tm.rst.in
:start-after: [TARGET_OPTION_PRINT]
:end-before: [TARGET_OPTION_PRINT]
This hook is called to parse ``attribute(target("..."))``, which
allows setting target-specific options on individual functions.
These function-specific options may differ
from the options specified on the command line. The hook should return
``true`` if the options are valid.
The hook should set the ``DECL_FUNCTION_SPECIFIC_TARGET`` field in
the function declaration to hold a pointer to a target-specific
``struct cl_target_option`` structure.
.. include:: tm.rst.in
:start-after: [TARGET_OPTION_PRAGMA_PARSE]
:end-before: [TARGET_OPTION_PRAGMA_PARSE]
.. hook-end
.. function:: void TARGET_OPTION_SAVE (struct cl_target_option *ptr, struct gcc_options *opts, struct gcc_options *opts_set)
.. include:: tm.rst.in
:start-after: [TARGET_OPTION_OVERRIDE]
:end-before: [TARGET_OPTION_OVERRIDE]
.. hook-start:TARGET_OPTION_SAVE
This hook is called to save any additional target-specific information
in the ``struct cl_target_option`` structure for function-specific
options from the ``struct gcc_options`` structure.
See :ref:`option-file-format`.
.. include:: tm.rst.in
:start-after: [TARGET_OPTION_FUNCTION_VERSIONS]
:end-before: [TARGET_OPTION_FUNCTION_VERSIONS]
.. hook-end
.. function:: void TARGET_OPTION_RESTORE (struct gcc_options *opts, struct gcc_options *opts_set, struct cl_target_option *ptr)
.. include:: tm.rst.in
:start-after: [TARGET_CAN_INLINE_P]
:end-before: [TARGET_CAN_INLINE_P]
.. hook-start:TARGET_OPTION_RESTORE
This hook is called to restore any additional target-specific
information in the ``struct cl_target_option`` structure for
function-specific options to the ``struct gcc_options`` structure.
.. include:: tm.rst.in
:start-after: [TARGET_UPDATE_IPA_FN_TARGET_INFO]
:end-before: [TARGET_UPDATE_IPA_FN_TARGET_INFO]
.. hook-end
.. function:: void TARGET_OPTION_POST_STREAM_IN (struct cl_target_option *ptr)
.. include:: tm.rst.in
:start-after: [TARGET_NEED_IPA_FN_TARGET_INFO]
:end-before: [TARGET_NEED_IPA_FN_TARGET_INFO]
.. hook-start:TARGET_OPTION_POST_STREAM_IN
This hook is called to update target-specific information in the
``struct cl_target_option`` structure after it is streamed in from
LTO bytecode.
.. hook-end
.. function:: void TARGET_OPTION_PRINT (FILE *file, int indent, struct cl_target_option *ptr)
.. hook-start:TARGET_OPTION_PRINT
This hook is called to print any additional target-specific
information in the ``struct cl_target_option`` structure for
function-specific options.
.. hook-end
.. function:: bool TARGET_OPTION_PRAGMA_PARSE (tree args, tree pop_target)
.. hook-start:TARGET_OPTION_PRAGMA_PARSE
This target hook parses the options for ``#pragma GCC target``, which
sets the target-specific options for functions that occur later in the
input stream. The options accepted should be the same as those handled by the
``TARGET_OPTION_VALID_ATTRIBUTE_P`` hook.
.. hook-end
.. function:: void TARGET_OPTION_OVERRIDE (void)
.. hook-start:TARGET_OPTION_OVERRIDE
Sometimes certain combinations of command options do not make sense on
a particular target machine. You can override the hook
``TARGET_OPTION_OVERRIDE`` to take account of this. This hooks is called
once just after all the command options have been parsed.
Don't use this hook to turn on various extra optimizations for
:option:`-O`. That is what ``TARGET_OPTION_OPTIMIZATION`` is for.
If you need to do something whenever the optimization level is
changed via the optimize attribute or pragma, see
``TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE``
.. hook-end
.. function:: bool TARGET_OPTION_FUNCTION_VERSIONS (tree decl1, tree decl2)
.. hook-start:TARGET_OPTION_FUNCTION_VERSIONS
This target hook returns ``true`` if :samp:`{DECL1}` and :samp:`{DECL2}` are
versions of the same function. :samp:`{DECL1}` and :samp:`{DECL2}` are function
versions if and only if they have the same function signature and
different target specific attributes, that is, they are compiled for
different target machines.
.. hook-end
.. function:: bool TARGET_CAN_INLINE_P (tree caller, tree callee)
.. hook-start:TARGET_CAN_INLINE_P
This target hook returns ``false`` if the :samp:`{caller}` function
cannot inline :samp:`{callee}`, based on target specific information. By
default, inlining is not allowed if the callee function has function
specific target options and the caller does not use the same options.
.. hook-end
.. function:: bool TARGET_UPDATE_IPA_FN_TARGET_INFO (unsigned int& info, const gimple* stmt)
.. hook-start:TARGET_UPDATE_IPA_FN_TARGET_INFO
Allow target to analyze all gimple statements for the given function to
record and update some target specific information for inlining. A typical
example is that a caller with one isa feature disabled is normally not
allowed to inline a callee with that same isa feature enabled even which is
attributed by always_inline, but with the conservative analysis on all
statements of the callee if we are able to guarantee the callee does not
exploit any instructions from the mismatch isa feature, it would be safe to
allow the caller to inline the callee.
:samp:`{info}` is one ``unsigned int`` value to record information in which
one set bit indicates one corresponding feature is detected in the analysis,
:samp:`{stmt}` is the statement being analyzed. Return true if target still
need to analyze the subsequent statements, otherwise return false to stop
subsequent analysis.
The default version of this hook returns false.
.. hook-end
.. function:: bool TARGET_NEED_IPA_FN_TARGET_INFO (const_tree decl, unsigned int& info)
.. hook-start:TARGET_NEED_IPA_FN_TARGET_INFO
Allow target to check early whether it is necessary to analyze all gimple
statements in the given function to update target specific information for
inlining. See hook ``update_ipa_fn_target_info`` for usage example of
target specific information. This hook is expected to be invoked ahead of
the iterating with hook ``update_ipa_fn_target_info``.
:samp:`{decl}` is the function being analyzed, :samp:`{info}` is the same as what
in hook ``update_ipa_fn_target_info``, target can do one time update
into :samp:`{info}` without iterating for some case. Return true if target
decides to analyze all gimple statements to collect information, otherwise
return false.
The default version of this hook returns false.
.. hook-end
.. function:: void TARGET_RELAYOUT_FUNCTION (tree fndecl)
.. hook-start:TARGET_RELAYOUT_FUNCTION
This target hook fixes function :samp:`{fndecl}` after attributes are processed.
Default does nothing. On ARM, the default function's alignment is updated
with the attribute target.
.. hook-end
.. include:: tm.rst.in
:start-after: [TARGET_RELAYOUT_FUNCTION]
:end-before: [TARGET_RELAYOUT_FUNCTION]

91
gcc/doc/gccint/target-macros/defining-the-output-assembler-language/assembler-commands-for-exception-regions.rst
View File

@ -54,11 +54,10 @@ region.
``INCOMING_RETURN_ADDR_RTX`` and ``OBJECT_FORMAT_ELF``),
GCC will provide a default definition of 1.
.. function:: enum unwind_info_type TARGET_EXCEPT_UNWIND_INFO (struct gcc_options *opts)
.. include:: ../tm.rst.in
:start-after: [TARGET_EXCEPT_UNWIND_INFO]
:end-before: [TARGET_EXCEPT_UNWIND_INFO]
.. hook-start:TARGET_EXCEPT_UNWIND_INFO
.. hook-end
This hook defines the mechanism that will be used for exception handling
by the target. If the target has ABI specified unwind tables, the hook
@ -84,11 +83,10 @@ region.
``DWARF2_UNWIND_INFO`` depends on command-line options, the target
must define this hook so that :samp:`{opts}` is used correctly.
.. c:var:: bool TARGET_UNWIND_TABLES_DEFAULT
.. include:: ../tm.rst.in
:start-after: [TARGET_UNWIND_TABLES_DEFAULT]
:end-before: [TARGET_UNWIND_TABLES_DEFAULT]
.. hook-start:TARGET_UNWIND_TABLES_DEFAULT
.. hook-end
This variable should be set to ``true`` if the target ABI requires unwinding
tables even when exceptions are not used. It must not be modified by
@ -117,72 +115,31 @@ region.
minimum alignment otherwise. See :ref:`dwarf`. Only applicable if
the target supports DWARF 2 frame unwind information.
.. c:var:: bool TARGET_TERMINATE_DW2_EH_FRAME_INFO
.. include:: ../tm.rst.in
:start-after: [TARGET_TERMINATE_DW2_EH_FRAME_INFO]
:end-before: [TARGET_TERMINATE_DW2_EH_FRAME_INFO]
.. hook-start:TARGET_TERMINATE_DW2_EH_FRAME_INFO
Contains the value true if the target should add a zero word onto the
end of a Dwarf-2 frame info section when used for exception handling.
Default value is false if ``EH_FRAME_SECTION_NAME`` is defined, and
true otherwise.
.. include:: ../tm.rst.in
:start-after: [TARGET_DWARF_REGISTER_SPAN]
:end-before: [TARGET_DWARF_REGISTER_SPAN]
.. hook-end
.. function:: rtx TARGET_DWARF_REGISTER_SPAN (rtx reg)
.. include:: ../tm.rst.in
:start-after: [TARGET_DWARF_FRAME_REG_MODE]
:end-before: [TARGET_DWARF_FRAME_REG_MODE]
.. hook-start:TARGET_DWARF_REGISTER_SPAN
Given a register, this hook should return a parallel of registers to
represent where to find the register pieces. Define this hook if the
register and its mode are represented in Dwarf in non-contiguous
locations, or if the register should be represented in more than one
register in Dwarf. Otherwise, this hook should return ``NULL_RTX``.
If not defined, the default is to return ``NULL_RTX``.
.. include:: ../tm.rst.in
:start-after: [TARGET_INIT_DWARF_REG_SIZES_EXTRA]
:end-before: [TARGET_INIT_DWARF_REG_SIZES_EXTRA]
.. hook-end
.. function:: machine_mode TARGET_DWARF_FRAME_REG_MODE (int regno)
.. include:: ../tm.rst.in
:start-after: [TARGET_ASM_TTYPE]
:end-before: [TARGET_ASM_TTYPE]
.. hook-start:TARGET_DWARF_FRAME_REG_MODE
Given a register, this hook should return the mode which the
corresponding Dwarf frame register should have. This is normally
used to return a smaller mode than the raw mode to prevent call
clobbered parts of a register altering the frame register size
.. hook-end
.. function:: void TARGET_INIT_DWARF_REG_SIZES_EXTRA (tree address)
.. hook-start:TARGET_INIT_DWARF_REG_SIZES_EXTRA
If some registers are represented in Dwarf-2 unwind information in
multiple pieces, define this hook to fill in information about the
sizes of those pieces in the table used by the unwinder at runtime.
It will be called by ``expand_builtin_init_dwarf_reg_sizes`` after
filling in a single size corresponding to each hard register;
:samp:`{address}` is the address of the table.
.. hook-end
.. function:: bool TARGET_ASM_TTYPE (rtx sym)
.. hook-start:TARGET_ASM_TTYPE
This hook is used to output a reference from a frame unwinding table to
the type_info object identified by :samp:`{sym}`. It should return ``true``
if the reference was output. Returning ``false`` will cause the
reference to be output using the normal Dwarf2 routines.
.. hook-end
.. c:var:: bool TARGET_ARM_EABI_UNWINDER
.. hook-start:TARGET_ARM_EABI_UNWINDER
This flag should be set to ``true`` on targets that use an ARM EABI
based unwinding library, and ``false`` on other targets. This effects
the format of unwinding tables, and how the unwinder in entered after
running a cleanup. The default is ``false``.
.. hook-end
.. include:: ../tm.rst.in
:start-after: [TARGET_ARM_EABI_UNWINDER]
:end-before: [TARGET_ARM_EABI_UNWINDER]

54
gcc/doc/gccint/target-macros/defining-the-output-assembler-language/macros-controlling-initialization-routines.rst
View File

@ -71,55 +71,25 @@ and termination functions:
of objects. If zero, the compiler will issue an error message upon
encountering an ``init_priority`` attribute.
.. c:var:: bool TARGET_HAVE_CTORS_DTORS
.. include:: ../tm.rst.in
:start-after: [TARGET_HAVE_CTORS_DTORS]
:end-before: [TARGET_HAVE_CTORS_DTORS]
.. hook-start:TARGET_HAVE_CTORS_DTORS
This value is true if the target supports some 'native' method of
collecting constructors and destructors to be run at startup and exit.
It is false if we must use :command:`collect2`.
.. include:: ../tm.rst.in
:start-after: [TARGET_DTORS_FROM_CXA_ATEXIT]
:end-before: [TARGET_DTORS_FROM_CXA_ATEXIT]
.. hook-end
.. c:var:: bool TARGET_DTORS_FROM_CXA_ATEXIT
.. include:: ../tm.rst.in
:start-after: [TARGET_ASM_CONSTRUCTOR]
:end-before: [TARGET_ASM_CONSTRUCTOR]
.. hook-start:TARGET_DTORS_FROM_CXA_ATEXIT
This value is true if the target wants destructors to be queued to be
run from __cxa_atexit. If this is the case then, for each priority level,
a new constructor will be entered that registers the destructors for that
level with __cxa_atexit (and there will be no destructors emitted).
It is false the method implied by ``have_ctors_dtors`` is used.
.. include:: ../tm.rst.in
:start-after: [TARGET_ASM_DESTRUCTOR]
:end-before: [TARGET_ASM_DESTRUCTOR]
.. hook-end
.. function:: void TARGET_ASM_CONSTRUCTOR (rtx symbol, int priority)
.. hook-start:TARGET_ASM_CONSTRUCTOR
If defined, a function that outputs assembler code to arrange to call
the function referenced by :samp:`{symbol}` at initialization time.
Assume that :samp:`{symbol}` is a ``SYMBOL_REF`` for a function taking
no arguments and with no return value. If the target supports initialization
priorities, :samp:`{priority}` is a value between 0 and ``MAX_INIT_PRIORITY`` ;
otherwise it must be ``DEFAULT_INIT_PRIORITY``.
If this macro is not defined by the target, a suitable default will
be chosen if (1) the target supports arbitrary section names, (2) the
target defines ``CTORS_SECTION_ASM_OP``, or (3) ``USE_COLLECT2``
is not defined.
.. hook-end
.. function:: void TARGET_ASM_DESTRUCTOR (rtx symbol, int priority)
.. hook-start:TARGET_ASM_DESTRUCTOR
This is like ``TARGET_ASM_CONSTRUCTOR`` but used for termination
functions rather than initialization functions.
.. hook-end
If ``TARGET_HAVE_CTORS_DTORS`` is true, the initialization routine
generated for the generated object file will have static linkage.

126
gcc/doc/gccint/target-macros/defining-the-output-assembler-language/output-and-generation-of-labels.rst
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@ -199,23 +199,10 @@ This is about outputting labels.
You may wish to use ``ASM_OUTPUT_TYPE_DIRECTIVE`` and/or
``ASM_OUTPUT_SIZE_DIRECTIVE`` in the definition of this macro.
.. function:: void TARGET_ASM_DECLARE_CONSTANT_NAME (FILE *file, const char *name, const_tree expr, HOST_WIDE_INT size)
.. include:: ../tm.rst.in
:start-after: [TARGET_ASM_DECLARE_CONSTANT_NAME]
:end-before: [TARGET_ASM_DECLARE_CONSTANT_NAME]
.. hook-start:TARGET_ASM_DECLARE_CONSTANT_NAME
A target hook to output to the stdio stream :samp:`{file}` any text necessary
for declaring the name :samp:`{name}` of a constant which is being defined. This
target hook is responsible for outputting the label definition (perhaps using
``assemble_label``). The argument :samp:`{exp}` is the value of the constant,
and :samp:`{size}` is the size of the constant in bytes. The :samp:`{name}`
will be an internal label.
The default version of this target hook, define the :samp:`{name}` in the
usual manner as a label (by means of ``assemble_label``).
You may wish to use ``ASM_OUTPUT_TYPE_DIRECTIVE`` in this target hook.
.. hook-end
.. c:macro:: ASM_DECLARE_REGISTER_GLOBAL (stream, decl, regno, name)
@ -240,41 +227,20 @@ This is about outputting labels.
You may wish to use ``ASM_OUTPUT_SIZE_DIRECTIVE`` and/or
``ASM_OUTPUT_MEASURED_SIZE`` in the definition of this macro.
.. function:: void TARGET_ASM_GLOBALIZE_LABEL (FILE *stream, const char *name)
.. include:: ../tm.rst.in
:start-after: [TARGET_ASM_GLOBALIZE_LABEL]
:end-before: [TARGET_ASM_GLOBALIZE_LABEL]
.. hook-start:TARGET_ASM_GLOBALIZE_LABEL
This target hook is a function to output to the stdio stream
:samp:`{stream}` some commands that will make the label :samp:`{name}` global;
that is, available for reference from other files.
.. include:: ../tm.rst.in
:start-after: [TARGET_ASM_GLOBALIZE_DECL_NAME]
:end-before: [TARGET_ASM_GLOBALIZE_DECL_NAME]
The default implementation relies on a proper definition of
``GLOBAL_ASM_OP``.
.. hook-end
.. include:: ../tm.rst.in
:start-after: [TARGET_ASM_ASSEMBLE_UNDEFINED_DECL]
:end-before: [TARGET_ASM_ASSEMBLE_UNDEFINED_DECL]
.. function:: void TARGET_ASM_GLOBALIZE_DECL_NAME (FILE *stream, tree decl)
.. hook-start:TARGET_ASM_GLOBALIZE_DECL_NAME
This target hook is a function to output to the stdio stream
:samp:`{stream}` some commands that will make the name associated with :samp:`{decl}`
global; that is, available for reference from other files.
The default implementation uses the TARGET_ASM_GLOBALIZE_LABEL target hook.
.. hook-end
.. function:: void TARGET_ASM_ASSEMBLE_UNDEFINED_DECL (FILE *stream, const char *name, const_tree decl)
.. hook-start:TARGET_ASM_ASSEMBLE_UNDEFINED_DECL
This target hook is a function to output to the stdio stream
:samp:`{stream}` some commands that will declare the name associated with
:samp:`{decl}` which is not defined in the current translation unit. Most
assemblers do not require anything to be output in this case.
.. hook-end
.. c:macro:: ASM_WEAKEN_LABEL (stream, name)
@ -345,15 +311,10 @@ This is about outputting labels.
setting the ``DECL_ONE_ONLY`` flag is enough to mark a declaration to
be emitted as one-only.
.. function:: void TARGET_ASM_ASSEMBLE_VISIBILITY (tree decl, int visibility)
.. include:: ../tm.rst.in
:start-after: [TARGET_ASM_ASSEMBLE_VISIBILITY]
:end-before: [TARGET_ASM_ASSEMBLE_VISIBILITY]
.. hook-start:TARGET_ASM_ASSEMBLE_VISIBILITY
This target hook is a function to output to :samp:`{asm_out_file}` some
commands that will make the symbol(s) associated with :samp:`{decl}` have
hidden, protected or internal visibility as specified by :samp:`{visibility}`.
.. hook-end
.. c:macro:: TARGET_WEAK_NOT_IN_ARCHIVE_TOC
@ -385,25 +346,15 @@ This is about outputting labels.
This macro need not be defined if it does not need to output anything.
The GNU assembler and most Unix assemblers don't require anything.
.. function:: void TARGET_ASM_EXTERNAL_LIBCALL (rtx symref)
.. include:: ../tm.rst.in
:start-after: [TARGET_ASM_EXTERNAL_LIBCALL]
:end-before: [TARGET_ASM_EXTERNAL_LIBCALL]
.. hook-start:TARGET_ASM_EXTERNAL_LIBCALL
This target hook is a function to output to :samp:`{asm_out_file}` an assembler
pseudo-op to declare a library function name external. The name of the
library function is given by :samp:`{symref}`, which is a ``symbol_ref``.
.. include:: ../tm.rst.in
:start-after: [TARGET_ASM_MARK_DECL_PRESERVED]
:end-before: [TARGET_ASM_MARK_DECL_PRESERVED]
.. hook-end
.. function:: void TARGET_ASM_MARK_DECL_PRESERVED (const char *symbol)
.. hook-start:TARGET_ASM_MARK_DECL_PRESERVED
This target hook is a function to output to :samp:`{asm_out_file}` an assembler
directive to annotate :samp:`{symbol}` as used. The Darwin target uses the
.no_dead_code_strip directive.
.. hook-end
.. c:macro:: ASM_OUTPUT_LABELREF (stream, name)
@ -413,17 +364,10 @@ This is about outputting labels.
is customary on your operating system, as it is in most Berkeley Unix
systems. This macro is used in ``assemble_name``.
.. function:: tree TARGET_MANGLE_ASSEMBLER_NAME (const char *name)
.. include:: ../tm.rst.in
:start-after: [TARGET_MANGLE_ASSEMBLER_NAME]
:end-before: [TARGET_MANGLE_ASSEMBLER_NAME]
.. hook-start:TARGET_MANGLE_ASSEMBLER_NAME
Given a symbol :samp:`{name}`, perform same mangling as ``varasm.cc`` 's
``assemble_name``, but in memory rather than to a file stream, returning
result as an ``IDENTIFIER_NODE``. Required for correct LTO symtabs. The
default implementation calls the ``TARGET_STRIP_NAME_ENCODING`` hook and
then prepends the ``USER_LABEL_PREFIX``, if any.
.. hook-end
.. c:macro:: ASM_OUTPUT_SYMBOL_REF (stream, sym)
@ -443,26 +387,10 @@ This is about outputting labels.
when it is necessary to output a label differently when its address is
being taken.
.. function:: void TARGET_ASM_INTERNAL_LABEL (FILE *stream, const char *prefix, unsigned long labelno)
.. include:: ../tm.rst.in
:start-after: [TARGET_ASM_INTERNAL_LABEL]
:end-before: [TARGET_ASM_INTERNAL_LABEL]
.. hook-start:TARGET_ASM_INTERNAL_LABEL
A function to output to the stdio stream :samp:`{stream}` a label whose
name is made from the string :samp:`{prefix}` and the number :samp:`{labelno}`.
It is absolutely essential that these labels be distinct from the labels
used for user-level functions and variables. Otherwise, certain programs
will have name conflicts with internal labels.
It is desirable to exclude internal labels from the symbol table of the
object file. Most assemblers have a naming convention for labels that
should be excluded; on many systems, the letter :samp:`L` at the
beginning of a label has this effect. You should find out what
convention your system uses, and follow it.
The default version of this function utilizes ``ASM_GENERATE_INTERNAL_LABEL``.
.. hook-end
.. c:macro:: ASM_OUTPUT_DEBUG_LABEL (stream, prefix, num)

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@ -91,22 +91,10 @@ This describes assembler instruction output.
If this macro is not defined, it is equivalent to a null statement.
.. function:: void TARGET_ASM_FINAL_POSTSCAN_INSN (FILE *file, rtx_insn *insn, rtx *opvec, int noperands)
.. include:: ../tm.rst.in
:start-after: [TARGET_ASM_FINAL_POSTSCAN_INSN]
:end-before: [TARGET_ASM_FINAL_POSTSCAN_INSN]
.. hook-start:TARGET_ASM_FINAL_POSTSCAN_INSN
If defined, this target hook is a function which is executed just after the
output of assembler code for :samp:`{insn}`, to change the mode of the assembler
if necessary.
Here the argument :samp:`{opvec}` is the vector containing the operands
extracted from :samp:`{insn}`, and :samp:`{noperands}` is the number of
elements of the vector which contain meaningful data for this insn.
The contents of this vector are what was used to convert the insn
template into assembler code, so you can change the assembler mode
by checking the contents of the vector.
.. hook-end
.. c:macro:: PRINT_OPERAND (stream, x, code)

73
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@ -8,63 +8,25 @@
Output of Data
^^^^^^^^^^^^^^
.. c:var:: const char * TARGET_ASM_BYTE_OP
.. include:: ../tm.rst.in
:start-after: [TARGET_ASM_BYTE_OP]
:end-before: [TARGET_ASM_BYTE_OP]
.. hook-start:TARGET_ASM_BYTE_OP
These hooks specify assembly directives for creating certain kinds
of integer object. The ``TARGET_ASM_BYTE_OP`` directive creates a
byte-sized object, the ``TARGET_ASM_ALIGNED_HI_OP`` one creates an
aligned two-byte object, and so on. Any of the hooks may be
``NULL``, indicating that no suitable directive is available.
.. include:: ../tm.rst.in
:start-after: [TARGET_ASM_INTEGER]
:end-before: [TARGET_ASM_INTEGER]
The compiler will print these strings at the start of a new line,
followed immediately by the object's initial value. In most cases,
the string should contain a tab, a pseudo-op, and then another tab.
.. hook-end
.. include:: ../tm.rst.in
:start-after: [TARGET_ASM_DECL_END]
:end-before: [TARGET_ASM_DECL_END]
.. function:: bool TARGET_ASM_INTEGER (rtx x, unsigned int size, int aligned_p)
.. hook-start:TARGET_ASM_INTEGER
.. include:: ../tm.rst.in
:start-after: [TARGET_ASM_OUTPUT_ADDR_CONST_EXTRA]
:end-before: [TARGET_ASM_OUTPUT_ADDR_CONST_EXTRA]
The ``assemble_integer`` function uses this hook to output an
integer object. :samp:`{x}` is the object's value, :samp:`{size}` is its size
in bytes and :samp:`{aligned_p}` indicates whether it is aligned. The
function should return ``true`` if it was able to output the
object. If it returns false, ``assemble_integer`` will try to
split the object into smaller parts.
The default implementation of this hook will use the
``TARGET_ASM_BYTE_OP`` family of strings, returning ``false``
when the relevant string is ``NULL``.
.. hook-end
.. function:: void TARGET_ASM_DECL_END (void)
.. hook-start:TARGET_ASM_DECL_END
Define this hook if the target assembler requires a special marker to
terminate an initialized variable declaration.
.. hook-end
.. function:: bool TARGET_ASM_OUTPUT_ADDR_CONST_EXTRA (FILE *file, rtx x)
.. hook-start:TARGET_ASM_OUTPUT_ADDR_CONST_EXTRA
A target hook to recognize :samp:`{rtx}` patterns that ``output_addr_const``
can't deal with, and output assembly code to :samp:`{file}` corresponding to
the pattern :samp:`{x}`. This may be used to allow machine-dependent
``UNSPEC`` s to appear within constants.
If target hook fails to recognize a pattern, it must return ``false``,
so that a standard error message is printed. If it prints an error message
itself, by calling, for example, ``output_operand_lossage``, it may just
return ``true``.
.. hook-end
.. c:macro:: ASM_OUTPUT_ASCII (stream, ptr, len)
@ -155,15 +117,10 @@ Output of Data
.. c:var:: const char * TARGET_ASM_OPEN_PAREN
.. c:var:: const char * TARGET_ASM_CLOSE_PAREN
.. include:: ../tm.rst.in
:start-after: [TARGET_ASM_OPEN_PAREN]
:end-before: [TARGET_ASM_OPEN_PAREN]
.. hook-start:TARGET_ASM_OPEN_PAREN
These target hooks are C string constants, describing the syntax in the
assembler for grouping arithmetic expressions. If not overridden, they
default to normal parentheses, which is correct for most assemblers.
.. hook-end
These macros are provided by :samp:`real.h` for writing the definitions
of ``ASM_OUTPUT_DOUBLE`` and the like:

104
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@ -75,97 +75,41 @@ This concerns dispatch tables.
If this macro is not defined, nothing special is output at the end of
the jump-table.
.. function:: void TARGET_ASM_POST_CFI_STARTPROC (FILE *, tree)
.. include:: ../tm.rst.in
:start-after: [TARGET_ASM_POST_CFI_STARTPROC]
:end-before: [TARGET_ASM_POST_CFI_STARTPROC]
.. hook-start:TARGET_ASM_POST_CFI_STARTPROC
This target hook is used to emit assembly strings required by the target
after the .cfi_startproc directive. The first argument is the file stream to
write the strings to and the second argument is the function's declaration. The
expected use is to add more .cfi_\* directives.
.. include:: ../tm.rst.in
:start-after: [TARGET_ASM_EMIT_UNWIND_LABEL]
:end-before: [TARGET_ASM_EMIT_UNWIND_LABEL]
The default is to not output any assembly strings.
.. hook-end
.. include:: ../tm.rst.in
:start-after: [TARGET_ASM_EMIT_EXCEPT_TABLE_LABEL]
:end-before: [TARGET_ASM_EMIT_EXCEPT_TABLE_LABEL]
.. function:: void TARGET_ASM_EMIT_UNWIND_LABEL (FILE *stream, tree decl, int for_eh, int empty)
.. hook-start:TARGET_ASM_EMIT_UNWIND_LABEL
.. include:: ../tm.rst.in
:start-after: [TARGET_ASM_EMIT_EXCEPT_PERSONALITY]
:end-before: [TARGET_ASM_EMIT_EXCEPT_PERSONALITY]
This target hook emits a label at the beginning of each FDE. It
should be defined on targets where FDEs need special labels, and it
should write the appropriate label, for the FDE associated with the
function declaration :samp:`{decl}`, to the stdio stream :samp:`{stream}`.
The third argument, :samp:`{for_eh}`, is a boolean: true if this is for an
exception table. The fourth argument, :samp:`{empty}`, is a boolean:
true if this is a placeholder label for an omitted FDE.
The default is that FDEs are not given nonlocal labels.
.. include:: ../tm.rst.in
:start-after: [TARGET_ASM_UNWIND_EMIT]
:end-before: [TARGET_ASM_UNWIND_EMIT]
.. hook-end
.. function:: void TARGET_ASM_EMIT_EXCEPT_TABLE_LABEL (FILE *stream)
.. include:: ../tm.rst.in
:start-after: [TARGET_ASM_MAKE_EH_SYMBOL_INDIRECT]
:end-before: [TARGET_ASM_MAKE_EH_SYMBOL_INDIRECT]
.. hook-start:TARGET_ASM_EMIT_EXCEPT_TABLE_LABEL
This target hook emits a label at the beginning of the exception table.
It should be defined on targets where it is desirable for the table
to be broken up according to function.
.. include:: ../tm.rst.in
:start-after: [TARGET_ASM_UNWIND_EMIT_BEFORE_INSN]
:end-before: [TARGET_ASM_UNWIND_EMIT_BEFORE_INSN]
The default is that no label is emitted.
.. hook-end
.. function:: void TARGET_ASM_EMIT_EXCEPT_PERSONALITY (rtx personality)
.. hook-start:TARGET_ASM_EMIT_EXCEPT_PERSONALITY
If the target implements ``TARGET_ASM_UNWIND_EMIT``, this hook may be
used to emit a directive to install a personality hook into the unwind
info. This hook should not be used if dwarf2 unwind info is used.
.. hook-end
.. function:: void TARGET_ASM_UNWIND_EMIT (FILE *stream, rtx_insn *insn)
.. hook-start:TARGET_ASM_UNWIND_EMIT
This target hook emits assembly directives required to unwind the
given instruction. This is only used when ``TARGET_EXCEPT_UNWIND_INFO``
returns ``UI_TARGET``.
.. hook-end
.. function:: rtx TARGET_ASM_MAKE_EH_SYMBOL_INDIRECT (rtx origsymbol, bool pubvis)
.. hook-start:TARGET_ASM_MAKE_EH_SYMBOL_INDIRECT
If necessary, modify personality and LSDA references to handle indirection.
The original symbol is in ``origsymbol`` and if ``pubvis`` is true
the symbol is visible outside the TU.
.. hook-end
.. c:var:: bool TARGET_ASM_UNWIND_EMIT_BEFORE_INSN
.. hook-start:TARGET_ASM_UNWIND_EMIT_BEFORE_INSN
True if the ``TARGET_ASM_UNWIND_EMIT`` hook should be called before
the assembly for :samp:`{insn}` has been emitted, false if the hook should
be called afterward.
.. hook-end
.. function:: bool TARGET_ASM_SHOULD_RESTORE_CFA_STATE (void)
.. hook-start:TARGET_ASM_SHOULD_RESTORE_CFA_STATE
For DWARF-based unwind frames, two CFI instructions provide for save and
restore of register state. GCC maintains the current frame address (CFA)
separately from the register bank but the unwinder in libgcc preserves this
state along with the registers (and this is expected by the code that writes
the unwind frames). This hook allows the target to specify that the CFA data
is not saved/restored along with the registers by the target unwinder so that
suitable additional instructions should be emitted to restore it.
.. hook-end
.. include:: ../tm.rst.in
:start-after: [TARGET_ASM_SHOULD_RESTORE_CFA_STATE]
:end-before: [TARGET_ASM_SHOULD_RESTORE_CFA_STATE]

237
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@ -16,56 +16,25 @@ This describes the overall framework of an assembly file.
.. index:: default_file_start
.. function:: void TARGET_ASM_FILE_START (void)
.. include:: ../tm.rst.in
:start-after: [TARGET_ASM_FILE_START]
:end-before: [TARGET_ASM_FILE_START]
.. hook-start:TARGET_ASM_FILE_START
Output to ``asm_out_file`` any text which the assembler expects to
find at the beginning of a file. The default behavior is controlled
by two flags, documented below. Unless your target's assembler is
quite unusual, if you override the default, you should call
``default_file_start`` at some point in your target hook. This
lets other target files rely on these variables.
.. include:: ../tm.rst.in
:start-after: [TARGET_ASM_FILE_START_APP_OFF]
:end-before: [TARGET_ASM_FILE_START_APP_OFF]
.. hook-end
.. c:var:: bool TARGET_ASM_FILE_START_APP_OFF
.. include:: ../tm.rst.in
:start-after: [TARGET_ASM_FILE_START_FILE_DIRECTIVE]
:end-before: [TARGET_ASM_FILE_START_FILE_DIRECTIVE]
.. hook-start:TARGET_ASM_FILE_START_APP_OFF
If this flag is true, the text of the macro ``ASM_APP_OFF`` will be
printed as the very first line in the assembly file, unless
:option:`-fverbose-asm` is in effect. (If that macro has been defined
to the empty string, this variable has no effect.) With the normal
definition of ``ASM_APP_OFF``, the effect is to notify the GNU
assembler that it need not bother stripping comments or extra
whitespace from its input. This allows it to work a bit faster.
.. include:: ../tm.rst.in
:start-after: [TARGET_ASM_FILE_END]
:end-before: [TARGET_ASM_FILE_END]
The default is false. You should not set it to true unless you have
verified that your port does not generate any extra whitespace or
comments that will cause GAS to issue errors in NO_APP mode.
.. hook-end
.. c:var:: bool TARGET_ASM_FILE_START_FILE_DIRECTIVE
.. hook-start:TARGET_ASM_FILE_START_FILE_DIRECTIVE
If this flag is true, ``output_file_directive`` will be called
for the primary source file, immediately after printing
``ASM_APP_OFF`` (if that is enabled). Most ELF assemblers expect
this to be done. The default is false.
.. hook-end
.. function:: void TARGET_ASM_FILE_END (void)
.. hook-start:TARGET_ASM_FILE_END
Output to ``asm_out_file`` any text which the assembler expects
to find at the end of a file. The default is to output nothing.
.. hook-end
.. function:: void file_end_indicate_exec_stack ()
@ -76,37 +45,20 @@ This describes the overall framework of an assembly file.
need to do other things in that hook, have your hook function call
this function.
.. function:: void TARGET_ASM_LTO_START (void)
.. include:: ../tm.rst.in
:start-after: [TARGET_ASM_LTO_START]
:end-before: [TARGET_ASM_LTO_START]
.. hook-start:TARGET_ASM_LTO_START
Output to ``asm_out_file`` any text which the assembler expects
to find at the start of an LTO section. The default is to output
nothing.
.. include:: ../tm.rst.in
:start-after: [TARGET_ASM_LTO_END]
:end-before: [TARGET_ASM_LTO_END]
.. hook-end
.. function:: void TARGET_ASM_LTO_END (void)
.. include:: ../tm.rst.in
:start-after: [TARGET_ASM_CODE_END]
:end-before: [TARGET_ASM_CODE_END]
.. hook-start:TARGET_ASM_LTO_END
Output to ``asm_out_file`` any text which the assembler expects
to find at the end of an LTO section. The default is to output
nothing.
.. hook-end
.. function:: void TARGET_ASM_CODE_END (void)
.. hook-start:TARGET_ASM_CODE_END
Output to ``asm_out_file`` any text which is needed before emitting
unwind info and debug info at the end of a file. Some targets emit
here PIC setup thunks that cannot be emitted at the end of file,
because they couldn't have unwind info then. The default is to output
nothing.
.. hook-end
.. c:macro:: ASM_COMMENT_START
@ -138,28 +90,15 @@ This describes the overall framework of an assembly file.
This macro need not be defined if the standard form of output
for the file format in use is appropriate.
.. function:: void TARGET_ASM_OUTPUT_SOURCE_FILENAME (FILE *file, const char *name)
.. include:: ../tm.rst.in
:start-after: [TARGET_ASM_OUTPUT_SOURCE_FILENAME]
:end-before: [TARGET_ASM_OUTPUT_SOURCE_FILENAME]
.. hook-start:TARGET_ASM_OUTPUT_SOURCE_FILENAME
Output DWARF debugging information which indicates that filename
:samp:`{name}` is the current source file to the stdio stream :samp:`{file}`.
.. include:: ../tm.rst.in
:start-after: [TARGET_ASM_OUTPUT_IDENT]
:end-before: [TARGET_ASM_OUTPUT_IDENT]
This target hook need not be defined if the standard form of output
for the file format in use is appropriate.
.. hook-end
.. function:: void TARGET_ASM_OUTPUT_IDENT (const char *name)
.. hook-start:TARGET_ASM_OUTPUT_IDENT
Output a string based on :samp:`{name}`, suitable for the :samp:`#ident`
directive, or the equivalent directive or pragma in non-C-family languages.
If this hook is not defined, nothing is output for the :samp:`#ident`
directive.
.. hook-end
.. c:macro:: OUTPUT_QUOTED_STRING (stream, string)
@ -169,119 +108,51 @@ This describes the overall framework of an assembly file.
the assembler source. So you can use it to canonicalize the format
of the filename using this macro.
.. function:: void TARGET_ASM_NAMED_SECTION (const char *name, unsigned int flags, tree decl)
.. include:: ../tm.rst.in
:start-after: [TARGET_ASM_NAMED_SECTION]
:end-before: [TARGET_ASM_NAMED_SECTION]
.. hook-start:TARGET_ASM_NAMED_SECTION
Output assembly directives to switch to section :samp:`{name}`. The section
should have attributes as specified by :samp:`{flags}`, which is a bit mask
of the ``SECTION_*`` flags defined in :samp:`output.h`. If :samp:`{decl}`
is non-NULL, it is the ``VAR_DECL`` or ``FUNCTION_DECL`` with which
this section is associated.
.. include:: ../tm.rst.in
:start-after: [TARGET_ASM_ELF_FLAGS_NUMERIC]
:end-before: [TARGET_ASM_ELF_FLAGS_NUMERIC]
.. hook-end
.. function:: bool TARGET_ASM_ELF_FLAGS_NUMERIC (unsigned int flags, unsigned int *num)
.. include:: ../tm.rst.in
:start-after: [TARGET_ASM_FUNCTION_SECTION]
:end-before: [TARGET_ASM_FUNCTION_SECTION]
.. hook-start:TARGET_ASM_ELF_FLAGS_NUMERIC
This hook can be used to encode ELF section flags for which no letter
code has been defined in the assembler. It is called by
``default_asm_named_section`` whenever the section flags need to be
emitted in the assembler output. If the hook returns true, then the
numerical value for ELF section flags should be calculated from
:samp:`{flags}` and saved in :samp:`{*num}` ; the value is printed out instead of the
normal sequence of letter codes. If the hook is not defined, or if it
returns false, then :samp:`{num}` is ignored and the traditional letter sequence
is emitted.
.. include:: ../tm.rst.in
:start-after: [TARGET_ASM_FUNCTION_SWITCHED_TEXT_SECTIONS]
:end-before: [TARGET_ASM_FUNCTION_SWITCHED_TEXT_SECTIONS]
.. hook-end
.. function:: section * TARGET_ASM_FUNCTION_SECTION (tree decl, enum node_frequency freq, bool startup, bool exit)
.. include:: ../tm.rst.in
:start-after: [TARGET_HAVE_NAMED_SECTIONS]
:end-before: [TARGET_HAVE_NAMED_SECTIONS]
.. hook-start:TARGET_ASM_FUNCTION_SECTION
Return preferred text (sub)section for function :samp:`{decl}`.
Main purpose of this function is to separate cold, normal and hot
functions. :samp:`{startup}` is true when function is known to be used only
at startup (from static constructors or it is ``main()``).
:samp:`{exit}` is true when function is known to be used only at exit
(from static destructors).
Return NULL if function should go to default text section.
.. hook-end
.. function:: void TARGET_ASM_FUNCTION_SWITCHED_TEXT_SECTIONS (FILE *file, tree decl, bool new_is_cold)
.. hook-start:TARGET_ASM_FUNCTION_SWITCHED_TEXT_SECTIONS
Used by the target to emit any assembler directives or additional
labels needed when a function is partitioned between different
sections. Output should be written to :samp:`{file}`. The function
decl is available as :samp:`{decl}` and the new section is 'cold' if
:samp:`{new_is_cold}` is ``true``.
.. hook-end
.. c:var:: bool TARGET_HAVE_NAMED_SECTIONS
.. hook-start:TARGET_HAVE_NAMED_SECTIONS
.. hook-end
This flag is true if the target supports ``TARGET_ASM_NAMED_SECTION``.
It must not be modified by command-line option processing.
.. _target_have_switchable_bss_sections:
.. c:var:: bool TARGET_HAVE_SWITCHABLE_BSS_SECTIONS
.. include:: ../tm.rst.in
:start-after: [TARGET_HAVE_SWITCHABLE_BSS_SECTIONS]
:end-before: [TARGET_HAVE_SWITCHABLE_BSS_SECTIONS]
.. hook-start:TARGET_HAVE_SWITCHABLE_BSS_SECTIONS
This flag is true if we can create zeroed data by switching to a BSS
section and then using ``ASM_OUTPUT_SKIP`` to allocate the space.
This is true on most ELF targets.
.. include:: ../tm.rst.in
:start-after: [TARGET_SECTION_TYPE_FLAGS]
:end-before: [TARGET_SECTION_TYPE_FLAGS]
.. hook-end
.. function:: unsigned int TARGET_SECTION_TYPE_FLAGS (tree decl, const char *name, int reloc)
.. include:: ../tm.rst.in
:start-after: [TARGET_ASM_RECORD_GCC_SWITCHES]
:end-before: [TARGET_ASM_RECORD_GCC_SWITCHES]
.. hook-start:TARGET_SECTION_TYPE_FLAGS
Choose a set of section attributes for use by ``TARGET_ASM_NAMED_SECTION``
based on a variable or function decl, a section name, and whether or not the
declaration's initializer may contain runtime relocations. :samp:`{decl}` may be
null, in which case read-write data should be assumed.
The default version of this function handles choosing code vs data,
read-only vs read-write data, and ``flag_pic``. You should only
need to override this if your target has special flags that might be
set via ``__attribute__``.
.. hook-end
.. function:: void TARGET_ASM_RECORD_GCC_SWITCHES (const char *)
.. hook-start:TARGET_ASM_RECORD_GCC_SWITCHES
Provides the target with the ability to record the gcc command line
switches provided as argument.
By default this hook is set to NULL, but an example implementation is
provided for ELF based targets. Called :samp:`{elf_record_gcc_switches}`,
it records the switches as ASCII text inside a new, string mergeable
section in the assembler output file. The name of the new section is
provided by the ``TARGET_ASM_RECORD_GCC_SWITCHES_SECTION`` target
hook.
.. hook-end
.. c:var:: const char * TARGET_ASM_RECORD_GCC_SWITCHES_SECTION
.. hook-start:TARGET_ASM_RECORD_GCC_SWITCHES_SECTION
This is the name of the section that will be created by the example
ELF implementation of the ``TARGET_ASM_RECORD_GCC_SWITCHES`` target
hook.
.. hook-end
.. include:: ../tm.rst.in
:start-after: [TARGET_ASM_RECORD_GCC_SWITCHES_SECTION]
:end-before: [TARGET_ASM_RECORD_GCC_SWITCHES_SECTION]

335
gcc/doc/gccint/target-macros/describing-relative-costs-of-operations.rst
View File

@ -35,30 +35,10 @@ on the target machine.
These macros are obsolete, new ports should use the target hook
``TARGET_REGISTER_MOVE_COST`` instead.
.. function:: int TARGET_REGISTER_MOVE_COST (machine_mode mode, reg_class_t from, reg_class_t to)
.. include:: tm.rst.in
:start-after: [TARGET_REGISTER_MOVE_COST]
:end-before: [TARGET_REGISTER_MOVE_COST]
.. hook-start:TARGET_REGISTER_MOVE_COST
This target hook should return the cost of moving data of mode :samp:`{mode}`
from a register in class :samp:`{from}` to one in class :samp:`{to}`. The classes
are expressed using the enumeration values such as ``GENERAL_REGS``.
A value of 2 is the default; other values are interpreted relative to
that.
It is not required that the cost always equal 2 when :samp:`{from}` is the
same as :samp:`{to}` ; on some machines it is expensive to move between
registers if they are not general registers.
If reload sees an insn consisting of a single ``set`` between two
hard registers, and if ``TARGET_REGISTER_MOVE_COST`` applied to their
classes returns a value of 2, reload does not check to ensure that the
constraints of the insn are met. Setting a cost of other than 2 will
allow reload to verify that the constraints are met. You should do this
if the :samp:`mov{m}` pattern's constraints do not allow such copying.
The default version of this function returns 2.
.. hook-end
.. c:macro:: MEMORY_MOVE_COST (mode, class, in)
@ -87,33 +67,10 @@ on the target machine.
These macros are obsolete, new ports should use the target hook
``TARGET_MEMORY_MOVE_COST`` instead.
.. function:: int TARGET_MEMORY_MOVE_COST (machine_mode mode, reg_class_t rclass, bool in)
.. include:: tm.rst.in
:start-after: [TARGET_MEMORY_MOVE_COST]
:end-before: [TARGET_MEMORY_MOVE_COST]
.. hook-start:TARGET_MEMORY_MOVE_COST
This target hook should return the cost of moving data of mode :samp:`{mode}`
between a register of class :samp:`{rclass}` and memory; :samp:`{in}` is ``false``
if the value is to be written to memory, ``true`` if it is to be read in.
This cost is relative to those in ``TARGET_REGISTER_MOVE_COST``.
If moving between registers and memory is more expensive than between two
registers, you should add this target hook to express the relative cost.
If you do not add this target hook, GCC uses a default cost of 4 plus
the cost of copying via a secondary reload register, if one is
needed. If your machine requires a secondary reload register to copy
between memory and a register of :samp:`{rclass}` but the reload mechanism is
more complex than copying via an intermediate, use this target hook to
reflect the actual cost of the move.
GCC defines the function ``memory_move_secondary_cost`` if
secondary reloads are needed. It computes the costs due to copying via
a secondary register. If your machine copies from memory using a
secondary register in the conventional way but the default base value of
4 is not correct for your machine, use this target hook to add some other
value to the result of that function. The arguments to that function
are the same as to this target hook.
.. hook-end
.. c:macro:: BRANCH_COST (speed_p, predictable_p)
@ -144,26 +101,10 @@ ordinarily expect.
may eliminate subsequent memory access if subsequent accesses occur to
other fields in the same word of the structure, but to different bytes.
.. function:: bool TARGET_SLOW_UNALIGNED_ACCESS (machine_mode mode, unsigned int align)
.. include:: tm.rst.in
:start-after: [TARGET_SLOW_UNALIGNED_ACCESS]
:end-before: [TARGET_SLOW_UNALIGNED_ACCESS]
.. hook-start:TARGET_SLOW_UNALIGNED_ACCESS
This hook returns true if memory accesses described by the
:samp:`{mode}` and :samp:`{alignment}` parameters have a cost many times greater
than aligned accesses, for example if they are emulated in a trap handler.
This hook is invoked only for unaligned accesses, i.e. when
``alignment < GET_MODE_ALIGNMENT (mode)``.
When this hook returns true, the compiler will act as if
``STRICT_ALIGNMENT`` were true when generating code for block
moves. This can cause significantly more instructions to be produced.
Therefore, do not make this hook return true if unaligned accesses only
add a cycle or two to the time for a memory access.
The hook must return true whenever ``STRICT_ALIGNMENT`` is true.
The default implementation returns ``STRICT_ALIGNMENT``.
.. hook-end
.. c:macro:: MOVE_RATIO (speed)
@ -181,69 +122,20 @@ ordinarily expect.
If you don't define this, a reasonable default is used.
.. function:: bool TARGET_USE_BY_PIECES_INFRASTRUCTURE_P (unsigned HOST_WIDE_INT size, unsigned int alignment, enum by_pieces_operation op, bool speed_p)
.. include:: tm.rst.in
:start-after: [TARGET_USE_BY_PIECES_INFRASTRUCTURE_P]
:end-before: [TARGET_USE_BY_PIECES_INFRASTRUCTURE_P]
.. hook-start:TARGET_USE_BY_PIECES_INFRASTRUCTURE_P
GCC will attempt several strategies when asked to copy between
two areas of memory, or to set, clear or store to memory, for example
when copying a ``struct``. The ``by_pieces`` infrastructure
implements such memory operations as a sequence of load, store or move
insns. Alternate strategies are to expand the
``cpymem`` or ``setmem`` optabs, to emit a library call, or to emit
unit-by-unit, loop-based operations.
.. include:: tm.rst.in
:start-after: [TARGET_OVERLAP_OP_BY_PIECES_P]
:end-before: [TARGET_OVERLAP_OP_BY_PIECES_P]
This target hook should return true if, for a memory operation with a
given :samp:`{size}` and :samp:`{alignment}`, using the ``by_pieces``
infrastructure is expected to result in better code generation.
Both :samp:`{size}` and :samp:`{alignment}` are measured in terms of storage
units.
The parameter :samp:`{op}` is one of: ``CLEAR_BY_PIECES``,
``MOVE_BY_PIECES``, ``SET_BY_PIECES``, ``STORE_BY_PIECES`` or
``COMPARE_BY_PIECES``. These describe the type of memory operation
under consideration.
.. include:: tm.rst.in
:start-after: [TARGET_COMPARE_BY_PIECES_BRANCH_RATIO]
:end-before: [TARGET_COMPARE_BY_PIECES_BRANCH_RATIO]
The parameter :samp:`{speed_p}` is true if the code is currently being
optimized for speed rather than size.
Returning true for higher values of :samp:`{size}` can improve code generation
for speed if the target does not provide an implementation of the
``cpymem`` or ``setmem`` standard names, if the ``cpymem`` or
``setmem`` implementation would be more expensive than a sequence of
insns, or if the overhead of a library call would dominate that of
the body of the memory operation.
Returning true for higher values of ``size`` may also cause an increase
in code size, for example where the number of insns emitted to perform a
move would be greater than that of a library call.
.. hook-end
.. function:: bool TARGET_OVERLAP_OP_BY_PIECES_P (void)
.. hook-start:TARGET_OVERLAP_OP_BY_PIECES_P
This target hook should return true if when the ``by_pieces``
infrastructure is used, an offset adjusted unaligned memory operation
in the smallest integer mode for the last piece operation of a memory
region can be generated to avoid doing more than one smaller operations.
.. hook-end
.. function:: int TARGET_COMPARE_BY_PIECES_BRANCH_RATIO (machine_mode mode)
.. hook-start:TARGET_COMPARE_BY_PIECES_BRANCH_RATIO
When expanding a block comparison in MODE, gcc can try to reduce the
number of branches at the expense of more memory operations. This hook
allows the target to override the default choice. It should return the
factor by which branches should be reduced over the plain expansion with
one comparison per :samp:`{mode}` -sized piece. A port can also prevent a
particular mode from being used for block comparisons by returning a
negative number from this hook.
.. hook-end
.. c:macro:: MOVE_MAX_PIECES
@ -346,183 +238,46 @@ ordinarily expect.
:samp:`fold_range_test ()` is optimal. This macro defaults to true if
``BRANCH_COST`` is greater than or equal to the value 2.
.. function:: bool TARGET_OPTAB_SUPPORTED_P (int op, machine_mode mode1, machine_mode mode2, optimization_type opt_type)
.. include:: tm.rst.in
:start-after: [TARGET_OPTAB_SUPPORTED_P]
:end-before: [TARGET_OPTAB_SUPPORTED_P]
.. hook-start:TARGET_OPTAB_SUPPORTED_P
Return true if the optimizers should use optab :samp:`{op}` with
modes :samp:`{mode1}` and :samp:`{mode2}` for optimization type :samp:`{opt_type}`.
The optab is known to have an associated :samp:`.md` instruction
whose C condition is true. :samp:`{mode2}` is only meaningful for conversion
optabs; for direct optabs it is a copy of :samp:`{mode1}`.
.. include:: tm.rst.in
:start-after: [TARGET_RTX_COSTS]
:end-before: [TARGET_RTX_COSTS]
For example, when called with :samp:`{op}` equal to ``rint_optab`` and
:samp:`{mode1}` equal to ``DFmode``, the hook should say whether the
optimizers should use optab ``rintdf2``.
The default hook returns true for all inputs.
.. include:: tm.rst.in
:start-after: [TARGET_ADDRESS_COST]
:end-before: [TARGET_ADDRESS_COST]
.. hook-end
.. function:: bool TARGET_RTX_COSTS (rtx x, machine_mode mode, int outer_code, int opno, int *total, bool speed)
.. include:: tm.rst.in
:start-after: [TARGET_INSN_COST]
:end-before: [TARGET_INSN_COST]
.. hook-start:TARGET_RTX_COSTS
This target hook describes the relative costs of RTL expressions.
.. include:: tm.rst.in
:start-after: [TARGET_MAX_NOCE_IFCVT_SEQ_COST]
:end-before: [TARGET_MAX_NOCE_IFCVT_SEQ_COST]
The cost may depend on the precise form of the expression, which is
available for examination in :samp:`{x}`, and the fact that :samp:`{x}` appears
as operand :samp:`{opno}` of an expression with rtx code :samp:`{outer_code}`.
That is, the hook can assume that there is some rtx :samp:`{y}` such
that :samp:`GET_CODE ({y}) == {outer_code}` and such that
either (a) :samp:`XEXP ({y}, {opno}) == {x}` or
(b) :samp:`XVEC ({y}, {opno})` contains :samp:`{x}`.
:samp:`{mode}` is :samp:`{x}` 's machine mode, or for cases like ``const_int`` that
do not have a mode, the mode in which :samp:`{x}` is used.
.. include:: tm.rst.in
:start-after: [TARGET_NOCE_CONVERSION_PROFITABLE_P]
:end-before: [TARGET_NOCE_CONVERSION_PROFITABLE_P]
In implementing this hook, you can use the construct
``COSTS_N_INSNS (n)`` to specify a cost equal to :samp:`{n}` fast
instructions.
On entry to the hook, ``*total`` contains a default estimate
for the cost of the expression. The hook should modify this value as
necessary. Traditionally, the default costs are ``COSTS_N_INSNS (5)``
for multiplications, ``COSTS_N_INSNS (7)`` for division and modulus
operations, and ``COSTS_N_INSNS (1)`` for all other operations.
.. include:: tm.rst.in
:start-after: [TARGET_NEW_ADDRESS_PROFITABLE_P]
:end-before: [TARGET_NEW_ADDRESS_PROFITABLE_P]
When optimizing for code size, i.e. when ``speed`` is
false, this target hook should be used to estimate the relative
size cost of an expression, again relative to ``COSTS_N_INSNS``.
The hook returns true when all subexpressions of :samp:`{x}` have been
processed, and false when ``rtx_cost`` should recurse.
.. include:: tm.rst.in
:start-after: [TARGET_NO_SPECULATION_IN_DELAY_SLOTS_P]
:end-before: [TARGET_NO_SPECULATION_IN_DELAY_SLOTS_P]
.. hook-end
.. function:: int TARGET_ADDRESS_COST (rtx address, machine_mode mode, addr_space_t as, bool speed)
.. hook-start:TARGET_ADDRESS_COST
This hook computes the cost of an addressing mode that contains
:samp:`{address}`. If not defined, the cost is computed from
the :samp:`{address}` expression and the ``TARGET_RTX_COST`` hook.
For most CISC machines, the default cost is a good approximation of the
true cost of the addressing mode. However, on RISC machines, all
instructions normally have the same length and execution time. Hence
all addresses will have equal costs.
In cases where more than one form of an address is known, the form with
the lowest cost will be used. If multiple forms have the same, lowest,
cost, the one that is the most complex will be used.
For example, suppose an address that is equal to the sum of a register
and a constant is used twice in the same basic block. When this macro
is not defined, the address will be computed in a register and memory
references will be indirect through that register. On machines where
the cost of the addressing mode containing the sum is no higher than
that of a simple indirect reference, this will produce an additional
instruction and possibly require an additional register. Proper
specification of this macro eliminates this overhead for such machines.
This hook is never called with an invalid address.
On machines where an address involving more than one register is as
cheap as an address computation involving only one register, defining
``TARGET_ADDRESS_COST`` to reflect this can cause two registers to
be live over a region of code where only one would have been if
``TARGET_ADDRESS_COST`` were not defined in that manner. This effect
should be considered in the definition of this macro. Equivalent costs
should probably only be given to addresses with different numbers of
registers on machines with lots of registers.
.. hook-end
.. function:: int TARGET_INSN_COST (rtx_insn *insn, bool speed)
.. hook-start:TARGET_INSN_COST
This target hook describes the relative costs of RTL instructions.
In implementing this hook, you can use the construct
``COSTS_N_INSNS (n)`` to specify a cost equal to :samp:`{n}` fast
instructions.
When optimizing for code size, i.e. when ``speed`` is
false, this target hook should be used to estimate the relative
size cost of an expression, again relative to ``COSTS_N_INSNS``.
.. hook-end
.. function:: unsigned int TARGET_MAX_NOCE_IFCVT_SEQ_COST (edge e)
.. hook-start:TARGET_MAX_NOCE_IFCVT_SEQ_COST
This hook returns a value in the same units as ``TARGET_RTX_COSTS``,
giving the maximum acceptable cost for a sequence generated by the RTL
if-conversion pass when conditional execution is not available.
The RTL if-conversion pass attempts to convert conditional operations
that would require a branch to a series of unconditional operations and
``movmodecc`` insns. This hook returns the maximum cost of the
unconditional instructions and the ``movmodecc`` insns.
RTL if-conversion is cancelled if the cost of the converted sequence
is greater than the value returned by this hook.
``e`` is the edge between the basic block containing the conditional
branch to the basic block which would be executed if the condition
were true.
The default implementation of this hook uses the
``max-rtl-if-conversion-[un]predictable`` parameters if they are set,
and uses a multiple of ``BRANCH_COST`` otherwise.
.. hook-end
.. function:: bool TARGET_NOCE_CONVERSION_PROFITABLE_P (rtx_insn *seq, struct noce_if_info *if_info)
.. hook-start:TARGET_NOCE_CONVERSION_PROFITABLE_P
This hook returns true if the instruction sequence ``seq`` is a good
candidate as a replacement for the if-convertible sequence described in
``if_info``.
.. hook-end
.. function:: bool TARGET_NEW_ADDRESS_PROFITABLE_P (rtx memref, rtx_insn * insn, rtx new_addr)
.. hook-start:TARGET_NEW_ADDRESS_PROFITABLE_P
Return ``true`` if it is profitable to replace the address in
:samp:`{memref}` with :samp:`{new_addr}`. This allows targets to prevent the
scheduler from undoing address optimizations. The instruction containing the
memref is :samp:`{insn}`. The default implementation returns ``true``.
.. hook-end
.. function:: bool TARGET_NO_SPECULATION_IN_DELAY_SLOTS_P (void)
.. hook-start:TARGET_NO_SPECULATION_IN_DELAY_SLOTS_P
This predicate controls the use of the eager delay slot filler to disallow
speculatively executed instructions being placed in delay slots. Targets
such as certain MIPS architectures possess both branches with and without
delay slots. As the eager delay slot filler can decrease performance,
disabling it is beneficial when ordinary branches are available. Use of
delay slot branches filled using the basic filler is often still desirable
as the delay slot can hide a pipeline bubble.
.. hook-end
.. function:: HOST_WIDE_INT TARGET_ESTIMATED_POLY_VALUE (poly_int64 val, poly_value_estimate_kind kind)
.. hook-start:TARGET_ESTIMATED_POLY_VALUE
Return an estimate of the runtime value of :samp:`{val}`, for use in
things like cost calculations or profiling frequencies. :samp:`{kind}` is used
to ask for the minimum, maximum, and likely estimates of the value through
the ``POLY_VALUE_MIN``, ``POLY_VALUE_MAX`` and
``POLY_VALUE_LIKELY`` values. The default
implementation returns the lowest possible value of :samp:`{val}`.
.. hook-end
.. include:: tm.rst.in
:start-after: [TARGET_ESTIMATED_POLY_VALUE]
:end-before: [TARGET_ESTIMATED_POLY_VALUE]

262
gcc/doc/gccint/target-macros/dividing-the-output-into-sections-texts-data.rst
View File

@ -191,65 +191,25 @@ if the target does not provide them.
This macro is irrelevant if there is no separate readonly data section.
.. function:: void TARGET_ASM_INIT_SECTIONS (void)
.. include:: tm.rst.in
:start-after: [TARGET_ASM_INIT_SECTIONS]
:end-before: [TARGET_ASM_INIT_SECTIONS]
.. hook-start:TARGET_ASM_INIT_SECTIONS
Define this hook if you need to do something special to set up the
:samp:`varasm.cc` sections, or if your target has some special sections
of its own that you need to create.
.. include:: tm.rst.in
:start-after: [TARGET_ASM_RELOC_RW_MASK]
:end-before: [TARGET_ASM_RELOC_RW_MASK]
GCC calls this hook after processing the command line, but before writing
any assembly code, and before calling any of the section-returning hooks
described below.
.. hook-end
.. include:: tm.rst.in
:start-after: [TARGET_ASM_GENERATE_PIC_ADDR_DIFF_VEC]
:end-before: [TARGET_ASM_GENERATE_PIC_ADDR_DIFF_VEC]
.. function:: int TARGET_ASM_RELOC_RW_MASK (void)
.. hook-start:TARGET_ASM_RELOC_RW_MASK
.. include:: tm.rst.in
:start-after: [TARGET_ASM_SELECT_SECTION]
:end-before: [TARGET_ASM_SELECT_SECTION]
Return a mask describing how relocations should be treated when
selecting sections. Bit 1 should be set if global relocations
should be placed in a read-write section; bit 0 should be set if
local relocations should be placed in a read-write section.
The default version of this function returns 3 when :option:`-fpic`
is in effect, and 0 otherwise. The hook is typically redefined
when the target cannot support (some kinds of) dynamic relocations
in read-only sections even in executables.
.. hook-end
.. function:: bool TARGET_ASM_GENERATE_PIC_ADDR_DIFF_VEC (void)
.. hook-start:TARGET_ASM_GENERATE_PIC_ADDR_DIFF_VEC
Return true to generate ADDR_DIF_VEC table
or false to generate ADDR_VEC table for jumps in case of -fPIC.
The default version of this function returns true if flag_pic
equals true and false otherwise
.. hook-end
.. function:: section * TARGET_ASM_SELECT_SECTION (tree exp, int reloc, unsigned HOST_WIDE_INT align)
.. hook-start:TARGET_ASM_SELECT_SECTION
Return the section into which :samp:`{exp}` should be placed. You can
assume that :samp:`{exp}` is either a ``VAR_DECL`` node or a constant of
some sort. :samp:`{reloc}` indicates whether the initial value of :samp:`{exp}`
requires link-time relocations. Bit 0 is set when variable contains
local relocations only, while bit 1 is set for global relocations.
:samp:`{align}` is the constant alignment in bits.
The default version of this function takes care of putting read-only
variables in ``readonly_data_section``.
See also :samp:`{USE_SELECT_SECTION_FOR_FUNCTIONS}`.
.. hook-end
.. c:macro:: USE_SELECT_SECTION_FOR_FUNCTIONS
@ -260,186 +220,66 @@ if the target does not provide them.
function has been determined to be likely to be called, and nonzero if
it is unlikely to be called.
.. function:: void TARGET_ASM_UNIQUE_SECTION (tree decl, int reloc)
.. include:: tm.rst.in
:start-after: [TARGET_ASM_UNIQUE_SECTION]
:end-before: [TARGET_ASM_UNIQUE_SECTION]
.. hook-start:TARGET_ASM_UNIQUE_SECTION
Build up a unique section name, expressed as a ``STRING_CST`` node,
and assign it to :samp:`DECL_SECTION_NAME ({decl})`.
As with ``TARGET_ASM_SELECT_SECTION``, :samp:`{reloc}` indicates whether
the initial value of :samp:`{exp}` requires link-time relocations.
.. include:: tm.rst.in
:start-after: [TARGET_ASM_FUNCTION_RODATA_SECTION]
:end-before: [TARGET_ASM_FUNCTION_RODATA_SECTION]
The default version of this function appends the symbol name to the
ELF section name that would normally be used for the symbol. For
example, the function ``foo`` would be placed in ``.text.foo``.
Whatever the actual target object format, this is often good enough.
.. hook-end
.. include:: tm.rst.in
:start-after: [TARGET_ASM_MERGEABLE_RODATA_PREFIX]
:end-before: [TARGET_ASM_MERGEABLE_RODATA_PREFIX]
.. function:: section * TARGET_ASM_FUNCTION_RODATA_SECTION (tree decl, bool relocatable)
.. hook-start:TARGET_ASM_FUNCTION_RODATA_SECTION
.. include:: tm.rst.in
:start-after: [TARGET_ASM_TM_CLONE_TABLE_SECTION]
:end-before: [TARGET_ASM_TM_CLONE_TABLE_SECTION]
Return the readonly data or reloc readonly data section associated with
:samp:`DECL_SECTION_NAME ({decl})`. :samp:`{relocatable}` selects the latter
over the former.
The default version of this function selects ``.gnu.linkonce.r.name`` if
the function's section is ``.gnu.linkonce.t.name``, ``.rodata.name``
or ``.data.rel.ro.name`` if function is in ``.text.name``, and
the normal readonly-data or reloc readonly data section otherwise.
.. hook-end
.. include:: tm.rst.in
:start-after: [TARGET_ASM_SELECT_RTX_SECTION]
:end-before: [TARGET_ASM_SELECT_RTX_SECTION]
.. c:var:: const char * TARGET_ASM_MERGEABLE_RODATA_PREFIX
.. hook-start:TARGET_ASM_MERGEABLE_RODATA_PREFIX
.. include:: tm.rst.in
:start-after: [TARGET_MANGLE_DECL_ASSEMBLER_NAME]
:end-before: [TARGET_MANGLE_DECL_ASSEMBLER_NAME]
Usually, the compiler uses the prefix ``".rodata"`` to construct
section names for mergeable constant data. Define this macro to override
the string if a different section name should be used.
.. hook-end
.. include:: tm.rst.in
:start-after: [TARGET_ENCODE_SECTION_INFO]
:end-before: [TARGET_ENCODE_SECTION_INFO]
.. function:: section * TARGET_ASM_TM_CLONE_TABLE_SECTION (void)
.. hook-start:TARGET_ASM_TM_CLONE_TABLE_SECTION
.. include:: tm.rst.in
:start-after: [TARGET_STRIP_NAME_ENCODING]
:end-before: [TARGET_STRIP_NAME_ENCODING]
Return the section that should be used for transactional memory clone
tables.
.. hook-end
.. include:: tm.rst.in
:start-after: [TARGET_IN_SMALL_DATA_P]
:end-before: [TARGET_IN_SMALL_DATA_P]
.. function:: section * TARGET_ASM_SELECT_RTX_SECTION (machine_mode mode, rtx x, unsigned HOST_WIDE_INT align)
.. hook-start:TARGET_ASM_SELECT_RTX_SECTION
.. include:: tm.rst.in
:start-after: [TARGET_HAVE_SRODATA_SECTION]
:end-before: [TARGET_HAVE_SRODATA_SECTION]
Return the section into which a constant :samp:`{x}`, of mode :samp:`{mode}`,
should be placed. You can assume that :samp:`{x}` is some kind of
constant in RTL. The argument :samp:`{mode}` is redundant except in the
case of a ``const_int`` rtx. :samp:`{align}` is the constant alignment
in bits.
The default version of this function takes care of putting symbolic
constants in ``flag_pic`` mode in ``data_section`` and everything
else in ``readonly_data_section``.
.. include:: tm.rst.in
:start-after: [TARGET_PROFILE_BEFORE_PROLOGUE]
:end-before: [TARGET_PROFILE_BEFORE_PROLOGUE]
.. hook-end
.. function:: tree TARGET_MANGLE_DECL_ASSEMBLER_NAME (tree decl, tree id)
.. include:: tm.rst.in
:start-after: [TARGET_BINDS_LOCAL_P]
:end-before: [TARGET_BINDS_LOCAL_P]
.. hook-start:TARGET_MANGLE_DECL_ASSEMBLER_NAME
Define this hook if you need to postprocess the assembler name generated
by target-independent code. The :samp:`{id}` provided to this hook will be
the computed name (e.g., the macro ``DECL_NAME`` of the :samp:`{decl}` in C,
or the mangled name of the :samp:`{decl}` in C++). The return value of the
hook is an ``IDENTIFIER_NODE`` for the appropriate mangled name on
your target system. The default implementation of this hook just
returns the :samp:`{id}` provided.
.. hook-end
.. function:: void TARGET_ENCODE_SECTION_INFO (tree decl, rtx rtl, int new_decl_p)
.. hook-start:TARGET_ENCODE_SECTION_INFO
Define this hook if references to a symbol or a constant must be
treated differently depending on something about the variable or
function named by the symbol (such as what section it is in).
The hook is executed immediately after rtl has been created for
:samp:`{decl}`, which may be a variable or function declaration or
an entry in the constant pool. In either case, :samp:`{rtl}` is the
rtl in question. Do *not* use ``DECL_RTL (decl)``
in this hook; that field may not have been initialized yet.
In the case of a constant, it is safe to assume that the rtl is
a ``mem`` whose address is a ``symbol_ref``. Most decls
will also have this form, but that is not guaranteed. Global
register variables, for instance, will have a ``reg`` for their
rtl. (Normally the right thing to do with such unusual rtl is
leave it alone.)
The :samp:`{new_decl_p}` argument will be true if this is the first time
that ``TARGET_ENCODE_SECTION_INFO`` has been invoked on this decl. It will
be false for subsequent invocations, which will happen for duplicate
declarations. Whether or not anything must be done for the duplicate
declaration depends on whether the hook examines ``DECL_ATTRIBUTES``.
:samp:`{new_decl_p}` is always true when the hook is called for a constant.
.. index:: SYMBOL_REF_FLAG, in TARGET_ENCODE_SECTION_INFO
The usual thing for this hook to do is to record flags in the
``symbol_ref``, using ``SYMBOL_REF_FLAG`` or ``SYMBOL_REF_FLAGS``.
Historically, the name string was modified if it was necessary to
encode more than one bit of information, but this practice is now
discouraged; use ``SYMBOL_REF_FLAGS``.
The default definition of this hook, ``default_encode_section_info``
in :samp:`varasm.cc`, sets a number of commonly-useful bits in
``SYMBOL_REF_FLAGS``. Check whether the default does what you need
before overriding it.
.. hook-end
.. function:: const char * TARGET_STRIP_NAME_ENCODING (const char *name)
.. hook-start:TARGET_STRIP_NAME_ENCODING
Decode :samp:`{name}` and return the real name part, sans
the characters that ``TARGET_ENCODE_SECTION_INFO``
may have added.
.. hook-end
.. function:: bool TARGET_IN_SMALL_DATA_P (const_tree exp)
.. hook-start:TARGET_IN_SMALL_DATA_P
Returns true if :samp:`{exp}` should be placed into a 'small data' section.
The default version of this hook always returns false.
.. hook-end
.. c:var:: bool TARGET_HAVE_SRODATA_SECTION
.. hook-start:TARGET_HAVE_SRODATA_SECTION
Contains the value true if the target places read-only
'small data' into a separate section. The default value is false.
.. hook-end
.. function:: bool TARGET_PROFILE_BEFORE_PROLOGUE (void)
.. hook-start:TARGET_PROFILE_BEFORE_PROLOGUE
It returns true if target wants profile code emitted before prologue.
The default version of this hook use the target macro
``PROFILE_BEFORE_PROLOGUE``.
.. hook-end
.. function:: bool TARGET_BINDS_LOCAL_P (const_tree exp)
.. hook-start:TARGET_BINDS_LOCAL_P
Returns true if :samp:`{exp}` names an object for which name resolution
rules must resolve to the current 'module' (dynamic shared library
or executable image).
The default version of this hook implements the name resolution rules
for ELF, which has a looser model of global name binding than other
currently supported object file formats.
.. hook-end
.. c:var:: bool TARGET_HAVE_TLS
.. hook-start:TARGET_HAVE_TLS
Contains the value true if the target supports thread-local storage.
The default value is false.
.. hook-end
.. include:: tm.rst.in
:start-after: [TARGET_HAVE_TLS]
:end-before: [TARGET_HAVE_TLS]

113
gcc/doc/gccint/target-macros/emulating-tls.rst
View File

@ -22,104 +22,51 @@ object. To access the TLS object, a lookup function is provided
which, when given the address of the control object, will return the
address of the current thread's instance of the TLS object.
.. c:var:: const char * TARGET_EMUTLS_GET_ADDRESS
.. include:: tm.rst.in
:start-after: [TARGET_EMUTLS_GET_ADDRESS]
:end-before: [TARGET_EMUTLS_GET_ADDRESS]
.. hook-start:TARGET_EMUTLS_GET_ADDRESS
Contains the name of the helper function that uses a TLS control
object to locate a TLS instance. The default causes libgcc's
emulated TLS helper function to be used.
.. include:: tm.rst.in
:start-after: [TARGET_EMUTLS_REGISTER_COMMON]
:end-before: [TARGET_EMUTLS_REGISTER_COMMON]
.. hook-end
.. c:var:: const char * TARGET_EMUTLS_REGISTER_COMMON
.. include:: tm.rst.in
:start-after: [TARGET_EMUTLS_VAR_SECTION]
:end-before: [TARGET_EMUTLS_VAR_SECTION]
.. hook-start:TARGET_EMUTLS_REGISTER_COMMON
Contains the name of the helper function that should be used at
program startup to register TLS objects that are implicitly
initialized to zero. If this is ``NULL``, all TLS objects will
have explicit initializers. The default causes libgcc's emulated TLS
registration function to be used.
.. include:: tm.rst.in
:start-after: [TARGET_EMUTLS_TMPL_SECTION]
:end-before: [TARGET_EMUTLS_TMPL_SECTION]
.. hook-end
.. c:var:: const char * TARGET_EMUTLS_VAR_SECTION
.. include:: tm.rst.in
:start-after: [TARGET_EMUTLS_VAR_PREFIX]
:end-before: [TARGET_EMUTLS_VAR_PREFIX]
.. hook-start:TARGET_EMUTLS_VAR_SECTION
Contains the name of the section in which TLS control variables should
be placed. The default of ``NULL`` allows these to be placed in
any section.
.. include:: tm.rst.in
:start-after: [TARGET_EMUTLS_TMPL_PREFIX]
:end-before: [TARGET_EMUTLS_TMPL_PREFIX]
.. hook-end
.. c:var:: const char * TARGET_EMUTLS_TMPL_SECTION
.. include:: tm.rst.in
:start-after: [TARGET_EMUTLS_VAR_FIELDS]
:end-before: [TARGET_EMUTLS_VAR_FIELDS]
.. hook-start:TARGET_EMUTLS_TMPL_SECTION
Contains the name of the section in which TLS initializers should be
placed. The default of ``NULL`` allows these to be placed in any
section.
.. include:: tm.rst.in
:start-after: [TARGET_EMUTLS_VAR_INIT]
:end-before: [TARGET_EMUTLS_VAR_INIT]
.. hook-end
.. c:var:: const char * TARGET_EMUTLS_VAR_PREFIX
.. include:: tm.rst.in
:start-after: [TARGET_EMUTLS_VAR_ALIGN_FIXED]
:end-before: [TARGET_EMUTLS_VAR_ALIGN_FIXED]
.. hook-start:TARGET_EMUTLS_VAR_PREFIX
Contains the prefix to be prepended to TLS control variable names.
The default of ``NULL`` uses a target-specific prefix.
.. hook-end
.. c:var:: const char * TARGET_EMUTLS_TMPL_PREFIX
.. hook-start:TARGET_EMUTLS_TMPL_PREFIX
Contains the prefix to be prepended to TLS initializer objects. The
default of ``NULL`` uses a target-specific prefix.
.. hook-end
.. function:: tree TARGET_EMUTLS_VAR_FIELDS (tree type, tree *name)
.. hook-start:TARGET_EMUTLS_VAR_FIELDS
Specifies a function that generates the FIELD_DECLs for a TLS control
object type. :samp:`{type}` is the RECORD_TYPE the fields are for and
:samp:`{name}` should be filled with the structure tag, if the default of
``__emutls_object`` is unsuitable. The default creates a type suitable
for libgcc's emulated TLS function.
.. hook-end
.. function:: tree TARGET_EMUTLS_VAR_INIT (tree var, tree decl, tree tmpl_addr)
.. hook-start:TARGET_EMUTLS_VAR_INIT
Specifies a function that generates the CONSTRUCTOR to initialize a
TLS control object. :samp:`{var}` is the TLS control object, :samp:`{decl}`
is the TLS object and :samp:`{tmpl_addr}` is the address of the
initializer. The default initializes libgcc's emulated TLS control object.
.. hook-end
.. c:var:: bool TARGET_EMUTLS_VAR_ALIGN_FIXED
.. hook-start:TARGET_EMUTLS_VAR_ALIGN_FIXED
Specifies whether the alignment of TLS control variable objects is
fixed and should not be increased as some backends may do to optimize
single objects. The default is false.
.. hook-end
.. c:var:: bool TARGET_EMUTLS_DEBUG_FORM_TLS_ADDRESS
.. hook-start:TARGET_EMUTLS_DEBUG_FORM_TLS_ADDRESS
Specifies whether a DWARF ``DW_OP_form_tls_address`` location descriptor
may be used to describe emulated TLS control objects.
.. hook-end
.. include:: tm.rst.in
:start-after: [TARGET_EMUTLS_DEBUG_FORM_TLS_ADDRESS]
:end-before: [TARGET_EMUTLS_DEBUG_FORM_TLS_ADDRESS]

122
gcc/doc/gccint/target-macros/implementing-the-varargs-macros.rst
View File

@ -76,117 +76,31 @@ below.
These machine description macros help implement varargs:
.. function:: rtx TARGET_EXPAND_BUILTIN_SAVEREGS (void)
.. include:: tm.rst.in
:start-after: [TARGET_EXPAND_BUILTIN_SAVEREGS]
:end-before: [TARGET_EXPAND_BUILTIN_SAVEREGS]
.. hook-start:TARGET_EXPAND_BUILTIN_SAVEREGS
If defined, this hook produces the machine-specific code for a call to
``__builtin_saveregs``. This code will be moved to the very
beginning of the function, before any parameter access are made. The
return value of this function should be an RTX that contains the value
to use as the return of ``__builtin_saveregs``.
.. include:: tm.rst.in
:start-after: [TARGET_SETUP_INCOMING_VARARGS]
:end-before: [TARGET_SETUP_INCOMING_VARARGS]
.. hook-end
.. function:: void TARGET_SETUP_INCOMING_VARARGS (cumulative_args_t args_so_far, const function_arg_info &arg, int *pretend_args_size, int second_time)
.. include:: tm.rst.in
:start-after: [TARGET_STRICT_ARGUMENT_NAMING]
:end-before: [TARGET_STRICT_ARGUMENT_NAMING]
.. hook-start:TARGET_SETUP_INCOMING_VARARGS
This target hook offers an alternative to using
``__builtin_saveregs`` and defining the hook
``TARGET_EXPAND_BUILTIN_SAVEREGS``. Use it to store the anonymous
register arguments into the stack so that all the arguments appear to
have been passed consecutively on the stack. Once this is done, you can
use the standard implementation of varargs that works for machines that
pass all their arguments on the stack.
.. include:: tm.rst.in
:start-after: [TARGET_CALL_ARGS]
:end-before: [TARGET_CALL_ARGS]
The argument :samp:`{args_so_far}` points to the ``CUMULATIVE_ARGS`` data
structure, containing the values that are obtained after processing the
named arguments. The argument :samp:`{arg}` describes the last of these named
arguments. The argument :samp:`{arg}` should not be used if the function type
satisfies ``TYPE_NO_NAMED_ARGS_STDARG_P``, since in that case there are
no named arguments and all arguments are accessed with ``va_arg``.
The target hook should do two things: first, push onto the stack all the
argument registers *not* used for the named arguments, and second,
store the size of the data thus pushed into the ``int`` -valued
variable pointed to by :samp:`{pretend_args_size}`. The value that you
store here will serve as additional offset for setting up the stack
frame.
.. include:: tm.rst.in
:start-after: [TARGET_END_CALL_ARGS]
:end-before: [TARGET_END_CALL_ARGS]
Because you must generate code to push the anonymous arguments at
compile time without knowing their data types,
``TARGET_SETUP_INCOMING_VARARGS`` is only useful on machines that
have just a single category of argument register and use it uniformly
for all data types.
If the argument :samp:`{second_time}` is nonzero, it means that the
arguments of the function are being analyzed for the second time. This
happens for an inline function, which is not actually compiled until the
end of the source file. The hook ``TARGET_SETUP_INCOMING_VARARGS`` should
not generate any instructions in this case.
.. hook-end
.. function:: bool TARGET_STRICT_ARGUMENT_NAMING (cumulative_args_t ca)
.. hook-start:TARGET_STRICT_ARGUMENT_NAMING
Define this hook to return ``true`` if the location where a function
argument is passed depends on whether or not it is a named argument.
This hook controls how the :samp:`{named}` argument to ``TARGET_FUNCTION_ARG``
is set for varargs and stdarg functions. If this hook returns
``true``, the :samp:`{named}` argument is always true for named
arguments, and false for unnamed arguments. If it returns ``false``,
but ``TARGET_PRETEND_OUTGOING_VARARGS_NAMED`` returns ``true``,
then all arguments are treated as named. Otherwise, all named arguments
except the last are treated as named.
You need not define this hook if it always returns ``false``.
.. hook-end
.. function:: void TARGET_CALL_ARGS (rtx, tree)
.. hook-start:TARGET_CALL_ARGS
While generating RTL for a function call, this target hook is invoked once
for each argument passed to the function, either a register returned by
``TARGET_FUNCTION_ARG`` or a memory location. It is called just
before the point where argument registers are stored. The type of the
function to be called is also passed as the second argument; it is
``NULL_TREE`` for libcalls. The ``TARGET_END_CALL_ARGS`` hook is
invoked just after the code to copy the return reg has been emitted.
This functionality can be used to perform special setup of call argument
registers if a target needs it.
For functions without arguments, the hook is called once with ``pc_rtx``
passed instead of an argument register.
Most ports do not need to implement anything for this hook.
.. hook-end
.. function:: void TARGET_END_CALL_ARGS (void)
.. hook-start:TARGET_END_CALL_ARGS
This target hook is invoked while generating RTL for a function call,
just after the point where the return reg is copied into a pseudo. It
signals that all the call argument and return registers for the just
emitted call are now no longer in use.
Most ports do not need to implement anything for this hook.
.. hook-end
.. function:: bool TARGET_PRETEND_OUTGOING_VARARGS_NAMED (cumulative_args_t ca)
.. hook-start:TARGET_PRETEND_OUTGOING_VARARGS_NAMED
If you need to conditionally change ABIs so that one works with
``TARGET_SETUP_INCOMING_VARARGS``, but the other works like neither
``TARGET_SETUP_INCOMING_VARARGS`` nor ``TARGET_STRICT_ARGUMENT_NAMING`` was
defined, then define this hook to return ``true`` if
``TARGET_SETUP_INCOMING_VARARGS`` is used, ``false`` otherwise.
Otherwise, you should not define this hook.
.. hook-end
.. include:: tm.rst.in
:start-after: [TARGET_PRETEND_OUTGOING_VARARGS_NAMED]
:end-before: [TARGET_PRETEND_OUTGOING_VARARGS_NAMED]

52
gcc/doc/gccint/target-macros/implicit-calls-to-library-routines.rst
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@ -23,32 +23,15 @@ Here is an explanation of implicit calls to library routines.
.. index:: set_optab_libfunc, init_one_libfunc
.. function:: void TARGET_INIT_LIBFUNCS (void)
.. include:: tm.rst.in
:start-after: [TARGET_INIT_LIBFUNCS]
:end-before: [TARGET_INIT_LIBFUNCS]
.. hook-start:TARGET_INIT_LIBFUNCS
This hook should declare additional library routines or rename
existing ones, using the functions ``set_optab_libfunc`` and
``init_one_libfunc`` defined in :samp:`optabs.cc`.
``init_optabs`` calls this macro after initializing all the normal
library routines.
.. include:: tm.rst.in
:start-after: [TARGET_LIBFUNC_GNU_PREFIX]
:end-before: [TARGET_LIBFUNC_GNU_PREFIX]
The default is to do nothing. Most ports don't need to define this hook.
.. hook-end
.. c:var:: bool TARGET_LIBFUNC_GNU_PREFIX
.. hook-start:TARGET_LIBFUNC_GNU_PREFIX
If false (the default), internal library routines start with two
underscores. If set to true, these routines start with ``__gnu_``
instead. E.g., ``__muldi3`` changes to ``__gnu_muldi3``. This
currently only affects functions defined in :samp:`libgcc2.c`. If this
is set to true, the :samp:`tm.h` file must also
``#define LIBGCC2_GNU_PREFIX``.
.. hook-end
.. c:macro:: FLOAT_LIB_COMPARE_RETURNS_BOOL (mode, comparison)
@ -104,26 +87,15 @@ Here is an explanation of implicit calls to library routines.
``errno`` may not actually be a variable.) If you don't define this
macro, a reasonable default is used.
.. function:: bool TARGET_LIBC_HAS_FUNCTION (enum function_class fn_class, tree type)
.. include:: tm.rst.in
:start-after: [TARGET_LIBC_HAS_FUNCTION]
:end-before: [TARGET_LIBC_HAS_FUNCTION]
.. hook-start:TARGET_LIBC_HAS_FUNCTION
This hook determines whether a function from a class of functions
:samp:`{fn_class}` is present in the target C library. If :samp:`{type}` is NULL,
the caller asks for support for all standard (float, double, long double)
types. If :samp:`{type}` is non-NULL, the caller asks for support for a
specific type.
.. include:: tm.rst.in
:start-after: [TARGET_LIBC_HAS_FAST_FUNCTION]
:end-before: [TARGET_LIBC_HAS_FAST_FUNCTION]
.. hook-end
.. function:: bool TARGET_LIBC_HAS_FAST_FUNCTION (int fcode)
.. hook-start:TARGET_LIBC_HAS_FAST_FUNCTION
This hook determines whether a function from a class of functions
``(enum function_class)``:samp:`{fcode}` has a fast implementation.
.. hook-end
.. c:macro:: NEXT_OBJC_RUNTIME

14
gcc/doc/gccint/target-macros/layout-of-source-language-data-types.rst
View File

@ -146,18 +146,10 @@ languages, rather than to fundamental aspects of storage layout.
always override this default with the options :option:`-fsigned-char`
and :option:`-funsigned-char`.
.. function:: bool TARGET_DEFAULT_SHORT_ENUMS (void)
.. include:: tm.rst.in
:start-after: [TARGET_DEFAULT_SHORT_ENUMS]
:end-before: [TARGET_DEFAULT_SHORT_ENUMS]
.. hook-start:TARGET_DEFAULT_SHORT_ENUMS
This target hook should return true if the compiler should give an
``enum`` type only as many bytes as it takes to represent the range
of possible values of that type. It should return false if all
``enum`` types should be allocated like ``int``.
The default is to return false.
.. hook-end
.. c:macro:: SIZE_TYPE

1149
gcc/doc/gccint/target-macros/miscellaneous-parameters.rst
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80
gcc/doc/gccint/target-macros/mode-switching-instructions.rst
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@ -47,75 +47,31 @@ The following macros control mode switching optimizations:
represented as numbers 0 ... N - 1. N is used to specify that no mode
switch is needed / supplied.
.. function:: void TARGET_MODE_EMIT (int entity, int mode, int prev_mode, HARD_REG_SET regs_live)
.. include:: tm.rst.in
:start-after: [TARGET_MODE_EMIT]
:end-before: [TARGET_MODE_EMIT]
.. hook-start:TARGET_MODE_EMIT
Generate one or more insns to set :samp:`{entity}` to :samp:`{mode}`.
:samp:`{hard_reg_live}` is the set of hard registers live at the point where
the insn(s) are to be inserted. :samp:`{prev_moxde}` indicates the mode
to switch from. Sets of a lower numbered entity will be emitted before
sets of a higher numbered entity to a mode of the same or lower priority.
.. include:: tm.rst.in
:start-after: [TARGET_MODE_NEEDED]
:end-before: [TARGET_MODE_NEEDED]
.. hook-end
.. function:: int TARGET_MODE_NEEDED (int entity, rtx_insn *insn)
.. include:: tm.rst.in
:start-after: [TARGET_MODE_AFTER]
:end-before: [TARGET_MODE_AFTER]
.. hook-start:TARGET_MODE_NEEDED
:samp:`{entity}` is an integer specifying a mode-switched entity.
If ``OPTIMIZE_MODE_SWITCHING`` is defined, you must define this macro
to return an integer value not larger than the corresponding element
in ``NUM_MODES_FOR_MODE_SWITCHING``, to denote the mode that :samp:`{entity}`
must be switched into prior to the execution of :samp:`{insn}`.
.. include:: tm.rst.in
:start-after: [TARGET_MODE_ENTRY]
:end-before: [TARGET_MODE_ENTRY]
.. hook-end
.. function:: int TARGET_MODE_AFTER (int entity, int mode, rtx_insn *insn)
.. include:: tm.rst.in
:start-after: [TARGET_MODE_EXIT]
:end-before: [TARGET_MODE_EXIT]
.. hook-start:TARGET_MODE_AFTER
:samp:`{entity}` is an integer specifying a mode-switched entity.
If this macro is defined, it is evaluated for every :samp:`{insn}` during mode
switching. It determines the mode that an insn results
in (if different from the incoming mode).
.. hook-end
.. function:: int TARGET_MODE_ENTRY (int entity)
.. hook-start:TARGET_MODE_ENTRY
If this macro is defined, it is evaluated for every :samp:`{entity}` that
needs mode switching. It should evaluate to an integer, which is a mode
that :samp:`{entity}` is assumed to be switched to at function entry.
If ``TARGET_MODE_ENTRY`` is defined then ``TARGET_MODE_EXIT``
must be defined.
.. hook-end
.. function:: int TARGET_MODE_EXIT (int entity)
.. hook-start:TARGET_MODE_EXIT
If this macro is defined, it is evaluated for every :samp:`{entity}` that
needs mode switching. It should evaluate to an integer, which is a mode
that :samp:`{entity}` is assumed to be switched to at function exit.
If ``TARGET_MODE_EXIT`` is defined then ``TARGET_MODE_ENTRY``
must be defined.
.. hook-end
.. function:: int TARGET_MODE_PRIORITY (int entity, int n)
.. hook-start:TARGET_MODE_PRIORITY
This macro specifies the order in which modes for :samp:`{entity}`
are processed. 0 is the highest priority,
``NUM_MODES_FOR_MODE_SWITCHING[entity] - 1`` the lowest.
The value of the macro should be an integer designating a mode
for :samp:`{entity}`. For any fixed :samp:`{entity}`, ``mode_priority``
(:samp:`{entity}`, :samp:`{n}`) shall be a bijection in 0 ...
``num_modes_for_mode_switching[entity] - 1``.
.. hook-end
.. include:: tm.rst.in
:start-after: [TARGET_MODE_PRIORITY]
:end-before: [TARGET_MODE_PRIORITY]

57
gcc/doc/gccint/target-macros/parameters-for-precompiled-header-validity-checking.rst
View File

@ -10,54 +10,21 @@
Parameters for Precompiled Header Validity Checking
***************************************************
.. function:: void * TARGET_GET_PCH_VALIDITY (size_t *sz)
.. include:: tm.rst.in
:start-after: [TARGET_GET_PCH_VALIDITY]
:end-before: [TARGET_GET_PCH_VALIDITY]
.. hook-start:TARGET_GET_PCH_VALIDITY
This hook returns a pointer to the data needed by
``TARGET_PCH_VALID_P`` and sets
:samp:`*{sz}` to the size of the data in bytes.
.. include:: tm.rst.in
:start-after: [TARGET_PCH_VALID_P]
:end-before: [TARGET_PCH_VALID_P]
.. hook-end
.. function:: const char * TARGET_PCH_VALID_P (const void *data, size_t sz)
.. include:: tm.rst.in
:start-after: [TARGET_CHECK_PCH_TARGET_FLAGS]
:end-before: [TARGET_CHECK_PCH_TARGET_FLAGS]
.. hook-start:TARGET_PCH_VALID_P
This hook checks whether the options used to create a PCH file are
compatible with the current settings. It returns ``NULL``
if so and a suitable error message if not. Error messages will
be presented to the user and must be localized using :samp:`_({msg})`.
:samp:`{data}` is the data that was returned by ``TARGET_GET_PCH_VALIDITY``
when the PCH file was created and :samp:`{sz}` is the size of that data in bytes.
It's safe to assume that the data was created by the same version of the
compiler, so no format checking is needed.
The default definition of ``default_pch_valid_p`` should be
suitable for most targets.
.. hook-end
.. function:: const char * TARGET_CHECK_PCH_TARGET_FLAGS (int pch_flags)
.. hook-start:TARGET_CHECK_PCH_TARGET_FLAGS
If this hook is nonnull, the default implementation of
``TARGET_PCH_VALID_P`` will use it to check for compatible values
of ``target_flags``. :samp:`{pch_flags}` specifies the value that
``target_flags`` had when the PCH file was created. The return
value is the same as for ``TARGET_PCH_VALID_P``.
.. hook-end
.. function:: void TARGET_PREPARE_PCH_SAVE (void)
.. hook-start:TARGET_PREPARE_PCH_SAVE
Called before writing out a PCH file. If the target has some
garbage-collected data that needs to be in a particular state on PCH loads,
it can use this hook to enforce that state. Very few targets need
to do anything here.
.. hook-end
.. include:: tm.rst.in
:start-after: [TARGET_PREPARE_PCH_SAVE]
:end-before: [TARGET_PREPARE_PCH_SAVE]

465
gcc/doc/gccint/target-macros/register-classes.rst
View File

@ -221,60 +221,15 @@ in many of the tables described below.
looking for one that is valid, and will reload one or both registers
only if neither labeling works.
.. function:: reg_class_t TARGET_PREFERRED_RENAME_CLASS (reg_class_t rclass)
.. include:: tm.rst.in
:start-after: [TARGET_PREFERRED_RENAME_CLASS]
:end-before: [TARGET_PREFERRED_RENAME_CLASS]
.. hook-start:TARGET_PREFERRED_RENAME_CLASS
A target hook that places additional preference on the register
class to use when it is necessary to rename a register in class
:samp:`{rclass}` to another class, or perhaps :samp:`{NO_REGS}`, if no
preferred register class is found or hook ``preferred_rename_class``
is not implemented.
Sometimes returning a more restrictive class makes better code. For
example, on ARM, thumb-2 instructions using ``LO_REGS`` may be
smaller than instructions using ``GENERIC_REGS``. By returning
``LO_REGS`` from ``preferred_rename_class``, code size can
be reduced.
.. include:: tm.rst.in
:start-after: [TARGET_PREFERRED_RELOAD_CLASS]
:end-before: [TARGET_PREFERRED_RELOAD_CLASS]
.. hook-end
.. function:: reg_class_t TARGET_PREFERRED_RELOAD_CLASS (rtx x, reg_class_t rclass)
.. hook-start:TARGET_PREFERRED_RELOAD_CLASS
A target hook that places additional restrictions on the register class
to use when it is necessary to copy value :samp:`{x}` into a register in class
:samp:`{rclass}`. The value is a register class; perhaps :samp:`{rclass}`, or perhaps
another, smaller class.
The default version of this hook always returns value of ``rclass`` argument.
Sometimes returning a more restrictive class makes better code. For
example, on the 68000, when :samp:`{x}` is an integer constant that is in range
for a :samp:`moveq` instruction, the value of this macro is always
``DATA_REGS`` as long as :samp:`{rclass}` includes the data registers.
Requiring a data register guarantees that a :samp:`moveq` will be used.
One case where ``TARGET_PREFERRED_RELOAD_CLASS`` must not return
:samp:`{rclass}` is if :samp:`{x}` is a legitimate constant which cannot be
loaded into some register class. By returning ``NO_REGS`` you can
force :samp:`{x}` into a memory location. For example, rs6000 can load
immediate values into general-purpose registers, but does not have an
instruction for loading an immediate value into a floating-point
register, so ``TARGET_PREFERRED_RELOAD_CLASS`` returns ``NO_REGS`` when
:samp:`{x}` is a floating-point constant. If the constant can't be loaded
into any kind of register, code generation will be better if
``TARGET_LEGITIMATE_CONSTANT_P`` makes the constant illegitimate instead
of using ``TARGET_PREFERRED_RELOAD_CLASS``.
If an insn has pseudos in it after register allocation, reload will go
through the alternatives and call repeatedly ``TARGET_PREFERRED_RELOAD_CLASS``
to find the best one. Returning ``NO_REGS``, in this case, makes
reload add a ``!`` in front of the constraint: the x86 back-end uses
this feature to discourage usage of 387 registers when math is done in
the SSE registers (and vice versa).
.. hook-end
.. c:macro:: PREFERRED_RELOAD_CLASS (x, class)
@ -313,20 +268,10 @@ in many of the tables described below.
this feature to discourage usage of 387 registers when math is done in
the SSE registers (and vice versa).
.. function:: reg_class_t TARGET_PREFERRED_OUTPUT_RELOAD_CLASS (rtx x, reg_class_t rclass)
.. include:: tm.rst.in
:start-after: [TARGET_PREFERRED_OUTPUT_RELOAD_CLASS]
:end-before: [TARGET_PREFERRED_OUTPUT_RELOAD_CLASS]
.. hook-start:TARGET_PREFERRED_OUTPUT_RELOAD_CLASS
Like ``TARGET_PREFERRED_RELOAD_CLASS``, but for output reloads instead of
input reloads.
The default version of this hook always returns value of ``rclass``
argument.
You can also use ``TARGET_PREFERRED_OUTPUT_RELOAD_CLASS`` to discourage
reload from using some alternatives, like ``TARGET_PREFERRED_RELOAD_CLASS``.
.. hook-end
.. c:macro:: LIMIT_RELOAD_CLASS (mode, class)
@ -344,103 +289,10 @@ in many of the tables described below.
Don't define this macro unless the target machine has limitations which
require the macro to do something nontrivial.
.. function:: reg_class_t TARGET_SECONDARY_RELOAD (bool in_p, rtx x, reg_class_t reload_class, machine_mode reload_mode, secondary_reload_info *sri)
.. include:: tm.rst.in
:start-after: [TARGET_SECONDARY_RELOAD]
:end-before: [TARGET_SECONDARY_RELOAD]
.. hook-start:TARGET_SECONDARY_RELOAD
Many machines have some registers that cannot be copied directly to or
from memory or even from other types of registers. An example is the
:samp:`MQ` register, which on most machines, can only be copied to or
from general registers, but not memory. Below, we shall be using the
term 'intermediate register' when a move operation cannot be performed
directly, but has to be done by copying the source into the intermediate
register first, and then copying the intermediate register to the
destination. An intermediate register always has the same mode as
source and destination. Since it holds the actual value being copied,
reload might apply optimizations to re-use an intermediate register
and eliding the copy from the source when it can determine that the
intermediate register still holds the required value.
Another kind of secondary reload is required on some machines which
allow copying all registers to and from memory, but require a scratch
register for stores to some memory locations (e.g., those with symbolic
address on the RT, and those with certain symbolic address on the SPARC
when compiling PIC). Scratch registers need not have the same mode
as the value being copied, and usually hold a different value than
that being copied. Special patterns in the md file are needed to
describe how the copy is performed with the help of the scratch register;
these patterns also describe the number, register class(es) and mode(s)
of the scratch register(s).
In some cases, both an intermediate and a scratch register are required.
For input reloads, this target hook is called with nonzero :samp:`{in_p}`,
and :samp:`{x}` is an rtx that needs to be copied to a register of class
:samp:`{reload_class}` in :samp:`{reload_mode}`. For output reloads, this target
hook is called with zero :samp:`{in_p}`, and a register of class :samp:`{reload_class}`
needs to be copied to rtx :samp:`{x}` in :samp:`{reload_mode}`.
If copying a register of :samp:`{reload_class}` from/to :samp:`{x}` requires
an intermediate register, the hook ``secondary_reload`` should
return the register class required for this intermediate register.
If no intermediate register is required, it should return NO_REGS.
If more than one intermediate register is required, describe the one
that is closest in the copy chain to the reload register.
If scratch registers are needed, you also have to describe how to
perform the copy from/to the reload register to/from this
closest intermediate register. Or if no intermediate register is
required, but still a scratch register is needed, describe the
copy from/to the reload register to/from the reload operand :samp:`{x}`.
You do this by setting ``sri->icode`` to the instruction code of a pattern
in the md file which performs the move. Operands 0 and 1 are the output
and input of this copy, respectively. Operands from operand 2 onward are
for scratch operands. These scratch operands must have a mode, and a
single-register-class
.. [later: or memory]
output constraint.
When an intermediate register is used, the ``secondary_reload``
hook will be called again to determine how to copy the intermediate
register to/from the reload operand :samp:`{x}`, so your hook must also
have code to handle the register class of the intermediate operand.
.. [For later: maybe we'll allow multi-alternative reload patterns -
.. the port maintainer could name a mov<mode> pattern that has clobbers -
.. and match the constraints of input and output to determine the required
.. alternative. A restriction would be that constraints used to match
.. against reloads registers would have to be written as register class
.. constraints, or we need a new target macro / hook that tells us if an
.. arbitrary constraint can match an unknown register of a given class.
.. Such a macro / hook would also be useful in other places.]
:samp:`{x}` might be a pseudo-register or a ``subreg`` of a
pseudo-register, which could either be in a hard register or in memory.
Use ``true_regnum`` to find out; it will return -1 if the pseudo is
in memory and the hard register number if it is in a register.
Scratch operands in memory (constraint ``"=m"`` / ``"=&m"``) are
currently not supported. For the time being, you will have to continue
to use ``TARGET_SECONDARY_MEMORY_NEEDED`` for that purpose.
``copy_cost`` also uses this target hook to find out how values are
copied. If you want it to include some extra cost for the need to allocate
(a) scratch register(s), set ``sri->extra_cost`` to the additional cost.
Or if two dependent moves are supposed to have a lower cost than the sum
of the individual moves due to expected fortuitous scheduling and/or special
forwarding logic, you can set ``sri->extra_cost`` to a negative amount.
.. hook-end
.. c:macro:: SECONDARY_RELOAD_CLASS (class, mode, x)
SECONDARY_INPUT_RELOAD_CLASS (class, mode, x)
@ -502,19 +354,10 @@ in many of the tables described below.
intermediate storage. This case often occurs between floating-point and
general registers.
.. function:: bool TARGET_SECONDARY_MEMORY_NEEDED (machine_mode mode, reg_class_t class1, reg_class_t class2)
.. include:: tm.rst.in
:start-after: [TARGET_SECONDARY_MEMORY_NEEDED]
:end-before: [TARGET_SECONDARY_MEMORY_NEEDED]
.. hook-start:TARGET_SECONDARY_MEMORY_NEEDED
Certain machines have the property that some registers cannot be copied
to some other registers without using memory. Define this hook on
those machines to return true if objects of mode :samp:`{m}` in registers
of :samp:`{class1}` can only be copied to registers of class :samp:`{class2}` by
storing a register of :samp:`{class1}` into memory and loading that memory
location into a register of :samp:`{class2}`. The default definition returns
false for all inputs.
.. hook-end
.. c:macro:: SECONDARY_MEMORY_NEEDED_RTX (mode)
@ -526,87 +369,25 @@ in many of the tables described below.
Do not define this macro if you do not define
``TARGET_SECONDARY_MEMORY_NEEDED``.
.. function:: machine_mode TARGET_SECONDARY_MEMORY_NEEDED_MODE (machine_mode mode)
.. include:: tm.rst.in
:start-after: [TARGET_SECONDARY_MEMORY_NEEDED_MODE]
:end-before: [TARGET_SECONDARY_MEMORY_NEEDED_MODE]
.. hook-start:TARGET_SECONDARY_MEMORY_NEEDED_MODE
If ``TARGET_SECONDARY_MEMORY_NEEDED`` tells the compiler to use memory
when moving between two particular registers of mode :samp:`{mode}`,
this hook specifies the mode that the memory should have.
.. include:: tm.rst.in
:start-after: [TARGET_SELECT_EARLY_REMAT_MODES]
:end-before: [TARGET_SELECT_EARLY_REMAT_MODES]
The default depends on ``TARGET_LRA_P``. Without LRA, the default
is to use a word-sized mode for integral modes that are smaller than a
a word. This is right thing to do on most machines because it ensures
that all bits of the register are copied and prevents accesses to the
registers in a narrower mode, which some machines prohibit for
floating-point registers.
However, this default behavior is not correct on some machines, such as
the DEC Alpha, that store short integers in floating-point registers
differently than in integer registers. On those machines, the default
widening will not work correctly and you must define this hook to
suppress that widening in some cases. See the file :samp:`alpha.cc` for
details.
.. include:: tm.rst.in
:start-after: [TARGET_CLASS_LIKELY_SPILLED_P]
:end-before: [TARGET_CLASS_LIKELY_SPILLED_P]
With LRA, the default is to use :samp:`{mode}` unmodified.
.. hook-end
.. include:: tm.rst.in
:start-after: [TARGET_CLASS_MAX_NREGS]
:end-before: [TARGET_CLASS_MAX_NREGS]
.. function:: void TARGET_SELECT_EARLY_REMAT_MODES (sbitmap modes)
.. hook-start:TARGET_SELECT_EARLY_REMAT_MODES
On some targets, certain modes cannot be held in registers around a
standard ABI call and are relatively expensive to spill to the stack.
The early rematerialization pass can help in such cases by aggressively
recomputing values after calls, so that they don't need to be spilled.
This hook returns the set of such modes by setting the associated bits
in :samp:`{modes}`. The default implementation selects no modes, which has
the effect of disabling the early rematerialization pass.
.. hook-end
.. function:: bool TARGET_CLASS_LIKELY_SPILLED_P (reg_class_t rclass)
.. hook-start:TARGET_CLASS_LIKELY_SPILLED_P
A target hook which returns ``true`` if pseudos that have been assigned
to registers of class :samp:`{rclass}` would likely be spilled because
registers of :samp:`{rclass}` are needed for spill registers.
The default version of this target hook returns ``true`` if :samp:`{rclass}`
has exactly one register and ``false`` otherwise. On most machines, this
default should be used. For generally register-starved machines, such as
i386, or machines with right register constraints, such as SH, this hook
can be used to avoid excessive spilling.
This hook is also used by some of the global intra-procedural code
transformations to throtle code motion, to avoid increasing register
pressure.
.. hook-end
.. function:: unsigned char TARGET_CLASS_MAX_NREGS (reg_class_t rclass, machine_mode mode)
.. hook-start:TARGET_CLASS_MAX_NREGS
A target hook returns the maximum number of consecutive registers
of class :samp:`{rclass}` needed to hold a value of mode :samp:`{mode}`.
This is closely related to the macro ``TARGET_HARD_REGNO_NREGS``.
In fact, the value returned by ``TARGET_CLASS_MAX_NREGS (rclass,
mode)`` target hook should be the maximum value of
``TARGET_HARD_REGNO_NREGS (regno, mode)`` for all :samp:`{regno}`
values in the class :samp:`{rclass}`.
This target hook helps control the handling of multiple-word values
in the reload pass.
The default version of this target hook returns the size of :samp:`{mode}`
in words.
.. hook-end
.. c:macro:: CLASS_MAX_NREGS (class, mode)
@ -621,181 +402,61 @@ in many of the tables described below.
This macro helps control the handling of multiple-word values
in the reload pass.
.. function:: bool TARGET_CAN_CHANGE_MODE_CLASS (machine_mode from, machine_mode to, reg_class_t rclass)
.. include:: tm.rst.in
:start-after: [TARGET_CAN_CHANGE_MODE_CLASS]
:end-before: [TARGET_CAN_CHANGE_MODE_CLASS]
.. hook-start:TARGET_CAN_CHANGE_MODE_CLASS
This hook returns true if it is possible to bitcast values held in
registers of class :samp:`{rclass}` from mode :samp:`{from}` to mode :samp:`{to}`
and if doing so preserves the low-order bits that are common to both modes.
The result is only meaningful if :samp:`{rclass}` has registers that can hold
both ``from`` and ``to``. The default implementation returns true.
.. include:: tm.rst.in
:start-after: [TARGET_IRA_CHANGE_PSEUDO_ALLOCNO_CLASS]
:end-before: [TARGET_IRA_CHANGE_PSEUDO_ALLOCNO_CLASS]
As an example of when such bitcasting is invalid, loading 32-bit integer or
floating-point objects into floating-point registers on Alpha extends them
to 64 bits. Therefore loading a 64-bit object and then storing it as a
32-bit object does not store the low-order 32 bits, as would be the case
for a normal register. Therefore, :samp:`alpha.h` defines
``TARGET_CAN_CHANGE_MODE_CLASS`` to return:
.. code-block:: c++
.. include:: tm.rst.in
:start-after: [TARGET_LRA_P]
:end-before: [TARGET_LRA_P]
(GET_MODE_SIZE (from) == GET_MODE_SIZE (to)
|| !reg_classes_intersect_p (FLOAT_REGS, rclass))
Even if storing from a register in mode :samp:`{to}` would be valid,
if both :samp:`{from}` and ``raw_reg_mode`` for :samp:`{rclass}` are wider
than ``word_mode``, then we must prevent :samp:`{to}` narrowing the
mode. This happens when the middle-end assumes that it can load
or store pieces of an :samp:`{N}` -word pseudo, and that the pseudo will
eventually be allocated to :samp:`{N}` ``word_mode`` hard registers.
Failure to prevent this kind of mode change will result in the
entire ``raw_reg_mode`` being modified instead of the partial
value that the middle-end intended.
.. include:: tm.rst.in
:start-after: [TARGET_REGISTER_PRIORITY]
:end-before: [TARGET_REGISTER_PRIORITY]
.. hook-end
.. function:: reg_class_t TARGET_IRA_CHANGE_PSEUDO_ALLOCNO_CLASS (int, reg_class_t, reg_class_t)
.. include:: tm.rst.in
:start-after: [TARGET_REGISTER_USAGE_LEVELING_P]
:end-before: [TARGET_REGISTER_USAGE_LEVELING_P]
.. hook-start:TARGET_IRA_CHANGE_PSEUDO_ALLOCNO_CLASS
A target hook which can change allocno class for given pseudo from
allocno and best class calculated by IRA.
.. include:: tm.rst.in
:start-after: [TARGET_DIFFERENT_ADDR_DISPLACEMENT_P]
:end-before: [TARGET_DIFFERENT_ADDR_DISPLACEMENT_P]
The default version of this target hook always returns given class.
.. hook-end
.. include:: tm.rst.in
:start-after: [TARGET_CANNOT_SUBSTITUTE_MEM_EQUIV_P]
:end-before: [TARGET_CANNOT_SUBSTITUTE_MEM_EQUIV_P]
.. function:: bool TARGET_LRA_P (void)
.. hook-start:TARGET_LRA_P
.. include:: tm.rst.in
:start-after: [TARGET_LEGITIMIZE_ADDRESS_DISPLACEMENT]
:end-before: [TARGET_LEGITIMIZE_ADDRESS_DISPLACEMENT]
A target hook which returns true if we use LRA instead of reload pass.
The default version of this target hook returns true. New ports
should use LRA, and existing ports are encouraged to convert.
.. include:: tm.rst.in
:start-after: [TARGET_SPILL_CLASS]
:end-before: [TARGET_SPILL_CLASS]
.. hook-end
.. function:: int TARGET_REGISTER_PRIORITY (int)
.. include:: tm.rst.in
:start-after: [TARGET_ADDITIONAL_ALLOCNO_CLASS_P]
:end-before: [TARGET_ADDITIONAL_ALLOCNO_CLASS_P]
.. hook-start:TARGET_REGISTER_PRIORITY
A target hook which returns the register priority number to which the
register :samp:`{hard_regno}` belongs to. The bigger the number, the
more preferable the hard register usage (when all other conditions are
the same). This hook can be used to prefer some hard register over
others in LRA. For example, some x86-64 register usage needs
additional prefix which makes instructions longer. The hook can
return lower priority number for such registers make them less favorable
and as result making the generated code smaller.
.. include:: tm.rst.in
:start-after: [TARGET_CSTORE_MODE]
:end-before: [TARGET_CSTORE_MODE]
The default version of this target hook returns always zero.
.. hook-end
.. function:: bool TARGET_REGISTER_USAGE_LEVELING_P (void)
.. hook-start:TARGET_REGISTER_USAGE_LEVELING_P
A target hook which returns true if we need register usage leveling.
That means if a few hard registers are equally good for the
assignment, we choose the least used hard register. The register
usage leveling may be profitable for some targets. Don't use the
usage leveling for targets with conditional execution or targets
with big register files as it hurts if-conversion and cross-jumping
optimizations.
The default version of this target hook returns always false.
.. hook-end
.. function:: bool TARGET_DIFFERENT_ADDR_DISPLACEMENT_P (void)
.. hook-start:TARGET_DIFFERENT_ADDR_DISPLACEMENT_P
A target hook which returns true if an address with the same structure
can have different maximal legitimate displacement. For example, the
displacement can depend on memory mode or on operand combinations in
the insn.
The default version of this target hook returns always false.
.. hook-end
.. function:: bool TARGET_CANNOT_SUBSTITUTE_MEM_EQUIV_P (rtx subst)
.. hook-start:TARGET_CANNOT_SUBSTITUTE_MEM_EQUIV_P
A target hook which returns ``true`` if :samp:`{subst}` can't
substitute safely pseudos with equivalent memory values during
register allocation.
The default version of this target hook returns ``false``.
On most machines, this default should be used. For generally
machines with non orthogonal register usage for addressing, such
as SH, this hook can be used to avoid excessive spilling.
.. hook-end
.. function:: bool TARGET_LEGITIMIZE_ADDRESS_DISPLACEMENT (rtx *offset1, rtx *offset2, poly_int64 orig_offset, machine_mode mode)
.. hook-start:TARGET_LEGITIMIZE_ADDRESS_DISPLACEMENT
This hook tries to split address offset :samp:`{orig_offset}` into
two parts: one that should be added to the base address to create
a local anchor point, and an additional offset that can be applied
to the anchor to address a value of mode :samp:`{mode}`. The idea is that
the local anchor could be shared by other accesses to nearby locations.
The hook returns true if it succeeds, storing the offset of the
anchor from the base in :samp:`{offset1}` and the offset of the final address
from the anchor in :samp:`{offset2}`. The default implementation returns false.
.. hook-end
.. function:: reg_class_t TARGET_SPILL_CLASS (reg_class_t, machine_mode)
.. hook-start:TARGET_SPILL_CLASS
This hook defines a class of registers which could be used for spilling
pseudos of the given mode and class, or ``NO_REGS`` if only memory
should be used. Not defining this hook is equivalent to returning
``NO_REGS`` for all inputs.
.. hook-end
.. function:: bool TARGET_ADDITIONAL_ALLOCNO_CLASS_P (reg_class_t)
.. hook-start:TARGET_ADDITIONAL_ALLOCNO_CLASS_P
This hook should return ``true`` if given class of registers should
be an allocno class in any way. Usually RA uses only one register
class from all classes containing the same register set. In some
complicated cases, you need to have two or more such classes as
allocno ones for RA correct work. Not defining this hook is
equivalent to returning ``false`` for all inputs.
.. hook-end
.. function:: scalar_int_mode TARGET_CSTORE_MODE (enum insn_code icode)
.. hook-start:TARGET_CSTORE_MODE
This hook defines the machine mode to use for the boolean result of
conditional store patterns. The ICODE argument is the instruction code
for the cstore being performed. Not definiting this hook is the same
as accepting the mode encoded into operand 0 of the cstore expander
patterns.
.. hook-end
.. function:: int TARGET_COMPUTE_PRESSURE_CLASSES (enum reg_class *pressure_classes)
.. hook-start:TARGET_COMPUTE_PRESSURE_CLASSES
A target hook which lets a backend compute the set of pressure classes to
be used by those optimization passes which take register pressure into
account, as opposed to letting IRA compute them. It returns the number of
register classes stored in the array :samp:`{pressure_classes}`.
.. hook-end
.. include:: tm.rst.in
:start-after: [TARGET_COMPUTE_PRESSURE_CLASSES]
:end-before: [TARGET_COMPUTE_PRESSURE_CLASSES]

216
gcc/doc/gccint/target-macros/register-usage.rst
View File

@ -91,104 +91,34 @@ Registers have various characteristics.
.. index:: call-used register, call-clobbered register, call-saved register
.. function:: const predefined_function_abi & TARGET_FNTYPE_ABI (const_tree type)
.. include:: tm.rst.in
:start-after: [TARGET_FNTYPE_ABI]
:end-before: [TARGET_FNTYPE_ABI]
.. hook-start:TARGET_FNTYPE_ABI
Return the ABI used by a function with type :samp:`{type}` ; see the
definition of ``predefined_function_abi`` for details of the ABI
descriptor. Targets only need to define this hook if they support
interoperability between several ABIs in the same translation unit.
.. include:: tm.rst.in
:start-after: [TARGET_INSN_CALLEE_ABI]
:end-before: [TARGET_INSN_CALLEE_ABI]
.. hook-end
.. function:: const predefined_function_abi & TARGET_INSN_CALLEE_ABI (const rtx_insn *insn)
.. hook-start:TARGET_INSN_CALLEE_ABI
This hook returns a description of the ABI used by the target of
call instruction :samp:`{insn}` ; see the definition of
``predefined_function_abi`` for details of the ABI descriptor.
Only the global function ``insn_callee_abi`` should call this hook
directly.
Targets only need to define this hook if they support
interoperability between several ABIs in the same translation unit.
.. hook-end
.. index:: call-used register, call-clobbered register, call-saved register
.. function:: bool TARGET_HARD_REGNO_CALL_PART_CLOBBERED (unsigned int abi_id, unsigned int regno, machine_mode mode)
.. include:: tm.rst.in
:start-after: [TARGET_HARD_REGNO_CALL_PART_CLOBBERED]
:end-before: [TARGET_HARD_REGNO_CALL_PART_CLOBBERED]
.. hook-start:TARGET_HARD_REGNO_CALL_PART_CLOBBERED
ABIs usually specify that calls must preserve the full contents
of a particular register, or that calls can alter any part of a
particular register. This information is captured by the target macro
``CALL_REALLY_USED_REGISTERS``. However, some ABIs specify that calls
must preserve certain bits of a particular register but can alter others.
This hook should return true if this applies to at least one of the
registers in :samp:`(reg:{mode}{regno})`, and if as a result the
call would alter part of the :samp:`{mode}` value. For example, if a call
preserves the low 32 bits of a 64-bit hard register :samp:`{regno}` but can
clobber the upper 32 bits, this hook should return true for a 64-bit mode
but false for a 32-bit mode.
.. include:: tm.rst.in
:start-after: [TARGET_GET_MULTILIB_ABI_NAME]
:end-before: [TARGET_GET_MULTILIB_ABI_NAME]
The value of :samp:`{abi_id}` comes from the ``predefined_function_abi``
structure that describes the ABI of the call; see the definition of the
structure for more details. If (as is usual) the target uses the same ABI
for all functions in a translation unit, :samp:`{abi_id}` is always 0.
The default implementation returns false, which is correct
for targets that don't have partly call-clobbered registers.
.. hook-end
.. function:: const char * TARGET_GET_MULTILIB_ABI_NAME (void)
.. hook-start:TARGET_GET_MULTILIB_ABI_NAME
This hook returns name of multilib ABI name.
.. hook-end
.. index:: fixed_regs, call_used_regs, global_regs, reg_names, reg_class_contents
.. function:: void TARGET_CONDITIONAL_REGISTER_USAGE (void)
.. include:: tm.rst.in
:start-after: [TARGET_CONDITIONAL_REGISTER_USAGE]
:end-before: [TARGET_CONDITIONAL_REGISTER_USAGE]
.. hook-start:TARGET_CONDITIONAL_REGISTER_USAGE
This hook may conditionally modify five variables
``fixed_regs``, ``call_used_regs``, ``global_regs``,
``reg_names``, and ``reg_class_contents``, to take into account
any dependence of these register sets on target flags. The first three
of these are of type ``char []`` (interpreted as boolean vectors).
``global_regs`` is a ``const char *[]``, and
``reg_class_contents`` is a ``HARD_REG_SET``. Before the macro is
called, ``fixed_regs``, ``call_used_regs``,
``reg_class_contents``, and ``reg_names`` have been initialized
from ``FIXED_REGISTERS``, ``CALL_USED_REGISTERS``,
``REG_CLASS_CONTENTS``, and ``REGISTER_NAMES``, respectively.
``global_regs`` has been cleared, and any :option:`-ffixed-reg`,
:option:`-fcall-used-reg` and :option:`-fcall-saved-reg`
command options have been applied.
.. index:: disabling certain registers, controlling register usage
If the usage of an entire class of registers depends on the target
flags, you may indicate this to GCC by using this macro to modify
``fixed_regs`` and ``call_used_regs`` to 1 for each of the
registers in the classes which should not be used by GCC. Also make
``define_register_constraint`` s return ``NO_REGS`` for constraints
that shouldn't be used.
(However, if this class is not included in ``GENERAL_REGS`` and all
of the insn patterns whose constraints permit this class are
controlled by target switches, then GCC will automatically avoid using
these registers when the target switches are opposed to them.)
.. hook-end
.. c:macro:: INCOMING_REGNO (out)
@ -289,20 +219,10 @@ This section discusses the macros that describe which kinds of values
(specifically, which machine modes) each register can hold, and how many
consecutive registers are needed for a given mode.
.. function:: unsigned int TARGET_HARD_REGNO_NREGS (unsigned int regno, machine_mode mode)
.. include:: tm.rst.in
:start-after: [TARGET_HARD_REGNO_NREGS]
:end-before: [TARGET_HARD_REGNO_NREGS]
.. hook-start:TARGET_HARD_REGNO_NREGS
This hook returns the number of consecutive hard registers, starting
at register number :samp:`{regno}`, required to hold a value of mode
:samp:`{mode}`. This hook must never return zero, even if a register
cannot hold the requested mode - indicate that with
``TARGET_HARD_REGNO_MODE_OK`` and/or
``TARGET_CAN_CHANGE_MODE_CLASS`` instead.
The default definition returns the number of words in :samp:`{mode}`.
.. hook-end
.. c:macro:: HARD_REGNO_NREGS_HAS_PADDING (regno, mode)
@ -340,67 +260,10 @@ consecutive registers are needed for a given mode.
happens for example on SPARC 64-bit where the natural size of
floating-point registers is still 32-bit.
.. function:: bool TARGET_HARD_REGNO_MODE_OK (unsigned int regno, machine_mode mode)
.. include:: tm.rst.in
:start-after: [TARGET_HARD_REGNO_MODE_OK]
:end-before: [TARGET_HARD_REGNO_MODE_OK]
.. hook-start:TARGET_HARD_REGNO_MODE_OK
This hook returns true if it is permissible to store a value
of mode :samp:`{mode}` in hard register number :samp:`{regno}` (or in several
registers starting with that one). The default definition returns true
unconditionally.
You need not include code to check for the numbers of fixed registers,
because the allocation mechanism considers them to be always occupied.
.. index:: register pairs
On some machines, double-precision values must be kept in even/odd
register pairs. You can implement that by defining this hook to reject
odd register numbers for such modes.
The minimum requirement for a mode to be OK in a register is that the
:samp:`mov{mode}` instruction pattern support moves between the
register and other hard register in the same class and that moving a
value into the register and back out not alter it.
Since the same instruction used to move ``word_mode`` will work for
all narrower integer modes, it is not necessary on any machine for
this hook to distinguish between these modes, provided you define
patterns :samp:`movhi`, etc., to take advantage of this. This is
useful because of the interaction between ``TARGET_HARD_REGNO_MODE_OK``
and ``TARGET_MODES_TIEABLE_P`` ; it is very desirable for all integer
modes to be tieable.
Many machines have special registers for floating point arithmetic.
Often people assume that floating point machine modes are allowed only
in floating point registers. This is not true. Any registers that
can hold integers can safely *hold* a floating point machine
mode, whether or not floating arithmetic can be done on it in those
registers. Integer move instructions can be used to move the values.
On some machines, though, the converse is true: fixed-point machine
modes may not go in floating registers. This is true if the floating
registers normalize any value stored in them, because storing a
non-floating value there would garble it. In this case,
``TARGET_HARD_REGNO_MODE_OK`` should reject fixed-point machine modes in
floating registers. But if the floating registers do not automatically
normalize, if you can store any bit pattern in one and retrieve it
unchanged without a trap, then any machine mode may go in a floating
register, so you can define this hook to say so.
The primary significance of special floating registers is rather that
they are the registers acceptable in floating point arithmetic
instructions. However, this is of no concern to
``TARGET_HARD_REGNO_MODE_OK``. You handle it by writing the proper
constraints for those instructions.
On some machines, the floating registers are especially slow to access,
so that it is better to store a value in a stack frame than in such a
register if floating point arithmetic is not being done. As long as the
floating registers are not in class ``GENERAL_REGS``, they will not
be used unless some pattern's constraint asks for one.
.. hook-end
.. c:macro:: HARD_REGNO_RENAME_OK (from, to)
@ -413,40 +276,15 @@ consecutive registers are needed for a given mode.
The default is always nonzero.
.. function:: bool TARGET_MODES_TIEABLE_P (machine_mode mode1, machine_mode mode2)
.. include:: tm.rst.in
:start-after: [TARGET_MODES_TIEABLE_P]
:end-before: [TARGET_MODES_TIEABLE_P]
.. hook-start:TARGET_MODES_TIEABLE_P
This hook returns true if a value of mode :samp:`{mode1}` is accessible
in mode :samp:`{mode2}` without copying.
.. include:: tm.rst.in
:start-after: [TARGET_HARD_REGNO_SCRATCH_OK]
:end-before: [TARGET_HARD_REGNO_SCRATCH_OK]
If ``TARGET_HARD_REGNO_MODE_OK (r, mode1)`` and
``TARGET_HARD_REGNO_MODE_OK (r, mode2)`` are always
the same for any :samp:`{r}`, then
``TARGET_MODES_TIEABLE_P (mode1, mode2)``
should be true. If they differ for any :samp:`{r}`, you should define
this hook to return false unless some other mechanism ensures the
accessibility of the value in a narrower mode.
You should define this hook to return true in as many cases as
possible since doing so will allow GCC to perform better register
allocation. The default definition returns true unconditionally.
.. hook-end
.. function:: bool TARGET_HARD_REGNO_SCRATCH_OK (unsigned int regno)
.. hook-start:TARGET_HARD_REGNO_SCRATCH_OK
This target hook should return ``true`` if it is OK to use a hard register
:samp:`{regno}` as scratch reg in peephole2.
One common use of this macro is to prevent using of a register that
is not saved by a prologue in an interrupt handler.
The default version of this hook always returns ``true``.
.. hook-end
.. c:macro:: AVOID_CCMODE_COPIES

151
gcc/doc/gccint/target-macros/run-time-target-specification.rst
View File

@ -67,22 +67,20 @@ Here are run-time target specifications.
Variable extern int target_flagsThis variable is declared in :samp:`options.h`, which is included before
any target-specific headers.
.. c:var:: int TARGET_DEFAULT_TARGET_FLAGS
.. include:: tm.rst.in
:start-after: [TARGET_DEFAULT_TARGET_FLAGS]
:end-before: [TARGET_DEFAULT_TARGET_FLAGS]
.. hook-start:TARGET_DEFAULT_TARGET_FLAGS
.. hook-end
This variable specifies the initial value of ``target_flags``.
Its default setting is 0.
.. index:: optional hardware or system features, features, optional, in system conventions
.. function:: bool TARGET_HANDLE_OPTION (struct gcc_options *opts, struct gcc_options *opts_set, const struct cl_decoded_option *decoded, location_t loc)
.. include:: tm.rst.in
:start-after: [TARGET_HANDLE_OPTION]
:end-before: [TARGET_HANDLE_OPTION]
.. hook-start:TARGET_HANDLE_OPTION
.. hook-end
This hook is called whenever the user specifies one of the
target-specific options described by the :samp:`.opt` definition files
@ -96,11 +94,10 @@ any target-specific headers.
option was passed (``UNKNOWN_LOCATION`` except for options passed
via attributes).
.. function:: bool TARGET_HANDLE_C_OPTION (size_t code, const char *arg, int value)
.. include:: tm.rst.in
:start-after: [TARGET_HANDLE_C_OPTION]
:end-before: [TARGET_HANDLE_C_OPTION]
.. hook-start:TARGET_HANDLE_C_OPTION
.. hook-end
This target hook is called whenever the user specifies one of the
target-specific C language family options described by the :samp:`.opt`
@ -114,76 +111,35 @@ any target-specific headers.
only available in the C (and related language) front ends, then you
should use ``TARGET_HANDLE_C_OPTION`` instead.
.. function:: tree TARGET_OBJC_CONSTRUCT_STRING_OBJECT (tree string)
.. include:: tm.rst.in
:start-after: [TARGET_OBJC_CONSTRUCT_STRING_OBJECT]
:end-before: [TARGET_OBJC_CONSTRUCT_STRING_OBJECT]
.. hook-start:TARGET_OBJC_CONSTRUCT_STRING_OBJECT
Targets may provide a string object type that can be used within
and between C, C++ and their respective Objective-C dialects.
A string object might, for example, embed encoding and length information.
These objects are considered opaque to the compiler and handled as references.
An ideal implementation makes the composition of the string object
match that of the Objective-C ``NSString`` (``NXString`` for GNUStep),
allowing efficient interworking between C-only and Objective-C code.
If a target implements string objects then this hook should return a
reference to such an object constructed from the normal 'C' string
representation provided in :samp:`{string}`.
At present, the hook is used by Objective-C only, to obtain a
common-format string object when the target provides one.
.. include:: tm.rst.in
:start-after: [TARGET_OBJC_DECLARE_UNRESOLVED_CLASS_REFERENCE]
:end-before: [TARGET_OBJC_DECLARE_UNRESOLVED_CLASS_REFERENCE]
.. hook-end
.. function:: void TARGET_OBJC_DECLARE_UNRESOLVED_CLASS_REFERENCE (const char *classname)
.. include:: tm.rst.in
:start-after: [TARGET_OBJC_DECLARE_CLASS_DEFINITION]
:end-before: [TARGET_OBJC_DECLARE_CLASS_DEFINITION]
.. hook-start:TARGET_OBJC_DECLARE_UNRESOLVED_CLASS_REFERENCE
Declare that Objective C class :samp:`{classname}` is referenced
by the current TU.
.. include:: tm.rst.in
:start-after: [TARGET_STRING_OBJECT_REF_TYPE_P]
:end-before: [TARGET_STRING_OBJECT_REF_TYPE_P]
.. hook-end
.. function:: void TARGET_OBJC_DECLARE_CLASS_DEFINITION (const char *classname)
.. include:: tm.rst.in
:start-after: [TARGET_CHECK_STRING_OBJECT_FORMAT_ARG]
:end-before: [TARGET_CHECK_STRING_OBJECT_FORMAT_ARG]
.. hook-start:TARGET_OBJC_DECLARE_CLASS_DEFINITION
Declare that Objective C class :samp:`{classname}` is defined
by the current TU.
.. include:: tm.rst.in
:start-after: [TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE]
:end-before: [TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE]
.. hook-end
.. function:: bool TARGET_STRING_OBJECT_REF_TYPE_P (const_tree stringref)
.. hook-start:TARGET_STRING_OBJECT_REF_TYPE_P
If a target implements string objects then this hook should return
``true`` if :samp:`{stringref}` is a valid reference to such an object.
.. hook-end
.. function:: void TARGET_CHECK_STRING_OBJECT_FORMAT_ARG (tree format_arg, tree args_list)
.. hook-start:TARGET_CHECK_STRING_OBJECT_FORMAT_ARG
If a target implements string objects then this hook should
provide a facility to check the function arguments in :samp:`{args_list}`
against the format specifiers in :samp:`{format_arg}` where the type of
:samp:`{format_arg}` is one recognized as a valid string reference type.
.. hook-end
.. function:: void TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE (void)
.. hook-start:TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE
This target function is similar to the hook ``TARGET_OPTION_OVERRIDE``
but is called when the optimize level is changed via an attribute or
pragma or when it is reset at the end of the code affected by the
attribute or pragma. It is not called at the beginning of compilation
when ``TARGET_OPTION_OVERRIDE`` is called so if you want to perform these
actions then, you should have ``TARGET_OPTION_OVERRIDE`` call
``TARGET_OVERRIDE_OPTIONS_AFTER_CHANGE``.
.. hook-end
.. c:macro:: C_COMMON_OVERRIDE_OPTIONS
@ -193,11 +149,10 @@ any target-specific headers.
used to alter option flag variables which only exist in those
frontends.
.. c:var:: const struct default_options * TARGET_OPTION_OPTIMIZATION_TABLE
.. include:: tm.rst.in
:start-after: [TARGET_OPTION_OPTIMIZATION_TABLE]
:end-before: [TARGET_OPTION_OPTIMIZATION_TABLE]
.. hook-start:TARGET_OPTION_OPTIMIZATION_TABLE
.. hook-end
Some machines may desire to change what optimizations are performed for
various optimization levels. This variable, if defined, describes
@ -211,33 +166,15 @@ any target-specific headers.
options are changed via ``#pragma GCC optimize`` or by using the
``optimize`` attribute.
.. function:: void TARGET_OPTION_INIT_STRUCT (struct gcc_options *opts)
.. include:: tm.rst.in
:start-after: [TARGET_OPTION_INIT_STRUCT]
:end-before: [TARGET_OPTION_INIT_STRUCT]
.. hook-start:TARGET_OPTION_INIT_STRUCT
Set target-dependent initial values of fields in :samp:`{opts}`.
.. include:: tm.rst.in
:start-after: [TARGET_COMPUTE_MULTILIB]
:end-before: [TARGET_COMPUTE_MULTILIB]
.. hook-end
.. function:: const char * TARGET_COMPUTE_MULTILIB (const struct switchstr *switches, int n_switches, const char *multilib_dir, const char *multilib_defaults, const char *multilib_select, const char *multilib_matches, const char *multilib_exclusions, const char *multilib_reuse)
.. hook-start:TARGET_COMPUTE_MULTILIB
Some targets like RISC-V might have complicated multilib reuse rules which
are hard to implement with the current multilib scheme. This hook allows
targets to override the result from the built-in multilib mechanism.
:samp:`{switches}` is the raw option list with :samp:`{n_switches}` items;
:samp:`{multilib_dir}` is the multi-lib result which is computed by the built-in
multi-lib mechanism;
:samp:`{multilib_defaults}` is the default options list for multi-lib;
:samp:`{multilib_select}` is the string containing the list of supported
multi-libs, and the option checking list.
:samp:`{multilib_matches}`, :samp:`{multilib_exclusions}`, and :samp:`{multilib_reuse}`
are corresponding to :samp:`{MULTILIB_MATCHES}`, :samp:`{MULTILIB_EXCLUSIONS}`,
and :samp:`{MULTILIB_REUSE}`.
The default definition does nothing but return :samp:`{multilib_dir}` directly.
.. hook-end
.. c:macro:: SWITCHABLE_TARGET
@ -258,16 +195,6 @@ any target-specific headers.
Define this macro to 1 if your target needs this facility. The default
is 0.
.. function:: bool TARGET_FLOAT_EXCEPTIONS_ROUNDING_SUPPORTED_P (void)
.. hook-start:TARGET_FLOAT_EXCEPTIONS_ROUNDING_SUPPORTED_P
Returns true if the target supports IEEE 754 floating-point exceptions
and rounding modes, false otherwise. This is intended to relate to the
``float`` and ``double`` types, but not necessarily ``long double``.
By default, returns true if the ``adddf3`` instruction pattern is
available and false otherwise, on the assumption that hardware floating
point supports exceptions and rounding modes but software floating point
does not.
.. hook-end
.. include:: tm.rst.in
:start-after: [TARGET_FLOAT_EXCEPTIONS_ROUNDING_SUPPORTED_P]
:end-before: [TARGET_FLOAT_EXCEPTIONS_ROUNDING_SUPPORTED_P]

70
gcc/doc/gccint/target-macros/stack-layout-and-calling-conventions/basic-stack-layout.rst
View File

@ -45,17 +45,10 @@ Here is the basic stack layout.
Define this macro if successive arguments to a function occupy decreasing
addresses on the stack.
.. function:: HOST_WIDE_INT TARGET_STARTING_FRAME_OFFSET (void)
.. include:: ../tm.rst.in
:start-after: [TARGET_STARTING_FRAME_OFFSET]
:end-before: [TARGET_STARTING_FRAME_OFFSET]
.. hook-start:TARGET_STARTING_FRAME_OFFSET
This hook returns the offset from the frame pointer to the first local
variable slot to be allocated. If ``FRAME_GROWS_DOWNWARD``, it is the
offset to *end* of the first slot allocated, otherwise it is the
offset to *beginning* of the first slot allocated. The default
implementation returns 0.
.. hook-end
.. c:macro:: STACK_ALIGNMENT_NEEDED
@ -122,17 +115,10 @@ Here is the basic stack layout.
before we can access arbitrary stack frames. You will seldom need to
define this macro. The default is to do nothing.
.. function:: rtx TARGET_BUILTIN_SETJMP_FRAME_VALUE (void)
.. include:: ../tm.rst.in
:start-after: [TARGET_BUILTIN_SETJMP_FRAME_VALUE]
:end-before: [TARGET_BUILTIN_SETJMP_FRAME_VALUE]
.. hook-start:TARGET_BUILTIN_SETJMP_FRAME_VALUE
This target hook should return an rtx that is used to store
the address of the current frame into the built in ``setjmp`` buffer.
The default value, ``virtual_stack_vars_rtx``, is correct for most
machines. One reason you may need to define this target hook is if
``hard_frame_pointer_rtx`` is the appropriate value on your machine.
.. hook-end
.. c:macro:: FRAME_ADDR_RTX (frameaddr)
@ -200,47 +186,15 @@ Here is the basic stack layout.
and advertise when generating dwarf debug information, in absence of
an explicit :option:`-gdwarf-version` option on the command line.
.. function:: void TARGET_DWARF_HANDLE_FRAME_UNSPEC (const char *label, rtx pattern, int index)
.. include:: ../tm.rst.in
:start-after: [TARGET_DWARF_HANDLE_FRAME_UNSPEC]
:end-before: [TARGET_DWARF_HANDLE_FRAME_UNSPEC]
.. hook-start:TARGET_DWARF_HANDLE_FRAME_UNSPEC
This target hook allows the backend to emit frame-related insns that
contain UNSPECs or UNSPEC_VOLATILEs. The DWARF 2 call frame debugging
info engine will invoke it on insns of the form
.. include:: ../tm.rst.in
:start-after: [TARGET_DWARF_POLY_INDETERMINATE_VALUE]
:end-before: [TARGET_DWARF_POLY_INDETERMINATE_VALUE]
.. code-block:: c++
(set (reg) (unspec [...] UNSPEC_INDEX))
and
.. code-block:: c++
(set (reg) (unspec_volatile [...] UNSPECV_INDEX)).
to let the backend emit the call frame instructions. :samp:`{label}` is
the CFI label attached to the insn, :samp:`{pattern}` is the pattern of
the insn and :samp:`{index}` is ``UNSPEC_INDEX`` or ``UNSPECV_INDEX``.
.. hook-end
.. function:: unsigned int TARGET_DWARF_POLY_INDETERMINATE_VALUE (unsigned int i, unsigned int *factor, int *offset)
.. hook-start:TARGET_DWARF_POLY_INDETERMINATE_VALUE
Express the value of ``poly_int`` indeterminate :samp:`{i}` as a DWARF
expression, with :samp:`{i}` counting from 1. Return the number of a DWARF
register :samp:`{R}` and set :samp:`*{factor}` and :samp:`*{offset}` such
that the value of the indeterminate is:
.. code-block:: c++
value_of(R) / factor - offset
A target only needs to define this hook if it sets
:samp:`NUM_POLY_INT_COEFFS` to a value greater than 1.
.. hook-end
.. c:macro:: INCOMING_FRAME_SP_OFFSET

60
gcc/doc/gccint/target-macros/stack-layout-and-calling-conventions/eliminating-frame-pointer-and-arg-pointer.rst
View File

@ -12,34 +12,10 @@ Eliminating Frame Pointer and Arg Pointer
This is about eliminating the frame pointer and arg pointer.
.. function:: bool TARGET_FRAME_POINTER_REQUIRED (void)
.. include:: ../tm.rst.in
:start-after: [TARGET_FRAME_POINTER_REQUIRED]
:end-before: [TARGET_FRAME_POINTER_REQUIRED]
.. hook-start:TARGET_FRAME_POINTER_REQUIRED
This target hook should return ``true`` if a function must have and use
a frame pointer. This target hook is called in the reload pass. If its return
value is ``true`` the function will have a frame pointer.
This target hook can in principle examine the current function and decide
according to the facts, but on most machines the constant ``false`` or the
constant ``true`` suffices. Use ``false`` when the machine allows code
to be generated with no frame pointer, and doing so saves some time or space.
Use ``true`` when there is no possible advantage to avoiding a frame
pointer.
In certain cases, the compiler does not know how to produce valid code
without a frame pointer. The compiler recognizes those cases and
automatically gives the function a frame pointer regardless of what
``targetm.frame_pointer_required`` returns. You don't need to worry about
them.
In a function that does not require a frame pointer, the frame pointer
register can be allocated for ordinary usage, unless you mark it as a
fixed register. See ``FIXED_REGISTERS`` for more information.
Default return value is ``false``.
.. hook-end
.. c:macro:: ELIMINABLE_REGS
@ -67,19 +43,10 @@ This is about eliminating the frame pointer and arg pointer.
Note that the elimination of the argument pointer with the stack pointer is
specified first since that is the preferred elimination.
.. function:: bool TARGET_CAN_ELIMINATE (const int from_reg, const int to_reg)
.. include:: ../tm.rst.in
:start-after: [TARGET_CAN_ELIMINATE]
:end-before: [TARGET_CAN_ELIMINATE]
.. hook-start:TARGET_CAN_ELIMINATE
This target hook should return ``true`` if the compiler is allowed to
try to replace register number :samp:`{from_reg}` with register number
:samp:`{to_reg}`. This target hook will usually be ``true``, since most of the
cases preventing register elimination are things that the compiler already
knows about.
Default return value is ``true``.
.. hook-end
.. c:macro:: INITIAL_ELIMINATION_OFFSET (from_reg, to_reg, offset_var)
@ -88,15 +55,6 @@ This is about eliminating the frame pointer and arg pointer.
such as the result of ``get_frame_size ()`` and the tables of
registers ``df_regs_ever_live_p`` and ``call_used_regs``.
.. function:: void TARGET_COMPUTE_FRAME_LAYOUT (void)
.. hook-start:TARGET_COMPUTE_FRAME_LAYOUT
This target hook is called once each time the frame layout needs to be
recalculated. The calculations can be cached by the target and can then
be used by ``INITIAL_ELIMINATION_OFFSET`` instead of re-computing the
layout on every invocation of that hook. This is particularly useful
for targets that have an expensive frame layout function. Implementing
this callback is optional.
.. hook-end
.. include:: ../tm.rst.in
:start-after: [TARGET_COMPUTE_FRAME_LAYOUT]
:end-before: [TARGET_COMPUTE_FRAME_LAYOUT]

203
gcc/doc/gccint/target-macros/stack-layout-and-calling-conventions/function-entry-and-exit.rst
View File

@ -13,142 +13,30 @@ Function Entry and Exit
This section describes the macros that output function entry
(:dfn:`prologue`) and exit (:dfn:`epilogue`) code.
.. function:: void TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY (FILE *file, unsigned HOST_WIDE_INT patch_area_size, bool record_p)
.. include:: ../tm.rst.in
:start-after: [TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY]
:end-before: [TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY]
.. hook-start:TARGET_ASM_PRINT_PATCHABLE_FUNCTION_ENTRY
Generate a patchable area at the function start, consisting of
:samp:`{patch_area_size}` NOP instructions. If the target supports named
sections and if :samp:`{record_p}` is true, insert a pointer to the current
location in the table of patchable functions. The default implementation
of the hook places the table of pointers in the special section named
``__patchable_function_entries``.
.. include:: ../tm.rst.in
:start-after: [TARGET_ASM_FUNCTION_PROLOGUE]
:end-before: [TARGET_ASM_FUNCTION_PROLOGUE]
.. hook-end
.. function:: void TARGET_ASM_FUNCTION_PROLOGUE (FILE *file)
.. include:: ../tm.rst.in
:start-after: [TARGET_ASM_FUNCTION_END_PROLOGUE]
:end-before: [TARGET_ASM_FUNCTION_END_PROLOGUE]
.. hook-start:TARGET_ASM_FUNCTION_PROLOGUE
If defined, a function that outputs the assembler code for entry to a
function. The prologue is responsible for setting up the stack frame,
initializing the frame pointer register, saving registers that must be
saved, and allocating :samp:`{size}` additional bytes of storage for the
local variables. :samp:`{file}` is a stdio stream to which the assembler
code should be output.
.. include:: ../tm.rst.in
:start-after: [TARGET_ASM_FUNCTION_BEGIN_EPILOGUE]
:end-before: [TARGET_ASM_FUNCTION_BEGIN_EPILOGUE]
The label for the beginning of the function need not be output by this
macro. That has already been done when the macro is run.
.. index:: regs_ever_live
.. include:: ../tm.rst.in
:start-after: [TARGET_ASM_FUNCTION_EPILOGUE]
:end-before: [TARGET_ASM_FUNCTION_EPILOGUE]
To determine which registers to save, the macro can refer to the array
``regs_ever_live`` : element :samp:`{r}` is nonzero if hard register
:samp:`{r}` is used anywhere within the function. This implies the function
prologue should save register :samp:`{r}`, provided it is not one of the
call-used registers. (``TARGET_ASM_FUNCTION_EPILOGUE`` must likewise use
``regs_ever_live``.)
On machines that have 'register windows', the function entry code does
not save on the stack the registers that are in the windows, even if
they are supposed to be preserved by function calls; instead it takes
appropriate steps to 'push' the register stack, if any non-call-used
registers are used in the function.
.. index:: frame_pointer_needed
On machines where functions may or may not have frame-pointers, the
function entry code must vary accordingly; it must set up the frame
pointer if one is wanted, and not otherwise. To determine whether a
frame pointer is in wanted, the macro can refer to the variable
``frame_pointer_needed``. The variable's value will be 1 at run
time in a function that needs a frame pointer. See :ref:`elimination`.
The function entry code is responsible for allocating any stack space
required for the function. This stack space consists of the regions
listed below. In most cases, these regions are allocated in the
order listed, with the last listed region closest to the top of the
stack (the lowest address if ``STACK_GROWS_DOWNWARD`` is defined, and
the highest address if it is not defined). You can use a different order
for a machine if doing so is more convenient or required for
compatibility reasons. Except in cases where required by standard
or by a debugger, there is no reason why the stack layout used by GCC
need agree with that used by other compilers for a machine.
.. hook-end
.. function:: void TARGET_ASM_FUNCTION_END_PROLOGUE (FILE *file)
.. hook-start:TARGET_ASM_FUNCTION_END_PROLOGUE
If defined, a function that outputs assembler code at the end of a
prologue. This should be used when the function prologue is being
emitted as RTL, and you have some extra assembler that needs to be
emitted. See :ref:`prologue-instruction-pattern`.
.. hook-end
.. function:: void TARGET_ASM_FUNCTION_BEGIN_EPILOGUE (FILE *file)
.. hook-start:TARGET_ASM_FUNCTION_BEGIN_EPILOGUE
If defined, a function that outputs assembler code at the start of an
epilogue. This should be used when the function epilogue is being
emitted as RTL, and you have some extra assembler that needs to be
emitted. See :ref:`epilogue-instruction-pattern`.
.. hook-end
.. function:: void TARGET_ASM_FUNCTION_EPILOGUE (FILE *file)
.. hook-start:TARGET_ASM_FUNCTION_EPILOGUE
If defined, a function that outputs the assembler code for exit from a
function. The epilogue is responsible for restoring the saved
registers and stack pointer to their values when the function was
called, and returning control to the caller. This macro takes the
same argument as the macro ``TARGET_ASM_FUNCTION_PROLOGUE``, and the
registers to restore are determined from ``regs_ever_live`` and
``CALL_USED_REGISTERS`` in the same way.
On some machines, there is a single instruction that does all the work
of returning from the function. On these machines, give that
instruction the name :samp:`return` and do not define the macro
``TARGET_ASM_FUNCTION_EPILOGUE`` at all.
Do not define a pattern named :samp:`return` if you want the
``TARGET_ASM_FUNCTION_EPILOGUE`` to be used. If you want the target
switches to control whether return instructions or epilogues are used,
define a :samp:`return` pattern with a validity condition that tests the
target switches appropriately. If the :samp:`return` pattern's validity
condition is false, epilogues will be used.
On machines where functions may or may not have frame-pointers, the
function exit code must vary accordingly. Sometimes the code for these
two cases is completely different. To determine whether a frame pointer
is wanted, the macro can refer to the variable
``frame_pointer_needed``. The variable's value will be 1 when compiling
a function that needs a frame pointer.
Normally, ``TARGET_ASM_FUNCTION_PROLOGUE`` and
``TARGET_ASM_FUNCTION_EPILOGUE`` must treat leaf functions specially.
The C variable ``current_function_is_leaf`` is nonzero for such a
function. See :ref:`leaf-functions`.
On some machines, some functions pop their arguments on exit while
others leave that for the caller to do. For example, the 68020 when
given :option:`-mrtd` pops arguments in functions that take a fixed
number of arguments.
.. index:: pops_args, crtl->args.pops_args
Your definition of the macro ``RETURN_POPS_ARGS`` decides which
functions pop their own arguments. ``TARGET_ASM_FUNCTION_EPILOGUE``
needs to know what was decided. The number of bytes of the current
function's arguments that this function should pop is available in
``crtl->args.pops_args``. See :ref:`scalar-return`.
.. hook-end
*
.. index:: pretend_args_size, crtl->args.pretend_args_size
@ -206,60 +94,11 @@ This section describes the macros that output function entry
used by the exception handling mechanism, and so should be considered live
on entry to an exception edge.
.. function:: void TARGET_ASM_OUTPUT_MI_THUNK (FILE *file, tree thunk_fndecl, HOST_WIDE_INT delta, HOST_WIDE_INT vcall_offset, tree function)
.. include:: ../tm.rst.in
:start-after: [TARGET_ASM_OUTPUT_MI_THUNK]
:end-before: [TARGET_ASM_OUTPUT_MI_THUNK]
.. hook-start:TARGET_ASM_OUTPUT_MI_THUNK
A function that outputs the assembler code for a thunk
function, used to implement C++ virtual function calls with multiple
inheritance. The thunk acts as a wrapper around a virtual function,
adjusting the implicit object parameter before handing control off to
the real function.
First, emit code to add the integer :samp:`{delta}` to the location that
contains the incoming first argument. Assume that this argument
contains a pointer, and is the one used to pass the ``this`` pointer
in C++. This is the incoming argument *before* the function prologue,
e.g. :samp:`%o0` on a sparc. The addition must preserve the values of
all other incoming arguments.
Then, if :samp:`{vcall_offset}` is nonzero, an additional adjustment should be
made after adding ``delta``. In particular, if :samp:`{p}` is the
adjusted pointer, the following adjustment should be made:
.. code-block:: c++
p += (*((ptrdiff_t **)p))[vcall_offset/sizeof(ptrdiff_t)]
After the additions, emit code to jump to :samp:`{function}`, which is a
``FUNCTION_DECL``. This is a direct pure jump, not a call, and does
not touch the return address. Hence returning from :samp:`{FUNCTION}` will
return to whoever called the current :samp:`thunk`.
The effect must be as if :samp:`{function}` had been called directly with
the adjusted first argument. This macro is responsible for emitting all
of the code for a thunk function; ``TARGET_ASM_FUNCTION_PROLOGUE``
and ``TARGET_ASM_FUNCTION_EPILOGUE`` are not invoked.
The :samp:`{thunk_fndecl}` is redundant. (:samp:`{delta}` and :samp:`{function}`
have already been extracted from it.) It might possibly be useful on
some targets, but probably not.
If you do not define this macro, the target-independent code in the C++
front end will generate a less efficient heavyweight thunk that calls
:samp:`{function}` instead of jumping to it. The generic approach does
not support varargs.
.. hook-end
.. function:: bool TARGET_ASM_CAN_OUTPUT_MI_THUNK (const_tree thunk_fndecl, HOST_WIDE_INT delta, HOST_WIDE_INT vcall_offset, const_tree function)
.. hook-start:TARGET_ASM_CAN_OUTPUT_MI_THUNK
A function that returns true if TARGET_ASM_OUTPUT_MI_THUNK would be able
to output the assembler code for the thunk function specified by the
arguments it is passed, and false otherwise. In the latter case, the
generic approach will be used by the C++ front end, with the limitations
previously exposed.
.. hook-end
.. include:: ../tm.rst.in
:start-after: [TARGET_ASM_CAN_OUTPUT_MI_THUNK]
:end-before: [TARGET_ASM_CAN_OUTPUT_MI_THUNK]

14
gcc/doc/gccint/target-macros/stack-layout-and-calling-conventions/generating-code-for-profiling.rst
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@ -48,14 +48,6 @@ These macros will help you generate code for profiling.
Define this macro if the code for function profiling should come before
the function prologue. Normally, the profiling code comes after.
.. function:: bool TARGET_KEEP_LEAF_WHEN_PROFILED (void)
.. hook-start:TARGET_KEEP_LEAF_WHEN_PROFILED
This target hook returns true if the target wants the leaf flag for
the current function to stay true even if it calls mcount. This might
make sense for targets using the leaf flag only to determine whether a
stack frame needs to be generated or not and for which the call to
mcount is generated before the function prologue.
.. hook-end
.. include:: ../tm.rst.in
:start-after: [TARGET_KEEP_LEAF_WHEN_PROFILED]
:end-before: [TARGET_KEEP_LEAF_WHEN_PROFILED]

95
gcc/doc/gccint/target-macros/stack-layout-and-calling-conventions/how-large-values-are-returned.rst
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@ -20,28 +20,10 @@ address`.
This section describes how to control returning structure values in
memory.
.. function:: bool TARGET_RETURN_IN_MEMORY (const_tree type, const_tree fntype)
.. include:: ../tm.rst.in
:start-after: [TARGET_RETURN_IN_MEMORY]
:end-before: [TARGET_RETURN_IN_MEMORY]
.. hook-start:TARGET_RETURN_IN_MEMORY
This target hook should return a nonzero value to say to return the
function value in memory, just as large structures are always returned.
Here :samp:`{type}` will be the data type of the value, and :samp:`{fntype}`
will be the type of the function doing the returning, or ``NULL`` for
libcalls.
Note that values of mode ``BLKmode`` must be explicitly handled
by this function. Also, the option :option:`-fpcc-struct-return`
takes effect regardless of this macro. On most systems, it is
possible to leave the hook undefined; this causes a default
definition to be used, whose value is the constant 1 for ``BLKmode``
values, and 0 otherwise.
Do not use this hook to indicate that structures and unions should always
be returned in memory. You should instead use ``DEFAULT_PCC_STRUCT_RETURN``
to indicate this.
.. hook-end
.. c:macro:: DEFAULT_PCC_STRUCT_RETURN
@ -54,32 +36,10 @@ memory.
If not defined, this defaults to the value 1.
.. function:: rtx TARGET_STRUCT_VALUE_RTX (tree fndecl, int incoming)
.. include:: ../tm.rst.in
:start-after: [TARGET_STRUCT_VALUE_RTX]
:end-before: [TARGET_STRUCT_VALUE_RTX]
.. hook-start:TARGET_STRUCT_VALUE_RTX
This target hook should return the location of the structure value
address (normally a ``mem`` or ``reg``), or 0 if the address is
passed as an 'invisible' first argument. Note that :samp:`{fndecl}` may
be ``NULL``, for libcalls. You do not need to define this target
hook if the address is always passed as an 'invisible' first
argument.
On some architectures the place where the structure value address
is found by the called function is not the same place that the
caller put it. This can be due to register windows, or it could
be because the function prologue moves it to a different place.
:samp:`{incoming}` is ``1`` or ``2`` when the location is needed in
the context of the called function, and ``0`` in the context of
the caller.
If :samp:`{incoming}` is nonzero and the address is to be found on the
stack, return a ``mem`` which refers to the frame pointer. If
:samp:`{incoming}` is ``2``, the result is being used to fetch the
structure value address at the beginning of a function. If you need
to emit adjusting code, you should do it at this point.
.. hook-end
.. c:macro:: PCC_STATIC_STRUCT_RETURN
@ -93,40 +53,21 @@ memory.
This macro has effect in :option:`-fpcc-struct-return` mode, but it does
nothing when you use :option:`-freg-struct-return` mode.
.. function:: fixed_size_mode TARGET_GET_RAW_RESULT_MODE (int regno)
.. include:: ../tm.rst.in
:start-after: [TARGET_GET_RAW_RESULT_MODE]
:end-before: [TARGET_GET_RAW_RESULT_MODE]
.. hook-start:TARGET_GET_RAW_RESULT_MODE
This target hook returns the mode to be used when accessing raw return
registers in ``__builtin_return``. Define this macro if the value
in :samp:`{reg_raw_mode}` is not correct.
.. include:: ../tm.rst.in
:start-after: [TARGET_GET_RAW_ARG_MODE]
:end-before: [TARGET_GET_RAW_ARG_MODE]
.. hook-end
.. function:: fixed_size_mode TARGET_GET_RAW_ARG_MODE (int regno)
.. include:: ../tm.rst.in
:start-after: [TARGET_EMPTY_RECORD_P]
:end-before: [TARGET_EMPTY_RECORD_P]
.. hook-start:TARGET_GET_RAW_ARG_MODE
This target hook returns the mode to be used when accessing raw argument
registers in ``__builtin_apply_args``. Define this macro if the value
in :samp:`{reg_raw_mode}` is not correct.
.. hook-end
.. function:: bool TARGET_EMPTY_RECORD_P (const_tree type)
.. hook-start:TARGET_EMPTY_RECORD_P
This target hook returns true if the type is an empty record. The default
is to return ``false``.
.. hook-end
.. function:: void TARGET_WARN_PARAMETER_PASSING_ABI (cumulative_args_t ca, tree type)
.. hook-start:TARGET_WARN_PARAMETER_PASSING_ABI
This target hook warns about the change in empty class parameter passing
ABI.
.. hook-end
.. include:: ../tm.rst.in
:start-after: [TARGET_WARN_PARAMETER_PASSING_ABI]
:end-before: [TARGET_WARN_PARAMETER_PASSING_ABI]

116
gcc/doc/gccint/target-macros/stack-layout-and-calling-conventions/how-scalar-function-values-are-returned.rst
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@ -13,52 +13,10 @@ How Scalar Function Values Are Returned
This section discusses the macros that control returning scalars as
values---values that can fit in registers.
.. function:: rtx TARGET_FUNCTION_VALUE (const_tree ret_type, const_tree fn_decl_or_type, bool outgoing)
.. include:: ../tm.rst.in
:start-after: [TARGET_FUNCTION_VALUE]
:end-before: [TARGET_FUNCTION_VALUE]
.. hook-start:TARGET_FUNCTION_VALUE
Define this to return an RTX representing the place where a function
returns or receives a value of data type :samp:`{ret_type}`, a tree node
representing a data type. :samp:`{fn_decl_or_type}` is a tree node
representing ``FUNCTION_DECL`` or ``FUNCTION_TYPE`` of a
function being called. If :samp:`{outgoing}` is false, the hook should
compute the register in which the caller will see the return value.
Otherwise, the hook should return an RTX representing the place where
a function returns a value.
On many machines, only ``TYPE_MODE (ret_type)`` is relevant.
(Actually, on most machines, scalar values are returned in the same
place regardless of mode.) The value of the expression is usually a
``reg`` RTX for the hard register where the return value is stored.
The value can also be a ``parallel`` RTX, if the return value is in
multiple places. See ``TARGET_FUNCTION_ARG`` for an explanation of the
``parallel`` form. Note that the callee will populate every
location specified in the ``parallel``, but if the first element of
the ``parallel`` contains the whole return value, callers will use
that element as the canonical location and ignore the others. The m68k
port uses this type of ``parallel`` to return pointers in both
:samp:`%a0` (the canonical location) and :samp:`%d0`.
If ``TARGET_PROMOTE_FUNCTION_RETURN`` returns true, you must apply
the same promotion rules specified in ``PROMOTE_MODE`` if
:samp:`{valtype}` is a scalar type.
If the precise function being called is known, :samp:`{func}` is a tree
node (``FUNCTION_DECL``) for it; otherwise, :samp:`{func}` is a null
pointer. This makes it possible to use a different value-returning
convention for specific functions when all their calls are
known.
Some target machines have 'register windows' so that the register in
which a function returns its value is not the same as the one in which
the caller sees the value. For such machines, you should return
different RTX depending on :samp:`{outgoing}`.
``TARGET_FUNCTION_VALUE`` is not used for return values with
aggregate data types, because these are returned in another way. See
``TARGET_STRUCT_VALUE_RTX`` and related macros, below.
.. hook-end
.. c:macro:: FUNCTION_VALUE (valtype, func)
@ -75,20 +33,10 @@ values---values that can fit in registers.
specially by the compiler and was not mentioned in the C code being
compiled.
.. function:: rtx TARGET_LIBCALL_VALUE (machine_mode mode, const_rtx fun)
.. include:: ../tm.rst.in
:start-after: [TARGET_LIBCALL_VALUE]
:end-before: [TARGET_LIBCALL_VALUE]
.. hook-start:TARGET_LIBCALL_VALUE
Define this hook if the back-end needs to know the name of the libcall
function in order to determine where the result should be returned.
The mode of the result is given by :samp:`{mode}` and the name of the called
library function is given by :samp:`{fun}`. The hook should return an RTX
representing the place where the library function result will be returned.
If this hook is not defined, then LIBCALL_VALUE will be used.
.. hook-end
.. c:macro:: FUNCTION_VALUE_REGNO_P (regno)
@ -111,24 +59,10 @@ values---values that can fit in registers.
This macro has been deprecated. Use ``TARGET_FUNCTION_VALUE_REGNO_P``
for a new target instead.
.. function:: bool TARGET_FUNCTION_VALUE_REGNO_P (const unsigned int regno)
.. include:: ../tm.rst.in
:start-after: [TARGET_FUNCTION_VALUE_REGNO_P]
:end-before: [TARGET_FUNCTION_VALUE_REGNO_P]
.. hook-start:TARGET_FUNCTION_VALUE_REGNO_P
A target hook that return ``true`` if :samp:`{regno}` is the number of a hard
register in which the values of called function may come back.
A register whose use for returning values is limited to serving as the
second of a pair (for a value of type ``double``, say) need not be
recognized by this target hook.
If the machine has register windows, so that the caller and the called
function use different registers for the return value, this target hook
should recognize only the caller's register numbers.
If this hook is not defined, then FUNCTION_VALUE_REGNO_P will be used.
.. hook-end
.. c:macro:: APPLY_RESULT_SIZE
@ -136,31 +70,11 @@ values---values that can fit in registers.
need more space than is implied by ``FUNCTION_VALUE_REGNO_P`` for
saving and restoring an arbitrary return value.
.. c:var:: bool TARGET_OMIT_STRUCT_RETURN_REG
.. include:: ../tm.rst.in
:start-after: [TARGET_OMIT_STRUCT_RETURN_REG]
:end-before: [TARGET_OMIT_STRUCT_RETURN_REG]
.. hook-start:TARGET_OMIT_STRUCT_RETURN_REG
Normally, when a function returns a structure by memory, the address
is passed as an invisible pointer argument, but the compiler also
arranges to return the address from the function like it would a normal
pointer return value. Define this to true if that behavior is
undesirable on your target.
.. hook-end
.. function:: bool TARGET_RETURN_IN_MSB (const_tree type)
.. hook-start:TARGET_RETURN_IN_MSB
This hook should return true if values of type :samp:`{type}` are returned
at the most significant end of a register (in other words, if they are
padded at the least significant end). You can assume that :samp:`{type}`
is returned in a register; the caller is required to check this.
Note that the register provided by ``TARGET_FUNCTION_VALUE`` must
be able to hold the complete return value. For example, if a 1-, 2-
or 3-byte structure is returned at the most significant end of a
4-byte register, ``TARGET_FUNCTION_VALUE`` should provide an
``SImode`` rtx.
.. hook-end
.. include:: ../tm.rst.in
:start-after: [TARGET_RETURN_IN_MSB]
:end-before: [TARGET_RETURN_IN_MSB]

17
gcc/doc/gccint/target-macros/stack-layout-and-calling-conventions/miscellaneous-register-hooks.rst
View File

@ -10,17 +10,6 @@
Miscellaneous register hooks
^^^^^^^^^^^^^^^^^^^^^^^^^^^^
.. c:var:: bool TARGET_CALL_FUSAGE_CONTAINS_NON_CALLEE_CLOBBERS
.. hook-start:TARGET_CALL_FUSAGE_CONTAINS_NON_CALLEE_CLOBBERS
Set to true if each call that binds to a local definition explicitly
clobbers or sets all non-fixed registers modified by performing the call.
That is, by the call pattern itself, or by code that might be inserted by the
linker (e.g. stubs, veneers, branch islands), but not including those
modifiable by the callee. The affected registers may be mentioned explicitly
in the call pattern, or included as clobbers in CALL_INSN_FUNCTION_USAGE.
The default version of this hook is set to false. The purpose of this hook
is to enable the fipa-ra optimization.
.. hook-end
.. include:: ../tm.rst.in
:start-after: [TARGET_CALL_FUSAGE_CONTAINS_NON_CALLEE_CLOBBERS]
:end-before: [TARGET_CALL_FUSAGE_CONTAINS_NON_CALLEE_CLOBBERS]

554
gcc/doc/gccint/target-macros/stack-layout-and-calling-conventions/passing-arguments-in-registers.rst
View File

@ -14,164 +14,45 @@ This section describes the macros which let you control how various
types of arguments are passed in registers or how they are arranged in
the stack.
.. function:: rtx TARGET_FUNCTION_ARG (cumulative_args_t ca, const function_arg_info &arg)
.. include:: ../tm.rst.in
:start-after: [TARGET_FUNCTION_ARG]
:end-before: [TARGET_FUNCTION_ARG]
.. hook-start:TARGET_FUNCTION_ARG
Return an RTX indicating whether function argument :samp:`{arg}` is passed
in a register and if so, which register. Argument :samp:`{ca}` summarizes all
the previous arguments.
.. include:: ../tm.rst.in
:start-after: [TARGET_MUST_PASS_IN_STACK]
:end-before: [TARGET_MUST_PASS_IN_STACK]
The return value is usually either a ``reg`` RTX for the hard
register in which to pass the argument, or zero to pass the argument
on the stack.
The value of the expression can also be a ``parallel`` RTX. This is
used when an argument is passed in multiple locations. The mode of the
``parallel`` should be the mode of the entire argument. The
``parallel`` holds any number of ``expr_list`` pairs; each one
describes where part of the argument is passed. In each
``expr_list`` the first operand must be a ``reg`` RTX for the hard
register in which to pass this part of the argument, and the mode of the
register RTX indicates how large this part of the argument is. The
second operand of the ``expr_list`` is a ``const_int`` which gives
the offset in bytes into the entire argument of where this part starts.
As a special exception the first ``expr_list`` in the ``parallel``
RTX may have a first operand of zero. This indicates that the entire
argument is also stored on the stack.
.. include:: ../tm.rst.in
:start-after: [TARGET_FUNCTION_INCOMING_ARG]
:end-before: [TARGET_FUNCTION_INCOMING_ARG]
The last time this hook is called, it is called with ``MODE ==
VOIDmode``, and its result is passed to the ``call`` or ``call_value``
pattern as operands 2 and 3 respectively.
.. index:: stdarg.h and register arguments
.. include:: ../tm.rst.in
:start-after: [TARGET_USE_PSEUDO_PIC_REG]
:end-before: [TARGET_USE_PSEUDO_PIC_REG]
The usual way to make the ISO library :samp:`stdarg.h` work on a
machine where some arguments are usually passed in registers, is to
cause nameless arguments to be passed on the stack instead. This is
done by making ``TARGET_FUNCTION_ARG`` return 0 whenever
:samp:`{named}` is ``false``.
.. index:: TARGET_MUST_PASS_IN_STACK, and TARGET_FUNCTION_ARG, REG_PARM_STACK_SPACE, and TARGET_FUNCTION_ARG
.. include:: ../tm.rst.in
:start-after: [TARGET_INIT_PIC_REG]
:end-before: [TARGET_INIT_PIC_REG]
You may use the hook ``targetm.calls.must_pass_in_stack``
in the definition of this macro to determine if this argument is of a
type that must be passed in the stack. If ``REG_PARM_STACK_SPACE``
is not defined and ``TARGET_FUNCTION_ARG`` returns nonzero for such an
argument, the compiler will abort. If ``REG_PARM_STACK_SPACE`` is
defined, the argument will be computed in the stack and then loaded into
a register.
.. hook-end
.. include:: ../tm.rst.in
:start-after: [TARGET_ARG_PARTIAL_BYTES]
:end-before: [TARGET_ARG_PARTIAL_BYTES]
.. function:: bool TARGET_MUST_PASS_IN_STACK (const function_arg_info &arg)
.. hook-start:TARGET_MUST_PASS_IN_STACK
.. include:: ../tm.rst.in
:start-after: [TARGET_PASS_BY_REFERENCE]
:end-before: [TARGET_PASS_BY_REFERENCE]
This target hook should return ``true`` if we should not pass :samp:`{arg}`
solely in registers. The file :samp:`expr.h` defines a
definition that is usually appropriate, refer to :samp:`expr.h` for additional
documentation.
.. hook-end
.. include:: ../tm.rst.in
:start-after: [TARGET_CALLEE_COPIES]
:end-before: [TARGET_CALLEE_COPIES]
.. function:: rtx TARGET_FUNCTION_INCOMING_ARG (cumulative_args_t ca, const function_arg_info &arg)
.. hook-start:TARGET_FUNCTION_INCOMING_ARG
Define this hook if the caller and callee on the target have different
views of where arguments are passed. Also define this hook if there are
functions that are never directly called, but are invoked by the hardware
and which have nonstandard calling conventions.
In this case ``TARGET_FUNCTION_ARG`` computes the register in
which the caller passes the value, and
``TARGET_FUNCTION_INCOMING_ARG`` should be defined in a similar
fashion to tell the function being called where the arguments will
arrive.
``TARGET_FUNCTION_INCOMING_ARG`` can also return arbitrary address
computation using hard register, which can be forced into a register,
so that it can be used to pass special arguments.
If ``TARGET_FUNCTION_INCOMING_ARG`` is not defined,
``TARGET_FUNCTION_ARG`` serves both purposes.
.. hook-end
.. function:: bool TARGET_USE_PSEUDO_PIC_REG (void)
.. hook-start:TARGET_USE_PSEUDO_PIC_REG
This hook should return 1 in case pseudo register should be created
for pic_offset_table_rtx during function expand.
.. hook-end
.. function:: void TARGET_INIT_PIC_REG (void)
.. hook-start:TARGET_INIT_PIC_REG
Perform a target dependent initialization of pic_offset_table_rtx.
This hook is called at the start of register allocation.
.. hook-end
.. function:: int TARGET_ARG_PARTIAL_BYTES (cumulative_args_t cum, const function_arg_info &arg)
.. hook-start:TARGET_ARG_PARTIAL_BYTES
This target hook returns the number of bytes at the beginning of an
argument that must be put in registers. The value must be zero for
arguments that are passed entirely in registers or that are entirely
pushed on the stack.
On some machines, certain arguments must be passed partially in
registers and partially in memory. On these machines, typically the
first few words of arguments are passed in registers, and the rest
on the stack. If a multi-word argument (a ``double`` or a
structure) crosses that boundary, its first few words must be passed
in registers and the rest must be pushed. This macro tells the
compiler when this occurs, and how many bytes should go in registers.
``TARGET_FUNCTION_ARG`` for these arguments should return the first
register to be used by the caller for this argument; likewise
``TARGET_FUNCTION_INCOMING_ARG``, for the called function.
.. hook-end
.. function:: bool TARGET_PASS_BY_REFERENCE (cumulative_args_t cum, const function_arg_info &arg)
.. hook-start:TARGET_PASS_BY_REFERENCE
This target hook should return ``true`` if argument :samp:`{arg}` at the
position indicated by :samp:`{cum}` should be passed by reference. This
predicate is queried after target independent reasons for being
passed by reference, such as ``TREE_ADDRESSABLE (arg.type)``.
If the hook returns true, a copy of that argument is made in memory and a
pointer to the argument is passed instead of the argument itself.
The pointer is passed in whatever way is appropriate for passing a pointer
to that type.
.. hook-end
.. function:: bool TARGET_CALLEE_COPIES (cumulative_args_t cum, const function_arg_info &arg)
.. hook-start:TARGET_CALLEE_COPIES
The function argument described by the parameters to this hook is
known to be passed by reference. The hook should return true if the
function argument should be copied by the callee instead of copied
by the caller.
For any argument for which the hook returns true, if it can be
determined that the argument is not modified, then a copy need
not be generated.
The default version of this hook always returns false.
.. hook-end
.. c:macro:: CUMULATIVE_ARGS
@ -241,52 +122,20 @@ the stack.
.. -mew 5feb93 i switched the order of the sentences. -mew 10feb93
.. function:: void TARGET_FUNCTION_ARG_ADVANCE (cumulative_args_t ca, const function_arg_info &arg)
.. include:: ../tm.rst.in
:start-after: [TARGET_FUNCTION_ARG_ADVANCE]
:end-before: [TARGET_FUNCTION_ARG_ADVANCE]
.. hook-start:TARGET_FUNCTION_ARG_ADVANCE
This hook updates the summarizer variable pointed to by :samp:`{ca}` to
advance past argument :samp:`{arg}` in the argument list. Once this is done,
the variable :samp:`{cum}` is suitable for analyzing the *following*
argument with ``TARGET_FUNCTION_ARG``, etc.
.. include:: ../tm.rst.in
:start-after: [TARGET_FUNCTION_ARG_OFFSET]
:end-before: [TARGET_FUNCTION_ARG_OFFSET]
This hook need not do anything if the argument in question was passed
on the stack. The compiler knows how to track the amount of stack space
used for arguments without any special help.
.. hook-end
.. include:: ../tm.rst.in
:start-after: [TARGET_FUNCTION_ARG_PADDING]
:end-before: [TARGET_FUNCTION_ARG_PADDING]
.. function:: HOST_WIDE_INT TARGET_FUNCTION_ARG_OFFSET (machine_mode mode, const_tree type)
.. hook-start:TARGET_FUNCTION_ARG_OFFSET
This hook returns the number of bytes to add to the offset of an
argument of type :samp:`{type}` and mode :samp:`{mode}` when passed in memory.
This is needed for the SPU, which passes ``char`` and ``short``
arguments in the preferred slot that is in the middle of the quad word
instead of starting at the top. The default implementation returns 0.
.. hook-end
.. function:: pad_direction TARGET_FUNCTION_ARG_PADDING (machine_mode mode, const_tree type)
.. hook-start:TARGET_FUNCTION_ARG_PADDING
This hook determines whether, and in which direction, to pad out
an argument of mode :samp:`{mode}` and type :samp:`{type}`. It returns
``PAD_UPWARD`` to insert padding above the argument, ``PAD_DOWNWARD``
to insert padding below the argument, or ``PAD_NONE`` to inhibit padding.
The *amount* of padding is not controlled by this hook, but by
``TARGET_FUNCTION_ARG_ROUND_BOUNDARY``. It is always just enough
to reach the next multiple of that boundary.
This hook has a default definition that is right for most systems.
For little-endian machines, the default is to pad upward. For
big-endian machines, the default is to pad downward for an argument of
constant size shorter than an ``int``, and upward otherwise.
.. hook-end
.. c:macro:: PAD_VARARGS_DOWN
@ -307,26 +156,15 @@ the stack.
a three byte aggregate may be passed in the high part of a register if so
required.
.. function:: unsigned int TARGET_FUNCTION_ARG_BOUNDARY (machine_mode mode, const_tree type)
.. include:: ../tm.rst.in
:start-after: [TARGET_FUNCTION_ARG_BOUNDARY]
:end-before: [TARGET_FUNCTION_ARG_BOUNDARY]
.. hook-start:TARGET_FUNCTION_ARG_BOUNDARY
This hook returns the alignment boundary, in bits, of an argument
with the specified mode and type. The default hook returns
``PARM_BOUNDARY`` for all arguments.
.. include:: ../tm.rst.in
:start-after: [TARGET_FUNCTION_ARG_ROUND_BOUNDARY]
:end-before: [TARGET_FUNCTION_ARG_ROUND_BOUNDARY]
.. hook-end
.. function:: unsigned int TARGET_FUNCTION_ARG_ROUND_BOUNDARY (machine_mode mode, const_tree type)
.. hook-start:TARGET_FUNCTION_ARG_ROUND_BOUNDARY
Normally, the size of an argument is rounded up to ``PARM_BOUNDARY``,
which is the default value for this hook. You can define this hook to
return a different value if an argument size must be rounded to a larger
value.
.. hook-end
.. c:macro:: FUNCTION_ARG_REGNO_P (regno)
@ -337,297 +175,91 @@ the stack.
used for this purpose since all function arguments are pushed on the
stack.
.. function:: bool TARGET_SPLIT_COMPLEX_ARG (const_tree type)
.. include:: ../tm.rst.in
:start-after: [TARGET_SPLIT_COMPLEX_ARG]
:end-before: [TARGET_SPLIT_COMPLEX_ARG]
.. hook-start:TARGET_SPLIT_COMPLEX_ARG
This hook should return true if parameter of type :samp:`{type}` are passed
as two scalar parameters. By default, GCC will attempt to pack complex
arguments into the target's word size. Some ABIs require complex arguments
to be split and treated as their individual components. For example, on
AIX64, complex floats should be passed in a pair of floating point
registers, even though a complex float would fit in one 64-bit floating
point register.
.. include:: ../tm.rst.in
:start-after: [TARGET_BUILD_BUILTIN_VA_LIST]
:end-before: [TARGET_BUILD_BUILTIN_VA_LIST]
The default value of this hook is ``NULL``, which is treated as always
false.
.. hook-end
.. include:: ../tm.rst.in
:start-after: [TARGET_ENUM_VA_LIST_P]
:end-before: [TARGET_ENUM_VA_LIST_P]
.. function:: tree TARGET_BUILD_BUILTIN_VA_LIST (void)
.. hook-start:TARGET_BUILD_BUILTIN_VA_LIST
.. include:: ../tm.rst.in
:start-after: [TARGET_FN_ABI_VA_LIST]
:end-before: [TARGET_FN_ABI_VA_LIST]
This hook returns a type node for ``va_list`` for the target.
The default version of the hook returns ``void*``.
.. hook-end
.. include:: ../tm.rst.in
:start-after: [TARGET_CANONICAL_VA_LIST_TYPE]
:end-before: [TARGET_CANONICAL_VA_LIST_TYPE]
.. function:: int TARGET_ENUM_VA_LIST_P (int idx, const char **pname, tree *ptree)
.. hook-start:TARGET_ENUM_VA_LIST_P
.. include:: ../tm.rst.in
:start-after: [TARGET_GIMPLIFY_VA_ARG_EXPR]
:end-before: [TARGET_GIMPLIFY_VA_ARG_EXPR]
This target hook is used in function ``c_common_nodes_and_builtins``
to iterate through the target specific builtin types for va_list. The
variable :samp:`{idx}` is used as iterator. :samp:`{pname}` has to be a pointer
to a ``const char *`` and :samp:`{ptree}` a pointer to a ``tree`` typed
variable.
The arguments :samp:`{pname}` and :samp:`{ptree}` are used to store the result of
this macro and are set to the name of the va_list builtin type and its
internal type.
If the return value of this macro is zero, then there is no more element.
Otherwise the :samp:`{IDX}` should be increased for the next call of this
macro to iterate through all types.
.. hook-end
.. include:: ../tm.rst.in
:start-after: [TARGET_VALID_POINTER_MODE]
:end-before: [TARGET_VALID_POINTER_MODE]
.. function:: tree TARGET_FN_ABI_VA_LIST (tree fndecl)
.. hook-start:TARGET_FN_ABI_VA_LIST
.. include:: ../tm.rst.in
:start-after: [TARGET_REF_MAY_ALIAS_ERRNO]
:end-before: [TARGET_REF_MAY_ALIAS_ERRNO]
This hook returns the va_list type of the calling convention specified by
:samp:`{fndecl}`.
The default version of this hook returns ``va_list_type_node``.
.. hook-end
.. include:: ../tm.rst.in
:start-after: [TARGET_TRANSLATE_MODE_ATTRIBUTE]
:end-before: [TARGET_TRANSLATE_MODE_ATTRIBUTE]
.. function:: tree TARGET_CANONICAL_VA_LIST_TYPE (tree type)
.. hook-start:TARGET_CANONICAL_VA_LIST_TYPE
.. include:: ../tm.rst.in
:start-after: [TARGET_SCALAR_MODE_SUPPORTED_P]
:end-before: [TARGET_SCALAR_MODE_SUPPORTED_P]
This hook returns the va_list type of the calling convention specified by the
type of :samp:`{type}`. If :samp:`{type}` is not a valid va_list type, it returns
``NULL_TREE``.
.. hook-end
.. include:: ../tm.rst.in
:start-after: [TARGET_VECTOR_MODE_SUPPORTED_P]
:end-before: [TARGET_VECTOR_MODE_SUPPORTED_P]
.. function:: tree TARGET_GIMPLIFY_VA_ARG_EXPR (tree valist, tree type, gimple_seq *pre_p, gimple_seq *post_p)
.. hook-start:TARGET_GIMPLIFY_VA_ARG_EXPR
.. include:: ../tm.rst.in
:start-after: [TARGET_COMPATIBLE_VECTOR_TYPES_P]
:end-before: [TARGET_COMPATIBLE_VECTOR_TYPES_P]
This hook performs target-specific gimplification of
``VA_ARG_EXPR``. The first two parameters correspond to the
arguments to ``va_arg`` ; the latter two are as in
``gimplify.cc:gimplify_expr``.
.. hook-end
.. include:: ../tm.rst.in
:start-after: [TARGET_ARRAY_MODE]
:end-before: [TARGET_ARRAY_MODE]
.. function:: bool TARGET_VALID_POINTER_MODE (scalar_int_mode mode)
.. hook-start:TARGET_VALID_POINTER_MODE
.. include:: ../tm.rst.in
:start-after: [TARGET_ARRAY_MODE_SUPPORTED_P]
:end-before: [TARGET_ARRAY_MODE_SUPPORTED_P]
Define this to return nonzero if the port can handle pointers
with machine mode :samp:`{mode}`. The default version of this
hook returns true for both ``ptr_mode`` and ``Pmode``.
.. hook-end
.. include:: ../tm.rst.in
:start-after: [TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P]
:end-before: [TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P]
.. function:: bool TARGET_REF_MAY_ALIAS_ERRNO (ao_ref *ref)
.. hook-start:TARGET_REF_MAY_ALIAS_ERRNO
.. include:: ../tm.rst.in
:start-after: [TARGET_FLOATN_MODE]
:end-before: [TARGET_FLOATN_MODE]
Define this to return nonzero if the memory reference :samp:`{ref}`
may alias with the system C library errno location. The default
version of this hook assumes the system C library errno location
is either a declaration of type int or accessed by dereferencing
a pointer to int.
.. hook-end
.. include:: ../tm.rst.in
:start-after: [TARGET_FLOATN_BUILTIN_P]
:end-before: [TARGET_FLOATN_BUILTIN_P]
.. function:: machine_mode TARGET_TRANSLATE_MODE_ATTRIBUTE (machine_mode mode)
.. hook-start:TARGET_TRANSLATE_MODE_ATTRIBUTE
Define this hook if during mode attribute processing, the port should
translate machine_mode :samp:`{mode}` to another mode. For example, rs6000's
``KFmode``, when it is the same as ``TFmode``.
The default version of the hook returns that mode that was passed in.
.. hook-end
.. function:: bool TARGET_SCALAR_MODE_SUPPORTED_P (scalar_mode mode)
.. hook-start:TARGET_SCALAR_MODE_SUPPORTED_P
Define this to return nonzero if the port is prepared to handle
insns involving scalar mode :samp:`{mode}`. For a scalar mode to be
considered supported, all the basic arithmetic and comparisons
must work.
The default version of this hook returns true for any mode
required to handle the basic C types (as defined by the port).
Included here are the double-word arithmetic supported by the
code in :samp:`optabs.cc`.
.. hook-end
.. function:: bool TARGET_VECTOR_MODE_SUPPORTED_P (machine_mode mode)
.. hook-start:TARGET_VECTOR_MODE_SUPPORTED_P
Define this to return nonzero if the port is prepared to handle
insns involving vector mode :samp:`{mode}`. At the very least, it
must have move patterns for this mode.
.. hook-end
.. function:: bool TARGET_COMPATIBLE_VECTOR_TYPES_P (const_tree type1, const_tree type2)
.. hook-start:TARGET_COMPATIBLE_VECTOR_TYPES_P
Return true if there is no target-specific reason for treating
vector types :samp:`{type1}` and :samp:`{type2}` as distinct types. The caller
has already checked for target-independent reasons, meaning that the
types are known to have the same mode, to have the same number of elements,
and to have what the caller considers to be compatible element types.
The main reason for defining this hook is to reject pairs of types
that are handled differently by the target's calling convention.
For example, when a new :samp:`{N}` -bit vector architecture is added
to a target, the target may want to handle normal :samp:`{N}` -bit
``VECTOR_TYPE`` arguments and return values in the same way as
before, to maintain backwards compatibility. However, it may also
provide new, architecture-specific ``VECTOR_TYPE`` s that are passed
and returned in a more efficient way. It is then important to maintain
a distinction between the 'normal' ``VECTOR_TYPE`` s and the new
architecture-specific ones.
The default implementation returns true, which is correct for most targets.
.. hook-end
.. function:: opt_machine_mode TARGET_ARRAY_MODE (machine_mode mode, unsigned HOST_WIDE_INT nelems)
.. hook-start:TARGET_ARRAY_MODE
Return the mode that GCC should use for an array that has
:samp:`{nelems}` elements, with each element having mode :samp:`{mode}`.
Return no mode if the target has no special requirements. In the
latter case, GCC looks for an integer mode of the appropriate size
if available and uses BLKmode otherwise. Usually the search for the
integer mode is limited to ``MAX_FIXED_MODE_SIZE``, but the
``TARGET_ARRAY_MODE_SUPPORTED_P`` hook allows a larger mode to be
used in specific cases.
The main use of this hook is to specify that an array of vectors should
also have a vector mode. The default implementation returns no mode.
.. hook-end
.. function:: bool TARGET_ARRAY_MODE_SUPPORTED_P (machine_mode mode, unsigned HOST_WIDE_INT nelems)
.. hook-start:TARGET_ARRAY_MODE_SUPPORTED_P
Return true if GCC should try to use a scalar mode to store an array
of :samp:`{nelems}` elements, given that each element has mode :samp:`{mode}`.
Returning true here overrides the usual ``MAX_FIXED_MODE`` limit
and allows GCC to use any defined integer mode.
One use of this hook is to support vector load and store operations
that operate on several homogeneous vectors. For example, ARM NEON
has operations like:
.. code-block:: c++
int8x8x3_t vld3_s8 (const int8_t *)
where the return type is defined as:
.. code-block:: c++
typedef struct int8x8x3_t
{
int8x8_t val[3];
} int8x8x3_t;
If this hook allows ``val`` to have a scalar mode, then
``int8x8x3_t`` can have the same mode. GCC can then store
``int8x8x3_t`` s in registers rather than forcing them onto the stack.
.. hook-end
.. function:: bool TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P (scalar_float_mode mode)
.. hook-start:TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P
Define this to return nonzero if libgcc provides support for the
floating-point mode :samp:`{mode}`, which is known to pass
``TARGET_SCALAR_MODE_SUPPORTED_P``. The default version of this
hook returns true for all of ``SFmode``, ``DFmode``,
``XFmode`` and ``TFmode``, if such modes exist.
.. hook-end
.. function:: opt_scalar_float_mode TARGET_FLOATN_MODE (int n, bool extended)
.. hook-start:TARGET_FLOATN_MODE
Define this to return the machine mode to use for the type
``_Floatn``, if :samp:`{extended}` is false, or the type
``_Floatnx``, if :samp:`{extended}` is true. If such a type is not
supported, return ``opt_scalar_float_mode ()``. The default version of
this hook returns ``SFmode`` for ``_Float32``, ``DFmode`` for
``_Float64`` and ``_Float32x`` and ``TFmode`` for
``_Float128``, if those modes exist and satisfy the requirements for
those types and pass ``TARGET_SCALAR_MODE_SUPPORTED_P`` and
``TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P`` ; for ``_Float64x``, it
returns the first of ``XFmode`` and ``TFmode`` that exists and
satisfies the same requirements; for other types, it returns
``opt_scalar_float_mode ()``. The hook is only called for values
of :samp:`{n}` and :samp:`{extended}` that are valid according to
ISO/IEC TS 18661-3:2015; that is, :samp:`{n}` is one of 32, 64, 128, or,
if :samp:`{extended}` is false, 16 or greater than 128 and a multiple of 32.
.. hook-end
.. function:: bool TARGET_FLOATN_BUILTIN_P (int func)
.. hook-start:TARGET_FLOATN_BUILTIN_P
Define this to return true if the ``_Floatn`` and
``_Floatnx`` built-in functions should implicitly enable the
built-in function without the ``__builtin_`` prefix in addition to the
normal built-in function with the ``__builtin_`` prefix. The default is
to only enable built-in functions without the ``__builtin_`` prefix for
the GNU C langauge. In strict ANSI/ISO mode, the built-in function without
the ``__builtin_`` prefix is not enabled. The argument ``FUNC`` is the
``enum built_in_function`` id of the function to be enabled.
.. hook-end
.. function:: bool TARGET_SMALL_REGISTER_CLASSES_FOR_MODE_P (machine_mode mode)
.. hook-start:TARGET_SMALL_REGISTER_CLASSES_FOR_MODE_P
Define this to return nonzero for machine modes for which the port has
small register classes. If this target hook returns nonzero for a given
:samp:`{mode}`, the compiler will try to minimize the lifetime of registers
in :samp:`{mode}`. The hook may be called with ``VOIDmode`` as argument.
In this case, the hook is expected to return nonzero if it returns nonzero
for any mode.
On some machines, it is risky to let hard registers live across arbitrary
insns. Typically, these machines have instructions that require values
to be in specific registers (like an accumulator), and reload will fail
if the required hard register is used for another purpose across such an
insn.
Passes before reload do not know which hard registers will be used
in an instruction, but the machine modes of the registers set or used in
the instruction are already known. And for some machines, register
classes are small for, say, integer registers but not for floating point
registers. For example, the AMD x86-64 architecture requires specific
registers for the legacy x86 integer instructions, but there are many
SSE registers for floating point operations. On such targets, a good
strategy may be to return nonzero from this hook for ``INTEGRAL_MODE_P``
machine modes but zero for the SSE register classes.
The default version of this hook returns false for any mode. It is always
safe to redefine this hook to return with a nonzero value. But if you
unnecessarily define it, you will reduce the amount of optimizations
that can be performed in some cases. If you do not define this hook
to return a nonzero value when it is required, the compiler will run out
of spill registers and print a fatal error message.
.. hook-end
.. include:: ../tm.rst.in
:start-after: [TARGET_SMALL_REGISTER_CLASSES_FOR_MODE_P]
:end-before: [TARGET_SMALL_REGISTER_CLASSES_FOR_MODE_P]

73
gcc/doc/gccint/target-macros/stack-layout-and-calling-conventions/passing-function-arguments-on-the-stack.rst
View File

@ -14,33 +14,15 @@ The macros in this section control how arguments are passed
on the stack. See the following section for other macros that
control passing certain arguments in registers.
.. function:: bool TARGET_PROMOTE_PROTOTYPES (const_tree fntype)
.. include:: ../tm.rst.in
:start-after: [TARGET_PROMOTE_PROTOTYPES]
:end-before: [TARGET_PROMOTE_PROTOTYPES]
.. hook-start:TARGET_PROMOTE_PROTOTYPES
This target hook returns ``true`` if an argument declared in a
prototype as an integral type smaller than ``int`` should actually be
passed as an ``int``. In addition to avoiding errors in certain
cases of mismatch, it also makes for better code on certain machines.
The default is to not promote prototypes.
.. include:: ../tm.rst.in
:start-after: [TARGET_PUSH_ARGUMENT]
:end-before: [TARGET_PUSH_ARGUMENT]
.. hook-end
.. function:: bool TARGET_PUSH_ARGUMENT (unsigned int npush)
.. hook-start:TARGET_PUSH_ARGUMENT
This target hook returns ``true`` if push instructions will be
used to pass outgoing arguments. When the push instruction usage is
optional, :samp:`{npush}` is nonzero to indicate the number of bytes to
push. Otherwise, :samp:`{npush}` is zero. If the target machine does not
have a push instruction or push instruction should be avoided,
``false`` should be returned. That directs GCC to use an alternate
strategy: to allocate the entire argument block and then store the
arguments into it. If this target hook may return ``true``,
``PUSH_ROUNDING`` must be defined.
.. hook-end
.. c:macro:: PUSH_ARGS_REVERSED
@ -135,47 +117,10 @@ control passing certain arguments in registers.
suppresses this behavior and causes the parameter to be passed on the
stack in its natural location.
.. function:: poly_int64 TARGET_RETURN_POPS_ARGS (tree fundecl, tree funtype, poly_int64 size)
.. include:: ../tm.rst.in
:start-after: [TARGET_RETURN_POPS_ARGS]
:end-before: [TARGET_RETURN_POPS_ARGS]
.. hook-start:TARGET_RETURN_POPS_ARGS
This target hook returns the number of bytes of its own arguments that
a function pops on returning, or 0 if the function pops no arguments
and the caller must therefore pop them all after the function returns.
:samp:`{fundecl}` is a C variable whose value is a tree node that describes
the function in question. Normally it is a node of type
``FUNCTION_DECL`` that describes the declaration of the function.
From this you can obtain the ``DECL_ATTRIBUTES`` of the function.
:samp:`{funtype}` is a C variable whose value is a tree node that
describes the function in question. Normally it is a node of type
``FUNCTION_TYPE`` that describes the data type of the function.
From this it is possible to obtain the data types of the value and
arguments (if known).
When a call to a library function is being considered, :samp:`{fundecl}`
will contain an identifier node for the library function. Thus, if
you need to distinguish among various library functions, you can do so
by their names. Note that 'library function' in this context means
a function used to perform arithmetic, whose name is known specially
in the compiler and was not mentioned in the C code being compiled.
:samp:`{size}` is the number of bytes of arguments passed on the
stack. If a variable number of bytes is passed, it is zero, and
argument popping will always be the responsibility of the calling function.
On the VAX, all functions always pop their arguments, so the definition
of this macro is :samp:`{size}`. On the 68000, using the standard
calling convention, no functions pop their arguments, so the value of
the macro is always 0 in this case. But an alternative calling
convention is available in which functions that take a fixed number of
arguments pop them but other functions (such as ``printf``) pop
nothing (the caller pops all). When this convention is in use,
:samp:`{funtype}` is examined to determine whether a function takes a fixed
number of arguments.
.. hook-end
.. c:macro:: CALL_POPS_ARGS (cum)

54
gcc/doc/gccint/target-macros/stack-layout-and-calling-conventions/permitting-tail-calls.rst
View File

@ -10,51 +10,21 @@
Permitting tail calls
^^^^^^^^^^^^^^^^^^^^^
.. function:: bool TARGET_FUNCTION_OK_FOR_SIBCALL (tree decl, tree exp)
.. include:: ../tm.rst.in
:start-after: [TARGET_FUNCTION_OK_FOR_SIBCALL]
:end-before: [TARGET_FUNCTION_OK_FOR_SIBCALL]
.. hook-start:TARGET_FUNCTION_OK_FOR_SIBCALL
True if it is OK to do sibling call optimization for the specified
call expression :samp:`{exp}`. :samp:`{decl}` will be the called function,
or ``NULL`` if this is an indirect call.
.. include:: ../tm.rst.in
:start-after: [TARGET_EXTRA_LIVE_ON_ENTRY]
:end-before: [TARGET_EXTRA_LIVE_ON_ENTRY]
It is not uncommon for limitations of calling conventions to prevent
tail calls to functions outside the current unit of translation, or
during PIC compilation. The hook is used to enforce these restrictions,
as the ``sibcall`` md pattern cannot fail, or fall over to a
'normal' call. The criteria for successful sibling call optimization
may vary greatly between different architectures.
.. hook-end
.. include:: ../tm.rst.in
:start-after: [TARGET_SET_UP_BY_PROLOGUE]
:end-before: [TARGET_SET_UP_BY_PROLOGUE]
.. function:: void TARGET_EXTRA_LIVE_ON_ENTRY (bitmap regs)
.. hook-start:TARGET_EXTRA_LIVE_ON_ENTRY
Add any hard registers to :samp:`{regs}` that are live on entry to the
function. This hook only needs to be defined to provide registers that
cannot be found by examination of FUNCTION_ARG_REGNO_P, the callee saved
registers, STATIC_CHAIN_INCOMING_REGNUM, STATIC_CHAIN_REGNUM,
TARGET_STRUCT_VALUE_RTX, FRAME_POINTER_REGNUM, EH_USES,
FRAME_POINTER_REGNUM, ARG_POINTER_REGNUM, and the PIC_OFFSET_TABLE_REGNUM.
.. hook-end
.. function:: void TARGET_SET_UP_BY_PROLOGUE (struct hard_reg_set_container *)
.. hook-start:TARGET_SET_UP_BY_PROLOGUE
This hook should add additional registers that are computed by the prologue
to the hard regset for shrink-wrapping optimization purposes.
.. hook-end
.. function:: bool TARGET_WARN_FUNC_RETURN (tree)
.. hook-start:TARGET_WARN_FUNC_RETURN
True if a function's return statements should be checked for matching
the function's return type. This includes checking for falling off the end
of a non-void function. Return false if no such check should be made.
.. hook-end
.. include:: ../tm.rst.in
:start-after: [TARGET_WARN_FUNC_RETURN]
:end-before: [TARGET_WARN_FUNC_RETURN]

27
gcc/doc/gccint/target-macros/stack-layout-and-calling-conventions/registers-that-address-the-stack-frame.rst
View File

@ -102,31 +102,10 @@ This discusses registers that address the stack frame.
If the static chain is passed in memory, these macros should not be
defined; instead, the ``TARGET_STATIC_CHAIN`` hook should be used.
.. function:: rtx TARGET_STATIC_CHAIN (const_tree fndecl_or_type, bool incoming_p)
.. include:: ../tm.rst.in
:start-after: [TARGET_STATIC_CHAIN]
:end-before: [TARGET_STATIC_CHAIN]
.. hook-start:TARGET_STATIC_CHAIN
This hook replaces the use of ``STATIC_CHAIN_REGNUM`` et al for
targets that may use different static chain locations for different
nested functions. This may be required if the target has function
attributes that affect the calling conventions of the function and
those calling conventions use different static chain locations.
The default version of this hook uses ``STATIC_CHAIN_REGNUM`` et al.
If the static chain is passed in memory, this hook should be used to
provide rtx giving ``mem`` expressions that denote where they are stored.
Often the ``mem`` expression as seen by the caller will be at an offset
from the stack pointer and the ``mem`` expression as seen by the callee
will be at an offset from the frame pointer.
.. index:: stack_pointer_rtx, frame_pointer_rtx, arg_pointer_rtx
The variables ``stack_pointer_rtx``, ``frame_pointer_rtx``, and
``arg_pointer_rtx`` will have been initialized and should be used
to refer to those items.
.. hook-end
.. c:macro:: DWARF_FRAME_REGISTERS

68
gcc/doc/gccint/target-macros/stack-layout-and-calling-conventions/shrink-wrapping-separate-components.rst
View File

@ -31,63 +31,31 @@ code treats them abstractly, as a bit in an ``sbitmap``. These
and ``shrink_wrap.components_for_bb`` hooks, and deallocated by the
generic code.
.. function:: sbitmap TARGET_SHRINK_WRAP_GET_SEPARATE_COMPONENTS (void)
.. include:: ../tm.rst.in
:start-after: [TARGET_SHRINK_WRAP_GET_SEPARATE_COMPONENTS]
:end-before: [TARGET_SHRINK_WRAP_GET_SEPARATE_COMPONENTS]
.. hook-start:TARGET_SHRINK_WRAP_GET_SEPARATE_COMPONENTS
This hook should return an ``sbitmap`` with the bits set for those
components that can be separately shrink-wrapped in the current function.
Return ``NULL`` if the current function should not get any separate
shrink-wrapping.
Don't define this hook if it would always return ``NULL``.
If it is defined, the other hooks in this group have to be defined as well.
.. include:: ../tm.rst.in
:start-after: [TARGET_SHRINK_WRAP_COMPONENTS_FOR_BB]
:end-before: [TARGET_SHRINK_WRAP_COMPONENTS_FOR_BB]
.. hook-end
.. function:: sbitmap TARGET_SHRINK_WRAP_COMPONENTS_FOR_BB (basic_block)
.. include:: ../tm.rst.in
:start-after: [TARGET_SHRINK_WRAP_DISQUALIFY_COMPONENTS]
:end-before: [TARGET_SHRINK_WRAP_DISQUALIFY_COMPONENTS]
.. hook-start:TARGET_SHRINK_WRAP_COMPONENTS_FOR_BB
This hook should return an ``sbitmap`` with the bits set for those
components where either the prologue component has to be executed before
the ``basic_block``, or the epilogue component after it, or both.
.. include:: ../tm.rst.in
:start-after: [TARGET_SHRINK_WRAP_EMIT_PROLOGUE_COMPONENTS]
:end-before: [TARGET_SHRINK_WRAP_EMIT_PROLOGUE_COMPONENTS]
.. hook-end
.. function:: void TARGET_SHRINK_WRAP_DISQUALIFY_COMPONENTS (sbitmap components, edge e, sbitmap edge_components, bool is_prologue)
.. include:: ../tm.rst.in
:start-after: [TARGET_SHRINK_WRAP_EMIT_EPILOGUE_COMPONENTS]
:end-before: [TARGET_SHRINK_WRAP_EMIT_EPILOGUE_COMPONENTS]
.. hook-start:TARGET_SHRINK_WRAP_DISQUALIFY_COMPONENTS
This hook should clear the bits in the :samp:`{components}` bitmap for those
components in :samp:`{edge_components}` that the target cannot handle on edge
:samp:`{e}`, where :samp:`{is_prologue}` says if this is for a prologue or an
epilogue instead.
.. hook-end
.. function:: void TARGET_SHRINK_WRAP_EMIT_PROLOGUE_COMPONENTS (sbitmap)
.. hook-start:TARGET_SHRINK_WRAP_EMIT_PROLOGUE_COMPONENTS
Emit prologue insns for the components indicated by the parameter.
.. hook-end
.. function:: void TARGET_SHRINK_WRAP_EMIT_EPILOGUE_COMPONENTS (sbitmap)
.. hook-start:TARGET_SHRINK_WRAP_EMIT_EPILOGUE_COMPONENTS
Emit epilogue insns for the components indicated by the parameter.
.. hook-end
.. function:: void TARGET_SHRINK_WRAP_SET_HANDLED_COMPONENTS (sbitmap)
.. hook-start:TARGET_SHRINK_WRAP_SET_HANDLED_COMPONENTS
Mark the components in the parameter as handled, so that the
``prologue`` and ``epilogue`` named patterns know to ignore those
components. The target code should not hang on to the ``sbitmap``, it
will be deleted after this call.
.. hook-end
.. include:: ../tm.rst.in
:start-after: [TARGET_SHRINK_WRAP_SET_HANDLED_COMPONENTS]
:end-before: [TARGET_SHRINK_WRAP_SET_HANDLED_COMPONENTS]

17
gcc/doc/gccint/target-macros/stack-layout-and-calling-conventions/specifying-how-stack-checking-is-done.rst
View File

@ -102,17 +102,6 @@ in the opposite case.
GCC computed the default from the values of the above macros and you will
normally not need to override that default.
.. function:: HOST_WIDE_INT TARGET_STACK_CLASH_PROTECTION_ALLOCA_PROBE_RANGE (void)
.. hook-start:TARGET_STACK_CLASH_PROTECTION_ALLOCA_PROBE_RANGE
Some targets have an ABI defined interval for which no probing needs to be done.
When a probe does need to be done this same interval is used as the probe distance
up when doing stack clash protection for alloca.
On such targets this value can be set to override the default probing up interval.
Define this variable to return nonzero if such a probe range is required or zero otherwise.
Defining this hook also requires your functions which make use of alloca to have at least 8 byes
of outgoing arguments. If this is not the case the stack will be corrupted.
You need not define this macro if it would always have the value zero.
.. hook-end
.. include:: ../tm.rst.in
:start-after: [TARGET_STACK_CLASH_PROTECTION_ALLOCA_PROBE_RANGE]
:end-before: [TARGET_STACK_CLASH_PROTECTION_ALLOCA_PROBE_RANGE]

70
gcc/doc/gccint/target-macros/stack-layout-and-calling-conventions/stack-smashing-protection.rst
View File

@ -10,66 +10,26 @@
Stack smashing protection
^^^^^^^^^^^^^^^^^^^^^^^^^
.. function:: tree TARGET_STACK_PROTECT_GUARD (void)
.. include:: ../tm.rst.in
:start-after: [TARGET_STACK_PROTECT_GUARD]
:end-before: [TARGET_STACK_PROTECT_GUARD]
.. hook-start:TARGET_STACK_PROTECT_GUARD
This hook returns a ``DECL`` node for the external variable to use
for the stack protection guard. This variable is initialized by the
runtime to some random value and is used to initialize the guard value
that is placed at the top of the local stack frame. The type of this
variable must be ``ptr_type_node``.
.. include:: ../tm.rst.in
:start-after: [TARGET_STACK_PROTECT_FAIL]
:end-before: [TARGET_STACK_PROTECT_FAIL]
The default version of this hook creates a variable called
:samp:`__stack_chk_guard`, which is normally defined in :samp:`libgcc2.c`.
.. hook-end
.. include:: ../tm.rst.in
:start-after: [TARGET_STACK_PROTECT_RUNTIME_ENABLED_P]
:end-before: [TARGET_STACK_PROTECT_RUNTIME_ENABLED_P]
.. function:: tree TARGET_STACK_PROTECT_FAIL (void)
.. hook-start:TARGET_STACK_PROTECT_FAIL
.. include:: ../tm.rst.in
:start-after: [TARGET_SUPPORTS_SPLIT_STACK]
:end-before: [TARGET_SUPPORTS_SPLIT_STACK]
This hook returns a ``CALL_EXPR`` that alerts the runtime that the
stack protect guard variable has been modified. This expression should
involve a call to a ``noreturn`` function.
The default version of this hook invokes a function called
:samp:`__stack_chk_fail`, taking no arguments. This function is
normally defined in :samp:`libgcc2.c`.
.. hook-end
.. function:: bool TARGET_STACK_PROTECT_RUNTIME_ENABLED_P (void)
.. hook-start:TARGET_STACK_PROTECT_RUNTIME_ENABLED_P
Returns true if the target wants GCC's default stack protect runtime support,
otherwise return false. The default implementation always returns true.
.. hook-end
.. function:: bool TARGET_SUPPORTS_SPLIT_STACK (bool report, struct gcc_options *opts)
.. hook-start:TARGET_SUPPORTS_SPLIT_STACK
Whether this target supports splitting the stack when the options
described in :samp:`{opts}` have been passed. This is called
after options have been parsed, so the target may reject splitting
the stack in some configurations. The default version of this hook
returns false. If :samp:`{report}` is true, this function may issue a warning
or error; if :samp:`{report}` is false, it must simply return a value
.. hook-end
.. function:: vec<const char *> TARGET_GET_VALID_OPTION_VALUES (int option_code, const char *prefix)
.. hook-start:TARGET_GET_VALID_OPTION_VALUES
The hook is used for options that have a non-trivial list of
possible option values. OPTION_CODE is option code of opt_code
enum type. PREFIX is used for bash completion and allows an implementation
to return more specific completion based on the prefix. All string values
should be allocated from heap memory and consumers should release them.
The result will be pruned to cases with PREFIX if not NULL.
.. hook-end
.. include:: ../tm.rst.in
:start-after: [TARGET_GET_VALID_OPTION_VALUES]
:end-before: [TARGET_GET_VALID_OPTION_VALUES]

313
gcc/doc/gccint/target-macros/storage-layout.rst
View File

@ -121,61 +121,15 @@ See :ref:`run-time-target`.
Do not define this macro if it would never modify :samp:`{m}`.
.. function:: enum flt_eval_method TARGET_C_EXCESS_PRECISION (enum excess_precision_type type)
.. include:: tm.rst.in
:start-after: [TARGET_C_EXCESS_PRECISION]
:end-before: [TARGET_C_EXCESS_PRECISION]
.. hook-start:TARGET_C_EXCESS_PRECISION
Return a value, with the same meaning as the C99 macro
``FLT_EVAL_METHOD`` that describes which excess precision should be
applied. :samp:`{type}` is either ``EXCESS_PRECISION_TYPE_IMPLICIT``,
``EXCESS_PRECISION_TYPE_FAST``,
``EXCESS_PRECISION_TYPE_STANDARD``, or
``EXCESS_PRECISION_TYPE_FLOAT16``. For
``EXCESS_PRECISION_TYPE_IMPLICIT``, the target should return which
precision and range operations will be implictly evaluated in regardless
of the excess precision explicitly added. For
``EXCESS_PRECISION_TYPE_STANDARD``,
``EXCESS_PRECISION_TYPE_FLOAT16``, and
``EXCESS_PRECISION_TYPE_FAST``, the target should return the
explicit excess precision that should be added depending on the
value set for :option:`-fexcess-precision=[standard|fast|16]`.
Note that unpredictable explicit excess precision does not make sense,
so a target should never return ``FLT_EVAL_METHOD_UNPREDICTABLE``
when :samp:`{type}` is ``EXCESS_PRECISION_TYPE_STANDARD``,
``EXCESS_PRECISION_TYPE_FLOAT16`` or
``EXCESS_PRECISION_TYPE_FAST``.
.. include:: tm.rst.in
:start-after: [TARGET_PROMOTE_FUNCTION_MODE]
:end-before: [TARGET_PROMOTE_FUNCTION_MODE]
Return a value, with the same meaning as the C99 macro
``FLT_EVAL_METHOD`` that describes which excess precision should be
applied.
.. hook-end
.. function:: machine_mode TARGET_PROMOTE_FUNCTION_MODE (const_tree type, machine_mode mode, int *punsignedp, const_tree funtype, int for_return)
.. hook-start:TARGET_PROMOTE_FUNCTION_MODE
Like ``PROMOTE_MODE``, but it is applied to outgoing function arguments or
function return values. The target hook should return the new mode
and possibly change ``*punsignedp`` if the promotion should
change signedness. This function is called only for scalar *or
pointer* types.
:samp:`{for_return}` allows to distinguish the promotion of arguments and
return values. If it is ``1``, a return value is being promoted and
``TARGET_FUNCTION_VALUE`` must perform the same promotions done here.
If it is ``2``, the returned mode should be that of the register in
which an incoming parameter is copied, or the outgoing result is computed;
then the hook should return the same mode as ``promote_mode``, though
the signedness may be different.
:samp:`{type}` can be NULL when promoting function arguments of libcalls.
The default is to not promote arguments and return values. You can
also define the hook to ``default_promote_function_mode_always_promote``
if you would like to apply the same rules given by ``PROMOTE_MODE``.
.. hook-end
.. c:macro:: PARM_BOUNDARY
@ -216,15 +170,10 @@ applied.
bits. Note that this is not the biggest alignment that is supported,
just the biggest alignment that, when violated, may cause a fault.
.. c:var:: HOST_WIDE_INT TARGET_ABSOLUTE_BIGGEST_ALIGNMENT
.. include:: tm.rst.in
:start-after: [TARGET_ABSOLUTE_BIGGEST_ALIGNMENT]
:end-before: [TARGET_ABSOLUTE_BIGGEST_ALIGNMENT]
.. hook-start:TARGET_ABSOLUTE_BIGGEST_ALIGNMENT
If defined, this target hook specifies the absolute biggest alignment
that a type or variable can have on this machine, otherwise,
``BIGGEST_ALIGNMENT`` is used.
.. hook-end
.. c:macro:: MALLOC_ABI_ALIGNMENT
@ -289,25 +238,15 @@ applied.
On 32-bit ELF the largest supported section alignment in bits is
:samp:`(0x80000000 * 8)`, but this is not representable on 32-bit hosts.
.. function:: void TARGET_LOWER_LOCAL_DECL_ALIGNMENT (tree decl)
.. include:: tm.rst.in
:start-after: [TARGET_LOWER_LOCAL_DECL_ALIGNMENT]
:end-before: [TARGET_LOWER_LOCAL_DECL_ALIGNMENT]
.. hook-start:TARGET_LOWER_LOCAL_DECL_ALIGNMENT
Define this hook to lower alignment of local, parm or result
decl :samp:`({decl})`.
.. include:: tm.rst.in
:start-after: [TARGET_STATIC_RTX_ALIGNMENT]
:end-before: [TARGET_STATIC_RTX_ALIGNMENT]
.. hook-end
.. function:: HOST_WIDE_INT TARGET_STATIC_RTX_ALIGNMENT (machine_mode mode)
.. hook-start:TARGET_STATIC_RTX_ALIGNMENT
This hook returns the preferred alignment in bits for a
statically-allocated rtx, such as a constant pool entry. :samp:`{mode}`
is the mode of the rtx. The default implementation returns
:samp:`GET_MODE_ALIGNMENT ({mode})`.
.. hook-end
.. c:macro:: DATA_ALIGNMENT (type, basic_align)
@ -333,22 +272,10 @@ applied.
If this macro is not defined, then :samp:`{basic_align}` is used.
.. function:: HOST_WIDE_INT TARGET_CONSTANT_ALIGNMENT (const_tree constant, HOST_WIDE_INT basic_align)
.. include:: tm.rst.in
:start-after: [TARGET_CONSTANT_ALIGNMENT]
:end-before: [TARGET_CONSTANT_ALIGNMENT]
.. hook-start:TARGET_CONSTANT_ALIGNMENT
This hook returns the alignment in bits of a constant that is being
placed in memory. :samp:`{constant}` is the constant and :samp:`{basic_align}`
is the alignment that the object would ordinarily have.
The default definition just returns :samp:`{basic_align}`.
The typical use of this hook is to increase alignment for string
constants to be word aligned so that ``strcpy`` calls that copy
constants can be done inline. The function
``constant_alignment_word_strings`` provides such a definition.
.. hook-end
.. c:macro:: LOCAL_ALIGNMENT (type, basic_align)
@ -364,17 +291,10 @@ applied.
If the value of this macro has a type, it should be an unsigned type.
.. function:: HOST_WIDE_INT TARGET_VECTOR_ALIGNMENT (const_tree type)
.. include:: tm.rst.in
:start-after: [TARGET_VECTOR_ALIGNMENT]
:end-before: [TARGET_VECTOR_ALIGNMENT]
.. hook-start:TARGET_VECTOR_ALIGNMENT
This hook can be used to define the alignment for a vector of type
:samp:`{type}`, in order to comply with a platform ABI. The default is to
require natural alignment for vector types. The alignment returned by
this hook must be a power-of-two multiple of the default alignment of
the vector element type.
.. hook-end
.. c:macro:: STACK_SLOT_ALIGNMENT (type, mode, basic_align)
@ -508,44 +428,20 @@ applied.
Like ``PCC_BITFIELD_TYPE_MATTERS`` except that its effect is limited
to aligning a bit-field within the structure.
.. function:: bool TARGET_ALIGN_ANON_BITFIELD (void)
.. include:: tm.rst.in
:start-after: [TARGET_ALIGN_ANON_BITFIELD]
:end-before: [TARGET_ALIGN_ANON_BITFIELD]
.. hook-start:TARGET_ALIGN_ANON_BITFIELD
When ``PCC_BITFIELD_TYPE_MATTERS`` is true this hook will determine
whether unnamed bitfields affect the alignment of the containing
structure. The hook should return true if the structure should inherit
the alignment requirements of an unnamed bitfield's type.
.. include:: tm.rst.in
:start-after: [TARGET_NARROW_VOLATILE_BITFIELD]
:end-before: [TARGET_NARROW_VOLATILE_BITFIELD]
.. hook-end
.. function:: bool TARGET_NARROW_VOLATILE_BITFIELD (void)
.. include:: tm.rst.in
:start-after: [TARGET_MEMBER_TYPE_FORCES_BLK]
:end-before: [TARGET_MEMBER_TYPE_FORCES_BLK]
.. hook-start:TARGET_NARROW_VOLATILE_BITFIELD
This target hook should return ``true`` if accesses to volatile bitfields
should use the narrowest mode possible. It should return ``false`` if
these accesses should use the bitfield container type.
The default is ``false``.
.. hook-end
.. function:: bool TARGET_MEMBER_TYPE_FORCES_BLK (const_tree field, machine_mode mode)
.. hook-start:TARGET_MEMBER_TYPE_FORCES_BLK
Return true if a structure, union or array containing :samp:`{field}` should
be accessed using ``BLKMODE``.
If :samp:`{field}` is the only field in the structure, :samp:`{mode}` is its
mode, otherwise :samp:`{mode}` is VOIDmode. :samp:`{mode}` is provided in the
case where structures of one field would require the structure's mode to
retain the field's mode.
Normally, this is not needed.
.. hook-end
.. c:macro:: ROUND_TYPE_ALIGN (type, computed, specified)
@ -589,141 +485,46 @@ applied.
You would most commonly define this macro if the ``allocate_stack``
pattern needs to support both a 32- and a 64-bit mode.
.. function:: scalar_int_mode TARGET_LIBGCC_CMP_RETURN_MODE (void)
.. include:: tm.rst.in
:start-after: [TARGET_LIBGCC_CMP_RETURN_MODE]
:end-before: [TARGET_LIBGCC_CMP_RETURN_MODE]
.. hook-start:TARGET_LIBGCC_CMP_RETURN_MODE
This target hook should return the mode to be used for the return value
of compare instructions expanded to libgcc calls. If not defined
``word_mode`` is returned which is the right choice for a majority of
targets.
.. include:: tm.rst.in
:start-after: [TARGET_LIBGCC_SHIFT_COUNT_MODE]
:end-before: [TARGET_LIBGCC_SHIFT_COUNT_MODE]
.. hook-end
.. function:: scalar_int_mode TARGET_LIBGCC_SHIFT_COUNT_MODE (void)
.. include:: tm.rst.in
:start-after: [TARGET_UNWIND_WORD_MODE]
:end-before: [TARGET_UNWIND_WORD_MODE]
.. hook-start:TARGET_LIBGCC_SHIFT_COUNT_MODE
This target hook should return the mode to be used for the shift count operand
of shift instructions expanded to libgcc calls. If not defined
``word_mode`` is returned which is the right choice for a majority of
targets.
.. include:: tm.rst.in
:start-after: [TARGET_MS_BITFIELD_LAYOUT_P]
:end-before: [TARGET_MS_BITFIELD_LAYOUT_P]
.. hook-end
.. function:: scalar_int_mode TARGET_UNWIND_WORD_MODE (void)
.. include:: tm.rst.in
:start-after: [TARGET_DECIMAL_FLOAT_SUPPORTED_P]
:end-before: [TARGET_DECIMAL_FLOAT_SUPPORTED_P]
.. hook-start:TARGET_UNWIND_WORD_MODE
Return machine mode to be used for ``_Unwind_Word`` type.
The default is to use ``word_mode``.
.. include:: tm.rst.in
:start-after: [TARGET_FIXED_POINT_SUPPORTED_P]
:end-before: [TARGET_FIXED_POINT_SUPPORTED_P]
.. hook-end
.. function:: bool TARGET_MS_BITFIELD_LAYOUT_P (const_tree record_type)
.. include:: tm.rst.in
:start-after: [TARGET_EXPAND_TO_RTL_HOOK]
:end-before: [TARGET_EXPAND_TO_RTL_HOOK]
.. hook-start:TARGET_MS_BITFIELD_LAYOUT_P
This target hook returns ``true`` if bit-fields in the given
:samp:`{record_type}` are to be laid out following the rules of Microsoft
Visual C/C++, namely: (i) a bit-field won't share the same storage
unit with the previous bit-field if their underlying types have
different sizes, and the bit-field will be aligned to the highest
alignment of the underlying types of itself and of the previous
bit-field; (ii) a zero-sized bit-field will affect the alignment of
the whole enclosing structure, even if it is unnamed; except that
(iii) a zero-sized bit-field will be disregarded unless it follows
another bit-field of nonzero size. If this hook returns ``true``,
other macros that control bit-field layout are ignored.
.. include:: tm.rst.in
:start-after: [TARGET_INSTANTIATE_DECLS]
:end-before: [TARGET_INSTANTIATE_DECLS]
When a bit-field is inserted into a packed record, the whole size
of the underlying type is used by one or more same-size adjacent
bit-fields (that is, if its long:3, 32 bits is used in the record,
and any additional adjacent long bit-fields are packed into the same
chunk of 32 bits. However, if the size changes, a new field of that
size is allocated). In an unpacked record, this is the same as using
alignment, but not equivalent when packing.
If both MS bit-fields and :samp:`__attribute__((packed))` are used,
the latter will take precedence. If :samp:`__attribute__((packed))` is
used on a single field when MS bit-fields are in use, it will take
precedence for that field, but the alignment of the rest of the structure
may affect its placement.
.. hook-end
.. function:: bool TARGET_DECIMAL_FLOAT_SUPPORTED_P (void)
.. hook-start:TARGET_DECIMAL_FLOAT_SUPPORTED_P
Returns true if the target supports decimal floating point.
.. hook-end
.. function:: bool TARGET_FIXED_POINT_SUPPORTED_P (void)
.. hook-start:TARGET_FIXED_POINT_SUPPORTED_P
Returns true if the target supports fixed-point arithmetic.
.. hook-end
.. function:: void TARGET_EXPAND_TO_RTL_HOOK (void)
.. hook-start:TARGET_EXPAND_TO_RTL_HOOK
This hook is called just before expansion into rtl, allowing the target
to perform additional initializations or analysis before the expansion.
For example, the rs6000 port uses it to allocate a scratch stack slot
for use in copying SDmode values between memory and floating point
registers whenever the function being expanded has any SDmode
usage.
.. hook-end
.. function:: void TARGET_INSTANTIATE_DECLS (void)
.. hook-start:TARGET_INSTANTIATE_DECLS
This hook allows the backend to perform additional instantiations on rtl
that are not actually in any insns yet, but will be later.
.. hook-end
.. function:: const char * TARGET_MANGLE_TYPE (const_tree type)
.. hook-start:TARGET_MANGLE_TYPE
If your target defines any fundamental types, or any types your target
uses should be mangled differently from the default, define this hook
to return the appropriate encoding for these types as part of a C++
mangled name. The :samp:`{type}` argument is the tree structure representing
the type to be mangled. The hook may be applied to trees which are
not target-specific fundamental types; it should return ``NULL``
for all such types, as well as arguments it does not recognize. If the
return value is not ``NULL``, it must point to a statically-allocated
string constant.
Target-specific fundamental types might be new fundamental types or
qualified versions of ordinary fundamental types. Encode new
fundamental types as :samp:`u {n}{name}`, where :samp:`{name}`
is the name used for the type in source code, and :samp:`{n}` is the
length of :samp:`{name}` in decimal. Encode qualified versions of
ordinary types as :samp:`U{n}{name}{code}`, where
:samp:`{name}` is the name used for the type qualifier in source code,
:samp:`{n}` is the length of :samp:`{name}` as above, and :samp:`{code}` is the
code used to represent the unqualified version of this type. (See
``write_builtin_type`` in :samp:`cp/mangle.cc` for the list of
codes.) In both cases the spaces are for clarity; do not include any
spaces in your string.
This hook is applied to types prior to typedef resolution. If the mangled
name for a particular type depends only on that type's main variant, you
can perform typedef resolution yourself using ``TYPE_MAIN_VARIANT``
before mangling.
The default version of this hook always returns ``NULL``, which is
appropriate for a target that does not define any new fundamental
types.
.. hook-end
.. include:: tm.rst.in
:start-after: [TARGET_MANGLE_TYPE]
:end-before: [TARGET_MANGLE_TYPE]

98
gcc/doc/gccint/target-macros/support-for-nested-functions.rst
View File

@ -49,28 +49,10 @@ Define the following hook if your backend either implements ABI-specified
descriptor support, or can use GCC's generic descriptor implementation
for nested functions.
.. c:var:: int TARGET_CUSTOM_FUNCTION_DESCRIPTORS
.. include:: tm.rst.in
:start-after: [TARGET_CUSTOM_FUNCTION_DESCRIPTORS]
:end-before: [TARGET_CUSTOM_FUNCTION_DESCRIPTORS]
.. hook-start:TARGET_CUSTOM_FUNCTION_DESCRIPTORS
If the target can use GCC's generic descriptor mechanism for nested
functions, define this hook to a power of 2 representing an unused bit
in function pointers which can be used to differentiate descriptors at
run time. This value gives the number of bytes by which descriptor
pointers are misaligned compared to function pointers. For example, on
targets that require functions to be aligned to a 4-byte boundary, a
value of either 1 or 2 is appropriate unless the architecture already
reserves the bit for another purpose, such as on ARM.
Define this hook to 0 if the target implements ABI support for
function descriptors in its standard calling sequence, like for example
HPPA or IA-64.
Using descriptors for nested functions
eliminates the need for trampolines that reside on the stack and require
it to be made executable.
.. hook-end
The following macros tell GCC how to generate code to allocate and
initialize an executable trampoline. You can also use this interface
@ -94,21 +76,10 @@ proper offset from the start of the trampoline. On a RISC machine, it
may be necessary to take out pieces of the address and store them
separately.
.. function:: void TARGET_ASM_TRAMPOLINE_TEMPLATE (FILE *f)
.. include:: tm.rst.in
:start-after: [TARGET_ASM_TRAMPOLINE_TEMPLATE]
:end-before: [TARGET_ASM_TRAMPOLINE_TEMPLATE]
.. hook-start:TARGET_ASM_TRAMPOLINE_TEMPLATE
This hook is called by ``assemble_trampoline_template`` to output,
on the stream :samp:`{f}`, assembler code for a block of data that contains
the constant parts of a trampoline. This code should not include a
label---the label is taken care of automatically.
If you do not define this hook, it means no template is needed
for the target. Do not define this hook on systems where the block move
code to copy the trampoline into place would be larger than the code
to generate it on the spot.
.. hook-end
.. c:macro:: TRAMPOLINE_SECTION
@ -126,59 +97,20 @@ separately.
If you don't define this macro, the value of ``FUNCTION_ALIGNMENT``
is used for aligning trampolines.
.. function:: void TARGET_TRAMPOLINE_INIT (rtx m_tramp, tree fndecl, rtx static_chain)
.. include:: tm.rst.in
:start-after: [TARGET_TRAMPOLINE_INIT]
:end-before: [TARGET_TRAMPOLINE_INIT]
.. hook-start:TARGET_TRAMPOLINE_INIT
This hook is called to initialize a trampoline.
:samp:`{m_tramp}` is an RTX for the memory block for the trampoline; :samp:`{fndecl}`
is the ``FUNCTION_DECL`` for the nested function; :samp:`{static_chain}` is an
RTX for the static chain value that should be passed to the function
when it is called.
.. include:: tm.rst.in
:start-after: [TARGET_EMIT_CALL_BUILTIN___CLEAR_CACHE]
:end-before: [TARGET_EMIT_CALL_BUILTIN___CLEAR_CACHE]
If the target defines ``TARGET_ASM_TRAMPOLINE_TEMPLATE``, then the
first thing this hook should do is emit a block move into :samp:`{m_tramp}`
from the memory block returned by ``assemble_trampoline_template``.
Note that the block move need only cover the constant parts of the
trampoline. If the target isolates the variable parts of the trampoline
to the end, not all ``TRAMPOLINE_SIZE`` bytes need be copied.
If the target requires any other actions, such as flushing caches
(possibly calling function maybe_emit_call_builtin___clear_cache) or
enabling stack execution, these actions should be performed after
initializing the trampoline proper.
.. include:: tm.rst.in
:start-after: [TARGET_TRAMPOLINE_ADJUST_ADDRESS]
:end-before: [TARGET_TRAMPOLINE_ADJUST_ADDRESS]
.. hook-end
.. function:: void TARGET_EMIT_CALL_BUILTIN___CLEAR_CACHE (rtx begin, rtx end)
.. hook-start:TARGET_EMIT_CALL_BUILTIN___CLEAR_CACHE
On targets that do not define a ``clear_cache`` insn expander,
but that define the ``CLEAR_CACHE_INSN`` macro,
maybe_emit_call_builtin___clear_cache relies on this target hook
to clear an address range in the instruction cache.
The default implementation calls the ``__clear_cache`` builtin,
taking the assembler name from the builtin declaration. Overriding
definitions may call alternate functions, with alternate calling
conventions, or emit alternate RTX to perform the job.
.. hook-end
.. function:: rtx TARGET_TRAMPOLINE_ADJUST_ADDRESS (rtx addr)
.. hook-start:TARGET_TRAMPOLINE_ADJUST_ADDRESS
This hook should perform any machine-specific adjustment in
the address of the trampoline. Its argument contains the address of the
memory block that was passed to ``TARGET_TRAMPOLINE_INIT``. In case
the address to be used for a function call should be different from the
address at which the template was stored, the different address should
be returned; otherwise :samp:`{addr}` should be returned unchanged.
If this hook is not defined, :samp:`{addr}` will be used for function calls.
.. hook-end
Implementing trampolines is difficult on many machines because they have
separate instruction and data caches. Writing into a stack location