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extend.texi: Clarify use of __attribute__((naked)).

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gcc/

2008-05-23  Paul Brook  <paul@codesourcery.com>
	    Carlos O'Donell  <carlos@codesourcery.com>

	* doc/extend.texi: Clarify use of __attribute__((naked)).
	* doc/tm.texi: Document TARGET_ALLOCATE_STACK_SLOTS_FOR_ARGS.
	* target.h (gcc_target): Add allocate_stack_slots_for_args.
	* function.c (use_register_for_decl): Use
	targetm.calls.allocate_stack_slots_for_args.
	* target-def.h (TARGET_CALLS): Add 
	TARGET_ALLOCATE_STACK_SLOTS_FOR_ARGS.
	* config/arm/arm.c (arm_allocate_stack_slots_for_args): 
	New function.
	(TARGET_ALLOCATE_STACK_SLOTS_FOR_ARGS): Define.

gcc/testsuite/

2008-05-23  Paul Brook  <paul@codesourcery.com>
	    Carlos O'Donell  <carlos@codesourcery.com>

	* gcc.target/arm/naked-1.c: New test.
	* gcc.target/arm/naked-2.c: New test.


Co-Authored-By: Carlos O'Donell <carlos@codesourcery.com>

From-SVN: r135831
This commit is contained in:
Paul Brook 2008-05-23 20:36:57 +00:00 committed by Carlos O'Donell
parent b86c6d94f8
commit 007e61c28b
10 changed files with 86 additions and 2 deletions
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14
gcc/ChangeLog
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@ -1,3 +1,17 @@
2008-05-23 Paul Brook <paul@codesourcery.com>
Carlos O'Donell <carlos@codesourcery.com>
* doc/extend.texi: Clarify use of __attribute__((naked)).
* doc/tm.texi: Document TARGET_ALLOCATE_STACK_SLOTS_FOR_ARGS.
* target.h (gcc_target): Add allocate_stack_slots_for_args.
* function.c (use_register_for_decl): Use
targetm.calls.allocate_stack_slots_for_args.
* target-def.h (TARGET_CALLS): Add
TARGET_ALLOCATE_STACK_SLOTS_FOR_ARGS.
* config/arm/arm.c (arm_allocate_stack_slots_for_args):
New function.
(TARGET_ALLOCATE_STACK_SLOTS_FOR_ARGS): Define.
2008-05-23 Eric Botcazou <ebotcazou@adacore.com>
* expr.c (highest_pow2_factor) <BIT_AND_EXPR>: New case.

12
gcc/config/arm/arm.c
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@ -189,6 +189,7 @@ static bool arm_cannot_copy_insn_p (rtx);
static bool arm_tls_symbol_p (rtx x);
static int arm_issue_rate (void);
static void arm_output_dwarf_dtprel (FILE *, int, rtx) ATTRIBUTE_UNUSED;
static bool arm_allocate_stack_slots_for_args (void);
/* Initialize the GCC target structure. */
@ -289,6 +290,9 @@ static void arm_output_dwarf_dtprel (FILE *, int, rtx) ATTRIBUTE_UNUSED;
#undef TARGET_SETUP_INCOMING_VARARGS
#define TARGET_SETUP_INCOMING_VARARGS arm_setup_incoming_varargs
#undef TARGET_ALLOCATE_STACK_SLOTS_FOR_ARGS
#define TARGET_ALLOCATE_STACK_SLOTS_FOR_ARGS arm_allocate_stack_slots_for_args
#undef TARGET_DEFAULT_SHORT_ENUMS
#define TARGET_DEFAULT_SHORT_ENUMS arm_default_short_enums
@ -1619,6 +1623,14 @@ arm_current_func_type (void)
return cfun->machine->func_type;
}
bool
arm_allocate_stack_slots_for_args (void)
{
/* Naked functions should not allocate stack slots for arguments. */
return !IS_NAKED (arm_current_func_type ());
}
/* Return 1 if it is possible to return using a single instruction.
If SIBLING is non-null, this is a test for a return before a sibling

8
gcc/doc/extend.texi
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@ -2512,7 +2512,13 @@ defined by shared libraries.
@cindex function without a prologue/epilogue code
Use this attribute on the ARM, AVR, IP2K and SPU ports to indicate that
the specified function does not need prologue/epilogue sequences generated by
the compiler. It is up to the programmer to provide these sequences.
the compiler. It is up to the programmer to provide these sequences. The
only statements that can be safely included in naked functions are
@code{asm} statements that do not have operands. All other statements,
including declarations of local variables, @code{if} statements, and so
forth, should be avoided. Naked functions should be used to implement the
body of an assembly function, while allowing the compiler to construct
the requisite function declaration for the assembler.
@item near
@cindex functions which do not handle memory bank switching on 68HC11/68HC12

11
gcc/doc/tm.texi
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@ -10465,3 +10465,14 @@ to the functions in @file{libgcc} that provide low-level support for
call stack unwinding. It is used in declarations in @file{unwind-generic.h}
and the associated definitions of those functions.
@end defmac
@deftypefn {Target Hook} {bool} TARGET_ALLOCATE_STACK_SLOTS_FOR_ARGS (void)
When optimization is disabled, this hook indicates whether or not
arguments should be allocated to stack slots. Normally, GCC allocates
stacks slots for arguments when not optimizing in order to make
debugging easier. However, when a function is declared with
@code{__attribute__((naked))}, there is no stack frame, and the compiler
cannot safely move arguments from the registers in which they are passed
to the stack. Therefore, this hook should return true in general, but
false for naked functions. The default implementation always returns true.
@end deftypefn

3
gcc/function.c
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@ -1776,6 +1776,9 @@ aggregate_value_p (const_tree exp, const_tree fntype)
bool
use_register_for_decl (const_tree decl)
{
if (!targetm.calls.allocate_stack_slots_for_args())
return true;
/* Honor volatile. */
if (TREE_SIDE_EFFECTS (decl))
return false;

4
gcc/target-def.h
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@ -568,6 +568,7 @@
#define TARGET_FUNCTION_VALUE default_function_value
#define TARGET_INTERNAL_ARG_POINTER default_internal_arg_pointer
#define TARGET_ALLOCATE_STACK_SLOTS_FOR_ARGS hook_bool_void_true
#define TARGET_CALLS { \
TARGET_PROMOTE_FUNCTION_ARGS, \
@ -587,7 +588,8 @@
TARGET_ARG_PARTIAL_BYTES, \
TARGET_INVALID_ARG_FOR_UNPROTOTYPED_FN, \
TARGET_FUNCTION_VALUE, \
TARGET_INTERNAL_ARG_POINTER \
TARGET_INTERNAL_ARG_POINTER, \
TARGET_ALLOCATE_STACK_SLOTS_FOR_ARGS \
}
#ifndef TARGET_UNWIND_TABLES_DEFAULT

5
gcc/target.h
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@ -830,6 +830,11 @@ struct gcc_target
/* Return an rtx for the argument pointer incoming to the
current function. */
rtx (*internal_arg_pointer) (void);
/* Return true if all function parameters should be spilled to the
stack. */
bool (*allocate_stack_slots_for_args) (void);
} calls;
/* Return the diagnostic message string if conversion from FROMTYPE

6
gcc/testsuite/ChangeLog
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@ -1,3 +1,9 @@
2008-05-23 Paul Brook <paul@codesourcery.com>
Carlos O'Donell <carlos@codesourcery.com>
* gcc.target/arm/naked-1.c: New test.
* gcc.target/arm/naked-2.c: New test.
2008-05-23 Tobias Burnus <burnus@net-b.de>
PR fortran/36314

13
gcc/testsuite/gcc.target/arm/naked-1.c Normal file
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@ -0,0 +1,13 @@
/* { dg-do compile } */
/* { dg-options "-O0" } */
/* Check that function arguments aren't assigned and copied to stack slots
in naked functions. This ususally happens at -O0 (presumably for
better debugging), but is highly undesirable if we haven't created
a stack frame. */
void __attribute__((naked))
foo(int n)
{
__asm__ volatile ("frob r0\n");
}
/* { dg-final { scan-assembler "\tfrob r0" } } */
/* { dg-final { scan-assembler-not "\tstr" } } */

12
gcc/testsuite/gcc.target/arm/naked-2.c Normal file
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@ -0,0 +1,12 @@
/* Verify that __attribute__((naked)) produces a naked function
that does not use bx to return. Naked functions could be used
to implement interrupt routines and must not return using bx. */
/* { dg-do compile } */
/* { dg-options "-O0" } */
/* Use more arguments than we have argument registers. */
int __attribute__((naked)) foo(int a, int b, int c, int d, int e, int f)
{
__asm__ volatile ("@ naked");
}
/* { dg-final { scan-assembler "\t@ naked" } } */
/* { dg-final { scan-assembler-not "\tbx\tlr" } } */