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implement-c.texi: New file.
* doc/implement-c.texi: New file. * doc/extend.texi (C Implementation): Move to there. * doc/gcc.texi: Include implement-c.texi. * Makefile.in (TEXI_GCC_FILES): Add implement-c.texi. From-SVN: r85058
This commit is contained in:
Joseph Myers
Joseph Myers
parent
669d6ecca2
commit
d592f1c398
@ -1,3 +1,10 @@
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2004-07-22 Joseph S. Myers <jsm@polyomino.org.uk>
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* doc/implement-c.texi: New file.
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* doc/extend.texi (C Implementation): Move to there.
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* doc/gcc.texi: Include implement-c.texi.
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* Makefile.in (TEXI_GCC_FILES): Add implement-c.texi.
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2004-07-22 Jason Merrill <jason@redhat.com>
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* integrate.c (copy_decl_for_inlining): Remove invisible reference
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@ -2911,7 +2911,8 @@ TEXI_CPP_FILES = cpp.texi fdl.texi cppenv.texi cppopts.texi
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TEXI_GCC_FILES = gcc.texi gcc-common.texi frontends.texi standards.texi \
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invoke.texi extend.texi md.texi objc.texi gcov.texi trouble.texi \
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bugreport.texi service.texi contribute.texi compat.texi funding.texi \
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gnu.texi gpl.texi fdl.texi contrib.texi cppenv.texi cppopts.texi
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gnu.texi gpl.texi fdl.texi contrib.texi cppenv.texi cppopts.texi \
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implement-c.texi
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TEXI_GCCINT_FILES = gccint.texi gcc-common.texi contribute.texi makefile.texi \
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configterms.texi portability.texi interface.texi passes.texi \
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@ -3,406 +3,6 @@
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@c This is part of the GCC manual.
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@c For copying conditions, see the file gcc.texi.
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@node C Implementation
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@chapter C Implementation-defined behavior
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@cindex implementation-defined behavior, C language
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A conforming implementation of ISO C is required to document its
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choice of behavior in each of the areas that are designated
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``implementation defined.'' The following lists all such areas,
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along with the section number from the ISO/IEC 9899:1999 standard.
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@menu
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* Translation implementation::
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* Environment implementation::
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* Identifiers implementation::
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* Characters implementation::
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* Integers implementation::
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* Floating point implementation::
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* Arrays and pointers implementation::
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* Hints implementation::
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* Structures unions enumerations and bit-fields implementation::
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* Qualifiers implementation::
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* Preprocessing directives implementation::
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* Library functions implementation::
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* Architecture implementation::
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* Locale-specific behavior implementation::
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@end menu
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@node Translation implementation
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@section Translation
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@itemize @bullet
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@item
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@cite{How a diagnostic is identified (3.10, 5.1.1.3).}
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Diagnostics consist of all the output sent to stderr by GCC.
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@item
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@cite{Whether each nonempty sequence of white-space characters other than
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new-line is retained or replaced by one space character in translation
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phase 3 (5.1.1.2).}
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@end itemize
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@node Environment implementation
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@section Environment
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The behavior of these points are dependent on the implementation
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of the C library, and are not defined by GCC itself.
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@node Identifiers implementation
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@section Identifiers
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@itemize @bullet
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@item
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@cite{Which additional multibyte characters may appear in identifiers
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and their correspondence to universal character names (6.4.2).}
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@item
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@cite{The number of significant initial characters in an identifier
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(5.2.4.1, 6.4.2).}
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For internal names, all characters are significant. For external names,
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the number of significant characters are defined by the linker; for
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almost all targets, all characters are significant.
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@end itemize
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@node Characters implementation
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@section Characters
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@itemize @bullet
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@item
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@cite{The number of bits in a byte (3.6).}
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@item
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@cite{The values of the members of the execution character set (5.2.1).}
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@item
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@cite{The unique value of the member of the execution character set produced
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for each of the standard alphabetic escape sequences (5.2.2).}
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@item
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@cite{The value of a @code{char} object into which has been stored any
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character other than a member of the basic execution character set (6.2.5).}
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@item
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@cite{Which of @code{signed char} or @code{unsigned char} has the same range,
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representation, and behavior as ``plain'' @code{char} (6.2.5, 6.3.1.1).}
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@item
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@cite{The mapping of members of the source character set (in character
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constants and string literals) to members of the execution character
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set (6.4.4.4, 5.1.1.2).}
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@item
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@cite{The value of an integer character constant containing more than one
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character or containing a character or escape sequence that does not map
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to a single-byte execution character (6.4.4.4).}
|
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@item
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@cite{The value of a wide character constant containing more than one
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multibyte character, or containing a multibyte character or escape
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sequence not represented in the extended execution character set (6.4.4.4).}
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@item
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@cite{The current locale used to convert a wide character constant consisting
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of a single multibyte character that maps to a member of the extended
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execution character set into a corresponding wide character code (6.4.4.4).}
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@item
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@cite{The current locale used to convert a wide string literal into
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corresponding wide character codes (6.4.5).}
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@item
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@cite{The value of a string literal containing a multibyte character or escape
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sequence not represented in the execution character set (6.4.5).}
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@end itemize
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@node Integers implementation
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@section Integers
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@itemize @bullet
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@item
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@cite{Any extended integer types that exist in the implementation (6.2.5).}
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@item
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@cite{Whether signed integer types are represented using sign and magnitude,
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two's complement, or one's complement, and whether the extraordinary value
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is a trap representation or an ordinary value (6.2.6.2).}
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GCC supports only two's complement integer types, and all bit patterns
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are ordinary values.
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@item
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@cite{The rank of any extended integer type relative to another extended
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integer type with the same precision (6.3.1.1).}
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@item
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@cite{The result of, or the signal raised by, converting an integer to a
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signed integer type when the value cannot be represented in an object of
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that type (6.3.1.3).}
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@item
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@cite{The results of some bitwise operations on signed integers (6.5).}
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@end itemize
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@node Floating point implementation
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@section Floating point
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@itemize @bullet
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@item
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@cite{The accuracy of the floating-point operations and of the library
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functions in @code{<math.h>} and @code{<complex.h>} that return floating-point
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results (5.2.4.2.2).}
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@item
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@cite{The rounding behaviors characterized by non-standard values
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of @code{FLT_ROUNDS} @gol
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(5.2.4.2.2).}
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@item
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@cite{The evaluation methods characterized by non-standard negative
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values of @code{FLT_EVAL_METHOD} (5.2.4.2.2).}
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@item
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@cite{The direction of rounding when an integer is converted to a
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floating-point number that cannot exactly represent the original
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value (6.3.1.4).}
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@item
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@cite{The direction of rounding when a floating-point number is
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converted to a narrower floating-point number (6.3.1.5).}
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@item
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@cite{How the nearest representable value or the larger or smaller
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representable value immediately adjacent to the nearest representable
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value is chosen for certain floating constants (6.4.4.2).}
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@item
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@cite{Whether and how floating expressions are contracted when not
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disallowed by the @code{FP_CONTRACT} pragma (6.5).}
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@item
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@cite{The default state for the @code{FENV_ACCESS} pragma (7.6.1).}
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@item
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@cite{Additional floating-point exceptions, rounding modes, environments,
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and classifications, and their macro names (7.6, 7.12).}
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@item
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@cite{The default state for the @code{FP_CONTRACT} pragma (7.12.2).}
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@item
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@cite{Whether the ``inexact'' floating-point exception can be raised
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when the rounded result actually does equal the mathematical result
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in an IEC 60559 conformant implementation (F.9).}
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@item
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@cite{Whether the ``underflow'' (and ``inexact'') floating-point
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exception can be raised when a result is tiny but not inexact in an
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IEC 60559 conformant implementation (F.9).}
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@end itemize
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@node Arrays and pointers implementation
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@section Arrays and pointers
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@itemize @bullet
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@item
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@cite{The result of converting a pointer to an integer or
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vice versa (6.3.2.3).}
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A cast from pointer to integer discards most-significant bits if the
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pointer representation is larger than the integer type,
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sign-extends@footnote{Future versions of GCC may zero-extend, or use
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a target-defined @code{ptr_extend} pattern. Do not rely on sign extension.}
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if the pointer representation is smaller than the integer type, otherwise
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the bits are unchanged.
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@c ??? We've always claimed that pointers were unsigned entities.
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@c Shouldn't we therefore be doing zero-extension? If so, the bug
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@c is in convert_to_integer, where we call type_for_size and request
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@c a signed integral type. On the other hand, it might be most useful
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@c for the target if we extend according to POINTERS_EXTEND_UNSIGNED.
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A cast from integer to pointer discards most-significant bits if the
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pointer representation is smaller than the integer type, extends according
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to the signedness of the integer type if the pointer representation
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is larger than the integer type, otherwise the bits are unchanged.
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When casting from pointer to integer and back again, the resulting
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pointer must reference the same object as the original pointer, otherwise
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the behavior is undefined. That is, one may not use integer arithmetic to
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avoid the undefined behavior of pointer arithmetic as proscribed in 6.5.6/8.
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@item
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@cite{The size of the result of subtracting two pointers to elements
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of the same array (6.5.6).}
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@end itemize
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@node Hints implementation
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@section Hints
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@itemize @bullet
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@item
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@cite{The extent to which suggestions made by using the @code{register}
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storage-class specifier are effective (6.7.1).}
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The @code{register} specifier affects code generation only in these ways:
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@itemize @bullet
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@item
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When used as part of the register variable extension, see
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@ref{Explicit Reg Vars}.
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@item
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When @option{-O0} is in use, the compiler allocates distinct stack
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memory for all variables that do not have the @code{register}
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storage-class specifier; if @code{register} is specified, the variable
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may have a shorter lifespan than the code would indicate and may never
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be placed in memory.
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@item
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On some rare x86 targets, @code{setjmp} doesn't save the registers in
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all circumstances. In those cases, GCC doesn't allocate any variables
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in registers unless they are marked @code{register}.
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@end itemize
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@item
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@cite{The extent to which suggestions made by using the inline function
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specifier are effective (6.7.4).}
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GCC will not inline any functions if the @option{-fno-inline} option is
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used or if @option{-O0} is used. Otherwise, GCC may still be unable to
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inline a function for many reasons; the @option{-Winline} option may be
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used to determine if a function has not been inlined and why not.
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@end itemize
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@node Structures unions enumerations and bit-fields implementation
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@section Structures, unions, enumerations, and bit-fields
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@itemize @bullet
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@item
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@cite{Whether a ``plain'' int bit-field is treated as a @code{signed int}
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bit-field or as an @code{unsigned int} bit-field (6.7.2, 6.7.2.1).}
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@item
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@cite{Allowable bit-field types other than @code{_Bool}, @code{signed int},
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and @code{unsigned int} (6.7.2.1).}
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@item
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@cite{Whether a bit-field can straddle a storage-unit boundary (6.7.2.1).}
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|
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@item
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@cite{The order of allocation of bit-fields within a unit (6.7.2.1).}
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@item
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@cite{The alignment of non-bit-field members of structures (6.7.2.1).}
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|
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@item
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@cite{The integer type compatible with each enumerated type (6.7.2.2).}
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@end itemize
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@node Qualifiers implementation
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@section Qualifiers
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@itemize @bullet
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@item
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@cite{What constitutes an access to an object that has volatile-qualified
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type (6.7.3).}
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|
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@end itemize
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@node Preprocessing directives implementation
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@section Preprocessing directives
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@itemize @bullet
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@item
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||||
@cite{How sequences in both forms of header names are mapped to headers
|
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or external source file names (6.4.7).}
|
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|
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@item
|
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@cite{Whether the value of a character constant in a constant expression
|
||||
that controls conditional inclusion matches the value of the same character
|
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constant in the execution character set (6.10.1).}
|
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|
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@item
|
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@cite{Whether the value of a single-character character constant in a
|
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constant expression that controls conditional inclusion may have a
|
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negative value (6.10.1).}
|
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|
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@item
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@cite{The places that are searched for an included @samp{<>} delimited
|
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header, and how the places are specified or the header is
|
||||
identified (6.10.2).}
|
||||
|
||||
@item
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@cite{How the named source file is searched for in an included @samp{""}
|
||||
delimited header (6.10.2).}
|
||||
|
||||
@item
|
||||
@cite{The method by which preprocessing tokens (possibly resulting from
|
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macro expansion) in a @code{#include} directive are combined into a header
|
||||
name (6.10.2).}
|
||||
|
||||
@item
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||||
@cite{The nesting limit for @code{#include} processing (6.10.2).}
|
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||||
GCC imposes a limit of 200 nested @code{#include}s.
|
||||
|
||||
@item
|
||||
@cite{Whether the @samp{#} operator inserts a @samp{\} character before
|
||||
the @samp{\} character that begins a universal character name in a
|
||||
character constant or string literal (6.10.3.2).}
|
||||
|
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@item
|
||||
@cite{The behavior on each recognized non-@code{STDC #pragma}
|
||||
directive (6.10.6).}
|
||||
|
||||
@item
|
||||
@cite{The definitions for @code{__DATE__} and @code{__TIME__} when
|
||||
respectively, the date and time of translation are not available (6.10.8).}
|
||||
|
||||
If the date and time are not available, @code{__DATE__} expands to
|
||||
@code{@w{"??? ?? ????"}} and @code{__TIME__} expands to
|
||||
@code{"??:??:??"}.
|
||||
|
||||
@end itemize
|
||||
|
||||
@node Library functions implementation
|
||||
@section Library functions
|
||||
|
||||
The behavior of these points are dependent on the implementation
|
||||
of the C library, and are not defined by GCC itself.
|
||||
|
||||
@node Architecture implementation
|
||||
@section Architecture
|
||||
|
||||
@itemize @bullet
|
||||
@item
|
||||
@cite{The values or expressions assigned to the macros specified in the
|
||||
headers @code{<float.h>}, @code{<limits.h>}, and @code{<stdint.h>}
|
||||
(5.2.4.2, 7.18.2, 7.18.3).}
|
||||
|
||||
@item
|
||||
@cite{The number, order, and encoding of bytes in any object
|
||||
(when not explicitly specified in this International Standard) (6.2.6.1).}
|
||||
|
||||
@item
|
||||
@cite{The value of the result of the sizeof operator (6.5.3.4).}
|
||||
|
||||
@end itemize
|
||||
|
||||
@node Locale-specific behavior implementation
|
||||
@section Locale-specific behavior
|
||||
|
||||
The behavior of these points are dependent on the implementation
|
||||
of the C library, and are not defined by GCC itself.
|
||||
|
||||
@node C Extensions
|
||||
@chapter Extensions to the C Language Family
|
||||
@cindex extensions, C language
|
||||
|
||||
@ -160,6 +160,7 @@ Introduction, gccint, GNU Compiler Collection (GCC) Internals}.
|
||||
@include frontends.texi
|
||||
@include standards.texi
|
||||
@include invoke.texi
|
||||
@include implement-c.texi
|
||||
@include extend.texi
|
||||
@include objc.texi
|
||||
@include compat.texi
|
||||
|
||||
403
gcc/doc/implement-c.texi
Normal file
403
gcc/doc/implement-c.texi
Normal file
@ -0,0 +1,403 @@
|
||||
@c Copyright (C) 2001,2002,2003,2004 Free Software Foundation, Inc.
|
||||
@c This is part of the GCC manual.
|
||||
@c For copying conditions, see the file gcc.texi.
|
||||
|
||||
@node C Implementation
|
||||
@chapter C Implementation-defined behavior
|
||||
@cindex implementation-defined behavior, C language
|
||||
|
||||
A conforming implementation of ISO C is required to document its
|
||||
choice of behavior in each of the areas that are designated
|
||||
``implementation defined.'' The following lists all such areas,
|
||||
along with the section number from the ISO/IEC 9899:1999 standard.
|
||||
|
||||
@menu
|
||||
* Translation implementation::
|
||||
* Environment implementation::
|
||||
* Identifiers implementation::
|
||||
* Characters implementation::
|
||||
* Integers implementation::
|
||||
* Floating point implementation::
|
||||
* Arrays and pointers implementation::
|
||||
* Hints implementation::
|
||||
* Structures unions enumerations and bit-fields implementation::
|
||||
* Qualifiers implementation::
|
||||
* Preprocessing directives implementation::
|
||||
* Library functions implementation::
|
||||
* Architecture implementation::
|
||||
* Locale-specific behavior implementation::
|
||||
@end menu
|
||||
|
||||
@node Translation implementation
|
||||
@section Translation
|
||||
|
||||
@itemize @bullet
|
||||
@item
|
||||
@cite{How a diagnostic is identified (3.10, 5.1.1.3).}
|
||||
|
||||
Diagnostics consist of all the output sent to stderr by GCC.
|
||||
|
||||
@item
|
||||
@cite{Whether each nonempty sequence of white-space characters other than
|
||||
new-line is retained or replaced by one space character in translation
|
||||
phase 3 (5.1.1.2).}
|
||||
@end itemize
|
||||
|
||||
@node Environment implementation
|
||||
@section Environment
|
||||
|
||||
The behavior of these points are dependent on the implementation
|
||||
of the C library, and are not defined by GCC itself.
|
||||
|
||||
@node Identifiers implementation
|
||||
@section Identifiers
|
||||
|
||||
@itemize @bullet
|
||||
@item
|
||||
@cite{Which additional multibyte characters may appear in identifiers
|
||||
and their correspondence to universal character names (6.4.2).}
|
||||
|
||||
@item
|
||||
@cite{The number of significant initial characters in an identifier
|
||||
(5.2.4.1, 6.4.2).}
|
||||
|
||||
For internal names, all characters are significant. For external names,
|
||||
the number of significant characters are defined by the linker; for
|
||||
almost all targets, all characters are significant.
|
||||
|
||||
@end itemize
|
||||
|
||||
@node Characters implementation
|
||||
@section Characters
|
||||
|
||||
@itemize @bullet
|
||||
@item
|
||||
@cite{The number of bits in a byte (3.6).}
|
||||
|
||||
@item
|
||||
@cite{The values of the members of the execution character set (5.2.1).}
|
||||
|
||||
@item
|
||||
@cite{The unique value of the member of the execution character set produced
|
||||
for each of the standard alphabetic escape sequences (5.2.2).}
|
||||
|
||||
@item
|
||||
@cite{The value of a @code{char} object into which has been stored any
|
||||
character other than a member of the basic execution character set (6.2.5).}
|
||||
|
||||
@item
|
||||
@cite{Which of @code{signed char} or @code{unsigned char} has the same range,
|
||||
representation, and behavior as ``plain'' @code{char} (6.2.5, 6.3.1.1).}
|
||||
|
||||
@item
|
||||
@cite{The mapping of members of the source character set (in character
|
||||
constants and string literals) to members of the execution character
|
||||
set (6.4.4.4, 5.1.1.2).}
|
||||
|
||||
@item
|
||||
@cite{The value of an integer character constant containing more than one
|
||||
character or containing a character or escape sequence that does not map
|
||||
to a single-byte execution character (6.4.4.4).}
|
||||
|
||||
@item
|
||||
@cite{The value of a wide character constant containing more than one
|
||||
multibyte character, or containing a multibyte character or escape
|
||||
sequence not represented in the extended execution character set (6.4.4.4).}
|
||||
|
||||
@item
|
||||
@cite{The current locale used to convert a wide character constant consisting
|
||||
of a single multibyte character that maps to a member of the extended
|
||||
execution character set into a corresponding wide character code (6.4.4.4).}
|
||||
|
||||
@item
|
||||
@cite{The current locale used to convert a wide string literal into
|
||||
corresponding wide character codes (6.4.5).}
|
||||
|
||||
@item
|
||||
@cite{The value of a string literal containing a multibyte character or escape
|
||||
sequence not represented in the execution character set (6.4.5).}
|
||||
@end itemize
|
||||
|
||||
@node Integers implementation
|
||||
@section Integers
|
||||
|
||||
@itemize @bullet
|
||||
@item
|
||||
@cite{Any extended integer types that exist in the implementation (6.2.5).}
|
||||
|
||||
@item
|
||||
@cite{Whether signed integer types are represented using sign and magnitude,
|
||||
two's complement, or one's complement, and whether the extraordinary value
|
||||
is a trap representation or an ordinary value (6.2.6.2).}
|
||||
|
||||
GCC supports only two's complement integer types, and all bit patterns
|
||||
are ordinary values.
|
||||
|
||||
@item
|
||||
@cite{The rank of any extended integer type relative to another extended
|
||||
integer type with the same precision (6.3.1.1).}
|
||||
|
||||
@item
|
||||
@cite{The result of, or the signal raised by, converting an integer to a
|
||||
signed integer type when the value cannot be represented in an object of
|
||||
that type (6.3.1.3).}
|
||||
|
||||
@item
|
||||
@cite{The results of some bitwise operations on signed integers (6.5).}
|
||||
@end itemize
|
||||
|
||||
@node Floating point implementation
|
||||
@section Floating point
|
||||
|
||||
@itemize @bullet
|
||||
@item
|
||||
@cite{The accuracy of the floating-point operations and of the library
|
||||
functions in @code{<math.h>} and @code{<complex.h>} that return floating-point
|
||||
results (5.2.4.2.2).}
|
||||
|
||||
@item
|
||||
@cite{The rounding behaviors characterized by non-standard values
|
||||
of @code{FLT_ROUNDS} @gol
|
||||
(5.2.4.2.2).}
|
||||
|
||||
@item
|
||||
@cite{The evaluation methods characterized by non-standard negative
|
||||
values of @code{FLT_EVAL_METHOD} (5.2.4.2.2).}
|
||||
|
||||
@item
|
||||
@cite{The direction of rounding when an integer is converted to a
|
||||
floating-point number that cannot exactly represent the original
|
||||
value (6.3.1.4).}
|
||||
|
||||
@item
|
||||
@cite{The direction of rounding when a floating-point number is
|
||||
converted to a narrower floating-point number (6.3.1.5).}
|
||||
|
||||
@item
|
||||
@cite{How the nearest representable value or the larger or smaller
|
||||
representable value immediately adjacent to the nearest representable
|
||||
value is chosen for certain floating constants (6.4.4.2).}
|
||||
|
||||
@item
|
||||
@cite{Whether and how floating expressions are contracted when not
|
||||
disallowed by the @code{FP_CONTRACT} pragma (6.5).}
|
||||
|
||||
@item
|
||||
@cite{The default state for the @code{FENV_ACCESS} pragma (7.6.1).}
|
||||
|
||||
@item
|
||||
@cite{Additional floating-point exceptions, rounding modes, environments,
|
||||
and classifications, and their macro names (7.6, 7.12).}
|
||||
|
||||
@item
|
||||
@cite{The default state for the @code{FP_CONTRACT} pragma (7.12.2).}
|
||||
|
||||
@item
|
||||
@cite{Whether the ``inexact'' floating-point exception can be raised
|
||||
when the rounded result actually does equal the mathematical result
|
||||
in an IEC 60559 conformant implementation (F.9).}
|
||||
|
||||
@item
|
||||
@cite{Whether the ``underflow'' (and ``inexact'') floating-point
|
||||
exception can be raised when a result is tiny but not inexact in an
|
||||
IEC 60559 conformant implementation (F.9).}
|
||||
|
||||
@end itemize
|
||||
|
||||
@node Arrays and pointers implementation
|
||||
@section Arrays and pointers
|
||||
|
||||
@itemize @bullet
|
||||
@item
|
||||
@cite{The result of converting a pointer to an integer or
|
||||
vice versa (6.3.2.3).}
|
||||
|
||||
A cast from pointer to integer discards most-significant bits if the
|
||||
pointer representation is larger than the integer type,
|
||||
sign-extends@footnote{Future versions of GCC may zero-extend, or use
|
||||
a target-defined @code{ptr_extend} pattern. Do not rely on sign extension.}
|
||||
if the pointer representation is smaller than the integer type, otherwise
|
||||
the bits are unchanged.
|
||||
@c ??? We've always claimed that pointers were unsigned entities.
|
||||
@c Shouldn't we therefore be doing zero-extension? If so, the bug
|
||||
@c is in convert_to_integer, where we call type_for_size and request
|
||||
@c a signed integral type. On the other hand, it might be most useful
|
||||
@c for the target if we extend according to POINTERS_EXTEND_UNSIGNED.
|
||||
|
||||
A cast from integer to pointer discards most-significant bits if the
|
||||
pointer representation is smaller than the integer type, extends according
|
||||
to the signedness of the integer type if the pointer representation
|
||||
is larger than the integer type, otherwise the bits are unchanged.
|
||||
|
||||
When casting from pointer to integer and back again, the resulting
|
||||
pointer must reference the same object as the original pointer, otherwise
|
||||
the behavior is undefined. That is, one may not use integer arithmetic to
|
||||
avoid the undefined behavior of pointer arithmetic as proscribed in 6.5.6/8.
|
||||
|
||||
@item
|
||||
@cite{The size of the result of subtracting two pointers to elements
|
||||
of the same array (6.5.6).}
|
||||
|
||||
@end itemize
|
||||
|
||||
@node Hints implementation
|
||||
@section Hints
|
||||
|
||||
@itemize @bullet
|
||||
@item
|
||||
@cite{The extent to which suggestions made by using the @code{register}
|
||||
storage-class specifier are effective (6.7.1).}
|
||||
|
||||
The @code{register} specifier affects code generation only in these ways:
|
||||
|
||||
@itemize @bullet
|
||||
@item
|
||||
When used as part of the register variable extension, see
|
||||
@ref{Explicit Reg Vars}.
|
||||
|
||||
@item
|
||||
When @option{-O0} is in use, the compiler allocates distinct stack
|
||||
memory for all variables that do not have the @code{register}
|
||||
storage-class specifier; if @code{register} is specified, the variable
|
||||
may have a shorter lifespan than the code would indicate and may never
|
||||
be placed in memory.
|
||||
|
||||
@item
|
||||
On some rare x86 targets, @code{setjmp} doesn't save the registers in
|
||||
all circumstances. In those cases, GCC doesn't allocate any variables
|
||||
in registers unless they are marked @code{register}.
|
||||
|
||||
@end itemize
|
||||
|
||||
@item
|
||||
@cite{The extent to which suggestions made by using the inline function
|
||||
specifier are effective (6.7.4).}
|
||||
|
||||
GCC will not inline any functions if the @option{-fno-inline} option is
|
||||
used or if @option{-O0} is used. Otherwise, GCC may still be unable to
|
||||
inline a function for many reasons; the @option{-Winline} option may be
|
||||
used to determine if a function has not been inlined and why not.
|
||||
|
||||
@end itemize
|
||||
|
||||
@node Structures unions enumerations and bit-fields implementation
|
||||
@section Structures, unions, enumerations, and bit-fields
|
||||
|
||||
@itemize @bullet
|
||||
@item
|
||||
@cite{Whether a ``plain'' int bit-field is treated as a @code{signed int}
|
||||
bit-field or as an @code{unsigned int} bit-field (6.7.2, 6.7.2.1).}
|
||||
|
||||
@item
|
||||
@cite{Allowable bit-field types other than @code{_Bool}, @code{signed int},
|
||||
and @code{unsigned int} (6.7.2.1).}
|
||||
|
||||
@item
|
||||
@cite{Whether a bit-field can straddle a storage-unit boundary (6.7.2.1).}
|
||||
|
||||
@item
|
||||
@cite{The order of allocation of bit-fields within a unit (6.7.2.1).}
|
||||
|
||||
@item
|
||||
@cite{The alignment of non-bit-field members of structures (6.7.2.1).}
|
||||
|
||||
@item
|
||||
@cite{The integer type compatible with each enumerated type (6.7.2.2).}
|
||||
|
||||
@end itemize
|
||||
|
||||
@node Qualifiers implementation
|
||||
@section Qualifiers
|
||||
|
||||
@itemize @bullet
|
||||
@item
|
||||
@cite{What constitutes an access to an object that has volatile-qualified
|
||||
type (6.7.3).}
|
||||
|
||||
@end itemize
|
||||
|
||||
@node Preprocessing directives implementation
|
||||
@section Preprocessing directives
|
||||
|
||||
@itemize @bullet
|
||||
@item
|
||||
@cite{How sequences in both forms of header names are mapped to headers
|
||||
or external source file names (6.4.7).}
|
||||
|
||||
@item
|
||||
@cite{Whether the value of a character constant in a constant expression
|
||||
that controls conditional inclusion matches the value of the same character
|
||||
constant in the execution character set (6.10.1).}
|
||||
|
||||
@item
|
||||
@cite{Whether the value of a single-character character constant in a
|
||||
constant expression that controls conditional inclusion may have a
|
||||
negative value (6.10.1).}
|
||||
|
||||
@item
|
||||
@cite{The places that are searched for an included @samp{<>} delimited
|
||||
header, and how the places are specified or the header is
|
||||
identified (6.10.2).}
|
||||
|
||||
@item
|
||||
@cite{How the named source file is searched for in an included @samp{""}
|
||||
delimited header (6.10.2).}
|
||||
|
||||
@item
|
||||
@cite{The method by which preprocessing tokens (possibly resulting from
|
||||
macro expansion) in a @code{#include} directive are combined into a header
|
||||
name (6.10.2).}
|
||||
|
||||
@item
|
||||
@cite{The nesting limit for @code{#include} processing (6.10.2).}
|
||||
|
||||
GCC imposes a limit of 200 nested @code{#include}s.
|
||||
|
||||
@item
|
||||
@cite{Whether the @samp{#} operator inserts a @samp{\} character before
|
||||
the @samp{\} character that begins a universal character name in a
|
||||
character constant or string literal (6.10.3.2).}
|
||||
|
||||
@item
|
||||
@cite{The behavior on each recognized non-@code{STDC #pragma}
|
||||
directive (6.10.6).}
|
||||
|
||||
@item
|
||||
@cite{The definitions for @code{__DATE__} and @code{__TIME__} when
|
||||
respectively, the date and time of translation are not available (6.10.8).}
|
||||
|
||||
If the date and time are not available, @code{__DATE__} expands to
|
||||
@code{@w{"??? ?? ????"}} and @code{__TIME__} expands to
|
||||
@code{"??:??:??"}.
|
||||
|
||||
@end itemize
|
||||
|
||||
@node Library functions implementation
|
||||
@section Library functions
|
||||
|
||||
The behavior of these points are dependent on the implementation
|
||||
of the C library, and are not defined by GCC itself.
|
||||
|
||||
@node Architecture implementation
|
||||
@section Architecture
|
||||
|
||||
@itemize @bullet
|
||||
@item
|
||||
@cite{The values or expressions assigned to the macros specified in the
|
||||
headers @code{<float.h>}, @code{<limits.h>}, and @code{<stdint.h>}
|
||||
(5.2.4.2, 7.18.2, 7.18.3).}
|
||||
|
||||
@item
|
||||
@cite{The number, order, and encoding of bytes in any object
|
||||
(when not explicitly specified in this International Standard) (6.2.6.1).}
|
||||
|
||||
@item
|
||||
@cite{The value of the result of the sizeof operator (6.5.3.4).}
|
||||
|
||||
@end itemize
|
||||
|
||||
@node Locale-specific behavior implementation
|
||||
@section Locale-specific behavior
|
||||
|
||||
The behavior of these points are dependent on the implementation
|
||||
of the C library, and are not defined by GCC itself.
|
||||
Loading…
x
Reference in New Issue
Block a user