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Update from gnulib

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This incorporates:
2016-06-24 intprops: port better to GCC 7
2016-06-13 xalloc-oversized: port to GCC 7; fewer warnings
* doc/misc/texinfo.tex, lib/xalloc-oversized.h, lib/intprops.h:
Copy from gnulib.
This commit is contained in:
Paul Eggert 2016-06-24 13:49:32 +02:00
parent dc49db725e
commit 63457dcfe0
3 changed files with 97 additions and 42 deletions
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44
lib/xalloc-oversized.h
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@ -20,15 +20,13 @@
#include <stddef.h>
/* Default for (non-Clang) compilers that lack __has_builtin. */
#ifndef __has_builtin
# define __has_builtin(x) 0
#endif
/* Return 1 if an array of N objects, each of size S, cannot exist due
to size arithmetic overflow. S must be positive and N must be
nonnegative. This is a macro, not a function, so that it
works correctly even when SIZE_MAX < N.
/* True if N * S would overflow in a size calculation.
This expands to a constant expression if N and S are both constants.
By gnulib convention, SIZE_MAX represents overflow in size
calculations, so the conservative dividend to use here is
SIZE_MAX - 1, since SIZE_MAX might represent an overflowed value.
@ -36,12 +34,38 @@
sizeof (ptrdiff_t) <= sizeof (size_t), so do not bother to test for
exactly-SIZE_MAX allocations on such hosts; this avoids a test and
branch when S is known to be 1. */
#if 5 <= __GNUC__ || __has_builtin (__builtin_mul_overflow)
# define xalloc_oversized(n, s) \
({ size_t __xalloc_size; __builtin_mul_overflow (n, s, &__xalloc_size); })
#else
# define xalloc_oversized(n, s) \
#define __xalloc_oversized(n, s) \
((size_t) (sizeof (ptrdiff_t) <= sizeof (size_t) ? -1 : -2) / (s) < (n))
/* Return 1 if an array of N objects, each of size S, cannot exist due
to size arithmetic overflow. S must be positive and N must be
nonnegative. This is a macro, not a function, so that it
works correctly even when SIZE_MAX < N. */
/* GCC 7 __builtin_mul_overflow should easily compute this. See:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68120 */
#if 7 <= __GNUC__
# define xalloc_oversized(n, s) __builtin_mul_overflow (n, s, (size_t *) NULL)
/* GCC 5 and Clang __builtin_mul_overflow needs a temporary, and
should be used only for non-constant operands, so that
xalloc_oversized is a constant expression if both arguments are.
Do not use this if pedantic, since pedantic GCC issues a diagnostic
for ({ ... }). */
#elif ((5 <= __GNUC__ \
|| (__has_builtin (__builtin_mul_overflow) \
&& __has_builtin (__builtin_constant_p))) \
&& !__STRICT_ANSI__)
# define xalloc_oversized(n, s) \
(__builtin_constant_p (n) && __builtin_constant_p (s) \
? __xalloc_oversized (n, s) \
: ({ size_t __xalloc_size; __builtin_mul_overflow (n, s, &__xalloc_size); }))
/* Other compilers use integer division; this may be slower but is
more portable. */
#else
# define xalloc_oversized(n, s) __xalloc_oversized (n, s)
#endif
#endif /* !XALLOC_OVERSIZED_H_ */