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Merge from gnulib

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This incorporates:
2015-11-13 xalloc-oversized: improve performance with GCC 5
* lib/xalloc-oversized.h: Copy from gnulib.
This commit is contained in:
Paul Eggert 2015-11-13 12:39:13 -08:00
parent 04ac097f34
commit 92a501022e
1 changed files with 11 additions and 2 deletions
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13
lib/xalloc-oversized.h
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@ -16,9 +16,13 @@
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#ifndef XALLOC_OVERSIZED_H_
# define XALLOC_OVERSIZED_H_
#define XALLOC_OVERSIZED_H_
# include <stddef.h>
#include <stddef.h>
#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
@ -32,7 +36,12 @@
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) \
((size_t) (sizeof (ptrdiff_t) <= sizeof (size_t) ? -1 : -2) / (s) < (n))
#endif
#endif /* !XALLOC_OVERSIZED_H_ */