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1999-04-30 09:02 -0400  Zack Weinberg  <zack@rabi.columbia.edu>

	* string/bits/string2.h (memset): Avoid arithmetic overflow at
	compile time, which produces obnoxious warnings.  If GCCv2 is
	in use, map __bzero to __builtin_memset to enable that
	optimization.
This commit is contained in:
Ulrich Drepper
1999-04-30 09:36:37 +00:00
parent 9943472996
commit c1d226e77f
2 changed files with 17 additions and 3 deletions
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13
string/bits/string2.h
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@ -95,13 +95,15 @@ __STRING2_COPY_TYPE (8);
#ifndef _HAVE_STRING_ARCH_memset
# define memset(s, c, n) \
(__extension__ (__builtin_constant_p (n) && (n) <= 16 \
? (__builtin_constant_p (c) \
? __memset_gc (s, (c) * 0x01010101, n) \
: __memset_gc (s, (n) == 1 ? (c) : (c) * 0x01010101, n)) \
? ((n) == 1 \
? __memset_1 (s, c) \
: __memset_gc (s, (((__uint8_t) c) * 0x1010101), n)) \
: (__builtin_constant_p (c) && (c) == '\0' \
? ({ void *__s = (s); __bzero (__s, n); __s; }) \
: memset (s, c, n))))
#define __memset_1(s, c) ({ void *__s = (s); *((__uint8_t *) __s) = c; __s; })
#define __memset_gc(s, c, n) \
({ void *__s = (s); \
__uint32_t *__ts = (__uint32_t *) __s; \
@ -153,6 +155,11 @@ __STRING2_COPY_TYPE (8);
} \
\
__s; })
/* GCC optimizes memset(s, 0, n) but not bzero(s, n). */
#if defined __GNUC__ && __GNUC__ >= 2
# define __bzero(s, n) __builtin_memset(s, '\0', n)
#endif
#endif