(memset): Avoid arithmetic overflow at compile time, which produces
authordrepper <drepper>
Fri, 30 Apr 1999 09:36:19 +0000 (09:36 +0000)
committerdrepper <drepper>
Fri, 30 Apr 1999 09:36:19 +0000 (09:36 +0000)
obnoxious warnings.  If GCCv2 is in use, map __bzero to
__builtin_memset to enable that optimization.

string/bits/string2.h

index d9ed80b..391859a 100644 (file)
@@ -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