Following a change in Linux 2.6.33, make x86-32 always use
__builtin_mem{cpy,set}() on gcc 4.0+. This particularly works around
certain intermediate gcc revisions generating out-of-range-array-index
warnings with the current inline implementation.
It may be worthwhile considering to make this the case for x86-64 too.
At the same time eliminate the redundant inline assembly in the C
file, and instead use the inline functions coming from the header.
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>
--- 2010-05-04.orig/xen/arch/x86/string.c 2007-11-26 16:57:03.000000000
+0100
+++ 2010-05-04/xen/arch/x86/string.c 2010-05-11 09:45:27.000000000 +0200
@@ -11,44 +11,13 @@
#undef memcpy
void *memcpy(void *dest, const void *src, size_t n)
{
- long d0, d1, d2;
-
- asm volatile (
-#ifdef __i386__
- " rep movsl ; "
-#else
- " rep movsq ; "
- " testb $4,%b4 ; "
- " je 0f ; "
- " movsl ; "
- "0: ; "
-#endif
- " testb $2,%b4 ; "
- " je 1f ; "
- " movsw ; "
- "1: testb $1,%b4 ; "
- " je 2f ; "
- " movsb ; "
- "2: "
- : "=&c" (d0), "=&D" (d1), "=&S" (d2)
- : "0" (n/sizeof(long)), "q" (n), "1" (dest), "2" (src)
- : "memory");
-
- return dest;
+ return __variable_memcpy(dest, src, n);
}
#undef memset
void *memset(void *s, int c, size_t n)
{
- long d0, d1;
-
- asm volatile (
- "rep stosb"
- : "=&c" (d0), "=&D" (d1)
- : "a" (c), "1" (s), "0" (n)
- : "memory");
-
- return s;
+ return __memset_generic(s, c, n);
}
#undef memmove
--- 2010-05-04.orig/xen/include/asm-x86/string.h 2009-10-07
13:31:36.000000000 +0200
+++ 2010-05-04/xen/include/asm-x86/string.h 2010-05-11 10:21:04.000000000
+0200
@@ -16,6 +16,11 @@ static inline void *__variable_memcpy(vo
return to;
}
+#define __HAVE_ARCH_MEMCPY
+#if defined(__i386__) && __GNUC__ >= 4
+#define memcpy(t, f, n) __builtin_memcpy(t, f, n)
+#else
+
/*
* This looks horribly ugly, but the compiler can optimize it totally,
* as the count is constant.
@@ -95,7 +100,6 @@ static always_inline void * __constant_m
return to;
}
-#define __HAVE_ARCH_MEMCPY
/* align source to a 64-bit boundary */
static always_inline
void *__var_memcpy(void *t, const void *f, size_t n)
@@ -121,11 +125,13 @@ void *__memcpy(void *t, const void *f, s
__var_memcpy((t),(f),(n)));
}
+#endif /* !__i386__ || __GNUC__ < 4 */
+
/* Some version of gcc don't have this builtin. It's non-critical anyway. */
#define __HAVE_ARCH_MEMMOVE
extern void *memmove(void *dest, const void *src, size_t n);
-static inline void *__memset_generic(void *s, char c, size_t count)
+static inline void *__memset_generic(void *s, int c, size_t count)
{
long d0, d1;
__asm__ __volatile__ (
@@ -134,6 +140,11 @@ static inline void *__memset_generic(voi
return s;
}
+#define __HAVE_ARCH_MEMSET
+#if defined(__i386__) && __GNUC__ >= 4
+#define memset(s, c, n) __builtin_memset(s, c, n)
+#else
+
/* we might want to write optimized versions of these later */
#define __constant_count_memset(s,c,count) __memset_generic((s),(c),(count))
@@ -238,11 +249,12 @@ static always_inline void *__constant_c_
#define MEMSET_PATTERN_MUL 0x01010101UL
#endif
-#define __HAVE_ARCH_MEMSET
#define memset(s, c, count) (__memset((s),(c),(count)))
#define __memset(s, c, count) \
(__builtin_constant_p(c) ? \
__constant_c_x_memset((s),(MEMSET_PATTERN_MUL*(unsigned char)(c)),(count)) : \
__var_x_memset((s),(c),(count)))
+#endif /* !__i386__ || __GNUC__ < 4 */
+
#endif /* __X86_STRING_H__ */
x86-memcpy.patch
Description: Text document
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