Mailing List Archive

# HG changeset patch
# User Keir Fraser <keir.fraser@citrix.com>
# Date 1273583128 -3600
# Node ID d77a88f938c635c3ccfedaa00f946e4d9ed26098
# Parent 2b5e14e4c5e57b0064d1c0415d9c4629bd0aac9b
x86: Replace our own specialised versions of memset and memcpy with
direct use of gcc's built-in versions.

This dramatically simplifies our code while also avoiding compile
warnings with certain intermediate versions of gcc.

This patch is based on an initial version by Jan Beulich.

Signed-off-by: Keir Fraser <keir.fraser@citrix.com>
---
xen/arch/x86/string.c | 25 +---
xen/include/asm-x86/string.h | 240 -------------------------------------------
2 files changed, 10 insertions(+), 255 deletions(-)

diff -r 2b5e14e4c5e5 -r d77a88f938c6 xen/arch/x86/string.c
--- a/xen/arch/x86/string.c Tue May 11 12:37:26 2010 +0100
+++ b/xen/arch/x86/string.c Tue May 11 14:05:28 2010 +0100
@@ -14,25 +14,12 @@ void *memcpy(void *dest, const void *src
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: "
+ " rep ; movs"__OS" ; "
+ " mov %4,%3 ; "
+ " rep ; movsb "
: "=&c" (d0), "=&D" (d1), "=&S" (d2)
- : "0" (n/sizeof(long)), "q" (n), "1" (dest), "2" (src)
- : "memory");
+ : "0" (n/BYTES_PER_LONG), "r" (n%BYTES_PER_LONG), "1" (dest), "2" (src)
+ : "memory" );

return dest;
}
@@ -55,7 +42,7 @@ void *memmove(void *dest, const void *sr
void *memmove(void *dest, const void *src, size_t n)
{
long d0, d1, d2;
-
+
if ( dest < src )
return memcpy(dest, src, n);

diff -r 2b5e14e4c5e5 -r d77a88f938c6 xen/include/asm-x86/string.h
--- a/xen/include/asm-x86/string.h Tue May 11 12:37:26 2010 +0100
+++ b/xen/include/asm-x86/string.h Tue May 11 14:05:28 2010 +0100
@@ -3,246 +3,14 @@

#include <xen/config.h>

-static inline void *__variable_memcpy(void *to, const void *from, size_t n)
-{
- long d0, d1, d2;
- __asm__ __volatile__ (
- " rep ; movs"__OS"\n"
- " mov %4,%3 \n"
- " rep ; movsb \n"
- : "=&c" (d0), "=&D" (d1), "=&S" (d2)
- : "0" (n/BYTES_PER_LONG), "r" (n%BYTES_PER_LONG), "1" (to), "2" (from)
- : "memory" );
- return to;
-}
+#define __HAVE_ARCH_MEMCPY
+#define memcpy(t,f,n) (__builtin_memcpy((t),(f),(n)))

-/*
- * This looks horribly ugly, but the compiler can optimize it totally,
- * as the count is constant.
- */
-static always_inline void * __constant_memcpy(
- void * to, const void * from, size_t n)
-{
- switch ( n )
- {
- case 0:
- return to;
- case 1:
- *(u8 *)to = *(const u8 *)from;
- return to;
- case 2:
- *(u16 *)to = *(const u16 *)from;
- return to;
- case 3:
- *(u16 *)to = *(const u16 *)from;
- *(2+(u8 *)to) = *(2+(const u8 *)from);
- return to;
- case 4:
- *(u32 *)to = *(const u32 *)from;
- return to;
- case 5:
- *(u32 *)to = *(const u32 *)from;
- *(4+(u8 *)to) = *(4+(const u8 *)from);
- return to;
- case 6:
- *(u32 *)to = *(const u32 *)from;
- *(2+(u16 *)to) = *(2+(const u16 *)from);
- return to;
- case 7:
- *(u32 *)to = *(const u32 *)from;
- *(2+(u16 *)to) = *(2+(const u16 *)from);
- *(6+(u8 *)to) = *(6+(const u8 *)from);
- return to;
- case 8:
- *(u64 *)to = *(const u64 *)from;
- return to;
- case 12:
- *(u64 *)to = *(const u64 *)from;
- *(2+(u32 *)to) = *(2+(const u32 *)from);
- return to;
- case 16:
- *(u64 *)to = *(const u64 *)from;
- *(1+(u64 *)to) = *(1+(const u64 *)from);
- return to;
- case 20:
- *(u64 *)to = *(const u64 *)from;
- *(1+(u64 *)to) = *(1+(const u64 *)from);
- *(4+(u32 *)to) = *(4+(const u32 *)from);
- return to;
- }
-#define COMMON(x) \
- __asm__ __volatile__ ( \
- "rep ; movs"__OS \
- x \
- : "=&c" (d0), "=&D" (d1), "=&S" (d2) \
- : "0" (n/BYTES_PER_LONG), "1" (to), "2" (from) \
- : "memory" );
- {
- long d0, d1, d2;
- switch ( n % BYTES_PER_LONG )
- {
- case 0: COMMON(""); return to;
- case 1: COMMON("\n\tmovsb"); return to;
- case 2: COMMON("\n\tmovsw"); return to;
- case 3: COMMON("\n\tmovsw\n\tmovsb"); return to;
- case 4: COMMON("\n\tmovsl"); return to;
- case 5: COMMON("\n\tmovsl\n\tmovsb"); return to;
- case 6: COMMON("\n\tmovsl\n\tmovsw"); return to;
- case 7: COMMON("\n\tmovsl\n\tmovsw\n\tmovsb"); return to;
- }
- }
-#undef COMMON
- 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)
-{
- int off = (unsigned long)f & 0x7;
- /* just do alignment if needed and if size is worth */
- if ( (n > 32) && off ) {
- size_t n1 = 8 - off;
- __variable_memcpy(t, f, n1);
- __variable_memcpy(t + n1, f + n1, n - n1);
- return t;
- } else {
- return (__variable_memcpy(t, f, n));
- }
-}
-
-#define memcpy(t,f,n) (__memcpy((t),(f),(n)))
-static always_inline
-void *__memcpy(void *t, const void *f, size_t n)
-{
- return (__builtin_constant_p(n) ?
- __constant_memcpy((t),(f),(n)) :
- __var_memcpy((t),(f),(n)));
-}
-
-/* Some version of gcc don't have this builtin. It's non-critical anyway. */
+/* Some versions 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)
-{
- long d0, d1;
- __asm__ __volatile__ (
- "rep ; stosb"
- : "=&c" (d0), "=&D" (d1) : "a" (c), "1" (s), "0" (count) : "memory" );
- return s;
-}
-
-/* we might want to write optimized versions of these later */
-#define __constant_count_memset(s,c,count) __memset_generic((s),(c),(count))
-
-/*
- * memset(x,0,y) is a reasonably common thing to do, so we want to fill
- * things 32 bits at a time even when we don't know the size of the
- * area at compile-time..
- */
-static inline void *__constant_c_memset(void *s, unsigned long c, size_t count)
-{
- long d0, d1;
- __asm__ __volatile__(
- " rep ; stos"__OS"\n"
- " mov %3,%4 \n"
- " rep ; stosb \n"
- : "=&c" (d0), "=&D" (d1)
- : "a" (c), "r" (count%BYTES_PER_LONG),
- "0" (count/BYTES_PER_LONG), "1" (s)
- : "memory" );
- return s;
-}
-
-/*
- * This looks horribly ugly, but the compiler can optimize it totally,
- * as we by now know that both pattern and count is constant..
- */
-static always_inline void *__constant_c_and_count_memset(
- void *s, unsigned long pattern, size_t count)
-{
- switch ( count )
- {
- case 0:
- return s;
- case 1:
- *(u8 *)s = pattern;
- return s;
- case 2:
- *(u16 *)s = pattern;
- return s;
- case 3:
- *(u16 *)s = pattern;
- *(2+(u8 *)s) = pattern;
- return s;
- case 4:
- *(u32 *)s = pattern;
- return s;
- case 5:
- *(u32 *)s = pattern;
- *(4+(u8 *)s) = pattern;
- return s;
- case 6:
- *(u32 *)s = pattern;
- *(2+(u16 *)s) = pattern;
- return s;
- case 7:
- *(u32 *)s = pattern;
- *(2+(u16 *)s) = pattern;
- *(6+(u8 *)s) = pattern;
- return s;
- case 8:
- *(u64 *)s = pattern;
- return s;
- }
-#define COMMON(x) \
- __asm__ __volatile__ ( \
- "rep ; stos"__OS \
- x \
- : "=&c" (d0), "=&D" (d1) \
- : "a" (pattern), "0" (count/BYTES_PER_LONG), "1" (s) \
- : "memory" )
- {
- long d0, d1;
- switch ( count % BYTES_PER_LONG )
- {
- case 0: COMMON(""); return s;
- case 1: COMMON("\n\tstosb"); return s;
- case 2: COMMON("\n\tstosw"); return s;
- case 3: COMMON("\n\tstosw\n\tstosb"); return s;
- case 4: COMMON("\n\tstosl"); return s;
- case 5: COMMON("\n\tstosl\n\tstosb"); return s;
- case 6: COMMON("\n\tstosl\n\tstosw"); return s;
- case 7: COMMON("\n\tstosl\n\tstosw\n\tstosb"); return s;
- }
- }
-#undef COMMON
- return s;
-}
-
-#define __constant_c_x_memset(s, c, count) \
-(__builtin_constant_p(count) ? \
- __constant_c_and_count_memset((s),(c),(count)) : \
- __constant_c_memset((s),(c),(count)))
-
-#define __var_x_memset(s, c, count) \
-(__builtin_constant_p(count) ? \
- __constant_count_memset((s),(c),(count)) : \
- __memset_generic((s),(c),(count)))
-
-#ifdef CONFIG_X86_64
-#define MEMSET_PATTERN_MUL 0x0101010101010101UL
-#else
-#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)))
+#define memset(s,c,n) (__builtin_memset((s),(c),(n)))

#endif /* __X86_STRING_H__ */

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