[PATCH] fix i386 memcpy
This patch shortens non-constant memcpy() by two bytes and fixes spurious out-of-line constant memcpy(). # size vmlinux.org vmlinux text data bss dec hex filename 3954591 1553426 236544 5744561 57a7b1 vmlinux.org 3952615 1553426 236544 5742585 579ff9 vmlinux Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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@ -198,46 +198,79 @@ static inline void * __memcpy(void * to, const void * from, size_t n)
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int d0, d1, d2;
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__asm__ __volatile__(
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"rep ; movsl\n\t"
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"testb $2,%b4\n\t"
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"je 1f\n\t"
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"movsw\n"
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"1:\ttestb $1,%b4\n\t"
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"je 2f\n\t"
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"movsb\n"
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"2:"
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"movl %4,%%ecx\n\t"
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"andl $3,%%ecx\n\t"
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#if 1 /* want to pay 2 byte penalty for a chance to skip microcoded rep? */
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"jz 1f\n\t"
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#endif
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"rep ; movsb\n\t"
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"1:"
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: "=&c" (d0), "=&D" (d1), "=&S" (d2)
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:"0" (n/4), "q" (n),"1" ((long) to),"2" ((long) from)
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: "0" (n/4), "g" (n), "1" ((long) to), "2" ((long) from)
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: "memory");
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return (to);
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}
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/*
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* This looks horribly ugly, but the compiler can optimize it totally,
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* This looks ugly, but the compiler can optimize it totally,
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* as the count is constant.
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*/
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static inline void * __constant_memcpy(void * to, const void * from, size_t n)
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{
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if (n <= 128)
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return __builtin_memcpy(to, from, n);
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#define COMMON(x) \
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__asm__ __volatile__( \
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"rep ; movsl" \
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x \
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: "=&c" (d0), "=&D" (d1), "=&S" (d2) \
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: "0" (n/4),"1" ((long) to),"2" ((long) from) \
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: "memory");
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{
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int d0, d1, d2;
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switch (n % 4) {
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case 0: COMMON(""); return to;
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case 1: COMMON("\n\tmovsb"); return to;
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case 2: COMMON("\n\tmovsw"); return to;
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default: COMMON("\n\tmovsw\n\tmovsb"); return to;
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long esi, edi;
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if (!n) return to;
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#if 1 /* want to do small copies with non-string ops? */
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switch (n) {
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case 1: *(char*)to = *(char*)from; return to;
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case 2: *(short*)to = *(short*)from; return to;
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case 4: *(int*)to = *(int*)from; return to;
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#if 1 /* including those doable with two moves? */
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case 3: *(short*)to = *(short*)from;
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*((char*)to+2) = *((char*)from+2); return to;
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case 5: *(int*)to = *(int*)from;
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*((char*)to+4) = *((char*)from+4); return to;
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case 6: *(int*)to = *(int*)from;
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*((short*)to+2) = *((short*)from+2); return to;
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case 8: *(int*)to = *(int*)from;
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*((int*)to+1) = *((int*)from+1); return to;
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#endif
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}
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#endif
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esi = (long) from;
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edi = (long) to;
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if (n >= 5*4) {
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/* large block: use rep prefix */
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int ecx;
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__asm__ __volatile__(
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"rep ; movsl"
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: "=&c" (ecx), "=&D" (edi), "=&S" (esi)
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: "0" (n/4), "1" (edi),"2" (esi)
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: "memory"
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);
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} else {
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/* small block: don't clobber ecx + smaller code */
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if (n >= 4*4) __asm__ __volatile__("movsl"
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:"=&D"(edi),"=&S"(esi):"0"(edi),"1"(esi):"memory");
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if (n >= 3*4) __asm__ __volatile__("movsl"
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:"=&D"(edi),"=&S"(esi):"0"(edi),"1"(esi):"memory");
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if (n >= 2*4) __asm__ __volatile__("movsl"
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:"=&D"(edi),"=&S"(esi):"0"(edi),"1"(esi):"memory");
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if (n >= 1*4) __asm__ __volatile__("movsl"
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:"=&D"(edi),"=&S"(esi):"0"(edi),"1"(esi):"memory");
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}
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switch (n % 4) {
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/* tail */
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case 0: return to;
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case 1: __asm__ __volatile__("movsb"
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:"=&D"(edi),"=&S"(esi):"0"(edi),"1"(esi):"memory");
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return to;
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case 2: __asm__ __volatile__("movsw"
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:"=&D"(edi),"=&S"(esi):"0"(edi),"1"(esi):"memory");
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return to;
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default: __asm__ __volatile__("movsw\n\tmovsb"
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:"=&D"(edi),"=&S"(esi):"0"(edi),"1"(esi):"memory");
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return to;
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}
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}
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#undef COMMON
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}
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#define __HAVE_ARCH_MEMCPY
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