amd64: tidy up copying backwards in memmove
For non-ERMS case the code used handle possible trailing bytes with movsb first and then followed it up with movsq. This also happened to alter how calculations were done for other cases. Handle the tail with regular movs, just like when copying forward. Use leaq to calculate the right offset from the get go, instead of doing separate add and sub. This adjusts the offset for non-rep cases so that they can be used to handle the tail. The routine is still a work in progress. Sponsored by: The FreeBSD Foundation
This commit is contained in:
Mateusz Guzik
parent
31562c4440
commit
dd219e5ea5
@ -150,24 +150,24 @@ __FBSDID("$FreeBSD$");
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*/
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ALIGN_TEXT
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2:
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addq %rcx,%rdi
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addq %rcx,%rsi
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cmpq $256,%rcx
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ja 2256f
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leaq -8(%rdi,%rcx),%rdi
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leaq -8(%rsi,%rcx),%rsi
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cmpq $32,%rcx
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jb 2016f
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cmpq $256,%rcx
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ja 2256f
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2032:
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movq (%rsi),%rdx
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movq %rdx,(%rdi)
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movq -8(%rsi),%rdx
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movq %rdx,-8(%rdi)
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movq -16(%rsi),%rdx
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movq %rdx,-16(%rdi)
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movq -24(%rsi),%rdx
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movq %rdx,-24(%rdi)
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movq -32(%rsi),%rdx
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movq %rdx,-32(%rdi)
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leaq -32(%rsi),%rsi
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leaq -32(%rdi),%rdi
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subq $32,%rcx
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@ -181,10 +181,10 @@ __FBSDID("$FreeBSD$");
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2016:
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cmpb $16,%cl
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jl 2008f
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movq (%rsi),%rdx
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movq %rdx,(%rdi)
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movq -8(%rsi),%rdx
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movq %rdx,-8(%rdi)
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movq -16(%rsi),%rdx
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movq %rdx,-16(%rdi)
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subb $16,%cl
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jz 2000f
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leaq -16(%rsi),%rsi
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@ -192,8 +192,8 @@ __FBSDID("$FreeBSD$");
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2008:
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cmpb $8,%cl
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jl 2004f
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movq -8(%rsi),%rdx
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movq %rdx,-8(%rdi)
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movq (%rsi),%rdx
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movq %rdx,(%rdi)
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subb $8,%cl
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jz 2000f
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leaq -8(%rsi),%rsi
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@ -201,8 +201,8 @@ __FBSDID("$FreeBSD$");
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2004:
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cmpb $4,%cl
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jl 2002f
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movl -4(%rsi),%edx
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movl %edx,-4(%rdi)
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movl 4(%rsi),%edx
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movl %edx,4(%rdi)
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subb $4,%cl
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jz 2000f
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leaq -4(%rsi),%rsi
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@ -210,8 +210,8 @@ __FBSDID("$FreeBSD$");
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2002:
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cmpb $2,%cl
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jl 2001f
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movw -2(%rsi),%dx
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movw %dx,-2(%rdi)
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movw 6(%rsi),%dx
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movw %dx,6(%rdi)
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subb $2,%cl
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jz 2000f
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leaq -2(%rsi),%rsi
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@ -219,33 +219,31 @@ __FBSDID("$FreeBSD$");
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2001:
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cmpb $1,%cl
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jl 2000f
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movb -1(%rsi),%dl
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movb %dl,-1(%rdi)
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movb 7(%rsi),%dl
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movb %dl,7(%rdi)
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2000:
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\end
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ret
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ALIGN_TEXT
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2256:
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decq %rdi
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decq %rsi
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std
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.if \erms == 1
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leaq -1(%rdi,%rcx),%rdi
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leaq -1(%rsi,%rcx),%rsi
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rep
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movsb
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cld
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.else
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andq $7,%rcx /* any fractional bytes? */
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je 3f
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rep
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movsb
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3:
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movq %rdx,%rcx /* copy remainder by 32-bit words */
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leaq -8(%rdi,%rcx),%rdi
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leaq -8(%rsi,%rcx),%rsi
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shrq $3,%rcx
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subq $7,%rsi
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subq $7,%rdi
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rep
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movsq
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.endif
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cld
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movq %rdx,%rcx
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andb $7,%cl
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jne 2004b
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.endif
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\end
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ret
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.endif
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@ -313,24 +313,24 @@ END(memcmp)
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*/
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ALIGN_TEXT
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2:
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addq %rcx,%rdi
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addq %rcx,%rsi
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cmpq $256,%rcx
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ja 2256f
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leaq -8(%rdi,%rcx),%rdi
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leaq -8(%rsi,%rcx),%rsi
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cmpq $32,%rcx
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jb 2016f
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cmpq $256,%rcx
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ja 2256f
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2032:
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movq (%rsi),%rdx
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movq %rdx,(%rdi)
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movq -8(%rsi),%rdx
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movq %rdx,-8(%rdi)
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movq -16(%rsi),%rdx
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movq %rdx,-16(%rdi)
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movq -24(%rsi),%rdx
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movq %rdx,-24(%rdi)
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movq -32(%rsi),%rdx
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movq %rdx,-32(%rdi)
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leaq -32(%rsi),%rsi
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leaq -32(%rdi),%rdi
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subq $32,%rcx
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@ -344,10 +344,10 @@ END(memcmp)
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2016:
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cmpb $16,%cl
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jl 2008f
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movq (%rsi),%rdx
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movq %rdx,(%rdi)
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movq -8(%rsi),%rdx
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movq %rdx,-8(%rdi)
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movq -16(%rsi),%rdx
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movq %rdx,-16(%rdi)
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subb $16,%cl
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jz 2000f
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leaq -16(%rsi),%rsi
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@ -355,8 +355,8 @@ END(memcmp)
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2008:
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cmpb $8,%cl
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jl 2004f
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movq -8(%rsi),%rdx
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movq %rdx,-8(%rdi)
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movq (%rsi),%rdx
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movq %rdx,(%rdi)
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subb $8,%cl
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jz 2000f
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leaq -8(%rsi),%rsi
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@ -364,8 +364,8 @@ END(memcmp)
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2004:
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cmpb $4,%cl
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jl 2002f
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movl -4(%rsi),%edx
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movl %edx,-4(%rdi)
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movl 4(%rsi),%edx
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movl %edx,4(%rdi)
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subb $4,%cl
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jz 2000f
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leaq -4(%rsi),%rsi
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@ -373,8 +373,8 @@ END(memcmp)
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2002:
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cmpb $2,%cl
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jl 2001f
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movw -2(%rsi),%dx
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movw %dx,-2(%rdi)
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movw 6(%rsi),%dx
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movw %dx,6(%rdi)
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subb $2,%cl
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jz 2000f
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leaq -2(%rsi),%rsi
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@ -382,33 +382,31 @@ END(memcmp)
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2001:
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cmpb $1,%cl
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jl 2000f
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movb -1(%rsi),%dl
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movb %dl,-1(%rdi)
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movb 7(%rsi),%dl
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movb %dl,7(%rdi)
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2000:
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\end
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ret
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ALIGN_TEXT
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2256:
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decq %rdi
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decq %rsi
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std
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.if \erms == 1
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leaq -1(%rdi,%rcx),%rdi
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leaq -1(%rsi,%rcx),%rsi
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rep
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movsb
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cld
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.else
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andq $7,%rcx /* any fractional bytes? */
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je 3f
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rep
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movsb
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3:
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movq %rdx,%rcx /* copy remainder by 32-bit words */
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leaq -8(%rdi,%rcx),%rdi
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leaq -8(%rsi,%rcx),%rsi
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shrq $3,%rcx
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subq $7,%rsi
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subq $7,%rdi
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rep
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movsq
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.endif
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cld
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movq %rdx,%rcx
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andb $7,%cl
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jne 2004b
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.endif
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\end
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ret
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.endif
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