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amd64: sync up libc memcmp with the kernel version (r357309)

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This commit is contained in:
Mateusz Guzik 2020-01-30 19:57:05 +00:00
parent aa88cc44f3
commit 8291e88748
1 changed files with 48 additions and 57 deletions
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105
lib/libc/amd64/string/memcmp.S
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@ -45,7 +45,7 @@ ENTRY(memcmp)
movq (%rdi),%r8
movq (%rsi),%r9
cmpq %r8,%r9
jne 1f
jne 80f
movq -8(%rdi,%rdx),%r8
movq -8(%rsi,%rdx),%r9
cmpq %r8,%r9
@ -54,34 +54,33 @@ ENTRY(memcmp)
100408:
cmpb $4,%dl
jl 100204f
movl (%rsi),%r8d
movl (%rdi),%r9d
movl (%rdi),%r8d
movl (%rsi),%r9d
cmpl %r8d,%r9d
jne 1f
movl -4(%rsi,%rdx),%r8d
movl -4(%rdi,%rdx),%r9d
jne 80f
movl -4(%rdi,%rdx),%r8d
movl -4(%rsi,%rdx),%r9d
cmpl %r8d,%r9d
jne 1f
jne 10040804f
ret
100204:
cmpb $2,%dl
jl 100001f
movzwl (%rsi),%r8d
movzwl (%rdi),%r9d
movzwl (%rdi),%r8d
movzwl (%rsi),%r9d
cmpl %r8d,%r9d
jne 1f
movzwl -2(%rsi,%rdx),%r8d
movzwl -2(%rdi,%rdx),%r9d
movzwl -2(%rdi,%rdx),%r8d
movzwl -2(%rsi,%rdx),%r9d
cmpl %r8d,%r9d
jne 1f
ret
100001:
cmpb $1,%dl
jl 100000f
movzbl (%rdi),%r8d
movzbl (%rsi),%r9d
cmpb %r8b,%r9b
jne 1f
movzbl (%rdi),%eax
movzbl (%rsi),%r8d
subl %r8d,%eax
100000:
ret
ALIGN_TEXT
@ -91,11 +90,11 @@ ALIGN_TEXT
movq (%rdi),%r8
movq (%rsi),%r9
cmpq %r8,%r9
jne 1f
jne 80f
movq 8(%rdi),%r8
movq 8(%rsi),%r9
cmpq %r8,%r9
jne 10163208f
jne 10163208f
movq -16(%rdi,%rdx),%r8
movq -16(%rsi,%rdx),%r9
cmpq %r8,%r9
@ -111,14 +110,14 @@ ALIGN_TEXT
movq 8(%rdi),%r9
subq (%rsi),%r8
subq 8(%rsi),%r9
or %r8,%r9
orq %r8,%r9
jnz 10320000f
movq 16(%rdi),%r8
movq 24(%rdi),%r9
subq 16(%rsi),%r8
subq 24(%rsi),%r9
or %r8,%r9
orq %r8,%r9
jnz 10320016f
leaq 32(%rdi),%rdi
@ -130,40 +129,57 @@ ALIGN_TEXT
jne 10b
ret
/*
* Mismatch was found.
*
* Before we compute it we narrow down the range (16 -> 8 -> 4 bytes).
*/
ALIGN_TEXT
10320016:
leaq 16(%rdi),%rdi
leaq 16(%rsi),%rsi
10320000:
/*
* Mismatch was found within a 16 bytes range. The part of the routine
* which calculates it only operates on sizes up to 8 bytes. Find the
* right part.
*/
movq (%rdi),%r8
movq (%rsi),%r9
cmpq %r8,%r9
jne 1f
jne 80f
leaq 8(%rdi),%rdi
leaq 8(%rsi),%rsi
jmp 1f
jmp 80f
ALIGN_TEXT
10081608:
10163224:
leaq -8(%rdi,%rdx),%rdi
leaq -8(%rsi,%rdx),%rsi
jmp 1f
jmp 80f
ALIGN_TEXT
10163216:
leaq -16(%rdi,%rdx),%rdi
leaq -16(%rsi,%rdx),%rsi
jmp 1f
jmp 80f
ALIGN_TEXT
10163208:
10081608:
leaq 8(%rdi),%rdi
leaq 8(%rsi),%rsi
jmp 80f
ALIGN_TEXT
10040804:
leaq -4(%rdi,%rdx),%rdi
leaq -4(%rsi,%rdx),%rsi
jmp 1f
/*
* Mismatch was found. We have no more than 8 bytes to inspect.
*/
ALIGN_TEXT
80:
movl (%rdi),%r8d
movl (%rsi),%r9d
cmpl %r8d,%r9d
jne 1f
leaq 4(%rdi),%rdi
leaq 4(%rsi),%rsi
/*
* We have up to 4 bytes to inspect.
*/
1:
movzbl (%rdi),%eax
movzbl (%rsi),%r8d
@ -182,31 +198,6 @@ ALIGN_TEXT
movzbl 3(%rdi),%eax
movzbl 3(%rsi),%r8d
cmpb %r8b,%al
jne 2f
movzbl 4(%rdi),%eax
movzbl 4(%rsi),%r8d
cmpb %r8b,%al
jne 2f
movzbl 5(%rdi),%eax
movzbl 5(%rsi),%r8d
cmpb %r8b,%al
jne 2f
movzbl 6(%rdi),%eax
movzbl 6(%rsi),%r8d
cmpb %r8b,%al
jne 2f
movzbl 7(%rdi),%eax
movzbl 7(%rsi),%r8d
cmpb %r8b,%al
jne 2f
xorl %eax,%eax
ret
2:
subl %r8d,%eax
ret