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x86_64: Remove redundant REX bytes from memchr.S

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By x86-64 specification, 32-bit destination registers are zero-extended
to 64 bits.  There is no need to use 64-bit registers when only the lower
32 bits are non-zero.

	* sysdeps/x86_64/memchr.S (MEMCHR): Use 32-bit registers for
	the lower 32 bits.
This commit is contained in:
H.J. Lu 2017-05-30 12:39:14 -07:00
parent 542a34783c
commit 4f26ef1b67
2 changed files with 19 additions and 14 deletions
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5
ChangeLog
View File

@ -1,3 +1,8 @@
2017-05-30 H.J. Lu <hongjiu.lu@intel.com>
* sysdeps/x86_64/memchr.S (memchr): Use 32-bit registers for
the lower 32 bits.
2017-05-29 Andreas Schwab <schwab@linux-m68k.org>
* sysdeps/m68k/Makefile (ASFLAGS-.o) [$(subdir) = csu &&

28
sysdeps/x86_64/memchr.S
View File

@ -22,18 +22,18 @@
.text
ENTRY(memchr)
movd %rsi, %xmm1
mov %rdi, %rcx
movd %esi, %xmm1
mov %edi, %ecx
punpcklbw %xmm1, %xmm1
test %rdx, %rdx
jz L(return_null)
punpcklbw %xmm1, %xmm1
and $63, %rcx
and $63, %ecx
pshufd $0, %xmm1, %xmm1
cmp $48, %rcx
cmp $48, %ecx
ja L(crosscache)
movdqu (%rdi), %xmm0
@ -45,7 +45,7 @@ ENTRY(memchr)
sub $16, %rdx
jbe L(return_null)
add $16, %rdi
and $15, %rcx
and $15, %ecx
and $-16, %rdi
add %rcx, %rdx
sub $64, %rdx
@ -54,7 +54,7 @@ ENTRY(memchr)
.p2align 4
L(crosscache):
and $15, %rcx
and $15, %ecx
and $-16, %rdi
movdqa (%rdi), %xmm0
@ -148,7 +148,7 @@ L(loop_prolog):
mov %rdi, %rcx
and $-64, %rdi
and $63, %rcx
and $63, %ecx
add %rcx, %rdx
.p2align 4
@ -200,7 +200,7 @@ L(align64_loop):
.p2align 4
L(exit_loop):
add $32, %rdx
add $32, %edx
jle L(exit_loop_32)
movdqa (%rdi), %xmm0
@ -220,32 +220,32 @@ L(exit_loop):
pmovmskb %xmm3, %eax
test %eax, %eax
jnz L(matches32_1)
sub $16, %rdx
sub $16, %edx
jle L(return_null)
pcmpeqb 48(%rdi), %xmm1
pmovmskb %xmm1, %eax
test %eax, %eax
jnz L(matches48_1)
xor %rax, %rax
xor %eax, %eax
ret
.p2align 4
L(exit_loop_32):
add $32, %rdx
add $32, %edx
movdqa (%rdi), %xmm0
pcmpeqb %xmm1, %xmm0
pmovmskb %xmm0, %eax
test %eax, %eax
jnz L(matches_1)
sub $16, %rdx
sub $16, %edx
jbe L(return_null)
pcmpeqb 16(%rdi), %xmm1
pmovmskb %xmm1, %eax
test %eax, %eax
jnz L(matches16_1)
xor %rax, %rax
xor %eax, %eax
ret
.p2align 4
@ -306,7 +306,7 @@ L(matches48_1):
.p2align 4
L(return_null):
xor %rax, %rax
xor %eax, %eax
ret
END(memchr)