x86_64: Remove redundant REX bytes from memchr.S

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.

diff --git a/ChangeLog b/ChangeLog
index 93f0088ace0e1ab54babf3ba7ce12cad6f988d00..92d762e48cd221a87c045f882467817ce9ddd114 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -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 &&

diff --git a/sysdeps/x86_64/memchr.S b/sysdeps/x86_64/memchr.S
index f82e1c5bf72e901bfd15593165a8a68e6b4a6ce9..d3be01242425cf66293bea89f73ce1bf85492917 100644 (file)
--- a/sysdeps/x86_64/memchr.S
+++ b/sysdeps/x86_64/memchr.S
@@ -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)