Libc-594.9.5.tar.gz

[apple/libc.git] / x86_64 / string / strlen.s

diff --git a/x86_64/string/strlen.s b/x86_64/string/strlen.s
index 51def0c31fd240eba8108bab9e443e9649544fee..54ea653ac241e70a24c409de06b9b3224a79688a 100644 (file)
--- a/x86_64/string/strlen.s
+++ b/x86_64/string/strlen.s
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2005 Apple Computer, Inc. All rights reserved.
+ * Copyright (c) 2005-2007 Apple Inc. All rights reserved.
  *
  * @APPLE_LICENSE_HEADER_START@
  *
@@ -36,8 +36,8 @@
         .align  4, 0x90
 _strlen:                               // size_t strlen(char *b);
        pxor    %xmm0,%xmm0             // zero %xmm0
-       movq    %rdi,%rcx               // copy ptr
-       movq    %rdi,%rdx               // make another copy
+       movl    %edi,%ecx               // copy low half of ptr
+       movq    %rdi,%rdx               // make another full copy
        andq    $(-16),%rdi             // 16-byte align ptr
        orl     $(-1),%eax
        pcmpeqb (%rdi),%xmm0            // check whole qw for 0s
@@ -53,9 +53,8 @@ _strlen:                              // size_t strlen(char *b);
 
 LFoundIt:
        bsf     %ecx,%eax               // find first 1-bit (ie, first 0-byte)
-       movq    %rdx,%rcx               // recover ptr to 1st byte in string
-       addq    %rdi,%rax               // get address of the 0-byte
-       subq    %rcx,%rax               // subtract address of 1st byte to get string length
+       subq    %rdx,%rdi               // get length to start of 16-byte block while we wait
+       addq    %rdi,%rax               // add bytes in 16-byte block
        ret
        
 // Loop over aligned 16-byte blocks: