diff options
Diffstat (limited to 'libc/sysdeps/i386/i686/multiarch/strlen.S')
| -rw-r--r-- | libc/sysdeps/i386/i686/multiarch/strlen.S | 83 |
1 files changed, 4 insertions, 79 deletions
diff --git a/libc/sysdeps/i386/i686/multiarch/strlen.S b/libc/sysdeps/i386/i686/multiarch/strlen.S index 9786add74..9d465c845 100644 --- a/libc/sysdeps/i386/i686/multiarch/strlen.S +++ b/libc/sysdeps/i386/i686/multiarch/strlen.S @@ -1,5 +1,5 @@ /* Multiple versions of strlen - Copyright (C) 2009 Free Software Foundation, Inc. + Copyright (C) 2009, 2010 Free Software Foundation, Inc. Contributed by Intel Corporation. This file is part of the GNU C Library. @@ -48,6 +48,9 @@ ENTRY(strlen) 1: leal __strlen_ia32@GOTOFF(%ebx), %eax testl $bit_SSE2, CPUID_OFFSET+index_SSE2+__cpu_features@GOTOFF(%ebx) jz 2f + leal __strlen_sse2_bsf@GOTOFF(%ebx), %eax + testl $bit_Slow_BSF, FEATURE_OFFSET+index_Slow_BSF+__cpu_features@GOTOFF(%ebx) + jz 2f leal __strlen_sse2@GOTOFF(%ebx), %eax 2: popl %ebx cfi_adjust_cfa_offset (-4); @@ -55,84 +58,6 @@ ENTRY(strlen) ret END(strlen) -#define CFI_POP(REG) \ - cfi_adjust_cfa_offset (-4); \ - cfi_restore (REG) - -#define RETURN popl %esi; CFI_POP (esi); ret - - .text -ENTRY (__strlen_sse2) -/* - * This implementation uses SSE instructions to compare up to 16 bytes - * at a time looking for the end of string (null char). - */ - pushl %esi - cfi_adjust_cfa_offset (4) - cfi_rel_offset (%esi, 0) - mov 8(%esp), %eax - mov %eax, %ecx - pxor %xmm0, %xmm0 /* 16 null chars */ - mov %eax, %esi - and $15, %ecx - jz 1f /* string is 16 byte aligned */ - - /* - * Unaligned case. Round down to 16-byte boundary before comparing - * 16 bytes for a null char. The code then compensates for any extra chars - * preceding the start of the string. - */ - and $-16, %esi - - pcmpeqb (%esi), %xmm0 - lea 16(%eax), %esi - pmovmskb %xmm0, %edx - - shr %cl, %edx /* Compensate for bytes preceding the string */ - test %edx, %edx - jnz 2f - sub %ecx, %esi /* no null, adjust to next 16-byte boundary */ - pxor %xmm0, %xmm0 /* clear xmm0, may have been changed... */ - - .p2align 4 -1: /* 16 byte aligned */ - pcmpeqb (%esi), %xmm0 /* look for null bytes */ - pmovmskb %xmm0, %edx /* move each byte mask of %xmm0 to edx */ - - add $16, %esi /* prepare to search next 16 bytes */ - test %edx, %edx /* if no null byte, %edx must be 0 */ - jnz 2f /* found a null */ - - pcmpeqb (%esi), %xmm0 - pmovmskb %xmm0, %edx - add $16, %esi - test %edx, %edx - jnz 2f - - pcmpeqb (%esi), %xmm0 - pmovmskb %xmm0, %edx - add $16, %esi - test %edx, %edx - jnz 2f - - pcmpeqb (%esi), %xmm0 - pmovmskb %xmm0, %edx - add $16, %esi - test %edx, %edx - jz 1b - -2: - neg %eax - lea -16(%eax, %esi), %eax /* calculate exact offset */ - bsf %edx, %ecx /* Least significant 1 bit is index of null */ - add %ecx, %eax - popl %esi - cfi_adjust_cfa_offset (-4) - cfi_restore (%esi) - ret - -END (__strlen_sse2) - # undef ENTRY # define ENTRY(name) \ .type __strlen_ia32, @function; \ |