/* strlen(str) -- determine the length of the string STR. Copyright (C) 2009 Free Software Foundation, Inc. Contributed by Ulrich Drepper . This file is part of the GNU C Library. The GNU C Library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. The GNU C Library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with the GNU C Library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA. */ #include #include /* Define multiple versions only for the definition in libc and for the DSO. In static binaries we need strlen before the initialization happened. */ #if defined SHARED && !defined NOT_IN_libc .text ENTRY(strlen) .type strlen, @gnu_indirect_function cmpl $0, __cpu_features+KIND_OFFSET(%rip) jne 1f call __init_cpu_features 1: leaq __strlen_sse2(%rip), %rax testl $(1<<20), __cpu_features+CPUID_OFFSET+COMMON_CPUID_INDEX_1*CPUID_SIZE+CPUID_ECX_OFFSET(%rip) jz 2f leaq __strlen_sse42(%rip), %rax 2: ret END(strlen) .align 16 .type __strlen_sse42, @function __strlen_sse42: cfi_startproc CALL_MCOUNT pxor %xmm2, %xmm2 movq %rdi, %rcx movq %rdi, %r8 andq $~15, %rdi movdqa %xmm2, %xmm1 pcmpeqb (%rdi), %xmm2 orl $0xffffffff, %esi subq %rdi, %rcx shll %cl, %esi pmovmskb %xmm2, %edx andl %esi, %edx jnz 1f 2: pcmpistri $0x08, 16(%rdi), %xmm1 leaq 16(%rdi), %rdi jnz 2b leaq (%rdi,%rcx), %rax subq %r8, %rax ret 1: subq %r8, %rdi bsfl %edx, %eax addq %rdi, %rax ret cfi_endproc .size __strlen_sse42, .-__strlen_sse42 # undef ENTRY # define ENTRY(name) \ .type __strlen_sse2, @function; \ .align 16; \ __strlen_sse2: cfi_startproc; \ CALL_MCOUNT # undef END # define END(name) \ cfi_endproc; .size __strlen_sse2, .-__strlen_sse2 # undef libc_hidden_builtin_def /* It doesn't make sense to send libc-internal strlen calls through a PLT. The speedup we get from using SSE4.2 instruction is likely eaten away by the indirect call in the PLT. */ # define libc_hidden_builtin_def(name) \ .globl __GI_strlen; __GI_strlen = __strlen_sse2 #endif #include "../strlen.S"