diff options
Diffstat (limited to 'sysdeps/i386/i686/multiarch/strlen.S')
| -rw-r--r-- | sysdeps/i386/i686/multiarch/strlen.S | 154 |
1 files changed, 154 insertions, 0 deletions
diff --git a/sysdeps/i386/i686/multiarch/strlen.S b/sysdeps/i386/i686/multiarch/strlen.S new file mode 100644 index 0000000000..0c1e8646ff --- /dev/null +++ b/sysdeps/i386/i686/multiarch/strlen.S @@ -0,0 +1,154 @@ +/* Multiple versions of strlen + Copyright (C) 2009 Free Software Foundation, Inc. + Contributed by Intel Corporation. + 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 <sysdep.h> +#include <ifunc-defines.h> + +/* 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 + .section .gnu.linkonce.t.__i686.get_pc_thunk.bx,"ax",@progbits + .globl __i686.get_pc_thunk.bx + .hidden __i686.get_pc_thunk.bx + .p2align 4 + .type __i686.get_pc_thunk.bx,@function +__i686.get_pc_thunk.bx: + movl (%esp), %ebx + ret + + .text +ENTRY(strlen) + .type strlen, @gnu_indirect_function + pushl %ebx + cfi_adjust_cfa_offset (4) + cfi_rel_offset (ebx, 0) + call __i686.get_pc_thunk.bx + addl $_GLOBAL_OFFSET_TABLE_, %ebx + cmpl $0, KIND_OFFSET+__cpu_features@GOTOFF(%ebx) + jne 1f + call __init_cpu_features +1: leal __strlen_ia32@GOTOFF(%ebx), %eax + testl $(1<<26), CPUID_OFFSET+COMMON_CPUID_INDEX_1*CPUID_SIZE+CPUID_EDX_OFFSET+__cpu_features@GOTOFF(%ebx) + jz 2f + leal __strlen_sse2@GOTOFF(%ebx), %eax +2: popl %ebx + cfi_adjust_cfa_offset (-4); + cfi_restore (ebx) + 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; \ + .globl __strlen_ia32; \ + .p2align 4; \ + __strlen_ia32: cfi_startproc; \ + CALL_MCOUNT +# undef END +# define END(name) \ + cfi_endproc; .size __strlen_ia32, .-__strlen_ia32 +# undef libc_hidden_builtin_def +/* IFUNC doesn't work with the hidden functions in shared library since + they will be called without setting up EBX needed for PLT which is + used by IFUNC. */ +# define libc_hidden_builtin_def(name) \ + .globl __GI_strlen; __GI_strlen = __strlen_ia32 +#endif + +#include "../../i586/strlen.S" |