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279 lines
7.0 KiB
ArmAsm
279 lines
7.0 KiB
ArmAsm
/* strrchr with SSE4.2
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Copyright (C) 2009 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, write to the Free
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Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA. */
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#include <sysdep.h>
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#include <ifunc-defines.h>
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/* Define multiple versions only for the definition in libc and for
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the DSO. In static binaries we need strrchr before the initialization
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happened. */
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#if defined SHARED && !defined NOT_IN_libc
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.text
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ENTRY(strrchr)
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.type strrchr, @gnu_indirect_function
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cmpl $0, __cpu_features+KIND_OFFSET(%rip)
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jne 1f
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call __init_cpu_features
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1: leaq __strrchr_sse2(%rip), %rax
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testl $(1<<20), __cpu_features+CPUID_OFFSET+COMMON_CPUID_INDEX_1*CPUID_SIZE+CPUID_ECX_OFFSET(%rip)
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jz 2f
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leaq __strrchr_sse42(%rip), %rax
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2: ret
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END(strrchr)
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/*
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This implementation uses SSE4 instructions to compare up to 16 bytes
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at a time looking for the last occurrence of the character c in the
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string s:
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char *strrchr (const char *s, int c);
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We use 0x4a:
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_SIDD_SBYTE_OPS
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| _SIDD_CMP_EQUAL_EACH
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| _SIDD_MOST_SIGNIFICANT
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on pcmpistri to compare xmm/mem128
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0 1 2 3 4 5 6 7 8 9 A B C D E F
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X X X X X X X X X X X X X X X X
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against xmm
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0 1 2 3 4 5 6 7 8 9 A B C D E F
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C C C C C C C C C C C C C C C C
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to find out if the first 16byte data element has a byte C and the
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last offset. There are 4 cases:
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1. The first 16byte data element has EOS and has the byte C at the
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last offset X.
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2. The first 16byte data element is valid and has the byte C at the
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last offset X.
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3. The first 16byte data element has EOS and doesn't have the byte C.
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4. The first 16byte data element is valid and doesn't have the byte C.
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Here is the table of ECX, CFlag, ZFlag and SFlag for 3 cases:
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case ECX CFlag ZFlag SFlag
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1 X 1 1 0
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2 X 1 0 0
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3 16 0 1 0
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4 16 0 0 0
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We exit from the loop for cases 1 and 3 with jz which branches
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when ZFlag is 1. If CFlag == 1, ECX has the offset X for case 1. */
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.section .text.sse4.2,"ax",@progbits
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.align 16
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.type __strrchr_sse42, @function
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__strrchr_sse42:
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cfi_startproc
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CALL_MCOUNT
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testb %sil, %sil
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je __strend_sse4
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xor %eax,%eax /* RAX has the last occurrence of s. */
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movd %esi, %xmm1
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punpcklbw %xmm1, %xmm1
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movl %edi, %esi
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punpcklbw %xmm1, %xmm1
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andl $15, %esi
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pshufd $0, %xmm1, %xmm1
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movq %rdi, %r8
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je L(loop)
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/* Handle unaligned string using psrldq. */
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leaq L(psrldq_table)(%rip), %rdx
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andq $-16, %r8
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movslq (%rdx,%rsi,4),%r9
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movdqa (%r8), %xmm0
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addq %rdx, %r9
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jmp *%r9
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/* Handle unaligned string with offset 1 using psrldq. */
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.p2align 4
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L(psrldq_1):
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psrldq $1, %xmm0
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.p2align 4
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L(unaligned_pcmpistri):
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pcmpistri $0x4a, %xmm1, %xmm0
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jnc L(unaligned_no_byte)
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leaq (%rdi,%rcx), %rax
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L(unaligned_no_byte):
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/* Find the length of the unaligned string. */
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pcmpistri $0x3a, %xmm0, %xmm0
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movl $16, %edx
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subl %esi, %edx
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cmpl %ecx, %edx
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/* Return RAX if the unaligned fragment to next 16B already
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contain the NULL terminator. */
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jg L(exit)
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addq $16, %r8
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/* Loop start on aligned string. */
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.p2align 4
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L(loop):
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pcmpistri $0x4a, (%r8), %xmm1
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jbe L(match_or_eos)
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addq $16, %r8
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jmp L(loop)
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.p2align 4
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L(match_or_eos):
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je L(had_eos)
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L(match_no_eos):
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leaq (%r8,%rcx), %rax
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addq $16, %r8
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jmp L(loop)
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.p2align 4
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L(had_eos):
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jnc L(exit)
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leaq (%r8,%rcx), %rax
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.p2align 4
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L(exit):
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ret
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/* Handle unaligned string with offset 15 using psrldq. */
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.p2align 4
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L(psrldq_15):
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psrldq $15, %xmm0
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jmp L(unaligned_pcmpistri)
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/* Handle unaligned string with offset 14 using psrldq. */
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.p2align 4
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L(psrldq_14):
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psrldq $14, %xmm0
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jmp L(unaligned_pcmpistri)
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/* Handle unaligned string with offset 13 using psrldq. */
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.p2align 4
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L(psrldq_13):
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psrldq $13, %xmm0
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jmp L(unaligned_pcmpistri)
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/* Handle unaligned string with offset 12 using psrldq. */
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.p2align 4
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L(psrldq_12):
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psrldq $12, %xmm0
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jmp L(unaligned_pcmpistri)
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/* Handle unaligned string with offset 11 using psrldq. */
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.p2align 4
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L(psrldq_11):
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psrldq $11, %xmm0
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jmp L(unaligned_pcmpistri)
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/* Handle unaligned string with offset 10 using psrldq. */
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.p2align 4
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L(psrldq_10):
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psrldq $10, %xmm0
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jmp L(unaligned_pcmpistri)
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/* Handle unaligned string with offset 9 using psrldq. */
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.p2align 4
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L(psrldq_9):
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psrldq $9, %xmm0
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jmp L(unaligned_pcmpistri)
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/* Handle unaligned string with offset 8 using psrldq. */
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.p2align 4
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L(psrldq_8):
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psrldq $8, %xmm0
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jmp L(unaligned_pcmpistri)
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/* Handle unaligned string with offset 7 using psrldq. */
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.p2align 4
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L(psrldq_7):
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psrldq $7, %xmm0
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jmp L(unaligned_pcmpistri)
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/* Handle unaligned string with offset 6 using psrldq. */
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.p2align 4
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L(psrldq_6):
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psrldq $6, %xmm0
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jmp L(unaligned_pcmpistri)
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/* Handle unaligned string with offset 5 using psrldq. */
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.p2align 4
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L(psrldq_5):
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psrldq $5, %xmm0
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jmp L(unaligned_pcmpistri)
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/* Handle unaligned string with offset 4 using psrldq. */
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.p2align 4
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L(psrldq_4):
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psrldq $4, %xmm0
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jmp L(unaligned_pcmpistri)
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/* Handle unaligned string with offset 3 using psrldq. */
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.p2align 4
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L(psrldq_3):
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psrldq $3, %xmm0
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jmp L(unaligned_pcmpistri)
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/* Handle unaligned string with offset 2 using psrldq. */
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.p2align 4
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L(psrldq_2):
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psrldq $2, %xmm0
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jmp L(unaligned_pcmpistri)
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cfi_endproc
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.size __strrchr_sse42, .-__strrchr_sse42
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.section .rodata.sse4.2,"a",@progbits
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.p2align 4
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L(psrldq_table):
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.int L(loop) - L(psrldq_table)
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.int L(psrldq_1) - L(psrldq_table)
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.int L(psrldq_2) - L(psrldq_table)
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.int L(psrldq_3) - L(psrldq_table)
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.int L(psrldq_4) - L(psrldq_table)
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.int L(psrldq_5) - L(psrldq_table)
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.int L(psrldq_6) - L(psrldq_table)
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.int L(psrldq_7) - L(psrldq_table)
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.int L(psrldq_8) - L(psrldq_table)
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.int L(psrldq_9) - L(psrldq_table)
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.int L(psrldq_10) - L(psrldq_table)
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.int L(psrldq_11) - L(psrldq_table)
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.int L(psrldq_12) - L(psrldq_table)
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.int L(psrldq_13) - L(psrldq_table)
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.int L(psrldq_14) - L(psrldq_table)
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.int L(psrldq_15) - L(psrldq_table)
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# undef ENTRY
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# define ENTRY(name) \
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.type __strrchr_sse2, @function; \
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.align 16; \
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__strrchr_sse2: cfi_startproc; \
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CALL_MCOUNT
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# undef END
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# define END(name) \
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cfi_endproc; .size __strrchr_sse2, .-__strrchr_sse2
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# undef libc_hidden_builtin_def
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/* It doesn't make sense to send libc-internal strrchr calls through a PLT.
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The speedup we get from using SSE4.2 instruction is likely eaten away
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by the indirect call in the PLT. */
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# define libc_hidden_builtin_def(name) \
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.globl __GI_strrchr; __GI_strrchr = __strrchr_sse2
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#endif
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#include "../strrchr.S"
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