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0a11305416
The new code unrolls the main loop slightly without adding too much
overhead and minimizes the comparisons for the search CHAR.
Geometric Mean of all benchmarks New / Old: 0.741
See email for all results.
Full xcheck passes on x86_64 with and without multiarch enabled.
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
(cherry picked from commit 5307aa9c18)
379 lines
8.0 KiB
ArmAsm
379 lines
8.0 KiB
ArmAsm
/* strrchr (str, ch) -- Return pointer to last occurrence of CH in STR.
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Copyright (C) 2013-2021 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, see
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<https://www.gnu.org/licenses/>. */
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#include <sysdep.h>
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#ifndef STRRCHR
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# define STRRCHR strrchr
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#endif
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#ifdef USE_AS_WCSRCHR
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# define PCMPEQ pcmpeqd
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# define CHAR_SIZE 4
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# define PMINU pminud
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#else
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# define PCMPEQ pcmpeqb
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# define CHAR_SIZE 1
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# define PMINU pminub
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#endif
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#define PAGE_SIZE 4096
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#define VEC_SIZE 16
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.text
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ENTRY(STRRCHR)
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movd %esi, %xmm0
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movq %rdi, %rax
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andl $(PAGE_SIZE - 1), %eax
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#ifndef USE_AS_WCSRCHR
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punpcklbw %xmm0, %xmm0
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punpcklwd %xmm0, %xmm0
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#endif
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pshufd $0, %xmm0, %xmm0
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cmpl $(PAGE_SIZE - VEC_SIZE), %eax
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ja L(cross_page)
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L(cross_page_continue):
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movups (%rdi), %xmm1
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pxor %xmm2, %xmm2
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PCMPEQ %xmm1, %xmm2
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pmovmskb %xmm2, %ecx
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testl %ecx, %ecx
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jz L(aligned_more)
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PCMPEQ %xmm0, %xmm1
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pmovmskb %xmm1, %eax
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leal -1(%rcx), %edx
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xorl %edx, %ecx
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andl %ecx, %eax
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jz L(ret0)
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bsrl %eax, %eax
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addq %rdi, %rax
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/* We are off by 3 for wcsrchr if search CHAR is non-zero. If
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search CHAR is zero we are correct. Either way `andq
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-CHAR_SIZE, %rax` gets the correct result. */
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#ifdef USE_AS_WCSRCHR
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andq $-CHAR_SIZE, %rax
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#endif
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L(ret0):
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ret
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/* Returns for first vec x1/x2 have hard coded backward search
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path for earlier matches. */
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.p2align 4
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L(first_vec_x0_test):
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PCMPEQ %xmm0, %xmm1
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pmovmskb %xmm1, %eax
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testl %eax, %eax
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jz L(ret0)
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bsrl %eax, %eax
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addq %r8, %rax
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#ifdef USE_AS_WCSRCHR
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andq $-CHAR_SIZE, %rax
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#endif
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ret
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.p2align 4
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L(first_vec_x1):
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PCMPEQ %xmm0, %xmm2
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pmovmskb %xmm2, %eax
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leal -1(%rcx), %edx
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xorl %edx, %ecx
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andl %ecx, %eax
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jz L(first_vec_x0_test)
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bsrl %eax, %eax
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leaq (VEC_SIZE)(%rdi, %rax), %rax
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#ifdef USE_AS_WCSRCHR
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andq $-CHAR_SIZE, %rax
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#endif
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ret
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.p2align 4
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L(first_vec_x1_test):
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PCMPEQ %xmm0, %xmm2
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pmovmskb %xmm2, %eax
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testl %eax, %eax
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jz L(first_vec_x0_test)
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bsrl %eax, %eax
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leaq (VEC_SIZE)(%rdi, %rax), %rax
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#ifdef USE_AS_WCSRCHR
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andq $-CHAR_SIZE, %rax
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#endif
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ret
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.p2align 4
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L(first_vec_x2):
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PCMPEQ %xmm0, %xmm3
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pmovmskb %xmm3, %eax
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leal -1(%rcx), %edx
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xorl %edx, %ecx
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andl %ecx, %eax
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jz L(first_vec_x1_test)
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bsrl %eax, %eax
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leaq (VEC_SIZE * 2)(%rdi, %rax), %rax
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#ifdef USE_AS_WCSRCHR
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andq $-CHAR_SIZE, %rax
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#endif
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ret
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.p2align 4
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L(aligned_more):
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/* Save original pointer if match was in VEC 0. */
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movq %rdi, %r8
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andq $-VEC_SIZE, %rdi
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movaps VEC_SIZE(%rdi), %xmm2
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pxor %xmm3, %xmm3
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PCMPEQ %xmm2, %xmm3
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pmovmskb %xmm3, %ecx
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testl %ecx, %ecx
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jnz L(first_vec_x1)
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movaps (VEC_SIZE * 2)(%rdi), %xmm3
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pxor %xmm4, %xmm4
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PCMPEQ %xmm3, %xmm4
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pmovmskb %xmm4, %ecx
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testl %ecx, %ecx
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jnz L(first_vec_x2)
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addq $VEC_SIZE, %rdi
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/* Save pointer again before realigning. */
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movq %rdi, %rsi
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andq $-(VEC_SIZE * 2), %rdi
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.p2align 4
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L(first_loop):
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/* Do 2x VEC at a time. */
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movaps (VEC_SIZE * 2)(%rdi), %xmm4
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movaps (VEC_SIZE * 3)(%rdi), %xmm5
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/* Since SSE2 no pminud so wcsrchr needs seperate logic for
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detecting zero. Note if this is found to be a bottleneck it
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may be worth adding an SSE4.1 wcsrchr implementation. */
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#ifdef USE_AS_WCSRCHR
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movaps %xmm5, %xmm6
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pxor %xmm8, %xmm8
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PCMPEQ %xmm8, %xmm5
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PCMPEQ %xmm4, %xmm8
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por %xmm5, %xmm8
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#else
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movaps %xmm5, %xmm6
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PMINU %xmm4, %xmm5
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#endif
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movaps %xmm4, %xmm9
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PCMPEQ %xmm0, %xmm4
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PCMPEQ %xmm0, %xmm6
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movaps %xmm6, %xmm7
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por %xmm4, %xmm6
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#ifndef USE_AS_WCSRCHR
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pxor %xmm8, %xmm8
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PCMPEQ %xmm5, %xmm8
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#endif
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pmovmskb %xmm8, %ecx
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pmovmskb %xmm6, %eax
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addq $(VEC_SIZE * 2), %rdi
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/* Use `addl` 1) so we can undo it with `subl` and 2) it can
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macro-fuse with `jz`. */
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addl %ecx, %eax
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jz L(first_loop)
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/* Check if there is zero match. */
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testl %ecx, %ecx
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jz L(second_loop_match)
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/* Check if there was a match in last iteration. */
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subl %ecx, %eax
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jnz L(new_match)
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L(first_loop_old_match):
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PCMPEQ %xmm0, %xmm2
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PCMPEQ %xmm0, %xmm3
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pmovmskb %xmm2, %ecx
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pmovmskb %xmm3, %eax
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addl %eax, %ecx
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jz L(first_vec_x0_test)
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/* NB: We could move this shift to before the branch and save a
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bit of code size / performance on the fall through. The
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branch leads to the null case which generally seems hotter
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than char in first 3x VEC. */
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sall $16, %eax
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orl %ecx, %eax
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bsrl %eax, %eax
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addq %rsi, %rax
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#ifdef USE_AS_WCSRCHR
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andq $-CHAR_SIZE, %rax
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#endif
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ret
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.p2align 4
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L(new_match):
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pxor %xmm6, %xmm6
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PCMPEQ %xmm9, %xmm6
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pmovmskb %xmm6, %eax
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sall $16, %ecx
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orl %eax, %ecx
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/* We can't reuse either of the old comparisons as since we mask
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of zeros after first zero (instead of using the full
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comparison) we can't gurantee no interference between match
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after end of string and valid match. */
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pmovmskb %xmm4, %eax
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pmovmskb %xmm7, %edx
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sall $16, %edx
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orl %edx, %eax
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leal -1(%ecx), %edx
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xorl %edx, %ecx
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andl %ecx, %eax
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jz L(first_loop_old_match)
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bsrl %eax, %eax
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addq %rdi, %rax
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#ifdef USE_AS_WCSRCHR
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andq $-CHAR_SIZE, %rax
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#endif
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ret
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/* Save minimum state for getting most recent match. We can
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throw out all previous work. */
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.p2align 4
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L(second_loop_match):
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movq %rdi, %rsi
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movaps %xmm4, %xmm2
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movaps %xmm7, %xmm3
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.p2align 4
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L(second_loop):
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movaps (VEC_SIZE * 2)(%rdi), %xmm4
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movaps (VEC_SIZE * 3)(%rdi), %xmm5
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/* Since SSE2 no pminud so wcsrchr needs seperate logic for
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detecting zero. Note if this is found to be a bottleneck it
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may be worth adding an SSE4.1 wcsrchr implementation. */
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#ifdef USE_AS_WCSRCHR
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movaps %xmm5, %xmm6
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pxor %xmm8, %xmm8
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PCMPEQ %xmm8, %xmm5
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PCMPEQ %xmm4, %xmm8
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por %xmm5, %xmm8
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#else
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movaps %xmm5, %xmm6
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PMINU %xmm4, %xmm5
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#endif
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movaps %xmm4, %xmm9
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PCMPEQ %xmm0, %xmm4
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PCMPEQ %xmm0, %xmm6
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movaps %xmm6, %xmm7
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por %xmm4, %xmm6
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#ifndef USE_AS_WCSRCHR
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pxor %xmm8, %xmm8
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PCMPEQ %xmm5, %xmm8
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#endif
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pmovmskb %xmm8, %ecx
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pmovmskb %xmm6, %eax
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addq $(VEC_SIZE * 2), %rdi
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/* Either null term or new occurence of CHAR. */
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addl %ecx, %eax
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jz L(second_loop)
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/* No null term so much be new occurence of CHAR. */
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testl %ecx, %ecx
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jz L(second_loop_match)
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subl %ecx, %eax
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jnz L(second_loop_new_match)
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L(second_loop_old_match):
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pmovmskb %xmm2, %ecx
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pmovmskb %xmm3, %eax
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sall $16, %eax
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orl %ecx, %eax
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bsrl %eax, %eax
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addq %rsi, %rax
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#ifdef USE_AS_WCSRCHR
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andq $-CHAR_SIZE, %rax
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#endif
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ret
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.p2align 4
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L(second_loop_new_match):
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pxor %xmm6, %xmm6
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PCMPEQ %xmm9, %xmm6
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pmovmskb %xmm6, %eax
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sall $16, %ecx
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orl %eax, %ecx
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/* We can't reuse either of the old comparisons as since we mask
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of zeros after first zero (instead of using the full
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comparison) we can't gurantee no interference between match
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after end of string and valid match. */
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pmovmskb %xmm4, %eax
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pmovmskb %xmm7, %edx
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sall $16, %edx
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orl %edx, %eax
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leal -1(%ecx), %edx
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xorl %edx, %ecx
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andl %ecx, %eax
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jz L(second_loop_old_match)
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bsrl %eax, %eax
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addq %rdi, %rax
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#ifdef USE_AS_WCSRCHR
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andq $-CHAR_SIZE, %rax
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#endif
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ret
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.p2align 4,, 4
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L(cross_page):
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movq %rdi, %rsi
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andq $-VEC_SIZE, %rsi
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movaps (%rsi), %xmm1
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pxor %xmm2, %xmm2
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PCMPEQ %xmm1, %xmm2
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pmovmskb %xmm2, %edx
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movl %edi, %ecx
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andl $(VEC_SIZE - 1), %ecx
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sarl %cl, %edx
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jz L(cross_page_continue)
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PCMPEQ %xmm0, %xmm1
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pmovmskb %xmm1, %eax
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sarl %cl, %eax
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leal -1(%rdx), %ecx
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xorl %edx, %ecx
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andl %ecx, %eax
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jz L(ret1)
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bsrl %eax, %eax
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addq %rdi, %rax
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#ifdef USE_AS_WCSRCHR
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andq $-CHAR_SIZE, %rax
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#endif
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L(ret1):
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ret
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END(STRRCHR)
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#ifndef USE_AS_WCSRCHR
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weak_alias (STRRCHR, rindex)
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libc_hidden_builtin_def (STRRCHR)
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#endif
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