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https://sourceware.org/git/glibc.git
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4ba6558684
No bug. This commit optimizes strlen-evex.S. The optimizations are mostly small things but they add up to roughly 10-30% performance improvement for strlen. The results for strnlen are bit more ambiguous. test-strlen, test-strnlen, test-wcslen, and test-wcsnlen are all passing. Signed-off-by: Noah Goldstein <goldstein.w.n@gmail.com>
490 lines
11 KiB
ArmAsm
490 lines
11 KiB
ArmAsm
/* strlen/strnlen/wcslen/wcsnlen optimized with 256-bit EVEX instructions.
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Copyright (C) 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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#if IS_IN (libc)
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# include <sysdep.h>
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# ifndef STRLEN
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# define STRLEN __strlen_evex
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# endif
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# define VMOVA vmovdqa64
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# ifdef USE_AS_WCSLEN
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# define VPCMP vpcmpd
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# define VPMINU vpminud
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# define SHIFT_REG ecx
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# define CHAR_SIZE 4
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# else
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# define VPCMP vpcmpb
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# define VPMINU vpminub
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# define SHIFT_REG edx
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# define CHAR_SIZE 1
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# endif
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# define XMMZERO xmm16
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# define YMMZERO ymm16
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# define YMM1 ymm17
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# define YMM2 ymm18
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# define YMM3 ymm19
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# define YMM4 ymm20
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# define YMM5 ymm21
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# define YMM6 ymm22
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# define VEC_SIZE 32
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# define PAGE_SIZE 4096
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# define CHAR_PER_VEC (VEC_SIZE / CHAR_SIZE)
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.section .text.evex,"ax",@progbits
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ENTRY (STRLEN)
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# ifdef USE_AS_STRNLEN
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/* Check zero length. */
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test %RSI_LP, %RSI_LP
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jz L(zero)
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# ifdef __ILP32__
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/* Clear the upper 32 bits. */
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movl %esi, %esi
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# endif
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mov %RSI_LP, %R8_LP
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# endif
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movl %edi, %eax
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vpxorq %XMMZERO, %XMMZERO, %XMMZERO
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/* Clear high bits from edi. Only keeping bits relevant to page
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cross check. */
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andl $(PAGE_SIZE - 1), %eax
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/* Check if we may cross page boundary with one vector load. */
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cmpl $(PAGE_SIZE - VEC_SIZE), %eax
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ja L(cross_page_boundary)
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/* Check the first VEC_SIZE bytes. Each bit in K0 represents a
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null byte. */
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VPCMP $0, (%rdi), %YMMZERO, %k0
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kmovd %k0, %eax
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# ifdef USE_AS_STRNLEN
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/* If length < CHAR_PER_VEC handle special. */
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cmpq $CHAR_PER_VEC, %rsi
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jbe L(first_vec_x0)
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# endif
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testl %eax, %eax
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jz L(aligned_more)
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tzcntl %eax, %eax
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ret
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# ifdef USE_AS_STRNLEN
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L(zero):
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xorl %eax, %eax
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ret
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.p2align 4
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L(first_vec_x0):
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/* Set bit for max len so that tzcnt will return min of max len
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and position of first match. */
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btsq %rsi, %rax
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tzcntl %eax, %eax
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ret
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# endif
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.p2align 4
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L(first_vec_x1):
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tzcntl %eax, %eax
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/* Safe to use 32 bit instructions as these are only called for
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size = [1, 159]. */
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# ifdef USE_AS_STRNLEN
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/* Use ecx which was computed earlier to compute correct value.
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*/
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leal -(CHAR_PER_VEC * 4 + 1)(%rcx, %rax), %eax
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# else
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subl %edx, %edi
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# ifdef USE_AS_WCSLEN
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/* NB: Divide bytes by 4 to get the wchar_t count. */
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sarl $2, %edi
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# endif
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leal CHAR_PER_VEC(%rdi, %rax), %eax
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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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tzcntl %eax, %eax
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/* Safe to use 32 bit instructions as these are only called for
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size = [1, 159]. */
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# ifdef USE_AS_STRNLEN
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/* Use ecx which was computed earlier to compute correct value.
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*/
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leal -(CHAR_PER_VEC * 3 + 1)(%rcx, %rax), %eax
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# else
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subl %edx, %edi
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# ifdef USE_AS_WCSLEN
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/* NB: Divide bytes by 4 to get the wchar_t count. */
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sarl $2, %edi
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# endif
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leal (CHAR_PER_VEC * 2)(%rdi, %rax), %eax
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# endif
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ret
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.p2align 4
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L(first_vec_x3):
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tzcntl %eax, %eax
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/* Safe to use 32 bit instructions as these are only called for
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size = [1, 159]. */
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# ifdef USE_AS_STRNLEN
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/* Use ecx which was computed earlier to compute correct value.
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*/
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leal -(CHAR_PER_VEC * 2 + 1)(%rcx, %rax), %eax
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# else
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subl %edx, %edi
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# ifdef USE_AS_WCSLEN
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/* NB: Divide bytes by 4 to get the wchar_t count. */
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sarl $2, %edi
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# endif
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leal (CHAR_PER_VEC * 3)(%rdi, %rax), %eax
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# endif
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ret
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.p2align 4
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L(first_vec_x4):
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tzcntl %eax, %eax
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/* Safe to use 32 bit instructions as these are only called for
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size = [1, 159]. */
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# ifdef USE_AS_STRNLEN
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/* Use ecx which was computed earlier to compute correct value.
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*/
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leal -(CHAR_PER_VEC + 1)(%rcx, %rax), %eax
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# else
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subl %edx, %edi
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# ifdef USE_AS_WCSLEN
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/* NB: Divide bytes by 4 to get the wchar_t count. */
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sarl $2, %edi
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# endif
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leal (CHAR_PER_VEC * 4)(%rdi, %rax), %eax
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# endif
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ret
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.p2align 5
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L(aligned_more):
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movq %rdi, %rdx
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/* Align data to VEC_SIZE. */
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andq $-(VEC_SIZE), %rdi
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L(cross_page_continue):
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/* Check the first 4 * VEC_SIZE. Only one VEC_SIZE at a time
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since data is only aligned to VEC_SIZE. */
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# ifdef USE_AS_STRNLEN
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/* + CHAR_SIZE because it simplies the logic in
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last_4x_vec_or_less. */
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leaq (VEC_SIZE * 5 + CHAR_SIZE)(%rdi), %rcx
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subq %rdx, %rcx
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# ifdef USE_AS_WCSLEN
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/* NB: Divide bytes by 4 to get the wchar_t count. */
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sarl $2, %ecx
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# endif
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# endif
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/* Load first VEC regardless. */
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VPCMP $0, VEC_SIZE(%rdi), %YMMZERO, %k0
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# ifdef USE_AS_STRNLEN
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/* Adjust length. If near end handle specially. */
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subq %rcx, %rsi
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jb L(last_4x_vec_or_less)
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# endif
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kmovd %k0, %eax
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testl %eax, %eax
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jnz L(first_vec_x1)
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VPCMP $0, (VEC_SIZE * 2)(%rdi), %YMMZERO, %k0
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kmovd %k0, %eax
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test %eax, %eax
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jnz L(first_vec_x2)
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VPCMP $0, (VEC_SIZE * 3)(%rdi), %YMMZERO, %k0
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kmovd %k0, %eax
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testl %eax, %eax
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jnz L(first_vec_x3)
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VPCMP $0, (VEC_SIZE * 4)(%rdi), %YMMZERO, %k0
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kmovd %k0, %eax
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testl %eax, %eax
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jnz L(first_vec_x4)
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addq $VEC_SIZE, %rdi
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# ifdef USE_AS_STRNLEN
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/* Check if at last VEC_SIZE * 4 length. */
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cmpq $(CHAR_PER_VEC * 4 - 1), %rsi
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jbe L(last_4x_vec_or_less_load)
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movl %edi, %ecx
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andl $(VEC_SIZE * 4 - 1), %ecx
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# ifdef USE_AS_WCSLEN
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/* NB: Divide bytes by 4 to get the wchar_t count. */
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sarl $2, %ecx
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# endif
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/* Readjust length. */
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addq %rcx, %rsi
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# endif
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/* Align data to VEC_SIZE * 4. */
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andq $-(VEC_SIZE * 4), %rdi
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/* Compare 4 * VEC at a time forward. */
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.p2align 4
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L(loop_4x_vec):
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/* Load first VEC regardless. */
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VMOVA (VEC_SIZE * 4)(%rdi), %YMM1
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# ifdef USE_AS_STRNLEN
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/* Break if at end of length. */
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subq $(CHAR_PER_VEC * 4), %rsi
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jb L(last_4x_vec_or_less_cmpeq)
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# endif
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/* Save some code size by microfusing VPMINU with the load. Since
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the matches in ymm2/ymm4 can only be returned if there where no
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matches in ymm1/ymm3 respectively there is no issue with overlap.
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*/
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VPMINU (VEC_SIZE * 5)(%rdi), %YMM1, %YMM2
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VMOVA (VEC_SIZE * 6)(%rdi), %YMM3
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VPMINU (VEC_SIZE * 7)(%rdi), %YMM3, %YMM4
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VPCMP $0, %YMM2, %YMMZERO, %k0
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VPCMP $0, %YMM4, %YMMZERO, %k1
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subq $-(VEC_SIZE * 4), %rdi
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kortestd %k0, %k1
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jz L(loop_4x_vec)
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/* Check if end was in first half. */
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kmovd %k0, %eax
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subq %rdx, %rdi
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# ifdef USE_AS_WCSLEN
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shrq $2, %rdi
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# endif
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testl %eax, %eax
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jz L(second_vec_return)
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VPCMP $0, %YMM1, %YMMZERO, %k2
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kmovd %k2, %edx
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/* Combine VEC1 matches (edx) with VEC2 matches (eax). */
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# ifdef USE_AS_WCSLEN
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sall $CHAR_PER_VEC, %eax
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orl %edx, %eax
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tzcntl %eax, %eax
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# else
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salq $CHAR_PER_VEC, %rax
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orq %rdx, %rax
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tzcntq %rax, %rax
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# endif
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addq %rdi, %rax
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ret
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# ifdef USE_AS_STRNLEN
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L(last_4x_vec_or_less_load):
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/* Depending on entry adjust rdi / prepare first VEC in YMM1. */
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VMOVA (VEC_SIZE * 4)(%rdi), %YMM1
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L(last_4x_vec_or_less_cmpeq):
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VPCMP $0, %YMM1, %YMMZERO, %k0
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addq $(VEC_SIZE * 3), %rdi
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L(last_4x_vec_or_less):
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kmovd %k0, %eax
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/* If remaining length > VEC_SIZE * 2. This works if esi is off by
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VEC_SIZE * 4. */
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testl $(CHAR_PER_VEC * 2), %esi
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jnz L(last_4x_vec)
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/* length may have been negative or positive by an offset of
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CHAR_PER_VEC * 4 depending on where this was called from. This
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fixes that. */
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andl $(CHAR_PER_VEC * 4 - 1), %esi
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testl %eax, %eax
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jnz L(last_vec_x1_check)
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/* Check the end of data. */
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subl $CHAR_PER_VEC, %esi
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jb L(max)
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VPCMP $0, (VEC_SIZE * 2)(%rdi), %YMMZERO, %k0
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kmovd %k0, %eax
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tzcntl %eax, %eax
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/* Check the end of data. */
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cmpl %eax, %esi
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jb L(max)
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subq %rdx, %rdi
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# ifdef USE_AS_WCSLEN
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/* NB: Divide bytes by 4 to get the wchar_t count. */
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sarq $2, %rdi
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# endif
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leaq (CHAR_PER_VEC * 2)(%rdi, %rax), %rax
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ret
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L(max):
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movq %r8, %rax
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ret
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# endif
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/* Placed here in strnlen so that the jcc L(last_4x_vec_or_less)
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in the 4x VEC loop can use 2 byte encoding. */
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.p2align 4
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L(second_vec_return):
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VPCMP $0, %YMM3, %YMMZERO, %k0
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/* Combine YMM3 matches (k0) with YMM4 matches (k1). */
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# ifdef USE_AS_WCSLEN
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kunpckbw %k0, %k1, %k0
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kmovd %k0, %eax
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tzcntl %eax, %eax
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# else
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kunpckdq %k0, %k1, %k0
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kmovq %k0, %rax
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tzcntq %rax, %rax
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# endif
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leaq (CHAR_PER_VEC * 2)(%rdi, %rax), %rax
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ret
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# ifdef USE_AS_STRNLEN
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L(last_vec_x1_check):
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tzcntl %eax, %eax
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/* Check the end of data. */
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cmpl %eax, %esi
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jb L(max)
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subq %rdx, %rdi
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# ifdef USE_AS_WCSLEN
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/* NB: Divide bytes by 4 to get the wchar_t count. */
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sarq $2, %rdi
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# endif
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leaq (CHAR_PER_VEC)(%rdi, %rax), %rax
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ret
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.p2align 4
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L(last_4x_vec):
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/* Test first 2x VEC normally. */
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testl %eax, %eax
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jnz L(last_vec_x1)
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VPCMP $0, (VEC_SIZE * 2)(%rdi), %YMMZERO, %k0
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kmovd %k0, %eax
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testl %eax, %eax
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jnz L(last_vec_x2)
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/* Normalize length. */
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andl $(CHAR_PER_VEC * 4 - 1), %esi
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VPCMP $0, (VEC_SIZE * 3)(%rdi), %YMMZERO, %k0
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kmovd %k0, %eax
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testl %eax, %eax
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jnz L(last_vec_x3)
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/* Check the end of data. */
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subl $(CHAR_PER_VEC * 3), %esi
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jb L(max)
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VPCMP $0, (VEC_SIZE * 4)(%rdi), %YMMZERO, %k0
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kmovd %k0, %eax
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tzcntl %eax, %eax
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/* Check the end of data. */
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cmpl %eax, %esi
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jb L(max_end)
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subq %rdx, %rdi
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# ifdef USE_AS_WCSLEN
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/* NB: Divide bytes by 4 to get the wchar_t count. */
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sarq $2, %rdi
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# endif
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leaq (CHAR_PER_VEC * 4)(%rdi, %rax), %rax
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ret
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.p2align 4
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L(last_vec_x1):
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tzcntl %eax, %eax
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subq %rdx, %rdi
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# ifdef USE_AS_WCSLEN
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/* NB: Divide bytes by 4 to get the wchar_t count. */
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sarq $2, %rdi
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# endif
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leaq (CHAR_PER_VEC)(%rdi, %rax), %rax
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ret
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.p2align 4
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L(last_vec_x2):
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tzcntl %eax, %eax
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subq %rdx, %rdi
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# ifdef USE_AS_WCSLEN
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/* NB: Divide bytes by 4 to get the wchar_t count. */
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sarq $2, %rdi
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# endif
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leaq (CHAR_PER_VEC * 2)(%rdi, %rax), %rax
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ret
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.p2align 4
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L(last_vec_x3):
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tzcntl %eax, %eax
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subl $(CHAR_PER_VEC * 2), %esi
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/* Check the end of data. */
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cmpl %eax, %esi
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jb L(max_end)
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subq %rdx, %rdi
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# ifdef USE_AS_WCSLEN
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/* NB: Divide bytes by 4 to get the wchar_t count. */
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sarq $2, %rdi
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# endif
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leaq (CHAR_PER_VEC * 3)(%rdi, %rax), %rax
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ret
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L(max_end):
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movq %r8, %rax
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ret
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# endif
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/* Cold case for crossing page with first load. */
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.p2align 4
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L(cross_page_boundary):
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movq %rdi, %rdx
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/* Align data to VEC_SIZE. */
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andq $-VEC_SIZE, %rdi
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VPCMP $0, (%rdi), %YMMZERO, %k0
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kmovd %k0, %eax
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/* Remove the leading bytes. */
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# ifdef USE_AS_WCSLEN
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/* NB: Divide shift count by 4 since each bit in K0 represent 4
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bytes. */
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movl %edx, %ecx
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shrl $2, %ecx
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andl $(CHAR_PER_VEC - 1), %ecx
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# endif
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/* SHIFT_REG is ecx for USE_AS_WCSLEN and edx otherwise. */
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sarxl %SHIFT_REG, %eax, %eax
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testl %eax, %eax
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# ifndef USE_AS_STRNLEN
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jz L(cross_page_continue)
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tzcntl %eax, %eax
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ret
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# else
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jnz L(cross_page_less_vec)
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# ifndef USE_AS_WCSLEN
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movl %edx, %ecx
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andl $(CHAR_PER_VEC - 1), %ecx
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# endif
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movl $CHAR_PER_VEC, %eax
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subl %ecx, %eax
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/* Check the end of data. */
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cmpq %rax, %rsi
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ja L(cross_page_continue)
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movl %esi, %eax
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ret
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|
L(cross_page_less_vec):
|
|
tzcntl %eax, %eax
|
|
/* Select min of length and position of first null. */
|
|
cmpq %rax, %rsi
|
|
cmovb %esi, %eax
|
|
ret
|
|
# endif
|
|
|
|
END (STRLEN)
|
|
#endif
|