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c25eb94aed
commit b412213eee
Author: Noah Goldstein <goldstein.w.n@gmail.com>
Date: Tue Oct 18 17:44:07 2022 -0700
x86: Optimize strrchr-evex.S and implement with VMM headers
Added `vpcompress{b|d}` to the page-cross logic with is an
AVX512-VBMI2 instruction. This is not supported on SKX. Since the
page-cross logic is relatively cold and the benefit is minimal
revert the page-cross case back to the old logic which is supported
on SKX.
Tested on x86-64.
395 lines
9.4 KiB
ArmAsm
395 lines
9.4 KiB
ArmAsm
/* strrchr/wcsrchr optimized with 256-bit EVEX instructions.
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Copyright (C) 2021-2022 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 <isa-level.h>
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#if ISA_SHOULD_BUILD (4)
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# include <sysdep.h>
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# ifndef STRRCHR
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# define STRRCHR __strrchr_evex
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# endif
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# include "x86-evex256-vecs.h"
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# ifdef USE_AS_WCSRCHR
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# define SHIFT_REG rsi
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# define kunpck_2x kunpckbw
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# define kmov_2x kmovd
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# define maskz_2x ecx
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# define maskm_2x eax
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# define CHAR_SIZE 4
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# define VPMIN vpminud
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# define VPTESTN vptestnmd
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# define VPTEST vptestmd
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# define VPBROADCAST vpbroadcastd
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# define VPCMPEQ vpcmpeqd
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# define VPCMP vpcmpd
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# define USE_WIDE_CHAR
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# else
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# define SHIFT_REG rdi
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# define kunpck_2x kunpckdq
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# define kmov_2x kmovq
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# define maskz_2x rcx
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# define maskm_2x rax
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# define CHAR_SIZE 1
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# define VPMIN vpminub
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# define VPTESTN vptestnmb
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# define VPTEST vptestmb
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# define VPBROADCAST vpbroadcastb
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# define VPCMPEQ vpcmpeqb
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# define VPCMP vpcmpb
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# endif
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# include "reg-macros.h"
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# define VMATCH VMM(0)
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# define CHAR_PER_VEC (VEC_SIZE / CHAR_SIZE)
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# define PAGE_SIZE 4096
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.section SECTION(.text), "ax", @progbits
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ENTRY_P2ALIGN(STRRCHR, 6)
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movl %edi, %eax
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/* Broadcast CHAR to VMATCH. */
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VPBROADCAST %esi, %VMATCH
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andl $(PAGE_SIZE - 1), %eax
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cmpl $(PAGE_SIZE - VEC_SIZE), %eax
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jg L(cross_page_boundary)
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L(page_cross_continue):
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VMOVU (%rdi), %VMM(1)
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/* k0 has a 1 for each zero CHAR in VEC(1). */
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VPTESTN %VMM(1), %VMM(1), %k0
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KMOV %k0, %VRSI
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test %VRSI, %VRSI
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jz L(aligned_more)
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/* fallthrough: zero CHAR in first VEC. */
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/* K1 has a 1 for each search CHAR match in VEC(1). */
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VPCMPEQ %VMATCH, %VMM(1), %k1
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KMOV %k1, %VRAX
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/* Build mask up until first zero CHAR (used to mask of
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potential search CHAR matches past the end of the string).
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*/
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blsmsk %VRSI, %VRSI
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and %VRSI, %VRAX
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jz L(ret0)
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/* Get last match (the `and` removed any out of bounds matches).
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*/
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bsr %VRAX, %VRAX
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# ifdef USE_AS_WCSRCHR
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leaq (%rdi, %rax, CHAR_SIZE), %rax
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# else
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addq %rdi, %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/x3 have hard coded backward
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search path for earlier matches. */
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.p2align 4,, 6
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L(first_vec_x1):
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VPCMPEQ %VMATCH, %VMM(2), %k1
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KMOV %k1, %VRAX
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blsmsk %VRCX, %VRCX
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/* eax non-zero if search CHAR in range. */
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and %VRCX, %VRAX
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jnz L(first_vec_x1_return)
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/* fallthrough: no match in VEC(2) then need to check for
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earlier matches (in VEC(1)). */
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.p2align 4,, 4
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L(first_vec_x0_test):
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VPCMPEQ %VMATCH, %VMM(1), %k1
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KMOV %k1, %VRAX
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test %VRAX, %VRAX
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jz L(ret1)
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bsr %VRAX, %VRAX
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# ifdef USE_AS_WCSRCHR
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leaq (%rsi, %rax, CHAR_SIZE), %rax
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# else
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addq %rsi, %rax
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# endif
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L(ret1):
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ret
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.p2align 4,, 10
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L(first_vec_x1_or_x2):
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VPCMPEQ %VMM(3), %VMATCH, %k3
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VPCMPEQ %VMM(2), %VMATCH, %k2
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/* K2 and K3 have 1 for any search CHAR match. Test if any
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matches between either of them. Otherwise check VEC(1). */
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KORTEST %k2, %k3
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jz L(first_vec_x0_test)
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/* Guranteed that VEC(2) and VEC(3) are within range so merge
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the two bitmasks then get last result. */
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kunpck_2x %k2, %k3, %k3
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kmov_2x %k3, %maskm_2x
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bsr %maskm_2x, %maskm_2x
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leaq (VEC_SIZE * 1)(%r8, %rax, CHAR_SIZE), %rax
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ret
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.p2align 4,, 7
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L(first_vec_x3):
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VPCMPEQ %VMATCH, %VMM(4), %k1
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KMOV %k1, %VRAX
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blsmsk %VRCX, %VRCX
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/* If no search CHAR match in range check VEC(1)/VEC(2)/VEC(3).
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*/
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and %VRCX, %VRAX
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jz L(first_vec_x1_or_x2)
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bsr %VRAX, %VRAX
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leaq (VEC_SIZE * 3)(%rdi, %rax, CHAR_SIZE), %rax
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ret
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.p2align 4,, 6
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L(first_vec_x0_x1_test):
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VPCMPEQ %VMATCH, %VMM(2), %k1
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KMOV %k1, %VRAX
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/* Check VEC(2) for last match first. If no match try VEC(1).
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*/
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test %VRAX, %VRAX
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jz L(first_vec_x0_test)
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.p2align 4,, 4
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L(first_vec_x1_return):
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bsr %VRAX, %VRAX
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leaq (VEC_SIZE)(%rdi, %rax, CHAR_SIZE), %rax
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ret
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.p2align 4,, 10
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L(first_vec_x2):
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VPCMPEQ %VMATCH, %VMM(3), %k1
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KMOV %k1, %VRAX
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blsmsk %VRCX, %VRCX
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/* Check VEC(3) for last match first. If no match try
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VEC(2)/VEC(1). */
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and %VRCX, %VRAX
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jz L(first_vec_x0_x1_test)
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bsr %VRAX, %VRAX
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leaq (VEC_SIZE * 2)(%rdi, %rax, CHAR_SIZE), %rax
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ret
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.p2align 4,, 12
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L(aligned_more):
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/* Need to keep original pointer incase VEC(1) has last match.
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*/
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movq %rdi, %rsi
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andq $-VEC_SIZE, %rdi
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VMOVU VEC_SIZE(%rdi), %VMM(2)
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VPTESTN %VMM(2), %VMM(2), %k0
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KMOV %k0, %VRCX
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test %VRCX, %VRCX
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jnz L(first_vec_x1)
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VMOVU (VEC_SIZE * 2)(%rdi), %VMM(3)
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VPTESTN %VMM(3), %VMM(3), %k0
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KMOV %k0, %VRCX
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test %VRCX, %VRCX
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jnz L(first_vec_x2)
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VMOVU (VEC_SIZE * 3)(%rdi), %VMM(4)
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VPTESTN %VMM(4), %VMM(4), %k0
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KMOV %k0, %VRCX
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movq %rdi, %r8
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test %VRCX, %VRCX
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jnz L(first_vec_x3)
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andq $-(VEC_SIZE * 2), %rdi
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.p2align 4,, 10
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L(first_aligned_loop):
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/* Preserve VEC(1), VEC(2), VEC(3), and VEC(4) until we can
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gurantee they don't store a match. */
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VMOVA (VEC_SIZE * 4)(%rdi), %VMM(5)
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VMOVA (VEC_SIZE * 5)(%rdi), %VMM(6)
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VPCMPEQ %VMM(5), %VMATCH, %k2
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vpxord %VMM(6), %VMATCH, %VMM(7)
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VPMIN %VMM(5), %VMM(6), %VMM(8)
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VPMIN %VMM(8), %VMM(7), %VMM(7)
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VPTESTN %VMM(7), %VMM(7), %k1
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subq $(VEC_SIZE * -2), %rdi
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KORTEST %k1, %k2
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jz L(first_aligned_loop)
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VPCMPEQ %VMM(6), %VMATCH, %k3
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VPTESTN %VMM(8), %VMM(8), %k1
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/* If k1 is zero, then we found a CHAR match but no null-term.
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We can now safely throw out VEC1-4. */
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KTEST %k1, %k1
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jz L(second_aligned_loop_prep)
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KORTEST %k2, %k3
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jnz L(return_first_aligned_loop)
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.p2align 4,, 6
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L(first_vec_x1_or_x2_or_x3):
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VPCMPEQ %VMM(4), %VMATCH, %k4
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KMOV %k4, %VRAX
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bsr %VRAX, %VRAX
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jz L(first_vec_x1_or_x2)
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leaq (VEC_SIZE * 3)(%r8, %rax, CHAR_SIZE), %rax
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ret
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.p2align 4,, 8
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L(return_first_aligned_loop):
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VPTESTN %VMM(5), %VMM(5), %k0
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/* Combined results from VEC5/6. */
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kunpck_2x %k0, %k1, %k0
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kmov_2x %k0, %maskz_2x
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blsmsk %maskz_2x, %maskz_2x
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kunpck_2x %k2, %k3, %k3
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kmov_2x %k3, %maskm_2x
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and %maskz_2x, %maskm_2x
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jz L(first_vec_x1_or_x2_or_x3)
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bsr %maskm_2x, %maskm_2x
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leaq (VEC_SIZE * 2)(%rdi, %rax, CHAR_SIZE), %rax
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ret
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.p2align 4
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/* We can throw away the work done for the first 4x checks here
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as we have a later match. This is the 'fast' path persay.
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*/
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L(second_aligned_loop_prep):
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L(second_aligned_loop_set_furthest_match):
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movq %rdi, %rsi
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/* Ideally we would safe k2/k3 but `kmov/kunpck` take uops on
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port0 and have noticable overhead in the loop. */
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VMOVA %VMM(5), %VMM(7)
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VMOVA %VMM(6), %VMM(8)
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.p2align 4
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L(second_aligned_loop):
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VMOVU (VEC_SIZE * 4)(%rdi), %VMM(5)
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VMOVU (VEC_SIZE * 5)(%rdi), %VMM(6)
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VPCMPEQ %VMM(5), %VMATCH, %k2
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vpxord %VMM(6), %VMATCH, %VMM(3)
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VPMIN %VMM(5), %VMM(6), %VMM(4)
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VPMIN %VMM(3), %VMM(4), %VMM(3)
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VPTESTN %VMM(3), %VMM(3), %k1
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subq $(VEC_SIZE * -2), %rdi
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KORTEST %k1, %k2
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jz L(second_aligned_loop)
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VPCMPEQ %VMM(6), %VMATCH, %k3
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VPTESTN %VMM(4), %VMM(4), %k1
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KTEST %k1, %k1
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jz L(second_aligned_loop_set_furthest_match)
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/* branch here because we know we have a match in VEC7/8 but
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might not in VEC5/6 so the latter is expected to be less
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likely. */
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KORTEST %k2, %k3
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jnz L(return_new_match)
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L(return_old_match):
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VPCMPEQ %VMM(8), %VMATCH, %k0
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KMOV %k0, %VRCX
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bsr %VRCX, %VRCX
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jnz L(return_old_match_ret)
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VPCMPEQ %VMM(7), %VMATCH, %k0
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KMOV %k0, %VRCX
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bsr %VRCX, %VRCX
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subq $VEC_SIZE, %rsi
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L(return_old_match_ret):
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leaq (VEC_SIZE * 3)(%rsi, %rcx, CHAR_SIZE), %rax
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ret
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.p2align 4,, 10
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L(return_new_match):
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VPTESTN %VMM(5), %VMM(5), %k0
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/* Combined results from VEC5/6. */
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kunpck_2x %k0, %k1, %k0
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kmov_2x %k0, %maskz_2x
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blsmsk %maskz_2x, %maskz_2x
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kunpck_2x %k2, %k3, %k3
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kmov_2x %k3, %maskm_2x
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/* Match at end was out-of-bounds so use last known match. */
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and %maskz_2x, %maskm_2x
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jz L(return_old_match)
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bsr %maskm_2x, %maskm_2x
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leaq (VEC_SIZE * 2)(%rdi, %rax, CHAR_SIZE), %rax
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ret
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L(cross_page_boundary):
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/* eax contains all the page offset bits of src (rdi). `xor rdi,
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rax` sets pointer will all page offset bits cleared so
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offset of (PAGE_SIZE - VEC_SIZE) will get last aligned VEC
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before page cross (guranteed to be safe to read). Doing this
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as opposed to `movq %rdi, %rax; andq $-VEC_SIZE, %rax` saves
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a bit of code size. */
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xorq %rdi, %rax
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VMOVU (PAGE_SIZE - VEC_SIZE)(%rax), %VMM(1)
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VPTESTN %VMM(1), %VMM(1), %k0
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KMOV %k0, %VRCX
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/* Shift out zero CHAR matches that are before the begining of
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src (rdi). */
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# ifdef USE_AS_WCSRCHR
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movl %edi, %esi
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andl $(VEC_SIZE - 1), %esi
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shrl $2, %esi
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# endif
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shrx %VGPR(SHIFT_REG), %VRCX, %VRCX
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test %VRCX, %VRCX
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jz L(page_cross_continue)
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/* Found zero CHAR so need to test for search CHAR. */
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VPCMP $0, %VMATCH, %VMM(1), %k1
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KMOV %k1, %VRAX
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/* Shift out search CHAR matches that are before the begining of
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src (rdi). */
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shrx %VGPR(SHIFT_REG), %VRAX, %VRAX
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/* Check if any search CHAR match in range. */
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blsmsk %VRCX, %VRCX
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and %VRCX, %VRAX
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jz L(ret3)
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bsr %VRAX, %VRAX
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# ifdef USE_AS_WCSRCHR
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leaq (%rdi, %rax, CHAR_SIZE), %rax
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# else
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addq %rdi, %rax
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# endif
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L(ret3):
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ret
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END(STRRCHR)
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#endif
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