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559 lines
14 KiB
559 lines
14 KiB
From c966099cdc3e0fdf92f63eac09b22fa7e5f5f02d Mon Sep 17 00:00:00 2001
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From: Noah Goldstein <goldstein.w.n@gmail.com>
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Date: Thu, 21 Apr 2022 20:52:30 -0500
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Subject: [PATCH] x86: Optimize {str|wcs}rchr-evex
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Content-type: text/plain; charset=UTF-8
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The new code unrolls the main loop slightly without adding too much
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overhead and minimizes the comparisons for the search CHAR.
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Geometric Mean of all benchmarks New / Old: 0.755
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See email for all results.
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Full xcheck passes on x86_64 with and without multiarch enabled.
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Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
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---
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sysdeps/x86_64/multiarch/strrchr-evex.S | 471 +++++++++++++++---------
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1 file changed, 290 insertions(+), 181 deletions(-)
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diff --git a/sysdeps/x86_64/multiarch/strrchr-evex.S b/sysdeps/x86_64/multiarch/strrchr-evex.S
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index f920b5a5..f5b6d755 100644
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--- a/sysdeps/x86_64/multiarch/strrchr-evex.S
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+++ b/sysdeps/x86_64/multiarch/strrchr-evex.S
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@@ -24,242 +24,351 @@
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# define STRRCHR __strrchr_evex
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# endif
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-# define VMOVU vmovdqu64
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-# define VMOVA vmovdqa64
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+# define VMOVU vmovdqu64
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+# define VMOVA vmovdqa64
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# ifdef USE_AS_WCSRCHR
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+# define SHIFT_REG esi
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+
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+# define kunpck 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 VPBROADCAST vpbroadcastd
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-# define VPCMP vpcmpd
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-# define SHIFT_REG r8d
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+# define VPCMP vpcmpd
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# else
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+# define SHIFT_REG edi
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+
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+# define kunpck 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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+
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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 VPBROADCAST vpbroadcastb
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-# define VPCMP vpcmpb
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-# define SHIFT_REG ecx
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+# define VPCMP vpcmpb
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# endif
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# define XMMZERO xmm16
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# define YMMZERO ymm16
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# define YMMMATCH ymm17
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-# define YMM1 ymm18
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+# define YMMSAVE ymm18
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+
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+# define YMM1 ymm19
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+# define YMM2 ymm20
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+# define YMM3 ymm21
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+# define YMM4 ymm22
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+# define YMM5 ymm23
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+# define YMM6 ymm24
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+# define YMM7 ymm25
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+# define YMM8 ymm26
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-# define VEC_SIZE 32
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- .section .text.evex,"ax",@progbits
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-ENTRY (STRRCHR)
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- movl %edi, %ecx
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+# define VEC_SIZE 32
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+# define PAGE_SIZE 4096
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+ .section .text.evex, "ax", @progbits
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+ENTRY(STRRCHR)
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+ movl %edi, %eax
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/* Broadcast CHAR to YMMMATCH. */
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VPBROADCAST %esi, %YMMMATCH
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- vpxorq %XMMZERO, %XMMZERO, %XMMZERO
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-
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- /* Check if we may cross page boundary with one vector load. */
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- andl $(2 * VEC_SIZE - 1), %ecx
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- cmpl $VEC_SIZE, %ecx
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- ja L(cros_page_boundary)
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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), %YMM1
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-
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- /* Each bit in K0 represents a null byte in YMM1. */
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- VPCMP $0, %YMMZERO, %YMM1, %k0
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- /* Each bit in K1 represents a CHAR in YMM1. */
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- VPCMP $0, %YMMMATCH, %YMM1, %k1
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+ /* k0 has a 1 for each zero CHAR in YMM1. */
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+ VPTESTN %YMM1, %YMM1, %k0
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kmovd %k0, %ecx
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- kmovd %k1, %eax
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-
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- addq $VEC_SIZE, %rdi
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-
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- testl %eax, %eax
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- jnz L(first_vec)
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-
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testl %ecx, %ecx
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- jnz L(return_null)
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-
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- andq $-VEC_SIZE, %rdi
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- xorl %edx, %edx
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- jmp L(aligned_loop)
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-
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- .p2align 4
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-L(first_vec):
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- /* Check if there is a null byte. */
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- testl %ecx, %ecx
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- jnz L(char_and_nul_in_first_vec)
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-
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- /* Remember the match and keep searching. */
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- movl %eax, %edx
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- movq %rdi, %rsi
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- andq $-VEC_SIZE, %rdi
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- jmp L(aligned_loop)
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-
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- .p2align 4
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-L(cros_page_boundary):
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- andl $(VEC_SIZE - 1), %ecx
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- andq $-VEC_SIZE, %rdi
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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 YMM1. */
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+ VPCMP $0, %YMMMATCH, %YMM1, %k1
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+ kmovd %k1, %eax
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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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+ blsmskl %ecx, %ecx
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+ andl %ecx, %eax
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+ jz L(ret0)
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+ /* Get last match (the `andl` removed any out of bounds
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+ matches). */
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+ bsrl %eax, %eax
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# ifdef USE_AS_WCSRCHR
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- /* NB: Divide shift count by 4 since each bit in K1 represent 4
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- bytes. */
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- movl %ecx, %SHIFT_REG
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- sarl $2, %SHIFT_REG
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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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- VMOVA (%rdi), %YMM1
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-
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- /* Each bit in K0 represents a null byte in YMM1. */
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- VPCMP $0, %YMMZERO, %YMM1, %k0
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- /* Each bit in K1 represents a CHAR in YMM1. */
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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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+ VPCMP $0, %YMMMATCH, %YMM2, %k1
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+ kmovd %k1, %eax
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+ blsmskl %ecx, %ecx
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+ /* eax non-zero if search CHAR in range. */
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+ andl %ecx, %eax
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+ jnz L(first_vec_x1_return)
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+
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+ /* fallthrough: no match in YMM2 then need to check for earlier
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+ matches (in YMM1). */
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+ .p2align 4,, 4
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+L(first_vec_x0_test):
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VPCMP $0, %YMMMATCH, %YMM1, %k1
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- kmovd %k0, %edx
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kmovd %k1, %eax
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-
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- shrxl %SHIFT_REG, %edx, %edx
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- shrxl %SHIFT_REG, %eax, %eax
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- addq $VEC_SIZE, %rdi
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-
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- /* Check if there is a CHAR. */
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testl %eax, %eax
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- jnz L(found_char)
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-
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- testl %edx, %edx
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- jnz L(return_null)
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-
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- jmp L(aligned_loop)
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-
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- .p2align 4
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-L(found_char):
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- testl %edx, %edx
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- jnz L(char_and_nul)
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-
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- /* Remember the match and keep searching. */
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- movl %eax, %edx
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- leaq (%rdi, %rcx), %rsi
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+ jz L(ret1)
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+ bsrl %eax, %eax
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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
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-L(aligned_loop):
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- VMOVA (%rdi), %YMM1
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- addq $VEC_SIZE, %rdi
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+ .p2align 4,, 10
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+L(first_vec_x1_or_x2):
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+ VPCMP $0, %YMM3, %YMMMATCH, %k3
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+ VPCMP $0, %YMM2, %YMMMATCH, %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 YMM1. */
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+ kortestd %k2, %k3
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+ jz L(first_vec_x0_test)
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+
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+ /* Guranteed that YMM2 and YMM3 are within range so merge the
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+ two bitmasks then get last result. */
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+ kunpck %k2, %k3, %k3
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+ kmovq %k3, %rax
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+ bsrq %rax, %rax
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+ leaq (VEC_SIZE)(%r8, %rax, CHAR_SIZE), %rax
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+ ret
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- /* Each bit in K0 represents a null byte in YMM1. */
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- VPCMP $0, %YMMZERO, %YMM1, %k0
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- /* Each bit in K1 represents a CHAR in YMM1. */
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- VPCMP $0, %YMMMATCH, %YMM1, %k1
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- kmovd %k0, %ecx
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+ .p2align 4,, 6
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+L(first_vec_x3):
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+ VPCMP $0, %YMMMATCH, %YMM4, %k1
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kmovd %k1, %eax
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- orl %eax, %ecx
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- jnz L(char_nor_null)
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+ blsmskl %ecx, %ecx
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+ /* If no search CHAR match in range check YMM1/YMM2/YMM3. */
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+ andl %ecx, %eax
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+ jz L(first_vec_x1_or_x2)
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+ bsrl %eax, %eax
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+ leaq (VEC_SIZE * 3)(%rdi, %rax, CHAR_SIZE), %rax
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+ ret
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- VMOVA (%rdi), %YMM1
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- add $VEC_SIZE, %rdi
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+ .p2align 4,, 6
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+L(first_vec_x0_x1_test):
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+ VPCMP $0, %YMMMATCH, %YMM2, %k1
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+ kmovd %k1, %eax
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+ /* Check YMM2 for last match first. If no match try YMM1. */
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+ testl %eax, %eax
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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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+ bsrl %eax, %eax
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+ leaq (VEC_SIZE)(%rdi, %rax, CHAR_SIZE), %rax
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+ ret
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- /* Each bit in K0 represents a null byte in YMM1. */
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- VPCMP $0, %YMMZERO, %YMM1, %k0
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- /* Each bit in K1 represents a CHAR in YMM1. */
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- VPCMP $0, %YMMMATCH, %YMM1, %k1
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- kmovd %k0, %ecx
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+ .p2align 4,, 10
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+L(first_vec_x2):
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+ VPCMP $0, %YMMMATCH, %YMM3, %k1
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kmovd %k1, %eax
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- orl %eax, %ecx
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- jnz L(char_nor_null)
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+ blsmskl %ecx, %ecx
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+ /* Check YMM3 for last match first. If no match try YMM2/YMM1.
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+ */
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+ andl %ecx, %eax
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+ jz L(first_vec_x0_x1_test)
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+ bsrl %eax, %eax
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+ leaq (VEC_SIZE * 2)(%rdi, %rax, CHAR_SIZE), %rax
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+ ret
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- VMOVA (%rdi), %YMM1
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- addq $VEC_SIZE, %rdi
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- /* Each bit in K0 represents a null byte in YMM1. */
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- VPCMP $0, %YMMZERO, %YMM1, %k0
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- /* Each bit in K1 represents a CHAR in YMM1. */
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- VPCMP $0, %YMMMATCH, %YMM1, %k1
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+ .p2align 4
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+L(aligned_more):
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+ /* Need to keep original pointer incase YMM1 has last match. */
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+ movq %rdi, %rsi
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+ andq $-VEC_SIZE, %rdi
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+ VMOVU VEC_SIZE(%rdi), %YMM2
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+ VPTESTN %YMM2, %YMM2, %k0
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kmovd %k0, %ecx
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- kmovd %k1, %eax
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- orl %eax, %ecx
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- jnz L(char_nor_null)
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+ testl %ecx, %ecx
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+ jnz L(first_vec_x1)
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- VMOVA (%rdi), %YMM1
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- addq $VEC_SIZE, %rdi
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+ VMOVU (VEC_SIZE * 2)(%rdi), %YMM3
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+ VPTESTN %YMM3, %YMM3, %k0
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+ kmovd %k0, %ecx
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+ testl %ecx, %ecx
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+ jnz L(first_vec_x2)
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- /* Each bit in K0 represents a null byte in YMM1. */
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- VPCMP $0, %YMMZERO, %YMM1, %k0
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- /* Each bit in K1 represents a CHAR in YMM1. */
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- VPCMP $0, %YMMMATCH, %YMM1, %k1
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+ VMOVU (VEC_SIZE * 3)(%rdi), %YMM4
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+ VPTESTN %YMM4, %YMM4, %k0
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kmovd %k0, %ecx
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- kmovd %k1, %eax
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- orl %eax, %ecx
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- jz L(aligned_loop)
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+ movq %rdi, %r8
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+ testl %ecx, %ecx
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+ jnz L(first_vec_x3)
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+ andq $-(VEC_SIZE * 2), %rdi
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.p2align 4
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-L(char_nor_null):
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- /* Find a CHAR or a null byte in a loop. */
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+L(first_aligned_loop):
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+ /* Preserve YMM1, YMM2, YMM3, and YMM4 until we can gurantee
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+ they don't store a match. */
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+ VMOVA (VEC_SIZE * 4)(%rdi), %YMM5
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+ VMOVA (VEC_SIZE * 5)(%rdi), %YMM6
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+
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+ VPCMP $0, %YMM5, %YMMMATCH, %k2
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+ vpxord %YMM6, %YMMMATCH, %YMM7
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+
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+ VPMIN %YMM5, %YMM6, %YMM8
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+ VPMIN %YMM8, %YMM7, %YMM7
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+
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+ VPTESTN %YMM7, %YMM7, %k1
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+ subq $(VEC_SIZE * -2), %rdi
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+ kortestd %k1, %k2
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+ jz L(first_aligned_loop)
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+
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+ VPCMP $0, %YMM6, %YMMMATCH, %k3
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+ VPTESTN %YMM8, %YMM8, %k1
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+ ktestd %k1, %k1
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+ jz L(second_aligned_loop_prep)
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+
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+ kortestd %k2, %k3
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+ jnz L(return_first_aligned_loop)
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+
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+ .p2align 4,, 6
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+L(first_vec_x1_or_x2_or_x3):
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+ VPCMP $0, %YMM4, %YMMMATCH, %k4
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+ kmovd %k4, %eax
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testl %eax, %eax
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- jnz L(match)
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-L(return_value):
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- testl %edx, %edx
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- jz L(return_null)
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- movl %edx, %eax
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- movq %rsi, %rdi
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+ jz L(first_vec_x1_or_x2)
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bsrl %eax, %eax
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-# ifdef USE_AS_WCSRCHR
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- /* NB: Multiply wchar_t count by 4 to get the number of bytes. */
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- leaq -VEC_SIZE(%rdi, %rax, 4), %rax
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-# else
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- leaq -VEC_SIZE(%rdi, %rax), %rax
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-# endif
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+ leaq (VEC_SIZE * 3)(%r8, %rax, CHAR_SIZE), %rax
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ret
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- .p2align 4
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-L(match):
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- /* Find a CHAR. Check if there is a null byte. */
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- kmovd %k0, %ecx
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- testl %ecx, %ecx
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- jnz L(find_nul)
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+ .p2align 4,, 8
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+L(return_first_aligned_loop):
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+ VPTESTN %YMM5, %YMM5, %k0
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+ kunpck %k0, %k1, %k0
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+ kmov_2x %k0, %maskz_2x
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+
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+ blsmsk %maskz_2x, %maskz_2x
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+ kunpck %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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- /* Remember the match and keep searching. */
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- movl %eax, %edx
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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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+
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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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- jmp L(aligned_loop)
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+ kunpck %k2, %k3, %k4
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.p2align 4
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-L(find_nul):
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- /* Mask out any matching bits after the null byte. */
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- movl %ecx, %r8d
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- subl $1, %r8d
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- xorl %ecx, %r8d
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- andl %r8d, %eax
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- testl %eax, %eax
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- /* If there is no CHAR here, return the remembered one. */
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- jz L(return_value)
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- bsrl %eax, %eax
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+L(second_aligned_loop):
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+ VMOVU (VEC_SIZE * 4)(%rdi), %YMM1
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+ VMOVU (VEC_SIZE * 5)(%rdi), %YMM2
|
|
+
|
|
+ VPCMP $0, %YMM1, %YMMMATCH, %k2
|
|
+ vpxord %YMM2, %YMMMATCH, %YMM3
|
|
+
|
|
+ VPMIN %YMM1, %YMM2, %YMM4
|
|
+ VPMIN %YMM3, %YMM4, %YMM3
|
|
+
|
|
+ VPTESTN %YMM3, %YMM3, %k1
|
|
+ subq $(VEC_SIZE * -2), %rdi
|
|
+ kortestd %k1, %k2
|
|
+ jz L(second_aligned_loop)
|
|
+
|
|
+ VPCMP $0, %YMM2, %YMMMATCH, %k3
|
|
+ VPTESTN %YMM4, %YMM4, %k1
|
|
+ ktestd %k1, %k1
|
|
+ jz L(second_aligned_loop_set_furthest_match)
|
|
+
|
|
+ kortestd %k2, %k3
|
|
+ /* branch here because there is a significant advantage interms
|
|
+ of output dependency chance in using edx. */
|
|
+ jnz L(return_new_match)
|
|
+L(return_old_match):
|
|
+ kmovq %k4, %rax
|
|
+ bsrq %rax, %rax
|
|
+ leaq (VEC_SIZE * 2)(%rsi, %rax, CHAR_SIZE), %rax
|
|
+ ret
|
|
+
|
|
+L(return_new_match):
|
|
+ VPTESTN %YMM1, %YMM1, %k0
|
|
+ kunpck %k0, %k1, %k0
|
|
+ kmov_2x %k0, %maskz_2x
|
|
+
|
|
+ blsmsk %maskz_2x, %maskz_2x
|
|
+ kunpck %k2, %k3, %k3
|
|
+ kmov_2x %k3, %maskm_2x
|
|
+ and %maskz_2x, %maskm_2x
|
|
+ jz L(return_old_match)
|
|
+
|
|
+ bsr %maskm_2x, %maskm_2x
|
|
+ leaq (VEC_SIZE * 2)(%rdi, %rax, CHAR_SIZE), %rax
|
|
+ ret
|
|
+
|
|
+L(cross_page_boundary):
|
|
+ /* eax contains all the page offset bits of src (rdi). `xor rdi,
|
|
+ rax` sets pointer will all page offset bits cleared so
|
|
+ offset of (PAGE_SIZE - VEC_SIZE) will get last aligned VEC
|
|
+ before page cross (guranteed to be safe to read). Doing this
|
|
+ as opposed to `movq %rdi, %rax; andq $-VEC_SIZE, %rax` saves
|
|
+ a bit of code size. */
|
|
+ xorq %rdi, %rax
|
|
+ VMOVU (PAGE_SIZE - VEC_SIZE)(%rax), %YMM1
|
|
+ VPTESTN %YMM1, %YMM1, %k0
|
|
+ kmovd %k0, %ecx
|
|
+
|
|
+ /* Shift out zero CHAR matches that are before the begining of
|
|
+ src (rdi). */
|
|
# ifdef USE_AS_WCSRCHR
|
|
- /* NB: Multiply wchar_t count by 4 to get the number of bytes. */
|
|
- leaq -VEC_SIZE(%rdi, %rax, 4), %rax
|
|
-# else
|
|
- leaq -VEC_SIZE(%rdi, %rax), %rax
|
|
+ movl %edi, %esi
|
|
+ andl $(VEC_SIZE - 1), %esi
|
|
+ shrl $2, %esi
|
|
# endif
|
|
- ret
|
|
+ shrxl %SHIFT_REG, %ecx, %ecx
|
|
|
|
- .p2align 4
|
|
-L(char_and_nul):
|
|
- /* Find both a CHAR and a null byte. */
|
|
- addq %rcx, %rdi
|
|
- movl %edx, %ecx
|
|
-L(char_and_nul_in_first_vec):
|
|
- /* Mask out any matching bits after the null byte. */
|
|
- movl %ecx, %r8d
|
|
- subl $1, %r8d
|
|
- xorl %ecx, %r8d
|
|
- andl %r8d, %eax
|
|
- testl %eax, %eax
|
|
- /* Return null pointer if the null byte comes first. */
|
|
- jz L(return_null)
|
|
+ testl %ecx, %ecx
|
|
+ jz L(page_cross_continue)
|
|
+
|
|
+ /* Found zero CHAR so need to test for search CHAR. */
|
|
+ VPCMP $0, %YMMMATCH, %YMM1, %k1
|
|
+ kmovd %k1, %eax
|
|
+ /* Shift out search CHAR matches that are before the begining of
|
|
+ src (rdi). */
|
|
+ shrxl %SHIFT_REG, %eax, %eax
|
|
+
|
|
+ /* Check if any search CHAR match in range. */
|
|
+ blsmskl %ecx, %ecx
|
|
+ andl %ecx, %eax
|
|
+ jz L(ret3)
|
|
bsrl %eax, %eax
|
|
# ifdef USE_AS_WCSRCHR
|
|
- /* NB: Multiply wchar_t count by 4 to get the number of bytes. */
|
|
- leaq -VEC_SIZE(%rdi, %rax, 4), %rax
|
|
+ leaq (%rdi, %rax, CHAR_SIZE), %rax
|
|
# else
|
|
- leaq -VEC_SIZE(%rdi, %rax), %rax
|
|
+ addq %rdi, %rax
|
|
# endif
|
|
+L(ret3):
|
|
ret
|
|
|
|
- .p2align 4
|
|
-L(return_null):
|
|
- xorl %eax, %eax
|
|
- ret
|
|
-
|
|
-END (STRRCHR)
|
|
+END(STRRCHR)
|
|
#endif
|
|
--
|
|
GitLab
|
|
|