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585 lines
14 KiB
585 lines
14 KiB
From acfd088a1963ba51cd83c78f95c0ab25ead79e04 Mon Sep 17 00:00:00 2001
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From: Noah Goldstein <goldstein.w.n@gmail.com>
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Date: Mon, 3 May 2021 03:01:58 -0400
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Subject: [PATCH] x86: Optimize memchr-avx2.S
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Content-type: text/plain; charset=UTF-8
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No bug. This commit optimizes memchr-avx2.S. The optimizations include
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replacing some branches with cmovcc, avoiding some branches entirely
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in the less_4x_vec case, making the page cross logic less strict,
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asaving a few instructions the in loop return loop. test-memchr,
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test-rawmemchr, and test-wmemchr are all passing.
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Signed-off-by: Noah Goldstein <goldstein.w.n@gmail.com>
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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/memchr-avx2.S | 425 ++++++++++++++-----------
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1 file changed, 247 insertions(+), 178 deletions(-)
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diff --git a/sysdeps/x86_64/multiarch/memchr-avx2.S b/sysdeps/x86_64/multiarch/memchr-avx2.S
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index cf893e77..b377f22e 100644
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--- a/sysdeps/x86_64/multiarch/memchr-avx2.S
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+++ b/sysdeps/x86_64/multiarch/memchr-avx2.S
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@@ -26,8 +26,22 @@
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# ifdef USE_AS_WMEMCHR
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# define VPCMPEQ vpcmpeqd
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+# define VPBROADCAST vpbroadcastd
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+# define CHAR_SIZE 4
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# else
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# define VPCMPEQ vpcmpeqb
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+# define VPBROADCAST vpbroadcastb
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+# define CHAR_SIZE 1
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+# endif
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+
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+# ifdef USE_AS_RAWMEMCHR
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+# define ERAW_PTR_REG ecx
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+# define RRAW_PTR_REG rcx
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+# define ALGN_PTR_REG rdi
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+# else
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+# define ERAW_PTR_REG edi
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+# define RRAW_PTR_REG rdi
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+# define ALGN_PTR_REG rcx
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# endif
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# ifndef VZEROUPPER
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@@ -39,6 +53,7 @@
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# endif
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# define VEC_SIZE 32
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+# define PAGE_SIZE 4096
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.section SECTION(.text),"ax",@progbits
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ENTRY (MEMCHR)
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@@ -47,295 +62,349 @@ ENTRY (MEMCHR)
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test %RDX_LP, %RDX_LP
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jz L(null)
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# endif
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- movl %edi, %ecx
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- /* Broadcast CHAR to YMM0. */
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- vmovd %esi, %xmm0
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# ifdef USE_AS_WMEMCHR
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shl $2, %RDX_LP
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- vpbroadcastd %xmm0, %ymm0
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# else
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# ifdef __ILP32__
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/* Clear the upper 32 bits. */
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movl %edx, %edx
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# endif
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- vpbroadcastb %xmm0, %ymm0
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# endif
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+ /* Broadcast CHAR to YMMMATCH. */
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+ vmovd %esi, %xmm0
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+ VPBROADCAST %xmm0, %ymm0
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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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+ movl %edi, %eax
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+ andl $(PAGE_SIZE - 1), %eax
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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. */
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- VPCMPEQ (%rdi), %ymm0, %ymm1
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+ VPCMPEQ (%rdi), %ymm0, %ymm1
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vpmovmskb %ymm1, %eax
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- testl %eax, %eax
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-
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# ifndef USE_AS_RAWMEMCHR
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- jnz L(first_vec_x0_check)
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- /* Adjust length and check the end of data. */
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- subq $VEC_SIZE, %rdx
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- jbe L(zero)
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-# else
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- jnz L(first_vec_x0)
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+ /* If length < CHAR_PER_VEC handle special. */
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+ cmpq $VEC_SIZE, %rdx
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+ jbe L(first_vec_x0)
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# endif
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-
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- /* Align data for aligned loads in the loop. */
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- addq $VEC_SIZE, %rdi
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- andl $(VEC_SIZE - 1), %ecx
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- andq $-VEC_SIZE, %rdi
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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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+ addq %rdi, %rax
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+ VZEROUPPER_RETURN
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# ifndef USE_AS_RAWMEMCHR
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- /* Adjust length. */
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- addq %rcx, %rdx
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+ .p2align 5
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+L(first_vec_x0):
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+ /* Check if first match was before length. */
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+ tzcntl %eax, %eax
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+ xorl %ecx, %ecx
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+ cmpl %eax, %edx
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+ leaq (%rdi, %rax), %rax
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+ cmovle %rcx, %rax
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+ VZEROUPPER_RETURN
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- subq $(VEC_SIZE * 4), %rdx
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- jbe L(last_4x_vec_or_less)
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+L(null):
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+ xorl %eax, %eax
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+ ret
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# endif
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- jmp L(more_4x_vec)
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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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- VPCMPEQ (%rdi), %ymm0, %ymm1
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+L(cross_page_boundary):
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+ /* Save pointer before aligning as its original value is necessary
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+ for computer return address if byte is found or adjusting length
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+ if it is not and this is memchr. */
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+ movq %rdi, %rcx
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+ /* Align data to VEC_SIZE - 1. ALGN_PTR_REG is rcx for memchr and
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+ rdi for rawmemchr. */
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+ orq $(VEC_SIZE - 1), %ALGN_PTR_REG
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+ VPCMPEQ -(VEC_SIZE - 1)(%ALGN_PTR_REG), %ymm0, %ymm1
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vpmovmskb %ymm1, %eax
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+# ifndef USE_AS_RAWMEMCHR
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+ /* Calculate length until end of page (length checked for a
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+ match). */
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+ leaq 1(%ALGN_PTR_REG), %rsi
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+ subq %RRAW_PTR_REG, %rsi
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+# endif
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/* Remove the leading bytes. */
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- sarl %cl, %eax
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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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+ sarxl %ERAW_PTR_REG, %eax, %eax
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# ifndef USE_AS_RAWMEMCHR
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/* Check the end of data. */
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- cmpq %rax, %rdx
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- jbe L(zero)
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+ cmpq %rsi, %rdx
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+ jbe L(first_vec_x0)
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# endif
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- addq %rdi, %rax
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- addq %rcx, %rax
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+ testl %eax, %eax
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+ jz L(cross_page_continue)
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+ tzcntl %eax, %eax
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+ addq %RRAW_PTR_REG, %rax
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L(return_vzeroupper):
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ZERO_UPPER_VEC_REGISTERS_RETURN
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.p2align 4
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-L(aligned_more):
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-# ifndef USE_AS_RAWMEMCHR
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- /* Calculate "rdx + rcx - VEC_SIZE" with "rdx - (VEC_SIZE - rcx)"
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- instead of "(rdx + rcx) - VEC_SIZE" to void possible addition
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- overflow. */
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- negq %rcx
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- addq $VEC_SIZE, %rcx
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+L(first_vec_x1):
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+ tzcntl %eax, %eax
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+ incq %rdi
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+ addq %rdi, %rax
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+ VZEROUPPER_RETURN
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- /* Check the end of data. */
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- subq %rcx, %rdx
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- jbe L(zero)
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-# endif
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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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+ addq $(VEC_SIZE + 1), %rdi
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+ addq %rdi, %rax
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+ VZEROUPPER_RETURN
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+
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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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+ addq $(VEC_SIZE * 2 + 1), %rdi
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+ addq %rdi, %rax
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+ VZEROUPPER_RETURN
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- addq $VEC_SIZE, %rdi
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-# ifndef USE_AS_RAWMEMCHR
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- subq $(VEC_SIZE * 4), %rdx
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- jbe L(last_4x_vec_or_less)
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-# endif
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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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+ addq $(VEC_SIZE * 3 + 1), %rdi
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+ addq %rdi, %rax
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+ VZEROUPPER_RETURN
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-L(more_4x_vec):
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+ .p2align 4
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+L(aligned_more):
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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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- VPCMPEQ (%rdi), %ymm0, %ymm1
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- vpmovmskb %ymm1, %eax
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- testl %eax, %eax
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- jnz L(first_vec_x0)
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- VPCMPEQ VEC_SIZE(%rdi), %ymm0, %ymm1
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+# ifndef USE_AS_RAWMEMCHR
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+L(cross_page_continue):
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+ /* Align data to VEC_SIZE - 1. */
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+ xorl %ecx, %ecx
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+ subl %edi, %ecx
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+ orq $(VEC_SIZE - 1), %rdi
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+ /* esi is for adjusting length to see if near the end. */
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+ leal (VEC_SIZE * 4 + 1)(%rdi, %rcx), %esi
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+# else
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+ orq $(VEC_SIZE - 1), %rdi
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+L(cross_page_continue):
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+# endif
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+ /* Load first VEC regardless. */
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+ VPCMPEQ 1(%rdi), %ymm0, %ymm1
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vpmovmskb %ymm1, %eax
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+# ifndef USE_AS_RAWMEMCHR
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+ /* Adjust length. If near end handle specially. */
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+ subq %rsi, %rdx
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+ jbe L(last_4x_vec_or_less)
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+# endif
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testl %eax, %eax
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jnz L(first_vec_x1)
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- VPCMPEQ (VEC_SIZE * 2)(%rdi), %ymm0, %ymm1
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+ VPCMPEQ (VEC_SIZE + 1)(%rdi), %ymm0, %ymm1
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vpmovmskb %ymm1, %eax
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testl %eax, %eax
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jnz L(first_vec_x2)
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- VPCMPEQ (VEC_SIZE * 3)(%rdi), %ymm0, %ymm1
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+ VPCMPEQ (VEC_SIZE * 2 + 1)(%rdi), %ymm0, %ymm1
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vpmovmskb %ymm1, %eax
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testl %eax, %eax
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jnz L(first_vec_x3)
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- addq $(VEC_SIZE * 4), %rdi
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+ VPCMPEQ (VEC_SIZE * 3 + 1)(%rdi), %ymm0, %ymm1
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+ vpmovmskb %ymm1, %eax
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+ testl %eax, %eax
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+ jnz L(first_vec_x4)
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# ifndef USE_AS_RAWMEMCHR
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+ /* Check if at last VEC_SIZE * 4 length. */
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subq $(VEC_SIZE * 4), %rdx
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- jbe L(last_4x_vec_or_less)
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-# endif
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-
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- /* Align data to 4 * VEC_SIZE. */
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- movq %rdi, %rcx
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- andl $(4 * VEC_SIZE - 1), %ecx
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- andq $-(4 * VEC_SIZE), %rdi
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-
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-# ifndef USE_AS_RAWMEMCHR
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- /* Adjust length. */
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+ jbe L(last_4x_vec_or_less_cmpeq)
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+ /* Align data to VEC_SIZE * 4 - 1 for the loop and readjust
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+ length. */
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+ incq %rdi
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+ movl %edi, %ecx
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+ orq $(VEC_SIZE * 4 - 1), %rdi
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+ andl $(VEC_SIZE * 4 - 1), %ecx
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addq %rcx, %rdx
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+# else
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+ /* Align data to VEC_SIZE * 4 - 1 for loop. */
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+ incq %rdi
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+ orq $(VEC_SIZE * 4 - 1), %rdi
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# endif
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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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- /* Compare 4 * VEC at a time forward. */
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- VPCMPEQ (%rdi), %ymm0, %ymm1
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- VPCMPEQ VEC_SIZE(%rdi), %ymm0, %ymm2
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- VPCMPEQ (VEC_SIZE * 2)(%rdi), %ymm0, %ymm3
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- VPCMPEQ (VEC_SIZE * 3)(%rdi), %ymm0, %ymm4
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-
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+ VPCMPEQ 1(%rdi), %ymm0, %ymm1
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+ VPCMPEQ (VEC_SIZE + 1)(%rdi), %ymm0, %ymm2
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+ VPCMPEQ (VEC_SIZE * 2 + 1)(%rdi), %ymm0, %ymm3
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+ VPCMPEQ (VEC_SIZE * 3 + 1)(%rdi), %ymm0, %ymm4
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vpor %ymm1, %ymm2, %ymm5
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vpor %ymm3, %ymm4, %ymm6
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vpor %ymm5, %ymm6, %ymm5
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- vpmovmskb %ymm5, %eax
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- testl %eax, %eax
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- jnz L(4x_vec_end)
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-
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- addq $(VEC_SIZE * 4), %rdi
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-
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+ vpmovmskb %ymm5, %ecx
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# ifdef USE_AS_RAWMEMCHR
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- jmp L(loop_4x_vec)
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+ subq $-(VEC_SIZE * 4), %rdi
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+ testl %ecx, %ecx
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+ jz L(loop_4x_vec)
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# else
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- subq $(VEC_SIZE * 4), %rdx
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- ja L(loop_4x_vec)
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+ testl %ecx, %ecx
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+ jnz L(loop_4x_vec_end)
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-L(last_4x_vec_or_less):
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- /* Less than 4 * VEC and aligned to VEC_SIZE. */
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- addl $(VEC_SIZE * 2), %edx
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- jle L(last_2x_vec)
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+ subq $-(VEC_SIZE * 4), %rdi
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- VPCMPEQ (%rdi), %ymm0, %ymm1
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- vpmovmskb %ymm1, %eax
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- testl %eax, %eax
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- jnz L(first_vec_x0)
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+ subq $(VEC_SIZE * 4), %rdx
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+ ja L(loop_4x_vec)
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- VPCMPEQ VEC_SIZE(%rdi), %ymm0, %ymm1
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+ /* Fall through into less than 4 remaining vectors of length case.
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+ */
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+ VPCMPEQ (VEC_SIZE * 0 + 1)(%rdi), %ymm0, %ymm1
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vpmovmskb %ymm1, %eax
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+ .p2align 4
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+L(last_4x_vec_or_less):
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+ /* Check if first VEC contained match. */
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testl %eax, %eax
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- jnz L(first_vec_x1)
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+ jnz L(first_vec_x1_check)
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- VPCMPEQ (VEC_SIZE * 2)(%rdi), %ymm0, %ymm1
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- vpmovmskb %ymm1, %eax
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- testl %eax, %eax
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+ /* If remaining length > VEC_SIZE * 2. */
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+ addl $(VEC_SIZE * 2), %edx
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+ jg L(last_4x_vec)
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- jnz L(first_vec_x2_check)
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- subl $VEC_SIZE, %edx
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- jle L(zero)
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+L(last_2x_vec):
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+ /* If remaining length < VEC_SIZE. */
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+ addl $VEC_SIZE, %edx
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+ jle L(zero_end)
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- VPCMPEQ (VEC_SIZE * 3)(%rdi), %ymm0, %ymm1
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+ /* Check VEC2 and compare any match with remaining length. */
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+ VPCMPEQ (VEC_SIZE + 1)(%rdi), %ymm0, %ymm1
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vpmovmskb %ymm1, %eax
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- testl %eax, %eax
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-
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- jnz L(first_vec_x3_check)
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- xorl %eax, %eax
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+ tzcntl %eax, %eax
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+ cmpl %eax, %edx
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+ jbe L(set_zero_end)
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+ addq $(VEC_SIZE + 1), %rdi
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+ addq %rdi, %rax
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+L(zero_end):
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VZEROUPPER_RETURN
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.p2align 4
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-L(last_2x_vec):
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- addl $(VEC_SIZE * 2), %edx
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- VPCMPEQ (%rdi), %ymm0, %ymm1
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+L(loop_4x_vec_end):
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+# endif
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+ /* rawmemchr will fall through into this if match was found in
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+ loop. */
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+
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vpmovmskb %ymm1, %eax
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testl %eax, %eax
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+ jnz L(last_vec_x1_return)
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- jnz L(first_vec_x0_check)
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- subl $VEC_SIZE, %edx
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- jle L(zero)
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-
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- VPCMPEQ VEC_SIZE(%rdi), %ymm0, %ymm1
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- vpmovmskb %ymm1, %eax
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+ vpmovmskb %ymm2, %eax
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testl %eax, %eax
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- jnz L(first_vec_x1_check)
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- xorl %eax, %eax
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- VZEROUPPER_RETURN
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+ jnz L(last_vec_x2_return)
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- .p2align 4
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-L(first_vec_x0_check):
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- tzcntl %eax, %eax
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- /* Check the end of data. */
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- cmpq %rax, %rdx
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- jbe L(zero)
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+ vpmovmskb %ymm3, %eax
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+ /* Combine VEC3 matches (eax) with VEC4 matches (ecx). */
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+ salq $32, %rcx
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+ orq %rcx, %rax
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+ tzcntq %rax, %rax
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+# ifdef USE_AS_RAWMEMCHR
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+ subq $(VEC_SIZE * 2 - 1), %rdi
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+# else
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+ subq $-(VEC_SIZE * 2 + 1), %rdi
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+# endif
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addq %rdi, %rax
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VZEROUPPER_RETURN
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+# ifndef USE_AS_RAWMEMCHR
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.p2align 4
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L(first_vec_x1_check):
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tzcntl %eax, %eax
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- /* Check the end of data. */
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- cmpq %rax, %rdx
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- jbe L(zero)
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- addq $VEC_SIZE, %rax
|
|
+ /* Adjust length. */
|
|
+ subl $-(VEC_SIZE * 4), %edx
|
|
+ /* Check if match within remaining length. */
|
|
+ cmpl %eax, %edx
|
|
+ jbe L(set_zero_end)
|
|
+ incq %rdi
|
|
addq %rdi, %rax
|
|
VZEROUPPER_RETURN
|
|
+ .p2align 4
|
|
+L(set_zero_end):
|
|
+ xorl %eax, %eax
|
|
+ VZEROUPPER_RETURN
|
|
+# endif
|
|
|
|
.p2align 4
|
|
-L(first_vec_x2_check):
|
|
+L(last_vec_x1_return):
|
|
tzcntl %eax, %eax
|
|
- /* Check the end of data. */
|
|
- cmpq %rax, %rdx
|
|
- jbe L(zero)
|
|
- addq $(VEC_SIZE * 2), %rax
|
|
+# ifdef USE_AS_RAWMEMCHR
|
|
+ subq $(VEC_SIZE * 4 - 1), %rdi
|
|
+# else
|
|
+ incq %rdi
|
|
+# endif
|
|
addq %rdi, %rax
|
|
VZEROUPPER_RETURN
|
|
|
|
.p2align 4
|
|
-L(first_vec_x3_check):
|
|
+L(last_vec_x2_return):
|
|
tzcntl %eax, %eax
|
|
- /* Check the end of data. */
|
|
- cmpq %rax, %rdx
|
|
- jbe L(zero)
|
|
- addq $(VEC_SIZE * 3), %rax
|
|
+# ifdef USE_AS_RAWMEMCHR
|
|
+ subq $(VEC_SIZE * 3 - 1), %rdi
|
|
+# else
|
|
+ subq $-(VEC_SIZE + 1), %rdi
|
|
+# endif
|
|
addq %rdi, %rax
|
|
VZEROUPPER_RETURN
|
|
|
|
+# ifndef USE_AS_RAWMEMCHR
|
|
.p2align 4
|
|
-L(zero):
|
|
- xorl %eax, %eax
|
|
- jmp L(return_vzeroupper)
|
|
+L(last_4x_vec_or_less_cmpeq):
|
|
+ VPCMPEQ (VEC_SIZE * 4 + 1)(%rdi), %ymm0, %ymm1
|
|
+ vpmovmskb %ymm1, %eax
|
|
+ subq $-(VEC_SIZE * 4), %rdi
|
|
+ /* Check first VEC regardless. */
|
|
+ testl %eax, %eax
|
|
+ jnz L(first_vec_x1_check)
|
|
|
|
+ /* If remaining length <= CHAR_PER_VEC * 2. */
|
|
+ addl $(VEC_SIZE * 2), %edx
|
|
+ jle L(last_2x_vec)
|
|
.p2align 4
|
|
-L(null):
|
|
- xorl %eax, %eax
|
|
- ret
|
|
-# endif
|
|
+L(last_4x_vec):
|
|
+ VPCMPEQ (VEC_SIZE + 1)(%rdi), %ymm0, %ymm1
|
|
+ vpmovmskb %ymm1, %eax
|
|
+ testl %eax, %eax
|
|
+ jnz L(last_vec_x2_return)
|
|
|
|
- .p2align 4
|
|
-L(first_vec_x0):
|
|
- tzcntl %eax, %eax
|
|
- addq %rdi, %rax
|
|
- VZEROUPPER_RETURN
|
|
+ VPCMPEQ (VEC_SIZE * 2 + 1)(%rdi), %ymm0, %ymm1
|
|
+ vpmovmskb %ymm1, %eax
|
|
|
|
- .p2align 4
|
|
-L(first_vec_x1):
|
|
- tzcntl %eax, %eax
|
|
- addq $VEC_SIZE, %rax
|
|
- addq %rdi, %rax
|
|
- VZEROUPPER_RETURN
|
|
+ /* Create mask for possible matches within remaining length. */
|
|
+ movq $-1, %rcx
|
|
+ bzhiq %rdx, %rcx, %rcx
|
|
|
|
- .p2align 4
|
|
-L(first_vec_x2):
|
|
+ /* Test matches in data against length match. */
|
|
+ andl %ecx, %eax
|
|
+ jnz L(last_vec_x3)
|
|
+
|
|
+ /* if remaining length <= VEC_SIZE * 3 (Note this is after
|
|
+ remaining length was found to be > VEC_SIZE * 2. */
|
|
+ subl $VEC_SIZE, %edx
|
|
+ jbe L(zero_end2)
|
|
+
|
|
+ VPCMPEQ (VEC_SIZE * 3 + 1)(%rdi), %ymm0, %ymm1
|
|
+ vpmovmskb %ymm1, %eax
|
|
+ /* Shift remaining length mask for last VEC. */
|
|
+ shrq $32, %rcx
|
|
+ andl %ecx, %eax
|
|
+ jz L(zero_end2)
|
|
tzcntl %eax, %eax
|
|
- addq $(VEC_SIZE * 2), %rax
|
|
+ addq $(VEC_SIZE * 3 + 1), %rdi
|
|
addq %rdi, %rax
|
|
+L(zero_end2):
|
|
VZEROUPPER_RETURN
|
|
|
|
.p2align 4
|
|
-L(4x_vec_end):
|
|
- vpmovmskb %ymm1, %eax
|
|
- testl %eax, %eax
|
|
- jnz L(first_vec_x0)
|
|
- vpmovmskb %ymm2, %eax
|
|
- testl %eax, %eax
|
|
- jnz L(first_vec_x1)
|
|
- vpmovmskb %ymm3, %eax
|
|
- testl %eax, %eax
|
|
- jnz L(first_vec_x2)
|
|
- vpmovmskb %ymm4, %eax
|
|
- testl %eax, %eax
|
|
-L(first_vec_x3):
|
|
+L(last_vec_x3):
|
|
tzcntl %eax, %eax
|
|
- addq $(VEC_SIZE * 3), %rax
|
|
+ subq $-(VEC_SIZE * 2 + 1), %rdi
|
|
addq %rdi, %rax
|
|
VZEROUPPER_RETURN
|
|
+# endif
|
|
|
|
END (MEMCHR)
|
|
#endif
|
|
--
|
|
GitLab
|
|
|