397 lines
9.6 KiB
Diff
397 lines
9.6 KiB
Diff
From ccabe7971f508709d034b63b8672f6f751a3d356 Mon Sep 17 00:00:00 2001
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From: Noah Goldstein <goldstein.w.n@gmail.com>
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Date: Fri, 23 Apr 2021 15:56:24 -0400
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Subject: [PATCH] x86: Optimize strchr-avx2.S
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Content-type: text/plain; charset=UTF-8
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No bug. This commit optimizes strchr-avx2.S. The optimizations are all
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small things such as save an ALU in the alignment process, saving a
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few instructions in the loop return, saving some bytes in the main
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loop, and increasing the ILP in the return cases. test-strchr,
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test-strchrnul, test-wcschr, and test-wcschrnul are all passing.
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Signed-off-by: Noah Goldstein <goldstein.w.n@gmail.com>
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---
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sysdeps/x86_64/multiarch/strchr-avx2.S | 290 +++++++++++++++----------
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1 file changed, 170 insertions(+), 120 deletions(-)
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Conflics:
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sysdeps/x86_64/multiarch/strchr-avx2.S
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(rearranged to account for branch changes)
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diff --git a/sysdeps/x86_64/multiarch/strchr-avx2.S b/sysdeps/x86_64/multiarch/strchr-avx2.S
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index 919d256c..5884726b 100644
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--- a/sysdeps/x86_64/multiarch/strchr-avx2.S
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+++ b/sysdeps/x86_64/multiarch/strchr-avx2.S
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@@ -49,133 +49,144 @@
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.section SECTION(.text),"ax",@progbits
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ENTRY (STRCHR)
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- movl %edi, %ecx
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-# ifndef USE_AS_STRCHRNUL
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- xorl %edx, %edx
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-# endif
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-
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/* Broadcast CHAR to YMM0. */
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vmovd %esi, %xmm0
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+ movl %edi, %eax
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+ andl $(PAGE_SIZE - 1), %eax
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+ VPBROADCAST %xmm0, %ymm0
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vpxor %xmm9, %xmm9, %xmm9
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- VPBROADCAST %xmm0, %ymm0
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/* Check if we cross page boundary with one vector load. */
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- andl $(PAGE_SIZE - 1), %ecx
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- cmpl $(PAGE_SIZE - VEC_SIZE), %ecx
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- ja L(cross_page_boundary)
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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. Search for both CHAR and the
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null byte. */
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vmovdqu (%rdi), %ymm8
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- VPCMPEQ %ymm8, %ymm0, %ymm1
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- VPCMPEQ %ymm8, %ymm9, %ymm2
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+ VPCMPEQ %ymm8, %ymm0, %ymm1
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+ VPCMPEQ %ymm8, %ymm9, %ymm2
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vpor %ymm1, %ymm2, %ymm1
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vpmovmskb %ymm1, %eax
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testl %eax, %eax
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- jz L(more_vecs)
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+ jz L(aligned_more)
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tzcntl %eax, %eax
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+# ifndef USE_AS_STRCHRNUL
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/* Found CHAR or the null byte. */
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+ cmp (%rdi, %rax), %CHAR_REG
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+ jne L(zero)
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+# endif
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addq %rdi, %rax
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+ VZEROUPPER_RETURN
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+
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+ /* .p2align 5 helps keep performance more consistent if ENTRY()
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+ alignment % 32 was either 16 or 0. As well this makes the
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+ alignment % 32 of the loop_4x_vec fixed which makes tuning it
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+ easier. */
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+ .p2align 5
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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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# ifndef USE_AS_STRCHRNUL
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- cmp (%rax), %CHAR_REG
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- cmovne %rdx, %rax
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+ /* Found CHAR or the null byte. */
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+ cmp (%rdi, %rax), %CHAR_REG
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+ jne L(zero)
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# endif
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-L(return_vzeroupper):
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- ZERO_UPPER_VEC_REGISTERS_RETURN
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-
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- .p2align 4
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-L(more_vecs):
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- /* Align data for aligned loads in the loop. */
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- andq $-VEC_SIZE, %rdi
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-L(aligned_more):
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-
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- /* Check the next 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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- vmovdqa VEC_SIZE(%rdi), %ymm8
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- addq $VEC_SIZE, %rdi
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- VPCMPEQ %ymm8, %ymm0, %ymm1
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- VPCMPEQ %ymm8, %ymm9, %ymm2
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- vpor %ymm1, %ymm2, %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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-
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- vmovdqa VEC_SIZE(%rdi), %ymm8
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- VPCMPEQ %ymm8, %ymm0, %ymm1
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- VPCMPEQ %ymm8, %ymm9, %ymm2
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- vpor %ymm1, %ymm2, %ymm1
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- vpmovmskb %ymm1, %eax
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- testl %eax, %eax
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- jnz L(first_vec_x1)
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-
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- vmovdqa (VEC_SIZE * 2)(%rdi), %ymm8
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- VPCMPEQ %ymm8, %ymm0, %ymm1
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- VPCMPEQ %ymm8, %ymm9, %ymm2
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- vpor %ymm1, %ymm2, %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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-
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- vmovdqa (VEC_SIZE * 3)(%rdi), %ymm8
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- VPCMPEQ %ymm8, %ymm0, %ymm1
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- VPCMPEQ %ymm8, %ymm9, %ymm2
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- vpor %ymm1, %ymm2, %ymm1
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- vpmovmskb %ymm1, %eax
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- testl %eax, %eax
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- jz L(prep_loop_4x)
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+ addq %rdi, %rax
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+ VZEROUPPER_RETURN
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- tzcntl %eax, %eax
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- leaq (VEC_SIZE * 3)(%rdi, %rax), %rax
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# ifndef USE_AS_STRCHRNUL
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- cmp (%rax), %CHAR_REG
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- cmovne %rdx, %rax
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+L(zero):
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+ xorl %eax, %eax
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+ VZEROUPPER_RETURN
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# endif
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- VZEROUPPER
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- ret
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+
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.p2align 4
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-L(first_vec_x0):
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+L(first_vec_x1):
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tzcntl %eax, %eax
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- /* Found CHAR or the null byte. */
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- addq %rdi, %rax
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+ incq %rdi
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# ifndef USE_AS_STRCHRNUL
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- cmp (%rax), %CHAR_REG
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- cmovne %rdx, %rax
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+ /* Found CHAR or the null byte. */
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+ cmp (%rdi, %rax), %CHAR_REG
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+ jne L(zero)
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# endif
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+ addq %rdi, %rax
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VZEROUPPER_RETURN
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.p2align 4
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-L(first_vec_x1):
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+L(first_vec_x2):
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tzcntl %eax, %eax
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- leaq VEC_SIZE(%rdi, %rax), %rax
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+ addq $(VEC_SIZE + 1), %rdi
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# ifndef USE_AS_STRCHRNUL
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- cmp (%rax), %CHAR_REG
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- cmovne %rdx, %rax
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+ /* Found CHAR or the null byte. */
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+ cmp (%rdi, %rax), %CHAR_REG
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+ jne L(zero)
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# endif
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+ addq %rdi, %rax
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VZEROUPPER_RETURN
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.p2align 4
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-L(first_vec_x2):
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+L(first_vec_x3):
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tzcntl %eax, %eax
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- /* Found CHAR or the null byte. */
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- leaq (VEC_SIZE * 2)(%rdi, %rax), %rax
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+ addq $(VEC_SIZE * 2 + 1), %rdi
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# ifndef USE_AS_STRCHRNUL
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- cmp (%rax), %CHAR_REG
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- cmovne %rdx, %rax
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+ /* Found CHAR or the null byte. */
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+ cmp (%rdi, %rax), %CHAR_REG
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+ jne L(zero)
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# endif
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+ addq %rdi, %rax
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VZEROUPPER_RETURN
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-L(prep_loop_4x):
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- /* Align data to 4 * VEC_SIZE. */
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- andq $-(VEC_SIZE * 4), %rdi
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+ .p2align 4
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+L(aligned_more):
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+ /* Align data to VEC_SIZE - 1. This is the same number of
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+ instructions as using andq -VEC_SIZE but saves 4 bytes of code
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+ on x4 check. */
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+ orq $(VEC_SIZE - 1), %rdi
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+L(cross_page_continue):
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+ /* Check the next 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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+ vmovdqa 1(%rdi), %ymm8
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+ VPCMPEQ %ymm8, %ymm0, %ymm1
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+ VPCMPEQ %ymm8, %ymm9, %ymm2
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+ vpor %ymm1, %ymm2, %ymm1
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+ vpmovmskb %ymm1, %eax
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+ testl %eax, %eax
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+ jnz L(first_vec_x1)
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+
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+ vmovdqa (VEC_SIZE + 1)(%rdi), %ymm8
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+ VPCMPEQ %ymm8, %ymm0, %ymm1
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+ VPCMPEQ %ymm8, %ymm9, %ymm2
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+ vpor %ymm1, %ymm2, %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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+
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+ vmovdqa (VEC_SIZE * 2 + 1)(%rdi), %ymm8
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+ VPCMPEQ %ymm8, %ymm0, %ymm1
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+ VPCMPEQ %ymm8, %ymm9, %ymm2
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+ vpor %ymm1, %ymm2, %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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+ vmovdqa (VEC_SIZE * 3 + 1)(%rdi), %ymm8
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+ VPCMPEQ %ymm8, %ymm0, %ymm1
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+ VPCMPEQ %ymm8, %ymm9, %ymm2
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+ vpor %ymm1, %ymm2, %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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+ /* Align data to VEC_SIZE * 4 - 1. */
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+ addq $(VEC_SIZE * 4 + 1), %rdi
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+ andq $-(VEC_SIZE * 4), %rdi
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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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- vmovdqa (VEC_SIZE * 4)(%rdi), %ymm5
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- vmovdqa (VEC_SIZE * 5)(%rdi), %ymm6
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- vmovdqa (VEC_SIZE * 6)(%rdi), %ymm7
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- vmovdqa (VEC_SIZE * 7)(%rdi), %ymm8
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+ vmovdqa (%rdi), %ymm5
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+ vmovdqa (VEC_SIZE)(%rdi), %ymm6
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+ vmovdqa (VEC_SIZE * 2)(%rdi), %ymm7
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+ vmovdqa (VEC_SIZE * 3)(%rdi), %ymm8
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/* Leaves only CHARS matching esi as 0. */
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vpxor %ymm5, %ymm0, %ymm1
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@@ -191,63 +202,102 @@ L(loop_4x_vec):
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VPMINU %ymm1, %ymm2, %ymm5
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VPMINU %ymm3, %ymm4, %ymm6
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- VPMINU %ymm5, %ymm6, %ymm5
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+ VPMINU %ymm5, %ymm6, %ymm6
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- VPCMPEQ %ymm5, %ymm9, %ymm5
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- vpmovmskb %ymm5, %eax
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+ VPCMPEQ %ymm6, %ymm9, %ymm6
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+ vpmovmskb %ymm6, %ecx
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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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- addq $(VEC_SIZE * 4), %rdi
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- testl %eax, %eax
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- jz L(loop_4x_vec)
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- VPCMPEQ %ymm1, %ymm9, %ymm1
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+ VPCMPEQ %ymm1, %ymm9, %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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+ jnz L(last_vec_x0)
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+
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- VPCMPEQ %ymm2, %ymm9, %ymm2
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+ VPCMPEQ %ymm5, %ymm9, %ymm2
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vpmovmskb %ymm2, %eax
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testl %eax, %eax
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- jnz L(first_vec_x1)
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+ jnz L(last_vec_x1)
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+
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+ VPCMPEQ %ymm3, %ymm9, %ymm3
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+ vpmovmskb %ymm3, %eax
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+ /* rcx has combined result from all 4 VEC. It will only be used
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+ if the first 3 other VEC all did not contain a match. */
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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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+ subq $(VEC_SIZE * 2), %rdi
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+# ifndef USE_AS_STRCHRNUL
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+ /* Found CHAR or the null byte. */
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+ cmp (%rdi, %rax), %CHAR_REG
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+ jne L(zero_end)
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+# endif
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+ addq %rdi, %rax
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+ VZEROUPPER_RETURN
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+
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+
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+ .p2align 4
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+L(last_vec_x0):
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+ tzcntl %eax, %eax
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+ addq $-(VEC_SIZE * 4), %rdi
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+# ifndef USE_AS_STRCHRNUL
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+ /* Found CHAR or the null byte. */
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+ cmp (%rdi, %rax), %CHAR_REG
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+ jne L(zero_end)
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+# endif
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+ addq %rdi, %rax
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+ VZEROUPPER_RETURN
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- VPCMPEQ %ymm3, %ymm9, %ymm3
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- VPCMPEQ %ymm4, %ymm9, %ymm4
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- vpmovmskb %ymm3, %ecx
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- vpmovmskb %ymm4, %eax
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- salq $32, %rax
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- orq %rcx, %rax
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- tzcntq %rax, %rax
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- leaq (VEC_SIZE * 2)(%rdi, %rax), %rax
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# ifndef USE_AS_STRCHRNUL
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- cmp (%rax), %CHAR_REG
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- cmovne %rdx, %rax
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+L(zero_end):
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+ xorl %eax, %eax
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+ VZEROUPPER_RETURN
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# endif
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- VZEROUPPER
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- ret
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+
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+ .p2align 4
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+L(last_vec_x1):
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+ tzcntl %eax, %eax
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+ subq $(VEC_SIZE * 3), %rdi
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+# ifndef USE_AS_STRCHRNUL
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+ /* Found CHAR or the null byte. */
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+ cmp (%rdi, %rax), %CHAR_REG
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+ jne L(zero_end)
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+# endif
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+ addq %rdi, %rax
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+ VZEROUPPER_RETURN
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+
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/* Cold case for crossing page with first load. */
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.p2align 4
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L(cross_page_boundary):
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- andq $-VEC_SIZE, %rdi
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- andl $(VEC_SIZE - 1), %ecx
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-
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- vmovdqa (%rdi), %ymm8
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- VPCMPEQ %ymm8, %ymm0, %ymm1
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- VPCMPEQ %ymm8, %ymm9, %ymm2
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+ movq %rdi, %rdx
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+ /* Align rdi to VEC_SIZE - 1. */
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+ orq $(VEC_SIZE - 1), %rdi
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+ vmovdqa -(VEC_SIZE - 1)(%rdi), %ymm8
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+ VPCMPEQ %ymm8, %ymm0, %ymm1
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+ VPCMPEQ %ymm8, %ymm9, %ymm2
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vpor %ymm1, %ymm2, %ymm1
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vpmovmskb %ymm1, %eax
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- /* Remove the leading bits. */
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- sarxl %ecx, %eax, %eax
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+ /* Remove the leading bytes. sarxl only uses bits [5:0] of COUNT
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+ so no need to manually mod edx. */
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+ sarxl %edx, %eax, %eax
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testl %eax, %eax
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- jz L(aligned_more)
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+ jz L(cross_page_continue)
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tzcntl %eax, %eax
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- addq %rcx, %rdi
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- addq %rdi, %rax
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# ifndef USE_AS_STRCHRNUL
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- cmp (%rax), %CHAR_REG
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- cmovne %rdx, %rax
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+ xorl %ecx, %ecx
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+ /* Found CHAR or the null byte. */
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+ cmp (%rdx, %rax), %CHAR_REG
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+ leaq (%rdx, %rax), %rax
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+ cmovne %rcx, %rax
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+# else
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+ addq %rdx, %rax
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# endif
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- VZEROUPPER_RETURN
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+L(return_vzeroupper):
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+ ZERO_UPPER_VEC_REGISTERS_RETURN
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END (STRCHR)
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# endif
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--
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GitLab
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