From ccabe7971f508709d034b63b8672f6f751a3d356 Mon Sep 17 00:00:00 2001 From: Noah Goldstein Date: Fri, 23 Apr 2021 15:56:24 -0400 Subject: [PATCH] x86: Optimize strchr-avx2.S Content-type: text/plain; charset=UTF-8 No bug. This commit optimizes strchr-avx2.S. The optimizations are all small things such as save an ALU in the alignment process, saving a few instructions in the loop return, saving some bytes in the main loop, and increasing the ILP in the return cases. test-strchr, test-strchrnul, test-wcschr, and test-wcschrnul are all passing. Signed-off-by: Noah Goldstein --- sysdeps/x86_64/multiarch/strchr-avx2.S | 290 +++++++++++++++---------- 1 file changed, 170 insertions(+), 120 deletions(-) Conflics: sysdeps/x86_64/multiarch/strchr-avx2.S (rearranged to account for branch changes) diff --git a/sysdeps/x86_64/multiarch/strchr-avx2.S b/sysdeps/x86_64/multiarch/strchr-avx2.S index 919d256c..5884726b 100644 --- a/sysdeps/x86_64/multiarch/strchr-avx2.S +++ b/sysdeps/x86_64/multiarch/strchr-avx2.S @@ -49,133 +49,144 @@ .section SECTION(.text),"ax",@progbits ENTRY (STRCHR) - movl %edi, %ecx -# ifndef USE_AS_STRCHRNUL - xorl %edx, %edx -# endif - /* Broadcast CHAR to YMM0. */ vmovd %esi, %xmm0 + movl %edi, %eax + andl $(PAGE_SIZE - 1), %eax + VPBROADCAST %xmm0, %ymm0 vpxor %xmm9, %xmm9, %xmm9 - VPBROADCAST %xmm0, %ymm0 /* Check if we cross page boundary with one vector load. */ - andl $(PAGE_SIZE - 1), %ecx - cmpl $(PAGE_SIZE - VEC_SIZE), %ecx - ja L(cross_page_boundary) + cmpl $(PAGE_SIZE - VEC_SIZE), %eax + ja L(cross_page_boundary) /* Check the first VEC_SIZE bytes. Search for both CHAR and the null byte. */ vmovdqu (%rdi), %ymm8 - VPCMPEQ %ymm8, %ymm0, %ymm1 - VPCMPEQ %ymm8, %ymm9, %ymm2 + VPCMPEQ %ymm8, %ymm0, %ymm1 + VPCMPEQ %ymm8, %ymm9, %ymm2 vpor %ymm1, %ymm2, %ymm1 vpmovmskb %ymm1, %eax testl %eax, %eax - jz L(more_vecs) + jz L(aligned_more) tzcntl %eax, %eax +# ifndef USE_AS_STRCHRNUL /* Found CHAR or the null byte. */ + cmp (%rdi, %rax), %CHAR_REG + jne L(zero) +# endif addq %rdi, %rax + VZEROUPPER_RETURN + + /* .p2align 5 helps keep performance more consistent if ENTRY() + alignment % 32 was either 16 or 0. As well this makes the + alignment % 32 of the loop_4x_vec fixed which makes tuning it + easier. */ + .p2align 5 +L(first_vec_x4): + tzcntl %eax, %eax + addq $(VEC_SIZE * 3 + 1), %rdi # ifndef USE_AS_STRCHRNUL - cmp (%rax), %CHAR_REG - cmovne %rdx, %rax + /* Found CHAR or the null byte. */ + cmp (%rdi, %rax), %CHAR_REG + jne L(zero) # endif -L(return_vzeroupper): - ZERO_UPPER_VEC_REGISTERS_RETURN - - .p2align 4 -L(more_vecs): - /* Align data for aligned loads in the loop. */ - andq $-VEC_SIZE, %rdi -L(aligned_more): - - /* Check the next 4 * VEC_SIZE. Only one VEC_SIZE at a time - since data is only aligned to VEC_SIZE. */ - vmovdqa VEC_SIZE(%rdi), %ymm8 - addq $VEC_SIZE, %rdi - VPCMPEQ %ymm8, %ymm0, %ymm1 - VPCMPEQ %ymm8, %ymm9, %ymm2 - vpor %ymm1, %ymm2, %ymm1 - vpmovmskb %ymm1, %eax - testl %eax, %eax - jnz L(first_vec_x0) - - vmovdqa VEC_SIZE(%rdi), %ymm8 - VPCMPEQ %ymm8, %ymm0, %ymm1 - VPCMPEQ %ymm8, %ymm9, %ymm2 - vpor %ymm1, %ymm2, %ymm1 - vpmovmskb %ymm1, %eax - testl %eax, %eax - jnz L(first_vec_x1) - - vmovdqa (VEC_SIZE * 2)(%rdi), %ymm8 - VPCMPEQ %ymm8, %ymm0, %ymm1 - VPCMPEQ %ymm8, %ymm9, %ymm2 - vpor %ymm1, %ymm2, %ymm1 - vpmovmskb %ymm1, %eax - testl %eax, %eax - jnz L(first_vec_x2) - - vmovdqa (VEC_SIZE * 3)(%rdi), %ymm8 - VPCMPEQ %ymm8, %ymm0, %ymm1 - VPCMPEQ %ymm8, %ymm9, %ymm2 - vpor %ymm1, %ymm2, %ymm1 - vpmovmskb %ymm1, %eax - testl %eax, %eax - jz L(prep_loop_4x) + addq %rdi, %rax + VZEROUPPER_RETURN - tzcntl %eax, %eax - leaq (VEC_SIZE * 3)(%rdi, %rax), %rax # ifndef USE_AS_STRCHRNUL - cmp (%rax), %CHAR_REG - cmovne %rdx, %rax +L(zero): + xorl %eax, %eax + VZEROUPPER_RETURN # endif - VZEROUPPER - ret + .p2align 4 -L(first_vec_x0): +L(first_vec_x1): tzcntl %eax, %eax - /* Found CHAR or the null byte. */ - addq %rdi, %rax + incq %rdi # ifndef USE_AS_STRCHRNUL - cmp (%rax), %CHAR_REG - cmovne %rdx, %rax + /* Found CHAR or the null byte. */ + cmp (%rdi, %rax), %CHAR_REG + jne L(zero) # endif + addq %rdi, %rax VZEROUPPER_RETURN .p2align 4 -L(first_vec_x1): +L(first_vec_x2): tzcntl %eax, %eax - leaq VEC_SIZE(%rdi, %rax), %rax + addq $(VEC_SIZE + 1), %rdi # ifndef USE_AS_STRCHRNUL - cmp (%rax), %CHAR_REG - cmovne %rdx, %rax + /* Found CHAR or the null byte. */ + cmp (%rdi, %rax), %CHAR_REG + jne L(zero) # endif + addq %rdi, %rax VZEROUPPER_RETURN .p2align 4 -L(first_vec_x2): +L(first_vec_x3): tzcntl %eax, %eax - /* Found CHAR or the null byte. */ - leaq (VEC_SIZE * 2)(%rdi, %rax), %rax + addq $(VEC_SIZE * 2 + 1), %rdi # ifndef USE_AS_STRCHRNUL - cmp (%rax), %CHAR_REG - cmovne %rdx, %rax + /* Found CHAR or the null byte. */ + cmp (%rdi, %rax), %CHAR_REG + jne L(zero) # endif + addq %rdi, %rax VZEROUPPER_RETURN -L(prep_loop_4x): - /* Align data to 4 * VEC_SIZE. */ - andq $-(VEC_SIZE * 4), %rdi + .p2align 4 +L(aligned_more): + /* Align data to VEC_SIZE - 1. This is the same number of + instructions as using andq -VEC_SIZE but saves 4 bytes of code + on x4 check. */ + orq $(VEC_SIZE - 1), %rdi +L(cross_page_continue): + /* Check the next 4 * VEC_SIZE. Only one VEC_SIZE at a time + since data is only aligned to VEC_SIZE. */ + vmovdqa 1(%rdi), %ymm8 + VPCMPEQ %ymm8, %ymm0, %ymm1 + VPCMPEQ %ymm8, %ymm9, %ymm2 + vpor %ymm1, %ymm2, %ymm1 + vpmovmskb %ymm1, %eax + testl %eax, %eax + jnz L(first_vec_x1) + + vmovdqa (VEC_SIZE + 1)(%rdi), %ymm8 + VPCMPEQ %ymm8, %ymm0, %ymm1 + VPCMPEQ %ymm8, %ymm9, %ymm2 + vpor %ymm1, %ymm2, %ymm1 + vpmovmskb %ymm1, %eax + testl %eax, %eax + jnz L(first_vec_x2) + + vmovdqa (VEC_SIZE * 2 + 1)(%rdi), %ymm8 + VPCMPEQ %ymm8, %ymm0, %ymm1 + VPCMPEQ %ymm8, %ymm9, %ymm2 + vpor %ymm1, %ymm2, %ymm1 + vpmovmskb %ymm1, %eax + testl %eax, %eax + jnz L(first_vec_x3) + vmovdqa (VEC_SIZE * 3 + 1)(%rdi), %ymm8 + VPCMPEQ %ymm8, %ymm0, %ymm1 + VPCMPEQ %ymm8, %ymm9, %ymm2 + vpor %ymm1, %ymm2, %ymm1 + vpmovmskb %ymm1, %eax + testl %eax, %eax + jnz L(first_vec_x4) + /* Align data to VEC_SIZE * 4 - 1. */ + addq $(VEC_SIZE * 4 + 1), %rdi + andq $-(VEC_SIZE * 4), %rdi .p2align 4 L(loop_4x_vec): /* Compare 4 * VEC at a time forward. */ - vmovdqa (VEC_SIZE * 4)(%rdi), %ymm5 - vmovdqa (VEC_SIZE * 5)(%rdi), %ymm6 - vmovdqa (VEC_SIZE * 6)(%rdi), %ymm7 - vmovdqa (VEC_SIZE * 7)(%rdi), %ymm8 + vmovdqa (%rdi), %ymm5 + vmovdqa (VEC_SIZE)(%rdi), %ymm6 + vmovdqa (VEC_SIZE * 2)(%rdi), %ymm7 + vmovdqa (VEC_SIZE * 3)(%rdi), %ymm8 /* Leaves only CHARS matching esi as 0. */ vpxor %ymm5, %ymm0, %ymm1 @@ -191,63 +202,102 @@ L(loop_4x_vec): VPMINU %ymm1, %ymm2, %ymm5 VPMINU %ymm3, %ymm4, %ymm6 - VPMINU %ymm5, %ymm6, %ymm5 + VPMINU %ymm5, %ymm6, %ymm6 - VPCMPEQ %ymm5, %ymm9, %ymm5 - vpmovmskb %ymm5, %eax + VPCMPEQ %ymm6, %ymm9, %ymm6 + vpmovmskb %ymm6, %ecx + subq $-(VEC_SIZE * 4), %rdi + testl %ecx, %ecx + jz L(loop_4x_vec) - addq $(VEC_SIZE * 4), %rdi - testl %eax, %eax - jz L(loop_4x_vec) - VPCMPEQ %ymm1, %ymm9, %ymm1 + VPCMPEQ %ymm1, %ymm9, %ymm1 vpmovmskb %ymm1, %eax testl %eax, %eax - jnz L(first_vec_x0) + jnz L(last_vec_x0) + - VPCMPEQ %ymm2, %ymm9, %ymm2 + VPCMPEQ %ymm5, %ymm9, %ymm2 vpmovmskb %ymm2, %eax testl %eax, %eax - jnz L(first_vec_x1) + jnz L(last_vec_x1) + + VPCMPEQ %ymm3, %ymm9, %ymm3 + vpmovmskb %ymm3, %eax + /* rcx has combined result from all 4 VEC. It will only be used + if the first 3 other VEC all did not contain a match. */ + salq $32, %rcx + orq %rcx, %rax + tzcntq %rax, %rax + subq $(VEC_SIZE * 2), %rdi +# ifndef USE_AS_STRCHRNUL + /* Found CHAR or the null byte. */ + cmp (%rdi, %rax), %CHAR_REG + jne L(zero_end) +# endif + addq %rdi, %rax + VZEROUPPER_RETURN + + + .p2align 4 +L(last_vec_x0): + tzcntl %eax, %eax + addq $-(VEC_SIZE * 4), %rdi +# ifndef USE_AS_STRCHRNUL + /* Found CHAR or the null byte. */ + cmp (%rdi, %rax), %CHAR_REG + jne L(zero_end) +# endif + addq %rdi, %rax + VZEROUPPER_RETURN - VPCMPEQ %ymm3, %ymm9, %ymm3 - VPCMPEQ %ymm4, %ymm9, %ymm4 - vpmovmskb %ymm3, %ecx - vpmovmskb %ymm4, %eax - salq $32, %rax - orq %rcx, %rax - tzcntq %rax, %rax - leaq (VEC_SIZE * 2)(%rdi, %rax), %rax # ifndef USE_AS_STRCHRNUL - cmp (%rax), %CHAR_REG - cmovne %rdx, %rax +L(zero_end): + xorl %eax, %eax + VZEROUPPER_RETURN # endif - VZEROUPPER - ret + + .p2align 4 +L(last_vec_x1): + tzcntl %eax, %eax + subq $(VEC_SIZE * 3), %rdi +# ifndef USE_AS_STRCHRNUL + /* Found CHAR or the null byte. */ + cmp (%rdi, %rax), %CHAR_REG + jne L(zero_end) +# endif + addq %rdi, %rax + VZEROUPPER_RETURN + /* Cold case for crossing page with first load. */ .p2align 4 L(cross_page_boundary): - andq $-VEC_SIZE, %rdi - andl $(VEC_SIZE - 1), %ecx - - vmovdqa (%rdi), %ymm8 - VPCMPEQ %ymm8, %ymm0, %ymm1 - VPCMPEQ %ymm8, %ymm9, %ymm2 + movq %rdi, %rdx + /* Align rdi to VEC_SIZE - 1. */ + orq $(VEC_SIZE - 1), %rdi + vmovdqa -(VEC_SIZE - 1)(%rdi), %ymm8 + VPCMPEQ %ymm8, %ymm0, %ymm1 + VPCMPEQ %ymm8, %ymm9, %ymm2 vpor %ymm1, %ymm2, %ymm1 vpmovmskb %ymm1, %eax - /* Remove the leading bits. */ - sarxl %ecx, %eax, %eax + /* Remove the leading bytes. sarxl only uses bits [5:0] of COUNT + so no need to manually mod edx. */ + sarxl %edx, %eax, %eax testl %eax, %eax - jz L(aligned_more) + jz L(cross_page_continue) tzcntl %eax, %eax - addq %rcx, %rdi - addq %rdi, %rax # ifndef USE_AS_STRCHRNUL - cmp (%rax), %CHAR_REG - cmovne %rdx, %rax + xorl %ecx, %ecx + /* Found CHAR or the null byte. */ + cmp (%rdx, %rax), %CHAR_REG + leaq (%rdx, %rax), %rax + cmovne %rcx, %rax +# else + addq %rdx, %rax # endif - VZEROUPPER_RETURN +L(return_vzeroupper): + ZERO_UPPER_VEC_REGISTERS_RETURN END (STRCHR) # endif -- GitLab