From 1f745ecc2109890886b161d4791e1406fdfc29b8 Mon Sep 17 00:00:00 2001 From: noah Date: Wed, 3 Feb 2021 00:38:59 -0500 Subject: [PATCH 1/2] x86-64: Refactor and improve performance of strchr-avx2.S No bug. Just seemed the performance could be improved a bit. Observed and expected behavior are unchanged. Optimized body of main loop. Updated page cross logic and optimized accordingly. Made a few minor instruction selection modifications. No regressions in test suite. Both test-strchrnul and test-strchr passed. --- sysdeps/x86_64/multiarch/strchr-avx2.S | 225 ++++++++++++------------- sysdeps/x86_64/multiarch/strchr.c | 1 + 2 files changed, 113 insertions(+), 113 deletions(-) diff --git a/sysdeps/x86_64/multiarch/strchr-avx2.S b/sysdeps/x86_64/multiarch/strchr-avx2.S index d416558d04..476c20c289 100644 --- a/sysdeps/x86_64/multiarch/strchr-avx2.S +++ b/sysdeps/x86_64/multiarch/strchr-avx2.S @@ -27,10 +27,12 @@ # ifdef USE_AS_WCSCHR # define VPBROADCAST vpbroadcastd # define VPCMPEQ vpcmpeqd +# define VPMINU vpminud # define CHAR_REG esi # else # define VPBROADCAST vpbroadcastb # define VPCMPEQ vpcmpeqb +# define VPMINU vpminub # define CHAR_REG sil # endif @@ -39,71 +41,54 @@ # endif # define VEC_SIZE 32 +# define PAGE_SIZE 4096 .section .text.avx,"ax",@progbits ENTRY (STRCHR) movl %edi, %ecx - /* Broadcast CHAR to YMM0. */ +# ifndef USE_AS_STRCHRNUL + xorl %edx, %edx +# endif + + /* Broadcast CHAR to YMM0. */ vmovd %esi, %xmm0 vpxor %xmm9, %xmm9, %xmm9 VPBROADCAST %xmm0, %ymm0 - /* Check if we may cross page boundary with one vector load. */ - andl $(2 * VEC_SIZE - 1), %ecx - cmpl $VEC_SIZE, %ecx - ja L(cros_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 - vpor %ymm1, %ymm2, %ymm1 - vpmovmskb %ymm1, %eax - testl %eax, %eax - jnz L(first_vec_x0) - - /* Align data for aligned loads in the loop. */ - addq $VEC_SIZE, %rdi - andl $(VEC_SIZE - 1), %ecx - andq $-VEC_SIZE, %rdi - jmp L(more_4x_vec) + /* 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) - .p2align 4 -L(cros_page_boundary): - andl $(VEC_SIZE - 1), %ecx - andq $-VEC_SIZE, %rdi + /* 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 vpor %ymm1, %ymm2, %ymm1 vpmovmskb %ymm1, %eax - /* Remove the leading bytes. */ - sarl %cl, %eax testl %eax, %eax - jz L(aligned_more) - /* Found CHAR or the null byte. */ + jz L(more_vecs) tzcntl %eax, %eax - addq %rcx, %rax -# ifdef USE_AS_STRCHRNUL + /* Found CHAR or the null byte. */ addq %rdi, %rax -# else - xorl %edx, %edx - leaq (%rdi, %rax), %rax - cmp (%rax), %CHAR_REG +# ifndef USE_AS_STRCHRNUL + cmp (%rax), %CHAR_REG cmovne %rdx, %rax # endif VZEROUPPER ret .p2align 4 +L(more_vecs): + /* Align data for aligned loads in the loop. */ + andq $-VEC_SIZE, %rdi L(aligned_more): - addq $VEC_SIZE, %rdi -L(more_4x_vec): - /* Check the first 4 * VEC_SIZE. Only one VEC_SIZE at a time - since data is only aligned to VEC_SIZE. */ - vmovdqa (%rdi), %ymm8 + /* 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 @@ -133,61 +118,24 @@ L(more_4x_vec): vpor %ymm1, %ymm2, %ymm1 vpmovmskb %ymm1, %eax testl %eax, %eax - jnz L(first_vec_x3) - - addq $(VEC_SIZE * 4), %rdi - - /* Align data to 4 * VEC_SIZE. */ - movq %rdi, %rcx - andl $(4 * VEC_SIZE - 1), %ecx - andq $-(4 * VEC_SIZE), %rdi - - .p2align 4 -L(loop_4x_vec): - /* Compare 4 * VEC at a time forward. */ - vmovdqa (%rdi), %ymm5 - vmovdqa VEC_SIZE(%rdi), %ymm6 - vmovdqa (VEC_SIZE * 2)(%rdi), %ymm7 - vmovdqa (VEC_SIZE * 3)(%rdi), %ymm8 - - VPCMPEQ %ymm5, %ymm0, %ymm1 - VPCMPEQ %ymm6, %ymm0, %ymm2 - VPCMPEQ %ymm7, %ymm0, %ymm3 - VPCMPEQ %ymm8, %ymm0, %ymm4 + jz L(prep_loop_4x) - VPCMPEQ %ymm5, %ymm9, %ymm5 - VPCMPEQ %ymm6, %ymm9, %ymm6 - VPCMPEQ %ymm7, %ymm9, %ymm7 - VPCMPEQ %ymm8, %ymm9, %ymm8 - - vpor %ymm1, %ymm5, %ymm1 - vpor %ymm2, %ymm6, %ymm2 - vpor %ymm3, %ymm7, %ymm3 - vpor %ymm4, %ymm8, %ymm4 - - vpor %ymm1, %ymm2, %ymm5 - vpor %ymm3, %ymm4, %ymm6 - - vpor %ymm5, %ymm6, %ymm5 - - vpmovmskb %ymm5, %eax - testl %eax, %eax - jnz L(4x_vec_end) - - addq $(VEC_SIZE * 4), %rdi - - jmp L(loop_4x_vec) + tzcntl %eax, %eax + leaq (VEC_SIZE * 3)(%rdi, %rax), %rax +# ifndef USE_AS_STRCHRNUL + cmp (%rax), %CHAR_REG + cmovne %rdx, %rax +# endif + VZEROUPPER + ret .p2align 4 L(first_vec_x0): - /* Found CHAR or the null byte. */ tzcntl %eax, %eax -# ifdef USE_AS_STRCHRNUL + /* Found CHAR or the null byte. */ addq %rdi, %rax -# else - xorl %edx, %edx - leaq (%rdi, %rax), %rax - cmp (%rax), %CHAR_REG +# ifndef USE_AS_STRCHRNUL + cmp (%rax), %CHAR_REG cmovne %rdx, %rax # endif VZEROUPPER @@ -196,13 +144,9 @@ L(first_vec_x0): .p2align 4 L(first_vec_x1): tzcntl %eax, %eax -# ifdef USE_AS_STRCHRNUL - addq $VEC_SIZE, %rax - addq %rdi, %rax -# else - xorl %edx, %edx leaq VEC_SIZE(%rdi, %rax), %rax - cmp (%rax), %CHAR_REG +# ifndef USE_AS_STRCHRNUL + cmp (%rax), %CHAR_REG cmovne %rdx, %rax # endif VZEROUPPER @@ -211,44 +155,99 @@ L(first_vec_x1): .p2align 4 L(first_vec_x2): tzcntl %eax, %eax -# ifdef USE_AS_STRCHRNUL - addq $(VEC_SIZE * 2), %rax - addq %rdi, %rax -# else - xorl %edx, %edx + /* Found CHAR or the null byte. */ leaq (VEC_SIZE * 2)(%rdi, %rax), %rax - cmp (%rax), %CHAR_REG +# ifndef USE_AS_STRCHRNUL + cmp (%rax), %CHAR_REG cmovne %rdx, %rax # endif VZEROUPPER ret +L(prep_loop_4x): + /* Align data to 4 * VEC_SIZE. */ + andq $-(VEC_SIZE * 4), %rdi + .p2align 4 -L(4x_vec_end): +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 + + /* Leaves only CHARS matching esi as 0. */ + vpxor %ymm5, %ymm0, %ymm1 + vpxor %ymm6, %ymm0, %ymm2 + vpxor %ymm7, %ymm0, %ymm3 + vpxor %ymm8, %ymm0, %ymm4 + + VPMINU %ymm1, %ymm5, %ymm1 + VPMINU %ymm2, %ymm6, %ymm2 + VPMINU %ymm3, %ymm7, %ymm3 + VPMINU %ymm4, %ymm8, %ymm4 + + VPMINU %ymm1, %ymm2, %ymm5 + VPMINU %ymm3, %ymm4, %ymm6 + + VPMINU %ymm5, %ymm6, %ymm5 + + VPCMPEQ %ymm5, %ymm9, %ymm5 + vpmovmskb %ymm5, %eax + + addq $(VEC_SIZE * 4), %rdi + testl %eax, %eax + jz L(loop_4x_vec) + + VPCMPEQ %ymm1, %ymm9, %ymm1 vpmovmskb %ymm1, %eax testl %eax, %eax jnz L(first_vec_x0) + + VPCMPEQ %ymm2, %ymm9, %ymm2 vpmovmskb %ymm2, %eax testl %eax, %eax jnz L(first_vec_x1) - vpmovmskb %ymm3, %eax - testl %eax, %eax - jnz L(first_vec_x2) + + 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 +# endif + VZEROUPPER + ret + + /* 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 + vpor %ymm1, %ymm2, %ymm1 + vpmovmskb %ymm1, %eax + /* Remove the leading bits. */ + sarxl %ecx, %eax, %eax testl %eax, %eax -L(first_vec_x3): + jz L(aligned_more) tzcntl %eax, %eax -# ifdef USE_AS_STRCHRNUL - addq $(VEC_SIZE * 3), %rax + addq %rcx, %rdi addq %rdi, %rax -# else - xorl %edx, %edx - leaq (VEC_SIZE * 3)(%rdi, %rax), %rax - cmp (%rax), %CHAR_REG +# ifndef USE_AS_STRCHRNUL + cmp (%rax), %CHAR_REG cmovne %rdx, %rax # endif VZEROUPPER ret END (STRCHR) -#endif +# endif diff --git a/sysdeps/x86_64/multiarch/strchr.c b/sysdeps/x86_64/multiarch/strchr.c index 583a152794..4dfbe3b58b 100644 --- a/sysdeps/x86_64/multiarch/strchr.c +++ b/sysdeps/x86_64/multiarch/strchr.c @@ -37,6 +37,7 @@ IFUNC_SELECTOR (void) if (!CPU_FEATURES_ARCH_P (cpu_features, Prefer_No_VZEROUPPER) && CPU_FEATURE_USABLE_P (cpu_features, AVX2) + && CPU_FEATURE_USABLE_P (cpu_features, BMI2) && CPU_FEATURES_ARCH_P (cpu_features, AVX_Fast_Unaligned_Load)) return OPTIMIZE (avx2); -- 2.29.2