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author | Noah Goldstein <goldstein.w.n@gmail.com> | 2022-04-21 20:52:30 -0500 |
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committer | Noah Goldstein <goldstein.w.n@gmail.com> | 2022-04-22 23:08:43 -0500 |
commit | c966099cdc3e0fdf92f63eac09b22fa7e5f5f02d (patch) | |
tree | 6cc2471be9d9eeff2ab39aa69f716ab4023b7b0d | |
parent | df7e295d18ffa34f629578c0017a9881af7620f6 (diff) | |
download | glibc-c966099cdc3e0fdf92f63eac09b22fa7e5f5f02d.zip glibc-c966099cdc3e0fdf92f63eac09b22fa7e5f5f02d.tar.gz glibc-c966099cdc3e0fdf92f63eac09b22fa7e5f5f02d.tar.bz2 |
x86: Optimize {str|wcs}rchr-evex
The new code unrolls the main loop slightly without adding too much
overhead and minimizes the comparisons for the search CHAR.
Geometric Mean of all benchmarks New / Old: 0.755
See email for all results.
Full xcheck passes on x86_64 with and without multiarch enabled.
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
-rw-r--r-- | sysdeps/x86_64/multiarch/strrchr-evex.S | 471 |
1 files changed, 290 insertions, 181 deletions
diff --git a/sysdeps/x86_64/multiarch/strrchr-evex.S b/sysdeps/x86_64/multiarch/strrchr-evex.S index adeddae..8014c28 100644 --- a/sysdeps/x86_64/multiarch/strrchr-evex.S +++ b/sysdeps/x86_64/multiarch/strrchr-evex.S @@ -24,242 +24,351 @@ # define STRRCHR __strrchr_evex # endif -# define VMOVU vmovdqu64 -# define VMOVA vmovdqa64 +# define VMOVU vmovdqu64 +# define VMOVA vmovdqa64 # ifdef USE_AS_WCSRCHR +# define SHIFT_REG esi + +# define kunpck kunpckbw +# define kmov_2x kmovd +# define maskz_2x ecx +# define maskm_2x eax +# define CHAR_SIZE 4 +# define VPMIN vpminud +# define VPTESTN vptestnmd # define VPBROADCAST vpbroadcastd -# define VPCMP vpcmpd -# define SHIFT_REG r8d +# define VPCMP vpcmpd # else +# define SHIFT_REG edi + +# define kunpck kunpckdq +# define kmov_2x kmovq +# define maskz_2x rcx +# define maskm_2x rax + +# define CHAR_SIZE 1 +# define VPMIN vpminub +# define VPTESTN vptestnmb # define VPBROADCAST vpbroadcastb -# define VPCMP vpcmpb -# define SHIFT_REG ecx +# define VPCMP vpcmpb # endif # define XMMZERO xmm16 # define YMMZERO ymm16 # define YMMMATCH ymm17 -# define YMM1 ymm18 +# define YMMSAVE ymm18 + +# define YMM1 ymm19 +# define YMM2 ymm20 +# define YMM3 ymm21 +# define YMM4 ymm22 +# define YMM5 ymm23 +# define YMM6 ymm24 +# define YMM7 ymm25 +# define YMM8 ymm26 -# define VEC_SIZE 32 - .section .text.evex,"ax",@progbits -ENTRY (STRRCHR) - movl %edi, %ecx +# define VEC_SIZE 32 +# define PAGE_SIZE 4096 + .section .text.evex, "ax", @progbits +ENTRY(STRRCHR) + movl %edi, %eax /* Broadcast CHAR to YMMMATCH. */ VPBROADCAST %esi, %YMMMATCH - vpxorq %XMMZERO, %XMMZERO, %XMMZERO - - /* 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) + andl $(PAGE_SIZE - 1), %eax + cmpl $(PAGE_SIZE - VEC_SIZE), %eax + jg L(cross_page_boundary) +L(page_cross_continue): VMOVU (%rdi), %YMM1 - - /* Each bit in K0 represents a null byte in YMM1. */ - VPCMP $0, %YMMZERO, %YMM1, %k0 - /* Each bit in K1 represents a CHAR in YMM1. */ - VPCMP $0, %YMMMATCH, %YMM1, %k1 + /* k0 has a 1 for each zero CHAR in YMM1. */ + VPTESTN %YMM1, %YMM1, %k0 kmovd %k0, %ecx - kmovd %k1, %eax - - addq $VEC_SIZE, %rdi - - testl %eax, %eax - jnz L(first_vec) - testl %ecx, %ecx - jnz L(return_null) - - andq $-VEC_SIZE, %rdi - xorl %edx, %edx - jmp L(aligned_loop) - - .p2align 4 -L(first_vec): - /* Check if there is a null byte. */ - testl %ecx, %ecx - jnz L(char_and_nul_in_first_vec) - - /* Remember the match and keep searching. */ - movl %eax, %edx - movq %rdi, %rsi - andq $-VEC_SIZE, %rdi - jmp L(aligned_loop) - - .p2align 4 -L(cros_page_boundary): - andl $(VEC_SIZE - 1), %ecx - andq $-VEC_SIZE, %rdi + jz L(aligned_more) + /* fallthrough: zero CHAR in first VEC. */ + /* K1 has a 1 for each search CHAR match in YMM1. */ + VPCMP $0, %YMMMATCH, %YMM1, %k1 + kmovd %k1, %eax + /* Build mask up until first zero CHAR (used to mask of + potential search CHAR matches past the end of the string). + */ + blsmskl %ecx, %ecx + andl %ecx, %eax + jz L(ret0) + /* Get last match (the `andl` removed any out of bounds + matches). */ + bsrl %eax, %eax # ifdef USE_AS_WCSRCHR - /* NB: Divide shift count by 4 since each bit in K1 represent 4 - bytes. */ - movl %ecx, %SHIFT_REG - sarl $2, %SHIFT_REG + leaq (%rdi, %rax, CHAR_SIZE), %rax +# else + addq %rdi, %rax # endif +L(ret0): + ret - VMOVA (%rdi), %YMM1 - - /* Each bit in K0 represents a null byte in YMM1. */ - VPCMP $0, %YMMZERO, %YMM1, %k0 - /* Each bit in K1 represents a CHAR in YMM1. */ + /* Returns for first vec x1/x2/x3 have hard coded backward + search path for earlier matches. */ + .p2align 4,, 6 +L(first_vec_x1): + VPCMP $0, %YMMMATCH, %YMM2, %k1 + kmovd %k1, %eax + blsmskl %ecx, %ecx + /* eax non-zero if search CHAR in range. */ + andl %ecx, %eax + jnz L(first_vec_x1_return) + + /* fallthrough: no match in YMM2 then need to check for earlier + matches (in YMM1). */ + .p2align 4,, 4 +L(first_vec_x0_test): VPCMP $0, %YMMMATCH, %YMM1, %k1 - kmovd %k0, %edx kmovd %k1, %eax - - shrxl %SHIFT_REG, %edx, %edx - shrxl %SHIFT_REG, %eax, %eax - addq $VEC_SIZE, %rdi - - /* Check if there is a CHAR. */ testl %eax, %eax - jnz L(found_char) - - testl %edx, %edx - jnz L(return_null) - - jmp L(aligned_loop) - - .p2align 4 -L(found_char): - testl %edx, %edx - jnz L(char_and_nul) - - /* Remember the match and keep searching. */ - movl %eax, %edx - leaq (%rdi, %rcx), %rsi + jz L(ret1) + bsrl %eax, %eax +# ifdef USE_AS_WCSRCHR + leaq (%rsi, %rax, CHAR_SIZE), %rax +# else + addq %rsi, %rax +# endif +L(ret1): + ret - .p2align 4 -L(aligned_loop): - VMOVA (%rdi), %YMM1 - addq $VEC_SIZE, %rdi + .p2align 4,, 10 +L(first_vec_x1_or_x2): + VPCMP $0, %YMM3, %YMMMATCH, %k3 + VPCMP $0, %YMM2, %YMMMATCH, %k2 + /* K2 and K3 have 1 for any search CHAR match. Test if any + matches between either of them. Otherwise check YMM1. */ + kortestd %k2, %k3 + jz L(first_vec_x0_test) + + /* Guranteed that YMM2 and YMM3 are within range so merge the + two bitmasks then get last result. */ + kunpck %k2, %k3, %k3 + kmovq %k3, %rax + bsrq %rax, %rax + leaq (VEC_SIZE)(%r8, %rax, CHAR_SIZE), %rax + ret - /* Each bit in K0 represents a null byte in YMM1. */ - VPCMP $0, %YMMZERO, %YMM1, %k0 - /* Each bit in K1 represents a CHAR in YMM1. */ - VPCMP $0, %YMMMATCH, %YMM1, %k1 - kmovd %k0, %ecx + .p2align 4,, 6 +L(first_vec_x3): + VPCMP $0, %YMMMATCH, %YMM4, %k1 kmovd %k1, %eax - orl %eax, %ecx - jnz L(char_nor_null) + blsmskl %ecx, %ecx + /* If no search CHAR match in range check YMM1/YMM2/YMM3. */ + andl %ecx, %eax + jz L(first_vec_x1_or_x2) + bsrl %eax, %eax + leaq (VEC_SIZE * 3)(%rdi, %rax, CHAR_SIZE), %rax + ret - VMOVA (%rdi), %YMM1 - add $VEC_SIZE, %rdi + .p2align 4,, 6 +L(first_vec_x0_x1_test): + VPCMP $0, %YMMMATCH, %YMM2, %k1 + kmovd %k1, %eax + /* Check YMM2 for last match first. If no match try YMM1. */ + testl %eax, %eax + jz L(first_vec_x0_test) + .p2align 4,, 4 +L(first_vec_x1_return): + bsrl %eax, %eax + leaq (VEC_SIZE)(%rdi, %rax, CHAR_SIZE), %rax + ret - /* Each bit in K0 represents a null byte in YMM1. */ - VPCMP $0, %YMMZERO, %YMM1, %k0 - /* Each bit in K1 represents a CHAR in YMM1. */ - VPCMP $0, %YMMMATCH, %YMM1, %k1 - kmovd %k0, %ecx + .p2align 4,, 10 +L(first_vec_x2): + VPCMP $0, %YMMMATCH, %YMM3, %k1 kmovd %k1, %eax - orl %eax, %ecx - jnz L(char_nor_null) + blsmskl %ecx, %ecx + /* Check YMM3 for last match first. If no match try YMM2/YMM1. + */ + andl %ecx, %eax + jz L(first_vec_x0_x1_test) + bsrl %eax, %eax + leaq (VEC_SIZE * 2)(%rdi, %rax, CHAR_SIZE), %rax + ret - VMOVA (%rdi), %YMM1 - addq $VEC_SIZE, %rdi - /* Each bit in K0 represents a null byte in YMM1. */ - VPCMP $0, %YMMZERO, %YMM1, %k0 - /* Each bit in K1 represents a CHAR in YMM1. */ - VPCMP $0, %YMMMATCH, %YMM1, %k1 + .p2align 4 +L(aligned_more): + /* Need to keep original pointer incase YMM1 has last match. */ + movq %rdi, %rsi + andq $-VEC_SIZE, %rdi + VMOVU VEC_SIZE(%rdi), %YMM2 + VPTESTN %YMM2, %YMM2, %k0 kmovd %k0, %ecx - kmovd %k1, %eax - orl %eax, %ecx - jnz L(char_nor_null) + testl %ecx, %ecx + jnz L(first_vec_x1) - VMOVA (%rdi), %YMM1 - addq $VEC_SIZE, %rdi + VMOVU (VEC_SIZE * 2)(%rdi), %YMM3 + VPTESTN %YMM3, %YMM3, %k0 + kmovd %k0, %ecx + testl %ecx, %ecx + jnz L(first_vec_x2) - /* Each bit in K0 represents a null byte in YMM1. */ - VPCMP $0, %YMMZERO, %YMM1, %k0 - /* Each bit in K1 represents a CHAR in YMM1. */ - VPCMP $0, %YMMMATCH, %YMM1, %k1 + VMOVU (VEC_SIZE * 3)(%rdi), %YMM4 + VPTESTN %YMM4, %YMM4, %k0 kmovd %k0, %ecx - kmovd %k1, %eax - orl %eax, %ecx - jz L(aligned_loop) + movq %rdi, %r8 + testl %ecx, %ecx + jnz L(first_vec_x3) + andq $-(VEC_SIZE * 2), %rdi .p2align 4 -L(char_nor_null): - /* Find a CHAR or a null byte in a loop. */ +L(first_aligned_loop): + /* Preserve YMM1, YMM2, YMM3, and YMM4 until we can gurantee + they don't store a match. */ + VMOVA (VEC_SIZE * 4)(%rdi), %YMM5 + VMOVA (VEC_SIZE * 5)(%rdi), %YMM6 + + VPCMP $0, %YMM5, %YMMMATCH, %k2 + vpxord %YMM6, %YMMMATCH, %YMM7 + + VPMIN %YMM5, %YMM6, %YMM8 + VPMIN %YMM8, %YMM7, %YMM7 + + VPTESTN %YMM7, %YMM7, %k1 + subq $(VEC_SIZE * -2), %rdi + kortestd %k1, %k2 + jz L(first_aligned_loop) + + VPCMP $0, %YMM6, %YMMMATCH, %k3 + VPTESTN %YMM8, %YMM8, %k1 + ktestd %k1, %k1 + jz L(second_aligned_loop_prep) + + kortestd %k2, %k3 + jnz L(return_first_aligned_loop) + + .p2align 4,, 6 +L(first_vec_x1_or_x2_or_x3): + VPCMP $0, %YMM4, %YMMMATCH, %k4 + kmovd %k4, %eax testl %eax, %eax - jnz L(match) -L(return_value): - testl %edx, %edx - jz L(return_null) - movl %edx, %eax - movq %rsi, %rdi + jz L(first_vec_x1_or_x2) 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 -# else - leaq -VEC_SIZE(%rdi, %rax), %rax -# endif + leaq (VEC_SIZE * 3)(%r8, %rax, CHAR_SIZE), %rax ret - .p2align 4 -L(match): - /* Find a CHAR. Check if there is a null byte. */ - kmovd %k0, %ecx - testl %ecx, %ecx - jnz L(find_nul) + .p2align 4,, 8 +L(return_first_aligned_loop): + VPTESTN %YMM5, %YMM5, %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(first_vec_x1_or_x2_or_x3) - /* Remember the match and keep searching. */ - movl %eax, %edx + bsr %maskm_2x, %maskm_2x + leaq (VEC_SIZE * 2)(%rdi, %rax, CHAR_SIZE), %rax + ret + + .p2align 4 + /* We can throw away the work done for the first 4x checks here + as we have a later match. This is the 'fast' path persay. + */ +L(second_aligned_loop_prep): +L(second_aligned_loop_set_furthest_match): movq %rdi, %rsi - jmp L(aligned_loop) + kunpck %k2, %k3, %k4 .p2align 4 -L(find_nul): - /* Mask out any matching bits after the null byte. */ - movl %ecx, %r8d - subl $1, %r8d - xorl %ecx, %r8d - andl %r8d, %eax - testl %eax, %eax - /* If there is no CHAR here, return the remembered one. */ - jz L(return_value) - bsrl %eax, %eax +L(second_aligned_loop): + VMOVU (VEC_SIZE * 4)(%rdi), %YMM1 + 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 |