[v3,4/4] x86: Optimize {str|wcs}rchr-evex
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dj/TryBot-apply_patch |
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Patch applied to master at the time it was sent
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dj/TryBot-32bit |
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Build for i686
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Commit Message
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.
---
sysdeps/x86_64/multiarch/strrchr-evex.S | 471 +++++++++++++++---------
1 file changed, 290 insertions(+), 181 deletions(-)
Comments
On Thu, Apr 21, 2022 at 6:52 PM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
>
> 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.
> ---
> sysdeps/x86_64/multiarch/strrchr-evex.S | 471 +++++++++++++++---------
> 1 file changed, 290 insertions(+), 181 deletions(-)
>
> diff --git a/sysdeps/x86_64/multiarch/strrchr-evex.S b/sysdeps/x86_64/multiarch/strrchr-evex.S
> index adeddaed32..8014c285b3 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
> --
> 2.25.1
>
LGTM.
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
Thanks.
On Fri, Apr 22, 2022 at 12:08 PM H.J. Lu via Libc-alpha
<libc-alpha@sourceware.org> wrote:
>
> On Thu, Apr 21, 2022 at 6:52 PM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
> >
> > 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.
> > ---
> > sysdeps/x86_64/multiarch/strrchr-evex.S | 471 +++++++++++++++---------
> > 1 file changed, 290 insertions(+), 181 deletions(-)
> >
> > diff --git a/sysdeps/x86_64/multiarch/strrchr-evex.S b/sysdeps/x86_64/multiarch/strrchr-evex.S
> > index adeddaed32..8014c285b3 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
> > --
> > 2.25.1
> >
>
> LGTM.
>
> Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
>
> Thanks.
>
> --
> H.J.
I would like to backport this patch to release branches.
Any comments or objections?
--Sunil
@@ -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