[v2,3/3] x86: Optimize memchr-evex.S
Commit Message
No bug. This commit optimizes memchr-evex.S. The optimizations include
replacing some branches with cmovcc, avoiding some branches entirely
in the less_4x_vec case, making the page cross logic less strict,
saving some ALU in the alignment process, and most importantly
increasing ILP in the 4x loop. test-memchr, test-rawmemchr, and
test-wmemchr are all passing.
Signed-off-by: Noah Goldstein <goldstein.w.n@gmail.com>
---
sysdeps/x86_64/multiarch/memchr-evex.S | 547 +++++++++++++++----------
1 file changed, 322 insertions(+), 225 deletions(-)
Comments
On Mon, May 03, 2021 at 04:06:55PM -0400, Noah Goldstein wrote:
> No bug. This commit optimizes memchr-evex.S. The optimizations include
> replacing some branches with cmovcc, avoiding some branches entirely
> in the less_4x_vec case, making the page cross logic less strict,
> saving some ALU in the alignment process, and most importantly
> increasing ILP in the 4x loop. test-memchr, test-rawmemchr, and
> test-wmemchr are all passing.
>
> Signed-off-by: Noah Goldstein <goldstein.w.n@gmail.com>
> ---
> sysdeps/x86_64/multiarch/memchr-evex.S | 547 +++++++++++++++----------
> 1 file changed, 322 insertions(+), 225 deletions(-)
>
> diff --git a/sysdeps/x86_64/multiarch/memchr-evex.S b/sysdeps/x86_64/multiarch/memchr-evex.S
> index 6dd5d67b90..147d7aa8ee 100644
> --- a/sysdeps/x86_64/multiarch/memchr-evex.S
> +++ b/sysdeps/x86_64/multiarch/memchr-evex.S
> @@ -26,14 +26,28 @@
>
> # ifdef USE_AS_WMEMCHR
> # define VPBROADCAST vpbroadcastd
> -# define VPCMP vpcmpd
> -# define SHIFT_REG r8d
> +# define VPMINU vpminud
> +# define VPCMP vpcmpd
> +# define VPCMPEQ vpcmpeqd
> +# define CHAR_SIZE 4
> # else
> # define VPBROADCAST vpbroadcastb
> -# define VPCMP vpcmpb
> -# define SHIFT_REG ecx
> +# define VPMINU vpminub
> +# define VPCMP vpcmpb
> +# define VPCMPEQ vpcmpeqb
> +# define CHAR_SIZE 1
> # endif
>
> +# ifdef USE_AS_RAWMEMCHR
> +# define RAW_PTR_REG rcx
> +# define ALGN_PTR_REG rdi
> +# else
> +# define RAW_PTR_REG rdi
> +# define ALGN_PTR_REG rcx
> +# endif
> +
> +# define XZERO xmm23
> +# define YZERO ymm23
Please rename XZERO/YZERO to XMMZERO/YMMZERO. OK with this change.
Thanks.
> # define XMMMATCH xmm16
> # define YMMMATCH ymm16
> # define YMM1 ymm17
> @@ -44,6 +58,8 @@
> # define YMM6 ymm22
>
> # define VEC_SIZE 32
> +# define CHAR_PER_VEC (VEC_SIZE / CHAR_SIZE)
> +# define PAGE_SIZE 4096
>
> .section .text.evex,"ax",@progbits
> ENTRY (MEMCHR)
> @@ -51,11 +67,7 @@ ENTRY (MEMCHR)
> /* Check for zero length. */
> test %RDX_LP, %RDX_LP
> jz L(zero)
> -# endif
> - movl %edi, %ecx
> -# ifdef USE_AS_WMEMCHR
> - shl $2, %RDX_LP
> -# else
> +
> # ifdef __ILP32__
> /* Clear the upper 32 bits. */
> movl %edx, %edx
> @@ -64,318 +76,403 @@ ENTRY (MEMCHR)
> /* Broadcast CHAR to YMMMATCH. */
> VPBROADCAST %esi, %YMMMATCH
> /* 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)
> + movl %edi, %eax
> + andl $(PAGE_SIZE - 1), %eax
> + cmpl $(PAGE_SIZE - VEC_SIZE), %eax
> + ja L(cross_page_boundary)
>
> /* Check the first VEC_SIZE bytes. */
> - VPCMP $0, (%rdi), %YMMMATCH, %k1
> - kmovd %k1, %eax
> - testl %eax, %eax
> -
> + VPCMP $0, (%rdi), %YMMMATCH, %k0
> + kmovd %k0, %eax
> # ifndef USE_AS_RAWMEMCHR
> - jnz L(first_vec_x0_check)
> - /* Adjust length and check the end of data. */
> - subq $VEC_SIZE, %rdx
> - jbe L(zero)
> + /* If length < CHAR_PER_VEC handle special. */
> + cmpq $CHAR_PER_VEC, %rdx
> + jbe L(first_vec_x0)
> +# endif
> + testl %eax, %eax
> + jz L(aligned_more)
> + tzcntl %eax, %eax
> +# ifdef USE_AS_WMEMCHR
> + /* NB: Multiply bytes by CHAR_SIZE to get the wchar_t count. */
> + leaq (%rdi, %rax, CHAR_SIZE), %rax
> # else
> - jnz L(first_vec_x0)
> + addq %rdi, %rax
> # endif
> -
> - /* Align data for aligned loads in the loop. */
> - addq $VEC_SIZE, %rdi
> - andl $(VEC_SIZE - 1), %ecx
> - andq $-VEC_SIZE, %rdi
> + ret
>
> # ifndef USE_AS_RAWMEMCHR
> - /* Adjust length. */
> - addq %rcx, %rdx
> -
> - subq $(VEC_SIZE * 4), %rdx
> - jbe L(last_4x_vec_or_less)
> -# endif
> - jmp L(more_4x_vec)
> +L(zero):
> + xorl %eax, %eax
> + ret
>
> + .p2align 5
> +L(first_vec_x0):
> + /* Check if first match was before length. */
> + tzcntl %eax, %eax
> + xorl %ecx, %ecx
> + cmpl %eax, %edx
> + leaq (%rdi, %rax, CHAR_SIZE), %rax
> + cmovle %rcx, %rax
> + ret
> +# else
> + /* NB: first_vec_x0 is 17 bytes which will leave
> + cross_page_boundary (which is relatively cold) close enough
> + to ideal alignment. So only realign L(cross_page_boundary) if
> + rawmemchr. */
> .p2align 4
> -L(cros_page_boundary):
> - andl $(VEC_SIZE - 1), %ecx
> +# endif
> +L(cross_page_boundary):
> + /* Save pointer before aligning as its original value is
> + necessary for computer return address if byte is found or
> + adjusting length if it is not and this is memchr. */
> + movq %rdi, %rcx
> + /* Align data to VEC_SIZE. ALGN_PTR_REG is rcx for memchr and rdi
> + for rawmemchr. */
> + andq $-VEC_SIZE, %ALGN_PTR_REG
> + VPCMP $0, (%ALGN_PTR_REG), %YMMMATCH, %k0
> + kmovd %k0, %r8d
> # ifdef USE_AS_WMEMCHR
> - /* NB: Divide shift count by 4 since each bit in K1 represent 4
> + /* NB: Divide shift count by 4 since each bit in K0 represent 4
> bytes. */
> - movl %ecx, %SHIFT_REG
> - sarl $2, %SHIFT_REG
> + sarl $2, %eax
> +# endif
> +# ifndef USE_AS_RAWMEMCHR
> + movl $(PAGE_SIZE / CHAR_SIZE), %esi
> + subl %eax, %esi
> # endif
> - andq $-VEC_SIZE, %rdi
> - VPCMP $0, (%rdi), %YMMMATCH, %k1
> - kmovd %k1, %eax
> - /* Remove the leading bytes. */
> - sarxl %SHIFT_REG, %eax, %eax
> - testl %eax, %eax
> - jz L(aligned_more)
> - tzcntl %eax, %eax
> # ifdef USE_AS_WMEMCHR
> - /* NB: Multiply wchar_t count by 4 to get the number of bytes. */
> - sall $2, %eax
> + andl $(CHAR_PER_VEC - 1), %eax
> # endif
> + /* Remove the leading bytes. */
> + sarxl %eax, %r8d, %eax
> # ifndef USE_AS_RAWMEMCHR
> /* Check the end of data. */
> - cmpq %rax, %rdx
> - jbe L(zero)
> + cmpq %rsi, %rdx
> + jbe L(first_vec_x0)
> +# endif
> + testl %eax, %eax
> + jz L(cross_page_continue)
> + tzcntl %eax, %eax
> +# ifdef USE_AS_WMEMCHR
> + /* NB: Multiply bytes by CHAR_SIZE to get the wchar_t count. */
> + leaq (%RAW_PTR_REG, %rax, CHAR_SIZE), %rax
> +# else
> + addq %RAW_PTR_REG, %rax
> # endif
> - addq %rdi, %rax
> - addq %rcx, %rax
> ret
>
> .p2align 4
> -L(aligned_more):
> -# ifndef USE_AS_RAWMEMCHR
> - /* Calculate "rdx + rcx - VEC_SIZE" with "rdx - (VEC_SIZE - rcx)"
> - instead of "(rdx + rcx) - VEC_SIZE" to void possible addition
> - overflow. */
> - negq %rcx
> - addq $VEC_SIZE, %rcx
> +L(first_vec_x1):
> + tzcntl %eax, %eax
> + leaq VEC_SIZE(%rdi, %rax, CHAR_SIZE), %rax
> + ret
>
> - /* Check the end of data. */
> - subq %rcx, %rdx
> - jbe L(zero)
> -# endif
> + .p2align 4
> +L(first_vec_x2):
> + tzcntl %eax, %eax
> + leaq (VEC_SIZE * 2)(%rdi, %rax, CHAR_SIZE), %rax
> + ret
>
> - addq $VEC_SIZE, %rdi
> + .p2align 4
> +L(first_vec_x3):
> + tzcntl %eax, %eax
> + leaq (VEC_SIZE * 3)(%rdi, %rax, CHAR_SIZE), %rax
> + ret
>
> -# ifndef USE_AS_RAWMEMCHR
> - subq $(VEC_SIZE * 4), %rdx
> - jbe L(last_4x_vec_or_less)
> -# endif
> + .p2align 4
> +L(first_vec_x4):
> + tzcntl %eax, %eax
> + leaq (VEC_SIZE * 4)(%rdi, %rax, CHAR_SIZE), %rax
> + ret
>
> -L(more_4x_vec):
> + .p2align 5
> +L(aligned_more):
> /* Check the first 4 * VEC_SIZE. Only one VEC_SIZE at a time
> since data is only aligned to VEC_SIZE. */
> - VPCMP $0, (%rdi), %YMMMATCH, %k1
> - kmovd %k1, %eax
> - testl %eax, %eax
> - jnz L(first_vec_x0)
>
> - VPCMP $0, VEC_SIZE(%rdi), %YMMMATCH, %k1
> - kmovd %k1, %eax
> +# ifndef USE_AS_RAWMEMCHR
> + /* Align data to VEC_SIZE. */
> +L(cross_page_continue):
> + xorl %ecx, %ecx
> + subl %edi, %ecx
> + andq $-VEC_SIZE, %rdi
> + /* esi is for adjusting length to see if near the end. */
> + leal (VEC_SIZE * 5)(%rdi, %rcx), %esi
> +# ifdef USE_AS_WMEMCHR
> + /* NB: Divide bytes by 4 to get the wchar_t count. */
> + sarl $2, %esi
> +# endif
> +# else
> + andq $-VEC_SIZE, %rdi
> +L(cross_page_continue):
> +# endif
> + /* Load first VEC regardless. */
> + VPCMP $0, (VEC_SIZE)(%rdi), %YMMMATCH, %k0
> + kmovd %k0, %eax
> +# ifndef USE_AS_RAWMEMCHR
> + /* Adjust length. If near end handle specially. */
> + subq %rsi, %rdx
> + jbe L(last_4x_vec_or_less)
> +# endif
> testl %eax, %eax
> jnz L(first_vec_x1)
>
> - VPCMP $0, (VEC_SIZE * 2)(%rdi), %YMMMATCH, %k1
> - kmovd %k1, %eax
> + VPCMP $0, (VEC_SIZE * 2)(%rdi), %YMMMATCH, %k0
> + kmovd %k0, %eax
> testl %eax, %eax
> jnz L(first_vec_x2)
>
> - VPCMP $0, (VEC_SIZE * 3)(%rdi), %YMMMATCH, %k1
> - kmovd %k1, %eax
> + VPCMP $0, (VEC_SIZE * 3)(%rdi), %YMMMATCH, %k0
> + kmovd %k0, %eax
> testl %eax, %eax
> jnz L(first_vec_x3)
>
> - addq $(VEC_SIZE * 4), %rdi
> + VPCMP $0, (VEC_SIZE * 4)(%rdi), %YMMMATCH, %k0
> + kmovd %k0, %eax
> + testl %eax, %eax
> + jnz L(first_vec_x4)
> +
>
> # ifndef USE_AS_RAWMEMCHR
> - subq $(VEC_SIZE * 4), %rdx
> - jbe L(last_4x_vec_or_less)
> -# endif
> + /* Check if at last CHAR_PER_VEC * 4 length. */
> + subq $(CHAR_PER_VEC * 4), %rdx
> + jbe L(last_4x_vec_or_less_cmpeq)
> + addq $VEC_SIZE, %rdi
>
> - /* Align data to 4 * VEC_SIZE. */
> - movq %rdi, %rcx
> - andl $(4 * VEC_SIZE - 1), %ecx
> + /* Align data to VEC_SIZE * 4 for the loop and readjust length.
> + */
> +# ifdef USE_AS_WMEMCHR
> + movl %edi, %ecx
> andq $-(4 * VEC_SIZE), %rdi
> -
> -# ifndef USE_AS_RAWMEMCHR
> - /* Adjust length. */
> + andl $(VEC_SIZE * 4 - 1), %ecx
> + /* NB: Divide bytes by 4 to get the wchar_t count. */
> + sarl $2, %ecx
> addq %rcx, %rdx
> +# else
> + addq %rdi, %rdx
> + andq $-(4 * VEC_SIZE), %rdi
> + subq %rdi, %rdx
> +# endif
> +# else
> + addq $VEC_SIZE, %rdi
> + andq $-(4 * VEC_SIZE), %rdi
> # endif
>
> + vpxorq %XZERO, %XZERO, %XZERO
> +
> + /* Compare 4 * VEC at a time forward. */
> .p2align 4
> L(loop_4x_vec):
> - /* Compare 4 * VEC at a time forward. */
> - VPCMP $0, (%rdi), %YMMMATCH, %k1
> - VPCMP $0, VEC_SIZE(%rdi), %YMMMATCH, %k2
> - kord %k1, %k2, %k5
> - VPCMP $0, (VEC_SIZE * 2)(%rdi), %YMMMATCH, %k3
> - VPCMP $0, (VEC_SIZE * 3)(%rdi), %YMMMATCH, %k4
> -
> - kord %k3, %k4, %k6
> - kortestd %k5, %k6
> - jnz L(4x_vec_end)
> -
> - addq $(VEC_SIZE * 4), %rdi
> -
> + /* It would be possible to save some instructions using 4x VPCMP
> + but bottleneck on port 5 makes it not woth it. */
> + VPCMP $4, (VEC_SIZE * 4)(%rdi), %YMMMATCH, %k1
> + /* xor will set bytes match esi to zero. */
> + vpxorq (VEC_SIZE * 5)(%rdi), %YMMMATCH, %YMM2
> + vpxorq (VEC_SIZE * 6)(%rdi), %YMMMATCH, %YMM3
> + VPCMP $0, (VEC_SIZE * 7)(%rdi), %YMMMATCH, %k3
> + /* Reduce VEC2 / VEC3 with min and VEC1 with zero mask. */
> + VPMINU %YMM2, %YMM3, %YMM3 {%k1} {z}
> + VPCMP $0, %YMM3, %YZERO, %k2
> # ifdef USE_AS_RAWMEMCHR
> - jmp L(loop_4x_vec)
> + subq $-(VEC_SIZE * 4), %rdi
> + kortestd %k2, %k3
> + jz L(loop_4x_vec)
> # else
> - subq $(VEC_SIZE * 4), %rdx
> + kortestd %k2, %k3
> + jnz L(loop_4x_vec_end)
> +
> + subq $-(VEC_SIZE * 4), %rdi
> +
> + subq $(CHAR_PER_VEC * 4), %rdx
> ja L(loop_4x_vec)
>
> + /* Fall through into less than 4 remaining vectors of length case.
> + */
> + VPCMP $0, (VEC_SIZE * 4)(%rdi), %YMMMATCH, %k0
> + kmovd %k0, %eax
> + addq $(VEC_SIZE * 3), %rdi
> + .p2align 4
> L(last_4x_vec_or_less):
> - /* Less than 4 * VEC and aligned to VEC_SIZE. */
> - addl $(VEC_SIZE * 2), %edx
> - jle L(last_2x_vec)
> -
> - VPCMP $0, (%rdi), %YMMMATCH, %k1
> - kmovd %k1, %eax
> + /* Check if first VEC contained match. */
> testl %eax, %eax
> - jnz L(first_vec_x0)
> + jnz L(first_vec_x1_check)
>
> - VPCMP $0, VEC_SIZE(%rdi), %YMMMATCH, %k1
> - kmovd %k1, %eax
> - testl %eax, %eax
> - jnz L(first_vec_x1)
> + /* If remaining length > CHAR_PER_VEC * 2. */
> + addl $(CHAR_PER_VEC * 2), %edx
> + jg L(last_4x_vec)
>
> - VPCMP $0, (VEC_SIZE * 2)(%rdi), %YMMMATCH, %k1
> - kmovd %k1, %eax
> - testl %eax, %eax
> +L(last_2x_vec):
> + /* If remaining length < CHAR_PER_VEC. */
> + addl $CHAR_PER_VEC, %edx
> + jle L(zero_end)
>
> - jnz L(first_vec_x2_check)
> - subl $VEC_SIZE, %edx
> - jle L(zero)
> + /* Check VEC2 and compare any match with remaining length. */
> + VPCMP $0, (VEC_SIZE * 2)(%rdi), %YMMMATCH, %k0
> + kmovd %k0, %eax
> + tzcntl %eax, %eax
> + cmpl %eax, %edx
> + jbe L(set_zero_end)
> + leaq (VEC_SIZE * 2)(%rdi, %rax, CHAR_SIZE), %rax
> +L(zero_end):
> + ret
>
> - VPCMP $0, (VEC_SIZE * 3)(%rdi), %YMMMATCH, %k1
> - kmovd %k1, %eax
> - testl %eax, %eax
>
> - jnz L(first_vec_x3_check)
> + .p2align 4
> +L(first_vec_x1_check):
> + tzcntl %eax, %eax
> + /* Adjust length. */
> + subl $-(CHAR_PER_VEC * 4), %edx
> + /* Check if match within remaining length. */
> + cmpl %eax, %edx
> + jbe L(set_zero_end)
> + /* NB: Multiply bytes by CHAR_SIZE to get the wchar_t count. */
> + leaq VEC_SIZE(%rdi, %rax, CHAR_SIZE), %rax
> + ret
> +L(set_zero_end):
> xorl %eax, %eax
> ret
>
> .p2align 4
> -L(last_2x_vec):
> - addl $(VEC_SIZE * 2), %edx
> - VPCMP $0, (%rdi), %YMMMATCH, %k1
> +L(loop_4x_vec_end):
> +# endif
> + /* rawmemchr will fall through into this if match was found in
> + loop. */
> +
> + /* k1 has not of matches with VEC1. */
> kmovd %k1, %eax
> - testl %eax, %eax
> +# ifdef USE_AS_WMEMCHR
> + subl $((1 << CHAR_PER_VEC) - 1), %eax
> +# else
> + incl %eax
> +# endif
> + jnz L(last_vec_x1_return)
>
> - jnz L(first_vec_x0_check)
> - subl $VEC_SIZE, %edx
> - jle L(zero)
> + VPCMP $0, %YMM2, %YZERO, %k0
> + kmovd %k0, %eax
> + testl %eax, %eax
> + jnz L(last_vec_x2_return)
>
> - VPCMP $0, VEC_SIZE(%rdi), %YMMMATCH, %k1
> - kmovd %k1, %eax
> + kmovd %k2, %eax
> testl %eax, %eax
> - jnz L(first_vec_x1_check)
> - xorl %eax, %eax
> - ret
> + jnz L(last_vec_x3_return)
>
> - .p2align 4
> -L(first_vec_x0_check):
> + kmovd %k3, %eax
> tzcntl %eax, %eax
> -# ifdef USE_AS_WMEMCHR
> - /* NB: Multiply wchar_t count by 4 to get the number of bytes. */
> - sall $2, %eax
> +# ifdef USE_AS_RAWMEMCHR
> + leaq (VEC_SIZE * 3)(%rdi, %rax, CHAR_SIZE), %rax
> +# else
> + leaq (VEC_SIZE * 7)(%rdi, %rax, CHAR_SIZE), %rax
> # endif
> - /* Check the end of data. */
> - cmpq %rax, %rdx
> - jbe L(zero)
> - addq %rdi, %rax
> ret
>
> .p2align 4
> -L(first_vec_x1_check):
> +L(last_vec_x1_return):
> tzcntl %eax, %eax
> -# ifdef USE_AS_WMEMCHR
> - /* NB: Multiply wchar_t count by 4 to get the number of bytes. */
> - sall $2, %eax
> -# endif
> - /* Check the end of data. */
> - cmpq %rax, %rdx
> - jbe L(zero)
> - addq $VEC_SIZE, %rax
> +# ifdef USE_AS_RAWMEMCHR
> +# ifdef USE_AS_WMEMCHR
> + /* NB: Multiply bytes by CHAR_SIZE to get the wchar_t count. */
> + leaq (%rdi, %rax, CHAR_SIZE), %rax
> +# else
> addq %rdi, %rax
> - ret
> -
> - .p2align 4
> -L(first_vec_x2_check):
> - tzcntl %eax, %eax
> -# ifdef USE_AS_WMEMCHR
> - /* NB: Multiply wchar_t count by 4 to get the number of bytes. */
> - sall $2, %eax
> +# endif
> +# else
> + /* NB: Multiply bytes by CHAR_SIZE to get the wchar_t count. */
> + leaq (VEC_SIZE * 4)(%rdi, %rax, CHAR_SIZE), %rax
> # endif
> - /* Check the end of data. */
> - cmpq %rax, %rdx
> - jbe L(zero)
> - addq $(VEC_SIZE * 2), %rax
> - addq %rdi, %rax
> ret
>
> .p2align 4
> -L(first_vec_x3_check):
> +L(last_vec_x2_return):
> tzcntl %eax, %eax
> -# ifdef USE_AS_WMEMCHR
> - /* NB: Multiply wchar_t count by 4 to get the number of bytes. */
> - sall $2, %eax
> +# ifdef USE_AS_RAWMEMCHR
> + /* NB: Multiply bytes by CHAR_SIZE to get the wchar_t count. */
> + leaq VEC_SIZE(%rdi, %rax, CHAR_SIZE), %rax
> +# else
> + /* NB: Multiply bytes by CHAR_SIZE to get the wchar_t count. */
> + leaq (VEC_SIZE * 5)(%rdi, %rax, CHAR_SIZE), %rax
> # endif
> - /* Check the end of data. */
> - cmpq %rax, %rdx
> - jbe L(zero)
> - addq $(VEC_SIZE * 3), %rax
> - addq %rdi, %rax
> ret
>
> .p2align 4
> -L(zero):
> - xorl %eax, %eax
> - ret
> -# endif
> -
> - .p2align 4
> -L(first_vec_x0):
> +L(last_vec_x3_return):
> tzcntl %eax, %eax
> -# ifdef USE_AS_WMEMCHR
> - /* NB: Multiply wchar_t count by 4 to get the number of bytes. */
> - leaq (%rdi, %rax, 4), %rax
> +# ifdef USE_AS_RAWMEMCHR
> + /* NB: Multiply bytes by CHAR_SIZE to get the wchar_t count. */
> + leaq (VEC_SIZE * 2)(%rdi, %rax, CHAR_SIZE), %rax
> # else
> - addq %rdi, %rax
> + /* NB: Multiply bytes by CHAR_SIZE to get the wchar_t count. */
> + leaq (VEC_SIZE * 6)(%rdi, %rax, CHAR_SIZE), %rax
> # endif
> ret
>
> +
> +# ifndef USE_AS_RAWMEMCHR
> +L(last_4x_vec_or_less_cmpeq):
> + VPCMP $0, (VEC_SIZE * 5)(%rdi), %YMMMATCH, %k0
> + kmovd %k0, %eax
> + subq $-(VEC_SIZE * 4), %rdi
> + /* Check first VEC regardless. */
> + testl %eax, %eax
> + jnz L(first_vec_x1_check)
> +
> + /* If remaining length <= CHAR_PER_VEC * 2. */
> + addl $(CHAR_PER_VEC * 2), %edx
> + jle L(last_2x_vec)
> +
> .p2align 4
> -L(first_vec_x1):
> +L(last_4x_vec):
> + VPCMP $0, (VEC_SIZE * 2)(%rdi), %YMMMATCH, %k0
> + kmovd %k0, %eax
> + testl %eax, %eax
> + jnz L(last_vec_x2)
> +
> +
> + VPCMP $0, (VEC_SIZE * 3)(%rdi), %YMMMATCH, %k0
> + kmovd %k0, %eax
> + /* Create mask for possible matches within remaining length. */
> +# ifdef USE_AS_WMEMCHR
> + movl $((1 << (CHAR_PER_VEC * 2)) - 1), %ecx
> + bzhil %edx, %ecx, %ecx
> +# else
> + movq $-1, %rcx
> + bzhiq %rdx, %rcx, %rcx
> +# endif
> + /* Test matches in data against length match. */
> + andl %ecx, %eax
> + jnz L(last_vec_x3)
> +
> + /* if remaining length <= CHAR_PER_VEC * 3 (Note this is after
> + remaining length was found to be > CHAR_PER_VEC * 2. */
> + subl $CHAR_PER_VEC, %edx
> + jbe L(zero_end2)
> +
> +
> + VPCMP $0, (VEC_SIZE * 4)(%rdi), %YMMMATCH, %k0
> + kmovd %k0, %eax
> + /* Shift remaining length mask for last VEC. */
> +# ifdef USE_AS_WMEMCHR
> + shrl $CHAR_PER_VEC, %ecx
> +# else
> + shrq $CHAR_PER_VEC, %rcx
> +# endif
> + andl %ecx, %eax
> + jz L(zero_end2)
> tzcntl %eax, %eax
> -# ifdef USE_AS_WMEMCHR
> - /* NB: Multiply wchar_t count by 4 to get the number of bytes. */
> - leaq VEC_SIZE(%rdi, %rax, 4), %rax
> -# else
> - addq $VEC_SIZE, %rax
> - addq %rdi, %rax
> -# endif
> + leaq (VEC_SIZE * 4)(%rdi, %rax, CHAR_SIZE), %rax
> +L(zero_end2):
> ret
>
> - .p2align 4
> -L(first_vec_x2):
> +L(last_vec_x2):
> tzcntl %eax, %eax
> -# ifdef USE_AS_WMEMCHR
> - /* NB: Multiply wchar_t count by 4 to get the number of bytes. */
> - leaq (VEC_SIZE * 2)(%rdi, %rax, 4), %rax
> -# else
> - addq $(VEC_SIZE * 2), %rax
> - addq %rdi, %rax
> -# endif
> + leaq (VEC_SIZE * 2)(%rdi, %rax, CHAR_SIZE), %rax
> ret
>
> .p2align 4
> -L(4x_vec_end):
> - kmovd %k1, %eax
> - testl %eax, %eax
> - jnz L(first_vec_x0)
> - kmovd %k2, %eax
> - testl %eax, %eax
> - jnz L(first_vec_x1)
> - kmovd %k3, %eax
> - testl %eax, %eax
> - jnz L(first_vec_x2)
> - kmovd %k4, %eax
> - testl %eax, %eax
> -L(first_vec_x3):
> +L(last_vec_x3):
> tzcntl %eax, %eax
> -# ifdef USE_AS_WMEMCHR
> - /* NB: Multiply wchar_t count by 4 to get the number of bytes. */
> - leaq (VEC_SIZE * 3)(%rdi, %rax, 4), %rax
> -# else
> - addq $(VEC_SIZE * 3), %rax
> - addq %rdi, %rax
> -# endif
> + leaq (VEC_SIZE * 3)(%rdi, %rax, CHAR_SIZE), %rax
> ret
> +# endif
>
> END (MEMCHR)
> #endif
> --
> 2.29.2
>
On Mon, May 3, 2021 at 6:26 PM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> On Mon, May 03, 2021 at 04:06:55PM -0400, Noah Goldstein wrote:
> > No bug. This commit optimizes memchr-evex.S. The optimizations include
> > replacing some branches with cmovcc, avoiding some branches entirely
> > in the less_4x_vec case, making the page cross logic less strict,
> > saving some ALU in the alignment process, and most importantly
> > increasing ILP in the 4x loop. test-memchr, test-rawmemchr, and
> > test-wmemchr are all passing.
> >
> > Signed-off-by: Noah Goldstein <goldstein.w.n@gmail.com>
> > ---
> > sysdeps/x86_64/multiarch/memchr-evex.S | 547 +++++++++++++++----------
> > 1 file changed, 322 insertions(+), 225 deletions(-)
> >
> > diff --git a/sysdeps/x86_64/multiarch/memchr-evex.S b/sysdeps/x86_64/multiarch/memchr-evex.S
> > index 6dd5d67b90..147d7aa8ee 100644
> > --- a/sysdeps/x86_64/multiarch/memchr-evex.S
> > +++ b/sysdeps/x86_64/multiarch/memchr-evex.S
> > @@ -26,14 +26,28 @@
> >
> > # ifdef USE_AS_WMEMCHR
> > # define VPBROADCAST vpbroadcastd
> > -# define VPCMP vpcmpd
> > -# define SHIFT_REG r8d
> > +# define VPMINU vpminud
> > +# define VPCMP vpcmpd
> > +# define VPCMPEQ vpcmpeqd
> > +# define CHAR_SIZE 4
> > # else
> > # define VPBROADCAST vpbroadcastb
> > -# define VPCMP vpcmpb
> > -# define SHIFT_REG ecx
> > +# define VPMINU vpminub
> > +# define VPCMP vpcmpb
> > +# define VPCMPEQ vpcmpeqb
> > +# define CHAR_SIZE 1
> > # endif
> >
> > +# ifdef USE_AS_RAWMEMCHR
> > +# define RAW_PTR_REG rcx
> > +# define ALGN_PTR_REG rdi
> > +# else
> > +# define RAW_PTR_REG rdi
> > +# define ALGN_PTR_REG rcx
> > +# endif
> > +
> > +# define XZERO xmm23
> > +# define YZERO ymm23
>
> Please rename XZERO/YZERO to XMMZERO/YMMZERO. OK with this change.
Done and thanks!
>
> Thanks.
>
> > # define XMMMATCH xmm16
> > # define YMMMATCH ymm16
> > # define YMM1 ymm17
> > @@ -44,6 +58,8 @@
> > # define YMM6 ymm22
> >
> > # define VEC_SIZE 32
> > +# define CHAR_PER_VEC (VEC_SIZE / CHAR_SIZE)
> > +# define PAGE_SIZE 4096
> >
> > .section .text.evex,"ax",@progbits
> > ENTRY (MEMCHR)
> > @@ -51,11 +67,7 @@ ENTRY (MEMCHR)
> > /* Check for zero length. */
> > test %RDX_LP, %RDX_LP
> > jz L(zero)
> > -# endif
> > - movl %edi, %ecx
> > -# ifdef USE_AS_WMEMCHR
> > - shl $2, %RDX_LP
> > -# else
> > +
> > # ifdef __ILP32__
> > /* Clear the upper 32 bits. */
> > movl %edx, %edx
> > @@ -64,318 +76,403 @@ ENTRY (MEMCHR)
> > /* Broadcast CHAR to YMMMATCH. */
> > VPBROADCAST %esi, %YMMMATCH
> > /* 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)
> > + movl %edi, %eax
> > + andl $(PAGE_SIZE - 1), %eax
> > + cmpl $(PAGE_SIZE - VEC_SIZE), %eax
> > + ja L(cross_page_boundary)
> >
> > /* Check the first VEC_SIZE bytes. */
> > - VPCMP $0, (%rdi), %YMMMATCH, %k1
> > - kmovd %k1, %eax
> > - testl %eax, %eax
> > -
> > + VPCMP $0, (%rdi), %YMMMATCH, %k0
> > + kmovd %k0, %eax
> > # ifndef USE_AS_RAWMEMCHR
> > - jnz L(first_vec_x0_check)
> > - /* Adjust length and check the end of data. */
> > - subq $VEC_SIZE, %rdx
> > - jbe L(zero)
> > + /* If length < CHAR_PER_VEC handle special. */
> > + cmpq $CHAR_PER_VEC, %rdx
> > + jbe L(first_vec_x0)
> > +# endif
> > + testl %eax, %eax
> > + jz L(aligned_more)
> > + tzcntl %eax, %eax
> > +# ifdef USE_AS_WMEMCHR
> > + /* NB: Multiply bytes by CHAR_SIZE to get the wchar_t count. */
> > + leaq (%rdi, %rax, CHAR_SIZE), %rax
> > # else
> > - jnz L(first_vec_x0)
> > + addq %rdi, %rax
> > # endif
> > -
> > - /* Align data for aligned loads in the loop. */
> > - addq $VEC_SIZE, %rdi
> > - andl $(VEC_SIZE - 1), %ecx
> > - andq $-VEC_SIZE, %rdi
> > + ret
> >
> > # ifndef USE_AS_RAWMEMCHR
> > - /* Adjust length. */
> > - addq %rcx, %rdx
> > -
> > - subq $(VEC_SIZE * 4), %rdx
> > - jbe L(last_4x_vec_or_less)
> > -# endif
> > - jmp L(more_4x_vec)
> > +L(zero):
> > + xorl %eax, %eax
> > + ret
> >
> > + .p2align 5
> > +L(first_vec_x0):
> > + /* Check if first match was before length. */
> > + tzcntl %eax, %eax
> > + xorl %ecx, %ecx
> > + cmpl %eax, %edx
> > + leaq (%rdi, %rax, CHAR_SIZE), %rax
> > + cmovle %rcx, %rax
> > + ret
> > +# else
> > + /* NB: first_vec_x0 is 17 bytes which will leave
> > + cross_page_boundary (which is relatively cold) close enough
> > + to ideal alignment. So only realign L(cross_page_boundary) if
> > + rawmemchr. */
> > .p2align 4
> > -L(cros_page_boundary):
> > - andl $(VEC_SIZE - 1), %ecx
> > +# endif
> > +L(cross_page_boundary):
> > + /* Save pointer before aligning as its original value is
> > + necessary for computer return address if byte is found or
> > + adjusting length if it is not and this is memchr. */
> > + movq %rdi, %rcx
> > + /* Align data to VEC_SIZE. ALGN_PTR_REG is rcx for memchr and rdi
> > + for rawmemchr. */
> > + andq $-VEC_SIZE, %ALGN_PTR_REG
> > + VPCMP $0, (%ALGN_PTR_REG), %YMMMATCH, %k0
> > + kmovd %k0, %r8d
> > # ifdef USE_AS_WMEMCHR
> > - /* NB: Divide shift count by 4 since each bit in K1 represent 4
> > + /* NB: Divide shift count by 4 since each bit in K0 represent 4
> > bytes. */
> > - movl %ecx, %SHIFT_REG
> > - sarl $2, %SHIFT_REG
> > + sarl $2, %eax
> > +# endif
> > +# ifndef USE_AS_RAWMEMCHR
> > + movl $(PAGE_SIZE / CHAR_SIZE), %esi
> > + subl %eax, %esi
> > # endif
> > - andq $-VEC_SIZE, %rdi
> > - VPCMP $0, (%rdi), %YMMMATCH, %k1
> > - kmovd %k1, %eax
> > - /* Remove the leading bytes. */
> > - sarxl %SHIFT_REG, %eax, %eax
> > - testl %eax, %eax
> > - jz L(aligned_more)
> > - tzcntl %eax, %eax
> > # ifdef USE_AS_WMEMCHR
> > - /* NB: Multiply wchar_t count by 4 to get the number of bytes. */
> > - sall $2, %eax
> > + andl $(CHAR_PER_VEC - 1), %eax
> > # endif
> > + /* Remove the leading bytes. */
> > + sarxl %eax, %r8d, %eax
> > # ifndef USE_AS_RAWMEMCHR
> > /* Check the end of data. */
> > - cmpq %rax, %rdx
> > - jbe L(zero)
> > + cmpq %rsi, %rdx
> > + jbe L(first_vec_x0)
> > +# endif
> > + testl %eax, %eax
> > + jz L(cross_page_continue)
> > + tzcntl %eax, %eax
> > +# ifdef USE_AS_WMEMCHR
> > + /* NB: Multiply bytes by CHAR_SIZE to get the wchar_t count. */
> > + leaq (%RAW_PTR_REG, %rax, CHAR_SIZE), %rax
> > +# else
> > + addq %RAW_PTR_REG, %rax
> > # endif
> > - addq %rdi, %rax
> > - addq %rcx, %rax
> > ret
> >
> > .p2align 4
> > -L(aligned_more):
> > -# ifndef USE_AS_RAWMEMCHR
> > - /* Calculate "rdx + rcx - VEC_SIZE" with "rdx - (VEC_SIZE - rcx)"
> > - instead of "(rdx + rcx) - VEC_SIZE" to void possible addition
> > - overflow. */
> > - negq %rcx
> > - addq $VEC_SIZE, %rcx
> > +L(first_vec_x1):
> > + tzcntl %eax, %eax
> > + leaq VEC_SIZE(%rdi, %rax, CHAR_SIZE), %rax
> > + ret
> >
> > - /* Check the end of data. */
> > - subq %rcx, %rdx
> > - jbe L(zero)
> > -# endif
> > + .p2align 4
> > +L(first_vec_x2):
> > + tzcntl %eax, %eax
> > + leaq (VEC_SIZE * 2)(%rdi, %rax, CHAR_SIZE), %rax
> > + ret
> >
> > - addq $VEC_SIZE, %rdi
> > + .p2align 4
> > +L(first_vec_x3):
> > + tzcntl %eax, %eax
> > + leaq (VEC_SIZE * 3)(%rdi, %rax, CHAR_SIZE), %rax
> > + ret
> >
> > -# ifndef USE_AS_RAWMEMCHR
> > - subq $(VEC_SIZE * 4), %rdx
> > - jbe L(last_4x_vec_or_less)
> > -# endif
> > + .p2align 4
> > +L(first_vec_x4):
> > + tzcntl %eax, %eax
> > + leaq (VEC_SIZE * 4)(%rdi, %rax, CHAR_SIZE), %rax
> > + ret
> >
> > -L(more_4x_vec):
> > + .p2align 5
> > +L(aligned_more):
> > /* Check the first 4 * VEC_SIZE. Only one VEC_SIZE at a time
> > since data is only aligned to VEC_SIZE. */
> > - VPCMP $0, (%rdi), %YMMMATCH, %k1
> > - kmovd %k1, %eax
> > - testl %eax, %eax
> > - jnz L(first_vec_x0)
> >
> > - VPCMP $0, VEC_SIZE(%rdi), %YMMMATCH, %k1
> > - kmovd %k1, %eax
> > +# ifndef USE_AS_RAWMEMCHR
> > + /* Align data to VEC_SIZE. */
> > +L(cross_page_continue):
> > + xorl %ecx, %ecx
> > + subl %edi, %ecx
> > + andq $-VEC_SIZE, %rdi
> > + /* esi is for adjusting length to see if near the end. */
> > + leal (VEC_SIZE * 5)(%rdi, %rcx), %esi
> > +# ifdef USE_AS_WMEMCHR
> > + /* NB: Divide bytes by 4 to get the wchar_t count. */
> > + sarl $2, %esi
> > +# endif
> > +# else
> > + andq $-VEC_SIZE, %rdi
> > +L(cross_page_continue):
> > +# endif
> > + /* Load first VEC regardless. */
> > + VPCMP $0, (VEC_SIZE)(%rdi), %YMMMATCH, %k0
> > + kmovd %k0, %eax
> > +# ifndef USE_AS_RAWMEMCHR
> > + /* Adjust length. If near end handle specially. */
> > + subq %rsi, %rdx
> > + jbe L(last_4x_vec_or_less)
> > +# endif
> > testl %eax, %eax
> > jnz L(first_vec_x1)
> >
> > - VPCMP $0, (VEC_SIZE * 2)(%rdi), %YMMMATCH, %k1
> > - kmovd %k1, %eax
> > + VPCMP $0, (VEC_SIZE * 2)(%rdi), %YMMMATCH, %k0
> > + kmovd %k0, %eax
> > testl %eax, %eax
> > jnz L(first_vec_x2)
> >
> > - VPCMP $0, (VEC_SIZE * 3)(%rdi), %YMMMATCH, %k1
> > - kmovd %k1, %eax
> > + VPCMP $0, (VEC_SIZE * 3)(%rdi), %YMMMATCH, %k0
> > + kmovd %k0, %eax
> > testl %eax, %eax
> > jnz L(first_vec_x3)
> >
> > - addq $(VEC_SIZE * 4), %rdi
> > + VPCMP $0, (VEC_SIZE * 4)(%rdi), %YMMMATCH, %k0
> > + kmovd %k0, %eax
> > + testl %eax, %eax
> > + jnz L(first_vec_x4)
> > +
> >
> > # ifndef USE_AS_RAWMEMCHR
> > - subq $(VEC_SIZE * 4), %rdx
> > - jbe L(last_4x_vec_or_less)
> > -# endif
> > + /* Check if at last CHAR_PER_VEC * 4 length. */
> > + subq $(CHAR_PER_VEC * 4), %rdx
> > + jbe L(last_4x_vec_or_less_cmpeq)
> > + addq $VEC_SIZE, %rdi
> >
> > - /* Align data to 4 * VEC_SIZE. */
> > - movq %rdi, %rcx
> > - andl $(4 * VEC_SIZE - 1), %ecx
> > + /* Align data to VEC_SIZE * 4 for the loop and readjust length.
> > + */
> > +# ifdef USE_AS_WMEMCHR
> > + movl %edi, %ecx
> > andq $-(4 * VEC_SIZE), %rdi
> > -
> > -# ifndef USE_AS_RAWMEMCHR
> > - /* Adjust length. */
> > + andl $(VEC_SIZE * 4 - 1), %ecx
> > + /* NB: Divide bytes by 4 to get the wchar_t count. */
> > + sarl $2, %ecx
> > addq %rcx, %rdx
> > +# else
> > + addq %rdi, %rdx
> > + andq $-(4 * VEC_SIZE), %rdi
> > + subq %rdi, %rdx
> > +# endif
> > +# else
> > + addq $VEC_SIZE, %rdi
> > + andq $-(4 * VEC_SIZE), %rdi
> > # endif
> >
> > + vpxorq %XZERO, %XZERO, %XZERO
> > +
> > + /* Compare 4 * VEC at a time forward. */
> > .p2align 4
> > L(loop_4x_vec):
> > - /* Compare 4 * VEC at a time forward. */
> > - VPCMP $0, (%rdi), %YMMMATCH, %k1
> > - VPCMP $0, VEC_SIZE(%rdi), %YMMMATCH, %k2
> > - kord %k1, %k2, %k5
> > - VPCMP $0, (VEC_SIZE * 2)(%rdi), %YMMMATCH, %k3
> > - VPCMP $0, (VEC_SIZE * 3)(%rdi), %YMMMATCH, %k4
> > -
> > - kord %k3, %k4, %k6
> > - kortestd %k5, %k6
> > - jnz L(4x_vec_end)
> > -
> > - addq $(VEC_SIZE * 4), %rdi
> > -
> > + /* It would be possible to save some instructions using 4x VPCMP
> > + but bottleneck on port 5 makes it not woth it. */
> > + VPCMP $4, (VEC_SIZE * 4)(%rdi), %YMMMATCH, %k1
> > + /* xor will set bytes match esi to zero. */
> > + vpxorq (VEC_SIZE * 5)(%rdi), %YMMMATCH, %YMM2
> > + vpxorq (VEC_SIZE * 6)(%rdi), %YMMMATCH, %YMM3
> > + VPCMP $0, (VEC_SIZE * 7)(%rdi), %YMMMATCH, %k3
> > + /* Reduce VEC2 / VEC3 with min and VEC1 with zero mask. */
> > + VPMINU %YMM2, %YMM3, %YMM3 {%k1} {z}
> > + VPCMP $0, %YMM3, %YZERO, %k2
> > # ifdef USE_AS_RAWMEMCHR
> > - jmp L(loop_4x_vec)
> > + subq $-(VEC_SIZE * 4), %rdi
> > + kortestd %k2, %k3
> > + jz L(loop_4x_vec)
> > # else
> > - subq $(VEC_SIZE * 4), %rdx
> > + kortestd %k2, %k3
> > + jnz L(loop_4x_vec_end)
> > +
> > + subq $-(VEC_SIZE * 4), %rdi
> > +
> > + subq $(CHAR_PER_VEC * 4), %rdx
> > ja L(loop_4x_vec)
> >
> > + /* Fall through into less than 4 remaining vectors of length case.
> > + */
> > + VPCMP $0, (VEC_SIZE * 4)(%rdi), %YMMMATCH, %k0
> > + kmovd %k0, %eax
> > + addq $(VEC_SIZE * 3), %rdi
> > + .p2align 4
> > L(last_4x_vec_or_less):
> > - /* Less than 4 * VEC and aligned to VEC_SIZE. */
> > - addl $(VEC_SIZE * 2), %edx
> > - jle L(last_2x_vec)
> > -
> > - VPCMP $0, (%rdi), %YMMMATCH, %k1
> > - kmovd %k1, %eax
> > + /* Check if first VEC contained match. */
> > testl %eax, %eax
> > - jnz L(first_vec_x0)
> > + jnz L(first_vec_x1_check)
> >
> > - VPCMP $0, VEC_SIZE(%rdi), %YMMMATCH, %k1
> > - kmovd %k1, %eax
> > - testl %eax, %eax
> > - jnz L(first_vec_x1)
> > + /* If remaining length > CHAR_PER_VEC * 2. */
> > + addl $(CHAR_PER_VEC * 2), %edx
> > + jg L(last_4x_vec)
> >
> > - VPCMP $0, (VEC_SIZE * 2)(%rdi), %YMMMATCH, %k1
> > - kmovd %k1, %eax
> > - testl %eax, %eax
> > +L(last_2x_vec):
> > + /* If remaining length < CHAR_PER_VEC. */
> > + addl $CHAR_PER_VEC, %edx
> > + jle L(zero_end)
> >
> > - jnz L(first_vec_x2_check)
> > - subl $VEC_SIZE, %edx
> > - jle L(zero)
> > + /* Check VEC2 and compare any match with remaining length. */
> > + VPCMP $0, (VEC_SIZE * 2)(%rdi), %YMMMATCH, %k0
> > + kmovd %k0, %eax
> > + tzcntl %eax, %eax
> > + cmpl %eax, %edx
> > + jbe L(set_zero_end)
> > + leaq (VEC_SIZE * 2)(%rdi, %rax, CHAR_SIZE), %rax
> > +L(zero_end):
> > + ret
> >
> > - VPCMP $0, (VEC_SIZE * 3)(%rdi), %YMMMATCH, %k1
> > - kmovd %k1, %eax
> > - testl %eax, %eax
> >
> > - jnz L(first_vec_x3_check)
> > + .p2align 4
> > +L(first_vec_x1_check):
> > + tzcntl %eax, %eax
> > + /* Adjust length. */
> > + subl $-(CHAR_PER_VEC * 4), %edx
> > + /* Check if match within remaining length. */
> > + cmpl %eax, %edx
> > + jbe L(set_zero_end)
> > + /* NB: Multiply bytes by CHAR_SIZE to get the wchar_t count. */
> > + leaq VEC_SIZE(%rdi, %rax, CHAR_SIZE), %rax
> > + ret
> > +L(set_zero_end):
> > xorl %eax, %eax
> > ret
> >
> > .p2align 4
> > -L(last_2x_vec):
> > - addl $(VEC_SIZE * 2), %edx
> > - VPCMP $0, (%rdi), %YMMMATCH, %k1
> > +L(loop_4x_vec_end):
> > +# endif
> > + /* rawmemchr will fall through into this if match was found in
> > + loop. */
> > +
> > + /* k1 has not of matches with VEC1. */
> > kmovd %k1, %eax
> > - testl %eax, %eax
> > +# ifdef USE_AS_WMEMCHR
> > + subl $((1 << CHAR_PER_VEC) - 1), %eax
> > +# else
> > + incl %eax
> > +# endif
> > + jnz L(last_vec_x1_return)
> >
> > - jnz L(first_vec_x0_check)
> > - subl $VEC_SIZE, %edx
> > - jle L(zero)
> > + VPCMP $0, %YMM2, %YZERO, %k0
> > + kmovd %k0, %eax
> > + testl %eax, %eax
> > + jnz L(last_vec_x2_return)
> >
> > - VPCMP $0, VEC_SIZE(%rdi), %YMMMATCH, %k1
> > - kmovd %k1, %eax
> > + kmovd %k2, %eax
> > testl %eax, %eax
> > - jnz L(first_vec_x1_check)
> > - xorl %eax, %eax
> > - ret
> > + jnz L(last_vec_x3_return)
> >
> > - .p2align 4
> > -L(first_vec_x0_check):
> > + kmovd %k3, %eax
> > tzcntl %eax, %eax
> > -# ifdef USE_AS_WMEMCHR
> > - /* NB: Multiply wchar_t count by 4 to get the number of bytes. */
> > - sall $2, %eax
> > +# ifdef USE_AS_RAWMEMCHR
> > + leaq (VEC_SIZE * 3)(%rdi, %rax, CHAR_SIZE), %rax
> > +# else
> > + leaq (VEC_SIZE * 7)(%rdi, %rax, CHAR_SIZE), %rax
> > # endif
> > - /* Check the end of data. */
> > - cmpq %rax, %rdx
> > - jbe L(zero)
> > - addq %rdi, %rax
> > ret
> >
> > .p2align 4
> > -L(first_vec_x1_check):
> > +L(last_vec_x1_return):
> > tzcntl %eax, %eax
> > -# ifdef USE_AS_WMEMCHR
> > - /* NB: Multiply wchar_t count by 4 to get the number of bytes. */
> > - sall $2, %eax
> > -# endif
> > - /* Check the end of data. */
> > - cmpq %rax, %rdx
> > - jbe L(zero)
> > - addq $VEC_SIZE, %rax
> > +# ifdef USE_AS_RAWMEMCHR
> > +# ifdef USE_AS_WMEMCHR
> > + /* NB: Multiply bytes by CHAR_SIZE to get the wchar_t count. */
> > + leaq (%rdi, %rax, CHAR_SIZE), %rax
> > +# else
> > addq %rdi, %rax
> > - ret
> > -
> > - .p2align 4
> > -L(first_vec_x2_check):
> > - tzcntl %eax, %eax
> > -# ifdef USE_AS_WMEMCHR
> > - /* NB: Multiply wchar_t count by 4 to get the number of bytes. */
> > - sall $2, %eax
> > +# endif
> > +# else
> > + /* NB: Multiply bytes by CHAR_SIZE to get the wchar_t count. */
> > + leaq (VEC_SIZE * 4)(%rdi, %rax, CHAR_SIZE), %rax
> > # endif
> > - /* Check the end of data. */
> > - cmpq %rax, %rdx
> > - jbe L(zero)
> > - addq $(VEC_SIZE * 2), %rax
> > - addq %rdi, %rax
> > ret
> >
> > .p2align 4
> > -L(first_vec_x3_check):
> > +L(last_vec_x2_return):
> > tzcntl %eax, %eax
> > -# ifdef USE_AS_WMEMCHR
> > - /* NB: Multiply wchar_t count by 4 to get the number of bytes. */
> > - sall $2, %eax
> > +# ifdef USE_AS_RAWMEMCHR
> > + /* NB: Multiply bytes by CHAR_SIZE to get the wchar_t count. */
> > + leaq VEC_SIZE(%rdi, %rax, CHAR_SIZE), %rax
> > +# else
> > + /* NB: Multiply bytes by CHAR_SIZE to get the wchar_t count. */
> > + leaq (VEC_SIZE * 5)(%rdi, %rax, CHAR_SIZE), %rax
> > # endif
> > - /* Check the end of data. */
> > - cmpq %rax, %rdx
> > - jbe L(zero)
> > - addq $(VEC_SIZE * 3), %rax
> > - addq %rdi, %rax
> > ret
> >
> > .p2align 4
> > -L(zero):
> > - xorl %eax, %eax
> > - ret
> > -# endif
> > -
> > - .p2align 4
> > -L(first_vec_x0):
> > +L(last_vec_x3_return):
> > tzcntl %eax, %eax
> > -# ifdef USE_AS_WMEMCHR
> > - /* NB: Multiply wchar_t count by 4 to get the number of bytes. */
> > - leaq (%rdi, %rax, 4), %rax
> > +# ifdef USE_AS_RAWMEMCHR
> > + /* NB: Multiply bytes by CHAR_SIZE to get the wchar_t count. */
> > + leaq (VEC_SIZE * 2)(%rdi, %rax, CHAR_SIZE), %rax
> > # else
> > - addq %rdi, %rax
> > + /* NB: Multiply bytes by CHAR_SIZE to get the wchar_t count. */
> > + leaq (VEC_SIZE * 6)(%rdi, %rax, CHAR_SIZE), %rax
> > # endif
> > ret
> >
> > +
> > +# ifndef USE_AS_RAWMEMCHR
> > +L(last_4x_vec_or_less_cmpeq):
> > + VPCMP $0, (VEC_SIZE * 5)(%rdi), %YMMMATCH, %k0
> > + kmovd %k0, %eax
> > + subq $-(VEC_SIZE * 4), %rdi
> > + /* Check first VEC regardless. */
> > + testl %eax, %eax
> > + jnz L(first_vec_x1_check)
> > +
> > + /* If remaining length <= CHAR_PER_VEC * 2. */
> > + addl $(CHAR_PER_VEC * 2), %edx
> > + jle L(last_2x_vec)
> > +
> > .p2align 4
> > -L(first_vec_x1):
> > +L(last_4x_vec):
> > + VPCMP $0, (VEC_SIZE * 2)(%rdi), %YMMMATCH, %k0
> > + kmovd %k0, %eax
> > + testl %eax, %eax
> > + jnz L(last_vec_x2)
> > +
> > +
> > + VPCMP $0, (VEC_SIZE * 3)(%rdi), %YMMMATCH, %k0
> > + kmovd %k0, %eax
> > + /* Create mask for possible matches within remaining length. */
> > +# ifdef USE_AS_WMEMCHR
> > + movl $((1 << (CHAR_PER_VEC * 2)) - 1), %ecx
> > + bzhil %edx, %ecx, %ecx
> > +# else
> > + movq $-1, %rcx
> > + bzhiq %rdx, %rcx, %rcx
> > +# endif
> > + /* Test matches in data against length match. */
> > + andl %ecx, %eax
> > + jnz L(last_vec_x3)
> > +
> > + /* if remaining length <= CHAR_PER_VEC * 3 (Note this is after
> > + remaining length was found to be > CHAR_PER_VEC * 2. */
> > + subl $CHAR_PER_VEC, %edx
> > + jbe L(zero_end2)
> > +
> > +
> > + VPCMP $0, (VEC_SIZE * 4)(%rdi), %YMMMATCH, %k0
> > + kmovd %k0, %eax
> > + /* Shift remaining length mask for last VEC. */
> > +# ifdef USE_AS_WMEMCHR
> > + shrl $CHAR_PER_VEC, %ecx
> > +# else
> > + shrq $CHAR_PER_VEC, %rcx
> > +# endif
> > + andl %ecx, %eax
> > + jz L(zero_end2)
> > tzcntl %eax, %eax
> > -# ifdef USE_AS_WMEMCHR
> > - /* NB: Multiply wchar_t count by 4 to get the number of bytes. */
> > - leaq VEC_SIZE(%rdi, %rax, 4), %rax
> > -# else
> > - addq $VEC_SIZE, %rax
> > - addq %rdi, %rax
> > -# endif
> > + leaq (VEC_SIZE * 4)(%rdi, %rax, CHAR_SIZE), %rax
> > +L(zero_end2):
> > ret
> >
> > - .p2align 4
> > -L(first_vec_x2):
> > +L(last_vec_x2):
> > tzcntl %eax, %eax
> > -# ifdef USE_AS_WMEMCHR
> > - /* NB: Multiply wchar_t count by 4 to get the number of bytes. */
> > - leaq (VEC_SIZE * 2)(%rdi, %rax, 4), %rax
> > -# else
> > - addq $(VEC_SIZE * 2), %rax
> > - addq %rdi, %rax
> > -# endif
> > + leaq (VEC_SIZE * 2)(%rdi, %rax, CHAR_SIZE), %rax
> > ret
> >
> > .p2align 4
> > -L(4x_vec_end):
> > - kmovd %k1, %eax
> > - testl %eax, %eax
> > - jnz L(first_vec_x0)
> > - kmovd %k2, %eax
> > - testl %eax, %eax
> > - jnz L(first_vec_x1)
> > - kmovd %k3, %eax
> > - testl %eax, %eax
> > - jnz L(first_vec_x2)
> > - kmovd %k4, %eax
> > - testl %eax, %eax
> > -L(first_vec_x3):
> > +L(last_vec_x3):
> > tzcntl %eax, %eax
> > -# ifdef USE_AS_WMEMCHR
> > - /* NB: Multiply wchar_t count by 4 to get the number of bytes. */
> > - leaq (VEC_SIZE * 3)(%rdi, %rax, 4), %rax
> > -# else
> > - addq $(VEC_SIZE * 3), %rax
> > - addq %rdi, %rax
> > -# endif
> > + leaq (VEC_SIZE * 3)(%rdi, %rax, CHAR_SIZE), %rax
> > ret
> > +# endif
> >
> > END (MEMCHR)
> > #endif
> > --
> > 2.29.2
> >
@@ -26,14 +26,28 @@
# ifdef USE_AS_WMEMCHR
# define VPBROADCAST vpbroadcastd
-# define VPCMP vpcmpd
-# define SHIFT_REG r8d
+# define VPMINU vpminud
+# define VPCMP vpcmpd
+# define VPCMPEQ vpcmpeqd
+# define CHAR_SIZE 4
# else
# define VPBROADCAST vpbroadcastb
-# define VPCMP vpcmpb
-# define SHIFT_REG ecx
+# define VPMINU vpminub
+# define VPCMP vpcmpb
+# define VPCMPEQ vpcmpeqb
+# define CHAR_SIZE 1
# endif
+# ifdef USE_AS_RAWMEMCHR
+# define RAW_PTR_REG rcx
+# define ALGN_PTR_REG rdi
+# else
+# define RAW_PTR_REG rdi
+# define ALGN_PTR_REG rcx
+# endif
+
+# define XZERO xmm23
+# define YZERO ymm23
# define XMMMATCH xmm16
# define YMMMATCH ymm16
# define YMM1 ymm17
@@ -44,6 +58,8 @@
# define YMM6 ymm22
# define VEC_SIZE 32
+# define CHAR_PER_VEC (VEC_SIZE / CHAR_SIZE)
+# define PAGE_SIZE 4096
.section .text.evex,"ax",@progbits
ENTRY (MEMCHR)
@@ -51,11 +67,7 @@ ENTRY (MEMCHR)
/* Check for zero length. */
test %RDX_LP, %RDX_LP
jz L(zero)
-# endif
- movl %edi, %ecx
-# ifdef USE_AS_WMEMCHR
- shl $2, %RDX_LP
-# else
+
# ifdef __ILP32__
/* Clear the upper 32 bits. */
movl %edx, %edx
@@ -64,318 +76,403 @@ ENTRY (MEMCHR)
/* Broadcast CHAR to YMMMATCH. */
VPBROADCAST %esi, %YMMMATCH
/* 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)
+ movl %edi, %eax
+ andl $(PAGE_SIZE - 1), %eax
+ cmpl $(PAGE_SIZE - VEC_SIZE), %eax
+ ja L(cross_page_boundary)
/* Check the first VEC_SIZE bytes. */
- VPCMP $0, (%rdi), %YMMMATCH, %k1
- kmovd %k1, %eax
- testl %eax, %eax
-
+ VPCMP $0, (%rdi), %YMMMATCH, %k0
+ kmovd %k0, %eax
# ifndef USE_AS_RAWMEMCHR
- jnz L(first_vec_x0_check)
- /* Adjust length and check the end of data. */
- subq $VEC_SIZE, %rdx
- jbe L(zero)
+ /* If length < CHAR_PER_VEC handle special. */
+ cmpq $CHAR_PER_VEC, %rdx
+ jbe L(first_vec_x0)
+# endif
+ testl %eax, %eax
+ jz L(aligned_more)
+ tzcntl %eax, %eax
+# ifdef USE_AS_WMEMCHR
+ /* NB: Multiply bytes by CHAR_SIZE to get the wchar_t count. */
+ leaq (%rdi, %rax, CHAR_SIZE), %rax
# else
- jnz L(first_vec_x0)
+ addq %rdi, %rax
# endif
-
- /* Align data for aligned loads in the loop. */
- addq $VEC_SIZE, %rdi
- andl $(VEC_SIZE - 1), %ecx
- andq $-VEC_SIZE, %rdi
+ ret
# ifndef USE_AS_RAWMEMCHR
- /* Adjust length. */
- addq %rcx, %rdx
-
- subq $(VEC_SIZE * 4), %rdx
- jbe L(last_4x_vec_or_less)
-# endif
- jmp L(more_4x_vec)
+L(zero):
+ xorl %eax, %eax
+ ret
+ .p2align 5
+L(first_vec_x0):
+ /* Check if first match was before length. */
+ tzcntl %eax, %eax
+ xorl %ecx, %ecx
+ cmpl %eax, %edx
+ leaq (%rdi, %rax, CHAR_SIZE), %rax
+ cmovle %rcx, %rax
+ ret
+# else
+ /* NB: first_vec_x0 is 17 bytes which will leave
+ cross_page_boundary (which is relatively cold) close enough
+ to ideal alignment. So only realign L(cross_page_boundary) if
+ rawmemchr. */
.p2align 4
-L(cros_page_boundary):
- andl $(VEC_SIZE - 1), %ecx
+# endif
+L(cross_page_boundary):
+ /* Save pointer before aligning as its original value is
+ necessary for computer return address if byte is found or
+ adjusting length if it is not and this is memchr. */
+ movq %rdi, %rcx
+ /* Align data to VEC_SIZE. ALGN_PTR_REG is rcx for memchr and rdi
+ for rawmemchr. */
+ andq $-VEC_SIZE, %ALGN_PTR_REG
+ VPCMP $0, (%ALGN_PTR_REG), %YMMMATCH, %k0
+ kmovd %k0, %r8d
# ifdef USE_AS_WMEMCHR
- /* NB: Divide shift count by 4 since each bit in K1 represent 4
+ /* NB: Divide shift count by 4 since each bit in K0 represent 4
bytes. */
- movl %ecx, %SHIFT_REG
- sarl $2, %SHIFT_REG
+ sarl $2, %eax
+# endif
+# ifndef USE_AS_RAWMEMCHR
+ movl $(PAGE_SIZE / CHAR_SIZE), %esi
+ subl %eax, %esi
# endif
- andq $-VEC_SIZE, %rdi
- VPCMP $0, (%rdi), %YMMMATCH, %k1
- kmovd %k1, %eax
- /* Remove the leading bytes. */
- sarxl %SHIFT_REG, %eax, %eax
- testl %eax, %eax
- jz L(aligned_more)
- tzcntl %eax, %eax
# ifdef USE_AS_WMEMCHR
- /* NB: Multiply wchar_t count by 4 to get the number of bytes. */
- sall $2, %eax
+ andl $(CHAR_PER_VEC - 1), %eax
# endif
+ /* Remove the leading bytes. */
+ sarxl %eax, %r8d, %eax
# ifndef USE_AS_RAWMEMCHR
/* Check the end of data. */
- cmpq %rax, %rdx
- jbe L(zero)
+ cmpq %rsi, %rdx
+ jbe L(first_vec_x0)
+# endif
+ testl %eax, %eax
+ jz L(cross_page_continue)
+ tzcntl %eax, %eax
+# ifdef USE_AS_WMEMCHR
+ /* NB: Multiply bytes by CHAR_SIZE to get the wchar_t count. */
+ leaq (%RAW_PTR_REG, %rax, CHAR_SIZE), %rax
+# else
+ addq %RAW_PTR_REG, %rax
# endif
- addq %rdi, %rax
- addq %rcx, %rax
ret
.p2align 4
-L(aligned_more):
-# ifndef USE_AS_RAWMEMCHR
- /* Calculate "rdx + rcx - VEC_SIZE" with "rdx - (VEC_SIZE - rcx)"
- instead of "(rdx + rcx) - VEC_SIZE" to void possible addition
- overflow. */
- negq %rcx
- addq $VEC_SIZE, %rcx
+L(first_vec_x1):
+ tzcntl %eax, %eax
+ leaq VEC_SIZE(%rdi, %rax, CHAR_SIZE), %rax
+ ret
- /* Check the end of data. */
- subq %rcx, %rdx
- jbe L(zero)
-# endif
+ .p2align 4
+L(first_vec_x2):
+ tzcntl %eax, %eax
+ leaq (VEC_SIZE * 2)(%rdi, %rax, CHAR_SIZE), %rax
+ ret
- addq $VEC_SIZE, %rdi
+ .p2align 4
+L(first_vec_x3):
+ tzcntl %eax, %eax
+ leaq (VEC_SIZE * 3)(%rdi, %rax, CHAR_SIZE), %rax
+ ret
-# ifndef USE_AS_RAWMEMCHR
- subq $(VEC_SIZE * 4), %rdx
- jbe L(last_4x_vec_or_less)
-# endif
+ .p2align 4
+L(first_vec_x4):
+ tzcntl %eax, %eax
+ leaq (VEC_SIZE * 4)(%rdi, %rax, CHAR_SIZE), %rax
+ ret
-L(more_4x_vec):
+ .p2align 5
+L(aligned_more):
/* Check the first 4 * VEC_SIZE. Only one VEC_SIZE at a time
since data is only aligned to VEC_SIZE. */
- VPCMP $0, (%rdi), %YMMMATCH, %k1
- kmovd %k1, %eax
- testl %eax, %eax
- jnz L(first_vec_x0)
- VPCMP $0, VEC_SIZE(%rdi), %YMMMATCH, %k1
- kmovd %k1, %eax
+# ifndef USE_AS_RAWMEMCHR
+ /* Align data to VEC_SIZE. */
+L(cross_page_continue):
+ xorl %ecx, %ecx
+ subl %edi, %ecx
+ andq $-VEC_SIZE, %rdi
+ /* esi is for adjusting length to see if near the end. */
+ leal (VEC_SIZE * 5)(%rdi, %rcx), %esi
+# ifdef USE_AS_WMEMCHR
+ /* NB: Divide bytes by 4 to get the wchar_t count. */
+ sarl $2, %esi
+# endif
+# else
+ andq $-VEC_SIZE, %rdi
+L(cross_page_continue):
+# endif
+ /* Load first VEC regardless. */
+ VPCMP $0, (VEC_SIZE)(%rdi), %YMMMATCH, %k0
+ kmovd %k0, %eax
+# ifndef USE_AS_RAWMEMCHR
+ /* Adjust length. If near end handle specially. */
+ subq %rsi, %rdx
+ jbe L(last_4x_vec_or_less)
+# endif
testl %eax, %eax
jnz L(first_vec_x1)
- VPCMP $0, (VEC_SIZE * 2)(%rdi), %YMMMATCH, %k1
- kmovd %k1, %eax
+ VPCMP $0, (VEC_SIZE * 2)(%rdi), %YMMMATCH, %k0
+ kmovd %k0, %eax
testl %eax, %eax
jnz L(first_vec_x2)
- VPCMP $0, (VEC_SIZE * 3)(%rdi), %YMMMATCH, %k1
- kmovd %k1, %eax
+ VPCMP $0, (VEC_SIZE * 3)(%rdi), %YMMMATCH, %k0
+ kmovd %k0, %eax
testl %eax, %eax
jnz L(first_vec_x3)
- addq $(VEC_SIZE * 4), %rdi
+ VPCMP $0, (VEC_SIZE * 4)(%rdi), %YMMMATCH, %k0
+ kmovd %k0, %eax
+ testl %eax, %eax
+ jnz L(first_vec_x4)
+
# ifndef USE_AS_RAWMEMCHR
- subq $(VEC_SIZE * 4), %rdx
- jbe L(last_4x_vec_or_less)
-# endif
+ /* Check if at last CHAR_PER_VEC * 4 length. */
+ subq $(CHAR_PER_VEC * 4), %rdx
+ jbe L(last_4x_vec_or_less_cmpeq)
+ addq $VEC_SIZE, %rdi
- /* Align data to 4 * VEC_SIZE. */
- movq %rdi, %rcx
- andl $(4 * VEC_SIZE - 1), %ecx
+ /* Align data to VEC_SIZE * 4 for the loop and readjust length.
+ */
+# ifdef USE_AS_WMEMCHR
+ movl %edi, %ecx
andq $-(4 * VEC_SIZE), %rdi
-
-# ifndef USE_AS_RAWMEMCHR
- /* Adjust length. */
+ andl $(VEC_SIZE * 4 - 1), %ecx
+ /* NB: Divide bytes by 4 to get the wchar_t count. */
+ sarl $2, %ecx
addq %rcx, %rdx
+# else
+ addq %rdi, %rdx
+ andq $-(4 * VEC_SIZE), %rdi
+ subq %rdi, %rdx
+# endif
+# else
+ addq $VEC_SIZE, %rdi
+ andq $-(4 * VEC_SIZE), %rdi
# endif
+ vpxorq %XZERO, %XZERO, %XZERO
+
+ /* Compare 4 * VEC at a time forward. */
.p2align 4
L(loop_4x_vec):
- /* Compare 4 * VEC at a time forward. */
- VPCMP $0, (%rdi), %YMMMATCH, %k1
- VPCMP $0, VEC_SIZE(%rdi), %YMMMATCH, %k2
- kord %k1, %k2, %k5
- VPCMP $0, (VEC_SIZE * 2)(%rdi), %YMMMATCH, %k3
- VPCMP $0, (VEC_SIZE * 3)(%rdi), %YMMMATCH, %k4
-
- kord %k3, %k4, %k6
- kortestd %k5, %k6
- jnz L(4x_vec_end)
-
- addq $(VEC_SIZE * 4), %rdi
-
+ /* It would be possible to save some instructions using 4x VPCMP
+ but bottleneck on port 5 makes it not woth it. */
+ VPCMP $4, (VEC_SIZE * 4)(%rdi), %YMMMATCH, %k1
+ /* xor will set bytes match esi to zero. */
+ vpxorq (VEC_SIZE * 5)(%rdi), %YMMMATCH, %YMM2
+ vpxorq (VEC_SIZE * 6)(%rdi), %YMMMATCH, %YMM3
+ VPCMP $0, (VEC_SIZE * 7)(%rdi), %YMMMATCH, %k3
+ /* Reduce VEC2 / VEC3 with min and VEC1 with zero mask. */
+ VPMINU %YMM2, %YMM3, %YMM3 {%k1} {z}
+ VPCMP $0, %YMM3, %YZERO, %k2
# ifdef USE_AS_RAWMEMCHR
- jmp L(loop_4x_vec)
+ subq $-(VEC_SIZE * 4), %rdi
+ kortestd %k2, %k3
+ jz L(loop_4x_vec)
# else
- subq $(VEC_SIZE * 4), %rdx
+ kortestd %k2, %k3
+ jnz L(loop_4x_vec_end)
+
+ subq $-(VEC_SIZE * 4), %rdi
+
+ subq $(CHAR_PER_VEC * 4), %rdx
ja L(loop_4x_vec)
+ /* Fall through into less than 4 remaining vectors of length case.
+ */
+ VPCMP $0, (VEC_SIZE * 4)(%rdi), %YMMMATCH, %k0
+ kmovd %k0, %eax
+ addq $(VEC_SIZE * 3), %rdi
+ .p2align 4
L(last_4x_vec_or_less):
- /* Less than 4 * VEC and aligned to VEC_SIZE. */
- addl $(VEC_SIZE * 2), %edx
- jle L(last_2x_vec)
-
- VPCMP $0, (%rdi), %YMMMATCH, %k1
- kmovd %k1, %eax
+ /* Check if first VEC contained match. */
testl %eax, %eax
- jnz L(first_vec_x0)
+ jnz L(first_vec_x1_check)
- VPCMP $0, VEC_SIZE(%rdi), %YMMMATCH, %k1
- kmovd %k1, %eax
- testl %eax, %eax
- jnz L(first_vec_x1)
+ /* If remaining length > CHAR_PER_VEC * 2. */
+ addl $(CHAR_PER_VEC * 2), %edx
+ jg L(last_4x_vec)
- VPCMP $0, (VEC_SIZE * 2)(%rdi), %YMMMATCH, %k1
- kmovd %k1, %eax
- testl %eax, %eax
+L(last_2x_vec):
+ /* If remaining length < CHAR_PER_VEC. */
+ addl $CHAR_PER_VEC, %edx
+ jle L(zero_end)
- jnz L(first_vec_x2_check)
- subl $VEC_SIZE, %edx
- jle L(zero)
+ /* Check VEC2 and compare any match with remaining length. */
+ VPCMP $0, (VEC_SIZE * 2)(%rdi), %YMMMATCH, %k0
+ kmovd %k0, %eax
+ tzcntl %eax, %eax
+ cmpl %eax, %edx
+ jbe L(set_zero_end)
+ leaq (VEC_SIZE * 2)(%rdi, %rax, CHAR_SIZE), %rax
+L(zero_end):
+ ret
- VPCMP $0, (VEC_SIZE * 3)(%rdi), %YMMMATCH, %k1
- kmovd %k1, %eax
- testl %eax, %eax
- jnz L(first_vec_x3_check)
+ .p2align 4
+L(first_vec_x1_check):
+ tzcntl %eax, %eax
+ /* Adjust length. */
+ subl $-(CHAR_PER_VEC * 4), %edx
+ /* Check if match within remaining length. */
+ cmpl %eax, %edx
+ jbe L(set_zero_end)
+ /* NB: Multiply bytes by CHAR_SIZE to get the wchar_t count. */
+ leaq VEC_SIZE(%rdi, %rax, CHAR_SIZE), %rax
+ ret
+L(set_zero_end):
xorl %eax, %eax
ret
.p2align 4
-L(last_2x_vec):
- addl $(VEC_SIZE * 2), %edx
- VPCMP $0, (%rdi), %YMMMATCH, %k1
+L(loop_4x_vec_end):
+# endif
+ /* rawmemchr will fall through into this if match was found in
+ loop. */
+
+ /* k1 has not of matches with VEC1. */
kmovd %k1, %eax
- testl %eax, %eax
+# ifdef USE_AS_WMEMCHR
+ subl $((1 << CHAR_PER_VEC) - 1), %eax
+# else
+ incl %eax
+# endif
+ jnz L(last_vec_x1_return)
- jnz L(first_vec_x0_check)
- subl $VEC_SIZE, %edx
- jle L(zero)
+ VPCMP $0, %YMM2, %YZERO, %k0
+ kmovd %k0, %eax
+ testl %eax, %eax
+ jnz L(last_vec_x2_return)
- VPCMP $0, VEC_SIZE(%rdi), %YMMMATCH, %k1
- kmovd %k1, %eax
+ kmovd %k2, %eax
testl %eax, %eax
- jnz L(first_vec_x1_check)
- xorl %eax, %eax
- ret
+ jnz L(last_vec_x3_return)
- .p2align 4
-L(first_vec_x0_check):
+ kmovd %k3, %eax
tzcntl %eax, %eax
-# ifdef USE_AS_WMEMCHR
- /* NB: Multiply wchar_t count by 4 to get the number of bytes. */
- sall $2, %eax
+# ifdef USE_AS_RAWMEMCHR
+ leaq (VEC_SIZE * 3)(%rdi, %rax, CHAR_SIZE), %rax
+# else
+ leaq (VEC_SIZE * 7)(%rdi, %rax, CHAR_SIZE), %rax
# endif
- /* Check the end of data. */
- cmpq %rax, %rdx
- jbe L(zero)
- addq %rdi, %rax
ret
.p2align 4
-L(first_vec_x1_check):
+L(last_vec_x1_return):
tzcntl %eax, %eax
-# ifdef USE_AS_WMEMCHR
- /* NB: Multiply wchar_t count by 4 to get the number of bytes. */
- sall $2, %eax
-# endif
- /* Check the end of data. */
- cmpq %rax, %rdx
- jbe L(zero)
- addq $VEC_SIZE, %rax
+# ifdef USE_AS_RAWMEMCHR
+# ifdef USE_AS_WMEMCHR
+ /* NB: Multiply bytes by CHAR_SIZE to get the wchar_t count. */
+ leaq (%rdi, %rax, CHAR_SIZE), %rax
+# else
addq %rdi, %rax
- ret
-
- .p2align 4
-L(first_vec_x2_check):
- tzcntl %eax, %eax
-# ifdef USE_AS_WMEMCHR
- /* NB: Multiply wchar_t count by 4 to get the number of bytes. */
- sall $2, %eax
+# endif
+# else
+ /* NB: Multiply bytes by CHAR_SIZE to get the wchar_t count. */
+ leaq (VEC_SIZE * 4)(%rdi, %rax, CHAR_SIZE), %rax
# endif
- /* Check the end of data. */
- cmpq %rax, %rdx
- jbe L(zero)
- addq $(VEC_SIZE * 2), %rax
- addq %rdi, %rax
ret
.p2align 4
-L(first_vec_x3_check):
+L(last_vec_x2_return):
tzcntl %eax, %eax
-# ifdef USE_AS_WMEMCHR
- /* NB: Multiply wchar_t count by 4 to get the number of bytes. */
- sall $2, %eax
+# ifdef USE_AS_RAWMEMCHR
+ /* NB: Multiply bytes by CHAR_SIZE to get the wchar_t count. */
+ leaq VEC_SIZE(%rdi, %rax, CHAR_SIZE), %rax
+# else
+ /* NB: Multiply bytes by CHAR_SIZE to get the wchar_t count. */
+ leaq (VEC_SIZE * 5)(%rdi, %rax, CHAR_SIZE), %rax
# endif
- /* Check the end of data. */
- cmpq %rax, %rdx
- jbe L(zero)
- addq $(VEC_SIZE * 3), %rax
- addq %rdi, %rax
ret
.p2align 4
-L(zero):
- xorl %eax, %eax
- ret
-# endif
-
- .p2align 4
-L(first_vec_x0):
+L(last_vec_x3_return):
tzcntl %eax, %eax
-# ifdef USE_AS_WMEMCHR
- /* NB: Multiply wchar_t count by 4 to get the number of bytes. */
- leaq (%rdi, %rax, 4), %rax
+# ifdef USE_AS_RAWMEMCHR
+ /* NB: Multiply bytes by CHAR_SIZE to get the wchar_t count. */
+ leaq (VEC_SIZE * 2)(%rdi, %rax, CHAR_SIZE), %rax
# else
- addq %rdi, %rax
+ /* NB: Multiply bytes by CHAR_SIZE to get the wchar_t count. */
+ leaq (VEC_SIZE * 6)(%rdi, %rax, CHAR_SIZE), %rax
# endif
ret
+
+# ifndef USE_AS_RAWMEMCHR
+L(last_4x_vec_or_less_cmpeq):
+ VPCMP $0, (VEC_SIZE * 5)(%rdi), %YMMMATCH, %k0
+ kmovd %k0, %eax
+ subq $-(VEC_SIZE * 4), %rdi
+ /* Check first VEC regardless. */
+ testl %eax, %eax
+ jnz L(first_vec_x1_check)
+
+ /* If remaining length <= CHAR_PER_VEC * 2. */
+ addl $(CHAR_PER_VEC * 2), %edx
+ jle L(last_2x_vec)
+
.p2align 4
-L(first_vec_x1):
+L(last_4x_vec):
+ VPCMP $0, (VEC_SIZE * 2)(%rdi), %YMMMATCH, %k0
+ kmovd %k0, %eax
+ testl %eax, %eax
+ jnz L(last_vec_x2)
+
+
+ VPCMP $0, (VEC_SIZE * 3)(%rdi), %YMMMATCH, %k0
+ kmovd %k0, %eax
+ /* Create mask for possible matches within remaining length. */
+# ifdef USE_AS_WMEMCHR
+ movl $((1 << (CHAR_PER_VEC * 2)) - 1), %ecx
+ bzhil %edx, %ecx, %ecx
+# else
+ movq $-1, %rcx
+ bzhiq %rdx, %rcx, %rcx
+# endif
+ /* Test matches in data against length match. */
+ andl %ecx, %eax
+ jnz L(last_vec_x3)
+
+ /* if remaining length <= CHAR_PER_VEC * 3 (Note this is after
+ remaining length was found to be > CHAR_PER_VEC * 2. */
+ subl $CHAR_PER_VEC, %edx
+ jbe L(zero_end2)
+
+
+ VPCMP $0, (VEC_SIZE * 4)(%rdi), %YMMMATCH, %k0
+ kmovd %k0, %eax
+ /* Shift remaining length mask for last VEC. */
+# ifdef USE_AS_WMEMCHR
+ shrl $CHAR_PER_VEC, %ecx
+# else
+ shrq $CHAR_PER_VEC, %rcx
+# endif
+ andl %ecx, %eax
+ jz L(zero_end2)
tzcntl %eax, %eax
-# ifdef USE_AS_WMEMCHR
- /* NB: Multiply wchar_t count by 4 to get the number of bytes. */
- leaq VEC_SIZE(%rdi, %rax, 4), %rax
-# else
- addq $VEC_SIZE, %rax
- addq %rdi, %rax
-# endif
+ leaq (VEC_SIZE * 4)(%rdi, %rax, CHAR_SIZE), %rax
+L(zero_end2):
ret
- .p2align 4
-L(first_vec_x2):
+L(last_vec_x2):
tzcntl %eax, %eax
-# ifdef USE_AS_WMEMCHR
- /* NB: Multiply wchar_t count by 4 to get the number of bytes. */
- leaq (VEC_SIZE * 2)(%rdi, %rax, 4), %rax
-# else
- addq $(VEC_SIZE * 2), %rax
- addq %rdi, %rax
-# endif
+ leaq (VEC_SIZE * 2)(%rdi, %rax, CHAR_SIZE), %rax
ret
.p2align 4
-L(4x_vec_end):
- kmovd %k1, %eax
- testl %eax, %eax
- jnz L(first_vec_x0)
- kmovd %k2, %eax
- testl %eax, %eax
- jnz L(first_vec_x1)
- kmovd %k3, %eax
- testl %eax, %eax
- jnz L(first_vec_x2)
- kmovd %k4, %eax
- testl %eax, %eax
-L(first_vec_x3):
+L(last_vec_x3):
tzcntl %eax, %eax
-# ifdef USE_AS_WMEMCHR
- /* NB: Multiply wchar_t count by 4 to get the number of bytes. */
- leaq (VEC_SIZE * 3)(%rdi, %rax, 4), %rax
-# else
- addq $(VEC_SIZE * 3), %rax
- addq %rdi, %rax
-# endif
+ leaq (VEC_SIZE * 3)(%rdi, %rax, CHAR_SIZE), %rax
ret
+# endif
END (MEMCHR)
#endif