| Message ID | 20210419184345.2576413-1-goldstein.w.n@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | [v4,1/2] x86: Optimize strlen-evex.S | expand |
On Mon, Apr 19, 2021 at 02:43:44PM -0400, Noah Goldstein wrote: > No bug. This commit optimizes strlen-evex.S. The > optimizations are mostly small things but they add up to roughly > 10-30% performance improvement for strlen. The results for strnlen are > bit more ambiguous. test-strlen, test-strnlen, test-wcslen, and > test-wcsnlen are all passing. > > Signed-off-by: Noah Goldstein <goldstein.w.n@gmail.com> > --- > sysdeps/x86_64/multiarch/strlen-evex.S | 584 ++++++++++++++----------- > 1 file changed, 320 insertions(+), 264 deletions(-) > > diff --git a/sysdeps/x86_64/multiarch/strlen-evex.S b/sysdeps/x86_64/multiarch/strlen-evex.S > index 0583819078..36b28198c8 100644 > --- a/sysdeps/x86_64/multiarch/strlen-evex.S > +++ b/sysdeps/x86_64/multiarch/strlen-evex.S > @@ -29,11 +29,13 @@ > # ifdef USE_AS_WCSLEN > # define VPCMP vpcmpd > # define VPMINU vpminud > -# define SHIFT_REG r9d > +# define SHIFT_REG ecx > +# define CHAR_SIZE 4 > # else > # define VPCMP vpcmpb > # define VPMINU vpminub > -# define SHIFT_REG ecx > +# define SHIFT_REG edx > +# define CHAR_SIZE 1 > # endif > > # define XMMZERO xmm16 > @@ -46,132 +48,168 @@ > # define YMM6 ymm22 > > # define VEC_SIZE 32 > +# define PAGE_SIZE 4096 > +# define LOG_PAGE_SIZE 12 > +# define CHAR_PER_VEC (VEC_SIZE / CHAR_SIZE) > > .section .text.evex,"ax",@progbits > ENTRY (STRLEN) > # ifdef USE_AS_STRNLEN > - /* Check for zero length. */ > + /* Check zero length. */ > test %RSI_LP, %RSI_LP > jz L(zero) > -# ifdef USE_AS_WCSLEN > - shl $2, %RSI_LP > -# elif defined __ILP32__ > +# ifdef __ILP32__ > /* Clear the upper 32 bits. */ > movl %esi, %esi > # endif > mov %RSI_LP, %R8_LP > # endif > - movl %edi, %ecx > - movq %rdi, %rdx > + movl %edi, %eax > vpxorq %XMMZERO, %XMMZERO, %XMMZERO > - > + /* Shift left eax to clear all bits not relevant to page cross > + check. This saves 2 bytes of code as opposed to using andl with > + PAGE_SIZE - 1. Then compare with PAGE_SIZE - VEC_SIZE shifted > + left by the same amount (an imm32 either way). */ > + sall $(32 - LOG_PAGE_SIZE), %eax I prefer AND over SAL for better throughput. H.J. --- > /* 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) > + cmpl $((PAGE_SIZE - VEC_SIZE) << (32 - LOG_PAGE_SIZE)), %eax > + ja L(cross_page_boundary) > > /* Check the first VEC_SIZE bytes. Each bit in K0 represents a > null byte. */ > VPCMP $0, (%rdi), %YMMZERO, %k0 > kmovd %k0, %eax > - testl %eax, %eax > - > # ifdef USE_AS_STRNLEN > - jnz L(first_vec_x0_check) > - /* Adjust length and check the end of data. */ > - subq $VEC_SIZE, %rsi > - jbe L(max) > -# else > - jnz L(first_vec_x0) > + /* If length < CHAR_PER_VEC handle special. */ > + cmpq $CHAR_PER_VEC, %rsi > + jbe L(first_vec_x0) > # endif > - > - /* Align data for aligned loads in the loop. */ > - addq $VEC_SIZE, %rdi > - andl $(VEC_SIZE - 1), %ecx > - andq $-VEC_SIZE, %rdi > - > + testl %eax, %eax > + jz L(aligned_more) > + tzcntl %eax, %eax > + ret > # ifdef USE_AS_STRNLEN > - /* Adjust length. */ > - addq %rcx, %rsi > +L(zero): > + xorl %eax, %eax > + ret > > - subq $(VEC_SIZE * 4), %rsi > - jbe L(last_4x_vec_or_less) > + .p2align 4 > +L(first_vec_x0): > + /* Set bit for max len so that tzcnt will return min of max len > + and position of first match. */ > + btsq %rsi, %rax > + tzcntl %eax, %eax > + ret > # endif > - jmp L(more_4x_vec) > > .p2align 4 > -L(cros_page_boundary): > - andl $(VEC_SIZE - 1), %ecx > - andq $-VEC_SIZE, %rdi > - > -# ifdef USE_AS_WCSLEN > - /* NB: Divide shift count by 4 since each bit in K0 represent 4 > - bytes. */ > - movl %ecx, %SHIFT_REG > - sarl $2, %SHIFT_REG > +L(first_vec_x1): > + tzcntl %eax, %eax > + /* Safe to use 32 bit instructions as these are only called for > + size = [1, 159]. */ > +# ifdef USE_AS_STRNLEN > + /* Use ecx which was computed earlier to compute correct value. > + */ > + leal -(CHAR_PER_VEC * 4 + 1)(%rcx, %rax), %eax > +# else > + subl %edx, %edi > +# ifdef USE_AS_WCSLEN > + /* NB: Divide bytes by 4 to get the wchar_t count. */ > + sarl $2, %edi > +# endif > + leal CHAR_PER_VEC(%rdi, %rax), %eax > # endif > - VPCMP $0, (%rdi), %YMMZERO, %k0 > - kmovd %k0, %eax > + ret > > - /* Remove the leading bytes. */ > - sarxl %SHIFT_REG, %eax, %eax > - testl %eax, %eax > - jz L(aligned_more) > + .p2align 4 > +L(first_vec_x2): > tzcntl %eax, %eax > -# ifdef USE_AS_WCSLEN > - /* NB: Multiply wchar_t count by 4 to get the number of bytes. */ > - sall $2, %eax > -# endif > + /* Safe to use 32 bit instructions as these are only called for > + size = [1, 159]. */ > # ifdef USE_AS_STRNLEN > - /* Check the end of data. */ > - cmpq %rax, %rsi > - jbe L(max) > -# endif > - addq %rdi, %rax > - addq %rcx, %rax > - subq %rdx, %rax > -# ifdef USE_AS_WCSLEN > - shrq $2, %rax > + /* Use ecx which was computed earlier to compute correct value. > + */ > + leal -(CHAR_PER_VEC * 3 + 1)(%rcx, %rax), %eax > +# else > + subl %edx, %edi > +# ifdef USE_AS_WCSLEN > + /* NB: Divide bytes by 4 to get the wchar_t count. */ > + sarl $2, %edi > +# endif > + leal (CHAR_PER_VEC * 2)(%rdi, %rax), %eax > # endif > ret > > .p2align 4 > -L(aligned_more): > +L(first_vec_x3): > + tzcntl %eax, %eax > + /* Safe to use 32 bit instructions as these are only called for > + size = [1, 159]. */ > # ifdef USE_AS_STRNLEN > - /* "rcx" is less than VEC_SIZE. 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 > - > - /* Check the end of data. */ > - subq %rcx, %rsi > - jbe L(max) > + /* Use ecx which was computed earlier to compute correct value. > + */ > + leal -(CHAR_PER_VEC * 2 + 1)(%rcx, %rax), %eax > +# else > + subl %edx, %edi > +# ifdef USE_AS_WCSLEN > + /* NB: Divide bytes by 4 to get the wchar_t count. */ > + sarl $2, %edi > +# endif > + leal (CHAR_PER_VEC * 3)(%rdi, %rax), %eax > # endif > + ret > > - addq $VEC_SIZE, %rdi > - > + .p2align 4 > +L(first_vec_x4): > + tzcntl %eax, %eax > + /* Safe to use 32 bit instructions as these are only called for > + size = [1, 159]. */ > # ifdef USE_AS_STRNLEN > - subq $(VEC_SIZE * 4), %rsi > - jbe L(last_4x_vec_or_less) > + /* Use ecx which was computed earlier to compute correct value. > + */ > + leal -(CHAR_PER_VEC + 1)(%rcx, %rax), %eax > +# else > + subl %edx, %edi > +# ifdef USE_AS_WCSLEN > + /* NB: Divide bytes by 4 to get the wchar_t count. */ > + sarl $2, %edi > +# endif > + leal (CHAR_PER_VEC * 4)(%rdi, %rax), %eax > # endif > + ret > > -L(more_4x_vec): > + .p2align 5 > +L(aligned_more): > + movq %rdi, %rdx > + /* Align data to VEC_SIZE. */ > + andq $-(VEC_SIZE), %rdi > +L(cross_page_continue): > /* Check the first 4 * VEC_SIZE. Only one VEC_SIZE at a time > since data is only aligned to VEC_SIZE. */ > - VPCMP $0, (%rdi), %YMMZERO, %k0 > - kmovd %k0, %eax > - testl %eax, %eax > - jnz L(first_vec_x0) > - > +# ifdef USE_AS_STRNLEN > + /* + CHAR_SIZE because it simplies the logic in > + last_4x_vec_or_less. */ > + leaq (VEC_SIZE * 5 + CHAR_SIZE)(%rdi), %rcx > + subq %rdx, %rcx > +# ifdef USE_AS_WCSLEN > + /* NB: Divide bytes by 4 to get the wchar_t count. */ > + sarl $2, %ecx > +# endif > +# endif > + /* Load first VEC regardless. */ > VPCMP $0, VEC_SIZE(%rdi), %YMMZERO, %k0 > +# ifdef USE_AS_STRNLEN > + /* Adjust length. If near end handle specially. */ > + subq %rcx, %rsi > + jb L(last_4x_vec_or_less) > +# endif > kmovd %k0, %eax > testl %eax, %eax > jnz L(first_vec_x1) > > VPCMP $0, (VEC_SIZE * 2)(%rdi), %YMMZERO, %k0 > kmovd %k0, %eax > - testl %eax, %eax > + test %eax, %eax > jnz L(first_vec_x2) > > VPCMP $0, (VEC_SIZE * 3)(%rdi), %YMMZERO, %k0 > @@ -179,258 +217,276 @@ L(more_4x_vec): > testl %eax, %eax > jnz L(first_vec_x3) > > - addq $(VEC_SIZE * 4), %rdi > - > -# ifdef USE_AS_STRNLEN > - subq $(VEC_SIZE * 4), %rsi > - jbe L(last_4x_vec_or_less) > -# endif > - > - /* Align data to 4 * VEC_SIZE. */ > - movq %rdi, %rcx > - andl $(4 * VEC_SIZE - 1), %ecx > - andq $-(4 * VEC_SIZE), %rdi > + VPCMP $0, (VEC_SIZE * 4)(%rdi), %YMMZERO, %k0 > + kmovd %k0, %eax > + testl %eax, %eax > + jnz L(first_vec_x4) > > + addq $VEC_SIZE, %rdi > # ifdef USE_AS_STRNLEN > - /* Adjust length. */ > + /* Check if at last VEC_SIZE * 4 length. */ > + cmpq $(CHAR_PER_VEC * 4 - 1), %rsi > + jbe L(last_4x_vec_or_less_load) > + movl %edi, %ecx > + andl $(VEC_SIZE * 4 - 1), %ecx > +# ifdef USE_AS_WCSLEN > + /* NB: Divide bytes by 4 to get the wchar_t count. */ > + sarl $2, %ecx > +# endif > + /* Readjust length. */ > addq %rcx, %rsi > # endif > + /* Align data to VEC_SIZE * 4. */ > + andq $-(VEC_SIZE * 4), %rdi > > + /* Compare 4 * VEC at a time forward. */ > .p2align 4 > L(loop_4x_vec): > - /* Compare 4 * VEC at a time forward. */ > - VMOVA (%rdi), %YMM1 > - VMOVA VEC_SIZE(%rdi), %YMM2 > - VMOVA (VEC_SIZE * 2)(%rdi), %YMM3 > - VMOVA (VEC_SIZE * 3)(%rdi), %YMM4 > - > - VPMINU %YMM1, %YMM2, %YMM5 > - VPMINU %YMM3, %YMM4, %YMM6 > + /* Load first VEC regardless. */ > + VMOVA (VEC_SIZE * 4)(%rdi), %YMM1 > +# ifdef USE_AS_STRNLEN > + /* Break if at end of length. */ > + subq $(CHAR_PER_VEC * 4), %rsi > + jb L(last_4x_vec_or_less_cmpeq) > +# endif > + /* Save some code size by microfusing VPMINU with the load. Since > + the matches in ymm2/ymm4 can only be returned if there where no > + matches in ymm1/ymm3 respectively there is no issue with overlap. > + */ > + VPMINU (VEC_SIZE * 5)(%rdi), %YMM1, %YMM2 > + VMOVA (VEC_SIZE * 6)(%rdi), %YMM3 > + VPMINU (VEC_SIZE * 7)(%rdi), %YMM3, %YMM4 > + > + VPCMP $0, %YMM2, %YMMZERO, %k0 > + VPCMP $0, %YMM4, %YMMZERO, %k1 > + subq $-(VEC_SIZE * 4), %rdi > + kortestd %k0, %k1 > + jz L(loop_4x_vec) > + > + /* Check if end was in first half. */ > + kmovd %k0, %eax > + subq %rdx, %rdi > +# ifdef USE_AS_WCSLEN > + shrq $2, %rdi > +# endif > + testl %eax, %eax > + jz L(second_vec_return) > > - VPMINU %YMM5, %YMM6, %YMM5 > - VPCMP $0, %YMM5, %YMMZERO, %k0 > - ktestd %k0, %k0 > - jnz L(4x_vec_end) > + VPCMP $0, %YMM1, %YMMZERO, %k2 > + kmovd %k2, %edx > + /* Combine VEC1 matches (edx) with VEC2 matches (eax). */ > +# ifdef USE_AS_WCSLEN > + sall $CHAR_PER_VEC, %eax > + orl %edx, %eax > + tzcntl %eax, %eax > +# else > + salq $CHAR_PER_VEC, %rax > + orq %rdx, %rax > + tzcntq %rax, %rax > +# endif > + addq %rdi, %rax > + ret > > - addq $(VEC_SIZE * 4), %rdi > > -# ifndef USE_AS_STRNLEN > - jmp L(loop_4x_vec) > -# else > - subq $(VEC_SIZE * 4), %rsi > - ja L(loop_4x_vec) > +# ifdef USE_AS_STRNLEN > > +L(last_4x_vec_or_less_load): > + /* Depending on entry adjust rdi / prepare first VEC in YMM1. */ > + VMOVA (VEC_SIZE * 4)(%rdi), %YMM1 > +L(last_4x_vec_or_less_cmpeq): > + VPCMP $0, %YMM1, %YMMZERO, %k0 > + addq $(VEC_SIZE * 3), %rdi > L(last_4x_vec_or_less): > - /* Less than 4 * VEC and aligned to VEC_SIZE. */ > - addl $(VEC_SIZE * 2), %esi > - jle L(last_2x_vec) > - > - VPCMP $0, (%rdi), %YMMZERO, %k0 > kmovd %k0, %eax > + /* If remaining length > VEC_SIZE * 2. This works if esi is off by > + VEC_SIZE * 4. */ > + testl $(CHAR_PER_VEC * 2), %esi > + jnz L(last_4x_vec) > + > + /* length may have been negative or positive by an offset of > + CHAR_PER_VEC * 4 depending on where this was called from. This > + fixes that. */ > + andl $(CHAR_PER_VEC * 4 - 1), %esi > testl %eax, %eax > - jnz L(first_vec_x0) > + jnz L(last_vec_x1_check) > > - VPCMP $0, VEC_SIZE(%rdi), %YMMZERO, %k0 > - kmovd %k0, %eax > - testl %eax, %eax > - jnz L(first_vec_x1) > + /* Check the end of data. */ > + subl $CHAR_PER_VEC, %esi > + jb L(max) > > VPCMP $0, (VEC_SIZE * 2)(%rdi), %YMMZERO, %k0 > kmovd %k0, %eax > - testl %eax, %eax > - jnz L(first_vec_x2_check) > - subl $VEC_SIZE, %esi > - jle L(max) > + tzcntl %eax, %eax > + /* Check the end of data. */ > + cmpl %eax, %esi > + jb L(max) > > - VPCMP $0, (VEC_SIZE * 3)(%rdi), %YMMZERO, %k0 > - kmovd %k0, %eax > - testl %eax, %eax > - jnz L(first_vec_x3_check) > + subq %rdx, %rdi > +# ifdef USE_AS_WCSLEN > + /* NB: Divide bytes by 4 to get the wchar_t count. */ > + sarq $2, %rdi > +# endif > + leaq (CHAR_PER_VEC * 2)(%rdi, %rax), %rax > + ret > +L(max): > movq %r8, %rax > + ret > +# endif > + > + /* Placed here in strnlen so that the jcc L(last_4x_vec_or_less) > + in the 4x VEC loop can use 2 byte encoding. */ > + .p2align 4 > +L(second_vec_return): > + VPCMP $0, %YMM3, %YMMZERO, %k0 > + /* Combine YMM3 matches (k0) with YMM4 matches (k1). */ > +# ifdef USE_AS_WCSLEN > + kunpckbw %k0, %k1, %k0 > + kmovd %k0, %eax > + tzcntl %eax, %eax > +# else > + kunpckdq %k0, %k1, %k0 > + kmovq %k0, %rax > + tzcntq %rax, %rax > +# endif > + leaq (CHAR_PER_VEC * 2)(%rdi, %rax), %rax > + ret > + > + > +# ifdef USE_AS_STRNLEN > +L(last_vec_x1_check): > + tzcntl %eax, %eax > + /* Check the end of data. */ > + cmpl %eax, %esi > + jb L(max) > + subq %rdx, %rdi > # ifdef USE_AS_WCSLEN > - shrq $2, %rax > + /* NB: Divide bytes by 4 to get the wchar_t count. */ > + sarq $2, %rdi > # endif > + leaq (CHAR_PER_VEC)(%rdi, %rax), %rax > ret > > .p2align 4 > -L(last_2x_vec): > - addl $(VEC_SIZE * 2), %esi > +L(last_4x_vec): > + /* Test first 2x VEC normally. */ > + testl %eax, %eax > + jnz L(last_vec_x1) > > - VPCMP $0, (%rdi), %YMMZERO, %k0 > + VPCMP $0, (VEC_SIZE * 2)(%rdi), %YMMZERO, %k0 > kmovd %k0, %eax > testl %eax, %eax > - jnz L(first_vec_x0_check) > - subl $VEC_SIZE, %esi > - jle L(max) > + jnz L(last_vec_x2) > > - VPCMP $0, VEC_SIZE(%rdi), %YMMZERO, %k0 > + /* Normalize length. */ > + andl $(CHAR_PER_VEC * 4 - 1), %esi > + VPCMP $0, (VEC_SIZE * 3)(%rdi), %YMMZERO, %k0 > kmovd %k0, %eax > testl %eax, %eax > - jnz L(first_vec_x1_check) > - movq %r8, %rax > -# ifdef USE_AS_WCSLEN > - shrq $2, %rax > -# endif > - ret > + jnz L(last_vec_x3) > > - .p2align 4 > -L(first_vec_x0_check): > + /* Check the end of data. */ > + subl $(CHAR_PER_VEC * 3), %esi > + jb L(max) > + > + VPCMP $0, (VEC_SIZE * 4)(%rdi), %YMMZERO, %k0 > + kmovd %k0, %eax > tzcntl %eax, %eax > -# ifdef USE_AS_WCSLEN > - /* NB: Multiply wchar_t count by 4 to get the number of bytes. */ > - sall $2, %eax > -# endif > /* Check the end of data. */ > - cmpq %rax, %rsi > - jbe L(max) > - addq %rdi, %rax > - subq %rdx, %rax > + cmpl %eax, %esi > + jb L(max_end) > + > + subq %rdx, %rdi > # ifdef USE_AS_WCSLEN > - shrq $2, %rax > + /* NB: Divide bytes by 4 to get the wchar_t count. */ > + sarq $2, %rdi > # endif > + leaq (CHAR_PER_VEC * 4)(%rdi, %rax), %rax > ret > > .p2align 4 > -L(first_vec_x1_check): > +L(last_vec_x1): > tzcntl %eax, %eax > + subq %rdx, %rdi > # ifdef USE_AS_WCSLEN > - /* NB: Multiply wchar_t count by 4 to get the number of bytes. */ > - sall $2, %eax > -# endif > - /* Check the end of data. */ > - cmpq %rax, %rsi > - jbe L(max) > - addq $VEC_SIZE, %rax > - addq %rdi, %rax > - subq %rdx, %rax > -# ifdef USE_AS_WCSLEN > - shrq $2, %rax > + /* NB: Divide bytes by 4 to get the wchar_t count. */ > + sarq $2, %rdi > # endif > + leaq (CHAR_PER_VEC)(%rdi, %rax), %rax > ret > > .p2align 4 > -L(first_vec_x2_check): > +L(last_vec_x2): > tzcntl %eax, %eax > + subq %rdx, %rdi > # ifdef USE_AS_WCSLEN > - /* NB: Multiply wchar_t count by 4 to get the number of bytes. */ > - sall $2, %eax > -# endif > - /* Check the end of data. */ > - cmpq %rax, %rsi > - jbe L(max) > - addq $(VEC_SIZE * 2), %rax > - addq %rdi, %rax > - subq %rdx, %rax > -# ifdef USE_AS_WCSLEN > - shrq $2, %rax > + /* NB: Divide bytes by 4 to get the wchar_t count. */ > + sarq $2, %rdi > # endif > + leaq (CHAR_PER_VEC * 2)(%rdi, %rax), %rax > ret > > .p2align 4 > -L(first_vec_x3_check): > +L(last_vec_x3): > tzcntl %eax, %eax > -# ifdef USE_AS_WCSLEN > - /* NB: Multiply wchar_t count by 4 to get the number of bytes. */ > - sall $2, %eax > -# endif > + subl $(CHAR_PER_VEC * 2), %esi > /* Check the end of data. */ > - cmpq %rax, %rsi > - jbe L(max) > - addq $(VEC_SIZE * 3), %rax > - addq %rdi, %rax > - subq %rdx, %rax > + cmpl %eax, %esi > + jb L(max_end) > + subq %rdx, %rdi > # ifdef USE_AS_WCSLEN > - shrq $2, %rax > + /* NB: Divide bytes by 4 to get the wchar_t count. */ > + sarq $2, %rdi > # endif > + leaq (CHAR_PER_VEC * 3)(%rdi, %rax), %rax > ret > - > - .p2align 4 > -L(max): > +L(max_end): > movq %r8, %rax > -# ifdef USE_AS_WCSLEN > - shrq $2, %rax > -# endif > - ret > - > - .p2align 4 > -L(zero): > - xorl %eax, %eax > ret > # endif > > + /* Cold case for crossing page with first load. */ > .p2align 4 > -L(first_vec_x0): > - tzcntl %eax, %eax > -# ifdef USE_AS_WCSLEN > - /* NB: Multiply wchar_t count by 4 to get the number of bytes. */ > - sall $2, %eax > -# endif > - addq %rdi, %rax > - subq %rdx, %rax > +L(cross_page_boundary): > + movq %rdi, %rdx > + /* Align data to VEC_SIZE. */ > + andq $-VEC_SIZE, %rdi > + VPCMP $0, (%rdi), %YMMZERO, %k0 > + kmovd %k0, %eax > + /* Remove the leading bytes. */ > # ifdef USE_AS_WCSLEN > - shrq $2, %rax > + /* NB: Divide shift count by 4 since each bit in K0 represent 4 > + bytes. */ > + movl %edx, %ecx > + shrl $2, %ecx > + andl $(CHAR_PER_VEC - 1), %ecx > # endif > - ret > - > - .p2align 4 > -L(first_vec_x1): > + /* SHIFT_REG is ecx for USE_AS_WCSLEN and edx otherwise. */ > + sarxl %SHIFT_REG, %eax, %eax > + testl %eax, %eax > +# ifndef USE_AS_STRNLEN > + jz L(cross_page_continue) > tzcntl %eax, %eax > -# ifdef USE_AS_WCSLEN > - /* NB: Multiply wchar_t count by 4 to get the number of bytes. */ > - sall $2, %eax > -# endif > - addq $VEC_SIZE, %rax > - addq %rdi, %rax > - subq %rdx, %rax > -# ifdef USE_AS_WCSLEN > - shrq $2, %rax > -# endif > ret > - > - .p2align 4 > -L(first_vec_x2): > - tzcntl %eax, %eax > -# ifdef USE_AS_WCSLEN > - /* NB: Multiply wchar_t count by 4 to get the number of bytes. */ > - sall $2, %eax > -# endif > - addq $(VEC_SIZE * 2), %rax > - addq %rdi, %rax > - subq %rdx, %rax > -# ifdef USE_AS_WCSLEN > - shrq $2, %rax > -# endif > +# else > + jnz L(cross_page_less_vec) > +# ifndef USE_AS_WCSLEN > + movl %edx, %ecx > + andl $(CHAR_PER_VEC - 1), %ecx > +# endif > + movl $CHAR_PER_VEC, %eax > + subl %ecx, %eax > + /* Check the end of data. */ > + cmpq %rax, %rsi > + ja L(cross_page_continue) > + movl %esi, %eax > ret > - > - .p2align 4 > -L(4x_vec_end): > - VPCMP $0, %YMM1, %YMMZERO, %k0 > - kmovd %k0, %eax > - testl %eax, %eax > - jnz L(first_vec_x0) > - VPCMP $0, %YMM2, %YMMZERO, %k1 > - kmovd %k1, %eax > - testl %eax, %eax > - jnz L(first_vec_x1) > - VPCMP $0, %YMM3, %YMMZERO, %k2 > - kmovd %k2, %eax > - testl %eax, %eax > - jnz L(first_vec_x2) > - VPCMP $0, %YMM4, %YMMZERO, %k3 > - kmovd %k3, %eax > -L(first_vec_x3): > +L(cross_page_less_vec): > tzcntl %eax, %eax > -# ifdef USE_AS_WCSLEN > - /* NB: Multiply wchar_t count by 4 to get the number of bytes. */ > - sall $2, %eax > -# endif > - addq $(VEC_SIZE * 3), %rax > - addq %rdi, %rax > - subq %rdx, %rax > -# ifdef USE_AS_WCSLEN > - shrq $2, %rax > -# endif > + /* Select min of length and position of first null. */ > + cmpq %rax, %rsi > + cmovb %esi, %eax > ret > +# endif > > END (STRLEN) > #endif > -- > 2.29.2 >
On Mon, Apr 19, 2021 at 6:16 PM H.J. Lu <hjl.tools@gmail.com> wrote: > > On Mon, Apr 19, 2021 at 02:43:44PM -0400, Noah Goldstein wrote: > > No bug. This commit optimizes strlen-evex.S. The > > optimizations are mostly small things but they add up to roughly > > 10-30% performance improvement for strlen. The results for strnlen are > > bit more ambiguous. test-strlen, test-strnlen, test-wcslen, and > > test-wcsnlen are all passing. > > > > Signed-off-by: Noah Goldstein <goldstein.w.n@gmail.com> > > --- > > sysdeps/x86_64/multiarch/strlen-evex.S | 584 ++++++++++++++----------- > > 1 file changed, 320 insertions(+), 264 deletions(-) > > > > diff --git a/sysdeps/x86_64/multiarch/strlen-evex.S b/sysdeps/x86_64/multiarch/strlen-evex.S > > index 0583819078..36b28198c8 100644 > > --- a/sysdeps/x86_64/multiarch/strlen-evex.S > > +++ b/sysdeps/x86_64/multiarch/strlen-evex.S > > @@ -29,11 +29,13 @@ > > # ifdef USE_AS_WCSLEN > > # define VPCMP vpcmpd > > # define VPMINU vpminud > > -# define SHIFT_REG r9d > > +# define SHIFT_REG ecx > > +# define CHAR_SIZE 4 > > # else > > # define VPCMP vpcmpb > > # define VPMINU vpminub > > -# define SHIFT_REG ecx > > +# define SHIFT_REG edx > > +# define CHAR_SIZE 1 > > # endif > > > > # define XMMZERO xmm16 > > @@ -46,132 +48,168 @@ > > # define YMM6 ymm22 > > > > # define VEC_SIZE 32 > > +# define PAGE_SIZE 4096 > > +# define LOG_PAGE_SIZE 12 > > +# define CHAR_PER_VEC (VEC_SIZE / CHAR_SIZE) > > > > .section .text.evex,"ax",@progbits > > ENTRY (STRLEN) > > # ifdef USE_AS_STRNLEN > > - /* Check for zero length. */ > > + /* Check zero length. */ > > test %RSI_LP, %RSI_LP > > jz L(zero) > > -# ifdef USE_AS_WCSLEN > > - shl $2, %RSI_LP > > -# elif defined __ILP32__ > > +# ifdef __ILP32__ > > /* Clear the upper 32 bits. */ > > movl %esi, %esi > > # endif > > mov %RSI_LP, %R8_LP > > # endif > > - movl %edi, %ecx > > - movq %rdi, %rdx > > + movl %edi, %eax > > vpxorq %XMMZERO, %XMMZERO, %XMMZERO > > - > > + /* Shift left eax to clear all bits not relevant to page cross > > + check. This saves 2 bytes of code as opposed to using andl with > > + PAGE_SIZE - 1. Then compare with PAGE_SIZE - VEC_SIZE shifted > > + left by the same amount (an imm32 either way). */ > > + sall $(32 - LOG_PAGE_SIZE), %eax > > I prefer AND over SAL for better throughput. Done. > > > H.J. > --- > > /* 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) > > + cmpl $((PAGE_SIZE - VEC_SIZE) << (32 - LOG_PAGE_SIZE)), %eax > > + ja L(cross_page_boundary) > > > > /* Check the first VEC_SIZE bytes. Each bit in K0 represents a > > null byte. */ > > VPCMP $0, (%rdi), %YMMZERO, %k0 > > kmovd %k0, %eax > > - testl %eax, %eax > > - > > # ifdef USE_AS_STRNLEN > > - jnz L(first_vec_x0_check) > > - /* Adjust length and check the end of data. */ > > - subq $VEC_SIZE, %rsi > > - jbe L(max) > > -# else > > - jnz L(first_vec_x0) > > + /* If length < CHAR_PER_VEC handle special. */ > > + cmpq $CHAR_PER_VEC, %rsi > > + jbe L(first_vec_x0) > > # endif > > - > > - /* Align data for aligned loads in the loop. */ > > - addq $VEC_SIZE, %rdi > > - andl $(VEC_SIZE - 1), %ecx > > - andq $-VEC_SIZE, %rdi > > - > > + testl %eax, %eax > > + jz L(aligned_more) > > + tzcntl %eax, %eax > > + ret > > # ifdef USE_AS_STRNLEN > > - /* Adjust length. */ > > - addq %rcx, %rsi > > +L(zero): > > + xorl %eax, %eax > > + ret > > > > - subq $(VEC_SIZE * 4), %rsi > > - jbe L(last_4x_vec_or_less) > > + .p2align 4 > > +L(first_vec_x0): > > + /* Set bit for max len so that tzcnt will return min of max len > > + and position of first match. */ > > + btsq %rsi, %rax > > + tzcntl %eax, %eax > > + ret > > # endif > > - jmp L(more_4x_vec) > > > > .p2align 4 > > -L(cros_page_boundary): > > - andl $(VEC_SIZE - 1), %ecx > > - andq $-VEC_SIZE, %rdi > > - > > -# ifdef USE_AS_WCSLEN > > - /* NB: Divide shift count by 4 since each bit in K0 represent 4 > > - bytes. */ > > - movl %ecx, %SHIFT_REG > > - sarl $2, %SHIFT_REG > > +L(first_vec_x1): > > + tzcntl %eax, %eax > > + /* Safe to use 32 bit instructions as these are only called for > > + size = [1, 159]. */ > > +# ifdef USE_AS_STRNLEN > > + /* Use ecx which was computed earlier to compute correct value. > > + */ > > + leal -(CHAR_PER_VEC * 4 + 1)(%rcx, %rax), %eax > > +# else > > + subl %edx, %edi > > +# ifdef USE_AS_WCSLEN > > + /* NB: Divide bytes by 4 to get the wchar_t count. */ > > + sarl $2, %edi > > +# endif > > + leal CHAR_PER_VEC(%rdi, %rax), %eax > > # endif > > - VPCMP $0, (%rdi), %YMMZERO, %k0 > > - kmovd %k0, %eax > > + ret > > > > - /* Remove the leading bytes. */ > > - sarxl %SHIFT_REG, %eax, %eax > > - testl %eax, %eax > > - jz L(aligned_more) > > + .p2align 4 > > +L(first_vec_x2): > > tzcntl %eax, %eax > > -# ifdef USE_AS_WCSLEN > > - /* NB: Multiply wchar_t count by 4 to get the number of bytes. */ > > - sall $2, %eax > > -# endif > > + /* Safe to use 32 bit instructions as these are only called for > > + size = [1, 159]. */ > > # ifdef USE_AS_STRNLEN > > - /* Check the end of data. */ > > - cmpq %rax, %rsi > > - jbe L(max) > > -# endif > > - addq %rdi, %rax > > - addq %rcx, %rax > > - subq %rdx, %rax > > -# ifdef USE_AS_WCSLEN > > - shrq $2, %rax > > + /* Use ecx which was computed earlier to compute correct value. > > + */ > > + leal -(CHAR_PER_VEC * 3 + 1)(%rcx, %rax), %eax > > +# else > > + subl %edx, %edi > > +# ifdef USE_AS_WCSLEN > > + /* NB: Divide bytes by 4 to get the wchar_t count. */ > > + sarl $2, %edi > > +# endif > > + leal (CHAR_PER_VEC * 2)(%rdi, %rax), %eax > > # endif > > ret > > > > .p2align 4 > > -L(aligned_more): > > +L(first_vec_x3): > > + tzcntl %eax, %eax > > + /* Safe to use 32 bit instructions as these are only called for > > + size = [1, 159]. */ > > # ifdef USE_AS_STRNLEN > > - /* "rcx" is less than VEC_SIZE. 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 > > - > > - /* Check the end of data. */ > > - subq %rcx, %rsi > > - jbe L(max) > > + /* Use ecx which was computed earlier to compute correct value. > > + */ > > + leal -(CHAR_PER_VEC * 2 + 1)(%rcx, %rax), %eax > > +# else > > + subl %edx, %edi > > +# ifdef USE_AS_WCSLEN > > + /* NB: Divide bytes by 4 to get the wchar_t count. */ > > + sarl $2, %edi > > +# endif > > + leal (CHAR_PER_VEC * 3)(%rdi, %rax), %eax > > # endif > > + ret > > > > - addq $VEC_SIZE, %rdi > > - > > + .p2align 4 > > +L(first_vec_x4): > > + tzcntl %eax, %eax > > + /* Safe to use 32 bit instructions as these are only called for > > + size = [1, 159]. */ > > # ifdef USE_AS_STRNLEN > > - subq $(VEC_SIZE * 4), %rsi > > - jbe L(last_4x_vec_or_less) > > + /* Use ecx which was computed earlier to compute correct value. > > + */ > > + leal -(CHAR_PER_VEC + 1)(%rcx, %rax), %eax > > +# else > > + subl %edx, %edi > > +# ifdef USE_AS_WCSLEN > > + /* NB: Divide bytes by 4 to get the wchar_t count. */ > > + sarl $2, %edi > > +# endif > > + leal (CHAR_PER_VEC * 4)(%rdi, %rax), %eax > > # endif > > + ret > > > > -L(more_4x_vec): > > + .p2align 5 > > +L(aligned_more): > > + movq %rdi, %rdx > > + /* Align data to VEC_SIZE. */ > > + andq $-(VEC_SIZE), %rdi > > +L(cross_page_continue): > > /* Check the first 4 * VEC_SIZE. Only one VEC_SIZE at a time > > since data is only aligned to VEC_SIZE. */ > > - VPCMP $0, (%rdi), %YMMZERO, %k0 > > - kmovd %k0, %eax > > - testl %eax, %eax > > - jnz L(first_vec_x0) > > - > > +# ifdef USE_AS_STRNLEN > > + /* + CHAR_SIZE because it simplies the logic in > > + last_4x_vec_or_less. */ > > + leaq (VEC_SIZE * 5 + CHAR_SIZE)(%rdi), %rcx > > + subq %rdx, %rcx > > +# ifdef USE_AS_WCSLEN > > + /* NB: Divide bytes by 4 to get the wchar_t count. */ > > + sarl $2, %ecx > > +# endif > > +# endif > > + /* Load first VEC regardless. */ > > VPCMP $0, VEC_SIZE(%rdi), %YMMZERO, %k0 > > +# ifdef USE_AS_STRNLEN > > + /* Adjust length. If near end handle specially. */ > > + subq %rcx, %rsi > > + jb L(last_4x_vec_or_less) > > +# endif > > kmovd %k0, %eax > > testl %eax, %eax > > jnz L(first_vec_x1) > > > > VPCMP $0, (VEC_SIZE * 2)(%rdi), %YMMZERO, %k0 > > kmovd %k0, %eax > > - testl %eax, %eax > > + test %eax, %eax > > jnz L(first_vec_x2) > > > > VPCMP $0, (VEC_SIZE * 3)(%rdi), %YMMZERO, %k0 > > @@ -179,258 +217,276 @@ L(more_4x_vec): > > testl %eax, %eax > > jnz L(first_vec_x3) > > > > - addq $(VEC_SIZE * 4), %rdi > > - > > -# ifdef USE_AS_STRNLEN > > - subq $(VEC_SIZE * 4), %rsi > > - jbe L(last_4x_vec_or_less) > > -# endif > > - > > - /* Align data to 4 * VEC_SIZE. */ > > - movq %rdi, %rcx > > - andl $(4 * VEC_SIZE - 1), %ecx > > - andq $-(4 * VEC_SIZE), %rdi > > + VPCMP $0, (VEC_SIZE * 4)(%rdi), %YMMZERO, %k0 > > + kmovd %k0, %eax > > + testl %eax, %eax > > + jnz L(first_vec_x4) > > > > + addq $VEC_SIZE, %rdi > > # ifdef USE_AS_STRNLEN > > - /* Adjust length. */ > > + /* Check if at last VEC_SIZE * 4 length. */ > > + cmpq $(CHAR_PER_VEC * 4 - 1), %rsi > > + jbe L(last_4x_vec_or_less_load) > > + movl %edi, %ecx > > + andl $(VEC_SIZE * 4 - 1), %ecx > > +# ifdef USE_AS_WCSLEN > > + /* NB: Divide bytes by 4 to get the wchar_t count. */ > > + sarl $2, %ecx > > +# endif > > + /* Readjust length. */ > > addq %rcx, %rsi > > # endif > > + /* Align data to VEC_SIZE * 4. */ > > + andq $-(VEC_SIZE * 4), %rdi > > > > + /* Compare 4 * VEC at a time forward. */ > > .p2align 4 > > L(loop_4x_vec): > > - /* Compare 4 * VEC at a time forward. */ > > - VMOVA (%rdi), %YMM1 > > - VMOVA VEC_SIZE(%rdi), %YMM2 > > - VMOVA (VEC_SIZE * 2)(%rdi), %YMM3 > > - VMOVA (VEC_SIZE * 3)(%rdi), %YMM4 > > - > > - VPMINU %YMM1, %YMM2, %YMM5 > > - VPMINU %YMM3, %YMM4, %YMM6 > > + /* Load first VEC regardless. */ > > + VMOVA (VEC_SIZE * 4)(%rdi), %YMM1 > > +# ifdef USE_AS_STRNLEN > > + /* Break if at end of length. */ > > + subq $(CHAR_PER_VEC * 4), %rsi > > + jb L(last_4x_vec_or_less_cmpeq) > > +# endif > > + /* Save some code size by microfusing VPMINU with the load. Since > > + the matches in ymm2/ymm4 can only be returned if there where no > > + matches in ymm1/ymm3 respectively there is no issue with overlap. > > + */ > > + VPMINU (VEC_SIZE * 5)(%rdi), %YMM1, %YMM2 > > + VMOVA (VEC_SIZE * 6)(%rdi), %YMM3 > > + VPMINU (VEC_SIZE * 7)(%rdi), %YMM3, %YMM4 > > + > > + VPCMP $0, %YMM2, %YMMZERO, %k0 > > + VPCMP $0, %YMM4, %YMMZERO, %k1 > > + subq $-(VEC_SIZE * 4), %rdi > > + kortestd %k0, %k1 > > + jz L(loop_4x_vec) > > + > > + /* Check if end was in first half. */ > > + kmovd %k0, %eax > > + subq %rdx, %rdi > > +# ifdef USE_AS_WCSLEN > > + shrq $2, %rdi > > +# endif > > + testl %eax, %eax > > + jz L(second_vec_return) > > > > - VPMINU %YMM5, %YMM6, %YMM5 > > - VPCMP $0, %YMM5, %YMMZERO, %k0 > > - ktestd %k0, %k0 > > - jnz L(4x_vec_end) > > + VPCMP $0, %YMM1, %YMMZERO, %k2 > > + kmovd %k2, %edx > > + /* Combine VEC1 matches (edx) with VEC2 matches (eax). */ > > +# ifdef USE_AS_WCSLEN > > + sall $CHAR_PER_VEC, %eax > > + orl %edx, %eax > > + tzcntl %eax, %eax > > +# else > > + salq $CHAR_PER_VEC, %rax > > + orq %rdx, %rax > > + tzcntq %rax, %rax > > +# endif > > + addq %rdi, %rax > > + ret > > > > - addq $(VEC_SIZE * 4), %rdi > > > > -# ifndef USE_AS_STRNLEN > > - jmp L(loop_4x_vec) > > -# else > > - subq $(VEC_SIZE * 4), %rsi > > - ja L(loop_4x_vec) > > +# ifdef USE_AS_STRNLEN > > > > +L(last_4x_vec_or_less_load): > > + /* Depending on entry adjust rdi / prepare first VEC in YMM1. */ > > + VMOVA (VEC_SIZE * 4)(%rdi), %YMM1 > > +L(last_4x_vec_or_less_cmpeq): > > + VPCMP $0, %YMM1, %YMMZERO, %k0 > > + addq $(VEC_SIZE * 3), %rdi > > L(last_4x_vec_or_less): > > - /* Less than 4 * VEC and aligned to VEC_SIZE. */ > > - addl $(VEC_SIZE * 2), %esi > > - jle L(last_2x_vec) > > - > > - VPCMP $0, (%rdi), %YMMZERO, %k0 > > kmovd %k0, %eax > > + /* If remaining length > VEC_SIZE * 2. This works if esi is off by > > + VEC_SIZE * 4. */ > > + testl $(CHAR_PER_VEC * 2), %esi > > + jnz L(last_4x_vec) > > + > > + /* length may have been negative or positive by an offset of > > + CHAR_PER_VEC * 4 depending on where this was called from. This > > + fixes that. */ > > + andl $(CHAR_PER_VEC * 4 - 1), %esi > > testl %eax, %eax > > - jnz L(first_vec_x0) > > + jnz L(last_vec_x1_check) > > > > - VPCMP $0, VEC_SIZE(%rdi), %YMMZERO, %k0 > > - kmovd %k0, %eax > > - testl %eax, %eax > > - jnz L(first_vec_x1) > > + /* Check the end of data. */ > > + subl $CHAR_PER_VEC, %esi > > + jb L(max) > > > > VPCMP $0, (VEC_SIZE * 2)(%rdi), %YMMZERO, %k0 > > kmovd %k0, %eax > > - testl %eax, %eax > > - jnz L(first_vec_x2_check) > > - subl $VEC_SIZE, %esi > > - jle L(max) > > + tzcntl %eax, %eax > > + /* Check the end of data. */ > > + cmpl %eax, %esi > > + jb L(max) > > > > - VPCMP $0, (VEC_SIZE * 3)(%rdi), %YMMZERO, %k0 > > - kmovd %k0, %eax > > - testl %eax, %eax > > - jnz L(first_vec_x3_check) > > + subq %rdx, %rdi > > +# ifdef USE_AS_WCSLEN > > + /* NB: Divide bytes by 4 to get the wchar_t count. */ > > + sarq $2, %rdi > > +# endif > > + leaq (CHAR_PER_VEC * 2)(%rdi, %rax), %rax > > + ret > > +L(max): > > movq %r8, %rax > > + ret > > +# endif > > + > > + /* Placed here in strnlen so that the jcc L(last_4x_vec_or_less) > > + in the 4x VEC loop can use 2 byte encoding. */ > > + .p2align 4 > > +L(second_vec_return): > > + VPCMP $0, %YMM3, %YMMZERO, %k0 > > + /* Combine YMM3 matches (k0) with YMM4 matches (k1). */ > > +# ifdef USE_AS_WCSLEN > > + kunpckbw %k0, %k1, %k0 > > + kmovd %k0, %eax > > + tzcntl %eax, %eax > > +# else > > + kunpckdq %k0, %k1, %k0 > > + kmovq %k0, %rax > > + tzcntq %rax, %rax > > +# endif > > + leaq (CHAR_PER_VEC * 2)(%rdi, %rax), %rax > > + ret > > + > > + > > +# ifdef USE_AS_STRNLEN > > +L(last_vec_x1_check): > > + tzcntl %eax, %eax > > + /* Check the end of data. */ > > + cmpl %eax, %esi > > + jb L(max) > > + subq %rdx, %rdi > > # ifdef USE_AS_WCSLEN > > - shrq $2, %rax > > + /* NB: Divide bytes by 4 to get the wchar_t count. */ > > + sarq $2, %rdi > > # endif > > + leaq (CHAR_PER_VEC)(%rdi, %rax), %rax > > ret > > > > .p2align 4 > > -L(last_2x_vec): > > - addl $(VEC_SIZE * 2), %esi > > +L(last_4x_vec): > > + /* Test first 2x VEC normally. */ > > + testl %eax, %eax > > + jnz L(last_vec_x1) > > > > - VPCMP $0, (%rdi), %YMMZERO, %k0 > > + VPCMP $0, (VEC_SIZE * 2)(%rdi), %YMMZERO, %k0 > > kmovd %k0, %eax > > testl %eax, %eax > > - jnz L(first_vec_x0_check) > > - subl $VEC_SIZE, %esi > > - jle L(max) > > + jnz L(last_vec_x2) > > > > - VPCMP $0, VEC_SIZE(%rdi), %YMMZERO, %k0 > > + /* Normalize length. */ > > + andl $(CHAR_PER_VEC * 4 - 1), %esi > > + VPCMP $0, (VEC_SIZE * 3)(%rdi), %YMMZERO, %k0 > > kmovd %k0, %eax > > testl %eax, %eax > > - jnz L(first_vec_x1_check) > > - movq %r8, %rax > > -# ifdef USE_AS_WCSLEN > > - shrq $2, %rax > > -# endif > > - ret > > + jnz L(last_vec_x3) > > > > - .p2align 4 > > -L(first_vec_x0_check): > > + /* Check the end of data. */ > > + subl $(CHAR_PER_VEC * 3), %esi > > + jb L(max) > > + > > + VPCMP $0, (VEC_SIZE * 4)(%rdi), %YMMZERO, %k0 > > + kmovd %k0, %eax > > tzcntl %eax, %eax > > -# ifdef USE_AS_WCSLEN > > - /* NB: Multiply wchar_t count by 4 to get the number of bytes. */ > > - sall $2, %eax > > -# endif > > /* Check the end of data. */ > > - cmpq %rax, %rsi > > - jbe L(max) > > - addq %rdi, %rax > > - subq %rdx, %rax > > + cmpl %eax, %esi > > + jb L(max_end) > > + > > + subq %rdx, %rdi > > # ifdef USE_AS_WCSLEN > > - shrq $2, %rax > > + /* NB: Divide bytes by 4 to get the wchar_t count. */ > > + sarq $2, %rdi > > # endif > > + leaq (CHAR_PER_VEC * 4)(%rdi, %rax), %rax > > ret > > > > .p2align 4 > > -L(first_vec_x1_check): > > +L(last_vec_x1): > > tzcntl %eax, %eax > > + subq %rdx, %rdi > > # ifdef USE_AS_WCSLEN > > - /* NB: Multiply wchar_t count by 4 to get the number of bytes. */ > > - sall $2, %eax > > -# endif > > - /* Check the end of data. */ > > - cmpq %rax, %rsi > > - jbe L(max) > > - addq $VEC_SIZE, %rax > > - addq %rdi, %rax > > - subq %rdx, %rax > > -# ifdef USE_AS_WCSLEN > > - shrq $2, %rax > > + /* NB: Divide bytes by 4 to get the wchar_t count. */ > > + sarq $2, %rdi > > # endif > > + leaq (CHAR_PER_VEC)(%rdi, %rax), %rax > > ret > > > > .p2align 4 > > -L(first_vec_x2_check): > > +L(last_vec_x2): > > tzcntl %eax, %eax > > + subq %rdx, %rdi > > # ifdef USE_AS_WCSLEN > > - /* NB: Multiply wchar_t count by 4 to get the number of bytes. */ > > - sall $2, %eax > > -# endif > > - /* Check the end of data. */ > > - cmpq %rax, %rsi > > - jbe L(max) > > - addq $(VEC_SIZE * 2), %rax > > - addq %rdi, %rax > > - subq %rdx, %rax > > -# ifdef USE_AS_WCSLEN > > - shrq $2, %rax > > + /* NB: Divide bytes by 4 to get the wchar_t count. */ > > + sarq $2, %rdi > > # endif > > + leaq (CHAR_PER_VEC * 2)(%rdi, %rax), %rax > > ret > > > > .p2align 4 > > -L(first_vec_x3_check): > > +L(last_vec_x3): > > tzcntl %eax, %eax > > -# ifdef USE_AS_WCSLEN > > - /* NB: Multiply wchar_t count by 4 to get the number of bytes. */ > > - sall $2, %eax > > -# endif > > + subl $(CHAR_PER_VEC * 2), %esi > > /* Check the end of data. */ > > - cmpq %rax, %rsi > > - jbe L(max) > > - addq $(VEC_SIZE * 3), %rax > > - addq %rdi, %rax > > - subq %rdx, %rax > > + cmpl %eax, %esi > > + jb L(max_end) > > + subq %rdx, %rdi > > # ifdef USE_AS_WCSLEN > > - shrq $2, %rax > > + /* NB: Divide bytes by 4 to get the wchar_t count. */ > > + sarq $2, %rdi > > # endif > > + leaq (CHAR_PER_VEC * 3)(%rdi, %rax), %rax > > ret > > - > > - .p2align 4 > > -L(max): > > +L(max_end): > > movq %r8, %rax > > -# ifdef USE_AS_WCSLEN > > - shrq $2, %rax > > -# endif > > - ret > > - > > - .p2align 4 > > -L(zero): > > - xorl %eax, %eax > > ret > > # endif > > > > + /* Cold case for crossing page with first load. */ > > .p2align 4 > > -L(first_vec_x0): > > - tzcntl %eax, %eax > > -# ifdef USE_AS_WCSLEN > > - /* NB: Multiply wchar_t count by 4 to get the number of bytes. */ > > - sall $2, %eax > > -# endif > > - addq %rdi, %rax > > - subq %rdx, %rax > > +L(cross_page_boundary): > > + movq %rdi, %rdx > > + /* Align data to VEC_SIZE. */ > > + andq $-VEC_SIZE, %rdi > > + VPCMP $0, (%rdi), %YMMZERO, %k0 > > + kmovd %k0, %eax > > + /* Remove the leading bytes. */ > > # ifdef USE_AS_WCSLEN > > - shrq $2, %rax > > + /* NB: Divide shift count by 4 since each bit in K0 represent 4 > > + bytes. */ > > + movl %edx, %ecx > > + shrl $2, %ecx > > + andl $(CHAR_PER_VEC - 1), %ecx > > # endif > > - ret > > - > > - .p2align 4 > > -L(first_vec_x1): > > + /* SHIFT_REG is ecx for USE_AS_WCSLEN and edx otherwise. */ > > + sarxl %SHIFT_REG, %eax, %eax > > + testl %eax, %eax > > +# ifndef USE_AS_STRNLEN > > + jz L(cross_page_continue) > > tzcntl %eax, %eax > > -# ifdef USE_AS_WCSLEN > > - /* NB: Multiply wchar_t count by 4 to get the number of bytes. */ > > - sall $2, %eax > > -# endif > > - addq $VEC_SIZE, %rax > > - addq %rdi, %rax > > - subq %rdx, %rax > > -# ifdef USE_AS_WCSLEN > > - shrq $2, %rax > > -# endif > > ret > > - > > - .p2align 4 > > -L(first_vec_x2): > > - tzcntl %eax, %eax > > -# ifdef USE_AS_WCSLEN > > - /* NB: Multiply wchar_t count by 4 to get the number of bytes. */ > > - sall $2, %eax > > -# endif > > - addq $(VEC_SIZE * 2), %rax > > - addq %rdi, %rax > > - subq %rdx, %rax > > -# ifdef USE_AS_WCSLEN > > - shrq $2, %rax > > -# endif > > +# else > > + jnz L(cross_page_less_vec) > > +# ifndef USE_AS_WCSLEN > > + movl %edx, %ecx > > + andl $(CHAR_PER_VEC - 1), %ecx > > +# endif > > + movl $CHAR_PER_VEC, %eax > > + subl %ecx, %eax > > + /* Check the end of data. */ > > + cmpq %rax, %rsi > > + ja L(cross_page_continue) > > + movl %esi, %eax > > ret > > - > > - .p2align 4 > > -L(4x_vec_end): > > - VPCMP $0, %YMM1, %YMMZERO, %k0 > > - kmovd %k0, %eax > > - testl %eax, %eax > > - jnz L(first_vec_x0) > > - VPCMP $0, %YMM2, %YMMZERO, %k1 > > - kmovd %k1, %eax > > - testl %eax, %eax > > - jnz L(first_vec_x1) > > - VPCMP $0, %YMM3, %YMMZERO, %k2 > > - kmovd %k2, %eax > > - testl %eax, %eax > > - jnz L(first_vec_x2) > > - VPCMP $0, %YMM4, %YMMZERO, %k3 > > - kmovd %k3, %eax > > -L(first_vec_x3): > > +L(cross_page_less_vec): > > tzcntl %eax, %eax > > -# ifdef USE_AS_WCSLEN > > - /* NB: Multiply wchar_t count by 4 to get the number of bytes. */ > > - sall $2, %eax > > -# endif > > - addq $(VEC_SIZE * 3), %rax > > - addq %rdi, %rax > > - subq %rdx, %rax > > -# ifdef USE_AS_WCSLEN > > - shrq $2, %rax > > -# endif > > + /* Select min of length and position of first null. */ > > + cmpq %rax, %rsi > > + cmovb %esi, %eax > > ret > > +# endif > > > > END (STRLEN) > > #endif > > -- > > 2.29.2 > >
diff --git a/sysdeps/x86_64/multiarch/strlen-evex.S b/sysdeps/x86_64/multiarch/strlen-evex.S index 0583819078..36b28198c8 100644 --- a/sysdeps/x86_64/multiarch/strlen-evex.S +++ b/sysdeps/x86_64/multiarch/strlen-evex.S @@ -29,11 +29,13 @@ # ifdef USE_AS_WCSLEN # define VPCMP vpcmpd # define VPMINU vpminud -# define SHIFT_REG r9d +# define SHIFT_REG ecx +# define CHAR_SIZE 4 # else # define VPCMP vpcmpb # define VPMINU vpminub -# define SHIFT_REG ecx +# define SHIFT_REG edx +# define CHAR_SIZE 1 # endif # define XMMZERO xmm16 @@ -46,132 +48,168 @@ # define YMM6 ymm22 # define VEC_SIZE 32 +# define PAGE_SIZE 4096 +# define LOG_PAGE_SIZE 12 +# define CHAR_PER_VEC (VEC_SIZE / CHAR_SIZE) .section .text.evex,"ax",@progbits ENTRY (STRLEN) # ifdef USE_AS_STRNLEN - /* Check for zero length. */ + /* Check zero length. */ test %RSI_LP, %RSI_LP jz L(zero) -# ifdef USE_AS_WCSLEN - shl $2, %RSI_LP -# elif defined __ILP32__ +# ifdef __ILP32__ /* Clear the upper 32 bits. */ movl %esi, %esi # endif mov %RSI_LP, %R8_LP # endif - movl %edi, %ecx - movq %rdi, %rdx + movl %edi, %eax vpxorq %XMMZERO, %XMMZERO, %XMMZERO - + /* Shift left eax to clear all bits not relevant to page cross + check. This saves 2 bytes of code as opposed to using andl with + PAGE_SIZE - 1. Then compare with PAGE_SIZE - VEC_SIZE shifted + left by the same amount (an imm32 either way). */ + sall $(32 - LOG_PAGE_SIZE), %eax /* 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) + cmpl $((PAGE_SIZE - VEC_SIZE) << (32 - LOG_PAGE_SIZE)), %eax + ja L(cross_page_boundary) /* Check the first VEC_SIZE bytes. Each bit in K0 represents a null byte. */ VPCMP $0, (%rdi), %YMMZERO, %k0 kmovd %k0, %eax - testl %eax, %eax - # ifdef USE_AS_STRNLEN - jnz L(first_vec_x0_check) - /* Adjust length and check the end of data. */ - subq $VEC_SIZE, %rsi - jbe L(max) -# else - jnz L(first_vec_x0) + /* If length < CHAR_PER_VEC handle special. */ + cmpq $CHAR_PER_VEC, %rsi + jbe L(first_vec_x0) # endif - - /* Align data for aligned loads in the loop. */ - addq $VEC_SIZE, %rdi - andl $(VEC_SIZE - 1), %ecx - andq $-VEC_SIZE, %rdi - + testl %eax, %eax + jz L(aligned_more) + tzcntl %eax, %eax + ret # ifdef USE_AS_STRNLEN - /* Adjust length. */ - addq %rcx, %rsi +L(zero): + xorl %eax, %eax + ret - subq $(VEC_SIZE * 4), %rsi - jbe L(last_4x_vec_or_less) + .p2align 4 +L(first_vec_x0): + /* Set bit for max len so that tzcnt will return min of max len + and position of first match. */ + btsq %rsi, %rax + tzcntl %eax, %eax + ret # endif - jmp L(more_4x_vec) .p2align 4 -L(cros_page_boundary): - andl $(VEC_SIZE - 1), %ecx - andq $-VEC_SIZE, %rdi - -# ifdef USE_AS_WCSLEN - /* NB: Divide shift count by 4 since each bit in K0 represent 4 - bytes. */ - movl %ecx, %SHIFT_REG - sarl $2, %SHIFT_REG +L(first_vec_x1): + tzcntl %eax, %eax + /* Safe to use 32 bit instructions as these are only called for + size = [1, 159]. */ +# ifdef USE_AS_STRNLEN + /* Use ecx which was computed earlier to compute correct value. + */ + leal -(CHAR_PER_VEC * 4 + 1)(%rcx, %rax), %eax +# else + subl %edx, %edi +# ifdef USE_AS_WCSLEN + /* NB: Divide bytes by 4 to get the wchar_t count. */ + sarl $2, %edi +# endif + leal CHAR_PER_VEC(%rdi, %rax), %eax # endif - VPCMP $0, (%rdi), %YMMZERO, %k0 - kmovd %k0, %eax + ret - /* Remove the leading bytes. */ - sarxl %SHIFT_REG, %eax, %eax - testl %eax, %eax - jz L(aligned_more) + .p2align 4 +L(first_vec_x2): tzcntl %eax, %eax -# ifdef USE_AS_WCSLEN - /* NB: Multiply wchar_t count by 4 to get the number of bytes. */ - sall $2, %eax -# endif + /* Safe to use 32 bit instructions as these are only called for + size = [1, 159]. */ # ifdef USE_AS_STRNLEN - /* Check the end of data. */ - cmpq %rax, %rsi - jbe L(max) -# endif - addq %rdi, %rax - addq %rcx, %rax - subq %rdx, %rax -# ifdef USE_AS_WCSLEN - shrq $2, %rax + /* Use ecx which was computed earlier to compute correct value. + */ + leal -(CHAR_PER_VEC * 3 + 1)(%rcx, %rax), %eax +# else + subl %edx, %edi +# ifdef USE_AS_WCSLEN + /* NB: Divide bytes by 4 to get the wchar_t count. */ + sarl $2, %edi +# endif + leal (CHAR_PER_VEC * 2)(%rdi, %rax), %eax # endif ret .p2align 4 -L(aligned_more): +L(first_vec_x3): + tzcntl %eax, %eax + /* Safe to use 32 bit instructions as these are only called for + size = [1, 159]. */ # ifdef USE_AS_STRNLEN - /* "rcx" is less than VEC_SIZE. 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 - - /* Check the end of data. */ - subq %rcx, %rsi - jbe L(max) + /* Use ecx which was computed earlier to compute correct value. + */ + leal -(CHAR_PER_VEC * 2 + 1)(%rcx, %rax), %eax +# else + subl %edx, %edi +# ifdef USE_AS_WCSLEN + /* NB: Divide bytes by 4 to get the wchar_t count. */ + sarl $2, %edi +# endif + leal (CHAR_PER_VEC * 3)(%rdi, %rax), %eax # endif + ret - addq $VEC_SIZE, %rdi - + .p2align 4 +L(first_vec_x4): + tzcntl %eax, %eax + /* Safe to use 32 bit instructions as these are only called for + size = [1, 159]. */ # ifdef USE_AS_STRNLEN - subq $(VEC_SIZE * 4), %rsi - jbe L(last_4x_vec_or_less) + /* Use ecx which was computed earlier to compute correct value. + */ + leal -(CHAR_PER_VEC + 1)(%rcx, %rax), %eax +# else + subl %edx, %edi +# ifdef USE_AS_WCSLEN + /* NB: Divide bytes by 4 to get the wchar_t count. */ + sarl $2, %edi +# endif + leal (CHAR_PER_VEC * 4)(%rdi, %rax), %eax # endif + ret -L(more_4x_vec): + .p2align 5 +L(aligned_more): + movq %rdi, %rdx + /* Align data to VEC_SIZE. */ + andq $-(VEC_SIZE), %rdi +L(cross_page_continue): /* Check the first 4 * VEC_SIZE. Only one VEC_SIZE at a time since data is only aligned to VEC_SIZE. */ - VPCMP $0, (%rdi), %YMMZERO, %k0 - kmovd %k0, %eax - testl %eax, %eax - jnz L(first_vec_x0) - +# ifdef USE_AS_STRNLEN + /* + CHAR_SIZE because it simplies the logic in + last_4x_vec_or_less. */ + leaq (VEC_SIZE * 5 + CHAR_SIZE)(%rdi), %rcx + subq %rdx, %rcx +# ifdef USE_AS_WCSLEN + /* NB: Divide bytes by 4 to get the wchar_t count. */ + sarl $2, %ecx +# endif +# endif + /* Load first VEC regardless. */ VPCMP $0, VEC_SIZE(%rdi), %YMMZERO, %k0 +# ifdef USE_AS_STRNLEN + /* Adjust length. If near end handle specially. */ + subq %rcx, %rsi + jb L(last_4x_vec_or_less) +# endif kmovd %k0, %eax testl %eax, %eax jnz L(first_vec_x1) VPCMP $0, (VEC_SIZE * 2)(%rdi), %YMMZERO, %k0 kmovd %k0, %eax - testl %eax, %eax + test %eax, %eax jnz L(first_vec_x2) VPCMP $0, (VEC_SIZE * 3)(%rdi), %YMMZERO, %k0 @@ -179,258 +217,276 @@ L(more_4x_vec): testl %eax, %eax jnz L(first_vec_x3) - addq $(VEC_SIZE * 4), %rdi - -# ifdef USE_AS_STRNLEN - subq $(VEC_SIZE * 4), %rsi - jbe L(last_4x_vec_or_less) -# endif - - /* Align data to 4 * VEC_SIZE. */ - movq %rdi, %rcx - andl $(4 * VEC_SIZE - 1), %ecx - andq $-(4 * VEC_SIZE), %rdi + VPCMP $0, (VEC_SIZE * 4)(%rdi), %YMMZERO, %k0 + kmovd %k0, %eax + testl %eax, %eax + jnz L(first_vec_x4) + addq $VEC_SIZE, %rdi # ifdef USE_AS_STRNLEN - /* Adjust length. */ + /* Check if at last VEC_SIZE * 4 length. */ + cmpq $(CHAR_PER_VEC * 4 - 1), %rsi + jbe L(last_4x_vec_or_less_load) + movl %edi, %ecx + andl $(VEC_SIZE * 4 - 1), %ecx +# ifdef USE_AS_WCSLEN + /* NB: Divide bytes by 4 to get the wchar_t count. */ + sarl $2, %ecx +# endif + /* Readjust length. */ addq %rcx, %rsi # endif + /* Align data to VEC_SIZE * 4. */ + andq $-(VEC_SIZE * 4), %rdi + /* Compare 4 * VEC at a time forward. */ .p2align 4 L(loop_4x_vec): - /* Compare 4 * VEC at a time forward. */ - VMOVA (%rdi), %YMM1 - VMOVA VEC_SIZE(%rdi), %YMM2 - VMOVA (VEC_SIZE * 2)(%rdi), %YMM3 - VMOVA (VEC_SIZE * 3)(%rdi), %YMM4 - - VPMINU %YMM1, %YMM2, %YMM5 - VPMINU %YMM3, %YMM4, %YMM6 + /* Load first VEC regardless. */ + VMOVA (VEC_SIZE * 4)(%rdi), %YMM1 +# ifdef USE_AS_STRNLEN + /* Break if at end of length. */ + subq $(CHAR_PER_VEC * 4), %rsi + jb L(last_4x_vec_or_less_cmpeq) +# endif + /* Save some code size by microfusing VPMINU with the load. Since + the matches in ymm2/ymm4 can only be returned if there where no + matches in ymm1/ymm3 respectively there is no issue with overlap. + */ + VPMINU (VEC_SIZE * 5)(%rdi), %YMM1, %YMM2 + VMOVA (VEC_SIZE * 6)(%rdi), %YMM3 + VPMINU (VEC_SIZE * 7)(%rdi), %YMM3, %YMM4 + + VPCMP $0, %YMM2, %YMMZERO, %k0 + VPCMP $0, %YMM4, %YMMZERO, %k1 + subq $-(VEC_SIZE * 4), %rdi + kortestd %k0, %k1 + jz L(loop_4x_vec) + + /* Check if end was in first half. */ + kmovd %k0, %eax + subq %rdx, %rdi +# ifdef USE_AS_WCSLEN + shrq $2, %rdi +# endif + testl %eax, %eax + jz L(second_vec_return) - VPMINU %YMM5, %YMM6, %YMM5 - VPCMP $0, %YMM5, %YMMZERO, %k0 - ktestd %k0, %k0 - jnz L(4x_vec_end) + VPCMP $0, %YMM1, %YMMZERO, %k2 + kmovd %k2, %edx + /* Combine VEC1 matches (edx) with VEC2 matches (eax). */ +# ifdef USE_AS_WCSLEN + sall $CHAR_PER_VEC, %eax + orl %edx, %eax + tzcntl %eax, %eax +# else + salq $CHAR_PER_VEC, %rax + orq %rdx, %rax + tzcntq %rax, %rax +# endif + addq %rdi, %rax + ret - addq $(VEC_SIZE * 4), %rdi -# ifndef USE_AS_STRNLEN - jmp L(loop_4x_vec) -# else - subq $(VEC_SIZE * 4), %rsi - ja L(loop_4x_vec) +# ifdef USE_AS_STRNLEN +L(last_4x_vec_or_less_load): + /* Depending on entry adjust rdi / prepare first VEC in YMM1. */ + VMOVA (VEC_SIZE * 4)(%rdi), %YMM1 +L(last_4x_vec_or_less_cmpeq): + VPCMP $0, %YMM1, %YMMZERO, %k0 + addq $(VEC_SIZE * 3), %rdi L(last_4x_vec_or_less): - /* Less than 4 * VEC and aligned to VEC_SIZE. */ - addl $(VEC_SIZE * 2), %esi - jle L(last_2x_vec) - - VPCMP $0, (%rdi), %YMMZERO, %k0 kmovd %k0, %eax + /* If remaining length > VEC_SIZE * 2. This works if esi is off by + VEC_SIZE * 4. */ + testl $(CHAR_PER_VEC * 2), %esi + jnz L(last_4x_vec) + + /* length may have been negative or positive by an offset of + CHAR_PER_VEC * 4 depending on where this was called from. This + fixes that. */ + andl $(CHAR_PER_VEC * 4 - 1), %esi testl %eax, %eax - jnz L(first_vec_x0) + jnz L(last_vec_x1_check) - VPCMP $0, VEC_SIZE(%rdi), %YMMZERO, %k0 - kmovd %k0, %eax - testl %eax, %eax - jnz L(first_vec_x1) + /* Check the end of data. */ + subl $CHAR_PER_VEC, %esi + jb L(max) VPCMP $0, (VEC_SIZE * 2)(%rdi), %YMMZERO, %k0 kmovd %k0, %eax - testl %eax, %eax - jnz L(first_vec_x2_check) - subl $VEC_SIZE, %esi - jle L(max) + tzcntl %eax, %eax + /* Check the end of data. */ + cmpl %eax, %esi + jb L(max) - VPCMP $0, (VEC_SIZE * 3)(%rdi), %YMMZERO, %k0 - kmovd %k0, %eax - testl %eax, %eax - jnz L(first_vec_x3_check) + subq %rdx, %rdi +# ifdef USE_AS_WCSLEN + /* NB: Divide bytes by 4 to get the wchar_t count. */ + sarq $2, %rdi +# endif + leaq (CHAR_PER_VEC * 2)(%rdi, %rax), %rax + ret +L(max): movq %r8, %rax + ret +# endif + + /* Placed here in strnlen so that the jcc L(last_4x_vec_or_less) + in the 4x VEC loop can use 2 byte encoding. */ + .p2align 4 +L(second_vec_return): + VPCMP $0, %YMM3, %YMMZERO, %k0 + /* Combine YMM3 matches (k0) with YMM4 matches (k1). */ +# ifdef USE_AS_WCSLEN + kunpckbw %k0, %k1, %k0 + kmovd %k0, %eax + tzcntl %eax, %eax +# else + kunpckdq %k0, %k1, %k0 + kmovq %k0, %rax + tzcntq %rax, %rax +# endif + leaq (CHAR_PER_VEC * 2)(%rdi, %rax), %rax + ret + + +# ifdef USE_AS_STRNLEN +L(last_vec_x1_check): + tzcntl %eax, %eax + /* Check the end of data. */ + cmpl %eax, %esi + jb L(max) + subq %rdx, %rdi # ifdef USE_AS_WCSLEN - shrq $2, %rax + /* NB: Divide bytes by 4 to get the wchar_t count. */ + sarq $2, %rdi # endif + leaq (CHAR_PER_VEC)(%rdi, %rax), %rax ret .p2align 4 -L(last_2x_vec): - addl $(VEC_SIZE * 2), %esi +L(last_4x_vec): + /* Test first 2x VEC normally. */ + testl %eax, %eax + jnz L(last_vec_x1) - VPCMP $0, (%rdi), %YMMZERO, %k0 + VPCMP $0, (VEC_SIZE * 2)(%rdi), %YMMZERO, %k0 kmovd %k0, %eax testl %eax, %eax - jnz L(first_vec_x0_check) - subl $VEC_SIZE, %esi - jle L(max) + jnz L(last_vec_x2) - VPCMP $0, VEC_SIZE(%rdi), %YMMZERO, %k0 + /* Normalize length. */ + andl $(CHAR_PER_VEC * 4 - 1), %esi + VPCMP $0, (VEC_SIZE * 3)(%rdi), %YMMZERO, %k0 kmovd %k0, %eax testl %eax, %eax - jnz L(first_vec_x1_check) - movq %r8, %rax -# ifdef USE_AS_WCSLEN - shrq $2, %rax -# endif - ret + jnz L(last_vec_x3) - .p2align 4 -L(first_vec_x0_check): + /* Check the end of data. */ + subl $(CHAR_PER_VEC * 3), %esi + jb L(max) + + VPCMP $0, (VEC_SIZE * 4)(%rdi), %YMMZERO, %k0 + kmovd %k0, %eax tzcntl %eax, %eax -# ifdef USE_AS_WCSLEN - /* NB: Multiply wchar_t count by 4 to get the number of bytes. */ - sall $2, %eax -# endif /* Check the end of data. */ - cmpq %rax, %rsi - jbe L(max) - addq %rdi, %rax - subq %rdx, %rax + cmpl %eax, %esi + jb L(max_end) + + subq %rdx, %rdi # ifdef USE_AS_WCSLEN - shrq $2, %rax + /* NB: Divide bytes by 4 to get the wchar_t count. */ + sarq $2, %rdi # endif + leaq (CHAR_PER_VEC * 4)(%rdi, %rax), %rax ret .p2align 4 -L(first_vec_x1_check): +L(last_vec_x1): tzcntl %eax, %eax + subq %rdx, %rdi # ifdef USE_AS_WCSLEN - /* NB: Multiply wchar_t count by 4 to get the number of bytes. */ - sall $2, %eax -# endif - /* Check the end of data. */ - cmpq %rax, %rsi - jbe L(max) - addq $VEC_SIZE, %rax - addq %rdi, %rax - subq %rdx, %rax -# ifdef USE_AS_WCSLEN - shrq $2, %rax + /* NB: Divide bytes by 4 to get the wchar_t count. */ + sarq $2, %rdi # endif + leaq (CHAR_PER_VEC)(%rdi, %rax), %rax ret .p2align 4 -L(first_vec_x2_check): +L(last_vec_x2): tzcntl %eax, %eax + subq %rdx, %rdi # ifdef USE_AS_WCSLEN - /* NB: Multiply wchar_t count by 4 to get the number of bytes. */ - sall $2, %eax -# endif - /* Check the end of data. */ - cmpq %rax, %rsi - jbe L(max) - addq $(VEC_SIZE * 2), %rax - addq %rdi, %rax - subq %rdx, %rax -# ifdef USE_AS_WCSLEN - shrq $2, %rax + /* NB: Divide bytes by 4 to get the wchar_t count. */ + sarq $2, %rdi # endif + leaq (CHAR_PER_VEC * 2)(%rdi, %rax), %rax ret .p2align 4 -L(first_vec_x3_check): +L(last_vec_x3): tzcntl %eax, %eax -# ifdef USE_AS_WCSLEN - /* NB: Multiply wchar_t count by 4 to get the number of bytes. */ - sall $2, %eax -# endif + subl $(CHAR_PER_VEC * 2), %esi /* Check the end of data. */ - cmpq %rax, %rsi - jbe L(max) - addq $(VEC_SIZE * 3), %rax - addq %rdi, %rax - subq %rdx, %rax + cmpl %eax, %esi + jb L(max_end) + subq %rdx, %rdi # ifdef USE_AS_WCSLEN - shrq $2, %rax + /* NB: Divide bytes by 4 to get the wchar_t count. */ + sarq $2, %rdi # endif + leaq (CHAR_PER_VEC * 3)(%rdi, %rax), %rax ret - - .p2align 4 -L(max): +L(max_end): movq %r8, %rax -# ifdef USE_AS_WCSLEN - shrq $2, %rax -# endif - ret - - .p2align 4 -L(zero): - xorl %eax, %eax ret # endif + /* Cold case for crossing page with first load. */ .p2align 4 -L(first_vec_x0): - tzcntl %eax, %eax -# ifdef USE_AS_WCSLEN - /* NB: Multiply wchar_t count by 4 to get the number of bytes. */ - sall $2, %eax -# endif - addq %rdi, %rax - subq %rdx, %rax +L(cross_page_boundary): + movq %rdi, %rdx + /* Align data to VEC_SIZE. */ + andq $-VEC_SIZE, %rdi + VPCMP $0, (%rdi), %YMMZERO, %k0 + kmovd %k0, %eax + /* Remove the leading bytes. */ # ifdef USE_AS_WCSLEN - shrq $2, %rax + /* NB: Divide shift count by 4 since each bit in K0 represent 4 + bytes. */ + movl %edx, %ecx + shrl $2, %ecx + andl $(CHAR_PER_VEC - 1), %ecx # endif - ret - - .p2align 4 -L(first_vec_x1): + /* SHIFT_REG is ecx for USE_AS_WCSLEN and edx otherwise. */ + sarxl %SHIFT_REG, %eax, %eax + testl %eax, %eax +# ifndef USE_AS_STRNLEN + jz L(cross_page_continue) tzcntl %eax, %eax -# ifdef USE_AS_WCSLEN - /* NB: Multiply wchar_t count by 4 to get the number of bytes. */ - sall $2, %eax -# endif - addq $VEC_SIZE, %rax - addq %rdi, %rax - subq %rdx, %rax -# ifdef USE_AS_WCSLEN - shrq $2, %rax -# endif ret - - .p2align 4 -L(first_vec_x2): - tzcntl %eax, %eax -# ifdef USE_AS_WCSLEN - /* NB: Multiply wchar_t count by 4 to get the number of bytes. */ - sall $2, %eax -# endif - addq $(VEC_SIZE * 2), %rax - addq %rdi, %rax - subq %rdx, %rax -# ifdef USE_AS_WCSLEN - shrq $2, %rax -# endif +# else + jnz L(cross_page_less_vec) +# ifndef USE_AS_WCSLEN + movl %edx, %ecx + andl $(CHAR_PER_VEC - 1), %ecx +# endif + movl $CHAR_PER_VEC, %eax + subl %ecx, %eax + /* Check the end of data. */ + cmpq %rax, %rsi + ja L(cross_page_continue) + movl %esi, %eax ret - - .p2align 4 -L(4x_vec_end): - VPCMP $0, %YMM1, %YMMZERO, %k0 - kmovd %k0, %eax - testl %eax, %eax - jnz L(first_vec_x0) - VPCMP $0, %YMM2, %YMMZERO, %k1 - kmovd %k1, %eax - testl %eax, %eax - jnz L(first_vec_x1) - VPCMP $0, %YMM3, %YMMZERO, %k2 - kmovd %k2, %eax - testl %eax, %eax - jnz L(first_vec_x2) - VPCMP $0, %YMM4, %YMMZERO, %k3 - kmovd %k3, %eax -L(first_vec_x3): +L(cross_page_less_vec): tzcntl %eax, %eax -# ifdef USE_AS_WCSLEN - /* NB: Multiply wchar_t count by 4 to get the number of bytes. */ - sall $2, %eax -# endif - addq $(VEC_SIZE * 3), %rax - addq %rdi, %rax - subq %rdx, %rax -# ifdef USE_AS_WCSLEN - shrq $2, %rax -# endif + /* Select min of length and position of first null. */ + cmpq %rax, %rsi + cmovb %esi, %eax ret +# endif END (STRLEN) #endif
No bug. This commit optimizes strlen-evex.S. The optimizations are mostly small things but they add up to roughly 10-30% performance improvement for strlen. The results for strnlen are bit more ambiguous. test-strlen, test-strnlen, test-wcslen, and test-wcsnlen are all passing. Signed-off-by: Noah Goldstein <goldstein.w.n@gmail.com> --- sysdeps/x86_64/multiarch/strlen-evex.S | 584 ++++++++++++++----------- 1 file changed, 320 insertions(+), 264 deletions(-)