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| author | H.J. Lu <hjl.tools@gmail.com> | 2017-06-27 07:55:00 -0700 |
|---|---|---|
| committer | H.J. Lu <hjl.tools@gmail.com> | 2017-06-27 07:55:00 -0700 |
| commit | e94c31035739b693c3699b3c4cad0206631fbee7 (patch) | |
| tree | b0666d325944a10e78d4dd6333c19c108c50d74c /sysdeps | |
| parent | 6980be7cbf4f108a4936ac64242f58340d56c806 (diff) | |
| download | glibc-e94c31035739b693c3699b3c4cad0206631fbee7.tar.gz glibc-e94c31035739b693c3699b3c4cad0206631fbee7.tar.xz glibc-e94c31035739b693c3699b3c4cad0206631fbee7.zip | |
x86-64: Optimize memcmp-avx2-movbe.S for short difference
Check the first 32 bytes before checking size when size >= 32 bytes to avoid unnecessary branch if the difference is in the first 32 bytes. Replace vpmovmskb/subl/jnz with vptest/jnc. On Haswell, the new version is as fast as the previous one. On Skylake, the new version is a little bit faster. * sysdeps/x86_64/multiarch/memcmp-avx2-movbe.S (MEMCMP): Check the first 32 bytes before checking size when size >= 32 bytes. Replace vpmovmskb/subl/jnz with vptest/jnc.
Diffstat (limited to 'sysdeps')
| -rw-r--r-- | sysdeps/x86_64/multiarch/memcmp-avx2-movbe.S | 118 |
1 files changed, 62 insertions, 56 deletions
diff --git a/sysdeps/x86_64/multiarch/memcmp-avx2-movbe.S b/sysdeps/x86_64/multiarch/memcmp-avx2-movbe.S index abcc61c381..16f46301ca 100644 --- a/sysdeps/x86_64/multiarch/memcmp-avx2-movbe.S +++ b/sysdeps/x86_64/multiarch/memcmp-avx2-movbe.S @@ -62,9 +62,68 @@ ENTRY (MEMCMP) # endif cmpq $VEC_SIZE, %rdx jb L(less_vec) + + /* From VEC to 2 * VEC. No branch when size == VEC_SIZE. */ + vmovdqu (%rsi), %ymm2 + VPCMPEQ (%rdi), %ymm2, %ymm2 + vpmovmskb %ymm2, %eax + subl $VEC_MASK, %eax + jnz L(first_vec) + cmpq $(VEC_SIZE * 2), %rdx - ja L(more_2x_vec) + jbe L(last_vec) + + VPCMPEQ %ymm0, %ymm0, %ymm0 + /* More than 2 * VEC. */ + cmpq $(VEC_SIZE * 8), %rdx + ja L(more_8x_vec) + cmpq $(VEC_SIZE * 4), %rdx + jb L(last_4x_vec) + + /* From 4 * VEC to 8 * VEC, inclusively. */ + vmovdqu (%rsi), %ymm1 + VPCMPEQ (%rdi), %ymm1, %ymm1 + + vmovdqu VEC_SIZE(%rsi), %ymm2 + VPCMPEQ VEC_SIZE(%rdi), %ymm2, %ymm2 + + vmovdqu (VEC_SIZE * 2)(%rsi), %ymm3 + VPCMPEQ (VEC_SIZE * 2)(%rdi), %ymm3, %ymm3 + + vmovdqu (VEC_SIZE * 3)(%rsi), %ymm4 + VPCMPEQ (VEC_SIZE * 3)(%rdi), %ymm4, %ymm4 + + vpand %ymm1, %ymm2, %ymm5 + vpand %ymm3, %ymm4, %ymm6 + vpand %ymm5, %ymm6, %ymm5 + + vptest %ymm0, %ymm5 + jnc L(4x_vec_end) + + leaq -(4 * VEC_SIZE)(%rdi, %rdx), %rdi + leaq -(4 * VEC_SIZE)(%rsi, %rdx), %rsi + vmovdqu (%rsi), %ymm1 + VPCMPEQ (%rdi), %ymm1, %ymm1 + + vmovdqu VEC_SIZE(%rsi), %ymm2 + VPCMPEQ VEC_SIZE(%rdi), %ymm2, %ymm2 + vpand %ymm2, %ymm1, %ymm5 + + vmovdqu (VEC_SIZE * 2)(%rsi), %ymm3 + VPCMPEQ (VEC_SIZE * 2)(%rdi), %ymm3, %ymm3 + vpand %ymm3, %ymm5, %ymm5 + vmovdqu (VEC_SIZE * 3)(%rsi), %ymm4 + VPCMPEQ (VEC_SIZE * 3)(%rdi), %ymm4, %ymm4 + vpand %ymm4, %ymm5, %ymm5 + + vptest %ymm0, %ymm5 + jnc L(4x_vec_end) + xorl %eax, %eax + VZEROUPPER + ret + + .p2align 4 L(last_2x_vec): /* From VEC to 2 * VEC. No branch when size == VEC_SIZE. */ vmovdqu (%rsi), %ymm2 @@ -219,58 +278,6 @@ L(between_16_31): ret .p2align 4 -L(more_2x_vec): - /* More than 2 * VEC. */ - cmpq $(VEC_SIZE * 8), %rdx - ja L(more_8x_vec) - cmpq $(VEC_SIZE * 4), %rdx - jb L(last_4x_vec) - - /* From 4 * VEC to 8 * VEC, inclusively. */ - vmovdqu (%rsi), %ymm1 - VPCMPEQ (%rdi), %ymm1, %ymm1 - - vmovdqu VEC_SIZE(%rsi), %ymm2 - VPCMPEQ VEC_SIZE(%rdi), %ymm2, %ymm2 - - vmovdqu (VEC_SIZE * 2)(%rsi), %ymm3 - VPCMPEQ (VEC_SIZE * 2)(%rdi), %ymm3, %ymm3 - - vmovdqu (VEC_SIZE * 3)(%rsi), %ymm4 - VPCMPEQ (VEC_SIZE * 3)(%rdi), %ymm4, %ymm4 - - vpand %ymm1, %ymm2, %ymm5 - vpand %ymm3, %ymm4, %ymm6 - vpand %ymm5, %ymm6, %ymm5 - - vpmovmskb %ymm5, %eax - subl $VEC_MASK, %eax - jnz L(4x_vec_end) - - leaq -(4 * VEC_SIZE)(%rdi, %rdx), %rdi - leaq -(4 * VEC_SIZE)(%rsi, %rdx), %rsi - vmovdqu (%rsi), %ymm1 - VPCMPEQ (%rdi), %ymm1, %ymm1 - - vmovdqu VEC_SIZE(%rsi), %ymm2 - VPCMPEQ VEC_SIZE(%rdi), %ymm2, %ymm2 - vpand %ymm2, %ymm1, %ymm5 - - vmovdqu (VEC_SIZE * 2)(%rsi), %ymm3 - VPCMPEQ (VEC_SIZE * 2)(%rdi), %ymm3, %ymm3 - vpand %ymm3, %ymm5, %ymm5 - - vmovdqu (VEC_SIZE * 3)(%rsi), %ymm4 - VPCMPEQ (VEC_SIZE * 3)(%rdi), %ymm4, %ymm4 - vpand %ymm4, %ymm5, %ymm5 - - vpmovmskb %ymm5, %eax - subl $VEC_MASK, %eax - jnz L(4x_vec_end) - VZEROUPPER - ret - - .p2align 4 L(more_8x_vec): /* More than 8 * VEC. Check the first VEC. */ vmovdqu (%rsi), %ymm2 @@ -309,9 +316,8 @@ L(loop_4x_vec): VPCMPEQ (VEC_SIZE * 3)(%rdi), %ymm4, %ymm4 vpand %ymm4, %ymm5, %ymm5 - vpmovmskb %ymm5, %eax - subl $VEC_MASK, %eax - jnz L(4x_vec_end) + vptest %ymm0, %ymm5 + jnc L(4x_vec_end) addq $(VEC_SIZE * 4), %rdi addq $(VEC_SIZE * 4), %rsi |