diff options
| author | Noah Goldstein <goldstein.w.n@gmail.com> | 2022-03-25 17:13:33 -0500 |
|---|---|---|
| committer | Noah Goldstein <goldstein.w.n@gmail.com> | 2022-03-28 15:00:03 -0500 |
| commit | 244b415d386487521882debb845a040a4758cb18 (patch) | |
| tree | 25037631403bb43edecf213273f0a8cf28ec9b15 | |
| parent | f5bff979d02cf115be94c0c0c6f1a1a505964772 (diff) | |
| download | glibc-244b415d386487521882debb845a040a4758cb18.zip glibc-244b415d386487521882debb845a040a4758cb18.tar.gz glibc-244b415d386487521882debb845a040a4758cb18.tar.bz2 | |
x86: Small improvements for wcslen
Just a few QOL changes.
1. Prefer `add` > `lea` as it has high execution units it can run
on.
2. Don't break macro-fusion between `test` and `jcc`
3. Reduce code size by removing gratuitous padding bytes (-90
bytes).
geometric_mean(N=20) of all benchmarks New / Original: 0.959
All string/memory tests pass.
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
| -rw-r--r-- | sysdeps/x86_64/wcslen.S | 86 |
1 files changed, 41 insertions, 45 deletions
diff --git a/sysdeps/x86_64/wcslen.S b/sysdeps/x86_64/wcslen.S index c9165db..d641141 100644 --- a/sysdeps/x86_64/wcslen.S +++ b/sysdeps/x86_64/wcslen.S @@ -40,82 +40,82 @@ ENTRY (__wcslen) pxor %xmm0, %xmm0 lea 32(%rdi), %rax - lea 16(%rdi), %rcx + addq $16, %rdi and $-16, %rax pcmpeqd (%rax), %xmm0 pmovmskb %xmm0, %edx pxor %xmm1, %xmm1 + addq $16, %rax test %edx, %edx - lea 16(%rax), %rax jnz L(exit) pcmpeqd (%rax), %xmm1 pmovmskb %xmm1, %edx pxor %xmm2, %xmm2 + addq $16, %rax test %edx, %edx - lea 16(%rax), %rax jnz L(exit) pcmpeqd (%rax), %xmm2 pmovmskb %xmm2, %edx pxor %xmm3, %xmm3 + addq $16, %rax test %edx, %edx - lea 16(%rax), %rax jnz L(exit) pcmpeqd (%rax), %xmm3 pmovmskb %xmm3, %edx + addq $16, %rax test %edx, %edx - lea 16(%rax), %rax jnz L(exit) pcmpeqd (%rax), %xmm0 pmovmskb %xmm0, %edx + addq $16, %rax test %edx, %edx - lea 16(%rax), %rax jnz L(exit) pcmpeqd (%rax), %xmm1 pmovmskb %xmm1, %edx + addq $16, %rax test %edx, %edx - lea 16(%rax), %rax jnz L(exit) pcmpeqd (%rax), %xmm2 pmovmskb %xmm2, %edx + addq $16, %rax test %edx, %edx - lea 16(%rax), %rax jnz L(exit) pcmpeqd (%rax), %xmm3 pmovmskb %xmm3, %edx + addq $16, %rax test %edx, %edx - lea 16(%rax), %rax jnz L(exit) pcmpeqd (%rax), %xmm0 pmovmskb %xmm0, %edx + addq $16, %rax test %edx, %edx - lea 16(%rax), %rax jnz L(exit) pcmpeqd (%rax), %xmm1 pmovmskb %xmm1, %edx + addq $16, %rax test %edx, %edx - lea 16(%rax), %rax jnz L(exit) pcmpeqd (%rax), %xmm2 pmovmskb %xmm2, %edx + addq $16, %rax test %edx, %edx - lea 16(%rax), %rax jnz L(exit) pcmpeqd (%rax), %xmm3 pmovmskb %xmm3, %edx + addq $16, %rax test %edx, %edx - lea 16(%rax), %rax jnz L(exit) and $-0x40, %rax @@ -132,104 +132,100 @@ L(aligned_64_loop): pminub %xmm0, %xmm2 pcmpeqd %xmm3, %xmm2 pmovmskb %xmm2, %edx + addq $64, %rax test %edx, %edx - lea 64(%rax), %rax jz L(aligned_64_loop) pcmpeqd -64(%rax), %xmm3 pmovmskb %xmm3, %edx + addq $48, %rdi test %edx, %edx - lea 48(%rcx), %rcx jnz L(exit) pcmpeqd %xmm1, %xmm3 pmovmskb %xmm3, %edx + addq $-16, %rdi test %edx, %edx - lea -16(%rcx), %rcx jnz L(exit) pcmpeqd -32(%rax), %xmm3 pmovmskb %xmm3, %edx + addq $-16, %rdi test %edx, %edx - lea -16(%rcx), %rcx jnz L(exit) pcmpeqd %xmm6, %xmm3 pmovmskb %xmm3, %edx + addq $-16, %rdi test %edx, %edx - lea -16(%rcx), %rcx - jnz L(exit) - - jmp L(aligned_64_loop) + jz L(aligned_64_loop) .p2align 4 L(exit): - sub %rcx, %rax + sub %rdi, %rax shr $2, %rax test %dl, %dl jz L(exit_high) - mov %dl, %cl - and $15, %cl + andl $15, %edx jz L(exit_1) ret - .p2align 4 + /* No align here. Naturally aligned % 16 == 1. */ L(exit_high): - mov %dh, %ch - and $15, %ch + andl $(15 << 8), %edx jz L(exit_3) add $2, %rax ret - .p2align 4 + .p2align 3 L(exit_1): add $1, %rax ret - .p2align 4 + .p2align 3 L(exit_3): add $3, %rax ret - .p2align 4 + .p2align 3 L(exit_tail0): - xor %rax, %rax + xorl %eax, %eax ret - .p2align 4 + .p2align 3 L(exit_tail1): - mov $1, %rax + movl $1, %eax ret - .p2align 4 + .p2align 3 L(exit_tail2): - mov $2, %rax + movl $2, %eax ret - .p2align 4 + .p2align 3 L(exit_tail3): - mov $3, %rax + movl $3, %eax ret - .p2align 4 + .p2align 3 L(exit_tail4): - mov $4, %rax + movl $4, %eax ret - .p2align 4 + .p2align 3 L(exit_tail5): - mov $5, %rax + movl $5, %eax ret - .p2align 4 + .p2align 3 L(exit_tail6): - mov $6, %rax + movl $6, %eax ret - .p2align 4 + .p2align 3 L(exit_tail7): - mov $7, %rax + movl $7, %eax ret END (__wcslen) |