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| author | Noah Goldstein <goldstein.w.n@gmail.com> | 2021-09-30 15:32:50 -0500 |
|---|---|---|
| committer | Noah Goldstein <goldstein.w.n@gmail.com> | 2021-10-27 13:03:46 -0500 |
| commit | fa7f63d8d6a081d59dadcb9986efaafb8093735d (patch) | |
| tree | fbb41b7ab1dc352393da1897036749f81a180543 | |
| parent | cf4fd28ea453d1a9cec93939bc88b58ccef5437a (diff) | |
| download | glibc-fa7f63d8d6a081d59dadcb9986efaafb8093735d.tar glibc-fa7f63d8d6a081d59dadcb9986efaafb8093735d.tar.gz glibc-fa7f63d8d6a081d59dadcb9986efaafb8093735d.tar.bz2 glibc-fa7f63d8d6a081d59dadcb9986efaafb8093735d.zip | |
x86_64: Add sse2 optimized __memcmpeq in memcmp-sse2.S
No bug. This commit does not modify any of the memcmp
implementation. It just adds __memcmpeq ifdefs to skip obvious cases
where computing the proper 1/-1 required by memcmp is not needed.
| -rw-r--r-- | sysdeps/x86_64/memcmp.S | 55 |
1 files changed, 51 insertions, 4 deletions
diff --git a/sysdeps/x86_64/memcmp.S b/sysdeps/x86_64/memcmp.S index b53f2c0866..c245383963 100644 --- a/sysdeps/x86_64/memcmp.S +++ b/sysdeps/x86_64/memcmp.S @@ -49,34 +49,63 @@ L(s2b): movzwl (%rdi), %eax movzwl (%rdi, %rsi), %edx subq $2, %r10 +#ifdef USE_AS_MEMCMPEQ + je L(finz1) +#else je L(fin2_7) +#endif addq $2, %rdi cmpl %edx, %eax +#ifdef USE_AS_MEMCMPEQ + jnz L(neq_early) +#else jnz L(fin2_7) +#endif L(s4b): testq $4, %r10 jz L(s8b) movl (%rdi), %eax movl (%rdi, %rsi), %edx subq $4, %r10 +#ifdef USE_AS_MEMCMPEQ + je L(finz1) +#else je L(fin2_7) +#endif addq $4, %rdi cmpl %edx, %eax +#ifdef USE_AS_MEMCMPEQ + jnz L(neq_early) +#else jnz L(fin2_7) +#endif L(s8b): testq $8, %r10 jz L(s16b) movq (%rdi), %rax movq (%rdi, %rsi), %rdx subq $8, %r10 +#ifdef USE_AS_MEMCMPEQ + je L(sub_return8) +#else je L(fin2_7) +#endif addq $8, %rdi cmpq %rdx, %rax +#ifdef USE_AS_MEMCMPEQ + jnz L(neq_early) +#else jnz L(fin2_7) +#endif L(s16b): movdqu (%rdi), %xmm1 movdqu (%rdi, %rsi), %xmm0 pcmpeqb %xmm0, %xmm1 +#ifdef USE_AS_MEMCMPEQ + pmovmskb %xmm1, %eax + subl $0xffff, %eax + ret +#else pmovmskb %xmm1, %edx xorl %eax, %eax subl $0xffff, %edx @@ -86,7 +115,7 @@ L(s16b): movzbl (%rcx), %eax movzbl (%rsi, %rcx), %edx jmp L(finz1) - +#endif .p2align 4,, 4 L(finr1b): movzbl (%rdi), %eax @@ -95,7 +124,15 @@ L(finz1): subl %edx, %eax L(exit): ret - +#ifdef USE_AS_MEMCMPEQ + .p2align 4,, 4 +L(sub_return8): + subq %rdx, %rax + movl %eax, %edx + shrq $32, %rax + orl %edx, %eax + ret +#else .p2align 4,, 4 L(fin2_7): cmpq %rdx, %rax @@ -111,12 +148,17 @@ L(fin2_7): movzbl %dl, %edx subl %edx, %eax ret - +#endif .p2align 4,, 4 L(finz): xorl %eax, %eax ret - +#ifdef USE_AS_MEMCMPEQ + .p2align 4,, 4 +L(neq_early): + movl $1, %eax + ret +#endif /* For blocks bigger than 32 bytes 1. Advance one of the addr pointer to be 16B aligned. 2. Treat the case of both addr pointers aligned to 16B @@ -246,11 +288,16 @@ L(mt16): .p2align 4,, 4 L(neq): +#ifdef USE_AS_MEMCMPEQ + movl $1, %eax + ret +#else bsfl %edx, %ecx movzbl (%rdi, %rcx), %eax addq %rdi, %rsi movzbl (%rsi,%rcx), %edx jmp L(finz1) +#endif .p2align 4,, 4 L(ATR): |