From: Noah Goldstein <goldstein.w.n@gmail.com>
To: libc-alpha@sourceware.org
Subject: [PATCH v1 4/6] x86_64: Add sse2 optimized __memcmpeq in memcmp-sse2.S
Date: Tue, 26 Oct 2021 21:43:21 -0500 [thread overview]
Message-ID: <20211027024323.1199441-4-goldstein.w.n@gmail.com> (raw)
In-Reply-To: <20211027024323.1199441-1-goldstein.w.n@gmail.com>
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.
---
sysdeps/x86_64/memcmp.S | 55 ++++++++++++++++++++++++++++++++++++++---
1 file 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):
--
2.25.1
next prev parent reply other threads:[~2021-10-27 2:43 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-27 2:43 [PATCH v1 1/6] String: Add __memcmpeq as build target Noah Goldstein
2021-10-27 2:43 ` [PATCH v1 2/6] Benchtests: Add benchtests for __memcmpeq Noah Goldstein
2021-10-27 12:45 ` H.J. Lu
2021-10-27 16:08 ` Noah Goldstein
2021-10-27 16:07 ` [PATCH v2 " Noah Goldstein
2021-10-27 17:59 ` H.J. Lu
2021-10-27 2:43 ` [PATCH v1 3/6] x86_64: Add support for __memcmpeq using sse2, avx2, and evex Noah Goldstein
2021-10-27 12:47 ` H.J. Lu
2021-10-27 2:43 ` Noah Goldstein [this message]
2021-10-27 12:48 ` [PATCH v1 4/6] x86_64: Add sse2 optimized __memcmpeq in memcmp-sse2.S H.J. Lu
2021-10-27 2:43 ` [PATCH v1 5/6] x86_64: Add avx2 optimized __memcmpeq in memcmpeq-avx2.S Noah Goldstein
2021-10-27 12:48 ` H.J. Lu
2021-10-27 2:43 ` [PATCH v1 6/6] x86_64: Add evex optimized __memcmpeq in memcmpeq-evex.S Noah Goldstein
2021-10-27 2:44 ` Noah Goldstein
2021-10-27 12:49 ` H.J. Lu
2021-10-27 12:42 ` [PATCH v1 1/6] String: Add __memcmpeq as build target H.J. Lu
2021-10-27 18:46 ` Noah Goldstein
2021-10-28 17:57 ` Joseph Myers
2021-10-28 18:25 ` Noah Goldstein
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