41 lines
1.6 KiB
Diff
41 lines
1.6 KiB
Diff
|
commit baf3ece63453adac59c5688930324a78ced5b2e4
|
||
|
|
Author: Noah Goldstein <goldstein.w.n@gmail.com>
|
||
|
|
Date: Sat Oct 23 01:26:47 2021 -0400
|
||
|
|
|
||
|
|
x86: Replace sse2 instructions with avx in memcmp-evex-movbe.S
|
||
|
|
|
||
|
|
This commit replaces two usages of SSE2 'movups' with AVX 'vmovdqu'.
|
||
|
|
|
||
|
|
it could potentially be dangerous to use SSE2 if this function is ever
|
||
|
|
called without using 'vzeroupper' beforehand. While compilers appear
|
||
|
|
to use 'vzeroupper' before function calls if AVX2 has been used, using
|
||
|
|
SSE2 here is more brittle. Since it is not absolutely necessary it
|
||
|
|
should be avoided.
|
||
|
|
|
||
|
|
It costs 2-extra bytes but the extra bytes should only eat into
|
||
|
|
alignment padding.
|
||
|
|
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
|
||
|
|
|
||
|
|
(cherry picked from commit bad852b61b79503fcb3c5fc379c70f768df3e1fb)
|
||
|
|
|
||
|
|
diff --git a/sysdeps/x86_64/multiarch/memcmp-evex-movbe.S b/sysdeps/x86_64/multiarch/memcmp-evex-movbe.S
|
||
|
|
index 2761b54f2e7dea9f..640f6757fac8a356 100644
|
||
|
|
--- a/sysdeps/x86_64/multiarch/memcmp-evex-movbe.S
|
||
|
|
+++ b/sysdeps/x86_64/multiarch/memcmp-evex-movbe.S
|
||
|
|
@@ -561,13 +561,13 @@ L(between_16_31):
|
||
|
|
/* From 16 to 31 bytes. No branch when size == 16. */
|
||
|
|
|
||
|
|
/* Use movups to save code size. */
|
||
|
|
- movups (%rsi), %xmm2
|
||
|
|
+ vmovdqu (%rsi), %xmm2
|
||
|
|
VPCMP $4, (%rdi), %xmm2, %k1
|
||
|
|
kmovd %k1, %eax
|
||
|
|
testl %eax, %eax
|
||
|
|
jnz L(return_vec_0_lv)
|
||
|
|
/* Use overlapping loads to avoid branches. */
|
||
|
|
- movups -16(%rsi, %rdx, CHAR_SIZE), %xmm2
|
||
|
|
+ vmovdqu -16(%rsi, %rdx, CHAR_SIZE), %xmm2
|
||
|
|
VPCMP $4, -16(%rdi, %rdx, CHAR_SIZE), %xmm2, %k1
|
||
|
|
addl $(CHAR_PER_VEC - (16 / CHAR_SIZE)), %edx
|
||
|
|
kmovd %k1, %eax
|