[PATCH v1] x86: Replace sse2 instructions with avx in memcmp-evex-movbe.S

[Noah Goldstein]

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.
---
 sysdeps/x86_64/multiarch/memcmp-evex-movbe.S | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/sysdeps/x86_64/multiarch/memcmp-evex-movbe.S b/sysdeps/x86_64/multiarch/memcmp-evex-movbe.S
index 2761b54f2e..640f6757fa 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
-- 
2.29.2