[glibc] x86: Only align destination to 1x VEC_SIZE in memset 4x loop

[glibc] x86: Only align destination to 1x VEC_SIZE in memset 4x loop

[Noah Goldstein]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=9469261cf1924d350feeec64d2c80cafbbdcdd4d

commit 9469261cf1924d350feeec64d2c80cafbbdcdd4d
Author: Noah Goldstein <goldstein.w.n@gmail.com>
Date:   Wed Nov 1 15:30:26 2023 -0500

    x86: Only align destination to 1x VEC_SIZE in memset 4x loop
    
    Current code aligns to 2x VEC_SIZE. Aligning to 2x has no affect on
    performance other than potentially resulting in an additional
    iteration of the loop.
    1x maintains aligned stores (the only reason to align in this case)
    and doesn't incur any unnecessary loop iterations.
    Reviewed-by: Sunil K Pandey <skpgkp2@gmail.com>

Diff:
---
 sysdeps/x86_64/multiarch/memset-vec-unaligned-erms.S | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sysdeps/x86_64/multiarch/memset-vec-unaligned-erms.S b/sysdeps/x86_64/multiarch/memset-vec-unaligned-erms.S
index 3d9ad49cb9..0f0636b90f 100644
--- a/sysdeps/x86_64/multiarch/memset-vec-unaligned-erms.S
+++ b/sysdeps/x86_64/multiarch/memset-vec-unaligned-erms.S
@@ -293,7 +293,7 @@ L(more_2x_vec):
 	leaq	(VEC_SIZE * 4)(%rax), %LOOP_REG
 #endif
 	/* Align dst for loop.  */
-	andq	$(VEC_SIZE * -2), %LOOP_REG
+	andq	$(VEC_SIZE * -1), %LOOP_REG
 	.p2align 4
 L(loop):
 	VMOVA	%VMM(0), LOOP_4X_OFFSET(%LOOP_REG)