From: Noah Goldstein <goldstein.w.n@gmail.com>
Date: Mon, 7 Feb 2022 06:32:23 +0000 (-0600)
Subject: x86: Remove SSSE3 instruction for broadcast in memset.S (SSE2 Only)
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f5e0ea6c0dbfd0761a5ce5d6c2226bdd45835c66;p=thirdparty%2Fglibc.git

x86: Remove SSSE3 instruction for broadcast in memset.S (SSE2 Only)

commit b62ace2740a106222e124cc86956448fa07abf4d
Author: Noah Goldstein <goldstein.w.n@gmail.com>
Date:   Sun Feb 6 00:54:18 2022 -0600

    x86: Improve vec generation in memset-vec-unaligned-erms.S

Revert usage of 'pshufb' in broadcast logic as it is an SSSE3
instruction and memset.S is restricted to only SSE2 instructions.

(cherry picked from commit 1b0c60f95bbe2eded80b2bb5be75c0e45b11cde1)
---

diff --git a/sysdeps/x86_64/memset.S b/sysdeps/x86_64/memset.S
index 34ee0bfdcb8..954471e5a5b 100644
--- a/sysdeps/x86_64/memset.S
+++ b/sysdeps/x86_64/memset.S
@@ -30,9 +30,10 @@
 
 # define MEMSET_SET_VEC0_AND_SET_RETURN(d, r) \
   movd d, %xmm0; \
-  pxor %xmm1, %xmm1; \
-  pshufb %xmm1, %xmm0; \
-  movq r, %rax
+  movq r, %rax; \
+  punpcklbw %xmm0, %xmm0; \
+  punpcklwd %xmm0, %xmm0; \
+  pshufd $0, %xmm0, %xmm0
 
 # define WMEMSET_SET_VEC0_AND_SET_RETURN(d, r) \
   movd d, %xmm0; \