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authorH.J. Lu <hjl.tools@gmail.com>2017-01-30 10:59:15 -0800
committerH.J. Lu <hjl.tools@gmail.com>2017-02-24 09:46:15 -0800
commit4d393a8831fc0ab1b7c29e2d5bafbdbfe2102082 (patch)
tree61dd7efdad17adb9047e1f6eaf6fe646d20b5d16
parentd012ea850680a2a94959f1c5136502a0f712b30a (diff)
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Add VZEROUPPER to memset-vec-unaligned-erms.S [BZ #21081]
Since memset-vec-unaligned-erms.S has VDUP_TO_VEC0_AND_SET_RETURN at
function entry, memset optimized for AVX2 and AVX512 will always use
ymm/zmm register. VZEROUPPER should be placed before ret in

L(stosb):
        movq    %rdx, %rcx
        movzbl  %sil, %eax
        movq    %rdi, %rdx
        rep stosb
        movq    %rdx, %rax
        ret

since it can be reached from

L(stosb_more_2x_vec):
        cmpq    $REP_STOSB_THRESHOLD, %rdx
        ja      L(stosb)

	[BZ #21081]
	* sysdeps/x86_64/multiarch/memset-vec-unaligned-erms.S
	(L(stosb)): Add VZEROUPPER before ret.

(cherry picked from commit 02b78ff749f0c88771713368dbb2a09b1979814f)
-rw-r--r--ChangeLog6
-rw-r--r--sysdeps/x86_64/multiarch/memset-vec-unaligned-erms.S2
2 files changed, 8 insertions, 0 deletions
diff --git a/ChangeLog b/ChangeLog
index a9b7540017..1b7d40adc0 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2017-01-30  H.J. Lu  <hongjiu.lu@intel.com>
+
+	[BZ #21081]
+	* sysdeps/x86_64/multiarch/memset-vec-unaligned-erms.S
+	(L(stosb)): Add VZEROUPPER before ret.
+
 2016-11-28  H.J. Lu  <hongjiu.lu@intel.com>
 
 	[BZ #20750]
diff --git a/sysdeps/x86_64/multiarch/memset-vec-unaligned-erms.S b/sysdeps/x86_64/multiarch/memset-vec-unaligned-erms.S
index 28e71fd576..acf448c9a6 100644
--- a/sysdeps/x86_64/multiarch/memset-vec-unaligned-erms.S
+++ b/sysdeps/x86_64/multiarch/memset-vec-unaligned-erms.S
@@ -110,6 +110,8 @@ ENTRY (__memset_erms)
 ENTRY (MEMSET_SYMBOL (__memset, erms))
 # endif
 L(stosb):
+	/* Issue vzeroupper before rep stosb.  */
+	VZEROUPPER
 	movq	%rdx, %rcx
 	movzbl	%sil, %eax
 	movq	%rdi, %rdx