From: H.J. Lu <hjl.tools@gmail.com>
Date: Fri, 18 Aug 2017 13:18:55 +0000 (-0700)
Subject: x86-64: Check FMA_Usable in ifunc-mathvec-avx2.h [BZ #21966]
X-Git-Tag: glibc-2.27~1133
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=098b9dd46814f7e624e42a8844c169f3edc67052;p=thirdparty%2Fglibc.git

x86-64: Check FMA_Usable in ifunc-mathvec-avx2.h [BZ #21966]

Since the AVX2 version of mathvec functions uses FMA, it can only be
used when FMA is usable.

	[BZ #21966]
	* sysdeps/x86_64/fpu/multiarch/ifunc-mathvec-avx2.h
	(IFUNC_SELECTOR): Don't use the AVX2 version if FMA isn't
	usable.
---

diff --git a/ChangeLog b/ChangeLog
index 9ffc40cb503..8da8e34fa9f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2017-08-18  H.J. Lu  <hongjiu.lu@intel.com>
+
+	[BZ #21966]
+	* sysdeps/x86_64/fpu/multiarch/ifunc-mathvec-avx2.h
+	(IFUNC_SELECTOR): Don't use the AVX2 version if FMA isn't
+	usable.
+
 2017-08-17  DJ Delorie  <dj@redhat.com>
 
 	* bug17079.c: Update to new test harness.
diff --git a/sysdeps/x86_64/fpu/multiarch/ifunc-mathvec-avx2.h b/sysdeps/x86_64/fpu/multiarch/ifunc-mathvec-avx2.h
index a43d4c54fae..ccda2748c5c 100644
--- a/sysdeps/x86_64/fpu/multiarch/ifunc-mathvec-avx2.h
+++ b/sysdeps/x86_64/fpu/multiarch/ifunc-mathvec-avx2.h
@@ -31,7 +31,8 @@ IFUNC_SELECTOR (void)
 {
   const struct cpu_features* cpu_features = __get_cpu_features ();
 
-  if (CPU_FEATURES_ARCH_P (cpu_features, AVX2_Usable))
+  if (CPU_FEATURES_ARCH_P (cpu_features, FMA_Usable)
+      && CPU_FEATURES_ARCH_P (cpu_features, AVX2_Usable))
     return OPTIMIZE (avx2);
 
   return OPTIMIZE (sse_wrapper);