[COMMITTED 2.22] Fix x86_64 fma4 pow inappropriate contraction (bug 19003).

[Aurelien Jarno]

From: Joseph Myers <joseph@codesourcery.com>

The x86_64 fma4 version of pow fails to disable contraction of
operations other than those explicitly intended to use fma
instructions, so resulting in large ulps errors on processors with
fma4 instructions, as in bug 18104 (165ulp for the test added for that
bug; error originally reported by "blaaa" on #glibc).  This patch adds
$(config-cflags-nofma) for e_pow-fma4.c, corresponding to the use for
e_pow.c in sysdeps/ieee754/dbl-64/Makefile.

Tested for x86_64 on a processor with fma4.

	[BZ #19003]
	* sysdeps/x86_64/fpu/multiarch/Makefile (CFLAGS-e_pow-fma4.c): Add
	$(config-cflags-nofma).

(cherry picked from commit 51df2605064a2bfd44fa0655ef9815812347de80)
---
 ChangeLog                             | 6 ++++++
 NEWS                                  | 4 ++--
 sysdeps/x86_64/fpu/multiarch/Makefile | 2 +-
 3 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 602a967..6e42a1e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2015-09-24  Joseph Myers  <joseph@codesourcery.com>
+
+	[BZ #19003]
+	* sysdeps/x86_64/fpu/multiarch/Makefile (CFLAGS-e_pow-fma4.c): Add
+	$(config-cflags-nofma).
+
 2016-03-07  Hongjiu Zhang  <noctuorare@gmail.com>
 
 	* elf/sln.c (makesymlink): Change struct stat to stat64, and lstat
diff --git a/NEWS b/NEWS
index 3d52bec..4679258 100644
--- a/NEWS
+++ b/NEWS
@@ -24,8 +24,8 @@ Version 2.22.1
 * The following bugs are resolved with this release:
 
   17905, 18420, 18421, 18480, 18589, 18743, 18778, 18781, 18787, 18796,
-  18870, 18887, 18921, 18928, 18969, 18985, 19018, 19058, 19174, 19178,
-  19682.
+  18870, 18887, 18921, 18928, 18969, 18985, 19003, 19018, 19058, 19174,
+  19178, 19682.
 
 * The LD_POINTER_GUARD environment variable can no longer be used to
   disable the pointer guard feature.  It is always enabled.
diff --git a/sysdeps/x86_64/fpu/multiarch/Makefile b/sysdeps/x86_64/fpu/multiarch/Makefile
index 86ea473..631534a 100644
--- a/sysdeps/x86_64/fpu/multiarch/Makefile
+++ b/sysdeps/x86_64/fpu/multiarch/Makefile
@@ -16,7 +16,7 @@ CFLAGS-e_asin-fma4.c = -mfma4
 CFLAGS-e_atan2-fma4.c = -mfma4
 CFLAGS-e_exp-fma4.c = -mfma4
 CFLAGS-e_log-fma4.c = -mfma4
-CFLAGS-e_pow-fma4.c = -mfma4
+CFLAGS-e_pow-fma4.c = -mfma4 $(config-cflags-nofma)
 CFLAGS-halfulp-fma4.c = -mfma4
 CFLAGS-mpa-fma4.c = -mfma4
 CFLAGS-mpatan-fma4.c = -mfma4
-- 
2.7.0