Fix i386/x86_64 fesetenv SSE exception clearing (bug 19181).

The i386 and x86_64 versions of fesetenv, when called with FE_DFL_ENV
or FE_NOMASK_ENV as argument, do not clear SSE exceptions raised in
MXCSR.  These arguments should, like other fenv_t values, represent
the whole of the floating-point state, so such exceptions should be
cleared; this patch adds the required clearing.  (Discovered while
working on bug 16068.)

Tested for x86_64 and x86.

	[BZ #19181]
	* sysdeps/i386/fpu/fesetenv.c (__fesetenv): Clear already-raised
	SSE exceptions when argument is FE_DFL_ENV or FE_NOMASK_ENV.
	* sysdeps/x86_64/fpu/fesetenv.c (__fesetenv): Likewise.
	* math/test-fenv-clear-main.c: New file.
	* math/test-fenv-clear.c: Likewise.
	* math/Makefile (tests): Add test-fenv-clear.
	* sysdeps/x86/fpu/test-fenv-clear-sse.c: New file.
	* sysdeps/x86/fpu/Makefile [$(subdir) = math] (tests): Add
	test-fenv-clear-sse.
	[$(subdir) = math] (CFLAGS-test-fenv-clear-sse.c): New variable.

4 files changed, 55 insertions, 1 deletions

diff --git a/sysdeps/i386/fpu/fesetenv.c b/sysdeps/i386/fpu/fesetenv.c
index 9566e09..910aa09 100644
--- a/sysdeps/i386/fpu/fesetenv.c
+++ b/sysdeps/i386/fpu/fesetenv.c
@@ -72,6 +72,8 @@ __fesetenv (const fenv_t *envp)
 
       if (envp == FE_DFL_ENV)
 	{
+	  /* Clear SSE exceptions.  */
+	  mxcsr &= ~FE_ALL_EXCEPT;
 	  /* Set mask for SSE MXCSR.  */
 	  mxcsr |= (FE_ALL_EXCEPT << 7);
 	  /* Set rounding to FE_TONEAREST.  */
@@ -80,6 +82,8 @@ __fesetenv (const fenv_t *envp)
 	}
       else if (envp == FE_NOMASK_ENV)
 	{
+	  /* Clear SSE exceptions.  */
+	  mxcsr &= ~FE_ALL_EXCEPT;
 	  /* Do not mask exceptions.  */
 	  mxcsr &= ~(FE_ALL_EXCEPT << 7);
 	  /* Set rounding to FE_TONEAREST.  */
diff --git a/sysdeps/x86/fpu/Makefile b/sysdeps/x86/fpu/Makefile
index 9cb7bb2..d38497c 100644
--- a/sysdeps/x86/fpu/Makefile
+++ b/sysdeps/x86/fpu/Makefile
@@ -1,5 +1,6 @@
 ifeq ($(subdir),math)
 libm-support += powl_helper
-tests += test-fenv-sse
+tests += test-fenv-sse test-fenv-clear-sse
 CFLAGS-test-fenv-sse.c += -msse2 -mfpmath=sse
+CFLAGS-test-fenv-clear-sse.c += -msse2 -mfpmath=sse
 endif
diff --git a/sysdeps/x86/fpu/test-fenv-clear-sse.c b/sysdeps/x86/fpu/test-fenv-clear-sse.c
new file mode 100644
index 0000000..531164c
--- /dev/null
+++ b/sysdeps/x86/fpu/test-fenv-clear-sse.c
@@ -0,0 +1,45 @@
+/* Test fesetenv (FE_DFL_ENV) and fesetenv (FE_NOMASK_ENV) clear
+   exceptions (bug 19181).  SSE version.
+   Copyright (C) 2015 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <cpuid.h>
+#include <stdbool.h>
+
+static bool
+have_sse2 (void)
+{
+  unsigned int eax, ebx, ecx, edx;
+
+  if (!__get_cpuid (1, &eax, &ebx, &ecx, &edx))
+    return false;
+
+  return (edx & bit_SSE2) != 0;
+}
+
+#define CHECK_CAN_TEST						\
+  do								\
+    {								\
+      if (!have_sse2 ())					\
+	{							\
+	  puts ("CPU does not support SSE2, cannot test");	\
+	  return 0;						\
+	}							\
+    }								\
+  while (0)
+
+#include <test-fenv-clear-main.c>
diff --git a/sysdeps/x86_64/fpu/fesetenv.c b/sysdeps/x86_64/fpu/fesetenv.c
index 3e3fd84..9950aa7 100644
--- a/sysdeps/x86_64/fpu/fesetenv.c
+++ b/sysdeps/x86_64/fpu/fesetenv.c
@@ -42,6 +42,8 @@ __fesetenv (const fenv_t *envp)
       temp.__opcode = 0;
       temp.__data_offset = 0;
       temp.__data_selector = 0;
+      /* Clear SSE exceptions.  */
+      temp.__mxcsr &= ~FE_ALL_EXCEPT;
       /* Set mask for SSE MXCSR.  */
       temp.__mxcsr |= (FE_ALL_EXCEPT << 7);
       /* Set rounding to FE_TONEAREST.  */
@@ -57,6 +59,8 @@ __fesetenv (const fenv_t *envp)
       temp.__opcode = 0;
       temp.__data_offset = 0;
       temp.__data_selector = 0;
+      /* Clear SSE exceptions.  */
+      temp.__mxcsr &= ~FE_ALL_EXCEPT;
       /* Set mask for SSE MXCSR.  */
       /* Set rounding to FE_TONEAREST.  */
       temp.__mxcsr &= ~ 0x6000;