PATCH: PR libc/12460: AVX audit test failures with gcc 4.6

[H.J. Lu]

The vzeroupper optimization in gcc 4.6 will add vzeroupper before function
return even if AVX isn't supported. Due to nature of special codes in AVX
audit tests, we can't use __builtin_ia32_vzeroupper in AVX audit tests.
This patch adds -mno-vzeroupper for those tests if needed.


H.J.
---
2011-02-02  H.J. Lu  <hongjiu.lu@intel.com>

	PR libc/12460
	* config.make.in (config-cflags-novzeroupper): New.

	* configure.in: Substitute libc_cv_cc_novzeroupper.
	* configure: Regenerated.

	* elf/Makefile (AVX-CFLAGS): New.
	(CFLAGS-tst-audit4.c): Replace -mavx with $(AVX-CFLAGS).
	(CFLAGS-tst-auditmod4a.c): Likewise.
	(CFLAGS-tst-auditmod4b.c): Likewise.
	(CFLAGS-tst-auditmod6b.c): Likewise.
	(CFLAGS-tst-auditmod6c.c): Likewise.
	(CFLAGS-tst-auditmod7b.c): Likewise.

	* sysdeps/i386/configure.in: Check -mno-vzeroupper.
	* sysdeps/i386/configure: Regenerated.

diff --git a/config.make.in b/config.make.in
index efffee4..3f6a698 100644
--- a/config.make.in
+++ b/config.make.in
@@ -36,6 +36,7 @@ asflags-cpu = @libc_cv_cc_submachine@
 
 config-cflags-sse4 = @libc_cv_cc_sse4@
 config-cflags-avx = @libc_cv_cc_avx@
+config-cflags-novzeroupper = @libc_cv_cc_novzeroupper@
 config-asflags-i686 = @libc_cv_as_i686@
 
 defines = @DEFINES@
diff --git a/elf/Makefile b/elf/Makefile
index 0f37804..36ea9b8 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -1181,10 +1181,14 @@ $(objpfx)tst-initorder.out: $(objpfx)tst-initorder
 	cmp $@ tst-initorder.exp > /dev/null
 
 ifeq (yes,$(config-cflags-avx))
-CFLAGS-tst-audit4.c += -mavx
-CFLAGS-tst-auditmod4a.c += -mavx
-CFLAGS-tst-auditmod4b.c += -mavx
-CFLAGS-tst-auditmod6b.c += -mavx
-CFLAGS-tst-auditmod6c.c += -mavx
-CFLAGS-tst-auditmod7b.c += -mavx
+AVX-CFLAGS=-mavx
+ifeq (yes,$(config-cflags-novzeroupper))
+AVX-CFLAGS+=-mno-vzeroupper
+endif
+CFLAGS-tst-audit4.c += $(AVX-CFLAGS)
+CFLAGS-tst-auditmod4a.c += $(AVX-CFLAGS)
+CFLAGS-tst-auditmod4b.c += $(AVX-CFLAGS)
+CFLAGS-tst-auditmod6b.c += $(AVX-CFLAGS)
+CFLAGS-tst-auditmod6c.c += $(AVX-CFLAGS)
+CFLAGS-tst-auditmod7b.c += $(AVX-CFLAGS)
 endif
diff --git a/sysdeps/i386/configure.in b/sysdeps/i386/configure.in
index d8dd648..67fd1d7 100644
--- a/sysdeps/i386/configure.in
+++ b/sysdeps/i386/configure.in
@@ -66,3 +66,11 @@ fi])
 if test $libc_cv_cc_avx = yes; then
   AC_DEFINE(HAVE_AVX_SUPPORT)
 fi
+
+dnl Check if -mno-vzeroupper works.
+AC_CACHE_CHECK(for -mno-vzeroupper support, libc_cv_cc_novzeroupper, [dnl
+if AC_TRY_COMMAND([${CC-cc} -mno-vzeroupper -xc /dev/null -S -o /dev/null]); then
+  libc_cv_cc_novzeroupper=yes
+else
+  libc_cv_cc_novzeroupper=no
+fi])