[PATCH 2/2] Make option mvzeroupper independent of optimization level.

[liuhongt <hongtao.liu@intel.com>]

pass_insert_vzeroupper is under condition

TARGET_AVX && TARGET_VZEROUPPER
&& flag_expensive_optimizations && !optimize_size

But the document of mvzeroupper doesn't mention the insertion
required -O2 and above, it may confuse users when they explicitly
use -Os -mvzeroupper.

------------
mvzeroupper
Target Mask(VZEROUPPER) Save
Generate vzeroupper instruction before a transfer of control flow out of
the function.
------------

The patch moves flag_expensive_optimizations && !optimize_size to
ix86_option_override_internal. It makes -mvzeroupper independent of
optimization level, but still keeps the behavior of architecture
tuning(emit_vzeroupper) unchanged.

Bootstrapped and regtested on x86_64-pc-linux-gnu{-m32,}.
Ok for trunk?

gcc/ChangeLog:

	* config/i386/i386-features.cc (pass_insert_vzeroupper:gate):
	Move flag_expensive_optimizations && !optimize_size to ..
	* config/i386/i386-options.cc (ix86_option_override_internal):
	.. this, it makes -mvzeroupper independent of optimization
	level, but still keeps the behavior of architecture
	tuning(emit_vzeroupper) unchanged.

gcc/testsuite/ChangeLog:

	* gcc.target/i386/avx-vzeroupper-29.c: New testcase.
---
 gcc/config/i386/i386-features.cc                  |  3 +--
 gcc/config/i386/i386-options.cc                   |  4 +++-
 gcc/testsuite/gcc.target/i386/avx-vzeroupper-29.c | 14 ++++++++++++++
 3 files changed, 18 insertions(+), 3 deletions(-)
 create mode 100644 gcc/testsuite/gcc.target/i386/avx-vzeroupper-29.c

diff --git a/gcc/config/i386/i386-features.cc b/gcc/config/i386/i386-features.cc
index 4a3b07ae045..92ae08d442e 100644
--- a/gcc/config/i386/i386-features.cc
+++ b/gcc/config/i386/i386-features.cc
@@ -2489,8 +2489,7 @@ public:
   /* opt_pass methods: */
   bool gate (function *) final override
     {
-      return TARGET_AVX && TARGET_VZEROUPPER
-	&& flag_expensive_optimizations && !optimize_size;
+      return TARGET_AVX && TARGET_VZEROUPPER;
     }
 
   unsigned int execute (function *) final override
diff --git a/gcc/config/i386/i386-options.cc b/gcc/config/i386/i386-options.cc
index 2cb0bddcd35..f76e7c5947b 100644
--- a/gcc/config/i386/i386-options.cc
+++ b/gcc/config/i386/i386-options.cc
@@ -2727,7 +2727,9 @@ ix86_option_override_internal (bool main_args_p,
     sorry ("%<-mcall-ms2sysv-xlogues%> isn%'t currently supported with SEH");
 
   if (!(opts_set->x_target_flags & MASK_VZEROUPPER)
-      && TARGET_EMIT_VZEROUPPER)
+      && TARGET_EMIT_VZEROUPPER
+      && flag_expensive_optimizations
+      && !optimize_size)
     opts->x_target_flags |= MASK_VZEROUPPER;
   if (!(opts_set->x_target_flags & MASK_STV))
     opts->x_target_flags |= MASK_STV;
diff --git a/gcc/testsuite/gcc.target/i386/avx-vzeroupper-29.c b/gcc/testsuite/gcc.target/i386/avx-vzeroupper-29.c
new file mode 100644
index 00000000000..4af637757f7
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/avx-vzeroupper-29.c
@@ -0,0 +1,14 @@
+/* { dg-do compile } */
+/* { dg-options "-O0 -mavx -mtune=generic -mvzeroupper -dp" } */
+
+#include <immintrin.h>
+
+extern __m256 x, y;
+
+void
+foo ()
+{
+  x = y;
+}
+
+/* { dg-final { scan-assembler-times "avx_vzeroupper" 1 } } */
-- 
2.39.1.388.g2fc9e9ca3c