[PATCH] i386: Update the default -mzeroupper setting

["H.J. Lu" <hjl dot tools at gmail dot com>]

-mzeroupper is specified to generate vzeroupper instruction.  If it
isn't used, the default should depend on !TARGET_AVX512ER.  Users can
always use -mzeroupper or -mno-zeroupper to override it.

Sebastian, can you run the full test with it?

OK for trunk if there is no regression?

Thanks.

H.J.
---
gcc/

	PR target/82990
	* config/i386/i386.c (pass_insert_vzeroupper::gate): Remove
	TARGET_AVX512ER check.
	(ix86_option_override_internal): Set MASK_VZEROUPPER if
	neither -mzeroupper nor -mno-zeroupper is used and AVX512ER is
	disabled.

gcc/testsuite/

	PR target/82990
	* gcc.target/i386/pr82990-1.c: New test.
	* gcc.target/i386/pr82990-2.c: Likewise.
	* gcc.target/i386/pr82990-3.c: Likewise.
	* gcc.target/i386/pr82990-4.c: Likewise.
---
 gcc/config/i386/i386.c                    |  5 +++--
 gcc/testsuite/gcc.target/i386/pr82990-1.c | 14 ++++++++++++++
 gcc/testsuite/gcc.target/i386/pr82990-2.c |  6 ++++++
 gcc/testsuite/gcc.target/i386/pr82990-3.c |  6 ++++++
 gcc/testsuite/gcc.target/i386/pr82990-4.c |  6 ++++++
 5 files changed, 35 insertions(+), 2 deletions(-)
 create mode 100644 gcc/testsuite/gcc.target/i386/pr82990-1.c
 create mode 100644 gcc/testsuite/gcc.target/i386/pr82990-2.c
 create mode 100644 gcc/testsuite/gcc.target/i386/pr82990-3.c
 create mode 100644 gcc/testsuite/gcc.target/i386/pr82990-4.c

diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index c5e84a09954..2c729236a29 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -2497,7 +2497,7 @@ public:
   /* opt_pass methods: */
   virtual bool gate (function *)
     {
-      return TARGET_AVX && !TARGET_AVX512ER
+      return TARGET_AVX
 	     && TARGET_VZEROUPPER && flag_expensive_optimizations
 	     && !optimize_size;
     }
@@ -4666,7 +4666,8 @@ ix86_option_override_internal (bool main_args_p,
   if (TARGET_SEH && TARGET_CALL_MS2SYSV_XLOGUES)
     sorry ("-mcall-ms2sysv-xlogues isn%'t currently supported with SEH");
 
-  if (!(opts_set->x_target_flags & MASK_VZEROUPPER))
+  if (!(opts_set->x_target_flags & MASK_VZEROUPPER)
+      && !TARGET_AVX512ER_P (opts->x_ix86_isa_flags))
     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/pr82990-1.c b/gcc/testsuite/gcc.target/i386/pr82990-1.c
new file mode 100644
index 00000000000..ff1d6d40eb2
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr82990-1.c
@@ -0,0 +1,14 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -march=knl -mvzeroupper" } */
+
+#include <immintrin.h>
+
+extern __m512d y, z;
+
+void
+pr82941 ()
+{
+  z = y;
+}
+
+/* { dg-final { scan-assembler-times "vzeroupper" 1 } } */
diff --git a/gcc/testsuite/gcc.target/i386/pr82990-2.c b/gcc/testsuite/gcc.target/i386/pr82990-2.c
new file mode 100644
index 00000000000..0d3cb2333dd
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr82990-2.c
@@ -0,0 +1,6 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -march=skylake-avx512 -mno-vzeroupper" } */
+
+#include "pr82941-1.c"
+
+/* { dg-final { scan-assembler-not "vzeroupper" } } */
diff --git a/gcc/testsuite/gcc.target/i386/pr82990-3.c b/gcc/testsuite/gcc.target/i386/pr82990-3.c
new file mode 100644
index 00000000000..201fa98d8d4
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr82990-3.c
@@ -0,0 +1,6 @@
+/* { dg-do compile } */
+/* { dg-options "-mavx512f -mavx512er -mvzeroupper -O2" } */
+
+#include "pr82941-1.c"
+
+/* { dg-final { scan-assembler-times "vzeroupper" 1 } } */
diff --git a/gcc/testsuite/gcc.target/i386/pr82990-4.c b/gcc/testsuite/gcc.target/i386/pr82990-4.c
new file mode 100644
index 00000000000..09f161c7291
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr82990-4.c
@@ -0,0 +1,6 @@
+/* { dg-do compile } */
+/* { dg-options "-mavx512f -mno-avx512er -mno-vzeroupper -O2" } */
+
+#include "pr82941-1.c"
+
+/* { dg-final { scan-assembler-not "vzeroupper" } } */
-- 
2.13.6