From 86e040399dd5ca6b23597be4aff5edb9ac2ab5d7 Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Mon, 25 Jan 2016 12:31:45 -0800
Subject: [PATCH] Don't align DImode to 32 bits if the STV pass is enabled

Since the STV pass uses SSE2 instructions on DImode which needs 64-bit
alignment for DImode, don't align DImode to 32 bits if the STV pass is
enabled.

gcc/

	PR target/69454
	* config/i386/i386.c (convert_scalars_to_vector): Don't change
	stack alignment here.
	(ix86_minimum_alignment): Don't align DImode to 32 bits if the
	STV pass is enabled.

gcc/testsuite/

	PR target/69454
	* gcc.target/i386/pr69454-1.c: New test.
	* gcc.target/i386/pr69454-2.c: Likewise.
---
 gcc/config/i386/i386.c                    | 16 ++++------------
 gcc/testsuite/gcc.target/i386/pr69454-1.c | 11 +++++++++++
 gcc/testsuite/gcc.target/i386/pr69454-2.c | 13 +++++++++++++
 3 files changed, 28 insertions(+), 12 deletions(-)
 create mode 100644 gcc/testsuite/gcc.target/i386/pr69454-1.c
 create mode 100644 gcc/testsuite/gcc.target/i386/pr69454-2.c

diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index cfbdf0f..8babdaf 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -3588,16 +3588,6 @@ convert_scalars_to_vector ()
   bitmap_obstack_release (NULL);
   df_process_deferred_rescans ();
 
-  /* Conversion means we may have 128bit register spills/fills
-     which require aligned stack.  */
-  if (converted_insns)
-    {
-      if (crtl->stack_alignment_needed < 128)
-	crtl->stack_alignment_needed = 128;
-      if (crtl->stack_alignment_estimated < 128)
-	crtl->stack_alignment_estimated = 128;
-    }
-
   return 0;
 }
 
@@ -29299,8 +29289,10 @@ ix86_minimum_alignment (tree exp, machine_mode mode,
     return align;
 
   /* Don't do dynamic stack realignment for long long objects with
-     -mpreferred-stack-boundary=2.  */
-  if ((mode == DImode || (type && TYPE_MODE (type) == DImode))
+     -mpreferred-stack-boundary=2.  The STV pass uses SSE2 instructions
+     on DImode which needs 64-bit alignment for DImode.  */
+  if (!(TARGET_STV && TARGET_SSE2 && optimize > 1)
+      && (mode == DImode || (type && TYPE_MODE (type) == DImode))
       && (!type || !TYPE_USER_ALIGN (type))
       && (!decl || !DECL_USER_ALIGN (decl)))
     return 32;
diff --git a/gcc/testsuite/gcc.target/i386/pr69454-1.c b/gcc/testsuite/gcc.target/i386/pr69454-1.c
new file mode 100644
index 0000000..12ecfd3
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr69454-1.c
@@ -0,0 +1,11 @@
+/* { dg-do compile { target { ia32 } } } */
+/* { dg-options "-O2 -msse2 -mno-accumulate-outgoing-args -mpreferred-stack-boundary=2" } */
+
+typedef struct { long long w64[2]; } V128;
+extern V128* fn2(void);
+long long a;
+V128 b;
+void fn1() {
+  V128 *c = fn2();
+  c->w64[0] = a ^ b.w64[0];
+}
diff --git a/gcc/testsuite/gcc.target/i386/pr69454-2.c b/gcc/testsuite/gcc.target/i386/pr69454-2.c
new file mode 100644
index 0000000..4820b76
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr69454-2.c
@@ -0,0 +1,13 @@
+/* { dg-do compile { target { ia32 } } } */
+/* { dg-options "-O2 -msse2 -mno-accumulate-outgoing-args -mpreferred-stack-boundary=2" } */
+
+extern void fn2 (void);
+long long a, b;
+void
+fn1 (void)
+{
+  long long c = a;
+  a = b ^ a;
+  fn2 ();
+  a = c;
+}
-- 
2.5.0