2008-09-08 Richard Guenther <rguenther@suse.de>

	PR tree-optimization/37421
	* tree-ssa-sccvn.c (visit_copy): Make sure to fully
	valueize the RHS.

	* g++.dg/torture/pr37421.C: New testcase.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@140111 138bc75d-0d04-0410-961f-82ee72b054a4

4 files changed, 57 insertions, 3 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 15848c2d0e4..e8d4c0303f8 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2008-09-08  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/37421
+	* tree-ssa-sccvn.c (visit_copy): Make sure to fully
+	valueize the RHS.
+
 2008-09-08  Jakub Jelinek  <jakub@redhat.com>
 
 	PR middle-end/37415
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 219fa164975..e136c69091e 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2008-09-08  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/37421
+	* g++.dg/torture/pr37421.C: New testcase.
+
 2008-09-08  Daniel Kraft  <d@domob.eu>
 
 	PR fortran/36167
diff --git a/gcc/testsuite/g++.dg/torture/pr37421.C b/gcc/testsuite/g++.dg/torture/pr37421.C
new file mode 100644
index 00000000000..4b8447eac49
--- /dev/null
+++ b/gcc/testsuite/g++.dg/torture/pr37421.C
@@ -0,0 +1,39 @@
+/* { dg-do compile } */
+
+#include <stdio.h>
+#include <string.h>
+
+inline int
+bci (const float &source)
+{
+ int dest;
+ memcpy (&dest, &source, sizeof (dest));
+ return dest;
+}
+
+inline float
+bcf (const int &source)
+{
+ float dest;
+ memcpy (&dest, &source, sizeof (dest));
+ return dest;
+}
+
+float
+Foo ()
+{
+ const int foo = bci (0.0f);
+ int bar = foo;
+ const int baz = foo & 1;
+ if (!baz && (foo & 2))
+   bar = 0;
+ return bcf (bar);
+}
+
+int
+main ()
+{
+  printf ("Foo() = %f\n", Foo());
+  return 0;
+}
+
diff --git a/gcc/tree-ssa-sccvn.c b/gcc/tree-ssa-sccvn.c
index 0b995d6837d..09b2ee8fffd 100644
--- a/gcc/tree-ssa-sccvn.c
+++ b/gcc/tree-ssa-sccvn.c
@@ -1607,13 +1607,17 @@ static bool
 visit_copy (tree lhs, tree rhs)
 {
   /* Follow chains of copies to their destination.  */
-  while (SSA_VAL (rhs) != rhs && TREE_CODE (SSA_VAL (rhs)) == SSA_NAME)
+  while (TREE_CODE (rhs) == SSA_NAME
+	 && SSA_VAL (rhs) != rhs)
     rhs = SSA_VAL (rhs);
 
   /* The copy may have a more interesting constant filled expression
      (we don't, since we know our RHS is just an SSA name).  */
-  VN_INFO (lhs)->has_constants = VN_INFO (rhs)->has_constants;
-  VN_INFO (lhs)->expr = VN_INFO (rhs)->expr;
+  if (TREE_CODE (rhs) == SSA_NAME)
+    {
+      VN_INFO (lhs)->has_constants = VN_INFO (rhs)->has_constants;
+      VN_INFO (lhs)->expr = VN_INFO (rhs)->expr;
+    }
 
   return set_ssa_val_to (lhs, rhs);
 }