2013-03-18 Richard Biener <rguenther@suse.de>

	PR tree-optimization/3713
	* tree-ssa-sccvn.c (visit_copy): Simplify.  Always propagate
	has_constants and expr.
	(stmt_has_constants): Properly valueize SSA names when deciding
	whether the stmt has constants.

	* g++.dg/ipa/devirt-12.C: New testcase.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@196771 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 27 insertions, 19 deletions

diff --git a/gcc/tree-ssa-sccvn.c b/gcc/tree-ssa-sccvn.c
index c63aa2d0eca..8360cc73000 100644
--- a/gcc/tree-ssa-sccvn.c
+++ b/gcc/tree-ssa-sccvn.c
@@ -2652,18 +2652,13 @@ static tree valueize_expr (tree expr);
 static bool
 visit_copy (tree lhs, tree rhs)
 {
-  /* Follow chains of copies to their destination.  */
-  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).  */
-  if (TREE_CODE (rhs) == SSA_NAME)
-    {
-      VN_INFO (lhs)->has_constants = VN_INFO (rhs)->has_constants;
-      VN_INFO (lhs)->expr = VN_INFO (rhs)->expr;
-    }
+  VN_INFO (lhs)->has_constants = VN_INFO (rhs)->has_constants;
+  VN_INFO (lhs)->expr = VN_INFO (rhs)->expr;
+
+  /* And finally valueize.  */
+  rhs = SSA_VAL (rhs);
 
   return set_ssa_val_to (lhs, rhs);
 }
@@ -3062,25 +3057,38 @@ expr_has_constants (tree expr)
 static bool
 stmt_has_constants (gimple stmt)
 {
+  tree tem;
+
   if (gimple_code (stmt) != GIMPLE_ASSIGN)
     return false;
 
   switch (get_gimple_rhs_class (gimple_assign_rhs_code (stmt)))
     {
-    case GIMPLE_UNARY_RHS:
-      return is_gimple_min_invariant (gimple_assign_rhs1 (stmt));
+    case GIMPLE_TERNARY_RHS:
+      tem = gimple_assign_rhs3 (stmt);
+      if (TREE_CODE (tem) == SSA_NAME)
+	tem = SSA_VAL (tem);
+      if (is_gimple_min_invariant (tem))
+	return true;
+      /* Fallthru.  */
 
     case GIMPLE_BINARY_RHS:
-      return (is_gimple_min_invariant (gimple_assign_rhs1 (stmt))
-	      || is_gimple_min_invariant (gimple_assign_rhs2 (stmt)));
-    case GIMPLE_TERNARY_RHS:
-      return (is_gimple_min_invariant (gimple_assign_rhs1 (stmt))
-	      || is_gimple_min_invariant (gimple_assign_rhs2 (stmt))
-	      || is_gimple_min_invariant (gimple_assign_rhs3 (stmt)));
+      tem = gimple_assign_rhs2 (stmt);
+      if (TREE_CODE (tem) == SSA_NAME)
+	tem = SSA_VAL (tem);
+      if (is_gimple_min_invariant (tem))
+	return true;
+      /* Fallthru.  */
+
     case GIMPLE_SINGLE_RHS:
       /* Constants inside reference ops are rarely interesting, but
 	 it can take a lot of looking to find them.  */
-      return is_gimple_min_invariant (gimple_assign_rhs1 (stmt));
+    case GIMPLE_UNARY_RHS:
+      tem = gimple_assign_rhs1 (stmt);
+      if (TREE_CODE (tem) == SSA_NAME)
+	tem = SSA_VAL (tem);
+      return is_gimple_min_invariant (tem);
+
     default:
       gcc_unreachable ();
     }