File pr34043-1.diff of Package gcc43

2008-02-29  Richard Guenther  <rguenther@suse.de>

	* tree-ssa-pre.c (get_sccvn_value): Create missing VNs via
	vn_lookup_or_add.
	* tree-ssa-sccnv.c (visit_reference_op_store): Use the rhs
	value for comparing for a store match.
	(simplify_unary_expression): Do nothing for SSA_NAMEs.
	(try_to_simplify): Do not do a full-blown reference lookup.

Index: gcc/tree-ssa-sccvn.c
===================================================================
--- gcc/tree-ssa-sccvn.c	(revision 132767)
+++ gcc/tree-ssa-sccvn.c	(revision 132768)
@@ -1231,6 +1231,8 @@ visit_reference_op_store (tree lhs, tree
     {
       if (TREE_CODE (result) == SSA_NAME)
 	result = SSA_VAL (result);
+      if (TREE_CODE (op) == SSA_NAME)
+	op = SSA_VAL (op);
       resultsame = expressions_equal_p (result, op);
     }
 
@@ -1527,13 +1529,10 @@ simplify_unary_expression (tree rhs)
 static tree
 try_to_simplify (tree stmt, tree rhs)
 {
+  /* For stores we can end up simplifying a SSA_NAME rhs.  Just return
+     in this case, there is no point in doing extra work.  */
   if (TREE_CODE (rhs) == SSA_NAME)
-    {
-      if (is_gimple_min_invariant (SSA_VAL (rhs)))
-	return SSA_VAL (rhs);
-      else if (VN_INFO (rhs)->has_constants)
-	return VN_INFO (rhs)->expr;
-    }
+    return rhs;
   else
     {
       switch (TREE_CODE_CLASS (TREE_CODE (rhs)))
@@ -1550,13 +1549,11 @@ try_to_simplify (tree stmt, tree rhs)
 
 	    /* Fallthrough. */
 	case tcc_reference:
-	  {
-	    tree result = vn_reference_lookup (rhs,
-					       shared_vuses_from_stmt (stmt));
-	    if (result)
-	      return result;
-	  }
-	  /* Fallthrough for some codes.  */
+	  /* Do not do full-blown reference lookup here.
+	     ???  But like for tcc_declaration, we should simplify
+		  from constant initializers.  */
+
+	  /* Fallthrough for some codes that can operate on registers.  */
 	  if (!(TREE_CODE (rhs) == REALPART_EXPR
 	        || TREE_CODE (rhs) == IMAGPART_EXPR))
 	    break;
Index: gcc/tree-ssa-pre.c
===================================================================
--- gcc/tree-ssa-pre.c	(revision 132767)
+++ gcc/tree-ssa-pre.c	(revision 132768)
@@ -3256,7 +3256,9 @@ get_sccvn_value (tree name)
 		!ZERO_SSA_OPERANDS (defstmt2, SSA_OP_ALL_VIRTUALS))
 	      gcc_assert (defstmt);
 	  }
-	  valvh = vn_lookup_or_add_with_stmt (val, defstmt);
+	  /* We lookup with the LHS, so do not use vn_lookup_or_add_with_stmt
+	     here, as that will result in useless reference lookups.  */
+	  valvh = vn_lookup_or_add (val);
 	}
 
       if (dump_file && (dump_flags & TDF_DETAILS))