Don't generate COND_EXPRs for degenerate_phi_result.

2010-05-28  Sebastian Pop  <sebastian.pop@amd.com>

	* tree-if-conv.c (replace_phi_with_cond_gimple_assign_stmt): Don't
	generate COND_EXPRs for degenerate_phi_result.

From-SVN: r159991

gcc/ChangeLog

 2010-05-28  Sebastian Pop  <sebastian.pop@amd.com>
 
+	* tree-if-conv.c (replace_phi_with_cond_gimple_assign_stmt): Don't
+	generate COND_EXPRs for degenerate_phi_result.
+
+2010-05-28  Sebastian Pop  <sebastian.pop@amd.com>
+
 	PR middle-end/44293
 	* tree-if-conv.c (if_convertible_loop_p): Check the
 	if-convertibility of phi nodes in non predicated BBs.

gcc/tree-if-conv.c

@@ -864,13 +864,19 @@ replace_phi_with_cond_gimple_assign_stmt (gimple phi, tree cond,
   gimple new_stmt;
   basic_block bb;
   tree rhs;
-  tree arg_0, arg_1;
+  tree arg;
 
   gcc_assert (gimple_code (phi) == GIMPLE_PHI
 	      && gimple_phi_num_args (phi) == 2);
 
   bb = gimple_bb (phi);
 
+  arg = degenerate_phi_result (phi);
+  if (arg)
+    rhs = arg;
+  else
+    {
+      tree arg_0, arg_1;
       /* Use condition that is not TRUTH_NOT_EXPR in conditional modify expr.  */
       if (EDGE_PRED (bb, 1)->src == true_bb)
 	{
@@ -885,10 +891,10 @@ replace_phi_with_cond_gimple_assign_stmt (gimple phi, tree cond,
 
       /* Build new RHS using selected condition and arguments.  */
       rhs = build3 (COND_EXPR, TREE_TYPE (PHI_RESULT (phi)),
-	        unshare_expr (cond), unshare_expr (arg_0),
-	        unshare_expr (arg_1));
+		    unshare_expr (cond), arg_0, arg_1);
+    }
 
-  new_stmt = gimple_build_assign (unshare_expr (PHI_RESULT (phi)), rhs);
+  new_stmt = gimple_build_assign (PHI_RESULT (phi), rhs);
   SSA_NAME_DEF_STMT (gimple_phi_result (phi)) = new_stmt;
   gsi_insert_before (gsi, new_stmt, GSI_SAME_STMT);
   update_stmt (new_stmt);