2011-09-07 Richard Guenther <rguenther@suse.de>

	* tree-ssa-forwprop.c (forward_propagate_into_gimple_cond):
	Canonicalize negated predicates by swapping edges.
	(forward_propagate_into_cond): Likewise.

	* gcc.dg/tree-ssa/forwprop-16.c: New testcase.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@178634 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 39 insertions, 3 deletions

diff --git a/gcc/tree-ssa-forwprop.c b/gcc/tree-ssa-forwprop.c
index ae37095d88e..6333ed6c148 100644
--- a/gcc/tree-ssa-forwprop.c
+++ b/gcc/tree-ssa-forwprop.c
@@ -534,6 +534,23 @@ forward_propagate_into_gimple_cond (gimple stmt)
       return (cfg_changed || is_gimple_min_invariant (tmp)) ? 2 : 1;
     }
 
+  /* Canonicalize _Bool == 0 and _Bool != 1 to _Bool != 0 by swapping edges.  */
+  if ((TREE_CODE (TREE_TYPE (rhs1)) == BOOLEAN_TYPE
+       || (INTEGRAL_TYPE_P (TREE_TYPE (rhs1))
+	   && TYPE_PRECISION (TREE_TYPE (rhs1)) == 1))
+      && ((code == EQ_EXPR
+	   && integer_zerop (rhs2))
+	  || (code == NE_EXPR
+	      && integer_onep (rhs2))))
+    {
+      basic_block bb = gimple_bb (stmt);
+      gimple_cond_set_code (stmt, NE_EXPR);
+      gimple_cond_set_rhs (stmt, build_zero_cst (TREE_TYPE (rhs1)));
+      EDGE_SUCC (bb, 0)->flags ^= (EDGE_TRUE_VALUE|EDGE_FALSE_VALUE);
+      EDGE_SUCC (bb, 1)->flags ^= (EDGE_TRUE_VALUE|EDGE_FALSE_VALUE);
+      return 1;
+    }
+
   return 0;
 }
 
@@ -548,6 +565,7 @@ forward_propagate_into_cond (gimple_stmt_iterator *gsi_p)
   gimple stmt = gsi_stmt (*gsi_p);
   tree tmp = NULL_TREE;
   tree cond = gimple_assign_rhs1 (stmt);
+  bool swap = false;
 
   /* We can do tree combining on SSA_NAME and comparison expressions.  */
   if (COMPARISON_CLASS_P (cond))
@@ -557,17 +575,27 @@ forward_propagate_into_cond (gimple_stmt_iterator *gsi_p)
 					       TREE_OPERAND (cond, 1));
   else if (TREE_CODE (cond) == SSA_NAME)
     {
+      enum tree_code code;
       tree name = cond;
       gimple def_stmt = get_prop_source_stmt (name, true, NULL);
       if (!def_stmt || !can_propagate_from (def_stmt))
 	return 0;
 
-      if (TREE_CODE_CLASS (gimple_assign_rhs_code (def_stmt)) == tcc_comparison)
+      code = gimple_assign_rhs_code (def_stmt);
+      if (TREE_CODE_CLASS (code) == tcc_comparison)
 	tmp = fold_build2_loc (gimple_location (def_stmt),
-			       gimple_assign_rhs_code (def_stmt),
+			       code,
 			       boolean_type_node,
 			       gimple_assign_rhs1 (def_stmt),
 			       gimple_assign_rhs2 (def_stmt));
+      else if ((code == BIT_NOT_EXPR
+		&& TYPE_PRECISION (TREE_TYPE (cond)) == 1)
+	       || (code == BIT_XOR_EXPR
+		   && integer_onep (gimple_assign_rhs2 (def_stmt))))
+	{
+	  tmp = gimple_assign_rhs1 (def_stmt);
+	  swap = true;
+	}
     }
 
   if (tmp)
@@ -586,7 +614,15 @@ forward_propagate_into_cond (gimple_stmt_iterator *gsi_p)
       else if (integer_zerop (tmp))
 	gimple_assign_set_rhs_from_tree (gsi_p, gimple_assign_rhs3 (stmt));
       else
-	gimple_assign_set_rhs1 (stmt, unshare_expr (tmp));
+	{
+	  gimple_assign_set_rhs1 (stmt, unshare_expr (tmp));
+	  if (swap)
+	    {
+	      tree t = gimple_assign_rhs2 (stmt);
+	      gimple_assign_set_rhs2 (stmt, gimple_assign_rhs3 (stmt));
+	      gimple_assign_set_rhs3 (stmt, t);
+	    }
+	}
       stmt = gsi_stmt (*gsi_p);
       update_stmt (stmt);