[PATCH] Fix PR52975

[Richard Guenther]

This fixes the missed cleanup opportunities from the if-conversion mess.
We should try to produce consistent predicates - thus not do overly
optimistic simplifications on them.

Bootstrapped and tested on x86_64-unknown-linux-gnu, applied to trunk.

Richard.

2012-04-16  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/52975
	* tree-if-conv.c (predicate_bbs): Do not simplify inverted
	condition but always mark it with TRUTH_NOT_EXPR.

Index: gcc/tree-if-conv.c
===================================================================
--- gcc/tree-if-conv.c	(revision 186487)
+++ gcc/tree-if-conv.c	(working copy)
@@ -968,7 +968,7 @@ predicate_bbs (loop_p loop)
 
 	    case GIMPLE_COND:
 	      {
-		tree c2, tem;
+		tree c2;
 		edge true_edge, false_edge;
 		location_t loc = gimple_location (stmt);
 		tree c = fold_build2_loc (loc, gimple_cond_code (stmt),
@@ -986,10 +986,8 @@ predicate_bbs (loop_p loop)
 					   unshare_expr (c));
 
 		/* If C is false, then FALSE_EDGE is taken.  */
-		c2 = invert_truthvalue_loc (loc, unshare_expr (c));
-		tem = canonicalize_cond_expr_cond (c2);
-		if (tem)
-		  c2 = tem;
+		c2 = build1_loc (loc, TRUTH_NOT_EXPR,
+				 boolean_type_node, unshare_expr (c));
 		add_to_dst_predicate_list (loop, false_edge,
 					   unshare_expr (cond), c2);