gimple-fold.c (gimple_fold_stmt_to_constant_1): Canonicalize bool compares on RHS.

2015-08-04  Richard Biener  <rguenther@suse.de>

	* gimple-fold.c (gimple_fold_stmt_to_constant_1): Canonicalize
	bool compares on RHS.
	* match.pd: Add X ==/!= !X is false/true pattern.

	* gcc.dg/tree-ssa/ssa-ccp-38.c: New testcase.

From-SVN: r226576

gcc/ChangeLog

@@ -1,3 +1,9 @@
+2015-08-04  Richard Biener  <rguenther@suse.de>
+
+	* gimple-fold.c (gimple_fold_stmt_to_constant_1): Canonicalize
+	bool compares on RHS.
+	* match.pd: Add X ==/!= !X is false/true pattern.
+
 2015-08-04  Pawel Kupidura  <pawel.kupidura@arm.com>
 
 	* config/aarch64/aarch64.c: Change inner loop statement cost

gcc/gimple-fold.c

@@ -5012,10 +5012,8 @@ gimple_fold_stmt_to_constant_1 (gimple stmt, tree (*valueize) (tree),
 	       further propagation.  */
 	    if (subcode == POINTER_PLUS_EXPR)
 	      {
-		/* Handle binary operators that can appear in GIMPLE form.  */
 		tree op0 = (*valueize) (gimple_assign_rhs1 (stmt));
 		tree op1 = (*valueize) (gimple_assign_rhs2 (stmt));
-
 		if (TREE_CODE (op0) == ADDR_EXPR
 		    && TREE_CODE (op1) == INTEGER_CST)
 		  {
@@ -5027,6 +5025,38 @@ gimple_fold_stmt_to_constant_1 (gimple stmt, tree (*valueize) (tree),
 				      unshare_expr (op0), off));
 		  }
 	      }
+	    /* Canonicalize bool != 0 and bool == 0 appearing after
+	       valueization.  While gimple_simplify handles this
+	       it can get confused by the ~X == 1 -> X == 0 transform
+	       which we cant reduce to a SSA name or a constant
+	       (and we have no way to tell gimple_simplify to not
+	       consider those transforms in the first place).  */
+	    else if (subcode == EQ_EXPR
+		     || subcode == NE_EXPR)
+	      {
+		tree lhs = gimple_assign_lhs (stmt);
+		tree op0 = gimple_assign_rhs1 (stmt);
+		if (useless_type_conversion_p (TREE_TYPE (lhs),
+					       TREE_TYPE (op0)))
+		  {
+		    tree op1 = (*valueize) (gimple_assign_rhs2 (stmt));
+		    op0 = (*valueize) (op0);
+		    if (subcode == NE_EXPR)
+		      {
+			if (integer_zerop (op1))
+			  return op0;
+			else if (integer_zerop (op0))
+			  return op1;
+		      }
+		    else
+		      {
+			if (integer_onep (op1))
+			  return op0;
+			else if (integer_onep (op0))
+			  return op1;
+		      }
+		  }
+	      }
 	    return NULL_TREE;
 
           case GIMPLE_TERNARY_RHS:

gcc/match.pd

@@ -618,6 +618,11 @@ along with GCC; see the file COPYING3.  If not see
  (simplify
   (op:c truth_valued_p@0 (logical_inverted_value @0))
   { constant_boolean_node (true, type); }))
+/* X ==/!= !X is false/true.  */
+(for op (eq ne)
+ (simplify
+  (op:c truth_valued_p@0 (logical_inverted_value @0))
+  { constant_boolean_node (op == NE_EXPR ? true : false, type); }))
 
 /* If arg1 and arg2 are booleans (or any single bit type)
    then try to simplify:

gcc/testsuite/ChangeLog

@@ -1,3 +1,7 @@
+2015-08-04  Richard Biener  <rguenther@suse.de>
+
+	* gcc.dg/tree-ssa/ssa-ccp-38.c: New testcase.
+
 2015-08-04  H.J. Lu  <hongjiu.lu@intel.com>
 
 	PR target/67110

gcc/testsuite/gcc.dg/tree-ssa/ssa-ccp-38.c

@@ -0,0 +1,13 @@
+/* { dg-do compile } */
+/* { dg-options "-O -fdump-tree-ccp1" } */
+
+int foo (_Bool x)
+{
+  _Bool t = 1;
+  _Bool xx = !x;
+  _Bool y = xx == t;
+  _Bool z = y == x;
+  return z ? 1 : 0;
+}
+
+/* { dg-final { scan-tree-dump "return 0;" "ccp1" } } */