re PR tree-optimization/63798 (FAIL: gcc.target/powerpc/ppc-fmadd-1.c…

re PR tree-optimization/63798 (FAIL: gcc.target/powerpc/ppc-fmadd-1.c scan-assembler-not f(add|sub|mul|neg))

2014-11-10  Richard Biener  <rguenther@suse.de>

	PR middle-end/63798
	* expr.c (expand_expr_real_2): When expanding FMA_EXPRs
	properly treat the embedded multiplication as commutative
	when looking for feeding negates.

From-SVN: r217287

gcc/ChangeLog

+2014-11-10  Richard Biener  <rguenther@suse.de>
+
+	PR middle-end/63798
+	* expr.c (expand_expr_real_2): When expanding FMA_EXPRs
+	properly treat the embedded multiplication as commutative
+	when looking for feeding negates.
+
 2014-11-10  Joern Rennecke  <joern.rennecke@embecosm.com>
 
 	* config/avr/avr.h (CPLUSPLUS_CPP_SPEC): Define.

gcc/expr.c

@@ -8621,6 +8621,19 @@ expand_expr_real_2 (sepops ops, rtx target, machine_mode tmode,
 	  }
 
 	def0 = get_def_for_expr (treeop0, NEGATE_EXPR);
+	/* The multiplication is commutative - look at its 2nd operand
+	   if the first isn't fed by a negate.  */
+	if (!def0)
+	  {
+	    def0 = get_def_for_expr (treeop1, NEGATE_EXPR);
+	    /* Swap operands if the 2nd operand is fed by a negate.  */
+	    if (def0)
+	      {
+		tree tem = treeop0;
+		treeop0 = treeop1;
+		treeop1 = tem;
+	      }
+	  }
 	def2 = get_def_for_expr (treeop2, NEGATE_EXPR);
 
 	op0 = op2 = NULL;