re PR middle-end/55152 (MAX_EXPR(a,-a) is really ABS_EXPR(a))

2016-09-29  Richard Biener  <rguenther@suse.de>

	PR middle-end/55152
	* match.pd: Add max(a,-a) -> abs(a) pattern.
	* tree-ssa-phiopt.c (minmax_replacement): Disable for
	HONOR_SIGNED_ZEROS types.

	* gcc.dg/pr55152.c: New testcase.
	* gcc.dg/tree-ssa/phi-opt-5.c: Adjust.

From-SVN: r240615

gcc/ChangeLog

+2016-09-29  Richard Biener  <rguenther@suse.de>
+
+	PR middle-end/55152
+	* match.pd: Add max(a,-a) -> abs(a) pattern.
+	* tree-ssa-phiopt.c (minmax_replacement): Disable for
+	HONOR_SIGNED_ZEROS types.
+
 2016-09-29  James Greenhalgh  <james.greenhalgh@arm.com>
 
 	* defaults.h (TARGET_FLT_EVAL_METHOD_NON_DEFAULT): Remove.

gcc/match.pd

@@ -1271,6 +1271,13 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
 (simplify
  (max:c (min:c @0 @1) @1)
  @1)
+/* max(a,-a) -> abs(a).  */
+(simplify
+ (max:c @0 (negate @0))
+ (if (TREE_CODE (type) != COMPLEX_TYPE
+      && (! ANY_INTEGRAL_TYPE_P (type)
+	  || TYPE_OVERFLOW_UNDEFINED (type)))
+  (abs @0)))
 (simplify
  (min @0 @1)
  (switch

gcc/testsuite/ChangeLog

+2016-09-29  Richard Biener  <rguenther@suse.de>
+
+	PR middle-end/55152
+	* gcc.dg/pr55152.c: New testcase.
+	* gcc.dg/tree-ssa/phi-opt-5.c: Adjust.
+
 2016-09-29  Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>
 
 	* gcc.dg/profile-update-warning.c: Restrict to ia32.

gcc/testsuite/gcc.dg/pr55152.c

+/* { dg-do compile } */
+/* { dg-options "-O -ffinite-math-only -fno-signed-zeros -fstrict-overflow -fdump-tree-optimized" } */
+
+double g (double a)
+{
+  return (a>=-a)?a:-a;
+}
+int f(int a)
+{
+  return (a>=-a)?a:-a;
+}
+
+/* { dg-final { scan-tree-dump-times "ABS_EXPR" 2 "optimized" } } */

gcc/testsuite/gcc.dg/tree-ssa/phi-opt-5.c

 /* { dg-do compile } */
-/* { dg-options "-O1 -ffinite-math-only -fdump-tree-phiopt1" } */
+/* { dg-options "-O1 -ffinite-math-only -fno-signed-zeros -fdump-tree-phiopt1" } */
 
 float repl1 (float varx)
 {

gcc/tree-ssa-phiopt.c

@@ -1075,7 +1075,7 @@ minmax_replacement (basic_block cond_bb, basic_block middle_bb,
   type = TREE_TYPE (PHI_RESULT (phi));
 
   /* The optimization may be unsafe due to NaNs.  */
-  if (HONOR_NANS (type))
+  if (HONOR_NANS (type) || HONOR_SIGNED_ZEROS (type))
     return false;
 
   cond = as_a <gcond *> (last_stmt (cond_bb));