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

2016-10-05  Richard Biener  <rguenther@suse.de>

	PR middle-end/55152
	* match.pd (min(a,-a) -> -abs(a)): New pattern.

	* gcc.dg/pr55152-2.c: New testcase.

From-SVN: r240770

gcc/ChangeLog

+2016-10-05  Richard Biener  <rguenther@suse.de>
+
+	PR middle-end/55152
+	* match.pd (min(a,-a) -> -abs(a)): New pattern.
+
 2016-10-04  Ian Lance Taylor  <iant@golang.org>
 
 	* explow.c (allocate_dynamic_stack_space): Call

gcc/match.pd

@@ -1291,6 +1291,13 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
       && (! ANY_INTEGRAL_TYPE_P (type)
 	  || TYPE_OVERFLOW_UNDEFINED (type)))
   (abs @0)))
+/* min(a,-a) -> -abs(a).  */
+(simplify
+ (min:c @0 (negate @0))
+ (if (TREE_CODE (type) != COMPLEX_TYPE
+      && (! ANY_INTEGRAL_TYPE_P (type)
+	  || TYPE_OVERFLOW_UNDEFINED (type)))
+  (negate (abs @0))))
 (simplify
  (min @0 @1)
  (switch

gcc/testsuite/ChangeLog

+2016-10-05  Richard Biener  <rguenther@suse.de>
+
+	PR middle-end/55152
+	* gcc.dg/pr55152-2.c: New testcase.
+
 2016-10-04  Jerry DeLisle  <jvdelisle@gcc.gnu.org>
 
 	* gfortran.dg/dtio_15.f90: New test.

gcc/testsuite/gcc.dg/pr55152-2.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" } } */