[PATCH] Fix PR83517

[Richard Biener]

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

Richard.

2018-01-08  Richard Biener  <rguenther@suse.de>

	PR middle-end/83517
	* match.pd ((t * 2) / 2) -> t): Add missing :c.

	* gcc.dg/pr83517.c: New testcase.

Index: gcc/match.pd
===================================================================
--- gcc/match.pd	(revision 256275)
+++ gcc/match.pd	(working copy)
@@ -510,7 +510,7 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
 /* Simplify (t * 2) / 2) -> t.  */
 (for div (trunc_div ceil_div floor_div round_div exact_div)
  (simplify
-  (div (mult @0 @1) @1)
+  (div (mult:c @0 @1) @1)
   (if (ANY_INTEGRAL_TYPE_P (type)
        && TYPE_OVERFLOW_UNDEFINED (type))
    @0)))
Index: gcc/testsuite/gcc.dg/pr83517.c
===================================================================
--- gcc/testsuite/gcc.dg/pr83517.c	(nonexistent)
+++ gcc/testsuite/gcc.dg/pr83517.c	(working copy)
@@ -0,0 +1,9 @@
+/* { dg-do compile } */
+/* { dg-options "-fdump-tree-original" } */
+
+int test(int x)
+{
+  return (x+x)/x;
+}
+
+/* { dg-final { scan-tree-dump "return 2;" "original" } } */