re PR tree-optimization/81428 (ICE: in build_one_cst, at tree.c:2079 with -O2. Fixed point division.)

PR tree-optimization/81428
	* match.pd (X / X -> one): Don't optimize _Fract divisions, as 1
	can't be built for those types.

	* gcc.dg/fixed-point/pr81428.c: New test.

From-SVN: r250265

gcc/ChangeLog

@@ -1,3 +1,9 @@
+2017-07-17  Jakub Jelinek  <jakub@redhat.com>
+
+	PR tree-optimization/81428
+	* match.pd (X / X -> one): Don't optimize _Fract divisions, as 1
+	can't be built for those types.
+
 2017-07-17  Georg-Johann Lay  <avr@gjlay.de>
 
 	Remove stuff dead since r239246.

gcc/match.pd

@@ -243,8 +243,9 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
  /* X / X is one.  */
  (simplify
   (div @0 @0)
-  /* But not for 0 / 0 so that we can get the proper warnings and errors.  */
+  /* But not for 0 / 0 so that we can get the proper warnings and errors.
-  (if (!integer_zerop (@0))
+     And not for _Fract types where we can't build 1.  */
+  (if (!integer_zerop (@0) && !ALL_FRACT_MODE_P (TYPE_MODE (type)))
    { build_one_cst (type); }))
  /* X / abs (X) is X < 0 ? -1 : 1.  */ 
  (simplify

gcc/testsuite/ChangeLog

@@ -1,5 +1,8 @@
 2017-07-17  Jakub Jelinek  <jakub@redhat.com>
 
+	PR tree-optimization/81428
+	* gcc.dg/fixed-point/pr81428.c: New test.
+
 	PR tree-optimization/81365
 	* g++.dg/torture/pr81365.C: New test.
 

gcc/testsuite/gcc.dg/fixed-point/pr81428.c

@@ -0,0 +1,9 @@
+/* PR tree-optimization/81428 */
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+void
+foo (long _Fract *a, long _Fract *b)
+{
+  *b = *a / *a;
+}