re PR rtl-optimization/89588 (ICE in unroll_loop_constant_iterations, at loop-unroll.c:498)

	PR rtl-optimization/89588
	* loop-unroll.c (decide_unroll_constant_iterations): Make guard for
	explicit unrolling factor more robust.

From-SVN: r269579

gcc/ChangeLog

+2019-03-11  Eric Botcazou  <ebotcazou@adacore.com>
+
+	PR rtl-optimization/89588
+	* loop-unroll.c (decide_unroll_constant_iterations): Make guard for
+	explicit unrolling factor more robust.
+
 2019-03-11  Richard Biener  <rguenther@suse.de>
 
 	PR tree-optimization/89649

gcc/loop-unroll.c

@@ -400,7 +400,7 @@ decide_unroll_constant_iterations (struct loop *loop, int flags)
     {
       /* However we cannot unroll completely at the RTL level a loop with
 	 constant number of iterations; it should have been peeled instead.  */
-      if ((unsigned) loop->unroll - 1 > desc->niter - 2)
+      if ((unsigned) loop->unroll > desc->niter - 1)
 	{
 	  if (dump_file)
 	    fprintf (dump_file, ";; Loop should have been peeled\n");

gcc/testsuite/ChangeLog

+2019-03-11  Eric Botcazou  <ebotcazou@adacore.com>
+
+	* c-c++-common/unroll-6.c: New test.
+
 2019-03-11  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	PR c++/87571

gcc/testsuite/c-c++-common/unroll-6.c

+/* { dg-do compile } */
+/* { dg-options "-O -fno-tree-loop-optimize" } */
+
+void test (void)
+{
+  #pragma GCC unroll 2
+  for (int nv = 0; nv <= 2; nv += 2)
+    {}
+}