re PR tree-optimization/83189 (internal compiler error: in probability_in, at profile-count.h:1050)

	PR middle-end/83189
	* gfortran.fortran-torture/compile/pr83189.f90: New testcase.
	* tree-ssa-loop-manip.c (tree_transform_and_unroll_loop): Handle zero
	profile.

From-SVN: r256480

gcc/ChangeLog

 2018-01-10  Jan Hubicka  <hubicka@ucw.cz>
 
+	PR middle-end/83189
+	* gfortran.fortran-torture/compile/pr83189.f90: New testcase.
+	* tree-ssa-loop-manip.c (tree_transform_and_unroll_loop): Handle zero
+	profile.
+
+2018-01-10  Jan Hubicka  <hubicka@ucw.cz>
+
 	PR middle-end/83575
 	* cfgrtl.c (rtl_verify_edges): Only verify fixability of partition
 	when in layout mode.

gcc/testsuite/ChangeLog

 2018-01-10  Jan Hubicka  <hubicka@ucw.cz>
 
+	PR middle-end/83189
+	* gfortran.fortran-torture/compile/pr83189.f90: New testcase.
+
+2018-01-10  Jan Hubicka  <hubicka@ucw.cz>
+
 	* gcc.c-torture/compile/pr83575.c: New testcase.
 
 2018-01-10  Michael Collison  <michael.collison@arm.com>

gcc/tree-ssa-loop-manip.c

@@ -1378,7 +1378,8 @@ tree_transform_and_unroll_loop (struct loop *loop, unsigned factor,
     {
       /* Avoid dropping loop body profile counter to 0 because of zero count
 	 in loop's preheader.  */
-      freq_e = freq_e.force_nonzero ();
+      if (freq_h.nonzero_p () && !(freq_e == profile_count::zero ()))
+        freq_e = freq_e.force_nonzero ();
       scale_loop_frequencies (loop, freq_e.probability_in (freq_h));
     }