loop-unswitch.c (unswitch_single_loop): Use estimated_loop_iterations_int to prevent unswitching when...

	* loop-unswitch.c (unswitch_single_loop): Use
	estimated_loop_iterations_int to prevent unswitching when loop
	is known to not roll.
	* tree-ssa-loop-niter.c (estimated_loop_iterations): Do not segfault
	when SCEV is not initialized.
	(max_loop_iterations): Likewise.
	* tree-ssa-loop-unswitch.c (tree_ssa_unswitch_loops): Use
	estimated_loop_iterations_int to prevent unswithcing when
	loop is known to not roll.
	* tree-scalar-evolution.c (scev_initialized_p): New function.
	* tree-scalar-evolution.h (scev_initialized_p): Likewise.
	* loop-unroll.c (decide_peel_once_rolling): Use
	max_loop_iterations_int.
	(unroll_loop_constant_iterations): Update
	nb_iterations_upper_bound and nb_iterations_estimate.
	(decide_unroll_runtime_iterations): Use
	estimated_loop_iterations or max_loop_iterations;
	(unroll_loop_runtime_iterations): fix profile updating.
	(decide_peel_simple): Use estimated_loop_iterations
	and max_loop_iterations.
	(decide_unroll_stupid): Use estimated_loop_iterations
	ad max_loop_iterations.
	* loop-doloop.c (doloop_modify): Use max_loop_iterations_int.
	(doloop_optimize): Likewise.
	* loop-iv.c (iv_number_of_iterations): Use record_niter_bound.
	(find_simple_exit): Likewise.
	* cfgloop.h (struct niter_desc): Remove niter_max.

From-SVN: r192219

1 files changed, 11 insertions, 0 deletions

diff --git a/gcc/tree-ssa-loop-unswitch.c b/gcc/tree-ssa-loop-unswitch.c
index eaf41e7..b24f3d7 100644
--- a/gcc/tree-ssa-loop-unswitch.c
+++ b/gcc/tree-ssa-loop-unswitch.c
@@ -78,6 +78,7 @@ tree_ssa_unswitch_loops (void)
   loop_iterator li;
   struct loop *loop;
   bool changed = false;
+  HOST_WIDE_INT iterations;
 
   /* Go through inner loops (only original ones).  */
   FOR_EACH_LOOP (li, loop, LI_ONLY_INNERMOST)
@@ -102,6 +103,16 @@ tree_ssa_unswitch_loops (void)
           continue;
         }
 
+      /* If the loop is not expected to iterate, there is no need
+	 for unswitching.  */
+      iterations = estimated_loop_iterations_int (loop);
+      if (iterations >= 0 && iterations <= 1)
+	{
+          if (dump_file && (dump_flags & TDF_DETAILS))
+            fprintf (dump_file, ";; Not unswitching, loop is not expected to iterate\n");
+          continue;
+	}
+
       changed |= tree_unswitch_single_loop (loop, 0);
     }