re PR rtl-optimization/32773 (SH: ICE in create_pre_exit, at mode-switching.c:223)

	PR rtl-optimization/32773
	* cfglayout.c (force_one_exit_fallthru): New function.
	(cfg_layout_finalize): Use it.

	* gcc.dg/pr32773.c: New test.

From-SVN: r126700

1 files changed, 51 insertions, 0 deletions

diff --git a/gcc/cfglayout.c b/gcc/cfglayout.c
index be4b087..e989344 100644
--- a/gcc/cfglayout.c
+++ b/gcc/cfglayout.c
@@ -963,6 +963,56 @@ fixup_fallthru_exit_predecessor (void)
       bb->aux = NULL;
     }
 }
+
+/* In case there are more than one fallthru predecessors of exit, force that
+   there is only one.  */
+
+static void
+force_one_exit_fallthru (void)
+{
+  edge e, predecessor = NULL;
+  bool more = false;
+  edge_iterator ei;
+  basic_block forwarder, bb;
+
+  FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
+    if (e->flags & EDGE_FALLTHRU)
+      {
+	if (predecessor == NULL)
+	  predecessor = e;
+	else
+	  {
+	    more = true;
+	    break;
+	  }
+      }
+
+  if (!more)
+    return;
+
+  /* Exit has several fallthru predecessors.  Create a forwarder block for
+     them.  */
+  forwarder = split_edge (predecessor);
+  for (ei = ei_start (EXIT_BLOCK_PTR->preds); (e = ei_safe_edge (ei)); )
+    {
+      if (e->src == forwarder
+	  || !(e->flags & EDGE_FALLTHRU))
+	ei_next (&ei);
+      else
+	redirect_edge_and_branch_force (e, forwarder);
+    }
+
+  /* Fix up the chain of blocks -- make FORWARDER immediately preceed the
+     exit block.  */
+  FOR_EACH_BB (bb)
+    {
+      if (bb->aux == NULL && bb != forwarder)
+	{
+	  bb->aux = forwarder;
+	  break;
+	}
+    }
+}
 
 /* Return true in case it is possible to duplicate the basic block BB.  */
 
@@ -1178,6 +1228,7 @@ cfg_layout_finalize (void)
 #ifdef ENABLE_CHECKING
   verify_flow_info ();
 #endif
+  force_one_exit_fallthru ();
   rtl_register_cfg_hooks ();
   if (reload_completed
 #ifdef HAVE_epilogue