re PR tree-optimization/21380 (ICE compiling with -O)

	PR tree-optimization/21380
	* tree-ssa-threadupdate.c (thread_through_all_blocks): Do not
	thread through a block with no preds.

 	* gcc.c-torture/compile/pr21380.c: New test.

From-SVN: r99324

gcc/ChangeLog

+2005-05-06  Jeff Law  <law@redhat.com>
+
+	PR tree-optimization/21380
+	* tree-ssa-threadupdate.c (thread_through_all_blocks): Do not
+	thread through a block with no preds.
+
 2005-05-06  Kazu Hirata  <kazu@cs.umass.edu>
 
 	* tree-ssa-operands.c (clobbered_v_may_defs, clobbered_vuses,

gcc/testsuite/ChangeLog

+2005-05-06  Jeff Law  <law@redhat.com>
+
+	* gcc.c-torture/compile/pr21380.c: New test.
+
 2005-05-06  Jakub Jelinek  <jakub@redhat.com>
 
 	PR c++/20961

gcc/testsuite/gcc.c-torture/compile/pr21380.c

+void bar (void);
+                                                                                
+void
+foo (int *diff)
+{
+  double deltay = 0.0;
+  int Stangent = 0;
+  int mindiff;
+  int Sflipped = 0;
+  int i;
+  int Sturn, Snofit;
+                                                                                
+  Sturn = 1;
+  if (Sturn)
+    Stangent = 1;
+  if (Sturn)
+    {
+      Sflipped = 0;
+      Snofit = 1;
+      while (Snofit)
+        {
+          Snofit = 0;
+          mindiff = 0;
+          for (i = 0; i < 4; i++)
+            mindiff = diff[i];
+          while (!Snofit && (mindiff < 0.0))
+            {
+              deltay = (Stangent ? deltay : 0.0);
+              if (deltay < 0.0)
+                Snofit = 1;
+              for (i = 0; i < 4; i++)
+                {
+                }
+            }
+          if (Snofit)
+            if (Sflipped)
+              break;
+        }
+      if (Snofit)
+        bar ();
+    }
+}

gcc/tree-ssa-threadupdate.c

@@ -811,7 +811,8 @@ thread_through_all_blocks (void)
 
   FOR_EACH_BB (bb)
     {
-      if (bb_ann (bb)->incoming_edge_threaded)
+      if (bb_ann (bb)->incoming_edge_threaded
+	  && EDGE_COUNT (bb->preds) > 0)
 	{
 	  retval |= thread_block (bb);
 	  bb_ann (bb)->incoming_edge_threaded = false;