[PATCH] Fix PR56689

[Richard Biener]

This fixes VRP to properly fixup loops when it removes edges from
the CFG.

Bootstrap and regtest running on x86_64-unknown-linux-gnu.

Richard.

2013-03-25  Richard Biener  <rguent...@suse.de>

        PR tree-optimization/56689
        * tree-vrp.c (execute_vrp): Mark loops for fixup if we removed
        any edge.

        * gcc.dg/torture/pr56689.c: New testcase.

Index: gcc/tree-vrp.c
===================================================================
--- gcc/tree-vrp.c      (revision 197029)
+++ gcc/tree-vrp.c      (working copy)
@@ -9329,7 +9329,11 @@ execute_vrp (void)
     }
 
   if (to_remove_edges.length () > 0)
-    free_dominance_info (CDI_DOMINATORS);
+    {
+      free_dominance_info (CDI_DOMINATORS);
+      if (current_loops)
+       loops_state_set (LOOPS_NEED_FIXUP);
+    }
 
   to_remove_edges.release ();
   to_update_switch_stmts.release ();
Index: gcc/testsuite/gcc.dg/torture/pr56689.c
===================================================================
--- gcc/testsuite/gcc.dg/torture/pr56689.c      (revision 0)
+++ gcc/testsuite/gcc.dg/torture/pr56689.c      (working copy)
@@ -0,0 +1,46 @@
+/* { dg-do compile } */
+
+extern int baz ();
+extern void bar (void);
+extern void noret (void)   __attribute__ ((__noreturn__));
+
+void
+fix_register (const char *name, int fixed, int call_used, int nregs)
+{
+  int i;
+  int reg;
+
+  if ((reg = baz ()) >= 0)
+    {
+      for (i = reg; i < nregs; i++)
+       {
+         if ((i == 15 || i == 11) && (fixed == 0 || call_used == 0))
+           {
+             switch (fixed)
+               {
+               case 0:
+                 switch (call_used)
+                   {
+                   case 1:
+                     bar ();
+                     break;
+                   default:
+                     (noret ());
+                   }
+               case 1:
+                 switch (call_used)
+                   {
+                   case 1:
+                     break;
+                   case 0:
+                   default:
+                     (noret ());
+                   }
+                 break;
+               default:
+                 (noret ());
+               }
+           }
+       }
+    }
+}