*** old/src/share/vm/opto/phaseX.cpp	Tue Sep 28 18:04:11 2010
--- new/src/share/vm/opto/phaseX.cpp	Tue Sep 28 18:04:11 2010

*** 842,855 ****
--- 842,875 ----
        _verify_window[i] = NULL;
      }
    }
  #endif
  
+ #ifdef ASSERT
+   Node* prev = NULL;
+   uint rep_cnt = 0;
+   uint loop_count = 0;
+ #endif
    // Pull from worklist; transform node;
    // If node has changed: update edge info and put uses on worklist.
    while( _worklist.size() ) {
      Node *n  = _worklist.pop();
+ #ifdef ASSERT
+     if (++loop_count >= K * C->unique()) {
+       n->dump(4);
+       assert(false, "infinite loop in PhaseIterGVN::optimize");
+     }
+     if (n == prev) {
+       if (++rep_cnt > 3) {
+         n->dump(4);
+         assert(false, "loop in Ideal transformation");
+       }
+     } else {
+       rep_cnt = 0;
+     }
+     prev = n;
+ #endif
      if (TraceIterativeGVN && Verbose) {
        tty->print("  Pop ");
        NOT_PRODUCT( n->dump(); )
        debug_only(if( (num_processed++ % 100) == 0 ) _worklist.print_set();)
      }