*** old/src/share/vm/opto/loopnode.cpp	Wed Aug 10 12:44:31 2011
--- new/src/share/vm/opto/loopnode.cpp	Wed Aug 10 12:44:31 2011

*** 687,696 ****
--- 687,697 ----
  
  //----------------------exact_limit-------------------------------------------
  Node* PhaseIdealLoop::exact_limit( IdealLoopTree *loop ) {
    assert(loop->_head->is_CountedLoop(), "");
    CountedLoopNode *cl = loop->_head->as_CountedLoop();
+   assert(cl->is_valid_counted_loop(), "");
  
    if (!LoopLimitCheck || ABS(cl->stride_con()) == 1 ||
        cl->limit()->Opcode() == Op_LoopLimit) {
      // Old code has exact limit (it could be incorrect in case of int overflow).
      // Loop limit is exact with stride == 1. And loop may already have exact limit.

*** 1606,1623 ****
--- 1607,1623 ----
  //---------------------------replace_parallel_iv-------------------------------
  // Replace parallel induction variable (parallel to trip counter)
  void PhaseIdealLoop::replace_parallel_iv(IdealLoopTree *loop) {
    assert(loop->_head->is_CountedLoop(), "");
    CountedLoopNode *cl = loop->_head->as_CountedLoop();
+   if (!cl->is_valid_counted_loop())
+     return;         // skip malformed counted loop
    Node *incr = cl->incr();
    if (incr == NULL)
      return;         // Dead loop?
    Node *init = cl->init_trip();
    Node *phi  = cl->phi();
    // protect against stride not being a constant
    if (!cl->stride_is_con())
      return;
    int stride_con = cl->stride_con();
  
    PhaseGVN *gvn = &_igvn;
  
    // Visit all children, looking for Phis