changeset 2442:bad7ecd0b6ed

5091921: Sign flip issues in loop optimizer Summary: Fix integer overflow problem in the code generated by loop optimizer. Reviewed-by: never
author kvn
date Wed, 04 May 2011 13:12:42 -0700
parents 0139aac70fb5
children dcfb3dede009
files src/cpu/x86/vm/x86_32.ad src/share/vm/oops/methodDataOop.hpp src/share/vm/opto/bytecodeInfo.cpp src/share/vm/opto/c2_globals.hpp src/share/vm/opto/cfgnode.cpp src/share/vm/opto/classes.hpp src/share/vm/opto/graphKit.cpp src/share/vm/opto/ifnode.cpp src/share/vm/opto/loopPredicate.cpp src/share/vm/opto/loopTransform.cpp src/share/vm/opto/loopUnswitch.cpp src/share/vm/opto/loopnode.cpp src/share/vm/opto/loopnode.hpp src/share/vm/opto/macro.cpp src/share/vm/opto/matcher.cpp src/share/vm/opto/parse.hpp src/share/vm/opto/parse1.cpp src/share/vm/opto/phaseX.hpp src/share/vm/runtime/deoptimization.cpp src/share/vm/runtime/deoptimization.hpp test/compiler/5091921/Test5091921.java test/compiler/5091921/Test6186134.java test/compiler/5091921/Test6196102.java test/compiler/5091921/Test6357214.java test/compiler/5091921/Test6559156.java test/compiler/5091921/Test6753639.java test/compiler/5091921/Test6850611.java test/compiler/5091921/Test6890943.java test/compiler/5091921/Test6890943.sh test/compiler/5091921/Test6897150.java test/compiler/5091921/Test6905845.java test/compiler/5091921/Test6931567.java test/compiler/5091921/Test6935022.java test/compiler/5091921/Test6959129.java test/compiler/5091921/Test6985295.java test/compiler/5091921/Test6992759.java test/compiler/5091921/Test7005594.java test/compiler/5091921/Test7020614.java test/compiler/5091921/input6890943.txt test/compiler/5091921/output6890943.txt
diffstat 40 files changed, 4196 insertions(+), 215 deletions(-) [+]
line wrap: on
line diff
--- a/src/cpu/x86/vm/x86_32.ad	Wed May 04 03:42:58 2011 -0700
+++ b/src/cpu/x86/vm/x86_32.ad	Wed May 04 13:12:42 2011 -0700
@@ -12989,6 +12989,53 @@
 %}
 
 // ============================================================================
+// Counted Loop limit node which represents exact final iterator value.
+// Note: the resulting value should fit into integer range since
+// counted loops have limit check on overflow.
+instruct loopLimit_eReg(eAXRegI limit, nadxRegI init, immI stride, eDXRegI limit_hi, nadxRegI tmp, eFlagsReg flags) %{
+  match(Set limit (LoopLimit (Binary init limit) stride));
+  effect(TEMP limit_hi, TEMP tmp, KILL flags);
+  ins_cost(300);
+
+  format %{ "loopLimit $init,$limit,$stride  # $limit = $init + $stride *( $limit - $init + $stride -1)/ $stride, kills $limit_hi" %}
+  ins_encode %{
+    int strd = (int)$stride$$constant;
+    assert(strd != 1 && strd != -1, "sanity");
+    int m1 = (strd > 0) ? 1 : -1;
+    // Convert limit to long (EAX:EDX)
+    __ cdql();
+    // Convert init to long (init:tmp)
+    __ movl($tmp$$Register, $init$$Register);
+    __ sarl($tmp$$Register, 31);
+    // $limit - $init
+    __ subl($limit$$Register, $init$$Register);
+    __ sbbl($limit_hi$$Register, $tmp$$Register);
+    // + ($stride - 1)
+    if (strd > 0) {
+      __ addl($limit$$Register, (strd - 1));
+      __ adcl($limit_hi$$Register, 0);
+      __ movl($tmp$$Register, strd);
+    } else {
+      __ addl($limit$$Register, (strd + 1));
+      __ adcl($limit_hi$$Register, -1);
+      __ lneg($limit_hi$$Register, $limit$$Register);
+      __ movl($tmp$$Register, -strd);
+    }
+    // signed devision: (EAX:EDX) / pos_stride
+    __ idivl($tmp$$Register);
+    if (strd < 0) {
+      // restore sign
+      __ negl($tmp$$Register);
+    }
+    // (EAX) * stride
+    __ mull($tmp$$Register);
+    // + init (ignore upper bits)
+    __ addl($limit$$Register, $init$$Register);
+  %}
+  ins_pipe( pipe_slow );
+%}
+
+// ============================================================================
 // Branch Instructions
 // Jump Table
 instruct jumpXtnd(eRegI switch_val) %{
--- a/src/share/vm/oops/methodDataOop.hpp	Wed May 04 03:42:58 2011 -0700
+++ b/src/share/vm/oops/methodDataOop.hpp	Wed May 04 13:12:42 2011 -0700
@@ -1194,7 +1194,7 @@
   // Whole-method sticky bits and flags
 public:
   enum {
-    _trap_hist_limit    = 16,   // decoupled from Deoptimization::Reason_LIMIT
+    _trap_hist_limit    = 17,   // decoupled from Deoptimization::Reason_LIMIT
     _trap_hist_mask     = max_jubyte,
     _extra_data_count   = 4     // extra DataLayout headers, for trap history
   }; // Public flag values
--- a/src/share/vm/opto/bytecodeInfo.cpp	Wed May 04 03:42:58 2011 -0700
+++ b/src/share/vm/opto/bytecodeInfo.cpp	Wed May 04 13:12:42 2011 -0700
@@ -373,7 +373,6 @@
   return true;
 }
 
-#ifndef PRODUCT
 //------------------------------print_inlining---------------------------------
 // Really, the failure_msg can be a success message also.
 void InlineTree::print_inlining(ciMethod* callee_method, int caller_bci, const char* failure_msg) const {
@@ -385,7 +384,6 @@
     tty->print("  bcs: %d+%d  invoked: %d", top->count_inline_bcs(), callee_method->code_size(), callee_method->interpreter_invocation_count());
   }
 }
-#endif
 
 //------------------------------ok_to_inline-----------------------------------
 WarmCallInfo* InlineTree::ok_to_inline(ciMethod* callee_method, JVMState* jvms, ciCallProfile& profile, WarmCallInfo* initial_wci) {
--- a/src/share/vm/opto/c2_globals.hpp	Wed May 04 03:42:58 2011 -0700
+++ b/src/share/vm/opto/c2_globals.hpp	Wed May 04 13:12:42 2011 -0700
@@ -183,6 +183,21 @@
   develop(bool, TraceLoopOpts, false,                                       \
           "Trace executed loop optimizations")                              \
                                                                             \
+  diagnostic(bool, LoopLimitCheck, true,                                    \
+          "Generate a loop limits check for overflow")                      \
+                                                                            \
+  develop(bool, TraceLoopLimitCheck, false,                                 \
+          "Trace generation of loop limits checks")                         \
+                                                                            \
+  diagnostic(bool, RangeLimitCheck, true,                                   \
+          "Additional overflow checks during range check elimination")      \
+                                                                            \
+  develop(bool, TraceRangeLimitCheck, false,                                \
+          "Trace additional overflow checks in RCE")                        \
+                                                                            \
+  diagnostic(bool, UnrollLimitCheck, true,                                  \
+          "Additional overflow checks during loop unroll")                  \
+                                                                            \
   product(bool, OptimizeFill, false,                                        \
           "convert fill/copy loops into intrinsic")                         \
                                                                             \
--- a/src/share/vm/opto/cfgnode.cpp	Wed May 04 03:42:58 2011 -0700
+++ b/src/share/vm/opto/cfgnode.cpp	Wed May 04 13:12:42 2011 -0700
@@ -1373,7 +1373,7 @@
 
   // Clone loop predicates
   if (predicate_proj != NULL) {
-    newn = igvn->clone_loop_predicates(predicate_proj, newn);
+    newn = igvn->clone_loop_predicates(predicate_proj, newn, !n->is_CountedLoop());
   }
 
   // Now I can point to the new node.
--- a/src/share/vm/opto/classes.hpp	Wed May 04 03:42:58 2011 -0700
+++ b/src/share/vm/opto/classes.hpp	Wed May 04 13:12:42 2011 -0700
@@ -156,6 +156,7 @@
 macro(LogD)
 macro(Log10D)
 macro(Loop)
+macro(LoopLimit)
 macro(Mach)
 macro(MachProj)
 macro(MaxI)
--- a/src/share/vm/opto/graphKit.cpp	Wed May 04 03:42:58 2011 -0700
+++ b/src/share/vm/opto/graphKit.cpp	Wed May 04 13:12:42 2011 -0700
@@ -3378,6 +3378,10 @@
   if (UseLoopPredicate) {
     add_predicate_impl(Deoptimization::Reason_predicate, nargs);
   }
+  // loop's limit check predicate should be near the loop.
+  if (LoopLimitCheck) {
+    add_predicate_impl(Deoptimization::Reason_loop_limit_check, nargs);
+  }
 }
 
 //----------------------------- store barriers ----------------------------
--- a/src/share/vm/opto/ifnode.cpp	Wed May 04 03:42:58 2011 -0700
+++ b/src/share/vm/opto/ifnode.cpp	Wed May 04 13:12:42 2011 -0700
@@ -236,6 +236,7 @@
   }
   Node* predicate_c = NULL;
   Node* predicate_x = NULL;
+  bool counted_loop = r->is_CountedLoop();
 
   Node *region_c = new (igvn->C, req_c + 1) RegionNode(req_c + 1);
   Node *phi_c    = con1;
@@ -294,16 +295,16 @@
   if (predicate_c != NULL) {
     assert(predicate_x == NULL, "only one predicate entry expected");
     // Clone loop predicates to each path
-    iff_c_t = igvn->clone_loop_predicates(predicate_c, iff_c_t);
-    iff_c_f = igvn->clone_loop_predicates(predicate_c, iff_c_f);
+    iff_c_t = igvn->clone_loop_predicates(predicate_c, iff_c_t, !counted_loop);
+    iff_c_f = igvn->clone_loop_predicates(predicate_c, iff_c_f, !counted_loop);
   }
   Node *iff_x_t = phase->transform(new (igvn->C, 1) IfTrueNode (iff_x));
   Node *iff_x_f = phase->transform(new (igvn->C, 1) IfFalseNode(iff_x));
   if (predicate_x != NULL) {
     assert(predicate_c == NULL, "only one predicate entry expected");
     // Clone loop predicates to each path
-    iff_x_t = igvn->clone_loop_predicates(predicate_x, iff_x_t);
-    iff_x_f = igvn->clone_loop_predicates(predicate_x, iff_x_f);
+    iff_x_t = igvn->clone_loop_predicates(predicate_x, iff_x_t, !counted_loop);
+    iff_x_f = igvn->clone_loop_predicates(predicate_x, iff_x_f, !counted_loop);
   }
 
   // Merge the TRUE paths
--- a/src/share/vm/opto/loopPredicate.cpp	Wed May 04 03:42:58 2011 -0700
+++ b/src/share/vm/opto/loopPredicate.cpp	Wed May 04 13:12:42 2011 -0700
@@ -341,7 +341,7 @@
   // Cut predicate from old place.
   Node* old = predicate_proj;
   igvn->_worklist.push(old);
-  for (DUIterator_Last imin, i = old->last_outs(imin); i >= imin; ) {
+  for (DUIterator_Last imin, i = old->last_outs(imin); i >= imin;) {
     Node* use = old->last_out(i);  // for each use...
     igvn->hash_delete(use);
     igvn->_worklist.push(use);
@@ -384,24 +384,25 @@
 
 //--------------------------clone_loop_predicates-----------------------
 // Interface from IGVN
-Node* PhaseIterGVN::clone_loop_predicates(Node* old_entry, Node* new_entry) {
-  return PhaseIdealLoop::clone_loop_predicates(old_entry, new_entry, false, NULL, this);
+Node* PhaseIterGVN::clone_loop_predicates(Node* old_entry, Node* new_entry, bool clone_limit_check) {
+  return PhaseIdealLoop::clone_loop_predicates(old_entry, new_entry, false, clone_limit_check, NULL, this);
 }
-Node* PhaseIterGVN::move_loop_predicates(Node* old_entry, Node* new_entry) {
-  return PhaseIdealLoop::clone_loop_predicates(old_entry, new_entry, true, NULL, this);
+Node* PhaseIterGVN::move_loop_predicates(Node* old_entry, Node* new_entry, bool clone_limit_check) {
+  return PhaseIdealLoop::clone_loop_predicates(old_entry, new_entry, true, clone_limit_check, NULL, this);
 }
 
 // Interface from PhaseIdealLoop
-Node* PhaseIdealLoop::clone_loop_predicates(Node* old_entry, Node* new_entry) {
-  return clone_loop_predicates(old_entry, new_entry, false, this, &this->_igvn);
+Node* PhaseIdealLoop::clone_loop_predicates(Node* old_entry, Node* new_entry, bool clone_limit_check) {
+  return clone_loop_predicates(old_entry, new_entry, false, clone_limit_check, this, &this->_igvn);
 }
-Node* PhaseIdealLoop::move_loop_predicates(Node* old_entry, Node* new_entry) {
-  return clone_loop_predicates(old_entry, new_entry, true, this, &this->_igvn);
+Node* PhaseIdealLoop::move_loop_predicates(Node* old_entry, Node* new_entry, bool clone_limit_check) {
+  return clone_loop_predicates(old_entry, new_entry, true, clone_limit_check, this, &this->_igvn);
 }
 
 // Clone loop predicates to cloned loops (peeled, unswitched, split_if).
 Node* PhaseIdealLoop::clone_loop_predicates(Node* old_entry, Node* new_entry,
                                                 bool move_predicates,
+                                                bool clone_limit_check,
                                                 PhaseIdealLoop* loop_phase,
                                                 PhaseIterGVN* igvn) {
 #ifdef ASSERT
@@ -413,10 +414,16 @@
 #endif
   // Search original predicates
   Node* entry = old_entry;
+  ProjNode* limit_check_proj = NULL;
+  if (LoopLimitCheck) {
+    limit_check_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check);
+    if (limit_check_proj != NULL) {
+      entry = entry->in(0)->in(0);
+    }
+  }
   if (UseLoopPredicate) {
     ProjNode* predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
     if (predicate_proj != NULL) { // right pattern that can be used by loop predication
-      assert(entry->in(0)->in(1)->in(1)->Opcode()==Op_Opaque1, "must be");
       if (move_predicates) {
         new_entry =  move_predicate(predicate_proj, new_entry,
                                     Deoptimization::Reason_predicate,
@@ -435,11 +442,37 @@
       }
     }
   }
+  if (limit_check_proj != NULL && clone_limit_check) {
+    // Clone loop limit check last to insert it before loop.
+    // Don't clone a limit check which was already finalized
+    // for this counted loop (only one limit check is needed).
+    if (move_predicates) {
+      new_entry =  move_predicate(limit_check_proj, new_entry,
+                                  Deoptimization::Reason_loop_limit_check,
+                                  loop_phase, igvn);
+      assert(new_entry == limit_check_proj, "old limit check fall through projection");
+    } else {
+      new_entry = clone_predicate(limit_check_proj, new_entry,
+                                  Deoptimization::Reason_loop_limit_check,
+                                  loop_phase, igvn);
+      assert(new_entry != NULL && new_entry->is_Proj(), "IfTrue or IfFalse after clone limit check");
+    }
+    if (TraceLoopLimitCheck) {
+      tty->print_cr("Loop Limit Check %s: ", move_predicates ? "moved" : "cloned");
+      debug_only( new_entry->in(0)->dump(); )
+    }
+  }
   return new_entry;
 }
 
 //--------------------------eliminate_loop_predicates-----------------------
 void PhaseIdealLoop::eliminate_loop_predicates(Node* entry) {
+  if (LoopLimitCheck) {
+    Node* predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check);
+    if (predicate != NULL) {
+      entry = entry->in(0)->in(0);
+    }
+  }
   if (UseLoopPredicate) {
     ProjNode* predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
     if (predicate_proj != NULL) { // right pattern that can be used by loop predication
@@ -456,10 +489,15 @@
 // Skip related predicates.
 Node* PhaseIdealLoop::skip_loop_predicates(Node* entry) {
   Node* predicate = NULL;
+  if (LoopLimitCheck) {
+    predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check);
+    if (predicate != NULL) {
+      entry = entry->in(0)->in(0);
+    }
+  }
   if (UseLoopPredicate) {
     predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
     if (predicate != NULL) { // right pattern that can be used by loop predication
-      assert(entry->is_Proj() && entry->in(0)->in(1)->in(1)->Opcode()==Op_Opaque1, "must be");
       IfNode* iff = entry->in(0)->as_If();
       ProjNode* uncommon_proj = iff->proj_out(1 - entry->as_Proj()->_con);
       Node* rgn = uncommon_proj->unique_ctrl_out();
@@ -491,10 +529,15 @@
 // Find a predicate
 Node* PhaseIdealLoop::find_predicate(Node* entry) {
   Node* predicate = NULL;
+  if (LoopLimitCheck) {
+    predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check);
+    if (predicate != NULL) { // right pattern that can be used by loop predication
+      return entry;
+    }
+  }
   if (UseLoopPredicate) {
     predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
     if (predicate != NULL) { // right pattern that can be used by loop predication
-      assert(entry->in(0)->in(1)->in(1)->Opcode()==Op_Opaque1, "must be");
       return entry;
     }
   }
@@ -658,7 +701,7 @@
   Node* range = cmp->in(2);
   if (range->Opcode() != Op_LoadRange) {
     const TypeInt* tint = phase->_igvn.type(range)->isa_int();
-    if (!OptimizeFill || tint == NULL || tint->empty() || tint->_lo < 0) {
+    if (tint == NULL || tint->empty() || tint->_lo < 0) {
       // Allow predication on positive values that aren't LoadRanges.
       // This allows optimization of loops where the length of the
       // array is a known value and doesn't need to be loaded back
@@ -696,7 +739,7 @@
 //   max(scale*i + offset) = scale*(limit-stride) + offset
 // (2) stride*scale < 0
 //   max(scale*i + offset) = scale*init + offset
-BoolNode* PhaseIdealLoop::rc_predicate(Node* ctrl,
+BoolNode* PhaseIdealLoop::rc_predicate(IdealLoopTree *loop, Node* ctrl,
                                        int scale, Node* offset,
                                        Node* init, Node* limit, Node* stride,
                                        Node* range, bool upper) {
@@ -709,9 +752,19 @@
   Node* max_idx_expr  = init;
   int stride_con = stride->get_int();
   if ((stride_con > 0) == (scale > 0) == upper) {
-    max_idx_expr = new (C, 3) SubINode(limit, stride);
-    register_new_node(max_idx_expr, ctrl);
-    if (TraceLoopPredicate) predString->print("(limit - stride) ");
+    if (LoopLimitCheck) {
+      // With LoopLimitCheck limit is not exact.
+      // Calculate exact limit here.
+      // Note, counted loop's test is '<' or '>'.
+      limit = exact_limit(loop);
+      max_idx_expr = new (C, 3) SubINode(limit, stride);
+      register_new_node(max_idx_expr, ctrl);
+      if (TraceLoopPredicate) predString->print("(limit - stride) ");
+    } else {
+      max_idx_expr = new (C, 3) SubINode(limit, stride);
+      register_new_node(max_idx_expr, ctrl);
+      if (TraceLoopPredicate) predString->print("(limit - stride) ");
+    }
   } else {
     if (TraceLoopPredicate) predString->print("init ");
   }
@@ -752,29 +805,36 @@
     // Could be a simple region when irreducible loops are present.
     return false;
   }
+  LoopNode* head = loop->_head->as_Loop();
 
-  if (loop->_head->unique_ctrl_out()->Opcode() == Op_NeverBranch) {
+  if (head->unique_ctrl_out()->Opcode() == Op_NeverBranch) {
     // do nothing for infinite loops
     return false;
   }
 
   CountedLoopNode *cl = NULL;
-  if (loop->_head->is_CountedLoop()) {
-    cl = loop->_head->as_CountedLoop();
+  if (head->is_CountedLoop()) {
+    cl = head->as_CountedLoop();
     // do nothing for iteration-splitted loops
     if (!cl->is_normal_loop()) return false;
   }
 
-  LoopNode *lpn  = loop->_head->as_Loop();
-  Node* entry = lpn->in(LoopNode::EntryControl);
+  Node* entry = head->in(LoopNode::EntryControl);
+  ProjNode *predicate_proj = NULL;
+  // Loop limit check predicate should be near the loop.
+  if (LoopLimitCheck) {
+    predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check);
+    if (predicate_proj != NULL)
+      entry = predicate_proj->in(0)->in(0);
+  }
 
-  ProjNode *predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
+  predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
   if (!predicate_proj) {
 #ifndef PRODUCT
     if (TraceLoopPredicate) {
       tty->print("missing predicate:");
       loop->dump_head();
-      lpn->dump(1);
+      head->dump(1);
     }
 #endif
     return false;
@@ -788,7 +848,6 @@
   // Create list of if-projs such that a newer proj dominates all older
   // projs in the list, and they all dominate loop->tail()
   Node_List if_proj_list(area);
-  LoopNode *head  = loop->_head->as_Loop();
   Node *current_proj = loop->tail(); //start from tail
   while (current_proj != head) {
     if (loop == get_loop(current_proj) && // still in the loop ?
@@ -862,8 +921,8 @@
       const Node*    cmp    = bol->in(1)->as_Cmp();
       Node*          idx    = cmp->in(1);
       assert(!invar.is_invariant(idx), "index is variant");
-      assert(cmp->in(2)->Opcode() == Op_LoadRange || OptimizeFill, "must be");
       Node* rng = cmp->in(2);
+      assert(rng->Opcode() == Op_LoadRange || _igvn.type(rng)->is_int() >= 0, "must be");
       assert(invar.is_invariant(rng), "range must be invariant");
       int scale    = 1;
       Node* offset = zero;
@@ -892,14 +951,14 @@
       }
 
       // Test the lower bound
-      Node*  lower_bound_bol = rc_predicate(ctrl, scale, offset, init, limit, stride, rng, false);
+      Node*  lower_bound_bol = rc_predicate(loop, ctrl, scale, offset, init, limit, stride, rng, false);
       IfNode* lower_bound_iff = lower_bound_proj->in(0)->as_If();
       _igvn.hash_delete(lower_bound_iff);
       lower_bound_iff->set_req(1, lower_bound_bol);
       if (TraceLoopPredicate) tty->print_cr("lower bound check if: %d", lower_bound_iff->_idx);
 
       // Test the upper bound
-      Node* upper_bound_bol = rc_predicate(ctrl, scale, offset, init, limit, stride, rng, true);
+      Node* upper_bound_bol = rc_predicate(loop, ctrl, scale, offset, init, limit, stride, rng, true);
       IfNode* upper_bound_iff = upper_bound_proj->in(0)->as_If();
       _igvn.hash_delete(upper_bound_iff);
       upper_bound_iff->set_req(1, upper_bound_bol);
--- a/src/share/vm/opto/loopTransform.cpp	Wed May 04 03:42:58 2011 -0700
+++ b/src/share/vm/opto/loopTransform.cpp	Wed May 04 13:12:42 2011 -0700
@@ -83,7 +83,7 @@
 #ifdef ASSERT
   BoolTest::mask bt = cl->loopexit()->test_trip();
   assert(bt == BoolTest::lt || bt == BoolTest::gt ||
-         bt == BoolTest::ne, "canonical test is expected");
+         (bt == BoolTest::ne && !LoopLimitCheck), "canonical test is expected");
 #endif
 
   Node* init_n = cl->init_trip();
@@ -510,7 +510,7 @@
   //         the pre-loop with only 1 user (the new peeled iteration), but the
   //         peeled-loop backedge has 2 users.
   Node* new_exit_value = old_new[head->in(LoopNode::LoopBackControl)->_idx];
-  new_exit_value = move_loop_predicates(entry, new_exit_value);
+  new_exit_value = move_loop_predicates(entry, new_exit_value, !counted_loop);
   _igvn.hash_delete(head);
   head->set_req(LoopNode::EntryControl, new_exit_value);
   for (DUIterator_Fast jmax, j = head->fast_outs(jmax); j < jmax; j++) {
@@ -593,6 +593,12 @@
     return false;
   }
 
+  // Fully unroll a loop with few iterations regardless next
+  // conditions since following loop optimizations will split
+  // such loop anyway (pre-main-post).
+  if (trip_count <= 3)
+    return true;
+
   // Take into account that after unroll conjoined heads and tails will fold,
   // otherwise policy_unroll() may allow more unrolling than max unrolling.
   uint new_body_size = EMPTY_LOOP_SIZE + (body_size - EMPTY_LOOP_SIZE) * trip_count;
@@ -605,15 +611,6 @@
     return false;
   }
 
-  // Currently we don't have policy to optimize one iteration loops.
-  // Maximally unrolling transformation is used for that:
-  // it is peeled and the original loop become non reachable (dead).
-  // Also fully unroll a loop with few iterations regardless next
-  // conditions since following loop optimizations will split
-  // such loop anyway (pre-main-post).
-  if (trip_count <= 3)
-    return true;
-
   // Do not unroll a loop with String intrinsics code.
   // String intrinsics are large and have loops.
   for (uint k = 0; k < _body.size(); k++) {
@@ -645,8 +642,9 @@
   if (!cl->is_valid_counted_loop())
     return false; // Malformed counted loop
 
-  // protect against over-unrolling
-  if (cl->trip_count() <= 1) return false;
+  // Protect against over-unrolling.
+  // After split at least one iteration will be executed in pre-loop.
+  if (cl->trip_count() <= (uint)(cl->is_normal_loop() ? 2 : 1)) return false;
 
   int future_unroll_ct = cl->unrolled_count() * 2;
   if (future_unroll_ct > MAX_UNROLL) return false;
@@ -678,6 +676,7 @@
 
   Node *init_n = cl->init_trip();
   Node *limit_n = cl->limit();
+  int stride_con = cl->stride_con();
   // Non-constant bounds.
   // Protect against over-unrolling when init or/and limit are not constant
   // (so that trip_count's init value is maxint) but iv range is known.
@@ -687,7 +686,7 @@
     if (phi != NULL) {
       assert(phi->is_Phi() && phi->in(0) == _head, "Counted loop should have iv phi.");
       const TypeInt* iv_type = phase->_igvn.type(phi)->is_int();
-      int next_stride = cl->stride_con() * 2; // stride after this unroll
+      int next_stride = stride_con * 2; // stride after this unroll
       if (next_stride > 0) {
         if (iv_type->_lo + next_stride <= iv_type->_lo || // overflow
             iv_type->_lo + next_stride >  iv_type->_hi) {
@@ -702,15 +701,19 @@
     }
   }
 
+  // After unroll limit will be adjusted: new_limit = limit-stride.
+  // Bailout if adjustment overflow.
+  const TypeInt* limit_type = phase->_igvn.type(limit_n)->is_int();
+  if (stride_con > 0 && ((limit_type->_hi - stride_con) >= limit_type->_hi) ||
+      stride_con < 0 && ((limit_type->_lo - stride_con) <= limit_type->_lo))
+    return false;  // overflow
+
   // Adjust body_size to determine if we unroll or not
   uint body_size = _body.size();
-  // Key test to unroll CaffeineMark's Logic test
-  int xors_in_loop = 0;
   // Also count ModL, DivL and MulL which expand mightly
   for (uint k = 0; k < _body.size(); k++) {
     Node* n = _body.at(k);
     switch (n->Opcode()) {
-      case Op_XorI: xors_in_loop++; break; // CaffeineMark's Logic test
       case Op_ModL: body_size += 30; break;
       case Op_DivL: body_size += 30; break;
       case Op_MulL: body_size += 10; break;
@@ -727,8 +730,7 @@
 
   // Check for being too big
   if (body_size > (uint)LoopUnrollLimit) {
-    if (xors_in_loop >= 4 && body_size < (uint)LoopUnrollLimit*4) return true;
-    // Normal case: loop too big
+     // Normal case: loop too big
     return false;
   }
 
@@ -750,28 +752,31 @@
 // Return TRUE or FALSE if the loop should be range-check-eliminated.
 // Actually we do iteration-splitting, a more powerful form of RCE.
 bool IdealLoopTree::policy_range_check( PhaseIdealLoop *phase ) const {
-  if( !RangeCheckElimination ) return false;
+  if (!RangeCheckElimination) return false;
 
   CountedLoopNode *cl = _head->as_CountedLoop();
   // If we unrolled with no intention of doing RCE and we later
   // changed our minds, we got no pre-loop.  Either we need to
   // make a new pre-loop, or we gotta disallow RCE.
-  if( cl->is_main_no_pre_loop() ) return false; // Disallowed for now.
+  if (cl->is_main_no_pre_loop()) return false; // Disallowed for now.
   Node *trip_counter = cl->phi();
 
   // Check loop body for tests of trip-counter plus loop-invariant vs
   // loop-invariant.
-  for( uint i = 0; i < _body.size(); i++ ) {
+  for (uint i = 0; i < _body.size(); i++) {
     Node *iff = _body[i];
-    if( iff->Opcode() == Op_If ) { // Test?
+    if (iff->Opcode() == Op_If) { // Test?
 
       // Comparing trip+off vs limit
       Node *bol = iff->in(1);
-      if( bol->req() != 2 ) continue; // dead constant test
+      if (bol->req() != 2) continue; // dead constant test
       if (!bol->is_Bool()) {
         assert(UseLoopPredicate && bol->Opcode() == Op_Conv2B, "predicate check only");
         continue;
       }
+      if (bol->as_Bool()->_test._test == BoolTest::ne)
+        continue; // not RC
+
       Node *cmp = bol->in(1);
 
       Node *rc_exp = cmp->in(1);
@@ -1067,6 +1072,7 @@
   // negative stride use >
 
   if (pre_end->in(CountedLoopEndNode::TestValue)->as_Bool()->_test._test == BoolTest::ne) {
+    assert(!LoopLimitCheck, "only canonical tests (lt or gt) are expected");
 
     BoolTest::mask new_test = (main_end->stride_con() > 0) ? BoolTest::lt : BoolTest::gt;
     // Modify pre loop end condition
@@ -1093,6 +1099,9 @@
   main_head->set_main_loop();
   if( peel_only ) main_head->set_main_no_pre_loop();
 
+  // Subtract a trip count for the pre-loop.
+  main_head->set_trip_count(main_head->trip_count() - 1);
+
   // It's difficult to be precise about the trip-counts
   // for the pre/post loops.  They are usually very short,
   // so guess that 4 trips is a reasonable value.
@@ -1126,9 +1135,9 @@
     loop->dump_head();
   } else if (TraceLoopOpts) {
     if (loop_head->trip_count() < (uint)LoopUnrollLimit) {
-      tty->print("Unroll  %d(%2d) ", loop_head->unrolled_count()*2, loop_head->trip_count());
+      tty->print("Unroll %d(%2d) ", loop_head->unrolled_count()*2, loop_head->trip_count());
     } else {
-      tty->print("Unroll  %d     ", loop_head->unrolled_count()*2);
+      tty->print("Unroll %d     ", loop_head->unrolled_count()*2);
     }
     loop->dump_head();
   }
@@ -1144,7 +1153,8 @@
   Node *stride = loop_head->stride();
 
   Node *opaq = NULL;
-  if( adjust_min_trip ) {       // If not maximally unrolling, need adjustment
+  if (adjust_min_trip) {       // If not maximally unrolling, need adjustment
+    // Search for zero-trip guard.
     assert( loop_head->is_main_loop(), "" );
     assert( ctrl->Opcode() == Op_IfTrue || ctrl->Opcode() == Op_IfFalse, "" );
     Node *iff = ctrl->in(0);
@@ -1154,63 +1164,202 @@
     Node *cmp = bol->in(1);
     assert( cmp->Opcode() == Op_CmpI, "" );
     opaq = cmp->in(2);
-    // Occasionally it's possible for a pre-loop Opaque1 node to be
+    // Occasionally it's possible for a zero-trip guard Opaque1 node to be
     // optimized away and then another round of loop opts attempted.
     // We can not optimize this particular loop in that case.
-    if( opaq->Opcode() != Op_Opaque1 )
-      return;                   // Cannot find pre-loop!  Bail out!
+    if (opaq->Opcode() != Op_Opaque1)
+      return; // Cannot find zero-trip guard!  Bail out!
+    // Zero-trip test uses an 'opaque' node which is not shared.
+    assert(opaq->outcnt() == 1 && opaq->in(1) == limit, "");
   }
 
   C->set_major_progress();
 
-  // Adjust max trip count. The trip count is intentionally rounded
-  // down here (e.g. 15-> 7-> 3-> 1) because if we unwittingly over-unroll,
-  // the main, unrolled, part of the loop will never execute as it is protected
-  // by the min-trip test.  See bug 4834191 for a case where we over-unrolled
-  // and later determined that part of the unrolled loop was dead.
-  loop_head->set_trip_count(loop_head->trip_count() / 2);
+  Node* new_limit = NULL;
+  if (UnrollLimitCheck) {
+    int stride_con = stride->get_int();
+    int stride_p = (stride_con > 0) ? stride_con : -stride_con;
+    uint old_trip_count = loop_head->trip_count();
+    // Verify that unroll policy result is still valid.
+    assert(old_trip_count > 1 &&
+           (!adjust_min_trip || stride_p <= (1<<3)*loop_head->unrolled_count()), "sanity");
 
-  // Double the count of original iterations in the unrolled loop body.
-  loop_head->double_unrolled_count();
+    // Adjust loop limit to keep valid iterations number after unroll.
+    // Use (limit - stride) instead of (((limit - init)/stride) & (-2))*stride
+    // which may overflow.
+    if (!adjust_min_trip) {
+      assert(old_trip_count > 1 && (old_trip_count & 1) == 0,
+             "odd trip count for maximally unroll");
+      // Don't need to adjust limit for maximally unroll since trip count is even.
+    } else if (loop_head->has_exact_trip_count() && init->is_Con()) {
+      // Loop's limit is constant. Loop's init could be constant when pre-loop
+      // become peeled iteration.
+      long init_con = init->get_int();
+      // We can keep old loop limit if iterations count stays the same:
+      //   old_trip_count == new_trip_count * 2
+      // Note: since old_trip_count >= 2 then new_trip_count >= 1
+      // so we also don't need to adjust zero trip test.
+      long limit_con  = limit->get_int();
+      // (stride_con*2) not overflow since stride_con <= 8.
+      int new_stride_con = stride_con * 2;
+      int stride_m    = new_stride_con - (stride_con > 0 ? 1 : -1);
+      long trip_count = (limit_con - init_con + stride_m)/new_stride_con;
+      // New trip count should satisfy next conditions.
+      assert(trip_count > 0 && (julong)trip_count < (julong)max_juint/2, "sanity");
+      uint new_trip_count = (uint)trip_count;
+      adjust_min_trip = (old_trip_count != new_trip_count*2);
+    }
 
-  // -----------
-  // Step 2: Cut back the trip counter for an unroll amount of 2.
-  // Loop will normally trip (limit - init)/stride_con.  Since it's a
-  // CountedLoop this is exact (stride divides limit-init exactly).
-  // We are going to double the loop body, so we want to knock off any
-  // odd iteration: (trip_cnt & ~1).  Then back compute a new limit.
-  Node *span = new (C, 3) SubINode( limit, init );
-  register_new_node( span, ctrl );
-  Node *trip = new (C, 3) DivINode( 0, span, stride );
-  register_new_node( trip, ctrl );
-  Node *mtwo = _igvn.intcon(-2);
-  set_ctrl(mtwo, C->root());
-  Node *rond = new (C, 3) AndINode( trip, mtwo );
-  register_new_node( rond, ctrl );
-  Node *spn2 = new (C, 3) MulINode( rond, stride );
-  register_new_node( spn2, ctrl );
-  Node *lim2 = new (C, 3) AddINode( spn2, init );
-  register_new_node( lim2, ctrl );
+    if (adjust_min_trip) {
+      // Step 2: Adjust the trip limit if it is called for.
+      // The adjustment amount is -stride. Need to make sure if the
+      // adjustment underflows or overflows, then the main loop is skipped.
+      Node* cmp = loop_end->cmp_node();
+      assert(cmp->in(2) == limit, "sanity");
+      assert(opaq != NULL && opaq->in(1) == limit, "sanity");
 
-  // Hammer in the new limit
-  Node *ctrl2 = loop_end->in(0);
-  Node *cmp2 = new (C, 3) CmpINode( loop_head->incr(), lim2 );
-  register_new_node( cmp2, ctrl2 );
-  Node *bol2 = new (C, 2) BoolNode( cmp2, loop_end->test_trip() );
-  register_new_node( bol2, ctrl2 );
-  _igvn.hash_delete(loop_end);
-  loop_end->set_req(CountedLoopEndNode::TestValue, bol2);
+      // Verify that policy_unroll result is still valid.
+      const TypeInt* limit_type = _igvn.type(limit)->is_int();
+      assert(stride_con > 0 && ((limit_type->_hi - stride_con) < limit_type->_hi) ||
+             stride_con < 0 && ((limit_type->_lo - stride_con) > limit_type->_lo), "sanity");
 
-  // Step 3: Find the min-trip test guaranteed before a 'main' loop.
-  // Make it a 1-trip test (means at least 2 trips).
-  if( adjust_min_trip ) {
-    // Guard test uses an 'opaque' node which is not shared.  Hence I
-    // can edit it's inputs directly.  Hammer in the new limit for the
-    // minimum-trip guard.
-    assert( opaq->outcnt() == 1, "" );
-    _igvn.hash_delete(opaq);
-    opaq->set_req(1, lim2);
-  }
+      if (limit->is_Con()) {
+        // The check in policy_unroll and the assert above guarantee
+        // no underflow if limit is constant.
+        new_limit = _igvn.intcon(limit->get_int() - stride_con);
+        set_ctrl(new_limit, C->root());
+      } else {
+        if (stride_con > 0 && ((limit_type->_lo - stride_con) < limit_type->_lo) ||
+                   stride_con < 0 && ((limit_type->_hi - stride_con) > limit_type->_hi)) {
+          // No underflow.
+          new_limit = new (C, 3) SubINode(limit, stride);
+        } else {
+          // (limit - stride) may underflow.
+          // Clamp the adjustment value with MININT or MAXINT:
+          //
+          //   new_limit = limit-stride
+          //   if (stride > 0)
+          //     new_limit = (limit < new_limit) ? MININT : new_limit;
+          //   else
+          //     new_limit = (limit > new_limit) ? MAXINT : new_limit;
+          //
+          BoolTest::mask bt = loop_end->test_trip();
+          assert(bt == BoolTest::lt || bt == BoolTest::gt, "canonical test is expected");
+          Node* adj_max = _igvn.intcon((stride_con > 0) ? min_jint : max_jint);
+          set_ctrl(adj_max, C->root());
+          Node* old_limit = NULL;
+          Node* adj_limit = NULL;
+          Node* bol = limit->is_CMove() ? limit->in(CMoveNode::Condition) : NULL;
+          if (loop_head->unrolled_count() > 1 &&
+              limit->is_CMove() && limit->Opcode() == Op_CMoveI &&
+              limit->in(CMoveNode::IfTrue) == adj_max &&
+              bol->as_Bool()->_test._test == bt &&
+              bol->in(1)->Opcode() == Op_CmpI &&
+              bol->in(1)->in(2) == limit->in(CMoveNode::IfFalse)) {
+            // Loop was unrolled before.
+            // Optimize the limit to avoid nested CMove:
+            // use original limit as old limit.
+            old_limit = bol->in(1)->in(1);
+            // Adjust previous adjusted limit.
+            adj_limit = limit->in(CMoveNode::IfFalse);
+            adj_limit = new (C, 3) SubINode(adj_limit, stride);
+          } else {
+            old_limit = limit;
+            adj_limit = new (C, 3) SubINode(limit, stride);
+          }
+          assert(old_limit != NULL && adj_limit != NULL, "");
+          register_new_node( adj_limit, ctrl ); // adjust amount
+          Node* adj_cmp = new (C, 3) CmpINode(old_limit, adj_limit);
+          register_new_node( adj_cmp, ctrl );
+          Node* adj_bool = new (C, 2) BoolNode(adj_cmp, bt);
+          register_new_node( adj_bool, ctrl );
+          new_limit = new (C, 4) CMoveINode(adj_bool, adj_limit, adj_max, TypeInt::INT);
+        }
+        register_new_node(new_limit, ctrl);
+      }
+      assert(new_limit != NULL, "");
+      if (limit->outcnt() == 2) {
+        // Replace old limit if it is used only in loop tests.
+        _igvn.replace_node(limit, new_limit);
+      } else {
+        // Replace in loop test.
+        _igvn.hash_delete(cmp);
+        cmp->set_req(2, new_limit);
+
+        // Step 3: Find the min-trip test guaranteed before a 'main' loop.
+        // Make it a 1-trip test (means at least 2 trips).
+
+        // Guard test uses an 'opaque' node which is not shared.  Hence I
+        // can edit it's inputs directly.  Hammer in the new limit for the
+        // minimum-trip guard.
+        assert(opaq->outcnt() == 1, "");
+        _igvn.hash_delete(opaq);
+        opaq->set_req(1, new_limit);
+      }
+    }
+
+    // Adjust max trip count. The trip count is intentionally rounded
+    // down here (e.g. 15-> 7-> 3-> 1) because if we unwittingly over-unroll,
+    // the main, unrolled, part of the loop will never execute as it is protected
+    // by the min-trip test.  See bug 4834191 for a case where we over-unrolled
+    // and later determined that part of the unrolled loop was dead.
+    loop_head->set_trip_count(old_trip_count / 2);
+
+    // Double the count of original iterations in the unrolled loop body.
+    loop_head->double_unrolled_count();
+
+  } else { // LoopLimitCheck
+
+    // Adjust max trip count. The trip count is intentionally rounded
+    // down here (e.g. 15-> 7-> 3-> 1) because if we unwittingly over-unroll,
+    // the main, unrolled, part of the loop will never execute as it is protected
+    // by the min-trip test.  See bug 4834191 for a case where we over-unrolled
+    // and later determined that part of the unrolled loop was dead.
+    loop_head->set_trip_count(loop_head->trip_count() / 2);
+
+    // Double the count of original iterations in the unrolled loop body.
+    loop_head->double_unrolled_count();
+
+    // -----------
+    // Step 2: Cut back the trip counter for an unroll amount of 2.
+    // Loop will normally trip (limit - init)/stride_con.  Since it's a
+    // CountedLoop this is exact (stride divides limit-init exactly).
+    // We are going to double the loop body, so we want to knock off any
+    // odd iteration: (trip_cnt & ~1).  Then back compute a new limit.
+    Node *span = new (C, 3) SubINode( limit, init );
+    register_new_node( span, ctrl );
+    Node *trip = new (C, 3) DivINode( 0, span, stride );
+    register_new_node( trip, ctrl );
+    Node *mtwo = _igvn.intcon(-2);
+    set_ctrl(mtwo, C->root());
+    Node *rond = new (C, 3) AndINode( trip, mtwo );
+    register_new_node( rond, ctrl );
+    Node *spn2 = new (C, 3) MulINode( rond, stride );
+    register_new_node( spn2, ctrl );
+    new_limit = new (C, 3) AddINode( spn2, init );
+    register_new_node( new_limit, ctrl );
+
+    // Hammer in the new limit
+    Node *ctrl2 = loop_end->in(0);
+    Node *cmp2 = new (C, 3) CmpINode( loop_head->incr(), new_limit );
+    register_new_node( cmp2, ctrl2 );
+    Node *bol2 = new (C, 2) BoolNode( cmp2, loop_end->test_trip() );
+    register_new_node( bol2, ctrl2 );
+    _igvn.hash_delete(loop_end);
+    loop_end->set_req(CountedLoopEndNode::TestValue, bol2);
+
+    // Step 3: Find the min-trip test guaranteed before a 'main' loop.
+    // Make it a 1-trip test (means at least 2 trips).
+    if( adjust_min_trip ) {
+      assert( new_limit != NULL, "" );
+      // Guard test uses an 'opaque' node which is not shared.  Hence I
+      // can edit it's inputs directly.  Hammer in the new limit for the
+      // minimum-trip guard.
+      assert( opaq->outcnt() == 1, "" );
+      _igvn.hash_delete(opaq);
+      opaq->set_req(1, new_limit);
+    }
+  } // LoopLimitCheck
 
   // ---------
   // Step 4: Clone the loop body.  Move it inside the loop.  This loop body
@@ -1266,6 +1415,7 @@
 
 void PhaseIdealLoop::do_maximally_unroll( IdealLoopTree *loop, Node_List &old_new ) {
   CountedLoopNode *cl = loop->_head->as_CountedLoop();
+  assert(cl->has_exact_trip_count(), "trip count is not exact");
   assert(cl->trip_count() > 0, "");
 #ifndef PRODUCT
   if (TraceLoopOpts) {
@@ -1282,6 +1432,7 @@
   // Now its tripping an even number of times remaining.  Double loop body.
   // Do not adjust pre-guards; they are not needed and do not exist.
   if (cl->trip_count() > 0) {
+    assert((cl->trip_count() & 1) == 0, "missed peeling");
     do_unroll(loop, old_new, false);
   }
 }
@@ -1295,22 +1446,13 @@
 }
 
 //------------------------------add_constraint---------------------------------
-// Constrain the main loop iterations so the condition:
-//    scale_con * I + offset  <  limit
+// Constrain the main loop iterations so the conditions:
+//    low_limit <= scale_con * I + offset  <  upper_limit
 // always holds true.  That is, either increase the number of iterations in
 // the pre-loop or the post-loop until the condition holds true in the main
 // loop.  Stride, scale, offset and limit are all loop invariant.  Further,
 // stride and scale are constants (offset and limit often are).
-void PhaseIdealLoop::add_constraint( int stride_con, int scale_con, Node *offset, Node *limit, Node *pre_ctrl, Node **pre_limit, Node **main_limit ) {
-
-  // Compute "I :: (limit-offset)/scale_con"
-  Node *con = new (C, 3) SubINode( limit, offset );
-  register_new_node( con, pre_ctrl );
-  Node *scale = _igvn.intcon(scale_con);
-  set_ctrl(scale, C->root());
-  Node *X = new (C, 3) DivINode( 0, con, scale );
-  register_new_node( X, pre_ctrl );
-
+void PhaseIdealLoop::add_constraint( int stride_con, int scale_con, Node *offset, Node *low_limit, Node *upper_limit, Node *pre_ctrl, Node **pre_limit, Node **main_limit ) {
   // For positive stride, the pre-loop limit always uses a MAX function
   // and the main loop a MIN function.  For negative stride these are
   // reversed.
@@ -1319,48 +1461,143 @@
   // pre-loop must check for underflow and the post-loop for overflow.
   // Negative stride*scale reverses this; pre-loop checks for overflow and
   // post-loop for underflow.
-  if( stride_con*scale_con > 0 ) {
-    // Compute I < (limit-offset)/scale_con
-    // Adjust main-loop last iteration to be MIN/MAX(main_loop,X)
-    *main_limit = (stride_con > 0)
-      ? (Node*)(new (C, 3) MinINode( *main_limit, X ))
-      : (Node*)(new (C, 3) MaxINode( *main_limit, X ));
-    register_new_node( *main_limit, pre_ctrl );
+  if (stride_con*scale_con > 0) {
+    // The overflow limit: scale*I+offset < upper_limit
+    // For main-loop compute
+    //   ( if (scale > 0) /* and stride > 0 */
+    //       I < (upper_limit-offset)/scale
+    //     else /* scale < 0 and stride < 0 */
+    //       I > (upper_limit-offset)/scale
+    //   )
+    //
+    // (upper_limit-offset) may overflow when offset < 0.
+    // But it is fine since main loop will either have
+    // less iterations or will be skipped in such case.
+    Node *con = new (C, 3) SubINode(upper_limit, offset);
+    register_new_node(con, pre_ctrl);
+    Node *scale = _igvn.intcon(scale_con);
+    set_ctrl(scale, C->root());
+    Node *X = new (C, 3) DivINode(0, con, scale);
+    register_new_node(X, pre_ctrl);
 
-  } else {
-    // Compute (limit-offset)/scale_con + SGN(-scale_con) <= I
-    // Add the negation of the main-loop constraint to the pre-loop.
-    // See footnote [++] below for a derivation of the limit expression.
-    Node *incr = _igvn.intcon(scale_con > 0 ? -1 : 1);
-    set_ctrl(incr, C->root());
-    Node *adj = new (C, 3) AddINode( X, incr );
-    register_new_node( adj, pre_ctrl );
-    *pre_limit = (scale_con > 0)
-      ? (Node*)new (C, 3) MinINode( *pre_limit, adj )
-      : (Node*)new (C, 3) MaxINode( *pre_limit, adj );
-    register_new_node( *pre_limit, pre_ctrl );
+    // Adjust main-loop last iteration
+    Node *loop_limit = *main_limit;
+    loop_limit = (stride_con > 0) // scale > 0
+      ? (Node*)(new (C, 3) MinINode(loop_limit, X))
+      : (Node*)(new (C, 3) MaxINode(loop_limit, X));
+    register_new_node(loop_limit, pre_ctrl);
+    *main_limit = loop_limit;
 
-//   [++] Here's the algebra that justifies the pre-loop limit expression:
-//
-//   NOT( scale_con * I + offset  <  limit )
-//      ==
-//   scale_con * I + offset  >=  limit
-//      ==
-//   SGN(scale_con) * I  >=  (limit-offset)/|scale_con|
-//      ==
-//   (limit-offset)/|scale_con|   <=  I * SGN(scale_con)
-//      ==
-//   (limit-offset)/|scale_con|-1  <  I * SGN(scale_con)
-//      ==
-//   ( if (scale_con > 0) /*common case*/
-//       (limit-offset)/scale_con - 1  <  I
-//     else
-//       (limit-offset)/scale_con + 1  >  I
-//    )
-//   ( if (scale_con > 0) /*common case*/
-//       (limit-offset)/scale_con + SGN(-scale_con)  <  I
-//     else
-//       (limit-offset)/scale_con + SGN(-scale_con)  >  I
+    // The underflow limit: low_limit <= scale*I+offset.
+    // For pre-loop compute
+    //   NOT(scale*I+offset >= low_limit)
+    //   scale*I+offset < low_limit
+    //   ( if (scale > 0) /* and stride > 0 */
+    //       I < (low_limit-offset)/scale
+    //     else /* scale < 0 and stride < 0 */
+    //       I > (low_limit-offset)/scale
+    //   )
+
+    if (low_limit->get_int() == -max_jint) {
+      if (!RangeLimitCheck) return;
+      // We need this guard when scale*pre_limit+offset >= limit
+      // due to underflow so we need execute pre-loop until
+      // scale*I+offset >= min_int. But (low_limit-offset) will
+      // underflow when offset > 0 and X will be > original_limit.
+      // To avoid it we replace offset = offset > 0 ? 0 : offset
+      // and add min(pre_limit, original_limit).
+      Node* shift = _igvn.intcon(31);
+      set_ctrl(shift, C->root());
+      Node *neg_off = new (C, 3) RShiftINode(offset, shift);
+      register_new_node(neg_off, pre_ctrl);
+      offset = new (C, 3) AndINode(offset, neg_off);
+      register_new_node(offset, pre_ctrl);
+    } else {
+      assert(low_limit->get_int() == 0, "wrong low limit for range check");
+      // The only problem we have here when offset == min_int
+      // since (0-min_int) == min_int. It may be fine for scale > 0
+      // but for scale < 0 X will be < original_limit.
+    }
+    con = new (C, 3) SubINode(low_limit, offset);
+    register_new_node(con, pre_ctrl);
+    scale = _igvn.intcon(scale_con);
+    set_ctrl(scale, C->root());
+    X = new (C, 3) DivINode(0, con, scale);
+    register_new_node(X, pre_ctrl);
+
+    // Adjust pre-loop last iteration
+    loop_limit = *pre_limit;
+    loop_limit = (stride_con > 0) // scale > 0
+      ? (Node*)(new (C, 3) MaxINode(loop_limit, X))
+      : (Node*)(new (C, 3) MinINode(loop_limit, X));
+    register_new_node( loop_limit, pre_ctrl );
+    *pre_limit = loop_limit;
+
+  } else { // stride_con*scale_con < 0
+    // For negative stride*scale pre-loop checks for overflow and
+    // post-loop for underflow.
+    //
+    // The underflow limit: low_limit <= scale*I+offset.
+    // For main-loop compute
+    //   scale*I+offset+1 > low_limit
+    //   ( if (scale < 0) /* and stride > 0 */
+    //       I < (low_limit-(offset+1))/scale
+    //     else /* scale < 0 and stride < 0 */
+    //       I > (low_limit-(offset+1))/scale
+    //   )
+
+    if (low_limit->get_int() == -max_jint) {
+      if (!RangeLimitCheck) return;
+    } else {
+      assert(low_limit->get_int() == 0, "wrong low limit for range check");
+    }
+
+    Node *one  = _igvn.intcon(1);
+    set_ctrl(one, C->root());
+    Node *plus_one = new (C, 3) AddINode(offset, one);
+    register_new_node( plus_one, pre_ctrl );
+    Node *con = new (C, 3) SubINode(low_limit, plus_one);
+    register_new_node(con, pre_ctrl);
+    Node *scale = _igvn.intcon(scale_con);
+    set_ctrl(scale, C->root());
+    Node *X = new (C, 3) DivINode(0, con, scale);
+    register_new_node(X, pre_ctrl);
+
+    // Adjust main-loop last iteration
+    Node *loop_limit = *main_limit;
+    loop_limit = (stride_con > 0) // scale < 0
+      ? (Node*)(new (C, 3) MinINode(loop_limit, X))
+      : (Node*)(new (C, 3) MaxINode(loop_limit, X));
+    register_new_node(loop_limit, pre_ctrl);
+    *main_limit = loop_limit;
+
+    // The overflow limit: scale*I+offset < upper_limit
+    // For pre-loop compute
+    //   NOT(scale*I+offset < upper_limit)
+    //   scale*I+offset >= upper_limit
+    //   scale*I+offset+1 > upper_limit
+    //   ( if (scale < 0) /* and stride > 0 */
+    //       I < (upper_limit-(offset+1))/scale
+    //     else /* scale < 0 and stride < 0 */
+    //       I > (upper_limit-(offset+1))/scale
+    //   )
+    plus_one = new (C, 3) AddINode(offset, one);
+    register_new_node( plus_one, pre_ctrl );
+    con = new (C, 3) SubINode(upper_limit, plus_one);
+    register_new_node(con, pre_ctrl);
+    scale = _igvn.intcon(scale_con);
+    set_ctrl(scale, C->root());
+    X = new (C, 3) DivINode(0, con, scale);
+    register_new_node(X, pre_ctrl);
+
+    // Adjust pre-loop last iteration
+    loop_limit = *pre_limit;
+    loop_limit = (stride_con > 0) // scale < 0
+      ? (Node*)(new (C, 3) MaxINode(loop_limit, X))
+      : (Node*)(new (C, 3) MinINode(loop_limit, X));
+    register_new_node( loop_limit, pre_ctrl );
+    *pre_limit = loop_limit;
+
   }
 }
 
@@ -1491,7 +1728,7 @@
   Node *cmpzm = bolzm->in(1);
   assert(cmpzm->is_Cmp(), "");
   Node *opqzm = cmpzm->in(2);
-  // Can not optimize a loop if pre-loop Opaque1 node is optimized
+  // Can not optimize a loop if zero-trip Opaque1 node is optimized
   // away and then another round of loop opts attempted.
   if (opqzm->Opcode() != Op_Opaque1)
     return;
@@ -1526,8 +1763,11 @@
   int stride_con = cl->stride_con();
   Node *zero = _igvn.intcon(0);
   Node *one  = _igvn.intcon(1);
+  // Use symmetrical int range [-max_jint,max_jint]
+  Node *mini = _igvn.intcon(-max_jint);
   set_ctrl(zero, C->root());
   set_ctrl(one,  C->root());
+  set_ctrl(mini, C->root());
 
   // Range checks that do not dominate the loop backedge (ie.
   // conditionally executed) can lengthen the pre loop limit beyond
@@ -1602,7 +1842,12 @@
       if( offset_c == ctrl ) {
         continue; // Don't rce this check but continue looking for other candidates.
       }
-
+#ifdef ASSERT
+      if (TraceRangeLimitCheck) {
+        tty->print_cr("RC bool node%s", flip ? " flipped:" : ":");
+        bol->dump(2);
+      }
+#endif
       // At this point we have the expression as:
       //   scale_con * trip_counter + offset :: limit
       // where scale_con, offset and limit are loop invariant.  Trip_counter
@@ -1613,17 +1858,16 @@
       // Adjust pre and main loop limits to guard the correct iteration set
       if( cmp->Opcode() == Op_CmpU ) {// Unsigned compare is really 2 tests
         if( b_test._test == BoolTest::lt ) { // Range checks always use lt
-          // The overflow limit: scale*I+offset < limit
-          add_constraint( stride_con, scale_con, offset, limit, pre_ctrl, &pre_limit, &main_limit );
-          // The underflow limit: 0 <= scale*I+offset.
-          // Some math yields: -scale*I-(offset+1) < 0
-          Node *plus_one = new (C, 3) AddINode( offset, one );
-          register_new_node( plus_one, pre_ctrl );
-          Node *neg_offset = new (C, 3) SubINode( zero, plus_one );
-          register_new_node( neg_offset, pre_ctrl );
-          add_constraint( stride_con, -scale_con, neg_offset, zero, pre_ctrl, &pre_limit, &main_limit );
+          // The underflow and overflow limits: 0 <= scale*I+offset < limit
+          add_constraint( stride_con, scale_con, offset, zero, limit, pre_ctrl, &pre_limit, &main_limit );
           if (!conditional_rc) {
             conditional_rc = !loop->dominates_backedge(iff);
+            // It is also needed if offset->_lo == min_int since
+            // (0-min_int) == min_int. It may be fine for stride > 0
+            // but for stride < 0 pre_limit will be < original_limit.
+            const TypeInt* offset_t = _igvn.type(offset)->is_int();
+            conditional_rc |= RangeLimitCheck && (offset_t->_lo == min_jint) &&
+                              (scale_con<0) && (stride_con<0);
           }
         } else {
 #ifndef PRODUCT
@@ -1634,21 +1878,35 @@
         }
       } else {                  // Otherwise work on normal compares
         switch( b_test._test ) {
-        case BoolTest::ge:      // Convert X >= Y to -X <= -Y
+        case BoolTest::gt:
+          // Fall into GE case
+        case BoolTest::ge:
+          // Convert (I*scale+offset) >= Limit to (I*(-scale)+(-offset)) <= -Limit
           scale_con = -scale_con;
           offset = new (C, 3) SubINode( zero, offset );
           register_new_node( offset, pre_ctrl );
           limit  = new (C, 3) SubINode( zero, limit  );
           register_new_node( limit, pre_ctrl );
           // Fall into LE case
-        case BoolTest::le:      // Convert X <= Y to X < Y+1
-          limit = new (C, 3) AddINode( limit, one );
-          register_new_node( limit, pre_ctrl );
+        case BoolTest::le:
+          if (b_test._test != BoolTest::gt) {
+            // Convert X <= Y to X < Y+1
+            limit = new (C, 3) AddINode( limit, one );
+            register_new_node( limit, pre_ctrl );
+          }
           // Fall into LT case
         case BoolTest::lt:
-          add_constraint( stride_con, scale_con, offset, limit, pre_ctrl, &pre_limit, &main_limit );
+          // The underflow and overflow limits: MIN_INT <= scale*I+offset < limit
+          add_constraint( stride_con, scale_con, offset, mini, limit, pre_ctrl, &pre_limit, &main_limit );
           if (!conditional_rc) {
             conditional_rc = !loop->dominates_backedge(iff);
+            // It is also needed if scale*pre_limit+offset >= limit
+            // due to underflow so we need execute pre-loop until
+            // scale*I+offset >= min_int. But (low_limit-offset) will
+            // underflow when offset > 0 and X will be > original_limit.
+            const TypeInt* offset_t = _igvn.type(offset)->is_int();
+            conditional_rc |= RangeLimitCheck && (offset_t->_hi > 0) &&
+                              (scale_con>0) && (stride_con>0);
           }
           break;
         default:
@@ -1699,7 +1957,8 @@
 
   // Note:: we are making the main loop limit no longer precise;
   // need to round up based on stride.
-  if( stride_con != 1 && stride_con != -1 ) { // Cutout for common case
+  cl->set_nonexact_trip_count();
+  if (!LoopLimitCheck && stride_con != 1 && stride_con != -1) { // Cutout for common case
     // "Standard" round-up logic:  ([main_limit-init+(y-1)]/y)*y+init
     // Hopefully, compiler will optimize for powers of 2.
     Node *ctrl = get_ctrl(main_limit);
@@ -1879,7 +2138,19 @@
   // iteration.  Then the CountedLoopEnd will collapse (backedge never
   // taken) and all loop-invariant uses of the exit values will be correct.
   Node *phi = cl->phi();
-  Node *final = new (phase->C, 3) SubINode( cl->limit(), cl->stride() );
+  Node *exact_limit = phase->exact_limit(this);
+  if (exact_limit != cl->limit()) {
+    // We also need to replace the original limit to collapse loop exit.
+    Node* cmp = cl->loopexit()->cmp_node();
+    assert(cl->limit() == cmp->in(2), "sanity");
+    phase->_igvn._worklist.push(cmp->in(2)); // put limit on worklist
+    phase->_igvn.hash_delete(cmp);
+    cmp->set_req(2, exact_limit);
+    phase->_igvn._worklist.push(cmp);        // put cmp on worklist
+  }
+  // Note: the final value after increment should not overflow since
+  // counted loop has limit check predicate.
+  Node *final = new (phase->C, 3) SubINode( exact_limit, cl->stride() );
   phase->register_new_node(final,cl->in(LoopNode::EntryControl));
   phase->_igvn.replace_node(phi,final);
   phase->C->set_major_progress();
--- a/src/share/vm/opto/loopUnswitch.cpp	Wed May 04 03:42:58 2011 -0700
+++ b/src/share/vm/opto/loopUnswitch.cpp	Wed May 04 13:12:42 2011 -0700
@@ -130,6 +130,11 @@
   Node* uniqc = proj_true->unique_ctrl_out();
   Node* entry = head->in(LoopNode::EntryControl);
   Node* predicate = find_predicate(entry);
+  if (predicate != NULL && LoopLimitCheck && UseLoopPredicate) {
+    // We may have two predicates, find first.
+    entry = find_predicate(entry->in(0)->in(0));
+    if (entry != NULL) predicate = entry;
+  }
   if (predicate != NULL) predicate = predicate->in(0);
   assert(proj_true->is_IfTrue() &&
          (predicate == NULL && uniqc == head ||
@@ -217,6 +222,7 @@
 ProjNode* PhaseIdealLoop::create_slow_version_of_loop(IdealLoopTree *loop,
                                                       Node_List &old_new) {
   LoopNode* head  = loop->_head->as_Loop();
+  bool counted_loop = head->is_CountedLoop();
   Node*     entry = head->in(LoopNode::EntryControl);
   _igvn.hash_delete(entry);
   _igvn._worklist.push(entry);
@@ -242,14 +248,14 @@
   assert(old_new[head->_idx]->is_Loop(), "" );
 
   // Fast (true) control
-  Node* iffast_pred = clone_loop_predicates(entry, iffast);
+  Node* iffast_pred = clone_loop_predicates(entry, iffast, !counted_loop);
   _igvn.hash_delete(head);
   head->set_req(LoopNode::EntryControl, iffast_pred);
   set_idom(head, iffast_pred, dom_depth(head));
   _igvn._worklist.push(head);
 
   // Slow (false) control
-  Node* ifslow_pred = move_loop_predicates(entry, ifslow);
+  Node* ifslow_pred = move_loop_predicates(entry, ifslow, !counted_loop);
   LoopNode* slow_head = old_new[head->_idx]->as_Loop();
   _igvn.hash_delete(slow_head);
   slow_head->set_req(LoopNode::EntryControl, ifslow_pred);
--- a/src/share/vm/opto/loopnode.cpp	Wed May 04 03:42:58 2011 -0700
+++ b/src/share/vm/opto/loopnode.cpp	Wed May 04 13:12:42 2011 -0700
@@ -206,7 +206,7 @@
   // Get backedge compare
   Node *cmp = test->in(1);
   int cmp_op = cmp->Opcode();
-  if( cmp_op != Op_CmpI )
+  if (cmp_op != Op_CmpI)
     return false;                // Avoid pointer & float compares
 
   // Find the trip-counter increment & limit.  Limit must be loop invariant.
@@ -259,7 +259,8 @@
   }
   // Stride must be constant
   int stride_con = stride->get_int();
-  assert(stride_con != 0, "missed some peephole opt");
+  if (stride_con == 0)
+    return false; // missed some peephole opt
 
   if (!xphi->is_Phi())
     return false; // Too much math on the trip counter
@@ -319,7 +320,7 @@
       // Count down loop rolls through MAXINT
       (bt == BoolTest::le || bt == BoolTest::lt) && stride_con < 0 ||
       // Count up loop rolls through MININT
-      (bt == BoolTest::ge || bt == BoolTest::gt) && stride_con > 0 ) {
+      (bt == BoolTest::ge || bt == BoolTest::gt) && stride_con > 0) {
     return false; // Bail out
   }
 
@@ -341,12 +342,137 @@
   //
   assert(x->Opcode() == Op_Loop, "regular loops only");
   C->print_method("Before CountedLoop", 3);
+
+  Node *hook = new (C, 6) Node(6);
+
+  if (LoopLimitCheck) {
+
+  // ===================================================
+  // Generate loop limit check to avoid integer overflow
+  // in cases like next (cyclic loops):
+  //
+  // for (i=0; i <= max_jint; i++) {}
+  // for (i=0; i <  max_jint; i+=2) {}
+  //
+  //
+  // Limit check predicate depends on the loop test:
+  //
+  // for(;i != limit; i++)       --> limit <= (max_jint)
+  // for(;i <  limit; i+=stride) --> limit <= (max_jint - stride + 1)
+  // for(;i <= limit; i+=stride) --> limit <= (max_jint - stride    )
+  //
+
+  // Check if limit is excluded to do more precise int overflow check.
+  bool incl_limit = (bt == BoolTest::le || bt == BoolTest::ge);
+  int stride_m  = stride_con - (incl_limit ? 0 : (stride_con > 0 ? 1 : -1));
+
+  // If compare points directly to the phi we need to adjust
+  // the compare so that it points to the incr. Limit have
+  // to be adjusted to keep trip count the same and the
+  // adjusted limit should be checked for int overflow.
+  if (phi_incr != NULL) {
+    stride_m  += stride_con;
+  }
+
+  if (limit->is_Con()) {
+    int limit_con = limit->get_int();
+    if ((stride_con > 0 && limit_con > (max_jint - stride_m)) ||
+        (stride_con < 0 && limit_con < (min_jint - stride_m))) {
+      // Bailout: it could be integer overflow.
+      return false;
+    }
+  } else if ((stride_con > 0 && limit_t->_hi <= (max_jint - stride_m)) ||
+             (stride_con < 0 && limit_t->_lo >= (min_jint - stride_m))) {
+      // Limit's type may satisfy the condition, for example,
+      // when it is an array length.
+  } else {
+    // Generate loop's limit check.
+    // Loop limit check predicate should be near the loop.
+    ProjNode *limit_check_proj = find_predicate_insertion_point(init_control, Deoptimization::Reason_loop_limit_check);
+    if (!limit_check_proj) {
+      // The limit check predicate is not generated if this method trapped here before.
+#ifdef ASSERT
+      if (TraceLoopLimitCheck) {
+        tty->print("missing loop limit check:");
+        loop->dump_head();
+        x->dump(1);
+      }
+#endif
+      return false;
+    }
+
+    IfNode* check_iff = limit_check_proj->in(0)->as_If();
+    Node* cmp_limit;
+    Node* bol;
+
+    if (stride_con > 0) {
+      cmp_limit = new (C, 3) CmpINode(limit, _igvn.intcon(max_jint - stride_m));
+      bol = new (C, 2) BoolNode(cmp_limit, BoolTest::le);
+    } else {
+      cmp_limit = new (C, 3) CmpINode(limit, _igvn.intcon(min_jint - stride_m));
+      bol = new (C, 2) BoolNode(cmp_limit, BoolTest::ge);
+    }
+    cmp_limit = _igvn.register_new_node_with_optimizer(cmp_limit);
+    bol = _igvn.register_new_node_with_optimizer(bol);
+    set_subtree_ctrl(bol);
+
+    // Replace condition in original predicate but preserve Opaque node
+    // so that previous predicates could be found.
+    assert(check_iff->in(1)->Opcode() == Op_Conv2B &&
+           check_iff->in(1)->in(1)->Opcode() == Op_Opaque1, "");
+    Node* opq = check_iff->in(1)->in(1);
+    _igvn.hash_delete(opq);
+    opq->set_req(1, bol);
+    // Update ctrl.
+    set_ctrl(opq, check_iff->in(0));
+    set_ctrl(check_iff->in(1), check_iff->in(0));
+
 #ifndef PRODUCT
-  if (TraceLoopOpts) {
-    tty->print("Counted      ");
-    loop->dump_head();
+    // report that the loop predication has been actually performed
+    // for this loop
+    if (TraceLoopLimitCheck) {
+      tty->print_cr("Counted Loop Limit Check generated:");
+      debug_only( bol->dump(2); )
+    }
+#endif
   }
-#endif
+
+  if (phi_incr != NULL) {
+    // If compare points directly to the phi we need to adjust
+    // the compare so that it points to the incr. Limit have
+    // to be adjusted to keep trip count the same and we
+    // should avoid int overflow.
+    //
+    //   i = init; do {} while(i++ < limit);
+    // is converted to
+    //   i = init; do {} while(++i < limit+1);
+    //
+    limit = gvn->transform(new (C, 3) AddINode(limit, stride));
+  }
+
+  // Now we need to canonicalize loop condition.
+  if (bt == BoolTest::ne) {
+    assert(stride_con == 1 || stride_con == -1, "simple increment only");
+    bt = (stride_con > 0) ? BoolTest::lt : BoolTest::gt;
+  }
+
+  if (incl_limit) {
+    // The limit check guaranties that 'limit <= (max_jint - stride)' so
+    // we can convert 'i <= limit' to 'i < limit+1' since stride != 0.
+    //
+    Node* one = (stride_con > 0) ? gvn->intcon( 1) : gvn->intcon(-1);
+    limit = gvn->transform(new (C, 3) AddINode(limit, one));
+    if (bt == BoolTest::le)
+      bt = BoolTest::lt;
+    else if (bt == BoolTest::ge)
+      bt = BoolTest::gt;
+    else
+      ShouldNotReachHere();
+  }
+  set_subtree_ctrl( limit );
+
+  } else { // LoopLimitCheck
+
   // If compare points to incr, we are ok.  Otherwise the compare
   // can directly point to the phi; in this case adjust the compare so that
   // it points to the incr by adjusting the limit.
@@ -359,7 +485,6 @@
   Node *one_m = gvn->intcon(-1);
 
   Node *trip_count = NULL;
-  Node *hook = new (C, 6) Node(6);
   switch( bt ) {
   case BoolTest::eq:
     ShouldNotReachHere();
@@ -441,6 +566,8 @@
   limit = gvn->transform(new (C, 3) AddINode(span,init_trip));
   set_subtree_ctrl( limit );
 
+  } // LoopLimitCheck
+
   // Check for SafePoint on backedge and remove
   Node *sfpt = x->in(LoopNode::LoopBackControl);
   if (sfpt->Opcode() == Op_SafePoint && is_deleteable_safept(sfpt)) {
@@ -531,7 +658,7 @@
 
   // Check for immediately preceding SafePoint and remove
   Node *sfpt2 = le->in(0);
-  if( sfpt2->Opcode() == Op_SafePoint && is_deleteable_safept(sfpt2))
+  if (sfpt2->Opcode() == Op_SafePoint && is_deleteable_safept(sfpt2))
     lazy_replace( sfpt2, sfpt2->in(TypeFunc::Control));
 
   // Free up intermediate goo
@@ -541,12 +668,56 @@
   assert(l->is_valid_counted_loop(), "counted loop shape is messed up");
   assert(l == loop->_head && l->phi() == phi && l->loopexit() == lex, "" );
 #endif
+#ifndef PRODUCT
+  if (TraceLoopOpts) {
+    tty->print("Counted      ");
+    loop->dump_head();
+  }
+#endif
 
   C->print_method("After CountedLoop", 3);
 
   return true;
 }
 
+//----------------------exact_limit-------------------------------------------
+Node* PhaseIdealLoop::exact_limit( IdealLoopTree *loop ) {
+  assert(loop->_head->is_CountedLoop(), "");
+  CountedLoopNode *cl = loop->_head->as_CountedLoop();
+
+  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.
+    return cl->limit();
+  }
+  Node *limit = NULL;
+#ifdef ASSERT
+  BoolTest::mask bt = cl->loopexit()->test_trip();
+  assert(bt == BoolTest::lt || bt == BoolTest::gt, "canonical test is expected");
+#endif
+  if (cl->has_exact_trip_count()) {
+    // Simple case: loop has constant boundaries.
+    // Use longs to avoid integer overflow.
+    int stride_con = cl->stride_con();
+    long  init_con = cl->init_trip()->get_int();
+    long limit_con = cl->limit()->get_int();
+    julong trip_cnt = cl->trip_count();
+    long final_con = init_con + trip_cnt*stride_con;
+    final_con -= stride_con;
+    int final_int = (int)final_con;
+    // The final value should be in integer range since the loop
+    // is counted and the limit was checked for overflow.
+    assert(final_con == (long)final_int, "final value should be integer");
+    limit = _igvn.intcon(final_int);
+  } else {
+    // Create new LoopLimit node to get exact limit (final iv value).
+    limit = new (C, 4) LoopLimitNode(C, cl->init_trip(), cl->limit(), cl->stride());
+    register_new_node(limit, cl->in(LoopNode::EntryControl));
+  }
+  assert(limit != NULL, "sanity");
+  return limit;
+}
 
 //------------------------------Ideal------------------------------------------
 // Return a node which is more "ideal" than the current node.
@@ -572,14 +743,12 @@
 #ifndef PRODUCT
 void CountedLoopNode::dump_spec(outputStream *st) const {
   LoopNode::dump_spec(st);
-  if( stride_is_con() ) {
+  if (stride_is_con()) {
     st->print("stride: %d ",stride_con());
-  } else {
-    st->print("stride: not constant ");
   }
-  if( is_pre_loop () ) st->print("pre of N%d" , _main_idx );
-  if( is_main_loop() ) st->print("main of N%d", _idx );
-  if( is_post_loop() ) st->print("post of N%d", _main_idx );
+  if (is_pre_loop ()) st->print("pre of N%d" , _main_idx);
+  if (is_main_loop()) st->print("main of N%d", _idx);
+  if (is_post_loop()) st->print("post of N%d", _main_idx);
 }
 #endif
 
@@ -588,7 +757,130 @@
   return stride()->bottom_type()->is_int()->get_con();
 }
 
-
+//=============================================================================
+//------------------------------Value-----------------------------------------
+const Type *LoopLimitNode::Value( PhaseTransform *phase ) const {
+  const Type* init_t   = phase->type(in(Init));
+  const Type* limit_t  = phase->type(in(Limit));
+  const Type* stride_t = phase->type(in(Stride));
+  // Either input is TOP ==> the result is TOP
+  if (init_t   == Type::TOP) return Type::TOP;
+  if (limit_t  == Type::TOP) return Type::TOP;
+  if (stride_t == Type::TOP) return Type::TOP;
+
+  int stride_con = stride_t->is_int()->get_con();
+  if (stride_con == 1)
+    return NULL;  // Identity
+
+  if (init_t->is_int()->is_con() && limit_t->is_int()->is_con()) {
+    // Use longs to avoid integer overflow.
+    long init_con   =  init_t->is_int()->get_con();
+    long limit_con  = limit_t->is_int()->get_con();
+    int  stride_m   = stride_con - (stride_con > 0 ? 1 : -1);
+    long trip_count = (limit_con - init_con + stride_m)/stride_con;
+    long final_con  = init_con + stride_con*trip_count;
+    int final_int = (int)final_con;
+    // The final value should be in integer range since the loop
+    // is counted and the limit was checked for overflow.
+    assert(final_con == (long)final_int, "final value should be integer");
+    return TypeInt::make(final_int);
+  }
+
+  return bottom_type(); // TypeInt::INT
+}
+
+//------------------------------Ideal------------------------------------------
+// Return a node which is more "ideal" than the current node.
+Node *LoopLimitNode::Ideal(PhaseGVN *phase, bool can_reshape) {
+  if (phase->type(in(Init))   == Type::TOP ||
+      phase->type(in(Limit))  == Type::TOP ||
+      phase->type(in(Stride)) == Type::TOP)
+    return NULL;  // Dead
+
+  int stride_con = phase->type(in(Stride))->is_int()->get_con();
+  if (stride_con == 1)
+    return NULL;  // Identity
+
+  if (in(Init)->is_Con() && in(Limit)->is_Con())
+    return NULL;  // Value
+
+  // Delay following optimizations until all loop optimizations
+  // done to keep Ideal graph simple.
+  if (!can_reshape || phase->C->major_progress())
+    return NULL;
+
+  const TypeInt* init_t  = phase->type(in(Init) )->is_int();
+  const TypeInt* limit_t = phase->type(in(Limit))->is_int();
+  int stride_p;
+  long lim, ini;
+  julong max;
+  if (stride_con > 0) {
+    stride_p = stride_con;
+    lim = limit_t->_hi;
+    ini = init_t->_lo;
+    max = (julong)max_jint;
+  } else {
+    stride_p = -stride_con;
+    lim = init_t->_hi;
+    ini = limit_t->_lo;
+    max = (julong)min_jint;
+  }
+  julong range = lim - ini + stride_p;
+  if (range <= max) {
+    // Convert to integer expression if it is not overflow.
+    Node* stride_m = phase->intcon(stride_con - (stride_con > 0 ? 1 : -1));
+    Node *range = phase->transform(new (phase->C, 3) SubINode(in(Limit), in(Init)));
+    Node *bias  = phase->transform(new (phase->C, 3) AddINode(range, stride_m));
+    Node *trip  = phase->transform(new (phase->C, 3) DivINode(0, bias, in(Stride)));
+    Node *span  = phase->transform(new (phase->C, 3) MulINode(trip, in(Stride)));
+    return new (phase->C, 3) AddINode(span, in(Init)); // exact limit
+  }
+
+  if (is_power_of_2(stride_p) ||                // divisor is 2^n
+      !Matcher::has_match_rule(Op_LoopLimit)) { // or no specialized Mach node?
+    // Convert to long expression to avoid integer overflow
+    // and let igvn optimizer convert this division.
+    //
+    Node*   init   = phase->transform( new (phase->C, 2) ConvI2LNode(in(Init)));
+    Node*  limit   = phase->transform( new (phase->C, 2) ConvI2LNode(in(Limit)));
+    Node* stride   = phase->longcon(stride_con);
+    Node* stride_m = phase->longcon(stride_con - (stride_con > 0 ? 1 : -1));
+
+    Node *range = phase->transform(new (phase->C, 3) SubLNode(limit, init));
+    Node *bias  = phase->transform(new (phase->C, 3) AddLNode(range, stride_m));
+    Node *span;
+    if (stride_con > 0 && is_power_of_2(stride_p)) {
+      // bias >= 0 if stride >0, so if stride is 2^n we can use &(-stride)
+      // and avoid generating rounding for division. Zero trip guard should
+      // guarantee that init < limit but sometimes the guard is missing and
+      // we can get situation when init > limit. Note, for the empty loop
+      // optimization zero trip guard is generated explicitly which leaves
+      // only RCE predicate where exact limit is used and the predicate
+      // will simply fail forcing recompilation.
+      Node* neg_stride   = phase->longcon(-stride_con);
+      span = phase->transform(new (phase->C, 3) AndLNode(bias, neg_stride));
+    } else {
+      Node *trip  = phase->transform(new (phase->C, 3) DivLNode(0, bias, stride));
+      span = phase->transform(new (phase->C, 3) MulLNode(trip, stride));
+    }
+    // Convert back to int
+    Node *span_int = phase->transform(new (phase->C, 2) ConvL2INode(span));
+    return new (phase->C, 3) AddINode(span_int, in(Init)); // exact limit
+  }
+
+  return NULL;    // No progress
+}
+
+//------------------------------Identity---------------------------------------
+// If stride == 1 return limit node.
+Node *LoopLimitNode::Identity( PhaseTransform *phase ) {
+  int stride_con = phase->type(in(Stride))->is_int()->get_con();
+  if (stride_con == 1 || stride_con == -1)
+    return in(Limit);
+  return this;
+}
+
+//=============================================================================
 //----------------------match_incr_with_optional_truncation--------------------
 // Match increment with optional truncation:
 // CHAR: (i+1)&0x7fff, BYTE: ((i+1)<<8)>>8, or SHORT: ((i+1)<<16)>>16
@@ -870,7 +1162,7 @@
   outer = igvn.register_new_node_with_optimizer(outer, _head);
   phase->set_created_loop_node();
 
-  Node* pred = phase->clone_loop_predicates(ctl, outer);
+  Node* pred = phase->clone_loop_predicates(ctl, outer, true);
   // Outermost loop falls into '_head' loop
   _head->set_req(LoopNode::EntryControl, pred);
   _head->del_req(outer_idx);
@@ -1440,9 +1732,16 @@
     tty->print("  ");
   tty->print("Loop: N%d/N%d ",_head->_idx,_tail->_idx);
   if (_irreducible) tty->print(" IRREDUCIBLE");
+  Node* entry = _head->in(LoopNode::EntryControl);
+  if (LoopLimitCheck) {
+    Node* predicate = PhaseIdealLoop::find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check);
+    if (predicate != NULL ) {
+      tty->print(" limit_check");
+      entry = entry->in(0)->in(0);
+    }
+  }
   if (UseLoopPredicate) {
-    Node* entry = PhaseIdealLoop::find_predicate_insertion_point(_head->in(LoopNode::EntryControl),
-                                                                 Deoptimization::Reason_predicate);
+    entry = PhaseIdealLoop::find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
     if (entry != NULL) {
       tty->print(" predicated");
     }
@@ -1528,10 +1827,15 @@
       !loop->tail()->is_top()) {
     LoopNode* lpn = loop->_head->as_Loop();
     Node* entry = lpn->in(LoopNode::EntryControl);
-    Node* predicate_proj = find_predicate(entry);
+    Node* predicate_proj = find_predicate(entry); // loop_limit_check first
     if (predicate_proj != NULL ) { // right pattern that can be used by loop predication
       assert(entry->in(0)->in(1)->in(1)->Opcode() == Op_Opaque1, "must be");
       useful_predicates.push(entry->in(0)->in(1)->in(1)); // good one
+      entry = entry->in(0)->in(0);
+    }
+    predicate_proj = find_predicate(entry); // Predicate
+    if (predicate_proj != NULL ) {
+      useful_predicates.push(entry->in(0)->in(1)->in(1)); // good one
     }
   }
 
@@ -1542,6 +1846,8 @@
 
 //------------------------eliminate_useless_predicates-----------------------------
 // Eliminate all inserted predicates if they could not be used by loop predication.
+// Note: it will also eliminates loop limits check predicate since it also uses
+// Opaque1 node (see Parse::add_predicate()).
 void PhaseIdealLoop::eliminate_useless_predicates() {
   if (C->predicate_count() == 0)
     return; // no predicate left
@@ -1731,7 +2037,7 @@
   // Some parser-inserted loop predicates could never be used by loop
   // predication or they were moved away from loop during some optimizations.
   // For example, peeling. Eliminate them before next loop optimizations.
-  if (UseLoopPredicate) {
+  if (UseLoopPredicate || LoopLimitCheck) {
     eliminate_useless_predicates();
   }
 
--- a/src/share/vm/opto/loopnode.hpp	Wed May 04 03:42:58 2011 -0700
+++ b/src/share/vm/opto/loopnode.hpp	Wed May 04 13:12:42 2011 -0700
@@ -289,6 +289,28 @@
 inline Node *CountedLoopNode::incr() const { return loopexit() ? loopexit()->incr() : NULL; }
 inline Node *CountedLoopNode::phi() const { return loopexit() ? loopexit()->phi() : NULL; }
 
+//------------------------------LoopLimitNode-----------------------------
+// Counted Loop limit node which represents exact final iterator value:
+// trip_count = (limit - init_trip + stride - 1)/stride
+// final_value= trip_count * stride + init_trip.
+// Use HW instructions to calculate it when it can overflow in integer.
+// Note, final_value should fit into integer since counted loop has
+// limit check: limit <= max_int-stride.
+class LoopLimitNode : public Node {
+  enum { Init=1, Limit=2, Stride=3 };
+ public:
+  LoopLimitNode( Compile* C, Node *init, Node *limit, Node *stride ) : Node(0,init,limit,stride) {
+    // Put it on the Macro nodes list to optimize during macro nodes expansion.
+    init_flags(Flag_is_macro);
+    C->add_macro_node(this);
+  }
+  virtual int Opcode() const;
+  virtual const Type *bottom_type() const { return TypeInt::INT; }
+  virtual uint ideal_reg() const { return Op_RegI; }
+  virtual const Type *Value( PhaseTransform *phase ) const;
+  virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
+  virtual Node *Identity( PhaseTransform *phase );
+};
 
 // -----------------------------IdealLoopTree----------------------------------
 class IdealLoopTree : public ResourceObj {
@@ -775,6 +797,8 @@
 
   bool is_counted_loop( Node *x, IdealLoopTree *loop );
 
+  Node* exact_limit( IdealLoopTree *loop );
+
   // Return a post-walked LoopNode
   IdealLoopTree *get_loop( Node *n ) const {
     // Dead nodes have no loop, so return the top level loop instead
@@ -837,7 +861,6 @@
   bool is_scaled_iv_plus_offset(Node* exp, Node* iv, int* p_scale, Node** p_offset, int depth = 0);
 
   // Return true if proj is for "proj->[region->..]call_uct"
-  // Return true if proj is for "proj->[region->..]call_uct"
   static bool is_uncommon_trap_proj(ProjNode* proj, Deoptimization::DeoptReason reason);
   // Return true for    "if(test)-> proj -> ...
   //                          |
@@ -860,10 +883,11 @@
                                    PhaseIterGVN* igvn);
   static Node* clone_loop_predicates(Node* old_entry, Node* new_entry,
                                          bool move_predicates,
+                                         bool clone_limit_check,
                                          PhaseIdealLoop* loop_phase,
                                          PhaseIterGVN* igvn);
-  Node* clone_loop_predicates(Node* old_entry, Node* new_entry);
-  Node*  move_loop_predicates(Node* old_entry, Node* new_entry);
+  Node* clone_loop_predicates(Node* old_entry, Node* new_entry, bool clone_limit_check);
+  Node*  move_loop_predicates(Node* old_entry, Node* new_entry, bool clone_limit_check);
 
   void eliminate_loop_predicates(Node* entry);
   static Node* skip_loop_predicates(Node* entry);
@@ -873,7 +897,7 @@
   // Find a predicate
   static Node* find_predicate(Node* entry);
   // Construct a range check for a predicate if
-  BoolNode* rc_predicate(Node* ctrl,
+  BoolNode* rc_predicate(IdealLoopTree *loop, Node* ctrl,
                          int scale, Node* offset,
                          Node* init, Node* limit, Node* stride,
                          Node* range, bool upper);
@@ -903,11 +927,11 @@
 
   // Range Check Elimination uses this function!
   // Constrain the main loop iterations so the affine function:
-  //    scale_con * I + offset  <  limit
+  //    low_limit <= scale_con * I + offset  <  upper_limit
   // always holds true.  That is, either increase the number of iterations in
   // the pre-loop or the post-loop until the condition holds true in the main
   // loop.  Scale_con, offset and limit are all loop invariant.
-  void add_constraint( int stride_con, int scale_con, Node *offset, Node *limit, Node *pre_ctrl, Node **pre_limit, Node **main_limit );
+  void add_constraint( int stride_con, int scale_con, Node *offset, Node *low_limit, Node *upper_limit, Node *pre_ctrl, Node **pre_limit, Node **main_limit );
 
   // Partially peel loop up through last_peel node.
   bool partial_peel( IdealLoopTree *loop, Node_List &old_new );
--- a/src/share/vm/opto/macro.cpp	Wed May 04 03:42:58 2011 -0700
+++ b/src/share/vm/opto/macro.cpp	Wed May 04 13:12:42 2011 -0700
@@ -2154,6 +2154,11 @@
       debug_only(int old_macro_count = C->macro_count(););
       if (n->is_AbstractLock()) {
         success = eliminate_locking_node(n->as_AbstractLock());
+      } else if (n->Opcode() == Op_LoopLimit) {
+        // Remove it from macro list and put on IGVN worklist to optimize.
+        C->remove_macro_node(n);
+        _igvn._worklist.push(n);
+        success = true;
       } else if (n->Opcode() == Op_Opaque1 || n->Opcode() == Op_Opaque2) {
         _igvn.replace_node(n, n->in(1));
         success = true;
--- a/src/share/vm/opto/matcher.cpp	Wed May 04 03:42:58 2011 -0700
+++ b/src/share/vm/opto/matcher.cpp	Wed May 04 13:12:42 2011 -0700
@@ -2086,6 +2086,13 @@
         n->del_req(3);
         break;
       }
+      case Op_LoopLimit: {
+        Node *pair1 = new (C, 3) BinaryNode(n->in(1),n->in(2));
+        n->set_req(1,pair1);
+        n->set_req(2,n->in(3));
+        n->del_req(3);
+        break;
+      }
       case Op_StrEquals: {
         Node *pair1 = new (C, 3) BinaryNode(n->in(2),n->in(3));
         n->set_req(2,pair1);
--- a/src/share/vm/opto/parse.hpp	Wed May 04 03:42:58 2011 -0700
+++ b/src/share/vm/opto/parse.hpp	Wed May 04 13:12:42 2011 -0700
@@ -70,7 +70,7 @@
   const char* try_to_inline(ciMethod* callee_method, ciMethod* caller_method, int caller_bci, ciCallProfile& profile, WarmCallInfo* wci_result);
   const char* shouldInline(ciMethod* callee_method, ciMethod* caller_method, int caller_bci, ciCallProfile& profile, WarmCallInfo* wci_result) const;
   const char* shouldNotInline(ciMethod* callee_method, ciMethod* caller_method, WarmCallInfo* wci_result) const;
-  void        print_inlining(ciMethod *callee_method, int caller_bci, const char *failure_msg) const PRODUCT_RETURN;
+  void        print_inlining(ciMethod *callee_method, int caller_bci, const char *failure_msg) const;
 
   InlineTree *caller_tree()       const { return _caller_tree;  }
   InlineTree* callee_at(int bci, ciMethod* m) const;
--- a/src/share/vm/opto/parse1.cpp	Wed May 04 03:42:58 2011 -0700
+++ b/src/share/vm/opto/parse1.cpp	Wed May 04 13:12:42 2011 -0700
@@ -638,7 +638,7 @@
         ensure_phis_everywhere();
 
         if (block->is_SEL_head() &&
-            UseLoopPredicate) {
+            (UseLoopPredicate || LoopLimitCheck)) {
           // Add predicate to single entry (not irreducible) loop head.
           assert(!block->has_merged_backedge(), "only entry paths should be merged for now");
           // Need correct bci for predicate.
--- a/src/share/vm/opto/phaseX.hpp	Wed May 04 03:42:58 2011 -0700
+++ b/src/share/vm/opto/phaseX.hpp	Wed May 04 13:12:42 2011 -0700
@@ -472,8 +472,8 @@
   }
 
   // Clone loop predicates. Defined in loopTransform.cpp.
-  Node* clone_loop_predicates(Node* old_entry, Node* new_entry);
-  Node*  move_loop_predicates(Node* old_entry, Node* new_entry);
+  Node* clone_loop_predicates(Node* old_entry, Node* new_entry, bool clone_limit_check);
+  Node*  move_loop_predicates(Node* old_entry, Node* new_entry, bool clone_limit_check);
   // Create a new if below new_entry for the predicate to be cloned
   ProjNode* create_new_if_for_predicate(ProjNode* cont_proj, Node* new_entry,
                                         Deoptimization::DeoptReason reason);
--- a/src/share/vm/runtime/deoptimization.cpp	Wed May 04 03:42:58 2011 -0700
+++ b/src/share/vm/runtime/deoptimization.cpp	Wed May 04 13:12:42 2011 -0700
@@ -1773,7 +1773,8 @@
   "constraint",
   "div0_check",
   "age",
-  "predicate"
+  "predicate",
+  "loop_limit_check"
 };
 const char* Deoptimization::_trap_action_name[Action_LIMIT] = {
   // Note:  Keep this in sync. with enum DeoptAction.
--- a/src/share/vm/runtime/deoptimization.hpp	Wed May 04 03:42:58 2011 -0700
+++ b/src/share/vm/runtime/deoptimization.hpp	Wed May 04 13:12:42 2011 -0700
@@ -56,6 +56,7 @@
     Reason_div0_check,            // a null_check due to division by zero
     Reason_age,                   // nmethod too old; tier threshold reached
     Reason_predicate,             // compiler generated predicate failed
+    Reason_loop_limit_check,      // compiler generated loop limits check failed
     Reason_LIMIT,
     // Note:  Keep this enum in sync. with _trap_reason_name.
     Reason_RECORDED_LIMIT = Reason_bimorphic  // some are not recorded per bc
@@ -78,7 +79,7 @@
 
   enum {
     _action_bits = 3,
-    _reason_bits = 4,
+    _reason_bits = 5,
     _action_shift = 0,
     _reason_shift = _action_shift+_action_bits,
     BC_CASE_LIMIT = PRODUCT_ONLY(1) NOT_PRODUCT(4) // for _deoptimization_hist
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/compiler/5091921/Test5091921.java	Wed May 04 13:12:42 2011 -0700
@@ -0,0 +1,309 @@
+/*
+ * Copyright (c) 2011 Hewlett-Packard Company. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+/**
+ * @test
+ * @bug 5091921
+ * @summary Sign flip issues in loop optimizer
+ *
+ * @run main/othervm -Xcomp -XX:CompileOnly=Test5091921 -XX:MaxInlineSize=1 Test5091921
+ */
+
+public class Test5091921 {
+  private static int result = 0;
+
+
+  /* Test for the bug of transforming indx >= MININT to indx > MININT-1 */
+  public static int test_ge1(int limit) {
+    int indx;
+    int sum = 0;
+    for (indx = 500; indx >= limit; indx -= 2) {
+      sum += 2000 / indx;
+      result = sum;
+    }
+    return sum;
+  }
+
+  /* Test for the bug of transforming indx <= MAXINT to indx < MAXINT+1 */
+  public static int test_le1(int limit) {
+    int indx;
+    int sum = 0;
+    for (indx = -500; indx <= limit; indx += 2)
+    {
+      sum += 3000 / indx;
+      result = sum;
+    }
+    return sum;
+  }
+
+  /* Run with -Xcomp -XX:CompileOnly=wrap1.test1 -XX:MaxInlineSize=1 */
+  /* limit reset to ((limit-init+stride-1)/stride)*stride+init */
+  /* Calculation may overflow */
+  public static volatile int c = 1;
+  public static int test_wrap1(int limit)
+  {
+    int indx;
+    int sum = 0;
+    for (indx = 0xffffffff; indx < limit; indx += 0x20000000)
+    {
+      sum += c;
+    }
+    return sum;
+  }
+
+  /* Test for range check elimination with bit flip issue for
+     scale*i+offset<limit where offset is not 0 */
+  static int[] box5 = {1,2,3,4,5,6,7,8,9};
+  public static int test_rce5(int[] b, int limit)
+  {
+    int indx;
+    int sum = b[1];
+    result = sum;
+    for (indx = 0x80000000; indx < limit; ++indx)
+    {
+      if (indx > 0x80000000)
+      {
+        // this test is not issued in pre-loop but issued in main loop
+        // trick rce into thinking expression is false when indx >= 0
+        // in fact it is false when indx==0x80000001
+        if (indx - 9 < -9)
+        {
+          sum += indx;
+          result = sum;
+          sum ^= b[indx & 7];
+          result = sum;
+        }
+        else
+          break;
+      }
+      else
+      {
+        sum += b[indx & 3];
+        result = sum;
+      }
+    }
+    return sum;
+  }
+
+  /* Test for range check elimination with bit flip issue for
+     scale*i<limit where scale > 1 */
+  static int[] box6 = {1,2,3,4,5,6,7,8,9};
+  public static int test_rce6(int[] b, int limit)
+  {
+    int indx;
+    int sum = b[1];
+    result = sum;
+    for (indx = 0x80000000; indx < limit; ++indx)
+    {
+      if (indx > 0x80000000)
+      {
+        // harmless rce target
+        if (indx < 0)
+        {
+          sum += result;
+          result = sum;
+        }
+        else
+          break;
+        // this test is not issued in pre-loop but issued in main loop
+        // trick rce into thinking expression is false when indx >= 0
+        // in fact it is false when indx==0x80000001
+        // In compilers that transform mulI to shiftI may mask this issue.
+        if (indx * 28 + 1 < 0)
+        {
+          sum += indx;
+          result = sum;
+          sum ^= b[indx & 7];
+          result = sum;
+        }
+        else
+          break;
+      }
+      else
+      {
+        sum += b[indx & 3];
+        result = sum;
+      }
+    }
+    return sum;
+  }
+
+  /* Test for range check elimination with i <= limit */
+  static int[] box7 = {1,2,3,4,5,6,7,8,9,0x7fffffff};
+  public static int test_rce7(int[] b)
+  {
+    int indx;
+    int max = b[9];
+    int sum = b[7];
+    result = sum;
+    for (indx = 0; indx < b.length; ++indx)
+    {
+      if (indx <= max)
+      {
+        sum += (indx ^ 15) + ((result != 0) ? 0 : sum);
+        result = sum;
+      }
+      else
+        throw new RuntimeException();
+    }
+    for (indx = -7; indx < b.length; ++indx)
+    {
+      if (indx <= 9)
+      {
+        sum += (sum ^ 15) + ((result != 0) ? 0 : sum);
+        result = sum;
+      }
+      else
+        throw new RuntimeException();
+    }
+    return sum;
+  }
+
+  /* Test for range check elimination with i >= limit */
+  static int[] box8 = {-1,0,1,2,3,4,5,6,7,8,0x80000000};
+  public static int test_rce8(int[] b)
+  {
+    int indx;
+    int sum = b[5];
+    int min = b[10];
+    result = sum;
+    for (indx = b.length-1; indx >= 0; --indx)
+    {
+      if (indx >= min)
+      {
+        sum += (sum ^ 9) + ((result != 0) ? 0 :sum);
+        result = sum;
+      }
+      else
+        throw new RuntimeException();
+    }
+    return sum;
+  }
+
+  public static void main(String[] args)
+  {
+    result=1;
+    int r = 0;
+    try {
+      r = test_ge1(0x80000000);
+      System.out.println(result);
+      System.out.println("test_ge1 FAILED");
+      System.exit(1);
+    }
+    catch (ArithmeticException e1) {
+      System.out.println("test_ge1: Expected exception caught");
+      if (result != 5986) {
+        System.out.println(result);
+        System.out.println("test_ge1 FAILED");
+        System.exit(97);
+      }
+    }
+    System.out.println("test_ge1 WORKED");
+
+    result=0;
+    try
+    {
+      r = test_le1(0x7fffffff);
+      System.out.println(result);
+      System.out.println("test_le1 FAILED");
+      System.exit(1);
+    }
+    catch (ArithmeticException e1)
+    {
+      System.out.println("test_le1: Expected exception caught");
+      if (result != -9039)
+      {
+        System.out.println(result);
+        System.out.println("test_le1 FAILED");
+        System.exit(97);
+      }
+    }
+    System.out.println("test_le1 WORKED");
+
+    result=0;
+    r = test_wrap1(0x7fffffff);
+    if (r != 4)
+    {
+      System.out.println(result);
+      System.out.println("test_wrap1 FAILED");
+      System.exit(97);
+    }
+    else
+    {
+      System.out.println("test_wrap1 WORKED");
+    }
+
+    result=0;
+    r = test_rce5(box5,0x80000100);
+    if (result != 3)
+    {
+      System.out.println(result);
+      System.out.println("test_rce5 FAILED");
+      System.exit(97);
+    }
+    else
+    {
+      System.out.println("test_rce5 WORKED");
+    }
+
+    result=0;
+    r = test_rce6(box6,0x80000100);
+    if (result != 6)
+    {
+      System.out.println(result);
+      System.out.println("test_rce6 FAILED");
+      System.exit(97);
+    }
+    else
+    {
+      System.out.println("test_rce6 WORKED");
+    }
+
+    result=0;
+    r = test_rce7(box7);
+    if (result != 14680079)
+    {
+      System.out.println(result);
+      System.out.println("test_rce7 FAILED");
+      System.exit(97);
+    }
+    else
+    {
+      System.out.println("test_rce7 WORKED");
+    }
+
+    result=0;
+    r = test_rce8(box8);
+    if (result != 16393)
+    {
+      System.out.println(result);
+      System.out.println("test_rce8 FAILED");
+      System.exit(97);
+    }
+    else
+    {
+      System.out.println("test_rce8 WORKED");
+    }
+  }
+}
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/compiler/5091921/Test6186134.java	Wed May 04 13:12:42 2011 -0700
@@ -0,0 +1,71 @@
+/*
+ * Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+/**
+ * @test
+ * @bug 6186134
+ * @summary Server virtual machine produces/exeutes incorrect code.
+ *
+ * @run main Test6186134 100000
+ */
+import java.util.ArrayList;
+
+public class Test6186134 {
+
+  int num = 0;
+
+  public Test6186134(int n) {
+    num = n;
+  }
+
+  public boolean more() {
+    return num-- > 0;
+  }
+
+  public ArrayList test1() {
+    ArrayList res = new ArrayList();
+    int maxResults = Integer.MAX_VALUE;
+    int n = 0;
+    boolean more = more();
+    while ((n++ < maxResults) && more) {
+      res.add(new Object());
+      more = more();
+    }
+    return res;
+  }
+
+  public static void main(String[] pars) {
+    int n = Integer.parseInt(pars[0]);
+    for (int i=0; i<n; i++) {
+      Test6186134 t = new Test6186134(10);
+      int size = t.test1().size();
+      if (size != 10) {
+        System.out.println("wrong size: " + size +", should be 10");
+        System.exit(97);
+      }
+    }
+    System.out.println("Passed");
+  }
+}
+
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/compiler/5091921/Test6196102.java	Wed May 04 13:12:42 2011 -0700
@@ -0,0 +1,47 @@
+/*
+ * Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+/**
+ * @test
+ * @bug 6196102
+ * @summary Integer seems to be greater than Integer.MAX_VALUE
+ *
+ * @run main Test6196102
+ */
+
+public class Test6196102 {
+    static public void main(String[] args) {
+        int i1 = 0;
+        int i2 = Integer.MAX_VALUE;
+
+        while (i1 >= 0) {
+            i1++;
+            if (i1 > i2) {
+                System.out.println("E R R O R: " + i1);
+                System.exit(97);
+            }
+        }
+    }
+}
+
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/compiler/5091921/Test6357214.java	Wed May 04 13:12:42 2011 -0700
@@ -0,0 +1,179 @@
+/*
+ * Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+/**
+ * @test
+ * @bug 6357214
+ * @summary Hotspot server compiler gets integer comparison wrong
+ *
+ * @run main/othervm/timeout=60 -DshowAll=ffo -DeventID=444 Test6357214
+ */
+
+// The test hangs after few iterations before the fix. So it fails if timeout.
+class MyResult {
+        public boolean next() {
+                return true;
+        }
+
+        public String getString(String in) {
+                if (in.equals("id"))
+                        return "idFoo";
+                if (in.equals("contentKey"))
+                        return "ckFoo";
+                return "Foo";
+        }
+
+        public int getInt(String in) {
+                if (in.equals("processingComplete"))
+                        return 0;
+                return 1;
+        }
+
+        public byte[] getBytes(String in) {
+                byte[] arr = null;
+                if (in.equals("content")) {
+                        arr = new byte[65536];
+                        byte j = 32;
+                        for (int i=0; i<65536; i++) {
+                                arr[i] = j;
+                                if (++j == 127)
+                                        j=32;
+                        }
+                }
+                return arr;
+        }
+}
+
+public class Test6357214 {
+        public static volatile boolean bollocks = true;
+    public String create(String context) throws Exception {
+
+        //
+        // Extract HTTP parameters
+        //
+
+        boolean showAll = System.getProperty("showAll") != null;
+          String eventID = System.getProperty("eventID");
+          String eventContentKey = System.getProperty("cKey");
+        //
+        // Build ContentStaging query based on eventID or eventContentKey
+        //
+
+        String sql = "select id, processingComplete, contentKey, content "
+                   + "from   ContentStaging cs, ContentStagingKey csk "
+                   + "where  cs.eventContentKey = csk.eventContentKey ";
+
+        if (eventID != null) {
+            sql += "and id = " + eventID;
+        }
+        else if (eventContentKey != null) {
+            sql += "and cs.eventContentKey = '"
+                +  eventContentKey
+                +  "' having id = max(id)";
+        }
+        else {
+            throw new Exception("Need eventID or eventContentKey");
+        }
+
+        //
+        // This factory builds a static panel, there is no JSP
+        //
+
+        StringBuffer html = new StringBuffer();
+
+        try {
+
+                MyResult result = new MyResult();
+            if (result.next()) {
+
+                eventID = result.getString("id");
+                int processingComplete = result.getInt("processingComplete");
+                String contentKey = result.getString("contentKey");
+                byte[] bytes = result.getBytes("content");
+
+                //
+                // Print content status and associated controls
+                //
+
+                html.append("<br/><font class=\"small\">");
+                html.append("Status: ");
+                switch (processingComplete) {
+                    case  0 :
+                    case  1 : html.append("PENDING"); break;
+                    case  2 : html.append(contentKey); break;
+                    case  3 : html.append(eventID); break;
+                    default : html.append("UNKNONW");
+                }
+                html.append("</font><br/>");
+
+                //
+                // Print at most 20Kb of content unless "showAll" is set
+                //
+
+                int limit = showAll ? Integer.MAX_VALUE : 1024 * 20;
+                System.out.println(limit);
+                html.append("<pre>");
+                for (int i = 0; bytes != null && i < bytes.length; i++) {
+                    char c = (char) bytes[i];
+                    switch (c) {
+                        case '<' : html.append("&lt;");  break;
+                        case '>' : html.append("&gt;");  break;
+                        case '&' : html.append("&amp;"); break;
+                        default  : html.append(c);
+                    }
+
+                    if (i > limit) {
+                        while (bollocks);
+                        // System.out.println("i is " + i);
+                        // System.out.println("limit is " + limit);
+                        html.append("...\n</pre>");
+                        html.append(eventID);
+                        html.append("<pre>");
+                        break;
+                    }
+                }
+                html.append("</pre>");
+            }
+        }
+        catch (Exception exception) {
+            throw exception;
+        }
+        finally {
+            html.append("Oof!!");
+        }
+        String ret = html.toString();
+        System.out.println("Returning string length = "+ ret.length());
+        return ret;
+    }
+
+    public static void main(String[] args) throws Exception {
+                int length=0;
+
+                for (int i = 0; i < 100; i++) {
+                        length = new Test6357214().create("boo").length();
+                        System.out.println(length);
+                }
+    }
+}
+
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/compiler/5091921/Test6559156.java	Wed May 04 13:12:42 2011 -0700
@@ -0,0 +1,81 @@
+/*
+ * Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+/**
+ * @test
+ * @bug 6559156
+ * @summary Server compiler generates bad code for "<= Integer.MAX_VALUE" expression
+ *
+ * @run main Test6559156
+ */
+
+public class Test6559156 {
+
+    static final int N_TESTS = 1000000;
+
+    public static void main(String[] args) throws Exception {
+
+        /*
+         * If MAX_VALUE is changed to MAX_VALUE - 1 below, the test passes
+         * because (apparently) bad code is only generated when comparing
+         * <= MAX_VALUE in the doTest method.
+         */
+        Test6559156 test = new Test6559156();
+        for (int i = 0; i < N_TESTS; i += 1) {
+            test.doTest1(10, Integer.MAX_VALUE, i);
+            test.doTest2(10, Integer.MAX_VALUE, i);
+        }
+        System.out.println("No failure");
+    }
+
+    void doTest1(int expected, int max, int i) {
+        int counted;
+        for (counted = 0;
+             (counted <= max) && (counted < expected);
+             counted += 1) {
+        }
+        if (counted != expected) {
+            throw new RuntimeException("Failed test1 iteration=" + i +
+                                       " max=" + max +
+                                       " counted=" + counted +
+                                       " expected=" + expected);
+        }
+    }
+
+    void doTest2(int expected, int max, int i) {
+        int counted;
+        for (counted = 0;
+             // change test sequence.
+             (counted < expected) && (counted <= max);
+             counted += 1) {
+        }
+        if (counted != expected) {
+            throw new RuntimeException("Failed test1 iteration=" + i +
+                                       " max=" + max +
+                                       " counted=" + counted +
+                                       " expected=" + expected);
+        }
+    }
+}
+
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/compiler/5091921/Test6753639.java	Wed May 04 13:12:42 2011 -0700
@@ -0,0 +1,50 @@
+/*
+ * Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+/**
+ * @test
+ * @bug 6753639
+ * @summary Strange optimisation in for loop with cyclic integer condition
+ *
+ * @run main/othervm -Xbatch Test6753639
+ */
+
+public class Test6753639 {
+    public static void main(String[] args) throws InterruptedException {
+        int END = Integer.MAX_VALUE;
+        int count = 0;
+        for(int i = Integer.MAX_VALUE - 5; i <= END; i++) {
+            count++;
+            if (count > 100000) {
+                System.out.println("Passed");
+                System.exit(95);
+            }
+        }
+        System.out.println("broken " + count);
+        System.out.println("FAILED");
+        System.exit(97);
+    }
+}
+
+
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/compiler/5091921/Test6850611.java	Wed May 04 13:12:42 2011 -0700
@@ -0,0 +1,53 @@
+/*
+ * Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+/**
+ * @test
+ * @bug 6850611
+ * @summary int / long arithmetic seems to be broken in 1.6.0_14 HotSpot Server VM (Win XP)
+ *
+ * @run main Test6850611
+ */
+
+public class Test6850611 {
+
+    public static void main(String[] args) {
+        test();
+    }
+
+    private static void test() {
+        for (int j = 0; j < 5; ++j) {
+            long x = 0;
+            for (int i = Integer.MIN_VALUE; i < Integer.MAX_VALUE; ++i) {
+                x += i;
+            }
+            System.out.println("sum: " + x);
+            if (x != -4294967295l) {
+                System.out.println("FAILED");
+                System.exit(97);
+            }
+        }
+    }
+}
+
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/compiler/5091921/Test6890943.java	Wed May 04 13:12:42 2011 -0700
@@ -0,0 +1,189 @@
+/*
+ * Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+/**
+ * @test
+ * @bug 6890943
+ * @summary JVM mysteriously gives wrong result on 64-bit 1.6 VMs in hotspot mode.
+ *
+ * @run shell Test6890943.sh
+ */
+import java.util.*;
+import java.io.*;
+import java.util.regex.*;
+
+public class Test6890943 {
+  public static final boolean AIR = true, ROCK = false;
+  public static void main(String[] args) {
+    new Test6890943().go();
+  }
+
+  int r, c, f, t;
+  boolean[][] grid;
+
+  public void go() {
+    Scanner s = new Scanner(System.in);
+    s.useDelimiter("\\s+");
+    int T = s.nextInt();
+    for (t = 0 ; t < T ; t++) {
+      r = s.nextInt(); c = s.nextInt(); f = s.nextInt();
+      grid = new boolean[r][c];
+      for (int x = 0 ; x < r ; x++) {
+        String line = s.next();
+        for (int y = 0 ; y < c ; y++) grid[x][y] = line.charAt(y) == '.';
+      }
+      int digs = solve();
+      String res = digs == -1 ? "No" : "Yes " + digs;
+      System.out.printf("Case #%d: %s\n", t+1, res);
+    }
+  }
+
+  Map<Integer, Integer> M = new HashMap<Integer, Integer>();
+
+  private int solve() {
+    M = new HashMap<Integer, Integer>();
+    M.put(calcWalkingRange(0, 0), 0);
+    for (int digDown = 0 ; digDown < r ; digDown++) {
+      Map<Integer, Integer> tries = new HashMap<Integer, Integer>();
+      for (Map.Entry<Integer, Integer> m : M.entrySet()) {
+        int q = m.getKey();
+        if (depth(q) != (digDown)) continue;
+        if (stuck(q)) continue;
+        tries.put(q, m.getValue());
+      }
+
+      for (Map.Entry<Integer, Integer> m : tries.entrySet()) {
+        int q = m.getKey();
+        int fallLeftDelta = 0, fallRightDelta = 0;
+        //fall left
+        int fallLeft = fall(digDown, start(q));
+        if (fallLeft > 0) {
+          fallLeftDelta = 1;
+          if (fallLeft <= f) addToM(calcWalkingRange(digDown+fallLeft, start(q)), m.getValue());
+        }
+
+        //fall right
+        int fallRight = fall(digDown, end(q));
+        if (fallRight > 0) {
+          fallRightDelta = 1;
+
+          if (fallRight <= f) addToM(calcWalkingRange(digDown+fallRight, end(q)), m.getValue());
+        }
+
+        for (int p = start(q) + fallLeftDelta ; p <= end(q) - fallRightDelta ; p++) {
+          //goLeft
+          for (int digSpot = p ; digSpot > start(q) +fallLeftDelta ; digSpot--) {
+            int fallDown = 1+fall(digDown+1, digSpot);
+            if (fallDown <= f) {
+              if (fallDown == 1) {
+                addToM(calcWalkingRange(digDown + 1, digSpot, digSpot, p), m.getValue() + Math.abs(digSpot-p)+1);
+              } else {
+                addToM(calcWalkingRange(digDown + fallDown, digSpot), m.getValue() + Math.abs(digSpot-p)+1);
+              }
+            }
+          }
+
+          //goRight
+          for (int digSpot = p ; digSpot < end(q)-fallRightDelta ;digSpot++) {
+            int fallDown = 1+fall(digDown+1, digSpot);
+            if (fallDown <= f) {
+              if (fallDown == 1) {
+                addToM(calcWalkingRange(digDown + 1, digSpot, p, digSpot), m.getValue() + Math.abs(digSpot-p)+1);
+              } else {
+                addToM(calcWalkingRange(digDown + fallDown, digSpot), m.getValue() + Math.abs(digSpot-p)+1);
+              }
+            }
+          }
+        }
+      }
+    }
+
+    int result = Integer.MAX_VALUE;
+    for (Map.Entry<Integer, Integer> m : M.entrySet()) {
+      if (depth(m.getKey()) == r-1) result = Math.min(m.getValue(), result);
+    }
+
+    if (result == Integer.MAX_VALUE) return -1;
+    return result;
+  }
+
+  private void addToM(int q, int i) {
+    Integer original = M.get(q);
+    if ( original == null ) M.put(q, i);
+    else M.put(q, Math.min(original, i));
+  }
+
+  private int fall(int row, int column) {
+    int res = 0;
+    for ( int p = row+1 ; p < r ; p++) {
+      if (grid[p][column] == AIR) res++;
+      else break;
+    }
+    return res;
+  }
+
+  private boolean stuck(int q) {
+    return start(q) == end(q);
+  }
+
+  private int depth(int q) {
+    return q % 50;
+  }
+
+  private int start(int q) {
+    return q / (50*50);
+  }
+
+  private int end(int q) {
+    return (q / 50) % 50;
+  }
+
+  private int calcWalkingRange(int depth, int pos) {
+    return calcWalkingRange(depth, pos, Integer.MAX_VALUE, Integer.MIN_VALUE);
+  }
+
+  private int calcWalkingRange(int depth, int pos, int airOverrideStart, int airOverrideEnd) {
+    int left = pos, right = pos;
+    if (depth >= r) return (c-1)*50 + depth;
+
+    while (left > 0) {
+      if (grid[depth][left-1] == ROCK && (left-1 < airOverrideStart || left-1 > airOverrideEnd)) break;
+      if (depth < r-1 && grid[depth+1][left-1] == AIR) {
+        left--;
+        break;
+      }
+      left--;
+    }
+    while (right < c-1) {
+      if (grid[depth][right+1] == ROCK && (right+1 < airOverrideStart || right+1 > airOverrideEnd)) break;
+      if (depth < r-1 && grid[depth+1][right+1] == AIR) {
+        right++;
+        break;
+      }
+      right++;
+    }
+
+    return left *50*50 + right*50 + depth;
+  }
+}
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/compiler/5091921/Test6890943.sh	Wed May 04 13:12:42 2011 -0700
@@ -0,0 +1,67 @@
+#!/bin/sh
+# 
+# Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved.
+# DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+# 
+# This code is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License version 2 only, as
+# published by the Free Software Foundation.
+# 
+# This code is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+# version 2 for more details (a copy is included in the LICENSE file that
+# accompanied this code).
+# 
+# You should have received a copy of the GNU General Public License version
+# 2 along with this work; if not, write to the Free Software Foundation,
+# Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+# 
+# Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+# or visit www.oracle.com if you need additional information or have any
+# questions.
+# 
+# 
+
+if [ "${TESTSRC}" = "" ]
+then
+  echo "TESTSRC not set.  Test cannot execute.  Failed."
+  exit 1
+fi
+echo "TESTSRC=${TESTSRC}"
+if [ "${TESTJAVA}" = "" ]
+then
+  echo "TESTJAVA not set.  Test cannot execute.  Failed."
+  exit 1
+fi
+echo "TESTJAVA=${TESTJAVA}"
+if [ "${TESTCLASSES}" = "" ]
+then
+  echo "TESTCLASSES not set.  Test cannot execute.  Failed."
+  exit 1
+fi
+echo "TESTCLASSES=${TESTCLASSES}"
+echo "CLASSPATH=${CLASSPATH}"
+
+set -x
+
+cp ${TESTSRC}/Test6890943.java .
+cp ${TESTSRC}/input6890943.txt .
+cp ${TESTSRC}/output6890943.txt .
+cp ${TESTSRC}/Test6890943.sh .
+
+${TESTJAVA}/bin/javac -d . Test6890943.java
+
+${TESTJAVA}/bin/java  ${TESTVMOPTS} Test6890943 < input6890943.txt > test.out 2>&1
+
+diff output6890943.txt test.out
+
+result=$?
+if [ $result -eq 0 ]
+then
+  echo "Passed"
+  exit 0
+else
+  echo "Failed"
+  exit 1
+fi
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/compiler/5091921/Test6897150.java	Wed May 04 13:12:42 2011 -0700
@@ -0,0 +1,58 @@
+/*
+ * Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+/**
+ * @test
+ * @bug 6897150
+ * @summary Hotspot optimises away a valid loop
+ *
+ * @run main Test6897150
+ */
+
+// Should be compiled with javac from JDK1.3 to get bytecode which shows the problem.
+public class Test6897150 {
+    public static void main(String[] args) {
+        // This works
+        loopAndPrint(Integer.MAX_VALUE -1);
+        // This doesn't
+        loopAndPrint(Integer.MAX_VALUE);
+    }
+
+    static void verify(int max, int a) {
+        if ( a != (max - 1)) {
+            System.out.println("Expected: " + (max - 1));
+            System.out.println("Actual  : " + a);
+            System.exit(97);
+        }
+    }
+    static void loopAndPrint(int max) {
+        int a = -1;
+        int i = 1;
+        for (; i < max; i++) {
+            a = i;
+        }
+        verify(max, a);
+    }
+}
+
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/compiler/5091921/Test6905845.java	Wed May 04 13:12:42 2011 -0700
@@ -0,0 +1,76 @@
+/*
+ * Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+/**
+ * @test
+ * @bug 6905845
+ * @summary Server VM improperly optimizing away loop.
+ *
+ * @run main Test6905845
+ */
+
+public class Test6905845 {
+
+   public static void main(String[] args){
+      for (int asdf = 0; asdf < 5; asdf++){
+         //test block
+         {
+            StringBuilder strBuf1 = new StringBuilder(65);
+            long          start   = System.currentTimeMillis();
+            int           count   = 0;
+
+            for (int i = Integer.MIN_VALUE; i < (Integer.MAX_VALUE - 80); i += 79){
+               strBuf1.append(i);
+               count++;
+               strBuf1.delete(0, 65);
+            }
+
+            System.out.println(count);
+            if (count != 54366674) {
+              System.out.println("wrong count: " + count +", should be 54366674");
+              System.exit(97);
+            }
+         }
+         //test block
+         {
+            StringBuilder strBuf1 = new StringBuilder(65);
+            long          start   = System.currentTimeMillis();
+            int           count   = 0;
+
+            for (int i = Integer.MIN_VALUE; i < (Integer.MAX_VALUE - 80); i += 79){
+               strBuf1.append(i);
+               count++;
+               strBuf1.delete(0, 65);
+            }
+
+            System.out.println(count);
+            if (count != 54366674) {
+              System.out.println("wrong count: " + count +", should be 54366674");
+              System.exit(97);
+            }
+         }
+      }
+   }
+}
+
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/compiler/5091921/Test6931567.java	Wed May 04 13:12:42 2011 -0700
@@ -0,0 +1,62 @@
+/*
+ * Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+/**
+ * @test
+ * @bug 6931567
+ * @summary JIT Error (on class file compiled with eclipse) on JVM x64 (but not on x32!).
+ *
+ * @run main Test6931567
+ */
+
+// Should be compiled with javac from JDK1.3 to get bytecode which shows the problem.
+public class Test6931567 {
+
+    public static void main(final String[] args) {
+        booleanInvert(Integer.MAX_VALUE);
+        booleanInvert(Integer.MAX_VALUE - 1);
+    }
+
+    private static void booleanInvert(final int max) {
+        boolean test1 = false;
+        boolean test2 = false;
+
+        for (int i = 0; i < max; i++) {
+            test1 = !test1;
+        }
+
+        for (int i = 0; i < max; i++) {
+            test2 ^= true;
+        }
+
+        if (test1 != test2) {
+            System.out.println("ERROR: Boolean invert\n\ttest1=" + test1
+                    + "\n\ttest2=" + test2);
+            System.exit(97);
+        } else {
+            System.out.println("Passed!");
+        }
+    }
+}
+
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/compiler/5091921/Test6935022.java	Wed May 04 13:12:42 2011 -0700
@@ -0,0 +1,74 @@
+/*
+ * Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+/**
+ * @test
+ * @bug 6935022
+ * @summary Server VM incorrectly breaks out of while loop
+ *
+ * @run main Test6935022
+ */
+
+public class Test6935022 {
+    public static final void main(String[] args) throws Exception {
+        Test6935022 test = new Test6935022();
+
+        int cnt = 0;
+
+        while (cnt < 10000) {
+            try {
+                ++cnt;
+                if ((cnt&1023) == 0)
+                  System.out.println("Thread="+Thread.currentThread().getName() + " iteration: " + cnt);
+                test.loop(2147483647, (cnt&1023));
+            }
+
+            catch (Exception e) {
+                System.out.println("Caught on iteration " + cnt);
+                e.printStackTrace();
+                System.exit(97);
+            }
+        }
+    }
+
+    private void loop(int endingRow, int mask) throws Exception {
+        int rows = 1;
+        boolean next = true;
+
+        while(rows <= endingRow && next) {
+            rows++;
+            if (rows == mask)
+              System.out.println("Rows="+rows+", end="+endingRow+", next="+next);
+            next = next(rows);
+        }
+
+        if (next)
+            throw new Exception("Ended on rows(no rs): " + rows);
+    }
+
+    private boolean next(int rows) {
+        return rows < 12;
+    }
+}
+
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/compiler/5091921/Test6959129.java	Wed May 04 13:12:42 2011 -0700
@@ -0,0 +1,90 @@
+/*
+ * Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+/**
+ * @test
+ * @bug 6959129
+ * @summary COMPARISON WITH INTEGER.MAX_INT DOES NOT WORK CORRECTLY IN THE CLIENT VM.
+ *
+ * @run main/othervm -ea Test6959129
+ */
+
+public class Test6959129 {
+
+  public static void main(String[] args) {
+    long start  = System.currentTimeMillis();
+    int min = Integer.MAX_VALUE-30000;
+    int max = Integer.MAX_VALUE;
+    long maxmoves = 0;
+    try {
+      maxmoves = maxMoves(min, max);
+    } catch (AssertionError e) {
+      System.out.println("Passed");
+      System.exit(95);
+    }
+    System.out.println("maxMove:" + maxmoves);
+    System.out.println("FAILED");
+    System.exit(97);
+  }
+  /**
+   * Imperative implementation that returns the length hailstone moves
+   * for a given number.
+   */
+  public static long hailstoneLengthImp(long n) {
+    long moves = 0;
+    while (n != 1) {
+      assert n > 1;
+      if (isEven(n)) {
+        n = n / 2;
+      } else {
+        n = 3 * n + 1;
+      }
+      ++moves;
+    }
+    return moves;
+  }
+
+  private static boolean isEven(long n) {
+    return n % 2 == 0;
+  }
+
+  /**
+   * Returns the maximum length of the hailstone sequence for numbers
+   * between min to max.
+   *
+   * For rec1 - Assume that min is bigger than max.
+   */
+  public static long maxMoves(int min, int max) {
+    long maxmoves = 0;
+    for (int n = min; n <= max; n++) {
+      if ((n & 1023) == 0) System.out.println(n);
+      long moves = hailstoneLengthImp(n);
+      if (moves > maxmoves) {
+        maxmoves = moves;
+      }
+    }
+    return maxmoves;
+  }
+}
+
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/compiler/5091921/Test6985295.java	Wed May 04 13:12:42 2011 -0700
@@ -0,0 +1,53 @@
+/*
+ * Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+/**
+ * @test
+ * @bug 6985295
+ * @summary JVM fails to evaluate condition randomly
+ *
+ * @run main/othervm -Xbatch Test6985295
+ */
+
+public class Test6985295 {
+
+    public static void main(String[] args) {
+        int min = Integer.MAX_VALUE-50000;
+        int max = Integer.MAX_VALUE;
+        System.out.println("max = " + max);
+        long counter = 0;
+        int i;
+        for(i = min; i <= max; i++) {
+            counter++;
+            if (counter > 1000000) {
+              System.out.println("Passed");
+              System.exit(95);
+            }
+        }
+        System.out.println("iteration went " + counter + " times (" + i + ")");
+        System.out.println("FAILED");
+        System.exit(97);
+    }
+}
+
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/compiler/5091921/Test6992759.java	Wed May 04 13:12:42 2011 -0700
@@ -0,0 +1,66 @@
+/*
+ * Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+/**
+ * @test
+ * @bug 6992759
+ * @summary Bad code generated for integer <= comparison, fails for Integer.MAX_VALUE
+ *
+ * @run main Test6992759
+ */
+
+public class Test6992759 {
+
+    static final int N_TESTS = 1000000000;
+
+    public static void main(String[] args) throws Exception {
+
+        /*
+         * If MAX_VALUE is changed to MAX_VALUE - 1 below, the test passes
+         * because (apparently) bad code is only generated when comparing
+         * <= MAX_VALUE in the doTest method.
+         */
+        Test6992759 test = new Test6992759();
+        for (int i = 0; i < N_TESTS; i += 1) {
+            test.doTest(10, Integer.MAX_VALUE, i);
+            //test.doTest(10, Integer.MAX_VALUE - 1, i);
+        }
+        System.out.println("No failure");
+    }
+
+    void doTest(int expected, int max, int i) {
+        int counted;
+        for (counted = 0;
+             (counted <= max) && (counted < expected);
+             counted += 1) {
+        }
+        if (counted != expected) {
+            throw new RuntimeException("Failed test iteration=" + i +
+                                       " max=" + max +
+                                       " counted=" + counted +
+                                       " expected=" + expected);
+        }
+    }
+}
+
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/compiler/5091921/Test7005594.java	Wed May 04 13:12:42 2011 -0700
@@ -0,0 +1,59 @@
+/*
+ * Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+/**
+ * @test
+ * @bug 7005594
+ * @summary Array overflow not handled correctly with loop optimzations
+ *
+ * @run main/othervm -Xms2048m -Xcomp -XX:CompileOnly=Test7005594.test Test7005594
+ */
+
+public class Test7005594 {
+
+      static int test(byte a[]){
+          int result=0;
+          for( int i=0; i<a.length; i+=((0x7fffffff>>1)+1) ){
+              result += a[i];
+          }
+          return result;
+      }
+
+      public static void main(String [] args){
+          byte a[]=new byte[(0x7fffffff>>1)+2];
+          int result = 0;
+          try {
+              result = test(a);
+          } catch (ArrayIndexOutOfBoundsException e) {
+              e.printStackTrace(System.out);
+              System.out.println("Passed");
+              System.exit(95);
+          }
+          System.out.println(result);
+          System.out.println("FAILED");
+          System.exit(97);
+      }
+
+}
+
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/compiler/5091921/Test7020614.java	Wed May 04 13:12:42 2011 -0700
@@ -0,0 +1,58 @@
+/*
+ * Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+/**
+ * @test
+ * @bug 7020614
+ * @summary "-server" mode optimizer makes code hang
+ *
+ * @run main/othervm/timeout=30 -Xbatch Test7020614
+ */
+
+public class Test7020614 {
+
+    private static final int ITERATIONS = 1000;
+    private static int doNotOptimizeOut = 0;
+
+    public static long bitCountShort() {
+        long t0 = System.currentTimeMillis();
+        int sum = 0;
+        for (int it = 0; it < ITERATIONS; ++it) {
+            short value = 0;
+            do {
+                sum += Integer.bitCount(value);
+            } while (++value != 0);
+        }
+        doNotOptimizeOut += sum;
+        return System.currentTimeMillis() - t0;
+    }
+
+    public static void main(String[] args) {
+        for (int i = 0; i < 4; ++i) {
+            System.out.println((i + 1) + ": " + bitCountShort());
+        }
+        System.out.println("doNotOptimizeOut value: " + doNotOptimizeOut);
+    }
+}
+
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/compiler/5091921/input6890943.txt	Wed May 04 13:12:42 2011 -0700
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--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/compiler/5091921/output6890943.txt	Wed May 04 13:12:42 2011 -0700
@@ -0,0 +1,50 @@
+Case #1: Yes 2
+Case #2: Yes 2
+Case #3: Yes 1
+Case #4: Yes 0
+Case #5: No
+Case #6: No
+Case #7: Yes 6
+Case #8: Yes 6
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+Case #12: Yes 0
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+Case #17: No
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+Case #19: Yes 7
+Case #20: Yes 2
+Case #21: Yes 1
+Case #22: No
+Case #23: Yes 3
+Case #24: Yes 1
+Case #25: Yes 7
+Case #26: No
+Case #27: Yes 2
+Case #28: Yes 4
+Case #29: Yes 2
+Case #30: Yes 1
+Case #31: Yes 2
+Case #32: Yes 20
+Case #33: Yes 161
+Case #34: Yes 48
+Case #35: No
+Case #36: Yes 218
+Case #37: Yes 51
+Case #38: Yes 247
+Case #39: Yes 32
+Case #40: Yes 31
+Case #41: Yes 31
+Case #42: Yes 25
+Case #43: Yes 17
+Case #44: Yes 2
+Case #45: Yes 61
+Case #46: Yes 25
+Case #47: No
+Case #48: No
+Case #49: Yes 8
+Case #50: Yes 0