--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/share/vm/opto/loopnode.cpp	Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,2886 @@
+/*
+ * Copyright 1998-2007 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ */
+
+#include "incls/_precompiled.incl"
+#include "incls/_loopnode.cpp.incl"
+
+//=============================================================================
+//------------------------------is_loop_iv-------------------------------------
+// Determine if a node is Counted loop induction variable.
+// The method is declared in node.hpp.
+const Node* Node::is_loop_iv() const {
+  if (this->is_Phi() && !this->as_Phi()->is_copy() &&
+      this->as_Phi()->region()->is_CountedLoop() &&
+      this->as_Phi()->region()->as_CountedLoop()->phi() == this) {
+    return this;
+  } else {
+    return NULL;
+  }
+}
+
+//=============================================================================
+//------------------------------dump_spec--------------------------------------
+// Dump special per-node info
+#ifndef PRODUCT
+void LoopNode::dump_spec(outputStream *st) const {
+  if( is_inner_loop () ) st->print( "inner " );
+  if( is_partial_peel_loop () ) st->print( "partial_peel " );
+  if( partial_peel_has_failed () ) st->print( "partial_peel_failed " );
+}
+#endif
+
+//------------------------------get_early_ctrl---------------------------------
+// Compute earliest legal control
+Node *PhaseIdealLoop::get_early_ctrl( Node *n ) {
+  assert( !n->is_Phi() && !n->is_CFG(), "this code only handles data nodes" );
+  uint i;
+  Node *early;
+  if( n->in(0) ) {
+    early = n->in(0);
+    if( !early->is_CFG() ) // Might be a non-CFG multi-def
+      early = get_ctrl(early);        // So treat input as a straight data input
+    i = 1;
+  } else {
+    early = get_ctrl(n->in(1));
+    i = 2;
+  }
+  uint e_d = dom_depth(early);
+  assert( early, "" );
+  for( ; i < n->req(); i++ ) {
+    Node *cin = get_ctrl(n->in(i));
+    assert( cin, "" );
+    // Keep deepest dominator depth
+    uint c_d = dom_depth(cin);
+    if( c_d > e_d ) {           // Deeper guy?
+      early = cin;              // Keep deepest found so far
+      e_d = c_d;
+    } else if( c_d == e_d &&    // Same depth?
+               early != cin ) { // If not equal, must use slower algorithm
+      // If same depth but not equal, one _must_ dominate the other
+      // and we want the deeper (i.e., dominated) guy.
+      Node *n1 = early;
+      Node *n2 = cin;
+      while( 1 ) {
+        n1 = idom(n1);          // Walk up until break cycle
+        n2 = idom(n2);
+        if( n1 == cin ||        // Walked early up to cin
+            dom_depth(n2) < c_d )
+          break;                // early is deeper; keep him
+        if( n2 == early ||      // Walked cin up to early
+            dom_depth(n1) < c_d ) {
+          early = cin;          // cin is deeper; keep him
+          break;
+        }
+      }
+      e_d = dom_depth(early);   // Reset depth register cache
+    }
+  }
+
+  // Return earliest legal location
+  assert(early == find_non_split_ctrl(early), "unexpected early control");
+
+  return early;
+}
+
+//------------------------------set_early_ctrl---------------------------------
+// Set earliest legal control
+void PhaseIdealLoop::set_early_ctrl( Node *n ) {
+  Node *early = get_early_ctrl(n);
+
+  // Record earliest legal location
+  set_ctrl(n, early);
+}
+
+//------------------------------set_subtree_ctrl-------------------------------
+// set missing _ctrl entries on new nodes
+void PhaseIdealLoop::set_subtree_ctrl( Node *n ) {
+  // Already set?  Get out.
+  if( _nodes[n->_idx] ) return;
+  // Recursively set _nodes array to indicate where the Node goes
+  uint i;
+  for( i = 0; i < n->req(); ++i ) {
+    Node *m = n->in(i);
+    if( m && m != C->root() )
+      set_subtree_ctrl( m );
+  }
+
+  // Fixup self
+  set_early_ctrl( n );
+}
+
+//------------------------------is_counted_loop--------------------------------
+Node *PhaseIdealLoop::is_counted_loop( Node *x, IdealLoopTree *loop ) {
+  PhaseGVN *gvn = &_igvn;
+
+  // Counted loop head must be a good RegionNode with only 3 not NULL
+  // control input edges: Self, Entry, LoopBack.
+  if ( x->in(LoopNode::Self) == NULL || x->req() != 3 )
+    return NULL;
+
+  Node *init_control = x->in(LoopNode::EntryControl);
+  Node *back_control = x->in(LoopNode::LoopBackControl);
+  if( init_control == NULL || back_control == NULL )    // Partially dead
+    return NULL;
+  // Must also check for TOP when looking for a dead loop
+  if( init_control->is_top() || back_control->is_top() )
+    return NULL;
+
+  // Allow funny placement of Safepoint
+  if( back_control->Opcode() == Op_SafePoint )
+    back_control = back_control->in(TypeFunc::Control);
+
+  // Controlling test for loop
+  Node *iftrue = back_control;
+  uint iftrue_op = iftrue->Opcode();
+  if( iftrue_op != Op_IfTrue &&
+      iftrue_op != Op_IfFalse )
+    // I have a weird back-control.  Probably the loop-exit test is in
+    // the middle of the loop and I am looking at some trailing control-flow
+    // merge point.  To fix this I would have to partially peel the loop.
+    return NULL; // Obscure back-control
+
+  // Get boolean guarding loop-back test
+  Node *iff = iftrue->in(0);
+  if( get_loop(iff) != loop || !iff->in(1)->is_Bool() ) return NULL;
+  BoolNode *test = iff->in(1)->as_Bool();
+  BoolTest::mask bt = test->_test._test;
+  float cl_prob = iff->as_If()->_prob;
+  if( iftrue_op == Op_IfFalse ) {
+    bt = BoolTest(bt).negate();
+    cl_prob = 1.0 - cl_prob;
+  }
+  // Get backedge compare
+  Node *cmp = test->in(1);
+  int cmp_op = cmp->Opcode();
+  if( cmp_op != Op_CmpI )
+    return NULL;                // Avoid pointer & float compares
+
+  // Find the trip-counter increment & limit.  Limit must be loop invariant.
+  Node *incr  = cmp->in(1);
+  Node *limit = cmp->in(2);
+
+  // ---------
+  // need 'loop()' test to tell if limit is loop invariant
+  // ---------
+
+  if( !is_member( loop, get_ctrl(incr) ) ) { // Swapped trip counter and limit?
+    Node *tmp = incr;           // Then reverse order into the CmpI
+    incr = limit;
+    limit = tmp;
+    bt = BoolTest(bt).commute(); // And commute the exit test
+  }
+  if( is_member( loop, get_ctrl(limit) ) ) // Limit must loop-invariant
+    return NULL;
+
+  // Trip-counter increment must be commutative & associative.
+  uint incr_op = incr->Opcode();
+  if( incr_op == Op_Phi && incr->req() == 3 ) {
+    incr = incr->in(2);         // Assume incr is on backedge of Phi
+    incr_op = incr->Opcode();
+  }
+  Node* trunc1 = NULL;
+  Node* trunc2 = NULL;
+  const TypeInt* iv_trunc_t = NULL;
+  if (!(incr = CountedLoopNode::match_incr_with_optional_truncation(incr, &trunc1, &trunc2, &iv_trunc_t))) {
+    return NULL; // Funny increment opcode
+  }
+
+  // Get merge point
+  Node *xphi = incr->in(1);
+  Node *stride = incr->in(2);
+  if( !stride->is_Con() ) {     // Oops, swap these
+    if( !xphi->is_Con() )       // Is the other guy a constant?
+      return NULL;              // Nope, unknown stride, bail out
+    Node *tmp = xphi;           // 'incr' is commutative, so ok to swap
+    xphi = stride;
+    stride = tmp;
+  }
+  //if( loop(xphi) != l) return NULL;// Merge point is in inner loop??
+  if( !xphi->is_Phi() ) return NULL; // Too much math on the trip counter
+  PhiNode *phi = xphi->as_Phi();
+
+  // Stride must be constant
+  const Type *stride_t = stride->bottom_type();
+  int stride_con = stride_t->is_int()->get_con();
+  assert( stride_con, "missed some peephole opt" );
+
+  // Phi must be of loop header; backedge must wrap to increment
+  if( phi->region() != x ) return NULL;
+  if( trunc1 == NULL && phi->in(LoopNode::LoopBackControl) != incr ||
+      trunc1 != NULL && phi->in(LoopNode::LoopBackControl) != trunc1 ) {
+    return NULL;
+  }
+  Node *init_trip = phi->in(LoopNode::EntryControl);
+  //if (!init_trip->is_Con()) return NULL; // avoid rolling over MAXINT/MININT
+
+  // If iv trunc type is smaller than int, check for possible wrap.
+  if (!TypeInt::INT->higher_equal(iv_trunc_t)) {
+    assert(trunc1 != NULL, "must have found some truncation");
+
+    // Get a better type for the phi (filtered thru if's)
+    const TypeInt* phi_ft = filtered_type(phi);
+
+    // Can iv take on a value that will wrap?
+    //
+    // Ensure iv's limit is not within "stride" of the wrap value.
+    //
+    // Example for "short" type
+    //    Truncation ensures value is in the range -32768..32767 (iv_trunc_t)
+    //    If the stride is +10, then the last value of the induction
+    //    variable before the increment (phi_ft->_hi) must be
+    //    <= 32767 - 10 and (phi_ft->_lo) must be >= -32768 to
+    //    ensure no truncation occurs after the increment.
+
+    if (stride_con > 0) {
+      if (iv_trunc_t->_hi - phi_ft->_hi < stride_con ||
+          iv_trunc_t->_lo > phi_ft->_lo) {
+        return NULL;  // truncation may occur
+      }
+    } else if (stride_con < 0) {
+      if (iv_trunc_t->_lo - phi_ft->_lo > stride_con ||
+          iv_trunc_t->_hi < phi_ft->_hi) {
+        return NULL;  // truncation may occur
+      }
+    }
+    // No possibility of wrap so truncation can be discarded
+    // Promote iv type to Int
+  } else {
+    assert(trunc1 == NULL && trunc2 == NULL, "no truncation for int");
+  }
+
+  // =================================================
+  // ---- SUCCESS!   Found A Trip-Counted Loop!  -----
+  //
+  // Canonicalize the condition on the test.  If we can exactly determine
+  // the trip-counter exit value, then set limit to that value and use
+  // a '!=' test.  Otherwise use conditon '<' for count-up loops and
+  // '>' for count-down loops.  If the condition is inverted and we will
+  // be rolling through MININT to MAXINT, then bail out.
+
+  C->print_method("Before CountedLoop", 3);
+
+  // Check for SafePoint on backedge and remove
+  Node *sfpt = x->in(LoopNode::LoopBackControl);
+  if( sfpt->Opcode() == Op_SafePoint && is_deleteable_safept(sfpt)) {
+    lazy_replace( sfpt, iftrue );
+    loop->_tail = iftrue;
+  }
+
+
+  // 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 adusting the limit.
+  if( cmp->in(1) == phi || cmp->in(2) == phi )
+    limit = gvn->transform(new (C, 3) AddINode(limit,stride));
+
+  // trip-count for +-tive stride should be: (limit - init_trip + stride - 1)/stride.
+  // Final value for iterator should be: trip_count * stride + init_trip.
+  const Type *limit_t = limit->bottom_type();
+  const Type *init_t = init_trip->bottom_type();
+  Node *one_p = gvn->intcon( 1);
+  Node *one_m = gvn->intcon(-1);
+
+  Node *trip_count = NULL;
+  Node *hook = new (C, 6) Node(6);
+  switch( bt ) {
+  case BoolTest::eq:
+    return NULL;                // Bail out, but this loop trips at most twice!
+  case BoolTest::ne:            // Ahh, the case we desire
+    if( stride_con == 1 )
+      trip_count = gvn->transform(new (C, 3) SubINode(limit,init_trip));
+    else if( stride_con == -1 )
+      trip_count = gvn->transform(new (C, 3) SubINode(init_trip,limit));
+    else
+      return NULL;              // Odd stride; must prove we hit limit exactly
+    set_subtree_ctrl( trip_count );
+    //_loop.map(trip_count->_idx,loop(limit));
+    break;
+  case BoolTest::le:            // Maybe convert to '<' case
+    limit = gvn->transform(new (C, 3) AddINode(limit,one_p));
+    set_subtree_ctrl( limit );
+    hook->init_req(4, limit);
+
+    bt = BoolTest::lt;
+    // Make the new limit be in the same loop nest as the old limit
+    //_loop.map(limit->_idx,limit_loop);
+    // Fall into next case
+  case BoolTest::lt: {          // Maybe convert to '!=' case
+    if( stride_con < 0 ) return NULL; // Count down loop rolls through MAXINT
+    Node *range = gvn->transform(new (C, 3) SubINode(limit,init_trip));
+    set_subtree_ctrl( range );
+    hook->init_req(0, range);
+
+    Node *bias  = gvn->transform(new (C, 3) AddINode(range,stride));
+    set_subtree_ctrl( bias );
+    hook->init_req(1, bias);
+
+    Node *bias1 = gvn->transform(new (C, 3) AddINode(bias,one_m));
+    set_subtree_ctrl( bias1 );
+    hook->init_req(2, bias1);
+
+    trip_count  = gvn->transform(new (C, 3) DivINode(0,bias1,stride));
+    set_subtree_ctrl( trip_count );
+    hook->init_req(3, trip_count);
+    break;
+  }
+
+  case BoolTest::ge:            // Maybe convert to '>' case
+    limit = gvn->transform(new (C, 3) AddINode(limit,one_m));
+    set_subtree_ctrl( limit );
+    hook->init_req(4 ,limit);
+
+    bt = BoolTest::gt;
+    // Make the new limit be in the same loop nest as the old limit
+    //_loop.map(limit->_idx,limit_loop);
+    // Fall into next case
+  case BoolTest::gt: {          // Maybe convert to '!=' case
+    if( stride_con > 0 ) return NULL; // count up loop rolls through MININT
+    Node *range = gvn->transform(new (C, 3) SubINode(limit,init_trip));
+    set_subtree_ctrl( range );
+    hook->init_req(0, range);
+
+    Node *bias  = gvn->transform(new (C, 3) AddINode(range,stride));
+    set_subtree_ctrl( bias );
+    hook->init_req(1, bias);
+
+    Node *bias1 = gvn->transform(new (C, 3) AddINode(bias,one_p));
+    set_subtree_ctrl( bias1 );
+    hook->init_req(2, bias1);
+
+    trip_count  = gvn->transform(new (C, 3) DivINode(0,bias1,stride));
+    set_subtree_ctrl( trip_count );
+    hook->init_req(3, trip_count);
+    break;
+  }
+  }
+
+  Node *span = gvn->transform(new (C, 3) MulINode(trip_count,stride));
+  set_subtree_ctrl( span );
+  hook->init_req(5, span);
+
+  limit = gvn->transform(new (C, 3) AddINode(span,init_trip));
+  set_subtree_ctrl( limit );
+
+  // Build a canonical trip test.
+  // Clone code, as old values may be in use.
+  incr = incr->clone();
+  incr->set_req(1,phi);
+  incr->set_req(2,stride);
+  incr = _igvn.register_new_node_with_optimizer(incr);
+  set_early_ctrl( incr );
+  _igvn.hash_delete(phi);
+  phi->set_req_X( LoopNode::LoopBackControl, incr, &_igvn );
+
+  // If phi type is more restrictive than Int, raise to
+  // Int to prevent (almost) infinite recursion in igvn
+  // which can only handle integer types for constants or minint..maxint.
+  if (!TypeInt::INT->higher_equal(phi->bottom_type())) {
+    Node* nphi = PhiNode::make(phi->in(0), phi->in(LoopNode::EntryControl), TypeInt::INT);
+    nphi->set_req(LoopNode::LoopBackControl, phi->in(LoopNode::LoopBackControl));
+    nphi = _igvn.register_new_node_with_optimizer(nphi);
+    set_ctrl(nphi, get_ctrl(phi));
+    _igvn.subsume_node(phi, nphi);
+    phi = nphi->as_Phi();
+  }
+  cmp = cmp->clone();
+  cmp->set_req(1,incr);
+  cmp->set_req(2,limit);
+  cmp = _igvn.register_new_node_with_optimizer(cmp);
+  set_ctrl(cmp, iff->in(0));
+
+  Node *tmp = test->clone();
+  assert( tmp->is_Bool(), "" );
+  test = (BoolNode*)tmp;
+  (*(BoolTest*)&test->_test)._test = bt; //BoolTest::ne;
+  test->set_req(1,cmp);
+  _igvn.register_new_node_with_optimizer(test);
+  set_ctrl(test, iff->in(0));
+  // If the exit test is dead, STOP!
+  if( test == NULL ) return NULL;
+  _igvn.hash_delete(iff);
+  iff->set_req_X( 1, test, &_igvn );
+
+  // Replace the old IfNode with a new LoopEndNode
+  Node *lex = _igvn.register_new_node_with_optimizer(new (C, 2) CountedLoopEndNode( iff->in(0), iff->in(1), cl_prob, iff->as_If()->_fcnt ));
+  IfNode *le = lex->as_If();
+  uint dd = dom_depth(iff);
+  set_idom(le, le->in(0), dd); // Update dominance for loop exit
+  set_loop(le, loop);
+
+  // Get the loop-exit control
+  Node *if_f = iff->as_If()->proj_out(!(iftrue_op == Op_IfTrue));
+
+  // Need to swap loop-exit and loop-back control?
+  if( iftrue_op == Op_IfFalse ) {
+    Node *ift2=_igvn.register_new_node_with_optimizer(new (C, 1) IfTrueNode (le));
+    Node *iff2=_igvn.register_new_node_with_optimizer(new (C, 1) IfFalseNode(le));
+
+    loop->_tail = back_control = ift2;
+    set_loop(ift2, loop);
+    set_loop(iff2, get_loop(if_f));
+
+    // Lazy update of 'get_ctrl' mechanism.
+    lazy_replace_proj( if_f  , iff2 );
+    lazy_replace_proj( iftrue, ift2 );
+
+    // Swap names
+    if_f   = iff2;
+    iftrue = ift2;
+  } else {
+    _igvn.hash_delete(if_f  );
+    _igvn.hash_delete(iftrue);
+    if_f  ->set_req_X( 0, le, &_igvn );
+    iftrue->set_req_X( 0, le, &_igvn );
+  }
+
+  set_idom(iftrue, le, dd+1);
+  set_idom(if_f,   le, dd+1);
+
+  // Now setup a new CountedLoopNode to replace the existing LoopNode
+  CountedLoopNode *l = new (C, 3) CountedLoopNode(init_control, back_control);
+  // The following assert is approximately true, and defines the intention
+  // of can_be_counted_loop.  It fails, however, because phase->type
+  // is not yet initialized for this loop and its parts.
+  //assert(l->can_be_counted_loop(this), "sanity");
+  _igvn.register_new_node_with_optimizer(l);
+  set_loop(l, loop);
+  loop->_head = l;
+  // Fix all data nodes placed at the old loop head.
+  // Uses the lazy-update mechanism of 'get_ctrl'.
+  lazy_replace( x, l );
+  set_idom(l, init_control, dom_depth(x));
+
+  // Check for immediately preceeding SafePoint and remove
+  Node *sfpt2 = le->in(0);
+  if( sfpt2->Opcode() == Op_SafePoint && is_deleteable_safept(sfpt2))
+    lazy_replace( sfpt2, sfpt2->in(TypeFunc::Control));
+
+  // Free up intermediate goo
+  _igvn.remove_dead_node(hook);
+
+  C->print_method("After CountedLoop", 3);
+
+  // Return trip counter
+  return trip_count;
+}
+
+
+//------------------------------Ideal------------------------------------------
+// Return a node which is more "ideal" than the current node.
+// Attempt to convert into a counted-loop.
+Node *LoopNode::Ideal(PhaseGVN *phase, bool can_reshape) {
+  if (!can_be_counted_loop(phase)) {
+    phase->C->set_major_progress();
+  }
+  return RegionNode::Ideal(phase, can_reshape);
+}
+
+
+//=============================================================================
+//------------------------------Ideal------------------------------------------
+// Return a node which is more "ideal" than the current node.
+// Attempt to convert into a counted-loop.
+Node *CountedLoopNode::Ideal(PhaseGVN *phase, bool can_reshape) {
+  return RegionNode::Ideal(phase, can_reshape);
+}
+
+//------------------------------dump_spec--------------------------------------
+// Dump special per-node info
+#ifndef PRODUCT
+void CountedLoopNode::dump_spec(outputStream *st) const {
+  LoopNode::dump_spec(st);
+  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 );
+}
+#endif
+
+//=============================================================================
+int CountedLoopEndNode::stride_con() const {
+  return stride()->bottom_type()->is_int()->get_con();
+}
+
+
+//----------------------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
+// Return NULL for failure. Success returns the increment node.
+Node* CountedLoopNode::match_incr_with_optional_truncation(
+                      Node* expr, Node** trunc1, Node** trunc2, const TypeInt** trunc_type) {
+  // Quick cutouts:
+  if (expr == NULL || expr->req() != 3)  return false;
+
+  Node *t1 = NULL;
+  Node *t2 = NULL;
+  const TypeInt* trunc_t = TypeInt::INT;
+  Node* n1 = expr;
+  int   n1op = n1->Opcode();
+
+  // Try to strip (n1 & M) or (n1 << N >> N) from n1.
+  if (n1op == Op_AndI &&
+      n1->in(2)->is_Con() &&
+      n1->in(2)->bottom_type()->is_int()->get_con() == 0x7fff) {
+    // %%% This check should match any mask of 2**K-1.
+    t1 = n1;
+    n1 = t1->in(1);
+    n1op = n1->Opcode();
+    trunc_t = TypeInt::CHAR;
+  } else if (n1op == Op_RShiftI &&
+             n1->in(1) != NULL &&
+             n1->in(1)->Opcode() == Op_LShiftI &&
+             n1->in(2) == n1->in(1)->in(2) &&
+             n1->in(2)->is_Con()) {
+    jint shift = n1->in(2)->bottom_type()->is_int()->get_con();
+    // %%% This check should match any shift in [1..31].
+    if (shift == 16 || shift == 8) {
+      t1 = n1;
+      t2 = t1->in(1);
+      n1 = t2->in(1);
+      n1op = n1->Opcode();
+      if (shift == 16) {
+        trunc_t = TypeInt::SHORT;
+      } else if (shift == 8) {
+        trunc_t = TypeInt::BYTE;
+      }
+    }
+  }
+
+  // If (maybe after stripping) it is an AddI, we won:
+  if (n1op == Op_AddI) {
+    *trunc1 = t1;
+    *trunc2 = t2;
+    *trunc_type = trunc_t;
+    return n1;
+  }
+
+  // failed
+  return NULL;
+}
+
+
+//------------------------------filtered_type--------------------------------
+// Return a type based on condition control flow
+// A successful return will be a type that is restricted due
+// to a series of dominating if-tests, such as:
+//    if (i < 10) {
+//       if (i > 0) {
+//          here: "i" type is [1..10)
+//       }
+//    }
+// or a control flow merge
+//    if (i < 10) {
+//       do {
+//          phi( , ) -- at top of loop type is [min_int..10)
+//         i = ?
+//       } while ( i < 10)
+//
+const TypeInt* PhaseIdealLoop::filtered_type( Node *n, Node* n_ctrl) {
+  assert(n && n->bottom_type()->is_int(), "must be int");
+  const TypeInt* filtered_t = NULL;
+  if (!n->is_Phi()) {
+    assert(n_ctrl != NULL || n_ctrl == C->top(), "valid control");
+    filtered_t = filtered_type_from_dominators(n, n_ctrl);
+
+  } else {
+    Node* phi    = n->as_Phi();
+    Node* region = phi->in(0);
+    assert(n_ctrl == NULL || n_ctrl == region, "ctrl parameter must be region");
+    if (region && region != C->top()) {
+      for (uint i = 1; i < phi->req(); i++) {
+        Node* val   = phi->in(i);
+        Node* use_c = region->in(i);
+        const TypeInt* val_t = filtered_type_from_dominators(val, use_c);
+        if (val_t != NULL) {
+          if (filtered_t == NULL) {
+            filtered_t = val_t;
+          } else {
+            filtered_t = filtered_t->meet(val_t)->is_int();
+          }
+        }
+      }
+    }
+  }
+  const TypeInt* n_t = _igvn.type(n)->is_int();
+  if (filtered_t != NULL) {
+    n_t = n_t->join(filtered_t)->is_int();
+  }
+  return n_t;
+}
+
+
+//------------------------------filtered_type_from_dominators--------------------------------
+// Return a possibly more restrictive type for val based on condition control flow of dominators
+const TypeInt* PhaseIdealLoop::filtered_type_from_dominators( Node* val, Node *use_ctrl) {
+  if (val->is_Con()) {
+     return val->bottom_type()->is_int();
+  }
+  uint if_limit = 10; // Max number of dominating if's visited
+  const TypeInt* rtn_t = NULL;
+
+  if (use_ctrl && use_ctrl != C->top()) {
+    Node* val_ctrl = get_ctrl(val);
+    uint val_dom_depth = dom_depth(val_ctrl);
+    Node* pred = use_ctrl;
+    uint if_cnt = 0;
+    while (if_cnt < if_limit) {
+      if ((pred->Opcode() == Op_IfTrue || pred->Opcode() == Op_IfFalse)) {
+        if_cnt++;
+        const TypeInt* if_t = filtered_type_at_if(val, pred);
+        if (if_t != NULL) {
+          if (rtn_t == NULL) {
+            rtn_t = if_t;
+          } else {
+            rtn_t = rtn_t->join(if_t)->is_int();
+          }
+        }
+      }
+      pred = idom(pred);
+      if (pred == NULL || pred == C->top()) {
+        break;
+      }
+      // Stop if going beyond definition block of val
+      if (dom_depth(pred) < val_dom_depth) {
+        break;
+      }
+    }
+  }
+  return rtn_t;
+}
+
+
+//------------------------------filtered_type_at_if--------------------------------
+// Return a possibly more restrictive type for val based on condition control flow for an if
+const TypeInt* PhaseIdealLoop::filtered_type_at_if( Node* val, Node *if_proj) {
+  assert(if_proj &&
+         (if_proj->Opcode() == Op_IfTrue || if_proj->Opcode() == Op_IfFalse), "expecting an if projection");
+  if (if_proj->in(0) && if_proj->in(0)->is_If()) {
+    IfNode* iff = if_proj->in(0)->as_If();
+    if (iff->in(1) && iff->in(1)->is_Bool()) {
+      BoolNode* bol = iff->in(1)->as_Bool();
+      if (bol->in(1) && bol->in(1)->is_Cmp()) {
+        const CmpNode* cmp  = bol->in(1)->as_Cmp();
+        if (cmp->in(1) == val) {
+          const TypeInt* cmp2_t = _igvn.type(cmp->in(2))->isa_int();
+          if (cmp2_t != NULL) {
+            jint lo = cmp2_t->_lo;
+            jint hi = cmp2_t->_hi;
+            BoolTest::mask msk = if_proj->Opcode() == Op_IfTrue ? bol->_test._test : bol->_test.negate();
+            switch (msk) {
+            case BoolTest::ne:
+              // Can't refine type
+              return NULL;
+            case BoolTest::eq:
+              return cmp2_t;
+            case BoolTest::lt:
+              lo = TypeInt::INT->_lo;
+              if (hi - 1 < hi) {
+                hi = hi - 1;
+              }
+              break;
+            case BoolTest::le:
+              lo = TypeInt::INT->_lo;
+              break;
+            case BoolTest::gt:
+              if (lo + 1 > lo) {
+                lo = lo + 1;
+              }
+              hi = TypeInt::INT->_hi;
+              break;
+            case BoolTest::ge:
+              // lo unchanged
+              hi = TypeInt::INT->_hi;
+              break;
+            }
+            const TypeInt* rtn_t = TypeInt::make(lo, hi, cmp2_t->_widen);
+            return rtn_t;
+          }
+        }
+      }
+    }
+  }
+  return NULL;
+}
+
+//------------------------------dump_spec--------------------------------------
+// Dump special per-node info
+#ifndef PRODUCT
+void CountedLoopEndNode::dump_spec(outputStream *st) const {
+  if( in(TestValue)->is_Bool() ) {
+    BoolTest bt( test_trip()); // Added this for g++.
+
+    st->print("[");
+    bt.dump_on(st);
+    st->print("]");
+  }
+  st->print(" ");
+  IfNode::dump_spec(st);
+}
+#endif
+
+//=============================================================================
+//------------------------------is_member--------------------------------------
+// Is 'l' a member of 'this'?
+int IdealLoopTree::is_member( const IdealLoopTree *l ) const {
+  while( l->_nest > _nest ) l = l->_parent;
+  return l == this;
+}
+
+//------------------------------set_nest---------------------------------------
+// Set loop tree nesting depth.  Accumulate _has_call bits.
+int IdealLoopTree::set_nest( uint depth ) {
+  _nest = depth;
+  int bits = _has_call;
+  if( _child ) bits |= _child->set_nest(depth+1);
+  if( bits ) _has_call = 1;
+  if( _next  ) bits |= _next ->set_nest(depth  );
+  return bits;
+}
+
+//------------------------------split_fall_in----------------------------------
+// Split out multiple fall-in edges from the loop header.  Move them to a
+// private RegionNode before the loop.  This becomes the loop landing pad.
+void IdealLoopTree::split_fall_in( PhaseIdealLoop *phase, int fall_in_cnt ) {
+  PhaseIterGVN &igvn = phase->_igvn;
+  uint i;
+
+  // Make a new RegionNode to be the landing pad.
+  Node *landing_pad = new (phase->C, fall_in_cnt+1) RegionNode( fall_in_cnt+1 );
+  phase->set_loop(landing_pad,_parent);
+  // Gather all the fall-in control paths into the landing pad
+  uint icnt = fall_in_cnt;
+  uint oreq = _head->req();
+  for( i = oreq-1; i>0; i-- )
+    if( !phase->is_member( this, _head->in(i) ) )
+      landing_pad->set_req(icnt--,_head->in(i));
+
+  // Peel off PhiNode edges as well
+  for (DUIterator_Fast jmax, j = _head->fast_outs(jmax); j < jmax; j++) {
+    Node *oj = _head->fast_out(j);
+    if( oj->is_Phi() ) {
+      PhiNode* old_phi = oj->as_Phi();
+      assert( old_phi->region() == _head, "" );
+      igvn.hash_delete(old_phi);   // Yank from hash before hacking edges
+      Node *p = PhiNode::make_blank(landing_pad, old_phi);
+      uint icnt = fall_in_cnt;
+      for( i = oreq-1; i>0; i-- ) {
+        if( !phase->is_member( this, _head->in(i) ) ) {
+          p->init_req(icnt--, old_phi->in(i));
+          // Go ahead and clean out old edges from old phi
+          old_phi->del_req(i);
+        }
+      }
+      // Search for CSE's here, because ZKM.jar does a lot of
+      // loop hackery and we need to be a little incremental
+      // with the CSE to avoid O(N^2) node blow-up.
+      Node *p2 = igvn.hash_find_insert(p); // Look for a CSE
+      if( p2 ) {                // Found CSE
+        p->destruct();          // Recover useless new node
+        p = p2;                 // Use old node
+      } else {
+        igvn.register_new_node_with_optimizer(p, old_phi);
+      }
+      // Make old Phi refer to new Phi.
+      old_phi->add_req(p);
+      // Check for the special case of making the old phi useless and
+      // disappear it.  In JavaGrande I have a case where this useless
+      // Phi is the loop limit and prevents recognizing a CountedLoop
+      // which in turn prevents removing an empty loop.
+      Node *id_old_phi = old_phi->Identity( &igvn );
+      if( id_old_phi != old_phi ) { // Found a simple identity?
+        // Note that I cannot call 'subsume_node' here, because
+        // that will yank the edge from old_phi to the Region and
+        // I'm mid-iteration over the Region's uses.
+        for (DUIterator_Last imin, i = old_phi->last_outs(imin); i >= imin; ) {
+          Node* use = old_phi->last_out(i);
+          igvn.hash_delete(use);
+          igvn._worklist.push(use);
+          uint uses_found = 0;
+          for (uint j = 0; j < use->len(); j++) {
+            if (use->in(j) == old_phi) {
+              if (j < use->req()) use->set_req (j, id_old_phi);
+              else                use->set_prec(j, id_old_phi);
+              uses_found++;
+            }
+          }
+          i -= uses_found;    // we deleted 1 or more copies of this edge
+        }
+      }
+      igvn._worklist.push(old_phi);
+    }
+  }
+  // Finally clean out the fall-in edges from the RegionNode
+  for( i = oreq-1; i>0; i-- ) {
+    if( !phase->is_member( this, _head->in(i) ) ) {
+      _head->del_req(i);
+    }
+  }
+  // Transform landing pad
+  igvn.register_new_node_with_optimizer(landing_pad, _head);
+  // Insert landing pad into the header
+  _head->add_req(landing_pad);
+}
+
+//------------------------------split_outer_loop-------------------------------
+// Split out the outermost loop from this shared header.
+void IdealLoopTree::split_outer_loop( PhaseIdealLoop *phase ) {
+  PhaseIterGVN &igvn = phase->_igvn;
+
+  // Find index of outermost loop; it should also be my tail.
+  uint outer_idx = 1;
+  while( _head->in(outer_idx) != _tail ) outer_idx++;
+
+  // Make a LoopNode for the outermost loop.
+  Node *ctl = _head->in(LoopNode::EntryControl);
+  Node *outer = new (phase->C, 3) LoopNode( ctl, _head->in(outer_idx) );
+  outer = igvn.register_new_node_with_optimizer(outer, _head);
+  phase->set_created_loop_node();
+  // Outermost loop falls into '_head' loop
+  _head->set_req(LoopNode::EntryControl, outer);
+  _head->del_req(outer_idx);
+  // Split all the Phis up between '_head' loop and 'outer' loop.
+  for (DUIterator_Fast jmax, j = _head->fast_outs(jmax); j < jmax; j++) {
+    Node *out = _head->fast_out(j);
+    if( out->is_Phi() ) {
+      PhiNode *old_phi = out->as_Phi();
+      assert( old_phi->region() == _head, "" );
+      Node *phi = PhiNode::make_blank(outer, old_phi);
+      phi->init_req(LoopNode::EntryControl,    old_phi->in(LoopNode::EntryControl));
+      phi->init_req(LoopNode::LoopBackControl, old_phi->in(outer_idx));
+      phi = igvn.register_new_node_with_optimizer(phi, old_phi);
+      // Make old Phi point to new Phi on the fall-in path
+      igvn.hash_delete(old_phi);
+      old_phi->set_req(LoopNode::EntryControl, phi);
+      old_phi->del_req(outer_idx);
+      igvn._worklist.push(old_phi);
+    }
+  }
+
+  // Use the new loop head instead of the old shared one
+  _head = outer;
+  phase->set_loop(_head, this);
+}
+
+//------------------------------fix_parent-------------------------------------
+static void fix_parent( IdealLoopTree *loop, IdealLoopTree *parent ) {
+  loop->_parent = parent;
+  if( loop->_child ) fix_parent( loop->_child, loop   );
+  if( loop->_next  ) fix_parent( loop->_next , parent );
+}
+
+//------------------------------estimate_path_freq-----------------------------
+static float estimate_path_freq( Node *n ) {
+  // Try to extract some path frequency info
+  IfNode *iff;
+  for( int i = 0; i < 50; i++ ) { // Skip through a bunch of uncommon tests
+    uint nop = n->Opcode();
+    if( nop == Op_SafePoint ) {   // Skip any safepoint
+      n = n->in(0);
+      continue;
+    }
+    if( nop == Op_CatchProj ) {   // Get count from a prior call
+      // Assume call does not always throw exceptions: means the call-site
+      // count is also the frequency of the fall-through path.
+      assert( n->is_CatchProj(), "" );
+      if( ((CatchProjNode*)n)->_con != CatchProjNode::fall_through_index )
+        return 0.0f;            // Assume call exception path is rare
+      Node *call = n->in(0)->in(0)->in(0);
+      assert( call->is_Call(), "expect a call here" );
+      const JVMState *jvms = ((CallNode*)call)->jvms();
+      ciMethodData* methodData = jvms->method()->method_data();
+      if (!methodData->is_mature())  return 0.0f; // No call-site data
+      ciProfileData* data = methodData->bci_to_data(jvms->bci());
+      if ((data == NULL) || !data->is_CounterData()) {
+        // no call profile available, try call's control input
+        n = n->in(0);
+        continue;
+      }
+      return data->as_CounterData()->count()/FreqCountInvocations;
+    }
+    // See if there's a gating IF test
+    Node *n_c = n->in(0);
+    if( !n_c->is_If() ) break;       // No estimate available
+    iff = n_c->as_If();
+    if( iff->_fcnt != COUNT_UNKNOWN )   // Have a valid count?
+      // Compute how much count comes on this path
+      return ((nop == Op_IfTrue) ? iff->_prob : 1.0f - iff->_prob) * iff->_fcnt;
+    // Have no count info.  Skip dull uncommon-trap like branches.
+    if( (nop == Op_IfTrue  && iff->_prob < PROB_LIKELY_MAG(5)) ||
+        (nop == Op_IfFalse && iff->_prob > PROB_UNLIKELY_MAG(5)) )
+      break;
+    // Skip through never-taken branch; look for a real loop exit.
+    n = iff->in(0);
+  }
+  return 0.0f;                  // No estimate available
+}
+
+//------------------------------merge_many_backedges---------------------------
+// Merge all the backedges from the shared header into a private Region.
+// Feed that region as the one backedge to this loop.
+void IdealLoopTree::merge_many_backedges( PhaseIdealLoop *phase ) {
+  uint i;
+
+  // Scan for the top 2 hottest backedges
+  float hotcnt = 0.0f;
+  float warmcnt = 0.0f;
+  uint hot_idx = 0;
+  // Loop starts at 2 because slot 1 is the fall-in path
+  for( i = 2; i < _head->req(); i++ ) {
+    float cnt = estimate_path_freq(_head->in(i));
+    if( cnt > hotcnt ) {       // Grab hottest path
+      warmcnt = hotcnt;
+      hotcnt = cnt;
+      hot_idx = i;
+    } else if( cnt > warmcnt ) { // And 2nd hottest path
+      warmcnt = cnt;
+    }
+  }
+
+  // See if the hottest backedge is worthy of being an inner loop
+  // by being much hotter than the next hottest backedge.
+  if( hotcnt <= 0.0001 ||
+      hotcnt < 2.0*warmcnt ) hot_idx = 0;// No hot backedge
+
+  // Peel out the backedges into a private merge point; peel
+  // them all except optionally hot_idx.
+  PhaseIterGVN &igvn = phase->_igvn;
+
+  Node *hot_tail = NULL;
+  // Make a Region for the merge point
+  Node *r = new (phase->C, 1) RegionNode(1);
+  for( i = 2; i < _head->req(); i++ ) {
+    if( i != hot_idx )
+      r->add_req( _head->in(i) );
+    else hot_tail = _head->in(i);
+  }
+  igvn.register_new_node_with_optimizer(r, _head);
+  // Plug region into end of loop _head, followed by hot_tail
+  while( _head->req() > 3 ) _head->del_req( _head->req()-1 );
+  _head->set_req(2, r);
+  if( hot_idx ) _head->add_req(hot_tail);
+
+  // Split all the Phis up between '_head' loop and the Region 'r'
+  for (DUIterator_Fast jmax, j = _head->fast_outs(jmax); j < jmax; j++) {
+    Node *out = _head->fast_out(j);
+    if( out->is_Phi() ) {
+      PhiNode* n = out->as_Phi();
+      igvn.hash_delete(n);      // Delete from hash before hacking edges
+      Node *hot_phi = NULL;
+      Node *phi = new (phase->C, r->req()) PhiNode(r, n->type(), n->adr_type());
+      // Check all inputs for the ones to peel out
+      uint j = 1;
+      for( uint i = 2; i < n->req(); i++ ) {
+        if( i != hot_idx )
+          phi->set_req( j++, n->in(i) );
+        else hot_phi = n->in(i);
+      }
+      // Register the phi but do not transform until whole place transforms
+      igvn.register_new_node_with_optimizer(phi, n);
+      // Add the merge phi to the old Phi
+      while( n->req() > 3 ) n->del_req( n->req()-1 );
+      n->set_req(2, phi);
+      if( hot_idx ) n->add_req(hot_phi);
+    }
+  }
+
+
+  // Insert a new IdealLoopTree inserted below me.  Turn it into a clone
+  // of self loop tree.  Turn self into a loop headed by _head and with
+  // tail being the new merge point.
+  IdealLoopTree *ilt = new IdealLoopTree( phase, _head, _tail );
+  phase->set_loop(_tail,ilt);   // Adjust tail
+  _tail = r;                    // Self's tail is new merge point
+  phase->set_loop(r,this);
+  ilt->_child = _child;         // New guy has my children
+  _child = ilt;                 // Self has new guy as only child
+  ilt->_parent = this;          // new guy has self for parent
+  ilt->_nest = _nest;           // Same nesting depth (for now)
+
+  // Starting with 'ilt', look for child loop trees using the same shared
+  // header.  Flatten these out; they will no longer be loops in the end.
+  IdealLoopTree **pilt = &_child;
+  while( ilt ) {
+    if( ilt->_head == _head ) {
+      uint i;
+      for( i = 2; i < _head->req(); i++ )
+        if( _head->in(i) == ilt->_tail )
+          break;                // Still a loop
+      if( i == _head->req() ) { // No longer a loop
+        // Flatten ilt.  Hang ilt's "_next" list from the end of
+        // ilt's '_child' list.  Move the ilt's _child up to replace ilt.
+        IdealLoopTree **cp = &ilt->_child;
+        while( *cp ) cp = &(*cp)->_next;   // Find end of child list
+        *cp = ilt->_next;       // Hang next list at end of child list
+        *pilt = ilt->_child;    // Move child up to replace ilt
+        ilt->_head = NULL;      // Flag as a loop UNIONED into parent
+        ilt = ilt->_child;      // Repeat using new ilt
+        continue;               // do not advance over ilt->_child
+      }
+      assert( ilt->_tail == hot_tail, "expected to only find the hot inner loop here" );
+      phase->set_loop(_head,ilt);
+    }
+    pilt = &ilt->_child;        // Advance to next
+    ilt = *pilt;
+  }
+
+  if( _child ) fix_parent( _child, this );
+}
+
+//------------------------------beautify_loops---------------------------------
+// Split shared headers and insert loop landing pads.
+// Insert a LoopNode to replace the RegionNode.
+// Return TRUE if loop tree is structurally changed.
+bool IdealLoopTree::beautify_loops( PhaseIdealLoop *phase ) {
+  bool result = false;
+  // Cache parts in locals for easy
+  PhaseIterGVN &igvn = phase->_igvn;
+
+  phase->C->print_method("Before beautify loops", 3);
+
+  igvn.hash_delete(_head);      // Yank from hash before hacking edges
+
+  // Check for multiple fall-in paths.  Peel off a landing pad if need be.
+  int fall_in_cnt = 0;
+  for( uint i = 1; i < _head->req(); i++ )
+    if( !phase->is_member( this, _head->in(i) ) )
+      fall_in_cnt++;
+  assert( fall_in_cnt, "at least 1 fall-in path" );
+  if( fall_in_cnt > 1 )         // Need a loop landing pad to merge fall-ins
+    split_fall_in( phase, fall_in_cnt );
+
+  // Swap inputs to the _head and all Phis to move the fall-in edge to
+  // the left.
+  fall_in_cnt = 1;
+  while( phase->is_member( this, _head->in(fall_in_cnt) ) )
+    fall_in_cnt++;
+  if( fall_in_cnt > 1 ) {
+    // Since I am just swapping inputs I do not need to update def-use info
+    Node *tmp = _head->in(1);
+    _head->set_req( 1, _head->in(fall_in_cnt) );
+    _head->set_req( fall_in_cnt, tmp );
+    // Swap also all Phis
+    for (DUIterator_Fast imax, i = _head->fast_outs(imax); i < imax; i++) {
+      Node* phi = _head->fast_out(i);
+      if( phi->is_Phi() ) {
+        igvn.hash_delete(phi); // Yank from hash before hacking edges
+        tmp = phi->in(1);
+        phi->set_req( 1, phi->in(fall_in_cnt) );
+        phi->set_req( fall_in_cnt, tmp );
+      }
+    }
+  }
+  assert( !phase->is_member( this, _head->in(1) ), "left edge is fall-in" );
+  assert(  phase->is_member( this, _head->in(2) ), "right edge is loop" );
+
+  // If I am a shared header (multiple backedges), peel off the many
+  // backedges into a private merge point and use the merge point as
+  // the one true backedge.
+  if( _head->req() > 3 ) {
+    // Merge the many backedges into a single backedge.
+    merge_many_backedges( phase );
+    result = true;
+  }
+
+  // If I am a shared header (multiple backedges), peel off myself loop.
+  // I better be the outermost loop.
+  if( _head->req() > 3 ) {
+    split_outer_loop( phase );
+    result = true;
+
+  } else if( !_head->is_Loop() && !_irreducible ) {
+    // Make a new LoopNode to replace the old loop head
+    Node *l = new (phase->C, 3) LoopNode( _head->in(1), _head->in(2) );
+    l = igvn.register_new_node_with_optimizer(l, _head);
+    phase->set_created_loop_node();
+    // Go ahead and replace _head
+    phase->_igvn.subsume_node( _head, l );
+    _head = l;
+    phase->set_loop(_head, this);
+    for (DUIterator_Fast imax, i = l->fast_outs(imax); i < imax; i++)
+      phase->_igvn.add_users_to_worklist(l->fast_out(i));
+  }
+
+  phase->C->print_method("After beautify loops", 3);
+
+  // Now recursively beautify nested loops
+  if( _child ) result |= _child->beautify_loops( phase );
+  if( _next  ) result |= _next ->beautify_loops( phase );
+  return result;
+}
+
+//------------------------------allpaths_check_safepts----------------------------
+// Allpaths backwards scan from loop tail, terminating each path at first safepoint
+// encountered.  Helper for check_safepts.
+void IdealLoopTree::allpaths_check_safepts(VectorSet &visited, Node_List &stack) {
+  assert(stack.size() == 0, "empty stack");
+  stack.push(_tail);
+  visited.Clear();
+  visited.set(_tail->_idx);
+  while (stack.size() > 0) {
+    Node* n = stack.pop();
+    if (n->is_Call() && n->as_Call()->guaranteed_safepoint()) {
+      // Terminate this path
+    } else if (n->Opcode() == Op_SafePoint) {
+      if (_phase->get_loop(n) != this) {
+        if (_required_safept == NULL) _required_safept = new Node_List();
+        _required_safept->push(n);  // save the one closest to the tail
+      }
+      // Terminate this path
+    } else {
+      uint start = n->is_Region() ? 1 : 0;
+      uint end   = n->is_Region() && !n->is_Loop() ? n->req() : start + 1;
+      for (uint i = start; i < end; i++) {
+        Node* in = n->in(i);
+        assert(in->is_CFG(), "must be");
+        if (!visited.test_set(in->_idx) && is_member(_phase->get_loop(in))) {
+          stack.push(in);
+        }
+      }
+    }
+  }
+}
+
+//------------------------------check_safepts----------------------------
+// Given dominators, try to find loops with calls that must always be
+// executed (call dominates loop tail).  These loops do not need non-call
+// safepoints (ncsfpt).
+//
+// A complication is that a safepoint in a inner loop may be needed
+// by an outer loop. In the following, the inner loop sees it has a
+// call (block 3) on every path from the head (block 2) to the
+// backedge (arc 3->2).  So it deletes the ncsfpt (non-call safepoint)
+// in block 2, _but_ this leaves the outer loop without a safepoint.
+//
+//          entry  0
+//                 |
+//                 v
+// outer 1,2    +->1
+//              |  |
+//              |  v
+//              |  2<---+  ncsfpt in 2
+//              |_/|\   |
+//                 | v  |
+// inner 2,3      /  3  |  call in 3
+//               /   |  |
+//              v    +--+
+//        exit  4
+//
+//
+// This method creates a list (_required_safept) of ncsfpt nodes that must
+// be protected is created for each loop. When a ncsfpt maybe deleted, it
+// is first looked for in the lists for the outer loops of the current loop.
+//
+// The insights into the problem:
+//  A) counted loops are okay
+//  B) innermost loops are okay (only an inner loop can delete
+//     a ncsfpt needed by an outer loop)
+//  C) a loop is immune from an inner loop deleting a safepoint
+//     if the loop has a call on the idom-path
+//  D) a loop is also immune if it has a ncsfpt (non-call safepoint) on the
+//     idom-path that is not in a nested loop
+//  E) otherwise, an ncsfpt on the idom-path that is nested in an inner
+//     loop needs to be prevented from deletion by an inner loop
+//
+// There are two analyses:
+//  1) The first, and cheaper one, scans the loop body from
+//     tail to head following the idom (immediate dominator)
+//     chain, looking for the cases (C,D,E) above.
+//     Since inner loops are scanned before outer loops, there is summary
+//     information about inner loops.  Inner loops can be skipped over
+//     when the tail of an inner loop is encountered.
+//
+//  2) The second, invoked if the first fails to find a call or ncsfpt on
+//     the idom path (which is rare), scans all predecessor control paths
+//     from the tail to the head, terminating a path when a call or sfpt
+//     is encountered, to find the ncsfpt's that are closest to the tail.
+//
+void IdealLoopTree::check_safepts(VectorSet &visited, Node_List &stack) {
+  // Bottom up traversal
+  IdealLoopTree* ch = _child;
+  while (ch != NULL) {
+    ch->check_safepts(visited, stack);
+    ch = ch->_next;
+  }
+
+  if (!_head->is_CountedLoop() && !_has_sfpt && _parent != NULL && !_irreducible) {
+    bool  has_call         = false; // call on dom-path
+    bool  has_local_ncsfpt = false; // ncsfpt on dom-path at this loop depth
+    Node* nonlocal_ncsfpt  = NULL;  // ncsfpt on dom-path at a deeper depth
+    // Scan the dom-path nodes from tail to head
+    for (Node* n = tail(); n != _head; n = _phase->idom(n)) {
+      if (n->is_Call() && n->as_Call()->guaranteed_safepoint()) {
+        has_call = true;
+        _has_sfpt = 1;          // Then no need for a safept!
+        break;
+      } else if (n->Opcode() == Op_SafePoint) {
+        if (_phase->get_loop(n) == this) {
+          has_local_ncsfpt = true;
+          break;
+        }
+        if (nonlocal_ncsfpt == NULL) {
+          nonlocal_ncsfpt = n; // save the one closest to the tail
+        }
+      } else {
+        IdealLoopTree* nlpt = _phase->get_loop(n);
+        if (this != nlpt) {
+          // If at an inner loop tail, see if the inner loop has already
+          // recorded seeing a call on the dom-path (and stop.)  If not,
+          // jump to the head of the inner loop.
+          assert(is_member(nlpt), "nested loop");
+          Node* tail = nlpt->_tail;
+          if (tail->in(0)->is_If()) tail = tail->in(0);
+          if (n == tail) {
+            // If inner loop has call on dom-path, so does outer loop
+            if (nlpt->_has_sfpt) {
+              has_call = true;
+              _has_sfpt = 1;
+              break;
+            }
+            // Skip to head of inner loop
+            assert(_phase->is_dominator(_head, nlpt->_head), "inner head dominated by outer head");
+            n = nlpt->_head;
+          }
+        }
+      }
+    }
+    // Record safept's that this loop needs preserved when an
+    // inner loop attempts to delete it's safepoints.
+    if (_child != NULL && !has_call && !has_local_ncsfpt) {
+      if (nonlocal_ncsfpt != NULL) {
+        if (_required_safept == NULL) _required_safept = new Node_List();
+        _required_safept->push(nonlocal_ncsfpt);
+      } else {
+        // Failed to find a suitable safept on the dom-path.  Now use
+        // an all paths walk from tail to head, looking for safepoints to preserve.
+        allpaths_check_safepts(visited, stack);
+      }
+    }
+  }
+}
+
+//---------------------------is_deleteable_safept----------------------------
+// Is safept not required by an outer loop?
+bool PhaseIdealLoop::is_deleteable_safept(Node* sfpt) {
+  assert(sfpt->Opcode() == Op_SafePoint, "");
+  IdealLoopTree* lp = get_loop(sfpt)->_parent;
+  while (lp != NULL) {
+    Node_List* sfpts = lp->_required_safept;
+    if (sfpts != NULL) {
+      for (uint i = 0; i < sfpts->size(); i++) {
+        if (sfpt == sfpts->at(i))
+          return false;
+      }
+    }
+    lp = lp->_parent;
+  }
+  return true;
+}
+
+//------------------------------counted_loop-----------------------------------
+// Convert to counted loops where possible
+void IdealLoopTree::counted_loop( PhaseIdealLoop *phase ) {
+
+  // For grins, set the inner-loop flag here
+  if( !_child ) {
+    if( _head->is_Loop() ) _head->as_Loop()->set_inner_loop();
+  }
+
+  if( _head->is_CountedLoop() ||
+      phase->is_counted_loop( _head, this ) ) {
+    _has_sfpt = 1;              // Indicate we do not need a safepoint here
+
+    // Look for a safepoint to remove
+    for (Node* n = tail(); n != _head; n = phase->idom(n))
+      if (n->Opcode() == Op_SafePoint && phase->get_loop(n) == this &&
+          phase->is_deleteable_safept(n))
+        phase->lazy_replace(n,n->in(TypeFunc::Control));
+
+    CountedLoopNode *cl = _head->as_CountedLoop();
+    Node *incr = cl->incr();
+    if( !incr ) return;         // Dead loop?
+    Node *init = cl->init_trip();
+    Node *phi  = cl->phi();
+    // protect against stride not being a constant
+    if( !cl->stride_is_con() ) return;
+    int stride_con = cl->stride_con();
+
+    // Look for induction variables
+
+    // Visit all children, looking for Phis
+    for (DUIterator i = cl->outs(); cl->has_out(i); i++) {
+      Node *out = cl->out(i);
+      if (!out->is_Phi())  continue; // Looking for phis
+      PhiNode* phi2 = out->as_Phi();
+      Node *incr2 = phi2->in( LoopNode::LoopBackControl );
+      // Look for induction variables of the form:  X += constant
+      if( phi2->region() != _head ||
+          incr2->req() != 3 ||
+          incr2->in(1) != phi2 ||
+          incr2 == incr ||
+          incr2->Opcode() != Op_AddI ||
+          !incr2->in(2)->is_Con() )
+        continue;
+
+      // Check for parallel induction variable (parallel to trip counter)
+      // via an affine function.  In particular, count-down loops with
+      // count-up array indices are common. We only RCE references off
+      // the trip-counter, so we need to convert all these to trip-counter
+      // expressions.
+      Node *init2 = phi2->in( LoopNode::EntryControl );
+      int stride_con2 = incr2->in(2)->get_int();
+
+      // The general case here gets a little tricky.  We want to find the
+      // GCD of all possible parallel IV's and make a new IV using this
+      // GCD for the loop.  Then all possible IVs are simple multiples of
+      // the GCD.  In practice, this will cover very few extra loops.
+      // Instead we require 'stride_con2' to be a multiple of 'stride_con',
+      // where +/-1 is the common case, but other integer multiples are
+      // also easy to handle.
+      int ratio_con = stride_con2/stride_con;
+
+      if( ratio_con * stride_con == stride_con2 ) { // Check for exact
+        // Convert to using the trip counter.  The parallel induction
+        // variable differs from the trip counter by a loop-invariant
+        // amount, the difference between their respective initial values.
+        // It is scaled by the 'ratio_con'.
+        Compile* C = phase->C;
+        Node* ratio = phase->_igvn.intcon(ratio_con);
+        phase->set_ctrl(ratio, C->root());
+        Node* ratio_init = new (C, 3) MulINode(init, ratio);
+        phase->_igvn.register_new_node_with_optimizer(ratio_init, init);
+        phase->set_early_ctrl(ratio_init);
+        Node* diff = new (C, 3) SubINode(init2, ratio_init);
+        phase->_igvn.register_new_node_with_optimizer(diff, init2);
+        phase->set_early_ctrl(diff);
+        Node* ratio_idx = new (C, 3) MulINode(phi, ratio);
+        phase->_igvn.register_new_node_with_optimizer(ratio_idx, phi);
+        phase->set_ctrl(ratio_idx, cl);
+        Node* add  = new (C, 3) AddINode(ratio_idx, diff);
+        phase->_igvn.register_new_node_with_optimizer(add);
+        phase->set_ctrl(add, cl);
+        phase->_igvn.hash_delete( phi2 );
+        phase->_igvn.subsume_node( phi2, add );
+        // Sometimes an induction variable is unused
+        if (add->outcnt() == 0) {
+          phase->_igvn.remove_dead_node(add);
+        }
+        --i; // deleted this phi; rescan starting with next position
+        continue;
+      }
+    }
+  } else if (_parent != NULL && !_irreducible) {
+    // Not a counted loop.
+    // Look for a safepoint on the idom-path to remove, preserving the first one
+    bool found = false;
+    Node* n = tail();
+    for (; n != _head && !found; n = phase->idom(n)) {
+      if (n->Opcode() == Op_SafePoint && phase->get_loop(n) == this)
+        found = true; // Found one
+    }
+    // Skip past it and delete the others
+    for (; n != _head; n = phase->idom(n)) {
+      if (n->Opcode() == Op_SafePoint && phase->get_loop(n) == this &&
+          phase->is_deleteable_safept(n))
+        phase->lazy_replace(n,n->in(TypeFunc::Control));
+    }
+  }
+
+  // Recursively
+  if( _child ) _child->counted_loop( phase );
+  if( _next  ) _next ->counted_loop( phase );
+}
+
+#ifndef PRODUCT
+//------------------------------dump_head--------------------------------------
+// Dump 1 liner for loop header info
+void IdealLoopTree::dump_head( ) const {
+  for( uint i=0; i<_nest; i++ )
+    tty->print("  ");
+  tty->print("Loop: N%d/N%d ",_head->_idx,_tail->_idx);
+  if( _irreducible ) tty->print(" IRREDUCIBLE");
+  if( _head->is_CountedLoop() ) {
+    CountedLoopNode *cl = _head->as_CountedLoop();
+    tty->print(" counted");
+    if( cl->is_pre_loop () ) tty->print(" pre" );
+    if( cl->is_main_loop() ) tty->print(" main");
+    if( cl->is_post_loop() ) tty->print(" post");
+  }
+  tty->cr();
+}
+
+//------------------------------dump-------------------------------------------
+// Dump loops by loop tree
+void IdealLoopTree::dump( ) const {
+  dump_head();
+  if( _child ) _child->dump();
+  if( _next  ) _next ->dump();
+}
+
+#endif
+
+//=============================================================================
+//------------------------------PhaseIdealLoop---------------------------------
+// Create a PhaseLoop.  Build the ideal Loop tree.  Map each Ideal Node to
+// its corresponding LoopNode.  If 'optimize' is true, do some loop cleanups.
+PhaseIdealLoop::PhaseIdealLoop( PhaseIterGVN &igvn, const PhaseIdealLoop *verify_me, bool do_split_ifs )
+  : PhaseTransform(Ideal_Loop),
+    _igvn(igvn),
+    _dom_lca_tags(C->comp_arena()) {
+  // Reset major-progress flag for the driver's heuristics
+  C->clear_major_progress();
+
+#ifndef PRODUCT
+  // Capture for later assert
+  uint unique = C->unique();
+  _loop_invokes++;
+  _loop_work += unique;
+#endif
+
+  // True if the method has at least 1 irreducible loop
+  _has_irreducible_loops = false;
+
+  _created_loop_node = false;
+
+  Arena *a = Thread::current()->resource_area();
+  VectorSet visited(a);
+  // Pre-grow the mapping from Nodes to IdealLoopTrees.
+  _nodes.map(C->unique(), NULL);
+  memset(_nodes.adr(), 0, wordSize * C->unique());
+
+  // Pre-build the top-level outermost loop tree entry
+  _ltree_root = new IdealLoopTree( this, C->root(), C->root() );
+  // Do not need a safepoint at the top level
+  _ltree_root->_has_sfpt = 1;
+
+  // Empty pre-order array
+  allocate_preorders();
+
+  // Build a loop tree on the fly.  Build a mapping from CFG nodes to
+  // IdealLoopTree entries.  Data nodes are NOT walked.
+  build_loop_tree();
+  // Check for bailout, and return
+  if (C->failing()) {
+    return;
+  }
+
+  // No loops after all
+  if( !_ltree_root->_child ) C->set_has_loops(false);
+
+  // There should always be an outer loop containing the Root and Return nodes.
+  // If not, we have a degenerate empty program.  Bail out in this case.
+  if (!has_node(C->root())) {
+    C->clear_major_progress();
+    C->record_method_not_compilable("empty program detected during loop optimization");
+    return;
+  }
+
+  // Nothing to do, so get out
+  if( !C->has_loops() && !do_split_ifs && !verify_me) {
+    _igvn.optimize();           // Cleanup NeverBranches
+    return;
+  }
+
+  // Set loop nesting depth
+  _ltree_root->set_nest( 0 );
+
+  // Split shared headers and insert loop landing pads.
+  // Do not bother doing this on the Root loop of course.
+  if( !verify_me && _ltree_root->_child ) {
+    if( _ltree_root->_child->beautify_loops( this ) ) {
+      // Re-build loop tree!
+      _ltree_root->_child = NULL;
+      _nodes.clear();
+      reallocate_preorders();
+      build_loop_tree();
+      // Check for bailout, and return
+      if (C->failing()) {
+        return;
+      }
+      // Reset loop nesting depth
+      _ltree_root->set_nest( 0 );
+    }
+  }
+
+  // Build Dominators for elision of NULL checks & loop finding.
+  // Since nodes do not have a slot for immediate dominator, make
+  // a persistant side array for that info indexed on node->_idx.
+  _idom_size = C->unique();
+  _idom      = NEW_RESOURCE_ARRAY( Node*, _idom_size );
+  _dom_depth = NEW_RESOURCE_ARRAY( uint,  _idom_size );
+  _dom_stk   = NULL; // Allocated on demand in recompute_dom_depth
+  memset( _dom_depth, 0, _idom_size * sizeof(uint) );
+
+  Dominators();
+
+  // As a side effect, Dominators removed any unreachable CFG paths
+  // into RegionNodes.  It doesn't do this test against Root, so
+  // we do it here.
+  for( uint i = 1; i < C->root()->req(); i++ ) {
+    if( !_nodes[C->root()->in(i)->_idx] ) {    // Dead path into Root?
+      _igvn.hash_delete(C->root());
+      C->root()->del_req(i);
+      _igvn._worklist.push(C->root());
+      i--;                      // Rerun same iteration on compressed edges
+    }
+  }
+
+  // Given dominators, try to find inner loops with calls that must
+  // always be executed (call dominates loop tail).  These loops do
+  // not need a seperate safepoint.
+  Node_List cisstack(a);
+  _ltree_root->check_safepts(visited, cisstack);
+
+  // Walk the DATA nodes and place into loops.  Find earliest control
+  // node.  For CFG nodes, the _nodes array starts out and remains
+  // holding the associated IdealLoopTree pointer.  For DATA nodes, the
+  // _nodes array holds the earliest legal controlling CFG node.
+
+  // Allocate stack with enough space to avoid frequent realloc
+  int stack_size = (C->unique() >> 1) + 16; // (unique>>1)+16 from Java2D stats
+  Node_Stack nstack( a, stack_size );
+
+  visited.Clear();
+  Node_List worklist(a);
+  // Don't need C->root() on worklist since
+  // it will be processed among C->top() inputs
+  worklist.push( C->top() );
+  visited.set( C->top()->_idx ); // Set C->top() as visited now
+  build_loop_early( visited, worklist, nstack, verify_me );
+
+  // Given early legal placement, try finding counted loops.  This placement
+  // is good enough to discover most loop invariants.
+  if( !verify_me )
+    _ltree_root->counted_loop( this );
+
+  // Find latest loop placement.  Find ideal loop placement.
+  visited.Clear();
+  init_dom_lca_tags();
+  // Need C->root() on worklist when processing outs
+  worklist.push( C->root() );
+  NOT_PRODUCT( C->verify_graph_edges(); )
+  worklist.push( C->top() );
+  build_loop_late( visited, worklist, nstack, verify_me );
+
+  // clear out the dead code
+  while(_deadlist.size()) {
+    igvn.remove_globally_dead_node(_deadlist.pop());
+  }
+
+#ifndef PRODUCT
+  C->verify_graph_edges();
+  if( verify_me ) {             // Nested verify pass?
+    // Check to see if the verify mode is broken
+    assert(C->unique() == unique, "non-optimize mode made Nodes? ? ?");
+    return;
+  }
+  if( VerifyLoopOptimizations ) verify();
+#endif
+
+  if (ReassociateInvariants) {
+    // Reassociate invariants and prep for split_thru_phi
+    for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
+      IdealLoopTree* lpt = iter.current();
+      if (!lpt->is_counted() || !lpt->is_inner()) continue;
+
+      lpt->reassociate_invariants(this);
+
+      // Because RCE opportunities can be masked by split_thru_phi,
+      // look for RCE candidates and inhibit split_thru_phi
+      // on just their loop-phi's for this pass of loop opts
+      if( SplitIfBlocks && do_split_ifs ) {
+        if (lpt->policy_range_check(this)) {
+          lpt->_rce_candidate = true;
+        }
+      }
+    }
+  }
+
+  // Check for aggressive application of split-if and other transforms
+  // that require basic-block info (like cloning through Phi's)
+  if( SplitIfBlocks && do_split_ifs ) {
+    visited.Clear();
+    split_if_with_blocks( visited, nstack );
+    NOT_PRODUCT( if( VerifyLoopOptimizations ) verify(); );
+  }
+
+  // Perform iteration-splitting on inner loops.  Split iterations to avoid
+  // range checks or one-shot null checks.
+
+  // If split-if's didn't hack the graph too bad (no CFG changes)
+  // then do loop opts.
+  if( C->has_loops() && !C->major_progress() ) {
+    memset( worklist.adr(), 0, worklist.Size()*sizeof(Node*) );
+    _ltree_root->_child->iteration_split( this, worklist );
+    // No verify after peeling!  GCM has hoisted code out of the loop.
+    // After peeling, the hoisted code could sink inside the peeled area.
+    // The peeling code does not try to recompute the best location for
+    // all the code before the peeled area, so the verify pass will always
+    // complain about it.
+  }
+  // Do verify graph edges in any case
+  NOT_PRODUCT( C->verify_graph_edges(); );
+
+  if( !do_split_ifs ) {
+    // We saw major progress in Split-If to get here.  We forced a
+    // pass with unrolling and not split-if, however more split-if's
+    // might make progress.  If the unrolling didn't make progress
+    // then the major-progress flag got cleared and we won't try
+    // another round of Split-If.  In particular the ever-common
+    // instance-of/check-cast pattern requires at least 2 rounds of
+    // Split-If to clear out.
+    C->set_major_progress();
+  }
+
+  // Repeat loop optimizations if new loops were seen
+  if (created_loop_node()) {
+    C->set_major_progress();
+  }
+
+  // Convert scalar to superword operations
+
+  if (UseSuperWord && C->has_loops() && !C->major_progress()) {
+    // SuperWord transform
+    SuperWord sw(this);
+    for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
+      IdealLoopTree* lpt = iter.current();
+      if (lpt->is_counted()) {
+        sw.transform_loop(lpt);
+      }
+    }
+  }
+
+  // Cleanup any modified bits
+  _igvn.optimize();
+
+  // Do not repeat loop optimizations if irreducible loops are present
+  // by claiming no-progress.
+  if( _has_irreducible_loops )
+    C->clear_major_progress();
+}
+
+#ifndef PRODUCT
+//------------------------------print_statistics-------------------------------
+int PhaseIdealLoop::_loop_invokes=0;// Count of PhaseIdealLoop invokes
+int PhaseIdealLoop::_loop_work=0; // Sum of PhaseIdealLoop x unique
+void PhaseIdealLoop::print_statistics() {
+  tty->print_cr("PhaseIdealLoop=%d, sum _unique=%d", _loop_invokes, _loop_work);
+}
+
+//------------------------------verify-----------------------------------------
+// Build a verify-only PhaseIdealLoop, and see that it agrees with me.
+static int fail;                // debug only, so its multi-thread dont care
+void PhaseIdealLoop::verify() const {
+  int old_progress = C->major_progress();
+  ResourceMark rm;
+  PhaseIdealLoop loop_verify( _igvn, this, false );
+  VectorSet visited(Thread::current()->resource_area());
+
+  fail = 0;
+  verify_compare( C->root(), &loop_verify, visited );
+  assert( fail == 0, "verify loops failed" );
+  // Verify loop structure is the same
+  _ltree_root->verify_tree(loop_verify._ltree_root, NULL);
+  // Reset major-progress.  It was cleared by creating a verify version of
+  // PhaseIdealLoop.
+  for( int i=0; i<old_progress; i++ )
+    C->set_major_progress();
+}
+
+//------------------------------verify_compare---------------------------------
+// Make sure me and the given PhaseIdealLoop agree on key data structures
+void PhaseIdealLoop::verify_compare( Node *n, const PhaseIdealLoop *loop_verify, VectorSet &visited ) const {
+  if( !n ) return;
+  if( visited.test_set( n->_idx ) ) return;
+  if( !_nodes[n->_idx] ) {      // Unreachable
+    assert( !loop_verify->_nodes[n->_idx], "both should be unreachable" );
+    return;
+  }
+
+  uint i;
+  for( i = 0; i < n->req(); i++ )
+    verify_compare( n->in(i), loop_verify, visited );
+
+  // Check the '_nodes' block/loop structure
+  i = n->_idx;
+  if( has_ctrl(n) ) {           // We have control; verify has loop or ctrl
+    if( _nodes[i] != loop_verify->_nodes[i] &&
+        get_ctrl_no_update(n) != loop_verify->get_ctrl_no_update(n) ) {
+      tty->print("Mismatched control setting for: ");
+      n->dump();
+      if( fail++ > 10 ) return;
+      Node *c = get_ctrl_no_update(n);
+      tty->print("We have it as: ");
+      if( c->in(0) ) c->dump();
+        else tty->print_cr("N%d",c->_idx);
+      tty->print("Verify thinks: ");
+      if( loop_verify->has_ctrl(n) )
+        loop_verify->get_ctrl_no_update(n)->dump();
+      else
+        loop_verify->get_loop_idx(n)->dump();
+      tty->cr();
+    }
+  } else {                    // We have a loop
+    IdealLoopTree *us = get_loop_idx(n);
+    if( loop_verify->has_ctrl(n) ) {
+      tty->print("Mismatched loop setting for: ");
+      n->dump();
+      if( fail++ > 10 ) return;
+      tty->print("We have it as: ");
+      us->dump();
+      tty->print("Verify thinks: ");
+      loop_verify->get_ctrl_no_update(n)->dump();
+      tty->cr();
+    } else if (!C->major_progress()) {
+      // Loop selection can be messed up if we did a major progress
+      // operation, like split-if.  Do not verify in that case.
+      IdealLoopTree *them = loop_verify->get_loop_idx(n);
+      if( us->_head != them->_head ||  us->_tail != them->_tail ) {
+        tty->print("Unequals loops for: ");
+        n->dump();
+        if( fail++ > 10 ) return;
+        tty->print("We have it as: ");
+        us->dump();
+        tty->print("Verify thinks: ");
+        them->dump();
+        tty->cr();
+      }
+    }
+  }
+
+  // Check for immediate dominators being equal
+  if( i >= _idom_size ) {
+    if( !n->is_CFG() ) return;
+    tty->print("CFG Node with no idom: ");
+    n->dump();
+    return;
+  }
+  if( !n->is_CFG() ) return;
+  if( n == C->root() ) return; // No IDOM here
+
+  assert(n->_idx == i, "sanity");
+  Node *id = idom_no_update(n);
+  if( id != loop_verify->idom_no_update(n) ) {
+    tty->print("Unequals idoms for: ");
+    n->dump();
+    if( fail++ > 10 ) return;
+    tty->print("We have it as: ");
+    id->dump();
+    tty->print("Verify thinks: ");
+    loop_verify->idom_no_update(n)->dump();
+    tty->cr();
+  }
+
+}
+
+//------------------------------verify_tree------------------------------------
+// Verify that tree structures match.  Because the CFG can change, siblings
+// within the loop tree can be reordered.  We attempt to deal with that by
+// reordering the verify's loop tree if possible.
+void IdealLoopTree::verify_tree(IdealLoopTree *loop, const IdealLoopTree *parent) const {
+  assert( _parent == parent, "Badly formed loop tree" );
+
+  // Siblings not in same order?  Attempt to re-order.
+  if( _head != loop->_head ) {
+    // Find _next pointer to update
+    IdealLoopTree **pp = &loop->_parent->_child;
+    while( *pp != loop )
+      pp = &((*pp)->_next);
+    // Find proper sibling to be next
+    IdealLoopTree **nn = &loop->_next;
+    while( (*nn) && (*nn)->_head != _head )
+      nn = &((*nn)->_next);
+
+    // Check for no match.
+    if( !(*nn) ) {
+      // Annoyingly, irreducible loops can pick different headers
+      // after a major_progress operation, so the rest of the loop
+      // tree cannot be matched.
+      if (_irreducible && Compile::current()->major_progress())  return;
+      assert( 0, "failed to match loop tree" );
+    }
+
+    // Move (*nn) to (*pp)
+    IdealLoopTree *hit = *nn;
+    *nn = hit->_next;
+    hit->_next = loop;
+    *pp = loop;
+    loop = hit;
+    // Now try again to verify
+  }
+
+  assert( _head  == loop->_head , "mismatched loop head" );
+  Node *tail = _tail;           // Inline a non-updating version of
+  while( !tail->in(0) )         // the 'tail()' call.
+    tail = tail->in(1);
+  assert( tail == loop->_tail, "mismatched loop tail" );
+
+  // Counted loops that are guarded should be able to find their guards
+  if( _head->is_CountedLoop() && _head->as_CountedLoop()->is_main_loop() ) {
+    CountedLoopNode *cl = _head->as_CountedLoop();
+    Node *init = cl->init_trip();
+    Node *ctrl = cl->in(LoopNode::EntryControl);
+    assert( ctrl->Opcode() == Op_IfTrue || ctrl->Opcode() == Op_IfFalse, "" );
+    Node *iff  = ctrl->in(0);
+    assert( iff->Opcode() == Op_If, "" );
+    Node *bol  = iff->in(1);
+    assert( bol->Opcode() == Op_Bool, "" );
+    Node *cmp  = bol->in(1);
+    assert( cmp->Opcode() == Op_CmpI, "" );
+    Node *add  = cmp->in(1);
+    Node *opaq;
+    if( add->Opcode() == Op_Opaque1 ) {
+      opaq = add;
+    } else {
+      assert( add->Opcode() == Op_AddI || add->Opcode() == Op_ConI , "" );
+      assert( add == init, "" );
+      opaq = cmp->in(2);
+    }
+    assert( opaq->Opcode() == Op_Opaque1, "" );
+
+  }
+
+  if (_child != NULL)  _child->verify_tree(loop->_child, this);
+  if (_next  != NULL)  _next ->verify_tree(loop->_next,  parent);
+  // Innermost loops need to verify loop bodies,
+  // but only if no 'major_progress'
+  int fail = 0;
+  if (!Compile::current()->major_progress() && _child == NULL) {
+    for( uint i = 0; i < _body.size(); i++ ) {
+      Node *n = _body.at(i);
+      if (n->outcnt() == 0)  continue; // Ignore dead
+      uint j;
+      for( j = 0; j < loop->_body.size(); j++ )
+        if( loop->_body.at(j) == n )
+          break;
+      if( j == loop->_body.size() ) { // Not found in loop body
+        // Last ditch effort to avoid assertion: Its possible that we
+        // have some users (so outcnt not zero) but are still dead.
+        // Try to find from root.
+        if (Compile::current()->root()->find(n->_idx)) {
+          fail++;
+          tty->print("We have that verify does not: ");
+          n->dump();
+        }
+      }
+    }
+    for( uint i2 = 0; i2 < loop->_body.size(); i2++ ) {
+      Node *n = loop->_body.at(i2);
+      if (n->outcnt() == 0)  continue; // Ignore dead
+      uint j;
+      for( j = 0; j < _body.size(); j++ )
+        if( _body.at(j) == n )
+          break;
+      if( j == _body.size() ) { // Not found in loop body
+        // Last ditch effort to avoid assertion: Its possible that we
+        // have some users (so outcnt not zero) but are still dead.
+        // Try to find from root.
+        if (Compile::current()->root()->find(n->_idx)) {
+          fail++;
+          tty->print("Verify has that we do not: ");
+          n->dump();
+        }
+      }
+    }
+    assert( !fail, "loop body mismatch" );
+  }
+}
+
+#endif
+
+//------------------------------set_idom---------------------------------------
+void PhaseIdealLoop::set_idom(Node* d, Node* n, uint dom_depth) {
+  uint idx = d->_idx;
+  if (idx >= _idom_size) {
+    uint newsize = _idom_size<<1;
+    while( idx >= newsize ) {
+      newsize <<= 1;
+    }
+    _idom      = REALLOC_RESOURCE_ARRAY( Node*,     _idom,_idom_size,newsize);
+    _dom_depth = REALLOC_RESOURCE_ARRAY( uint, _dom_depth,_idom_size,newsize);
+    memset( _dom_depth + _idom_size, 0, (newsize - _idom_size) * sizeof(uint) );
+    _idom_size = newsize;
+  }
+  _idom[idx] = n;
+  _dom_depth[idx] = dom_depth;
+}
+
+//------------------------------recompute_dom_depth---------------------------------------
+// The dominator tree is constructed with only parent pointers.
+// This recomputes the depth in the tree by first tagging all
+// nodes as "no depth yet" marker.  The next pass then runs up
+// the dom tree from each node marked "no depth yet", and computes
+// the depth on the way back down.
+void PhaseIdealLoop::recompute_dom_depth() {
+  uint no_depth_marker = C->unique();
+  uint i;
+  // Initialize depth to "no depth yet"
+  for (i = 0; i < _idom_size; i++) {
+    if (_dom_depth[i] > 0 && _idom[i] != NULL) {
+     _dom_depth[i] = no_depth_marker;
+    }
+  }
+  if (_dom_stk == NULL) {
+    uint init_size = C->unique() / 100; // Guess that 1/100 is a reasonable initial size.
+    if (init_size < 10) init_size = 10;
+    _dom_stk = new (C->node_arena()) GrowableArray<uint>(C->node_arena(), init_size, 0, 0);
+  }
+  // Compute new depth for each node.
+  for (i = 0; i < _idom_size; i++) {
+    uint j = i;
+    // Run up the dom tree to find a node with a depth
+    while (_dom_depth[j] == no_depth_marker) {
+      _dom_stk->push(j);
+      j = _idom[j]->_idx;
+    }
+    // Compute the depth on the way back down this tree branch
+    uint dd = _dom_depth[j] + 1;
+    while (_dom_stk->length() > 0) {
+      uint j = _dom_stk->pop();
+      _dom_depth[j] = dd;
+      dd++;
+    }
+  }
+}
+
+//------------------------------sort-------------------------------------------
+// Insert 'loop' into the existing loop tree.  'innermost' is a leaf of the
+// loop tree, not the root.
+IdealLoopTree *PhaseIdealLoop::sort( IdealLoopTree *loop, IdealLoopTree *innermost ) {
+  if( !innermost ) return loop; // New innermost loop
+
+  int loop_preorder = get_preorder(loop->_head); // Cache pre-order number
+  assert( loop_preorder, "not yet post-walked loop" );
+  IdealLoopTree **pp = &innermost;      // Pointer to previous next-pointer
+  IdealLoopTree *l = *pp;               // Do I go before or after 'l'?
+
+  // Insert at start of list
+  while( l ) {                  // Insertion sort based on pre-order
+    if( l == loop ) return innermost; // Already on list!
+    int l_preorder = get_preorder(l->_head); // Cache pre-order number
+    assert( l_preorder, "not yet post-walked l" );
+    // Check header pre-order number to figure proper nesting
+    if( loop_preorder > l_preorder )
+      break;                    // End of insertion
+    // If headers tie (e.g., shared headers) check tail pre-order numbers.
+    // Since I split shared headers, you'd think this could not happen.
+    // BUT: I must first do the preorder numbering before I can discover I
+    // have shared headers, so the split headers all get the same preorder
+    // number as the RegionNode they split from.
+    if( loop_preorder == l_preorder &&
+        get_preorder(loop->_tail) < get_preorder(l->_tail) )
+      break;                    // Also check for shared headers (same pre#)
+    pp = &l->_parent;           // Chain up list
+    l = *pp;
+  }
+  // Link into list
+  // Point predecessor to me
+  *pp = loop;
+  // Point me to successor
+  IdealLoopTree *p = loop->_parent;
+  loop->_parent = l;            // Point me to successor
+  if( p ) sort( p, innermost ); // Insert my parents into list as well
+  return innermost;
+}
+
+//------------------------------build_loop_tree--------------------------------
+// I use a modified Vick/Tarjan algorithm.  I need pre- and a post- visit
+// bits.  The _nodes[] array is mapped by Node index and holds a NULL for
+// not-yet-pre-walked, pre-order # for pre-but-not-post-walked and holds the
+// tightest enclosing IdealLoopTree for post-walked.
+//
+// During my forward walk I do a short 1-layer lookahead to see if I can find
+// a loop backedge with that doesn't have any work on the backedge.  This
+// helps me construct nested loops with shared headers better.
+//
+// Once I've done the forward recursion, I do the post-work.  For each child
+// I check to see if there is a backedge.  Backedges define a loop!  I
+// insert an IdealLoopTree at the target of the backedge.
+//
+// During the post-work I also check to see if I have several children
+// belonging to different loops.  If so, then this Node is a decision point
+// where control flow can choose to change loop nests.  It is at this
+// decision point where I can figure out how loops are nested.  At this
+// time I can properly order the different loop nests from my children.
+// Note that there may not be any backedges at the decision point!
+//
+// Since the decision point can be far removed from the backedges, I can't
+// order my loops at the time I discover them.  Thus at the decision point
+// I need to inspect loop header pre-order numbers to properly nest my
+// loops.  This means I need to sort my childrens' loops by pre-order.
+// The sort is of size number-of-control-children, which generally limits
+// it to size 2 (i.e., I just choose between my 2 target loops).
+void PhaseIdealLoop::build_loop_tree() {
+  // Allocate stack of size C->unique()/2 to avoid frequent realloc
+  GrowableArray <Node *> bltstack(C->unique() >> 1);
+  Node *n = C->root();
+  bltstack.push(n);
+  int pre_order = 1;
+  int stack_size;
+
+  while ( ( stack_size = bltstack.length() ) != 0 ) {
+    n = bltstack.top(); // Leave node on stack
+    if ( !is_visited(n) ) {
+      // ---- Pre-pass Work ----
+      // Pre-walked but not post-walked nodes need a pre_order number.
+
+      set_preorder_visited( n, pre_order ); // set as visited
+
+      // ---- Scan over children ----
+      // Scan first over control projections that lead to loop headers.
+      // This helps us find inner-to-outer loops with shared headers better.
+
+      // Scan children's children for loop headers.
+      for ( int i = n->outcnt() - 1; i >= 0; --i ) {
+        Node* m = n->raw_out(i);       // Child
+        if( m->is_CFG() && !is_visited(m) ) { // Only for CFG children
+          // Scan over children's children to find loop
+          for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
+            Node* l = m->fast_out(j);
+            if( is_visited(l) &&       // Been visited?
+                !is_postvisited(l) &&  // But not post-visited
+                get_preorder(l) < pre_order ) { // And smaller pre-order
+              // Found!  Scan the DFS down this path before doing other paths
+              bltstack.push(m);
+              break;
+            }
+          }
+        }
+      }
+      pre_order++;
+    }
+    else if ( !is_postvisited(n) ) {
+      // Note: build_loop_tree_impl() adds out edges on rare occasions,
+      // such as com.sun.rsasign.am::a.
+      // For non-recursive version, first, process current children.
+      // On next iteration, check if additional children were added.
+      for ( int k = n->outcnt() - 1; k >= 0; --k ) {
+        Node* u = n->raw_out(k);
+        if ( u->is_CFG() && !is_visited(u) ) {
+          bltstack.push(u);
+        }
+      }
+      if ( bltstack.length() == stack_size ) {
+        // There were no additional children, post visit node now
+        (void)bltstack.pop(); // Remove node from stack
+        pre_order = build_loop_tree_impl( n, pre_order );
+        // Check for bailout
+        if (C->failing()) {
+          return;
+        }
+        // Check to grow _preorders[] array for the case when
+        // build_loop_tree_impl() adds new nodes.
+        check_grow_preorders();
+      }
+    }
+    else {
+      (void)bltstack.pop(); // Remove post-visited node from stack
+    }
+  }
+}
+
+//------------------------------build_loop_tree_impl---------------------------
+int PhaseIdealLoop::build_loop_tree_impl( Node *n, int pre_order ) {
+  // ---- Post-pass Work ----
+  // Pre-walked but not post-walked nodes need a pre_order number.
+
+  // Tightest enclosing loop for this Node
+  IdealLoopTree *innermost = NULL;
+
+  // For all children, see if any edge is a backedge.  If so, make a loop
+  // for it.  Then find the tightest enclosing loop for the self Node.
+  for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
+    Node* m = n->fast_out(i);   // Child
+    if( n == m ) continue;      // Ignore control self-cycles
+    if( !m->is_CFG() ) continue;// Ignore non-CFG edges
+
+    IdealLoopTree *l;           // Child's loop
+    if( !is_postvisited(m) ) {  // Child visited but not post-visited?
+      // Found a backedge
+      assert( get_preorder(m) < pre_order, "should be backedge" );
+      // Check for the RootNode, which is already a LoopNode and is allowed
+      // to have multiple "backedges".
+      if( m == C->root()) {     // Found the root?
+        l = _ltree_root;        // Root is the outermost LoopNode
+      } else {                  // Else found a nested loop
+        // Insert a LoopNode to mark this loop.
+        l = new IdealLoopTree(this, m, n);
+      } // End of Else found a nested loop
+      if( !has_loop(m) )        // If 'm' does not already have a loop set
+        set_loop(m, l);         // Set loop header to loop now
+
+    } else {                    // Else not a nested loop
+      if( !_nodes[m->_idx] ) continue; // Dead code has no loop
+      l = get_loop(m);          // Get previously determined loop
+      // If successor is header of a loop (nest), move up-loop till it
+      // is a member of some outer enclosing loop.  Since there are no
+      // shared headers (I've split them already) I only need to go up
+      // at most 1 level.
+      while( l && l->_head == m ) // Successor heads loop?
+        l = l->_parent;         // Move up 1 for me
+      // If this loop is not properly parented, then this loop
+      // has no exit path out, i.e. its an infinite loop.
+      if( !l ) {
+        // Make loop "reachable" from root so the CFG is reachable.  Basically
+        // insert a bogus loop exit that is never taken.  'm', the loop head,
+        // points to 'n', one (of possibly many) fall-in paths.  There may be
+        // many backedges as well.
+
+        // Here I set the loop to be the root loop.  I could have, after
+        // inserting a bogus loop exit, restarted the recursion and found my
+        // new loop exit.  This would make the infinite loop a first-class
+        // loop and it would then get properly optimized.  What's the use of
+        // optimizing an infinite loop?
+        l = _ltree_root;        // Oops, found infinite loop
+
+        // Insert the NeverBranch between 'm' and it's control user.
+        NeverBranchNode *iff = new (C, 1) NeverBranchNode( m );
+        _igvn.register_new_node_with_optimizer(iff);
+        set_loop(iff, l);
+        Node *if_t = new (C, 1) CProjNode( iff, 0 );
+        _igvn.register_new_node_with_optimizer(if_t);
+        set_loop(if_t, l);
+
+        Node* cfg = NULL;       // Find the One True Control User of m
+        for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
+          Node* x = m->fast_out(j);
+          if (x->is_CFG() && x != m && x != iff)
+            { cfg = x; break; }
+        }
+        assert(cfg != NULL, "must find the control user of m");
+        uint k = 0;             // Probably cfg->in(0)
+        while( cfg->in(k) != m ) k++; // But check incase cfg is a Region
+        cfg->set_req( k, if_t ); // Now point to NeverBranch
+
+        // Now create the never-taken loop exit
+        Node *if_f = new (C, 1) CProjNode( iff, 1 );
+        _igvn.register_new_node_with_optimizer(if_f);
+        set_loop(if_f, l);
+        // Find frame ptr for Halt.  Relies on the optimizer
+        // V-N'ing.  Easier and quicker than searching through
+        // the program structure.
+        Node *frame = new (C, 1) ParmNode( C->start(), TypeFunc::FramePtr );
+        _igvn.register_new_node_with_optimizer(frame);
+        // Halt & Catch Fire
+        Node *halt = new (C, TypeFunc::Parms) HaltNode( if_f, frame );
+        _igvn.register_new_node_with_optimizer(halt);
+        set_loop(halt, l);
+        C->root()->add_req(halt);
+        set_loop(C->root(), _ltree_root);
+      }
+    }
+    // Weeny check for irreducible.  This child was already visited (this
+    // IS the post-work phase).  Is this child's loop header post-visited
+    // as well?  If so, then I found another entry into the loop.
+    while( is_postvisited(l->_head) ) {
+      // found irreducible
+      l->_irreducible = true;
+      l = l->_parent;
+      _has_irreducible_loops = true;
+      // Check for bad CFG here to prevent crash, and bailout of compile
+      if (l == NULL) {
+        C->record_method_not_compilable("unhandled CFG detected during loop optimization");
+        return pre_order;
+      }
+    }
+
+    // This Node might be a decision point for loops.  It is only if
+    // it's children belong to several different loops.  The sort call
+    // does a trivial amount of work if there is only 1 child or all
+    // children belong to the same loop.  If however, the children
+    // belong to different loops, the sort call will properly set the
+    // _parent pointers to show how the loops nest.
+    //
+    // In any case, it returns the tightest enclosing loop.
+    innermost = sort( l, innermost );
+  }
+
+  // Def-use info will have some dead stuff; dead stuff will have no
+  // loop decided on.
+
+  // Am I a loop header?  If so fix up my parent's child and next ptrs.
+  if( innermost && innermost->_head == n ) {
+    assert( get_loop(n) == innermost, "" );
+    IdealLoopTree *p = innermost->_parent;
+    IdealLoopTree *l = innermost;
+    while( p && l->_head == n ) {
+      l->_next = p->_child;     // Put self on parents 'next child'
+      p->_child = l;            // Make self as first child of parent
+      l = p;                    // Now walk up the parent chain
+      p = l->_parent;
+    }
+  } else {
+    // Note that it is possible for a LoopNode to reach here, if the
+    // backedge has been made unreachable (hence the LoopNode no longer
+    // denotes a Loop, and will eventually be removed).
+
+    // Record tightest enclosing loop for self.  Mark as post-visited.
+    set_loop(n, innermost);
+    // Also record has_call flag early on
+    if( innermost ) {
+      if( n->is_Call() && !n->is_CallLeaf() && !n->is_macro() ) {
+        // Do not count uncommon calls
+        if( !n->is_CallStaticJava() || !n->as_CallStaticJava()->_name ) {
+          Node *iff = n->in(0)->in(0);
+          if( !iff->is_If() ||
+              (n->in(0)->Opcode() == Op_IfFalse &&
+               (1.0 - iff->as_If()->_prob) >= 0.01) ||
+              (iff->as_If()->_prob >= 0.01) )
+            innermost->_has_call = 1;
+        }
+      }
+    }
+  }
+
+  // Flag as post-visited now
+  set_postvisited(n);
+  return pre_order;
+}
+
+
+//------------------------------build_loop_early-------------------------------
+// Put Data nodes into some loop nest, by setting the _nodes[]->loop mapping.
+// First pass computes the earliest controlling node possible.  This is the
+// controlling input with the deepest dominating depth.
+void PhaseIdealLoop::build_loop_early( VectorSet &visited, Node_List &worklist, Node_Stack &nstack, const PhaseIdealLoop *verify_me ) {
+  while (worklist.size() != 0) {
+    // Use local variables nstack_top_n & nstack_top_i to cache values
+    // on nstack's top.
+    Node *nstack_top_n = worklist.pop();
+    uint  nstack_top_i = 0;
+//while_nstack_nonempty:
+    while (true) {
+      // Get parent node and next input's index from stack's top.
+      Node  *n = nstack_top_n;
+      uint   i = nstack_top_i;
+      uint cnt = n->req(); // Count of inputs
+      if (i == 0) {        // Pre-process the node.
+        if( has_node(n) &&            // Have either loop or control already?
+            !has_ctrl(n) ) {          // Have loop picked out already?
+          // During "merge_many_backedges" we fold up several nested loops
+          // into a single loop.  This makes the members of the original
+          // loop bodies pointing to dead loops; they need to move up
+          // to the new UNION'd larger loop.  I set the _head field of these
+          // dead loops to NULL and the _parent field points to the owning
+          // loop.  Shades of UNION-FIND algorithm.
+          IdealLoopTree *ilt;
+          while( !(ilt = get_loop(n))->_head ) {
+            // Normally I would use a set_loop here.  But in this one special
+            // case, it is legal (and expected) to change what loop a Node
+            // belongs to.
+            _nodes.map(n->_idx, (Node*)(ilt->_parent) );
+          }
+          // Remove safepoints ONLY if I've already seen I don't need one.
+          // (the old code here would yank a 2nd safepoint after seeing a
+          // first one, even though the 1st did not dominate in the loop body
+          // and thus could be avoided indefinitely)
+          if( !verify_me && ilt->_has_sfpt && n->Opcode() == Op_SafePoint &&
+              is_deleteable_safept(n)) {
+            Node *in = n->in(TypeFunc::Control);
+            lazy_replace(n,in);       // Pull safepoint now
+            // Carry on with the recursion "as if" we are walking
+            // only the control input
+            if( !visited.test_set( in->_idx ) ) {
+              worklist.push(in);      // Visit this guy later, using worklist
+            }
+            // Get next node from nstack:
+            // - skip n's inputs processing by setting i > cnt;
+            // - we also will not call set_early_ctrl(n) since
+            //   has_node(n) == true (see the condition above).
+            i = cnt + 1;
+          }
+        }
+      } // if (i == 0)
+
+      // Visit all inputs
+      bool done = true;       // Assume all n's inputs will be processed
+      while (i < cnt) {
+        Node *in = n->in(i);
+        ++i;
+        if (in == NULL) continue;
+        if (in->pinned() && !in->is_CFG())
+          set_ctrl(in, in->in(0));
+        int is_visited = visited.test_set( in->_idx );
+        if (!has_node(in)) {  // No controlling input yet?
+          assert( !in->is_CFG(), "CFG Node with no controlling input?" );
+          assert( !is_visited, "visit only once" );
+          nstack.push(n, i);  // Save parent node and next input's index.
+          nstack_top_n = in;  // Process current input now.
+          nstack_top_i = 0;
+          done = false;       // Not all n's inputs processed.
+          break; // continue while_nstack_nonempty;
+        } else if (!is_visited) {
+          // This guy has a location picked out for him, but has not yet
+          // been visited.  Happens to all CFG nodes, for instance.
+          // Visit him using the worklist instead of recursion, to break
+          // cycles.  Since he has a location already we do not need to
+          // find his location before proceeding with the current Node.
+          worklist.push(in);  // Visit this guy later, using worklist
+        }
+      }
+      if (done) {
+        // All of n's inputs have been processed, complete post-processing.
+
+        // Compute earilest point this Node can go.
+        // CFG, Phi, pinned nodes already know their controlling input.
+        if (!has_node(n)) {
+          // Record earliest legal location
+          set_early_ctrl( n );
+        }
+        if (nstack.is_empty()) {
+          // Finished all nodes on stack.
+          // Process next node on the worklist.
+          break;
+        }
+        // Get saved parent node and next input's index.
+        nstack_top_n = nstack.node();
+        nstack_top_i = nstack.index();
+        nstack.pop();
+      }
+    } // while (true)
+  }
+}
+
+//------------------------------dom_lca_internal--------------------------------
+// Pair-wise LCA
+Node *PhaseIdealLoop::dom_lca_internal( Node *n1, Node *n2 ) const {
+  if( !n1 ) return n2;          // Handle NULL original LCA
+  assert( n1->is_CFG(), "" );
+  assert( n2->is_CFG(), "" );
+  // find LCA of all uses
+  uint d1 = dom_depth(n1);
+  uint d2 = dom_depth(n2);
+  while (n1 != n2) {
+    if (d1 > d2) {
+      n1 =      idom(n1);
+      d1 = dom_depth(n1);
+    } else if (d1 < d2) {
+      n2 =      idom(n2);
+      d2 = dom_depth(n2);
+    } else {
+      // Here d1 == d2.  Due to edits of the dominator-tree, sections
+      // of the tree might have the same depth.  These sections have
+      // to be searched more carefully.
+
+      // Scan up all the n1's with equal depth, looking for n2.
+      Node *t1 = idom(n1);
+      while (dom_depth(t1) == d1) {
+        if (t1 == n2)  return n2;
+        t1 = idom(t1);
+      }
+      // Scan up all the n2's with equal depth, looking for n1.
+      Node *t2 = idom(n2);
+      while (dom_depth(t2) == d2) {
+        if (t2 == n1)  return n1;
+        t2 = idom(t2);
+      }
+      // Move up to a new dominator-depth value as well as up the dom-tree.
+      n1 = t1;
+      n2 = t2;
+      d1 = dom_depth(n1);
+      d2 = dom_depth(n2);
+    }
+  }
+  return n1;
+}
+
+//------------------------------compute_idom-----------------------------------
+// Locally compute IDOM using dom_lca call.  Correct only if the incoming
+// IDOMs are correct.
+Node *PhaseIdealLoop::compute_idom( Node *region ) const {
+  assert( region->is_Region(), "" );
+  Node *LCA = NULL;
+  for( uint i = 1; i < region->req(); i++ ) {
+    if( region->in(i) != C->top() )
+      LCA = dom_lca( LCA, region->in(i) );
+  }
+  return LCA;
+}
+
+//------------------------------get_late_ctrl----------------------------------
+// Compute latest legal control.
+Node *PhaseIdealLoop::get_late_ctrl( Node *n, Node *early ) {
+  assert(early != NULL, "early control should not be NULL");
+
+  // Compute LCA over list of uses
+  Node *LCA = NULL;
+  for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax && LCA != early; i++) {
+    Node* c = n->fast_out(i);
+    if (_nodes[c->_idx] == NULL)
+      continue;                 // Skip the occasional dead node
+    if( c->is_Phi() ) {         // For Phis, we must land above on the path
+      for( uint j=1; j<c->req(); j++ ) {// For all inputs
+        if( c->in(j) == n ) {   // Found matching input?
+          Node *use = c->in(0)->in(j);
+          LCA = dom_lca_for_get_late_ctrl( LCA, use, n );
+        }
+      }
+    } else {
+      // For CFG data-users, use is in the block just prior
+      Node *use = has_ctrl(c) ? get_ctrl(c) : c->in(0);
+      LCA = dom_lca_for_get_late_ctrl( LCA, use, n );
+    }
+  }
+
+  // if this is a load, check for anti-dependent stores
+  // We use a conservative algorithm to identify potential interfering
+  // instructions and for rescheduling the load.  The users of the memory
+  // input of this load are examined.  Any use which is not a load and is
+  // dominated by early is considered a potentially interfering store.
+  // This can produce false positives.
+  if (n->is_Load() && LCA != early) {
+    Node_List worklist;
+
+    Node *mem = n->in(MemNode::Memory);
+    for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
+      Node* s = mem->fast_out(i);
+      worklist.push(s);
+    }
+    while(worklist.size() != 0 && LCA != early) {
+      Node* s = worklist.pop();
+      if (s->is_Load()) {
+        continue;
+      } else if (s->is_MergeMem()) {
+        for (DUIterator_Fast imax, i = s->fast_outs(imax); i < imax; i++) {
+          Node* s1 = s->fast_out(i);
+          worklist.push(s1);
+        }
+      } else {
+        Node *sctrl = has_ctrl(s) ? get_ctrl(s) : s->in(0);
+        assert(sctrl != NULL || s->outcnt() == 0, "must have control");
+        if (sctrl != NULL && !sctrl->is_top() && is_dominator(early, sctrl)) {
+          LCA = dom_lca_for_get_late_ctrl(LCA, sctrl, n);
+        }
+      }
+    }
+  }
+
+  assert(LCA == find_non_split_ctrl(LCA), "unexpected late control");
+  return LCA;
+}
+
+// true if CFG node d dominates CFG node n
+bool PhaseIdealLoop::is_dominator(Node *d, Node *n) {
+  if (d == n)
+    return true;
+  assert(d->is_CFG() && n->is_CFG(), "must have CFG nodes");
+  uint dd = dom_depth(d);
+  while (dom_depth(n) >= dd) {
+    if (n == d)
+      return true;
+    n = idom(n);
+  }
+  return false;
+}
+
+//------------------------------dom_lca_for_get_late_ctrl_internal-------------
+// Pair-wise LCA with tags.
+// Tag each index with the node 'tag' currently being processed
+// before advancing up the dominator chain using idom().
+// Later calls that find a match to 'tag' know that this path has already
+// been considered in the current LCA (which is input 'n1' by convention).
+// Since get_late_ctrl() is only called once for each node, the tag array
+// does not need to be cleared between calls to get_late_ctrl().
+// Algorithm trades a larger constant factor for better asymptotic behavior
+//
+Node *PhaseIdealLoop::dom_lca_for_get_late_ctrl_internal( Node *n1, Node *n2, Node *tag ) {
+  uint d1 = dom_depth(n1);
+  uint d2 = dom_depth(n2);
+
+  do {
+    if (d1 > d2) {
+      // current lca is deeper than n2
+      _dom_lca_tags.map(n1->_idx, tag);
+      n1 =      idom(n1);
+      d1 = dom_depth(n1);
+    } else if (d1 < d2) {
+      // n2 is deeper than current lca
+      Node *memo = _dom_lca_tags[n2->_idx];
+      if( memo == tag ) {
+        return n1;    // Return the current LCA
+      }
+      _dom_lca_tags.map(n2->_idx, tag);
+      n2 =      idom(n2);
+      d2 = dom_depth(n2);
+    } else {
+      // Here d1 == d2.  Due to edits of the dominator-tree, sections
+      // of the tree might have the same depth.  These sections have
+      // to be searched more carefully.
+
+      // Scan up all the n1's with equal depth, looking for n2.
+      _dom_lca_tags.map(n1->_idx, tag);
+      Node *t1 = idom(n1);
+      while (dom_depth(t1) == d1) {
+        if (t1 == n2)  return n2;
+        _dom_lca_tags.map(t1->_idx, tag);
+        t1 = idom(t1);
+      }
+      // Scan up all the n2's with equal depth, looking for n1.
+      _dom_lca_tags.map(n2->_idx, tag);
+      Node *t2 = idom(n2);
+      while (dom_depth(t2) == d2) {
+        if (t2 == n1)  return n1;
+        _dom_lca_tags.map(t2->_idx, tag);
+        t2 = idom(t2);
+      }
+      // Move up to a new dominator-depth value as well as up the dom-tree.
+      n1 = t1;
+      n2 = t2;
+      d1 = dom_depth(n1);
+      d2 = dom_depth(n2);
+    }
+  } while (n1 != n2);
+  return n1;
+}
+
+//------------------------------init_dom_lca_tags------------------------------
+// Tag could be a node's integer index, 32bits instead of 64bits in some cases
+// Intended use does not involve any growth for the array, so it could
+// be of fixed size.
+void PhaseIdealLoop::init_dom_lca_tags() {
+  uint limit = C->unique() + 1;
+  _dom_lca_tags.map( limit, NULL );
+#ifdef ASSERT
+  for( uint i = 0; i < limit; ++i ) {
+    assert(_dom_lca_tags[i] == NULL, "Must be distinct from each node pointer");
+  }
+#endif // ASSERT
+}
+
+//------------------------------clear_dom_lca_tags------------------------------
+// Tag could be a node's integer index, 32bits instead of 64bits in some cases
+// Intended use does not involve any growth for the array, so it could
+// be of fixed size.
+void PhaseIdealLoop::clear_dom_lca_tags() {
+  uint limit = C->unique() + 1;
+  _dom_lca_tags.map( limit, NULL );
+  _dom_lca_tags.clear();
+#ifdef ASSERT
+  for( uint i = 0; i < limit; ++i ) {
+    assert(_dom_lca_tags[i] == NULL, "Must be distinct from each node pointer");
+  }
+#endif // ASSERT
+}
+
+//------------------------------build_loop_late--------------------------------
+// Put Data nodes into some loop nest, by setting the _nodes[]->loop mapping.
+// Second pass finds latest legal placement, and ideal loop placement.
+void PhaseIdealLoop::build_loop_late( VectorSet &visited, Node_List &worklist, Node_Stack &nstack, const PhaseIdealLoop *verify_me ) {
+  while (worklist.size() != 0) {
+    Node *n = worklist.pop();
+    // Only visit once
+    if (visited.test_set(n->_idx)) continue;
+    uint cnt = n->outcnt();
+    uint   i = 0;
+    while (true) {
+      assert( _nodes[n->_idx], "no dead nodes" );
+      // Visit all children
+      if (i < cnt) {
+        Node* use = n->raw_out(i);
+        ++i;
+        // Check for dead uses.  Aggressively prune such junk.  It might be
+        // dead in the global sense, but still have local uses so I cannot
+        // easily call 'remove_dead_node'.
+        if( _nodes[use->_idx] != NULL || use->is_top() ) { // Not dead?
+          // Due to cycles, we might not hit the same fixed point in the verify
+          // pass as we do in the regular pass.  Instead, visit such phis as
+          // simple uses of the loop head.
+          if( use->in(0) && (use->is_CFG() || use->is_Phi()) ) {
+            if( !visited.test(use->_idx) )
+              worklist.push(use);
+          } else if( !visited.test_set(use->_idx) ) {
+            nstack.push(n, i); // Save parent and next use's index.
+            n   = use;         // Process all children of current use.
+            cnt = use->outcnt();
+            i   = 0;
+          }
+        } else {
+          // Do not visit around the backedge of loops via data edges.
+          // push dead code onto a worklist
+          _deadlist.push(use);
+        }
+      } else {
+        // All of n's children have been processed, complete post-processing.
+        build_loop_late_post(n, verify_me);
+        if (nstack.is_empty()) {
+          // Finished all nodes on stack.
+          // Process next node on the worklist.
+          break;
+        }
+        // Get saved parent node and next use's index. Visit the rest of uses.
+        n   = nstack.node();
+        cnt = n->outcnt();
+        i   = nstack.index();
+        nstack.pop();
+      }
+    }
+  }
+}
+
+//------------------------------build_loop_late_post---------------------------
+// Put Data nodes into some loop nest, by setting the _nodes[]->loop mapping.
+// Second pass finds latest legal placement, and ideal loop placement.
+void PhaseIdealLoop::build_loop_late_post( Node *n, const PhaseIdealLoop *verify_me ) {
+
+  if (n->req() == 2 && n->Opcode() == Op_ConvI2L && !C->major_progress()) {
+    _igvn._worklist.push(n);  // Maybe we'll normalize it, if no more loops.
+  }
+
+  // CFG and pinned nodes already handled
+  if( n->in(0) ) {
+    if( n->in(0)->is_top() ) return; // Dead?
+
+    // We'd like +VerifyLoopOptimizations to not believe that Mod's/Loads
+    // _must_ be pinned (they have to observe their control edge of course).
+    // Unlike Stores (which modify an unallocable resource, the memory
+    // state), Mods/Loads can float around.  So free them up.
+    bool pinned = true;
+    switch( n->Opcode() ) {
+    case Op_DivI:
+    case Op_DivF:
+    case Op_DivD:
+    case Op_ModI:
+    case Op_ModF:
+    case Op_ModD:
+    case Op_LoadB:              // Same with Loads; they can sink
+    case Op_LoadC:              // during loop optimizations.
+    case Op_LoadD:
+    case Op_LoadF:
+    case Op_LoadI:
+    case Op_LoadKlass:
+    case Op_LoadL:
+    case Op_LoadS:
+    case Op_LoadP:
+    case Op_LoadRange:
+    case Op_LoadD_unaligned:
+    case Op_LoadL_unaligned:
+    case Op_StrComp:            // Does a bunch of load-like effects
+      pinned = false;
+    }
+    if( pinned ) {
+      IdealLoopTree *choosen_loop = get_loop(n->is_CFG() ? n : get_ctrl(n));
+      if( !choosen_loop->_child )       // Inner loop?
+        choosen_loop->_body.push(n); // Collect inner loops
+      return;
+    }
+  } else {                      // No slot zero
+    if( n->is_CFG() ) {         // CFG with no slot 0 is dead
+      _nodes.map(n->_idx,0);    // No block setting, it's globally dead
+      return;
+    }
+    assert(!n->is_CFG() || n->outcnt() == 0, "");
+  }
+
+  // Do I have a "safe range" I can select over?
+  Node *early = get_ctrl(n);// Early location already computed
+
+  // Compute latest point this Node can go
+  Node *LCA = get_late_ctrl( n, early );
+  // LCA is NULL due to uses being dead
+  if( LCA == NULL ) {
+#ifdef ASSERT
+    for (DUIterator i1 = n->outs(); n->has_out(i1); i1++) {
+      assert( _nodes[n->out(i1)->_idx] == NULL, "all uses must also be dead");
+    }
+#endif
+    _nodes.map(n->_idx, 0);     // This node is useless
+    _deadlist.push(n);
+    return;
+  }
+  assert(LCA != NULL && !LCA->is_top(), "no dead nodes");
+
+  Node *legal = LCA;            // Walk 'legal' up the IDOM chain
+  Node *least = legal;          // Best legal position so far
+  while( early != legal ) {     // While not at earliest legal
+    // Find least loop nesting depth
+    legal = idom(legal);        // Bump up the IDOM tree
+    // Check for lower nesting depth
+    if( get_loop(legal)->_nest < get_loop(least)->_nest )
+      least = legal;
+  }
+
+  // Try not to place code on a loop entry projection
+  // which can inhibit range check elimination.
+  if (least != early) {
+    Node* ctrl_out = least->unique_ctrl_out();
+    if (ctrl_out && ctrl_out->is_CountedLoop() &&
+        least == ctrl_out->in(LoopNode::EntryControl)) {
+      Node* least_dom = idom(least);
+      if (get_loop(least_dom)->is_member(get_loop(least))) {
+        least = least_dom;
+      }
+    }
+  }
+
+#ifdef ASSERT
+  // If verifying, verify that 'verify_me' has a legal location
+  // and choose it as our location.
+  if( verify_me ) {
+    Node *v_ctrl = verify_me->get_ctrl_no_update(n);
+    Node *legal = LCA;
+    while( early != legal ) {   // While not at earliest legal
+      if( legal == v_ctrl ) break;  // Check for prior good location
+      legal = idom(legal)      ;// Bump up the IDOM tree
+    }
+    // Check for prior good location
+    if( legal == v_ctrl ) least = legal; // Keep prior if found
+  }
+#endif
+
+  // Assign discovered "here or above" point
+  least = find_non_split_ctrl(least);
+  set_ctrl(n, least);
+
+  // Collect inner loop bodies
+  IdealLoopTree *choosen_loop = get_loop(least);
+  if( !choosen_loop->_child )   // Inner loop?
+    choosen_loop->_body.push(n);// Collect inner loops
+}
+
+#ifndef PRODUCT
+//------------------------------dump-------------------------------------------
+void PhaseIdealLoop::dump( ) const {
+  ResourceMark rm;
+  Arena* arena = Thread::current()->resource_area();
+  Node_Stack stack(arena, C->unique() >> 2);
+  Node_List rpo_list;
+  VectorSet visited(arena);
+  visited.set(C->top()->_idx);
+  rpo( C->root(), stack, visited, rpo_list );
+  // Dump root loop indexed by last element in PO order
+  dump( _ltree_root, rpo_list.size(), rpo_list );
+}
+
+void PhaseIdealLoop::dump( IdealLoopTree *loop, uint idx, Node_List &rpo_list ) const {
+
+  // Indent by loop nesting depth
+  for( uint x = 0; x < loop->_nest; x++ )
+    tty->print("  ");
+  tty->print_cr("---- Loop N%d-N%d ----", loop->_head->_idx,loop->_tail->_idx);
+
+  // Now scan for CFG nodes in the same loop
+  for( uint j=idx; j > 0;  j-- ) {
+    Node *n = rpo_list[j-1];
+    if( !_nodes[n->_idx] )      // Skip dead nodes
+      continue;
+    if( get_loop(n) != loop ) { // Wrong loop nest
+      if( get_loop(n)->_head == n &&    // Found nested loop?
+          get_loop(n)->_parent == loop )
+        dump(get_loop(n),rpo_list.size(),rpo_list);     // Print it nested-ly
+      continue;
+    }
+
+    // Dump controlling node
+    for( uint x = 0; x < loop->_nest; x++ )
+      tty->print("  ");
+    tty->print("C");
+    if( n == C->root() ) {
+      n->dump();
+    } else {
+      Node* cached_idom   = idom_no_update(n);
+      Node *computed_idom = n->in(0);
+      if( n->is_Region() ) {
+        computed_idom = compute_idom(n);
+        // computed_idom() will return n->in(0) when idom(n) is an IfNode (or
+        // any MultiBranch ctrl node), so apply a similar transform to
+        // the cached idom returned from idom_no_update.
+        cached_idom = find_non_split_ctrl(cached_idom);
+      }
+      tty->print(" ID:%d",computed_idom->_idx);
+      n->dump();
+      if( cached_idom != computed_idom ) {
+        tty->print_cr("*** BROKEN IDOM!  Computed as: %d, cached as: %d",
+                      computed_idom->_idx, cached_idom->_idx);
+      }
+    }
+    // Dump nodes it controls
+    for( uint k = 0; k < _nodes.Size(); k++ ) {
+      // (k < C->unique() && get_ctrl(find(k)) == n)
+      if (k < C->unique() && _nodes[k] == (Node*)((intptr_t)n + 1)) {
+        Node *m = C->root()->find(k);
+        if( m && m->outcnt() > 0 ) {
+          if (!(has_ctrl(m) && get_ctrl_no_update(m) == n)) {
+            tty->print_cr("*** BROKEN CTRL ACCESSOR!  _nodes[k] is %p, ctrl is %p",
+                          _nodes[k], has_ctrl(m) ? get_ctrl_no_update(m) : NULL);
+          }
+          for( uint j = 0; j < loop->_nest; j++ )
+            tty->print("  ");
+          tty->print(" ");
+          m->dump();
+        }
+      }
+    }
+  }
+}
+
+// Collect a R-P-O for the whole CFG.
+// Result list is in post-order (scan backwards for RPO)
+void PhaseIdealLoop::rpo( Node *start, Node_Stack &stk, VectorSet &visited, Node_List &rpo_list ) const {
+  stk.push(start, 0);
+  visited.set(start->_idx);
+
+  while (stk.is_nonempty()) {
+    Node* m   = stk.node();
+    uint  idx = stk.index();
+    if (idx < m->outcnt()) {
+      stk.set_index(idx + 1);
+      Node* n = m->raw_out(idx);
+      if (n->is_CFG() && !visited.test_set(n->_idx)) {
+        stk.push(n, 0);
+      }
+    } else {
+      rpo_list.push(m);
+      stk.pop();
+    }
+  }
+}
+#endif
+
+
+//=============================================================================
+//------------------------------LoopTreeIterator-----------------------------------
+
+// Advance to next loop tree using a preorder, left-to-right traversal.
+void LoopTreeIterator::next() {
+  assert(!done(), "must not be done.");
+  if (_curnt->_child != NULL) {
+    _curnt = _curnt->_child;
+  } else if (_curnt->_next != NULL) {
+    _curnt = _curnt->_next;
+  } else {
+    while (_curnt != _root && _curnt->_next == NULL) {
+      _curnt = _curnt->_parent;
+    }
+    if (_curnt == _root) {
+      _curnt = NULL;
+      assert(done(), "must be done.");
+    } else {
+      assert(_curnt->_next != NULL, "must be more to do");
+      _curnt = _curnt->_next;
+    }
+  }
+}