7004535: Clone loop predicate during loop unswitch

Summary: Clone loop predicate for clonned loops
Reviewed-by: never

src/share/vm/opto/cfgnode.cpp

@@ -1349,9 +1349,17 @@ static Node* is_absolute( PhaseGVN *phase, PhiNode *phi_root, int true_path) {
 static void split_once(PhaseIterGVN *igvn, Node *phi, Node *val, Node *n, Node *newn) {
   igvn->hash_delete(n);         // Remove from hash before hacking edges
 
+  Node* predicate_proj = NULL;
   uint j = 1;
-  for( uint i = phi->req()-1; i > 0; i-- ) {
-    if( phi->in(i) == val ) {   // Found a path with val?
+  for (uint i = phi->req()-1; i > 0; i--) {
+    if (phi->in(i) == val) {   // Found a path with val?
+      if (n->is_Region()) {
+        Node* proj = PhaseIdealLoop::find_predicate(n->in(i));
+        if (proj != NULL) {
+          assert(predicate_proj == NULL, "only one predicate entry expected");
+          predicate_proj = proj;
+        }
+      }
       // Add to NEW Region/Phi, no DU info
       newn->set_req( j++, n->in(i) );
       // Remove from OLD Region/Phi
@@ -1362,6 +1370,12 @@ static void split_once(PhaseIterGVN *igvn, Node *phi, Node *val, Node *n, Node *
   // Register the new node but do not transform it.  Cannot transform until the
   // entire Region/Phi conglomerate has been hacked as a single huge transform.
   igvn->register_new_node_with_optimizer( newn );
+
+  // Clone loop predicates
+  if (predicate_proj != NULL) {
+    newn = igvn->clone_loop_predicates(predicate_proj, newn);
+  }
+
   // Now I can point to the new node.
   n->add_req(newn);
   igvn->_worklist.push(n);

src/share/vm/opto/compile.cpp

@@ -1632,7 +1632,6 @@ void Compile::cleanup_loop_predicates(PhaseIterGVN &igvn) {
     igvn.replace_node(n, n->in(1));
   }
   assert(predicate_count()==0, "should be clean!");
-  igvn.optimize();
 }
 
 //------------------------------Optimize---------------------------------------
@@ -1689,7 +1688,7 @@ void Compile::Optimize() {
   if((loop_opts_cnt > 0) && (has_loops() || has_split_ifs())) {
     {
       TracePhase t2("idealLoop", &_t_idealLoop, true);
-      PhaseIdealLoop ideal_loop( igvn, true, UseLoopPredicate);
+      PhaseIdealLoop ideal_loop( igvn, true );
       loop_opts_cnt--;
       if (major_progress()) print_method("PhaseIdealLoop 1", 2);
       if (failing())  return;
@@ -1697,7 +1696,7 @@ void Compile::Optimize() {
     // Loop opts pass if partial peeling occurred in previous pass
     if(PartialPeelLoop && major_progress() && (loop_opts_cnt > 0)) {
       TracePhase t3("idealLoop", &_t_idealLoop, true);
-      PhaseIdealLoop ideal_loop( igvn, false, UseLoopPredicate);
+      PhaseIdealLoop ideal_loop( igvn, false );
       loop_opts_cnt--;
       if (major_progress()) print_method("PhaseIdealLoop 2", 2);
       if (failing())  return;
@@ -1705,7 +1704,7 @@ void Compile::Optimize() {
     // Loop opts pass for loop-unrolling before CCP
     if(major_progress() && (loop_opts_cnt > 0)) {
       TracePhase t4("idealLoop", &_t_idealLoop, true);
-      PhaseIdealLoop ideal_loop( igvn, false, UseLoopPredicate);
+      PhaseIdealLoop ideal_loop( igvn, false );
       loop_opts_cnt--;
       if (major_progress()) print_method("PhaseIdealLoop 3", 2);
     }
@@ -1743,21 +1742,13 @@ void Compile::Optimize() {
   // peeling, unrolling, etc.
   if(loop_opts_cnt > 0) {
     debug_only( int cnt = 0; );
-    bool loop_predication = UseLoopPredicate;
     while(major_progress() && (loop_opts_cnt > 0)) {
       TracePhase t2("idealLoop", &_t_idealLoop, true);
       assert( cnt++ < 40, "infinite cycle in loop optimization" );
-      PhaseIdealLoop ideal_loop( igvn, true, loop_predication);
+      PhaseIdealLoop ideal_loop( igvn, true);
       loop_opts_cnt--;
       if (major_progress()) print_method("PhaseIdealLoop iterations", 2);
       if (failing())  return;
-      // Perform loop predication optimization during first iteration after CCP.
-      // After that switch it off and cleanup unused loop predicates.
-      if (loop_predication) {
-        loop_predication = false;
-        cleanup_loop_predicates(igvn);
-        if (failing())  return;
-      }
     }
   }
 

src/share/vm/opto/compile.hpp

@@ -489,6 +489,9 @@ class Compile : public Phase {
   // remove the opaque nodes that protect the predicates so that the unused checks and
   // uncommon traps will be eliminated from the graph.
   void cleanup_loop_predicates(PhaseIterGVN &igvn);
+  bool is_predicate_opaq(Node * n) {
+    return _predicate_opaqs->contains(n);
+  }
 
   // Compilation environment.
   Arena*            comp_arena()                { return &_comp_arena; }

src/share/vm/opto/ifnode.cpp

@@ -27,6 +27,7 @@
 #include "opto/addnode.hpp"
 #include "opto/cfgnode.hpp"
 #include "opto/connode.hpp"
+#include "opto/loopnode.hpp"
 #include "opto/phaseX.hpp"
 #include "opto/runtime.hpp"
 #include "opto/subnode.hpp"
@@ -222,22 +223,35 @@ static Node* split_if(IfNode *iff, PhaseIterGVN *igvn) {
 
   // Make a region merging constants and a region merging the rest
   uint req_c = 0;
+  Node* predicate_proj = NULL;
   for (uint ii = 1; ii < r->req(); ii++) {
-    if( phi->in(ii) == con1 ) {
+    if (phi->in(ii) == con1) {
       req_c++;
     }
+    Node* proj = PhaseIdealLoop::find_predicate(r->in(ii));
+    if (proj != NULL) {
+      assert(predicate_proj == NULL, "only one predicate entry expected");
+      predicate_proj = proj;
+    }
   }
+  Node* predicate_c = NULL;
+  Node* predicate_x = NULL;
+
   Node *region_c = new (igvn->C, req_c + 1) RegionNode(req_c + 1);
   Node *phi_c    = con1;
   uint  len      = r->req();
-  Node *region_x = new (igvn->C, len - req_c + 1) RegionNode(len - req_c + 1);
+  Node *region_x = new (igvn->C, len - req_c) RegionNode(len - req_c);
   Node *phi_x    = PhiNode::make_blank(region_x, phi);
   for (uint i = 1, i_c = 1, i_x = 1; i < len; i++) {
-    if( phi->in(i) == con1 ) {
+    if (phi->in(i) == con1) {
       region_c->init_req( i_c++, r  ->in(i) );
+      if (r->in(i) == predicate_proj)
+        predicate_c = predicate_proj;
     } else {
       region_x->init_req( i_x,   r  ->in(i) );
       phi_x   ->init_req( i_x++, phi->in(i) );
+      if (r->in(i) == predicate_proj)
+        predicate_x = predicate_proj;
     }
   }
 
@@ -277,8 +291,20 @@ static Node* split_if(IfNode *iff, PhaseIterGVN *igvn) {
   // Make the true/false arms
   Node *iff_c_t = phase->transform(new (igvn->C, 1) IfTrueNode (iff_c));
   Node *iff_c_f = phase->transform(new (igvn->C, 1) IfFalseNode(iff_c));
+  if (predicate_c != NULL) {
+    assert(predicate_x == NULL, "only one predicate entry expected");
+    // Clone loop predicates to each path
+    iff_c_t = igvn->clone_loop_predicates(predicate_c, iff_c_t);
+    iff_c_f = igvn->clone_loop_predicates(predicate_c, iff_c_f);
+  }
   Node *iff_x_t = phase->transform(new (igvn->C, 1) IfTrueNode (iff_x));
   Node *iff_x_f = phase->transform(new (igvn->C, 1) IfFalseNode(iff_x));
+  if (predicate_x != NULL) {
+    assert(predicate_c == NULL, "only one predicate entry expected");
+    // Clone loop predicates to each path
+    iff_x_t = igvn->clone_loop_predicates(predicate_x, iff_x_t);
+    iff_x_f = igvn->clone_loop_predicates(predicate_x, iff_x_f);
+  }
 
   // Merge the TRUE paths
   Node *region_s = new (igvn->C, 3) RegionNode(3);

src/share/vm/opto/loopPredicate.cpp

+/*
+ * Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#include "precompiled.hpp"
+#include "opto/loopnode.hpp"
+#include "opto/addnode.hpp"
+#include "opto/callnode.hpp"
+#include "opto/connode.hpp"
+#include "opto/loopnode.hpp"
+#include "opto/mulnode.hpp"
+#include "opto/rootnode.hpp"
+#include "opto/subnode.hpp"
+
+/*
+ * The general idea of Loop Predication is to insert a predicate on the entry
+ * path to a loop, and raise a uncommon trap if the check of the condition fails.
+ * The condition checks are promoted from inside the loop body, and thus
+ * the checks inside the loop could be eliminated. Currently, loop predication
+ * optimization has been applied to remove array range check and loop invariant
+ * checks (such as null checks).
+*/
+
+//-------------------------------is_uncommon_trap_proj----------------------------
+// Return true if proj is the form of "proj->[region->..]call_uct"
+bool PhaseIdealLoop::is_uncommon_trap_proj(ProjNode* proj, Deoptimization::DeoptReason reason) {
+  int path_limit = 10;
+  assert(proj, "invalid argument");
+  Node* out = proj;
+  for (int ct = 0; ct < path_limit; ct++) {
+    out = out->unique_ctrl_out();
+    if (out == NULL)
+      return false;
+    if (out->is_CallStaticJava()) {
+      int req = out->as_CallStaticJava()->uncommon_trap_request();
+      if (req != 0) {
+        Deoptimization::DeoptReason trap_reason = Deoptimization::trap_request_reason(req);
+        if (trap_reason == reason || reason == Deoptimization::Reason_none) {
+           return true;
+        }
+      }
+      return false; // don't do further after call
+    }
+    if (out->Opcode() != Op_Region)
+      return false;
+  }
+  return false;
+}
+
+//-------------------------------is_uncommon_trap_if_pattern-------------------------
+// Return true  for "if(test)-> proj -> ...
+//                          |
+//                          V
+//                      other_proj->[region->..]call_uct"
+//
+// "must_reason_predicate" means the uct reason must be Reason_predicate
+bool PhaseIdealLoop::is_uncommon_trap_if_pattern(ProjNode *proj, Deoptimization::DeoptReason reason) {
+  Node *in0 = proj->in(0);
+  if (!in0->is_If()) return false;
+  // Variation of a dead If node.
+  if (in0->outcnt() < 2)  return false;
+  IfNode* iff = in0->as_If();
+
+  // we need "If(Conv2B(Opaque1(...)))" pattern for reason_predicate
+  if (reason != Deoptimization::Reason_none) {
+    if (iff->in(1)->Opcode() != Op_Conv2B ||
+       iff->in(1)->in(1)->Opcode() != Op_Opaque1) {
+      return false;
+    }
+  }
+
+  ProjNode* other_proj = iff->proj_out(1-proj->_con)->as_Proj();
+  if (is_uncommon_trap_proj(other_proj, reason)) {
+    assert(reason == Deoptimization::Reason_none ||
+           Compile::current()->is_predicate_opaq(iff->in(1)->in(1)), "should be on the list");
+    return true;
+  }
+  return false;
+}
+
+//-------------------------------register_control-------------------------
+void PhaseIdealLoop::register_control(Node* n, IdealLoopTree *loop, Node* pred) {
+  assert(n->is_CFG(), "must be control node");
+  _igvn.register_new_node_with_optimizer(n);
+  loop->_body.push(n);
+  set_loop(n, loop);
+  // When called from beautify_loops() idom is not constructed yet.
+  if (_idom != NULL) {
+    set_idom(n, pred, dom_depth(pred));
+  }
+}
+
+//------------------------------create_new_if_for_predicate------------------------
+// create a new if above the uct_if_pattern for the predicate to be promoted.
+//
+//          before                                after
+//        ----------                           ----------
+//           ctrl                                 ctrl
+//            |                                     |
+//            |                                     |
+//            v                                     v
+//           iff                                 new_iff
+//          /    \                                /      \
+//         /      \                              /        \
+//        v        v                            v          v
+//  uncommon_proj cont_proj                   if_uct     if_cont
+// \      |        |                           |          |
+//  \     |        |                           |          |
+//   v    v        v                           |          v
+//     rgn       loop                          |         iff
+//      |                                      |        /     \
+//      |                                      |       /       \
+//      v                                      |      v         v
+// uncommon_trap                               | uncommon_proj cont_proj
+//                                           \  \    |           |
+//                                            \  \   |           |
+//                                             v  v  v           v
+//                                               rgn           loop
+//                                                |
+//                                                |
+//                                                v
+//                                           uncommon_trap
+//
+//
+// We will create a region to guard the uct call if there is no one there.
+// The true projecttion (if_cont) of the new_iff is returned.
+// This code is also used to clone predicates to clonned loops.
+ProjNode* PhaseIdealLoop::create_new_if_for_predicate(ProjNode* cont_proj, Node* new_entry,
+                                                      Deoptimization::DeoptReason reason) {
+  assert(is_uncommon_trap_if_pattern(cont_proj, reason), "must be a uct if pattern!");
+  IfNode* iff = cont_proj->in(0)->as_If();
+
+  ProjNode *uncommon_proj = iff->proj_out(1 - cont_proj->_con);
+  Node     *rgn   = uncommon_proj->unique_ctrl_out();
+  assert(rgn->is_Region() || rgn->is_Call(), "must be a region or call uct");
+
+  uint proj_index = 1; // region's edge corresponding to uncommon_proj
+  if (!rgn->is_Region()) { // create a region to guard the call
+    assert(rgn->is_Call(), "must be call uct");
+    CallNode* call = rgn->as_Call();
+    IdealLoopTree* loop = get_loop(call);
+    rgn = new (C, 1) RegionNode(1);
+    rgn->add_req(uncommon_proj);
+    register_control(rgn, loop, uncommon_proj);
+    _igvn.hash_delete(call);
+    call->set_req(0, rgn);
+    // When called from beautify_loops() idom is not constructed yet.
+    if (_idom != NULL) {
+      set_idom(call, rgn, dom_depth(rgn));
+    }
+  } else {
+    // Find region's edge corresponding to uncommon_proj
+    for (; proj_index < rgn->req(); proj_index++)
+      if (rgn->in(proj_index) == uncommon_proj) break;
+    assert(proj_index < rgn->req(), "sanity");
+  }
+
+  Node* entry = iff->in(0);
+  if (new_entry != NULL) {
+    // Clonning the predicate to new location.
+    entry = new_entry;
+  }
+  // Create new_iff
+  IdealLoopTree* lp = get_loop(entry);
+  IfNode *new_iff = iff->clone()->as_If();
+  new_iff->set_req(0, entry);
+  register_control(new_iff, lp, entry);
+  Node *if_cont = new (C, 1) IfTrueNode(new_iff);
+  Node *if_uct  = new (C, 1) IfFalseNode(new_iff);
+  if (cont_proj->is_IfFalse()) {
+    // Swap
+    Node* tmp = if_uct; if_uct = if_cont; if_cont = tmp;
+  }
+  register_control(if_cont, lp, new_iff);
+  register_control(if_uct, get_loop(rgn), new_iff);
+
+  // if_uct to rgn
+  _igvn.hash_delete(rgn);
+  rgn->add_req(if_uct);
+  // When called from beautify_loops() idom is not constructed yet.
+  if (_idom != NULL) {
+    Node* ridom = idom(rgn);
+    Node* nrdom = dom_lca(ridom, new_iff);
+    set_idom(rgn, nrdom, dom_depth(rgn));
+  }
+
+  // If rgn has phis add new edges which has the same
+  // value as on original uncommon_proj pass.
+  assert(rgn->in(rgn->req() -1) == if_uct, "new edge should be last");
+  bool has_phi = false;
+  for (DUIterator_Fast imax, i = rgn->fast_outs(imax); i < imax; i++) {
+    Node* use = rgn->fast_out(i);
+    if (use->is_Phi() && use->outcnt() > 0) {
+      assert(use->in(0) == rgn, "");
+      _igvn.hash_delete(use);
+      use->add_req(use->in(proj_index));
+      _igvn._worklist.push(use);
+      has_phi = true;
+    }
+  }
+  assert(!has_phi || rgn->req() > 3, "no phis when region is created");
+
+  if (new_entry == NULL) {
+    // Attach if_cont to iff
+    _igvn.hash_delete(iff);
+    iff->set_req(0, if_cont);
+    if (_idom != NULL) {
+      set_idom(iff, if_cont, dom_depth(iff));
+    }
+  }
+  return if_cont->as_Proj();
+}
+
+//------------------------------create_new_if_for_predicate------------------------
+// Create a new if below new_entry for the predicate to be cloned (IGVN optimization)
+ProjNode* PhaseIterGVN::create_new_if_for_predicate(ProjNode* cont_proj, Node* new_entry,
+                                                    Deoptimization::DeoptReason reason) {
+  assert(new_entry != 0, "only used for clone predicate");
+  assert(PhaseIdealLoop::is_uncommon_trap_if_pattern(cont_proj, reason), "must be a uct if pattern!");
+  IfNode* iff = cont_proj->in(0)->as_If();
+
+  ProjNode *uncommon_proj = iff->proj_out(1 - cont_proj->_con);
+  Node     *rgn   = uncommon_proj->unique_ctrl_out();
+  assert(rgn->is_Region() || rgn->is_Call(), "must be a region or call uct");
+
+  uint proj_index = 1; // region's edge corresponding to uncommon_proj
+  if (!rgn->is_Region()) { // create a region to guard the call
+    assert(rgn->is_Call(), "must be call uct");
+    CallNode* call = rgn->as_Call();
+    rgn = new (C, 1) RegionNode(1);
+    register_new_node_with_optimizer(rgn);
+    rgn->add_req(uncommon_proj);
+    hash_delete(call);
+    call->set_req(0, rgn);
+  } else {
+    // Find region's edge corresponding to uncommon_proj
+    for (; proj_index < rgn->req(); proj_index++)
+      if (rgn->in(proj_index) == uncommon_proj) break;
+    assert(proj_index < rgn->req(), "sanity");
+  }
+
+  // Create new_iff in new location.
+  IfNode *new_iff = iff->clone()->as_If();
+  new_iff->set_req(0, new_entry);
+
+  register_new_node_with_optimizer(new_iff);
+  Node *if_cont = new (C, 1) IfTrueNode(new_iff);
+  Node *if_uct  = new (C, 1) IfFalseNode(new_iff);
+  if (cont_proj->is_IfFalse()) {
+    // Swap
+    Node* tmp = if_uct; if_uct = if_cont; if_cont = tmp;
+  }
+  register_new_node_with_optimizer(if_cont);
+  register_new_node_with_optimizer(if_uct);
+
+  // if_uct to rgn
+  hash_delete(rgn);
+  rgn->add_req(if_uct);
+
+  // If rgn has phis add corresponding new edges which has the same
+  // value as on original uncommon_proj pass.
+  assert(rgn->in(rgn->req() -1) == if_uct, "new edge should be last");
+  bool has_phi = false;
+  for (DUIterator_Fast imax, i = rgn->fast_outs(imax); i < imax; i++) {
+    Node* use = rgn->fast_out(i);
+    if (use->is_Phi() && use->outcnt() > 0) {
+      hash_delete(use);
+      use->add_req(use->in(proj_index));
+      _worklist.push(use);
+      has_phi = true;
+    }
+  }
+  assert(!has_phi || rgn->req() > 3, "no phis when region is created");
+
+  return if_cont->as_Proj();
+}
+
+//--------------------------clone_predicate-----------------------
+ProjNode* PhaseIdealLoop::clone_predicate(ProjNode* predicate_proj, Node* new_entry,
+                                          Deoptimization::DeoptReason reason,
+                                          PhaseIdealLoop* loop_phase,
+                                          PhaseIterGVN* igvn) {
+  ProjNode* new_predicate_proj;
+  if (loop_phase != NULL) {
+    new_predicate_proj = loop_phase->create_new_if_for_predicate(predicate_proj, new_entry, reason);
+  } else {
+    new_predicate_proj =       igvn->create_new_if_for_predicate(predicate_proj, new_entry, reason);
+  }
+  IfNode* iff = new_predicate_proj->in(0)->as_If();
+  Node* ctrl  = iff->in(0);
+
+  // Match original condition since predicate's projections could be swapped.
+  assert(predicate_proj->in(0)->in(1)->in(1)->Opcode()==Op_Opaque1, "must be");
+  Node* opq = new (igvn->C, 2) Opaque1Node(igvn->C, predicate_proj->in(0)->in(1)->in(1)->in(1));
+  igvn->C->add_predicate_opaq(opq);
+
+  Node* bol = new (igvn->C, 2) Conv2BNode(opq);
+  if (loop_phase != NULL) {
+    loop_phase->register_new_node(opq, ctrl);
+    loop_phase->register_new_node(bol, ctrl);
+  } else {
+    igvn->register_new_node_with_optimizer(opq);
+    igvn->register_new_node_with_optimizer(bol);
+  }
+  igvn->hash_delete(iff);
+  iff->set_req(1, bol);
+  return new_predicate_proj;
+}
+
+//--------------------------move_predicate-----------------------
+// Cut predicate from old place and move it to new.
+ProjNode* PhaseIdealLoop::move_predicate(ProjNode* predicate_proj, Node* new_entry,
+                                         Deoptimization::DeoptReason reason,
+                                         PhaseIdealLoop* loop_phase,
+                                         PhaseIterGVN* igvn) {
+  assert(new_entry != NULL, "must be");
+  assert(predicate_proj->in(0)->in(1)->in(1)->Opcode()==Op_Opaque1, "must be");
+  IfNode* iff = predicate_proj->in(0)->as_If();
+  Node* old_entry = iff->in(0);
+
+  // Cut predicate from old place.
+  Node* old = predicate_proj;
+  igvn->_worklist.push(old);
+  for (DUIterator_Last imin, i = old->last_outs(imin); i >= imin; ) {
+    Node* use = old->last_out(i);  // for each use...
+    igvn->hash_delete(use);
+    igvn->_worklist.push(use);
+    // Update use-def info
+    uint uses_found = 0;
+    for (uint j = 0; j < use->req(); j++) {
+      if (use->in(j) == old) {
+        use->set_req(j, old_entry);
+        uses_found++;
+        if (loop_phase != NULL) {
+          if (use->is_CFG()) {
+            // When called from beautify_loops() idom is not constructed yet.
+            if (loop_phase->_idom != NULL)
+              loop_phase->set_idom(use, old_entry, loop_phase->dom_depth(use));
+          } else {
+            loop_phase->set_ctrl(use, old_entry);
+          }
+        }
+      }
+    }
+    i -= uses_found;    // we deleted 1 or more copies of this edge
+  }
+
+  // Move predicate.
+  igvn->hash_delete(iff);
+  iff->set_req(0, new_entry);
+  igvn->_worklist.push(iff);
+
+  if (loop_phase != NULL) {
+    // Fix up idom and ctrl.
+    loop_phase->set_ctrl(iff->in(1), new_entry);
+    loop_phase->set_ctrl(iff->in(1)->in(1), new_entry);
+    // When called from beautify_loops() idom is not constructed yet.
+    if (loop_phase->_idom != NULL)
+      loop_phase->set_idom(iff, new_entry, loop_phase->dom_depth(iff));
+  }
+
+  return predicate_proj;
+}
+
+//--------------------------clone_loop_predicates-----------------------
+// Interface from IGVN
+Node* PhaseIterGVN::clone_loop_predicates(Node* old_entry, Node* new_entry) {
+  return PhaseIdealLoop::clone_loop_predicates(old_entry, new_entry, false, NULL, this);
+}
+Node* PhaseIterGVN::move_loop_predicates(Node* old_entry, Node* new_entry) {
+  return PhaseIdealLoop::clone_loop_predicates(old_entry, new_entry, true, NULL, this);
+}
+
+// Interface from PhaseIdealLoop
+Node* PhaseIdealLoop::clone_loop_predicates(Node* old_entry, Node* new_entry) {
+  return clone_loop_predicates(old_entry, new_entry, false, this, &this->_igvn);
+}
+Node* PhaseIdealLoop::move_loop_predicates(Node* old_entry, Node* new_entry) {
+  return clone_loop_predicates(old_entry, new_entry, true, this, &this->_igvn);
+}
+
+// Clone loop predicates to cloned loops (peeled, unswitched, split_if).
+Node* PhaseIdealLoop::clone_loop_predicates(Node* old_entry, Node* new_entry,
+                                                bool move_predicates,
+                                                PhaseIdealLoop* loop_phase,
+                                                PhaseIterGVN* igvn) {
+#ifdef ASSERT
+  if (new_entry == NULL || !(new_entry->is_Proj() || new_entry->is_Region() || new_entry->is_SafePoint())) {
+    if (new_entry != NULL)
+      new_entry->dump();
+    assert(false, "not IfTrue, IfFalse, Region or SafePoint");
+  }
+#endif
+  // Search original predicates
+  Node* entry = old_entry;
+  if (UseLoopPredicate) {
+    ProjNode* predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
+    if (predicate_proj != NULL) { // right pattern that can be used by loop predication
+      assert(entry->in(0)->in(1)->in(1)->Opcode()==Op_Opaque1, "must be");
+      if (move_predicates) {
+        new_entry =  move_predicate(predicate_proj, new_entry,
+                                    Deoptimization::Reason_predicate,
+                                    loop_phase, igvn);
+        assert(new_entry == predicate_proj, "old predicate fall through projection");
+      } else {
+        // clone predicate
+        new_entry = clone_predicate(predicate_proj, new_entry,
+                                    Deoptimization::Reason_predicate,
+                                    loop_phase, igvn);
+        assert(new_entry != NULL && new_entry->is_Proj(), "IfTrue or IfFalse after clone predicate");
+      }
+      if (TraceLoopPredicate) {
+        tty->print_cr("Loop Predicate %s: ", move_predicates ? "moved" : "cloned");
+        debug_only( new_entry->in(0)->dump(); )
+      }
+    }
+  }
+  return new_entry;
+}
+
+//--------------------------eliminate_loop_predicates-----------------------
+void PhaseIdealLoop::eliminate_loop_predicates(Node* entry) {
+  if (UseLoopPredicate) {
+    ProjNode* predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
+    if (predicate_proj != NULL) { // right pattern that can be used by loop predication
+      Node* n = entry->in(0)->in(1)->in(1);
+      assert(n->Opcode()==Op_Opaque1, "must be");
+      // Remove Opaque1 node from predicates list.
+      // IGVN will remove this predicate check.
+      _igvn.replace_node(n, n->in(1));
+    }
+  }
+}
+
+//--------------------------skip_loop_predicates------------------------------
+// Skip related predicates.
+Node* PhaseIdealLoop::skip_loop_predicates(Node* entry) {
+  Node* predicate = NULL;
+  if (UseLoopPredicate) {
+    predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
+    if (predicate != NULL) { // right pattern that can be used by loop predication
+      assert(entry->is_Proj() && entry->in(0)->in(1)->in(1)->Opcode()==Op_Opaque1, "must be");
+      IfNode* iff = entry->in(0)->as_If();
+      ProjNode* uncommon_proj = iff->proj_out(1 - entry->as_Proj()->_con);
+      Node* rgn = uncommon_proj->unique_ctrl_out();
+      assert(rgn->is_Region() || rgn->is_Call(), "must be a region or call uct");
+      entry = entry->in(0)->in(0);
+      while (entry != NULL && entry->is_Proj() && entry->in(0)->is_If()) {
+        uncommon_proj = entry->in(0)->as_If()->proj_out(1 - entry->as_Proj()->_con);
+        if (uncommon_proj->unique_ctrl_out() != rgn)
+          break;
+        entry = entry->in(0)->in(0);
+      }
+    }
+  }
+  return entry;
+}
+
+//--------------------------find_predicate_insertion_point-------------------
+// Find a good location to insert a predicate
+ProjNode* PhaseIdealLoop::find_predicate_insertion_point(Node* start_c, Deoptimization::DeoptReason reason) {
+  if (start_c == NULL || !start_c->is_Proj())
+    return NULL;
+  if (is_uncommon_trap_if_pattern(start_c->as_Proj(), reason)) {
+    return start_c->as_Proj();
+  }
+  return NULL;
+}
+
+//--------------------------find_predicate------------------------------------
+// Find a predicate
+Node* PhaseIdealLoop::find_predicate(Node* entry) {
+  Node* predicate = NULL;
+  if (UseLoopPredicate) {
+    predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
+    if (predicate != NULL) { // right pattern that can be used by loop predication
+      assert(entry->in(0)->in(1)->in(1)->Opcode()==Op_Opaque1, "must be");
+      return entry;
+    }
+  }
+  return NULL;
+}
+
+//------------------------------Invariance-----------------------------------
+// Helper class for loop_predication_impl to compute invariance on the fly and
+// clone invariants.
+class Invariance : public StackObj {
+  VectorSet _visited, _invariant;
+  Node_Stack _stack;
+  VectorSet _clone_visited;
+  Node_List _old_new; // map of old to new (clone)
+  IdealLoopTree* _lpt;
+  PhaseIdealLoop* _phase;
+
+  // Helper function to set up the invariance for invariance computation
+  // If n is a known invariant, set up directly. Otherwise, look up the
+  // the possibility to push n onto the stack for further processing.
+  void visit(Node* use, Node* n) {
+    if (_lpt->is_invariant(n)) { // known invariant
+      _invariant.set(n->_idx);
+    } else if (!n->is_CFG()) {
+      Node *n_ctrl = _phase->ctrl_or_self(n);
+      Node *u_ctrl = _phase->ctrl_or_self(use); // self if use is a CFG
+      if (_phase->is_dominator(n_ctrl, u_ctrl)) {
+        _stack.push(n, n->in(0) == NULL ? 1 : 0);
+      }
+    }
+  }
+
+  // Compute invariance for "the_node" and (possibly) all its inputs recursively
+  // on the fly
+  void compute_invariance(Node* n) {
+    assert(_visited.test(n->_idx), "must be");
+    visit(n, n);
+    while (_stack.is_nonempty()) {
+      Node*  n = _stack.node();
+      uint idx = _stack.index();
+      if (idx == n->req()) { // all inputs are processed
+        _stack.pop();
+        // n is invariant if it's inputs are all invariant
+        bool all_inputs_invariant = true;
+        for (uint i = 0; i < n->req(); i++) {
+          Node* in = n->in(i);
+          if (in == NULL) continue;
+          assert(_visited.test(in->_idx), "must have visited input");
+          if (!_invariant.test(in->_idx)) { // bad guy
+            all_inputs_invariant = false;
+            break;
+          }
+        }
+        if (all_inputs_invariant) {
+          _invariant.set(n->_idx); // I am a invariant too
+        }
+      } else { // process next input
+        _stack.set_index(idx + 1);
+        Node* m = n->in(idx);
+        if (m != NULL && !_visited.test_set(m->_idx)) {
+          visit(n, m);
+        }
+      }
+    }
+  }
+
+  // Helper function to set up _old_new map for clone_nodes.
+  // If n is a known invariant, set up directly ("clone" of n == n).
+  // Otherwise, push n onto the stack for real cloning.
+  void clone_visit(Node* n) {
+    assert(_invariant.test(n->_idx), "must be invariant");
+    if (_lpt->is_invariant(n)) { // known invariant
+      _old_new.map(n->_idx, n);
+    } else { // to be cloned
+      assert(!n->is_CFG(), "should not see CFG here");
+      _stack.push(n, n->in(0) == NULL ? 1 : 0);
+    }
+  }
+
+  // Clone "n" and (possibly) all its inputs recursively
+  void clone_nodes(Node* n, Node* ctrl) {
+    clone_visit(n);
+    while (_stack.is_nonempty()) {
+      Node*  n = _stack.node();
+      uint idx = _stack.index();
+      if (idx == n->req()) { // all inputs processed, clone n!
+        _stack.pop();
+        // clone invariant node
+        Node* n_cl = n->clone();
+        _old_new.map(n->_idx, n_cl);
+        _phase->register_new_node(n_cl, ctrl);
+        for (uint i = 0; i < n->req(); i++) {
+          Node* in = n_cl->in(i);
+          if (in == NULL) continue;
+          n_cl->set_req(i, _old_new[in->_idx]);
+        }
+      } else { // process next input
+        _stack.set_index(idx + 1);
+        Node* m = n->in(idx);
+        if (m != NULL && !_clone_visited.test_set(m->_idx)) {
+          clone_visit(m); // visit the input
+        }
+      }
+    }
+  }
+
+ public:
+  Invariance(Arena* area, IdealLoopTree* lpt) :
+    _lpt(lpt), _phase(lpt->_phase),
+    _visited(area), _invariant(area), _stack(area, 10 /* guess */),
+    _clone_visited(area), _old_new(area)
+  {}
+
+  // Map old to n for invariance computation and clone
+  void map_ctrl(Node* old, Node* n) {
+    assert(old->is_CFG() && n->is_CFG(), "must be");
+    _old_new.map(old->_idx, n); // "clone" of old is n
+    _invariant.set(old->_idx);  // old is invariant
+    _clone_visited.set(old->_idx);
+  }
+
+  // Driver function to compute invariance
+  bool is_invariant(Node* n) {
+    if (!_visited.test_set(n->_idx))
+      compute_invariance(n);
+    return (_invariant.test(n->_idx) != 0);
+  }
+
+  // Driver function to clone invariant
+  Node* clone(Node* n, Node* ctrl) {
+    assert(ctrl->is_CFG(), "must be");
+    assert(_invariant.test(n->_idx), "must be an invariant");
+    if (!_clone_visited.test(n->_idx))
+      clone_nodes(n, ctrl);
+    return _old_new[n->_idx];
+  }
+};
+
+//------------------------------is_range_check_if -----------------------------------
+// Returns true if the predicate of iff is in "scale*iv + offset u< load_range(ptr)" format
+// Note: this function is particularly designed for loop predication. We require load_range
+//       and offset to be loop invariant computed on the fly by "invar"
+bool IdealLoopTree::is_range_check_if(IfNode *iff, PhaseIdealLoop *phase, Invariance& invar) const {
+  if (!is_loop_exit(iff)) {
+    return false;
+  }
+  if (!iff->in(1)->is_Bool()) {
+    return false;
+  }
+  const BoolNode *bol = iff->in(1)->as_Bool();
+  if (bol->_test._test != BoolTest::lt) {
+    return false;
+  }
+  if (!bol->in(1)->is_Cmp()) {
+    return false;
+  }
+  const CmpNode *cmp = bol->in(1)->as_Cmp();
+  if (cmp->Opcode() != Op_CmpU) {
+    return false;
+  }
+  Node* range = cmp->in(2);
+  if (range->Opcode() != Op_LoadRange) {
+    const TypeInt* tint = phase->_igvn.type(range)->isa_int();
+    if (!OptimizeFill || tint == NULL || tint->empty() || tint->_lo < 0) {
+      // Allow predication on positive values that aren't LoadRanges.
+      // This allows optimization of loops where the length of the
+      // array is a known value and doesn't need to be loaded back
+      // from the array.
+      return false;
+    }
+  }
+  if (!invar.is_invariant(range)) {
+    return false;
+  }
+  Node *iv     = _head->as_CountedLoop()->phi();
+  int   scale  = 0;
+  Node *offset = NULL;
+  if (!phase->is_scaled_iv_plus_offset(cmp->in(1), iv, &scale, &offset)) {
+    return false;
+  }
+  if (offset && !invar.is_invariant(offset)) { // offset must be invariant
+    return false;
+  }
+  return true;
+}
+
+//------------------------------rc_predicate-----------------------------------
+// Create a range check predicate
+//
+// for (i = init; i < limit; i += stride) {
+//    a[scale*i+offset]
+// }
+//
+// Compute max(scale*i + offset) for init <= i < limit and build the predicate
+// as "max(scale*i + offset) u< a.length".
+//
+// There are two cases for max(scale*i + offset):
+// (1) stride*scale > 0
+//   max(scale*i + offset) = scale*(limit-stride) + offset
+// (2) stride*scale < 0
+//   max(scale*i + offset) = scale*init + offset
+BoolNode* PhaseIdealLoop::rc_predicate(Node* ctrl,
+                                       int scale, Node* offset,
+                                       Node* init, Node* limit, Node* stride,
+                                       Node* range, bool upper) {
+  DEBUG_ONLY(ttyLocker ttyl);
+  if (TraceLoopPredicate) tty->print("rc_predicate ");
+
+  Node* max_idx_expr  = init;
+  int stride_con = stride->get_int();
+  if ((stride_con > 0) == (scale > 0) == upper) {
+    max_idx_expr = new (C, 3) SubINode(limit, stride);
+    register_new_node(max_idx_expr, ctrl);
+    if (TraceLoopPredicate) tty->print("(limit - stride) ");
+  } else {
+    if (TraceLoopPredicate) tty->print("init ");
+  }
+
+  if (scale != 1) {
+    ConNode* con_scale = _igvn.intcon(scale);
+    max_idx_expr = new (C, 3) MulINode(max_idx_expr, con_scale);
+    register_new_node(max_idx_expr, ctrl);
+    if (TraceLoopPredicate) tty->print("* %d ", scale);
+  }
+
+  if (offset && (!offset->is_Con() || offset->get_int() != 0)){
+    max_idx_expr = new (C, 3) AddINode(max_idx_expr, offset);
+    register_new_node(max_idx_expr, ctrl);
+    if (TraceLoopPredicate)
+      if (offset->is_Con()) tty->print("+ %d ", offset->get_int());
+      else tty->print("+ offset ");
+  }
+
+  CmpUNode* cmp = new (C, 3) CmpUNode(max_idx_expr, range);
+  register_new_node(cmp, ctrl);
+  BoolNode* bol = new (C, 2) BoolNode(cmp, BoolTest::lt);
+  register_new_node(bol, ctrl);
+
+  if (TraceLoopPredicate) tty->print_cr("<u range");
+  return bol;
+}
+
+//------------------------------ loop_predication_impl--------------------------
+// Insert loop predicates for null checks and range checks
+bool PhaseIdealLoop::loop_predication_impl(IdealLoopTree *loop) {
+  if (!UseLoopPredicate) return false;
+
+  if (!loop->_head->is_Loop()) {
+    // Could be a simple region when irreducible loops are present.
+    return false;
+  }
+
+  if (loop->_head->unique_ctrl_out()->Opcode() == Op_NeverBranch) {
+    // do nothing for infinite loops
+    return false;
+  }
+
+  CountedLoopNode *cl = NULL;
+  if (loop->_head->is_CountedLoop()) {
+    cl = loop->_head->as_CountedLoop();
+    // do nothing for iteration-splitted loops
+    if (!cl->is_normal_loop()) return false;
+  }
+
+  LoopNode *lpn  = loop->_head->as_Loop();
+  Node* entry = lpn->in(LoopNode::EntryControl);
+
+  ProjNode *predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
+  if (!predicate_proj) {
+#ifndef PRODUCT
+    if (TraceLoopPredicate) {
+      tty->print("missing predicate:");
+      loop->dump_head();
+      lpn->dump(1);
+    }
+#endif
+    return false;
+  }
+  ConNode* zero = _igvn.intcon(0);
+  set_ctrl(zero, C->root());
+
+  ResourceArea *area = Thread::current()->resource_area();
+  Invariance invar(area, loop);
+
+  // Create list of if-projs such that a newer proj dominates all older
+  // projs in the list, and they all dominate loop->tail()
+  Node_List if_proj_list(area);
+  LoopNode *head  = loop->_head->as_Loop();
+  Node *current_proj = loop->tail(); //start from tail
+  while (current_proj != head) {
+    if (loop == get_loop(current_proj) && // still in the loop ?
+        current_proj->is_Proj()        && // is a projection  ?
+        current_proj->in(0)->Opcode() == Op_If) { // is a if projection ?
+      if_proj_list.push(current_proj);
+    }
+    current_proj = idom(current_proj);
+  }
+
+  bool hoisted = false; // true if at least one proj is promoted
+  while (if_proj_list.size() > 0) {
+    // Following are changed to nonnull when a predicate can be hoisted
+    ProjNode* new_predicate_proj = NULL;
+
+    ProjNode* proj = if_proj_list.pop()->as_Proj();
+    IfNode*   iff  = proj->in(0)->as_If();
+
+    if (!is_uncommon_trap_if_pattern(proj, Deoptimization::Reason_none)) {
+      if (loop->is_loop_exit(iff)) {
+        // stop processing the remaining projs in the list because the execution of them
+        // depends on the condition of "iff" (iff->in(1)).
+        break;
+      } else {
+        // Both arms are inside the loop. There are two cases:
+        // (1) there is one backward branch. In this case, any remaining proj
+        //     in the if_proj list post-dominates "iff". So, the condition of "iff"
+        //     does not determine the execution the remining projs directly, and we
+        //     can safely continue.
+        // (2) both arms are forwarded, i.e. a diamond shape. In this case, "proj"
+        //     does not dominate loop->tail(), so it can not be in the if_proj list.
+        continue;
+      }
+    }
+
+    Node*     test = iff->in(1);
+    if (!test->is_Bool()){ //Conv2B, ...
+      continue;
+    }
+    BoolNode* bol = test->as_Bool();
+    if (invar.is_invariant(bol)) {
+      // Invariant test
+      new_predicate_proj = create_new_if_for_predicate(predicate_proj, NULL,
+                                                       Deoptimization::Reason_predicate);
+      Node* ctrl = new_predicate_proj->in(0)->as_If()->in(0);
+      BoolNode* new_predicate_bol = invar.clone(bol, ctrl)->as_Bool();
+
+      // Negate test if necessary
+      bool negated = false;
+      if (proj->_con != predicate_proj->_con) {
+        new_predicate_bol = new (C, 2) BoolNode(new_predicate_bol->in(1), new_predicate_bol->_test.negate());
+        register_new_node(new_predicate_bol, ctrl);
+        negated = true;
+      }
+      IfNode* new_predicate_iff = new_predicate_proj->in(0)->as_If();
+      _igvn.hash_delete(new_predicate_iff);
+      new_predicate_iff->set_req(1, new_predicate_bol);
+#ifndef PRODUCT
+      if (TraceLoopPredicate) {
+        tty->print("Predicate invariant if%s: %d ", negated ? " negated" : "", new_predicate_iff->_idx);
+        loop->dump_head();
+      } else if (TraceLoopOpts) {
+        tty->print("Predicate IC ");
+        loop->dump_head();
+      }
+#endif
+    } else if (cl != NULL && loop->is_range_check_if(iff, this, invar)) {
+      assert(proj->_con == predicate_proj->_con, "must match");
+
+      // Range check for counted loops
+      const Node*    cmp    = bol->in(1)->as_Cmp();
+      Node*          idx    = cmp->in(1);
+      assert(!invar.is_invariant(idx), "index is variant");
+      assert(cmp->in(2)->Opcode() == Op_LoadRange || OptimizeFill, "must be");
+      Node* rng = cmp->in(2);
+      assert(invar.is_invariant(rng), "range must be invariant");
+      int scale    = 1;
+      Node* offset = zero;
+      bool ok = is_scaled_iv_plus_offset(idx, cl->phi(), &scale, &offset);
+      assert(ok, "must be index expression");
+
+      Node* init    = cl->init_trip();
+      Node* limit   = cl->limit();
+      Node* stride  = cl->stride();
+
+      // Build if's for the upper and lower bound tests.  The
+      // lower_bound test will dominate the upper bound test and all
+      // cloned or created nodes will use the lower bound test as
+      // their declared control.
+      ProjNode* lower_bound_proj = create_new_if_for_predicate(predicate_proj, NULL, Deoptimization::Reason_predicate);
+      ProjNode* upper_bound_proj = create_new_if_for_predicate(predicate_proj, NULL, Deoptimization::Reason_predicate);
+      assert(upper_bound_proj->in(0)->as_If()->in(0) == lower_bound_proj, "should dominate");
+      Node *ctrl = lower_bound_proj->in(0)->as_If()->in(0);
+
+      // Perform cloning to keep Invariance state correct since the
+      // late schedule will place invariant things in the loop.
+      rng = invar.clone(rng, ctrl);
+      if (offset && offset != zero) {
+        assert(invar.is_invariant(offset), "offset must be loop invariant");
+        offset = invar.clone(offset, ctrl);
+      }
+
+      // Test the lower bound
+      Node*  lower_bound_bol = rc_predicate(ctrl, scale, offset, init, limit, stride, rng, false);
+      IfNode* lower_bound_iff = lower_bound_proj->in(0)->as_If();
+      _igvn.hash_delete(lower_bound_iff);
+      lower_bound_iff->set_req(1, lower_bound_bol);
+      if (TraceLoopPredicate) tty->print_cr("lower bound check if: %d", lower_bound_iff->_idx);
+
+      // Test the upper bound
+      Node* upper_bound_bol = rc_predicate(ctrl, scale, offset, init, limit, stride, rng, true);
+      IfNode* upper_bound_iff = upper_bound_proj->in(0)->as_If();
+      _igvn.hash_delete(upper_bound_iff);
+      upper_bound_iff->set_req(1, upper_bound_bol);
+      if (TraceLoopPredicate) tty->print_cr("upper bound check if: %d", lower_bound_iff->_idx);
+
+      // Fall through into rest of the clean up code which will move
+      // any dependent nodes onto the upper bound test.
+      new_predicate_proj = upper_bound_proj;
+
+#ifndef PRODUCT
+      if (TraceLoopOpts && !TraceLoopPredicate) {
+        tty->print("Predicate RC ");
+        loop->dump_head();
+      }
+#endif
+    } else {
+      // Loop variant check (for example, range check in non-counted loop)
+      // with uncommon trap.
+      continue;
+    }
+    assert(new_predicate_proj != NULL, "sanity");
+    // Success - attach condition (new_predicate_bol) to predicate if
+    invar.map_ctrl(proj, new_predicate_proj); // so that invariance test can be appropriate
+
+    // Eliminate the old If in the loop body
+    dominated_by( new_predicate_proj, iff, proj->_con != new_predicate_proj->_con );
+
+    hoisted = true;
+    C->set_major_progress();
+  } // end while
+
+#ifndef PRODUCT
+  // report that the loop predication has been actually performed
+  // for this loop
+  if (TraceLoopPredicate && hoisted) {
+    tty->print("Loop Predication Performed:");
+    loop->dump_head();
+  }
+#endif
+
+  return hoisted;
+}
+
+//------------------------------loop_predication--------------------------------
+// driver routine for loop predication optimization
+bool IdealLoopTree::loop_predication( PhaseIdealLoop *phase) {
+  bool hoisted = false;
+  // Recursively promote predicates
+  if (_child) {
+    hoisted = _child->loop_predication( phase);
+  }
+
+  // self
+  if (!_irreducible && !tail()->is_top()) {
+    hoisted |= phase->loop_predication_impl(this);
+  }
+
+  if (_next) { //sibling
+    hoisted |= _next->loop_predication( phase);
+  }
+
+  return hoisted;
+}
+

src/share/vm/opto/loopTransform.cpp

@@ -301,6 +301,132 @@ void PhaseIdealLoop::peeled_dom_test_elim( IdealLoopTree *loop, Node_List &old_n
 //         peeled-loop backedge has 2 users.
 // Step 3: Cut the backedge on the clone (so its not a loop) and remove the
 //         extra backedge user.
+//
+//                   orig
+//
+//                  stmt1
+//                    |
+//                    v
+//              loop predicate
+//                    |
+//                    v
+//                   loop<----+
+//                     |      |
+//                   stmt2    |
+//                     |      |
+//                     v      |
+//                    if      ^
+//                   / \      |
+//                  /   \     |
+//                 v     v    |
+//               false true   |
+//               /       \    |
+//              /         ----+
+//             |
+//             v
+//           exit
+//
+//
+//            after clone loop
+//
+//                   stmt1
+//                     |
+//                     v
+//               loop predicate
+//                 /       \
+//        clone   /         \   orig
+//               /           \
+//              /             \
+//             v               v
+//   +---->loop clone          loop<----+
+//   |      |                    |      |
+//   |    stmt2 clone          stmt2    |
+//   |      |                    |      |
+//   |      v                    v      |
+//   ^      if clone            If      ^
+//   |      / \                / \      |
+//   |     /   \              /   \     |
+//   |    v     v            v     v    |
+//   |    true  false      false true   |
+//   |    /         \      /       \    |
+//   +----           \    /         ----+
+//                    \  /
+//                    1v v2
+//                  region
+//                     |
+//                     v
+//                   exit
+//
+//
+//         after peel and predicate move
+//
+//                   stmt1
+//                    /
+//                   /
+//        clone     /            orig
+//                 /
+//                /              +----------+
+//               /               |          |
+//              /          loop predicate   |
+//             /                 |          |
+//            v                  v          |
+//   TOP-->loop clone          loop<----+   |
+//          |                    |      |   |
+//        stmt2 clone          stmt2    |   |
+//          |                    |      |   ^
+//          v                    v      |   |
+//          if clone            If      ^   |
+//          / \                / \      |   |
+//         /   \              /   \     |   |
+//        v     v            v     v    |   |
+//      true   false      false  true   |   |
+//        |         \      /       \    |   |
+//        |          \    /         ----+   ^
+//        |           \  /                  |
+//        |           1v v2                 |
+//        v         region                  |
+//        |            |                    |
+//        |            v                    |
+//        |          exit                   |
+//        |                                 |
+//        +--------------->-----------------+
+//
+//
+//              final graph
+//
+//                  stmt1
+//                    |
+//                    v
+//                  stmt2 clone
+//                    |
+//                    v
+//                   if clone
+//                  / |
+//                 /  |
+//                v   v
+//            false  true
+//             |      |
+//             |      v
+//             | loop predicate
+//             |      |
+//             |      v
+//             |     loop<----+
+//             |      |       |
+//             |    stmt2     |
+//             |      |       |
+//             |      v       |
+//             v      if      ^
+//             |     /  \     |
+//             |    /    \    |
+//             |   v     v    |
+//             | false  true  |
+//             |  |        \  |
+//             v  v         --+
+//            region
+//              |
+//              v
+//             exit
+//
 void PhaseIdealLoop::do_peeling( IdealLoopTree *loop, Node_List &old_new ) {
 
   C->set_major_progress();
@@ -315,9 +441,10 @@ void PhaseIdealLoop::do_peeling( IdealLoopTree *loop, Node_List &old_new ) {
     loop->dump_head();
   }
 #endif
-  Node *h = loop->_head;
-  if (h->is_CountedLoop()) {
-    CountedLoopNode *cl = h->as_CountedLoop();
+  Node* head = loop->_head;
+  bool counted_loop = head->is_CountedLoop();
+  if (counted_loop) {
+    CountedLoopNode *cl = head->as_CountedLoop();
     assert(cl->trip_count() > 0, "peeling a fully unrolled loop");
     cl->set_trip_count(cl->trip_count() - 1);
     if (cl->is_main_loop()) {
@@ -330,11 +457,11 @@ void PhaseIdealLoop::do_peeling( IdealLoopTree *loop, Node_List &old_new ) {
 #endif
     }
   }
+  Node* entry = head->in(LoopNode::EntryControl);
 
   // Step 1: Clone the loop body.  The clone becomes the peeled iteration.
   //         The pre-loop illegally has 2 control users (old & new loops).
-  clone_loop( loop, old_new, dom_depth(loop->_head) );
-
+  clone_loop( loop, old_new, dom_depth(head) );
 
   // Step 2: Make the old-loop fall-in edges point to the peeled iteration.
   //         Do this by making the old-loop fall-in edges act as if they came
@@ -342,12 +469,15 @@ void PhaseIdealLoop::do_peeling( IdealLoopTree *loop, Node_List &old_new ) {
   //         backedges) and then map to the new peeled iteration.  This leaves
   //         the pre-loop with only 1 user (the new peeled iteration), but the
   //         peeled-loop backedge has 2 users.
-  for (DUIterator_Fast jmax, j = loop->_head->fast_outs(jmax); j < jmax; j++) {
-    Node* old = loop->_head->fast_out(j);
-    if( old->in(0) == loop->_head && old->req() == 3 &&
-        (old->is_Loop() || old->is_Phi()) ) {
-      Node *new_exit_value = old_new[old->in(LoopNode::LoopBackControl)->_idx];
-      if( !new_exit_value )     // Backedge value is ALSO loop invariant?
+  Node* new_exit_value = old_new[head->in(LoopNode::LoopBackControl)->_idx];
+  new_exit_value = move_loop_predicates(entry, new_exit_value);
+  _igvn.hash_delete(head);
+  head->set_req(LoopNode::EntryControl, new_exit_value);
+  for (DUIterator_Fast jmax, j = head->fast_outs(jmax); j < jmax; j++) {
+    Node* old = head->fast_out(j);
+    if (old->in(0) == loop->_head && old->req() == 3 && old->is_Phi()) {
+      new_exit_value = old_new[old->in(LoopNode::LoopBackControl)->_idx];
+      if (!new_exit_value )     // Backedge value is ALSO loop invariant?
         // Then loop body backedge value remains the same.
         new_exit_value = old->in(LoopNode::LoopBackControl);
       _igvn.hash_delete(old);
@@ -358,12 +488,12 @@ void PhaseIdealLoop::do_peeling( IdealLoopTree *loop, Node_List &old_new ) {
 
   // Step 3: Cut the backedge on the clone (so its not a loop) and remove the
   //         extra backedge user.
-  Node *nnn = old_new[loop->_head->_idx];
-  _igvn.hash_delete(nnn);
-  nnn->set_req(LoopNode::LoopBackControl, C->top());
-  for (DUIterator_Fast j2max, j2 = nnn->fast_outs(j2max); j2 < j2max; j2++) {
-    Node* use = nnn->fast_out(j2);
-    if( use->in(0) == nnn && use->req() == 3 && use->is_Phi() ) {
+  Node* new_head = old_new[head->_idx];
+  _igvn.hash_delete(new_head);
+  new_head->set_req(LoopNode::LoopBackControl, C->top());
+  for (DUIterator_Fast j2max, j2 = new_head->fast_outs(j2max); j2 < j2max; j2++) {
+    Node* use = new_head->fast_out(j2);
+    if (use->in(0) == new_head && use->req() == 3 && use->is_Phi()) {
       _igvn.hash_delete(use);
       use->set_req(LoopNode::LoopBackControl, C->top());
     }
@@ -371,15 +501,15 @@ void PhaseIdealLoop::do_peeling( IdealLoopTree *loop, Node_List &old_new ) {
 
 
   // Step 4: Correct dom-depth info.  Set to loop-head depth.
-  int dd = dom_depth(loop->_head);
-  set_idom(loop->_head, loop->_head->in(1), dd);
+  int dd = dom_depth(head);
+  set_idom(head, head->in(1), dd);
   for (uint j3 = 0; j3 < loop->_body.size(); j3++) {
     Node *old = loop->_body.at(j3);
     Node *nnn = old_new[old->_idx];
     if (!has_ctrl(nnn))
       set_idom(nnn, idom(nnn), dd-1);
     // While we're at it, remove any SafePoints from the peeled code
-    if( old->Opcode() == Op_SafePoint ) {
+    if (old->Opcode() == Op_SafePoint) {
       Node *nnn = old_new[old->_idx];
       lazy_replace(nnn,nnn->in(TypeFunc::Control));
     }
@@ -1659,7 +1789,7 @@ bool IdealLoopTree::policy_do_remove_empty_loop( PhaseIdealLoop *phase ) {
   bool needs_guard = !cl->is_main_loop() && !cl->is_post_loop();
   if (needs_guard) {
     // Check for an obvious zero trip guard.
-    Node* inctrl = cl->in(LoopNode::EntryControl);
+    Node* inctrl = PhaseIdealLoop::skip_loop_predicates(cl->in(LoopNode::EntryControl));
     if (inctrl->Opcode() == Op_IfTrue) {
       // The test should look like just the backedge of a CountedLoop
       Node* iff = inctrl->in(0);
@@ -1861,651 +1991,8 @@ bool IdealLoopTree::iteration_split( PhaseIdealLoop *phase, Node_List &old_new )
   return true;
 }
 
-//-------------------------------is_uncommon_trap_proj----------------------------
-// Return true if proj is the form of "proj->[region->..]call_uct"
-bool PhaseIdealLoop::is_uncommon_trap_proj(ProjNode* proj, Deoptimization::DeoptReason reason) {
-  int path_limit = 10;
-  assert(proj, "invalid argument");
-  Node* out = proj;
-  for (int ct = 0; ct < path_limit; ct++) {
-    out = out->unique_ctrl_out();
-    if (out == NULL || out->is_Root() || out->is_Start())
-      return false;
-    if (out->is_CallStaticJava()) {
-      int req = out->as_CallStaticJava()->uncommon_trap_request();
-      if (req != 0) {
-        Deoptimization::DeoptReason trap_reason = Deoptimization::trap_request_reason(req);
-        if (trap_reason == reason || reason == Deoptimization::Reason_none) {
-           return true;
-        }
-      }
-      return false; // don't do further after call
-    }
-  }
-  return false;
-}
-
-//-------------------------------is_uncommon_trap_if_pattern-------------------------
-// Return true  for "if(test)-> proj -> ...
-//                          |
-//                          V
-//                      other_proj->[region->..]call_uct"
-//
-// "must_reason_predicate" means the uct reason must be Reason_predicate
-bool PhaseIdealLoop::is_uncommon_trap_if_pattern(ProjNode *proj, Deoptimization::DeoptReason reason) {
-  Node *in0 = proj->in(0);
-  if (!in0->is_If()) return false;
-  // Variation of a dead If node.
-  if (in0->outcnt() < 2)  return false;
-  IfNode* iff = in0->as_If();
-
-  // we need "If(Conv2B(Opaque1(...)))" pattern for reason_predicate
-  if (reason != Deoptimization::Reason_none) {
-    if (iff->in(1)->Opcode() != Op_Conv2B ||
-       iff->in(1)->in(1)->Opcode() != Op_Opaque1) {
-      return false;
-    }
-  }
-
-  ProjNode* other_proj = iff->proj_out(1-proj->_con)->as_Proj();
-  return is_uncommon_trap_proj(other_proj, reason);
-}
-
-//-------------------------------register_control-------------------------
-void PhaseIdealLoop::register_control(Node* n, IdealLoopTree *loop, Node* pred) {
-  assert(n->is_CFG(), "must be control node");
-  _igvn.register_new_node_with_optimizer(n);
-  loop->_body.push(n);
-  set_loop(n, loop);
-  // When called from beautify_loops() idom is not constructed yet.
-  if (_idom != NULL) {
-    set_idom(n, pred, dom_depth(pred));
-  }
-}
-
-//------------------------------create_new_if_for_predicate------------------------
-// create a new if above the uct_if_pattern for the predicate to be promoted.
-//
-//          before                                after
-//        ----------                           ----------
-//           ctrl                                 ctrl
-//            |                                     |
-//            |                                     |
-//            v                                     v
-//           iff                                 new_iff
-//          /    \                                /      \
-//         /      \                              /        \
-//        v        v                            v          v
-//  uncommon_proj cont_proj                   if_uct     if_cont
-// \      |        |                           |          |
-//  \     |        |                           |          |
-//   v    v        v                           |          v
-//     rgn       loop                          |         iff
-//      |                                      |        /     \
-//      |                                      |       /       \
-//      v                                      |      v         v
-// uncommon_trap                               | uncommon_proj cont_proj
-//                                           \  \    |           |
-//                                            \  \   |           |
-//                                             v  v  v           v
-//                                               rgn           loop
-//                                                |
-//                                                |
-//                                                v
-//                                           uncommon_trap
-//
-//
-// We will create a region to guard the uct call if there is no one there.
-// The true projecttion (if_cont) of the new_iff is returned.
-// This code is also used to clone predicates to clonned loops.
-ProjNode* PhaseIdealLoop::create_new_if_for_predicate(ProjNode* cont_proj, Node* new_entry,
-                                                      Deoptimization::DeoptReason reason) {
-  assert(is_uncommon_trap_if_pattern(cont_proj, reason), "must be a uct if pattern!");
-  IfNode* iff = cont_proj->in(0)->as_If();
-
-  ProjNode *uncommon_proj = iff->proj_out(1 - cont_proj->_con);
-  Node     *rgn   = uncommon_proj->unique_ctrl_out();
-  assert(rgn->is_Region() || rgn->is_Call(), "must be a region or call uct");
-
-  if (!rgn->is_Region()) { // create a region to guard the call
-    assert(rgn->is_Call(), "must be call uct");
-    CallNode* call = rgn->as_Call();
-    IdealLoopTree* loop = get_loop(call);
-    rgn = new (C, 1) RegionNode(1);
-    rgn->add_req(uncommon_proj);
-    register_control(rgn, loop, uncommon_proj);
-    _igvn.hash_delete(call);
-    call->set_req(0, rgn);
-    // When called from beautify_loops() idom is not constructed yet.
-    if (_idom != NULL) {
-      set_idom(call, rgn, dom_depth(rgn));
-    }
-  }
-
-  Node* entry = iff->in(0);
-  if (new_entry != NULL) {
-    // Clonning the predicate to new location.
-    entry = new_entry;
-  }
-  // Create new_iff
-  IdealLoopTree* lp = get_loop(entry);
-  IfNode *new_iff = new (C, 2) IfNode(entry, NULL, iff->_prob, iff->_fcnt);
-  register_control(new_iff, lp, entry);
-  Node *if_cont = new (C, 1) IfTrueNode(new_iff);
-  Node *if_uct  = new (C, 1) IfFalseNode(new_iff);
-  if (cont_proj->is_IfFalse()) {
-    // Swap
-    Node* tmp = if_uct; if_uct = if_cont; if_cont = tmp;
-  }
-  register_control(if_cont, lp, new_iff);
-  register_control(if_uct, get_loop(rgn), new_iff);
-
-  // if_uct to rgn
-  _igvn.hash_delete(rgn);
-  rgn->add_req(if_uct);
-  // When called from beautify_loops() idom is not constructed yet.
-  if (_idom != NULL) {
-    Node* ridom = idom(rgn);
-    Node* nrdom = dom_lca(ridom, new_iff);
-    set_idom(rgn, nrdom, dom_depth(rgn));
-  }
-  // rgn must have no phis
-  assert(!rgn->as_Region()->has_phi(), "region must have no phis");
-
-  if (new_entry == NULL) {
-    // Attach if_cont to iff
-    _igvn.hash_delete(iff);
-    iff->set_req(0, if_cont);
-    if (_idom != NULL) {
-      set_idom(iff, if_cont, dom_depth(iff));
-    }
-  }
-  return if_cont->as_Proj();
-}
-
-//--------------------------find_predicate_insertion_point-------------------
-// Find a good location to insert a predicate
-ProjNode* PhaseIdealLoop::find_predicate_insertion_point(Node* start_c, Deoptimization::DeoptReason reason) {
-  if (start_c == NULL || !start_c->is_Proj())
-    return NULL;
-  if (is_uncommon_trap_if_pattern(start_c->as_Proj(), reason)) {
-    return start_c->as_Proj();
-  }
-  return NULL;
-}
-
-//--------------------------find_predicate------------------------------------
-// Find a predicate
-Node* PhaseIdealLoop::find_predicate(Node* entry) {
-  Node* predicate = NULL;
-  if (UseLoopPredicate) {
-    predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
-    if (predicate != NULL) { // right pattern that can be used by loop predication
-      assert(entry->in(0)->in(1)->in(1)->Opcode()==Op_Opaque1, "must be");
-      return entry;
-    }
-  }
-  return NULL;
-}
-
-//------------------------------Invariance-----------------------------------
-// Helper class for loop_predication_impl to compute invariance on the fly and
-// clone invariants.
-class Invariance : public StackObj {
-  VectorSet _visited, _invariant;
-  Node_Stack _stack;
-  VectorSet _clone_visited;
-  Node_List _old_new; // map of old to new (clone)
-  IdealLoopTree* _lpt;
-  PhaseIdealLoop* _phase;
-
-  // Helper function to set up the invariance for invariance computation
-  // If n is a known invariant, set up directly. Otherwise, look up the
-  // the possibility to push n onto the stack for further processing.
-  void visit(Node* use, Node* n) {
-    if (_lpt->is_invariant(n)) { // known invariant
-      _invariant.set(n->_idx);
-    } else if (!n->is_CFG()) {
-      Node *n_ctrl = _phase->ctrl_or_self(n);
-      Node *u_ctrl = _phase->ctrl_or_self(use); // self if use is a CFG
-      if (_phase->is_dominator(n_ctrl, u_ctrl)) {
-        _stack.push(n, n->in(0) == NULL ? 1 : 0);
-      }
-    }
-  }
-
-  // Compute invariance for "the_node" and (possibly) all its inputs recursively
-  // on the fly
-  void compute_invariance(Node* n) {
-    assert(_visited.test(n->_idx), "must be");
-    visit(n, n);
-    while (_stack.is_nonempty()) {
-      Node*  n = _stack.node();
-      uint idx = _stack.index();
-      if (idx == n->req()) { // all inputs are processed
-        _stack.pop();
-        // n is invariant if it's inputs are all invariant
-        bool all_inputs_invariant = true;
-        for (uint i = 0; i < n->req(); i++) {
-          Node* in = n->in(i);
-          if (in == NULL) continue;
-          assert(_visited.test(in->_idx), "must have visited input");
-          if (!_invariant.test(in->_idx)) { // bad guy
-            all_inputs_invariant = false;
-            break;
-          }
-        }
-        if (all_inputs_invariant) {
-          _invariant.set(n->_idx); // I am a invariant too
-        }
-      } else { // process next input
-        _stack.set_index(idx + 1);
-        Node* m = n->in(idx);
-        if (m != NULL && !_visited.test_set(m->_idx)) {
-          visit(n, m);
-        }
-      }
-    }
-  }
-
-  // Helper function to set up _old_new map for clone_nodes.
-  // If n is a known invariant, set up directly ("clone" of n == n).
-  // Otherwise, push n onto the stack for real cloning.
-  void clone_visit(Node* n) {
-    assert(_invariant.test(n->_idx), "must be invariant");
-    if (_lpt->is_invariant(n)) { // known invariant
-      _old_new.map(n->_idx, n);
-    } else{ // to be cloned
-      assert (!n->is_CFG(), "should not see CFG here");
-      _stack.push(n, n->in(0) == NULL ? 1 : 0);
-    }
-  }
-
-  // Clone "n" and (possibly) all its inputs recursively
-  void clone_nodes(Node* n, Node* ctrl) {
-    clone_visit(n);
-    while (_stack.is_nonempty()) {
-      Node*  n = _stack.node();
-      uint idx = _stack.index();
-      if (idx == n->req()) { // all inputs processed, clone n!
-        _stack.pop();
-        // clone invariant node
-        Node* n_cl = n->clone();
-        _old_new.map(n->_idx, n_cl);
-        _phase->register_new_node(n_cl, ctrl);
-        for (uint i = 0; i < n->req(); i++) {
-          Node* in = n_cl->in(i);
-          if (in == NULL) continue;
-          n_cl->set_req(i, _old_new[in->_idx]);
-        }
-      } else { // process next input
-        _stack.set_index(idx + 1);
-        Node* m = n->in(idx);
-        if (m != NULL && !_clone_visited.test_set(m->_idx)) {
-          clone_visit(m); // visit the input
-        }
-      }
-    }
-  }
-
- public:
-  Invariance(Arena* area, IdealLoopTree* lpt) :
-    _lpt(lpt), _phase(lpt->_phase),
-    _visited(area), _invariant(area), _stack(area, 10 /* guess */),
-    _clone_visited(area), _old_new(area)
-  {}
-
-  // Map old to n for invariance computation and clone
-  void map_ctrl(Node* old, Node* n) {
-    assert(old->is_CFG() && n->is_CFG(), "must be");
-    _old_new.map(old->_idx, n); // "clone" of old is n
-    _invariant.set(old->_idx);  // old is invariant
-    _clone_visited.set(old->_idx);
-  }
-
-  // Driver function to compute invariance
-  bool is_invariant(Node* n) {
-    if (!_visited.test_set(n->_idx))
-      compute_invariance(n);
-    return (_invariant.test(n->_idx) != 0);
-  }
-
-  // Driver function to clone invariant
-  Node* clone(Node* n, Node* ctrl) {
-    assert(ctrl->is_CFG(), "must be");
-    assert(_invariant.test(n->_idx), "must be an invariant");
-    if (!_clone_visited.test(n->_idx))
-      clone_nodes(n, ctrl);
-    return _old_new[n->_idx];
-  }
-};
-
-//------------------------------is_range_check_if -----------------------------------
-// Returns true if the predicate of iff is in "scale*iv + offset u< load_range(ptr)" format
-// Note: this function is particularly designed for loop predication. We require load_range
-//       and offset to be loop invariant computed on the fly by "invar"
-bool IdealLoopTree::is_range_check_if(IfNode *iff, PhaseIdealLoop *phase, Invariance& invar) const {
-  if (!is_loop_exit(iff)) {
-    return false;
-  }
-  if (!iff->in(1)->is_Bool()) {
-    return false;
-  }
-  const BoolNode *bol = iff->in(1)->as_Bool();
-  if (bol->_test._test != BoolTest::lt) {
-    return false;
-  }
-  if (!bol->in(1)->is_Cmp()) {
-    return false;
-  }
-  const CmpNode *cmp = bol->in(1)->as_Cmp();
-  if (cmp->Opcode() != Op_CmpU ) {
-    return false;
-  }
-  Node* range = cmp->in(2);
-  if (range->Opcode() != Op_LoadRange) {
-    const TypeInt* tint = phase->_igvn.type(range)->isa_int();
-    if (!OptimizeFill || tint == NULL || tint->empty() || tint->_lo < 0) {
-      // Allow predication on positive values that aren't LoadRanges.
-      // This allows optimization of loops where the length of the
-      // array is a known value and doesn't need to be loaded back
-      // from the array.
-      return false;
-    }
-  }
-  if (!invar.is_invariant(range)) {
-    return false;
-  }
-  Node *iv     = _head->as_CountedLoop()->phi();
-  int   scale  = 0;
-  Node *offset = NULL;
-  if (!phase->is_scaled_iv_plus_offset(cmp->in(1), iv, &scale, &offset)) {
-    return false;
-  }
-  if(offset && !invar.is_invariant(offset)) { // offset must be invariant
-    return false;
-  }
-  return true;
-}
-
-//------------------------------rc_predicate-----------------------------------
-// Create a range check predicate
-//
-// for (i = init; i < limit; i += stride) {
-//    a[scale*i+offset]
-// }
-//
-// Compute max(scale*i + offset) for init <= i < limit and build the predicate
-// as "max(scale*i + offset) u< a.length".
-//
-// There are two cases for max(scale*i + offset):
-// (1) stride*scale > 0
-//   max(scale*i + offset) = scale*(limit-stride) + offset
-// (2) stride*scale < 0
-//   max(scale*i + offset) = scale*init + offset
-BoolNode* PhaseIdealLoop::rc_predicate(Node* ctrl,
-                                       int scale, Node* offset,
-                                       Node* init, Node* limit, Node* stride,
-                                       Node* range, bool upper) {
-  DEBUG_ONLY(ttyLocker ttyl);
-  if (TraceLoopPredicate) tty->print("rc_predicate ");
-
-  Node* max_idx_expr  = init;
-  int stride_con = stride->get_int();
-  if ((stride_con > 0) == (scale > 0) == upper) {
-    max_idx_expr = new (C, 3) SubINode(limit, stride);
-    register_new_node(max_idx_expr, ctrl);
-    if (TraceLoopPredicate) tty->print("(limit - stride) ");
-  } else {
-    if (TraceLoopPredicate) tty->print("init ");
-  }
-
-  if (scale != 1) {
-    ConNode* con_scale = _igvn.intcon(scale);
-    max_idx_expr = new (C, 3) MulINode(max_idx_expr, con_scale);
-    register_new_node(max_idx_expr, ctrl);
-    if (TraceLoopPredicate) tty->print("* %d ", scale);
-  }
-
-  if (offset && (!offset->is_Con() || offset->get_int() != 0)){
-    max_idx_expr = new (C, 3) AddINode(max_idx_expr, offset);
-    register_new_node(max_idx_expr, ctrl);
-    if (TraceLoopPredicate)
-      if (offset->is_Con()) tty->print("+ %d ", offset->get_int());
-      else tty->print("+ offset ");
-  }
-
-  CmpUNode* cmp = new (C, 3) CmpUNode(max_idx_expr, range);
-  register_new_node(cmp, ctrl);
-  BoolNode* bol = new (C, 2) BoolNode(cmp, BoolTest::lt);
-  register_new_node(bol, ctrl);
-
-  if (TraceLoopPredicate) tty->print_cr("<u range");
-  return bol;
-}
-
-//------------------------------ loop_predication_impl--------------------------
-// Insert loop predicates for null checks and range checks
-bool PhaseIdealLoop::loop_predication_impl(IdealLoopTree *loop) {
-  if (!UseLoopPredicate) return false;
-
-  if (!loop->_head->is_Loop()) {
-    // Could be a simple region when irreducible loops are present.
-    return false;
-  }
-
-  if (loop->_head->unique_ctrl_out()->Opcode() == Op_NeverBranch) {
-    // do nothing for infinite loops
-    return false;
-  }
-
-  CountedLoopNode *cl = NULL;
-  if (loop->_head->is_CountedLoop()) {
-    cl = loop->_head->as_CountedLoop();
-    // do nothing for iteration-splitted loops
-    if (!cl->is_normal_loop()) return false;
-  }
-
-  LoopNode *lpn  = loop->_head->as_Loop();
-  Node* entry = lpn->in(LoopNode::EntryControl);
-
-  ProjNode *predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
-  if (!predicate_proj) {
-#ifndef PRODUCT
-    if (TraceLoopPredicate) {
-      tty->print("missing predicate:");
-      loop->dump_head();
-      lpn->dump(1);
-    }
-#endif
-    return false;
-  }
-  ConNode* zero = _igvn.intcon(0);
-  set_ctrl(zero, C->root());
-
-  ResourceArea *area = Thread::current()->resource_area();
-  Invariance invar(area, loop);
-
-  // Create list of if-projs such that a newer proj dominates all older
-  // projs in the list, and they all dominate loop->tail()
-  Node_List if_proj_list(area);
-  LoopNode *head  = loop->_head->as_Loop();
-  Node *current_proj = loop->tail(); //start from tail
-  while ( current_proj != head ) {
-    if (loop == get_loop(current_proj) && // still in the loop ?
-        current_proj->is_Proj()        && // is a projection  ?
-        current_proj->in(0)->Opcode() == Op_If) { // is a if projection ?
-      if_proj_list.push(current_proj);
-    }
-    current_proj = idom(current_proj);
-  }
-
-  bool hoisted = false; // true if at least one proj is promoted
-  while (if_proj_list.size() > 0) {
-    // Following are changed to nonnull when a predicate can be hoisted
-    ProjNode* new_predicate_proj = NULL;
-
-    ProjNode* proj = if_proj_list.pop()->as_Proj();
-    IfNode*   iff  = proj->in(0)->as_If();
-
-    if (!is_uncommon_trap_if_pattern(proj, Deoptimization::Reason_none)) {
-      if (loop->is_loop_exit(iff)) {
-        // stop processing the remaining projs in the list because the execution of them
-        // depends on the condition of "iff" (iff->in(1)).
-        break;
-      } else {
-        // Both arms are inside the loop. There are two cases:
-        // (1) there is one backward branch. In this case, any remaining proj
-        //     in the if_proj list post-dominates "iff". So, the condition of "iff"
-        //     does not determine the execution the remining projs directly, and we
-        //     can safely continue.
-        // (2) both arms are forwarded, i.e. a diamond shape. In this case, "proj"
-        //     does not dominate loop->tail(), so it can not be in the if_proj list.
-        continue;
-      }
-    }
-
-    Node*     test = iff->in(1);
-    if (!test->is_Bool()){ //Conv2B, ...
-      continue;
-    }
-    BoolNode* bol = test->as_Bool();
-    if (invar.is_invariant(bol)) {
-      // Invariant test
-      new_predicate_proj = create_new_if_for_predicate(predicate_proj, NULL,
-                                                       Deoptimization::Reason_predicate);
-      Node* ctrl = new_predicate_proj->in(0)->as_If()->in(0);
-      BoolNode* new_predicate_bol = invar.clone(bol, ctrl)->as_Bool();
-
-      // Negate test if necessary
-      bool negated = false;
-      if (proj->_con != predicate_proj->_con) {
-        new_predicate_bol = new (C, 2) BoolNode(new_predicate_bol->in(1), new_predicate_bol->_test.negate());
-        register_new_node(new_predicate_bol, ctrl);
-        negated = true;
-      }
-      IfNode* new_predicate_iff = new_predicate_proj->in(0)->as_If();
-      _igvn.hash_delete(new_predicate_iff);
-      new_predicate_iff->set_req(1, new_predicate_bol);
-#ifndef PRODUCT
-      if (TraceLoopPredicate) {
-        tty->print("Predicate invariant if%s: %d ", negated ? " negated" : "", new_predicate_iff->_idx);
-        loop->dump_head();
-      } else if (TraceLoopOpts) {
-        tty->print("Predicate IC ");
-        loop->dump_head();
-      }
-#endif
-    } else if (cl != NULL && loop->is_range_check_if(iff, this, invar)) {
-      assert(proj->_con == predicate_proj->_con, "must match");
-
-      // Range check for counted loops
-      const Node*    cmp    = bol->in(1)->as_Cmp();
-      Node*          idx    = cmp->in(1);
-      assert(!invar.is_invariant(idx), "index is variant");
-      assert(cmp->in(2)->Opcode() == Op_LoadRange || OptimizeFill, "must be");
-      Node* rng = cmp->in(2);
-      assert(invar.is_invariant(rng), "range must be invariant");
-      int scale    = 1;
-      Node* offset = zero;
-      bool ok = is_scaled_iv_plus_offset(idx, cl->phi(), &scale, &offset);
-      assert(ok, "must be index expression");
-
-      Node* init    = cl->init_trip();
-      Node* limit   = cl->limit();
-      Node* stride  = cl->stride();
-
-      // Build if's for the upper and lower bound tests.  The
-      // lower_bound test will dominate the upper bound test and all
-      // cloned or created nodes will use the lower bound test as
-      // their declared control.
-      ProjNode* lower_bound_proj = create_new_if_for_predicate(predicate_proj, NULL, Deoptimization::Reason_predicate);
-      ProjNode* upper_bound_proj = create_new_if_for_predicate(predicate_proj, NULL, Deoptimization::Reason_predicate);
-      assert(upper_bound_proj->in(0)->as_If()->in(0) == lower_bound_proj, "should dominate");
-      Node *ctrl = lower_bound_proj->in(0)->as_If()->in(0);
-
-      // Perform cloning to keep Invariance state correct since the
-      // late schedule will place invariant things in the loop.
-      rng = invar.clone(rng, ctrl);
-      if (offset && offset != zero) {
-        assert(invar.is_invariant(offset), "offset must be loop invariant");
-        offset = invar.clone(offset, ctrl);
-      }
-
-      // Test the lower bound
-      Node*  lower_bound_bol = rc_predicate(ctrl, scale, offset, init, limit, stride, rng, false);
-      IfNode* lower_bound_iff = lower_bound_proj->in(0)->as_If();
-      _igvn.hash_delete(lower_bound_iff);
-      lower_bound_iff->set_req(1, lower_bound_bol);
-      if (TraceLoopPredicate) tty->print_cr("lower bound check if: %d", lower_bound_iff->_idx);
-
-      // Test the upper bound
-      Node* upper_bound_bol = rc_predicate(ctrl, scale, offset, init, limit, stride, rng, true);
-      IfNode* upper_bound_iff = upper_bound_proj->in(0)->as_If();
-      _igvn.hash_delete(upper_bound_iff);
-      upper_bound_iff->set_req(1, upper_bound_bol);
-      if (TraceLoopPredicate) tty->print_cr("upper bound check if: %d", lower_bound_iff->_idx);
-
-      // Fall through into rest of the clean up code which will move
-      // any dependent nodes onto the upper bound test.
-      new_predicate_proj = upper_bound_proj;
-
-#ifndef PRODUCT
-      if (TraceLoopOpts && !TraceLoopPredicate) {
-        tty->print("Predicate RC ");
-        loop->dump_head();
-      }
-#endif
-    } else {
-      // Loop variant check (for example, range check in non-counted loop)
-      // with uncommon trap.
-      continue;
-    }
-    assert(new_predicate_proj != NULL, "sanity");
-    // Success - attach condition (new_predicate_bol) to predicate if
-    invar.map_ctrl(proj, new_predicate_proj); // so that invariance test can be appropriate
-
-    // Eliminate the old If in the loop body
-    dominated_by( new_predicate_proj, iff, proj->_con != new_predicate_proj->_con );
-
-    hoisted = true;
-    C->set_major_progress();
-  } // end while
-
-#ifndef PRODUCT
-  // report that the loop predication has been actually performed
-  // for this loop
-  if (TraceLoopPredicate && hoisted) {
-    tty->print("Loop Predication Performed:");
-    loop->dump_head();
-  }
-#endif
-
-  return hoisted;
-}
-
-//------------------------------loop_predication--------------------------------
-// driver routine for loop predication optimization
-bool IdealLoopTree::loop_predication( PhaseIdealLoop *phase) {
-  bool hoisted = false;
-  // Recursively promote predicates
-  if ( _child ) {
-    hoisted = _child->loop_predication( phase);
-  }
-
-  // self
-  if (!_irreducible && !tail()->is_top()) {
-    hoisted |= phase->loop_predication_impl(this);
-  }
-
-  if ( _next ) { //sibling
-    hoisted |= _next->loop_predication( phase);
-  }
-
-  return hoisted;
-}
-
 
+//=============================================================================
 // Process all the loops in the loop tree and replace any fill
 // patterns with an intrisc version.
 bool PhaseIdealLoop::do_intrinsify_fill() {
@@ -2762,6 +2249,13 @@ bool PhaseIdealLoop::intrinsify_fill(IdealLoopTree* lpt) {
     return false;
   }
 
+#ifndef PRODUCT
+  if (TraceLoopOpts) {
+    tty->print("ArrayFill    ");
+    lpt->dump_head();
+  }
+#endif
+
   // Now replace the whole loop body by a call to a fill routine that
   // covers the same region as the loop.
   Node* base = store->in(MemNode::Address)->as_AddP()->in(AddPNode::Base);

src/share/vm/opto/loopUnswitch.cpp

@@ -32,15 +32,17 @@
 //
 // orig:                       transformed:
 //                               if (invariant-test) then
+//  predicate                      predicate
 //  loop                           loop
 //    stmt1                          stmt1
 //    if (invariant-test) then       stmt2
 //      stmt2                        stmt4
 //    else                         endloop
 //      stmt3                    else
-//    endif                        loop [clone]
-//    stmt4                          stmt1 [clone]
-//  endloop                          stmt3
+//    endif                        predicate [clone]
+//    stmt4                        loop [clone]
+//  endloop                          stmt1 [clone]
+//                                   stmt3
 //                                   stmt4 [clone]
 //                                 endloop
 //                               endif
@@ -124,8 +126,15 @@ void PhaseIdealLoop::do_unswitching (IdealLoopTree *loop, Node_List &old_new) {
 
   ProjNode* proj_true = create_slow_version_of_loop(loop, old_new);
 
-  assert(proj_true->is_IfTrue() && proj_true->unique_ctrl_out() == head, "by construction");
-
+#ifdef ASSERT
+  Node* uniqc = proj_true->unique_ctrl_out();
+  Node* entry = head->in(LoopNode::EntryControl);
+  Node* predicate = find_predicate(entry);
+  if (predicate != NULL) predicate = predicate->in(0);
+  assert(proj_true->is_IfTrue() &&
+         (predicate == NULL && uniqc == head ||
+          predicate != NULL && uniqc == predicate), "by construction");
+#endif
   // Increment unswitch count
   LoopNode* head_clone = old_new[head->_idx]->as_Loop();
   int nct = head->unswitch_count() + 1;
@@ -227,21 +236,24 @@ ProjNode* PhaseIdealLoop::create_slow_version_of_loop(IdealLoopTree *loop,
   register_node(ifslow, outer_loop, iff, dom_depth(iff));
 
   // Clone the loop body.  The clone becomes the fast loop.  The
-  // original pre-header will (illegally) have 2 control users (old & new loops).
+  // original pre-header will (illegally) have 3 control users
+  // (old & new loops & new if).
   clone_loop(loop, old_new, dom_depth(head), iff);
   assert(old_new[head->_idx]->is_Loop(), "" );
 
   // Fast (true) control
+  Node* iffast_pred = clone_loop_predicates(entry, iffast);
   _igvn.hash_delete(head);
-  head->set_req(LoopNode::EntryControl, iffast);
-  set_idom(head, iffast, dom_depth(head));
+  head->set_req(LoopNode::EntryControl, iffast_pred);
+  set_idom(head, iffast_pred, dom_depth(head));
   _igvn._worklist.push(head);
 
   // Slow (false) control
+  Node* ifslow_pred = move_loop_predicates(entry, ifslow);
   LoopNode* slow_head = old_new[head->_idx]->as_Loop();
   _igvn.hash_delete(slow_head);
-  slow_head->set_req(LoopNode::EntryControl, ifslow);
-  set_idom(slow_head, ifslow, dom_depth(slow_head));
+  slow_head->set_req(LoopNode::EntryControl, ifslow_pred);
+  set_idom(slow_head, ifslow_pred, dom_depth(slow_head));
   _igvn._worklist.push(slow_head);
 
   recompute_dom_depth();

src/share/vm/opto/loopnode.cpp

@@ -341,7 +341,12 @@ bool PhaseIdealLoop::is_counted_loop( Node *x, IdealLoopTree *loop ) {
   //
   assert(x->Opcode() == Op_Loop, "regular loops only");
   C->print_method("Before CountedLoop", 3);
-
+#ifndef PRODUCT
+  if (TraceLoopOpts) {
+    tty->print("Counted      ");
+    loop->dump_head();
+  }
+#endif
   // If compare points to incr, we are ok.  Otherwise the compare
   // can directly point to the phi; in this case adjust the compare so that
   // it points to the incr by adjusting the limit.
@@ -864,8 +869,10 @@ void IdealLoopTree::split_outer_loop( PhaseIdealLoop *phase ) {
   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();
+
+  Node* pred = phase->clone_loop_predicates(ctl, outer);
   // Outermost loop falls into '_head' loop
-  _head->set_req(LoopNode::EntryControl, outer);
+  _head->set_req(LoopNode::EntryControl, pred);
   _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++) {
@@ -1103,12 +1110,13 @@ bool IdealLoopTree::beautify_loops( PhaseIdealLoop *phase ) {
   // 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 the many backedges into a single backedge but leave
+    // the hottest backedge as separate edge for the following peel.
     merge_many_backedges( phase );
     result = true;
   }
 
-  // If I am a shared header (multiple backedges), peel off myself loop.
+  // If I have one hot backedge, peel off myself loop.
   // I better be the outermost loop.
   if( _head->req() > 3 ) {
     split_outer_loop( phase );
@@ -1433,9 +1441,9 @@ void IdealLoopTree::dump_head( ) const {
   tty->print("Loop: N%d/N%d ",_head->_idx,_tail->_idx);
   if (_irreducible) tty->print(" IRREDUCIBLE");
   if (UseLoopPredicate) {
-    Node* entry = _head->in(LoopNode::EntryControl);
-    if (entry != NULL && entry->is_Proj() &&
-        PhaseIdealLoop::is_uncommon_trap_if_pattern(entry->as_Proj(), Deoptimization::Reason_predicate)) {
+    Node* entry = PhaseIdealLoop::find_predicate_insertion_point(_head->in(LoopNode::EntryControl),
+                                                                 Deoptimization::Reason_predicate);
+    if (entry != NULL) {
       tty->print(" predicated");
     }
   }
@@ -1541,7 +1549,7 @@ void PhaseIdealLoop::eliminate_useless_predicates() {
 //----------------------------build_and_optimize-------------------------------
 // Create a PhaseLoop.  Build the ideal Loop tree.  Map each Ideal Node to
 // its corresponding LoopNode.  If 'optimize' is true, do some loop cleanups.
-void PhaseIdealLoop::build_and_optimize(bool do_split_ifs, bool do_loop_pred) {
+void PhaseIdealLoop::build_and_optimize(bool do_split_ifs) {
   ResourceMark rm;
 
   int old_progress = C->major_progress();
@@ -1573,6 +1581,13 @@ void PhaseIdealLoop::build_and_optimize(bool do_split_ifs, bool do_loop_pred) {
   // Do not need a safepoint at the top level
   _ltree_root->_has_sfpt = 1;
 
+  // Initialize Dominators.
+  // Checked in clone_loop_predicate() during beautify_loops().
+  _idom_size = 0;
+  _idom      = NULL;
+  _dom_depth = NULL;
+  _dom_stk   = NULL;
+
   // Empty pre-order array
   allocate_preorders();
 
@@ -1698,8 +1713,9 @@ void PhaseIdealLoop::build_and_optimize(bool do_split_ifs, bool do_loop_pred) {
     return;
   }
 
-  // some parser-inserted loop predicates could never be used by loop
-  // predication. Eliminate them before loop optimization
+  // Some parser-inserted loop predicates could never be used by loop
+  // predication or they were moved away from loop during some optimizations.
+  // For example, peeling. Eliminate them before next loop optimizations.
   if (UseLoopPredicate) {
     eliminate_useless_predicates();
   }
@@ -1750,7 +1766,7 @@ void PhaseIdealLoop::build_and_optimize(bool do_split_ifs, bool do_loop_pred) {
   }
 
   // Perform loop predication before iteration splitting
-  if (do_loop_pred && C->has_loops() && !C->major_progress()) {
+  if (C->has_loops() && !C->major_progress() && (C->predicate_count() > 0)) {
     _ltree_root->_child->loop_predication(this);
   }
 
@@ -1793,8 +1809,20 @@ void PhaseIdealLoop::build_and_optimize(bool do_split_ifs, bool do_loop_pred) {
     C->set_major_progress();
   }
 
-  // Convert scalar to superword operations
+  // Keep loop predicates and perform optimizations with them
+  // until no more loop optimizations could be done.
+  // After that switch predicates off and do more loop optimizations.
+  if (!C->major_progress() && (C->predicate_count() > 0)) {
+     C->cleanup_loop_predicates(_igvn);
+#ifndef PRODUCT
+     if (TraceLoopOpts) {
+       tty->print_cr("PredicatesOff");
+     }
+#endif
+     C->set_major_progress();
+  }
 
+  // Convert scalar to superword operations at the end of all loop opts.
   if (UseSuperWord && C->has_loops() && !C->major_progress()) {
     // SuperWord transform
     SuperWord sw(this);

src/share/vm/opto/loopnode.hpp

@@ -706,11 +706,11 @@ private:
     _dom_lca_tags(arena()), // Thread::resource_area
     _verify_me(NULL),
     _verify_only(true) {
-    build_and_optimize(false, false);
+    build_and_optimize(false);
   }
 
   // build the loop tree and perform any requested optimizations
-  void build_and_optimize(bool do_split_if, bool do_loop_pred);
+  void build_and_optimize(bool do_split_if);
 
 public:
   // Dominators for the sea of nodes
@@ -721,13 +721,13 @@ public:
   Node *dom_lca_internal( Node *n1, Node *n2 ) const;
 
   // Compute the Ideal Node to Loop mapping
-  PhaseIdealLoop( PhaseIterGVN &igvn, bool do_split_ifs, bool do_loop_pred) :
+  PhaseIdealLoop( PhaseIterGVN &igvn, bool do_split_ifs) :
     PhaseTransform(Ideal_Loop),
     _igvn(igvn),
     _dom_lca_tags(arena()), // Thread::resource_area
     _verify_me(NULL),
     _verify_only(false) {
-    build_and_optimize(do_split_ifs, do_loop_pred);
+    build_and_optimize(do_split_ifs);
   }
 
   // Verify that verify_me made the same decisions as a fresh run.
@@ -737,7 +737,7 @@ public:
     _dom_lca_tags(arena()), // Thread::resource_area
     _verify_me(verify_me),
     _verify_only(false) {
-    build_and_optimize(false, false);
+    build_and_optimize(false);
   }
 
   // Build and verify the loop tree without modifying the graph.  This
@@ -830,7 +830,26 @@ public:
                                         Deoptimization::DeoptReason reason);
   void register_control(Node* n, IdealLoopTree *loop, Node* pred);
 
-   // Find a good location to insert a predicate
+  // Clone loop predicates to cloned loops (peeled, unswitched)
+  static ProjNode* clone_predicate(ProjNode* predicate_proj, Node* new_entry,
+                                   Deoptimization::DeoptReason reason,
+                                   PhaseIdealLoop* loop_phase,
+                                   PhaseIterGVN* igvn);
+  static ProjNode*  move_predicate(ProjNode* predicate_proj, Node* new_entry,
+                                   Deoptimization::DeoptReason reason,
+                                   PhaseIdealLoop* loop_phase,
+                                   PhaseIterGVN* igvn);
+  static Node* clone_loop_predicates(Node* old_entry, Node* new_entry,
+                                         bool move_predicates,
+                                         PhaseIdealLoop* loop_phase,
+                                         PhaseIterGVN* igvn);
+  Node* clone_loop_predicates(Node* old_entry, Node* new_entry);
+  Node*  move_loop_predicates(Node* old_entry, Node* new_entry);
+
+  void eliminate_loop_predicates(Node* entry);
+  static Node* skip_loop_predicates(Node* entry);
+
+  // Find a good location to insert a predicate
   static ProjNode* find_predicate_insertion_point(Node* start_c, Deoptimization::DeoptReason reason);
   // Find a predicate
   static Node* find_predicate(Node* entry);

src/share/vm/opto/loopopts.cpp

@@ -2139,9 +2139,12 @@ bool PhaseIdealLoop::is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& p
 //
 //                   orig
 //
-//                  stmt1
-//                    |
-//                    v
+//                   stmt1
+//                     |
+//                     v
+//               loop predicate
+//                     |
+//                     v
 //                   loop<----+
 //                     |      |
 //                   stmt2    |
@@ -2172,6 +2175,9 @@ bool PhaseIdealLoop::is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& p
 //            after clone loop
 //
 //                   stmt1
+//                     |
+//                     v
+//               loop predicate
 //                 /       \
 //        clone   /         \   orig
 //               /           \
@@ -2210,12 +2216,15 @@ bool PhaseIdealLoop::is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& p
 //           after partial peel
 //
 //                  stmt1
+//                     |
+//                     v
+//               loop predicate
 //                 /
 //        clone   /             orig
 //               /          TOP
 //              /             \
 //             v               v
-//    TOP->region             region----+
+//    TOP->loop                loop----+
 //          |                    |      |
 //        stmt2                stmt2    |
 //          |                    |      |
@@ -2253,13 +2262,17 @@ bool PhaseIdealLoop::is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& p
 //                  stmt1
 //                    |
 //                    v
+//                  stmt2 clone
+//                    |
+//                    v
 //         ........> ifA clone
 //         :        / |
 //        dom      /  |
 //         :      v   v
 //         :  false   true
 //         :  |       |
-//         :  |     stmt2 clone
+//         :  |       v
+//         :  | loop predicate
 //         :  |       |
 //         :  |       v
 //         :  |    newloop<-----+
@@ -2289,6 +2302,7 @@ bool PhaseIdealLoop::is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& p
 //
 bool PhaseIdealLoop::partial_peel( IdealLoopTree *loop, Node_List &old_new ) {
 
+  assert(!loop->_head->is_CountedLoop(), "Non-counted loop only");
   if (!loop->_head->is_Loop()) {
     return false;  }
 
@@ -2316,6 +2330,7 @@ bool PhaseIdealLoop::partial_peel( IdealLoopTree *loop, Node_List &old_new ) {
     }
   }
 
+  Node* entry = head->in(LoopNode::EntryControl);
   int dd = dom_depth(head);
 
   // Step 1: find cut point
@@ -2612,6 +2627,8 @@ bool PhaseIdealLoop::partial_peel( IdealLoopTree *loop, Node_List &old_new ) {
 
   // Backedge of the surviving new_head (the clone) is original last_peel
   _igvn.hash_delete(new_head_clone);
+  Node* new_entry = move_loop_predicates(entry, new_head_clone->in(LoopNode::EntryControl));
+  new_head_clone->set_req(LoopNode::EntryControl, new_entry);
   new_head_clone->set_req(LoopNode::LoopBackControl, last_peel);
   _igvn._worklist.push(new_head_clone);
 

src/share/vm/opto/phaseX.hpp

@@ -471,6 +471,13 @@ public:
     _delay_transform = delay;
   }
 
+  // Clone loop predicates. Defined in loopTransform.cpp.
+  Node* clone_loop_predicates(Node* old_entry, Node* new_entry);
+  Node*  move_loop_predicates(Node* old_entry, Node* new_entry);
+  // Create a new if below new_entry for the predicate to be cloned
+  ProjNode* create_new_if_for_predicate(ProjNode* cont_proj, Node* new_entry,
+                                        Deoptimization::DeoptReason reason);
+
 #ifndef PRODUCT
 protected:
   // Sub-quadratic implementation of VerifyIterativeGVN.

src/share/vm/opto/split_if.cpp

@@ -399,6 +399,9 @@ void PhaseIdealLoop::do_split_if( Node *iff ) {
 #ifndef PRODUCT
   if( PrintOpto && VerifyLoopOptimizations )
     tty->print_cr("Split-if");
+  if (TraceLoopOpts) {
+    tty->print_cr("SplitIf");
+  }
 #endif
   C->set_major_progress();
   Node *region = iff->in(0);

src/share/vm/opto/superword.cpp

@@ -1132,6 +1132,13 @@ void SuperWord::co_locate_pack(Node_List* pk) {
 void SuperWord::output() {
   if (_packset.length() == 0) return;
 
+#ifndef PRODUCT
+  if (TraceLoopOpts) {
+    tty->print("SuperWord    ");
+    lpt()->dump_head();
+  }
+#endif
+
   // MUST ENSURE main loop's initial value is properly aligned:
   //  (iv_initial_value + min_iv_offset) % vector_width_in_bytes() == 0
 

src/share/vm/opto/vectornode.hpp

@@ -32,6 +32,7 @@
 //------------------------------VectorNode--------------------------------------
 // Vector Operation
 class VectorNode : public Node {
+  virtual uint size_of() const { return sizeof(*this); }
  protected:
   uint _length; // vector length
   virtual BasicType elt_basic_type() const = 0; // Vector element basic type