jdk8-mips64-public/hotspot: src/share/vm/opto/loopPredicate.cpp@04ff2f6cd0eb (annotated)

src/share/vm/opto/loopPredicate.cpp@04ff2f6cd0eb (annotated)

src/share/vm/opto/loopPredicate.cpp

Tue, 17 Oct 2017 12:58:25 +0800

author: aoqi
date: Tue, 17 Oct 2017 12:58:25 +0800
changeset 7994: 04ff2f6cd0eb
parent 7859: c1c199dde5c9
parent 6876: 710a3c8b516e
child 8856: ac27a9c85bea
permissions: -rw-r--r--

merge

 /*
  * Copyright (c) 2011, 2014, 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).
 */
 //-------------------------------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(cont_proj->is_uncommon_trap_if_pattern(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) 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) IfTrueNode(new_iff);
   Node *if_uct  = new (C) 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.rehash_node_delayed(use);
       use->add_req(use->in(proj_index));
       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(cont_proj->is_uncommon_trap_if_pattern(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) 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) IfTrueNode(new_iff);
   Node *if_uct  = new (C) 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) {
       rehash_node_delayed(use);
       use->add_req(use->in(proj_index));
       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) Opaque1Node(igvn->C, predicate_proj->in(0)->in(1)->in(1)->in(1));
   igvn->C->add_predicate_opaq(opq);
   Node* bol = new (igvn->C) 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;
 }
 //--------------------------clone_loop_predicates-----------------------
 // Interface from IGVN
 Node* PhaseIterGVN::clone_loop_predicates(Node* old_entry, Node* new_entry, bool clone_limit_check) {
   return PhaseIdealLoop::clone_loop_predicates(old_entry, new_entry, clone_limit_check, NULL, this);
 }
 // Interface from PhaseIdealLoop
 Node* PhaseIdealLoop::clone_loop_predicates(Node* old_entry, Node* new_entry, bool clone_limit_check) {
   return clone_loop_predicates(old_entry, new_entry, clone_limit_check, this, &this->_igvn);
 }
 // Clone loop predicates to cloned loops (peeled, unswitched, split_if).
 Node* PhaseIdealLoop::clone_loop_predicates(Node* old_entry, Node* new_entry,
                                                 bool clone_limit_check,
                                                 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;
   ProjNode* limit_check_proj = NULL;
   if (LoopLimitCheck) {
     limit_check_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check);
     if (limit_check_proj != NULL) {
       entry = entry->in(0)->in(0);
     }
   }
   if (UseLoopPredicate) {
     ProjNode* predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
     if (predicate_proj != NULL) { // right pattern that can be used by loop predication
       // 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("Loop Predicate cloned: ");
         debug_only( new_entry->in(0)->dump(); )
       }
     }
   }
   if (limit_check_proj != NULL && clone_limit_check) {
     // Clone loop limit check last to insert it before loop.
     // Don't clone a limit check which was already finalized
     // for this counted loop (only one limit check is needed).
     new_entry = clone_predicate(limit_check_proj, new_entry,
                                 Deoptimization::Reason_loop_limit_check,
                                 loop_phase, igvn);
     assert(new_entry != NULL && new_entry->is_Proj(), "IfTrue or IfFalse after clone limit check");
     if (TraceLoopLimitCheck) {
       tty->print("Loop Limit Check cloned: ");
       debug_only( new_entry->in(0)->dump(); )
     }
   }
   return new_entry;
 }
 //--------------------------skip_loop_predicates------------------------------
 // Skip related predicates.
 Node* PhaseIdealLoop::skip_loop_predicates(Node* entry) {
   Node* predicate = NULL;
   if (LoopLimitCheck) {
     predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check);
     if (predicate != NULL) {
       entry = entry->in(0)->in(0);
     }
   }
   if (UseLoopPredicate) {
     predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
     if (predicate != NULL) { // right pattern that can be used by loop predication
       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 (start_c->as_Proj()->is_uncommon_trap_if_pattern(reason)) {
     return start_c->as_Proj();
   }
   return NULL;
 }
 //--------------------------find_predicate------------------------------------
 // Find a predicate
 Node* PhaseIdealLoop::find_predicate(Node* entry) {
   Node* predicate = NULL;
   if (LoopLimitCheck) {
     predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check);
     if (predicate != NULL) { // right pattern that can be used by loop predication
       return entry;
     }
   }
   if (UseLoopPredicate) {
     predicate = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
     if (predicate != NULL) { // right pattern that can be used by loop predication
       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) {
           // If n's control is a predicate that was moved out of the
           // loop, it was marked invariant but n is only invariant if
           // it depends only on that test. Otherwise, unless that test
           // is out of the loop, it's not invariant.
           if (n->is_CFG() || n->depends_only_on_test() || n->in(0) == NULL || !_phase->is_member(_lpt, n->in(0))) {
             _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 (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(IdealLoopTree *loop, Node* ctrl,
                                        int scale, Node* offset,
                                        Node* init, Node* limit, Node* stride,
                                        Node* range, bool upper) {
   stringStream* predString = NULL;
   if (TraceLoopPredicate) {
     predString = new stringStream();
     predString->print("rc_predicate ");
   }
   Node* max_idx_expr  = init;
   int stride_con = stride->get_int();
   if ((stride_con > 0) == (scale > 0) == upper) {
     if (LoopLimitCheck) {
       // With LoopLimitCheck limit is not exact.
       // Calculate exact limit here.
       // Note, counted loop's test is '<' or '>'.
       limit = exact_limit(loop);
       max_idx_expr = new (C) SubINode(limit, stride);
       register_new_node(max_idx_expr, ctrl);
       if (TraceLoopPredicate) predString->print("(limit - stride) ");
     } else {
       max_idx_expr = new (C) SubINode(limit, stride);
       register_new_node(max_idx_expr, ctrl);
       if (TraceLoopPredicate) predString->print("(limit - stride) ");
     }
   } else {
     if (TraceLoopPredicate) predString->print("init ");
   }
   if (scale != 1) {
     ConNode* con_scale = _igvn.intcon(scale);
     max_idx_expr = new (C) MulINode(max_idx_expr, con_scale);
     register_new_node(max_idx_expr, ctrl);
     if (TraceLoopPredicate) predString->print("* %d ", scale);
   }
   if (offset && (!offset->is_Con() || offset->get_int() != 0)){
     max_idx_expr = new (C) AddINode(max_idx_expr, offset);
     register_new_node(max_idx_expr, ctrl);
     if (TraceLoopPredicate)
       if (offset->is_Con()) predString->print("+ %d ", offset->get_int());
       else predString->print("+ offset ");
   }
   CmpUNode* cmp = new (C) CmpUNode(max_idx_expr, range);
   register_new_node(cmp, ctrl);
   BoolNode* bol = new (C) BoolNode(cmp, BoolTest::lt);
   register_new_node(bol, ctrl);
   if (TraceLoopPredicate) {
     predString->print_cr("<u range");
     tty->print("%s", predString->as_string());
   }
   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;
   }
   LoopNode* head = loop->_head->as_Loop();
   if (head->unique_ctrl_out()->Opcode() == Op_NeverBranch) {
     // do nothing for infinite loops
     return false;
   }
   CountedLoopNode *cl = NULL;
   if (head->is_valid_counted_loop()) {
     cl = head->as_CountedLoop();
     // do nothing for iteration-splitted loops
     if (!cl->is_normal_loop()) return false;
     // Avoid RCE if Counted loop's test is '!='.
     BoolTest::mask bt = cl->loopexit()->test_trip();
     if (bt != BoolTest::lt && bt != BoolTest::gt)
       cl = NULL;
   }
   Node* entry = head->in(LoopNode::EntryControl);
   ProjNode *predicate_proj = NULL;
   // Loop limit check predicate should be near the loop.
   if (LoopLimitCheck) {
     predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check);
     if (predicate_proj != NULL)
       entry = predicate_proj->in(0)->in(0);
   }
   predicate_proj = find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
   if (!predicate_proj) {
 #ifndef PRODUCT
     if (TraceLoopPredicate) {
       tty->print("missing predicate:");
       loop->dump_head();
       head->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);
   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 (!proj->is_uncommon_trap_if_pattern(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) 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) && (proj->_con == predicate_proj->_con) &&
                loop->is_range_check_if(iff, this, invar)) {
       // 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");
       Node* rng = cmp->in(2);
       assert(rng->Opcode() == Op_LoadRange || _igvn.type(rng)->is_int() >= 0, "must be");
       assert(invar.is_invariant(rng), "range must be invariant");
       int scale    = 1;
       Node* offset = zero;
       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(loop, ctrl, scale, offset, init, limit, stride, rng, false);
       IfNode* lower_bound_iff = lower_bound_proj->in(0)->as_If();
       _igvn.hash_delete(lower_bound_iff);
       lower_bound_iff->set_req(1, lower_bound_bol);
       if (TraceLoopPredicate) tty->print_cr("lower bound check if: %d", lower_bound_iff->_idx);
       // Test the upper bound
       Node* upper_bound_bol = rc_predicate(loop, lower_bound_proj, 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;
 }

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/opto/loopPredicate.cpp@04ff2f6cd0eb (annotated)

src/share/vm/opto/loopPredicate.cpp