jdk8-mips64-public/hotspot: src/share/vm/opto/loopUnswitch.cpp@fd13a567f179 (annotated)

src/share/vm/opto/loopUnswitch.cpp@fd13a567f179 (annotated)

src/share/vm/opto/loopUnswitch.cpp

Thu, 24 May 2018 19:26:50 +0800

author: aoqi
date: Thu, 24 May 2018 19:26:50 +0800
changeset 8862: fd13a567f179
parent 7535: 7ae4e26cb1e0
permissions: -rw-r--r--

#7046 C2 supports long branch
Contributed-by: fujie

 /*
  * Copyright (c) 2006, 2012, 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 "memory/allocation.inline.hpp"
 #include "opto/connode.hpp"
 #include "opto/loopnode.hpp"
 #include "opto/rootnode.hpp"
 //================= Loop Unswitching =====================
 //
 // orig:                       transformed:
 //                               if (invariant-test) then
 //  predicate                      predicate
 //  loop                           loop
 //    stmt1                          stmt1
 //    if (invariant-test) then       stmt2
 //      stmt2                        stmt4
 //    else                         endloop
 //      stmt3                    else
 //    endif                        predicate [clone]
 //    stmt4                        loop [clone]
 //  endloop                          stmt1 [clone]
 //                                   stmt3
 //                                   stmt4 [clone]
 //                                 endloop
 //                               endif
 //
 // Note: the "else" clause may be empty
 //------------------------------policy_unswitching-----------------------------
 // Return TRUE or FALSE if the loop should be unswitched
 // (ie. clone loop with an invariant test that does not exit the loop)
 bool IdealLoopTree::policy_unswitching( PhaseIdealLoop *phase ) const {
   if( !LoopUnswitching ) {
     return false;
   }
   if (!_head->is_Loop()) {
     return false;
   }
   int nodes_left = phase->C->max_node_limit() - phase->C->live_nodes();
   if ((int)(2 * _body.size()) > nodes_left) {
     return false; // Too speculative if running low on nodes.
   }
   LoopNode* head = _head->as_Loop();
   if (head->unswitch_count() + 1 > head->unswitch_max()) {
     return false;
   }
   return phase->find_unswitching_candidate(this) != NULL;
 }
 //------------------------------find_unswitching_candidate-----------------------------
 // Find candidate "if" for unswitching
 IfNode* PhaseIdealLoop::find_unswitching_candidate(const IdealLoopTree *loop) const {
   // Find first invariant test that doesn't exit the loop
   LoopNode *head = loop->_head->as_Loop();
   IfNode* unswitch_iff = NULL;
   Node* n = head->in(LoopNode::LoopBackControl);
   while (n != head) {
     Node* n_dom = idom(n);
     if (n->is_Region()) {
       if (n_dom->is_If()) {
         IfNode* iff = n_dom->as_If();
         if (iff->in(1)->is_Bool()) {
           BoolNode* bol = iff->in(1)->as_Bool();
           if (bol->in(1)->is_Cmp()) {
             // If condition is invariant and not a loop exit,
             // then found reason to unswitch.
             if (loop->is_invariant(bol) && !loop->is_loop_exit(iff)) {
               unswitch_iff = iff;
             }
           }
         }
       }
     }
     n = n_dom;
   }
   return unswitch_iff;
 }
 //------------------------------do_unswitching-----------------------------
 // Clone loop with an invariant test (that does not exit) and
 // insert a clone of the test that selects which version to
 // execute.
 void PhaseIdealLoop::do_unswitching (IdealLoopTree *loop, Node_List &old_new) {
   // Find first invariant test that doesn't exit the loop
   LoopNode *head = loop->_head->as_Loop();
   IfNode* unswitch_iff = find_unswitching_candidate((const IdealLoopTree *)loop);
   assert(unswitch_iff != NULL, "should be at least one");
 #ifndef PRODUCT
   if (TraceLoopOpts) {
     tty->print("Unswitch   %d ", head->unswitch_count()+1);
     loop->dump_head();
   }
 #endif
   // Need to revert back to normal loop
   if (head->is_CountedLoop() && !head->as_CountedLoop()->is_normal_loop()) {
     head->as_CountedLoop()->set_normal_loop();
   }
   ProjNode* proj_true = create_slow_version_of_loop(loop, old_new);
 #ifdef ASSERT
   Node* uniqc = proj_true->unique_ctrl_out();
   Node* entry = head->in(LoopNode::EntryControl);
   Node* predicate = find_predicate(entry);
   if (predicate != NULL && LoopLimitCheck && UseLoopPredicate) {
     // We may have two predicates, find first.
     entry = find_predicate(entry->in(0)->in(0));
     if (entry != NULL) predicate = entry;
   }
   if (predicate != NULL) predicate = predicate->in(0);
   assert(proj_true->is_IfTrue() &&
          (predicate == NULL && uniqc == head ||
           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;
   head->set_unswitch_count(nct);
   head_clone->set_unswitch_count(nct);
   // Add test to new "if" outside of loop
   IfNode* invar_iff   = proj_true->in(0)->as_If();
   Node* invar_iff_c   = invar_iff->in(0);
   BoolNode* bol       = unswitch_iff->in(1)->as_Bool();
   invar_iff->set_req(1, bol);
   invar_iff->_prob    = unswitch_iff->_prob;
   ProjNode* proj_false = invar_iff->proj_out(0)->as_Proj();
   // Hoist invariant casts out of each loop to the appropriate
   // control projection.
   Node_List worklist;
   for (DUIterator_Fast imax, i = unswitch_iff->fast_outs(imax); i < imax; i++) {
     ProjNode* proj= unswitch_iff->fast_out(i)->as_Proj();
     // Copy to a worklist for easier manipulation
     for (DUIterator_Fast jmax, j = proj->fast_outs(jmax); j < jmax; j++) {
       Node* use = proj->fast_out(j);
       if (use->Opcode() == Op_CheckCastPP && loop->is_invariant(use->in(1))) {
         worklist.push(use);
       }
     }
     ProjNode* invar_proj = invar_iff->proj_out(proj->_con)->as_Proj();
     while (worklist.size() > 0) {
       Node* use = worklist.pop();
       Node* nuse = use->clone();
       nuse->set_req(0, invar_proj);
       _igvn.replace_input_of(use, 1, nuse);
       register_new_node(nuse, invar_proj);
       // Same for the clone
       Node* use_clone = old_new[use->_idx];
       _igvn.replace_input_of(use_clone, 1, nuse);
     }
   }
   // Hardwire the control paths in the loops into if(true) and if(false)
   _igvn.rehash_node_delayed(unswitch_iff);
   short_circuit_if(unswitch_iff, proj_true);
   IfNode* unswitch_iff_clone = old_new[unswitch_iff->_idx]->as_If();
   _igvn.rehash_node_delayed(unswitch_iff_clone);
   short_circuit_if(unswitch_iff_clone, proj_false);
   // Reoptimize loops
   loop->record_for_igvn();
   for(int i = loop->_body.size() - 1; i >= 0 ; i--) {
     Node *n = loop->_body[i];
     Node *n_clone = old_new[n->_idx];
     _igvn._worklist.push(n_clone);
   }
 #ifndef PRODUCT
   if (TraceLoopUnswitching) {
     tty->print_cr("Loop unswitching orig: %d @ %d  new: %d @ %d",
                   head->_idx,                unswitch_iff->_idx,
                   old_new[head->_idx]->_idx, unswitch_iff_clone->_idx);
   }
 #endif
   C->set_major_progress();
 }
 //-------------------------create_slow_version_of_loop------------------------
 // Create a slow version of the loop by cloning the loop
 // and inserting an if to select fast-slow versions.
 // Return control projection of the entry to the fast version.
 ProjNode* PhaseIdealLoop::create_slow_version_of_loop(IdealLoopTree *loop,
                                                       Node_List &old_new) {
   LoopNode* head  = loop->_head->as_Loop();
   bool counted_loop = head->is_CountedLoop();
   Node*     entry = head->in(LoopNode::EntryControl);
   _igvn.rehash_node_delayed(entry);
   IdealLoopTree* outer_loop = loop->_parent;
   Node *cont      = _igvn.intcon(1);
   set_ctrl(cont, C->root());
   Node* opq       = new (C) Opaque1Node(C, cont);
   register_node(opq, outer_loop, entry, dom_depth(entry));
   Node *bol       = new (C) Conv2BNode(opq);
   register_node(bol, outer_loop, entry, dom_depth(entry));
   IfNode* iff = new (C) IfNode(entry, bol, PROB_MAX, COUNT_UNKNOWN);
   register_node(iff, outer_loop, entry, dom_depth(entry));
   ProjNode* iffast = new (C) IfTrueNode(iff);
   register_node(iffast, outer_loop, iff, dom_depth(iff));
   ProjNode* ifslow = new (C) IfFalseNode(iff);
   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 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, !counted_loop);
   _igvn.replace_input_of(head, LoopNode::EntryControl, iffast_pred);
   set_idom(head, iffast_pred, dom_depth(head));
   // Slow (false) control
   Node* ifslow_pred = clone_loop_predicates(entry, ifslow, !counted_loop);
   LoopNode* slow_head = old_new[head->_idx]->as_Loop();
   _igvn.replace_input_of(slow_head, LoopNode::EntryControl, ifslow_pred);
   set_idom(slow_head, ifslow_pred, dom_depth(slow_head));
   recompute_dom_depth();
   return iffast;
 }

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/opto/loopUnswitch.cpp@fd13a567f179 (annotated)

src/share/vm/opto/loopUnswitch.cpp