1 /*
   2  * Copyright (c) 2017, 2019, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  */
  23 
  24 
  25 package org.graalvm.compiler.phases.common;
  26 
  27 import jdk.internal.vm.compiler.collections.EconomicMap;
  28 import jdk.internal.vm.compiler.collections.EconomicSet;
  29 import jdk.internal.vm.compiler.collections.Equivalence;
  30 import jdk.internal.vm.compiler.collections.MapCursor;
  31 import org.graalvm.compiler.graph.NodeStack;
  32 import org.graalvm.compiler.nodes.AbstractBeginNode;
  33 import org.graalvm.compiler.nodes.AbstractDeoptimizeNode;
  34 import org.graalvm.compiler.nodes.AbstractEndNode;
  35 import org.graalvm.compiler.nodes.AbstractMergeNode;
  36 import org.graalvm.compiler.nodes.ControlSplitNode;
  37 import org.graalvm.compiler.nodes.FixedNode;
  38 import org.graalvm.compiler.nodes.StructuredGraph;
  39 import org.graalvm.compiler.nodes.spi.CoreProviders;
  40 import org.graalvm.compiler.phases.BasePhase;
  41 
  42 /**
  43  * This phase will make sure that the branch leading towards this deopt has 0.0 probability.
  44  *
  45  */
  46 public class PropagateDeoptimizeProbabilityPhase extends BasePhase<CoreProviders> {
  47 
  48     @Override
  49     @SuppressWarnings("try")
  50     protected void run(final StructuredGraph graph, CoreProviders context) {
  51         assert !graph.hasValueProxies() : "ConvertDeoptimizeToGuardPhase always creates proxies";
  52 
  53         if (graph.hasNode(AbstractDeoptimizeNode.TYPE)) {
  54 
  55             NodeStack stack = new NodeStack();
  56             EconomicMap<ControlSplitNode, EconomicSet<AbstractBeginNode>> reachableSplits = EconomicMap.create(Equivalence.IDENTITY);
  57 
  58             // Mark all control flow nodes that are post-dominated by a deoptimization.
  59             for (AbstractDeoptimizeNode d : graph.getNodes(AbstractDeoptimizeNode.TYPE)) {
  60                 stack.push(AbstractBeginNode.prevBegin(d));
  61                 while (!stack.isEmpty()) {
  62                     AbstractBeginNode beginNode = (AbstractBeginNode) stack.pop();
  63                     FixedNode fixedNode = (FixedNode) beginNode.predecessor();
  64 
  65                     if (fixedNode == null) {
  66                         // Can happen for start node.
  67                     } else if (fixedNode instanceof AbstractMergeNode) {
  68                         AbstractMergeNode mergeNode = (AbstractMergeNode) fixedNode;
  69                         for (AbstractEndNode end : mergeNode.forwardEnds()) {
  70                             AbstractBeginNode newBeginNode = AbstractBeginNode.prevBegin(end);
  71                             stack.push(newBeginNode);
  72                         }
  73                     } else if (fixedNode instanceof ControlSplitNode) {
  74                         ControlSplitNode controlSplitNode = (ControlSplitNode) fixedNode;
  75                         EconomicSet<AbstractBeginNode> reachableSuccessors = reachableSplits.get(controlSplitNode);
  76                         if (reachableSuccessors == null) {
  77                             reachableSuccessors = EconomicSet.create();
  78                             reachableSplits.put(controlSplitNode, reachableSuccessors);
  79                         }
  80 
  81                         if (controlSplitNode.getSuccessorCount() == reachableSuccessors.size() - 1) {
  82                             // All successors of this split lead to deopt, propagate reachability
  83                             // further upwards.
  84                             reachableSplits.removeKey(controlSplitNode);
  85                             stack.push(AbstractBeginNode.prevBegin((FixedNode) controlSplitNode.predecessor()));
  86                         } else {
  87                             reachableSuccessors.add(beginNode);
  88                         }
  89                     } else {
  90                         stack.push(AbstractBeginNode.prevBegin(fixedNode));
  91                     }
  92                 }
  93             }
  94 
  95             // Make sure the probability on the path towards the deoptimization is 0.0.
  96             MapCursor<ControlSplitNode, EconomicSet<AbstractBeginNode>> entries = reachableSplits.getEntries();
  97             while (entries.advance()) {
  98                 ControlSplitNode controlSplitNode = entries.getKey();
  99                 EconomicSet<AbstractBeginNode> value = entries.getValue();
 100                 for (AbstractBeginNode begin : value) {
 101                     double probability = controlSplitNode.probability(begin);
 102                     if (probability != 0.0) {
 103                         controlSplitNode.setProbability(begin, 0.0);
 104                     }
 105                 }
 106             }
 107         }
 108     }
 109 }