FrameStateAssignmentPhase.java revision 12651:6ef01bd40ce2 
1/*
2 * Copyright (c) 2013, 2016, 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 */
23package org.graalvm.compiler.phases.common;
24
25import java.util.List;
26import java.util.Map;
27
28import org.graalvm.compiler.debug.GraalError;
29import org.graalvm.compiler.graph.Node;
30import org.graalvm.compiler.nodes.AbstractBeginNode;
31import org.graalvm.compiler.nodes.AbstractMergeNode;
32import org.graalvm.compiler.nodes.DeoptimizingNode;
33import org.graalvm.compiler.nodes.FixedNode;
34import org.graalvm.compiler.nodes.FrameState;
35import org.graalvm.compiler.nodes.LoopBeginNode;
36import org.graalvm.compiler.nodes.LoopExitNode;
37import org.graalvm.compiler.nodes.StateSplit;
38import org.graalvm.compiler.nodes.StructuredGraph;
39import org.graalvm.compiler.nodes.StructuredGraph.GuardsStage;
40import org.graalvm.compiler.nodes.util.GraphUtil;
41import org.graalvm.compiler.phases.Phase;
42import org.graalvm.compiler.phases.graph.ReentrantNodeIterator;
43import org.graalvm.compiler.phases.graph.ReentrantNodeIterator.NodeIteratorClosure;
44
45/**
46 * This phase transfers {@link FrameState} nodes from {@link StateSplit} nodes to
47 * {@link DeoptimizingNode DeoptimizingNodes}.
48 *
49 * This allow to enter the {@link GuardsStage#AFTER_FSA AFTER_FSA} stage of the graph where no new
50 * node that may cause deoptimization can be introduced anymore.
51 * <p>
52 * This Phase processes the graph in post order, assigning the {@link FrameState} from the last
53 * {@link StateSplit} node to {@link DeoptimizingNode DeoptimizingNodes}.
54 */
55public class FrameStateAssignmentPhase extends Phase {
56
57    private static class FrameStateAssignmentClosure extends NodeIteratorClosure<FrameState> {
58
59        @Override
60        protected FrameState processNode(FixedNode node, FrameState previousState) {
61            FrameState currentState = previousState;
62            if (node instanceof DeoptimizingNode.DeoptBefore) {
63                DeoptimizingNode.DeoptBefore deopt = (DeoptimizingNode.DeoptBefore) node;
64                if (deopt.canDeoptimize() && deopt.stateBefore() == null) {
65                    GraalError.guarantee(currentState != null, "no FrameState at DeoptimizingNode %s", deopt);
66                    deopt.setStateBefore(currentState);
67                }
68            }
69
70            if (node instanceof StateSplit) {
71                StateSplit stateSplit = (StateSplit) node;
72                FrameState stateAfter = stateSplit.stateAfter();
73                if (stateAfter != null) {
74                    currentState = stateAfter;
75                    stateSplit.setStateAfter(null);
76                }
77            }
78
79            if (node instanceof DeoptimizingNode.DeoptDuring) {
80                DeoptimizingNode.DeoptDuring deopt = (DeoptimizingNode.DeoptDuring) node;
81                if (deopt.canDeoptimize()) {
82                    GraalError.guarantee(currentState != null, "no FrameState at DeoptimizingNode %s", deopt);
83                    deopt.computeStateDuring(currentState);
84                }
85            }
86
87            if (node instanceof DeoptimizingNode.DeoptAfter) {
88                DeoptimizingNode.DeoptAfter deopt = (DeoptimizingNode.DeoptAfter) node;
89                if (deopt.canDeoptimize() && deopt.stateAfter() == null) {
90                    GraalError.guarantee(currentState != null, "no FrameState at DeoptimizingNode %s", deopt);
91                    deopt.setStateAfter(currentState);
92                }
93            }
94
95            return currentState;
96        }
97
98        @Override
99        protected FrameState merge(AbstractMergeNode merge, List<FrameState> states) {
100            FrameState singleFrameState = singleFrameState(states);
101            return singleFrameState == null ? merge.stateAfter() : singleFrameState;
102        }
103
104        @Override
105        protected FrameState afterSplit(AbstractBeginNode node, FrameState oldState) {
106            return oldState;
107        }
108
109        @Override
110        protected Map<LoopExitNode, FrameState> processLoop(LoopBeginNode loop, FrameState initialState) {
111            return ReentrantNodeIterator.processLoop(this, loop, initialState).exitStates;
112        }
113    }
114
115    @Override
116    protected void run(StructuredGraph graph) {
117        assert !graph.getGuardsStage().allowsFloatingGuards() && !hasFloatingDeopts(graph);
118        if (graph.getGuardsStage().areFrameStatesAtSideEffects()) {
119            ReentrantNodeIterator.apply(new FrameStateAssignmentClosure(), graph.start(), null);
120            graph.setGuardsStage(GuardsStage.AFTER_FSA);
121            graph.getNodes(FrameState.TYPE).filter(state -> state.hasNoUsages()).forEach(GraphUtil::killWithUnusedFloatingInputs);
122        }
123    }
124
125    private static boolean hasFloatingDeopts(StructuredGraph graph) {
126        for (Node n : graph.getNodes()) {
127            if (n instanceof DeoptimizingNode && GraphUtil.isFloatingNode(n)) {
128                DeoptimizingNode deoptimizingNode = (DeoptimizingNode) n;
129                if (deoptimizingNode.canDeoptimize()) {
130                    return true;
131                }
132            }
133        }
134        return false;
135    }
136
137    private static FrameState singleFrameState(List<FrameState> states) {
138        FrameState singleState = states.get(0);
139        for (int i = 1; i < states.size(); ++i) {
140            if (states.get(i) != singleState) {
141                return null;
142            }
143        }
144        return singleState;
145    }
146
147    @Override
148    public boolean checkContract() {
149        // TODO GR-1409
150        return false;
151    }
152}
153