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23 
24 
25 package org.graalvm.compiler.phases.common;
26 
27 import java.util.List;
28 
29 import jdk.internal.vm.compiler.collections.EconomicMap;
30 import org.graalvm.compiler.debug.GraalError;
31 import org.graalvm.compiler.graph.Node;
32 import org.graalvm.compiler.nodes.AbstractBeginNode;
33 import org.graalvm.compiler.nodes.AbstractMergeNode;
34 import org.graalvm.compiler.nodes.DeoptimizingNode;
35 import org.graalvm.compiler.nodes.FixedNode;
36 import org.graalvm.compiler.nodes.FrameState;
37 import org.graalvm.compiler.nodes.LoopBeginNode;
38 import org.graalvm.compiler.nodes.LoopExitNode;
39 import org.graalvm.compiler.nodes.StateSplit;
40 import org.graalvm.compiler.nodes.StructuredGraph;
41 import org.graalvm.compiler.nodes.StructuredGraph.GuardsStage;
42 import org.graalvm.compiler.nodes.util.GraphUtil;
43 import org.graalvm.compiler.phases.Phase;
44 import org.graalvm.compiler.phases.graph.ReentrantNodeIterator;
45 import org.graalvm.compiler.phases.graph.ReentrantNodeIterator.NodeIteratorClosure;
46 
47 import jdk.vm.ci.code.BytecodeFrame;
48 
49 /**
50  * This phase transfers {@link FrameState} nodes from {@link StateSplit} nodes to
51  * {@link DeoptimizingNode DeoptimizingNodes}.
52  *
53  * This allow to enter the {@link GuardsStage#AFTER_FSA AFTER_FSA} stage of the graph where no new
54  * node that may cause deoptimization can be introduced anymore.
55  * <p>
56  * This Phase processes the graph in post order, assigning the {@link FrameState} from the last
57  * {@link StateSplit} node to {@link DeoptimizingNode DeoptimizingNodes}.
58  */
59 public class FrameStateAssignmentPhase extends Phase {
60 
61     private static class FrameStateAssignmentClosure extends NodeIteratorClosure<FrameState> {
62 
63         @Override
processNode(FixedNode node, FrameState previousState)64         protected FrameState processNode(FixedNode node, FrameState previousState) {
65             FrameState currentState = previousState;
66             if (node instanceof DeoptimizingNode.DeoptBefore) {
67                 DeoptimizingNode.DeoptBefore deopt = (DeoptimizingNode.DeoptBefore) node;
68                 if (deopt.canDeoptimize() && deopt.stateBefore() == null) {
69                     GraalError.guarantee(currentState != null, "no FrameState at DeoptimizingNode %s", deopt);
70                     deopt.setStateBefore(currentState);
71                 }
72             }
73 
74             if (node instanceof StateSplit) {
75                 StateSplit stateSplit = (StateSplit) node;
76                 FrameState stateAfter = stateSplit.stateAfter();
77                 if (stateAfter != null) {
78                     if (stateAfter.bci == BytecodeFrame.INVALID_FRAMESTATE_BCI) {
79                         currentState = null;
80                     } else {
81                         currentState = stateAfter;
82                     }
83                     stateSplit.setStateAfter(null);
84                 }
85             }
86 
87             if (node instanceof DeoptimizingNode.DeoptDuring) {
88                 DeoptimizingNode.DeoptDuring deopt = (DeoptimizingNode.DeoptDuring) node;
89                 if (deopt.canDeoptimize()) {
90                     GraalError.guarantee(currentState != null, "no FrameState at DeoptimizingNode %s", deopt);
91                     deopt.computeStateDuring(currentState);
92                 }
93             }
94 
95             if (node instanceof DeoptimizingNode.DeoptAfter) {
96                 DeoptimizingNode.DeoptAfter deopt = (DeoptimizingNode.DeoptAfter) node;
97                 if (deopt.canDeoptimize() && deopt.stateAfter() == null) {
98                     GraalError.guarantee(currentState != null, "no FrameState at DeoptimizingNode %s", deopt);
99                     deopt.setStateAfter(currentState);
100                 }
101             }
102 
103             return currentState;
104         }
105 
106         @Override
merge(AbstractMergeNode merge, List<FrameState> states)107         protected FrameState merge(AbstractMergeNode merge, List<FrameState> states) {
108             FrameState singleFrameState = singleFrameState(states);
109             return singleFrameState == null ? merge.stateAfter() : singleFrameState;
110         }
111 
112         @Override
afterSplit(AbstractBeginNode node, FrameState oldState)113         protected FrameState afterSplit(AbstractBeginNode node, FrameState oldState) {
114             return oldState;
115         }
116 
117         @Override
processLoop(LoopBeginNode loop, FrameState initialState)118         protected EconomicMap<LoopExitNode, FrameState> processLoop(LoopBeginNode loop, FrameState initialState) {
119             return ReentrantNodeIterator.processLoop(this, loop, initialState).exitStates;
120         }
121     }
122 
123     @Override
run(StructuredGraph graph)124     protected void run(StructuredGraph graph) {
125         assert !graph.getGuardsStage().allowsFloatingGuards() && !hasFloatingDeopts(graph);
126         if (graph.getGuardsStage().areFrameStatesAtSideEffects()) {
127             ReentrantNodeIterator.apply(new FrameStateAssignmentClosure(), graph.start(), null);
128             graph.setGuardsStage(GuardsStage.AFTER_FSA);
129             graph.getNodes(FrameState.TYPE).filter(state -> state.hasNoUsages()).forEach(GraphUtil::killWithUnusedFloatingInputs);
130         }
131     }
132 
hasFloatingDeopts(StructuredGraph graph)133     private static boolean hasFloatingDeopts(StructuredGraph graph) {
134         for (Node n : graph.getNodes()) {
135             if (n instanceof DeoptimizingNode && GraphUtil.isFloatingNode(n)) {
136                 DeoptimizingNode deoptimizingNode = (DeoptimizingNode) n;
137                 if (deoptimizingNode.canDeoptimize()) {
138                     return true;
139                 }
140             }
141         }
142         return false;
143     }
144 
singleFrameState(List<FrameState> states)145     private static FrameState singleFrameState(List<FrameState> states) {
146         FrameState singleState = states.get(0);
147         for (int i = 1; i < states.size(); ++i) {
148             if (states.get(i) != singleState) {
149                 return null;
150             }
151         }
152         if (singleState != null && singleState.bci != BytecodeFrame.INVALID_FRAMESTATE_BCI) {
153             return singleState;
154         }
155         return null;
156     }
157 
158     @Override
checkContract()159     public boolean checkContract() {
160         // TODO GR-1409
161         return false;
162     }
163 }
164