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23 
24 
25 package org.graalvm.compiler.phases.schedule;
26 
27 import java.util.List;
28 
29 import jdk.internal.vm.compiler.collections.EconomicSet;
30 import jdk.internal.vm.compiler.collections.Equivalence;
31 import org.graalvm.compiler.core.common.cfg.BlockMap;
32 import org.graalvm.compiler.core.common.cfg.Loop;
33 import org.graalvm.compiler.debug.DebugContext;
34 import org.graalvm.compiler.graph.Node;
35 import org.graalvm.compiler.graph.NodeMap;
36 import org.graalvm.compiler.nodes.AbstractBeginNode;
37 import org.graalvm.compiler.nodes.AbstractMergeNode;
38 import org.graalvm.compiler.nodes.LoopBeginNode;
39 import org.graalvm.compiler.nodes.LoopExitNode;
40 import org.graalvm.compiler.nodes.MemoryProxyNode;
41 import org.graalvm.compiler.nodes.PhiNode;
42 import org.graalvm.compiler.nodes.ProxyNode;
43 import org.graalvm.compiler.nodes.StructuredGraph;
44 import org.graalvm.compiler.nodes.VirtualState;
45 import org.graalvm.compiler.nodes.cfg.Block;
46 import org.graalvm.compiler.nodes.cfg.HIRLoop;
47 import org.graalvm.compiler.nodes.memory.FloatingReadNode;
48 import org.graalvm.compiler.nodes.memory.MemoryCheckpoint;
49 import org.graalvm.compiler.nodes.memory.MemoryNode;
50 import org.graalvm.compiler.nodes.memory.MemoryPhiNode;
51 import org.graalvm.compiler.phases.graph.ReentrantBlockIterator;
52 import org.graalvm.compiler.phases.graph.ReentrantBlockIterator.BlockIteratorClosure;
53 import jdk.internal.vm.compiler.word.LocationIdentity;
54 
55 /**
56  * Verifies that the schedule of the graph is correct. Checks that floating reads are not killed
57  * between definition and usage. Also checks that there are no usages spanning loop exits without a
58  * proper proxy node.
59  */
60 public final class ScheduleVerification extends BlockIteratorClosure<EconomicSet<FloatingReadNode>> {
61 
62     private final BlockMap<List<Node>> blockToNodesMap;
63     private final NodeMap<Block> nodeMap;
64     private final StructuredGraph graph;
65 
check(Block startBlock, BlockMap<List<Node>> blockToNodesMap, NodeMap<Block> nodeMap)66     public static boolean check(Block startBlock, BlockMap<List<Node>> blockToNodesMap, NodeMap<Block> nodeMap) {
67         ReentrantBlockIterator.apply(new ScheduleVerification(blockToNodesMap, nodeMap, startBlock.getBeginNode().graph()), startBlock);
68         return true;
69     }
70 
ScheduleVerification(BlockMap<List<Node>> blockToNodesMap, NodeMap<Block> nodeMap, StructuredGraph graph)71     private ScheduleVerification(BlockMap<List<Node>> blockToNodesMap, NodeMap<Block> nodeMap, StructuredGraph graph) {
72         this.blockToNodesMap = blockToNodesMap;
73         this.nodeMap = nodeMap;
74         this.graph = graph;
75     }
76 
77     @Override
getInitialState()78     protected EconomicSet<FloatingReadNode> getInitialState() {
79         return EconomicSet.create(Equivalence.IDENTITY);
80     }
81 
82     @Override
processBlock(Block block, EconomicSet<FloatingReadNode> currentState)83     protected EconomicSet<FloatingReadNode> processBlock(Block block, EconomicSet<FloatingReadNode> currentState) {
84         AbstractBeginNode beginNode = block.getBeginNode();
85         if (beginNode instanceof AbstractMergeNode) {
86             AbstractMergeNode abstractMergeNode = (AbstractMergeNode) beginNode;
87             for (PhiNode phi : abstractMergeNode.phis()) {
88                 if (phi instanceof MemoryPhiNode) {
89                     MemoryPhiNode memoryPhiNode = (MemoryPhiNode) phi;
90                     addFloatingReadUsages(currentState, memoryPhiNode);
91                 }
92             }
93         }
94         if (beginNode instanceof LoopExitNode) {
95             LoopExitNode loopExitNode = (LoopExitNode) beginNode;
96             for (ProxyNode proxy : loopExitNode.proxies()) {
97                 if (proxy instanceof MemoryProxyNode) {
98                     MemoryProxyNode memoryProxyNode = (MemoryProxyNode) proxy;
99                     addFloatingReadUsages(currentState, memoryProxyNode);
100                 }
101             }
102         }
103         for (Node n : blockToNodesMap.get(block)) {
104             if (n instanceof MemoryCheckpoint) {
105                 if (n instanceof MemoryCheckpoint.Single) {
106                     MemoryCheckpoint.Single single = (MemoryCheckpoint.Single) n;
107                     processLocation(n, single.getKilledLocationIdentity(), currentState);
108                 } else if (n instanceof MemoryCheckpoint.Multi) {
109                     MemoryCheckpoint.Multi multi = (MemoryCheckpoint.Multi) n;
110                     for (LocationIdentity location : multi.getKilledLocationIdentities()) {
111                         processLocation(n, location, currentState);
112                     }
113                 }
114 
115                 addFloatingReadUsages(currentState, n);
116             } else if (n instanceof MemoryNode) {
117                 addFloatingReadUsages(currentState, n);
118             } else if (n instanceof FloatingReadNode) {
119                 FloatingReadNode floatingReadNode = (FloatingReadNode) n;
120                 if (floatingReadNode.getLastLocationAccess() != null && floatingReadNode.getLocationIdentity().isMutable()) {
121                     if (currentState.contains(floatingReadNode)) {
122                         // Floating read was found in the state.
123                         currentState.remove(floatingReadNode);
124                     } else {
125                         throw new RuntimeException("Floating read node " + n + " was not found in the state, i.e., it was killed by a memory check point before its place in the schedule. Block=" +
126                                         block + ", block begin: " + block.getBeginNode() + " block loop: " + block.getLoop() + ", " + blockToNodesMap.get(block).get(0));
127                     }
128                 }
129             }
130             assert nodeMap.get(n) == block;
131             if (graph.hasValueProxies() && block.getLoop() != null && !(n instanceof VirtualState)) {
132                 for (Node usage : n.usages()) {
133                     Node usageNode = usage;
134 
135                     if (usageNode instanceof PhiNode) {
136                         PhiNode phiNode = (PhiNode) usage;
137                         usageNode = phiNode.merge();
138                     }
139 
140                     if (usageNode instanceof LoopExitNode) {
141                         LoopExitNode loopExitNode = (LoopExitNode) usageNode;
142                         if (loopExitNode.loopBegin() == n || loopExitNode.stateAfter() == n) {
143                             continue;
144                         }
145                     }
146                     Block usageBlock = nodeMap.get(usageNode);
147 
148                     Loop<Block> usageLoop = null;
149                     if (usageNode instanceof ProxyNode) {
150                         ProxyNode proxyNode = (ProxyNode) usageNode;
151                         usageLoop = nodeMap.get(proxyNode.proxyPoint().loopBegin()).getLoop();
152                     } else {
153                         if (usageBlock.getBeginNode() instanceof LoopExitNode) {
154                             // For nodes in the loop exit node block, we don't know for sure
155                             // whether they are "in the loop" or not. It depends on whether
156                             // one of their transient usages is a loop proxy node.
157                             // For now, let's just assume those nodes are OK, i.e., "in the loop".
158                             LoopExitNode loopExitNode = (LoopExitNode) usageBlock.getBeginNode();
159                             usageLoop = nodeMap.get(loopExitNode.loopBegin()).getLoop();
160                         } else {
161                             usageLoop = usageBlock.getLoop();
162                         }
163                     }
164 
165                     assert usageLoop != null : n + ", " + nodeMap.get(n) + " / " + usageNode + ", " + nodeMap.get(usageNode);
166                     while (usageLoop != block.getLoop() && usageLoop != null) {
167                         usageLoop = usageLoop.getParent();
168                     }
169                     assert usageLoop != null : n + ", " + usageNode + ", " + usageBlock + ", " + usageBlock.getLoop() + ", " + block + ", " + block.getLoop();
170                 }
171             }
172         }
173         return currentState;
174     }
175 
addFloatingReadUsages(EconomicSet<FloatingReadNode> currentState, Node n)176     private static void addFloatingReadUsages(EconomicSet<FloatingReadNode> currentState, Node n) {
177         for (FloatingReadNode read : n.usages().filter(FloatingReadNode.class)) {
178             if (read.getLastLocationAccess() == n && read.getLocationIdentity().isMutable()) {
179                 currentState.add(read);
180             }
181         }
182     }
183 
processLocation(Node n, LocationIdentity location, EconomicSet<FloatingReadNode> currentState)184     private void processLocation(Node n, LocationIdentity location, EconomicSet<FloatingReadNode> currentState) {
185         assert n != null;
186         if (location.isImmutable()) {
187             return;
188         }
189 
190         for (FloatingReadNode r : cloneState(currentState)) {
191             if (r.getLocationIdentity().overlaps(location)) {
192                 // This read is killed by this location.
193                 r.getDebug().log(DebugContext.VERBOSE_LEVEL, "%s removing %s from state", n, r);
194                 currentState.remove(r);
195             }
196         }
197     }
198 
199     @Override
merge(Block merge, List<EconomicSet<FloatingReadNode>> states)200     protected EconomicSet<FloatingReadNode> merge(Block merge, List<EconomicSet<FloatingReadNode>> states) {
201         EconomicSet<FloatingReadNode> result = states.get(0);
202         for (int i = 1; i < states.size(); ++i) {
203             result.retainAll(states.get(i));
204         }
205         return result;
206     }
207 
208     @Override
cloneState(EconomicSet<FloatingReadNode> oldState)209     protected EconomicSet<FloatingReadNode> cloneState(EconomicSet<FloatingReadNode> oldState) {
210         EconomicSet<FloatingReadNode> result = EconomicSet.create(Equivalence.IDENTITY);
211         if (oldState != null) {
212             result.addAll(oldState);
213         }
214         return result;
215     }
216 
217     @Override
processLoop(Loop<Block> loop, EconomicSet<FloatingReadNode> initialState)218     protected List<EconomicSet<FloatingReadNode>> processLoop(Loop<Block> loop, EconomicSet<FloatingReadNode> initialState) {
219         HIRLoop l = (HIRLoop) loop;
220         for (MemoryPhiNode memoryPhi : ((LoopBeginNode) l.getHeader().getBeginNode()).memoryPhis()) {
221             for (FloatingReadNode r : cloneState(initialState)) {
222                 if (r.getLocationIdentity().overlaps(memoryPhi.getLocationIdentity())) {
223                     initialState.remove(r);
224                 }
225             }
226         }
227         return ReentrantBlockIterator.processLoop(this, loop, initialState).exitStates;
228     }
229 }
230