MatchStatement.java

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * This code is free software; you can redistribute it and/or modify it
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 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
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 * 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).
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package org.graalvm.compiler.core.match;

import static org.graalvm.compiler.debug.DebugOptions.LogVerbose;

import org.graalvm.compiler.core.gen.NodeLIRBuilder;
import org.graalvm.compiler.core.match.MatchPattern.MatchResultCode;
import org.graalvm.compiler.core.match.MatchPattern.Result;
import org.graalvm.compiler.debug.CounterKey;
import org.graalvm.compiler.debug.DebugContext;
import org.graalvm.compiler.graph.GraalGraphError;
import org.graalvm.compiler.graph.Node;
import org.graalvm.compiler.nodeinfo.Verbosity;

import jdk.vm.ci.meta.Value;
import org.graalvm.compiler.nodes.StructuredGraph;
import org.graalvm.compiler.nodes.cfg.Block;

/**
 * A named {@link MatchPattern} along with a {@link MatchGenerator} that can be evaluated to replace
 * one or more {@link Node}s with a single {@link Value}.
 */

public class MatchStatement {
    private static final CounterKey MatchStatementSuccess = DebugContext.counter("MatchStatementSuccess");

    /**
     * A printable name for this statement. Usually it's just the name of the method doing the
     * emission.
     */
    private final String name;

    /**
     * The actual match pattern.
     */
    private final MatchPattern pattern;

    /**
     * The method in the {@link NodeLIRBuilder} subclass that will actually do the code emission.
     */
    private MatchGenerator generatorMethod;

    /**
     * The name of arguments in the order they are expected to be passed to the generator method.
     */
    private String[] arguments;

    public MatchStatement(String name, MatchPattern pattern, MatchGenerator generator, String[] arguments) {
        this.name = name;
        this.pattern = pattern;
        this.generatorMethod = generator;
        this.arguments = arguments;
    }

    /**
     * Attempt to match the current statement against a Node.
     *
     * @param builder the current builder instance.
     * @param node the node to be matched
     * @param block the current block
     * @param schedule the schedule that's being used
     * @return true if the statement matched something and set a {@link ComplexMatchResult} to be
     *         evaluated by the NodeLIRBuilder.
     */
    public boolean generate(NodeLIRBuilder builder, int index, Node node, Block block, StructuredGraph.ScheduleResult schedule) {
        DebugContext debug = node.getDebug();
        assert index == schedule.getBlockToNodesMap().get(block).indexOf(node);
        // Check that the basic shape matches
        Result result = pattern.matchShape(node, this);
        if (result != Result.OK) {
            return false;
        }
        // Now ensure that the other safety constraints are matched.
        MatchContext context = new MatchContext(builder, this, index, node, block, schedule);
        result = pattern.matchUsage(node, context);
        if (result == Result.OK) {
            // Invoke the generator method and set the result if it's non null.
            ComplexMatchResult value = generatorMethod.match(builder.getNodeMatchRules(), buildArgList(context));
            if (value != null) {
                context.setResult(value);
                MatchStatementSuccess.increment(debug);
                DebugContext.counter("MatchStatement[%s]", getName()).increment(debug);
                return true;
            }
            // The pattern matched but some other code generation constraint disallowed code
            // generation for the pattern.
            if (LogVerbose.getValue(node.getOptions())) {
                debug.log("while matching %s|%s %s %s returned null", context.getRoot().toString(Verbosity.Id), context.getRoot().getClass().getSimpleName(), getName(), generatorMethod.getName());
                debug.log("with nodes %s", formatMatch(node));
            }
        } else {
            if (LogVerbose.getValue(node.getOptions()) && result.code != MatchResultCode.WRONG_CLASS) {
                debug.log("while matching %s|%s %s %s", context.getRoot().toString(Verbosity.Id), context.getRoot().getClass().getSimpleName(), getName(), result);
            }
        }
        return false;
    }

    /**
     * @param context
     * @return the Nodes captured by the match rule in the order expected by the generatorMethod
     */
    private Object[] buildArgList(MatchContext context) {
        Object[] result = new Object[arguments.length];
        for (int i = 0; i < arguments.length; i++) {
            if ("root".equals(arguments[i])) {
                result[i] = context.getRoot();
            } else {
                result[i] = context.namedNode(arguments[i]);
                if (result[i] == null) {
                    throw new GraalGraphError("Can't find named node %s", arguments[i]);
                }
            }
        }
        return result;
    }

    public String formatMatch(Node root) {
        return pattern.formatMatch(root);
    }

    public MatchPattern getPattern() {
        return pattern;
    }

    public String getName() {
        return name;
    }

    @Override
    public String toString() {
        return pattern.toString();
    }
}