SLReadPropertyCacheNode.java

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package com.oracle.truffle.sl.nodes.access;

import com.oracle.truffle.api.CompilerAsserts;
import com.oracle.truffle.api.CompilerDirectives;
import com.oracle.truffle.api.CompilerDirectives.TruffleBoundary;
import com.oracle.truffle.api.dsl.Cached;
import com.oracle.truffle.api.dsl.Fallback;
import com.oracle.truffle.api.dsl.Specialization;
import com.oracle.truffle.api.interop.ForeignAccess;
import com.oracle.truffle.api.interop.Message;
import com.oracle.truffle.api.interop.TruffleObject;
import com.oracle.truffle.api.interop.UnknownIdentifierException;
import com.oracle.truffle.api.interop.UnsupportedMessageException;
import com.oracle.truffle.api.nodes.Node;
import com.oracle.truffle.api.object.DynamicObject;
import com.oracle.truffle.api.object.Location;
import com.oracle.truffle.api.object.Property;
import com.oracle.truffle.api.object.Shape;
import com.oracle.truffle.sl.nodes.interop.SLForeignToSLTypeNode;
import com.oracle.truffle.sl.nodes.interop.SLForeignToSLTypeNodeGen;
import com.oracle.truffle.sl.runtime.SLUndefinedNameException;

public abstract class SLReadPropertyCacheNode extends SLPropertyCacheNode {

    public abstract Object executeRead(Object receiver, Object name);

    /**
     * Polymorphic inline cache for a limited number of distinct property names and shapes.
     */
    @Specialization(limit = "CACHE_LIMIT", //
                    guards = {
                                    "namesEqual(cachedName, name)",
                                    "shapeCheck(shape, receiver)"
                    }, //
                    assumptions = {
                                    "shape.getValidAssumption()"
                    })
    protected static Object readCached(DynamicObject receiver, @SuppressWarnings("unused") Object name,
                    @SuppressWarnings("unused") @Cached("name") Object cachedName,
                    @Cached("lookupShape(receiver)") Shape shape,
                    @Cached("lookupLocation(shape, name)") Location location) {

        return location.get(receiver, shape);
    }

    protected static Location lookupLocation(Shape shape, Object name) {
        /* Initialization of cached values always happens in a slow path. */
        CompilerAsserts.neverPartOfCompilation();

        Property property = shape.getProperty(name);
        if (property == null) {
            /* Property does not exist. */
            throw SLUndefinedNameException.undefinedProperty(name);
        }

        return property.getLocation();
    }

    /**
     * The generic case is used if the number of shapes accessed overflows the limit of the
     * polymorphic inline cache.
     */
    @TruffleBoundary
    @Specialization(replaces = {"readCached"}, guards = {"isValidSLObject(receiver)"})
    protected static Object readUncached(DynamicObject receiver, Object name) {

        Object result = receiver.get(name);
        if (result == null) {
            /* Property does not exist. */
            throw SLUndefinedNameException.undefinedProperty(name);
        }
        return result;
    }

    /**
     * When no specialization fits, the receiver is either not an object (which is a type error), or
     * the object has a shape that has been invalidated.
     */
    @Fallback
    protected static Object updateShape(Object r, Object name) {
        /*
         * Slow path that we do not handle in compiled code. But no need to invalidate compiled
         * code.
         */
        CompilerDirectives.transferToInterpreter();

        if (!(r instanceof DynamicObject)) {
            /* Non-object types do not have properties. */
            throw SLUndefinedNameException.undefinedProperty(name);
        }
        DynamicObject receiver = (DynamicObject) r;
        receiver.updateShape();
        return readUncached(receiver, name);

    }

    /**
     * Language interoperability: if the receiver object is a foreign value we use Truffle's interop
     * API to access the foreign data.
     */
    @Specialization(guards = "isForeignObject(receiver)")
    protected static Object readForeign(TruffleObject receiver, Object name,
                    // The child node to access the foreign object
                    @Cached("createForeignReadNode()") Node foreignReadNode,
                    // The child node to convert the result of the foreign read to a SL value
                    @Cached("createToSLTypeNode()") SLForeignToSLTypeNode toSLTypeNode) {

        try {
            /* Perform the foreign object access. */
            Object result = ForeignAccess.sendRead(foreignReadNode, receiver, name);
            /* Convert the result to a SL value. */
            return toSLTypeNode.executeConvert(result);

        } catch (UnknownIdentifierException | UnsupportedMessageException e) {
            /* Foreign access was not successful. */
            throw SLUndefinedNameException.undefinedProperty(name);
        }
    }

    protected static Node createForeignReadNode() {
        return Message.READ.createNode();
    }

    protected static SLForeignToSLTypeNode createToSLTypeNode() {
        return SLForeignToSLTypeNodeGen.create();
    }
}