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package com.oracle.truffle.js.nodes.function;

import java.util.Arrays;
import java.util.Set;

import com.oracle.truffle.api.CompilerAsserts;
import com.oracle.truffle.api.CompilerDirectives;
import com.oracle.truffle.api.dsl.NodeChild;
import com.oracle.truffle.api.frame.VirtualFrame;
import com.oracle.truffle.api.instrumentation.StandardTags;
import com.oracle.truffle.api.instrumentation.Tag;
import com.oracle.truffle.api.nodes.NodeInterface;
import com.oracle.truffle.js.nodes.JavaScriptNode;
import com.oracle.truffle.js.nodes.instrumentation.JSTags;
import com.oracle.truffle.js.runtime.JSConfig;
import com.oracle.truffle.js.runtime.JSContext;

Represents the body of a built-in function.
/**
 * Represents the body of a built-in function.
 */
@NodeChild(value = "arguments", type = JavaScriptNode[].class)
public abstract class JSBuiltinNode extends AbstractBodyNode {
    private final JSContext context;
    private final JSBuiltin builtin;
    boolean construct;
    boolean newTarget;

    @Override
    public boolean hasTag(Class<? extends Tag> tag) {
        if (tag == StandardTags.RootBodyTag.class) {
            return true;
        } else if (tag == JSTags.BuiltinRootTag.class) {
            return true;
        }
        return super.hasTag(tag);
    }

    @Override
    public Object getNodeObject() {
        return JSTags.createNodeObjectDescriptor("name", getBuiltin().getFullName());
    }

    protected JSBuiltinNode(JSContext context, JSBuiltin builtin) {
        this.context = context;
        this.builtin = builtin;
    }

    protected JSBuiltinNode(JSContext context, JSBuiltin builtin, boolean construct, boolean newTarget) {
        this.context = context;
        this.builtin = builtin;
        this.construct = construct;
        this.newTarget = newTarget;
    }

    public final JSContext getContext() {
        return context;
    }

    public JSBuiltin getBuiltin() {
        return builtin;
    }

    public abstract JavaScriptNode[] getArguments();

    public boolean isInlineable() {
        return this instanceof Inlineable;
    }

    public Inlined tryCreateInlined() {
        if (isInlineable()) {
            return ((Inlineable) this).createInlined();
        } else {
            return null;
        }
    }

    
If true, this function needs the call source location. The call node uses this hint to try
and pass the call node via a thread-local field (in the case of a direct call) that the
built-in can then use to avoid an expensive stack walk.
/**
     * If true, this function needs the call source location. The call node uses this hint to try
     * and pass the call node via a thread-local field (in the case of a direct call) that the
     * built-in can then use to avoid an expensive stack walk.
     */
    public boolean isCallerSensitive() {
        return false;
    }

    public static JSBuiltinNode createBuiltin(JSContext ctx, JSBuiltin builtin, boolean construct, boolean newTarget) {
        return new LazyBuiltinNode(ctx, builtin, construct, newTarget);
    }

    @Override
    protected JavaScriptNode copyUninitialized(Set<Class<? extends Tag>> materializedTags) {
        return createBuiltin(context, builtin, construct, newTarget);
    }

    static final class LazyBuiltinNode extends JSBuiltinNode {
        private static final boolean VERIFY_ARGUMENT_COUNT = false;

        LazyBuiltinNode(JSContext context, JSBuiltin builtin, boolean construct, boolean newTarget) {
            super(context, builtin, construct, newTarget);
            assert builtin != null;

            if (VERIFY_ARGUMENT_COUNT) {
                verifyArgumentCount();
            }
        }

        private void verifyArgumentCount() {
            assert !JSConfig.SubstrateVM;
            JSBuiltinNode builtinNode = createBuiltinNode();
            int argumentNodeCount = 0;
            Class<? extends JSBuiltinNode> nodeclass = builtinNode.getClass();
            for (Class<?> superclass = nodeclass; superclass != null; superclass = superclass.getSuperclass()) {
                argumentNodeCount += Arrays.stream(superclass.getDeclaredFields()).filter(f -> f.getAnnotation(Child.class) != null && f.getName().startsWith("arguments")).count();
            }
            int providedArgumentNodeCount = 0;
            for (Class<?> superclass = nodeclass; superclass != null; superclass = superclass.getSuperclass()) {
                providedArgumentNodeCount += Arrays.stream(superclass.getDeclaredFields()).filter(f -> f.getAnnotation(Child.class) != null && f.getName().startsWith("arguments")).filter(f -> {
                    try {
                        f.setAccessible(true);
                        return f.get(builtinNode) != null;
                    } catch (IllegalAccessException e) {
                        throw new AssertionError(e);
                    }
                }).count();
            }
            assert providedArgumentNodeCount == argumentNodeCount : nodeclass + " provided=" + providedArgumentNodeCount + " required=" + argumentNodeCount;
        }

        @Override
        public JavaScriptNode[] getArguments() {
            throw new UnsupportedOperationException();
        }

        @Override
        public Object execute(VirtualFrame frame) {
            CompilerDirectives.transferToInterpreterAndInvalidate();
            JSBuiltinNode resolved = materialize();
            return resolved.execute(frame);
        }

        private JSBuiltinNode materialize() {
            CompilerAsserts.neverPartOfCompilation();
            JSBuiltinNode builtinNode = createBuiltinNode();
            return replace(builtinNode, "lazy builtin");
        }

        private JSBuiltinNode createBuiltinNode() {
            return getBuiltin().createNode(getContext(), construct, newTarget);
        }

        @Override
        public boolean isInlineable() {
            return materialize().isInlineable();
        }

        @Override
        public Inlined tryCreateInlined() {
            return materialize().tryCreateInlined();
        }

        @Override
        public boolean isCallerSensitive() {
            return materialize().isCallerSensitive();
        }
    }

    
Interface for trivial built-in nodes that can be inlined without going through a call. The built-in function must not make any calls and must not throw an error (note that argument conversions and side-effecting accesses could make calls or throw errors); otherwise it could be observed that no actual call was made. The inlined node must check these preconditions to ensure it is safe to do an inline execution or throw RewriteToCallException. /**
     * Interface for trivial built-in nodes that can be inlined without going through a call.
     *
     * The built-in function must not make any calls and must not throw an error (note that argument
     * conversions and side-effecting accesses could make calls or throw errors); otherwise it could
     * be observed that no actual call was made. The inlined node must check these preconditions to
     * ensure it is safe to do an inline execution or throw {@link RewriteToCallException}.
     */
    public interface Inlineable extends NodeInterface {
        Inlined createInlined();
    }

    public interface Inlined extends NodeInterface {
        Object callInlined(Object[] arguments) throws RewriteToCallException;

        default RuntimeException rewriteToCall() {
            CompilerDirectives.transferToInterpreterAndInvalidate();
            throw RewriteToCallException.INSTANCE;
        }
    }

    @SuppressWarnings("serial")
    static final class RewriteToCallException extends RuntimeException {
        static final RuntimeException INSTANCE = new RewriteToCallException();

        private RewriteToCallException() {
            super(null, null, true, false);
        }
    }
}