internal/codegen/FieldObjectCreator.java

/*
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * 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).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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package jdk.nashorn.internal.codegen;

import static jdk.nashorn.internal.codegen.CompilerConstants.ARGUMENTS;
import static jdk.nashorn.internal.codegen.CompilerConstants.constructorNoLookup;
import static jdk.nashorn.internal.codegen.CompilerConstants.typeDescriptor;
import static jdk.nashorn.internal.codegen.ObjectClassGenerator.PRIMITIVE_FIELD_TYPE;
import static jdk.nashorn.internal.codegen.ObjectClassGenerator.getFieldName;
import static jdk.nashorn.internal.codegen.ObjectClassGenerator.getPaddedFieldCount;
import static jdk.nashorn.internal.runtime.arrays.ArrayIndex.getArrayIndex;
import static jdk.nashorn.internal.runtime.arrays.ArrayIndex.isValidArrayIndex;

import java.util.Iterator;
import java.util.List;
import jdk.nashorn.internal.codegen.types.Type;
import jdk.nashorn.internal.ir.Symbol;
import jdk.nashorn.internal.runtime.Context;
import jdk.nashorn.internal.runtime.JSType;
import jdk.nashorn.internal.runtime.PropertyMap;
import jdk.nashorn.internal.runtime.ScriptObject;
import jdk.nashorn.internal.runtime.arrays.ArrayIndex;

/**
 * Analyze an object's characteristics for appropriate code generation. This
 * is used for functions and for objects. A field object take a set of values which
 * to assign to the various fields in the object. This is done by the generated code
 *
 * @param <T> the value type for the fields being written on object creation, e.g. Node
 * @see jdk.nashorn.internal.ir.Node
 */
public abstract class FieldObjectCreator<T> extends ObjectCreator<T> {

    private String                        fieldObjectClassName;
    private Class<? extends ScriptObject> fieldObjectClass;
    private int                           fieldCount;
    private int                           paddedFieldCount;
    private int                           paramCount;

    /** call site flags to be used for invocations */
    private final int callSiteFlags;
    /** are we creating this field object from 'eval' code? */
    private final boolean evalCode;

    /**
     * Constructor
     *
     * @param codegen  code generator
     * @param tuples   tuples for fields in object
     */
    FieldObjectCreator(final CodeGenerator codegen, final List<MapTuple<T>> tuples) {
        this(codegen, tuples, false, false);
    }

    /**
     * Constructor
     *
     * @param codegen      code generator
     * @param tuples       tuples for fields in object
     * @param isScope      is this a scope object
     * @param hasArguments does the created object have an "arguments" property
     */
    FieldObjectCreator(final CodeGenerator codegen, final List<MapTuple<T>> tuples, final boolean isScope, final boolean hasArguments) {
        super(codegen, tuples, isScope, hasArguments);
        this.callSiteFlags = codegen.getCallSiteFlags();
        this.evalCode = codegen.isEvalCode();
        countFields();
        findClass();
    }

    /**
     * Construct an object.
     *
     * @param method the method emitter
     */
    @Override
    protected void makeObject(final MethodEmitter method) {
        makeMap();
        final String className = getClassName();
        try {
            // NOTE: we must load the actual structure class here, because the API operates with Nashorn Type objects,
            // and Type objects need a loaded class, for better or worse. We also have to be specific and use the type
            // of the actual structure class, we can't generalize it to e.g. Type.typeFor(ScriptObject.class) as the
            // exact type information is needed for generating continuations in rest-of methods. If we didn't do this,
            // object initializers like { x: arr[i] } would fail during deoptimizing compilation on arr[i], as the
            // values restored from the RewriteException would be cast to "ScriptObject" instead of to e.g. "JO4", and
            // subsequently the "PUTFIELD J04.L0" instruction in the continuation code would fail bytecode verification.
            method._new(Context.forStructureClass(className.replace('/', '.'))).dup();
        } catch (final ClassNotFoundException e) {
            throw new AssertionError(e);
        }
        loadMap(method); //load the map

        if (isScope()) {
            loadScope(method);

            if (hasArguments()) {
                method.loadCompilerConstant(ARGUMENTS);
                method.invoke(constructorNoLookup(className, PropertyMap.class, ScriptObject.class, ARGUMENTS.type()));
            } else {
                method.invoke(constructorNoLookup(className, PropertyMap.class, ScriptObject.class));
            }
        } else {
            method.invoke(constructorNoLookup(className, PropertyMap.class));
        }

        helpOptimisticRecognizeDuplicateIdentity(method);

        // Set values.
        final Iterator<MapTuple<T>> iter = tuples.iterator();

        while (iter.hasNext()) {
            final MapTuple<T> tuple = iter.next();
            //we only load when we have both symbols and values (which can be == the symbol)
            //if we didn't load, we need an array property
            if (tuple.symbol != null && tuple.value != null) {
                final int index = getArrayIndex(tuple.key);
                method.dup();
                if (!isValidArrayIndex(index)) {
                    putField(method, tuple.key, tuple.symbol.getFieldIndex(), tuple);
                } else {
                    putSlot(method, ArrayIndex.toLongIndex(index), tuple);
                }

                //this is a nop of tuple.key isn't e.g. "apply" or another special name
                method.invalidateSpecialName(tuple.key);
            }
        }
    }

    @Override
    protected PropertyMap makeMap() {
        assert propertyMap == null : "property map already initialized";
        propertyMap = newMapCreator(fieldObjectClass).makeFieldMap(hasArguments(), codegen.useDualFields(), fieldCount, paddedFieldCount, evalCode);
        return propertyMap;
    }

    /**
     * Store a value in a field of the generated class object.
     *
     * @param method      Script method.
     * @param key         Property key.
     * @param fieldIndex  Field number.
     * @param tuple       Tuple to store.
     */
    private void putField(final MethodEmitter method, final String key, final int fieldIndex, final MapTuple<T> tuple) {
        final Type    fieldType   = codegen.useDualFields() && tuple.isPrimitive() ? PRIMITIVE_FIELD_TYPE : Type.OBJECT;
        final String  fieldClass  = getClassName();
        final String  fieldName   = getFieldName(fieldIndex, fieldType);
        final String  fieldDesc   = typeDescriptor(fieldType.getTypeClass());

        assert fieldName.equals(getFieldName(fieldIndex, PRIMITIVE_FIELD_TYPE)) || fieldType.isObject() :    key + " object keys must store to L*-fields";
        assert fieldName.equals(getFieldName(fieldIndex, Type.OBJECT))          || fieldType.isPrimitive() : key + " primitive keys must store to J*-fields";

        loadTuple(method, tuple);

        method.putField(fieldClass, fieldName, fieldDesc);
    }

    /**
     * Store a value in an indexed slot of a generated class object.
     *
     * @param method Script method.
     * @param index  Slot index.
     * @param tuple  Tuple to store.
     */
    private void putSlot(final MethodEmitter method, final long index, final MapTuple<T> tuple) {
        if (JSType.isRepresentableAsInt(index)) {
            method.load((int)index);
        } else {
            method.load(index);
        }
        loadTuple(method, tuple, false); //we don't pack array like objects
        method.dynamicSetIndex(callSiteFlags);
    }

    /**
     * Locate (or indirectly create) the object container class.
     */
    private void findClass() {
        fieldObjectClassName = isScope() ?
                ObjectClassGenerator.getClassName(fieldCount, paramCount, codegen.useDualFields()) :
                ObjectClassGenerator.getClassName(paddedFieldCount, codegen.useDualFields());

        try {
            this.fieldObjectClass = Context.forStructureClass(Compiler.binaryName(fieldObjectClassName));
        } catch (final ClassNotFoundException e) {
            throw new AssertionError("Nashorn has encountered an internal error.  Structure can not be created.");
        }
    }

    /**
     * Get the class name for the object class,
     * e.g. {@code com.nashorn.oracle.scripts.JO2P0}
     *
     * @return script class name
     */
    String getClassName() {
        return fieldObjectClassName;
    }

    /**
     * Tally the number of fields and parameters.
     */
    private void countFields() {
        for (final MapTuple<T> tuple : tuples) {
            final Symbol symbol = tuple.symbol;
            if (symbol != null) {
                if (hasArguments() && symbol.isParam()) {
                    symbol.setFieldIndex(paramCount++);
                } else if (!isValidArrayIndex(getArrayIndex(tuple.key))) {
                    symbol.setFieldIndex(fieldCount++);
                }
            }
        }

        paddedFieldCount = getPaddedFieldCount(fieldCount);
    }

}