/*
* Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved.
* 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.internal.org.objectweb.asm.Opcodes.ACC_FINAL;
import static jdk.internal.org.objectweb.asm.Opcodes.ACC_PRIVATE;
import static jdk.internal.org.objectweb.asm.Opcodes.ACC_PUBLIC;
import static jdk.internal.org.objectweb.asm.Opcodes.ACC_STATIC;
import static jdk.internal.org.objectweb.asm.Opcodes.ACC_SUPER;
import static jdk.internal.org.objectweb.asm.Opcodes.ACC_VARARGS;
import static jdk.internal.org.objectweb.asm.Opcodes.H_INVOKEINTERFACE;
import static jdk.internal.org.objectweb.asm.Opcodes.H_INVOKESPECIAL;
import static jdk.internal.org.objectweb.asm.Opcodes.H_INVOKESTATIC;
import static jdk.internal.org.objectweb.asm.Opcodes.H_INVOKEVIRTUAL;
import static jdk.internal.org.objectweb.asm.Opcodes.H_NEWINVOKESPECIAL;
import static jdk.internal.org.objectweb.asm.Opcodes.V1_7;
import static jdk.nashorn.internal.codegen.CompilerConstants.CLINIT;
import static jdk.nashorn.internal.codegen.CompilerConstants.CONSTANTS;
import static jdk.nashorn.internal.codegen.CompilerConstants.GET_ARRAY_PREFIX;
import static jdk.nashorn.internal.codegen.CompilerConstants.GET_ARRAY_SUFFIX;
import static jdk.nashorn.internal.codegen.CompilerConstants.GET_MAP;
import static jdk.nashorn.internal.codegen.CompilerConstants.GET_STRING;
import static jdk.nashorn.internal.codegen.CompilerConstants.INIT;
import static jdk.nashorn.internal.codegen.CompilerConstants.SET_MAP;
import static jdk.nashorn.internal.codegen.CompilerConstants.SOURCE;
import static jdk.nashorn.internal.codegen.CompilerConstants.STRICT_MODE;
import static jdk.nashorn.internal.codegen.CompilerConstants.className;
import static jdk.nashorn.internal.codegen.CompilerConstants.methodDescriptor;
import static jdk.nashorn.internal.codegen.CompilerConstants.typeDescriptor;
import static jdk.nashorn.internal.codegen.CompilerConstants.virtualCallNoLookup;
import java.io.ByteArrayOutputStream;
import java.io.PrintWriter;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.Collections;
import java.util.EnumSet;
import java.util.HashSet;
import java.util.Set;
import jdk.internal.org.objectweb.asm.ClassWriter;
import jdk.internal.org.objectweb.asm.MethodVisitor;
import jdk.internal.org.objectweb.asm.util.TraceClassVisitor;
import jdk.nashorn.internal.codegen.types.Type;
import jdk.nashorn.internal.ir.FunctionNode;
import jdk.nashorn.internal.ir.debug.NashornClassReader;
import jdk.nashorn.internal.ir.debug.NashornTextifier;
import jdk.nashorn.internal.runtime.Context;
import jdk.nashorn.internal.runtime.PropertyMap;
import jdk.nashorn.internal.runtime.RewriteException;
import jdk.nashorn.internal.runtime.ScriptObject;
import jdk.nashorn.internal.runtime.Source;
/**
* The interface responsible for speaking to ASM, emitting classes,
* fields and methods.
* <p>
* This file contains the ClassEmitter, which is the master object
* responsible for writing byte codes. It utilizes a MethodEmitter
* for method generation, which also the NodeVisitors own, to keep
* track of the current code generator and what it is doing.
* <p>
* There is, however, nothing stopping you from using this in a
* completely self contained environment, for example in ObjectGenerator
* where there are no visitors or external hooks.
* <p>
* MethodEmitter makes it simple to generate code for methods without
* having to do arduous type checking. It maintains a type stack
* and will pick the appropriate operation for all operations sent to it
* We also allow chained called to a MethodEmitter for brevity, e.g.
* it is legal to write _new(className).dup() or
* load(slot).load(slot2).xor().store(slot3);
* <p>
* If running with assertions enabled, any type conflict, such as different
* bytecode stack sizes or operating on the wrong type will be detected
* and an error thrown.
* <p>
* There is also a very nice debug interface that can emit formatted
* bytecodes that have been written. This is enabled by setting the
* environment "nashorn.codegen.debug" to true, or --log=codegen:{@literal <level>}
*
* @see Compiler
*/
public class ClassEmitter {
/** Default flags for class generation - public class */
private static final EnumSet<Flag> DEFAULT_METHOD_FLAGS = EnumSet.of(Flag.PUBLIC);
/** Sanity check flag - have we started on a class? */
private boolean classStarted;
/** Sanity check flag - have we ended this emission? */
private boolean classEnded;
/**
* Sanity checks - which methods have we currently
* started for generation in this class?
*/
private final HashSet<MethodEmitter> methodsStarted;
/** The ASM classwriter that we use for all bytecode operations */
protected final ClassWriter cw;
/** The script environment */
protected final Context context;
/** Compile unit class name. */
private String unitClassName;
/** Set of constants access methods required. */
private Set<Class<?>> constantMethodNeeded;
private int methodCount;
private int initCount;
private int clinitCount;
private int fieldCount;
private final Set<String> methodNames;
/**
* Constructor - only used internally in this class as it breaks
* abstraction towards ASM or other code generator below.
*
* @param env script environment
* @param cw ASM classwriter
*/
private ClassEmitter(final Context context, final ClassWriter cw) {
this.context = context;
this.cw = cw;
this.methodsStarted = new HashSet<>();
this.methodNames = new HashSet<>();
}
/**
* Return the method names encountered.
*
* @return method names
*/
public Set<String> getMethodNames() {
return Collections.unmodifiableSet(methodNames);
}
/**
* Constructor.
*
* @param env script environment
* @param className name of class to weave
* @param superClassName super class name for class
* @param interfaceNames names of interfaces implemented by this class, or
* {@code null} if none
*/
ClassEmitter(final Context context, final String className, final String superClassName, final String... interfaceNames) {
this(context, new ClassWriter(ClassWriter.COMPUTE_FRAMES | ClassWriter.COMPUTE_MAXS));
cw.visit(V1_7, ACC_PUBLIC | ACC_SUPER, className, null, superClassName, interfaceNames);
}
/**
* Constructor from the compiler.
*
* @param env Script environment
* @param sourceName Source name
* @param unitClassName Compile unit class name.
* @param strictMode Should we generate this method in strict mode
*/
ClassEmitter(final Context context, final String sourceName, final String unitClassName, final boolean strictMode) {
this(context,
new ClassWriter(ClassWriter.COMPUTE_FRAMES | ClassWriter.COMPUTE_MAXS) {
private static final String OBJECT_CLASS = "java/lang/Object";
@Override
protected String getCommonSuperClass(final String type1, final String type2) {
try {
return super.getCommonSuperClass(type1, type2);
} catch (final RuntimeException e) {
if (isScriptObject(Compiler.SCRIPTS_PACKAGE, type1) && isScriptObject(Compiler.SCRIPTS_PACKAGE, type2)) {
return className(ScriptObject.class);
}
return OBJECT_CLASS;
}
}
});
this.unitClassName = unitClassName;
this.constantMethodNeeded = new HashSet<>();
cw.visit(V1_7, ACC_PUBLIC | ACC_SUPER, unitClassName, null, pathName(jdk.nashorn.internal.scripts.JS.class.getName()), null);
cw.visitSource(sourceName, null);
defineCommonStatics(strictMode);
}
Context getContext() {
return context;
}
/**
* @return the name of the compile unit class name.
*/
String getUnitClassName() {
return unitClassName;
}
/**
* Get the method count, including init and clinit methods.
*
* @return method count
*/
public int getMethodCount() {
return methodCount;
}
/**
* Get the clinit count.
*
* @return clinit count
*/
public int getClinitCount() {
return clinitCount;
}
/**
* Get the init count.
*
* @return init count
*/
public int getInitCount() {
return initCount;
}
/**
* Get the field count.
*
* @return field count
*/
public int getFieldCount() {
return fieldCount;
}
/**
* Convert a binary name to a package/class name.
*
* @param name Binary name.
*
* @return Package/class name.
*/
private static String pathName(final String name) {
return name.replace('.', '/');
}
/**
* Define the static fields common in all scripts.
*
* @param strictMode Should we generate this method in strict mode
*/
private void defineCommonStatics(final boolean strictMode) {
// source - used to store the source data (text) for this script. Shared across
// compile units. Set externally by the compiler.
field(EnumSet.of(Flag.PRIVATE, Flag.STATIC), SOURCE.symbolName(), Source.class);
// constants - used to the constants array for this script. Shared across
// compile units. Set externally by the compiler.
field(EnumSet.of(Flag.PRIVATE, Flag.STATIC), CONSTANTS.symbolName(), Object[].class);
// strictMode - was this script compiled in strict mode. Set externally by the compiler.
field(EnumSet.of(Flag.PUBLIC, Flag.STATIC, Flag.FINAL), STRICT_MODE.symbolName(), boolean.class, strictMode);
}
/**
* Define static utilities common needed in scripts. These are per compile
* unit and therefore have to be defined here and not in code gen.
*/
private void defineCommonUtilities() {
assert unitClassName != null;
if (constantMethodNeeded.contains(String.class)) {
// $getString - get the ith entry from the constants table and cast to String.
final MethodEmitter getStringMethod = method(EnumSet.of(Flag.PRIVATE, Flag.STATIC), GET_STRING.symbolName(), String.class, int.class);
getStringMethod.begin();
getStringMethod.getStatic(unitClassName, CONSTANTS.symbolName(), CONSTANTS.descriptor())
.load(Type.INT, 0)
.arrayload()
.checkcast(String.class)
._return();
getStringMethod.end();
}
if (constantMethodNeeded.contains(PropertyMap.class)) {
// $getMap - get the ith entry from the constants table and cast to PropertyMap.
final MethodEmitter getMapMethod = method(EnumSet.of(Flag.PUBLIC, Flag.STATIC), GET_MAP.symbolName(), PropertyMap.class, int.class);
getMapMethod.begin();
getMapMethod.loadConstants()
.load(Type.INT, 0)
.arrayload()
.checkcast(PropertyMap.class)
._return();
getMapMethod.end();
// $setMap - overwrite an existing map.
final MethodEmitter setMapMethod = method(EnumSet.of(Flag.PUBLIC, Flag.STATIC), SET_MAP.symbolName(), void.class, int.class, PropertyMap.class);
setMapMethod.begin();
setMapMethod.loadConstants()
.load(Type.INT, 0)
.load(Type.OBJECT, 1)
.arraystore();
setMapMethod.returnVoid();
setMapMethod.end();
}
// $getXXXX$array - get the ith entry from the constants table and cast to XXXX[].
for (final Class<?> clazz : constantMethodNeeded) {
if (clazz.isArray()) {
defineGetArrayMethod(clazz);
}
}
}
/**
* Constructs a primitive specific method for getting the ith entry from the
* constants table as an array.
*
* @param clazz Array class.
*/
private void defineGetArrayMethod(final Class<?> clazz) {
assert unitClassName != null;
final String methodName = getArrayMethodName(clazz);
final MethodEmitter getArrayMethod = method(EnumSet.of(Flag.PRIVATE, Flag.STATIC), methodName, clazz, int.class);
getArrayMethod.begin();
getArrayMethod.getStatic(unitClassName, CONSTANTS.symbolName(), CONSTANTS.descriptor())
.load(Type.INT, 0)
.arrayload()
.checkcast(clazz)
.invoke(virtualCallNoLookup(clazz, "clone", Object.class))
.checkcast(clazz)
._return();
getArrayMethod.end();
}
/**
* Generate the name of a get array from constant pool method.
*
* @param clazz Name of array class.
*
* @return Method name.
*/
static String getArrayMethodName(final Class<?> clazz) {
assert clazz.isArray();
return GET_ARRAY_PREFIX.symbolName() + clazz.getComponentType().getSimpleName() + GET_ARRAY_SUFFIX.symbolName();
}
/**
* Ensure a get constant method is issued for the class.
*
* @param clazz Class of constant.
*/
void needGetConstantMethod(final Class<?> clazz) {
constantMethodNeeded.add(clazz);
}
/**
* Inspect class name and decide whether we are generating a ScriptObject class.
*
* @param scriptPrefix the script class prefix for the current script
* @param type the type to check
*
* @return {@code true} if type is ScriptObject
*/
private static boolean isScriptObject(final String scriptPrefix, final String type) {
if (type.startsWith(scriptPrefix)) {
return true;
} else if (type.equals(CompilerConstants.className(ScriptObject.class))) {
return true;
} else if (type.startsWith(Compiler.OBJECTS_PACKAGE)) {
return true;
}
return false;
}
/**
* Call at beginning of class emission.
*/
public void begin() {
classStarted = true;
}
/**
* Call at end of class emission.
*/
public void end() {
assert classStarted : "class not started for " + unitClassName;
if (unitClassName != null) {
final MethodEmitter initMethod = init(EnumSet.of(Flag.PRIVATE));
initMethod.begin();
initMethod.load(Type.OBJECT, 0);
initMethod.newInstance(jdk.nashorn.internal.scripts.JS.class);
initMethod.returnVoid();
initMethod.end();
defineCommonUtilities();
}
cw.visitEnd();
classStarted = false;
classEnded = true;
assert methodsStarted.isEmpty() : "methodsStarted not empty " + methodsStarted;
}
/**
* Disassemble an array of byte code.
*
* @param bytecode byte array representing bytecode
*
* @return disassembly as human readable string
*/
static String disassemble(final byte[] bytecode) {
final ByteArrayOutputStream baos = new ByteArrayOutputStream();
try (final PrintWriter pw = new PrintWriter(baos)) {
final NashornClassReader cr = new NashornClassReader(bytecode);
final Context ctx = AccessController.doPrivileged(new PrivilegedAction<Context>() {
@Override
public Context run() {
return Context.getContext();
}
});
final TraceClassVisitor tcv = new TraceClassVisitor(null, new NashornTextifier(ctx.getEnv(), cr), pw);
cr.accept(tcv, 0);
}
final String str = new String(baos.toByteArray());
return str;
}
/**
* Call back from MethodEmitter for method start.
*
* @see MethodEmitter
*
* @param method method emitter.
*/
void beginMethod(final MethodEmitter method) {
assert !methodsStarted.contains(method);
methodsStarted.add(method);
}
/**
* Call back from MethodEmitter for method end.
*
* @see MethodEmitter
*
* @param method
*/
void endMethod(final MethodEmitter method) {
assert methodsStarted.contains(method);
methodsStarted.remove(method);
}
/**
* Add a new method to the class - defaults to public method.
*
* @param methodName name of method
* @param rtype return type of the method
* @param ptypes parameter types the method
*
* @return method emitter to use for weaving this method
*/
MethodEmitter method(final String methodName, final Class<?> rtype, final Class<?>... ptypes) {
return method(DEFAULT_METHOD_FLAGS, methodName, rtype, ptypes); //TODO why public default ?
}
/**
* Add a new method to the class - defaults to public method.
*
* @param methodFlags access flags for the method
* @param methodName name of method
* @param rtype return type of the method
* @param ptypes parameter types the method
*
* @return method emitter to use for weaving this method
*/
MethodEmitter method(final EnumSet<Flag> methodFlags, final String methodName, final Class<?> rtype, final Class<?>... ptypes) {
methodCount++;
methodNames.add(methodName);
return new MethodEmitter(this, methodVisitor(methodFlags, methodName, rtype, ptypes));
}
/**
* Add a new method to the class - defaults to public method.
*
* @param methodName name of method
* @param descriptor descriptor of method
*
* @return method emitter to use for weaving this method
*/
MethodEmitter method(final String methodName, final String descriptor) {
return method(DEFAULT_METHOD_FLAGS, methodName, descriptor);
}
/**
* Add a new method to the class - defaults to public method.
*
* @param methodFlags access flags for the method
* @param methodName name of method
* @param descriptor descriptor of method
*
* @return method emitter to use for weaving this method
*/
MethodEmitter method(final EnumSet<Flag> methodFlags, final String methodName, final String descriptor) {
methodCount++;
methodNames.add(methodName);
return new MethodEmitter(this, cw.visitMethod(Flag.getValue(methodFlags), methodName, descriptor, null, null));
}
/**
* Add a new method to the class, representing a function node.
*
* @param functionNode the function node to generate a method for
*
* @return method emitter to use for weaving this method
*/
MethodEmitter method(final FunctionNode functionNode) {
methodCount++;
methodNames.add(functionNode.getName());
final FunctionSignature signature = new FunctionSignature(functionNode);
final MethodVisitor mv = cw.visitMethod(
ACC_PUBLIC | ACC_STATIC | (functionNode.isVarArg() ? ACC_VARARGS : 0),
functionNode.getName(),
signature.toString(),
null,
null);
return new MethodEmitter(this, mv, functionNode);
}
/**
* Add a new method to the class, representing a rest-of version of the
* function node.
*
* @param functionNode the function node to generate a method for
*
* @return method emitter to use for weaving this method
*/
MethodEmitter restOfMethod(final FunctionNode functionNode) {
methodCount++;
methodNames.add(functionNode.getName());
final MethodVisitor mv = cw.visitMethod(
ACC_PUBLIC | ACC_STATIC,
functionNode.getName(),
Type.getMethodDescriptor(functionNode.getReturnType().getTypeClass(), RewriteException.class),
null,
null);
return new MethodEmitter(this, mv, functionNode);
}
/**
* Start generating the <clinit> method in the class.
*
* @return method emitter to use for weaving <clinit>
*/
MethodEmitter clinit() {
clinitCount++;
return method(EnumSet.of(Flag.STATIC), CLINIT.symbolName(), void.class);
}
/**
* Start generating an <init>()V method in the class.
*
* @return method emitter to use for weaving <init>()V
*/
MethodEmitter init() {
initCount++;
return method(INIT.symbolName(), void.class);
}
/**
* Start generating an <init>()V method in the class.
*
* @param ptypes parameter types for constructor
* @return method emitter to use for weaving <init>()V
*/
MethodEmitter init(final Class<?>... ptypes) {
initCount++;
return method(INIT.symbolName(), void.class, ptypes);
}
/**
* Start generating an <init>(...)V method in the class.
*
* @param flags access flags for the constructor
* @param ptypes parameter types for the constructor
*
* @return method emitter to use for weaving <init>(...)V
*/
MethodEmitter init(final EnumSet<Flag> flags, final Class<?>... ptypes) {
initCount++;
return method(flags, INIT.symbolName(), void.class, ptypes);
}
/**
* Add a field to the class, initialized to a value.
*
* @param fieldFlags flags, e.g. should it be static or public etc
* @param fieldName name of field
* @param fieldType the type of the field
* @param value the value
*
* @see ClassEmitter.Flag
*/
final void field(final EnumSet<Flag> fieldFlags, final String fieldName, final Class<?> fieldType, final Object value) {
fieldCount++;
cw.visitField(Flag.getValue(fieldFlags), fieldName, typeDescriptor(fieldType), null, value).visitEnd();
}
/**
* Add a field to the class.
*
* @param fieldFlags access flags for the field
* @param fieldName name of field
* @param fieldType type of the field
*
* @see ClassEmitter.Flag
*/
final void field(final EnumSet<Flag> fieldFlags, final String fieldName, final Class<?> fieldType) {
field(fieldFlags, fieldName, fieldType, null);
}
/**
* Add a field to the class - defaults to public.
*
* @param fieldName name of field
* @param fieldType type of field
*/
final void field(final String fieldName, final Class<?> fieldType) {
field(EnumSet.of(Flag.PUBLIC), fieldName, fieldType, null);
}
/**
* Return a bytecode array from this ClassEmitter. The ClassEmitter must
* have been ended (having its end function called) for this to work.
*
* @return byte code array for generated class, {@code null} if class
* generation hasn't been ended with {@link ClassEmitter#end()}.
*/
byte[] toByteArray() {
assert classEnded;
if (!classEnded) {
return null;
}
return cw.toByteArray();
}
/**
* Abstraction for flags used in class emission. We provide abstraction
* separating these from the underlying bytecode emitter. Flags are provided
* for method handles, protection levels, static/virtual fields/methods.
*/
static enum Flag {
/** method handle with static access */
HANDLE_STATIC(H_INVOKESTATIC),
/** method handle with new invoke special access */
HANDLE_NEWSPECIAL(H_NEWINVOKESPECIAL),
/** method handle with invoke special access */
HANDLE_SPECIAL(H_INVOKESPECIAL),
/** method handle with invoke virtual access */
HANDLE_VIRTUAL(H_INVOKEVIRTUAL),
/** method handle with invoke interface access */
HANDLE_INTERFACE(H_INVOKEINTERFACE),
/** final access */
FINAL(ACC_FINAL),
/** static access */
STATIC(ACC_STATIC),
/** public access */
PUBLIC(ACC_PUBLIC),
/** private access */
PRIVATE(ACC_PRIVATE);
private final int value;
private Flag(final int value) {
this.value = value;
}
/**
* Get the value of this flag
* @return the int value
*/
int getValue() {
return value;
}
/**
* Return the corresponding ASM flag value for an enum set of flags.
*
* @param flags enum set of flags
*
* @return an integer value representing the flags intrinsic values
* or:ed together
*/
static int getValue(final EnumSet<Flag> flags) {
int v = 0;
for (final Flag flag : flags) {
v |= flag.getValue();
}
return v;
}
}
private MethodVisitor methodVisitor(final EnumSet<Flag> flags, final String methodName, final Class<?> rtype, final Class<?>... ptypes) {
return cw.visitMethod(Flag.getValue(flags), methodName, methodDescriptor(rtype, ptypes), null, null);
}
}