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⏎ java/lang/invoke/ClassSpecializer.java
/*
* Copyright (c) 2017, 2021, Oracle and/or its affiliates. All rights reserved.
* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*
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package java.lang.invoke;
import jdk.internal.access.SharedSecrets;
import jdk.internal.loader.BootLoader;
import jdk.internal.org.objectweb.asm.ClassWriter;
import jdk.internal.org.objectweb.asm.FieldVisitor;
import jdk.internal.org.objectweb.asm.MethodVisitor;
import jdk.internal.vm.annotation.Stable;
import sun.invoke.util.BytecodeName;
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.security.ProtectionDomain;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Objects;
import java.util.concurrent.ConcurrentHashMap;
import java.util.function.Function;
import static java.lang.invoke.LambdaForm.*;
import static java.lang.invoke.MethodHandleNatives.Constants.REF_getStatic;
import static java.lang.invoke.MethodHandleNatives.Constants.REF_putStatic;
import static java.lang.invoke.MethodHandleStatics.*;
import static java.lang.invoke.MethodHandles.Lookup.IMPL_LOOKUP;
import static jdk.internal.org.objectweb.asm.Opcodes.*;
/**
* Class specialization code.
* @param <T> top class under which species classes are created.
* @param <K> key which identifies individual specializations.
* @param <S> species data type.
*/
/*non-public*/
abstract class ClassSpecializer<T,K,S extends ClassSpecializer<T,K,S>.SpeciesData> {
private final Class<T> topClass;
private final Class<K> keyType;
private final Class<S> metaType;
private final MemberName sdAccessor;
private final String sdFieldName;
private final List<MemberName> transformMethods;
private final MethodType baseConstructorType;
private final S topSpecies;
private final ConcurrentHashMap<K, Object> cache = new ConcurrentHashMap<>();
private final Factory factory;
private @Stable boolean topClassIsSuper;
/** Return the top type mirror, for type {@code T} */
public final Class<T> topClass() { return topClass; }
/** Return the key type mirror, for type {@code K} */
public final Class<K> keyType() { return keyType; }
/** Return the species metadata type mirror, for type {@code S} */
public final Class<S> metaType() { return metaType; }
/** Report the leading arguments (if any) required by every species factory.
* Every species factory adds its own field types as additional arguments,
* but these arguments always come first, in every factory method.
*/
protected MethodType baseConstructorType() { return baseConstructorType; }
/** Return the trivial species for the null sequence of arguments. */
protected final S topSpecies() { return topSpecies; }
/** Return the list of transform methods originally given at creation of this specializer. */
protected final List<MemberName> transformMethods() { return transformMethods; }
/** Return the factory object used to build and load concrete species code. */
protected final Factory factory() { return factory; }
/**
* Constructor for this class specializer.
* @param topClass type mirror for T
* @param keyType type mirror for K
* @param metaType type mirror for S
* @param baseConstructorType principal constructor type
* @param sdAccessor the method used to get the speciesData
* @param sdFieldName the name of the species data field, inject the speciesData object
* @param transformMethods optional list of transformMethods
*/
protected ClassSpecializer(Class<T> topClass,
Class<K> keyType,
Class<S> metaType,
MethodType baseConstructorType,
MemberName sdAccessor,
String sdFieldName,
List<MemberName> transformMethods) {
this.topClass = topClass;
this.keyType = keyType;
this.metaType = metaType;
this.sdAccessor = sdAccessor;
this.transformMethods = List.copyOf(transformMethods);
this.sdFieldName = sdFieldName;
this.baseConstructorType = baseConstructorType.changeReturnType(void.class);
this.factory = makeFactory();
K tsk = topSpeciesKey();
S topSpecies = null;
if (tsk != null && topSpecies == null) {
// if there is a key, build the top species if needed:
topSpecies = findSpecies(tsk);
}
this.topSpecies = topSpecies;
}
// Utilities for subclass constructors:
protected static <T> Constructor<T> reflectConstructor(Class<T> defc, Class<?>... ptypes) {
try {
return defc.getDeclaredConstructor(ptypes);
} catch (NoSuchMethodException ex) {
throw newIAE(defc.getName()+"("+MethodType.methodType(void.class, ptypes)+")", ex);
}
}
protected static Field reflectField(Class<?> defc, String name) {
try {
return defc.getDeclaredField(name);
} catch (NoSuchFieldException ex) {
throw newIAE(defc.getName()+"."+name, ex);
}
}
private static RuntimeException newIAE(String message, Throwable cause) {
return new IllegalArgumentException(message, cause);
}
private static final Function<Object, Object> CREATE_RESERVATION = new Function<>() {
@Override
public Object apply(Object key) {
return new Object();
}
};
public final S findSpecies(K key) {
// Note: Species instantiation may throw VirtualMachineError because of
// code cache overflow. If this happens the species bytecode may be
// loaded but not linked to its species metadata (with MH's etc).
// That will cause a throw out of Factory.loadSpecies.
//
// In a later attempt to get the same species, the already-loaded
// class will be present in the system dictionary, causing an
// error when the species generator tries to reload it.
// We try to detect this case and link the pre-existing code.
//
// Although it would be better to start fresh by loading a new
// copy, we have to salvage the previously loaded but broken code.
// (As an alternative, we might spin a new class with a new name,
// or use the anonymous class mechanism.)
//
// In the end, as long as everybody goes through this findSpecies method,
// it will ensure only one SpeciesData will be set successfully on a
// concrete class if ever.
// The concrete class is published via SpeciesData instance
// returned here only after the class and species data are linked together.
Object speciesDataOrReservation = cache.computeIfAbsent(key, CREATE_RESERVATION);
// Separating the creation of a placeholder SpeciesData instance above
// from the loading and linking a real one below ensures we can never
// accidentally call computeIfAbsent recursively.
S speciesData;
if (speciesDataOrReservation.getClass() == Object.class) {
synchronized (speciesDataOrReservation) {
Object existingSpeciesData = cache.get(key);
if (existingSpeciesData == speciesDataOrReservation) { // won the race
// create a new SpeciesData...
speciesData = newSpeciesData(key);
// load and link it...
speciesData = factory.loadSpecies(speciesData);
if (!cache.replace(key, existingSpeciesData, speciesData)) {
throw newInternalError("Concurrent loadSpecies");
}
} else { // lost the race; the retrieved existingSpeciesData is the final
speciesData = metaType.cast(existingSpeciesData);
}
}
} else {
speciesData = metaType.cast(speciesDataOrReservation);
}
assert(speciesData != null && speciesData.isResolved());
return speciesData;
}
/**
* Meta-data wrapper for concrete subtypes of the top class.
* Each concrete subtype corresponds to a given sequence of basic field types (LIJFD).
* The fields are immutable; their values are fully specified at object construction.
* Each species supplies an array of getter functions which may be used in lambda forms.
* A concrete value is always constructed from the full tuple of its field values,
* accompanied by the required constructor parameters.
* There *may* also be transforms which cloning a species instance and
* either replace a constructor parameter or add one or more new field values.
* The shortest possible species has zero fields.
* Subtypes are not interrelated among themselves by subtyping, even though
* it would appear that a shorter species could serve as a supertype of a
* longer one which extends it.
*/
public abstract class SpeciesData {
// Bootstrapping requires circular relations Class -> SpeciesData -> Class
// Therefore, we need non-final links in the chain. Use @Stable fields.
private final K key;
private final List<Class<?>> fieldTypes;
@Stable private Class<? extends T> speciesCode;
@Stable private List<MethodHandle> factories;
@Stable private List<MethodHandle> getters;
@Stable private List<LambdaForm.NamedFunction> nominalGetters;
@Stable private final MethodHandle[] transformHelpers = new MethodHandle[transformMethods.size()];
protected SpeciesData(K key) {
this.key = keyType.cast(Objects.requireNonNull(key));
List<Class<?>> types = deriveFieldTypes(key);
this.fieldTypes = List.copyOf(types);
}
public final K key() {
return key;
}
protected final List<Class<?>> fieldTypes() {
return fieldTypes;
}
protected final int fieldCount() {
return fieldTypes.size();
}
protected ClassSpecializer<T,K,S> outer() {
return ClassSpecializer.this;
}
protected final boolean isResolved() {
return speciesCode != null && factories != null && !factories.isEmpty();
}
@Override public String toString() {
return metaType.getSimpleName() + "[" + key.toString() + " => " + (isResolved() ? speciesCode.getSimpleName() : "UNRESOLVED") + "]";
}
@Override
public int hashCode() {
return key.hashCode();
}
@Override
public boolean equals(Object obj) {
if (!(obj instanceof ClassSpecializer.SpeciesData)) {
return false;
}
@SuppressWarnings("rawtypes")
ClassSpecializer.SpeciesData that = (ClassSpecializer.SpeciesData) obj;
return this.outer() == that.outer() && this.key.equals(that.key);
}
/** Throws NPE if this species is not yet resolved. */
protected final Class<? extends T> speciesCode() {
return Objects.requireNonNull(speciesCode);
}
/**
* Return a {@link MethodHandle} which can get the indexed field of this species.
* The return type is the type of the species field it accesses.
* The argument type is the {@code fieldHolder} class of this species.
*/
protected MethodHandle getter(int i) {
return getters.get(i);
}
/**
* Return a {@link LambdaForm.Name} containing a {@link LambdaForm.NamedFunction} that
* represents a MH bound to a generic invoker, which in turn forwards to the corresponding
* getter.
*/
protected LambdaForm.NamedFunction getterFunction(int i) {
LambdaForm.NamedFunction nf = nominalGetters.get(i);
assert(nf.memberDeclaringClassOrNull() == speciesCode());
assert(nf.returnType() == BasicType.basicType(fieldTypes.get(i)));
return nf;
}
protected List<LambdaForm.NamedFunction> getterFunctions() {
return nominalGetters;
}
protected List<MethodHandle> getters() {
return getters;
}
protected MethodHandle factory() {
return factories.get(0);
}
protected MethodHandle transformHelper(int whichtm) {
MethodHandle mh = transformHelpers[whichtm];
if (mh != null) return mh;
mh = deriveTransformHelper(transformMethods().get(whichtm), whichtm);
// Do a little type checking before we start using the MH.
// (It will be called with invokeBasic, so this is our only chance.)
final MethodType mt = transformHelperType(whichtm);
mh = mh.asType(mt);
return transformHelpers[whichtm] = mh;
}
private final MethodType transformHelperType(int whichtm) {
MemberName tm = transformMethods().get(whichtm);
ArrayList<Class<?>> args = new ArrayList<>();
ArrayList<Class<?>> fields = new ArrayList<>();
Collections.addAll(args, tm.getParameterTypes());
fields.addAll(fieldTypes());
List<Class<?>> helperArgs = deriveTransformHelperArguments(tm, whichtm, args, fields);
return MethodType.methodType(tm.getReturnType(), helperArgs);
}
// Hooks for subclasses:
/**
* Given a key, derive the list of field types, which all instances of this
* species must store.
*/
protected abstract List<Class<?>> deriveFieldTypes(K key);
/**
* Given the index of a method in the transforms list, supply a factory
* method that takes the arguments of the transform, plus the local fields,
* and produce a value of the required type.
* You can override this to return null or throw if there are no transforms.
* This method exists so that the transforms can be "grown" lazily.
* This is necessary if the transform *adds* a field to an instance,
* which sometimes requires the creation, on the fly, of an extended species.
* This method is only called once for any particular parameter.
* The species caches the result in a private array.
*
* @param transform the transform being implemented
* @param whichtm the index of that transform in the original list of transforms
* @return the method handle which creates a new result from a mix of transform
* arguments and field values
*/
protected abstract MethodHandle deriveTransformHelper(MemberName transform, int whichtm);
/**
* During code generation, this method is called once per transform to determine
* what is the mix of arguments to hand to the transform-helper. The bytecode
* which marshals these arguments is open-coded in the species-specific transform.
* The two lists are of opaque objects, which you shouldn't do anything with besides
* reordering them into the output list. (They are both mutable, to make editing
* easier.) The imputed types of the args correspond to the transform's parameter
* list, while the imputed types of the fields correspond to the species field types.
* After code generation, this method may be called occasionally by error-checking code.
*
* @param transform the transform being implemented
* @param whichtm the index of that transform in the original list of transforms
* @param args a list of opaque objects representing the incoming transform arguments
* @param fields a list of opaque objects representing the field values of the receiver
* @param <X> the common element type of the various lists
* @return a new list
*/
protected abstract <X> List<X> deriveTransformHelperArguments(MemberName transform, int whichtm,
List<X> args, List<X> fields);
/** Given a key, generate the name of the class which implements the species for that key.
* This algorithm must be stable.
*
* @return class name, which by default is {@code outer().topClass().getName() + "$Species_" + deriveTypeString(key)}
*/
protected String deriveClassName() {
return outer().topClass().getName() + "$Species_" + deriveTypeString();
}
/**
* Default implementation collects basic type characters,
* plus possibly type names, if some types don't correspond
* to basic types.
*
* @return a string suitable for use in a class name
*/
protected String deriveTypeString() {
List<Class<?>> types = fieldTypes();
StringBuilder buf = new StringBuilder();
StringBuilder end = new StringBuilder();
for (Class<?> type : types) {
BasicType basicType = BasicType.basicType(type);
if (basicType.basicTypeClass() == type) {
buf.append(basicType.basicTypeChar());
} else {
buf.append('V');
end.append(classSig(type));
}
}
String typeString;
if (end.length() > 0) {
typeString = BytecodeName.toBytecodeName(buf.append("_").append(end).toString());
} else {
typeString = buf.toString();
}
return LambdaForm.shortenSignature(typeString);
}
/**
* Report what immediate super-class to use for the concrete class of this species.
* Normally this is {@code topClass}, but if that is an interface, the factory must override.
* The super-class must provide a constructor which takes the {@code baseConstructorType} arguments, if any.
* This hook also allows the code generator to use more than one canned supertype for species.
*
* @return the super-class of the class to be generated
*/
protected Class<? extends T> deriveSuperClass() {
final Class<T> topc = topClass();
if (!topClassIsSuper) {
try {
final Constructor<T> con = reflectConstructor(topc, baseConstructorType().parameterArray());
if (!topc.isInterface() && !Modifier.isPrivate(con.getModifiers())) {
topClassIsSuper = true;
}
} catch (Exception|InternalError ex) {
// fall through...
}
if (!topClassIsSuper) {
throw newInternalError("must override if the top class cannot serve as a super class");
}
}
return topc;
}
}
protected abstract S newSpeciesData(K key);
protected K topSpeciesKey() {
return null; // null means don't report a top species
}
/**
* Code generation support for instances.
* Subclasses can modify the behavior.
*/
public class Factory {
/**
* Constructs a factory.
*/
Factory() {}
/**
* Get a concrete subclass of the top class for a given combination of bound types.
*
* @param speciesData the species requiring the class, not yet linked
* @return a linked version of the same species
*/
S loadSpecies(S speciesData) {
String className = speciesData.deriveClassName();
assert(className.indexOf('/') < 0) : className;
Class<?> salvage = null;
try {
salvage = BootLoader.loadClassOrNull(className);
} catch (Error ex) {
// ignore
} finally {
traceSpeciesType(className, salvage);
}
final Class<? extends T> speciesCode;
if (salvage != null) {
speciesCode = salvage.asSubclass(topClass());
linkSpeciesDataToCode(speciesData, speciesCode);
linkCodeToSpeciesData(speciesCode, speciesData, true);
} else {
// Not pregenerated, generate the class
try {
speciesCode = generateConcreteSpeciesCode(className, speciesData);
// This operation causes a lot of churn:
linkSpeciesDataToCode(speciesData, speciesCode);
// This operation commits the relation, but causes little churn:
linkCodeToSpeciesData(speciesCode, speciesData, false);
} catch (Error ex) {
// We can get here if there is a race condition loading a class.
// Or maybe we are out of resources. Back out of the CHM.get and retry.
throw ex;
}
}
if (!speciesData.isResolved()) {
throw newInternalError("bad species class linkage for " + className + ": " + speciesData);
}
assert(speciesData == loadSpeciesDataFromCode(speciesCode));
return speciesData;
}
/**
* Generate a concrete subclass of the top class for a given combination of bound types.
*
* A concrete species subclass roughly matches the following schema:
*
* <pre>
* class Species_[[types]] extends [[T]] {
* final [[S]] speciesData() { return ... }
* static [[T]] make([[fields]]) { return ... }
* [[fields]]
* final [[T]] transform([[args]]) { return ... }
* }
* </pre>
*
* The {@code [[types]]} signature is precisely the key for the species.
*
* The {@code [[fields]]} section consists of one field definition per character in
* the type signature, adhering to the naming schema described in the definition of
* {@link #chooseFieldName}.
*
* For example, a concrete species for two references and one integral bound value
* has a shape like the following:
*
* <pre>
* class TopClass {
* ...
* private static final class Species_LLI extends TopClass {
* final Object argL0;
* final Object argL1;
* final int argI2;
* private Species_LLI(CT ctarg, ..., Object argL0, Object argL1, int argI2) {
* super(ctarg, ...);
* this.argL0 = argL0;
* this.argL1 = argL1;
* this.argI2 = argI2;
* }
* final SpeciesData speciesData() { return BMH_SPECIES; }
* @Stable static SpeciesData BMH_SPECIES; // injected afterwards
* static TopClass make(CT ctarg, ..., Object argL0, Object argL1, int argI2) {
* return new Species_LLI(ctarg, ..., argL0, argL1, argI2);
* }
* final TopClass copyWith(CT ctarg, ...) {
* return new Species_LLI(ctarg, ..., argL0, argL1, argI2);
* }
* // two transforms, for the sake of illustration:
* final TopClass copyWithExtendL(CT ctarg, ..., Object narg) {
* return BMH_SPECIES.transform(L_TYPE).invokeBasic(ctarg, ..., argL0, argL1, argI2, narg);
* }
* final TopClass copyWithExtendI(CT ctarg, ..., int narg) {
* return BMH_SPECIES.transform(I_TYPE).invokeBasic(ctarg, ..., argL0, argL1, argI2, narg);
* }
* }
* }
* </pre>
*
* @param className of the species
* @param speciesData what species we are generating
* @return the generated concrete TopClass class
*/
@SuppressWarnings("removal")
Class<? extends T> generateConcreteSpeciesCode(String className, ClassSpecializer<T,K,S>.SpeciesData speciesData) {
byte[] classFile = generateConcreteSpeciesCodeFile(className, speciesData);
// load class
InvokerBytecodeGenerator.maybeDump(classBCName(className), classFile);
ClassLoader cl = topClass.getClassLoader();
ProtectionDomain pd = null;
if (cl != null) {
pd = AccessController.doPrivileged(
new PrivilegedAction<>() {
@Override
public ProtectionDomain run() {
return topClass().getProtectionDomain();
}
});
}
Class<?> speciesCode = SharedSecrets.getJavaLangAccess()
.defineClass(cl, className, classFile, pd, "_ClassSpecializer_generateConcreteSpeciesCode");
return speciesCode.asSubclass(topClass());
}
// These are named like constants because there is only one per specialization scheme:
private final String SPECIES_DATA = classBCName(metaType);
private final String SPECIES_DATA_SIG = classSig(SPECIES_DATA);
private final String SPECIES_DATA_NAME = sdAccessor.getName();
private final int SPECIES_DATA_MODS = sdAccessor.getModifiers();
private final List<String> TRANSFORM_NAMES; // derived from transformMethods
private final List<MethodType> TRANSFORM_TYPES;
private final List<Integer> TRANSFORM_MODS;
{
// Tear apart transformMethods to get the names, types, and modifiers.
List<String> tns = new ArrayList<>();
List<MethodType> tts = new ArrayList<>();
List<Integer> tms = new ArrayList<>();
for (int i = 0; i < transformMethods.size(); i++) {
MemberName tm = transformMethods.get(i);
tns.add(tm.getName());
final MethodType tt = tm.getMethodType();
tts.add(tt);
tms.add(tm.getModifiers());
}
TRANSFORM_NAMES = List.of(tns.toArray(new String[0]));
TRANSFORM_TYPES = List.of(tts.toArray(new MethodType[0]));
TRANSFORM_MODS = List.of(tms.toArray(new Integer[0]));
}
private static final int ACC_PPP = ACC_PUBLIC | ACC_PRIVATE | ACC_PROTECTED;
/*non-public*/
byte[] generateConcreteSpeciesCodeFile(String className0, ClassSpecializer<T,K,S>.SpeciesData speciesData) {
final String className = classBCName(className0);
final String superClassName = classBCName(speciesData.deriveSuperClass());
final ClassWriter cw = new ClassWriter(ClassWriter.COMPUTE_MAXS + ClassWriter.COMPUTE_FRAMES);
final int NOT_ACC_PUBLIC = 0; // not ACC_PUBLIC
cw.visit(V1_6, NOT_ACC_PUBLIC + ACC_FINAL + ACC_SUPER, className, null, superClassName, null);
final String sourceFile = className.substring(className.lastIndexOf('.')+1);
cw.visitSource(sourceFile, null);
// emit static types and BMH_SPECIES fields
FieldVisitor fw = cw.visitField(NOT_ACC_PUBLIC + ACC_STATIC, sdFieldName, SPECIES_DATA_SIG, null, null);
fw.visitAnnotation(STABLE_SIG, true);
fw.visitEnd();
// handy holder for dealing with groups of typed values (ctor arguments and fields)
class Var {
final int index;
final String name;
final Class<?> type;
final String desc;
final BasicType basicType;
final int slotIndex;
Var(int index, int slotIndex) {
this.index = index;
this.slotIndex = slotIndex;
name = null; type = null; desc = null;
basicType = BasicType.V_TYPE;
}
Var(String name, Class<?> type, Var prev) {
int slotIndex = prev.nextSlotIndex();
int index = prev.nextIndex();
if (name == null) name = "x";
if (name.endsWith("#"))
name = name.substring(0, name.length()-1) + index;
assert(!type.equals(void.class));
String desc = classSig(type);
BasicType basicType = BasicType.basicType(type);
this.index = index;
this.name = name;
this.type = type;
this.desc = desc;
this.basicType = basicType;
this.slotIndex = slotIndex;
}
Var lastOf(List<Var> vars) {
int n = vars.size();
return (n == 0 ? this : vars.get(n-1));
}
<X> List<Var> fromTypes(List<X> types) {
Var prev = this;
ArrayList<Var> result = new ArrayList<>(types.size());
int i = 0;
for (X x : types) {
String vn = name;
Class<?> vt;
if (x instanceof Class) {
vt = (Class<?>) x;
// make the names friendlier if debugging
assert((vn = vn + "_" + (i++)) != null);
} else {
@SuppressWarnings("unchecked")
Var v = (Var) x;
vn = v.name;
vt = v.type;
}
prev = new Var(vn, vt, prev);
result.add(prev);
}
return result;
}
int slotSize() { return basicType.basicTypeSlots(); }
int nextIndex() { return index + (slotSize() == 0 ? 0 : 1); }
int nextSlotIndex() { return slotIndex >= 0 ? slotIndex + slotSize() : slotIndex; }
boolean isInHeap() { return slotIndex < 0; }
void emitVarInstruction(int asmop, MethodVisitor mv) {
if (asmop == ALOAD)
asmop = typeLoadOp(basicType.basicTypeChar());
else
throw new AssertionError("bad op="+asmop+" for desc="+desc);
mv.visitVarInsn(asmop, slotIndex);
}
public void emitFieldInsn(int asmop, MethodVisitor mv) {
mv.visitFieldInsn(asmop, className, name, desc);
}
}
final Var NO_THIS = new Var(0, 0),
AFTER_THIS = new Var(0, 1),
IN_HEAP = new Var(0, -1);
// figure out the field types
final List<Class<?>> fieldTypes = speciesData.fieldTypes();
final List<Var> fields = new ArrayList<>(fieldTypes.size());
{
Var nextF = IN_HEAP;
for (Class<?> ft : fieldTypes) {
String fn = chooseFieldName(ft, nextF.nextIndex());
nextF = new Var(fn, ft, nextF);
fields.add(nextF);
}
}
// emit bound argument fields
for (Var field : fields) {
cw.visitField(ACC_FINAL, field.name, field.desc, null, null).visitEnd();
}
MethodVisitor mv;
// emit implementation of speciesData()
mv = cw.visitMethod((SPECIES_DATA_MODS & ACC_PPP) + ACC_FINAL,
SPECIES_DATA_NAME, "()" + SPECIES_DATA_SIG, null, null);
mv.visitCode();
mv.visitFieldInsn(GETSTATIC, className, sdFieldName, SPECIES_DATA_SIG);
mv.visitInsn(ARETURN);
mv.visitMaxs(0, 0);
mv.visitEnd();
// figure out the constructor arguments
MethodType superCtorType = ClassSpecializer.this.baseConstructorType();
MethodType thisCtorType = superCtorType.appendParameterTypes(fieldTypes);
// emit constructor
{
mv = cw.visitMethod(ACC_PRIVATE,
"<init>", methodSig(thisCtorType), null, null);
mv.visitCode();
mv.visitVarInsn(ALOAD, 0); // this
final List<Var> ctorArgs = AFTER_THIS.fromTypes(superCtorType.parameterList());
for (Var ca : ctorArgs) {
ca.emitVarInstruction(ALOAD, mv);
}
// super(ca...)
mv.visitMethodInsn(INVOKESPECIAL, superClassName,
"<init>", methodSig(superCtorType), false);
// store down fields
Var lastFV = AFTER_THIS.lastOf(ctorArgs);
for (Var f : fields) {
// this.argL1 = argL1
mv.visitVarInsn(ALOAD, 0); // this
lastFV = new Var(f.name, f.type, lastFV);
lastFV.emitVarInstruction(ALOAD, mv);
f.emitFieldInsn(PUTFIELD, mv);
}
mv.visitInsn(RETURN);
mv.visitMaxs(0, 0);
mv.visitEnd();
}
// emit make() ...factory method wrapping constructor
{
MethodType ftryType = thisCtorType.changeReturnType(topClass());
mv = cw.visitMethod(NOT_ACC_PUBLIC + ACC_STATIC,
"make", methodSig(ftryType), null, null);
mv.visitCode();
// make instance
mv.visitTypeInsn(NEW, className);
mv.visitInsn(DUP);
// load factory method arguments: ctarg... and arg...
for (Var v : NO_THIS.fromTypes(ftryType.parameterList())) {
v.emitVarInstruction(ALOAD, mv);
}
// finally, invoke the constructor and return
mv.visitMethodInsn(INVOKESPECIAL, className,
"<init>", methodSig(thisCtorType), false);
mv.visitInsn(ARETURN);
mv.visitMaxs(0, 0);
mv.visitEnd();
}
// For each transform, emit the customized override of the transform method.
// This method mixes together some incoming arguments (from the transform's
// static type signature) with the field types themselves, and passes
// the resulting mish-mosh of values to a method handle produced by
// the species itself. (Typically this method handle is the factory
// method of this species or a related one.)
for (int whichtm = 0; whichtm < TRANSFORM_NAMES.size(); whichtm++) {
final String TNAME = TRANSFORM_NAMES.get(whichtm);
final MethodType TTYPE = TRANSFORM_TYPES.get(whichtm);
final int TMODS = TRANSFORM_MODS.get(whichtm);
mv = cw.visitMethod((TMODS & ACC_PPP) | ACC_FINAL,
TNAME, TTYPE.toMethodDescriptorString(), null, E_THROWABLE);
mv.visitCode();
// return a call to the corresponding "transform helper", something like this:
// MY_SPECIES.transformHelper(whichtm).invokeBasic(ctarg, ..., argL0, ..., xarg)
mv.visitFieldInsn(GETSTATIC, className,
sdFieldName, SPECIES_DATA_SIG);
emitIntConstant(whichtm, mv);
mv.visitMethodInsn(INVOKEVIRTUAL, SPECIES_DATA,
"transformHelper", "(I)" + MH_SIG, false);
List<Var> targs = AFTER_THIS.fromTypes(TTYPE.parameterList());
List<Var> tfields = new ArrayList<>(fields);
// mix them up and load them for the transform helper:
List<Var> helperArgs = speciesData.deriveTransformHelperArguments(transformMethods.get(whichtm), whichtm, targs, tfields);
List<Class<?>> helperTypes = new ArrayList<>(helperArgs.size());
for (Var ha : helperArgs) {
helperTypes.add(ha.basicType.basicTypeClass());
if (ha.isInHeap()) {
assert(tfields.contains(ha));
mv.visitVarInsn(ALOAD, 0);
ha.emitFieldInsn(GETFIELD, mv);
} else {
assert(targs.contains(ha));
ha.emitVarInstruction(ALOAD, mv);
}
}
// jump into the helper (which is probably a factory method)
final Class<?> rtype = TTYPE.returnType();
final BasicType rbt = BasicType.basicType(rtype);
MethodType invokeBasicType = MethodType.methodType(rbt.basicTypeClass(), helperTypes);
mv.visitMethodInsn(INVOKEVIRTUAL, MH,
"invokeBasic", methodSig(invokeBasicType), false);
if (rbt == BasicType.L_TYPE) {
mv.visitTypeInsn(CHECKCAST, classBCName(rtype));
mv.visitInsn(ARETURN);
} else {
throw newInternalError("NYI: transform of type "+rtype);
}
mv.visitMaxs(0, 0);
mv.visitEnd();
}
cw.visitEnd();
return cw.toByteArray();
}
private int typeLoadOp(char t) {
return switch (t) {
case 'L' -> ALOAD;
case 'I' -> ILOAD;
case 'J' -> LLOAD;
case 'F' -> FLOAD;
case 'D' -> DLOAD;
default -> throw newInternalError("unrecognized type " + t);
};
}
private void emitIntConstant(int con, MethodVisitor mv) {
if (ICONST_M1 - ICONST_0 <= con && con <= ICONST_5 - ICONST_0)
mv.visitInsn(ICONST_0 + con);
else if (con == (byte) con)
mv.visitIntInsn(BIPUSH, con);
else if (con == (short) con)
mv.visitIntInsn(SIPUSH, con);
else {
mv.visitLdcInsn(con);
}
}
//
// Getter MH generation.
//
private MethodHandle findGetter(Class<?> speciesCode, List<Class<?>> types, int index) {
Class<?> fieldType = types.get(index);
String fieldName = chooseFieldName(fieldType, index);
try {
return IMPL_LOOKUP.findGetter(speciesCode, fieldName, fieldType);
} catch (NoSuchFieldException | IllegalAccessException e) {
throw newInternalError(e);
}
}
private List<MethodHandle> findGetters(Class<?> speciesCode, List<Class<?>> types) {
MethodHandle[] mhs = new MethodHandle[types.size()];
for (int i = 0; i < mhs.length; ++i) {
mhs[i] = findGetter(speciesCode, types, i);
assert(mhs[i].internalMemberName().getDeclaringClass() == speciesCode);
}
return List.of(mhs);
}
private List<MethodHandle> findFactories(Class<? extends T> speciesCode, List<Class<?>> types) {
MethodHandle[] mhs = new MethodHandle[1];
mhs[0] = findFactory(speciesCode, types);
return List.of(mhs);
}
List<LambdaForm.NamedFunction> makeNominalGetters(List<Class<?>> types, List<MethodHandle> getters) {
LambdaForm.NamedFunction[] nfs = new LambdaForm.NamedFunction[types.size()];
for (int i = 0; i < nfs.length; ++i) {
nfs[i] = new LambdaForm.NamedFunction(getters.get(i));
}
return List.of(nfs);
}
//
// Auxiliary methods.
//
protected void linkSpeciesDataToCode(ClassSpecializer<T,K,S>.SpeciesData speciesData, Class<? extends T> speciesCode) {
speciesData.speciesCode = speciesCode.asSubclass(topClass);
final List<Class<?>> types = speciesData.fieldTypes;
speciesData.factories = this.findFactories(speciesCode, types);
speciesData.getters = this.findGetters(speciesCode, types);
speciesData.nominalGetters = this.makeNominalGetters(types, speciesData.getters);
}
private Field reflectSDField(Class<? extends T> speciesCode) {
final Field field = reflectField(speciesCode, sdFieldName);
assert(field.getType() == metaType);
assert(Modifier.isStatic(field.getModifiers()));
return field;
}
private S readSpeciesDataFromCode(Class<? extends T> speciesCode) {
try {
MemberName sdField = IMPL_LOOKUP.resolveOrFail(REF_getStatic, speciesCode, sdFieldName, metaType);
Object base = MethodHandleNatives.staticFieldBase(sdField);
long offset = MethodHandleNatives.staticFieldOffset(sdField);
UNSAFE.loadFence();
return metaType.cast(UNSAFE.getReference(base, offset));
} catch (Error err) {
throw err;
} catch (Exception ex) {
throw newInternalError("Failed to load speciesData from speciesCode: " + speciesCode.getName(), ex);
} catch (Throwable t) {
throw uncaughtException(t);
}
}
protected S loadSpeciesDataFromCode(Class<? extends T> speciesCode) {
if (speciesCode == topClass()) {
return topSpecies;
}
S result = readSpeciesDataFromCode(speciesCode);
if (result.outer() != ClassSpecializer.this) {
throw newInternalError("wrong class");
}
return result;
}
protected void linkCodeToSpeciesData(Class<? extends T> speciesCode, ClassSpecializer<T,K,S>.SpeciesData speciesData, boolean salvage) {
try {
assert(readSpeciesDataFromCode(speciesCode) == null ||
(salvage && readSpeciesDataFromCode(speciesCode).equals(speciesData)));
MemberName sdField = IMPL_LOOKUP.resolveOrFail(REF_putStatic, speciesCode, sdFieldName, metaType);
Object base = MethodHandleNatives.staticFieldBase(sdField);
long offset = MethodHandleNatives.staticFieldOffset(sdField);
UNSAFE.storeFence();
UNSAFE.putReference(base, offset, speciesData);
UNSAFE.storeFence();
} catch (Error err) {
throw err;
} catch (Exception ex) {
throw newInternalError("Failed to link speciesData to speciesCode: " + speciesCode.getName(), ex);
} catch (Throwable t) {
throw uncaughtException(t);
}
}
/**
* Field names in concrete species classes adhere to this pattern:
* type + index, where type is a single character (L, I, J, F, D).
* The factory subclass can customize this.
* The name is purely cosmetic, since it applies to a private field.
*/
protected String chooseFieldName(Class<?> type, int index) {
BasicType bt = BasicType.basicType(type);
return "" + bt.basicTypeChar() + index;
}
MethodHandle findFactory(Class<? extends T> speciesCode, List<Class<?>> types) {
final MethodType type = baseConstructorType().changeReturnType(topClass()).appendParameterTypes(types);
try {
return IMPL_LOOKUP.findStatic(speciesCode, "make", type);
} catch (NoSuchMethodException | IllegalAccessException | IllegalArgumentException | TypeNotPresentException e) {
throw newInternalError(e);
}
}
}
/** Hook that virtualizes the Factory class, allowing subclasses to extend it. */
protected Factory makeFactory() {
return new Factory();
}
// Other misc helpers:
private static final String MH = "java/lang/invoke/MethodHandle";
private static final String MH_SIG = "L" + MH + ";";
private static final String STABLE = "jdk/internal/vm/annotation/Stable";
private static final String STABLE_SIG = "L" + STABLE + ";";
private static final String[] E_THROWABLE = new String[] { "java/lang/Throwable" };
static {
assert(MH_SIG.equals(classSig(MethodHandle.class)));
assert(MH.equals(classBCName(MethodHandle.class)));
}
static String methodSig(MethodType mt) {
return mt.toMethodDescriptorString();
}
static String classSig(Class<?> cls) {
if (cls.isPrimitive() || cls.isArray())
return MethodType.methodType(cls).toMethodDescriptorString().substring(2);
return classSig(classBCName(cls));
}
static String classSig(String bcName) {
assert(bcName.indexOf('.') < 0);
assert(!bcName.endsWith(";"));
assert(!bcName.startsWith("["));
return "L" + bcName + ";";
}
static String classBCName(Class<?> cls) {
return classBCName(className(cls));
}
static String classBCName(String str) {
assert(str.indexOf('/') < 0) : str;
return str.replace('.', '/');
}
static String className(Class<?> cls) {
assert(!cls.isArray() && !cls.isPrimitive());
return cls.getName();
}
}
⏎ java/lang/invoke/ClassSpecializer.java
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2023-09-26, 44478👍, 1💬
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