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⏎ java/lang/invoke/InvokerBytecodeGenerator.java
/*
* Copyright (c) 2012, 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.org.objectweb.asm.ClassWriter;
import jdk.internal.org.objectweb.asm.FieldVisitor;
import jdk.internal.org.objectweb.asm.Label;
import jdk.internal.org.objectweb.asm.MethodVisitor;
import jdk.internal.org.objectweb.asm.Opcodes;
import jdk.internal.org.objectweb.asm.Type;
import sun.invoke.util.VerifyAccess;
import sun.invoke.util.VerifyType;
import sun.invoke.util.Wrapper;
import sun.reflect.misc.ReflectUtil;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.lang.reflect.Modifier;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.stream.Stream;
import static java.lang.invoke.LambdaForm.BasicType;
import static java.lang.invoke.LambdaForm.BasicType.*;
import static java.lang.invoke.LambdaForm.*;
import static java.lang.invoke.MethodHandleNatives.Constants.*;
import static java.lang.invoke.MethodHandleStatics.*;
import static java.lang.invoke.MethodHandles.Lookup.*;
/**
* Code generation backend for LambdaForm.
* <p>
* @author John Rose, JSR 292 EG
*/
class InvokerBytecodeGenerator {
/** Define class names for convenience. */
private static final String MH = "java/lang/invoke/MethodHandle";
private static final String MHI = "java/lang/invoke/MethodHandleImpl";
private static final String LF = "java/lang/invoke/LambdaForm";
private static final String LFN = "java/lang/invoke/LambdaForm$Name";
private static final String CLS = "java/lang/Class";
private static final String OBJ = "java/lang/Object";
private static final String OBJARY = "[Ljava/lang/Object;";
private static final String LOOP_CLAUSES = MHI + "$LoopClauses";
private static final String MHARY2 = "[[L" + MH + ";";
private static final String MH_SIG = "L" + MH + ";";
private static final String LF_SIG = "L" + LF + ";";
private static final String LFN_SIG = "L" + LFN + ";";
private static final String LL_SIG = "(L" + OBJ + ";)L" + OBJ + ";";
private static final String LLV_SIG = "(L" + OBJ + ";L" + OBJ + ";)V";
private static final String CLASS_PREFIX = LF + "$";
private static final String SOURCE_PREFIX = "LambdaForm$";
/** Name of its super class*/
static final String INVOKER_SUPER_NAME = OBJ;
/** Name of new class */
private final String name;
private final String className;
private final LambdaForm lambdaForm;
private final String invokerName;
private final MethodType invokerType;
/** Info about local variables in compiled lambda form */
private int[] localsMap; // index
private Class<?>[] localClasses; // type
/** ASM bytecode generation. */
private ClassWriter cw;
private MethodVisitor mv;
private final List<ClassData> classData = new ArrayList<>();
/** Single element internal class name lookup cache. */
private Class<?> lastClass;
private String lastInternalName;
private static final MemberName.Factory MEMBERNAME_FACTORY = MemberName.getFactory();
private static final Class<?> HOST_CLASS = LambdaForm.class;
private static final MethodHandles.Lookup LOOKUP = lookup();
private static MethodHandles.Lookup lookup() {
try {
return MethodHandles.privateLookupIn(HOST_CLASS, IMPL_LOOKUP);
} catch (IllegalAccessException e) {
throw newInternalError(e);
}
}
/** Main constructor; other constructors delegate to this one. */
private InvokerBytecodeGenerator(LambdaForm lambdaForm, int localsMapSize,
String name, String invokerName, MethodType invokerType) {
int p = invokerName.indexOf('.');
if (p > -1) {
name = invokerName.substring(0, p);
invokerName = invokerName.substring(p + 1);
}
if (DUMP_CLASS_FILES) {
name = makeDumpableClassName(name);
}
this.name = name;
this.className = CLASS_PREFIX + name;
this.lambdaForm = lambdaForm;
this.invokerName = invokerName;
this.invokerType = invokerType;
this.localsMap = new int[localsMapSize+1]; // last entry of localsMap is count of allocated local slots
this.localClasses = new Class<?>[localsMapSize+1];
}
/** For generating LambdaForm interpreter entry points. */
private InvokerBytecodeGenerator(String name, String invokerName, MethodType invokerType) {
this(null, invokerType.parameterCount(),
name, invokerName, invokerType);
MethodType mt = invokerType.erase();
// Create an array to map name indexes to locals indexes.
localsMap[0] = 0; // localsMap has at least one element
for (int i = 1, index = 0; i < localsMap.length; i++) {
Wrapper w = Wrapper.forBasicType(mt.parameterType(i - 1));
index += w.stackSlots();
localsMap[i] = index;
}
}
/** For generating customized code for a single LambdaForm. */
private InvokerBytecodeGenerator(String name, LambdaForm form, MethodType invokerType) {
this(name, form.lambdaName(), form, invokerType);
}
/** For generating customized code for a single LambdaForm. */
InvokerBytecodeGenerator(String name, String invokerName,
LambdaForm form, MethodType invokerType) {
this(form, form.names.length,
name, invokerName, invokerType);
// Create an array to map name indexes to locals indexes.
Name[] names = form.names;
for (int i = 0, index = 0; i < localsMap.length; i++) {
localsMap[i] = index;
if (i < names.length) {
BasicType type = names[i].type();
index += type.basicTypeSlots();
}
}
}
/** instance counters for dumped classes */
private static final HashMap<String,Integer> DUMP_CLASS_FILES_COUNTERS;
/** debugging flag for saving generated class files */
private static final File DUMP_CLASS_FILES_DIR;
static {
if (DUMP_CLASS_FILES) {
DUMP_CLASS_FILES_COUNTERS = new HashMap<>();
try {
File dumpDir = new File("DUMP_CLASS_FILES");
if (!dumpDir.exists()) {
dumpDir.mkdirs();
}
DUMP_CLASS_FILES_DIR = dumpDir;
System.out.println("Dumping class files to "+DUMP_CLASS_FILES_DIR+"/...");
} catch (Exception e) {
throw newInternalError(e);
}
} else {
DUMP_CLASS_FILES_COUNTERS = null;
DUMP_CLASS_FILES_DIR = null;
}
}
private void maybeDump(final byte[] classFile) {
if (DUMP_CLASS_FILES) {
maybeDump(className, classFile);
}
}
// Also used from BoundMethodHandle
@SuppressWarnings("removal")
static void maybeDump(final String className, final byte[] classFile) {
if (DUMP_CLASS_FILES) {
java.security.AccessController.doPrivileged(
new java.security.PrivilegedAction<>() {
public Void run() {
try {
String dumpName = className.replace('.','/');
File dumpFile = new File(DUMP_CLASS_FILES_DIR, dumpName+".class");
System.out.println("dump: " + dumpFile);
dumpFile.getParentFile().mkdirs();
FileOutputStream file = new FileOutputStream(dumpFile);
file.write(classFile);
file.close();
return null;
} catch (IOException ex) {
throw newInternalError(ex);
}
}
});
}
}
private static String makeDumpableClassName(String className) {
Integer ctr;
synchronized (DUMP_CLASS_FILES_COUNTERS) {
ctr = DUMP_CLASS_FILES_COUNTERS.get(className);
if (ctr == null) ctr = 0;
DUMP_CLASS_FILES_COUNTERS.put(className, ctr+1);
}
String sfx = ctr.toString();
while (sfx.length() < 3)
sfx = "0" + sfx;
className += sfx;
return className;
}
static class ClassData {
final String name;
final String desc;
final Object value;
ClassData(String name, String desc, Object value) {
this.name = name;
this.desc = desc;
this.value = value;
}
public String name() { return name; }
public String toString() {
return name + ",value="+value;
}
}
String classData(Object arg) {
String desc;
if (arg instanceof Class) {
desc = "Ljava/lang/Class;";
} else if (arg instanceof MethodHandle) {
desc = MH_SIG;
} else if (arg instanceof LambdaForm) {
desc = LF_SIG;
} else {
desc = "Ljava/lang/Object;";
}
// unique static variable name
String name;
if (DUMP_CLASS_FILES) {
Class<?> c = arg.getClass();
while (c.isArray()) {
c = c.getComponentType();
}
name = "_DATA_" + c.getSimpleName() + "_" + classData.size();
} else {
name = "_D_" + classData.size();
}
ClassData cd = new ClassData(name, desc, arg);
classData.add(cd);
return name;
}
List<Object> classDataValues() {
final List<ClassData> cd = classData;
return switch(cd.size()) {
case 0 -> List.of();
case 1 -> List.of(cd.get(0).value);
case 2 -> List.of(cd.get(0).value, cd.get(1).value);
case 3 -> List.of(cd.get(0).value, cd.get(1).value, cd.get(2).value);
case 4 -> List.of(cd.get(0).value, cd.get(1).value, cd.get(2).value, cd.get(3).value);
default -> {
Object[] data = new Object[classData.size()];
for (int i = 0; i < classData.size(); i++) {
data[i] = classData.get(i).value;
}
yield List.of(data);
}
};
}
private static String debugString(Object arg) {
if (arg instanceof MethodHandle mh) {
MemberName member = mh.internalMemberName();
if (member != null)
return member.toString();
return mh.debugString();
}
return arg.toString();
}
/**
* Extract the MemberName of a newly-defined method.
*/
private MemberName loadMethod(byte[] classFile) {
Class<?> invokerClass = LOOKUP.makeHiddenClassDefiner(className, classFile)
.defineClass(true, classDataValues());
return resolveInvokerMember(invokerClass, invokerName, invokerType);
}
private static MemberName resolveInvokerMember(Class<?> invokerClass, String name, MethodType type) {
MemberName member = new MemberName(invokerClass, name, type, REF_invokeStatic);
try {
member = MEMBERNAME_FACTORY.resolveOrFail(REF_invokeStatic, member,
HOST_CLASS, LM_TRUSTED,
ReflectiveOperationException.class);
} catch (ReflectiveOperationException e) {
throw newInternalError(e);
}
return member;
}
/**
* Set up class file generation.
*/
private ClassWriter classFilePrologue() {
final int NOT_ACC_PUBLIC = 0; // not ACC_PUBLIC
ClassWriter cw = new ClassWriter(ClassWriter.COMPUTE_MAXS + ClassWriter.COMPUTE_FRAMES);
setClassWriter(cw);
cw.visit(Opcodes.V1_8, NOT_ACC_PUBLIC + Opcodes.ACC_FINAL + Opcodes.ACC_SUPER,
className, null, INVOKER_SUPER_NAME, null);
cw.visitSource(SOURCE_PREFIX + name, null);
return cw;
}
private void methodPrologue() {
String invokerDesc = invokerType.toMethodDescriptorString();
mv = cw.visitMethod(Opcodes.ACC_STATIC, invokerName, invokerDesc, null, null);
}
/**
* Tear down class file generation.
*/
private void methodEpilogue() {
mv.visitMaxs(0, 0);
mv.visitEnd();
}
/*
* <clinit> to initialize the static final fields with the live class data
* LambdaForms can't use condy due to bootstrapping issue.
*/
static void clinit(ClassWriter cw, String className, List<ClassData> classData) {
if (classData.isEmpty())
return;
for (ClassData p : classData) {
// add the static field
FieldVisitor fv = cw.visitField(Opcodes.ACC_STATIC|Opcodes.ACC_FINAL, p.name, p.desc, null, null);
fv.visitEnd();
}
MethodVisitor mv = cw.visitMethod(Opcodes.ACC_STATIC, "<clinit>", "()V", null, null);
mv.visitCode();
mv.visitLdcInsn(Type.getType("L" + className + ";"));
mv.visitMethodInsn(Opcodes.INVOKESTATIC, "java/lang/invoke/MethodHandleNatives",
"classData", "(Ljava/lang/Class;)Ljava/lang/Object;", false);
// we should optimize one single element case that does not need to create a List
mv.visitTypeInsn(Opcodes.CHECKCAST, "java/util/List");
mv.visitVarInsn(Opcodes.ASTORE, 0);
int index = 0;
for (ClassData p : classData) {
// initialize the static field
mv.visitVarInsn(Opcodes.ALOAD, 0);
emitIconstInsn(mv, index++);
mv.visitMethodInsn(Opcodes.INVOKEINTERFACE, "java/util/List",
"get", "(I)Ljava/lang/Object;", true);
mv.visitTypeInsn(Opcodes.CHECKCAST, p.desc.substring(1, p.desc.length()-1));
mv.visitFieldInsn(Opcodes.PUTSTATIC, className, p.name, p.desc);
}
mv.visitInsn(Opcodes.RETURN);
mv.visitMaxs(2, 1);
mv.visitEnd();
}
/*
* Low-level emit helpers.
*/
private void emitConst(Object con) {
if (con == null) {
mv.visitInsn(Opcodes.ACONST_NULL);
return;
}
if (con instanceof Integer) {
emitIconstInsn((int) con);
return;
}
if (con instanceof Byte) {
emitIconstInsn((byte)con);
return;
}
if (con instanceof Short) {
emitIconstInsn((short)con);
return;
}
if (con instanceof Character) {
emitIconstInsn((char)con);
return;
}
if (con instanceof Long) {
long x = (long) con;
short sx = (short)x;
if (x == sx) {
if (sx >= 0 && sx <= 1) {
mv.visitInsn(Opcodes.LCONST_0 + (int) sx);
} else {
emitIconstInsn((int) x);
mv.visitInsn(Opcodes.I2L);
}
return;
}
}
if (con instanceof Float) {
float x = (float) con;
short sx = (short)x;
if (x == sx) {
if (sx >= 0 && sx <= 2) {
mv.visitInsn(Opcodes.FCONST_0 + (int) sx);
} else {
emitIconstInsn((int) x);
mv.visitInsn(Opcodes.I2F);
}
return;
}
}
if (con instanceof Double) {
double x = (double) con;
short sx = (short)x;
if (x == sx) {
if (sx >= 0 && sx <= 1) {
mv.visitInsn(Opcodes.DCONST_0 + (int) sx);
} else {
emitIconstInsn((int) x);
mv.visitInsn(Opcodes.I2D);
}
return;
}
}
if (con instanceof Boolean) {
emitIconstInsn((boolean) con ? 1 : 0);
return;
}
// fall through:
mv.visitLdcInsn(con);
}
private void emitIconstInsn(final int cst) {
emitIconstInsn(mv, cst);
}
private static void emitIconstInsn(MethodVisitor mv, int cst) {
if (cst >= -1 && cst <= 5) {
mv.visitInsn(Opcodes.ICONST_0 + cst);
} else if (cst >= Byte.MIN_VALUE && cst <= Byte.MAX_VALUE) {
mv.visitIntInsn(Opcodes.BIPUSH, cst);
} else if (cst >= Short.MIN_VALUE && cst <= Short.MAX_VALUE) {
mv.visitIntInsn(Opcodes.SIPUSH, cst);
} else {
mv.visitLdcInsn(cst);
}
}
/*
* NOTE: These load/store methods use the localsMap to find the correct index!
*/
private void emitLoadInsn(BasicType type, int index) {
int opcode = loadInsnOpcode(type);
mv.visitVarInsn(opcode, localsMap[index]);
}
private int loadInsnOpcode(BasicType type) throws InternalError {
return switch (type) {
case I_TYPE -> Opcodes.ILOAD;
case J_TYPE -> Opcodes.LLOAD;
case F_TYPE -> Opcodes.FLOAD;
case D_TYPE -> Opcodes.DLOAD;
case L_TYPE -> Opcodes.ALOAD;
default -> throw new InternalError("unknown type: " + type);
};
}
private void emitAloadInsn(int index) {
emitLoadInsn(L_TYPE, index);
}
private void emitStoreInsn(BasicType type, int index) {
int opcode = storeInsnOpcode(type);
mv.visitVarInsn(opcode, localsMap[index]);
}
private int storeInsnOpcode(BasicType type) throws InternalError {
return switch (type) {
case I_TYPE -> Opcodes.ISTORE;
case J_TYPE -> Opcodes.LSTORE;
case F_TYPE -> Opcodes.FSTORE;
case D_TYPE -> Opcodes.DSTORE;
case L_TYPE -> Opcodes.ASTORE;
default -> throw new InternalError("unknown type: " + type);
};
}
private void emitAstoreInsn(int index) {
emitStoreInsn(L_TYPE, index);
}
private byte arrayTypeCode(Wrapper elementType) {
return (byte) switch (elementType) {
case BOOLEAN -> Opcodes.T_BOOLEAN;
case BYTE -> Opcodes.T_BYTE;
case CHAR -> Opcodes.T_CHAR;
case SHORT -> Opcodes.T_SHORT;
case INT -> Opcodes.T_INT;
case LONG -> Opcodes.T_LONG;
case FLOAT -> Opcodes.T_FLOAT;
case DOUBLE -> Opcodes.T_DOUBLE;
case OBJECT -> 0; // in place of Opcodes.T_OBJECT
default -> throw new InternalError();
};
}
private int arrayInsnOpcode(byte tcode, int aaop) throws InternalError {
assert(aaop == Opcodes.AASTORE || aaop == Opcodes.AALOAD);
int xas = switch (tcode) {
case Opcodes.T_BOOLEAN -> Opcodes.BASTORE;
case Opcodes.T_BYTE -> Opcodes.BASTORE;
case Opcodes.T_CHAR -> Opcodes.CASTORE;
case Opcodes.T_SHORT -> Opcodes.SASTORE;
case Opcodes.T_INT -> Opcodes.IASTORE;
case Opcodes.T_LONG -> Opcodes.LASTORE;
case Opcodes.T_FLOAT -> Opcodes.FASTORE;
case Opcodes.T_DOUBLE -> Opcodes.DASTORE;
case 0 -> Opcodes.AASTORE;
default -> throw new InternalError();
};
return xas - Opcodes.AASTORE + aaop;
}
/**
* Emit a boxing call.
*
* @param wrapper primitive type class to box.
*/
private void emitBoxing(Wrapper wrapper) {
String owner = "java/lang/" + wrapper.wrapperType().getSimpleName();
String name = "valueOf";
String desc = "(" + wrapper.basicTypeChar() + ")L" + owner + ";";
mv.visitMethodInsn(Opcodes.INVOKESTATIC, owner, name, desc, false);
}
/**
* Emit an unboxing call (plus preceding checkcast).
*
* @param wrapper wrapper type class to unbox.
*/
private void emitUnboxing(Wrapper wrapper) {
String owner = "java/lang/" + wrapper.wrapperType().getSimpleName();
String name = wrapper.primitiveSimpleName() + "Value";
String desc = "()" + wrapper.basicTypeChar();
emitReferenceCast(wrapper.wrapperType(), null);
mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, owner, name, desc, false);
}
/**
* Emit an implicit conversion for an argument which must be of the given pclass.
* This is usually a no-op, except when pclass is a subword type or a reference other than Object or an interface.
*
* @param ptype type of value present on stack
* @param pclass type of value required on stack
* @param arg compile-time representation of value on stack (Node, constant) or null if none
*/
private void emitImplicitConversion(BasicType ptype, Class<?> pclass, Object arg) {
assert(basicType(pclass) == ptype); // boxing/unboxing handled by caller
if (pclass == ptype.basicTypeClass() && ptype != L_TYPE)
return; // nothing to do
switch (ptype) {
case L_TYPE:
if (VerifyType.isNullConversion(Object.class, pclass, false)) {
if (PROFILE_LEVEL > 0)
emitReferenceCast(Object.class, arg);
return;
}
emitReferenceCast(pclass, arg);
return;
case I_TYPE:
if (!VerifyType.isNullConversion(int.class, pclass, false))
emitPrimCast(ptype.basicTypeWrapper(), Wrapper.forPrimitiveType(pclass));
return;
}
throw newInternalError("bad implicit conversion: tc="+ptype+": "+pclass);
}
/** Update localClasses type map. Return true if the information is already present. */
private boolean assertStaticType(Class<?> cls, Name n) {
int local = n.index();
Class<?> aclass = localClasses[local];
if (aclass != null && (aclass == cls || cls.isAssignableFrom(aclass))) {
return true; // type info is already present
} else if (aclass == null || aclass.isAssignableFrom(cls)) {
localClasses[local] = cls; // type info can be improved
}
return false;
}
private void emitReferenceCast(Class<?> cls, Object arg) {
Name writeBack = null; // local to write back result
if (arg instanceof Name n) {
if (lambdaForm.useCount(n) > 1) {
// This guy gets used more than once.
writeBack = n;
if (assertStaticType(cls, n)) {
return; // this cast was already performed
}
}
}
if (isStaticallyNameable(cls)) {
String sig = getInternalName(cls);
mv.visitTypeInsn(Opcodes.CHECKCAST, sig);
} else {
mv.visitFieldInsn(Opcodes.GETSTATIC, className, classData(cls), "Ljava/lang/Class;");
mv.visitInsn(Opcodes.SWAP);
mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, CLS, "cast", LL_SIG, false);
if (Object[].class.isAssignableFrom(cls))
mv.visitTypeInsn(Opcodes.CHECKCAST, OBJARY);
else if (PROFILE_LEVEL > 0)
mv.visitTypeInsn(Opcodes.CHECKCAST, OBJ);
}
if (writeBack != null) {
mv.visitInsn(Opcodes.DUP);
emitAstoreInsn(writeBack.index());
}
}
/**
* Emits an actual return instruction conforming to the given return type.
*/
private void emitReturnInsn(BasicType type) {
int opcode = switch (type) {
case I_TYPE -> Opcodes.IRETURN;
case J_TYPE -> Opcodes.LRETURN;
case F_TYPE -> Opcodes.FRETURN;
case D_TYPE -> Opcodes.DRETURN;
case L_TYPE -> Opcodes.ARETURN;
case V_TYPE -> Opcodes.RETURN;
default -> throw new InternalError("unknown return type: " + type);
};
mv.visitInsn(opcode);
}
private String getInternalName(Class<?> c) {
if (c == Object.class) return OBJ;
else if (c == Object[].class) return OBJARY;
else if (c == Class.class) return CLS;
else if (c == MethodHandle.class) return MH;
assert(VerifyAccess.isTypeVisible(c, Object.class)) : c.getName();
if (c == lastClass) {
return lastInternalName;
}
lastClass = c;
return lastInternalName = c.getName().replace('.', '/');
}
private static MemberName resolveFrom(String name, MethodType type, Class<?> holder) {
assert(!UNSAFE.shouldBeInitialized(holder)) : holder + "not initialized";
MemberName member = new MemberName(holder, name, type, REF_invokeStatic);
MemberName resolvedMember = MemberName.getFactory().resolveOrNull(REF_invokeStatic, member, holder, LM_TRUSTED);
traceLambdaForm(name, type, holder, resolvedMember);
return resolvedMember;
}
private static MemberName lookupPregenerated(LambdaForm form, MethodType invokerType) {
if (form.customized != null) {
// No pre-generated version for customized LF
return null;
}
String name = form.kind.methodName;
switch (form.kind) {
case BOUND_REINVOKER: {
name = name + "_" + BoundMethodHandle.speciesDataFor(form).key();
return resolveFrom(name, invokerType, DelegatingMethodHandle.Holder.class);
}
case DELEGATE: return resolveFrom(name, invokerType, DelegatingMethodHandle.Holder.class);
case ZERO: // fall-through
case IDENTITY: {
name = name + "_" + form.returnType().basicTypeChar();
return resolveFrom(name, invokerType, LambdaForm.Holder.class);
}
case EXACT_INVOKER: // fall-through
case EXACT_LINKER: // fall-through
case LINK_TO_CALL_SITE: // fall-through
case LINK_TO_TARGET_METHOD: // fall-through
case GENERIC_INVOKER: // fall-through
case GENERIC_LINKER: return resolveFrom(name, invokerType, Invokers.Holder.class);
case GET_REFERENCE: // fall-through
case GET_BOOLEAN: // fall-through
case GET_BYTE: // fall-through
case GET_CHAR: // fall-through
case GET_SHORT: // fall-through
case GET_INT: // fall-through
case GET_LONG: // fall-through
case GET_FLOAT: // fall-through
case GET_DOUBLE: // fall-through
case PUT_REFERENCE: // fall-through
case PUT_BOOLEAN: // fall-through
case PUT_BYTE: // fall-through
case PUT_CHAR: // fall-through
case PUT_SHORT: // fall-through
case PUT_INT: // fall-through
case PUT_LONG: // fall-through
case PUT_FLOAT: // fall-through
case PUT_DOUBLE: // fall-through
case DIRECT_NEW_INVOKE_SPECIAL: // fall-through
case DIRECT_INVOKE_INTERFACE: // fall-through
case DIRECT_INVOKE_SPECIAL: // fall-through
case DIRECT_INVOKE_SPECIAL_IFC: // fall-through
case DIRECT_INVOKE_STATIC: // fall-through
case DIRECT_INVOKE_STATIC_INIT: // fall-through
case DIRECT_INVOKE_VIRTUAL: return resolveFrom(name, invokerType, DirectMethodHandle.Holder.class);
}
return null;
}
/**
* Generate customized bytecode for a given LambdaForm.
*/
static MemberName generateCustomizedCode(LambdaForm form, MethodType invokerType) {
MemberName pregenerated = lookupPregenerated(form, invokerType);
if (pregenerated != null) return pregenerated; // pre-generated bytecode
InvokerBytecodeGenerator g = new InvokerBytecodeGenerator("MH", form, invokerType);
return g.loadMethod(g.generateCustomizedCodeBytes());
}
/** Generates code to check that actual receiver and LambdaForm matches */
private boolean checkActualReceiver() {
// Expects MethodHandle on the stack and actual receiver MethodHandle in slot #0
mv.visitInsn(Opcodes.DUP);
mv.visitVarInsn(Opcodes.ALOAD, localsMap[0]);
mv.visitMethodInsn(Opcodes.INVOKESTATIC, MHI, "assertSame", LLV_SIG, false);
return true;
}
static String className(String cn) {
assert checkClassName(cn): "Class not found: " + cn;
return cn;
}
static boolean checkClassName(String cn) {
Type tp = Type.getType(cn);
// additional sanity so only valid "L;" descriptors work
if (tp.getSort() != Type.OBJECT) {
return false;
}
try {
Class<?> c = Class.forName(tp.getClassName(), false, null);
return true;
} catch (ClassNotFoundException e) {
return false;
}
}
static final String DONTINLINE_SIG = className("Ljdk/internal/vm/annotation/DontInline;");
static final String FORCEINLINE_SIG = className("Ljdk/internal/vm/annotation/ForceInline;");
static final String HIDDEN_SIG = className("Ljdk/internal/vm/annotation/Hidden;");
static final String INJECTEDPROFILE_SIG = className("Ljava/lang/invoke/InjectedProfile;");
static final String LF_COMPILED_SIG = className("Ljava/lang/invoke/LambdaForm$Compiled;");
/**
* Generate an invoker method for the passed {@link LambdaForm}.
*/
private byte[] generateCustomizedCodeBytes() {
classFilePrologue();
addMethod();
clinit(cw, className, classData);
bogusMethod(lambdaForm);
final byte[] classFile = toByteArray();
maybeDump(classFile);
return classFile;
}
void setClassWriter(ClassWriter cw) {
this.cw = cw;
}
void addMethod() {
methodPrologue();
// Suppress this method in backtraces displayed to the user.
mv.visitAnnotation(HIDDEN_SIG, true);
// Mark this method as a compiled LambdaForm
mv.visitAnnotation(LF_COMPILED_SIG, true);
if (lambdaForm.forceInline) {
// Force inlining of this invoker method.
mv.visitAnnotation(FORCEINLINE_SIG, true);
} else {
mv.visitAnnotation(DONTINLINE_SIG, true);
}
classData(lambdaForm); // keep LambdaForm instance & its compiled form lifetime tightly coupled.
if (lambdaForm.customized != null) {
// Since LambdaForm is customized for a particular MethodHandle, it's safe to substitute
// receiver MethodHandle (at slot #0) with an embedded constant and use it instead.
// It enables more efficient code generation in some situations, since embedded constants
// are compile-time constants for JIT compiler.
mv.visitFieldInsn(Opcodes.GETSTATIC, className, classData(lambdaForm.customized), MH_SIG);
mv.visitTypeInsn(Opcodes.CHECKCAST, MH);
assert(checkActualReceiver()); // expects MethodHandle on top of the stack
mv.visitVarInsn(Opcodes.ASTORE, localsMap[0]);
}
// iterate over the form's names, generating bytecode instructions for each
// start iterating at the first name following the arguments
Name onStack = null;
for (int i = lambdaForm.arity; i < lambdaForm.names.length; i++) {
Name name = lambdaForm.names[i];
emitStoreResult(onStack);
onStack = name; // unless otherwise modified below
MethodHandleImpl.Intrinsic intr = name.function.intrinsicName();
switch (intr) {
case SELECT_ALTERNATIVE:
assert lambdaForm.isSelectAlternative(i);
if (PROFILE_GWT) {
assert(name.arguments[0] instanceof Name &&
((Name)name.arguments[0]).refersTo(MethodHandleImpl.class, "profileBoolean"));
mv.visitAnnotation(INJECTEDPROFILE_SIG, true);
}
onStack = emitSelectAlternative(name, lambdaForm.names[i+1]);
i++; // skip MH.invokeBasic of the selectAlternative result
continue;
case GUARD_WITH_CATCH:
assert lambdaForm.isGuardWithCatch(i);
onStack = emitGuardWithCatch(i);
i += 2; // jump to the end of GWC idiom
continue;
case TRY_FINALLY:
assert lambdaForm.isTryFinally(i);
onStack = emitTryFinally(i);
i += 2; // jump to the end of the TF idiom
continue;
case TABLE_SWITCH:
assert lambdaForm.isTableSwitch(i);
int numCases = (Integer) name.function.intrinsicData();
onStack = emitTableSwitch(i, numCases);
i += 2; // jump to the end of the TS idiom
continue;
case LOOP:
assert lambdaForm.isLoop(i);
onStack = emitLoop(i);
i += 2; // jump to the end of the LOOP idiom
continue;
case ARRAY_LOAD:
emitArrayLoad(name);
continue;
case ARRAY_STORE:
emitArrayStore(name);
continue;
case ARRAY_LENGTH:
emitArrayLength(name);
continue;
case IDENTITY:
assert(name.arguments.length == 1);
emitPushArguments(name, 0);
continue;
case ZERO:
assert(name.arguments.length == 0);
emitConst(name.type.basicTypeWrapper().zero());
continue;
case NONE:
// no intrinsic associated
break;
default:
throw newInternalError("Unknown intrinsic: "+intr);
}
MemberName member = name.function.member();
if (isStaticallyInvocable(member)) {
emitStaticInvoke(member, name);
} else {
emitInvoke(name);
}
}
// return statement
emitReturn(onStack);
methodEpilogue();
}
/*
* @throws BytecodeGenerationException if something goes wrong when
* generating the byte code
*/
private byte[] toByteArray() {
try {
return cw.toByteArray();
} catch (RuntimeException e) {
throw new BytecodeGenerationException(e);
}
}
/**
* The BytecodeGenerationException.
*/
@SuppressWarnings("serial")
static final class BytecodeGenerationException extends RuntimeException {
BytecodeGenerationException(Exception cause) {
super(cause);
}
}
void emitArrayLoad(Name name) { emitArrayOp(name, Opcodes.AALOAD); }
void emitArrayStore(Name name) { emitArrayOp(name, Opcodes.AASTORE); }
void emitArrayLength(Name name) { emitArrayOp(name, Opcodes.ARRAYLENGTH); }
void emitArrayOp(Name name, int arrayOpcode) {
assert arrayOpcode == Opcodes.AALOAD || arrayOpcode == Opcodes.AASTORE || arrayOpcode == Opcodes.ARRAYLENGTH;
Class<?> elementType = name.function.methodType().parameterType(0).getComponentType();
assert elementType != null;
emitPushArguments(name, 0);
if (arrayOpcode != Opcodes.ARRAYLENGTH && elementType.isPrimitive()) {
Wrapper w = Wrapper.forPrimitiveType(elementType);
arrayOpcode = arrayInsnOpcode(arrayTypeCode(w), arrayOpcode);
}
mv.visitInsn(arrayOpcode);
}
/**
* Emit an invoke for the given name.
*/
void emitInvoke(Name name) {
assert(!name.isLinkerMethodInvoke()); // should use the static path for these
if (true) {
// push receiver
MethodHandle target = name.function.resolvedHandle();
assert(target != null) : name.exprString();
mv.visitFieldInsn(Opcodes.GETSTATIC, className, classData(target), MH_SIG);
emitReferenceCast(MethodHandle.class, target);
} else {
// load receiver
emitAloadInsn(0);
emitReferenceCast(MethodHandle.class, null);
mv.visitFieldInsn(Opcodes.GETFIELD, MH, "form", LF_SIG);
mv.visitFieldInsn(Opcodes.GETFIELD, LF, "names", LFN_SIG);
// TODO more to come
}
// push arguments
emitPushArguments(name, 0);
// invocation
MethodType type = name.function.methodType();
mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, MH, "invokeBasic", type.basicType().toMethodDescriptorString(), false);
}
private static final Class<?>[] STATICALLY_INVOCABLE_PACKAGES = {
// Sample classes from each package we are willing to bind to statically:
java.lang.Object.class,
java.util.Arrays.class,
jdk.internal.misc.Unsafe.class
//MethodHandle.class already covered
};
static boolean isStaticallyInvocable(NamedFunction ... functions) {
for (NamedFunction nf : functions) {
if (!isStaticallyInvocable(nf.member())) {
return false;
}
}
return true;
}
static boolean isStaticallyInvocable(Name name) {
return isStaticallyInvocable(name.function.member());
}
static boolean isStaticallyInvocable(MemberName member) {
if (member == null) return false;
if (member.isConstructor()) return false;
Class<?> cls = member.getDeclaringClass();
// Fast-path non-private members declared by MethodHandles, which is a common
// case
if (MethodHandle.class.isAssignableFrom(cls) && !member.isPrivate()) {
assert(isStaticallyInvocableType(member.getMethodOrFieldType()));
return true;
}
if (cls.isArray() || cls.isPrimitive())
return false; // FIXME
if (cls.isAnonymousClass() || cls.isLocalClass())
return false; // inner class of some sort
if (cls.getClassLoader() != MethodHandle.class.getClassLoader())
return false; // not on BCP
if (cls.isHidden())
return false;
if (!isStaticallyInvocableType(member.getMethodOrFieldType()))
return false;
if (!member.isPrivate() && VerifyAccess.isSamePackage(MethodHandle.class, cls))
return true; // in java.lang.invoke package
if (member.isPublic() && isStaticallyNameable(cls))
return true;
return false;
}
private static boolean isStaticallyInvocableType(MethodType mtype) {
if (!isStaticallyNameable(mtype.returnType()))
return false;
for (Class<?> ptype : mtype.parameterArray())
if (!isStaticallyNameable(ptype))
return false;
return true;
}
static boolean isStaticallyNameable(Class<?> cls) {
if (cls == Object.class)
return true;
if (MethodHandle.class.isAssignableFrom(cls)) {
assert(!cls.isHidden());
return true;
}
while (cls.isArray())
cls = cls.getComponentType();
if (cls.isPrimitive())
return true; // int[].class, for example
if (cls.isHidden())
return false;
// could use VerifyAccess.isClassAccessible but the following is a safe approximation
if (cls.getClassLoader() != Object.class.getClassLoader())
return false;
if (VerifyAccess.isSamePackage(MethodHandle.class, cls))
return true;
if (!Modifier.isPublic(cls.getModifiers()))
return false;
for (Class<?> pkgcls : STATICALLY_INVOCABLE_PACKAGES) {
if (VerifyAccess.isSamePackage(pkgcls, cls))
return true;
}
return false;
}
void emitStaticInvoke(Name name) {
emitStaticInvoke(name.function.member(), name);
}
/**
* Emit an invoke for the given name, using the MemberName directly.
*/
void emitStaticInvoke(MemberName member, Name name) {
assert(member.equals(name.function.member()));
Class<?> defc = member.getDeclaringClass();
String cname = getInternalName(defc);
String mname = member.getName();
String mtype;
byte refKind = member.getReferenceKind();
if (refKind == REF_invokeSpecial) {
// in order to pass the verifier, we need to convert this to invokevirtual in all cases
assert(member.canBeStaticallyBound()) : member;
refKind = REF_invokeVirtual;
}
assert(!(member.getDeclaringClass().isInterface() && refKind == REF_invokeVirtual));
// push arguments
emitPushArguments(name, 0);
// invocation
if (member.isMethod()) {
mtype = member.getMethodType().toMethodDescriptorString();
mv.visitMethodInsn(refKindOpcode(refKind), cname, mname, mtype,
member.getDeclaringClass().isInterface());
} else {
mtype = MethodType.toFieldDescriptorString(member.getFieldType());
mv.visitFieldInsn(refKindOpcode(refKind), cname, mname, mtype);
}
// Issue a type assertion for the result, so we can avoid casts later.
if (name.type == L_TYPE) {
Class<?> rtype = member.getInvocationType().returnType();
assert(!rtype.isPrimitive());
if (rtype != Object.class && !rtype.isInterface()) {
assertStaticType(rtype, name);
}
}
}
int refKindOpcode(byte refKind) {
switch (refKind) {
case REF_invokeVirtual: return Opcodes.INVOKEVIRTUAL;
case REF_invokeStatic: return Opcodes.INVOKESTATIC;
case REF_invokeSpecial: return Opcodes.INVOKESPECIAL;
case REF_invokeInterface: return Opcodes.INVOKEINTERFACE;
case REF_getField: return Opcodes.GETFIELD;
case REF_putField: return Opcodes.PUTFIELD;
case REF_getStatic: return Opcodes.GETSTATIC;
case REF_putStatic: return Opcodes.PUTSTATIC;
}
throw new InternalError("refKind="+refKind);
}
/**
* Emit bytecode for the selectAlternative idiom.
*
* The pattern looks like (Cf. MethodHandleImpl.makeGuardWithTest):
* <blockquote><pre>{@code
* Lambda(a0:L,a1:I)=>{
* t2:I=foo.test(a1:I);
* t3:L=MethodHandleImpl.selectAlternative(t2:I,(MethodHandle(int)int),(MethodHandle(int)int));
* t4:I=MethodHandle.invokeBasic(t3:L,a1:I);t4:I}
* }</pre></blockquote>
*/
private Name emitSelectAlternative(Name selectAlternativeName, Name invokeBasicName) {
assert isStaticallyInvocable(invokeBasicName);
Name receiver = (Name) invokeBasicName.arguments[0];
Label L_fallback = new Label();
Label L_done = new Label();
// load test result
emitPushArgument(selectAlternativeName, 0);
// if_icmpne L_fallback
mv.visitJumpInsn(Opcodes.IFEQ, L_fallback);
// invoke selectAlternativeName.arguments[1]
Class<?>[] preForkClasses = localClasses.clone();
emitPushArgument(selectAlternativeName, 1); // get 2nd argument of selectAlternative
emitAstoreInsn(receiver.index()); // store the MH in the receiver slot
emitStaticInvoke(invokeBasicName);
// goto L_done
mv.visitJumpInsn(Opcodes.GOTO, L_done);
// L_fallback:
mv.visitLabel(L_fallback);
// invoke selectAlternativeName.arguments[2]
System.arraycopy(preForkClasses, 0, localClasses, 0, preForkClasses.length);
emitPushArgument(selectAlternativeName, 2); // get 3rd argument of selectAlternative
emitAstoreInsn(receiver.index()); // store the MH in the receiver slot
emitStaticInvoke(invokeBasicName);
// L_done:
mv.visitLabel(L_done);
// for now do not bother to merge typestate; just reset to the dominator state
System.arraycopy(preForkClasses, 0, localClasses, 0, preForkClasses.length);
return invokeBasicName; // return what's on stack
}
/**
* Emit bytecode for the guardWithCatch idiom.
*
* The pattern looks like (Cf. MethodHandleImpl.makeGuardWithCatch):
* <blockquote><pre>{@code
* guardWithCatch=Lambda(a0:L,a1:L,a2:L,a3:L,a4:L,a5:L,a6:L,a7:L)=>{
* t8:L=MethodHandle.invokeBasic(a4:L,a6:L,a7:L);
* t9:L=MethodHandleImpl.guardWithCatch(a1:L,a2:L,a3:L,t8:L);
* t10:I=MethodHandle.invokeBasic(a5:L,t9:L);t10:I}
* }</pre></blockquote>
*
* It is compiled into bytecode equivalent of the following code:
* <blockquote><pre>{@code
* try {
* return a1.invokeBasic(a6, a7);
* } catch (Throwable e) {
* if (!a2.isInstance(e)) throw e;
* return a3.invokeBasic(ex, a6, a7);
* }}</pre></blockquote>
*/
private Name emitGuardWithCatch(int pos) {
Name args = lambdaForm.names[pos];
Name invoker = lambdaForm.names[pos+1];
Name result = lambdaForm.names[pos+2];
Label L_startBlock = new Label();
Label L_endBlock = new Label();
Label L_handler = new Label();
Label L_done = new Label();
Class<?> returnType = result.function.resolvedHandle().type().returnType();
MethodType type = args.function.resolvedHandle().type()
.dropParameterTypes(0,1)
.changeReturnType(returnType);
mv.visitTryCatchBlock(L_startBlock, L_endBlock, L_handler, "java/lang/Throwable");
// Normal case
mv.visitLabel(L_startBlock);
// load target
emitPushArgument(invoker, 0);
emitPushArguments(args, 1); // skip 1st argument: method handle
mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, MH, "invokeBasic", type.basicType().toMethodDescriptorString(), false);
mv.visitLabel(L_endBlock);
mv.visitJumpInsn(Opcodes.GOTO, L_done);
// Exceptional case
mv.visitLabel(L_handler);
// Check exception's type
mv.visitInsn(Opcodes.DUP);
// load exception class
emitPushArgument(invoker, 1);
mv.visitInsn(Opcodes.SWAP);
mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, "java/lang/Class", "isInstance", "(Ljava/lang/Object;)Z", false);
Label L_rethrow = new Label();
mv.visitJumpInsn(Opcodes.IFEQ, L_rethrow);
// Invoke catcher
// load catcher
emitPushArgument(invoker, 2);
mv.visitInsn(Opcodes.SWAP);
emitPushArguments(args, 1); // skip 1st argument: method handle
MethodType catcherType = type.insertParameterTypes(0, Throwable.class);
mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, MH, "invokeBasic", catcherType.basicType().toMethodDescriptorString(), false);
mv.visitJumpInsn(Opcodes.GOTO, L_done);
mv.visitLabel(L_rethrow);
mv.visitInsn(Opcodes.ATHROW);
mv.visitLabel(L_done);
return result;
}
/**
* Emit bytecode for the tryFinally idiom.
* <p>
* The pattern looks like (Cf. MethodHandleImpl.makeTryFinally):
* <blockquote><pre>{@code
* // a0: BMH
* // a1: target, a2: cleanup
* // a3: box, a4: unbox
* // a5 (and following): arguments
* tryFinally=Lambda(a0:L,a1:L,a2:L,a3:L,a4:L,a5:L)=>{
* t6:L=MethodHandle.invokeBasic(a3:L,a5:L); // box the arguments into an Object[]
* t7:L=MethodHandleImpl.tryFinally(a1:L,a2:L,t6:L); // call the tryFinally executor
* t8:L=MethodHandle.invokeBasic(a4:L,t7:L);t8:L} // unbox the result; return the result
* }</pre></blockquote>
* <p>
* It is compiled into bytecode equivalent to the following code:
* <blockquote><pre>{@code
* Throwable t;
* Object r;
* try {
* r = a1.invokeBasic(a5);
* } catch (Throwable thrown) {
* t = thrown;
* throw t;
* } finally {
* r = a2.invokeBasic(t, r, a5);
* }
* return r;
* }</pre></blockquote>
* <p>
* Specifically, the bytecode will have the following form (the stack effects are given for the beginnings of
* blocks, and for the situations after executing the given instruction - the code will have a slightly different
* shape if the return type is {@code void}):
* <blockquote><pre>{@code
* TRY: (--)
* load target (-- target)
* load args (-- args... target)
* INVOKEVIRTUAL MethodHandle.invokeBasic (depends)
* FINALLY_NORMAL: (-- r_2nd* r)
* store returned value (--)
* load cleanup (-- cleanup)
* ACONST_NULL (-- t cleanup)
* load returned value (-- r_2nd* r t cleanup)
* load args (-- args... r_2nd* r t cleanup)
* INVOKEVIRTUAL MethodHandle.invokeBasic (-- r_2nd* r)
* GOTO DONE
* CATCH: (-- t)
* DUP (-- t t)
* FINALLY_EXCEPTIONAL: (-- t t)
* load cleanup (-- cleanup t t)
* SWAP (-- t cleanup t)
* load default for r (-- r_2nd* r t cleanup t)
* load args (-- args... r_2nd* r t cleanup t)
* INVOKEVIRTUAL MethodHandle.invokeBasic (-- r_2nd* r t)
* POP/POP2* (-- t)
* ATHROW
* DONE: (-- r)
* }</pre></blockquote>
* * = depends on whether the return type takes up 2 stack slots.
*/
private Name emitTryFinally(int pos) {
Name args = lambdaForm.names[pos];
Name invoker = lambdaForm.names[pos+1];
Name result = lambdaForm.names[pos+2];
Label lFrom = new Label();
Label lTo = new Label();
Label lCatch = new Label();
Label lDone = new Label();
Class<?> returnType = result.function.resolvedHandle().type().returnType();
BasicType basicReturnType = BasicType.basicType(returnType);
boolean isNonVoid = returnType != void.class;
MethodType type = args.function.resolvedHandle().type()
.dropParameterTypes(0,1)
.changeReturnType(returnType);
MethodType cleanupType = type.insertParameterTypes(0, Throwable.class);
if (isNonVoid) {
cleanupType = cleanupType.insertParameterTypes(1, returnType);
}
String cleanupDesc = cleanupType.basicType().toMethodDescriptorString();
// exception handler table
mv.visitTryCatchBlock(lFrom, lTo, lCatch, "java/lang/Throwable");
// TRY:
mv.visitLabel(lFrom);
emitPushArgument(invoker, 0); // load target
emitPushArguments(args, 1); // load args (skip 0: method handle)
mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, MH, "invokeBasic", type.basicType().toMethodDescriptorString(), false);
mv.visitLabel(lTo);
// FINALLY_NORMAL:
int index = extendLocalsMap(new Class<?>[]{ returnType });
if (isNonVoid) {
emitStoreInsn(basicReturnType, index);
}
emitPushArgument(invoker, 1); // load cleanup
mv.visitInsn(Opcodes.ACONST_NULL);
if (isNonVoid) {
emitLoadInsn(basicReturnType, index);
}
emitPushArguments(args, 1); // load args (skip 0: method handle)
mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, MH, "invokeBasic", cleanupDesc, false);
mv.visitJumpInsn(Opcodes.GOTO, lDone);
// CATCH:
mv.visitLabel(lCatch);
mv.visitInsn(Opcodes.DUP);
// FINALLY_EXCEPTIONAL:
emitPushArgument(invoker, 1); // load cleanup
mv.visitInsn(Opcodes.SWAP);
if (isNonVoid) {
emitZero(BasicType.basicType(returnType)); // load default for result
}
emitPushArguments(args, 1); // load args (skip 0: method handle)
mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, MH, "invokeBasic", cleanupDesc, false);
if (isNonVoid) {
emitPopInsn(basicReturnType);
}
mv.visitInsn(Opcodes.ATHROW);
// DONE:
mv.visitLabel(lDone);
return result;
}
private void emitPopInsn(BasicType type) {
mv.visitInsn(popInsnOpcode(type));
}
private static int popInsnOpcode(BasicType type) {
return switch (type) {
case I_TYPE, F_TYPE, L_TYPE -> Opcodes.POP;
case J_TYPE, D_TYPE -> Opcodes.POP2;
default -> throw new InternalError("unknown type: " + type);
};
}
private Name emitTableSwitch(int pos, int numCases) {
Name args = lambdaForm.names[pos];
Name invoker = lambdaForm.names[pos + 1];
Name result = lambdaForm.names[pos + 2];
Class<?> returnType = result.function.resolvedHandle().type().returnType();
MethodType caseType = args.function.resolvedHandle().type()
.dropParameterTypes(0, 1) // drop collector
.changeReturnType(returnType);
String caseDescriptor = caseType.basicType().toMethodDescriptorString();
emitPushArgument(invoker, 2); // push cases
mv.visitFieldInsn(Opcodes.GETFIELD, "java/lang/invoke/MethodHandleImpl$CasesHolder", "cases",
"[Ljava/lang/invoke/MethodHandle;");
int casesLocal = extendLocalsMap(new Class<?>[] { MethodHandle[].class });
emitStoreInsn(L_TYPE, casesLocal);
Label endLabel = new Label();
Label defaultLabel = new Label();
Label[] caseLabels = new Label[numCases];
for (int i = 0; i < caseLabels.length; i++) {
caseLabels[i] = new Label();
}
emitPushArgument(invoker, 0); // push switch input
mv.visitTableSwitchInsn(0, numCases - 1, defaultLabel, caseLabels);
mv.visitLabel(defaultLabel);
emitPushArgument(invoker, 1); // push default handle
emitPushArguments(args, 1); // again, skip collector
mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, MH, "invokeBasic", caseDescriptor, false);
mv.visitJumpInsn(Opcodes.GOTO, endLabel);
for (int i = 0; i < numCases; i++) {
mv.visitLabel(caseLabels[i]);
// Load the particular case:
emitLoadInsn(L_TYPE, casesLocal);
emitIconstInsn(i);
mv.visitInsn(Opcodes.AALOAD);
// invoke it:
emitPushArguments(args, 1); // again, skip collector
mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, MH, "invokeBasic", caseDescriptor, false);
mv.visitJumpInsn(Opcodes.GOTO, endLabel);
}
mv.visitLabel(endLabel);
return result;
}
/**
* Emit bytecode for the loop idiom.
* <p>
* The pattern looks like (Cf. MethodHandleImpl.loop):
* <blockquote><pre>{@code
* // a0: BMH
* // a1: LoopClauses (containing an array of arrays: inits, steps, preds, finis)
* // a2: box, a3: unbox
* // a4 (and following): arguments
* loop=Lambda(a0:L,a1:L,a2:L,a3:L,a4:L)=>{
* t5:L=MethodHandle.invokeBasic(a2:L,a4:L); // box the arguments into an Object[]
* t6:L=MethodHandleImpl.loop(bt:L,a1:L,t5:L); // call the loop executor (with supplied types in bt)
* t7:L=MethodHandle.invokeBasic(a3:L,t6:L);t7:L} // unbox the result; return the result
* }</pre></blockquote>
* <p>
* It is compiled into bytecode equivalent to the code seen in {@link MethodHandleImpl#loop(BasicType[],
* MethodHandleImpl.LoopClauses, Object...)}, with the difference that no arrays
* will be used for local state storage. Instead, the local state will be mapped to actual stack slots.
* <p>
* Bytecode generation applies an unrolling scheme to enable better bytecode generation regarding local state type
* handling. The generated bytecode will have the following form ({@code void} types are ignored for convenience).
* Assume there are {@code C} clauses in the loop.
* <blockquote><pre>{@code
* PREINIT: ALOAD_1
* CHECKCAST LoopClauses
* GETFIELD LoopClauses.clauses
* ASTORE clauseDataIndex // place the clauses 2-dimensional array on the stack
* INIT: (INIT_SEQ for clause 1)
* ...
* (INIT_SEQ for clause C)
* LOOP: (LOOP_SEQ for clause 1)
* ...
* (LOOP_SEQ for clause C)
* GOTO LOOP
* DONE: ...
* }</pre></blockquote>
* <p>
* The {@code INIT_SEQ_x} sequence for clause {@code x} (with {@code x} ranging from {@code 0} to {@code C-1}) has
* the following shape. Assume slot {@code vx} is used to hold the state for clause {@code x}.
* <blockquote><pre>{@code
* INIT_SEQ_x: ALOAD clauseDataIndex
* ICONST_0
* AALOAD // load the inits array
* ICONST x
* AALOAD // load the init handle for clause x
* load args
* INVOKEVIRTUAL MethodHandle.invokeBasic
* store vx
* }</pre></blockquote>
* <p>
* The {@code LOOP_SEQ_x} sequence for clause {@code x} (with {@code x} ranging from {@code 0} to {@code C-1}) has
* the following shape. Again, assume slot {@code vx} is used to hold the state for clause {@code x}.
* <blockquote><pre>{@code
* LOOP_SEQ_x: ALOAD clauseDataIndex
* ICONST_1
* AALOAD // load the steps array
* ICONST x
* AALOAD // load the step handle for clause x
* load locals
* load args
* INVOKEVIRTUAL MethodHandle.invokeBasic
* store vx
* ALOAD clauseDataIndex
* ICONST_2
* AALOAD // load the preds array
* ICONST x
* AALOAD // load the pred handle for clause x
* load locals
* load args
* INVOKEVIRTUAL MethodHandle.invokeBasic
* IFNE LOOP_SEQ_x+1 // predicate returned false -> jump to next clause
* ALOAD clauseDataIndex
* ICONST_3
* AALOAD // load the finis array
* ICONST x
* AALOAD // load the fini handle for clause x
* load locals
* load args
* INVOKEVIRTUAL MethodHandle.invokeBasic
* GOTO DONE // jump beyond end of clauses to return from loop
* }</pre></blockquote>
*/
private Name emitLoop(int pos) {
Name args = lambdaForm.names[pos];
Name invoker = lambdaForm.names[pos+1];
Name result = lambdaForm.names[pos+2];
// extract clause and loop-local state types
// find the type info in the loop invocation
BasicType[] loopClauseTypes = (BasicType[]) invoker.arguments[0];
Class<?>[] loopLocalStateTypes = Stream.of(loopClauseTypes).
filter(bt -> bt != BasicType.V_TYPE).map(BasicType::basicTypeClass).toArray(Class<?>[]::new);
Class<?>[] localTypes = new Class<?>[loopLocalStateTypes.length + 1];
localTypes[0] = MethodHandleImpl.LoopClauses.class;
System.arraycopy(loopLocalStateTypes, 0, localTypes, 1, loopLocalStateTypes.length);
final int clauseDataIndex = extendLocalsMap(localTypes);
final int firstLoopStateIndex = clauseDataIndex + 1;
Class<?> returnType = result.function.resolvedHandle().type().returnType();
MethodType loopType = args.function.resolvedHandle().type()
.dropParameterTypes(0,1)
.changeReturnType(returnType);
MethodType loopHandleType = loopType.insertParameterTypes(0, loopLocalStateTypes);
MethodType predType = loopHandleType.changeReturnType(boolean.class);
MethodType finiType = loopHandleType;
final int nClauses = loopClauseTypes.length;
// indices to invoker arguments to load method handle arrays
final int inits = 1;
final int steps = 2;
final int preds = 3;
final int finis = 4;
Label lLoop = new Label();
Label lDone = new Label();
Label lNext;
// PREINIT:
emitPushArgument(MethodHandleImpl.LoopClauses.class, invoker.arguments[1]);
mv.visitFieldInsn(Opcodes.GETFIELD, LOOP_CLAUSES, "clauses", MHARY2);
emitAstoreInsn(clauseDataIndex);
// INIT:
for (int c = 0, state = 0; c < nClauses; ++c) {
MethodType cInitType = loopType.changeReturnType(loopClauseTypes[c].basicTypeClass());
emitLoopHandleInvoke(invoker, inits, c, args, false, cInitType, loopLocalStateTypes, clauseDataIndex,
firstLoopStateIndex);
if (cInitType.returnType() != void.class) {
emitStoreInsn(BasicType.basicType(cInitType.returnType()), firstLoopStateIndex + state);
++state;
}
}
// LOOP:
mv.visitLabel(lLoop);
for (int c = 0, state = 0; c < nClauses; ++c) {
lNext = new Label();
MethodType stepType = loopHandleType.changeReturnType(loopClauseTypes[c].basicTypeClass());
boolean isVoid = stepType.returnType() == void.class;
// invoke loop step
emitLoopHandleInvoke(invoker, steps, c, args, true, stepType, loopLocalStateTypes, clauseDataIndex,
firstLoopStateIndex);
if (!isVoid) {
emitStoreInsn(BasicType.basicType(stepType.returnType()), firstLoopStateIndex + state);
++state;
}
// invoke loop predicate
emitLoopHandleInvoke(invoker, preds, c, args, true, predType, loopLocalStateTypes, clauseDataIndex,
firstLoopStateIndex);
mv.visitJumpInsn(Opcodes.IFNE, lNext);
// invoke fini
emitLoopHandleInvoke(invoker, finis, c, args, true, finiType, loopLocalStateTypes, clauseDataIndex,
firstLoopStateIndex);
mv.visitJumpInsn(Opcodes.GOTO, lDone);
// this is the beginning of the next loop clause
mv.visitLabel(lNext);
}
mv.visitJumpInsn(Opcodes.GOTO, lLoop);
// DONE:
mv.visitLabel(lDone);
return result;
}
private int extendLocalsMap(Class<?>[] types) {
int firstSlot = localsMap.length - 1;
localsMap = Arrays.copyOf(localsMap, localsMap.length + types.length);
localClasses = Arrays.copyOf(localClasses, localClasses.length + types.length);
System.arraycopy(types, 0, localClasses, firstSlot, types.length);
int index = localsMap[firstSlot - 1] + 1;
int lastSlots = 0;
for (int i = 0; i < types.length; ++i) {
localsMap[firstSlot + i] = index;
lastSlots = BasicType.basicType(localClasses[firstSlot + i]).basicTypeSlots();
index += lastSlots;
}
localsMap[localsMap.length - 1] = index - lastSlots;
return firstSlot;
}
private void emitLoopHandleInvoke(Name holder, int handles, int clause, Name args, boolean pushLocalState,
MethodType type, Class<?>[] loopLocalStateTypes, int clauseDataSlot,
int firstLoopStateSlot) {
// load handle for clause
emitPushClauseArray(clauseDataSlot, handles);
emitIconstInsn(clause);
mv.visitInsn(Opcodes.AALOAD);
// load loop state (preceding the other arguments)
if (pushLocalState) {
for (int s = 0; s < loopLocalStateTypes.length; ++s) {
emitLoadInsn(BasicType.basicType(loopLocalStateTypes[s]), firstLoopStateSlot + s);
}
}
// load loop args (skip 0: method handle)
emitPushArguments(args, 1);
mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, MH, "invokeBasic", type.toMethodDescriptorString(), false);
}
private void emitPushClauseArray(int clauseDataSlot, int which) {
emitAloadInsn(clauseDataSlot);
emitIconstInsn(which - 1);
mv.visitInsn(Opcodes.AALOAD);
}
private void emitZero(BasicType type) {
mv.visitInsn(switch (type) {
case I_TYPE -> Opcodes.ICONST_0;
case J_TYPE -> Opcodes.LCONST_0;
case F_TYPE -> Opcodes.FCONST_0;
case D_TYPE -> Opcodes.DCONST_0;
case L_TYPE -> Opcodes.ACONST_NULL;
default -> throw new InternalError("unknown type: " + type);
});
}
private void emitPushArguments(Name args, int start) {
MethodType type = args.function.methodType();
for (int i = start; i < args.arguments.length; i++) {
emitPushArgument(type.parameterType(i), args.arguments[i]);
}
}
private void emitPushArgument(Name name, int paramIndex) {
Object arg = name.arguments[paramIndex];
Class<?> ptype = name.function.methodType().parameterType(paramIndex);
emitPushArgument(ptype, arg);
}
private void emitPushArgument(Class<?> ptype, Object arg) {
BasicType bptype = basicType(ptype);
if (arg instanceof Name n) {
emitLoadInsn(n.type, n.index());
emitImplicitConversion(n.type, ptype, n);
} else if (arg == null && bptype == L_TYPE) {
mv.visitInsn(Opcodes.ACONST_NULL);
} else if (arg instanceof String && bptype == L_TYPE) {
mv.visitLdcInsn(arg);
} else {
if (Wrapper.isWrapperType(arg.getClass()) && bptype != L_TYPE) {
emitConst(arg);
} else {
mv.visitFieldInsn(Opcodes.GETSTATIC, className, classData(arg), "Ljava/lang/Object;");
emitImplicitConversion(L_TYPE, ptype, arg);
}
}
}
/**
* Store the name to its local, if necessary.
*/
private void emitStoreResult(Name name) {
if (name != null && name.type != V_TYPE) {
// non-void: actually assign
emitStoreInsn(name.type, name.index());
}
}
/**
* Emits a return statement from a LF invoker. If required, the result type is cast to the correct return type.
*/
private void emitReturn(Name onStack) {
// return statement
Class<?> rclass = invokerType.returnType();
BasicType rtype = lambdaForm.returnType();
assert(rtype == basicType(rclass)); // must agree
if (rtype == V_TYPE) {
// void
mv.visitInsn(Opcodes.RETURN);
// it doesn't matter what rclass is; the JVM will discard any value
} else {
LambdaForm.Name rn = lambdaForm.names[lambdaForm.result];
// put return value on the stack if it is not already there
if (rn != onStack) {
emitLoadInsn(rtype, lambdaForm.result);
}
emitImplicitConversion(rtype, rclass, rn);
// generate actual return statement
emitReturnInsn(rtype);
}
}
/**
* Emit a type conversion bytecode casting from "from" to "to".
*/
private void emitPrimCast(Wrapper from, Wrapper to) {
// Here's how.
// - indicates forbidden
// <-> indicates implicit
// to ----> boolean byte short char int long float double
// from boolean <-> - - - - - - -
// byte - <-> i2s i2c <-> i2l i2f i2d
// short - i2b <-> i2c <-> i2l i2f i2d
// char - i2b i2s <-> <-> i2l i2f i2d
// int - i2b i2s i2c <-> i2l i2f i2d
// long - l2i,i2b l2i,i2s l2i,i2c l2i <-> l2f l2d
// float - f2i,i2b f2i,i2s f2i,i2c f2i f2l <-> f2d
// double - d2i,i2b d2i,i2s d2i,i2c d2i d2l d2f <->
if (from == to) {
// no cast required, should be dead code anyway
return;
}
if (from.isSubwordOrInt()) {
// cast from {byte,short,char,int} to anything
emitI2X(to);
} else {
// cast from {long,float,double} to anything
if (to.isSubwordOrInt()) {
// cast to {byte,short,char,int}
emitX2I(from);
if (to.bitWidth() < 32) {
// targets other than int require another conversion
emitI2X(to);
}
} else {
// cast to {long,float,double} - this is verbose
boolean error = false;
switch (from) {
case LONG -> {
switch (to) {
case FLOAT -> mv.visitInsn(Opcodes.L2F);
case DOUBLE -> mv.visitInsn(Opcodes.L2D);
default -> error = true;
}
}
case FLOAT -> {
switch (to) {
case LONG -> mv.visitInsn(Opcodes.F2L);
case DOUBLE -> mv.visitInsn(Opcodes.F2D);
default -> error = true;
}
}
case DOUBLE -> {
switch (to) {
case LONG -> mv.visitInsn(Opcodes.D2L);
case FLOAT -> mv.visitInsn(Opcodes.D2F);
default -> error = true;
}
}
default -> error = true;
}
if (error) {
throw new IllegalStateException("unhandled prim cast: " + from + "2" + to);
}
}
}
}
private void emitI2X(Wrapper type) {
switch (type) {
case BYTE: mv.visitInsn(Opcodes.I2B); break;
case SHORT: mv.visitInsn(Opcodes.I2S); break;
case CHAR: mv.visitInsn(Opcodes.I2C); break;
case INT: /* naught */ break;
case LONG: mv.visitInsn(Opcodes.I2L); break;
case FLOAT: mv.visitInsn(Opcodes.I2F); break;
case DOUBLE: mv.visitInsn(Opcodes.I2D); break;
case BOOLEAN:
// For compatibility with ValueConversions and explicitCastArguments:
mv.visitInsn(Opcodes.ICONST_1);
mv.visitInsn(Opcodes.IAND);
break;
default: throw new InternalError("unknown type: " + type);
}
}
private void emitX2I(Wrapper type) {
switch (type) {
case LONG -> mv.visitInsn(Opcodes.L2I);
case FLOAT -> mv.visitInsn(Opcodes.F2I);
case DOUBLE -> mv.visitInsn(Opcodes.D2I);
default -> throw new InternalError("unknown type: " + type);
}
}
/**
* Generate bytecode for a LambdaForm.vmentry which calls interpretWithArguments.
*/
static MemberName generateLambdaFormInterpreterEntryPoint(MethodType mt) {
assert(isValidSignature(basicTypeSignature(mt)));
String name = "interpret_"+basicTypeChar(mt.returnType());
MethodType type = mt; // includes leading argument
type = type.changeParameterType(0, MethodHandle.class);
InvokerBytecodeGenerator g = new InvokerBytecodeGenerator("LFI", name, type);
return g.loadMethod(g.generateLambdaFormInterpreterEntryPointBytes());
}
private byte[] generateLambdaFormInterpreterEntryPointBytes() {
classFilePrologue();
methodPrologue();
// Suppress this method in backtraces displayed to the user.
mv.visitAnnotation(HIDDEN_SIG, true);
// Don't inline the interpreter entry.
mv.visitAnnotation(DONTINLINE_SIG, true);
// create parameter array
emitIconstInsn(invokerType.parameterCount());
mv.visitTypeInsn(Opcodes.ANEWARRAY, "java/lang/Object");
// fill parameter array
for (int i = 0; i < invokerType.parameterCount(); i++) {
Class<?> ptype = invokerType.parameterType(i);
mv.visitInsn(Opcodes.DUP);
emitIconstInsn(i);
emitLoadInsn(basicType(ptype), i);
// box if primitive type
if (ptype.isPrimitive()) {
emitBoxing(Wrapper.forPrimitiveType(ptype));
}
mv.visitInsn(Opcodes.AASTORE);
}
// invoke
emitAloadInsn(0);
mv.visitFieldInsn(Opcodes.GETFIELD, MH, "form", "Ljava/lang/invoke/LambdaForm;");
mv.visitInsn(Opcodes.SWAP); // swap form and array; avoid local variable
mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, LF, "interpretWithArguments", "([Ljava/lang/Object;)Ljava/lang/Object;", false);
// maybe unbox
Class<?> rtype = invokerType.returnType();
if (rtype.isPrimitive() && rtype != void.class) {
emitUnboxing(Wrapper.forPrimitiveType(rtype));
}
// return statement
emitReturnInsn(basicType(rtype));
methodEpilogue();
clinit(cw, className, classData);
bogusMethod(invokerType);
final byte[] classFile = cw.toByteArray();
maybeDump(classFile);
return classFile;
}
/**
* Generate bytecode for a NamedFunction invoker.
*/
static MemberName generateNamedFunctionInvoker(MethodTypeForm typeForm) {
MethodType invokerType = NamedFunction.INVOKER_METHOD_TYPE;
String invokerName = "invoke_" + shortenSignature(basicTypeSignature(typeForm.erasedType()));
InvokerBytecodeGenerator g = new InvokerBytecodeGenerator("NFI", invokerName, invokerType);
return g.loadMethod(g.generateNamedFunctionInvokerImpl(typeForm));
}
private byte[] generateNamedFunctionInvokerImpl(MethodTypeForm typeForm) {
MethodType dstType = typeForm.erasedType();
classFilePrologue();
methodPrologue();
// Suppress this method in backtraces displayed to the user.
mv.visitAnnotation(HIDDEN_SIG, true);
// Force inlining of this invoker method.
mv.visitAnnotation(FORCEINLINE_SIG, true);
// Load receiver
emitAloadInsn(0);
// Load arguments from array
for (int i = 0; i < dstType.parameterCount(); i++) {
emitAloadInsn(1);
emitIconstInsn(i);
mv.visitInsn(Opcodes.AALOAD);
// Maybe unbox
Class<?> dptype = dstType.parameterType(i);
if (dptype.isPrimitive()) {
Wrapper dstWrapper = Wrapper.forBasicType(dptype);
Wrapper srcWrapper = dstWrapper.isSubwordOrInt() ? Wrapper.INT : dstWrapper; // narrow subword from int
emitUnboxing(srcWrapper);
emitPrimCast(srcWrapper, dstWrapper);
}
}
// Invoke
String targetDesc = dstType.basicType().toMethodDescriptorString();
mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, MH, "invokeBasic", targetDesc, false);
// Box primitive types
Class<?> rtype = dstType.returnType();
if (rtype != void.class && rtype.isPrimitive()) {
Wrapper srcWrapper = Wrapper.forBasicType(rtype);
Wrapper dstWrapper = srcWrapper.isSubwordOrInt() ? Wrapper.INT : srcWrapper; // widen subword to int
// boolean casts not allowed
emitPrimCast(srcWrapper, dstWrapper);
emitBoxing(dstWrapper);
}
// If the return type is void we return a null reference.
if (rtype == void.class) {
mv.visitInsn(Opcodes.ACONST_NULL);
}
emitReturnInsn(L_TYPE); // NOTE: NamedFunction invokers always return a reference value.
methodEpilogue();
clinit(cw, className, classData);
bogusMethod(dstType);
final byte[] classFile = cw.toByteArray();
maybeDump(classFile);
return classFile;
}
/**
* Emit a bogus method that just loads some string constants. This is to get the constants into the constant pool
* for debugging purposes.
*/
private void bogusMethod(Object os) {
if (DUMP_CLASS_FILES) {
mv = cw.visitMethod(Opcodes.ACC_STATIC, "dummy", "()V", null, null);
mv.visitLdcInsn(os.toString());
mv.visitInsn(Opcodes.POP);
mv.visitInsn(Opcodes.RETURN);
mv.visitMaxs(0, 0);
mv.visitEnd();
}
}
}
⏎ java/lang/invoke/InvokerBytecodeGenerator.java
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