The InvokerBytecodeGenerator.java Java example source code
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* particular file as subject to the "Classpath" exception as provided
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*
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
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package java.lang.invoke;
import sun.invoke.util.VerifyAccess;
import java.lang.invoke.LambdaForm.Name;
import java.lang.invoke.MethodHandles.Lookup;
import sun.invoke.util.Wrapper;
import java.io.*;
import java.util.*;
import jdk.internal.org.objectweb.asm.*;
import java.lang.reflect.*;
import static java.lang.invoke.MethodHandleStatics.*;
import static java.lang.invoke.MethodHandleNatives.Constants.*;
import static java.lang.invoke.MethodHandles.Lookup.IMPL_LOOKUP;
import sun.invoke.util.ValueConversions;
import sun.invoke.util.VerifyType;
/**
* 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 BMH = "java/lang/invoke/BoundMethodHandle";
private static final String LF = "java/lang/invoke/LambdaForm";
private static final String LFN = "java/lang/invoke/LambdaForm$Name";
private static final String CLS = "java/lang/Class";
private static final String OBJ = "java/lang/Object";
private static final String OBJARY = "[Ljava/lang/Object;";
private static final String LF_SIG = "L" + LF + ";";
private static final String LFN_SIG = "L" + LFN + ";";
private static final String LL_SIG = "(L" + OBJ + ";)L" + OBJ + ";";
/** Name of its super class*/
private static final String superName = LF;
/** Name of new class */
private final String className;
/** Name of the source file (for stack trace printing). */
private final String sourceFile;
private final LambdaForm lambdaForm;
private final String invokerName;
private final MethodType invokerType;
private final int[] localsMap;
/** ASM bytecode generation. */
private ClassWriter cw;
private MethodVisitor mv;
private static final MemberName.Factory MEMBERNAME_FACTORY = MemberName.getFactory();
private static final Class<?> HOST_CLASS = LambdaForm.class;
private InvokerBytecodeGenerator(LambdaForm lambdaForm, int localsMapSize,
String className, String invokerName, MethodType invokerType) {
if (invokerName.contains(".")) {
int p = invokerName.indexOf(".");
className = invokerName.substring(0, p);
invokerName = invokerName.substring(p+1);
}
if (DUMP_CLASS_FILES) {
className = makeDumpableClassName(className);
}
this.className = superName + "$" + className;
this.sourceFile = "LambdaForm$" + className;
this.lambdaForm = lambdaForm;
this.invokerName = invokerName;
this.invokerType = invokerType;
this.localsMap = new int[localsMapSize];
}
private InvokerBytecodeGenerator(String className, String invokerName, MethodType invokerType) {
this(null, invokerType.parameterCount(),
className, invokerName, invokerType);
// Create an array to map name indexes to locals indexes.
for (int i = 0; i < localsMap.length; i++) {
localsMap[i] = invokerType.parameterSlotCount() - invokerType.parameterSlotDepth(i);
}
}
private InvokerBytecodeGenerator(String className, LambdaForm form, MethodType invokerType) {
this(form, form.names.length,
className, form.debugName, 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;
index += Wrapper.forBasicType(names[i].type).stackSlots();
}
}
/** instance counters for dumped classes */
private final static HashMap<String,Integer> DUMP_CLASS_FILES_COUNTERS;
/** debugging flag for saving generated class files */
private final static 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;
}
}
static void maybeDump(final String className, final byte[] classFile) {
if (DUMP_CLASS_FILES) {
System.out.println("dump: " + className);
java.security.AccessController.doPrivileged(
new java.security.PrivilegedAction<Void>() {
public Void run() {
try {
String dumpName = className;
//dumpName = dumpName.replace('/', '-');
File dumpFile = new File(DUMP_CLASS_FILES_DIR, dumpName+".class");
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;
}
class CpPatch {
final int index;
final String placeholder;
final Object value;
CpPatch(int index, String placeholder, Object value) {
this.index = index;
this.placeholder = placeholder;
this.value = value;
}
public String toString() {
return "CpPatch/index="+index+",placeholder="+placeholder+",value="+value;
}
}
Map<Object, CpPatch> cpPatches = new HashMap<>();
int cph = 0; // for counting constant placeholders
String constantPlaceholder(Object arg) {
String cpPlaceholder = "CONSTANT_PLACEHOLDER_" + cph++;
if (DUMP_CLASS_FILES) cpPlaceholder += " <<" + arg.toString() + ">>"; // debugging aid
if (cpPatches.containsKey(cpPlaceholder)) {
throw new InternalError("observed CP placeholder twice: " + cpPlaceholder);
}
// insert placeholder in CP and remember the patch
int index = cw.newConst((Object) cpPlaceholder); // TODO check if aready in the constant pool
cpPatches.put(cpPlaceholder, new CpPatch(index, cpPlaceholder, arg));
return cpPlaceholder;
}
Object[] cpPatches(byte[] classFile) {
int size = getConstantPoolSize(classFile);
Object[] res = new Object[size];
for (CpPatch p : cpPatches.values()) {
if (p.index >= size)
throw new InternalError("in cpool["+size+"]: "+p+"\n"+Arrays.toString(Arrays.copyOf(classFile, 20)));
res[p.index] = p.value;
}
return res;
}
/**
* Extract the number of constant pool entries from a given class file.
*
* @param classFile the bytes of the class file in question.
* @return the number of entries in the constant pool.
*/
private static int getConstantPoolSize(byte[] classFile) {
// The first few bytes:
// u4 magic;
// u2 minor_version;
// u2 major_version;
// u2 constant_pool_count;
return ((classFile[8] & 0xFF) << 8) | (classFile[9] & 0xFF);
}
/**
* Extract the MemberName of a newly-defined method.
*/
private MemberName loadMethod(byte[] classFile) {
Class<?> invokerClass = loadAndInitializeInvokerClass(classFile, cpPatches(classFile));
return resolveInvokerMember(invokerClass, invokerName, invokerType);
}
/**
* Define a given class as anonymous class in the runtime system.
*/
private static Class<?> loadAndInitializeInvokerClass(byte[] classBytes, Object[] patches) {
Class<?> invokerClass = UNSAFE.defineAnonymousClass(HOST_CLASS, classBytes, patches);
UNSAFE.ensureClassInitialized(invokerClass); // Make sure the class is initialized; VM might complain.
return invokerClass;
}
private static MemberName resolveInvokerMember(Class<?> invokerClass, String name, MethodType type) {
MemberName member = new MemberName(invokerClass, name, type, REF_invokeStatic);
//System.out.println("resolveInvokerMember => "+member);
//for (Method m : invokerClass.getDeclaredMethods()) System.out.println(" "+m);
try {
member = MEMBERNAME_FACTORY.resolveOrFail(REF_invokeStatic, member, HOST_CLASS, ReflectiveOperationException.class);
} catch (ReflectiveOperationException e) {
throw newInternalError(e);
}
//System.out.println("resolveInvokerMember => "+member);
return member;
}
/**
* Set up class file generation.
*/
private void classFilePrologue() {
cw = new ClassWriter(ClassWriter.COMPUTE_MAXS + ClassWriter.COMPUTE_FRAMES);
cw.visit(Opcodes.V1_8, Opcodes.ACC_PUBLIC + Opcodes.ACC_FINAL + Opcodes.ACC_SUPER, className, null, superName, null);
cw.visitSource(sourceFile, null);
String invokerDesc = invokerType.toMethodDescriptorString();
mv = cw.visitMethod(Opcodes.ACC_STATIC, invokerName, invokerDesc, null, null);
}
/**
* Tear down class file generation.
*/
private void classFileEpilogue() {
mv.visitMaxs(0, 0);
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 Long) {
long x = (long) con;
if (x == (short) x) {
emitIconstInsn((int) x);
mv.visitInsn(Opcodes.I2L);
return;
}
}
if (con instanceof Float) {
float x = (float) con;
if (x == (short) x) {
emitIconstInsn((int) x);
mv.visitInsn(Opcodes.I2F);
return;
}
}
if (con instanceof Double) {
double x = (double) con;
if (x == (short) x) {
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(int i) {
int opcode;
switch (i) {
case 0: opcode = Opcodes.ICONST_0; break;
case 1: opcode = Opcodes.ICONST_1; break;
case 2: opcode = Opcodes.ICONST_2; break;
case 3: opcode = Opcodes.ICONST_3; break;
case 4: opcode = Opcodes.ICONST_4; break;
case 5: opcode = Opcodes.ICONST_5; break;
default:
if (i == (byte) i) {
mv.visitIntInsn(Opcodes.BIPUSH, i & 0xFF);
} else if (i == (short) i) {
mv.visitIntInsn(Opcodes.SIPUSH, (char) i);
} else {
mv.visitLdcInsn(i);
}
return;
}
mv.visitInsn(opcode);
}
/*
* NOTE: These load/store methods use the localsMap to find the correct index!
*/
private void emitLoadInsn(char type, int index) {
int opcode;
switch (type) {
case 'I': opcode = Opcodes.ILOAD; break;
case 'J': opcode = Opcodes.LLOAD; break;
case 'F': opcode = Opcodes.FLOAD; break;
case 'D': opcode = Opcodes.DLOAD; break;
case 'L': opcode = Opcodes.ALOAD; break;
default:
throw new InternalError("unknown type: " + type);
}
mv.visitVarInsn(opcode, localsMap[index]);
}
private void emitAloadInsn(int index) {
emitLoadInsn('L', index);
}
private void emitStoreInsn(char type, int index) {
int opcode;
switch (type) {
case 'I': opcode = Opcodes.ISTORE; break;
case 'J': opcode = Opcodes.LSTORE; break;
case 'F': opcode = Opcodes.FSTORE; break;
case 'D': opcode = Opcodes.DSTORE; break;
case 'L': opcode = Opcodes.ASTORE; break;
default:
throw new InternalError("unknown type: " + type);
}
mv.visitVarInsn(opcode, localsMap[index]);
}
private void emitAstoreInsn(int index) {
emitStoreInsn('L', index);
}
/**
* Emit a boxing call.
*
* @param type primitive type class to box.
*/
private void emitBoxing(Class<?> type) {
Wrapper wrapper = Wrapper.forPrimitiveType(type);
String owner = "java/lang/" + wrapper.wrapperType().getSimpleName();
String name = "valueOf";
String desc = "(" + wrapper.basicTypeChar() + ")L" + owner + ";";
mv.visitMethodInsn(Opcodes.INVOKESTATIC, owner, name, desc);
}
/**
* Emit an unboxing call (plus preceding checkcast).
*
* @param type wrapper type class to unbox.
*/
private void emitUnboxing(Class<?> type) {
Wrapper wrapper = Wrapper.forWrapperType(type);
String owner = "java/lang/" + wrapper.wrapperType().getSimpleName();
String name = wrapper.primitiveSimpleName() + "Value";
String desc = "()" + wrapper.basicTypeChar();
mv.visitTypeInsn(Opcodes.CHECKCAST, owner);
mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, owner, name, desc);
}
/**
* Emit an implicit conversion.
*
* @param ptype type of value present on stack
* @param pclass type of value required on stack
*/
private void emitImplicitConversion(char ptype, Class<?> pclass) {
switch (ptype) {
case 'L':
if (VerifyType.isNullConversion(Object.class, pclass))
return;
if (isStaticallyNameable(pclass)) {
mv.visitTypeInsn(Opcodes.CHECKCAST, getInternalName(pclass));
} else {
mv.visitLdcInsn(constantPlaceholder(pclass));
mv.visitTypeInsn(Opcodes.CHECKCAST, CLS);
mv.visitInsn(Opcodes.SWAP);
mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, CLS, "cast", LL_SIG);
if (pclass.isArray())
mv.visitTypeInsn(Opcodes.CHECKCAST, OBJARY);
}
return;
case 'I':
if (!VerifyType.isNullConversion(int.class, pclass))
emitPrimCast(ptype, Wrapper.basicTypeChar(pclass));
return;
case 'J':
assert(pclass == long.class);
return;
case 'F':
assert(pclass == float.class);
return;
case 'D':
assert(pclass == double.class);
return;
}
throw new InternalError("bad implicit conversion: tc="+ptype+": "+pclass);
}
/**
* Emits an actual return instruction conforming to the given return type.
*/
private void emitReturnInsn(Class<?> type) {
int opcode;
switch (Wrapper.basicTypeChar(type)) {
case 'I': opcode = Opcodes.IRETURN; break;
case 'J': opcode = Opcodes.LRETURN; break;
case 'F': opcode = Opcodes.FRETURN; break;
case 'D': opcode = Opcodes.DRETURN; break;
case 'L': opcode = Opcodes.ARETURN; break;
case 'V': opcode = Opcodes.RETURN; break;
default:
throw new InternalError("unknown return type: " + type);
}
mv.visitInsn(opcode);
}
private static String getInternalName(Class<?> c) {
assert(VerifyAccess.isTypeVisible(c, Object.class));
return c.getName().replace('.', '/');
}
/**
* Generate customized bytecode for a given LambdaForm.
*/
static MemberName generateCustomizedCode(LambdaForm form, MethodType invokerType) {
InvokerBytecodeGenerator g = new InvokerBytecodeGenerator("MH", form, invokerType);
return g.loadMethod(g.generateCustomizedCodeBytes());
}
/**
* Generate an invoker method for the passed {@link LambdaForm}.
*/
private byte[] generateCustomizedCodeBytes() {
classFilePrologue();
// Suppress this method in backtraces displayed to the user.
mv.visitAnnotation("Ljava/lang/invoke/LambdaForm$Hidden;", true);
// Mark this method as a compiled LambdaForm
mv.visitAnnotation("Ljava/lang/invoke/LambdaForm$Compiled;", true);
// Force inlining of this invoker method.
mv.visitAnnotation("Ljava/lang/invoke/ForceInline;", true);
// iterate over the form's names, generating bytecode instructions for each
// start iterating at the first name following the arguments
for (int i = lambdaForm.arity; i < lambdaForm.names.length; i++) {
Name name = lambdaForm.names[i];
MemberName member = name.function.member();
if (isSelectAlternative(member)) {
// selectAlternative idiom
// FIXME: make sure this idiom is really present!
emitSelectAlternative(name, lambdaForm.names[i + 1]);
i++; // skip MH.invokeBasic of the selectAlternative result
} else if (isStaticallyInvocable(member)) {
emitStaticInvoke(member, name);
} else {
emitInvoke(name);
}
// store the result from evaluating to the target name in a local if required
// (if this is the last value, i.e., the one that is going to be returned,
// avoid store/load/return and just return)
if (i == lambdaForm.names.length - 1 && i == lambdaForm.result) {
// return value - do nothing
} else if (name.type != 'V') {
// non-void: actually assign
emitStoreInsn(name.type, name.index());
}
}
// return statement
emitReturn();
classFileEpilogue();
bogusMethod(lambdaForm);
final byte[] classFile = cw.toByteArray();
maybeDump(className, classFile);
return classFile;
}
/**
* Emit an invoke for the given name.
*/
void emitInvoke(Name name) {
if (true) {
// push receiver
MethodHandle target = name.function.resolvedHandle;
assert(target != null) : name.exprString();
mv.visitLdcInsn(constantPlaceholder(target));
mv.visitTypeInsn(Opcodes.CHECKCAST, MH);
} else {
// load receiver
emitAloadInsn(0);
mv.visitTypeInsn(Opcodes.CHECKCAST, MH);
mv.visitFieldInsn(Opcodes.GETFIELD, MH, "form", LF_SIG);
mv.visitFieldInsn(Opcodes.GETFIELD, LF, "names", LFN_SIG);
// TODO more to come
}
// push arguments
for (int i = 0; i < name.arguments.length; i++) {
emitPushArgument(name, i);
}
// invocation
MethodType type = name.function.methodType();
mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, MH, "invokeBasic", type.basicType().toMethodDescriptorString());
}
static private Class<?>[] STATICALLY_INVOCABLE_PACKAGES = {
// Sample classes from each package we are willing to bind to statically:
java.lang.Object.class,
java.util.Arrays.class,
sun.misc.Unsafe.class
//MethodHandle.class already covered
};
static boolean isStaticallyInvocable(MemberName member) {
if (member == null) return false;
if (member.isConstructor()) return false;
Class<?> cls = member.getDeclaringClass();
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
MethodType mtype = member.getMethodOrFieldType();
if (!isStaticallyNameable(mtype.returnType()))
return false;
for (Class<?> ptype : mtype.parameterArray())
if (!isStaticallyNameable(ptype))
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;
}
static boolean isStaticallyNameable(Class<?> cls) {
while (cls.isArray())
cls = cls.getComponentType();
if (cls.isPrimitive())
return true; // int[].class, for example
// 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;
}
/**
* Emit an invoke for the given name, using the MemberName directly.
*/
void emitStaticInvoke(MemberName member, Name name) {
assert(member.equals(name.function.member()));
String cname = getInternalName(member.getDeclaringClass());
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;
}
if (member.getDeclaringClass().isInterface() && refKind == REF_invokeVirtual) {
// Methods from Object declared in an interface can be resolved by JVM to invokevirtual kind.
// Need to convert it back to invokeinterface to pass verification and make the invocation works as expected.
refKind = REF_invokeInterface;
}
// push arguments
for (int i = 0; i < name.arguments.length; i++) {
emitPushArgument(name, i);
}
// 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);
}
}
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);
}
/**
* Check if MemberName is a call to MethodHandleImpl.selectAlternative.
*/
private boolean isSelectAlternative(MemberName member) {
return member != null &&
member.getDeclaringClass() == MethodHandleImpl.class &&
member.getName().equals("selectAlternative");
}
/**
* Emit bytecode for the selectAlternative idiom.
*
* The pattern looks like (Cf. MethodHandleImpl.makeGuardWithTest):
* <blockquote>{@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>
*/
private void emitSelectAlternative(Name selectAlternativeName, Name invokeBasicName) {
MethodType type = selectAlternativeName.function.methodType();
Name receiver = (Name) invokeBasicName.arguments[0];
Label L_fallback = new Label();
Label L_done = new Label();
// load test result
emitPushArgument(selectAlternativeName, 0);
mv.visitInsn(Opcodes.ICONST_1);
// if_icmpne L_fallback
mv.visitJumpInsn(Opcodes.IF_ICMPNE, L_fallback);
// invoke selectAlternativeName.arguments[1]
MethodHandle target = (MethodHandle) selectAlternativeName.arguments[1];
emitPushArgument(selectAlternativeName, 1); // get 2nd argument of selectAlternative
emitAstoreInsn(receiver.index()); // store the MH in the receiver slot
emitInvoke(invokeBasicName);
// goto L_done
mv.visitJumpInsn(Opcodes.GOTO, L_done);
// L_fallback:
mv.visitLabel(L_fallback);
// invoke selectAlternativeName.arguments[2]
MethodHandle fallback = (MethodHandle) selectAlternativeName.arguments[2];
emitPushArgument(selectAlternativeName, 2); // get 3rd argument of selectAlternative
emitAstoreInsn(receiver.index()); // store the MH in the receiver slot
emitInvoke(invokeBasicName);
// L_done:
mv.visitLabel(L_done);
}
private void emitPushArgument(Name name, int paramIndex) {
Object arg = name.arguments[paramIndex];
char ptype = name.function.parameterType(paramIndex);
MethodType mtype = name.function.methodType();
if (arg instanceof Name) {
Name n = (Name) arg;
emitLoadInsn(n.type, n.index());
emitImplicitConversion(n.type, mtype.parameterType(paramIndex));
} else if ((arg == null || arg instanceof String) && ptype == 'L') {
emitConst(arg);
} else {
if (Wrapper.isWrapperType(arg.getClass()) && ptype != 'L') {
emitConst(arg);
} else {
mv.visitLdcInsn(constantPlaceholder(arg));
emitImplicitConversion('L', mtype.parameterType(paramIndex));
}
}
}
/**
* Emits a return statement from a LF invoker. If required, the result type is cast to the correct return type.
*/
private void emitReturn() {
// return statement
if (lambdaForm.result == -1) {
// void
mv.visitInsn(Opcodes.RETURN);
} else {
LambdaForm.Name rn = lambdaForm.names[lambdaForm.result];
char rtype = Wrapper.basicTypeChar(invokerType.returnType());
// put return value on the stack if it is not already there
if (lambdaForm.result != lambdaForm.names.length - 1) {
emitLoadInsn(rn.type, lambdaForm.result);
}
// potentially generate cast
// rtype is the return type of the invoker - generated code must conform to this
// rn.type is the type of the result Name in the LF
if (rtype != rn.type) {
// need cast
if (rtype == 'L') {
// possibly cast the primitive to the correct type for boxing
char boxedType = Wrapper.forWrapperType(invokerType.returnType()).basicTypeChar();
if (boxedType != rn.type) {
emitPrimCast(rn.type, boxedType);
}
// cast primitive to reference ("boxing")
emitBoxing(invokerType.returnType());
} else {
// to-primitive cast
if (rn.type != 'L') {
// prim-to-prim cast
emitPrimCast(rn.type, rtype);
} else {
// ref-to-prim cast ("unboxing")
throw new InternalError("no ref-to-prim (unboxing) casts supported right now");
}
}
}
// generate actual return statement
emitReturnInsn(invokerType.returnType());
}
}
/**
* Emit a type conversion bytecode casting from "from" to "to".
*/
private void emitPrimCast(char from, char 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;
}
Wrapper wfrom = Wrapper.forBasicType(from);
Wrapper wto = Wrapper.forBasicType(to);
if (wfrom.isSubwordOrInt()) {
// cast from {byte,short,char,int} to anything
emitI2X(to);
} else {
// cast from {long,float,double} to anything
if (wto.isSubwordOrInt()) {
// cast to {byte,short,char,int}
emitX2I(from);
if (wto.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 'J':
if (to == 'F') { mv.visitInsn(Opcodes.L2F); }
else if (to == 'D') { mv.visitInsn(Opcodes.L2D); }
else error = true;
break;
case 'F':
if (to == 'J') { mv.visitInsn(Opcodes.F2L); }
else if (to == 'D') { mv.visitInsn(Opcodes.F2D); }
else error = true;
break;
case 'D':
if (to == 'J') { mv.visitInsn(Opcodes.D2L); }
else if (to == 'F') { mv.visitInsn(Opcodes.D2F); }
else error = true;
break;
default:
error = true;
break;
}
if (error) {
throw new IllegalStateException("unhandled prim cast: " + from + "2" + to);
}
}
}
}
private void emitI2X(char type) {
switch (type) {
case 'B': mv.visitInsn(Opcodes.I2B); break;
case 'S': mv.visitInsn(Opcodes.I2S); break;
case 'C': mv.visitInsn(Opcodes.I2C); break;
case 'I': /* naught */ break;
case 'J': mv.visitInsn(Opcodes.I2L); break;
case 'F': mv.visitInsn(Opcodes.I2F); break;
case 'D': mv.visitInsn(Opcodes.I2D); break;
case 'Z':
// 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(char type) {
switch (type) {
case 'J': mv.visitInsn(Opcodes.L2I); break;
case 'F': mv.visitInsn(Opcodes.F2I); break;
case 'D': mv.visitInsn(Opcodes.D2I); break;
default: throw new InternalError("unknown type: " + type);
}
}
private static String basicTypeCharSignature(String prefix, MethodType type) {
StringBuilder buf = new StringBuilder(prefix);
for (Class<?> ptype : type.parameterList())
buf.append(Wrapper.forBasicType(ptype).basicTypeChar());
buf.append('_').append(Wrapper.forBasicType(type.returnType()).basicTypeChar());
return buf.toString();
}
/**
* Generate bytecode for a LambdaForm.vmentry which calls interpretWithArguments.
*/
static MemberName generateLambdaFormInterpreterEntryPoint(String sig) {
assert(LambdaForm.isValidSignature(sig));
//System.out.println("generateExactInvoker "+sig);
// compute method type
// first parameter and return type
char tret = LambdaForm.signatureReturn(sig);
MethodType type = MethodType.methodType(LambdaForm.typeClass(tret), MethodHandle.class);
// other parameter types
int arity = LambdaForm.signatureArity(sig);
for (int i = 1; i < arity; i++) {
type = type.appendParameterTypes(LambdaForm.typeClass(sig.charAt(i)));
}
InvokerBytecodeGenerator g = new InvokerBytecodeGenerator("LFI", "interpret_"+tret, type);
return g.loadMethod(g.generateLambdaFormInterpreterEntryPointBytes());
}
private byte[] generateLambdaFormInterpreterEntryPointBytes() {
classFilePrologue();
// Suppress this method in backtraces displayed to the user.
mv.visitAnnotation("Ljava/lang/invoke/LambdaForm$Hidden;", true);
// Don't inline the interpreter entry.
mv.visitAnnotation("Ljava/lang/invoke/DontInline;", 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(Wrapper.basicTypeChar(ptype), i);
// box if primitive type
if (ptype.isPrimitive()) {
emitBoxing(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;");
// maybe unbox
Class<?> rtype = invokerType.returnType();
if (rtype.isPrimitive() && rtype != void.class) {
emitUnboxing(Wrapper.asWrapperType(rtype));
}
// return statement
emitReturnInsn(rtype);
classFileEpilogue();
bogusMethod(invokerType);
final byte[] classFile = cw.toByteArray();
maybeDump(className, classFile);
return classFile;
}
/**
* Generate bytecode for a NamedFunction invoker.
*/
static MemberName generateNamedFunctionInvoker(MethodTypeForm typeForm) {
MethodType invokerType = LambdaForm.NamedFunction.INVOKER_METHOD_TYPE;
String invokerName = basicTypeCharSignature("invoke_", typeForm.erasedType());
InvokerBytecodeGenerator g = new InvokerBytecodeGenerator("NFI", invokerName, invokerType);
return g.loadMethod(g.generateNamedFunctionInvokerImpl(typeForm));
}
static int nfi = 0;
private byte[] generateNamedFunctionInvokerImpl(MethodTypeForm typeForm) {
MethodType dstType = typeForm.erasedType();
classFilePrologue();
// Suppress this method in backtraces displayed to the user.
mv.visitAnnotation("Ljava/lang/invoke/LambdaForm$Hidden;", true);
// Force inlining of this invoker method.
mv.visitAnnotation("Ljava/lang/invoke/ForceInline;", 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()) {
Class<?> sptype = dstType.basicType().wrap().parameterType(i);
Wrapper dstWrapper = Wrapper.forBasicType(dptype);
Wrapper srcWrapper = dstWrapper.isSubwordOrInt() ? Wrapper.INT : dstWrapper; // narrow subword from int
emitUnboxing(srcWrapper.wrapperType());
emitPrimCast(srcWrapper.basicTypeChar(), dstWrapper.basicTypeChar());
}
}
// Invoke
String targetDesc = dstType.basicType().toMethodDescriptorString();
mv.visitMethodInsn(Opcodes.INVOKEVIRTUAL, MH, "invokeBasic", targetDesc);
// 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.basicTypeChar(), dstWrapper.basicTypeChar());
emitBoxing(dstWrapper.primitiveType());
}
// If the return type is void we return a null reference.
if (rtype == void.class) {
mv.visitInsn(Opcodes.ACONST_NULL);
}
emitReturnInsn(Object.class); // NOTE: NamedFunction invokers always return a reference value.
classFileEpilogue();
bogusMethod(dstType);
final byte[] classFile = cw.toByteArray();
maybeDump(className, 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);
for (Object o : os) {
mv.visitLdcInsn(o.toString());
mv.visitInsn(Opcodes.POP);
}
mv.visitInsn(Opcodes.RETURN);
mv.visitMaxs(0, 0);
mv.visitEnd();
}
}
}
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