1 /*
  2  * Copyright (c) 2024, 2025, Oracle and/or its affiliates. All rights reserved.
  3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  4  *
  5  * This code is free software; you can redistribute it and/or modify it
  6  * under the terms of the GNU General Public License version 2 only, as
  7  * published by the Free Software Foundation.  Oracle designates this
  8  * particular file as subject to the "Classpath" exception as provided
  9  * by Oracle in the LICENSE file that accompanied this code.
 10  *
 11  * This code is distributed in the hope that it will be useful, but WITHOUT
 12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 14  * version 2 for more details (a copy is included in the LICENSE file that
 15  * accompanied this code).
 16  *
 17  * You should have received a copy of the GNU General Public License version
 18  * 2 along with this work; if not, write to the Free Software Foundation,
 19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 20  *
 21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 22  * or visit www.oracle.com if you need additional information or have any
 23  * questions.
 24  */
 25 
 26 import jdk.incubator.code.dialect.core.CoreType;
 27 import jdk.incubator.code.dialect.core.FunctionType;
 28 import jdk.incubator.code.dialect.core.VarType;
 29 import jdk.incubator.code.dialect.java.*;
 30 
 31 import java.lang.classfile.Attributes;
 32 import java.lang.classfile.ClassFile;
 33 import java.lang.classfile.ClassModel;
 34 import java.lang.classfile.CodeElement;
 35 import java.lang.classfile.CodeModel;
 36 import java.lang.classfile.Instruction;
 37 import java.lang.classfile.Label;
 38 import java.lang.classfile.MethodModel;
 39 import java.lang.classfile.Opcode;
 40 import java.lang.classfile.PseudoInstruction;
 41 import java.lang.classfile.TypeKind;
 42 import java.lang.classfile.attribute.StackMapFrameInfo;
 43 import java.lang.classfile.instruction.*;
 44 import java.lang.constant.ClassDesc;
 45 import java.lang.constant.ConstantDesc;
 46 import java.lang.constant.ConstantDescs;
 47 import java.lang.constant.DirectMethodHandleDesc;
 48 import java.lang.constant.DynamicConstantDesc;
 49 import java.lang.constant.MethodTypeDesc;
 50 import java.lang.invoke.CallSite;
 51 import java.lang.invoke.MethodHandle;
 52 import java.lang.reflect.AccessFlag;
 53 import jdk.incubator.code.Block;
 54 import jdk.incubator.code.TypeElement;
 55 import jdk.incubator.code.dialect.core.CoreOp;
 56 import jdk.incubator.code.Op;
 57 import jdk.incubator.code.Value;
 58 import jdk.incubator.code.analysis.NormalizeBlocksTransformer;
 59 
 60 import java.util.ArrayDeque;
 61 import java.util.ArrayList;
 62 import java.util.Arrays;
 63 import java.util.BitSet;
 64 import java.util.Collections;
 65 import java.util.Deque;
 66 import java.util.HashMap;
 67 import java.util.IdentityHashMap;
 68 import java.util.List;
 69 import java.util.Map;
 70 import java.util.stream.Collectors;
 71 import java.util.stream.IntStream;
 72 import java.util.stream.Stream;
 73 
 74 import static java.lang.classfile.attribute.StackMapFrameInfo.SimpleVerificationTypeInfo.*;
 75 
 76 public final class BytecodeLift {
 77 
 78     private static final ClassDesc CD_LambdaMetafactory = ClassDesc.ofDescriptor("Ljava/lang/invoke/LambdaMetafactory;");
 79     private static final ClassDesc CD_StringConcatFactory = ClassDesc.ofDescriptor("Ljava/lang/invoke/StringConcatFactory;");
 80     private static final JavaType MHS_LOOKUP = JavaType.type(ConstantDescs.CD_MethodHandles_Lookup);
 81     private static final JavaType MH = JavaType.type(ConstantDescs.CD_MethodHandle);
 82     private static final JavaType MT = JavaType.type(ConstantDescs.CD_MethodType);
 83     private static final JavaType CLASS_ARRAY = JavaType.array(JavaType.J_L_CLASS);
 84     private static final MethodRef LCMP = MethodRef.method(JavaType.J_L_LONG, "compare", JavaType.INT, JavaType.LONG, JavaType.LONG);
 85     private static final MethodRef FCMP = MethodRef.method(JavaType.J_L_FLOAT, "compare", JavaType.INT, JavaType.FLOAT, JavaType.FLOAT);
 86     private static final MethodRef DCMP = MethodRef.method(JavaType.J_L_DOUBLE, "compare", JavaType.INT, JavaType.DOUBLE, JavaType.DOUBLE);
 87     private static final MethodRef LOOKUP = MethodRef.method(JavaType.type(ConstantDescs.CD_MethodHandles), "lookup", MHS_LOOKUP);
 88     private static final MethodRef FIND_STATIC = MethodRef.method(MHS_LOOKUP, "findStatic", MH, JavaType.J_L_CLASS, JavaType.J_L_STRING, MT);
 89     private static final MethodRef FIND_VIRTUAL = MethodRef.method(MHS_LOOKUP, "findVirtual", MH, JavaType.J_L_CLASS, JavaType.J_L_STRING, MT);
 90     private static final MethodRef FIND_CONSTRUCTOR = MethodRef.method(MHS_LOOKUP, "findConstructor", MH, JavaType.J_L_CLASS, MT);
 91     private static final MethodRef FIND_GETTER = MethodRef.method(MHS_LOOKUP, "findGetter", MH, JavaType.J_L_CLASS, JavaType.J_L_STRING, JavaType.J_L_CLASS);
 92     private static final MethodRef FIND_STATIC_GETTER = MethodRef.method(MHS_LOOKUP, "findStaticGetter", MH, JavaType.J_L_CLASS, JavaType.J_L_STRING, JavaType.J_L_CLASS);
 93     private static final MethodRef FIND_SETTER = MethodRef.method(MHS_LOOKUP, "findSetter", MH, JavaType.J_L_CLASS, JavaType.J_L_STRING, JavaType.J_L_CLASS);
 94     private static final MethodRef FIND_STATIC_SETTER = MethodRef.method(MHS_LOOKUP, "findStaticSetter", MH, JavaType.J_L_CLASS, JavaType.J_L_STRING, JavaType.J_L_CLASS);
 95     private static final MethodRef METHOD_TYPE_0 = MethodRef.method(MT, "methodType", MT, JavaType.J_L_CLASS);
 96     private static final MethodRef METHOD_TYPE_1 = MethodRef.method(MT, "methodType", MT, JavaType.J_L_CLASS, JavaType.J_L_CLASS);
 97     private static final MethodRef METHOD_TYPE_L = MethodRef.method(MT, "methodType", MT, JavaType.J_L_CLASS, CLASS_ARRAY);
 98 
 99     private final Block.Builder entryBlock;
100     private final List<Value> initialValues;
101     private final ClassModel classModel;
102     private final List<Label> exceptionHandlers;
103     private final Map<Integer, Block.Builder> exceptionHandlerBlocks;
104     private final BitSet actualEreStack;
105     private final Map<Label, BitSet> exceptionHandlersMap;
106     private final Map<Label, Block.Builder> blockMap;
107     private final List<CodeElement> elements;
108     private final Deque<Value> stack;
109     private final Deque<ClassDesc> newStack;
110     private final List<ExceptionCatch> ecs;
111     private Block.Builder currentBlock;
112 
113     private BytecodeLift(Block.Builder entryBlock, ClassModel classModel, CodeModel codeModel, Value... capturedValues) {
114         this.entryBlock = entryBlock;
115         this.initialValues = Stream.concat(Stream.of(capturedValues), entryBlock.parameters().stream()).toList();
116         this.currentBlock = entryBlock;
117         this.classModel = classModel;
118         this.exceptionHandlers = new ArrayList<>();
119         this.exceptionHandlerBlocks = new HashMap<>();
120         this.actualEreStack = new BitSet();
121         this.newStack = new ArrayDeque<>();
122         this.elements = codeModel.elementList();
123         this.stack = new ArrayDeque<>();
124         this.exceptionHandlersMap = new IdentityHashMap<>();
125         this.blockMap = codeModel.findAttribute(Attributes.stackMapTable()).map(sma ->
126                 sma.entries().stream().collect(Collectors.toUnmodifiableMap(
127                         StackMapFrameInfo::target,
128                         smfi -> entryBlock.block(toBlockParams(smfi.stack()))))).orElseGet(Map::of);
129         this.ecs = codeModel.exceptionHandlers();
130         for (var ec : ecs.reversed()) {
131             if (exceptionHandlers.indexOf(ec.handler()) < 0) {
132                 exceptionHandlers.add(ec.handler());
133             }
134         }
135     }
136 
137     private List<TypeElement> toBlockParams(List<StackMapFrameInfo.VerificationTypeInfo> vtis) {
138         ArrayList<TypeElement> params = new ArrayList<>(vtis.size());
139         for (int i = vtis.size() - 1; i >= 0; i--) {
140             var vti = vtis.get(i);
141             switch (vti) {
142                 case INTEGER -> params.add(UnresolvedType.unresolvedInt());
143                 case FLOAT -> params.add(JavaType.FLOAT);
144                 case DOUBLE -> params.add(JavaType.DOUBLE);
145                 case LONG -> params.add(JavaType.LONG);
146                 case NULL -> params.add(UnresolvedType.unresolvedRef());
147                 case UNINITIALIZED_THIS ->
148                     params.add(JavaType.type(classModel.thisClass().asSymbol()));
149                 case StackMapFrameInfo.ObjectVerificationTypeInfo ovti ->
150                     params.add(JavaType.type(ovti.classSymbol()));
151 
152                     // Unitialized entry (a new object before its constructor is called)
153                     // must be skipped from block parameters because they do not exist in code reflection model
154                 case StackMapFrameInfo.UninitializedVerificationTypeInfo _ -> {}
155                 default ->
156                     throw new IllegalArgumentException("Unexpected VTI: " + vti);
157             }
158         }
159         return params;
160     }
161 
162     private Op.Result op(Op op) {
163         return currentBlock.op(op);
164     }
165 
166     // Lift to core dialect
167     public static CoreOp.FuncOp lift(byte[] classdata, String methodName) {
168         return lift(classdata, methodName, null);
169     }
170 
171     public static CoreOp.FuncOp lift(byte[] classdata, String methodName, MethodTypeDesc methodType) {
172         return lift(ClassFile.of(
173                 ClassFile.DebugElementsOption.DROP_DEBUG,
174                 ClassFile.LineNumbersOption.DROP_LINE_NUMBERS).parse(classdata).methods().stream()
175                         .filter(mm -> mm.methodName().equalsString(methodName) && (methodType == null || mm.methodTypeSymbol().equals(methodType)))
176                         .findFirst().orElseThrow(() -> new IllegalArgumentException("Unknown method: " + methodName)));
177     }
178 
179     public static CoreOp.FuncOp lift(MethodModel methodModel) {
180         ClassModel classModel = methodModel.parent().orElseThrow();
181         MethodTypeDesc mDesc = methodModel.methodTypeSymbol();
182         if (!methodModel.flags().has(AccessFlag.STATIC)) {
183             mDesc = mDesc.insertParameterTypes(0, classModel.thisClass().asSymbol());
184         }
185         return NormalizeBlocksTransformer.transform(
186                 UnresolvedTypesTransformer.transform(
187                     SlotToVarTransformer.transform(
188                         CoreOp.func(methodModel.methodName().stringValue(),
189                                     MethodRef.ofNominalDescriptor(mDesc)).body(entryBlock ->
190                                             new BytecodeLift(entryBlock,
191                                                              classModel,
192                                                              methodModel.code().orElseThrow()).liftBody()))));
193     }
194 
195     private void liftBody() {
196         // store entry block
197         int slot = 0;
198         for (var ep : initialValues) {
199             op(SlotOp.store(slot, ep));
200             slot += ep.type().equals(JavaType.LONG) || ep.type().equals(JavaType.DOUBLE) ? 2 : 1;
201         }
202 
203         // fill exceptionHandlersMap
204         BitSet eStack = new BitSet();
205         for (var e : elements) {
206             if (e instanceof LabelTarget lt) {
207                 BitSet newEreStack = null;
208                 for (var er : ecs) {
209                     if (lt.label() == er.tryStart() || lt.label() == er.tryEnd()) {
210                         if (newEreStack == null) newEreStack = (BitSet)eStack.clone();
211 
212                         newEreStack.set(exceptionHandlers.indexOf(er.handler()), lt.label() == er.tryStart());
213                     }
214                 }
215                 if (newEreStack != null || blockMap.containsKey(lt.label()))  {
216                     if (newEreStack != null) eStack = newEreStack;
217                     exceptionHandlersMap.put(lt.label(), eStack);
218                 }
219             }
220         }
221 
222         for (int i = 0; i < elements.size(); i++) {
223             switch (elements.get(i)) {
224                 case ExceptionCatch _ -> {
225                     // Exception blocks are inserted by label target (below)
226                 }
227                 case LabelTarget lt -> {
228                     BitSet newEreStack = exceptionHandlersMap.get(lt.label());
229                     if (newEreStack != null) {
230                         Block.Builder target = blockMap.get(lt.label());
231                         if (target != null) {
232                             if (currentBlock != null) {
233                                 // Transition to a branch target or a handler
234                                 ereTransit(actualEreStack, newEreStack, currentBlock, target, stackValues(target), exceptionHandlers.indexOf(lt.label()));
235                             }
236                             currentBlock = target;
237                             stack.clear();
238                             stack.addAll(target.parameters());
239                         } else if (currentBlock != null && !actualEreStack.equals(newEreStack)) {
240                             // Transition to a block with a different ERE stack
241                             Block.Builder next = entryBlock.block();
242                             ereTransit(actualEreStack, newEreStack, currentBlock, next, List.of(), -1);
243                             currentBlock = next;
244                         }
245                         actualEreStack.clear();
246                         actualEreStack.or(newEreStack);
247                     }
248                 }
249                 case BranchInstruction inst when isUnconditionalBranch(inst.opcode()) -> {
250                     Block.Builder target = blockMap.get(inst.target());
251                     ereTransit(actualEreStack, exceptionHandlersMap.get(inst.target()), currentBlock, target, stackValues(target), exceptionHandlers.indexOf(inst.target()));
252                     endOfFlow();
253                 }
254                 case BranchInstruction inst -> {
255                     // Conditional branch
256                     Value operand = stack.pop();
257                     Op cop = switch (inst.opcode()) {
258                         case IFNE -> JavaOp.eq(operand, liftConstant(0));
259                         case IFEQ -> JavaOp.neq(operand, liftConstant(0));
260                         case IFGE -> JavaOp.lt(operand, liftConstant(0));
261                         case IFLE -> JavaOp.gt(operand, liftConstant(0));
262                         case IFGT -> JavaOp.le(operand, liftConstant(0));
263                         case IFLT -> JavaOp.ge(operand, liftConstant(0));
264                         case IFNULL -> JavaOp.neq(operand, liftConstant(null));
265                         case IFNONNULL -> JavaOp.eq(operand, liftConstant(null));
266                         case IF_ICMPNE -> JavaOp.eq(stack.pop(), operand);
267                         case IF_ICMPEQ -> JavaOp.neq(stack.pop(), operand);
268                         case IF_ICMPGE -> JavaOp.lt(stack.pop(), operand);
269                         case IF_ICMPLE -> JavaOp.gt(stack.pop(), operand);
270                         case IF_ICMPGT -> JavaOp.le(stack.pop(), operand);
271                         case IF_ICMPLT -> JavaOp.ge(stack.pop(), operand);
272                         case IF_ACMPEQ -> JavaOp.neq(stack.pop(), operand);
273                         case IF_ACMPNE -> JavaOp.eq(stack.pop(), operand);
274                         default -> throw new UnsupportedOperationException("Unsupported branch instruction: " + inst);
275                     };
276                     Block.Builder branch = targetBlockForBranch(inst.target());
277                     Block.Builder next = entryBlock.block();
278                     op(CoreOp.conditionalBranch(op(cop),
279                             next.successor(),
280                             successorWithStack(branch)));
281                     currentBlock = next;
282                 }
283                 case LookupSwitchInstruction si -> {
284                     liftSwitch(si.defaultTarget(), si.cases());
285                 }
286                 case TableSwitchInstruction si -> {
287                     liftSwitch(si.defaultTarget(), si.cases());
288                 }
289                 case ReturnInstruction inst when inst.typeKind() == TypeKind.VOID -> {
290                     op(CoreOp.return_());
291                     endOfFlow();
292                 }
293                 case ReturnInstruction _ -> {
294                     op(CoreOp.return_(stack.pop()));
295                     endOfFlow();
296                 }
297                 case ThrowInstruction _ -> {
298                     op(JavaOp.throw_(stack.pop()));
299                     endOfFlow();
300                 }
301                 case LoadInstruction inst -> {
302                     stack.push(op(SlotOp.load(inst.slot(), inst.typeKind())));
303                 }
304                 case StoreInstruction inst -> {
305                     op(SlotOp.store(inst.slot(), stack.pop()));
306                 }
307                 case IncrementInstruction inst -> {
308                     op(SlotOp.store(inst.slot(), op(JavaOp.add(op(SlotOp.load(inst.slot(), TypeKind.INT)), liftConstant(inst.constant())))));
309                 }
310                 case ConstantInstruction inst -> {
311                     stack.push(liftConstant(inst.constantValue()));
312                 }
313                 case ConvertInstruction inst -> {
314                     stack.push(op(JavaOp.conv(switch (inst.toType()) {
315                         case BYTE -> JavaType.BYTE;
316                         case SHORT -> JavaType.SHORT;
317                         case INT -> JavaType.INT;
318                         case FLOAT -> JavaType.FLOAT;
319                         case LONG -> JavaType.LONG;
320                         case DOUBLE -> JavaType.DOUBLE;
321                         case CHAR -> JavaType.CHAR;
322                         case BOOLEAN -> JavaType.BOOLEAN;
323                         default ->
324                             throw new IllegalArgumentException("Unsupported conversion target: " + inst.toType());
325                     }, stack.pop())));
326                 }
327                 case OperatorInstruction inst -> {
328                     TypeKind tk = inst.typeKind();
329                     Value operand = stack.pop();
330                     stack.push(op(switch (inst.opcode()) {
331                         case IADD, LADD, FADD, DADD ->
332                                 JavaOp.add(stack.pop(), operand);
333                         case ISUB, LSUB, FSUB, DSUB ->
334                                 JavaOp.sub(stack.pop(), operand);
335                         case IMUL, LMUL, FMUL, DMUL ->
336                                 JavaOp.mul(stack.pop(), operand);
337                         case IDIV, LDIV, FDIV, DDIV ->
338                                 JavaOp.div(stack.pop(), operand);
339                         case IREM, LREM, FREM, DREM ->
340                                 JavaOp.mod(stack.pop(), operand);
341                         case INEG, LNEG, FNEG, DNEG ->
342                                 JavaOp.neg(operand);
343                         case ARRAYLENGTH ->
344                                 JavaOp.arrayLength(operand);
345                         case IAND, LAND ->
346                                 JavaOp.and(stack.pop(), operand);
347                         case IOR, LOR ->
348                                 JavaOp.or(stack.pop(), operand);
349                         case IXOR, LXOR ->
350                                 JavaOp.xor(stack.pop(), operand);
351                         case ISHL, LSHL ->
352                                 JavaOp.lshl(stack.pop(), operand);
353                         case ISHR, LSHR ->
354                                 JavaOp.ashr(stack.pop(), operand);
355                         case IUSHR, LUSHR ->
356                                 JavaOp.lshr(stack.pop(), operand);
357                         case LCMP ->
358                                 JavaOp.invoke(LCMP, stack.pop(), operand);
359                         case FCMPL, FCMPG ->
360                                 JavaOp.invoke(FCMP, stack.pop(), operand);
361                         case DCMPL, DCMPG ->
362                                 JavaOp.invoke(DCMP, stack.pop(), operand);
363                         default ->
364                             throw new IllegalArgumentException("Unsupported operator opcode: " + inst.opcode());
365                     }));
366                 }
367                 case FieldInstruction inst -> {
368                         FieldRef fd = FieldRef.field(
369                                 JavaType.type(inst.owner().asSymbol()),
370                                 inst.name().stringValue(),
371                                 JavaType.type(inst.typeSymbol()));
372                         switch (inst.opcode()) {
373                             case GETFIELD ->
374                                 stack.push(op(JavaOp.fieldLoad(fd, stack.pop())));
375                             case GETSTATIC ->
376                                 stack.push(op(JavaOp.fieldLoad(fd)));
377                             case PUTFIELD -> {
378                                 Value value = stack.pop();
379                                 op(JavaOp.fieldStore(fd, stack.pop(), value));
380                             }
381                             case PUTSTATIC ->
382                                 op(JavaOp.fieldStore(fd, stack.pop()));
383                             default ->
384                                 throw new IllegalArgumentException("Unsupported field opcode: " + inst.opcode());
385                         }
386                 }
387                 case ArrayStoreInstruction _ -> {
388                     Value value = stack.pop();
389                     Value index = stack.pop();
390                     op(JavaOp.arrayStoreOp(stack.pop(), index, value));
391                 }
392                 case ArrayLoadInstruction ali -> {
393                     Value index = stack.pop();
394                     Value array = stack.pop();
395                     if (array.type() instanceof UnresolvedType) {
396                         stack.push(op(JavaOp.arrayLoadOp(array, index, switch (ali.typeKind()) {
397                             case BYTE -> UnresolvedType.unresolvedInt(); // @@@ Create UnresolvedType.unresolvedByteOrBoolean();
398                             case CHAR -> JavaType.CHAR;
399                             case DOUBLE -> JavaType.DOUBLE;
400                             case FLOAT -> JavaType.FLOAT;
401                             case INT -> JavaType.INT;
402                             case LONG -> JavaType.LONG;
403                             case SHORT -> JavaType.SHORT;
404                             case REFERENCE ->  UnresolvedType.unresolvedRef();
405                             case BOOLEAN, VOID -> throw new IllegalArgumentException("Unexpected array load instruction type");
406                         })));
407                     } else {
408                         stack.push(op(JavaOp.arrayLoadOp(array, index)));
409                     }
410                 }
411                 case InvokeInstruction inst -> {
412                     FunctionType mType = MethodRef.ofNominalDescriptor(inst.typeSymbol());
413                     List<Value> operands = new ArrayList<>();
414                     for (var _ : mType.parameterTypes()) {
415                         operands.add(stack.pop());
416                     }
417                     MethodRef mDesc = MethodRef.method(
418                             JavaType.type(inst.owner().asSymbol()),
419                             inst.name().stringValue(),
420                             mType);
421                     Op.Result result = switch (inst.opcode()) {
422                         case INVOKEVIRTUAL, INVOKEINTERFACE -> {
423                             operands.add(stack.pop());
424                             yield op(JavaOp.invoke(JavaOp.InvokeOp.InvokeKind.INSTANCE, false,
425                                     mDesc.type().returnType(), mDesc, operands.reversed()));
426                         }
427                         case INVOKESTATIC ->
428                                 op(JavaOp.invoke(JavaOp.InvokeOp.InvokeKind.STATIC, false,
429                                         mDesc.type().returnType(), mDesc, operands.reversed()));
430                         case INVOKESPECIAL -> {
431                             if (inst.owner().asSymbol().equals(newStack.peek()) && inst.name().equalsString(ConstantDescs.INIT_NAME)) {
432                                 newStack.pop();
433                                 yield op(JavaOp.new_(
434                                         MethodRef.constructor(
435                                                 mDesc.refType(),
436                                                 mType.parameterTypes()),
437                                         operands.reversed()));
438                             } else {
439                                 operands.add(stack.pop());
440                                 yield op(JavaOp.invoke(JavaOp.InvokeOp.InvokeKind.SUPER, false,
441                                         mDesc.type().returnType(), mDesc, operands.reversed()));
442                             }
443                         }
444                         default ->
445                             throw new IllegalArgumentException("Unsupported invocation opcode: " + inst.opcode());
446                     };
447                     if (!result.type().equals(JavaType.VOID)) {
448                         stack.push(result);
449                     }
450                 }
451                 case InvokeDynamicInstruction inst when inst.bootstrapMethod().kind() == DirectMethodHandleDesc.Kind.STATIC -> {
452                     DirectMethodHandleDesc bsm = inst.bootstrapMethod();
453                     ClassDesc bsmOwner = bsm.owner();
454                     if (bsmOwner.equals(CD_LambdaMetafactory)
455                         && inst.bootstrapArgs().get(0) instanceof MethodTypeDesc mtd
456                         && inst.bootstrapArgs().get(1) instanceof DirectMethodHandleDesc dmhd) {
457 
458                         var capturedValues = new Value[dmhd.invocationType().parameterCount() - mtd.parameterCount()];
459                         for (int ci = capturedValues.length - 1; ci >= 0; ci--) {
460                             capturedValues[ci] = stack.pop();
461                         }
462                         for (int ci = capturedValues.length; ci < inst.typeSymbol().parameterCount(); ci++) {
463                             stack.pop();
464                         }
465                         MethodTypeDesc mt = dmhd.invocationType();
466                         if (capturedValues.length > 0) {
467                             mt = mt.dropParameterTypes(0, capturedValues.length);
468                         }
469                         FunctionType lambdaFunc = CoreType.functionType(JavaType.type(mt.returnType()),
470                                                                             mt.parameterList().stream().map(JavaType::type).toList());
471                         JavaOp.LambdaOp.Builder lambda = JavaOp.lambda(currentBlock.parentBody(),
472                                                                        lambdaFunc,
473                                                                        JavaType.type(inst.typeSymbol().returnType()));
474                         // if ReflectableLambdaMetafactory is used, the lambda is reflectable
475                         if (bsm.owner().displayName().equals("jdk.incubator.code.runtime.ReflectableLambdaMetafactory")) {
476                             lambda = lambda.reflectable();
477                         }
478 
479                         if (dmhd.methodName().startsWith("lambda$") && dmhd.owner().equals(classModel.thisClass().asSymbol())) {
480                             // inline lambda impl method
481                             MethodModel implMethod = classModel.methods().stream().filter(m -> m.methodName().equalsString(dmhd.methodName())).findFirst().orElseThrow();
482                             stack.push(op(lambda.body(eb -> new BytecodeLift(eb,
483                                                            classModel,
484                                                            implMethod.code().orElseThrow(),
485                                                            capturedValues).liftBody())));
486                         } else {
487                             // lambda call to a MH
488                             stack.push(op(lambda.body(eb -> {
489                                 Op.Result ret = eb.op(JavaOp.invoke(
490                                         MethodRef.method(JavaType.type(dmhd.owner()),
491                                                          dmhd.methodName(),
492                                                          lambdaFunc.returnType(),
493                                                          lambdaFunc.parameterTypes()),
494                                         Stream.concat(Arrays.stream(capturedValues), eb.parameters().stream()).toArray(Value[]::new)));
495                                 eb.op(ret.type().equals(JavaType.VOID) ? CoreOp.return_() : CoreOp.return_(ret));
496                             })));
497                         }
498                     } else if (bsmOwner.equals(CD_StringConcatFactory)) {
499                         int argsCount = inst.typeSymbol().parameterCount();
500                         Deque<Value> args = new ArrayDeque<>(argsCount);
501                         for (int ai = 0; ai < argsCount; ai++) {
502                             args.push(stack.pop());
503                         }
504                         Value res = null;
505                         if (bsm.methodName().equals("makeConcat")) {
506                             for (Value argVal : args) {
507                                 res = res == null ? argVal : op(JavaOp.concat(res, argVal));
508                             }
509                         } else {
510                             assert bsm.methodName().equals("makeConcatWithConstants");
511                             var bsmArgs = inst.bootstrapArgs();
512                             String recipe = (String)(bsmArgs.getFirst());
513                             int bsmArg = 1;
514                             for (int ri = 0; ri < recipe.length(); ri++) {
515                                 Value argVal = switch (recipe.charAt(ri)) {
516                                     case '\u0001' -> args.pop();
517                                     case '\u0002' -> liftConstant(bsmArgs.get(bsmArg++));
518                                     default -> {
519                                         char c;
520                                         int start = ri;
521                                         while (ri < recipe.length() && (c = recipe.charAt(ri)) != '\u0001' && c != '\u0002') ri++;
522                                         yield liftConstant(recipe.substring(start, ri--));
523                                     }
524                                 };
525                                 res = res == null ? argVal : op(JavaOp.concat(res, argVal));
526                             }
527                         }
528                         if (res != null) stack.push(res);
529                     } else {
530                         MethodTypeDesc mtd = inst.typeSymbol();
531 
532                         //bootstrap
533                         MethodTypeDesc bsmDesc = bsm.invocationType();
534                         MethodRef bsmRef = MethodRef.method(JavaType.type(bsmOwner),
535                                                             bsm.methodName(),
536                                                             JavaType.type(bsmDesc.returnType()),
537                                                             bsmDesc.parameterList().stream().map(JavaType::type).toArray(TypeElement[]::new));
538 
539                         Value[] bootstrapArgs = liftBootstrapArgs(bsmDesc, inst.name().toString(), mtd, inst.bootstrapArgs());
540                         Value methodHandle = op(JavaOp.invoke(MethodRef.method(CallSite.class, "dynamicInvoker", MethodHandle.class),
541                                                     op(JavaOp.invoke(JavaType.type(ConstantDescs.CD_CallSite), bsmRef, bootstrapArgs))));
542 
543                         //invocation
544                         List<Value> operands = new ArrayList<>();
545                         for (int c = 0; c < mtd.parameterCount(); c++) {
546                             operands.add(stack.pop());
547                         }
548                         operands.add(methodHandle);
549                         MethodRef mDesc = MethodRef.method(JavaType.type(ConstantDescs.CD_MethodHandle),
550                                                            "invokeExact",
551                                                            MethodRef.ofNominalDescriptor(mtd));
552                         Op.Result result = op(JavaOp.invoke(mDesc, operands.reversed()));
553                         if (!result.type().equals(JavaType.VOID)) {
554                             stack.push(result);
555                         }
556                     }
557                 }
558                 case NewObjectInstruction inst -> {
559                     // Skip over this and the dup to process the invoke special
560                     if (i + 2 < elements.size() - 1
561                             && elements.get(i + 1) instanceof StackInstruction dup
562                             && dup.opcode() == Opcode.DUP) {
563                         i++;
564                         newStack.push(inst.className().asSymbol());
565                     } else {
566                         throw new UnsupportedOperationException("New must be followed by dup");
567                     }
568                 }
569                 case NewPrimitiveArrayInstruction inst -> {
570                     stack.push(op(JavaOp.newArray(
571                             switch (inst.typeKind()) {
572                                 case BOOLEAN -> JavaType.BOOLEAN_ARRAY;
573                                 case BYTE -> JavaType.BYTE_ARRAY;
574                                 case CHAR -> JavaType.CHAR_ARRAY;
575                                 case DOUBLE -> JavaType.DOUBLE_ARRAY;
576                                 case FLOAT -> JavaType.FLOAT_ARRAY;
577                                 case INT -> JavaType.INT_ARRAY;
578                                 case LONG -> JavaType.LONG_ARRAY;
579                                 case SHORT -> JavaType.SHORT_ARRAY;
580                                 default ->
581                                         throw new UnsupportedOperationException("Unsupported new primitive array type: " + inst.typeKind());
582                             },
583                             stack.pop())));
584                 }
585                 case NewReferenceArrayInstruction inst -> {
586                     stack.push(op(JavaOp.newArray(
587                             JavaType.type(inst.componentType().asSymbol().arrayType()),
588                             stack.pop())));
589                 }
590                 case NewMultiArrayInstruction inst -> {
591                     stack.push(op(JavaOp.new_(
592                             MethodRef.constructor(
593                                     JavaType.type(inst.arrayType().asSymbol()),
594                                     Collections.nCopies(inst.dimensions(), JavaType.INT)),
595                             IntStream.range(0, inst.dimensions()).mapToObj(_ -> stack.pop()).toList().reversed())));
596                 }
597                 case TypeCheckInstruction inst when inst.opcode() == Opcode.CHECKCAST -> {
598                     stack.push(op(JavaOp.cast(JavaType.type(inst.type().asSymbol()), stack.pop())));
599                 }
600                 case TypeCheckInstruction inst -> {
601                     stack.push(op(JavaOp.instanceOf(JavaType.type(inst.type().asSymbol()), stack.pop())));
602                 }
603                 case StackInstruction inst -> {
604                     switch (inst.opcode()) {
605                         case POP -> {
606                             stack.pop();
607                         }
608                         case POP2 -> {
609                             if (isCategory1(stack.pop())) {
610                                 stack.pop();
611                             }
612                         }
613                         case DUP -> {
614                             stack.push(stack.peek());
615                         }
616                         case DUP_X1 -> {
617                             var value1 = stack.pop();
618                             var value2 = stack.pop();
619                             stack.push(value1);
620                             stack.push(value2);
621                             stack.push(value1);
622                         }
623                         case DUP_X2 -> {
624                             var value1 = stack.pop();
625                             var value2 = stack.pop();
626                             if (isCategory1(value2)) {
627                                 var value3 = stack.pop();
628                                 stack.push(value1);
629                                 stack.push(value3);
630                             } else {
631                                 stack.push(value1);
632                             }
633                             stack.push(value2);
634                             stack.push(value1);
635                         }
636                         case DUP2 -> {
637                             var value1 = stack.peek();
638                             if (isCategory1(value1)) {
639                                 stack.pop();
640                                 var value2 = stack.peek();
641                                 stack.push(value1);
642                                 stack.push(value2);
643                             }
644                             stack.push(value1);
645                         }
646                         case DUP2_X1 -> {
647                             var value1 = stack.pop();
648                             var value2 = stack.pop();
649                             if (isCategory1(value1)) {
650                                 var value3 = stack.pop();
651                                 stack.push(value2);
652                                 stack.push(value1);
653                                 stack.push(value3);
654                             } else {
655                                 stack.push(value1);
656                             }
657                             stack.push(value2);
658                             stack.push(value1);
659                         }
660                         case DUP2_X2 -> {
661                             var value1 = stack.pop();
662                             var value2 = stack.pop();
663                             if (isCategory1(value1)) {
664                                 var value3 = stack.pop();
665                                 if (isCategory1(value3)) {
666                                     var value4 = stack.pop();
667                                     stack.push(value2);
668                                     stack.push(value1);
669                                     stack.push(value4);
670                                 } else {
671                                     stack.push(value2);
672                                     stack.push(value1);
673                                 }
674                                 stack.push(value3);
675                             } else {
676                                 if (isCategory1(value2)) {
677                                     var value3 = stack.pop();
678                                     stack.push(value1);
679                                     stack.push(value3);
680                                 } else {
681                                     stack.push(value1);
682                                 }
683                             }
684                             stack.push(value2);
685                             stack.push(value1);
686                         }
687                         case SWAP -> {
688                             var value1 = stack.pop();
689                             var value2 = stack.pop();
690                             stack.push(value1);
691                             stack.push(value2);
692                         }
693                         default ->
694                             throw new UnsupportedOperationException("Unsupported stack instruction: " + inst);
695                     }
696                 }
697                 case MonitorInstruction inst -> {
698                     var monitor = stack.pop();
699                     switch (inst.opcode()) {
700                         case MONITORENTER -> op(JavaOp.monitorEnter(monitor));
701                         case MONITOREXIT -> op(JavaOp.monitorExit(monitor));
702                         default ->
703                                 throw new UnsupportedOperationException("Unsupported stack instruction: " + inst);
704                     }
705                 }
706                 case NopInstruction _ -> {}
707                 case PseudoInstruction _ -> {}
708                 case Instruction inst ->
709                     throw new UnsupportedOperationException("Unsupported instruction: " + inst.opcode().name());
710                 default ->
711                     throw new UnsupportedOperationException("Unsupported code element: " + elements.get(i));
712             }
713         }
714         assert newStack.isEmpty();
715     }
716 
717     private Op.Result liftConstantsIntoArray(TypeElement arrayType, Object... constants) {
718         Op.Result array = op(JavaOp.newArray(arrayType, liftConstant(constants.length)));
719         for (int i = 0; i < constants.length; i++) {
720             op(JavaOp.arrayStoreOp(array, liftConstant(i), liftConstant(constants[i])));
721         }
722         return array;
723     }
724 
725     private Op.Result liftDefaultValue(ClassDesc type) {
726         return liftConstant(switch (TypeKind.from(type)) {
727             case BOOLEAN -> false;
728             case BYTE -> (byte)0;
729             case CHAR -> (char)0;
730             case DOUBLE -> 0d;
731             case FLOAT -> 0f;
732             case INT -> 0;
733             case LONG -> 0l;
734             case REFERENCE -> null;
735             case SHORT -> (short)0;
736             default -> throw new IllegalStateException("Invalid type " + type.displayName());
737         });
738     }
739 
740     private Op.Result liftConstant(Object c) {
741         return switch (c) {
742             case null -> op(CoreOp.constant(UnresolvedType.unresolvedRef(), null));
743             case ClassDesc cd -> op(CoreOp.constant(JavaType.J_L_CLASS, JavaType.type(cd)));
744             case Double d -> op(CoreOp.constant(JavaType.DOUBLE, d));
745             case Float f -> op(CoreOp.constant(JavaType.FLOAT, f));
746             case Integer ii -> op(CoreOp.constant(UnresolvedType.unresolvedInt(), ii));
747             case Long l -> op(CoreOp.constant(JavaType.LONG, l));
748             case String s -> op(CoreOp.constant(JavaType.J_L_STRING, s));
749             case DirectMethodHandleDesc dmh -> {
750                 Op.Result lookup = op(JavaOp.invoke(LOOKUP));
751                 Op.Result owner = liftConstant(dmh.owner());
752                 Op.Result name = liftConstant(dmh.methodName());
753                 MethodTypeDesc invDesc = dmh.invocationType();
754                 yield op(switch (dmh.kind()) {
755                     case STATIC, INTERFACE_STATIC  ->
756                         JavaOp.invoke(FIND_STATIC, lookup, owner, name, liftConstant(invDesc));
757                     case VIRTUAL, INTERFACE_VIRTUAL ->
758                         JavaOp.invoke(FIND_VIRTUAL, lookup, owner, name, liftConstant(invDesc.dropParameterTypes(0, 1)));
759                     case SPECIAL, INTERFACE_SPECIAL ->
760                         //CoreOp.invoke(MethodRef.method(e), "findSpecial", owner, name, liftConstant(invDesc.dropParameterTypes(0, 1)), lookup.lookupClass());
761                         throw new UnsupportedOperationException(dmh.toString());
762                     case CONSTRUCTOR       ->
763                         JavaOp.invoke(FIND_CONSTRUCTOR, lookup, owner, liftConstant(invDesc.changeReturnType(ConstantDescs.CD_Void)));
764                     case GETTER            ->
765                         JavaOp.invoke(FIND_GETTER, lookup, owner, name, liftConstant(invDesc.returnType()));
766                     case STATIC_GETTER     ->
767                         JavaOp.invoke(FIND_STATIC_GETTER, lookup, owner, name, liftConstant(invDesc.returnType()));
768                     case SETTER            ->
769                         JavaOp.invoke(FIND_SETTER, lookup, owner, name, liftConstant(invDesc.parameterType(1)));
770                     case STATIC_SETTER     ->
771                         JavaOp.invoke(FIND_STATIC_SETTER, lookup, owner, name, liftConstant(invDesc.parameterType(0)));
772                 });
773             }
774             case MethodTypeDesc mt -> op(switch (mt.parameterCount()) {
775                 case 0 -> JavaOp.invoke(METHOD_TYPE_0, liftConstant(mt.returnType()));
776                 case 1 -> JavaOp.invoke(METHOD_TYPE_1, liftConstant(mt.returnType()), liftConstant(mt.parameterType(0)));
777                 default -> JavaOp.invoke(METHOD_TYPE_L, liftConstant(mt.returnType()), liftConstantsIntoArray(CLASS_ARRAY, (Object[])mt.parameterArray()));
778             });
779             case DynamicConstantDesc<?> v when v.bootstrapMethod().owner().equals(ConstantDescs.CD_ConstantBootstraps)
780                                          && v.bootstrapMethod().methodName().equals("nullConstant")
781                     -> {
782                 c = null;
783                 yield liftConstant(null);
784             }
785             case DynamicConstantDesc<?> dcd -> {
786                 DirectMethodHandleDesc bsm = dcd.bootstrapMethod();
787                 MethodTypeDesc bsmDesc = bsm.invocationType();
788                 Value[] bootstrapArgs = liftBootstrapArgs(bsmDesc, dcd.constantName(), dcd.constantType(), dcd.bootstrapArgsList());
789                 MethodRef bsmRef = MethodRef.method(JavaType.type(bsm.owner()),
790                                                     bsm.methodName(),
791                                                     JavaType.type(bsmDesc.returnType()),
792                                                     bsmDesc.parameterList().stream().map(JavaType::type).toArray(TypeElement[]::new));
793                 yield op(JavaOp.invoke(bsmRef, bootstrapArgs));
794             }
795             case Boolean b -> op(CoreOp.constant(JavaType.BOOLEAN, b));
796             case Byte b -> op(CoreOp.constant(JavaType.BYTE, b));
797             case Short s -> op(CoreOp.constant(JavaType.SHORT, s));
798             case Character ch -> op(CoreOp.constant(JavaType.CHAR, ch));
799             default -> throw new UnsupportedOperationException(c.getClass().toString());
800         };
801     }
802 
803     private Value[] liftBootstrapArgs(MethodTypeDesc bsmDesc, String name, ConstantDesc desc, List<ConstantDesc> bsmArgs) {
804         Value[] bootstrapArgs = new Value[bsmDesc.parameterCount()];
805         bootstrapArgs[0] = op(JavaOp.invoke(LOOKUP));
806         bootstrapArgs[1] = liftConstant(name);
807         bootstrapArgs[2] = liftConstant(desc);
808         ClassDesc lastArgType = bsmDesc.parameterType(bsmDesc.parameterCount() - 1);
809         if (lastArgType.isArray()) {
810             for (int ai = 0; ai < bootstrapArgs.length - 4; ai++) {
811                 bootstrapArgs[ai + 3] = liftConstant(bsmArgs.get(ai));
812             }
813             // Vararg tail of the bootstrap method parameters
814             bootstrapArgs[bootstrapArgs.length - 1] =
815                     liftConstantsIntoArray(JavaType.type(lastArgType),
816                                            bsmArgs.subList(bootstrapArgs.length - 4, bsmArgs.size()).toArray());
817         } else {
818             for (int ai = 0; ai < bootstrapArgs.length - 3; ai++) {
819                 bootstrapArgs[ai + 3] = liftConstant(bsmArgs.get(ai));
820             }
821         }
822         return bootstrapArgs;
823     }
824 
825     private void liftSwitch(Label defaultTarget, List<SwitchCase> cases) {
826         Value v = stack.pop();
827         if (!valueType(v).equals(PrimitiveType.INT)) {
828             v = op(JavaOp.conv(PrimitiveType.INT, v));
829         }
830         SwitchCase last = cases.getLast();
831         Block.Builder def = targetBlockForBranch(defaultTarget);
832         for (SwitchCase sc : cases) {
833             if (sc == last) {
834                 op(CoreOp.conditionalBranch(
835                         op(JavaOp.eq(v, liftConstant(sc.caseValue()))),
836                         successorWithStack(targetBlockForBranch(sc.target())),
837                         successorWithStack(def)));
838             } else {
839                 Block.Builder next = entryBlock.block();
840                 op(CoreOp.conditionalBranch(
841                         op(JavaOp.eq(v, liftConstant(sc.caseValue()))),
842                         successorWithStack(targetBlockForBranch(sc.target())),
843                         next.successor()));
844                 currentBlock = next;
845             }
846         }
847         endOfFlow();
848     }
849 
850     private Block.Builder newBlock(List<Block.Parameter> otherBlockParams) {
851         return entryBlock.block(otherBlockParams.stream().map(Block.Parameter::type).toList());
852     }
853 
854     private void endOfFlow() {
855         currentBlock = null;
856         // Flow discontinued, stack cleared to be ready for the next label target
857         stack.clear();
858     }
859 
860     private Block.Builder targetBlockForExceptionHandler(BitSet initialEreStack, int exceptionHandlerIndex) {
861         Block.Builder target = exceptionHandlerBlocks.get(exceptionHandlerIndex);
862         if (target == null) { // Avoid ConcurrentModificationException
863             Label ehLabel = exceptionHandlers.get(exceptionHandlerIndex);
864             target = transitionBlockForTarget(initialEreStack, exceptionHandlersMap.get(ehLabel), blockMap.get(ehLabel), exceptionHandlerIndex);
865             exceptionHandlerBlocks.put(exceptionHandlerIndex, target);
866         }
867         return target;
868     }
869 
870     private Block.Builder targetBlockForBranch(Label targetLabel) {
871         return transitionBlockForTarget(actualEreStack, exceptionHandlersMap.get(targetLabel), blockMap.get(targetLabel), -1);
872     }
873 
874     private Block.Builder transitionBlockForTarget(BitSet initialEreStack, BitSet targetEreStack, Block.Builder targetBlock, int targetExceptionHandlerIndex) {
875         if (targetBlock == null) return null;
876         Block.Builder transitionBlock = newBlock(targetBlock.parameters());
877         ereTransit(initialEreStack, targetEreStack, transitionBlock, targetBlock, transitionBlock.parameters(), targetExceptionHandlerIndex);
878         return transitionBlock;
879     }
880 
881     record EreT(boolean enter, int ehi) {}
882 
883     private void ereTransit(BitSet initialEreStack, BitSet targetEreStack, Block.Builder initialBlock, Block.Builder targetBlock, List<? extends Value> values, int targetExceptionHandlerIndex) {
884         List<EreT> transits = new ArrayList<>();
885         BitSet ereStack = (BitSet)initialEreStack.clone();
886         ereStack.andNot(targetEreStack);
887         // Split region exits by handler stack
888         for (int ehi = ereStack.previousSetBit(Integer.MAX_VALUE); ehi >= 0; ehi = ereStack.previousSetBit(ehi - 1)) {
889             transits.add(new EreT(false, ehi));
890         }
891         ereStack = (BitSet)targetEreStack.clone();
892         ereStack.andNot(initialEreStack);
893         // Split region enters by handler stack
894         for (int ehi = ereStack.nextSetBit(0); ehi >= 0; ehi = ereStack.nextSetBit(ehi + 1)) {
895             transits.add(new EreT(true, ehi));
896         }
897 
898         if (transits.isEmpty()) {
899             // Join with branch
900             initialBlock.op(CoreOp.branch(targetBlock.successor(values)));
901         } else {
902             // Insert ERE transitions
903             Block.Builder currentBlock = initialBlock;
904             ereStack = (BitSet)initialEreStack.clone();
905             for (int i = 0; i < transits.size() - 1; i++) {
906                 EreT t = transits.get(i);
907                 Block.Builder next = entryBlock.block();
908                 ereTransit(initialBlock, currentBlock, t.enter(), next, List.of(), t.ehi(), targetExceptionHandlerIndex, ereStack);
909                 currentBlock = next;
910                 ereStack.set(t.ehi(), t.enter());
911             }
912             EreT t = transits.getLast();
913             ereTransit(initialBlock, currentBlock, t.enter(), targetBlock, values, t.ehi(), targetExceptionHandlerIndex, ereStack);
914         }
915     }
916 
917     private void ereTransit(Block.Builder initialBlock, Block.Builder currentBlock, boolean enter, Block.Builder targetBlock, List<? extends Value> values, int ehi, int targetExceptionHandlerIndex, BitSet handlerEreStack) {
918         Block.Reference ref = targetBlock.successor(values);
919         Block.Reference catcher = (ehi == targetExceptionHandlerIndex
920                 ? initialBlock
921                 : targetBlockForExceptionHandler(handlerEreStack, ehi)).successor();
922         currentBlock.op(enter ? JavaOp.exceptionRegionEnter(ref, catcher) : JavaOp.exceptionRegionExit(ref, catcher));
923     }
924 
925     Block.Reference successorWithStack(Block.Builder next) {
926         return next.successor(stackValues(next));
927     }
928 
929     private List<Value> stackValues(Block.Builder limit) {
930         return stack.stream().limit(limit.parameters().size()).toList();
931     }
932 
933     private static TypeElement valueType(Value v) {
934         var t = v.type();
935         while (t instanceof VarType vt) t = vt.valueType();
936         return t;
937     }
938 
939     private static boolean isCategory1(Value v) {
940         TypeElement t = v.type();
941         return !t.equals(JavaType.LONG) && !t.equals(JavaType.DOUBLE);
942     }
943 
944     private static boolean isUnconditionalBranch(Opcode opcode) {
945         return switch (opcode) {
946             case GOTO, ATHROW, GOTO_W, LOOKUPSWITCH, TABLESWITCH -> true;
947             default -> opcode.kind() == Opcode.Kind.RETURN;
948         };
949     }
950 }