Convert lambdas to method references when javac compiles a method reference to a lambda #532
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,260 @@ | ||
| package org.jetbrains.java.decompiler.modules.decompiler; | ||
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| import org.jetbrains.java.decompiler.code.CodeConstants; | ||
| import org.jetbrains.java.decompiler.code.FullInstructionSequence; | ||
| import org.jetbrains.java.decompiler.code.Instruction; | ||
| import org.jetbrains.java.decompiler.main.ClassesProcessor; | ||
| import org.jetbrains.java.decompiler.main.ClassesProcessor.ClassNode; | ||
| import org.jetbrains.java.decompiler.main.ClassesProcessor.ClassNode.LambdaInformation; | ||
| import org.jetbrains.java.decompiler.main.DecompilerContext; | ||
| import org.jetbrains.java.decompiler.modules.decompiler.exps.*; | ||
| import org.jetbrains.java.decompiler.modules.decompiler.stats.RootStatement; | ||
| import org.jetbrains.java.decompiler.modules.decompiler.stats.Statement; | ||
| import org.jetbrains.java.decompiler.struct.StructClass; | ||
| import org.jetbrains.java.decompiler.struct.StructMethod; | ||
| import org.jetbrains.java.decompiler.struct.consts.LinkConstant; | ||
| import org.jetbrains.java.decompiler.util.InterpreterUtil; | ||
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| import java.io.IOException; | ||
| import java.util.Iterator; | ||
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| public class MethodReferenceHelper { | ||
| public static boolean convertToMethodReference(RootStatement root) throws IOException { | ||
| return convertToMethodReferenceRec(root); | ||
| } | ||
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| public static boolean convertToMethodReferenceRec(Statement stat) throws IOException { | ||
| boolean result = false; | ||
| for (Statement subStat : stat.getStats()) { | ||
| result |= convertToMethodReferenceRec(subStat); | ||
| } | ||
| if (stat.getExprents() != null) { | ||
| for (int i = 0; i < stat.getExprents().size(); i++) { | ||
| Exprent exp = stat.getExprents().get(i); | ||
| for (Exprent subExp : exp.getAllExprents(true)) { | ||
| if (convertToMethodReference(stat, i, subExp)) { | ||
| result |= true; | ||
| } | ||
| for (int j = 0; j < stat.getExprents().size(); j++) { | ||
| if (stat.getExprents().get(j) == exp) { | ||
| i = j; | ||
| break; | ||
| } | ||
| } | ||
| if (removeInstanceAssignment(stat, i, subExp)) { | ||
| result |= true; | ||
| } | ||
| for (int j = 0; j < stat.getExprents().size(); j++) { | ||
| if (stat.getExprents().get(j) == exp) { | ||
| i = j; | ||
| break; | ||
| } | ||
| } | ||
| } | ||
| } | ||
| } | ||
| return result; | ||
| } | ||
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| private static boolean convertToMethodReference(Statement stat, int i, Exprent exp) throws IOException { | ||
| if (!(exp instanceof NewExprent newExprent) | ||
| || !newExprent.isLambda() | ||
| || newExprent.isMethodReference()) | ||
| return false; | ||
| String className = newExprent.getNewType().value; | ||
| ClassNode node = DecompilerContext.getClassProcessor().getMapRootClasses().get(className); | ||
| LambdaInformation info = node.lambdaInformation; | ||
| StructClass struct = DecompilerContext.getStructContext().getClass(info.content_class_name); | ||
| StructMethod method = struct.getMethod(info.content_method_key); | ||
| if (!method.hasModifier(CodeConstants.ACC_STATIC)) | ||
| return false; | ||
| method.expandData(struct); | ||
|
Member
There was a problem hiding this comment. Hmm, does this need to manually parse the instructions or would going through the exprents suffice?
Contributor
Author
There was a problem hiding this comment. The I did consider doing it when the lambda is written to the output like with array constructor references but that would prevent inlining the variable since if it happened when the lambda is written nothing in |
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| FullInstructionSequence seq = method.getInstructionSequence(); | ||
| Iterator<Instruction> iterator = seq.iterator(); | ||
| int argument = 0; | ||
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| if (!iterator.hasNext()) | ||
| return false; | ||
| Instruction next = iterator.next(); | ||
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| // new instance | ||
| if (next.opcode == CodeConstants.opc_new) { | ||
| if (!iterator.hasNext()) | ||
| return false; | ||
| next = iterator.next(); | ||
| if (next.opcode != CodeConstants.opc_dup) | ||
| return false; | ||
|
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| if (!iterator.hasNext()) | ||
| return false; | ||
| next = iterator.next(); | ||
| } | ||
|
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| // Load arguments | ||
| while (iterator.hasNext() | ||
| && next.opcode >= CodeConstants.opc_iload && next.opcode <= CodeConstants.opc_aload | ||
| && next.operand(0) == argument) { | ||
| next = iterator.next(); | ||
| argument++; | ||
| } | ||
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| boolean varargs = false; | ||
|
Contributor
Author
There was a problem hiding this comment. The |
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| int varargsCount = 0; | ||
| // varargs array length | ||
| if (next.opcode >= CodeConstants.opc_bipush && next.opcode <= CodeConstants.opc_sipush) { | ||
| varargsCount = next.operand(0); | ||
| varargs = true; | ||
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| // varargs array creation | ||
| if (!iterator.hasNext()) | ||
| return false; | ||
| next = iterator.next(); | ||
| if (next.opcode < CodeConstants.opc_newarray || next.opcode > CodeConstants.opc_anewarray) | ||
| return false; | ||
| for (int j = 0; j < varargsCount; j++) { | ||
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| // duplicate varargs array | ||
| if (!iterator.hasNext()) | ||
| return false; | ||
| next = iterator.next(); | ||
| if (next.opcode != CodeConstants.opc_dup) | ||
| return false; | ||
|
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| // varargs array index | ||
| if (!iterator.hasNext()) | ||
| return false; | ||
| next = iterator.next(); | ||
| if (next.opcode < CodeConstants.opc_bipush || next.opcode > CodeConstants.opc_sipush | ||
| || next.operand(0) != j) | ||
| return false; | ||
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| // load argument for varargs array | ||
| if (!iterator.hasNext()) | ||
| return false; | ||
| next = iterator.next(); | ||
| if (next.opcode < CodeConstants.opc_iload || next.opcode > CodeConstants.opc_aload | ||
| || next.operand(0) != argument + j) | ||
| return false; | ||
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| // store argument in varargs array | ||
| if (!iterator.hasNext()) | ||
| return false; | ||
| next = iterator.next(); | ||
| if (next.opcode < CodeConstants.opc_iastore || next.opcode > CodeConstants.opc_sastore) | ||
| return false; | ||
| } | ||
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| if (!iterator.hasNext()) | ||
| return false; | ||
| next = iterator.next(); | ||
| } | ||
| // invoke method | ||
| if (next.opcode < CodeConstants.opc_invokevirtual || next.opcode > CodeConstants.opc_invokeinterface) | ||
| return false; | ||
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| Instruction invoke = next; | ||
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| if (!iterator.hasNext()) | ||
| return false; | ||
| next = iterator.next(); | ||
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| if (next.opcode == CodeConstants.opc_pop) { | ||
| if (!iterator.hasNext()) | ||
| return false; | ||
| next = iterator.next(); | ||
| } | ||
|
|
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| // return | ||
| if (next.opcode < CodeConstants.opc_ireturn || next.opcode > CodeConstants.opc_return) | ||
| return false; | ||
|
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| if (iterator.hasNext()) | ||
| return false; | ||
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| LinkConstant link = struct.getPool().getLinkConstant(invoke.operand(0)); | ||
| boolean instance = invoke.opcode != CodeConstants.opc_invokestatic | ||
| && !link.elementname.equals(CodeConstants.INIT_NAME); | ||
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| String newClass = link.classname; | ||
| String newMethod = link.elementname; | ||
| String newDescriptor = link.descriptor; | ||
| String newKey = InterpreterUtil.makeUniqueKey(newMethod, newDescriptor); | ||
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| StructClass newStructClass = DecompilerContext.getStructContext().getClass(newClass); | ||
| if (newStructClass == null) | ||
| return false; | ||
| StructMethod newStructMethod = newStructClass.getMethodRecursive(newMethod, newDescriptor); | ||
| if (newStructMethod == null) | ||
| return false; | ||
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| if (newStructMethod.hasModifier(CodeConstants.ACC_SYNTHETIC)) | ||
| return false; | ||
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| ClassNode newNode = DecompilerContext.getClassProcessor().getMapRootClasses().get(newClass); | ||
| if (newNode != null && newNode.type == ClassesProcessor.ClassNode.Type.ANONYMOUS) | ||
| return false; | ||
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| if (method.methodDescriptor().params.length - (varargs ? varargsCount - 1 : 0) != newStructMethod.methodDescriptor().params.length + (instance ? 1 : 0)) | ||
| return false; | ||
| if (newExprent.getConstructor().getLstParameters().size() > (instance ? 1 : 0)) | ||
| return false; | ||
| info.content_class_name = newClass; | ||
| info.content_method_name = newMethod; | ||
| info.content_method_descriptor = newDescriptor; | ||
| info.content_method_invocation_type = switch (invoke.opcode) { | ||
| case CodeConstants.opc_invokevirtual -> CodeConstants.CONSTANT_MethodHandle_REF_invokeVirtual; | ||
| case CodeConstants.opc_invokespecial -> instance ? CodeConstants.CONSTANT_MethodHandle_REF_newInvokeSpecial : CodeConstants.CONSTANT_MethodHandle_REF_invokeSpecial; | ||
| case CodeConstants.opc_invokestatic -> CodeConstants.CONSTANT_MethodHandle_REF_invokeStatic; | ||
| case CodeConstants.opc_invokeinterface -> CodeConstants.CONSTANT_MethodHandle_REF_invokeInterface; | ||
| default -> -1; | ||
| }; | ||
| info.content_method_key = newKey; | ||
| info.is_method_reference = true; | ||
| info.is_content_method_static = invoke.opcode == CodeConstants.opc_invokestatic; | ||
| newExprent.setMethodReference(true); | ||
| InvocationExprent constructor = newExprent.getConstructor(); | ||
| if (instance && constructor.getLstParameters().size() == 1) { | ||
| constructor.setInstance(constructor.getLstParameters().get(0)); | ||
| } | ||
|
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| if (i > 0) { | ||
| Exprent instanceExp = newExprent.getConstructor().getInstance(); | ||
| Exprent previous = stat.getExprents().get(i - 1); | ||
| if (instanceExp instanceof VarExprent varExp | ||
| && previous instanceof AssignmentExprent assignment | ||
| && varExp.equalsVersions(assignment.getLeft()) | ||
| && !varExp.isVarReferenced(stat.getTopParent(), (VarExprent) assignment.getLeft())) { | ||
| newExprent.getConstructor().setInstance(assignment.getRight()); | ||
| newExprent.getConstructor().getLstParameters().set(0, assignment.getRight()); | ||
| stat.getExprents().remove(i - 1); | ||
| } | ||
| } | ||
| return true; | ||
| } | ||
|
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| private static boolean removeInstanceAssignment(Statement stat, int i, Exprent exp) { | ||
| if (exp instanceof NewExprent newExp | ||
| && newExp.isLambda() | ||
| && newExp.isMethodReference() | ||
| && i >= 2 | ||
| && newExp.getConstructor().getInstance() instanceof VarExprent stackVar | ||
| && stackVar.isStack()) { | ||
| Exprent nonNull = stat.getExprents().get(i - 1); | ||
| Exprent assign = stat.getExprents().get(i - 2); | ||
| if (nonNull instanceof InvocationExprent inv | ||
| && inv.getClassname().equals("java/util/Objects") | ||
| && inv.getName().equals("requireNonNull") | ||
| && inv.getStringDescriptor().equals("(Ljava/lang/Object;)Ljava/lang/Object;") | ||
| && stackVar.equalsVersions(inv.getLstParameters().get(0)) | ||
| && assign instanceof AssignmentExprent stackAssign | ||
| && stackVar.equalsVersions(stackAssign.getLeft())) { | ||
| newExp.getConstructor().setInstance(stackAssign.getRight()); | ||
| newExp.getConstructor().getLstParameters().set(0, stackAssign.getRight()); | ||
| stat.getExprents().remove(i - 1); | ||
| stat.getExprents().remove(i - 2); | ||
| return true; | ||
| } | ||
| } | ||
| return false; | ||
| } | ||
| } | ||
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This appears to also modify existing lambdas which could be represented with a method reference. Perhaps it should be behind a decompiler option