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/*
* Copyright 2010-2020 JetBrains s.r.o. and Kotlin Programming Language contributors.
* Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
*/
package org.jetbrains.kotlin.backend.jvm.lower
import org.jetbrains.kotlin.backend.common.FileLoweringPass
import org.jetbrains.kotlin.backend.common.IrElementTransformerVoidWithContext
import org.jetbrains.kotlin.backend.common.ir.moveBodyTo
import org.jetbrains.kotlin.backend.common.lower.LoweredStatementOrigins
import org.jetbrains.kotlin.backend.common.lower.SamEqualsHashCodeMethodsGenerator
import org.jetbrains.kotlin.backend.common.lower.VariableRemapper
import org.jetbrains.kotlin.backend.common.phaser.PhaseDescription
import org.jetbrains.kotlin.backend.jvm.JvmBackendContext
import org.jetbrains.kotlin.backend.jvm.JvmLoweredDeclarationOrigin
import org.jetbrains.kotlin.backend.jvm.JvmSymbols
import org.jetbrains.kotlin.backend.jvm.ir.*
import org.jetbrains.kotlin.backend.jvm.lower.indy.*
import org.jetbrains.kotlin.config.JvmClosureGenerationScheme
import org.jetbrains.kotlin.config.LanguageFeature
import org.jetbrains.kotlin.descriptors.DescriptorVisibilities
import org.jetbrains.kotlin.descriptors.Modality
import org.jetbrains.kotlin.ir.UNDEFINED_OFFSET
import org.jetbrains.kotlin.ir.builders.*
import org.jetbrains.kotlin.ir.builders.declarations.*
import org.jetbrains.kotlin.ir.declarations.*
import org.jetbrains.kotlin.ir.declarations.impl.IrVariableImpl
import org.jetbrains.kotlin.ir.expressions.*
import org.jetbrains.kotlin.ir.expressions.impl.*
import org.jetbrains.kotlin.ir.symbols.IrClassSymbol
import org.jetbrains.kotlin.ir.symbols.IrFunctionSymbol
import org.jetbrains.kotlin.ir.symbols.impl.IrVariableSymbolImpl
import org.jetbrains.kotlin.ir.types.*
import org.jetbrains.kotlin.ir.util.*
import org.jetbrains.kotlin.ir.visitors.transformChildrenVoid
import org.jetbrains.kotlin.load.java.JvmAnnotationNames
import org.jetbrains.kotlin.name.Name
import org.jetbrains.kotlin.name.SpecialNames
import org.jetbrains.kotlin.resolve.jvm.annotations.JVM_SERIALIZABLE_LAMBDA_ANNOTATION_FQ_NAME
@PhaseDescription(
name = "FunctionReference",
description = "Construct instances of anonymous KFunction subclasses for function references"
)
internal class FunctionReferenceLowering(private val context: JvmBackendContext) : FileLoweringPass, IrElementTransformerVoidWithContext() {
private val crossinlineLambdas = HashSet()
private val IrFunctionReference.isIgnored: Boolean
get() = (!type.isFunctionOrKFunction() && !isSuspendFunctionReference()) || origin == LoweredStatementOrigins.INLINE_LAMBDA
// `suspend` function references are the same as non-`suspend` ones, just with an extra continuation parameter;
// however, suspending lambdas require different generation implemented in SuspendLambdaLowering
// because they are also their own continuation classes.
// TODO: Currently, origin of callable references explicitly written in source code is null. Do we need to create one?
private fun IrFunctionReference.isSuspendFunctionReference(): Boolean = isSuspend &&
(origin == null || origin == IrStatementOrigin.ADAPTED_FUNCTION_REFERENCE || origin == IrStatementOrigin.SUSPEND_CONVERSION)
override fun lower(irFile: IrFile) {
irFile.findInlineLambdas(context) { argument, _, parameter, _ ->
if (parameter.isCrossinline) {
crossinlineLambdas.add(argument.symbol.owner as IrSimpleFunction)
}
}
irFile.transformChildrenVoid(this)
crossinlineLambdas.clear()
}
private val shouldGenerateIndySamConversions =
context.config.samConversionsScheme == JvmClosureGenerationScheme.INDY
private val shouldGenerateIndyLambdas =
context.config.lambdasScheme == JvmClosureGenerationScheme.INDY
private val shouldGenerateLightweightLambdas =
shouldGenerateIndyLambdas && context.config.languageVersionSettings.supportsFeature(LanguageFeature.LightweightLambdas)
private val isJavaSamConversionWithEqualsHashCode =
context.config.languageVersionSettings.supportsFeature(LanguageFeature.JavaSamConversionEqualsHashCode)
override fun visitBlock(expression: IrBlock): IrExpression {
if (!expression.origin.isLambda)
return super.visitBlock(expression)
val reference = expression.statements.last() as IrFunctionReference
if (reference.isIgnored)
return super.visitBlock(expression)
expression.statements.dropLast(1).forEach { it.transform(this, null) }
reference.transformChildrenVoid(this)
if (shouldGenerateIndyLambdas) {
val lambdaMetafactoryArguments =
LambdaMetafactoryArgumentsBuilder(context, crossinlineLambdas)
.getLambdaMetafactoryArguments(reference, reference.type, true)
if (lambdaMetafactoryArguments is LambdaMetafactoryArguments) {
return wrapLambdaReferenceWithIndySamConversion(expression, reference, lambdaMetafactoryArguments)
}
// TODO MetafactoryArgumentsResult.Failure.FunctionHazard?
}
return FunctionReferenceBuilder(reference).build()
}
private fun wrapLambdaReferenceWithIndySamConversion(
expression: IrBlock,
reference: IrFunctionReference,
lambdaMetafactoryArguments: LambdaMetafactoryArguments
): IrBlock {
val indySamConversion = wrapWithIndySamConversion(reference.type, lambdaMetafactoryArguments)
expression.statements[expression.statements.size - 1] = indySamConversion
expression.type = indySamConversion.type
return expression
}
override fun visitFunctionReference(expression: IrFunctionReference): IrExpression {
expression.transformChildrenVoid(this)
return if (expression.isIgnored)
expression
else
FunctionReferenceBuilder(expression).build()
}
private fun getDeclarationParentForDelegatingLambda(): IrDeclarationParent {
for (s in allScopes.asReversed()) {
val scopeOwner = s.scope.scopeOwnerSymbol.owner
if (scopeOwner is IrDeclarationParent) {
return scopeOwner
}
}
throw AssertionError(
"No IrDeclarationParent found in scopes:\n" +
allScopes.joinToString(separator = "\n") { " " + it.scope.scopeOwnerSymbol.owner.render() }
)
}
// Handle SAM conversions which wrap a function reference:
// class sam$n(private val receiver: R) : Interface { override fun method(...) = receiver.target(...) }
//
// This avoids materializing an invokable KFunction representing, thus producing one less class.
// This is actually very common, as `Interface { something }` is a local function + a SAM-conversion
// of a reference to it into an implementation.
override fun visitTypeOperator(expression: IrTypeOperatorCall): IrExpression {
if (expression.operator != IrTypeOperator.SAM_CONVERSION) {
return super.visitTypeOperator(expression)
}
val samSuperType = expression.typeOperand
val invokable = expression.argument
val reference = if (invokable is IrFunctionReference) {
invokable
} else if (invokable is IrBlock && invokable.origin.isLambda && invokable.statements.last() is IrFunctionReference) {
invokable.statements.dropLast(1).forEach { it.transform(this, null) }
invokable.statements.last() as IrFunctionReference
} else if (shouldGenerateIndySamConversions && canGenerateIndySamConversionOnFunctionalExpression(samSuperType, invokable)) {
val lambdaBlock = SamDelegatingLambdaBuilder(context)
.build(invokable, samSuperType, currentScope!!.scope.scopeOwnerSymbol, getDeclarationParentForDelegatingLambda())
val lambdaMetafactoryArguments = LambdaMetafactoryArgumentsBuilder(context, crossinlineLambdas)
.getLambdaMetafactoryArguments(lambdaBlock.ref, samSuperType, false)
if (lambdaMetafactoryArguments !is LambdaMetafactoryArguments) {
// TODO MetafactoryArgumentsResult.Failure.FunctionHazard?
return super.visitTypeOperator(expression)
}
invokable.transformChildrenVoid()
return wrapSamDelegatingLambdaWithIndySamConversion(samSuperType, lambdaBlock, lambdaMetafactoryArguments)
} else {
return super.visitTypeOperator(expression)
}
reference.transformChildrenVoid()
if (shouldGenerateIndySamConversions) {
val lambdaMetafactoryArguments =
LambdaMetafactoryArgumentsBuilder(context, crossinlineLambdas)
.getLambdaMetafactoryArguments(reference, samSuperType, false)
if (lambdaMetafactoryArguments is LambdaMetafactoryArguments) {
return wrapSamConversionArgumentWithIndySamConversion(expression) { samType ->
wrapWithIndySamConversion(samType, lambdaMetafactoryArguments, expression.startOffset, expression.endOffset)
}
} else if (lambdaMetafactoryArguments is MetafactoryArgumentsResult.Failure.FunctionHazard) {
// Try wrapping function with a proxy local function and see if that helps.
val proxyLocalFunBlock = createProxyLocalFunctionForIndySamConversion(reference)
val proxyLocalFunRef = proxyLocalFunBlock.statements[proxyLocalFunBlock.statements.size - 1] as IrFunctionReference
val proxyLambdaMetafactoryArguments = LambdaMetafactoryArgumentsBuilder(context, crossinlineLambdas)
.getLambdaMetafactoryArguments(proxyLocalFunRef, samSuperType, false)
if (proxyLambdaMetafactoryArguments is LambdaMetafactoryArguments) {
return wrapSamConversionArgumentWithIndySamConversion(expression) { samType ->
proxyLocalFunBlock.statements[proxyLocalFunBlock.statements.size - 1] =
wrapWithIndySamConversion(samType, proxyLambdaMetafactoryArguments)
proxyLocalFunBlock.type = samType
proxyLocalFunBlock
}
}
}
}
// Erase generic arguments in the SAM type, because they are not easy to approximate correctly otherwise,
// and LambdaMetafactory also uses erased type.
val erasedSamSuperType = samSuperType.erasedUpperBound.rawType(context)
return FunctionReferenceBuilder(reference, erasedSamSuperType).build()
}
private fun createProxyLocalFunctionForIndySamConversion(reference: IrFunctionReference): IrBlock {
val startOffset = reference.startOffset
val endOffset = reference.endOffset
val targetFun = reference.symbol.owner
// For a function reference with possibly bound value parameters
// [ dispatchReceiver = ..., extensionReceiver = ..., ... ]::foo
// create a proxy wrapper:
// {
// val tmp_proxy_0 =
// ...
// val tmp_proxy_N =
// fun `$proxy`(p_0: TP_0, ..., p_M: TP_M): TR =
// foo(... arg_J ...)
// // here for each J arg_J is either 'tmp_proxy_K' or 'p_K' for some K
// ::`$proxy`
// }
val temporaryVals = ArrayList()
val targetCall: IrFunctionAccessExpression =
when (targetFun) {
is IrSimpleFunction ->
IrCallImpl.fromSymbolOwner(startOffset, endOffset, targetFun.symbol)
is IrConstructor ->
IrConstructorCallImpl.fromSymbolOwner(startOffset, endOffset, targetFun.returnType, targetFun.symbol)
else ->
throw AssertionError("Unexpected callable reference target: ${targetFun.render()}")
}
val proxyFun = context.irFactory.buildFun {
name = Name.identifier("${targetFun.name.asString()}__proxy")
returnType = targetFun.returnType.eraseTypeParameters()
visibility = DescriptorVisibilities.LOCAL
modality = Modality.FINAL
isSuspend = false
isInline = false
origin =
if (targetFun.isInline || targetFun.isArrayOf())
JvmLoweredDeclarationOrigin.PROXY_FUN_FOR_METAFACTORY
else
JvmLoweredDeclarationOrigin.SYNTHETIC_PROXY_FUN_FOR_METAFACTORY
}.also { proxyFun ->
proxyFun.parent = currentDeclarationParent
?: throw AssertionError("No declaration parent when processing $reference")
var temporaryValIndex = 0
var proxyParameterIndex = 0
fun addAndGetTemporaryVal(initializer: IrExpression): IrGetValue {
val tmpVal = IrVariableImpl(
startOffset, endOffset,
IrDeclarationOrigin.IR_TEMPORARY_VARIABLE,
IrVariableSymbolImpl(),
Name.identifier("tmp_proxy_${temporaryValIndex++}"),
initializer.type,
isVar = false, isConst = false, isLateinit = false
)
tmpVal.initializer = initializer
tmpVal.parent = proxyFun.parent
temporaryVals.add(tmpVal)
return IrGetValueImpl(startOffset, endOffset, tmpVal.symbol)
}
fun addAndGetProxyValueParameter(originalParameter: IrValueParameter): IrGetValue {
val proxyParameter = buildValueParameter(proxyFun) {
updateFrom(originalParameter)
name = Name.identifier("p$proxyParameterIndex\$${originalParameter.name.asString()}")
index = proxyParameterIndex
type = originalParameter.type.eraseTypeParameters()
proxyParameterIndex++
}.apply {
parent = proxyFun
}
proxyFun.valueParameters += proxyParameter
return IrGetValueImpl(startOffset, endOffset, proxyParameter.symbol)
}
fun getTargetCallArgument(boundValue: IrExpression?, originalParameter: IrValueParameter?): IrExpression? =
when {
boundValue != null ->
addAndGetTemporaryVal(boundValue)
originalParameter != null ->
addAndGetProxyValueParameter(originalParameter)
else ->
null
}
targetCall.dispatchReceiver = getTargetCallArgument(reference.dispatchReceiver, targetFun.dispatchReceiverParameter)
targetCall.extensionReceiver = getTargetCallArgument(reference.extensionReceiver, targetFun.extensionReceiverParameter)
for ((valueParameterIndex, valueParameter) in targetFun.valueParameters.withIndex()) {
targetCall.putValueArgument(
valueParameterIndex,
getTargetCallArgument(
reference.getValueArgument(valueParameterIndex),
valueParameter
)
)
}
for (typeParameterIndex in targetFun.typeParameters.indices) {
targetCall.putTypeArgument(typeParameterIndex, reference.getTypeArgument(typeParameterIndex))
}
val proxyFunBody = context.irFactory.createBlockBody(startOffset, endOffset).also { proxyFun.body = it }
when {
targetFun.returnType.isUnit() -> {
proxyFunBody.statements.add(targetCall)
}
else -> {
proxyFunBody.statements.add(
IrReturnImpl(
startOffset, endOffset,
context.irBuiltIns.nothingType,
proxyFun.symbol,
targetCall
)
)
}
}
}
val proxyFunRef = IrFunctionReferenceImpl(
startOffset, endOffset,
reference.type,
proxyFun.symbol,
0, // TODO generic function reference?
proxyFun.valueParameters.size
)
return IrBlockImpl(
startOffset, endOffset,
reference.type,
origin = null,
temporaryVals + proxyFun + proxyFunRef
)
}
private fun canGenerateIndySamConversionOnFunctionalExpression(samSuperType: IrType, expression: IrExpression): Boolean {
val samClass = samSuperType.classOrNull
?: throw AssertionError("Class type expected: ${samSuperType.render()}")
if (!samClass.owner.isFromJava() || isJavaSamConversionWithEqualsHashCode)
return false
if (expression is IrBlock && expression.origin == IrStatementOrigin.ADAPTED_FUNCTION_REFERENCE)
return false
return true
}
private fun wrapSamDelegatingLambdaWithIndySamConversion(
samSuperType: IrType,
lambdaBlock: SamDelegatingLambdaBlock,
lambdaMetafactoryArguments: LambdaMetafactoryArguments
): IrExpression {
val indySamConversion = wrapWithIndySamConversion(samSuperType, lambdaMetafactoryArguments)
lambdaBlock.replaceRefWith(indySamConversion)
return lambdaBlock.block
}
private fun wrapSamConversionArgumentWithIndySamConversion(
expression: IrTypeOperatorCall,
produceSamConversion: (IrType) -> IrExpression
): IrExpression {
val samType = expression.typeOperand
return when (val argument = expression.argument) {
is IrFunctionReference ->
produceSamConversion(samType)
is IrBlock ->
wrapFunctionReferenceInsideBlockWithIndySamConversion(samType, argument, produceSamConversion)
else -> throw AssertionError("Block or function reference expected: ${expression.render()}")
}
}
private fun wrapFunctionReferenceInsideBlockWithIndySamConversion(
samType: IrType,
block: IrBlock,
produceSamConversion: (IrType) -> IrExpression
): IrExpression {
val indySamConversion = produceSamConversion(samType)
block.statements[block.statements.size - 1] = indySamConversion
block.type = indySamConversion.type
return block
}
private val jvmIndyLambdaMetafactoryIntrinsic = context.ir.symbols.indyLambdaMetafactoryIntrinsic
private val specialNullabilityAnnotationsFqNames =
setOf(
JvmSymbols.FLEXIBLE_NULLABILITY_ANNOTATION_FQ_NAME,
JvmAnnotationNames.ENHANCED_NULLABILITY_ANNOTATION,
)
private fun wrapWithIndySamConversion(
samType: IrType,
lambdaMetafactoryArguments: LambdaMetafactoryArguments,
startOffset: Int = UNDEFINED_OFFSET,
endOffset: Int = UNDEFINED_OFFSET,
): IrCall {
val notNullSamType = samType.makeNotNull()
.removeAnnotations { it.type.classFqName in specialNullabilityAnnotationsFqNames }
return context.createJvmIrBuilder(currentScope!!, startOffset, endOffset).run {
// See [org.jetbrains.kotlin.backend.jvm.JvmSymbols::indyLambdaMetafactoryIntrinsic].
irCall(jvmIndyLambdaMetafactoryIntrinsic, notNullSamType).apply {
putTypeArgument(0, notNullSamType)
putValueArgument(0, irRawFunctionRef(lambdaMetafactoryArguments.samMethod))
putValueArgument(1, lambdaMetafactoryArguments.implMethodReference)
putValueArgument(2, irRawFunctionRef(lambdaMetafactoryArguments.fakeInstanceMethod))
putValueArgument(3, irVarargOfRawFunctionRefs(lambdaMetafactoryArguments.extraOverriddenMethods))
putValueArgument(4, irBoolean(lambdaMetafactoryArguments.shouldBeSerializable))
}
}
}
private fun IrBuilderWithScope.irRawFunctionRef(irFun: IrFunction) =
irRawFunctionReference(context.irBuiltIns.anyType, irFun.symbol)
private fun IrBuilderWithScope.irVarargOfRawFunctionRefs(irFuns: List) =
irVararg(context.irBuiltIns.anyType, irFuns.map { irRawFunctionRef(it) })
private inner class FunctionReferenceBuilder(val irFunctionReference: IrFunctionReference, val samSuperType: IrType? = null) {
private val isLambda = irFunctionReference.origin.isLambda
private val isLightweightLambda = isLambda
&& shouldGenerateLightweightLambdas
&& !irFunctionReference.symbol.owner.hasAnnotation(JVM_SERIALIZABLE_LAMBDA_ANNOTATION_FQ_NAME)
private val isHeavyweightLambda = isLambda && !isLightweightLambda
private val callee = irFunctionReference.symbol.owner
// Only function references can bind a receiver and even then we can only bind either an extension or a dispatch receiver.
// However, when we bind a value of an inline class type as a receiver, the receiver will turn into an argument of
// the function in question. Yet we still need to record it as the "receiver" in CallableReference in order for reflection
// to work correctly.
private val boundReceiver: Pair? =
if (callee.isJvmStaticInObject()) createFakeBoundReceiverForJvmStaticInObject()
else irFunctionReference.getArgumentsWithIr().singleOrNull()
// The type of the reference is KFunction
private val parameterTypes = (irFunctionReference.type as IrSimpleType).arguments.map {
when (it) {
is IrTypeProjection -> it.type
is IrStarProjection -> context.irBuiltIns.anyNType
}
}
private val argumentTypes = parameterTypes.dropLast(1)
private val referenceReturnType = parameterTypes.last()
private val typeArgumentsMap = irFunctionReference.typeSubstitutionMap
private val functionSuperClass =
samSuperType?.classOrNull
?: if (irFunctionReference.isSuspend)
context.irBuiltIns.suspendFunctionN(argumentTypes.size).symbol
else
context.irBuiltIns.functionN(argumentTypes.size).symbol
private val superMethod =
functionSuperClass.owner.getSingleAbstractMethod()
?: throw AssertionError("Not a SAM class: ${functionSuperClass.owner.render()}")
private val useOptimizedSuperClass =
context.config.generateOptimizedCallableReferenceSuperClasses
// This code is partially duplicated in IrUtils getAdapteeFromAdaptedForReferenceFunction
// The difference is utils version supports ReturnableBlock, but returns called function instead of call node.
private val adapteeCall: IrFunctionAccessExpression? =
if (callee.origin == IrDeclarationOrigin.ADAPTER_FOR_CALLABLE_REFERENCE) {
// The body of a callable reference adapter contains either only a call, or an IMPLICIT_COERCION_TO_UNIT type operator
// applied to a call. That call's target is the original function which we need to get owner/name/signature.
val call = when (val statement = callee.body!!.statements.single()) {
is IrTypeOperatorCall -> {
assert(statement.operator == IrTypeOperator.IMPLICIT_COERCION_TO_UNIT) {
"Unexpected type operator in ADAPTER_FOR_CALLABLE_REFERENCE: ${callee.render()}"
}
statement.argument
}
is IrReturn -> statement.value
else -> statement
}
if (call !is IrFunctionAccessExpression) {
throw UnsupportedOperationException("Unknown structure of ADAPTER_FOR_CALLABLE_REFERENCE: ${callee.render()}")
}
call
} else {
null
}
private val adaptedReferenceOriginalTarget: IrFunction? = adapteeCall?.symbol?.owner
private val isFunInterfaceConstructorReference =
callee.origin == IrDeclarationOrigin.ADAPTER_FOR_FUN_INTERFACE_CONSTRUCTOR
private val constructedFunInterfaceSymbol: IrClassSymbol? =
if (isFunInterfaceConstructorReference)
callee.returnType.classOrNull
?: throw AssertionError("Fun interface type expected: ${callee.returnType.render()}")
else
null
private val isAdaptedReference =
isFunInterfaceConstructorReference || adaptedReferenceOriginalTarget != null
private val samInterface = samSuperType?.getClass()
private val isKotlinFunInterface = samInterface != null && !samInterface.isFromJava()
private val needToGenerateSamEqualsHashCodeMethods =
(isKotlinFunInterface || isJavaSamConversionWithEqualsHashCode) &&
(isAdaptedReference || !isLambda)
private val superType =
samSuperType
?: when {
isLightweightLambda -> context.ir.symbols.any
isHeavyweightLambda -> context.ir.symbols.lambdaClass
isFunInterfaceConstructorReference -> context.ir.symbols.funInterfaceConstructorReferenceClass
useOptimizedSuperClass -> when {
isAdaptedReference -> context.ir.symbols.adaptedFunctionReference
else -> context.ir.symbols.functionReferenceImpl
}
else -> context.ir.symbols.functionReference
}.defaultType
private val functionReferenceClass = context.irFactory.buildClass {
setSourceRange(irFunctionReference)
visibility = DescriptorVisibilities.LOCAL
// A callable reference results in a synthetic class, while a lambda is not synthetic.
// We don't produce GENERATED_SAM_IMPLEMENTATION, which is always synthetic.
origin = if (isLambda) JvmLoweredDeclarationOrigin.LAMBDA_IMPL else JvmLoweredDeclarationOrigin.FUNCTION_REFERENCE_IMPL
name = SpecialNames.NO_NAME_PROVIDED
}.apply {
parent = currentDeclarationParent ?: error("No current declaration parent at ${irFunctionReference.dump()}")
superTypes = listOfNotNull(
superType,
if (samSuperType == null)
functionSuperClass.typeWith(parameterTypes)
else null,
if (needToGenerateSamEqualsHashCodeMethods)
context.ir.symbols.functionAdapter.defaultType
else null,
)
if (samInterface != null && origin == JvmLoweredDeclarationOrigin.LAMBDA_IMPL) {
// Old back-end generates formal type parameters as in SAM supertype.
// Here we create formal type parameters with same names and equivalent upper bounds.
// We don't really perform any type substitutions within class body
// (it's all fine as soon as we have required generic signatures and don't fail anywhere).
// NB this would no longer matter if we generate SAM wrapper classes as synthetic.
typeParameters = createFakeFormalTypeParameters(samInterface.typeParameters, this)
}
createImplicitParameterDeclarationWithWrappedDescriptor()
copyAttributes(irFunctionReference)
if (isHeavyweightLambda) {
metadata = irFunctionReference.symbol.owner.metadata
}
}
private fun createFakeFormalTypeParameters(sourceTypeParameters: List, irClass: IrClass): List {
if (sourceTypeParameters.isEmpty()) return emptyList()
val fakeTypeParameters = sourceTypeParameters.map {
buildTypeParameter(irClass) {
updateFrom(it)
name = it.name
}
}
val typeRemapper = IrTypeParameterRemapper(sourceTypeParameters.associateWith { fakeTypeParameters[it.index] })
for (fakeTypeParameter in fakeTypeParameters) {
val sourceTypeParameter = sourceTypeParameters[fakeTypeParameter.index]
fakeTypeParameter.superTypes = sourceTypeParameter.superTypes.map { typeRemapper.remapType(it) }
}
return fakeTypeParameters
}
fun build(): IrExpression = context.createJvmIrBuilder(currentScope!!).run {
irBlock(irFunctionReference.startOffset, irFunctionReference.endOffset) {
val constructor = createConstructor()
val boundReceiverVar =
if (samSuperType != null && boundReceiver != null) {
irTemporary(boundReceiver.second)
} else null
createInvokeMethod(boundReceiverVar)
if (!isLambda && samSuperType == null && !useOptimizedSuperClass) {
createLegacyMethodOverride(irSymbols.functionReferenceGetSignature.owner) {
generateSignature(callee.symbol)
}
createLegacyMethodOverride(irSymbols.functionReferenceGetName.owner) {
irString(callee.originalName.asString())
}
createLegacyMethodOverride(irSymbols.functionReferenceGetOwner.owner) {
calculateOwner(callee.parent)
}
}
if (needToGenerateSamEqualsHashCodeMethods) {
generateSamEqualsHashCodeMethods(boundReceiverVar)
}
if (isKotlinFunInterface) {
functionReferenceClass.addFakeOverrides(backendContext.typeSystem)
}
+functionReferenceClass
+irCall(constructor.symbol).apply {
if (valueArgumentsCount > 0) putValueArgument(0, boundReceiver!!.second)
}
}
}
private fun JvmIrBuilder.generateSamEqualsHashCodeMethods(boundReceiverVar: IrVariable?) {
checkNotNull(samSuperType) { "equals/hashCode can only be generated for fun interface wrappers: ${callee.render()}" }
if (!useOptimizedSuperClass) {
// This is the case of a fun interface wrapper over a (maybe adapted) function reference,
// with `-Xno-optimized-callable-references` enabled. We can't use constructors of FunctionReferenceImpl,
// so we'd need to basically generate a full class for a reference inheriting from FunctionReference,
// effectively disabling the optimization of fun interface wrappers over references.
// This scenario is probably not very popular because it involves using equals/hashCode on function references
// and enabling the mentioned internal compiler argument.
// Right now we generate them as abstract so that any call would result in AbstractMethodError.
// TODO: generate getFunctionDelegate, equals and hashCode properly in this case
functionReferenceClass.addFunction("equals", backendContext.irBuiltIns.booleanType, Modality.ABSTRACT).apply {
addValueParameter("other", backendContext.irBuiltIns.anyNType)
overriddenSymbols = listOf(functionSuperClass.functions.single { isEqualsFromAny(it.owner) })
}
functionReferenceClass.addFunction("hashCode", backendContext.irBuiltIns.intType, Modality.ABSTRACT).apply {
overriddenSymbols = listOf(functionSuperClass.functions.single { isHashCodeFromAny(it.owner) })
}
return
}
SamEqualsHashCodeMethodsGenerator(backendContext, functionReferenceClass, samSuperType) {
val internalClass = when {
isAdaptedReference -> backendContext.ir.symbols.adaptedFunctionReference
else -> backendContext.ir.symbols.functionReferenceImpl
}
val constructor = internalClass.owner.constructors.single {
// arity, [receiver], owner, name, signature, flags
it.valueParameters.size == 1 + (if (boundReceiver != null) 1 else 0) + 4
}
irCallConstructor(constructor.symbol, emptyList()).apply {
generateConstructorCallArguments(this) { irGet(boundReceiverVar!!) }
}
}.generate()
}
private fun isEqualsFromAny(f: IrSimpleFunction): Boolean =
f.name.asString() == "equals" && f.extensionReceiverParameter == null &&
f.valueParameters.singleOrNull()?.type?.isNullableAny() == true
private fun isHashCodeFromAny(f: IrSimpleFunction): Boolean =
f.name.asString() == "hashCode" && f.extensionReceiverParameter == null && f.valueParameters.isEmpty()
private fun createConstructor(): IrConstructor =
functionReferenceClass.addConstructor {
origin = JvmLoweredDeclarationOrigin.GENERATED_MEMBER_IN_CALLABLE_REFERENCE
returnType = functionReferenceClass.defaultType
isPrimary = true
}.apply {
if (samSuperType == null && boundReceiver != null) {
addValueParameter("receiver", context.irBuiltIns.anyNType)
}
// Super constructor:
// - For fun interface constructor references, super class is kotlin.jvm.internal.FunInterfaceConstructorReference
// with single constructor 'public FunInterfaceConstructorReference(Class funInterface)'
// - For SAM references, the super class is Any
// - For lambdas, accepts arity
// - For optimized function references (1.4+), accepts:
// arity, [receiver], owner, name, signature, flags
// - For unoptimized function references, accepts:
// arity, [receiver]
val constructor =
when {
isFunInterfaceConstructorReference ->
context.ir.symbols.funInterfaceConstructorReferenceClass.owner.constructors.single()
samSuperType != null ->
context.irBuiltIns.anyClass.owner.constructors.single()
else -> {
val expectedArity =
if (isLightweightLambda && !isAdaptedReference) 0
else if (isHeavyweightLambda && !isAdaptedReference) 1
else 1 + (if (boundReceiver != null) 1 else 0) + (if (useOptimizedSuperClass) 4 else 0)
superType.getClass()!!.constructors.single {
it.valueParameters.size == expectedArity
}
}
}
body = context.createJvmIrBuilder(symbol).run {
irBlockBody(startOffset, endOffset) {
+irDelegatingConstructorCall(constructor).also { call ->
if (samSuperType == null) {
generateConstructorCallArguments(call) { irGet(valueParameters.first()) }
}
}
+IrInstanceInitializerCallImpl(startOffset, endOffset, functionReferenceClass.symbol, context.irBuiltIns.unitType)
}
}
}
private fun JvmIrBuilder.generateConstructorCallArguments(
call: IrFunctionAccessExpression,
generateBoundReceiver: IrBuilder.() -> IrExpression
) {
if (isFunInterfaceConstructorReference) {
val funInterfaceKClassRef = kClassReference(constructedFunInterfaceSymbol!!.owner.defaultType)
val funInterfaceJavaClassRef = kClassToJavaClass(funInterfaceKClassRef)
call.putValueArgument(0, funInterfaceJavaClassRef)
} else {
var index = 0
if (!isLightweightLambda) {
call.putValueArgument(index++, irInt(argumentTypes.size + if (irFunctionReference.isSuspend) 1 else 0))
}
if (boundReceiver != null) {
call.putValueArgument(index++, generateBoundReceiver())
}
if (!isLambda && useOptimizedSuperClass) {
val callableReferenceTarget = adaptedReferenceOriginalTarget ?: callee
val owner = calculateOwnerKClass(callableReferenceTarget.parent)
call.putValueArgument(index++, kClassToJavaClass(owner))
call.putValueArgument(index++, irString(callableReferenceTarget.originalName.asString()))
call.putValueArgument(index++, generateSignature(callableReferenceTarget.symbol))
call.putValueArgument(index, irInt(getFunctionReferenceFlags(callableReferenceTarget)))
}
}
}
private fun getFunctionReferenceFlags(callableReferenceTarget: IrFunction): Int {
val isTopLevelBit = callableReferenceTarget.getCallableReferenceTopLevelFlag()
val adaptedCallableReferenceFlags = getAdaptedCallableReferenceFlags()
return isTopLevelBit + (adaptedCallableReferenceFlags shl 1)
}
private fun getAdaptedCallableReferenceFlags(): Int {
if (adaptedReferenceOriginalTarget == null) return 0
val isVarargMappedToElementBit = if (hasVarargMappedToElement()) 1 else 0
val isSuspendConvertedBit = if (!adaptedReferenceOriginalTarget.isSuspend && callee.isSuspend) 1 else 0
val isCoercedToUnitBit = if (!adaptedReferenceOriginalTarget.returnType.isUnit() && callee.returnType.isUnit()) 1 else 0
return isVarargMappedToElementBit +
(isSuspendConvertedBit shl 1) +
(isCoercedToUnitBit shl 2)
}
private fun hasVarargMappedToElement(): Boolean {
if (adapteeCall == null) return false
for (i in 0 until adapteeCall.valueArgumentsCount) {
val arg = adapteeCall.getValueArgument(i) ?: continue
if (arg !is IrVararg) continue
for (varargElement in arg.elements) {
if (varargElement is IrGetValue) return true
}
}
return false
}
private fun createInvokeMethod(receiverVar: IrValueDeclaration?): IrSimpleFunction =
functionReferenceClass.addFunction {
setSourceRange(if (isLambda) callee else irFunctionReference)
name = superMethod.name
returnType = referenceReturnType
isSuspend = callee.isSuspend
}.apply {
metadata = functionReferenceClass.metadata
overriddenSymbols += superMethod.symbol
dispatchReceiverParameter = buildReceiverParameter(
this,
IrDeclarationOrigin.INSTANCE_RECEIVER,
functionReferenceClass.symbol.defaultType
)
when {
isLambda ->
createLambdaInvokeMethod()
isFunInterfaceConstructorReference ->
createFunInterfaceConstructorInvokeMethod()
else ->
createFunctionReferenceInvokeMethod(receiverVar)
}
}
// Inline the body of an anonymous function into the generated lambda subclass.
private fun IrSimpleFunction.createLambdaInvokeMethod() {
annotations += callee.annotations
val valueParameterMap = callee.explicitParameters.withIndex().associate { (index, param) ->
param to param.copyTo(this, index = index)
}
valueParameters += valueParameterMap.values
body = callee.moveBodyTo(this, valueParameterMap)
}
private fun IrSimpleFunction.createFunInterfaceConstructorInvokeMethod() {
val adapterValueParameter = callee.valueParameters.singleOrNull()
?: throw AssertionError("Single value parameter expected: ${callee.render()}")
val invokeValueParameter = adapterValueParameter.copyTo(this, index = 0)
val valueParameterMap = mapOf(adapterValueParameter to invokeValueParameter)
valueParameters = listOf(invokeValueParameter)
body = callee.moveBodyTo(this, valueParameterMap)
callee.body = null
}
private fun IrSimpleFunction.createFunctionReferenceInvokeMethod(receiver: IrValueDeclaration?) {
for ((index, argumentType) in argumentTypes.withIndex()) {
addValueParameter {
name = Name.identifier("p$index")
type = argumentType
}
}
body = context.createJvmIrBuilder(symbol, startOffset, endOffset).run {
var unboundIndex = 0
val call = irCall(callee.symbol, referenceReturnType).apply {
for (typeParameter in irFunctionReference.symbol.owner.allTypeParameters) {
putTypeArgument(typeParameter.index, typeArgumentsMap[typeParameter.symbol])
}
for (parameter in callee.explicitParameters) {
when {
boundReceiver?.first == parameter ->
// Bound receiver parameter. For function references, this is stored in a field of the superclass.
// For sam references, we just capture the value in a local variable and LocalDeclarationsLowering
// will put it into a field.
if (samSuperType == null)
irImplicitCast(
irGetField(
irGet(dispatchReceiverParameter!!),
functionReferenceClass.getReceiverField(backendContext)
),
boundReceiver.second.type
)
else
irGet(receiver!!)
unboundIndex >= argumentTypes.size ->
// Default value argument (this pass doesn't handle suspend functions, otherwise
// it could also be the continuation argument)
null
else ->
irGet(valueParameters[unboundIndex++])
}?.let { putArgument(callee, parameter, it) }
}
}
irExprBody(
inlineAdapterCallIfPossible(call, this@createFunctionReferenceInvokeMethod)
)
}
}
private fun inlineAdapterCallIfPossible(
expression: IrFunctionAccessExpression,
invokeMethod: IrSimpleFunction
): IrExpression {
val irCall = expression as? IrCall
?: return expression
val callee = irCall.symbol.owner
if (callee.origin != IrDeclarationOrigin.ADAPTER_FOR_CALLABLE_REFERENCE)
return expression
// TODO fix testSuspendUnitConversion
if (callee.isSuspend) return expression
// Callable reference adapter is a simple function that delegates to callable reference target,
// adapting its signature for required functional type.
// Usually it simply forwards arguments to target function.
// It also passes 'receiver' field for bound references, with downcast to the actual receiver type.
// In any case, adapter itself is synthetic and is not necessarily debuggable, so we can reuse variables freely.
// Inlining adapter into 'invoke' saves us two methods (adapter & synthetic accessor).
val adapterBody = callee.body as? IrBlockBody
if (adapterBody == null || adapterBody.statements.size != 1)
throw AssertionError("Unexpected adapter body: ${callee.dump()}")
val resultStatement = adapterBody.statements[0]
val resultExpression: IrExpression =
when {
resultStatement is IrReturn ->
resultStatement.value
resultStatement is IrTypeOperatorCall && resultStatement.operator == IrTypeOperator.IMPLICIT_COERCION_TO_UNIT ->
resultStatement
resultStatement is IrCall ->
resultStatement
resultStatement is IrConstructorCall ->
resultStatement
else ->
throw AssertionError("Unexpected adapter body: ${callee.dump()}")
}
val startOffset = irCall.startOffset
val endOffset = irCall.endOffset
val callArguments = LinkedHashMap()
val inlinedAdapterBlock = IrBlockImpl(startOffset, endOffset, irCall.type, origin = null)
var tmpVarIndex = 0
fun wrapIntoTemporaryVariableIfNecessary(expression: IrExpression): IrValueDeclaration {
if (expression is IrGetValue)
return expression.symbol.owner
if (expression !is IrTypeOperatorCall || expression.argument !is IrGetField)
throw AssertionError("Unexpected adapter argument:\n${expression.dump()}")
val temporaryVar = IrVariableImpl(
startOffset, endOffset, IrDeclarationOrigin.IR_TEMPORARY_VARIABLE,
IrVariableSymbolImpl(),
Name.identifier("tmp_${tmpVarIndex++}"),
expression.type,
isVar = false, isConst = false, isLateinit = false
)
temporaryVar.parent = invokeMethod
temporaryVar.initializer = expression
inlinedAdapterBlock.statements.add(temporaryVar)
return temporaryVar
}
callee.dispatchReceiverParameter?.let {
callArguments[it] = wrapIntoTemporaryVariableIfNecessary(
irCall.dispatchReceiver
?: throw AssertionError("No dispatch receiver in adapter call: ${irCall.dump()}")
)
}
callee.extensionReceiverParameter?.let {
callArguments[it] = wrapIntoTemporaryVariableIfNecessary(
irCall.extensionReceiver
?: throw AssertionError("No extension receiver in adapter call: ${irCall.dump()}")
)
}
for (valueParameter in callee.valueParameters) {
callArguments[valueParameter] = wrapIntoTemporaryVariableIfNecessary(
irCall.getValueArgument(valueParameter.index)
?: throw AssertionError("No value argument #${valueParameter.index} in adapter call: ${irCall.dump()}")
)
}
val inlinedAdapterResult = resultExpression.transform(VariableRemapper(callArguments), null)
inlinedAdapterBlock.statements.add(inlinedAdapterResult)
callee.body = null
return inlinedAdapterBlock.patchDeclarationParents(invokeMethod)
}
private fun buildOverride(superFunction: IrSimpleFunction, newReturnType: IrType = superFunction.returnType): IrSimpleFunction =
functionReferenceClass.addFunction {
setSourceRange(irFunctionReference)
origin = JvmLoweredDeclarationOrigin.GENERATED_MEMBER_IN_CALLABLE_REFERENCE
name = superFunction.name
returnType = newReturnType
visibility = superFunction.visibility
isSuspend = superFunction.isSuspend
}.apply {
overriddenSymbols += superFunction.symbol
dispatchReceiverParameter = functionReferenceClass.thisReceiver?.copyTo(this)
}
private val IrFunction.originalName: Name
get() = metadata?.name ?: name
private fun JvmIrBuilder.generateSignature(target: IrFunctionSymbol): IrExpression =
irCall(backendContext.ir.symbols.signatureStringIntrinsic).apply {
putValueArgument(
0,
//don't pass receivers otherwise LocalDeclarationLowering will create additional captured parameters
IrFunctionReferenceImpl(
UNDEFINED_OFFSET, UNDEFINED_OFFSET, irFunctionReference.type, target,
irFunctionReference.typeArgumentsCount, target.owner.valueParameters.size,
irFunctionReference.reflectionTarget, null
).apply {
copyTypeArgumentsFrom(irFunctionReference)
}
)
}
private fun createFakeBoundReceiverForJvmStaticInObject(): Pair {
// JvmStatic functions in objects are special in that they are generated as static methods in the bytecode, and JVM IR lowers
// both declarations and call sites early on in jvmStaticInObjectPhase because it's easier that way in subsequent lowerings.
// However from the point of view of Kotlin language (and thus reflection), these functions still take the dispatch receiver
// parameter of the object type. So we pretend here that a JvmStatic function in object has an additional dispatch receiver
// parameter, so that the correct function reference object will be created and reflective calls will work at runtime.
val objectClass = callee.parentAsClass
return buildValueParameter(callee) {
name = Name.identifier("\$this")
type = objectClass.typeWith()
} to IrGetObjectValueImpl(UNDEFINED_OFFSET, UNDEFINED_OFFSET, objectClass.typeWith(), objectClass.symbol)
}
private fun createLegacyMethodOverride(
superFunction: IrSimpleFunction,
generator: JvmIrBuilder.() -> IrExpression
): IrSimpleFunction =
buildOverride(superFunction).apply {
body = context.createJvmIrBuilder(symbol, startOffset, endOffset).run {
irExprBody(generator())
}
}
}
companion object {
internal fun JvmIrBuilder.calculateOwner(irContainer: IrDeclarationParent): IrExpression {
val kClass = calculateOwnerKClass(irContainer)
if ((irContainer as? IrClass)?.isFileClass != true && irContainer !is IrPackageFragment)
return kClass
return irCall(irSymbols.getOrCreateKotlinPackage).apply {
putValueArgument(0, kClassToJavaClass(kClass))
// Note that this name is not used in reflection. There should be the name of the referenced declaration's
// module instead, but there's no nice API to obtain that name here yet
// TODO: write the referenced declaration's module name and use it in reflection
putValueArgument(1, irString(backendContext.state.moduleName))
}
}
internal fun JvmIrBuilder.calculateOwnerKClass(irContainer: IrDeclarationParent): IrExpression =
kClassReference(irContainer.getCallableReferenceOwnerKClassType(backendContext))
// This method creates an IrField for the field `kotlin.jvm.internal.CallableReference.receiver`, as if this field was declared
// in the anonymous class for this callable reference. Technically it's incorrect because this field is not declared here. It would
// be more correct to create a fake override but that seems like more work for no clear benefit. Codegen will generate the correct
// field access anyway, even if the field is not present in this parent.
// Note that it is necessary to generate an access to the field whose parent is this anonymous class, and NOT some supertype like
// k.j.i.CallableReference, or k.j.i.FunctionReferenceImpl, because then AddSuperQualifierToJavaFieldAccess lowering would add
// superQualifierSymbol, which would break inlining of bound function references, since inliner will not understand how to transform
// this getfield instruction in the bytecode.
internal fun IrClass.getReceiverField(context: JvmBackendContext): IrField =
context.irFactory.buildField {
name = Name.identifier("receiver")
type = context.irBuiltIns.anyNType
visibility = DescriptorVisibilities.PROTECTED
}.apply {
parent = this@getReceiverField
}
}
}