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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.ir.moveBodyTo
import org.jetbrains.kotlin.backend.common.lower.LocalDeclarationsLowering
import org.jetbrains.kotlin.backend.common.lower.LoweredDeclarationOrigins
import org.jetbrains.kotlin.backend.common.lower.createIrBuilder
import org.jetbrains.kotlin.backend.common.peek
import org.jetbrains.kotlin.backend.common.phaser.PhaseDescription
import org.jetbrains.kotlin.backend.common.pop
import org.jetbrains.kotlin.backend.common.push
import org.jetbrains.kotlin.backend.jvm.*
import org.jetbrains.kotlin.backend.jvm.ir.*
import org.jetbrains.kotlin.codegen.coroutines.*
import org.jetbrains.kotlin.codegen.inline.coroutines.FOR_INLINE_SUFFIX
import org.jetbrains.kotlin.descriptors.DescriptorVisibilities
import org.jetbrains.kotlin.descriptors.Modality
import org.jetbrains.kotlin.ir.IrElement
import org.jetbrains.kotlin.ir.IrStatement
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.expressions.*
import org.jetbrains.kotlin.ir.expressions.impl.*
import org.jetbrains.kotlin.ir.symbols.IrFunctionSymbol
import org.jetbrains.kotlin.ir.symbols.IrSimpleFunctionSymbol
import org.jetbrains.kotlin.ir.types.IrType
import org.jetbrains.kotlin.ir.types.defaultType
import org.jetbrains.kotlin.ir.types.extractTypeParameters
import org.jetbrains.kotlin.ir.types.typeWith
import org.jetbrains.kotlin.ir.util.*
import org.jetbrains.kotlin.ir.visitors.*
import org.jetbrains.kotlin.load.java.JavaDescriptorVisibilities
import org.jetbrains.kotlin.name.Name
import org.jetbrains.kotlin.util.OperatorNameConventions
import org.jetbrains.org.objectweb.asm.Type
@PhaseDescription(
name = "AddContinuation",
description = "Add continuation classes and parameters to suspend functions",
prerequisite = [SuspendLambdaLowering::class, JvmLocalDeclarationsLowering::class, TailCallOptimizationLowering::class]
)
internal class AddContinuationLowering(context: JvmBackendContext) : SuspendLoweringUtils(context), FileLoweringPass {
override fun lower(irFile: IrFile) {
addContinuationObjectAndContinuationParameterToSuspendFunctions(irFile)
addContinuationParameterToSuspendCalls(irFile)
}
private fun addContinuationParameterToSuspendCalls(irFile: IrFile) {
irFile.transformChildrenVoid(object : IrElementTransformerVoid() {
val functionStack = mutableListOf()
override fun visitFunction(declaration: IrFunction): IrStatement {
functionStack.push(declaration)
return super.visitFunction(declaration).also { functionStack.pop() }
}
override fun visitFunctionReference(expression: IrFunctionReference): IrExpression {
val transformed = super.visitFunctionReference(expression) as IrFunctionReference
// The only references not yet transformed into objects are inline lambdas; the continuation
// for those will be taken from the inline functions they are passed to, not the enclosing scope.
return transformed.retargetToSuspendView(context, null) {
IrFunctionReferenceImpl.fromSymbolOwner(startOffset, endOffset, type, it, typeArgumentsCount, reflectionTarget, origin)
}
}
override fun visitCall(expression: IrCall): IrExpression {
val transformed = super.visitCall(expression) as IrCall
return transformed.retargetToSuspendView(context, functionStack.peek() ?: return transformed) {
IrCallImpl.fromSymbolOwner(
startOffset, endOffset, type, it,
origin = origin, superQualifierSymbol = superQualifierSymbol
)
}
}
})
}
private fun generateContinuationClassForNamedFunction(
irFunction: IrFunction,
dispatchReceiverParameter: IrValueParameter?,
attributeContainer: IrAttributeContainer,
capturesCrossinline: Boolean
): IrClass =
context.irFactory.buildClass {
name = Name.special("")
origin = JvmLoweredDeclarationOrigin.CONTINUATION_CLASS
visibility = if (capturesCrossinline) DescriptorVisibilities.PUBLIC else JavaDescriptorVisibilities.PACKAGE_VISIBILITY
}.apply {
createImplicitParameterDeclarationWithWrappedDescriptor()
superTypes += context.ir.symbols.continuationImplClass.owner.defaultType
parent = irFunction
copyTypeParametersFrom(irFunction)
val resultField = addField {
origin = JvmLoweredDeclarationOrigin.CONTINUATION_CLASS_RESULT_FIELD
name = Name.identifier(CONTINUATION_RESULT_FIELD_NAME)
type = context.ir.symbols.resultOfAnyType
visibility = JavaDescriptorVisibilities.PACKAGE_VISIBILITY
}
val capturedThisField = dispatchReceiverParameter?.let {
addField {
name = Name.identifier("this$0")
type = it.type
origin = IrDeclarationOrigin.FIELD_FOR_OUTER_THIS
visibility = JavaDescriptorVisibilities.PACKAGE_VISIBILITY
isFinal = true
}
}
val labelField = addField(COROUTINE_LABEL_FIELD_NAME, context.irBuiltIns.intType, JavaDescriptorVisibilities.PACKAGE_VISIBILITY)
addConstructorForNamedFunction(capturedThisField, capturesCrossinline)
addInvokeSuspendForNamedFunction(
irFunction,
resultField,
labelField,
capturedThisField,
irFunction.origin == JvmLoweredDeclarationOrigin.SUSPEND_IMPL_STATIC_FUNCTION
)
copyAttributes(attributeContainer)
}
private fun IrClass.addConstructorForNamedFunction(capturedThisField: IrField?, capturesCrossinline: Boolean): IrConstructor =
addConstructor {
isPrimary = true
returnType = defaultType
visibility = if (capturesCrossinline) DescriptorVisibilities.PUBLIC else JavaDescriptorVisibilities.PACKAGE_VISIBILITY
}.also { constructor ->
val capturedThisParameter = capturedThisField?.let { constructor.addValueParameter(it.name.asString(), it.type) }
val completionParameterSymbol = constructor.addCompletionValueParameter()
val superClassConstructor = context.ir.symbols.continuationImplClass.owner.constructors.single { it.valueParameters.size == 1 }
constructor.body = context.createIrBuilder(constructor.symbol).irBlockBody {
if (capturedThisField != null) {
+irSetField(irGet(thisReceiver!!), capturedThisField, irGet(capturedThisParameter!!))
}
+irDelegatingConstructorCall(superClassConstructor).also {
it.putValueArgument(0, irGet(completionParameterSymbol))
}
}
}
private fun IrClass.addInvokeSuspendForNamedFunction(
irFunction: IrFunction,
resultField: IrField,
labelField: IrField,
capturedThisField: IrField?,
isStaticSuspendImpl: Boolean
) {
val backendContext = context
val invokeSuspend = context.ir.symbols.continuationImplClass.owner.functions
.single { it.name == Name.identifier(INVOKE_SUSPEND_METHOD_NAME) }
addFunctionOverride(invokeSuspend, irFunction.startOffset, irFunction.endOffset) { function ->
+irSetField(irGet(function.dispatchReceiverParameter!!), resultField, irGet(function.valueParameters[0]))
// There can be three kinds of suspend function call:
// 1) direct call from another suspend function/lambda
// 2) resume of coroutines via resumeWith call on continuation object
// 3) recursive call
// To distinguish case 1 from 2 and 3, we use simple INSTANCEOF check.
// However, this check shows the same in cases 2 and 3.
// Thus, we flip sign bit of label field in case 2 and leave it untouched in case 3.
// Since this is literally case 2 (resumeWith calls invokeSuspend), flip the bit.
val signBit = 1 shl 31
+irSetField(
irGet(function.dispatchReceiverParameter!!), labelField,
irCallOp(
context.irBuiltIns.intClass.functions.single { it.owner.name == OperatorNameConventions.OR },
context.irBuiltIns.intType,
irGetField(irGet(function.dispatchReceiverParameter!!), labelField),
irInt(signBit)
)
)
+irReturn(irCall(irFunction).also {
for (i in irFunction.typeParameters.indices) {
it.putTypeArgument(i, typeParameters[i].defaultType)
}
val capturedThisValue = capturedThisField?.let { irField ->
irGetField(irGet(function.dispatchReceiverParameter!!), irField)
}
if (irFunction.dispatchReceiverParameter != null) {
it.dispatchReceiver = capturedThisValue
}
irFunction.extensionReceiverParameter?.let { extensionReceiverParameter ->
it.extensionReceiver = extensionReceiverParameter.type.defaultValue(
UNDEFINED_OFFSET, UNDEFINED_OFFSET, backendContext
)
}
for ((i, parameter) in irFunction.valueParameters.dropLast(1).withIndex()) {
it.putValueArgument(i, parameter.type.defaultValue(UNDEFINED_OFFSET, UNDEFINED_OFFSET, backendContext))
}
it.putValueArgument(
irFunction.valueParameters.size - 1,
IrGetValueImpl(UNDEFINED_OFFSET, UNDEFINED_OFFSET, function.dispatchReceiverParameter!!.symbol)
)
if (isStaticSuspendImpl) {
it.putValueArgument(0, capturedThisValue)
}
})
}
}
private fun Name.toSuspendImplementationName(): Name =
Name.guessByFirstCharacter(asString() + SUSPEND_IMPL_NAME_SUFFIX)
private fun createStaticSuspendImpl(irFunction: IrSimpleFunction): IrSimpleFunction {
// Create static suspend impl method.
val static = context.irFactory.createStaticFunctionWithReceivers(
irFunction.parent,
irFunction.name.toSuspendImplementationName(),
irFunction,
origin = JvmLoweredDeclarationOrigin.SUSPEND_IMPL_STATIC_FUNCTION,
modality = Modality.OPEN,
visibility = if (irFunction.parentAsClass.isJvmInterface)
DescriptorVisibilities.PUBLIC
else
JavaDescriptorVisibilities.PACKAGE_VISIBILITY,
isFakeOverride = false,
copyMetadata = false,
typeParametersFromContext = extractTypeParameters(irFunction.parentAsClass),
remapMultiFieldValueClassStructure = context::remapMultiFieldValueClassStructure
)
static.body = irFunction.moveBodyTo(static)
// Fixup dispatch parameter to outer class
if (irFunction.parentAsClass.isInner) {
val movedDispatchParameter = static.valueParameters[0]
assert(movedDispatchParameter.origin == IrDeclarationOrigin.MOVED_DISPATCH_RECEIVER) {
"MOVED_DISPATCH_RECEIVER should be the first parameter in ${static.render()}"
}
static.body!!.transformChildrenVoid(object : IrElementTransformerVoid() {
override fun visitGetValue(expression: IrGetValue): IrExpression {
val owner = expression.symbol.owner
if (owner is IrValueParameter && isInstanceReceiverOfOuterClass(owner)) {
// If inner class has inner classes, we need to traverse this$0 chain to get to captured dispatch receivers
var cursor = irFunction.parentAsClass
var value: IrExpression = IrGetValueImpl(expression.startOffset, expression.endOffset, movedDispatchParameter.symbol)
while (cursor != owner.parent) {
val outerThisField = context.innerClassesSupport.getOuterThisField(cursor)
value = IrGetFieldImpl(
expression.startOffset, expression.endOffset, outerThisField.symbol, outerThisField.type, value
)
cursor = cursor.parentAsClass
}
return value
}
return super.visitGetValue(expression)
}
private fun isInstanceReceiverOfOuterClass(param: IrValueParameter): Boolean {
if (param.origin != IrDeclarationOrigin.INSTANCE_RECEIVER) return false
if (param.parent !is IrClass) return false
var cursor = irFunction.parentAsClass.parent
while (cursor is IrClass) {
if (cursor == param.parent) return true
@Suppress("USELESS_CAST") // K2 warning suppression, TODO: KT-62472
cursor = (cursor as IrClass).parent
}
return false
}
})
}
static.copyAttributes(irFunction)
// Rewrite the body of the original suspend method to forward to the new static method.
irFunction.body = context.createIrBuilder(irFunction.symbol).irBlockBody {
+irReturn(irCall(static).also {
for (i in irFunction.typeParameters.indices) {
it.putTypeArgument(i, context.irBuiltIns.anyNType)
}
var i = 0
if (irFunction.dispatchReceiverParameter != null) {
it.putValueArgument(i++, irGet(irFunction.dispatchReceiverParameter!!))
}
if (irFunction.extensionReceiverParameter != null) {
it.putValueArgument(i++, irGet(irFunction.extensionReceiverParameter!!))
}
for (parameter in irFunction.valueParameters) {
it.putValueArgument(i++, irGet(parameter))
}
})
}
return static
}
private fun addContinuationObjectAndContinuationParameterToSuspendFunctions(irFile: IrFile) {
irFile.accept(object : IrElementTransformerVoid() {
override fun visitClass(declaration: IrClass): IrStatement {
declaration.transformDeclarationsFlat {
if (it is IrSimpleFunction && it.isSuspend)
return@transformDeclarationsFlat transformToView(it)
it.accept(this, null)
null
}
return declaration
}
private fun transformToView(function: IrSimpleFunction): List {
function.accept(this, null)
val capturesCrossinline = function.isCapturingCrossinline()
val view = function.suspendFunctionViewOrStub(context)
val continuationParameter = view.continuationParameter()
val parameterMap = function.explicitParameters.zip(view.explicitParameters.filter { it != continuationParameter }).toMap()
view.body = function.moveBodyTo(view, parameterMap)
val result = mutableListOf(view)
if (function.body == null || !function.hasContinuation()) return result
// Sometimes, suspend methods of SAM adapters or function references require a continuation class.
// However, the attribute owner is used to store the name of the SAM adapter or the function reference itself.
// So here we add a local class name using the suspend method itself as the key.
if (function.parentAsClass.origin == JvmLoweredDeclarationOrigin.LAMBDA_IMPL ||
function.parentAsClass.origin == JvmLoweredDeclarationOrigin.FUNCTION_REFERENCE_IMPL
) {
val newType = Type.getObjectType("${function.parentAsClass.localClassType!!.internalName}$${function.name}$1")
function.localClassType = newType
}
if (capturesCrossinline || function.isInline) {
result += context.irFactory.buildFun {
containerSource = view.containerSource
name = Name.identifier(context.defaultMethodSignatureMapper.mapFunctionName(view) + FOR_INLINE_SUFFIX)
returnType = view.returnType
modality = view.modality
isSuspend = view.isSuspend
isInline = view.isInline
visibility = if (view.isInline) DescriptorVisibilities.PRIVATE else view.visibility
origin =
if (view.isInline) JvmLoweredDeclarationOrigin.FOR_INLINE_STATE_MACHINE_TEMPLATE
else JvmLoweredDeclarationOrigin.FOR_INLINE_STATE_MACHINE_TEMPLATE_CAPTURES_CROSSINLINE
}.apply {
copyAnnotationsFrom(view)
copyParameterDeclarationsFrom(view)
context.remapMultiFieldValueClassStructure(view, this, parametersMappingOrNull = null)
copyAttributes(view)
generateErrorForInlineBody()
}
}
val newFunction = if (function.isOverridable) {
// Create static method for the suspend state machine method so that reentering the method
// does not lead to virtual dispatch to the wrong method.
createStaticSuspendImpl(view).also { result += it }
} else view
newFunction.body = context.createIrBuilder(newFunction.symbol).irBlockBody {
+generateContinuationClassForNamedFunction(
newFunction,
view.dispatchReceiverParameter,
function as IrAttributeContainer,
capturesCrossinline
)
if (newFunction.body is IrExpressionBody) {
+irReturn(newFunction.body!!.statements[0] as IrExpression)
} else {
for (statement in newFunction.body!!.statements) {
+statement
}
}
}
return result
}
private fun IrSimpleFunction.isCapturingCrossinline(): Boolean {
var capturesCrossinline = false
(this.originalBeforeInline ?: this).acceptVoid(object : IrElementVisitorVoid {
override fun visitElement(element: IrElement) {
element.acceptChildrenVoid(this)
}
override fun visitFieldAccess(expression: IrFieldAccessExpression) {
if (expression.symbol.owner.origin == LocalDeclarationsLowering.DECLARATION_ORIGIN_FIELD_FOR_CROSSINLINE_CAPTURED_VALUE) {
capturesCrossinline = true
return
}
super.visitFieldAccess(expression)
}
override fun visitClass(declaration: IrClass) {
return
}
})
return capturesCrossinline
}
}, null)
}
}
// Transform `suspend fun foo(params): RetType` into `fun foo(params, $completion: Continuation): Any?`
// the result is called 'view', just to be consistent with old backend.
private fun IrSimpleFunction.suspendFunctionViewOrStub(context: JvmBackendContext): IrSimpleFunction {
if (!isSuspend) return this
// If superinterface is in another file, the bridge to default method will already have continuation parameter,
// so skip it. See KT-47549.
if (origin == JvmLoweredDeclarationOrigin.SUPER_INTERFACE_METHOD_BRIDGE &&
overriddenSymbols.singleOrNull()?.owner?.valueParameters?.lastOrNull()?.origin == JvmLoweredDeclarationOrigin.CONTINUATION_CLASS
) return this
// We need to use suspend function originals here, since if we use 'this' here,
// turing FlowCollector into 'fun interface' leads to AbstractMethodError. See KT-49294.
return context.suspendFunctionOriginalToView.getOrPut(suspendFunctionOriginal()) { createSuspendFunctionStub(context) }
}
private fun IrSimpleFunction.createSuspendFunctionStub(context: JvmBackendContext): IrSimpleFunction {
require(this.isSuspend)
return factory.buildFun {
updateFrom(this@createSuspendFunctionStub)
name = [email protected]
origin = [email protected]
returnType = context.irBuiltIns.anyNType
}.also { function ->
function.parent = parent
function.annotations += annotations
function.metadata = metadata
function.contextReceiverParametersCount = contextReceiverParametersCount
function.copyAttributes(this)
function.copyTypeParametersFrom(this)
val substitutionMap = makeTypeParameterSubstitutionMap(this, function)
function.copyReceiverParametersFrom(this, substitutionMap)
function.overriddenSymbols += overriddenSymbols.map { it.owner.suspendFunctionViewOrStub(context).symbol }
// The continuation parameter goes before the default argument mask(s) and handler for default argument stubs.
// TODO: It would be nice if AddContinuationLowering could insert the continuation argument before default stub generation.
val index = valueParameters.firstOrNull { it.origin == IrDeclarationOrigin.MASK_FOR_DEFAULT_FUNCTION }?.index
?: valueParameters.size
function.valueParameters += valueParameters.take(index).map {
it.copyTo(function, index = it.index, type = it.type.substitute(substitutionMap))
}
val continuationParameter = function.addValueParameter(
SUSPEND_FUNCTION_COMPLETION_PARAMETER_NAME,
continuationType(context).substitute(substitutionMap),
JvmLoweredDeclarationOrigin.CONTINUATION_CLASS
)
function.valueParameters += valueParameters.drop(index).map {
it.copyTo(function, index = it.index + 1, type = it.type.substitute(substitutionMap))
}
context.remapMultiFieldValueClassStructure(
this, function,
parametersMappingOrNull = explicitParameters.zip(function.explicitParameters.filter { it != continuationParameter }).toMap()
)
}
}
private fun IrFunction.continuationType(context: JvmBackendContext): IrType {
// For SuspendFunction{N}.invoke we need to generate INVOKEINTERFACE Function{N+1}.invoke(...Ljava/lang/Object;)...
// instead of INVOKEINTERFACE Function{N+1}.invoke(...Lkotlin/coroutines/Continuation;)...
val isInvokeOfNumberedSuspendFunction = (parent as? IrClass)?.defaultType?.isSuspendFunction() == true
val isInvokeOfNumberedFunction = (parent as? IrClass)?.fqNameWhenAvailable?.asString()?.let {
it.startsWith("kotlin.jvm.functions.Function") && it.removePrefix("kotlin.jvm.functions.Function").all { c -> c.isDigit() }
} == true
return if (isInvokeOfNumberedSuspendFunction || isInvokeOfNumberedFunction)
context.irBuiltIns.anyNType
else
context.ir.symbols.continuationClass.typeWith(returnType)
}
private fun > T.retargetToSuspendView(
context: JvmBackendContext,
caller: IrFunction?,
copyWithTargetSymbol: T.(IrSimpleFunctionSymbol) -> T
): T {
// Calls inside continuation are already generated with continuation parameter as well as calls to suspendImpls
val owner = symbol.owner
if (owner !is IrSimpleFunction || !owner.isSuspend || caller?.isInvokeSuspendOfContinuation() == true
|| owner.origin == JvmLoweredDeclarationOrigin.SUSPEND_IMPL_STATIC_FUNCTION
|| owner.continuationParameter() != null
) return this
val view = owner.suspendFunctionViewOrStub(context)
if (view == owner) return this
// While the new callee technically returns ` | COROUTINE_SUSPENDED`, the latter case is handled
// by a method visitor so at an IR overview we don't need to consider it.
return copyWithTargetSymbol(view.symbol).also {
it.copyAttributes(this)
it.copyTypeArgumentsFrom(this)
it.dispatchReceiver = dispatchReceiver
it.extensionReceiver = extensionReceiver
val continuationParameter = view.continuationParameter()!!
for (i in 0 until valueArgumentsCount) {
it.putValueArgument(i + if (i >= continuationParameter.index) 1 else 0, getValueArgument(i))
}
if (caller != null) {
val continuation = if (caller.origin == LoweredDeclarationOrigins.INLINE_LAMBDA)
IrCompositeImpl(UNDEFINED_OFFSET, UNDEFINED_OFFSET, continuationParameter.type, JvmLoweredStatementOrigin.FAKE_CONTINUATION)
else
IrGetValueImpl(
UNDEFINED_OFFSET, UNDEFINED_OFFSET, caller.continuationParameter()?.symbol
?: throw AssertionError("${caller.render()} has no continuation; can't call ${owner.render()}")
)
it.putValueArgument(continuationParameter.index, continuation)
}
}
}