org.jetbrains.kotlin.backend.jvm.lower.MainMethodGenerationLowering.kt Maven / Gradle / Ivy
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/*
* Copyright 2010-2024 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.ClassLoweringPass
import org.jetbrains.kotlin.backend.common.lower.LocalDeclarationsLowering
import org.jetbrains.kotlin.backend.common.lower.createIrBuilder
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.ir.getJvmNameFromAnnotation
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.IrClass
import org.jetbrains.kotlin.ir.declarations.IrSimpleFunction
import org.jetbrains.kotlin.ir.declarations.IrValueParameter
import org.jetbrains.kotlin.ir.expressions.IrExpression
import org.jetbrains.kotlin.ir.expressions.impl.IrConstructorCallImpl
import org.jetbrains.kotlin.ir.expressions.impl.fromSymbolOwner
import org.jetbrains.kotlin.ir.types.*
import org.jetbrains.kotlin.ir.util.*
import org.jetbrains.kotlin.load.java.JavaDescriptorVisibilities
import org.jetbrains.kotlin.name.Name
import org.jetbrains.kotlin.types.Variance
@PhaseDescription(
name = "MainMethodGeneration",
description = "Generate main bridges to parameterless mains, and wrappers for suspend mains.",
prerequisite = [JvmOverloadsAnnotationLowering::class],
)
internal class MainMethodGenerationLowering(private val context: JvmBackendContext) : ClassLoweringPass {
/**
* This pass finds extended main methods and introduces a regular
* `public static void main(String[] args)` entry point, as appropriate:
* - invocation via [kotlin.coroutines.jvm.internal.runSuspend] suspend main methods.
* - a simple delegating wrapper for parameterless main methods
*
* There are three cases that must be handled, in order of precedence:
*
* 1. `suspend fun main(args: Array) { .. }` for which we generate
* ```
* fun main(args: Array) {
* runSuspend { main(args) }
* }
* ```
*
* 2. `suspend fun main() { .. }` for which we generate
* ```
* fun main(args: Array) {
* runSuspend { main() }
* }
* ```
*
* 3. `fun main() { .. }` for which we generate
* ```
* fun main(args: Array) {
* main()
* }
* ```
*/
override fun lower(irClass: IrClass) {
if (!context.config.languageVersionSettings.supportsFeature(LanguageFeature.ExtendedMainConvention)) return
if (!irClass.isFileClass) return
irClass.functions.find { it.isMainMethod() }?.let { mainMethod ->
if (mainMethod.isSuspend) {
irClass.generateMainMethod { newMain, args ->
+irRunSuspend(mainMethod, args, newMain)
}
}
return
}
irClass.functions.find { it.isParameterlessMainMethod() }?.let { parameterlessMainMethod ->
irClass.generateMainMethod { newMain, _ ->
if (parameterlessMainMethod.isSuspend) {
+irRunSuspend(parameterlessMainMethod, null, newMain)
} else {
+irCall(parameterlessMainMethod)
}
}
}
}
private fun IrSimpleFunction.isParameterlessMainMethod(): Boolean =
typeParameters.isEmpty() &&
extensionReceiverParameter == null &&
valueParameters.isEmpty() &&
returnType.isUnit() &&
name.asString() == "main"
private fun IrSimpleFunction.isMainMethod(): Boolean {
if ((getJvmNameFromAnnotation() ?: name.asString()) != "main") return false
if (!returnType.isUnit()) return false
val parameter = allParameters.singleOrNull() ?: return false
if (!parameter.type.isArray() && !parameter.type.isNullableArray()) return false
val argType = (parameter.type as IrSimpleType).arguments.first()
return when (argType) {
is IrTypeProjection -> {
(argType.variance != Variance.IN_VARIANCE) && argType.type.isStringClassType()
}
is IrStarProjection -> false
}
}
private fun IrClass.generateMainMethod(makeBody: IrBlockBodyBuilder.(IrSimpleFunction, IrValueParameter) -> Unit) =
addFunction {
name = Name.identifier("main")
visibility = DescriptorVisibilities.PUBLIC
returnType = context.irBuiltIns.unitType
modality = Modality.OPEN
origin = JvmLoweredDeclarationOrigin.GENERATED_EXTENDED_MAIN
}.apply {
val args = addValueParameter {
name = Name.identifier("args")
type = context.irBuiltIns.arrayClass.typeWith(context.irBuiltIns.stringType)
}
body = context.createIrBuilder(symbol).irBlockBody { makeBody(this@apply, args) }
}
private fun IrBuilderWithScope.irRunSuspend(
target: IrSimpleFunction,
args: IrValueParameter?,
newMain: IrSimpleFunction
): IrExpression {
val backendContext = [email protected]
return irBlock {
val wrapperConstructor = backendContext.irFactory.buildClass {
name = Name.special("")
visibility = JavaDescriptorVisibilities.PACKAGE_VISIBILITY
modality = Modality.FINAL
origin = JvmLoweredDeclarationOrigin.FUNCTION_REFERENCE_IMPL
}.let { wrapper ->
+wrapper
wrapper.createImplicitParameterDeclarationWithWrappedDescriptor()
val lambdaSuperClass = backendContext.ir.symbols.lambdaClass
val functionClass = backendContext.ir.symbols.getJvmSuspendFunctionClass(0)
wrapper.superTypes += lambdaSuperClass.defaultType
wrapper.superTypes += functionClass.typeWith(backendContext.irBuiltIns.anyNType)
wrapper.parent = newMain
val stringArrayType = backendContext.irBuiltIns.arrayClass.typeWith(backendContext.irBuiltIns.stringType)
val argsField = args?.let {
wrapper.addField {
name = Name.identifier("args")
type = stringArrayType
visibility = DescriptorVisibilities.PRIVATE
origin = LocalDeclarationsLowering.DECLARATION_ORIGIN_FIELD_FOR_CAPTURED_VALUE
}
}
wrapper.addFunction("invoke", backendContext.irBuiltIns.anyNType, isSuspend = true).also { invoke ->
val invokeToOverride = functionClass.functions.single()
invoke.overriddenSymbols += invokeToOverride
invoke.body = backendContext.createIrBuilder(invoke.symbol).irBlockBody {
+irReturn(irCall(target.symbol).also { call ->
if (args != null) {
call.putValueArgument(0, irGetField(irGet(invoke.dispatchReceiverParameter!!), argsField!!))
}
})
}
}
wrapper.addConstructor {
isPrimary = true
visibility = JavaDescriptorVisibilities.PACKAGE_VISIBILITY
}.also { constructor ->
val superClassConstructor = lambdaSuperClass.owner.constructors.single()
val param = args?.let { constructor.addValueParameter("args", stringArrayType) }
constructor.body = backendContext.createIrBuilder(constructor.symbol).irBlockBody {
+irDelegatingConstructorCall(superClassConstructor).also {
it.putValueArgument(0, irInt(1))
}
if (args != null) {
+irSetField(irGet(wrapper.thisReceiver!!), argsField!!, irGet(param!!))
}
}
}
}
+irCall(backendContext.ir.symbols.runSuspendFunction).apply {
putValueArgument(
0, IrConstructorCallImpl.fromSymbolOwner(
UNDEFINED_OFFSET,
UNDEFINED_OFFSET,
wrapperConstructor.returnType,
wrapperConstructor.symbol
).also {
if (args != null) {
it.putValueArgument(0, irGet(args))
}
}
)
}
}
}
}