编译器中端

相关源文件

• analysis/decompiled/decompiler-native/src/org/jetbrains/kotlin/analysis/decompiler/konan/KlibMetadataDeserializerForDecompiler.kt
• compiler/cli/src/org/jetbrains/kotlin/cli/metadata/MetadataUtils.kt
• compiler/fir/entrypoint/src/org/jetbrains/kotlin/fir/pipeline/Fir2KlibMetadataSerializer.kt
• compiler/frontend.common/src/org/jetbrains/kotlin/util/klibMetadataHelpers.kt
• compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/DisposableContext.kt
• compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/ir/IrInlineUtils.kt
• compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/InventNamesForLocalClasses.kt
• compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/inline/AvoidLocalFOsInInlineFunctionsLowering.kt
• compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/JsLoweringPhases.kt
• compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/CallableReferenceLowering.kt
• compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/InteropCallableReferenceLowering.kt
• compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/JsInventNamesForLocalClasses.kt
• compiler/ir/backend.jvm/codegen/src/org/jetbrains/kotlin/backend/jvm/codegen/ExpressionCodegen.kt
• compiler/ir/backend.jvm/codegen/src/org/jetbrains/kotlin/backend/jvm/codegen/LineNumberMapper.kt
• compiler/ir/backend.jvm/entrypoint/src/org/jetbrains/kotlin/backend/jvm/JvmIrSerializerImpl.kt
• compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/AddContinuationLowering.kt
• compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/CreateSeparateCallForInlinedLambdasLowering.kt
• compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/FakeLocalVariablesForIrInlinerLowering.kt
• compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/FunctionReferenceLowering.kt
• compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/JvmInlineCallableReferenceToLambdaPhase.kt
• compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/JvmIrInliner.kt
• compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/JvmTailrecLowering.kt
• compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/MarkNecessaryInlinedClassesAsRegeneratedLowering.kt
• compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/RemoveDuplicatedInlinedLocalClassesLowering.kt
• compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/SyntheticAccessorLowering.kt
• compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/ir/JvmIrInlineUtils.kt
• compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/WasmLoweringPhases.kt
• compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/ic/FileSignatureRemover.kt
• compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/lower/WasmFunctionInlining.kt
• compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/lower/WasmInlineCallableReferenceToLambdaPhase.kt
• compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/lower/WasmInlineFunctionResolver.kt
• compiler/ir/ir.inline/build.gradle.kts
• compiler/ir/ir.inline/src/org/jetbrains/kotlin/ir/inline/CommonInlineCallableReferenceToLambdaPhase.kt
• compiler/ir/ir.inline/src/org/jetbrains/kotlin/ir/inline/CommonLoweringPhases.kt
• compiler/ir/ir.inline/src/org/jetbrains/kotlin/ir/inline/FunctionInlining.kt
• compiler/ir/ir.inline/src/org/jetbrains/kotlin/ir/inline/InlineCallableReferenceToLambda.kt
• compiler/ir/ir.inline/src/org/jetbrains/kotlin/ir/inline/InlineFunctionBodyPreprocessor.kt
• compiler/ir/ir.inline/src/org/jetbrains/kotlin/ir/inline/InlineFunctionResolver.kt
• compiler/ir/ir.inline/src/org/jetbrains/kotlin/ir/inline/InlineFunctionSerializationPreProcessing.kt
• compiler/ir/ir.inline/src/org/jetbrains/kotlin/ir/inline/konan/NativeFirstPhaseLoweringPhases.kt
• compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/util/IdSignature.kt
• compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/util/IrInlineUtils.kt
• compiler/ir/serialization.common/src/KotlinIr.proto
• compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/linkage/partial/PartialLinkageSupportForLinker.kt
• compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/linkage/partial/PartialLinkageSupportForLinkerImpl.kt
• compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/overrides/FakeOverrides.kt
• compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/BasicIrModuleDeserializer.kt
• compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/DeclarationTable.kt
• compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/IdSignatureDeserializer.kt
• compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/IdSignatureSerializer.kt
• compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/IrBodyDeserializer.kt
• compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/IrDeclarationDeserializer.kt
• compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/IrDeserializationSettings.kt
• compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/IrFileDeserializer.kt
• compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/IrFileSerializer.kt
• compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/IrModuleSerializer.kt
• compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/IrSerializationSettings.kt
• compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/NonLinkingIrInlineFunctionDeserializer.kt
• compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/encodings/BinaryFlags.kt
• compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/proto/IrFile.java
• compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/proto/IrFileOrBuilder.java
• compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/proto/IrInlinedFunctionBlock.java
• compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/proto/IrInlinedFunctionBlockOrBuilder.java
• compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/proto/IrOperation.java
• compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/proto/IrOperationOrBuilder.java
• compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/proto/IrRichFunctionReference.java
• compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/proto/IrRichFunctionReferenceOrBuilder.java
• compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/proto/IrRichPropertyReference.java
• compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/proto/IrRichPropertyReferenceOrBuilder.java
• compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/serializeModuleIntoKlib.kt
• compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/signature/IdSignatureBuilder.kt
• compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/signature/IdSignatureComputers.kt
• compiler/ir/serialization.js/src/org/jetbrains/kotlin/ir/backend/js/KlibMetadataIncrementalSerializer.kt
• compiler/ir/serialization.js/src/org/jetbrains/kotlin/ir/backend/js/klib.kt
• compiler/ir/serialization.js/src/org/jetbrains/kotlin/ir/backend/js/lower/serialization/ir/JsDeclarationTable.kt
• compiler/ir/serialization.js/src/org/jetbrains/kotlin/ir/backend/js/lower/serialization/ir/JsIrFileSerializer.kt
• compiler/ir/serialization.js/src/org/jetbrains/kotlin/ir/backend/js/lower/serialization/ir/JsIrModuleSerializer.kt
• compiler/ir/serialization.jvm/src/org/jetbrains/kotlin/backend/jvm/serialization/JvmGlobalDeclarationTable.kt
• compiler/ir/serialization.jvm/src/org/jetbrains/kotlin/backend/jvm/serialization/JvmIrSerializerSession.kt
• compiler/ir/serialization.jvm/src/org/jetbrains/kotlin/backend/jvm/serialization/deserializeLazyDeclarations.kt
• compiler/ir/serialization.native/src/org/jetbrains/kotlin/backend/konan/serialization/KonanDeclarationTable.kt
• compiler/ir/serialization.native/src/org/jetbrains/kotlin/backend/konan/serialization/KonanIrFileSerializer.kt
• compiler/ir/serialization.native/src/org/jetbrains/kotlin/backend/konan/serialization/KonanIrModuleSerializer.kt
• compiler/testData/codegen/box/inline/kt67024.kt
• compiler/testData/codegen/box/inline/kt67866.kt
• compiler/testData/codegen/box/inline/kt69041.kt
• compiler/testData/codegen/box/nonLocalReturns/suspendConversion.kt
• compiler/testData/codegen/boxInline/anonymousObject/kt65503.kt
• compiler/testData/codegen/boxInline/anonymousObject/kt65503_2.kt
• compiler/testData/codegen/boxInline/callableReference/adaptedReferences/inlineVarargWithLetCall.kt
• compiler/testData/codegen/boxInline/enclosingInfo/kt52417.kt
• compiler/testData/codegen/boxInline/functionReference/fourthOrder.kt
• compiler/testData/codegen/boxInline/functionReference/noInlineForLambda.kt
• compiler/testData/codegen/boxInline/functionReference/thirdOrder.kt
• compiler/testData/klib/syntheticAccessors/topLevelPrivate/singleFile/effectivelyPrivateInlineFun.accessors.txt
• compiler/testData/klib/syntheticAccessors/topLevelPrivate/singleFile/effectivelyPrivateInlineFun.kt
• compiler/tests-common/tests/org/jetbrains/kotlin/test/KlibTestUtil.kt
• compiler/util-klib-metadata/src/org/jetbrains/kotlin/library/metadata/KlibMetadataClassDataFinder.kt
• compiler/util-klib-metadata/src/org/jetbrains/kotlin/library/metadata/KlibMetadataPackageFragment.kt
• js/js.tests/test/org/jetbrains/kotlin/benchmarks/GenerateIrRuntime.kt
• js/js.translator/testData/box/closure/inlineAnonymousFunctions/superInLambda.kt
• js/js.translator/testData/incremental/invalidation/inlineFunctionAsFunctionReference/project.info
• kotlin-native/Interop/StubGenerator/src/org/jetbrains/kotlin/native/interop/gen/jvm/InteropLibraryCreation.kt
• kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/FirNativeSerializer.kt
• kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/driver/DynamicCompilerDriver.kt
• kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/driver/phases/Fir2Ir.kt
• kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/driver/phases/FirFrontend.kt
• kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/driver/phases/FirSerializer.kt
• kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/driver/phases/NativeLoweringPhases.kt
• kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/driver/phases/Serializer.kt
• kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/driver/phases/TopLevelPhases.kt
• kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/driver/phases/WriteKlib.kt
• kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/lower/NativeInlineFunctionResolver.kt
• kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/lower/NativeInventNamesForLocalClasses.kt
• kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/lower/NativeIrInliner.kt
• kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/lower/ReturnsInsertionLowering.kt
• native/commonizer/tests/org/jetbrains/kotlin/commonizer/utils/mocks.kt
• native/native.tests/klib-ir-inliner/tests-gen/org/jetbrains/kotlin/konan/test/syntheticAccessors/FirNativeKlibSyntheticAccessorTestGenerated.java
• native/native.tests/klib-ir-inliner/tests/org/jetbrains/kotlin/konan/test/inlining/AbstractNativeUnboundIrSerializationTest.kt
• native/native.tests/testData/codegen/fileCheck/kt49847_generic_receiver.kt
• native/native.tests/tests/org/jetbrains/kotlin/konan/test/NativeKlibSerializerFacade.kt

本页面介绍 Kotlin 编译器的中端，重点关注介于前端（PSI/FIR）和后端（代码生成）之间的 IR 转换和优化管道。

有关 IR 结构本身的详细信息，请参阅 IR 中间表示。

目的与范围

Kotlin 编译器的中端负责转换和优化 Kotlin 代码的中间表示（IR）。其主要职责包括：

1. 应用一系列转换（lowering）来简化高级 Kotlin 结构
2. 通过函数内联和常量计算等操作优化代码
3. 在不同阶段验证 IR 以确保正确性
4. 为序列化或代码生成准备 IR

中端在前端生成的 IR 上运行，并输出优化的 IR，然后由后端处理以生成目标代码（JVM 字节码、JavaScript、原生代码或 WebAssembly）。

IR 转换管道

中端通过一系列称为“lowering”的转换来处理 IR。每个 lowering 专注于代码的特定方面。管道在所有平台（JVM、JS、Native、WASM）上都类似，但具有特定于平台的变体。

通用 lowering 管道

来源：[kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/driver/phases/NativeLoweringPhases.kt], [compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/JsLoweringPhases.kt], [compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/WasmLoweringPhases.kt]

关键 lowering 阶段

1. lateinitPhase：转换 Kotlin 的 lateinit 属性。
2. sharedVariablesLoweringPhase：处理 lambda 中捕获的变量。
3. localClassesInInlineLambdasPhase：从内联 lambda 中提取局部类。
4. arrayConstructorPhase：转换数组构造器。
5. inlineOnlyPrivateFunctionsPhase：内联私有的内联函数。
6. outerThisSpecialAccessorInInlineFunctionsPhase：为内联函数中的外部 this 引用创建访问器。
7. syntheticAccessorGenerationPhase：为私有成员创建访问器。
8. inlineAllFunctionsPhase：内联所有剩余的内联函数。
9. constEvaluationPhase：在编译时计算常量表达式。

这些阶段中的每一个都实现为对 IR 树的转换，通常扩展 FileLoweringPass 或 IrElementTransformerVoidWithContext。

来源：[compiler/ir/ir.inline/src/org/jetbrains/kotlin/ir/inline/CommonLoweringPhases.kt], [kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/driver/phases/NativeLoweringPhases.kt]

函数内联

函数内联是中端中最复杂和最重要的转换之一。它用实际的函数体替换标记为 inline 的函数的调用。

内联过程架构

来源：[compiler/ir/ir.inline/src/org/jetbrains/kotlin/ir/inline/FunctionInlining.kt]

主要组件

函数内联系统由几个关键类组成：

1. FunctionInlining：协调内联过程的主要类。它遍历 IR 树并识别需要内联的函数调用。

2. CallInlining：处理特定函数调用的实际内联，包括参数求值、参数替换和 return 语句的转换。

3. InlineFunctionResolver：确定要内联哪些函数以及如何处理它们的接口。

来源：[compiler/ir/ir.inline/src/org/jetbrains/kotlin/ir/inline/FunctionInlining.kt:38-134], [compiler/ir/ir.inline/src/org/jetbrains/kotlin/ir/inline/FunctionInlining.kt:136-748], [compiler/ir/ir.inline/src/org/jetbrains/kotlin/ir/inline/InlineFunctionResolver.kt]

两阶段内联

内联分两个阶段进行：

1. 私有函数阶段：仅内联私有的内联函数。这是必要的，因为在生成合成访问器等其他转换之前，私有函数可能在所有调用站点都不可访问。

2. 所有函数阶段：在生成合成访问器后，内联所有剩余的内联函数。

在这两个阶段之间，会生成合成访问器并进行验证。这种两阶段方法可确保所有内联函数都能正确内联。

来源：[compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/WasmLoweringPhases.kt:154-186], [compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/JsLoweringPhases.kt:200-235], [kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/driver/phases/NativeLoweringPhases.kt:339-366]

函数调用内联过程

函数调用的实际内联由 CallInlining 类处理。该类执行以下步骤：

1. 准备内联函数：复制函数体并处理类型参数。

2. 求值参数：对内联函数的参数进行求值并存储在临时变量中。

3. 创建内联函数块：一个表示内联函数的专用 IR 块。

4. 转换 return 语句：重写 return 语句，使其从内联块返回，而不是从原始函数返回。

5. 处理参数替换：将参数引用替换为相应的参数。

6. 递归内联 lambda：如果函数接收 lambda 参数，也会对这些 lambda 进行内联。

结果是一个包含内联函数体的 IR 块，其中所有参数引用都已替换为参数，并且所有 return 语句都已重写为从内联块返回。

来源：[compiler/ir/ir.inline/src/org/jetbrains/kotlin/ir/inline/FunctionInlining.kt:136-748]

处理可调用引用和 lambda

一个特殊的转换应用于传递给内联函数的k可调用引用和 lambda。这由 InlineCallableReferenceToLambdaPhase 处理。

此转换：

1. 为被引用的函数创建一个包装器函数
2. 设置参数转发
3. 创建一个引用包装器函数的 lambda 块

来源：[compiler/ir/ir.inline/src/org/jetbrains/kotlin/ir/inline/InlineCallableReferenceToLambda.kt]

用于内联函数的 IR 序列化

内联函数需要在编译使用它们的其他模块时可用。这需要在 IR 序列化过程中进行特殊处理。

序列化架构

来源：[compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/IrFileSerializer.kt], [compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/NonLinkingIrInlineFunctionDeserializer.kt]

序列化设置

序列化过程由 IrSerializationSettings 控制，该设置决定要序列化什么。

主要设置包括

• publicAbiOnly：是否仅序列化公共 API。
• bodiesOnlyForInlines：是否仅序列化内联函数的函数体。
• reuseExistingSignaturesForSymbols：是否为符号重用现有签名。

来源：[compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/IrSerializationSettings.kt]

对内联函数的特殊处理

IrFileSerializer 类即使在仅序列化公共 API 时也会序列化内联函数的函数体。

对于反序列化，NonLinkingIrInlineFunctionDeserializer 会按需反序列化内联函数的函数体。

来源：[compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/IrFileSerializer.kt], [compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/NonLinkingIrInlineFunctionDeserializer.kt]

特定平台实现

每个平台（JVM、JS、Native、WASM）都有其自己的中端管道实现，并针对目标平台进行了特定调整。

原生

Native 平台使用 NativeIrInliner 来处理函数内联。

来源：[kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/lower/NativeIrInliner.kt]

JavaScript

JS 平台实现了自己的内联器和解析器。

来源：[compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/JsLoweringPhases.kt:226-235]

WebAssembly

WASM 平台有自己的实现，专注于 WebAssembly 特定的问题。

来源：[compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/WasmLoweringPhases.kt:177-186]

结论

Kotlin 编译器的中端是一个用于转换和优化 IR 的复杂系统。函数内联是该过程的核心部分，它能带来性能改进和其他优化。中端以模块化的方式实现，跨平台共享通用组件，并根据需要进行特定于平台的调整。