IR (中间表示)

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

IR（中间表示）是 Kotlin 编译器管道中的一个关键组件，它作为前端（解析和分析）与后端（代码生成）之间的通用代码表示。本页面将介绍 IR 的结构和目的、如何对其应用转换，以及它如何实现 Kotlin 的跨平台编译。

IR 位于 Kotlin 编译器的中间阶段，在前端从源代码生成结构化表示之后，但在特定于后端的代码生成之前。有关前端 IR (FIR) 的信息，请参阅页面 FIR (前端 IR)。

IR 结构和组织

IR 以树状结构表示 Kotlin 代码，该结构在保留所有必要代码生成信息的同时，抽象化了源代码的语法。

来源：compiler/ir/ir.inline/src/org/jetbrains/kotlin/ir/inline/FunctionInlining.kt19-33 compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/util/IrInlineUtils.kt8-13

关键组件

1. 声明：定义程序结构（类、函数、属性）

   • IrClass：表示类、接口、对象、枚举类
   • IrFunction：所有类函数声明的基类
   • IrProperty：具有关联的 getter/setter 的属性
   • IrVariable：局部变量

2. 表达式：表示产生值的计算

   • IrCall：函数调用
   • IrGetValue/IrSetValue：变量访问/赋值
   • IrReturn：return 语句
   • IrWhen：条件表达式

3. 符号：充当声明的引用

   • IrClassSymbol：类引用
   • IrFunctionSymbol：函数引用
   • 符号可以是“绑定的”（指向声明）或“未绑定的”（占位符）

4. 类型：指定表达式产生的值的种类

   • IrSimpleType：常规类型（类、接口）
   • IrDynamicType：动态类型（主要用于 JavaScript）

5. 签名：声明的唯一标识符

   • IdSignature：用于跨模块链接和序列化

来源：compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/DeclarationTable.kt12-59 compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/signature/IdSignatureComputers.kt22-59

IR 转换和下推

IR 创建后，它会经历许多称为“下推”（lowerings）的转换，这些转换会修改 IR 树，逐步为代码生成做好准备。

来源：kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/driver/phases/NativeLoweringPhases.kt149-176 compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/JsLoweringPhases.kt747-779 compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/WasmLoweringPhases.kt149-186

函数内联

最重要的转换之一是函数内联，它在适当转换后用函数体替换对内联函数的调用。这分为两个阶段：

1. 内联私有函数：处理私有内联函数的第一个阶段
2. 内联所有函数：处理所有其他内联函数的第二个阶段

来源：compiler/ir/ir.inline/src/org/jetbrains/kotlin/ir/inline/FunctionInlining.kt37-134 compiler/ir/ir.inline/src/org/jetbrains/kotlin/ir/inline/InlineFunctionResolver.kt27-74 compiler/ir/ir.inline/src/org/jetbrains/kotlin/ir/inline/CommonInlineCallableReferenceToLambdaPhase.kt7-14

IR 阶段的函数内联支持多项重要功能：

• 跨模块内联（使用依赖项中的内联函数）
• Reified 类型参数的类型特化
• Lambda 参数内联
• 正确处理 Lambda 中的 return 语句

来源：compiler/ir/ir.inline/src/org/jetbrains/kotlin/ir/inline/InlineCallableReferenceToLambda.kt36-98 kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/lower/NativeIrInliner.kt12-18

其他关键转换

除了函数内联，IR 还经历许多其他转换：

• 默认参数：转换带默认参数的函数
• 枚举处理：将枚举类转换为具有静态字段的常规类
• 局部函数：将局部函数提升为顶层函数，支持闭包
• 类型操作：实现类型检查、类型转换和 reified 类型操作
• Tailrec：将尾递归函数转换为循环
• Suspend 函数：将挂起函数转换为状态机
• 属性访问器：处理属性的 getter 和 setter
• 特定平台转换：为目标平台准备代码

来源：kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/driver/phases/NativeLoweringPhases.kt551-615

IR 序列化

IR 可以被序列化以支持增量编译、多模块项目和库分发。

来源：compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/IrFileSerializer.kt114-205 compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/serializeModuleIntoKlib.kt1-40

序列化组件

1. IrFileSerializer：将 IR 文件序列化为 protobuf 格式
2. IrDeclarationSerializer：序列化声明（类、函数、属性）
3. IrBodySerializer：序列化函数体（表达式和语句）
4. Protocol Buffers：用于高效二进制表示的格式
5. KLIB：Kotlin 库格式，包含序列化的 IR 和元数据

来源：compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/IrSerializationSettings.kt36-46 compiler/ir/serialization.common/src/KotlinIr.proto1-2

反序列化和链接

当消费序列化的 IR 时

1. 声明结构：首先被重建
2. 符号表：构建用于跟踪声明
3. 延迟体反序列化：函数体按需加载
4. 符号链接：引用连接到声明

对于内联函数，存在特殊的反序列化器，可以在需要内联时按需加载函数体。

来源：compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/IrFileDeserializer.kt1-6 compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/IrBodyDeserializer.kt1-35 compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/NonLinkingIrInlineFunctionDeserializer.kt24-35

多平台支持

IR 通过提供可独立于平台转换的通用表示，实现了 Kotlin 的多平台能力

1. 平台无关的转换
2. 由平台特定的优化进一步处理
3. 序列化到可被不同后端使用的库中

来源：compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/klib.kt80-109 native/native.tests/tests/org/jetbrains/kotlin/konan/test/NativeKlibSerializerFacade.kt40-61

每个后端（JVM、JS、Native、WebAssembly）都有处理平台特定要求的特定 IR 降低阶段，但它们都从相同的通用 IR 结构开始。

来源：kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/FirNativeSerializer.kt1-5 js/js.tests/test/org/jetbrains/kotlin/benchmarks/GenerateIrRuntime.kt77-109 compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/WasmLoweringPhases.kt34-61

函数内联过程详解

函数内联是 IR 阶段最复杂的转换之一。该过程包括

来源：compiler/ir/ir.inline/src/org/jetbrains/kotlin/ir/inline/FunctionInlining.kt136-201 compiler/ir/ir.inline/src/org/jetbrains/kotlin/ir/inline/FunctionInlining.kt37-61

函数内联的关键步骤

1. 检测：识别内联函数的调用
2. 解析：查找函数体（可能来自库）
3. 转换:
   • 用实参替换形参
   • 处理 return 语句
   • 处理嵌套的内联函数
4. 集成：将转换后的函数体插入调用点

函数内联分两个阶段进行，以正确处理依赖关系

• 首先，仅内联 private 函数
• 然后，如有必要，生成合成访问器
• 最后，内联所有剩余的函数

来源：compiler/ir/ir.inline/src/org/jetbrains/kotlin/ir/inline/CommonLoweringPhases.kt54-63 compiler/ir/ir.inline/src/org/jetbrains/kotlin/ir/inline/CommonLoweringPhases.kt103-140

IR 对 IDE 和工具的支持

虽然 IR 主要用于编译，但也支持工具

1. 增量编译：仅重新编译已更改的内容
2. IDE 功能：代码分析和重构
3. 调试信息：行号和源映射
4. 错误报告：精确的错误位置

IR 结构保留了足够多的关于原始源代码的信息，可以支持这些功能，同时仍然是一个可优化的中间表示。

来源：compiler/ir/backend.jvm/codegen/src/org/jetbrains/kotlin/backend/jvm/codegen/ExpressionCodegen.kt204-208

结论

IR 是 Kotlin 编译器的骨干，它实现了

1. 平台无关的优化
2. 目标特定的代码生成
3. 跨模块内联和其他高级功能
4. 库格式，用于分发编译后的代码

它的设计允许 Kotlin 在所有目标平台保持相同的语言语义，同时仍然为每个平台生成最佳代码。

来源：compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/ir/IrInlineUtils.kt25-64