book

LLVM Techniques, Tips, and Best Practices Clang and Middle-End Libraries

by Min-Yih Hsu

April 2021

Intermediate to advanced

370 pages

7h 34m

English

Packt Publishing

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ContributorsAbout the authorAbout the reviewer
Who this book is forWhat this book coversTo get the most out of this bookDownload the example code filesDownload the color imagesConventions usedGet in touchReviews
Technical requirementsCutting down building resources with better toolingReplacing GNU Make with NinjaAvoiding the use of the BFD linkerTweaking CMake argumentsChoosing the right build typeAvoiding building all targetsBuilding as shared librariesSplitting the debug infoBuilding an optimized version of llvm-tblgenUsing the new PassManager and ClangUsing GN for a faster turnaround timeSummaryFurther reading
Technical requirementsExploring a glossary of LLVM's important CMake directivesUsing the CMake function to add new librariesUsing the CMake function to add executables and toolsUsing the CMake function to add Pass pluginsUnderstanding CMake integration for out-of-tree projectsSummary
Technical requirementsUsing LIT in out-of-tree projectsPreparing for our example project Writing LIT configurationsLIT internalsLearning useful FileCheck tricksPreparing for our example projectWriting FileCheck directivesExploring the TestSuite frameworkPreparing for our example projectImporting code into llvm-test-suiteSummaryFurther reading
Technical requirementsIntroduction to TableGen syntaxLayout and recordsBang operatorsMulticlassThe DAG data typeWriting a donut recipe in TableGenPrinting a recipe via the TableGen backendTableGen's high-level workflowWriting the TableGen backendIntegrating the RecipePrinter TableGen backendSummaryFurther reading
Technical requirementsLearning Clang's subsystems and their rolesDriverLLVM, assemblers, and linkersExploring Clang's tooling features and extension optionsThe FrontendAction classClang pluginsLibTooling and Clang ToolsSummaryFurther reading
Technical requirementsWorking with SourceLocation and SourceManagerIntroducing SourceLocationIntroducing SourceManagerLearning preprocessor and lexer essentialsUnderstanding the role of the preprocessor and lexer in ClangUnderstanding TokenHandling macrosDeveloping custom preprocessor plugins and callbacksThe project goal and preparationImplementing a custom pragma handlerImplementing custom preprocessor callbacksSummaryExercises

Technical requirementsLearning about AST in ClangIn-memory structure of Clang ASTTypes in Clang ASTASTMatcherWriting AST pluginsProject overviewPrinting diagnostic messagesCreating the AST pluginSummary
Technical requirementsUnderstanding drivers and toolchains in ClangAdding custom driver flagsProject overviewDeclaring custom driver flagsTranslating custom driver flagsPassing flags to the frontendAdding a custom toolchainProject overviewCreating the toolchain and adding a custom include pathCreating a custom assembling stageCreating a custom linking stageVerifying the custom toolchainSummaryExercises
Technical requirementsWriting an LLVM Pass for the new PassManagerProject overviewWriting the StrictOpt PassWorking with the new AnalysisManagerOverview of the projectWriting the HaltAnalyzer PassLearning instrumentations in the new PassManagerPrinting Pass pipeline detailsPrinting changes to the IR after each PassBisecting the Pass pipelineSummaryQuestions
Technical requirementsLearning LLVM IR basicsIterating different IR unitsIterating instructionsIterating basic blocksIterating the call graphLearning about GraphTraitsWorking with values and instructionsUnderstanding SSAWorking with valuesWorking with instructionsWorking with loopsLearning about loop representation in LLVMLearning about loop infrastructure in LLVMSummary
Technical requirementsPrinting diagnostic messagesCollecting statisticsUsing the Statistic classUsing an optimization remarkAdding time measurementsUsing the Timer classCollecting the time traceError-handling utilities in LLVMIntroducing the Error classLearning about the Expected and ErrorOr classesThe Expected classThe ErrorOr classSummary
Technical requirementsDeveloping a sanitizerAn example of using an address sanitizerCreating a loop counter sanitizerWorking with PGOIntroduction to instrumentation-based PGOIntroduction to sampling-based PGOUsing profiling data analysesSummary
Chapter 6, Extending the PreprocessorChapter 8, Working with Compiler Flags and ToolchainsChapter 9, Working with PassManager and AnalysisManager
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Overview

Dive into the capabilities of LLVM, a leading framework for constructing compilers and similar tools. In this book, you'll explore LLVM's components and tutorials while learning pragmatic techniques. By mastering LLVM, you'll be able to create tools like custom compilers, analyzers, and performance optimizers.

What this Book will help me do

Understand and work with LLVM's source build system to optimize build efficiency.
Develop skills to create custom plugins for Clang and extend its functionalities.
Learn to inspect, analyze, and modify LLVM IR to build optimization and transformation tools.
Explore LLVM's LIT framework for running custom tests tailored to your development needs.
Implement profile-guided optimizations and custom sanitizers using LLVM's utilities.

Author(s)

Min-Yih Hsu is an experienced software engineer with a deep understanding of compiler technologies and the LLVM framework. With firsthand experience creating real-world applications using LLVM, Min-Yih brings practical insights and thorough explanations to the table. His teaching approach emphasizes clarity and applicability, making this book an excellent resource for developers at various levels of expertise.

Who is it for?

This book is designed for software engineers, programming language enthusiasts, and academic researchers who want to deepen their understanding of LLVM. If you are building or enhancing tools like compilers or source analyzers, have practical use cases for LLVM, or wish to optimize programs with sophisticated backends, this book caters to your goals. Suitable for all levels of LLVM experience, readers will find actionable guidance and examples to advance their projects efficiently.