User Guides

NOTE: If you are a user who is only interested in using an LLVM-based compiler,you should look into Clang instead. Thedocumentation here is intended for users who have a need to work with theintermediate LLVM representation.

Clang

• How To Build On ARM
• Notes on building and testing LLVM/Clang on ARM.
• How To Build Clang and LLVM with Profile-Guided Optimizations
• Notes on building LLVM/Clang with PGO.
• How To Cross-Compile Clang/LLVM using Clang/LLVM
• Notes on cross-building and testing LLVM/Clang.
• How to build the C, C++, ObjC, and ObjC++ front end
• Instructions for building the clang front-end from source.
• LLVM Code Coverage Mapping Format
• This describes the format and encoding used for LLVM’s code coverage mapping.
• Control Flow Verification Tool Design Document
• A description of the verification tool for Control Flow Integrity.

LLVM Builds and Distributions

• Building a Distribution of LLVM
• A best-practices guide for using LLVM’s CMake build system to package anddistribute LLVM-based tools.
• Building LLVM with CMake
• An addendum to the main Getting Started guide for those using the CMakebuild system.
• A guide to Dockerfiles for building LLVM
• A reference for using Dockerfiles provided with LLVM.
• Support Library
• This document describes the LLVM Support Library (lib/Support) andhow to keep LLVM source code portable

Optimizations

• Writing an LLVM Pass
• Information on how to write LLVM transformations and analyses.
• LLVM’s Analysis and Transform Passes
• A list of optimizations and analyses implemented in LLVM.
• Stack Safety Analysis
• This document describes the design of the stack safety analysis of localvariables.
• MergeFunctions pass, how it works
• Describes functions merging optimization.
• LLVM Alias Analysis Infrastructure
• Information on how to write a new alias analysis implementation or how touse existing analyses.
• MemorySSA
• Information about the MemorySSA utility in LLVM, as well as how to use it.
• LLVM Loop Terminology (and Canonical Forms)
• A document describing Loops and associated terms as used in LLVM.
• Auto-Vectorization in LLVM
• This document describes the current status of vectorization in LLVM.
• LLVM Link Time Optimization: Design and Implementation
• This document describes the interface between LLVM intermodular optimizerand the linker and its design
• The LLVM gold plugin
• How to build your programs with link-time optimization on Linux.
• Remarks
• A reference on the implementation of remarks in LLVM.
• Source Level Debugging with LLVM
• This document describes the design and philosophy behind the LLVMsource-level debugger.

Code Generation

• Writing an LLVM Backend
• Information on how to write LLVM backends for machine targets.
• The LLVM Target-Independent Code Generator
• The design and implementation of the LLVM code generator. Useful if you areworking on retargetting LLVM to a new architecture, designing a new codegenpass, or enhancing existing components.
• TableGen
• Describes the TableGen tool, which is used heavily by the LLVM codegenerator.

JIT

• MCJIT Design and Implementation
• Describes the inner workings of MCJIT execution engine.
• Debugging JIT-ed Code With GDB
• How to debug JITed code with GDB.

How to debug JITed code with GDB.

Additional Topics

• CommandLine 2.0 Library Manual
• Provides information on using the command line parsing library.
• Extending LLVM: Adding instructions, intrinsics, types, etc.
• Look here to see how to add instructions and intrinsics to LLVM.
• How To Add A Constrained Floating-Point Intrinsic
• Gives the steps necessary when adding a new constrained math intrinsicto LLVM.
• How to Cross Compile Compiler-rt Builtins For Arm
• Notes on cross-building and testing the compiler-rt builtins for Arm.
• Using ARM NEON instructions in big endian mode
• LLVM’s support for generating NEON instructions on big endian ARM targets issomewhat nonintuitive. This document explains the implementation and rationale.
• Compiling CUDA with clang
• LLVM support for CUDA.
• User Guide for NVPTX Back-end
• This document describes using the NVPTX backend to compile GPU kernels.
• User Guide for AMDGPU Backend
• This document describes using the AMDGPU backend to compile GPU kernels.