llvm.mix

LLVM.Mix is a multi-stage specializer generator built as an extension to LLVM/Clang compiler.

Build

As the project is a fork of LLVM, the usual LLVM build procedure applies (see "The LLVM Compiler Infrastructure" below).

Invoke CMake with -DLLVM_ENABLE_PROJECTS=clang to build a working Clang compiler with llvm.mix support.

Usage

The extension has three main components: binding-time analysis, specializer generation pass, and Clang frontend.

To print the IR after specializer generation, just use -emit-llvm on a source using the extension:

$ clang -flegacy-pass-manager -S -emit-llvm -O1 tmp.c

To print results of the binding-time analysis for functions annotated with stage attributes, use opt -analyze:

$ opt -enable-new-pm=0 -analyze -bta tmp.ll

To generate specializer for the code containing the calls to @llvm.mix intrinsic, include Mix pass in the pipeline:

$ opt -enable-new-pm=0 -S -mix tmp.ll

Please refer to my presentation and mix-examples repository for more info. Test directories (BTA, Mix) may serve as something like a starting point as well.

Test

The check target by default includes all of the LLVM.Mix tests.

Use check-llvm-analysis-bindingtimeanalysis and check-llvm-transforms-mix targets to run the test suites separately.

Specializer test suite (check-llvm-transforms-mix) needs FFI (disabled by default). Pass -DLLVM_ENABLE_FFI=On to CMake to enable it.

Links

• Presentation at FOSDEM 2019
• Examples and micro benchmarks

The LLVM Compiler Infrastructure

This directory and its sub-directories contain source code for LLVM, a toolkit for the construction of highly optimized compilers, optimizers, and run-time environments.

The README briefly describes how to get started with building LLVM. For more information on how to contribute to the LLVM project, please take a look at the Contributing to LLVM guide.

Getting Started with the LLVM System

Taken from https://llvm.org/docs/GettingStarted.html.

Overview

Welcome to the LLVM project!

The LLVM project has multiple components. The core of the project is itself called "LLVM". This contains all of the tools, libraries, and header files needed to process intermediate representations and convert them into object files. Tools include an assembler, disassembler, bitcode analyzer, and bitcode optimizer. It also contains basic regression tests.

C-like languages use the Clang front end. This component compiles C, C++, Objective-C, and Objective-C++ code into LLVM bitcode -- and from there into object files, using LLVM.

Other components include: the libc++ C++ standard library, the LLD linker, and more.

Getting the Source Code and Building LLVM

The LLVM Getting Started documentation may be out of date. The Clang Getting Started page might have more accurate information.

This is an example work-flow and configuration to get and build the LLVM source:

1. Checkout LLVM (including related sub-projects like Clang):

   • git clone https://github.com/llvm/llvm-project.git

   • Or, on windows, git clone --config core.autocrlf=false https://github.com/llvm/llvm-project.git

2. Configure and build LLVM and Clang:

   • cd llvm-project

   • cmake -S llvm -B build -G <generator> [options]

     Some common build system generators are:

     • Ninja --- for generating Ninja build files. Most llvm developers use Ninja.
     • Unix Makefiles --- for generating make-compatible parallel makefiles.
     • Visual Studio --- for generating Visual Studio projects and solutions.
     • Xcode --- for generating Xcode projects.

     Some Common options:

     • -DLLVM_ENABLE_PROJECTS='...' --- semicolon-separated list of the LLVM sub-projects you'd like to additionally build. Can include any of: clang, clang-tools-extra, libcxx, libcxxabi, libunwind, lldb, compiler-rt, lld, polly, or cross-project-tests.

       For example, to build LLVM, Clang, libcxx, and libcxxabi, use -DLLVM_ENABLE_PROJECTS="clang;libcxx;libcxxabi".

     • -DCMAKE_INSTALL_PREFIX=directory --- Specify for directory the full path name of where you want the LLVM tools and libraries to be installed (default /usr/local).

     • -DCMAKE_BUILD_TYPE=type --- Valid options for type are Debug, Release, RelWithDebInfo, and MinSizeRel. Default is Debug.

     • -DLLVM_ENABLE_ASSERTIONS=On --- Compile with assertion checks enabled (default is Yes for Debug builds, No for all other build types).

   • cmake --build build [-- [options] <target>] or your build system specified above directly.

     • The default target (i.e. ninja or make) will build all of LLVM.

     • The check-all target (i.e. ninja check-all) will run the regression tests to ensure everything is in working order.

     • CMake will generate targets for each tool and library, and most LLVM sub-projects generate their own check-<project> target.

     • Running a serial build will be slow. To improve speed, try running a parallel build. That's done by default in Ninja; for make, use the option -j NNN, where NNN is the number of parallel jobs, e.g. the number of CPUs you have.

   • For more information see CMake

Consult the Getting Started with LLVM page for detailed information on configuring and compiling LLVM. You can visit Directory Layout to learn about the layout of the source code tree.