Halide

Halide is a programming language designed to make it easier to write high-performance image and array processing code on modern machines. Halide currently targets:

• CPU architectures: X86, ARM, Hexagon, PowerPC, RISC-V, WebAssembly
• Operating systems: Linux, Windows, macOS, Android, iOS, FreeBSD, Qualcomm QuRT
• GPU Compute APIs: CUDA, OpenCL, Apple Metal, Microsoft Direct X 12, Vulkan

Rather than being a standalone programming language, Halide is embedded in C++. This means you write C++ code that builds an in-memory representation of a Halide pipeline using Halide's C++ API. You can then compile this representation to an object file, or JIT-compile it and run it in the same process. Halide also provides a Python binding that provides full support for writing Halide embedded in Python without C++.

Halide requires C++17 (or later) to use.

For more detail about what Halide is, see https://halide-lang.org.

For API documentation see https://halide-lang.org/docs.

For some example code, read through the tutorials online at https://halide-lang.org/tutorials. The corresponding code is in the tutorials/ directory. Larger examples are in the apps/ directory.

If you've acquired a full source distribution and want to build Halide, see the notes below.

Getting Halide

Pip

We provide binary wheels on PyPI. Halide provides bindings for C++ and Python. Even if you only intend to use Halide from C++, pip may be the easiest way to get a binary build of Halide.

Full releases may be installed with pip or added to a uv project like so:

$ pip install halide
$ uv add halide

The published Python artifacts are split into three distributions that share the halide import package. The halide distribution provides the compiler Python API and depends on matching versions of halide-bin (the compiler, headers, tools, and CMake package) and halide-runtime (the standalone halide.runtime API). Most users should install only halide; the package manager installs its two dependencies automatically. Deployments that only call precompiled AOT pipelines can instead install halide-runtime, avoiding the compiler and LLVM entirely.

Every commit to main is published to our package index as a development version. If you use uv, you can pin the nightly Halide in a project like so:

$ uv add halide --prerelease=allow --index https://pypi.halide-lang.org/simple

Or install directly with pip:

$ pip install halide --pre --extra-index-url https://pypi.halide-lang.org/simple

Currently, we provide wheels for: Windows x86-64, macOS x86-64, macOS arm64, and Linux x86-64. The Linux wheels are built for manylinux_2_28, which makes them broadly compatible (Debian 10, Ubuntu 18.10, Fedora 29).

For C++ usage of the pip package: On Linux and macOS, CMake's find_package command should find Halide as long as you're in the same virtual environment you installed it in. On Windows, you will need to add the virtual environment root directory to CMAKE_PREFIX_PATH. This can be done by running set CMAKE_PREFIX_PATH=%VIRTUAL_ENV% in cmd.

Other build systems can find the Halide root path by running python -c "import halide; print(halide.install_dir())".

Alternative for no-Python Environments

If you cannot use Python tooling (e.g. pip or uv) to download the Halide wheels, you can download them directly from either our nightly index or the public PyPI index. Python wheel files are just standard zip files with a .whl extension.

Homebrew

Alternatively, if you use macOS, you can install Halide via Homebrew like so:

$ brew install halide

Vcpkg

If you use vcpkg to manage dependencies, you can install Halide via:

$ vcpkg install halide:x64-windows # or x64-linux/x64-osx

One caveat: vcpkg installs only the minimum Halide backends required to compile code for the active platform. If you want to include all the backends, you should install halide[target-all]:x64-windows instead.

Other package managers

We are interested in bringing Halide to other popular package managers and Linux distribution repositories! We track the status of various distributions of Halide in this GitHub issue. If you have experience publishing packages we would be happy to work with you!

Building Halide

Platform Support

There are two sets of platform requirements relevant to Halide: those required to run the compiler library in either JIT or AOT mode, and those required to run the binary outputs of the AOT compiler.

These are the tested host toolchain and platform combinations for building and running the Halide compiler library.

Compiler	Version	OS	Architectures
GCC	9.5	Ubuntu Linux 20.04 LTS	x86, x64
GCC	11.4	Ubuntu Linux 22.04 LTS	ARM32, ARM64
MSVC	2022 (19.37)	Windows 11 (22631)	x86, x64
AppleClang	15.0.0	macOS 14.4.1	x64
AppleClang	14.0.0	macOS 14.6	ARM64

Some users have successfully built Halide for Linux using Clang 9.0.0+, for Windows using ClangCL 11.0.0+, and for Windows ARM64 by cross-compiling with MSVC. We do not actively test these scenarios, however, so your mileage may vary.

Beyond these, we are willing to support (by accepting PRs for) platform and toolchain combinations that still receive active, first-party, public support from their original vendors. For instance, at time of writing, this excludes Windows 7 and includes Ubuntu 18.04 LTS.

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