Quick start Building with Bazel

Building with Bazel


Building with Bazel is mostly self-contained meaning that Bazel will download most of the dependencies and arrange them in you workspace such that you do not need to checkout submodules or install extra packages. However, following external dependencies needs installing in order to use Bazel for building:

  • C++ compiler (Clang 14 or MSVC 14.20)
  • Bazelisk (or Bazel 5.0)

We recommend the usage of Bazelisk as it is a wrapper that automatically downloads the correct version of Bazel for your project. The details of installing Bazelisk can be found here. You can also use Bazel without the wrapper. To do this, you need to install Bazel with the exact version specified in the .bazelversion file and in the subsequent sections replace bazelisk with bazel.

To install on macOS use brew:

brew install bazelisk

To install on Windows use choco:

choco install bazelisk

On any other platform, we suggest you use npm. Note that npm also works with macOS and Windows

npm install -g @bazel/bazelisk

Once installed, verify that Bazelisk is correctly installed by running

bazelisk --help

If you experience any trouble with this step, please refer to the official documentation.

Building QAT using Bazel

Before building, decide whether you are building with clang or msvc as well as whether you wish to make a release build or a debug build. On all operating systems, Bazelisk follows the pattern

bazelisk build [target] --config [clang/msvc] --config [debug/release]

On macOS and Ubuntu, you can build QAT as

bazelisk build //qir/qat:qat --config clang --config release

On Windows, you would use the msvc compiler

bazelisk build //qir/qat:qat --config msvc --config release

You will note that you do not need to checkout submodules and/or install LLVM locally on your machine. Bazel will download all dependencies and compile them from scratch. The benefit of this is that builds are much more reproducible and less dependent on you local system settings. The downside is that build times can be longer since everything is compiled from scratch.

You will note that you can run QAT directly using Bazel by

bazelisk run //qir/qat:qat --config msvc --config release -- [qat arguments]

In the subsequent sections feel free to substitute the QAT binary with this command.