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| <h1 id="gcc-codegen-backend"><a class="header" href="#gcc-codegen-backend">GCC codegen backend</a></h1> |
| <p>We run a subset of the compiler test suite with the GCC codegen backend on our CI, to help find changes that could break the integration of this backend with the compiler.</p> |
| <p>If you encounter any bugs or problems with the GCC codegen backend in general, don't hesitate to open issues on the |
| <a href="https://github.com/rust-lang/rustc_codegen_gcc"><code>rustc_codegen_gcc</code> repository</a>.</p> |
| <p>Note that the backend currently only supports the <code>x86_64-unknown-linux-gnu</code> target.</p> |
| <h2 id="running-into-gcc-backend-ci-errors"><a class="header" href="#running-into-gcc-backend-ci-errors">Running into GCC backend CI errors</a></h2> |
| <p>If you ran into an error related to tests executed with the GCC codegen backend on CI in the <code>x86_64-gnu-gcc</code> job, |
| you can use the following command to run UI tests locally using the GCC backend, which reproduces what happens on CI:</p> |
| <pre><code class="language-bash">./x test tests/ui \ |
| --set 'rust.codegen-backends = ["llvm", "gcc"]' \ |
| --set 'rust.debug-assertions = false' \ |
| --test-codegen-backend gcc |
| </code></pre> |
| <p>If a different test suite has failed on CI, you will have to modify the <code>tests/ui</code> part.</p> |
| <p>To reproduce the whole CI job locally, you can run <code>cargo run --manifest-path src/ci/citool/Cargo.toml run-local x86_64-gnu-gcc</code>. |
| See <a href="../docker.html">Testing with Docker</a> for more information.</p> |
| <h3 id="what-to-do-in-case-of-a-gcc-job-failure"><a class="header" href="#what-to-do-in-case-of-a-gcc-job-failure">What to do in case of a GCC job failure?</a></h3> |
| <p>If the GCC job test fails and it seems like the failure could be caused by the GCC backend, you can ping the <a href="https://github.com/orgs/rust-lang/teams/wg-gcc-backend">cg-gcc working group</a> using <code>@rust-lang/wg-gcc-backend</code></p> |
| <p>If fixing a compiler test that fails with the GCC backend is non-trivial, you can ignore that test when executed with <code>cg_gcc</code> using the <code>//@ ignore-backends: gcc</code> <a href="../directives.html">compiletest directive</a>.</p> |
| <h2 id="choosing-which-codegen-backends-are-built"><a class="header" href="#choosing-which-codegen-backends-are-built">Choosing which codegen backends are built</a></h2> |
| <p>The <code>rust.codegen-backends = [...]</code> bootstrap option affects which codegen backends will be built and |
| included in the sysroot of the produced <code>rustc</code>. |
| To use the GCC codegen backend, <code>"gcc"</code> has to be included in this array in <code>bootstrap.toml</code>:</p> |
| <pre><code class="language-toml">rust.codegen-backends = ["llvm", "gcc"] |
| </code></pre> |
| <p>If you don't want to change your <code>bootstrap.toml</code> file, you can alternatively run your <code>x</code> |
| commands with <code>--set 'rust.codegen-backends=["llvm", "gcc"]'</code>. |
| For example:</p> |
| <pre><code class="language-bash">./x build --set 'rust.codegen-backends=["llvm", "gcc"]' |
| </code></pre> |
| <p>The first backend in the <code>codegen-backends</code> array will determine which backend will be used as the |
| <em>default backend</em> of the built <code>rustc</code>. |
| This also determines which backend will be used to compile the |
| stage 1 standard library (or anything built in stage 2+). |
| To produce <code>rustc</code> that uses the GCC backend |
| by default, you can thus put <code>"gcc"</code> as the first element of this array:</p> |
| <pre><code class="language-bash">./x build --set 'rust.codegen-backends=["gcc"]' library |
| </code></pre> |
| <h2 id="choosing-the-codegen-backend-used-in-tests"><a class="header" href="#choosing-the-codegen-backend-used-in-tests">Choosing the codegen backend used in tests</a></h2> |
| <p>To run compiler tests with the GCC codegen backend being used to build the test Rust programs, you can use the |
| <code>--test-codegen-backend</code> flag:</p> |
| <pre><code class="language-bash">./x test tests/ui --test-codegen-backend gcc |
| </code></pre> |
| <p>Note that in order for this to work, the tested compiler must have the GCC codegen backend <a href="#choosing-which-codegen-backends-are-built">available</a> in its sysroot directory.</p> |
| <h2 id="downloading-gcc-from-ci"><a class="header" href="#downloading-gcc-from-ci">Downloading GCC from CI</a></h2> |
| <p>The <code>gcc.download-ci-gcc</code> bootstrap option controls if GCC (which is a dependency of the GCC codegen backend) |
| will be downloaded from CI or built locally. |
| The default value is <code>true</code>, which will download GCC from CI |
| if there are no local changes to the GCC sources and the given host target is available on CI.</p> |
| <h2 id="running-tests-of-the-backend-itself"><a class="header" href="#running-tests-of-the-backend-itself">Running tests of the backend itself</a></h2> |
| <p>In addition to running the compiler's test suites using the GCC codegen backend, you can also run the test suite of the backend itself.</p> |
| <p>Now you do that using the following command:</p> |
| <pre><code class="language-text">./x test rustc_codegen_gcc |
| </code></pre> |
| <p>The backend needs to be <a href="#choosing-which-codegen-backends-are-built">enabled</a> for this to work.</p> |
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