LLVM Documentation

LLVM's documentation is written in reStructuredText, a lightweight plaintext markup language (file extension .rst). While the reStructuredText documentation should be quite readable in source form, it is mostly meant to be processed by the Sphinx documentation generation system to create HTML pages which are hosted on https://llvm.org/docs/ and updated after every commit. Manpage output is also supported, see below.

If you instead would like to generate and view the HTML locally, install Sphinx http://sphinx-doc.org/ and then do:

cd <build-dir>
cmake -DLLVM_ENABLE_SPHINX=true -DSPHINX_OUTPUT_HTML=true <src-dir>
make -j3 docs-llvm-html
$BROWSER <build-dir>/docs/html/index.html

The mapping between reStructuredText files and generated documentation is docs/Foo.rst <-> <build-dir>/docs//html/Foo.html <-> https://llvm.org/docs/Foo.html.

If you are interested in writing new documentation, you will want to read SphinxQuickstartTemplate.rst which will get you writing documentation very fast and includes examples of the most important reStructuredText markup syntax.

Manpage Output

Building the manpages is similar to building the HTML documentation. The primary difference is to use the man makefile target, instead of the default (which is html). Sphinx then produces the man pages in the directory <build-dir>/docs/man/.

cd <build-dir>
cmake -DLLVM_ENABLE_SPHINX=true -DSPHINX_OUTPUT_MAN=true <src-dir>
make -j3 docs-llvm-man
man -l <build-dir>/docs/man/FileCheck.1

The correspondence between .rst files and man pages is docs/CommandGuide/Foo.rst <-> <build-dir>/docs//man/Foo.1. These .rst files are also included during HTML generation so they are also viewable online (as noted above) at e.g. https://llvm.org/docs/CommandGuide/Foo.html.

Checking links

The reachability of external links in the documentation can be checked by running:

cd llvm/docs/
sphinx-build -b linkcheck . _build/lintcheck/
# report will be generated in _build/lintcheck/output.txt

Doxygen page Output

Install doxygen https://www.doxygen.nl/download.html and dot2tex https://dot2tex.readthedocs.io/en/latest.

cd <build-dir>
cmake -DLLVM_ENABLE_DOXYGEN=On <llvm-top-src-dir>
make doxygen-llvm # for LLVM docs
make doxygen-clang # for clang docs

It will generate html in

<build-dir>/docs/doxygen/html # for LLVM docs
<build-dir>/tools/clang/docs/doxygen/html # for clang docs