mirror of
https://github.com/RPCS3/llvm-mirror.git
synced 2025-01-31 20:51:52 +01:00
259a327aae
This is split off from D79100 and: - adds a intrinsic description/definition for @llvm.get.active.lane.mask(), and - describe its semantics in LangRef. As described (in more detail) in its LangRef section, it is semantically equivalent to an icmp with the vector induction variable and the back-edge taken count, and generates a mask of active/inactive vector lanes. It will have several use cases. First, it will be used by the ExpandVectorPredication pass for the VP intrinsics, to expand VP intrinsics for scalable vectors on targets that do not support the `%evl` parameter, see D78203. Also, this is part of, and essential for our ARM MVE tail-predication story: - this intrinsic will be emitted by the LoopVectorizer in D79100, when the scalar epilogue is tail-folded into the vector body. This new intrinsic will generate the predicate for the masked loads/stores, and it takes the back-edge taken count as an argument. The back-edge taken count represents the number of elements processed by the loop, which we need to setup MVE tail-predication. - Emitting the intrinsic is controlled by a new TTI hook, see D80597. - We pick up this new intrinsic in an ARM MVETailPredication backend pass, see D79175, and convert it to a MVE target specific intrinsic/instruction to create a tail-predicated loop. Differential Revision: https://reviews.llvm.org/D80596
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 docs/
make -f Makefile.sphinx linkcheck
Doxygen page Output
==============
Install doxygen <http://www.stack.nl/~dimitri/doxygen/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