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This patch moves NEON immediate argument specification and checking to
the system currently shared by both SVE and SME.
In its current form, the TableGen definition of a NEON intrinsic cannot
control how its immediate arguments are range-checked, this information
must be inferred from the name of the intrinsic by NeonEmitter, which
also assumes that any NEON instruction will only ever receive a single
immediate argument. For SVE/SME instrinsics, this information is more
conveniently supplied in the TableGen definition.
As a result, for each immediate argument, NEON instructions must define
- The index of the immediate argument to be checked
- The type of immediate range check to be performed,
(e.g., ImmCheckShiftRight)
- The index of the argument whose type defines the context
of this immediate check (base type, vector size).
- **Difference from SVE/SME** If this definition generates a polymorphic
NEON builtin, the base type defined by this argument is overwritten by
that of the type code supplied to the overloaded builtin call. This
third argument is omitted in some cases due to this.
Here is an example for
[`vfma_laneq`](https://developer.arm.com/architectures/instruction-sets/intrinsics/#f:@navigationhierarchiessimdisa=[Neon]&q=vfma_laneq)
- The immediate is supplied in argument 3
- The immediate is used as an index into the lanes of argument 2
- So we must perform an immediate check on argument 3, based on the type
information of argument 2.
- `ImmCheck<3, ImmCheckLaneIndex, 2>`
During this work, we discovered that the existing immediate
range-checking system was largely untested, which made it difficult to
make reliable progress. Missing tests have been added to verify this
implementation against all intrinsics which take constrained immediate
arguments. All test immediate range checking tests for NEON intrinsics
are moved to a dedicated directory
`clang/test/Sema/aarch64-neon-immediate-ranges/`.
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