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fe647d2183
There was an efficiency problem with how we processed @llvm.assume in ValueTracking (and other places). The AssumptionCache tracked all of the assumptions in a given function. In order to find assumptions relevant to computing known bits, etc. we searched every assumption in the function. For ValueTracking, that means that we did O(#assumes * #values) work in InstCombine and other passes (with a constant factor that can be quite large because we'd repeat this search at every level of recursion of the analysis). Several of us discussed this situation at the last developers' meeting, and this implements the discussed solution: Make the values that an assume might affect operands of the assume itself. To avoid exposing this detail to frontends and passes that need not worry about it, I've used the new operand-bundle feature to add these extra call "operands" in a way that does not affect the intrinsic's signature. I think this solution is relatively clean. InstCombine adds these extra operands based on what ValueTracking, LVI, etc. will need and then those passes need only search the users of the values under consideration. This should fix the computational-complexity problem. At this point, no passes depend on the AssumptionCache, and so I'll remove that as a follow-up change. Differential Revision: https://reviews.llvm.org/D27259 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@289755 91177308-0d34-0410-b5e6-96231b3b80d8
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 <http://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` <-> `http://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.
`http://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