llvm-6502/docs
Philip Reames d1940dcca7 Clarify wording in the LangRef around !invariant.load
Clarify the wording around !invariant.load to properly reflect the semantics of such loads with respect to control dependence and location lifetime.  To the best of my knowledge, the revised wording respects the actual implementation and understanding of issues involved highlighted in the recent 'Optimization hints for "constant" loads' thread on LLVMDev.  

In particular, I'm aiming for the following results:
- To clarify that an invariant.load can fault and must respect control dependence.  In particular, it is not sound to unconditionally pull an invariant load out of a loop if that loop would potentially never execute.  
- To clarify that the invariant nature of a given pointer does not preclude the modification of that location through a pointer which is unrelated to the load operand.  In particular, initializing a location and then passing a pointer through an opaque intrinsic which produces a new unrelated pointer, should behave as expected provided that the intrinsic is memory dependent on the initializing store.  
- To clarify that storing a value to an invariant location is defined.  It can not, for example, be considered unreachable.  The value stored can be assumed to be equal to the value of any previous (or following!) invariant load, but the store itself is defined.  

I recommend that anyone interested in using !invariant.load, or optimizing for them, read over the discussion in the review thread.  A number of motivating examples are discussed.

Differential Revision: http://reviews.llvm.org/D6346



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222700 91177308-0d34-0410-b5e6-96231b3b80d8
2014-11-24 22:32:43 +00:00
..
_static [docs] Update HTML pages to refer to CSS in a way that works locally and with Sphinx. 2012-04-19 20:20:34 +00:00
_templates [docs] Convert docs index page into Sphinx. 2012-04-19 16:31:37 +00:00
_themes/llvm-theme Sphinx CSS: remove negative letter-spacing, it makes some fonts look really 2012-09-30 20:43:24 +00:00
CommandGuide [llvm-symbolizer] Introduce the -dsym-hint option. 2014-10-17 00:50:19 +00:00
HistoricalNotes [typo] An LLVM. 2013-08-16 23:30:19 +00:00
TableGen Fix typo in TableGen documentation 2014-10-03 20:46:05 +00:00
tutorial [Docs][JIT] Update the clang++ invocation lines in the kaleidoscope docs. 2014-11-06 00:31:04 +00:00
AliasAnalysis.rst Update some AliasAnalysis pass docs for getAdjustedAnalysisPointer. 2014-05-22 19:38:25 +00:00
ARM-BE-bitcastfail.png [ARM64-BE] Add sphinx documentation for the ARM64 NEON implementation. 2014-05-12 15:13:39 +00:00
ARM-BE-bitcastsuccess.png [ARM64-BE] Add sphinx documentation for the ARM64 NEON implementation. 2014-05-12 15:13:39 +00:00
ARM-BE-ld1.png [ARM64-BE] Add sphinx documentation for the ARM64 NEON implementation. 2014-05-12 15:13:39 +00:00
ARM-BE-ldr.png [ARM64-BE] Add sphinx documentation for the ARM64 NEON implementation. 2014-05-12 15:13:39 +00:00
Atomics.rst [sphinx cleanup] Fix unexpected indentation warning introduced by r218937 2014-10-03 12:28:48 +00:00
BigEndianNEON.rst Fix typos 2014-05-15 01:52:21 +00:00
BitCodeFormat.rst Fix sphinx warning. 2014-09-18 21:54:02 +00:00
BlockFrequencyTerminology.rst Fix typos 2014-05-15 01:52:21 +00:00
BranchWeightMetadata.rst blockfreq: Document BlockFrequencyInfo terminology 2014-04-11 23:21:07 +00:00
Bugpoint.rst [docs] Fix up some links to the preferred style. 2014-04-08 21:06:22 +00:00
CMake.rst Use ninja pools to limit the number of concurrent compile/link jobs. 2014-11-19 10:30:02 +00:00
CMakeLists.txt Added Sphinx documentation generation to CMake build system. 2014-04-18 21:45:25 +00:00
CodeGenerator.rst [sphinx cleanup] 2014-09-10 20:43:03 +00:00
CodingStandards.rst Introduce Go coding standards for LLVM. 2014-10-14 00:40:53 +00:00
CommandLine.rst Update the example of using a command-line option custom parser to 2014-10-13 21:11:22 +00:00
CompilerWriterInfo.rst Update documentation with link to Sea Islands documentation 2014-10-06 18:31:09 +00:00
conf.py Update LLVM version: 3.5 => 3.6 2014-07-28 22:10:52 +00:00
CoverageMappingFormat.rst Docs: add documentation for the coverage mapping format. 2014-08-19 17:05:58 +00:00
DebuggingJITedCode.rst docs: Fix long standing linking antipattern. 2013-01-11 02:28:08 +00:00
DeveloperPolicy.rst Document what backwards compatibility we provide for bitcode. 2014-07-23 22:43:22 +00:00
doxygen.cfg.in [docs] Teach CMake docs build how to generate Qt Creator help/documentation files. 2014-03-07 19:19:28 +00:00
doxygen.css [docs] Update Makefile for images removal. 2012-04-20 17:27:12 +00:00
doxygen.footer Update the copyright credits -- Happy new year 2014! 2014-01-01 08:27:31 +00:00
doxygen.header
doxygen.intro
Dummy.html Add a dummy documentation file to unbreak 'make install'. We need to find how 2012-12-13 13:37:35 +00:00
ExceptionHandling.rst Exception handling docs: Clarify how the llvm.eh.* intrinsics are used 2014-03-28 17:08:57 +00:00
ExtendedIntegerResults.txt
ExtendingLLVM.rst Correct path to regression tests in ExtendingLLVM 2014-11-24 19:40:07 +00:00
Extensions.rst ARM: add VLA extension for WoA Itanium ABI 2014-06-09 20:18:42 +00:00
FAQ.rst remove an old entry whose link is broken anyway 2014-03-02 06:37:03 +00:00
GarbageCollection.rst Remove the TargetMachine forwards for TargetSubtargetInfo based 2014-08-04 21:25:23 +00:00
gcc-loops.png Update the gcc-loops benchmark 2013-01-20 07:01:04 +00:00
GetElementPtr.rst [docs] Clean up some more llvm-gcc stuff 2014-02-19 00:12:34 +00:00
GettingStarted.rst VMCore was renamed to IR long time ago 2014-10-29 05:20:39 +00:00
GettingStartedVS.rst Document how to select build configuration with Visual C++ IDE or command line. 2014-06-05 16:42:26 +00:00
GoldPlugin.rst Docs: give binutils/gold instructions for CMake too. 2014-11-04 02:16:03 +00:00
HowToAddABuilder.rst docs: Fix long standing linking antipattern. 2013-01-11 02:28:08 +00:00
HowToBuildOnARM.rst Adding some info about stability of ARM boards 2013-11-15 08:42:14 +00:00
HowToCrossCompileLLVM.rst [docs] Some typographical fixes. 2013-09-09 19:05:03 +00:00
HowToReleaseLLVM.rst docs: Update relaease documents to include the patch number in the RELEASE tags 2014-07-21 14:28:31 +00:00
HowToSetUpLLVMStyleRTTI.rst [C++11] Replace LLVM-style type traits with C++11 standard ones. 2014-03-07 14:42:25 +00:00
HowToSubmitABug.rst Delete -std-compile-opts. 2014-10-16 20:00:02 +00:00
HowToUseAttributes.rst Documentation: HowToUseAttributes: formatting (use monospaced font) 2013-02-12 18:26:08 +00:00
HowToUseInstrMappings.rst docs: Fix long standing linking antipattern. 2013-01-11 02:28:08 +00:00
InAlloca.rst inalloca: *Really* fix the docs 2014-03-27 01:38:48 +00:00
index.rst R600/SI: Start implementing an assembler 2014-11-14 14:08:00 +00:00
LangRef.rst Clarify wording in the LangRef around !invariant.load 2014-11-24 22:32:43 +00:00
Lexicon.rst [docs] Document what "NFC" means in a commit message. 2014-09-06 00:19:16 +00:00
LinkTimeOptimization.rst docs: Fix long standing linking antipattern. 2013-01-11 02:28:08 +00:00
linpack-pc.png Update the linpack benchmark with different array sizes. 2013-01-20 06:52:47 +00:00
LLVMBuild.rst [docs] Fix some links 2014-04-07 22:46:40 +00:00
LLVMBuild.txt
make.bat
Makefile [OCaml] PR14083, PR9606: Only pick *.odoc files from current build target. 2014-10-28 22:45:25 +00:00
Makefile.sphinx Revert "Treat warnings in Sphinx as errors. The reasons for doing this are..." 2014-07-22 18:09:17 +00:00
MakefileGuide.rst Remove projects/sample. 2014-03-12 22:40:22 +00:00
MarkedUpDisassembly.rst undo test commit (whitespace only) 2014-06-30 08:09:35 +00:00
MCJIT-creation.png Adding a document to describe the MCJIT execution engine implementation. 2013-08-21 22:15:09 +00:00
MCJIT-dyld-load.png Adding a document to describe the MCJIT execution engine implementation. 2013-08-21 22:15:09 +00:00
MCJIT-engine-builder.png Adding a document to describe the MCJIT execution engine implementation. 2013-08-21 22:15:09 +00:00
MCJIT-load-object.png Adding a document to describe the MCJIT execution engine implementation. 2013-08-21 22:15:09 +00:00
MCJIT-load.png Adding a document to describe the MCJIT execution engine implementation. 2013-08-21 22:15:09 +00:00
MCJIT-resolve-relocations.png Adding a document to describe the MCJIT execution engine implementation. 2013-08-21 22:15:09 +00:00
MCJITDesignAndImplementation.rst Minor typo. 2014-09-05 04:56:43 +00:00
NVPTXUsage.rst Fix documentation typos 2013-12-20 00:33:39 +00:00
Packaging.rst docs: Fix long standing linking antipattern. 2013-01-11 02:28:08 +00:00
Passes.rst docs: Remove documentation for legacy PGO options 2014-06-04 06:29:38 +00:00
Phabricator.rst Phabricator doc: Explicit the fact that the patch needs to be there before the commit 2014-07-04 09:00:35 +00:00
ProgrammersManual.rst Update my previous commit to fit 80 cols... 2014-09-25 10:58:16 +00:00
Projects.rst Remove projects/sample. 2014-03-12 22:40:22 +00:00
R600Usage.rst R600/SI: Start implementing an assembler 2014-11-14 14:08:00 +00:00
re_format.7
README.txt [docs] Add a note to docs/README.txt 2014-04-22 21:47:53 +00:00
ReleaseNotes.rst LTO: introduce object file-based on-disk module format. 2014-09-18 21:28:49 +00:00
ReleaseProcess.rst Update Release Process doc 2013-06-12 11:35:33 +00:00
SegmentedStacks.rst Move the segmented stack switch to a function attribute 2014-04-10 22:58:43 +00:00
SourceLevelDebugging.rst Update dwarf::ApplePropertyAttributes enum to meaningful values. 2014-10-08 14:59:44 +00:00
SphinxQuickstartTemplate.rst [docs] Provide pointer for building Sphinx docs. 2013-02-27 18:33:21 +00:00
StackMaps.rst Stack map docs. Remove some stray markup. 2014-04-03 07:08:21 +00:00
SystemLibrary.rst remove the rest of the "written by" lines in the documentation. It is 2013-01-10 21:24:04 +00:00
TableGenFundamentals.rst Recover TableGen/LangRef, make it official 2014-04-01 09:51:49 +00:00
TestingGuide.rst [docs] Document usage of Inputs/ for extra test files. 2014-11-05 22:17:18 +00:00
TestSuiteMakefileGuide.rst remove the rest of the "written by" lines in the documentation. It is 2013-01-10 21:24:04 +00:00
Vectorizers.rst Vectorization documentation for loop hint pragmas and Rpass diagnostics. 2014-06-27 18:30:08 +00:00
WritingAnLLVMBackend.rst configure.ac lives in autoconf/, not autotools/ 2014-11-10 22:36:04 +00:00
WritingAnLLVMPass.rst docs: Modernize some examples in WritingAnLLVMPass 2014-11-18 05:22:39 +00:00
yaml2obj.rst Object: rename ARMV7 to ARMNT 2014-03-11 03:08:37 +00:00
YamlIO.rst [YAML] Add an optional argument EnumMask to the yaml::IO::bitSetCase(). 2014-05-23 08:07:09 +00:00

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 docs/
    make -f Makefile.sphinx
    $BROWSER _build/html/index.html

The mapping between reStructuredText files and generated documentation is
`docs/Foo.rst` <-> `_build/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/man/`.

    cd docs/
    make -f Makefile.sphinx man
    man -l _build/man/FileCheck.1

The correspondence between .rst files and man pages is
`docs/CommandGuide/Foo.rst` <-> `_build/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 reachibility of external links in the documentation can be checked by
running:

    cd docs/
    make -f Makefile.sphinx linkcheck