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d1940dcca7
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 |
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CommandGuide | ||
HistoricalNotes | ||
TableGen | ||
tutorial | ||
AliasAnalysis.rst | ||
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Atomics.rst | ||
BigEndianNEON.rst | ||
BitCodeFormat.rst | ||
BlockFrequencyTerminology.rst | ||
BranchWeightMetadata.rst | ||
Bugpoint.rst | ||
CMake.rst | ||
CMakeLists.txt | ||
CodeGenerator.rst | ||
CodingStandards.rst | ||
CommandLine.rst | ||
CompilerWriterInfo.rst | ||
conf.py | ||
CoverageMappingFormat.rst | ||
DebuggingJITedCode.rst | ||
DeveloperPolicy.rst | ||
doxygen.cfg.in | ||
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doxygen.intro | ||
Dummy.html | ||
ExceptionHandling.rst | ||
ExtendedIntegerResults.txt | ||
ExtendingLLVM.rst | ||
Extensions.rst | ||
FAQ.rst | ||
GarbageCollection.rst | ||
gcc-loops.png | ||
GetElementPtr.rst | ||
GettingStarted.rst | ||
GettingStartedVS.rst | ||
GoldPlugin.rst | ||
HowToAddABuilder.rst | ||
HowToBuildOnARM.rst | ||
HowToCrossCompileLLVM.rst | ||
HowToReleaseLLVM.rst | ||
HowToSetUpLLVMStyleRTTI.rst | ||
HowToSubmitABug.rst | ||
HowToUseAttributes.rst | ||
HowToUseInstrMappings.rst | ||
InAlloca.rst | ||
index.rst | ||
LangRef.rst | ||
Lexicon.rst | ||
LinkTimeOptimization.rst | ||
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LLVMBuild.rst | ||
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make.bat | ||
Makefile | ||
Makefile.sphinx | ||
MakefileGuide.rst | ||
MarkedUpDisassembly.rst | ||
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MCJITDesignAndImplementation.rst | ||
NVPTXUsage.rst | ||
Packaging.rst | ||
Passes.rst | ||
Phabricator.rst | ||
ProgrammersManual.rst | ||
Projects.rst | ||
R600Usage.rst | ||
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ReleaseNotes.rst | ||
ReleaseProcess.rst | ||
SegmentedStacks.rst | ||
SourceLevelDebugging.rst | ||
SphinxQuickstartTemplate.rst | ||
StackMaps.rst | ||
SystemLibrary.rst | ||
TableGenFundamentals.rst | ||
TestingGuide.rst | ||
TestSuiteMakefileGuide.rst | ||
Vectorizers.rst | ||
WritingAnLLVMBackend.rst | ||
WritingAnLLVMPass.rst | ||
yaml2obj.rst | ||
YamlIO.rst |
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