forked from OSchip/llvm-project
2c74fe977d
This patch implements Chandler's idea [0] for supporting languages that require support for infinite loops with side effects, such as Rust, providing part of a solution to bug 965 [1]. Specifically, it adds an `llvm.sideeffect()` intrinsic, which has no actual effect, but which appears to optimization passes to have obscure side effects, such that they don't optimize away loops containing it. It also teaches several optimization passes to ignore this intrinsic, so that it doesn't significantly impact optimization in most cases. As discussed on llvm-dev [2], this patch is the first of two major parts. The second part, to change LLVM's semantics to have defined behavior on infinite loops by default, with a function attribute for opting into potential-undefined-behavior, will be implemented and posted for review in a separate patch. [0] http://lists.llvm.org/pipermail/llvm-dev/2015-July/088103.html [1] https://bugs.llvm.org/show_bug.cgi?id=965 [2] http://lists.llvm.org/pipermail/llvm-dev/2017-October/118632.html Differential Revision: https://reviews.llvm.org/D38336 llvm-svn: 317729 |
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CommandGuide | ||
Frontend | ||
HistoricalNotes | ||
PDB | ||
Proposals | ||
TableGen | ||
_ocamldoc | ||
_static | ||
_templates | ||
_themes/llvm-theme | ||
tutorial | ||
AMDGPUUsage.rst | ||
ARM-BE-bitcastfail.png | ||
ARM-BE-bitcastsuccess.png | ||
ARM-BE-ld1.png | ||
ARM-BE-ldr.png | ||
AdvancedBuilds.rst | ||
AliasAnalysis.rst | ||
Atomics.rst | ||
Benchmarking.rst | ||
BigEndianNEON.rst | ||
BitCodeFormat.rst | ||
BlockFrequencyTerminology.rst | ||
BranchWeightMetadata.rst | ||
Bugpoint.rst | ||
CFIVerify.rst | ||
CMake.rst | ||
CMakeLists.txt | ||
CMakePrimer.rst | ||
CodeGenerator.rst | ||
CodeOfConduct.rst | ||
CodingStandards.rst | ||
CommandLine.rst | ||
CompileCudaWithLLVM.rst | ||
CompilerWriterInfo.rst | ||
Coroutines.rst | ||
CoverageMappingFormat.rst | ||
DebuggingJITedCode.rst | ||
DeveloperPolicy.rst | ||
Docker.rst | ||
ExceptionHandling.rst | ||
ExtendedIntegerResults.txt | ||
ExtendingLLVM.rst | ||
Extensions.rst | ||
FAQ.rst | ||
FaultMaps.rst | ||
FuzzingLLVM.rst | ||
GarbageCollection.rst | ||
GetElementPtr.rst | ||
GettingStarted.rst | ||
GettingStartedVS.rst | ||
GlobalISel.rst | ||
GoldPlugin.rst | ||
HowToAddABuilder.rst | ||
HowToBuildOnARM.rst | ||
HowToCrossCompileBuiltinsOnArm.rst | ||
HowToCrossCompileLLVM.rst | ||
HowToReleaseLLVM.rst | ||
HowToSetUpLLVMStyleRTTI.rst | ||
HowToSubmitABug.rst | ||
HowToUseAttributes.rst | ||
HowToUseInstrMappings.rst | ||
InAlloca.rst | ||
LLVMBuild.rst | ||
LLVMBuild.txt | ||
LangRef.rst | ||
Lexicon.rst | ||
LibFuzzer.rst | ||
LinkTimeOptimization.rst | ||
MCJIT-creation.png | ||
MCJIT-dyld-load.png | ||
MCJIT-engine-builder.png | ||
MCJIT-load-object.png | ||
MCJIT-load.png | ||
MCJIT-resolve-relocations.png | ||
MCJITDesignAndImplementation.rst | ||
MIRLangRef.rst | ||
Makefile.sphinx | ||
MarkedUpDisassembly.rst | ||
MemorySSA.rst | ||
MergeFunctions.rst | ||
NVPTXUsage.rst | ||
OptBisect.rst | ||
Packaging.rst | ||
Passes.rst | ||
Phabricator.rst | ||
ProgrammersManual.rst | ||
Projects.rst | ||
README.txt | ||
ReleaseNotes.rst | ||
ReleaseProcess.rst | ||
ReportingGuide.rst | ||
ScudoHardenedAllocator.rst | ||
SegmentedStacks.rst | ||
SourceLevelDebugging.rst | ||
SphinxQuickstartTemplate.rst | ||
StackMaps.rst | ||
Statepoints.rst | ||
SystemLibrary.rst | ||
TableGenFundamentals.rst | ||
TestSuiteMakefileGuide.rst | ||
TestingGuide.rst | ||
TypeMetadata.rst | ||
Vectorizers.rst | ||
WritingAnLLVMBackend.rst | ||
WritingAnLLVMPass.rst | ||
XRay.rst | ||
XRayExample.rst | ||
XRayFDRFormat.rst | ||
YamlIO.rst | ||
conf.py | ||
doxygen-mainpage.dox | ||
doxygen.cfg.in | ||
gcc-loops.png | ||
index.rst | ||
linpack-pc.png | ||
make.bat | ||
re_format.7 | ||
yaml2obj.rst |
README.txt
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 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