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e7de338270
This patch adds metadata !noundef and makes load instructions can optionally have it. A load with !noundef always return a well-defined value (has no undef bit or isn't poison). If the loaded value isn't well defined, the behavior is undefined. This metadata can be used to encode the assumption from C/C++ that certain reads of variables should have well-defined values. It is helpful for optimizing freeze instructions away, because freeze can be removed when its operand has well-defined value, and showing that a load from arbitrary location is well-defined is usually hard otherwise. The same information can be encoded with llvm.assume with operand bundle; using metadata is chosen because I wasn't sure whether code motion can be freely done when llvm.assume is inserted from clang instead. The existing codebase already is stripping unknown metadata when doing code motion, so using metadata is UB-safe as well. Reviewed By: jdoerfert Differential Revision: https://reviews.llvm.org/D89050 |
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_ocamldoc | ||
_static | ||
_templates | ||
_themes/llvm-theme | ||
AMDGPU | ||
CommandGuide | ||
DependenceGraphs | ||
Frontend | ||
GlobalISel | ||
HistoricalNotes | ||
PDB | ||
Proposals | ||
TableGen | ||
tutorial | ||
AddingConstrainedIntrinsics.rst | ||
AdvancedBuilds.rst | ||
AliasAnalysis.rst | ||
AMDGPUDwarfExtensionsForHeterogeneousDebugging.rst | ||
AMDGPUInstructionNotation.rst | ||
AMDGPUInstructionSyntax.rst | ||
AMDGPUModifierSyntax.rst | ||
AMDGPUOperandSyntax.rst | ||
AMDGPUUsage.rst | ||
ARM-BE-bitcastfail.png | ||
ARM-BE-bitcastsuccess.png | ||
ARM-BE-ld1.png | ||
ARM-BE-ldr.png | ||
Atomics.rst | ||
Benchmarking.rst | ||
BigEndianNEON.rst | ||
BitCodeFormat.rst | ||
BlockFrequencyTerminology.rst | ||
BranchWeightMetadata.rst | ||
BugLifeCycle.rst | ||
Bugpoint.rst | ||
BugpointRedesign.md | ||
BuildingADistribution.rst | ||
CFIVerify.rst | ||
CMake.rst | ||
CMakeLists.txt | ||
CMakePrimer.rst | ||
CodeGenerator.rst | ||
CodeOfConduct.rst | ||
CodeReview.rst | ||
CodingStandards.rst | ||
CommandLine.rst | ||
CompileCudaWithLLVM.rst | ||
CompilerWriterInfo.rst | ||
conf.py | ||
Contributing.rst | ||
Coroutines.rst | ||
CoverageMappingFormat.rst | ||
DebuggingJITedCode.rst | ||
DeveloperPolicy.rst | ||
Docker.rst | ||
doxygen-mainpage.dox | ||
doxygen.cfg.in | ||
ExceptionHandling.rst | ||
ExtendedIntegerResults.txt | ||
ExtendingLLVM.rst | ||
Extensions.rst | ||
FAQ.rst | ||
FaultMaps.rst | ||
FuzzingLLVM.rst | ||
GarbageCollection.rst | ||
gcc-loops.png | ||
GetElementPtr.rst | ||
GettingInvolved.rst | ||
GettingStarted.rst | ||
GettingStartedTutorials.rst | ||
GettingStartedVS.rst | ||
GitBisecting.rst | ||
GoldPlugin.rst | ||
GwpAsan.rst | ||
HowToAddABuilder.rst | ||
HowToBuildOnARM.rst | ||
HowToBuildWithPGO.rst | ||
HowToCrossCompileBuiltinsOnArm.rst | ||
HowToCrossCompileLLVM.rst | ||
HowToReleaseLLVM.rst | ||
HowToSetUpLLVMStyleRTTI.rst | ||
HowToSubmitABug.rst | ||
HowToUpdateDebugInfo.rst | ||
HowToUseAttributes.rst | ||
HowToUseInstrMappings.rst | ||
InAlloca.rst | ||
index.rst | ||
LangRef.rst | ||
Lexicon.rst | ||
LibFuzzer.rst | ||
LinkTimeOptimization.rst | ||
linpack-pc.png | ||
llvm-objdump.1 | ||
LLVMBuild.rst | ||
LLVMBuild.txt | ||
loop-guard.svg | ||
loop-irreducible.svg | ||
loop-merge.svg | ||
loop-nested.svg | ||
loop-nonmaximal.svg | ||
loop-separate.svg | ||
loop-single.svg | ||
loop-terminology-guarded-loop.png | ||
loop-terminology-initial-loop.png | ||
loop-terminology-rotated-loop.png | ||
loop-terminology.svg | ||
LoopTerminology.rst | ||
make.bat | ||
Makefile.sphinx | ||
MarkdownQuickstartTemplate.md | ||
MarkedUpDisassembly.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 | ||
MeetupGuidelines.rst | ||
MemorySSA.rst | ||
MemTagSanitizer.rst | ||
MergeFunctions.rst | ||
MIRLangRef.rst | ||
NVPTXUsage.rst | ||
OptBisect.rst | ||
ORCv2.rst | ||
Packaging.rst | ||
Passes.rst | ||
Phabricator.rst | ||
ProgrammersManual.rst | ||
Projects.rst | ||
re_format.7 | ||
README.txt | ||
Reference.rst | ||
ReleaseNotes.rst | ||
ReleaseProcess.rst | ||
Remarks.rst | ||
ReportingGuide.rst | ||
ScudoHardenedAllocator.rst | ||
Security.rst | ||
SegmentedStacks.rst | ||
SourceLevelDebugging.rst | ||
speculative_load_hardening_microbenchmarks.png | ||
SpeculativeLoadHardening.md | ||
SphinxQuickstartTemplate.rst | ||
StackMaps.rst | ||
StackSafetyAnalysis.rst | ||
Statepoints.rst | ||
SupportLibrary.rst | ||
SystemLibrary.rst | ||
TableGenFundamentals.rst | ||
TestingGuide.rst | ||
TestSuiteGuide.md | ||
TestSuiteMakefileGuide.rst | ||
TransformMetadata.rst | ||
TypeMetadata.rst | ||
UserGuides.rst | ||
Vectorizers.rst | ||
WritingAnLLVMBackend.rst | ||
WritingAnLLVMNewPMPass.rst | ||
WritingAnLLVMPass.rst | ||
XRay.rst | ||
XRayExample.rst | ||
XRayFDRFormat.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 <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 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