forked from OSchip/llvm-project
2fb5bc33a3
These linkages were introduced some time ago, but it was never very clear what exactly their semantics were or what they should be used for. Some investigation found these uses: * utf-16 strings in clang. * non-unnamed_addr strings produced by the sanitizers. It turns out they were just working around a more fundamental problem. For some sections a MachO linker needs a symbol in order to split the section into atoms, and llvm had no idea that was the case. I fixed that in r201700 and it is now safe to use the private linkage. When the object ends up in a section that requires symbols, llvm will use a 'l' prefix instead of a 'L' prefix and things just work. With that, these linkages were already dead, but there was a potential future user in the objc metadata information. I am still looking at CGObjcMac.cpp, but at this point I am convinced that linker_private and linker_private_weak are not what they need. The objc uses are currently split in * Regular symbols (no '\01' prefix). LLVM already directly provides whatever semantics they need. * Uses of a private name (start with "\01L" or "\01l") and private linkage. We can drop the "\01L" and "\01l" prefixes as soon as llvm agrees with clang on L being ok or not for a given section. I have two patches in code review for this. * Uses of private name and weak linkage. The last case is the one that one could think would fit one of these linkages. That is not the case. The semantics are * the linker will merge these symbol by *name*. * the linker will hide them in the final DSO. Given that the merging is done by name, any of the private (or internal) linkages would be a bad match. They allow llvm to rename the symbols, and that is really not what we want. From the llvm point of view, these objects should really be (linkonce|weak)(_odr)?. For now, just keeping the "\01l" prefix is probably the best for these symbols. If we one day want to have a more direct support in llvm, IMHO what we should add is not a linkage, it is just a hidden_symbol attribute. It would be applicable to multiple linkages. For example, on weak it would produce the current behavior we have for objc metadata. On internal, it would be equivalent to private (and we should then remove private). llvm-svn: 203866 |
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| .. | ||
| CommandGuide | ||
| HistoricalNotes | ||
| TableGen | ||
| _static | ||
| _templates | ||
| _themes/llvm-theme | ||
| tutorial | ||
| AliasAnalysis.rst | ||
| Atomics.rst | ||
| BitCodeFormat.rst | ||
| BranchWeightMetadata.rst | ||
| Bugpoint.rst | ||
| CMake.rst | ||
| CMakeLists.txt | ||
| CodeGenerator.rst | ||
| CodingStandards.rst | ||
| CommandLine.rst | ||
| CompilerWriterInfo.rst | ||
| DebuggingJITedCode.rst | ||
| DeveloperPolicy.rst | ||
| Dummy.html | ||
| ExceptionHandling.rst | ||
| ExtendedIntegerResults.txt | ||
| ExtendingLLVM.rst | ||
| Extensions.rst | ||
| FAQ.rst | ||
| GarbageCollection.rst | ||
| 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 | ||
| LLVMBuild.rst | ||
| LLVMBuild.txt | ||
| LangRef.rst | ||
| Lexicon.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 | ||
| Makefile | ||
| Makefile.sphinx | ||
| MakefileGuide.rst | ||
| MarkedUpDisassembly.rst | ||
| NVPTXUsage.rst | ||
| Packaging.rst | ||
| Passes.rst | ||
| Phabricator.rst | ||
| ProgrammersManual.rst | ||
| Projects.rst | ||
| README.txt | ||
| ReleaseNotes.rst | ||
| ReleaseProcess.rst | ||
| SegmentedStacks.rst | ||
| SourceLevelDebugging.rst | ||
| SphinxQuickstartTemplate.rst | ||
| StackMaps.rst | ||
| SystemLibrary.rst | ||
| TableGenFundamentals.rst | ||
| TestSuiteMakefileGuide.rst | ||
| TestingGuide.rst | ||
| Vectorizers.rst | ||
| WritingAnLLVMBackend.rst | ||
| WritingAnLLVMPass.rst | ||
| YamlIO.rst | ||
| conf.py | ||
| doxygen.cfg.in | ||
| doxygen.css | ||
| doxygen.footer | ||
| doxygen.header | ||
| doxygen.intro | ||
| 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 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`.