forked from OSchip/llvm-project
d889d1efef
Add support for continuously syncing profile counter updates to a file. The motivation for this is that programs do not always exit cleanly. On iOS, for example, programs are usually killed via a signal from the OS. Running atexit() handlers after catching a signal is unreliable, so some method for progressively writing out profile data is necessary. The approach taken here is to mmap() the `__llvm_prf_cnts` section onto a raw profile. To do this, the linker must page-align the counter and data sections, and the runtime must ensure that counters are mapped to a page-aligned offset within a raw profile. Continuous mode is (for the moment) incompatible with the online merging mode. This limitation is lifted in https://reviews.llvm.org/D69586. Continuous mode is also (for the moment) incompatible with value profiling, as I'm not sure whether there is interest in this and the implementation may be tricky. As I have not been able to test extensively on non-Darwin platforms, only Darwin support is included for the moment. However, continuous mode may "just work" without modification on Linux and some UNIX-likes. AIUI the default value for the GNU linker's `--section-alignment` flag is set to the page size on many systems. This appears to be true for LLD as well, as its `no_nmagic` option is on by default. Continuous mode will not "just work" on Fuchsia or Windows, as it's not possible to mmap() a section on these platforms. There is a proposal to add a layer of indirection to the profile instrumentation to support these platforms. rdar://54210980 Differential Revision: https://reviews.llvm.org/D68351 |
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| .. | ||
| CommandGuide | ||
| analyzer | ||
| tools | ||
| AddressSanitizer.rst | ||
| AttributeReference.rst | ||
| AutomaticReferenceCounting.rst | ||
| Block-ABI-Apple.rst | ||
| Block-ABI-Apple.txt | ||
| BlockLanguageSpec.rst | ||
| CMakeLists.txt | ||
| ClangCheck.rst | ||
| ClangCommandLineReference.rst | ||
| ClangFormat.rst | ||
| ClangFormatStyleOptions.rst | ||
| ClangPlugins.rst | ||
| ClangStaticAnalyzer.rst | ||
| ClangTools.rst | ||
| ConstantInterpreter.rst | ||
| ControlFlowIntegrity.rst | ||
| ControlFlowIntegrityDesign.rst | ||
| CrossCompilation.rst | ||
| DataFlowSanitizer.rst | ||
| DataFlowSanitizerDesign.rst | ||
| DiagnosticsReference.rst | ||
| DriverArchitecture.png | ||
| DriverInternals.rst | ||
| ExternalClangExamples.rst | ||
| FAQ.rst | ||
| HardwareAssistedAddressSanitizerDesign.rst | ||
| HowToSetupToolingForLLVM.rst | ||
| InternalsManual.rst | ||
| IntroductionToTheClangAST.rst | ||
| ItaniumMangleAbiTags.rst | ||
| JSONCompilationDatabase.rst | ||
| LTOVisibility.rst | ||
| LanguageExtensions.rst | ||
| LeakSanitizer.rst | ||
| LibASTImporter.rst | ||
| LibASTMatchers.rst | ||
| LibASTMatchersReference.html | ||
| LibASTMatchersTutorial.rst | ||
| LibFormat.rst | ||
| LibTooling.rst | ||
| MSVCCompatibility.rst | ||
| Makefile.sphinx | ||
| MemorySanitizer.rst | ||
| Modules.rst | ||
| ObjectiveCLiterals.rst | ||
| OpenCLSupport.rst | ||
| OpenMPSupport.rst | ||
| PCHInternals.rst | ||
| PCHLayout.graffle | ||
| PCHLayout.png | ||
| RAVFrontendAction.rst | ||
| README.txt | ||
| RefactoringEngine.rst | ||
| ReleaseNotes.rst | ||
| SafeStack.rst | ||
| SanitizerCoverage.rst | ||
| SanitizerSpecialCaseList.rst | ||
| SanitizerStats.rst | ||
| ShadowCallStack.rst | ||
| SourceBasedCodeCoverage.rst | ||
| ThinLTO.rst | ||
| ThreadSafetyAnalysis.rst | ||
| ThreadSanitizer.rst | ||
| Toolchain.rst | ||
| Tooling.rst | ||
| UndefinedBehaviorSanitizer.rst | ||
| UsersManual.rst | ||
| conf.py | ||
| doxygen-mainpage.dox | ||
| doxygen.cfg.in | ||
| index.rst | ||
| make.bat | ||
README.txt
See llvm/docs/README.txt