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cded1d3751
Summary: The LLVM SourceMgr class (which is used indirectly by Swift, though not Clang) has a routine for looking up line numbers of SMLocs. This routine uses a shared, special-purpose cache that handles exactly one access pattern efficiently: looking up the line number of an SMLoc that points into the same buffer as the last query made to the SourceMgr, at a location in the buffer at or ahead of the last query. When this works it's fine, but when it fails it's catastrophic for performancer: one recent out-of-order access from a Swift utility routine ran for tens of seconds, spending 99% of its time repeatedly scanning buffers for '\n'. This change removes the shared cache from the SourceMgr and installs a new cache in each SrcBuffer. The per-SrcBuffer caches are also "full", in the sense that rather than caching a single last-query pointer, they cache _all_ the line-ending offsets, in a binary-searchable array, such that once it's populated (on first access), all subsequent access patterns run at the same speed. Performance measurements I've done show this is actually a little bit faster on real codebases (though only a couple fractions of a percent). Memory usage is up by a few tens to hundreds of bytes per SrcBuffer that has a line lookup done on it; I've attempted to minimize this by using dynamic selection of integer sized when storing offset arrays. But the main motive here is to make-impossible the cases we don't always see, that show up by surprise when there is an out-of-order access pattern. Reviewers: jordan_rose Reviewed By: jordan_rose Subscribers: probinson, llvm-commits Differential Revision: https://reviews.llvm.org/D45003 llvm-svn: 329470 |
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| .. | ||
| DynamicLibrary | ||
| AlignOfTest.cpp | ||
| AllocatorTest.cpp | ||
| ARMAttributeParser.cpp | ||
| ArrayRecyclerTest.cpp | ||
| BinaryStreamTest.cpp | ||
| BlockFrequencyTest.cpp | ||
| BranchProbabilityTest.cpp | ||
| CachePruningTest.cpp | ||
| Casting.cpp | ||
| CheckedArithmeticTest.cpp | ||
| Chrono.cpp | ||
| CMakeLists.txt | ||
| CommandLineTest.cpp | ||
| CompressionTest.cpp | ||
| ConvertUTFTest.cpp | ||
| CrashRecoveryTest.cpp | ||
| DataExtractorTest.cpp | ||
| DebugTest.cpp | ||
| DJBTest.cpp | ||
| EndianStreamTest.cpp | ||
| EndianTest.cpp | ||
| ErrnoTest.cpp | ||
| ErrorOrTest.cpp | ||
| ErrorTest.cpp | ||
| FileOutputBufferTest.cpp | ||
| formatted_raw_ostream_test.cpp | ||
| FormatVariadicTest.cpp | ||
| GlobPatternTest.cpp | ||
| Host.cpp | ||
| LEB128Test.cpp | ||
| LineIteratorTest.cpp | ||
| LockFileManagerTest.cpp | ||
| ManagedStatic.cpp | ||
| MathExtrasTest.cpp | ||
| MD5Test.cpp | ||
| MemoryBufferTest.cpp | ||
| MemoryTest.cpp | ||
| NativeFormatTests.cpp | ||
| ParallelTest.cpp | ||
| Path.cpp | ||
| ProcessTest.cpp | ||
| ProgramTest.cpp | ||
| raw_ostream_test.cpp | ||
| raw_pwrite_stream_test.cpp | ||
| raw_sha1_ostream_test.cpp | ||
| RegexTest.cpp | ||
| ReplaceFileTest.cpp | ||
| ReverseIterationTest.cpp | ||
| ScaledNumberTest.cpp | ||
| SourceMgrTest.cpp | ||
| SpecialCaseListTest.cpp | ||
| StringPool.cpp | ||
| SwapByteOrderTest.cpp | ||
| TargetParserTest.cpp | ||
| TarWriterTest.cpp | ||
| Threading.cpp | ||
| ThreadLocalTest.cpp | ||
| ThreadPool.cpp | ||
| TimerTest.cpp | ||
| TrailingObjectsTest.cpp | ||
| TrigramIndexTest.cpp | ||
| TypeNameTest.cpp | ||
| UnicodeTest.cpp | ||
| xxhashTest.cpp | ||
| YAMLIOTest.cpp | ||
| YAMLParserTest.cpp | ||