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| Rev | Author | Line No. | Line |
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| 14 | pmbaty | 1 | //===- InMemoryModuleCache.h - In-memory cache for modules ------*- C++ -*-===// |
| 2 | // |
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| 3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
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| 4 | // See https://llvm.org/LICENSE.txt for license information. |
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| 5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
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| 6 | // |
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| 7 | //===----------------------------------------------------------------------===// |
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| 8 | |||
| 9 | #ifndef LLVM_CLANG_SERIALIZATION_INMEMORYMODULECACHE_H |
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| 10 | #define LLVM_CLANG_SERIALIZATION_INMEMORYMODULECACHE_H |
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| 11 | |||
| 12 | #include "llvm/ADT/IntrusiveRefCntPtr.h" |
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| 13 | #include "llvm/ADT/StringMap.h" |
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| 14 | #include "llvm/Support/MemoryBuffer.h" |
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| 15 | #include <memory> |
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| 16 | |||
| 17 | namespace clang { |
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| 18 | |||
| 19 | /// In-memory cache for modules. |
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| 20 | /// |
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| 21 | /// This is a cache for modules for use across a compilation, sharing state |
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| 22 | /// between the CompilerInstances in an implicit modules build. It must be |
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| 23 | /// shared by each CompilerInstance, ASTReader, ASTWriter, and ModuleManager |
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| 24 | /// that are coordinating. |
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| 25 | /// |
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| 26 | /// Critically, it ensures that a single process has a consistent view of each |
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| 27 | /// PCM. This is used by \a CompilerInstance when building PCMs to ensure that |
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| 28 | /// each \a ModuleManager sees the same files. |
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| 29 | class InMemoryModuleCache : public llvm::RefCountedBase<InMemoryModuleCache> { |
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| 30 | struct PCM { |
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| 31 | std::unique_ptr<llvm::MemoryBuffer> Buffer; |
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| 32 | |||
| 33 | /// Track whether this PCM is known to be good (either built or |
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| 34 | /// successfully imported by a CompilerInstance/ASTReader using this |
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| 35 | /// cache). |
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| 36 | bool IsFinal = false; |
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| 37 | |||
| 38 | PCM() = default; |
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| 39 | PCM(std::unique_ptr<llvm::MemoryBuffer> Buffer) |
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| 40 | : Buffer(std::move(Buffer)) {} |
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| 41 | }; |
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| 42 | |||
| 43 | /// Cache of buffers. |
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| 44 | llvm::StringMap<PCM> PCMs; |
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| 45 | |||
| 46 | public: |
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| 47 | /// There are four states for a PCM. It must monotonically increase. |
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| 48 | /// |
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| 49 | /// 1. Unknown: the PCM has neither been read from disk nor built. |
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| 50 | /// 2. Tentative: the PCM has been read from disk but not yet imported or |
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| 51 | /// built. It might work. |
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| 52 | /// 3. ToBuild: the PCM read from disk did not work but a new one has not |
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| 53 | /// been built yet. |
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| 54 | /// 4. Final: indicating that the current PCM was either built in this |
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| 55 | /// process or has been successfully imported. |
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| 56 | enum State { Unknown, Tentative, ToBuild, Final }; |
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| 57 | |||
| 58 | /// Get the state of the PCM. |
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| 59 | State getPCMState(llvm::StringRef Filename) const; |
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| 60 | |||
| 61 | /// Store the PCM under the Filename. |
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| 62 | /// |
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| 63 | /// \pre state is Unknown |
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| 64 | /// \post state is Tentative |
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| 65 | /// \return a reference to the buffer as a convenience. |
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| 66 | llvm::MemoryBuffer &addPCM(llvm::StringRef Filename, |
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| 67 | std::unique_ptr<llvm::MemoryBuffer> Buffer); |
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| 68 | |||
| 69 | /// Store a just-built PCM under the Filename. |
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| 70 | /// |
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| 71 | /// \pre state is Unknown or ToBuild. |
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| 72 | /// \pre state is not Tentative. |
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| 73 | /// \return a reference to the buffer as a convenience. |
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| 74 | llvm::MemoryBuffer &addBuiltPCM(llvm::StringRef Filename, |
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| 75 | std::unique_ptr<llvm::MemoryBuffer> Buffer); |
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| 76 | |||
| 77 | /// Try to remove a buffer from the cache. No effect if state is Final. |
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| 78 | /// |
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| 79 | /// \pre state is Tentative/Final. |
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| 80 | /// \post Tentative => ToBuild or Final => Final. |
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| 81 | /// \return false on success, i.e. if Tentative => ToBuild. |
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| 82 | bool tryToDropPCM(llvm::StringRef Filename); |
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| 83 | |||
| 84 | /// Mark a PCM as final. |
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| 85 | /// |
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| 86 | /// \pre state is Tentative or Final. |
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| 87 | /// \post state is Final. |
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| 88 | void finalizePCM(llvm::StringRef Filename); |
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| 89 | |||
| 90 | /// Get a pointer to the pCM if it exists; else nullptr. |
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| 91 | llvm::MemoryBuffer *lookupPCM(llvm::StringRef Filename) const; |
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| 92 | |||
| 93 | /// Check whether the PCM is final and has been shown to work. |
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| 94 | /// |
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| 95 | /// \return true iff state is Final. |
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| 96 | bool isPCMFinal(llvm::StringRef Filename) const; |
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| 97 | |||
| 98 | /// Check whether the PCM is waiting to be built. |
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| 99 | /// |
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| 100 | /// \return true iff state is ToBuild. |
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| 101 | bool shouldBuildPCM(llvm::StringRef Filename) const; |
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| 102 | }; |
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| 103 | |||
| 104 | } // end namespace clang |
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| 105 | |||
| 106 | #endif // LLVM_CLANG_SERIALIZATION_INMEMORYMODULECACHE_H |