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Diffstat (limited to 'include/clang/Basic/MemoryBufferCache.h')
-rw-r--r-- | include/clang/Basic/MemoryBufferCache.h | 80 |
1 files changed, 80 insertions, 0 deletions
diff --git a/include/clang/Basic/MemoryBufferCache.h b/include/clang/Basic/MemoryBufferCache.h new file mode 100644 index 0000000000..c79c3c40e4 --- /dev/null +++ b/include/clang/Basic/MemoryBufferCache.h @@ -0,0 +1,80 @@ +//===- MemoryBufferCache.h - Cache for loaded memory buffers ----*- C++ -*-===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// + +#ifndef LLVM_CLANG_BASIC_MEMORYBUFFERCACHE_H +#define LLVM_CLANG_BASIC_MEMORYBUFFERCACHE_H + +#include "llvm/ADT/IntrusiveRefCntPtr.h" +#include "llvm/ADT/StringMap.h" +#include <memory> + +namespace llvm { +class MemoryBuffer; +} // end namespace llvm + +namespace clang { + +/// Manage memory buffers across multiple users. +/// +/// Ensures that multiple users have a consistent view of each buffer. This is +/// used by \a CompilerInstance when building PCMs to ensure that each \a +/// ModuleManager sees the same files. +/// +/// \a finalizeCurrentBuffers() should be called before creating a new user. +/// This locks in the current buffers, ensuring that no buffer that has already +/// been accessed can be purged, preventing use-after-frees. +class MemoryBufferCache : public llvm::RefCountedBase<MemoryBufferCache> { + struct BufferEntry { + std::unique_ptr<llvm::MemoryBuffer> Buffer; + + /// Track the timeline of when this was added to the cache. + unsigned Index; + }; + + /// Cache of buffers. + llvm::StringMap<BufferEntry> Buffers; + + /// Monotonically increasing index. + unsigned NextIndex = 0; + + /// Bumped to prevent "older" buffers from being removed. + unsigned FirstRemovableIndex = 0; + +public: + /// Store the Buffer under the Filename. + /// + /// \pre There is not already buffer is not already in the cache. + /// \return a reference to the buffer as a convenience. + llvm::MemoryBuffer &addBuffer(llvm::StringRef Filename, + std::unique_ptr<llvm::MemoryBuffer> Buffer); + + /// Try to remove a buffer from the cache. + /// + /// \return false on success, iff \c !isBufferFinal(). + bool tryToRemoveBuffer(llvm::StringRef Filename); + + /// Get a pointer to the buffer if it exists; else nullptr. + llvm::MemoryBuffer *lookupBuffer(llvm::StringRef Filename); + + /// Check whether the buffer is final. + /// + /// \return true iff \a finalizeCurrentBuffers() has been called since the + /// buffer was added. This prevents buffers from being removed. + bool isBufferFinal(llvm::StringRef Filename); + + /// Finalize the current buffers in the cache. + /// + /// Should be called when creating a new user to ensure previous uses aren't + /// invalidated. + void finalizeCurrentBuffers(); +}; + +} // end namespace clang + +#endif // LLVM_CLANG_BASIC_MEMORYBUFFERCACHE_H |