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