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ff87ac19c3
After the call to sys::fs::exists succeeds, indicating a cache hit, we call AddFile and the client will open the file using the supplied path. If the client is using cache pruning, there is a potential race between the pruner and the client. To avoid this, change the caching API so that it provides a MemoryBuffer to the client, and have clients use that MemoryBuffer where possible. This scheme won't work with the gold plugin because the plugin API expects a file path. So we have the gold plugin use the buffer identifier as a path and live with the race for now. (Note that the gold plugin isn't actually affected by the problem at the moment because it doesn't support cache pruning.) This effectively reverts r279883 modulo the change to use the existing path in the gold plugin. Differential Revision: https://reviews.llvm.org/D31063 llvm-svn: 298020
45 lines
1.4 KiB
C++
45 lines
1.4 KiB
C++
//===- Caching.h - LLVM Link Time Optimizer Configuration -----------------===//
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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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//
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// This file defines the localCache function, which allows clients to add a
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// filesystem cache to ThinLTO.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_LTO_CACHING_H
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#define LLVM_LTO_CACHING_H
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#include "llvm/LTO/LTO.h"
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#include <string>
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namespace llvm {
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namespace lto {
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/// This type defines the callback to add a pre-existing native object file
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/// (e.g. in a cache).
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///
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/// MB->getBufferIdentifier() is a valid path for the file at the time that it
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/// was opened, but clients should prefer to access MB directly in order to
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/// avoid a potential race condition.
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///
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/// Buffer callbacks must be thread safe.
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typedef std::function<void(unsigned Task, std::unique_ptr<MemoryBuffer> MB)>
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AddBufferFn;
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/// Create a local file system cache which uses the given cache directory and
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/// file callback. This function also creates the cache directory if it does not
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/// already exist.
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Expected<NativeObjectCache> localCache(StringRef CacheDirectoryPath,
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AddBufferFn AddBuffer);
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} // namespace lto
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} // namespace llvm
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#endif
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