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048eeff265
Summary: Have the cache pass back the path to the cache entry when it is ready to be loaded, instead of a buffer. For gold-plugin we can simply pass this file back to gold directly, which avoids expensive writing of a separate tmp file. Ensure the cache entry is not deleted on cleanup by adjusting the setting of the IsTemporary flags. Moved the loading of the buffer into llvm-lto2 to maintain current behavior. Reviewers: mehdi_amini Subscribers: llvm-commits, mehdi_amini Differential Revision: https://reviews.llvm.org/D23946 llvm-svn: 279883
101 lines
3.4 KiB
C++
101 lines
3.4 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 lto::CacheObjectOutput data structure, which allows
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// clients to add a 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/ADT/SmallString.h"
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#include "llvm/LTO/Config.h"
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#include "llvm/Support/MemoryBuffer.h"
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namespace llvm {
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namespace lto {
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/// Type for client-supplied callback when a buffer is loaded from the cache.
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typedef std::function<void(std::string)> AddBufferFn;
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/// Manage caching on the filesystem.
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///
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/// The general scheme is the following:
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///
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/// void do_stuff(AddBufferFn CallBack) {
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/// /* ... */
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/// {
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/// /* Create the CacheObjectOutput pointing to a cache directory */
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/// auto Output = CacheObjectOutput("/tmp/cache", CallBack)
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///
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/// /* Call some processing function */
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/// process(Output);
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///
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/// } /* Callback is only called now, on destruction of the Output object */
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/// /* ... */
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/// }
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///
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///
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/// void process(NativeObjectOutput &Output) {
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/// /* check if caching is supported */
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/// if (Output.isCachingEnabled()) {
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/// auto Key = ComputeKeyForEntry(...); // "expensive" call
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/// if (Output.tryLoadFromCache())
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/// return; // Cache hit
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/// }
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///
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/// auto OS = Output.getStream();
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///
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/// OS << ...;
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/// /* Note that the callback is not called here, but only when the caller
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/// destroys Output */
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/// }
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///
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class CacheObjectOutput : public NativeObjectOutput {
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/// Path to the on-disk cache directory
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StringRef CacheDirectoryPath;
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/// Path to this entry in the cache, initialized by tryLoadFromCache().
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SmallString<128> EntryPath;
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/// Path to temporary file used to buffer output that will be committed to the
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/// cache entry when this object is destroyed
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SmallString<128> TempFilename;
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/// User-supplied callback, used to provide path to cache entry
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/// (potentially after creating it).
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AddBufferFn AddBuffer;
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public:
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/// The destructor pulls the entry from the cache and calls the AddBuffer
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/// callback, after committing the entry into the cache on miss.
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~CacheObjectOutput();
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/// Create a CacheObjectOutput: the client is supposed to create it in the
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/// callback supplied to LTO::run. The \p CacheDirectoryPath points to the
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/// directory on disk where to store the cache, and \p AddBuffer will be
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/// called when the buffer is ready to be pulled out of the cache
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/// (potentially after creating it).
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CacheObjectOutput(StringRef CacheDirectoryPath, AddBufferFn AddBuffer)
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: CacheDirectoryPath(CacheDirectoryPath), AddBuffer(AddBuffer) {}
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/// Return an allocated stream for the output, or null in case of failure.
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std::unique_ptr<raw_pwrite_stream> getStream() override;
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/// Set EntryPath, try loading from a possible cache first, return true on
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/// cache hit.
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bool tryLoadFromCache(StringRef Key) override;
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/// Returns true to signal that this implementation of NativeObjectFile
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/// support caching.
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bool isCachingEnabled() const override { return true; }
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};
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} // namespace lto
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} // namespace llvm
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#endif
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