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102 lines
4.1 KiB
C++
102 lines
4.1 KiB
C++
//===-Caching.cpp - LLVM Link Time Optimizer Cache Handling ---------------===//
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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 implements the Caching for ThinLTO.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/LTO/Caching.h"
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#include "llvm/ADT/StringExtras.h"
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#include "llvm/Support/Errc.h"
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#include "llvm/Support/FileSystem.h"
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#include "llvm/Support/MemoryBuffer.h"
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#include "llvm/Support/Path.h"
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#include "llvm/Support/raw_ostream.h"
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using namespace llvm;
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using namespace llvm::lto;
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Expected<NativeObjectCache> lto::localCache(StringRef CacheDirectoryPath,
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AddBufferFn AddBuffer) {
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if (std::error_code EC = sys::fs::create_directories(CacheDirectoryPath))
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return errorCodeToError(EC);
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return [=](unsigned Task, StringRef Key) -> AddStreamFn {
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// This choice of file name allows the cache to be pruned (see pruneCache()
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// in include/llvm/Support/CachePruning.h).
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SmallString<64> EntryPath;
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sys::path::append(EntryPath, CacheDirectoryPath, "llvmcache-" + Key);
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// First, see if we have a cache hit.
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ErrorOr<std::unique_ptr<MemoryBuffer>> MBOrErr =
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MemoryBuffer::getFile(EntryPath);
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if (MBOrErr) {
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AddBuffer(Task, std::move(*MBOrErr));
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return AddStreamFn();
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}
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if (MBOrErr.getError() != errc::no_such_file_or_directory)
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report_fatal_error(Twine("Failed to open cache file ") + EntryPath +
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": " + MBOrErr.getError().message() + "\n");
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// This native object stream is responsible for commiting the resulting
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// file to the cache and calling AddBuffer to add it to the link.
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struct CacheStream : NativeObjectStream {
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AddBufferFn AddBuffer;
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std::string TempFilename;
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std::string EntryPath;
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unsigned Task;
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CacheStream(std::unique_ptr<raw_pwrite_stream> OS, AddBufferFn AddBuffer,
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std::string TempFilename, std::string EntryPath,
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unsigned Task)
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: NativeObjectStream(std::move(OS)), AddBuffer(std::move(AddBuffer)),
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TempFilename(std::move(TempFilename)),
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EntryPath(std::move(EntryPath)), Task(Task) {}
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~CacheStream() {
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// FIXME: This code could race with the cache pruner, but it is unlikely
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// that the cache pruner will choose to remove a newly created file.
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// Make sure the file is closed before committing it.
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OS.reset();
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// This is atomic on POSIX systems.
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if (auto EC = sys::fs::rename(TempFilename, EntryPath))
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report_fatal_error(Twine("Failed to rename temporary file ") +
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TempFilename + ": " + EC.message() + "\n");
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ErrorOr<std::unique_ptr<MemoryBuffer>> MBOrErr =
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MemoryBuffer::getFile(EntryPath);
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if (!MBOrErr)
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report_fatal_error(Twine("Failed to open cache file ") + EntryPath +
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": " + MBOrErr.getError().message() + "\n");
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AddBuffer(Task, std::move(*MBOrErr));
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}
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};
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return [=](size_t Task) -> std::unique_ptr<NativeObjectStream> {
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// Write to a temporary to avoid race condition
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int TempFD;
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SmallString<64> TempFilenameModel, TempFilename;
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sys::path::append(TempFilenameModel, CacheDirectoryPath, "Thin-%%%%%%.tmp.o");
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std::error_code EC =
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sys::fs::createUniqueFile(TempFilenameModel, TempFD, TempFilename,
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sys::fs::owner_read | sys::fs::owner_write);
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if (EC) {
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errs() << "Error: " << EC.message() << "\n";
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report_fatal_error("ThinLTO: Can't get a temporary file");
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}
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// This CacheStream will move the temporary file into the cache when done.
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return llvm::make_unique<CacheStream>(
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llvm::make_unique<raw_fd_ostream>(TempFD, /* ShouldClose */ true),
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AddBuffer, TempFilename.str(), EntryPath.str(), Task);
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};
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};
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}
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