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100 lines
3.6 KiB
C++
100 lines
3.6 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/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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static void commitEntry(StringRef TempFilename, StringRef EntryPath) {
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// Rename to final destination (hopefully race condition won't matter here)
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auto EC = sys::fs::rename(TempFilename, EntryPath);
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if (EC) {
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// Renaming failed, probably not the same filesystem, copy and delete.
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// FIXME: Avoid needing to do this by creating the temporary file in the
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// cache directory.
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{
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auto ReloadedBufferOrErr = MemoryBuffer::getFile(TempFilename);
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if (auto EC = ReloadedBufferOrErr.getError())
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report_fatal_error(Twine("Failed to open temp file '") + TempFilename +
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"': " + EC.message() + "\n");
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raw_fd_ostream OS(EntryPath, EC, sys::fs::F_None);
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if (EC)
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report_fatal_error(Twine("Failed to open ") + EntryPath +
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" to save cached entry\n");
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// I'm not sure what are the guarantee if two processes are doing this
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// at the same time.
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OS << (*ReloadedBufferOrErr)->getBuffer();
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}
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sys::fs::remove(TempFilename);
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}
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}
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NativeObjectCache lto::localCache(std::string CacheDirectoryPath,
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AddFileFn AddFile) {
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return [=](unsigned Task, StringRef Key) -> AddStreamFn {
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// First, see if we have a cache hit.
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SmallString<64> EntryPath;
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sys::path::append(EntryPath, CacheDirectoryPath, Key);
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if (sys::fs::exists(EntryPath)) {
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AddFile(Task, EntryPath);
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return AddStreamFn();
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}
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// This native object stream is responsible for commiting the resulting
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// file to the cache and calling AddFile to add it to the link.
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struct CacheStream : NativeObjectStream {
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AddFileFn AddFile;
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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, AddFileFn AddFile,
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std::string TempFilename, std::string EntryPath,
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unsigned Task)
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: NativeObjectStream(std::move(OS)), AddFile(AddFile),
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TempFilename(TempFilename), EntryPath(EntryPath), Task(Task) {}
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~CacheStream() {
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// Make sure the file is closed before committing it.
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OS.reset();
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commitEntry(TempFilename, EntryPath);
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AddFile(Task, EntryPath);
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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> TempFilename;
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std::error_code EC =
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sys::fs::createTemporaryFile("Thin", "tmp.o", TempFD, TempFilename);
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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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AddFile, TempFilename.str(), EntryPath.str(), Task);
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};
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};
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}
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