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80186a57d6
The NativeObjectOutput class has a design problem: it mixes up the caching policy with the interface for output streams, which makes the client-side code hard to follow and would for example make it harder to replace the cache implementation in an arbitrary client. This change separates the two aspects by moving the caching policy to a separate field in Config, replacing NativeObjectOutput with a NativeObjectStream class which only deals with streams and does not need to be overridden by most clients and introducing an AddFile callback for adding files (e.g. from the cache) to the link. Differential Revision: https://reviews.llvm.org/D24622 llvm-svn: 282299
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 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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