1 files changed, 99 insertions, 0 deletions
diff --git a/contrib/llvm/lib/LTO/Caching.cpp b/contrib/llvm/lib/LTO/Caching.cpp
new file mode 100644
index 0000000..fd5bdb0
--- /dev/null
+++ b/contrib/llvm/lib/LTO/Caching.cpp
@@ -0,0 +1,99 @@
+//===-Caching.cpp - LLVM Link Time Optimizer Cache Handling ---------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the Caching for ThinLTO.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/LTO/Caching.h"
+#include "llvm/ADT/StringExtras.h"
+#include "llvm/Support/FileSystem.h"
+#include "llvm/Support/MemoryBuffer.h"
+#include "llvm/Support/Path.h"
+#include "llvm/Support/raw_ostream.h"
+
+using namespace llvm;
+using namespace llvm::lto;
+
+static void commitEntry(StringRef TempFilename, StringRef EntryPath) {
+  // Rename to final destination (hopefully race condition won't matter here)
+  auto EC = sys::fs::rename(TempFilename, EntryPath);
+  if (EC) {
+    // Renaming failed, probably not the same filesystem, copy and delete.
+    // FIXME: Avoid needing to do this by creating the temporary file in the
+    // cache directory.
+    {
+      auto ReloadedBufferOrErr = MemoryBuffer::getFile(TempFilename);
+      if (auto EC = ReloadedBufferOrErr.getError())
+        report_fatal_error(Twine("Failed to open temp file '") + TempFilename +
+                           "': " + EC.message() + "\n");
+
+      raw_fd_ostream OS(EntryPath, EC, sys::fs::F_None);
+      if (EC)
+        report_fatal_error(Twine("Failed to open ") + EntryPath +
+                           " to save cached entry\n");
+      // I'm not sure what are the guarantee if two processes are doing this
+      // at the same time.
+      OS << (*ReloadedBufferOrErr)->getBuffer();
+    }
+    sys::fs::remove(TempFilename);
+  }
+}
+
+NativeObjectCache lto::localCache(std::string CacheDirectoryPath,
+                                  AddFileFn AddFile) {
+  return [=](unsigned Task, StringRef Key) -> AddStreamFn {
+    // First, see if we have a cache hit.
+    SmallString<64> EntryPath;
+    sys::path::append(EntryPath, CacheDirectoryPath, Key);
+    if (sys::fs::exists(EntryPath)) {
+      AddFile(Task, EntryPath);
+      return AddStreamFn();
+    }
+
+    // This native object stream is responsible for commiting the resulting
+    // file to the cache and calling AddFile to add it to the link.
+    struct CacheStream : NativeObjectStream {
+      AddFileFn AddFile;
+      std::string TempFilename;
+      std::string EntryPath;
+      unsigned Task;
+
+      CacheStream(std::unique_ptr<raw_pwrite_stream> OS, AddFileFn AddFile,
+                  std::string TempFilename, std::string EntryPath,
+                  unsigned Task)
+          : NativeObjectStream(std::move(OS)), AddFile(AddFile),
+            TempFilename(TempFilename), EntryPath(EntryPath), Task(Task) {}
+
+      ~CacheStream() {
+        // Make sure the file is closed before committing it.
+        OS.reset();
+        commitEntry(TempFilename, EntryPath);
+        AddFile(Task, EntryPath);
+      }
+    };
+
+    return [=](size_t Task) -> std::unique_ptr<NativeObjectStream> {
+      // Write to a temporary to avoid race condition
+      int TempFD;
+      SmallString<64> TempFilename;
+      std::error_code EC =
+          sys::fs::createTemporaryFile("Thin", "tmp.o", TempFD, TempFilename);
+      if (EC) {
+        errs() << "Error: " << EC.message() << "\n";
+        report_fatal_error("ThinLTO: Can't get a temporary file");
+      }
+
+      // This CacheStream will move the temporary file into the cache when done.
+      return llvm::make_unique<CacheStream>(
+          llvm::make_unique<raw_fd_ostream>(TempFD, /* ShouldClose */ true),
+          AddFile, TempFilename.str(), EntryPath.str(), Task);
+    };
+  };
+}