versioner: use a virtual filesystem for input files.
Use an InMemoryFileSystem to store and share input files across
compilations.
This improves the result of `time versioner` further, from:
versioner 109.12s user 17.43s system 2433% cpu 5.201 total
to:
versioner 112.20s user 1.38s system 2416% cpu 4.700 total
Bug: http://b/32748936
Test: python run_tests.py
Change-Id: I72d37b7c30850b8399cc40338247700fe3e7b2f9
diff --git a/tools/versioner/src/VFS.h b/tools/versioner/src/VFS.h
new file mode 100644
index 0000000..e2ab002
--- /dev/null
+++ b/tools/versioner/src/VFS.h
@@ -0,0 +1,27 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <memory>
+#include <string>
+
+#include <llvm/ADT/IntrusiveRefCntPtr.h>
+#include <clang/Basic/VirtualFileSystem.h>
+
+llvm::IntrusiveRefCntPtr<clang::vfs::FileSystem> createCommonVFS(const std::string& header_dir,
+ const std::string& dependency_dir,
+ bool add_versioning_header);