From f43354f69c1f56016a2d7add6155332d866d4a2c Mon Sep 17 00:00:00 2001 From: Bob Wilson Date: Sat, 26 Mar 2016 18:55:13 +0000 Subject: [PATCH] Check if a path is already absolute before trying to make it so. The FileSystem::makeAbsolute function has been calculating the current working directory unconditionally, even when it is not needed. This calls down to llvm::sys::fs::current_path, which is relatively expensive because it stats two directories, regardless of whether those paths are already in the stat cache. The net effect is that when using the VFS, every stat during header search turns into three stats. With this change, we get back to a single stat for absolute directory paths. llvm-svn: 264519 --- clang/lib/Basic/VirtualFileSystem.cpp | 3 +++ 1 file changed, 3 insertions(+) diff --git a/clang/lib/Basic/VirtualFileSystem.cpp b/clang/lib/Basic/VirtualFileSystem.cpp index 83400cf..325e5eb 100644 --- a/clang/lib/Basic/VirtualFileSystem.cpp +++ b/clang/lib/Basic/VirtualFileSystem.cpp @@ -100,6 +100,9 @@ FileSystem::getBufferForFile(const llvm::Twine &Name, int64_t FileSize, } std::error_code FileSystem::makeAbsolute(SmallVectorImpl &Path) const { + if (llvm::sys::path::is_absolute(Path)) + return std::error_code(); + auto WorkingDir = getCurrentWorkingDirectory(); if (!WorkingDir) return WorkingDir.getError(); -- 2.7.4