Eliminate unnecessary file access checks in Clang driver on Windows

Differential Revision: http://reviews.llvm.org/D20454

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@270226 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Driver/MSVCToolChain.cpp b/lib/Driver/MSVCToolChain.cpp
index a80ad60cc188986f514a57d5d407c5c11c98e215..4af142de9220e5453632f34bd543884ec0664931 100644 (file)
--- a/lib/Driver/MSVCToolChain.cpp
+++ b/lib/Driver/MSVCToolChain.cpp
@@ -408,7 +408,10 @@ bool MSVCToolChain::getVisualStudioBinariesFolder(const char *clangProgramPath,
 
         SmallString<128> FilePath(PathSegment);
         llvm::sys::path::append(FilePath, "cl.exe");
-        if (llvm::sys::fs::can_execute(FilePath.c_str()) &&
+        // Checking if cl.exe exists is a small optimization over calling
+        // can_execute, which really only checks for existence but will also do
+        // extra checks for cl.exe.exe.  These add up when walking a long path.
+        if (llvm::sys::fs::exists(FilePath.c_str()) &&
             !llvm::sys::fs::equivalent(FilePath.c_str(), clangProgramPath)) {
           // If we found it on the PATH, use it exactly as is with no
           // modifications.