[clang] 0e916bf - Driver: Improve performance of getSDKName()

[Adrian Prantl via cfe-commits]

Author: Adrian Prantl
Date: 2020-03-20T16:41:59-07:00
New Revision: 0e916bf9f5e4a51af621fd72ccf4b00b7e6f86fa

URL: https://github.com/llvm/llvm-project/commit/0e916bf9f5e4a51af621fd72ccf4b00b7e6f86fa
DIFF: https://github.com/llvm/llvm-project/commit/0e916bf9f5e4a51af621fd72ccf4b00b7e6f86fa.diff

LOG: Driver: Improve performance of getSDKName()

The ".sdk" component is usually the last one in the -isysroot, so it
makes more sense to scan from the back. Also, technically, someone
could install Xcode into a directory ending with .sdk, which would
break this heuristic.

Differential Revision: https://reviews.llvm.org/D76097

Added: 
    

Modified: 
    clang/lib/Driver/ToolChains/Darwin.cpp

Removed: 
    


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diff  --git a/clang/lib/Driver/ToolChains/Darwin.cpp b/clang/lib/Driver/ToolChains/Darwin.cpp
index ab3a68b70f5d..a5c08b405914 100644
--- a/clang/lib/Driver/ToolChains/Darwin.cpp
+++ b/clang/lib/Driver/ToolChains/Darwin.cpp
@@ -1068,8 +1068,8 @@ StringRef Darwin::getPlatformFamily() const {
 
 StringRef Darwin::getSDKName(StringRef isysroot) {
   // Assume SDK has path: SOME_PATH/SDKs/PlatformXX.YY.sdk
-  auto BeginSDK = llvm::sys::path::begin(isysroot);
-  auto EndSDK = llvm::sys::path::end(isysroot);
+  auto BeginSDK = llvm::sys::path::rbegin(isysroot);
+  auto EndSDK = llvm::sys::path::rend(isysroot);
   for (auto IT = BeginSDK; IT != EndSDK; ++IT) {
     StringRef SDK = *IT;
     if (SDK.endswith(".sdk"))