[CUDA] Initialize our header search using the host triple.

Summary:
This used to work because system headers are found in a (somewhat)
predictable set of locations on Linux.  But this is not the case on
MacOS; without this change, we don't look in the right places for our
headers when doing device-side compilation on Mac.

Reviewers: tra

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D26776

llvm-svn: 287286

1 files changed, 9 insertions, 2 deletions

diff --git a/clang/lib/Frontend/CompilerInstance.cpp b/clang/lib/Frontend/CompilerInstance.cpp
index b96dc70cf5b..6fb880f7867 100644
--- a/clang/lib/Frontend/CompilerInstance.cpp
+++ b/clang/lib/Frontend/CompilerInstance.cpp
@@ -334,9 +334,16 @@ void CompilerInstance::createPreprocessor(TranslationUnitKind TUKind) {
   InitializePreprocessor(*PP, PPOpts, getPCHContainerReader(),
                          getFrontendOpts());
 
-  // Initialize the header search object.
+  // Initialize the header search object.  In CUDA compilations, we use the aux
+  // triple (the host triple) to initialize our header search, since we need to
+  // find the host headers in order to compile the CUDA code.
+  const llvm::Triple *HeaderSearchTriple = &PP->getTargetInfo().getTriple();
+  if (PP->getTargetInfo().getTriple().getOS() == llvm::Triple::CUDA &&
+      PP->getAuxTargetInfo())
+    HeaderSearchTriple = &PP->getAuxTargetInfo()->getTriple();
+
   ApplyHeaderSearchOptions(PP->getHeaderSearchInfo(), getHeaderSearchOpts(),
-                           PP->getLangOpts(), PP->getTargetInfo().getTriple());
+                           PP->getLangOpts(), *HeaderSearchTriple);
 
   PP->setPreprocessedOutput(getPreprocessorOutputOpts().ShowCPP);