[CUDA] Allow function overloads in CUDA based on host/device attributes.

The patch makes it possible to parse CUDA files that contain host/device
functions with identical signatures, but different attributes without
having to physically split source into host-only and device-only parts.

This change is needed in order to parse CUDA header files that have
a lot of name clashes with standard include files.

Gory details are in design doc here: https://goo.gl/EXnymm
Feel free to leave comments there or in this review thread.

This feature is controlled with CC1 option -fcuda-target-overloads
and is disabled by default.

Differential Revision: http://reviews.llvm.org/D12453

llvm-svn: 248295

1 files changed, 6 insertions, 0 deletions

diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 3101fda933c..cdf7d7981bd 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -5515,6 +5515,12 @@ static bool isIncompleteDeclExternC(Sema &S, const T *D) {
     // In C++, the overloadable attribute negates the effects of extern "C".
     if (!D->isInExternCContext() || D->template hasAttr<OverloadableAttr>())
       return false;
+
+    // So do CUDA's host/device attributes if overloading is enabled.
+    if (S.getLangOpts().CUDA && S.getLangOpts().CUDATargetOverloads &&
+        (D->template hasAttr<CUDADeviceAttr>() ||
+         D->template hasAttr<CUDAHostAttr>()))
+      return false;
   }
   return D->isExternC();
 }