[CUDA][OpenMP] Add a generic offload action builder

Summary:
This patch proposes a new class to generate and record action dependences related with offloading. The builder provides three main functionalities:
- Add device dependences to host actions.
- Add host dependence to device actions.
- Register device top-level actions.

The constructor of the builder detect the programming models that should be supported, and generates a specialized builder for each. If a new programming model is to be added in the future, only a new specialized builder has to be implemented. 

When the specialized builder is generated, it produces programming-model-specific diagnostics.

A CUDA specialized builder is proposed in the patch that mostly consists of the partition of the current  `buildCudaAction` by the three different functionalities.

Reviewers: tra, echristo, ABataev, jlebar, hfinkel

Subscribers: Hahnfeld, whchung, guansong, jlebar, mehdi_amini, andreybokhanko, tcramer, mkuron, cfe-commits, arpith-jacob, carlo.bertolli, caomhin

Differential Revision: https://reviews.llvm.org/D18172

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@282865 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 6 insertions, 0 deletions

diff --git a/include/clang/Driver/Compilation.h b/include/clang/Driver/Compilation.h
index 8846b6f6b3..b87a121187 100644
--- a/include/clang/Driver/Compilation.h
+++ b/include/clang/Driver/Compilation.h
@@ -115,6 +115,12 @@ public:
     return OrderedOffloadingToolchains.equal_range(Kind);
   }
 
+  /// Return true if an offloading tool chain of a given kind exists.
+  template <Action::OffloadKind Kind> bool hasOffloadToolChain() const {
+    return OrderedOffloadingToolchains.find(Kind) !=
+           OrderedOffloadingToolchains.end();
+  }
+
   /// Return an offload toolchain of the provided kind. Only one is expected to
   /// exist.
   template <Action::OffloadKind Kind>