[CUDA][OpenMP] Create generic offload toolchains

Summary:
This patch introduces the concept of offloading tool chain and offloading kind. Each tool chain may have associated an offloading kind that marks it as used in a given programming model that requires offloading. 

It also adds the logic to iterate on the tool chains based on the kind. Currently, only CUDA is supported, but in general a programming model (an offloading kind) may have associated multiple tool chains that require supporting offloading.

This patch does not add tests - its goal is to keep the existing functionality.

This patch is the first of a series of three that attempts to make the current support of CUDA more generic and easier to extend to other programming models, namely OpenMP. It tries to capture the suggestions/improvements/concerns on the initial proposal in  http://lists.llvm.org/pipermail/cfe-dev/2016-February/047547.html. It only tackles the more consensual part of the proposal, i.e.does not address the problem of intermediate files bundling yet.

Reviewers: ABataev, jlebar, echristo, hfinkel, tra

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

Differential Revision: http://reviews.llvm.org/D18170

llvm-svn: 272571

1 files changed, 6 insertions, 3 deletions

diff --git a/clang/lib/Driver/Compilation.cpp b/clang/lib/Driver/Compilation.cpp
index b24d381..46548e6 100644
--- a/clang/lib/Driver/Compilation.cpp
+++ b/clang/lib/Driver/Compilation.cpp
@@ -24,10 +24,13 @@ using namespace llvm::opt;
 
 Compilation::Compilation(const Driver &D, const ToolChain &_DefaultToolChain,
                          InputArgList *_Args, DerivedArgList *_TranslatedArgs)
-    : TheDriver(D), DefaultToolChain(_DefaultToolChain),
-      CudaHostToolChain(&DefaultToolChain), CudaDeviceToolChain(nullptr),
+    : TheDriver(D), DefaultToolChain(_DefaultToolChain), ActiveOffloadMask(0u),
       Args(_Args), TranslatedArgs(_TranslatedArgs), Redirects(nullptr),
-      ForDiagnostics(false) {}
+      ForDiagnostics(false) {
+  // The offloading host toolchain is the default tool chain.
+  OrderedOffloadingToolchains.insert(
+      std::make_pair(Action::OFK_Host, &DefaultToolChain));
+}
 
 Compilation::~Compilation() {
   delete TranslatedArgs;