[Driver][OpenMP] Add support to create jobs for unbundling actions.

Summary:
This patch adds the support to create jobs for the `OffloadBundlingAction` which will invoke the `clang-offload-bundler` tool to unbundle input files.

Unlike other actions, unbundling actions have multiple outputs. Therefore, this patch adds the required changes to have a variant of `Tool::ConstructJob` with multiple outputs. 

The way the naming of the results is implemented is also slightly modified so that the same action can use a different offloading prefix for each use by the different offloading actions. 

With this patch, it is possible to compile a functional OpenMP binary with offloading support, even with separate compilation.

Reviewers: echristo, tra, jlebar, ABataev, hfinkel

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

Differential Revision: https://reviews.llvm.org/D21857

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@285326 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 8 insertions, 5 deletions

diff --git a/lib/Driver/Action.cpp b/lib/Driver/Action.cpp
index ad6fb71810..4e0c224c3b 100644
--- a/lib/Driver/Action.cpp
+++ b/lib/Driver/Action.cpp
@@ -115,15 +115,18 @@ std::string Action::getOffloadingKindPrefix() const {
   return Res;
 }
 
+/// Return a string that can be used as prefix in order to generate unique files
+/// for each offloading kind.
 std::string
-Action::getOffloadingFileNamePrefix(llvm::StringRef NormalizedTriple) const {
-  // A file prefix is only generated for device actions and consists of the
-  // offload kind and triple.
-  if (!OffloadingDeviceKind)
+Action::GetOffloadingFileNamePrefix(OffloadKind Kind,
+                                    llvm::StringRef NormalizedTriple,
+                                    bool CreatePrefixForHost) {
+  // Don't generate prefix for host actions unless required.
+  if (!CreatePrefixForHost && (Kind == OFK_None || Kind == OFK_Host))
     return "";
 
   std::string Res("-");
-  Res += getOffloadingKindPrefix();
+  Res += GetOffloadKindName(Kind);
   Res += "-";
   Res += NormalizedTriple;
   return Res;