[OpenMP] Add flag for specifying the target device architecture for OpenMP device offloading

Summary:
OpenMP has the ability to offload target regions to devices which may have different architectures.

A new -fopenmp-target-arch flag is introduced to specify the device architecture.

In this patch I use the new flag to specify the compute capability of the underlying NVIDIA architecture for the OpenMP offloading CUDA tool chain.

Only a host-offloading test is provided since full device offloading capability will only be available when [[ https://reviews.llvm.org/D29654 | D29654 ]] lands.

Reviewers: hfinkel, Hahnfeld, carlo.bertolli, caomhin, ABataev

Reviewed By: hfinkel

Subscribers: guansong, cfe-commits

Tags: #openmp

Differential Revision: https://reviews.llvm.org/D34784

llvm-svn: 310263

1 files changed, 6 insertions, 1 deletions

diff --git a/clang/lib/Driver/Compilation.cpp b/clang/lib/Driver/Compilation.cpp
index cf86644..6626662 100644
--- a/clang/lib/Driver/Compilation.cpp
+++ b/clang/lib/Driver/Compilation.cpp
@@ -59,7 +59,12 @@ Compilation::getArgsForToolChain(const ToolChain *TC, StringRef BoundArch,
 
   DerivedArgList *&Entry = TCArgs[{TC, BoundArch, DeviceOffloadKind}];
   if (!Entry) {
-    Entry = TC->TranslateArgs(*TranslatedArgs, BoundArch, DeviceOffloadKind);
+    // Translate OpenMP toolchain arguments provided via the -Xopenmp-target flags.
+    Entry = TC->TranslateOpenMPTargetArgs(*TranslatedArgs, DeviceOffloadKind);
+    if (!Entry)
+      Entry = TranslatedArgs;
+
+    Entry = TC->TranslateArgs(*Entry, BoundArch, DeviceOffloadKind);
     if (!Entry)
       Entry = TranslatedArgs;
   }