[OpenMP] Support for the num_threads-clause on 'target parallel' on the NVPTX device.

This patch adds support for the Spmd construct 'target parallel' on the
NVPTX device. This involves ignoring the num_threads clause on the device
since the number of threads in this combined construct is already set on
the host through the call to __tgt_target_teams().

Reviewers: ABataev
Differential Revision: https://reviews.llvm.org/D29083

llvm-svn: 292999
diff --git a/clang/lib/CodeGen/CGOpenMPRuntimeNVPTX.h b/clang/lib/CodeGen/CGOpenMPRuntimeNVPTX.h
index 9647870..7a68c76 100644
--- a/clang/lib/CodeGen/CGOpenMPRuntimeNVPTX.h
+++ b/clang/lib/CodeGen/CGOpenMPRuntimeNVPTX.h
@@ -170,6 +170,14 @@
 public:
   explicit CGOpenMPRuntimeNVPTX(CodeGenModule &CGM);
 
+  /// \brief Emits call to void __kmpc_push_num_threads(ident_t *loc, kmp_int32
+  /// global_tid, kmp_int32 num_threads) to generate code for 'num_threads'
+  /// clause.
+  /// \param NumThreads An integer value of threads.
+  virtual void emitNumThreadsClause(CodeGenFunction &CGF,
+                                    llvm::Value *NumThreads,
+                                    SourceLocation Loc) override;
+
   /// \brief This function ought to emit, in the general case, a call to
   // the openmp runtime kmpc_push_num_teams. In NVPTX backend it is not needed
   // as these numbers are obtained through the PTX grid and block configuration.