[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

2 files changed, 19 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/CGOpenMPRuntimeNVPTX.cpp b/clang/lib/CodeGen/CGOpenMPRuntimeNVPTX.cpp
index f87649c7d6b..6b5591b8b5c 100644
--- a/clang/lib/CodeGen/CGOpenMPRuntimeNVPTX.cpp
+++ b/clang/lib/CodeGen/CGOpenMPRuntimeNVPTX.cpp
@@ -642,6 +642,17 @@ CGOpenMPRuntimeNVPTX::CGOpenMPRuntimeNVPTX(CodeGenModule &CGM)
     llvm_unreachable("OpenMP NVPTX can only handle device code.");
 }
 
+void CGOpenMPRuntimeNVPTX::emitNumThreadsClause(CodeGenFunction &CGF,
+                                                llvm::Value *NumThreads,
+                                                SourceLocation Loc) {
+  // Do nothing in case of Spmd mode and L0 parallel.
+  // TODO: If in Spmd mode and L1 parallel emit the clause.
+  if (isInSpmdExecutionMode())
+    return;
+
+  CGOpenMPRuntime::emitNumThreadsClause(CGF, NumThreads, Loc);
+}
+
 void CGOpenMPRuntimeNVPTX::emitNumTeamsClause(CodeGenFunction &CGF,
                                               const Expr *NumTeams,
                                               const Expr *ThreadLimit,
diff --git a/clang/lib/CodeGen/CGOpenMPRuntimeNVPTX.h b/clang/lib/CodeGen/CGOpenMPRuntimeNVPTX.h
index 96478707fce..7a68c76664f 100644
--- a/clang/lib/CodeGen/CGOpenMPRuntimeNVPTX.h
+++ b/clang/lib/CodeGen/CGOpenMPRuntimeNVPTX.h
@@ -170,6 +170,14 @@ protected:
 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.