3 files changed, 25 insertions, 2 deletions
diff --git a/clang/lib/CodeGen/CGOpenMPRuntime.cpp b/clang/lib/CodeGen/CGOpenMPRuntime.cpp
index c4bfa0363a2..9034829eabe 100644
--- a/clang/lib/CodeGen/CGOpenMPRuntime.cpp
+++ b/clang/lib/CodeGen/CGOpenMPRuntime.cpp
@@ -748,6 +748,14 @@ CGOpenMPRuntime::createRuntimeFunction(OpenMPRTLFunction Function) {
     RTLFn = CGM.CreateRuntimeFunction(FnTy, "__kmpc_end_ordered");
     break;
   }
+  case OMPRTL__kmpc_omp_taskwait: {
+    // Build kmp_int32 __kmpc_omp_taskwait(ident_t *loc, kmp_int32 global_tid);
+    llvm::Type *TypeParams[] = {getIdentTyPointerTy(), CGM.Int32Ty};
+    llvm::FunctionType *FnTy =
+        llvm::FunctionType::get(CGM.Int32Ty, TypeParams, /*isVarArg=*/false);
+    RTLFn = CGM.CreateRuntimeFunction(FnTy, "__kmpc_omp_taskwait");
+    break;
+  }
   }
   return RTLFn;
 }
@@ -2062,6 +2070,15 @@ void CGOpenMPRuntime::emitReduction(CodeGenFunction &CGF, SourceLocation Loc,
   CGF.EmitBlock(DefaultBB, /*IsFinished=*/true);
 }
 
+void CGOpenMPRuntime::emitTaskwaitCall(CodeGenFunction &CGF,
+                                       SourceLocation Loc) {
+  // Build call kmp_int32 __kmpc_omp_taskwait(ident_t *loc, kmp_int32
+  // global_tid);
+  llvm::Value *Args[] = {emitUpdateLocation(CGF, Loc), getThreadID(CGF, Loc)};
+  // Ignore return result until untied tasks are supported.
+  CGF.EmitRuntimeCall(createRuntimeFunction(OMPRTL__kmpc_omp_taskwait), Args);
+}
+
 void CGOpenMPRuntime::emitInlinedDirective(CodeGenFunction &CGF,
                                            const RegionCodeGenTy &CodeGen) {
   InlinedOpenMPRegionRAII Region(CGF, CodeGen);
diff --git a/clang/lib/CodeGen/CGOpenMPRuntime.h b/clang/lib/CodeGen/CGOpenMPRuntime.h
index 08b32d6d127..684d3565945 100644
--- a/clang/lib/CodeGen/CGOpenMPRuntime.h
+++ b/clang/lib/CodeGen/CGOpenMPRuntime.h
@@ -128,6 +128,9 @@ private:
     OMPRTL__kmpc_ordered,
     // Call to void __kmpc_end_ordered(ident_t *loc, kmp_int32 global_tid);
     OMPRTL__kmpc_end_ordered,
+    // Call to kmp_int32 __kmpc_omp_taskwait(ident_t *loc, kmp_int32
+    // global_tid);
+    OMPRTL__kmpc_omp_taskwait,
   };
 
   /// \brief Values for bit flags used in the ident_t to describe the fields.
@@ -602,6 +605,9 @@ public:
                              ArrayRef<const Expr *> RHSExprs,
                              ArrayRef<const Expr *> ReductionOps,
                              bool WithNowait);
+
+  /// \brief Emit code for 'taskwait' directive.
+  virtual void emitTaskwaitCall(CodeGenFunction &CGF, SourceLocation Loc);
 };
 
 } // namespace CodeGen
diff --git a/clang/lib/CodeGen/CGStmtOpenMP.cpp b/clang/lib/CodeGen/CGStmtOpenMP.cpp
index 22f6c3432a0..a31d6bcb484 100644
--- a/clang/lib/CodeGen/CGStmtOpenMP.cpp
+++ b/clang/lib/CodeGen/CGStmtOpenMP.cpp
@@ -1435,8 +1435,8 @@ void CodeGenFunction::EmitOMPBarrierDirective(const OMPBarrierDirective &S) {
   CGM.getOpenMPRuntime().emitBarrierCall(*this, S.getLocStart(), OMPD_barrier);
 }
 
-void CodeGenFunction::EmitOMPTaskwaitDirective(const OMPTaskwaitDirective &) {
-  llvm_unreachable("CodeGen for 'omp taskwait' is not supported yet.");
+void CodeGenFunction::EmitOMPTaskwaitDirective(const OMPTaskwaitDirective &S) {
+  CGM.getOpenMPRuntime().emitTaskwaitCall(*this, S.getLocStart());
 }
 
 void CodeGenFunction::EmitOMPFlushDirective(const OMPFlushDirective &S) {