16 files changed, 102 insertions, 8 deletions

diff --git a/clang/include/clang/AST/DataRecursiveASTVisitor.h b/clang/include/clang/AST/DataRecursiveASTVisitor.h
index 541886c0c18..f9de4fb9c32 100644
--- a/clang/include/clang/AST/DataRecursiveASTVisitor.h
+++ b/clang/include/clang/AST/DataRecursiveASTVisitor.h
@@ -2392,6 +2392,12 @@ bool RecursiveASTVisitor<Derived>::VisitOMPUntiedClause(OMPUntiedClause *) {
 }
 
 template <typename Derived>
+bool
+RecursiveASTVisitor<Derived>::VisitOMPMergeableClause(OMPMergeableClause *) {
+  return true;
+}
+
+template <typename Derived>
 template <typename T>
 bool RecursiveASTVisitor<Derived>::VisitOMPClauseList(T *Node) {
   for (auto *E : Node->varlists()) {
diff --git a/clang/include/clang/AST/OpenMPClause.h b/clang/include/clang/AST/OpenMPClause.h
index 4173e91d78b..009d8839b54 100644
--- a/clang/include/clang/AST/OpenMPClause.h
+++ b/clang/include/clang/AST/OpenMPClause.h
@@ -740,6 +740,36 @@ public:
   StmtRange children() { return StmtRange(); }
 };
 
+/// \brief This represents 'mergeable' clause in the '#pragma omp ...'
+/// directive.
+///
+/// \code
+/// #pragma omp task mergeable
+/// \endcode
+/// In this example directive '#pragma omp task' has 'mergeable' clause.
+///
+class OMPMergeableClause : public OMPClause {
+public:
+  /// \brief Build 'mergeable' clause.
+  ///
+  /// \param StartLoc Starting location of the clause.
+  /// \param EndLoc Ending location of the clause.
+  ///
+  OMPMergeableClause(SourceLocation StartLoc, SourceLocation EndLoc)
+      : OMPClause(OMPC_mergeable, StartLoc, EndLoc) {}
+
+  /// \brief Build an empty clause.
+  ///
+  OMPMergeableClause()
+      : OMPClause(OMPC_mergeable, SourceLocation(), SourceLocation()) {}
+
+  static bool classof(const OMPClause *T) {
+    return T->getClauseKind() == OMPC_mergeable;
+  }
+
+  StmtRange children() { return StmtRange(); }
+};
+
 /// \brief This represents clause 'private' in the '#pragma omp ...' directives.
 ///
 /// \code
diff --git a/clang/include/clang/AST/RecursiveASTVisitor.h b/clang/include/clang/AST/RecursiveASTVisitor.h
index 9178f67aa10..f427dd82b2a 100644
--- a/clang/include/clang/AST/RecursiveASTVisitor.h
+++ b/clang/include/clang/AST/RecursiveASTVisitor.h
@@ -2414,6 +2414,12 @@ bool RecursiveASTVisitor<Derived>::VisitOMPUntiedClause(OMPUntiedClause *) {
 }
 
 template <typename Derived>
+bool
+RecursiveASTVisitor<Derived>::VisitOMPMergeableClause(OMPMergeableClause *) {
+  return true;
+}
+
+template <typename Derived>
 template <typename T>
 bool RecursiveASTVisitor<Derived>::VisitOMPClauseList(T *Node) {
   for (auto *E : Node->varlists()) {
diff --git a/clang/include/clang/Basic/OpenMPKinds.def b/clang/include/clang/Basic/OpenMPKinds.def
index 6da343e05f9..91b026e2c3a 100644
--- a/clang/include/clang/Basic/OpenMPKinds.def
+++ b/clang/include/clang/Basic/OpenMPKinds.def
@@ -89,6 +89,7 @@ OPENMP_CLAUSE(schedule, OMPScheduleClause)
 OPENMP_CLAUSE(ordered, OMPOrderedClause)
 OPENMP_CLAUSE(nowait, OMPNowaitClause)
 OPENMP_CLAUSE(untied, OMPUntiedClause)
+OPENMP_CLAUSE(mergeable, OMPMergeableClause)
 
 // Clauses allowed for OpenMP directive 'parallel'.
 OPENMP_PARALLEL_CLAUSE(if)
@@ -176,7 +177,7 @@ OPENMP_PARALLEL_SECTIONS_CLAUSE(reduction)
 OPENMP_PARALLEL_SECTIONS_CLAUSE(copyin)
 OPENMP_PARALLEL_SECTIONS_CLAUSE(lastprivate)
 
-// TODO more clauses allowed for OpenMP directive 'task'.
+// Clauses allowed for OpenMP directive 'task'.
 OPENMP_TASK_CLAUSE(if)
 OPENMP_TASK_CLAUSE(final)
 OPENMP_TASK_CLAUSE(default)
@@ -184,6 +185,7 @@ OPENMP_TASK_CLAUSE(private)
 OPENMP_TASK_CLAUSE(firstprivate)
 OPENMP_TASK_CLAUSE(shared)
 OPENMP_TASK_CLAUSE(untied)
+OPENMP_TASK_CLAUSE(mergeable)
 
 #undef OPENMP_SCHEDULE_KIND
 #undef OPENMP_PROC_BIND_KIND
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index 283dfb6acdb..0ca5a545a7b 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -7443,6 +7443,9 @@ public:
   /// \brief Called on well-formed 'untied' clause.
   OMPClause *ActOnOpenMPUntiedClause(SourceLocation StartLoc,
                                      SourceLocation EndLoc);
+  /// \brief Called on well-formed 'mergeable' clause.
+  OMPClause *ActOnOpenMPMergeableClause(SourceLocation StartLoc,
+                                        SourceLocation EndLoc);
 
   OMPClause *
   ActOnOpenMPVarListClause(OpenMPClauseKind Kind, ArrayRef<Expr *> Vars,
diff --git a/clang/lib/AST/StmtPrinter.cpp b/clang/lib/AST/StmtPrinter.cpp
index 29d958bacff..da9a41339b2 100644
--- a/clang/lib/AST/StmtPrinter.cpp
+++ b/clang/lib/AST/StmtPrinter.cpp
@@ -661,6 +661,10 @@ void OMPClausePrinter::VisitOMPUntiedClause(OMPUntiedClause *) {
   OS << "untied";
 }
 
+void OMPClausePrinter::VisitOMPMergeableClause(OMPMergeableClause *) {
+  OS << "mergeable";
+}
+
 template<typename T>
 void OMPClausePrinter::VisitOMPClauseList(T *Node, char StartSym) {
   for (typename T::varlist_iterator I = Node->varlist_begin(),
diff --git a/clang/lib/AST/StmtProfile.cpp b/clang/lib/AST/StmtProfile.cpp
index b17551cd407..c4289dffba0 100644
--- a/clang/lib/AST/StmtProfile.cpp
+++ b/clang/lib/AST/StmtProfile.cpp
@@ -308,6 +308,8 @@ void OMPClauseProfiler::VisitOMPNowaitClause(const OMPNowaitClause *) {}
 
 void OMPClauseProfiler::VisitOMPUntiedClause(const OMPUntiedClause *) {}
 
+void OMPClauseProfiler::VisitOMPMergeableClause(const OMPMergeableClause *) {}
+
 template<typename T>
 void OMPClauseProfiler::VisitOMPClauseList(T *Node) {
   for (auto *I : Node->varlists())
diff --git a/clang/lib/Basic/OpenMPKinds.cpp b/clang/lib/Basic/OpenMPKinds.cpp
index d8af63f1d03..7e00b7ad453 100644
--- a/clang/lib/Basic/OpenMPKinds.cpp
+++ b/clang/lib/Basic/OpenMPKinds.cpp
@@ -104,6 +104,7 @@ unsigned clang::getOpenMPSimpleClauseType(OpenMPClauseKind Kind,
   case OMPC_ordered:
   case OMPC_nowait:
   case OMPC_untied:
+  case OMPC_mergeable:
     break;
   }
   llvm_unreachable("Invalid OpenMP simple clause kind");
@@ -161,6 +162,7 @@ const char *clang::getOpenMPSimpleClauseTypeName(OpenMPClauseKind Kind,
   case OMPC_ordered:
   case OMPC_nowait:
   case OMPC_untied:
+  case OMPC_mergeable:
     break;
   }
   llvm_unreachable("Invalid OpenMP simple clause kind");
diff --git a/clang/lib/Parse/ParseOpenMP.cpp b/clang/lib/Parse/ParseOpenMP.cpp
index 9f1fa0af154..cfe160216f8 100644
--- a/clang/lib/Parse/ParseOpenMP.cpp
+++ b/clang/lib/Parse/ParseOpenMP.cpp
@@ -292,7 +292,8 @@ bool Parser::ParseOpenMPSimpleVarList(OpenMPDirectiveKind Kind,
 ///       default-clause | private-clause | firstprivate-clause | shared-clause
 ///       | linear-clause | aligned-clause | collapse-clause |
 ///       lastprivate-clause | reduction-clause | proc_bind-clause |
-///       schedule-clause | copyin-clause | copyprivate-clause | untied-clause
+///       schedule-clause | copyin-clause | copyprivate-clause | untied-clause |
+///       mergeable-clause
 ///
 OMPClause *Parser::ParseOpenMPClause(OpenMPDirectiveKind DKind,
                                      OpenMPClauseKind CKind, bool FirstClause) {
@@ -354,6 +355,7 @@ OMPClause *Parser::ParseOpenMPClause(OpenMPDirectiveKind DKind,
   case OMPC_ordered:
   case OMPC_nowait:
   case OMPC_untied:
+  case OMPC_mergeable:
     // OpenMP [2.7.1, Restrictions, p. 9]
     //  Only one ordered clause can appear on a loop directive.
     // OpenMP [2.7.1, Restrictions, C/C++, p. 4]
@@ -472,6 +474,9 @@ OMPClause *Parser::ParseOpenMPSimpleClause(OpenMPClauseKind Kind) {
 ///    untied-clause:
 ///         'untied'
 ///
+///    mergeable-clause:
+///         'mergeable'
+///
 OMPClause *Parser::ParseOpenMPClause(OpenMPClauseKind Kind) {
   SourceLocation Loc = Tok.getLocation();
   ConsumeAnyToken();
diff --git a/clang/lib/Sema/SemaOpenMP.cpp b/clang/lib/Sema/SemaOpenMP.cpp
index 85a9ccffd8c..9f63dbbc472 100644
--- a/clang/lib/Sema/SemaOpenMP.cpp
+++ b/clang/lib/Sema/SemaOpenMP.cpp
@@ -2069,6 +2069,7 @@ OMPClause *Sema::ActOnOpenMPSingleExprClause(OpenMPClauseKind Kind, Expr *Expr,
   case OMPC_ordered:
   case OMPC_nowait:
   case OMPC_untied:
+  case OMPC_mergeable:
   case OMPC_threadprivate:
   case OMPC_unknown:
     llvm_unreachable("Clause is not allowed.");
@@ -2270,6 +2271,7 @@ OMPClause *Sema::ActOnOpenMPSimpleClause(
   case OMPC_ordered:
   case OMPC_nowait:
   case OMPC_untied:
+  case OMPC_mergeable:
   case OMPC_threadprivate:
   case OMPC_unknown:
     llvm_unreachable("Clause is not allowed.");
@@ -2383,6 +2385,7 @@ OMPClause *Sema::ActOnOpenMPSingleExprWithArgClause(
   case OMPC_ordered:
   case OMPC_nowait:
   case OMPC_untied:
+  case OMPC_mergeable:
   case OMPC_threadprivate:
   case OMPC_unknown:
     llvm_unreachable("Clause is not allowed.");
@@ -2460,6 +2463,9 @@ OMPClause *Sema::ActOnOpenMPClause(OpenMPClauseKind Kind,
   case OMPC_untied:
     Res = ActOnOpenMPUntiedClause(StartLoc, EndLoc);
     break;
+  case OMPC_mergeable:
+    Res = ActOnOpenMPMergeableClause(StartLoc, EndLoc);
+    break;
   case OMPC_if:
   case OMPC_final:
   case OMPC_num_threads:
@@ -2499,6 +2505,11 @@ OMPClause *Sema::ActOnOpenMPUntiedClause(SourceLocation StartLoc,
   return new (Context) OMPUntiedClause(StartLoc, EndLoc);
 }
 
+OMPClause *Sema::ActOnOpenMPMergeableClause(SourceLocation StartLoc,
+                                            SourceLocation EndLoc) {
+  return new (Context) OMPMergeableClause(StartLoc, EndLoc);
+}
+
 OMPClause *Sema::ActOnOpenMPVarListClause(
     OpenMPClauseKind Kind, ArrayRef<Expr *> VarList, Expr *TailExpr,
     SourceLocation StartLoc, SourceLocation LParenLoc, SourceLocation ColonLoc,
@@ -2547,6 +2558,7 @@ OMPClause *Sema::ActOnOpenMPVarListClause(
   case OMPC_ordered:
   case OMPC_nowait:
   case OMPC_untied:
+  case OMPC_mergeable:
   case OMPC_threadprivate:
   case OMPC_unknown:
     llvm_unreachable("Clause is not allowed.");
diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h
index 4a9cd78bb6e..0f1d24c4403 100644
--- a/clang/lib/Sema/TreeTransform.h
+++ b/clang/lib/Sema/TreeTransform.h
@@ -6653,6 +6653,13 @@ TreeTransform<Derived>::TransformOMPUntiedClause(OMPUntiedClause *C) {
 
 template <typename Derived>
 OMPClause *
+TreeTransform<Derived>::TransformOMPMergeableClause(OMPMergeableClause *C) {
+  // No need to rebuild this clause, no template-dependent parameters.
+  return C;
+}
+
+template <typename Derived>
+OMPClause *
 TreeTransform<Derived>::TransformOMPPrivateClause(OMPPrivateClause *C) {
   llvm::SmallVector<Expr *, 16> Vars;
   Vars.reserve(C->varlist_size());
diff --git a/clang/lib/Serialization/ASTReaderStmt.cpp b/clang/lib/Serialization/ASTReaderStmt.cpp
index 4986e2e47e7..c89c939cace 100644
--- a/clang/lib/Serialization/ASTReaderStmt.cpp
+++ b/clang/lib/Serialization/ASTReaderStmt.cpp
@@ -1712,6 +1712,9 @@ OMPClause *OMPClauseReader::readClause() {
   case OMPC_untied:
     C = new (Context) OMPUntiedClause();
     break;
+  case OMPC_mergeable:
+    C = new (Context) OMPMergeableClause();
+    break;
   case OMPC_private:
     C = OMPPrivateClause::CreateEmpty(Context, Record[Idx++]);
     break;
@@ -1801,6 +1804,8 @@ void OMPClauseReader::VisitOMPNowaitClause(OMPNowaitClause *) {}
 
 void OMPClauseReader::VisitOMPUntiedClause(OMPUntiedClause *) {}
 
+void OMPClauseReader::VisitOMPMergeableClause(OMPMergeableClause *) {}
+
 void OMPClauseReader::VisitOMPPrivateClause(OMPPrivateClause *C) {
   C->setLParenLoc(Reader->ReadSourceLocation(Record, Idx));
   unsigned NumVars = C->varlist_size();
diff --git a/clang/lib/Serialization/ASTWriterStmt.cpp b/clang/lib/Serialization/ASTWriterStmt.cpp
index 6edad3ddf5d..38bcdbea8f3 100644
--- a/clang/lib/Serialization/ASTWriterStmt.cpp
+++ b/clang/lib/Serialization/ASTWriterStmt.cpp
@@ -1733,6 +1733,8 @@ void OMPClauseWriter::VisitOMPNowaitClause(OMPNowaitClause *) {}
 
 void OMPClauseWriter::VisitOMPUntiedClause(OMPUntiedClause *) {}
 
+void OMPClauseWriter::VisitOMPMergeableClause(OMPMergeableClause *) {}
+
 void OMPClauseWriter::VisitOMPPrivateClause(OMPPrivateClause *C) {
   Record.push_back(C->varlist_size());
   Writer->Writer.AddSourceLocation(C->getLParenLoc(), Record);
diff --git a/clang/test/OpenMP/task_ast_print.cpp b/clang/test/OpenMP/task_ast_print.cpp
index f29b5b3fe71..2b43c0b0896 100644
--- a/clang/test/OpenMP/task_ast_print.cpp
+++ b/clang/test/OpenMP/task_ast_print.cpp
@@ -37,7 +37,7 @@ T tmain(T argc, T *argv) {
   a = 2;
 #pragma omp task default(none), private(argc, b) firstprivate(argv) shared(d) if (argc > 0) final(S<T>::TS > 0)
   foo();
-#pragma omp task if (C)
+#pragma omp task if (C) mergeable
   foo();
   return 0;
 }
@@ -50,7 +50,7 @@ T tmain(T argc, T *argv) {
 // CHECK-NEXT: a = 2;
 // CHECK-NEXT: #pragma omp task default(none) private(argc,b) firstprivate(argv) shared(d) if(argc > 0) final(S<int>::TS > 0)
 // CHECK-NEXT: foo()
-// CHECK-NEXT: #pragma omp task if(5)
+// CHECK-NEXT: #pragma omp task if(5) mergeable
 // CHECK-NEXT: foo()
 // CHECK: template <typename T = long, int C = 1> long tmain(long argc, long *argv) {
 // CHECK-NEXT: long b = argc, c, d, e, f, g;
@@ -60,7 +60,7 @@ T tmain(T argc, T *argv) {
 // CHECK-NEXT: a = 2;
 // CHECK-NEXT: #pragma omp task default(none) private(argc,b) firstprivate(argv) shared(d) if(argc > 0) final(S<long>::TS > 0)
 // CHECK-NEXT: foo()
-// CHECK-NEXT: #pragma omp task if(1)
+// CHECK-NEXT: #pragma omp task if(1) mergeable
 // CHECK-NEXT: foo()
 // CHECK: template <typename T, int C> T tmain(T argc, T *argv) {
 // CHECK-NEXT: T b = argc, c, d, e, f, g;
@@ -70,7 +70,7 @@ T tmain(T argc, T *argv) {
 // CHECK-NEXT: a = 2;
 // CHECK-NEXT: #pragma omp task default(none) private(argc,b) firstprivate(argv) shared(d) if(argc > 0) final(S<T>::TS > 0)
 // CHECK-NEXT: foo()
-// CHECK-NEXT: #pragma omp task if(C)
+// CHECK-NEXT: #pragma omp task if(C) mergeable
 // CHECK-NEXT: foo()
 
 enum Enum {};
@@ -82,8 +82,8 @@ int main(int argc, char **argv) {
 #pragma omp threadprivate(a)
   Enum ee;
 // CHECK: Enum ee;
-#pragma omp task untied
-  // CHECK-NEXT: #pragma omp task untied
+#pragma omp task untied mergeable
+  // CHECK-NEXT: #pragma omp task untied mergeable
   a = 2;
 // CHECK-NEXT: a = 2;
 #pragma omp task default(none), private(argc, b) firstprivate(argv) if (argc > 0) final(a > 0)
diff --git a/clang/test/OpenMP/task_messages.cpp b/clang/test/OpenMP/task_messages.cpp
index 7491c23b739..88c339afc11 100644
--- a/clang/test/OpenMP/task_messages.cpp
+++ b/clang/test/OpenMP/task_messages.cpp
@@ -100,6 +100,9 @@ int foo() {
 // expected-error@+1 {{directive '#pragma omp task' cannot contain more than one 'untied' clause}}
 #pragma omp task untied untied
   ++r;
+// expected-error@+1 {{directive '#pragma omp task' cannot contain more than one 'mergeable' clause}}
+#pragma omp task mergeable mergeable
+  ++r;
   return a + b;
 }
 
@@ -262,6 +265,9 @@ L2:
 // expected-error@+1 {{directive '#pragma omp task' cannot contain more than one 'untied' clause}}
 #pragma omp task untied untied
   ++r;
+// expected-error@+1 {{directive '#pragma omp task' cannot contain more than one 'mergeable' clause}}
+#pragma omp task mergeable mergeable
+  ++r;
   // expected-note@+2 {{in instantiation of function template specialization 'foo<int>' requested here}}
   // expected-note@+1 {{in instantiation of function template specialization 'foo<S>' requested here}}
   return foo<int>() + foo<S>();
diff --git a/clang/tools/libclang/CIndex.cpp b/clang/tools/libclang/CIndex.cpp
index e83a659b1f2..54b6db22972 100644
--- a/clang/tools/libclang/CIndex.cpp
+++ b/clang/tools/libclang/CIndex.cpp
@@ -1970,6 +1970,8 @@ void OMPClauseEnqueue::VisitOMPNowaitClause(const OMPNowaitClause *) {}
 
 void OMPClauseEnqueue::VisitOMPUntiedClause(const OMPUntiedClause *) {}
 
+void OMPClauseEnqueue::VisitOMPMergeableClause(const OMPMergeableClause *) {}
+
 template<typename T>
 void OMPClauseEnqueue::VisitOMPClauseList(T *Node) {
   for (const auto *I : Node->varlists())