Add support for 'atomic_default_mem_order' clause on 'requires' directive. Also renamed test files relating to 'requires'. Differntial review: https://reviews.llvm.org/D53513

llvm-svn: 345967

20 files changed, 253 insertions, 7 deletions

diff --git a/clang/include/clang/AST/OpenMPClause.h b/clang/include/clang/AST/OpenMPClause.h
index de2eb0c5d0f..e93f7e2b3e9 100644
--- a/clang/include/clang/AST/OpenMPClause.h
+++ b/clang/include/clang/AST/OpenMPClause.h
@@ -859,6 +859,85 @@ public:
   }
 };
 
+/// This represents 'atomic_default_mem_order' clause in the '#pragma omp
+/// requires'  directive.
+///
+/// \code
+/// #pragma omp requires atomic_default_mem_order(seq_cst)
+/// \endcode
+/// In this example directive '#pragma omp requires' has simple
+/// atomic_default_mem_order' clause with kind 'seq_cst'.
+class OMPAtomicDefaultMemOrderClause final : public OMPClause {
+  friend class OMPClauseReader;
+
+  /// Location of '('
+  SourceLocation LParenLoc;
+
+  /// A kind of the 'atomic_default_mem_order' clause.
+  OpenMPAtomicDefaultMemOrderClauseKind Kind =
+      OMPC_ATOMIC_DEFAULT_MEM_ORDER_unknown;
+
+  /// Start location of the kind in source code.
+  SourceLocation KindKwLoc;
+
+  /// Set kind of the clause.
+  ///
+  /// \param K Kind of clause.
+  void setAtomicDefaultMemOrderKind(OpenMPAtomicDefaultMemOrderClauseKind K) {
+    Kind = K;
+  }
+
+  /// Set clause kind location.
+  ///
+  /// \param KLoc Kind location.
+  void setAtomicDefaultMemOrderKindKwLoc(SourceLocation KLoc) {
+    KindKwLoc = KLoc;
+  }
+
+public:
+  /// Build 'atomic_default_mem_order' clause with argument \a A ('seq_cst',
+  /// 'acq_rel' or 'relaxed').
+  ///
+  /// \param A Argument of the clause ('seq_cst', 'acq_rel' or 'relaxed').
+  /// \param ALoc Starting location of the argument.
+  /// \param StartLoc Starting location of the clause.
+  /// \param LParenLoc Location of '('.
+  /// \param EndLoc Ending location of the clause.
+  OMPAtomicDefaultMemOrderClause(OpenMPAtomicDefaultMemOrderClauseKind A,
+                                 SourceLocation ALoc, SourceLocation StartLoc,
+                                 SourceLocation LParenLoc,
+                                 SourceLocation EndLoc)
+      : OMPClause(OMPC_atomic_default_mem_order, StartLoc, EndLoc),
+        LParenLoc(LParenLoc), Kind(A), KindKwLoc(ALoc) {}
+
+  /// Build an empty clause.
+  OMPAtomicDefaultMemOrderClause()
+      : OMPClause(OMPC_atomic_default_mem_order, SourceLocation(),
+                  SourceLocation()) {}
+
+  /// Sets the location of '('.
+  void setLParenLoc(SourceLocation Loc) { LParenLoc = Loc; }
+
+  /// Returns the locaiton of '('.
+  SourceLocation getLParenLoc() const { return LParenLoc; }
+
+  /// Returns kind of the clause.
+  OpenMPAtomicDefaultMemOrderClauseKind getAtomicDefaultMemOrderKind() const {
+    return Kind;
+  }
+
+  /// Returns location of clause kind.
+  SourceLocation getAtomicDefaultMemOrderKindKwLoc() const { return KindKwLoc; }
+
+  child_range children() {
+    return child_range(child_iterator(), child_iterator());
+  }
+
+  static bool classof(const OMPClause *T) {
+    return T->getClauseKind() == OMPC_atomic_default_mem_order;
+  }
+};
+
 /// This represents 'schedule' clause in the '#pragma omp ...' directive.
 ///
 /// \code
diff --git a/clang/include/clang/AST/RecursiveASTVisitor.h b/clang/include/clang/AST/RecursiveASTVisitor.h
index a19ea31433e..c2a13df6525 100644
--- a/clang/include/clang/AST/RecursiveASTVisitor.h
+++ b/clang/include/clang/AST/RecursiveASTVisitor.h
@@ -2888,6 +2888,12 @@ bool RecursiveASTVisitor<Derived>::VisitOMPDynamicAllocatorsClause(
 }
 
 template <typename Derived>
+bool RecursiveASTVisitor<Derived>::VisitOMPAtomicDefaultMemOrderClause(
+    OMPAtomicDefaultMemOrderClause *) {
+  return true;
+}
+
+template <typename Derived>
 bool
 RecursiveASTVisitor<Derived>::VisitOMPScheduleClause(OMPScheduleClause *C) {
   TRY_TO(VisitOMPClauseWithPreInit(C));
diff --git a/clang/include/clang/Basic/OpenMPKinds.def b/clang/include/clang/Basic/OpenMPKinds.def
index ad40d3f819f..eb9881115cc 100644
--- a/clang/include/clang/Basic/OpenMPKinds.def
+++ b/clang/include/clang/Basic/OpenMPKinds.def
@@ -126,6 +126,9 @@
 #ifndef OPENMP_DEFAULTMAP_KIND
 #define OPENMP_DEFAULTMAP_KIND(Name)
 #endif
+#ifndef OPENMP_ATOMIC_DEFAULT_MEM_ORDER_KIND
+#define OPENMP_ATOMIC_DEFAULT_MEM_ORDER_KIND(Name)
+#endif
 #ifndef OPENMP_DEFAULTMAP_MODIFIER
 #define OPENMP_DEFAULTMAP_MODIFIER(Name)
 #endif
@@ -283,6 +286,7 @@ OPENMP_CLAUSE(unified_address, OMPUnifiedAddressClause)
 OPENMP_CLAUSE(unified_shared_memory, OMPUnifiedSharedMemoryClause)
 OPENMP_CLAUSE(reverse_offload, OMPReverseOffloadClause)
 OPENMP_CLAUSE(dynamic_allocators, OMPDynamicAllocatorsClause)
+OPENMP_CLAUSE(atomic_default_mem_order, OMPAtomicDefaultMemOrderClause)
 
 // Clauses allowed for OpenMP directive 'parallel'.
 OPENMP_PARALLEL_CLAUSE(if)
@@ -469,6 +473,12 @@ OPENMP_REQUIRES_CLAUSE(unified_address)
 OPENMP_REQUIRES_CLAUSE(unified_shared_memory)
 OPENMP_REQUIRES_CLAUSE(reverse_offload)
 OPENMP_REQUIRES_CLAUSE(dynamic_allocators)
+OPENMP_REQUIRES_CLAUSE(atomic_default_mem_order)
+
+// Modifiers for 'atomic_default_mem_order' clause.
+OPENMP_ATOMIC_DEFAULT_MEM_ORDER_KIND(seq_cst)
+OPENMP_ATOMIC_DEFAULT_MEM_ORDER_KIND(acq_rel)
+OPENMP_ATOMIC_DEFAULT_MEM_ORDER_KIND(relaxed)
 
 // Clauses allowed for OpenMP directive 'target data'.
 OPENMP_TARGET_DATA_CLAUSE(if)
@@ -898,6 +908,7 @@ OPENMP_TASKGROUP_CLAUSE(task_reduction)
 #undef OPENMP_ATOMIC_CLAUSE
 #undef OPENMP_TARGET_CLAUSE
 #undef OPENMP_REQUIRES_CLAUSE
+#undef OPENMP_ATOMIC_DEFAULT_MEM_ORDER_KIND
 #undef OPENMP_TARGET_DATA_CLAUSE
 #undef OPENMP_TARGET_ENTER_DATA_CLAUSE
 #undef OPENMP_TARGET_EXIT_DATA_CLAUSE
diff --git a/clang/include/clang/Basic/OpenMPKinds.h b/clang/include/clang/Basic/OpenMPKinds.h
index c47973e53a8..b0fab5ab118 100644
--- a/clang/include/clang/Basic/OpenMPKinds.h
+++ b/clang/include/clang/Basic/OpenMPKinds.h
@@ -120,6 +120,14 @@ enum OpenMPDefaultmapClauseModifier {
   OMPC_DEFAULTMAP_MODIFIER_last
 };
 
+/// OpenMP attributes for 'atomic_default_mem_order' clause.
+enum OpenMPAtomicDefaultMemOrderClauseKind {
+#define OPENMP_ATOMIC_DEFAULT_MEM_ORDER_KIND(Name)  \
+  OMPC_ATOMIC_DEFAULT_MEM_ORDER_##Name,
+#include "clang/Basic/OpenMPKinds.def"
+  OMPC_ATOMIC_DEFAULT_MEM_ORDER_unknown
+};
+
 /// Scheduling data for loop-based OpenMP directives.
 struct OpenMPScheduleTy final {
   OpenMPScheduleClauseKind Schedule = OMPC_SCHEDULE_unknown;
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index 7ae9872bf27..4740cca466c 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -9209,6 +9209,11 @@ public:
   OMPClause *ActOnOpenMPDynamicAllocatorsClause(SourceLocation StartLoc,
                                                 SourceLocation EndLoc);
 
+  /// Called on well-formed 'atomic_default_mem_order' clause.
+  OMPClause *ActOnOpenMPAtomicDefaultMemOrderClause(
+      OpenMPAtomicDefaultMemOrderClauseKind Kind, SourceLocation KindLoc,
+      SourceLocation StartLoc, SourceLocation LParenLoc, SourceLocation EndLoc);
+
   OMPClause *ActOnOpenMPVarListClause(
       OpenMPClauseKind Kind, ArrayRef<Expr *> Vars, Expr *TailExpr,
       SourceLocation StartLoc, SourceLocation LParenLoc,
diff --git a/clang/lib/AST/DeclPrinter.cpp b/clang/lib/AST/DeclPrinter.cpp
index 7fc275f90e9..517851f9eeb 100644
--- a/clang/lib/AST/DeclPrinter.cpp
+++ b/clang/lib/AST/DeclPrinter.cpp
@@ -1549,11 +1549,9 @@ void DeclPrinter::VisitOMPThreadPrivateDecl(OMPThreadPrivateDecl *D) {
 void DeclPrinter::VisitOMPRequiresDecl(OMPRequiresDecl *D) {
   Out << "#pragma omp requires ";
   if (!D->clauselist_empty()) {
-    for (auto I = D->clauselist_begin(), E = D->clauselist_end(); I != E; ++I) {
-      if (I != D->clauselist_begin())
-        Out << ',';
-      Out << getOpenMPClauseName((*I)->getClauseKind());
-    }
+    OMPClausePrinter Printer(Out, Policy);
+    for (auto I = D->clauselist_begin(), E = D->clauselist_end(); I != E; ++I)
+      Printer.Visit(*I);
   }
 }
 
diff --git a/clang/lib/AST/OpenMPClause.cpp b/clang/lib/AST/OpenMPClause.cpp
index a6e02f69dd4..3124b0ff6f5 100644
--- a/clang/lib/AST/OpenMPClause.cpp
+++ b/clang/lib/AST/OpenMPClause.cpp
@@ -111,6 +111,7 @@ const OMPClauseWithPreInit *OMPClauseWithPreInit::get(const OMPClause *C) {
   case OMPC_unified_shared_memory:
   case OMPC_reverse_offload:
   case OMPC_dynamic_allocators:
+  case OMPC_atomic_default_mem_order:
     break;
   }
 
@@ -184,6 +185,7 @@ const OMPClauseWithPostUpdate *OMPClauseWithPostUpdate::get(const OMPClause *C)
   case OMPC_unified_shared_memory:
   case OMPC_reverse_offload:
   case OMPC_dynamic_allocators:
+  case OMPC_atomic_default_mem_order:
     break;
   }
 
@@ -1123,6 +1125,14 @@ void OMPClausePrinter::VisitOMPDynamicAllocatorsClause(
   OS << "dynamic_allocators";
 }
 
+void OMPClausePrinter::VisitOMPAtomicDefaultMemOrderClause(
+    OMPAtomicDefaultMemOrderClause *Node) {
+  OS << "atomic_default_mem_order("
+     << getOpenMPSimpleClauseTypeName(OMPC_atomic_default_mem_order,
+                                      Node->getAtomicDefaultMemOrderKind())
+     << ")";
+}
+
 void OMPClausePrinter::VisitOMPScheduleClause(OMPScheduleClause *Node) {
   OS << "schedule(";
   if (Node->getFirstScheduleModifier() != OMPC_SCHEDULE_MODIFIER_unknown) {
diff --git a/clang/lib/AST/StmtProfile.cpp b/clang/lib/AST/StmtProfile.cpp
index 987ee43f2cd..ec4dac03d49 100644
--- a/clang/lib/AST/StmtProfile.cpp
+++ b/clang/lib/AST/StmtProfile.cpp
@@ -479,6 +479,9 @@ void OMPClauseProfiler::VisitOMPReverseOffloadClause(
 void OMPClauseProfiler::VisitOMPDynamicAllocatorsClause(
     const OMPDynamicAllocatorsClause *C) {}
 
+void OMPClauseProfiler::VisitOMPAtomicDefaultMemOrderClause(
+    const OMPAtomicDefaultMemOrderClause *C) {}
+
 void OMPClauseProfiler::VisitOMPScheduleClause(const OMPScheduleClause *C) {
   VistOMPClauseWithPreInit(C);
   if (auto *S = C->getChunkSize())
diff --git a/clang/lib/Basic/OpenMPKinds.cpp b/clang/lib/Basic/OpenMPKinds.cpp
index 7693c4288b2..dcd36c456fd 100644
--- a/clang/lib/Basic/OpenMPKinds.cpp
+++ b/clang/lib/Basic/OpenMPKinds.cpp
@@ -125,6 +125,12 @@ unsigned clang::getOpenMPSimpleClauseType(OpenMPClauseKind Kind,
   .Case(#Name, static_cast<unsigned>(OMPC_DEFAULTMAP_MODIFIER_##Name))
 #include "clang/Basic/OpenMPKinds.def"
         .Default(OMPC_DEFAULTMAP_unknown);
+  case OMPC_atomic_default_mem_order:
+     return llvm::StringSwitch<OpenMPAtomicDefaultMemOrderClauseKind>(Str)
+#define OPENMP_ATOMIC_DEFAULT_MEM_ORDER_KIND(Name)       \
+  .Case(#Name, OMPC_ATOMIC_DEFAULT_MEM_ORDER_##Name)
+#include "clang/Basic/OpenMPKinds.def"
+        .Default(OMPC_ATOMIC_DEFAULT_MEM_ORDER_unknown);
   case OMPC_unknown:
   case OMPC_threadprivate:
   case OMPC_if:
@@ -270,6 +276,16 @@ const char *clang::getOpenMPSimpleClauseTypeName(OpenMPClauseKind Kind,
 #include "clang/Basic/OpenMPKinds.def"
     }
     llvm_unreachable("Invalid OpenMP 'schedule' clause type");
+  case OMPC_atomic_default_mem_order:
+    switch (Type) {
+    case OMPC_ATOMIC_DEFAULT_MEM_ORDER_unknown:
+      return "unknown";
+#define OPENMP_ATOMIC_DEFAULT_MEM_ORDER_KIND(Name)                           \
+    case OMPC_ATOMIC_DEFAULT_MEM_ORDER_##Name:                               \
+      return #Name;
+#include "clang/Basic/OpenMPKinds.def"
+}
+    llvm_unreachable("Invalid OpenMP 'atomic_default_mem_order' clause type");
   case OMPC_unknown:
   case OMPC_threadprivate:
   case OMPC_if:
diff --git a/clang/lib/CodeGen/CGStmtOpenMP.cpp b/clang/lib/CodeGen/CGStmtOpenMP.cpp
index b3972b6220a..4ad1f3d8d27 100644
--- a/clang/lib/CodeGen/CGStmtOpenMP.cpp
+++ b/clang/lib/CodeGen/CGStmtOpenMP.cpp
@@ -3970,6 +3970,7 @@ static void emitOMPAtomicExpr(CodeGenFunction &CGF, OpenMPClauseKind Kind,
   case OMPC_unified_shared_memory:
   case OMPC_reverse_offload:
   case OMPC_dynamic_allocators:
+  case OMPC_atomic_default_mem_order:
     llvm_unreachable("Clause is not allowed in 'omp atomic'.");
   }
 }
diff --git a/clang/lib/Parse/ParseOpenMP.cpp b/clang/lib/Parse/ParseOpenMP.cpp
index 353bb800607..2df4aecca32 100644
--- a/clang/lib/Parse/ParseOpenMP.cpp
+++ b/clang/lib/Parse/ParseOpenMP.cpp
@@ -1337,11 +1337,15 @@ OMPClause *Parser::ParseOpenMPClause(OpenMPDirectiveKind DKind,
     break;
   case OMPC_default:
   case OMPC_proc_bind:
+  case OMPC_atomic_default_mem_order:
     // OpenMP [2.14.3.1, Restrictions]
     //  Only a single default clause may be specified on a parallel, task or
     //  teams directive.
     // OpenMP [2.5, parallel Construct, Restrictions]
     //  At most one proc_bind clause can appear on the directive.
+    // OpenMP [5.0, Requires directive, Restrictions]
+    //  At most one atomic_default_mem_order clause can appear
+    //  on the directive
     if (!FirstClause) {
       Diag(Tok, diag::err_omp_more_one_clause)
           << getOpenMPDirectiveName(DKind) << getOpenMPClauseName(CKind) << 0;
diff --git a/clang/lib/Sema/SemaOpenMP.cpp b/clang/lib/Sema/SemaOpenMP.cpp
index 4e966144419..59ac0348cd4 100644
--- a/clang/lib/Sema/SemaOpenMP.cpp
+++ b/clang/lib/Sema/SemaOpenMP.cpp
@@ -8175,6 +8175,7 @@ OMPClause *Sema::ActOnOpenMPSingleExprClause(OpenMPClauseKind Kind, Expr *Expr,
   case OMPC_unified_shared_memory:
   case OMPC_reverse_offload:
   case OMPC_dynamic_allocators:
+  case OMPC_atomic_default_mem_order:
     llvm_unreachable("Clause is not allowed.");
   }
   return Res;
@@ -8700,6 +8701,7 @@ static OpenMPDirectiveKind getOpenMPCaptureRegionForClause(
   case OMPC_unified_shared_memory:
   case OMPC_reverse_offload:
   case OMPC_dynamic_allocators:
+  case OMPC_atomic_default_mem_order:
     llvm_unreachable("Unexpected OpenMP clause.");
   }
   return CaptureRegion;
@@ -8968,6 +8970,11 @@ OMPClause *Sema::ActOnOpenMPSimpleClause(
         static_cast<OpenMPProcBindClauseKind>(Argument), ArgumentLoc, StartLoc,
         LParenLoc, EndLoc);
     break;
+  case OMPC_atomic_default_mem_order:
+    Res = ActOnOpenMPAtomicDefaultMemOrderClause(
+        static_cast<OpenMPAtomicDefaultMemOrderClauseKind>(Argument),
+        ArgumentLoc, StartLoc, LParenLoc, EndLoc);
+    break;
   case OMPC_if:
   case OMPC_final:
   case OMPC_num_threads:
@@ -9093,6 +9100,21 @@ OMPClause *Sema::ActOnOpenMPProcBindClause(OpenMPProcBindClauseKind Kind,
       OMPProcBindClause(Kind, KindKwLoc, StartLoc, LParenLoc, EndLoc);
 }
 
+OMPClause *Sema::ActOnOpenMPAtomicDefaultMemOrderClause(
+    OpenMPAtomicDefaultMemOrderClauseKind Kind, SourceLocation KindKwLoc,
+    SourceLocation StartLoc, SourceLocation LParenLoc, SourceLocation EndLoc) {
+  if (Kind == OMPC_ATOMIC_DEFAULT_MEM_ORDER_unknown) {
+    Diag(KindKwLoc, diag::err_omp_unexpected_clause_value)
+        << getListOfPossibleValues(
+               OMPC_atomic_default_mem_order, /*First=*/0,
+               /*Last=*/OMPC_ATOMIC_DEFAULT_MEM_ORDER_unknown)
+        << getOpenMPClauseName(OMPC_atomic_default_mem_order);
+    return nullptr;
+  }
+  return new (Context) OMPAtomicDefaultMemOrderClause(Kind, KindKwLoc, StartLoc,
+                                                      LParenLoc, EndLoc);
+}
+
 OMPClause *Sema::ActOnOpenMPSingleExprWithArgClause(
     OpenMPClauseKind Kind, ArrayRef<unsigned> Argument, Expr *Expr,
     SourceLocation StartLoc, SourceLocation LParenLoc,
@@ -9181,6 +9203,7 @@ OMPClause *Sema::ActOnOpenMPSingleExprWithArgClause(
   case OMPC_unified_shared_memory:
   case OMPC_reverse_offload:
   case OMPC_dynamic_allocators:
+  case OMPC_atomic_default_mem_order:
     llvm_unreachable("Clause is not allowed.");
   }
   return Res;
@@ -9387,6 +9410,7 @@ OMPClause *Sema::ActOnOpenMPClause(OpenMPClauseKind Kind,
   case OMPC_from:
   case OMPC_use_device_ptr:
   case OMPC_is_device_ptr:
+  case OMPC_atomic_default_mem_order:
     llvm_unreachable("Clause is not allowed.");
   }
   return Res;
@@ -9579,6 +9603,7 @@ OMPClause *Sema::ActOnOpenMPVarListClause(
   case OMPC_unified_shared_memory:
   case OMPC_reverse_offload:
   case OMPC_dynamic_allocators:
+  case OMPC_atomic_default_mem_order:
     llvm_unreachable("Clause is not allowed.");
   }
   return Res;
diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h
index 61388825692..e99d75cdcf4 100644
--- a/clang/lib/Sema/TreeTransform.h
+++ b/clang/lib/Sema/TreeTransform.h
@@ -8457,6 +8457,13 @@ OMPClause *TreeTransform<Derived>::TransformOMPDynamicAllocatorsClause(
 }
 
 template <typename Derived>
+OMPClause *TreeTransform<Derived>::TransformOMPAtomicDefaultMemOrderClause(
+    OMPAtomicDefaultMemOrderClause *C) {
+  llvm_unreachable(
+      "atomic_default_mem_order clause cannot appear in dependent context");
+}
+
+template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPPrivateClause(OMPPrivateClause *C) {
   llvm::SmallVector<Expr *, 16> Vars;
diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index 5a29b2e33b1..2d27bb418a7 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -11732,7 +11732,10 @@ OMPClause *OMPClauseReader::readClause() {
   case OMPC_dynamic_allocators:
     C = new (Context) OMPDynamicAllocatorsClause();
     break;
-  case OMPC_private:
+  case OMPC_atomic_default_mem_order:
+    C = new (Context) OMPAtomicDefaultMemOrderClause();
+    break;
+ case OMPC_private:
     C = OMPPrivateClause::CreateEmpty(Context, Record.readInt());
     break;
   case OMPC_firstprivate:
@@ -11971,6 +11974,14 @@ void
 OMPClauseReader::VisitOMPDynamicAllocatorsClause(OMPDynamicAllocatorsClause *) {
 }
 
+void OMPClauseReader::VisitOMPAtomicDefaultMemOrderClause(
+    OMPAtomicDefaultMemOrderClause *C) {
+  C->setAtomicDefaultMemOrderKind(
+      static_cast<OpenMPAtomicDefaultMemOrderClauseKind>(Record.readInt()));
+  C->setLParenLoc(Record.readSourceLocation());
+  C->setAtomicDefaultMemOrderKindKwLoc(Record.readSourceLocation());
+}
+
 void OMPClauseReader::VisitOMPPrivateClause(OMPPrivateClause *C) {
   C->setLParenLoc(Record.readSourceLocation());
   unsigned NumVars = C->varlist_size();
diff --git a/clang/lib/Serialization/ASTWriter.cpp b/clang/lib/Serialization/ASTWriter.cpp
index eb20751a959..2bde4dc3946 100644
--- a/clang/lib/Serialization/ASTWriter.cpp
+++ b/clang/lib/Serialization/ASTWriter.cpp
@@ -6944,3 +6944,10 @@ void OMPClauseWriter::VisitOMPReverseOffloadClause(OMPReverseOffloadClause *) {}
 void
 OMPClauseWriter::VisitOMPDynamicAllocatorsClause(OMPDynamicAllocatorsClause *) {
 }
+
+void OMPClauseWriter::VisitOMPAtomicDefaultMemOrderClause(
+    OMPAtomicDefaultMemOrderClause *C) {
+  Record.push_back(C->getAtomicDefaultMemOrderKind());
+  Record.AddSourceLocation(C->getLParenLoc());
+  Record.AddSourceLocation(C->getAtomicDefaultMemOrderKindKwLoc());
+}
diff --git a/clang/test/OpenMP/requires_acq_rel_print.cpp b/clang/test/OpenMP/requires_acq_rel_print.cpp
new file mode 100644
index 00000000000..f4102416f08
--- /dev/null
+++ b/clang/test/OpenMP/requires_acq_rel_print.cpp
@@ -0,0 +1,16 @@
+// RUN: %clang_cc1 -verify -fopenmp -ast-print %s | FileCheck %s
+// RUN: %clang_cc1 -fopenmp -x c++ -std=c++11 -emit-pch -o %t %s
+// RUN: %clang_cc1 -fopenmp -std=c++11 -include-pch %t -fsyntax-only -verify %s -ast-print | FileCheck %s
+
+// RUN: %clang_cc1 -verify -fopenmp-simd -ast-print %s | FileCheck %s
+// RUN: %clang_cc1 -fopenmp-simd -x c++ -std=c++11 -emit-pch -o %t %s
+// RUN: %clang_cc1 -fopenmp-simd -std=c++11 -include-pch %t -fsyntax-only -verify %s -ast-print | FileCheck %s
+// expected-no-diagnostics
+
+#ifndef HEADER
+#define HEADER
+
+#pragma omp requires atomic_default_mem_order(acq_rel)
+// CHECK:#pragma omp requires atomic_default_mem_order(acq_rel)
+
+#endif
diff --git a/clang/test/OpenMP/requires_unified_address_ast_print.cpp b/clang/test/OpenMP/requires_ast_print.cpp
index 8c51ee05cad..e884c71c866 100644
--- a/clang/test/OpenMP/requires_unified_address_ast_print.cpp
+++ b/clang/test/OpenMP/requires_ast_print.cpp
@@ -22,4 +22,7 @@
 #pragma omp requires dynamic_allocators
 // CHECK:#pragma omp requires dynamic_allocators
 
+#pragma omp requires atomic_default_mem_order(seq_cst)
+// CHECK:#pragma omp requires atomic_default_mem_order(seq_cst)
+
 #endif
diff --git a/clang/test/OpenMP/requires_unified_address_messages.cpp b/clang/test/OpenMP/requires_messages.cpp
index 8809ec415b7..7404d3ea5f3 100644
--- a/clang/test/OpenMP/requires_unified_address_messages.cpp
+++ b/clang/test/OpenMP/requires_messages.cpp
@@ -18,6 +18,23 @@
 
 #pragma omp requires dynamic_allocators, dynamic_allocators // expected-error {{Only one dynamic_allocators clause can appear on a requires directive in a single translation unit}} expected-error {{directive '#pragma omp requires' cannot contain more than one 'dynamic_allocators' clause}}
 
+#pragma omp requires atomic_default_mem_order(seq_cst) // expected-note {{atomic_default_mem_order clause previously used here}} expected-note {{atomic_default_mem_order clause previously used here}} expected-note {{atomic_default_mem_order clause previously used here}} expected-note {{atomic_default_mem_order clause previously used here}} expected-note {{atomic_default_mem_order clause previously used here}}
+
+#pragma omp requires atomic_default_mem_order(acq_rel) // expected-error {{Only one atomic_default_mem_order clause can appear on a requires directive in a single translation unit}}
+
+#pragma omp requires atomic_default_mem_order(relaxed) // expected-error {{Only one atomic_default_mem_order clause can appear on a requires directive in a single translation unit}}
+
+#pragma omp requires atomic_default_mem_order // expected-error {{expected '(' after 'atomic_default_mem_order'}} expected-error {{expected at least one clause on '#pragma omp requires' directive}}
+
+#pragma omp requires atomic_default_mem_order( // expected-error {{expected ')'}} expected-note {{to match this '('}} expected-error {{expected 'seq_cst', 'acq_rel' or 'relaxed' in OpenMP clause 'atomic_default_mem_order'}} expected-error {{expected at least one clause on '#pragma omp requires' directive}}
+
+#pragma omp requires atomic_default_mem_order(seq_cst // expected-error {{expected ')'}} expected-note {{to match this '('}} expected-error {{Only one atomic_default_mem_order clause can appear on a requires directive in a single translation unit}} 
+
+#pragma omp requires atomic_default_mem_order(invalid_modifier) // expected-error {{expected 'seq_cst', 'acq_rel' or 'relaxed' in OpenMP clause 'atomic_default_mem_order'}} expected-error {{expected at least one clause on '#pragma omp requires' directive}} 
+
+#pragma omp requires atomic_default_mem_order(shared) // expected-error {{expected 'seq_cst', 'acq_rel' or 'relaxed' in OpenMP clause 'atomic_default_mem_order'}} expected-error {{expected at least one clause on '#pragma omp requires' directive}}
+
+#pragma omp requires atomic_default_mem_order(acq_rel), atomic_default_mem_order(relaxed) // expected-error {{directive '#pragma omp requires' cannot contain more than one 'atomic_default_mem_order' claus}} expected-error {{Only one atomic_default_mem_order clause can appear on a requires directive in a single translation unit}} 
 
 #pragma omp requires // expected-error {{expected at least one clause on '#pragma omp requires' directive}}
 
@@ -29,7 +46,7 @@
 
 #pragma omp requires invalid_clause unified_address // expected-warning {{extra tokens at the end of '#pragma omp requires' are ignored}} expected-error {{expected at least one clause on '#pragma omp requires' directive}}
 
-#pragma omp requires unified_shared_memory, unified_address, reverse_offload, dynamic_allocators // expected-error {{Only one unified_shared_memory clause can appear on a requires directive in a single translation unit}} expected-error{{Only one unified_address clause can appear on a requires directive in a single translation unit}} expected-error{{Only one reverse_offload clause can appear on a requires directive in a single translation unit}} expected-error{{Only one dynamic_allocators clause can appear on a requires directive in a single translation unit}}
+#pragma omp requires unified_shared_memory, unified_address, reverse_offload, dynamic_allocators, atomic_default_mem_order(seq_cst) // expected-error {{Only one unified_shared_memory clause can appear on a requires directive in a single translation unit}} expected-error{{Only one unified_address clause can appear on a requires directive in a single translation unit}} expected-error{{Only one reverse_offload clause can appear on a requires directive in a single translation unit}} expected-error{{Only one dynamic_allocators clause can appear on a requires directive in a single translation unit}} expected-error {{Only one atomic_default_mem_order clause can appear on a requires directive in a single translation unit}}
 
 namespace A {
   #pragma omp requires unified_address // expected-error {{Only one unified_address clause can appear on a requires directive in a single translation unit}}
diff --git a/clang/test/OpenMP/requires_relaxed_print.cpp b/clang/test/OpenMP/requires_relaxed_print.cpp
new file mode 100644
index 00000000000..98786e56605
--- /dev/null
+++ b/clang/test/OpenMP/requires_relaxed_print.cpp
@@ -0,0 +1,16 @@
+// RUN: %clang_cc1 -verify -fopenmp -ast-print %s | FileCheck %s
+// RUN: %clang_cc1 -fopenmp -x c++ -std=c++11 -emit-pch -o %t %s
+// RUN: %clang_cc1 -fopenmp -std=c++11 -include-pch %t -fsyntax-only -verify %s -ast-print | FileCheck %s
+
+// RUN: %clang_cc1 -verify -fopenmp-simd -ast-print %s | FileCheck %s
+// RUN: %clang_cc1 -fopenmp-simd -x c++ -std=c++11 -emit-pch -o %t %s
+// RUN: %clang_cc1 -fopenmp-simd -std=c++11 -include-pch %t -fsyntax-only -verify %s -ast-print | FileCheck %s
+// expected-no-diagnostics
+
+#ifndef HEADER
+#define HEADER
+
+#pragma omp requires atomic_default_mem_order(relaxed)
+// CHECK:#pragma omp requires atomic_default_mem_order(relaxed)
+
+#endif
diff --git a/clang/tools/libclang/CIndex.cpp b/clang/tools/libclang/CIndex.cpp
index d104edd82d4..62502720051 100644
--- a/clang/tools/libclang/CIndex.cpp
+++ b/clang/tools/libclang/CIndex.cpp
@@ -2219,6 +2219,9 @@ void OMPClauseEnqueue::VisitOMPReverseOffloadClause(
 void OMPClauseEnqueue::VisitOMPDynamicAllocatorsClause(
     const OMPDynamicAllocatorsClause *) {}
 
+void OMPClauseEnqueue::VisitOMPAtomicDefaultMemOrderClause(
+    const OMPAtomicDefaultMemOrderClause *) {}
+
 void OMPClauseEnqueue::VisitOMPDeviceClause(const OMPDeviceClause *C) {
   Visitor->AddStmt(C->getDevice());
 }