[OpenMP] Initial parsing/sema for the 'omp loop' constructomp-loop

Adds basic parsing/sema/serialization support for the #pragma omp loop
directive.

Differential Revision: https://reviews.llvm.org/D112499

27 files changed, 588 insertions, 8 deletions

diff --git a/clang/include/clang-c/Index.h b/clang/include/clang-c/Index.h
index b49acf6b5854..b0d7ef509c26 100644
--- a/clang/include/clang-c/Index.h
+++ b/clang/include/clang-c/Index.h
@@ -2596,7 +2596,11 @@ enum CXCursorKind {
    */
   CXCursor_OMPMetaDirective = 294,
 
-  CXCursor_LastStmt = CXCursor_OMPMetaDirective,
+  /** OpenMP loop directive.
+   */
+  CXCursor_OMPGenericLoopDirective = 295,
+
+  CXCursor_LastStmt = CXCursor_OMPGenericLoopDirective,
 
   /**
    * Cursor that represents the translation unit itself.
diff --git a/clang/include/clang/AST/RecursiveASTVisitor.h b/clang/include/clang/AST/RecursiveASTVisitor.h
index f200cd3920e6..74c49546c00b 100644
--- a/clang/include/clang/AST/RecursiveASTVisitor.h
+++ b/clang/include/clang/AST/RecursiveASTVisitor.h
@@ -3023,6 +3023,9 @@ DEF_TRAVERSE_STMT(OMPDispatchDirective,
 DEF_TRAVERSE_STMT(OMPMaskedDirective,
                   { TRY_TO(TraverseOMPExecutableDirective(S)); })
 
+DEF_TRAVERSE_STMT(OMPGenericLoopDirective,
+                  { TRY_TO(TraverseOMPExecutableDirective(S)); })
+
 // OpenMP clauses.
 template <typename Derived>
 bool RecursiveASTVisitor<Derived>::TraverseOMPClause(OMPClause *C) {
diff --git a/clang/include/clang/AST/StmtOpenMP.h b/clang/include/clang/AST/StmtOpenMP.h
index 60d47b93ba79..48b2dce152a6 100644
--- a/clang/include/clang/AST/StmtOpenMP.h
+++ b/clang/include/clang/AST/StmtOpenMP.h
@@ -1144,7 +1144,7 @@ protected:
     if (isOpenMPLoopBoundSharingDirective(Kind))
       return CombinedDistributeEnd;
     if (isOpenMPWorksharingDirective(Kind) || isOpenMPTaskLoopDirective(Kind) ||
-        isOpenMPDistributeDirective(Kind))
+        isOpenMPGenericLoopDirective(Kind) || isOpenMPDistributeDirective(Kind))
       return WorksharingEnd;
     return DefaultEnd;
   }
@@ -1176,6 +1176,7 @@ protected:
   }
   void setIsLastIterVariable(Expr *IL) {
     assert((isOpenMPWorksharingDirective(getDirectiveKind()) ||
+            isOpenMPGenericLoopDirective(getDirectiveKind()) ||
             isOpenMPTaskLoopDirective(getDirectiveKind()) ||
             isOpenMPDistributeDirective(getDirectiveKind())) &&
            "expected worksharing loop directive");
@@ -1183,6 +1184,7 @@ protected:
   }
   void setLowerBoundVariable(Expr *LB) {
     assert((isOpenMPWorksharingDirective(getDirectiveKind()) ||
+            isOpenMPGenericLoopDirective(getDirectiveKind()) ||
             isOpenMPTaskLoopDirective(getDirectiveKind()) ||
             isOpenMPDistributeDirective(getDirectiveKind())) &&
            "expected worksharing loop directive");
@@ -1190,6 +1192,7 @@ protected:
   }
   void setUpperBoundVariable(Expr *UB) {
     assert((isOpenMPWorksharingDirective(getDirectiveKind()) ||
+            isOpenMPGenericLoopDirective(getDirectiveKind()) ||
             isOpenMPTaskLoopDirective(getDirectiveKind()) ||
             isOpenMPDistributeDirective(getDirectiveKind())) &&
            "expected worksharing loop directive");
@@ -1197,6 +1200,7 @@ protected:
   }
   void setStrideVariable(Expr *ST) {
     assert((isOpenMPWorksharingDirective(getDirectiveKind()) ||
+            isOpenMPGenericLoopDirective(getDirectiveKind()) ||
             isOpenMPTaskLoopDirective(getDirectiveKind()) ||
             isOpenMPDistributeDirective(getDirectiveKind())) &&
            "expected worksharing loop directive");
@@ -1204,6 +1208,7 @@ protected:
   }
   void setEnsureUpperBound(Expr *EUB) {
     assert((isOpenMPWorksharingDirective(getDirectiveKind()) ||
+            isOpenMPGenericLoopDirective(getDirectiveKind()) ||
             isOpenMPTaskLoopDirective(getDirectiveKind()) ||
             isOpenMPDistributeDirective(getDirectiveKind())) &&
            "expected worksharing loop directive");
@@ -1211,6 +1216,7 @@ protected:
   }
   void setNextLowerBound(Expr *NLB) {
     assert((isOpenMPWorksharingDirective(getDirectiveKind()) ||
+            isOpenMPGenericLoopDirective(getDirectiveKind()) ||
             isOpenMPTaskLoopDirective(getDirectiveKind()) ||
             isOpenMPDistributeDirective(getDirectiveKind())) &&
            "expected worksharing loop directive");
@@ -1218,6 +1224,7 @@ protected:
   }
   void setNextUpperBound(Expr *NUB) {
     assert((isOpenMPWorksharingDirective(getDirectiveKind()) ||
+            isOpenMPGenericLoopDirective(getDirectiveKind()) ||
             isOpenMPTaskLoopDirective(getDirectiveKind()) ||
             isOpenMPDistributeDirective(getDirectiveKind())) &&
            "expected worksharing loop directive");
@@ -1225,6 +1232,7 @@ protected:
   }
   void setNumIterations(Expr *NI) {
     assert((isOpenMPWorksharingDirective(getDirectiveKind()) ||
+            isOpenMPGenericLoopDirective(getDirectiveKind()) ||
             isOpenMPTaskLoopDirective(getDirectiveKind()) ||
             isOpenMPDistributeDirective(getDirectiveKind())) &&
            "expected worksharing loop directive");
@@ -1327,6 +1335,7 @@ public:
   Stmt *getPreInits() { return Data->getChildren()[PreInitsOffset]; }
   Expr *getIsLastIterVariable() const {
     assert((isOpenMPWorksharingDirective(getDirectiveKind()) ||
+            isOpenMPGenericLoopDirective(getDirectiveKind()) ||
             isOpenMPTaskLoopDirective(getDirectiveKind()) ||
             isOpenMPDistributeDirective(getDirectiveKind())) &&
            "expected worksharing loop directive");
@@ -1334,6 +1343,7 @@ public:
   }
   Expr *getLowerBoundVariable() const {
     assert((isOpenMPWorksharingDirective(getDirectiveKind()) ||
+            isOpenMPGenericLoopDirective(getDirectiveKind()) ||
             isOpenMPTaskLoopDirective(getDirectiveKind()) ||
             isOpenMPDistributeDirective(getDirectiveKind())) &&
            "expected worksharing loop directive");
@@ -1341,6 +1351,7 @@ public:
   }
   Expr *getUpperBoundVariable() const {
     assert((isOpenMPWorksharingDirective(getDirectiveKind()) ||
+            isOpenMPGenericLoopDirective(getDirectiveKind()) ||
             isOpenMPTaskLoopDirective(getDirectiveKind()) ||
             isOpenMPDistributeDirective(getDirectiveKind())) &&
            "expected worksharing loop directive");
@@ -1348,6 +1359,7 @@ public:
   }
   Expr *getStrideVariable() const {
     assert((isOpenMPWorksharingDirective(getDirectiveKind()) ||
+            isOpenMPGenericLoopDirective(getDirectiveKind()) ||
             isOpenMPTaskLoopDirective(getDirectiveKind()) ||
             isOpenMPDistributeDirective(getDirectiveKind())) &&
            "expected worksharing loop directive");
@@ -1355,6 +1367,7 @@ public:
   }
   Expr *getEnsureUpperBound() const {
     assert((isOpenMPWorksharingDirective(getDirectiveKind()) ||
+            isOpenMPGenericLoopDirective(getDirectiveKind()) ||
             isOpenMPTaskLoopDirective(getDirectiveKind()) ||
             isOpenMPDistributeDirective(getDirectiveKind())) &&
            "expected worksharing loop directive");
@@ -1362,6 +1375,7 @@ public:
   }
   Expr *getNextLowerBound() const {
     assert((isOpenMPWorksharingDirective(getDirectiveKind()) ||
+            isOpenMPGenericLoopDirective(getDirectiveKind()) ||
             isOpenMPTaskLoopDirective(getDirectiveKind()) ||
             isOpenMPDistributeDirective(getDirectiveKind())) &&
            "expected worksharing loop directive");
@@ -1369,6 +1383,7 @@ public:
   }
   Expr *getNextUpperBound() const {
     assert((isOpenMPWorksharingDirective(getDirectiveKind()) ||
+            isOpenMPGenericLoopDirective(getDirectiveKind()) ||
             isOpenMPTaskLoopDirective(getDirectiveKind()) ||
             isOpenMPDistributeDirective(getDirectiveKind())) &&
            "expected worksharing loop directive");
@@ -1376,6 +1391,7 @@ public:
   }
   Expr *getNumIterations() const {
     assert((isOpenMPWorksharingDirective(getDirectiveKind()) ||
+            isOpenMPGenericLoopDirective(getDirectiveKind()) ||
             isOpenMPTaskLoopDirective(getDirectiveKind()) ||
             isOpenMPDistributeDirective(getDirectiveKind())) &&
            "expected worksharing loop directive");
@@ -1509,6 +1525,7 @@ public:
            T->getStmtClass() == OMPTaskLoopSimdDirectiveClass ||
            T->getStmtClass() == OMPMasterTaskLoopDirectiveClass ||
            T->getStmtClass() == OMPMasterTaskLoopSimdDirectiveClass ||
+           T->getStmtClass() == OMPGenericLoopDirectiveClass ||
            T->getStmtClass() == OMPParallelMasterTaskLoopDirectiveClass ||
            T->getStmtClass() == OMPParallelMasterTaskLoopSimdDirectiveClass ||
            T->getStmtClass() == OMPDistributeDirectiveClass ||
@@ -5461,6 +5478,69 @@ public:
   }
 };
 
+/// This represents '#pragma omp loop' directive.
+///
+/// \code
+/// #pragma omp loop private(a,b) binding(parallel) order(concurrent)
+/// \endcode
+/// In this example directive '#pragma omp loop' has
+/// clauses 'private' with the variables 'a' and 'b', 'binding' with
+/// modifier 'parallel' and 'order(concurrent).
+///
+class OMPGenericLoopDirective final : public OMPLoopDirective {
+  friend class ASTStmtReader;
+  friend class OMPExecutableDirective;
+  /// Build directive with the given start and end location.
+  ///
+  /// \param StartLoc Starting location of the directive kind.
+  /// \param EndLoc Ending location of the directive.
+  /// \param CollapsedNum Number of collapsed nested loops.
+  ///
+  OMPGenericLoopDirective(SourceLocation StartLoc, SourceLocation EndLoc,
+                          unsigned CollapsedNum)
+      : OMPLoopDirective(OMPGenericLoopDirectiveClass, llvm::omp::OMPD_loop,
+                         StartLoc, EndLoc, CollapsedNum) {}
+
+  /// Build an empty directive.
+  ///
+  /// \param CollapsedNum Number of collapsed nested loops.
+  ///
+  explicit OMPGenericLoopDirective(unsigned CollapsedNum)
+      : OMPLoopDirective(OMPGenericLoopDirectiveClass, llvm::omp::OMPD_loop,
+                         SourceLocation(), SourceLocation(), CollapsedNum) {}
+
+public:
+  /// Creates directive with a list of \p Clauses.
+  ///
+  /// \param C AST context.
+  /// \param StartLoc Starting location of the directive kind.
+  /// \param EndLoc Ending Location of the directive.
+  /// \param CollapsedNum Number of collapsed loops.
+  /// \param Clauses List of clauses.
+  /// \param AssociatedStmt Statement, associated with the directive.
+  /// \param Exprs Helper expressions for CodeGen.
+  ///
+  static OMPGenericLoopDirective *
+  Create(const ASTContext &C, SourceLocation StartLoc, SourceLocation EndLoc,
+         unsigned CollapsedNum, ArrayRef<OMPClause *> Clauses,
+         Stmt *AssociatedStmt, const HelperExprs &Exprs);
+
+  /// Creates an empty directive with a place for \a NumClauses clauses.
+  ///
+  /// \param C AST context.
+  /// \param NumClauses Number of clauses.
+  /// \param CollapsedNum Number of collapsed nested loops.
+  ///
+  static OMPGenericLoopDirective *CreateEmpty(const ASTContext &C,
+                                              unsigned NumClauses,
+                                              unsigned CollapsedNum,
+                                              EmptyShell);
+
+  static bool classof(const Stmt *T) {
+    return T->getStmtClass() == OMPGenericLoopDirectiveClass;
+  }
+};
+
 } // end namespace clang
 
 #endif
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 7153b9c66563..7f7410a20084 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -10803,6 +10803,9 @@ def note_omp_protected_structured_block
     : Note<"jump bypasses OpenMP structured block">;
 def note_omp_exits_structured_block
     : Note<"jump exits scope of OpenMP structured block">;
+def err_omp_lastprivate_loop_var_non_loop_iteration : Error<
+  "only loop iteration variables are allowed in 'lastprivate' clause in "
+  "'omp loop' directives">;
 def err_omp_interop_variable_expected : Error<
   "expected%select{| non-const}0 variable of type 'omp_interop_t'">;
 def err_omp_interop_variable_wrong_type : Error<
diff --git a/clang/include/clang/Basic/OpenMPKinds.h b/clang/include/clang/Basic/OpenMPKinds.h
index c90bd429d87c..269f8d96f0bb 100644
--- a/clang/include/clang/Basic/OpenMPKinds.h
+++ b/clang/include/clang/Basic/OpenMPKinds.h
@@ -253,6 +253,13 @@ bool isOpenMPDistributeDirective(OpenMPDirectiveKind DKind);
 /// otherwise - false.
 bool isOpenMPNestingDistributeDirective(OpenMPDirectiveKind DKind);
 
+/// Checks if the specified directive constitutes a 'loop' directive in the
+/// outermost nest.  For example, 'omp teams loop' or 'omp loop'.
+/// \param DKind Specified directive.
+/// \return true - the directive has loop on the outermost nest.
+/// otherwise - false.
+bool isOpenMPGenericLoopDirective(OpenMPDirectiveKind DKind);
+
 /// Checks if the specified clause is one of private clauses like
 /// 'private', 'firstprivate', 'reduction' etc..
 /// \param Kind Clause kind.
diff --git a/clang/include/clang/Basic/StmtNodes.td b/clang/include/clang/Basic/StmtNodes.td
index f002c3632829..ab31c544ea9d 100644
--- a/clang/include/clang/Basic/StmtNodes.td
+++ b/clang/include/clang/Basic/StmtNodes.td
@@ -282,3 +282,4 @@ def OMPTargetTeamsDistributeSimdDirective : StmtNode<OMPLoopDirective>;
 def OMPInteropDirective : StmtNode<OMPExecutableDirective>;
 def OMPDispatchDirective : StmtNode<OMPExecutableDirective>;
 def OMPMaskedDirective : StmtNode<OMPExecutableDirective>;
+def OMPGenericLoopDirective : StmtNode<OMPLoopDirective>;
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index b87532c51f63..11e157bc7d73 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -10940,6 +10940,12 @@ public:
                                         Stmt *AStmt, SourceLocation StartLoc,
                                         SourceLocation EndLoc);
 
+  /// Called on well-formed '\#pragma omp loop' after parsing of the
+  /// associated statement.
+  StmtResult ActOnOpenMPGenericLoopDirective(
+      ArrayRef<OMPClause *> Clauses, Stmt *AStmt, SourceLocation StartLoc,
+      SourceLocation EndLoc, VarsWithInheritedDSAType &VarsWithImplicitDSA);
+
   /// Checks correctness of linear modifiers.
   bool CheckOpenMPLinearModifier(OpenMPLinearClauseKind LinKind,
                                  SourceLocation LinLoc);
diff --git a/clang/include/clang/Serialization/ASTBitCodes.h b/clang/include/clang/Serialization/ASTBitCodes.h
index 68520cd9b3e3..341da5bd1d62 100644
--- a/clang/include/clang/Serialization/ASTBitCodes.h
+++ b/clang/include/clang/Serialization/ASTBitCodes.h
@@ -1957,6 +1957,7 @@ enum StmtCode {
   STMT_OMP_INTEROP_DIRECTIVE,
   STMT_OMP_DISPATCH_DIRECTIVE,
   STMT_OMP_MASKED_DIRECTIVE,
+  STMT_OMP_GENERIC_LOOP_DIRECTIVE,
   EXPR_OMP_ARRAY_SECTION,
   EXPR_OMP_ARRAY_SHAPING,
   EXPR_OMP_ITERATOR,
diff --git a/clang/lib/AST/StmtOpenMP.cpp b/clang/lib/AST/StmtOpenMP.cpp
index 014274f46cae..aa28cd193736 100644
--- a/clang/lib/AST/StmtOpenMP.cpp
+++ b/clang/lib/AST/StmtOpenMP.cpp
@@ -2086,3 +2086,45 @@ OMPMaskedDirective *OMPMaskedDirective::CreateEmpty(const ASTContext &C,
   return createEmptyDirective<OMPMaskedDirective>(C, NumClauses,
                                                   /*HasAssociatedStmt=*/true);
 }
+
+OMPGenericLoopDirective *OMPGenericLoopDirective::Create(
+    const ASTContext &C, SourceLocation StartLoc, SourceLocation EndLoc,
+    unsigned CollapsedNum, ArrayRef<OMPClause *> Clauses, Stmt *AssociatedStmt,
+    const HelperExprs &Exprs) {
+  auto *Dir = createDirective<OMPGenericLoopDirective>(
+      C, Clauses, AssociatedStmt, numLoopChildren(CollapsedNum, OMPD_loop),
+      StartLoc, EndLoc, CollapsedNum);
+  Dir->setIterationVariable(Exprs.IterationVarRef);
+  Dir->setLastIteration(Exprs.LastIteration);
+  Dir->setCalcLastIteration(Exprs.CalcLastIteration);
+  Dir->setPreCond(Exprs.PreCond);
+  Dir->setCond(Exprs.Cond);
+  Dir->setInit(Exprs.Init);
+  Dir->setInc(Exprs.Inc);
+  Dir->setIsLastIterVariable(Exprs.IL);
+  Dir->setLowerBoundVariable(Exprs.LB);
+  Dir->setUpperBoundVariable(Exprs.UB);
+  Dir->setStrideVariable(Exprs.ST);
+  Dir->setEnsureUpperBound(Exprs.EUB);
+  Dir->setNextLowerBound(Exprs.NLB);
+  Dir->setNextUpperBound(Exprs.NUB);
+  Dir->setNumIterations(Exprs.NumIterations);
+  Dir->setCounters(Exprs.Counters);
+  Dir->setPrivateCounters(Exprs.PrivateCounters);
+  Dir->setInits(Exprs.Inits);
+  Dir->setUpdates(Exprs.Updates);
+  Dir->setFinals(Exprs.Finals);
+  Dir->setDependentCounters(Exprs.DependentCounters);
+  Dir->setDependentInits(Exprs.DependentInits);
+  Dir->setFinalsConditions(Exprs.FinalsConditions);
+  Dir->setPreInits(Exprs.PreInits);
+  return Dir;
+}
+
+OMPGenericLoopDirective *
+OMPGenericLoopDirective::CreateEmpty(const ASTContext &C, unsigned NumClauses,
+                                     unsigned CollapsedNum, EmptyShell) {
+  return createEmptyDirective<OMPGenericLoopDirective>(
+      C, NumClauses, /*HasAssociatedStmt=*/true,
+      numLoopChildren(CollapsedNum, OMPD_loop), CollapsedNum);
+}
diff --git a/clang/lib/AST/StmtPrinter.cpp b/clang/lib/AST/StmtPrinter.cpp
index ce0b3bf62eb4..12af5bfa2013 100644
--- a/clang/lib/AST/StmtPrinter.cpp
+++ b/clang/lib/AST/StmtPrinter.cpp
@@ -1000,6 +1000,11 @@ void StmtPrinter::VisitOMPMaskedDirective(OMPMaskedDirective *Node) {
   PrintOMPExecutableDirective(Node);
 }
 
+void StmtPrinter::VisitOMPGenericLoopDirective(OMPGenericLoopDirective *Node) {
+  Indent() << "#pragma omp loop";
+  PrintOMPExecutableDirective(Node);
+}
+
 //===----------------------------------------------------------------------===//
 //  Expr printing methods.
 //===----------------------------------------------------------------------===//
diff --git a/clang/lib/AST/StmtProfile.cpp b/clang/lib/AST/StmtProfile.cpp
index 2184eb7aa010..4ea4322bfd0f 100644
--- a/clang/lib/AST/StmtProfile.cpp
+++ b/clang/lib/AST/StmtProfile.cpp
@@ -1190,6 +1190,11 @@ void StmtProfiler::VisitOMPMaskedDirective(const OMPMaskedDirective *S) {
   VisitOMPExecutableDirective(S);
 }
 
+void StmtProfiler::VisitOMPGenericLoopDirective(
+    const OMPGenericLoopDirective *S) {
+  VisitOMPLoopDirective(S);
+}
+
 void StmtProfiler::VisitExpr(const Expr *S) {
   VisitStmt(S);
 }
diff --git a/clang/lib/Basic/OpenMPKinds.cpp b/clang/lib/Basic/OpenMPKinds.cpp
index d9ddb7ea0fc3..5b01bf863bb0 100644
--- a/clang/lib/Basic/OpenMPKinds.cpp
+++ b/clang/lib/Basic/OpenMPKinds.cpp
@@ -474,7 +474,7 @@ bool clang::isOpenMPLoopDirective(OpenMPDirectiveKind DKind) {
          DKind == OMPD_target_teams_distribute_parallel_for ||
          DKind == OMPD_target_teams_distribute_parallel_for_simd ||
          DKind == OMPD_target_teams_distribute_simd || DKind == OMPD_tile ||
-         DKind == OMPD_unroll;
+         DKind == OMPD_unroll || DKind == OMPD_loop;
 }
 
 bool clang::isOpenMPWorksharingDirective(OpenMPDirectiveKind DKind) {
@@ -577,6 +577,10 @@ bool clang::isOpenMPDistributeDirective(OpenMPDirectiveKind Kind) {
          Kind == OMPD_target_teams_distribute_simd;
 }
 
+bool clang::isOpenMPGenericLoopDirective(OpenMPDirectiveKind Kind) {
+  return Kind == OMPD_loop;
+}
+
 bool clang::isOpenMPPrivate(OpenMPClauseKind Kind) {
   return Kind == OMPC_private || Kind == OMPC_firstprivate ||
          Kind == OMPC_lastprivate || Kind == OMPC_linear ||
@@ -675,6 +679,10 @@ void clang::getOpenMPCaptureRegions(
     CaptureRegions.push_back(OMPD_teams);
     CaptureRegions.push_back(OMPD_parallel);
     break;
+  case OMPD_loop:
+    // TODO: 'loop' may require different capture regions depending on the bind
+    // clause or the parent directive when there is no bind clause. Use
+    // OMPD_unknown for now.
   case OMPD_simd:
   case OMPD_for:
   case OMPD_for_simd:
diff --git a/clang/lib/CodeGen/CGStmt.cpp b/clang/lib/CodeGen/CGStmt.cpp
index 2aa3bfc76d84..6768a72319b0 100644
--- a/clang/lib/CodeGen/CGStmt.cpp
+++ b/clang/lib/CodeGen/CGStmt.cpp
@@ -393,6 +393,9 @@ void CodeGenFunction::EmitStmt(const Stmt *S, ArrayRef<const Attr *> Attrs) {
   case Stmt::OMPMaskedDirectiveClass:
     EmitOMPMaskedDirective(cast<OMPMaskedDirective>(*S));
     break;
+  case Stmt::OMPGenericLoopDirectiveClass:
+    EmitOMPGenericLoopDirective(cast<OMPGenericLoopDirective>(*S));
+    break;
   }
 }
 
diff --git a/clang/lib/CodeGen/CGStmtOpenMP.cpp b/clang/lib/CodeGen/CGStmtOpenMP.cpp
index 991c9573f897..b80f663a50a5 100644
--- a/clang/lib/CodeGen/CGStmtOpenMP.cpp
+++ b/clang/lib/CodeGen/CGStmtOpenMP.cpp
@@ -7239,6 +7239,16 @@ void CodeGenFunction::EmitOMPTargetUpdateDirective(
   CGM.getOpenMPRuntime().emitTargetDataStandAloneCall(*this, S, IfCond, Device);
 }
 
+void CodeGenFunction::EmitOMPGenericLoopDirective(
+    const OMPGenericLoopDirective &S) {
+  // Unimplemented, just inline the underlying statement for now.
+  auto &&CodeGen = [&S](CodeGenFunction &CGF, PrePostActionTy &Action) {
+    CGF.EmitStmt(cast<CapturedStmt>(S.getAssociatedStmt())->getCapturedStmt());
+  };
+  OMPLexicalScope Scope(*this, S, OMPD_unknown);
+  CGM.getOpenMPRuntime().emitInlinedDirective(*this, OMPD_loop, CodeGen);
+}
+
 void CodeGenFunction::EmitSimpleOMPExecutableDirective(
     const OMPExecutableDirective &D) {
   if (const auto *SD = dyn_cast<OMPScanDirective>(&D)) {
diff --git a/clang/lib/CodeGen/CodeGenFunction.h b/clang/lib/CodeGen/CodeGenFunction.h
index b996585d5f27..dd60e21b0ce1 100644
--- a/clang/lib/CodeGen/CodeGenFunction.h
+++ b/clang/lib/CodeGen/CodeGenFunction.h
@@ -3529,6 +3529,7 @@ public:
       const OMPTargetTeamsDistributeParallelForSimdDirective &S);
   void EmitOMPTargetTeamsDistributeSimdDirective(
       const OMPTargetTeamsDistributeSimdDirective &S);
+  void EmitOMPGenericLoopDirective(const OMPGenericLoopDirective &S);
 
   /// Emit device code for the target directive.
   static void EmitOMPTargetDeviceFunction(CodeGenModule &CGM,
diff --git a/clang/lib/Parse/ParseOpenMP.cpp b/clang/lib/Parse/ParseOpenMP.cpp
index d38e088a4706..d0114b8fdae7 100644
--- a/clang/lib/Parse/ParseOpenMP.cpp
+++ b/clang/lib/Parse/ParseOpenMP.cpp
@@ -2375,6 +2375,7 @@ Parser::DeclGroupPtrTy Parser::ParseOpenMPDeclarativeDirectiveWithExtDecl(
   case OMPD_dispatch:
   case OMPD_masked:
   case OMPD_metadirective:
+  case OMPD_loop:
     Diag(Tok, diag::err_omp_unexpected_directive)
         << 1 << getOpenMPDirectiveName(DKind);
     break;
@@ -2724,6 +2725,7 @@ Parser::ParseOpenMPDeclarativeOrExecutableDirective(ParsedStmtContext StmtCtx) {
   case OMPD_target_data:
   case OMPD_target_parallel:
   case OMPD_target_parallel_for:
+  case OMPD_loop:
   case OMPD_taskloop:
   case OMPD_taskloop_simd:
   case OMPD_master_taskloop:
diff --git a/clang/lib/Sema/SemaExceptionSpec.cpp b/clang/lib/Sema/SemaExceptionSpec.cpp
index f32bb0d298ba..3af4c6f4bc41 100644
--- a/clang/lib/Sema/SemaExceptionSpec.cpp
+++ b/clang/lib/Sema/SemaExceptionSpec.cpp
@@ -1497,6 +1497,7 @@ CanThrowResult Sema::canThrow(const Stmt *S) {
   case Stmt::OMPDispatchDirectiveClass:
   case Stmt::OMPMaskedDirectiveClass:
   case Stmt::OMPMetaDirectiveClass:
+  case Stmt::OMPGenericLoopDirectiveClass:
   case Stmt::ReturnStmtClass:
   case Stmt::SEHExceptStmtClass:
   case Stmt::SEHFinallyStmtClass:
diff --git a/clang/lib/Sema/SemaOpenMP.cpp b/clang/lib/Sema/SemaOpenMP.cpp
index f5937df17d82..fa55f925d117 100644
--- a/clang/lib/Sema/SemaOpenMP.cpp
+++ b/clang/lib/Sema/SemaOpenMP.cpp
@@ -4013,6 +4013,9 @@ void Sema::ActOnOpenMPRegionStart(OpenMPDirectiveKind DKind, Scope *CurScope) {
   case OMPD_tile:
   case OMPD_unroll:
     break;
+  case OMPD_loop:
+    // TODO: 'loop' may require additional parameters depending on the binding.
+    // Treat similar to OMPD_simd/OMPD_for for now.
   case OMPD_simd:
   case OMPD_for:
   case OMPD_for_simd:
@@ -4788,6 +4791,7 @@ static bool checkNestingOfRegions(Sema &SemaRef, const DSAStackTy *Stack,
       // A masked region may not be closely nested inside a worksharing, loop,
       // atomic, task, or taskloop region.
       NestingProhibited = isOpenMPWorksharingDirective(ParentRegion) ||
+                          isOpenMPGenericLoopDirective(ParentRegion) ||
                           isOpenMPTaskingDirective(ParentRegion);
     } else if (CurrentRegion == OMPD_critical && CurrentName.getName()) {
       // OpenMP [2.16, Nesting of Regions]
@@ -4821,6 +4825,7 @@ static bool checkNestingOfRegions(Sema &SemaRef, const DSAStackTy *Stack,
       // task, taskloop, critical, ordered, atomic, or masked region.
       NestingProhibited =
           isOpenMPWorksharingDirective(ParentRegion) ||
+          isOpenMPGenericLoopDirective(ParentRegion) ||
           isOpenMPTaskingDirective(ParentRegion) ||
           ParentRegion == OMPD_master || ParentRegion == OMPD_masked ||
           ParentRegion == OMPD_parallel_master ||
@@ -4834,6 +4839,7 @@ static bool checkNestingOfRegions(Sema &SemaRef, const DSAStackTy *Stack,
       // critical, ordered, atomic, or masked region.
       NestingProhibited =
           isOpenMPWorksharingDirective(ParentRegion) ||
+          isOpenMPGenericLoopDirective(ParentRegion) ||
           isOpenMPTaskingDirective(ParentRegion) ||
           ParentRegion == OMPD_master || ParentRegion == OMPD_masked ||
           ParentRegion == OMPD_parallel_master ||
@@ -4879,12 +4885,16 @@ static bool checkNestingOfRegions(Sema &SemaRef, const DSAStackTy *Stack,
         !isOpenMPTargetExecutionDirective(CurrentRegion) &&
         !isOpenMPTargetDataManagementDirective(CurrentRegion) &&
         (ParentRegion == OMPD_teams || ParentRegion == OMPD_target_teams)) {
-      // OpenMP [2.16, Nesting of Regions]
-      // distribute, parallel, parallel sections, parallel workshare, and the
-      // parallel loop and parallel loop SIMD constructs are the only OpenMP
-      // constructs that can be closely nested in the teams region.
+      // OpenMP [5.1, 2.22, Nesting of Regions]
+      // distribute, distribute simd, distribute parallel worksharing-loop,
+      // distribute parallel worksharing-loop SIMD, loop, parallel regions,
+      // including any parallel regions arising from combined constructs,
+      // omp_get_num_teams() regions, and omp_get_team_num() regions are the
+      // only OpenMP regions that may be strictly nested inside the teams
+      // region.
       NestingProhibited = !isOpenMPParallelDirective(CurrentRegion) &&
-                          !isOpenMPDistributeDirective(CurrentRegion);
+                          !isOpenMPDistributeDirective(CurrentRegion) &&
+                          CurrentRegion != OMPD_loop;
       Recommend = ShouldBeInParallelRegion;
     }
     if (!NestingProhibited &&
@@ -6231,6 +6241,10 @@ StmtResult Sema::ActOnOpenMPExecutableDirective(
     Res = ActOnOpenMPDispatchDirective(ClausesWithImplicit, AStmt, StartLoc,
                                        EndLoc);
     break;
+  case OMPD_loop:
+    Res = ActOnOpenMPGenericLoopDirective(ClausesWithImplicit, AStmt, StartLoc,
+                                          EndLoc, VarsWithInheritedDSA);
+    break;
   case OMPD_declare_target:
   case OMPD_end_declare_target:
   case OMPD_threadprivate:
@@ -8817,6 +8831,7 @@ static bool checkOpenMPIterationSpace(
   ResultIterSpaces[CurrentNestedLoopCount].NumIterations =
       ISC.buildNumIterations(DSA.getCurScope(), ResultIterSpaces,
                              (isOpenMPWorksharingDirective(DKind) ||
+                              isOpenMPGenericLoopDirective(DKind) ||
                               isOpenMPTaskLoopDirective(DKind) ||
                               isOpenMPDistributeDirective(DKind) ||
                               isOpenMPLoopTransformationDirective(DKind)),
@@ -9300,6 +9315,7 @@ checkOpenMPLoop(OpenMPDirectiveKind DKind, Expr *CollapseLoopCountExpr,
   ExprResult LB, UB, IL, ST, EUB, CombLB, CombUB, PrevLB, PrevUB, CombEUB;
   if (isOpenMPWorksharingDirective(DKind) || isOpenMPTaskLoopDirective(DKind) ||
       isOpenMPDistributeDirective(DKind) ||
+      isOpenMPGenericLoopDirective(DKind) ||
       isOpenMPLoopTransformationDirective(DKind)) {
     // Lower bound variable, initialized with zero.
     VarDecl *LBDecl = buildVarDecl(SemaRef, InitLoc, VType, ".omp.lb");
@@ -9399,6 +9415,7 @@ checkOpenMPLoop(OpenMPDirectiveKind DKind, Expr *CollapseLoopCountExpr,
     VarDecl *IVDecl = buildVarDecl(SemaRef, InitLoc, RealVType, ".omp.iv");
     IV = buildDeclRefExpr(SemaRef, IVDecl, RealVType, InitLoc);
     Expr *RHS = (isOpenMPWorksharingDirective(DKind) ||
+                 isOpenMPGenericLoopDirective(DKind) ||
                  isOpenMPTaskLoopDirective(DKind) ||
                  isOpenMPDistributeDirective(DKind) ||
                  isOpenMPLoopTransformationDirective(DKind))
@@ -9410,6 +9427,7 @@ checkOpenMPLoop(OpenMPDirectiveKind DKind, Expr *CollapseLoopCountExpr,
     if (isOpenMPLoopBoundSharingDirective(DKind)) {
       Expr *CombRHS =
           (isOpenMPWorksharingDirective(DKind) ||
+           isOpenMPGenericLoopDirective(DKind) ||
            isOpenMPTaskLoopDirective(DKind) ||
            isOpenMPDistributeDirective(DKind))
               ? CombLB.get()
@@ -9441,6 +9459,7 @@ checkOpenMPLoop(OpenMPDirectiveKind DKind, Expr *CollapseLoopCountExpr,
   }
   ExprResult Cond =
       (isOpenMPWorksharingDirective(DKind) ||
+       isOpenMPGenericLoopDirective(DKind) ||
        isOpenMPTaskLoopDirective(DKind) || isOpenMPDistributeDirective(DKind) ||
        isOpenMPLoopTransformationDirective(DKind))
           ? SemaRef.BuildBinOp(CurScope, CondLoc,
@@ -9490,6 +9509,7 @@ checkOpenMPLoop(OpenMPDirectiveKind DKind, Expr *CollapseLoopCountExpr,
   // base variables for the update
   ExprResult NextLB, NextUB, CombNextLB, CombNextUB;
   if (isOpenMPWorksharingDirective(DKind) || isOpenMPTaskLoopDirective(DKind) ||
+      isOpenMPGenericLoopDirective(DKind) ||
       isOpenMPDistributeDirective(DKind) ||
       isOpenMPLoopTransformationDirective(DKind)) {
     // LB + ST
@@ -10044,6 +10064,57 @@ StmtResult Sema::ActOnOpenMPDispatchDirective(ArrayRef<OMPClause *> Clauses,
                                       TargetCallLoc);
 }
 
+StmtResult Sema::ActOnOpenMPGenericLoopDirective(
+    ArrayRef<OMPClause *> Clauses, Stmt *AStmt, SourceLocation StartLoc,
+    SourceLocation EndLoc, VarsWithInheritedDSAType &VarsWithImplicitDSA) {
+  if (!AStmt)
+    return StmtError();
+
+  // OpenMP 5.1 [2.11.7, loop construct]
+  // A list item may not appear in a lastprivate clause unless it is the
+  // loop iteration variable of a loop that is associated with the construct.
+  for (OMPClause *C : Clauses) {
+    if (auto *LPC = dyn_cast<OMPLastprivateClause>(C)) {
+      for (Expr *RefExpr : LPC->varlists()) {
+        SourceLocation ELoc;
+        SourceRange ERange;
+        Expr *SimpleRefExpr = RefExpr;
+        auto Res = getPrivateItem(*this, SimpleRefExpr, ELoc, ERange);
+        if (ValueDecl *D = Res.first) {
+          auto &&Info = DSAStack->isLoopControlVariable(D);
+          if (!Info.first) {
+            Diag(ELoc, diag::err_omp_lastprivate_loop_var_non_loop_iteration);
+            return StmtError();
+          }
+        }
+      }
+    }
+  }
+
+  auto *CS = cast<CapturedStmt>(AStmt);
+  // 1.2.2 OpenMP Language Terminology
+  // Structured block - An executable statement with a single entry at the
+  // top and a single exit at the bottom.
+  // The point of exit cannot be a branch out of the structured block.
+  // longjmp() and throw() must not violate the entry/exit criteria.
+  CS->getCapturedDecl()->setNothrow();
+
+  OMPLoopDirective::HelperExprs B;
+  // In presence of clause 'collapse', it will define the nested loops number.
+  unsigned NestedLoopCount = checkOpenMPLoop(
+      OMPD_loop, getCollapseNumberExpr(Clauses), getOrderedNumberExpr(Clauses),
+      AStmt, *this, *DSAStack, VarsWithImplicitDSA, B);
+  if (NestedLoopCount == 0)
+    return StmtError();
+
+  assert((CurContext->isDependentContext() || B.builtAll()) &&
+         "omp loop exprs were not built");
+
+  setFunctionHasBranchProtectedScope();
+  return OMPGenericLoopDirective::Create(Context, StartLoc, EndLoc,
+                                         NestedLoopCount, Clauses, AStmt, B);
+}
+
 StmtResult Sema::ActOnOpenMPSingleDirective(ArrayRef<OMPClause *> Clauses,
                                             Stmt *AStmt,
                                             SourceLocation StartLoc,
@@ -13529,6 +13600,7 @@ static OpenMPDirectiveKind getOpenMPCaptureRegionForClause(
     case OMPD_end_declare_variant:
     case OMPD_declare_target:
     case OMPD_end_declare_target:
+    case OMPD_loop:
     case OMPD_teams:
     case OMPD_tile:
     case OMPD_unroll:
@@ -13608,6 +13680,7 @@ static OpenMPDirectiveKind getOpenMPCaptureRegionForClause(
     case OMPD_end_declare_variant:
     case OMPD_declare_target:
     case OMPD_end_declare_target:
+    case OMPD_loop:
     case OMPD_teams:
     case OMPD_simd:
     case OMPD_tile:
@@ -13692,6 +13765,7 @@ static OpenMPDirectiveKind getOpenMPCaptureRegionForClause(
     case OMPD_end_declare_variant:
     case OMPD_declare_target:
     case OMPD_end_declare_target:
+    case OMPD_loop:
     case OMPD_simd:
     case OMPD_tile:
     case OMPD_unroll:
@@ -13773,6 +13847,7 @@ static OpenMPDirectiveKind getOpenMPCaptureRegionForClause(
     case OMPD_end_declare_variant:
     case OMPD_declare_target:
     case OMPD_end_declare_target:
+    case OMPD_loop:
     case OMPD_simd:
     case OMPD_tile:
     case OMPD_unroll:
@@ -13855,6 +13930,7 @@ static OpenMPDirectiveKind getOpenMPCaptureRegionForClause(
     case OMPD_end_declare_variant:
     case OMPD_declare_target:
     case OMPD_end_declare_target:
+    case OMPD_loop:
     case OMPD_simd:
     case OMPD_tile:
     case OMPD_unroll:
@@ -13936,6 +14012,7 @@ static OpenMPDirectiveKind getOpenMPCaptureRegionForClause(
     case OMPD_end_declare_variant:
     case OMPD_declare_target:
     case OMPD_end_declare_target:
+    case OMPD_loop:
     case OMPD_simd:
     case OMPD_tile:
     case OMPD_unroll:
@@ -14018,6 +14095,7 @@ static OpenMPDirectiveKind getOpenMPCaptureRegionForClause(
     case OMPD_end_declare_variant:
     case OMPD_declare_target:
     case OMPD_end_declare_target:
+    case OMPD_loop:
     case OMPD_simd:
     case OMPD_tile:
     case OMPD_unroll:
@@ -14101,6 +14179,7 @@ static OpenMPDirectiveKind getOpenMPCaptureRegionForClause(
     case OMPD_end_declare_variant:
     case OMPD_declare_target:
     case OMPD_end_declare_target:
+    case OMPD_loop:
     case OMPD_simd:
     case OMPD_tile:
     case OMPD_unroll:
diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h
index 3f6c84acaff1..cfc6e608bc59 100644
--- a/clang/lib/Sema/TreeTransform.h
+++ b/clang/lib/Sema/TreeTransform.h
@@ -9172,6 +9172,17 @@ TreeTransform<Derived>::TransformOMPMaskedDirective(OMPMaskedDirective *D) {
   return Res;
 }
 
+template <typename Derived>
+StmtResult TreeTransform<Derived>::TransformOMPGenericLoopDirective(
+    OMPGenericLoopDirective *D) {
+  DeclarationNameInfo DirName;
+  getDerived().getSema().StartOpenMPDSABlock(OMPD_loop, DirName, nullptr,
+                                             D->getBeginLoc());
+  StmtResult Res = getDerived().TransformOMPExecutableDirective(D);
+  getDerived().getSema().EndOpenMPDSABlock(Res.get());
+  return Res;
+}
+
 //===----------------------------------------------------------------------===//
 // OpenMP clause transformation
 //===----------------------------------------------------------------------===//
diff --git a/clang/lib/Serialization/ASTReaderStmt.cpp b/clang/lib/Serialization/ASTReaderStmt.cpp
index 4e6eaf77ff56..02910b763800 100644
--- a/clang/lib/Serialization/ASTReaderStmt.cpp
+++ b/clang/lib/Serialization/ASTReaderStmt.cpp
@@ -2632,6 +2632,10 @@ void ASTStmtReader::VisitOMPMaskedDirective(OMPMaskedDirective *D) {
   VisitOMPExecutableDirective(D);
 }
 
+void ASTStmtReader::VisitOMPGenericLoopDirective(OMPGenericLoopDirective *D) {
+  VisitOMPLoopDirective(D);
+}
+
 //===----------------------------------------------------------------------===//
 // ASTReader Implementation
 //===----------------------------------------------------------------------===//
@@ -3578,6 +3582,14 @@ Stmt *ASTReader::ReadStmtFromStream(ModuleFile &F) {
           Context, Record[ASTStmtReader::NumStmtFields], Empty);
       break;
 
+    case STMT_OMP_GENERIC_LOOP_DIRECTIVE: {
+      unsigned CollapsedNum = Record[ASTStmtReader::NumStmtFields];
+      unsigned NumClauses = Record[ASTStmtReader::NumStmtFields + 1];
+      S = OMPGenericLoopDirective::CreateEmpty(Context, NumClauses,
+                                               CollapsedNum, Empty);
+      break;
+    }
+
     case EXPR_CXX_OPERATOR_CALL:
       S = CXXOperatorCallExpr::CreateEmpty(
           Context, /*NumArgs=*/Record[ASTStmtReader::NumExprFields],
diff --git a/clang/lib/Serialization/ASTWriterStmt.cpp b/clang/lib/Serialization/ASTWriterStmt.cpp
index 0e87bcce0e43..9fdd86765c5a 100644
--- a/clang/lib/Serialization/ASTWriterStmt.cpp
+++ b/clang/lib/Serialization/ASTWriterStmt.cpp
@@ -2589,6 +2589,11 @@ void ASTStmtWriter::VisitOMPMaskedDirective(OMPMaskedDirective *D) {
   Code = serialization::STMT_OMP_MASKED_DIRECTIVE;
 }
 
+void ASTStmtWriter::VisitOMPGenericLoopDirective(OMPGenericLoopDirective *D) {
+  VisitOMPLoopDirective(D);
+  Code = serialization::STMT_OMP_GENERIC_LOOP_DIRECTIVE;
+}
+
 //===----------------------------------------------------------------------===//
 // ASTWriter Implementation
 //===----------------------------------------------------------------------===//
diff --git a/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp b/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp
index 2229dbf83500..df27069baadd 100644
--- a/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp
+++ b/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp
@@ -1297,6 +1297,7 @@ void ExprEngine::Visit(const Stmt *S, ExplodedNode *Pred,
     case Stmt::OMPInteropDirectiveClass:
     case Stmt::OMPDispatchDirectiveClass:
     case Stmt::OMPMaskedDirectiveClass:
+    case Stmt::OMPGenericLoopDirectiveClass:
     case Stmt::CapturedStmtClass:
     case Stmt::OMPUnrollDirectiveClass:
     case Stmt::OMPMetaDirectiveClass: {
diff --git a/clang/test/OpenMP/generic_loop_ast_print.cpp b/clang/test/OpenMP/generic_loop_ast_print.cpp
new file mode 100644
index 000000000000..7f5f53003e40
--- /dev/null
+++ b/clang/test/OpenMP/generic_loop_ast_print.cpp
@@ -0,0 +1,141 @@
+// RUN: %clang_cc1 -triple x86_64-pc-linux-gnu -fopenmp -fopenmp-version=51 \
+// RUN:   -fsyntax-only -verify %s
+
+// expected-no-diagnostics
+
+// RUN: %clang_cc1 -triple x86_64-pc-linux-gnu -fopenmp -fopenmp-version=51 \
+// RUN:   -ast-print %s | FileCheck %s --check-prefix=PRINT
+
+// RUN: %clang_cc1 -triple x86_64-pc-linux-gnu -fopenmp -fopenmp-version=51 \
+// RUN:   -ast-dump  %s | FileCheck %s --check-prefix=DUMP
+
+// RUN: %clang_cc1 -triple x86_64-pc-linux-gnu -fopenmp -fopenmp-version=51 \
+// RUN:   -emit-pch -o %t %s
+
+// RUN: %clang_cc1 -triple x86_64-pc-linux-gnu -fopenmp -fopenmp-version=51 \
+// RUN:   -include-pch %t -ast-dump-all %s | FileCheck %s --check-prefix=DUMP
+
+// RUN: %clang_cc1 -triple x86_64-pc-linux-gnu -fopenmp -fopenmp-version=51 \
+// RUN:   -include-pch %t -ast-print %s | FileCheck %s --check-prefix=PRINT
+
+#ifndef HEADER
+#define HEADER
+
+//PRINT: template <typename T, int C> void templ_foo(T t) {
+//PRINT:   T j, z;
+//PRINT:   #pragma omp loop collapse(C) reduction(+: z) lastprivate(j)
+//PRINT:   for (T i = 0; i < t; ++i)
+//PRINT:       for (j = 0; j < t; ++j)
+//PRINT:           z += i + j;
+//PRINT: }
+//DUMP: FunctionTemplateDecl{{.*}}templ_foo
+//DUMP: TemplateTypeParmDecl{{.*}}T
+//DUMP: NonTypeTemplateParmDecl{{.*}}C
+//DUMP: OMPGenericLoopDirective
+//DUMP: OMPCollapseClause
+//DUMP: DeclRefExpr{{.*}}'C' 'int'
+//DUMP: OMPReductionClause
+//DUMP: DeclRefExpr{{.*}}'z' 'T'
+//DUMP: OMPLastprivateClause
+//DUMP: DeclRefExpr{{.*}}'j' 'T'
+//DUMP: ForStmt
+//DUMP: ForStmt
+
+//PRINT: template<> void templ_foo<int, 2>(int t) {
+//PRINT:     int j, z;
+//PRINT:     #pragma omp loop collapse(2) reduction(+: z) lastprivate(j)
+//PRINT:         for (int i = 0; i < t; ++i)
+//PRINT:             for (j = 0; j < t; ++j)
+//PRINT:                 z += i + j;
+//PRINT: }
+//DUMP: FunctionDecl{{.*}}templ_foo 'void (int)'
+//DUMP: TemplateArgument type 'int'
+//DUMP: TemplateArgument integral 2
+//DUMP: ParmVarDecl{{.*}}'int':'int'
+//DUMP: OMPGenericLoopDirective
+//DUMP: OMPCollapseClause
+//DUMP: ConstantExpr{{.*}}'int'
+//DUMP: value: Int 2
+//DUMP: OMPReductionClause
+//DUMP: DeclRefExpr{{.*}}'z' 'int':'int'
+//DUMP: OMPLastprivateClause
+//DUMP: DeclRefExpr{{.*}}'j' 'int':'int'
+//DUMP: ForStmt
+template <typename T, int C>
+void templ_foo(T t) {
+
+  T j,z;
+  #pragma omp loop collapse(C) reduction(+:z) lastprivate(j)
+  for (T i = 0; i<t; ++i)
+    for (j = 0; j<t; ++j)
+      z += i+j;
+}
+
+
+//PRINT: void test() {
+//DUMP: FunctionDecl {{.*}}test 'void ()'
+void test() {
+  constexpr int N = 100;
+  float MTX[N][N];
+  int aaa[1000];
+
+  //PRINT: #pragma omp target teams distribute parallel for map(tofrom: MTX)
+  //PRINT: #pragma omp loop
+  //DUMP: OMPTargetTeamsDistributeParallelForDirective
+  //DUMP: CapturedStmt
+  //DUMP: ForStmt
+  //DUMP: CompoundStmt
+  //DUMP: OMPGenericLoopDirective
+  #pragma omp target teams distribute parallel for map(MTX)
+  for (auto i = 0; i < N; ++i) {
+    #pragma omp loop
+    for (auto j = 0; j < N; ++j) {
+      MTX[i][j] = 0;
+    }
+  }
+
+  //PRINT: #pragma omp target teams
+  //PRINT: #pragma omp loop
+  //DUMP: OMPTargetTeamsDirective
+  //DUMP: CapturedStmt
+  //DUMP: ForStmt
+  //DUMP: OMPGenericLoopDirective
+  #pragma omp target teams
+  for (int i=0; i<1000; ++i) {
+    #pragma omp loop
+    for (int j=0; j<100; j++) {
+      aaa[i] += i + j;
+    }
+  }
+
+  int j, z, z1;
+  //PRINT: #pragma omp loop collapse(2) private(z) lastprivate(j) order(concurrent) reduction(+: z1)
+  //DUMP: OMPGenericLoopDirective
+  //DUMP: OMPCollapseClause
+  //DUMP: IntegerLiteral{{.*}}2
+  //DUMP: OMPPrivateClause
+  //DUMP-NEXT: DeclRefExpr{{.*}}'z'
+  //DUMP: OMPLastprivateClause
+  //DUMP-NEXT: DeclRefExpr{{.*}}'j'
+  //DUMP: OMPOrderClause
+  //DUMP: OMPReductionClause
+  //DUMP-NEXT: DeclRefExpr{{.*}}'z1'
+  //DUMP: ForStmt
+  //DUMP: ForStmt
+  #pragma omp loop collapse(2) private(z) lastprivate(j) order(concurrent) \
+                   reduction(+:z1)
+  for (auto i = 0; i < N; ++i) {
+    for (j = 0; j < N; ++j) {
+      z = i+j;
+      MTX[i][j] = z;
+      z1 += z;
+    }
+  }
+}
+
+void bar()
+{
+  templ_foo<int,2>(8);
+}
+
+#endif // HEADER
diff --git a/clang/test/OpenMP/generic_loop_messages.cpp b/clang/test/OpenMP/generic_loop_messages.cpp
new file mode 100644
index 000000000000..01838a921330
--- /dev/null
+++ b/clang/test/OpenMP/generic_loop_messages.cpp
@@ -0,0 +1,133 @@
+// RUN: %clang_cc1 -verify -fopenmp -fopenmp-version=51 -Wuninitialized %s
+
+void foo()
+{
+  int i,j,k;
+  int z;
+
+  // expected-error@+2 {{statement after '#pragma omp loop' must be a for loop}}
+  #pragma omp loop
+  i = 0;
+
+  // OpenMP 5.1 [2.22 Nesting of regions]
+  //
+  // A barrier region may not be closely nested inside a worksharing, loop,
+  // task, taskloop, critical, ordered, atomic, or masked region.
+
+  // expected-error@+3 {{region cannot be closely nested inside 'loop' region}}
+  #pragma omp loop
+  for (i=0; i<1000; ++i) {
+    #pragma omp barrier
+  }
+
+  // A masked region may not be closely nested inside a worksharing, loop,
+  // atomic, task, or taskloop region.
+
+  // expected-error@+3 {{region cannot be closely nested inside 'loop' region}}
+  #pragma omp loop
+  for (i=0; i<1000; ++i) {
+    #pragma omp masked filter(2)
+    { }
+  }
+
+  // An ordered region that corresponds to an ordered construct without any
+  // clause or with the threads or depend clause may not be closely nested
+  // inside a critical, ordered, loop, atomic, task, or taskloop region.
+
+  // expected-error@+3 {{region cannot be closely nested inside 'loop' region; perhaps you forget to enclose 'omp ordered' directive into a for or a parallel for region with 'ordered' clause?}}
+  #pragma omp loop
+  for (i=0; i<1000; ++i) {
+    #pragma omp ordered
+    { }
+  }
+
+  // expected-error@+3 {{region cannot be closely nested inside 'loop' region; perhaps you forget to enclose 'omp ordered' directive into a for or a parallel for region with 'ordered' clause?}}
+  #pragma omp loop
+  for (i=0; i<1000; ++i) {
+    #pragma omp ordered threads
+    { }
+  }
+
+  // expected-error@+3 {{region cannot be closely nested inside 'loop' region; perhaps you forget to enclose 'omp ordered' directive into a for or a parallel for region with 'ordered' clause?}}
+  #pragma omp loop
+  for (i=0; i<1000; ++i) {
+    #pragma omp ordered depend(source)
+  }
+
+  // bind clause (not yet implemented)
+
+  // collapse clause
+
+  // expected-error@+4 {{expected 2 for loops after '#pragma omp loop', but found only 1}}
+  // expected-note@+1 {{as specified in 'collapse' clause}}
+  #pragma omp loop collapse(2)
+  for (i=0; i<1000; ++i)
+    z = i+11;
+
+  // expected-error@+1 {{directive '#pragma omp loop' cannot contain more than one 'collapse' clause}}
+  #pragma omp loop collapse(2) collapse(2)
+  for (i=0; i<1000; ++i)
+    for (j=0; j<1000; ++j)
+      z = i+j+11;
+
+  // order clause
+
+  // expected-error@+1 {{expected 'concurrent' in OpenMP clause 'order'}}
+  #pragma omp loop order(foo)
+  for (i=0; i<1000; ++i)
+    z = i+11;
+
+  // private clause
+
+  // expected-error@+1 {{use of undeclared identifier 'undef_var'}}
+  #pragma omp loop private(undef_var)
+  for (i=0; i<1000; ++i)
+    z = i+11;
+
+  // lastprivate
+
+  // A list item may not appear in a lastprivate clause unless it is the loop
+  // iteration variable of a loop that is associated with the construct.
+
+  // expected-error@+1 {{only loop iteration variables are allowed in 'lastprivate' clause in 'omp loop' directives}}
+  #pragma omp loop lastprivate(z)
+  for (i=0; i<1000; ++i) {
+    z = i+11;
+  }
+
+  // expected-error@+1 {{only loop iteration variables are allowed in 'lastprivate' clause in 'omp loop' directives}}
+  #pragma omp loop lastprivate(k) collapse(2)
+  for (i=0; i<1000; ++i)
+    for (j=0; j<1000; ++j)
+      for (k=0; k<1000; ++k)
+        z = i+j+k+11;
+
+  // reduction
+
+  // expected-error@+1 {{use of undeclared identifier 'undef_var'}}
+  #pragma omp loop reduction(+:undef_var)
+  for (i=0; i<1000; ++i)
+    z = i+11;
+}
+
+template <typename T, int C>
+void templ_test(T t) {
+  T i,z;
+
+  // expected-error@+4 {{expected 2 for loops after '#pragma omp loop', but found only 1}}
+  // expected-note@+1 {{as specified in 'collapse' clause}}
+  #pragma omp loop collapse(C)
+  for (i=0; i<1000; ++i)
+    z = i+11;
+
+  // expected-error@+1 {{only loop iteration variables are allowed in 'lastprivate' clause in 'omp loop' directives}}
+  #pragma omp loop lastprivate(z)
+  for (i=0; i<1000; ++i) {
+    z = i+11;
+  }
+}
+
+void bar()
+{
+  templ_test<int, 2>(16); // expected-note {{in instantiation of function template specialization 'templ_test<int, 2>' requested here}}
+}
diff --git a/clang/tools/libclang/CIndex.cpp b/clang/tools/libclang/CIndex.cpp
index 02f986a6df1c..fb5c3fa9390a 100644
--- a/clang/tools/libclang/CIndex.cpp
+++ b/clang/tools/libclang/CIndex.cpp
@@ -5710,6 +5710,8 @@ CXString clang_getCursorKindSpelling(enum CXCursorKind Kind) {
     return cxstring::createRef("OMPDispatchDirective");
   case CXCursor_OMPMaskedDirective:
     return cxstring::createRef("OMPMaskedDirective");
+  case CXCursor_OMPGenericLoopDirective:
+    return cxstring::createRef("OMPGenericLoopDirective");
   case CXCursor_OverloadCandidate:
     return cxstring::createRef("OverloadCandidate");
   case CXCursor_TypeAliasTemplateDecl:
diff --git a/clang/tools/libclang/CXCursor.cpp b/clang/tools/libclang/CXCursor.cpp
index 8d214480e9b8..590797474b00 100644
--- a/clang/tools/libclang/CXCursor.cpp
+++ b/clang/tools/libclang/CXCursor.cpp
@@ -823,6 +823,9 @@ CXCursor cxcursor::MakeCXCursor(const Stmt *S, const Decl *Parent,
   case Stmt::OMPMaskedDirectiveClass:
     K = CXCursor_OMPMaskedDirective;
     break;
+  case Stmt::OMPGenericLoopDirectiveClass:
+    K = CXCursor_OMPGenericLoopDirective;
+    break;
   case Stmt::BuiltinBitCastExprClass:
     K = CXCursor_BuiltinBitCastExpr;
   }
diff --git a/llvm/include/llvm/Frontend/OpenMP/OMP.td b/llvm/include/llvm/Frontend/OpenMP/OMP.td
index 5fd30412721b..7ef0614c9f99 100644
--- a/llvm/include/llvm/Frontend/OpenMP/OMP.td
+++ b/llvm/include/llvm/Frontend/OpenMP/OMP.td
@@ -1732,6 +1732,17 @@ def OMP_masked : Directive<"masked"> {
     VersionedClause<OMPC_Filter>
   ];
 }
+def OMP_loop : Directive<"loop"> {
+  let allowedClauses = [
+    VersionedClause<OMPC_LastPrivate>,
+    VersionedClause<OMPC_Private>,
+    VersionedClause<OMPC_Reduction>,
+  ];
+  let allowedOnceClauses = [
+    VersionedClause<OMPC_Collapse>,
+    VersionedClause<OMPC_Order>,
+  ];
+}
 def OMP_Metadirective : Directive<"metadirective"> {
   let allowedClauses = [VersionedClause<OMPC_When>];
   let allowedOnceClauses = [VersionedClause<OMPC_Default>];