[clang] 13a1504 - [OPENMP50]Add initial support for OpenMP 5.0 iterator.

Alexey Bataev via cfe-commits cfe-commits at lists.llvm.org
Thu Apr 2 05:36:47 PDT 2020


Author: Alexey Bataev
Date: 2020-04-02T08:28:15-04:00
New Revision: 13a1504ffb9a9a4f82dc1b60d9e8cbb173c7d030

URL: https://github.com/llvm/llvm-project/commit/13a1504ffb9a9a4f82dc1b60d9e8cbb173c7d030
DIFF: https://github.com/llvm/llvm-project/commit/13a1504ffb9a9a4f82dc1b60d9e8cbb173c7d030.diff

LOG: [OPENMP50]Add initial support for OpenMP 5.0 iterator.

Added basic parsing/semantic analysis/(de)serialization support for
iterator expression introduced in OpenMP 5.0.

Added: 
    

Modified: 
    clang/include/clang-c/Index.h
    clang/include/clang/AST/ASTContext.h
    clang/include/clang/AST/BuiltinTypes.def
    clang/include/clang/AST/ComputeDependence.h
    clang/include/clang/AST/ExprOpenMP.h
    clang/include/clang/AST/OpenMPClause.h
    clang/include/clang/AST/RecursiveASTVisitor.h
    clang/include/clang/AST/TextNodeDumper.h
    clang/include/clang/Basic/DiagnosticParseKinds.td
    clang/include/clang/Basic/DiagnosticSemaKinds.td
    clang/include/clang/Basic/StmtNodes.td
    clang/include/clang/Parse/Parser.h
    clang/include/clang/Sema/Sema.h
    clang/include/clang/Serialization/ASTBitCodes.h
    clang/lib/AST/ASTContext.cpp
    clang/lib/AST/ComputeDependence.cpp
    clang/lib/AST/Expr.cpp
    clang/lib/AST/ExprClassification.cpp
    clang/lib/AST/ExprConstant.cpp
    clang/lib/AST/ItaniumMangle.cpp
    clang/lib/AST/NSAPI.cpp
    clang/lib/AST/OpenMPClause.cpp
    clang/lib/AST/StmtPrinter.cpp
    clang/lib/AST/StmtProfile.cpp
    clang/lib/AST/TextNodeDumper.cpp
    clang/lib/AST/Type.cpp
    clang/lib/AST/TypeLoc.cpp
    clang/lib/Parse/ParseOpenMP.cpp
    clang/lib/Sema/SemaExceptionSpec.cpp
    clang/lib/Sema/SemaExpr.cpp
    clang/lib/Sema/SemaOpenMP.cpp
    clang/lib/Sema/TreeTransform.h
    clang/lib/Serialization/ASTCommon.cpp
    clang/lib/Serialization/ASTReader.cpp
    clang/lib/Serialization/ASTReaderStmt.cpp
    clang/lib/Serialization/ASTWriter.cpp
    clang/lib/Serialization/ASTWriterStmt.cpp
    clang/lib/StaticAnalyzer/Checkers/IdenticalExprChecker.cpp
    clang/lib/StaticAnalyzer/Core/ExprEngine.cpp
    clang/test/OpenMP/depobj_messages.cpp
    clang/test/OpenMP/task_ast_print.cpp
    clang/test/OpenMP/task_depend_messages.cpp
    clang/tools/libclang/CIndex.cpp
    clang/tools/libclang/CXCursor.cpp

Removed: 
    


################################################################################
diff  --git a/clang/include/clang-c/Index.h b/clang/include/clang-c/Index.h
index 641f058dafaa..0acd50021ed8 100644
--- a/clang/include/clang-c/Index.h
+++ b/clang/include/clang-c/Index.h
@@ -2180,7 +2180,12 @@ enum CXCursorKind {
    */
   CXCursor_OMPArrayShapingExpr = 150,
 
-  CXCursor_LastExpr = CXCursor_OMPArrayShapingExpr,
+  /**
+   * OpenMP 5.0 [2.1.6 Iterators]
+   */
+  CXCursor_OMPIteratorExpr = 151,
+
+  CXCursor_LastExpr = CXCursor_OMPIteratorExpr,
 
   /* Statements */
   CXCursor_FirstStmt = 200,

diff  --git a/clang/include/clang/AST/ASTContext.h b/clang/include/clang/AST/ASTContext.h
index ebb5ca593843..6813ab58874e 100644
--- a/clang/include/clang/AST/ASTContext.h
+++ b/clang/include/clang/AST/ASTContext.h
@@ -970,7 +970,7 @@ class ASTContext : public RefCountedBase<ASTContext> {
 #include "clang/Basic/OpenCLImageTypes.def"
   CanQualType OCLSamplerTy, OCLEventTy, OCLClkEventTy;
   CanQualType OCLQueueTy, OCLReserveIDTy;
-  CanQualType OMPArraySectionTy, OMPArrayShapingTy;
+  CanQualType OMPArraySectionTy, OMPArrayShapingTy, OMPIteratorTy;
 #define EXT_OPAQUE_TYPE(ExtType, Id, Ext) \
   CanQualType Id##Ty;
 #include "clang/Basic/OpenCLExtensionTypes.def"

diff  --git a/clang/include/clang/AST/BuiltinTypes.def b/clang/include/clang/AST/BuiltinTypes.def
index f42503773945..f8eb4ec19c8f 100644
--- a/clang/include/clang/AST/BuiltinTypes.def
+++ b/clang/include/clang/AST/BuiltinTypes.def
@@ -316,8 +316,11 @@ PLACEHOLDER_TYPE(OMPArraySection, OMPArraySectionTy)
 // A placeholder type for OpenMP array shaping operation.
 PLACEHOLDER_TYPE(OMPArrayShaping, OMPArrayShapingTy)
 
+// A placeholder type for OpenMP iterators.
+PLACEHOLDER_TYPE(OMPIterator, OMPIteratorTy)
+
 #ifdef LAST_BUILTIN_TYPE
-LAST_BUILTIN_TYPE(OMPArrayShaping)
+LAST_BUILTIN_TYPE(OMPIterator)
 #undef LAST_BUILTIN_TYPE
 #endif
 

diff  --git a/clang/include/clang/AST/ComputeDependence.h b/clang/include/clang/AST/ComputeDependence.h
index 63947eaff73b..ab742c9b70dd 100644
--- a/clang/include/clang/AST/ComputeDependence.h
+++ b/clang/include/clang/AST/ComputeDependence.h
@@ -88,6 +88,7 @@ class PseudoObjectExpr;
 class AtomicExpr;
 class OMPArraySectionExpr;
 class OMPArrayShapingExpr;
+class OMPIteratorExpr;
 class ObjCArrayLiteral;
 class ObjCDictionaryLiteral;
 class ObjCBoxedExpr;
@@ -174,6 +175,7 @@ ExprDependence computeDependence(AtomicExpr *E);
 
 ExprDependence computeDependence(OMPArraySectionExpr *E);
 ExprDependence computeDependence(OMPArrayShapingExpr *E);
+ExprDependence computeDependence(OMPIteratorExpr *E);
 
 ExprDependence computeDependence(ObjCArrayLiteral *E);
 ExprDependence computeDependence(ObjCDictionaryLiteral *E);

diff  --git a/clang/include/clang/AST/ExprOpenMP.h b/clang/include/clang/AST/ExprOpenMP.h
index 4a0cd07f1dab..dc6e061604b3 100644
--- a/clang/include/clang/AST/ExprOpenMP.h
+++ b/clang/include/clang/AST/ExprOpenMP.h
@@ -205,6 +205,169 @@ class OMPArrayShapingExpr final
     return const_child_range(Begin, Begin + NumDims + 1);
   }
 };
+
+/// OpenMP 5.0 [2.1.6 Iterators]
+/// Iterators are identifiers that expand to multiple values in the clause on
+/// which they appear.
+/// The syntax of the iterator modifier is as follows:
+/// \code
+/// iterator(iterators-definition)
+/// \endcode
+/// where iterators-definition is one of the following:
+/// \code
+/// iterator-specifier [, iterators-definition ]
+/// \endcode
+/// where iterator-specifier is one of the following:
+/// \code
+/// [ iterator-type ] identifier = range-specification
+/// \endcode
+/// where identifier is a base language identifier.
+/// iterator-type is a type name.
+/// range-specification is of the form begin:end[:step], where begin and end are
+/// expressions for which their types can be converted to iterator-type and step
+/// is an integral expression.
+/// In an iterator-specifier, if the iterator-type is not specified then the
+/// type of that iterator is of int type.
+/// The iterator-type must be an integral or pointer type.
+/// The iterator-type must not be const qualified.
+class OMPIteratorExpr final
+    : public Expr,
+      private llvm::TrailingObjects<OMPIteratorExpr, Decl *, Expr *,
+                                    SourceLocation> {
+public:
+  /// Iterator range representation begin:end[:step].
+  struct IteratorRange {
+    Expr *Begin = nullptr;
+    Expr *End = nullptr;
+    Expr *Step = nullptr;
+  };
+  /// Iterator definition representation.
+  struct IteratorDefinition {
+    Decl *IteratorDecl = nullptr;
+    IteratorRange Range;
+    SourceLocation AssignmentLoc;
+    SourceLocation ColonLoc, SecondColonLoc;
+  };
+
+private:
+  friend TrailingObjects;
+  friend class ASTStmtReader;
+  friend class ASTStmtWriter;
+
+  /// Offset in the list of expressions for subelements of the ranges.
+  enum class RangeExprOffset {
+    Begin = 0,
+    End = 1,
+    Step = 2,
+    Total = 3,
+  };
+  /// Offset in the list of locations for subelements of colon symbols
+  /// locations.
+  enum class RangeLocOffset {
+    AssignLoc = 0,
+    FirstColonLoc = 1,
+    SecondColonLoc = 2,
+    Total = 3,
+  };
+  /// Location of 'iterator' keyword.
+  SourceLocation IteratorKwLoc;
+  /// Location of '('.
+  SourceLocation LPLoc;
+  /// Location of ')'.
+  SourceLocation RPLoc;
+  /// Number of iterator definitions.
+  unsigned NumIterators = 0;
+
+  OMPIteratorExpr(QualType ExprTy, SourceLocation IteratorKwLoc,
+                  SourceLocation L, SourceLocation R,
+                  ArrayRef<OMPIteratorExpr::IteratorDefinition> Data);
+
+  /// Construct an empty expression.
+  explicit OMPIteratorExpr(EmptyShell Shell, unsigned NumIterators)
+      : Expr(OMPIteratorExprClass, Shell), NumIterators(NumIterators) {}
+
+  /// Sets basic declaration for the specified iterator definition.
+  void setIteratorDeclaration(unsigned I, Decl *D);
+
+  /// Sets the location of the assignment symbol for the specified iterator
+  /// definition.
+  void setAssignmentLoc(unsigned I, SourceLocation Loc);
+
+  /// Sets begin, end and optional step expressions for specified iterator
+  /// definition.
+  void setIteratorRange(unsigned I, Expr *Begin, SourceLocation ColonLoc,
+                        Expr *End, SourceLocation SecondColonLoc, Expr *Step);
+
+  unsigned numTrailingObjects(OverloadToken<Decl *>) const {
+    return NumIterators;
+  }
+
+  unsigned numTrailingObjects(OverloadToken<Expr *>) const {
+    return NumIterators * static_cast<int>(RangeExprOffset::Total);
+  }
+
+public:
+  static OMPIteratorExpr *Create(const ASTContext &Context, QualType T,
+                                 SourceLocation IteratorKwLoc, SourceLocation L,
+                                 SourceLocation R,
+                                 ArrayRef<IteratorDefinition> Data);
+
+  static OMPIteratorExpr *CreateEmpty(const ASTContext &Context,
+                                      unsigned NumIterators);
+
+  SourceLocation getLParenLoc() const { return LPLoc; }
+  void setLParenLoc(SourceLocation L) { LPLoc = L; }
+
+  SourceLocation getRParenLoc() const { return RPLoc; }
+  void setRParenLoc(SourceLocation L) { RPLoc = L; }
+
+  SourceLocation getIteratorKwLoc() const { return IteratorKwLoc; }
+  void setIteratorKwLoc(SourceLocation L) { IteratorKwLoc = L; }
+  SourceLocation getBeginLoc() const LLVM_READONLY { return IteratorKwLoc; }
+  SourceLocation getEndLoc() const LLVM_READONLY { return RPLoc; }
+
+  /// Gets the iterator declaration for the given iterator.
+  Decl *getIteratorDecl(unsigned I);
+  const Decl *getIteratorDecl(unsigned I) const {
+    return const_cast<OMPIteratorExpr *>(this)->getIteratorDecl(I);
+  }
+
+  /// Gets the iterator range for the given iterator.
+  IteratorRange getIteratorRange(unsigned I);
+  const IteratorRange getIteratorRange(unsigned I) const {
+    return const_cast<OMPIteratorExpr *>(this)->getIteratorRange(I);
+  }
+
+  /// Gets the location of '=' for the given iterator definition.
+  SourceLocation getAssignLoc(unsigned I) const;
+  /// Gets the location of the first ':' in the range for the given iterator
+  /// definition.
+  SourceLocation getColonLoc(unsigned I) const;
+  /// Gets the location of the second ':' (if any) in the range for the given
+  /// iteratori definition.
+  SourceLocation getSecondColonLoc(unsigned I) const;
+
+  /// Returns number of iterator definitions.
+  unsigned numOfIterators() const { return NumIterators; }
+
+  static bool classof(const Stmt *T) {
+    return T->getStmtClass() == OMPIteratorExprClass;
+  }
+
+  // Iterators
+  child_range children() {
+    Stmt **Begin = reinterpret_cast<Stmt **>(getTrailingObjects<Expr *>());
+    return child_range(
+        Begin, Begin + NumIterators * static_cast<int>(RangeExprOffset::Total));
+  }
+  const_child_range children() const {
+    Stmt *const *Begin =
+        reinterpret_cast<Stmt *const *>(getTrailingObjects<Expr *>());
+    return const_child_range(
+        Begin, Begin + NumIterators * static_cast<int>(RangeExprOffset::Total));
+  }
+};
+
 } // end namespace clang
 
 #endif

diff  --git a/clang/include/clang/AST/OpenMPClause.h b/clang/include/clang/AST/OpenMPClause.h
index 0d4b69911f19..028af6ac9a72 100644
--- a/clang/include/clang/AST/OpenMPClause.h
+++ b/clang/include/clang/AST/OpenMPClause.h
@@ -4372,6 +4372,9 @@ class OMPDependClause final
   /// Set colon location.
   void setColonLoc(SourceLocation Loc) { ColonLoc = Loc; }
 
+  /// Sets optional dependency modifier.
+  void setModifier(Expr *DepModifier);
+
 public:
   /// Creates clause with a list of variables \a VL.
   ///
@@ -4387,7 +4390,7 @@ class OMPDependClause final
   /// clause.
   static OMPDependClause *Create(const ASTContext &C, SourceLocation StartLoc,
                                  SourceLocation LParenLoc,
-                                 SourceLocation EndLoc,
+                                 SourceLocation EndLoc, Expr *DepModifier,
                                  OpenMPDependClauseKind DepKind,
                                  SourceLocation DepLoc, SourceLocation ColonLoc,
                                  ArrayRef<Expr *> VL, unsigned NumLoops);
@@ -4404,6 +4407,12 @@ class OMPDependClause final
   /// Get dependency type.
   OpenMPDependClauseKind getDependencyKind() const { return DepKind; }
 
+  /// Return optional depend modifier.
+  Expr *getModifier();
+  const Expr *getModifier() const {
+    return const_cast<OMPDependClause *>(this)->getModifier();
+  }
+
   /// Get dependency type location.
   SourceLocation getDependencyLoc() const { return DepLoc; }
 

diff  --git a/clang/include/clang/AST/RecursiveASTVisitor.h b/clang/include/clang/AST/RecursiveASTVisitor.h
index 46661e59f181..345333849659 100644
--- a/clang/include/clang/AST/RecursiveASTVisitor.h
+++ b/clang/include/clang/AST/RecursiveASTVisitor.h
@@ -2552,6 +2552,7 @@ DEF_TRAVERSE_STMT(AddrLabelExpr, {})
 DEF_TRAVERSE_STMT(ArraySubscriptExpr, {})
 DEF_TRAVERSE_STMT(OMPArraySectionExpr, {})
 DEF_TRAVERSE_STMT(OMPArrayShapingExpr, {})
+DEF_TRAVERSE_STMT(OMPIteratorExpr, {})
 
 DEF_TRAVERSE_STMT(BlockExpr, {
   TRY_TO(TraverseDecl(S->getBlockDecl()));

diff  --git a/clang/include/clang/AST/TextNodeDumper.h b/clang/include/clang/AST/TextNodeDumper.h
index b08d1e482be8..0fb4baf0ca4d 100644
--- a/clang/include/clang/AST/TextNodeDumper.h
+++ b/clang/include/clang/AST/TextNodeDumper.h
@@ -274,6 +274,7 @@ class TextNodeDumper
   void VisitObjCSubscriptRefExpr(const ObjCSubscriptRefExpr *Node);
   void VisitObjCIvarRefExpr(const ObjCIvarRefExpr *Node);
   void VisitObjCBoolLiteralExpr(const ObjCBoolLiteralExpr *Node);
+  void VisitOMPIteratorExpr(const OMPIteratorExpr *Node);
 
   void VisitRValueReferenceType(const ReferenceType *T);
   void VisitArrayType(const ArrayType *T);

diff  --git a/clang/include/clang/Basic/DiagnosticParseKinds.td b/clang/include/clang/Basic/DiagnosticParseKinds.td
index 6eb320a85a30..f3741531c8b5 100644
--- a/clang/include/clang/Basic/DiagnosticParseKinds.td
+++ b/clang/include/clang/Basic/DiagnosticParseKinds.td
@@ -1220,6 +1220,10 @@ def err_omp_expected_identifier_for_critical : Error<
   "expected identifier specifying the name of the 'omp critical' directive">;
 def err_omp_expected_reduction_identifier : Error<
   "expected identifier or one of the following operators: '+', '-', '*', '&', '|', '^', '&&', or '||'">;
+def err_omp_expected_equal_in_iterator : Error<
+  "expected '=' in iterator specifier">;
+def err_omp_expected_punc_after_iterator : Error<
+  "expected ',' or ')' after iterator specifier">;
 def err_omp_decl_in_declare_simd_variant : Error<
   "function declaration is expected after 'declare %select{simd|variant}0' directive">;
 def err_omp_unknown_map_type : Error<

diff  --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 951a955984f6..901ac758b383 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -9760,6 +9760,14 @@ def note_omp_conversion_here : Note<
 def err_omp_ambiguous_conversion : Error<
   "ambiguous conversion from type %0 to an integral or unscoped "
   "enumeration type">;
+def err_omp_iterator_not_integral_or_pointer : Error<
+  "expected integral or pointer type as the iterator-type, not %0">;
+def err_omp_iterator_constant : Error<
+  "expected non-constant type as the iterator-type, constant %0 is provided">;
+def err_omp_iterator_step_not_integral : Error<
+  "iterator step expression %0 is not the integral expression">;
+def err_omp_iterator_step_constant_zero : Error<
+  "iterator step expression %0 evaluates to 0">;
 def err_omp_required_access : Error<
   "%0 variable must be %1">;
 def err_omp_const_variable : Error<
@@ -9953,6 +9961,7 @@ def err_omp_invalid_mapper: Error<
   "cannot find a valid user-defined mapper for type %0 with name %1">;
 def err_omp_array_section_use : Error<"OpenMP array section is not allowed here">;
 def err_omp_array_shaping_use : Error<"OpenMP array shaping operation is not allowed here">;
+def err_omp_iterator_use : Error<"OpenMP iterator is not allowed here">;
 def err_omp_typecheck_section_value : Error<
   "subscripted value is not an array or pointer">;
 def err_omp_typecheck_section_not_integer : Error<
@@ -10031,6 +10040,10 @@ def err_omp_depend_sink_source_not_allowed : Error<
   "'depend(%select{source|sink:vec}0)' clause%select{|s}0 cannot be mixed with 'depend(%select{sink:vec|source}0)' clause%select{s|}0">;
 def err_omp_depend_zero_length_array_section_not_allowed : Error<
   "zero-length array section is not allowed in 'depend' clause">;
+def err_omp_depend_sink_source_with_modifier : Error<
+  "depend modifier cannot be used with 'sink' or 'source' depend type">;
+def err_omp_depend_modifier_not_iterator : Error<
+  "expected iterator specification as depend modifier">;
 def err_omp_linear_ordered : Error<
   "'linear' clause cannot be specified along with 'ordered' clause with a parameter">;
 def err_omp_unexpected_schedule_modifier : Error<

diff  --git a/clang/include/clang/Basic/StmtNodes.td b/clang/include/clang/Basic/StmtNodes.td
index ba1b5ebd6305..aecf24f89033 100644
--- a/clang/include/clang/Basic/StmtNodes.td
+++ b/clang/include/clang/Basic/StmtNodes.td
@@ -70,6 +70,7 @@ def OffsetOfExpr : StmtNode<Expr>;
 def UnaryExprOrTypeTraitExpr : StmtNode<Expr>;
 def ArraySubscriptExpr : StmtNode<Expr>;
 def OMPArraySectionExpr : StmtNode<Expr>;
+def OMPIteratorExpr : StmtNode<Expr>;
 def CallExpr : StmtNode<Expr>;
 def MemberExpr : StmtNode<Expr>;
 def CastExpr : StmtNode<Expr, 1>;

diff  --git a/clang/include/clang/Parse/Parser.h b/clang/include/clang/Parse/Parser.h
index 290da0006116..ca0a5fd68994 100644
--- a/clang/include/clang/Parse/Parser.h
+++ b/clang/include/clang/Parse/Parser.h
@@ -3086,6 +3086,11 @@ class Parser : public CodeCompletionHandler {
   OMPClause *ParseOpenMPVarListClause(OpenMPDirectiveKind DKind,
                                       OpenMPClauseKind Kind, bool ParseOnly);
 
+  /// Parses and creates OpenMP 5.0 iterators expression:
+  /// <iterators> = 'iterator' '(' { [ <iterator-type> ] identifier =
+  /// <range-specification> }+ ')'
+  ExprResult ParseOpenMPIteratorsExpr();
+
 public:
   /// Parses simple expression in parens for single-expression clauses of OpenMP
   /// constructs.
@@ -3095,7 +3100,7 @@ class Parser : public CodeCompletionHandler {
 
   /// Data used for parsing list of variables in OpenMP clauses.
   struct OpenMPVarListDataTy {
-    Expr *TailExpr = nullptr;
+    Expr *DepModOrTailExpr = nullptr;
     SourceLocation ColonLoc;
     SourceLocation RLoc;
     CXXScopeSpec ReductionOrMapperIdScopeSpec;

diff  --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index 9a41356ddb70..e1365e84a0b3 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -25,6 +25,7 @@
 #include "clang/AST/ExprCXX.h"
 #include "clang/AST/ExprConcepts.h"
 #include "clang/AST/ExprObjC.h"
+#include "clang/AST/ExprOpenMP.h"
 #include "clang/AST/ExternalASTSource.h"
 #include "clang/AST/LocInfoType.h"
 #include "clang/AST/MangleNumberingContext.h"
@@ -4904,6 +4905,21 @@ class Sema final {
                                       ArrayRef<Expr *> Dims,
                                       ArrayRef<SourceRange> Brackets);
 
+  /// Data structure for iterator expression.
+  struct OMPIteratorData {
+    IdentifierInfo *DeclIdent = nullptr;
+    SourceLocation DeclIdentLoc;
+    ParsedType Type;
+    OMPIteratorExpr::IteratorRange Range;
+    SourceLocation AssignLoc;
+    SourceLocation ColonLoc;
+    SourceLocation SecColonLoc;
+  };
+
+  ExprResult ActOnOMPIteratorExpr(Scope *S, SourceLocation IteratorKwLoc,
+                                  SourceLocation LLoc, SourceLocation RLoc,
+                                  ArrayRef<OMPIteratorData> Data);
+
   // This struct is for use by ActOnMemberAccess to allow
   // BuildMemberReferenceExpr to be able to reinvoke ActOnMemberAccess after
   // changing the access operator from a '.' to a '->' (to see if that is the
@@ -10572,7 +10588,7 @@ class Sema final {
       SourceLocation StartLoc, SourceLocation LParenLoc, SourceLocation EndLoc);
 
   OMPClause *ActOnOpenMPVarListClause(
-      OpenMPClauseKind Kind, ArrayRef<Expr *> Vars, Expr *TailExpr,
+      OpenMPClauseKind Kind, ArrayRef<Expr *> Vars, Expr *DepModOrTailExpr,
       const OMPVarListLocTy &Locs, SourceLocation ColonLoc,
       CXXScopeSpec &ReductionOrMapperIdScopeSpec,
       DeclarationNameInfo &ReductionOrMapperId, int ExtraModifier,
@@ -10670,10 +10686,10 @@ class Sema final {
                                      SourceLocation EndLoc);
   /// Called on well-formed 'depend' clause.
   OMPClause *
-  ActOnOpenMPDependClause(OpenMPDependClauseKind DepKind, SourceLocation DepLoc,
-                          SourceLocation ColonLoc, ArrayRef<Expr *> VarList,
-                          SourceLocation StartLoc, SourceLocation LParenLoc,
-                          SourceLocation EndLoc);
+  ActOnOpenMPDependClause(Expr *DepModifier, OpenMPDependClauseKind DepKind,
+                          SourceLocation DepLoc, SourceLocation ColonLoc,
+                          ArrayRef<Expr *> VarList, SourceLocation StartLoc,
+                          SourceLocation LParenLoc, SourceLocation EndLoc);
   /// Called on well-formed 'device' clause.
   OMPClause *ActOnOpenMPDeviceClause(OpenMPDeviceClauseModifier Modifier,
                                      Expr *Device, SourceLocation StartLoc,

diff  --git a/clang/include/clang/Serialization/ASTBitCodes.h b/clang/include/clang/Serialization/ASTBitCodes.h
index 68bcb26b6df5..e6e9c8570cc8 100644
--- a/clang/include/clang/Serialization/ASTBitCodes.h
+++ b/clang/include/clang/Serialization/ASTBitCodes.h
@@ -1019,6 +1019,9 @@ namespace serialization {
       /// The placeholder type for OpenMP array shaping operation.
       PREDEF_TYPE_OMP_ARRAY_SHAPING = 70,
 
+      /// The placeholder type for OpenMP iterator expression.
+      PREDEF_TYPE_OMP_ITERATOR = 71,
+
       /// OpenCL image types with auto numeration
 #define IMAGE_TYPE(ImgType, Id, SingletonId, Access, Suffix) \
       PREDEF_TYPE_##Id##_ID,
@@ -1872,6 +1875,7 @@ namespace serialization {
       STMT_OMP_TARGET_TEAMS_DISTRIBUTE_SIMD_DIRECTIVE,
       EXPR_OMP_ARRAY_SECTION,
       EXPR_OMP_ARRAY_SHAPING,
+      EXPR_OMP_ITERATOR,
 
       // ARC
       EXPR_OBJC_BRIDGED_CAST,     // ObjCBridgedCastExpr

diff  --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
index 8bee34e65754..1e81e0a67b4d 100644
--- a/clang/lib/AST/ASTContext.cpp
+++ b/clang/lib/AST/ASTContext.cpp
@@ -1389,6 +1389,7 @@ void ASTContext::InitBuiltinTypes(const TargetInfo &Target,
   if (LangOpts.OpenMP) {
     InitBuiltinType(OMPArraySectionTy, BuiltinType::OMPArraySection);
     InitBuiltinType(OMPArrayShapingTy, BuiltinType::OMPArrayShaping);
+    InitBuiltinType(OMPIteratorTy, BuiltinType::OMPIterator);
   }
 
   // C99 6.2.5p11.

diff  --git a/clang/lib/AST/ComputeDependence.cpp b/clang/lib/AST/ComputeDependence.cpp
index a023ed173184..3a326f62a2ec 100644
--- a/clang/lib/AST/ComputeDependence.cpp
+++ b/clang/lib/AST/ComputeDependence.cpp
@@ -372,6 +372,22 @@ ExprDependence clang::computeDependence(OMPArrayShapingExpr *E) {
   return D;
 }
 
+ExprDependence clang::computeDependence(OMPIteratorExpr *E) {
+  auto D = toExprDependence(E->getType()->getDependence());
+  for (unsigned I = 0, End = E->numOfIterators(); I < End; ++I) {
+    if (auto *VD = cast_or_null<ValueDecl>(E->getIteratorDecl(I)))
+      D |= toExprDependence(VD->getType()->getDependence());
+    OMPIteratorExpr::IteratorRange IR = E->getIteratorRange(I);
+    if (Expr *BE = IR.Begin)
+      D |= BE->getDependence();
+    if (Expr *EE = IR.End)
+      D |= EE->getDependence();
+    if (Expr *SE = IR.Step)
+      D |= SE->getDependence();
+  }
+  return D;
+}
+
 /// Compute the type-, value-, and instantiation-dependence of a
 /// declaration reference
 /// based on the declaration being referenced.

diff  --git a/clang/lib/AST/Expr.cpp b/clang/lib/AST/Expr.cpp
index fb63897d871f..d82381d611ef 100644
--- a/clang/lib/AST/Expr.cpp
+++ b/clang/lib/AST/Expr.cpp
@@ -3399,6 +3399,7 @@ bool Expr::HasSideEffects(const ASTContext &Ctx,
   case ArraySubscriptExprClass:
   case OMPArraySectionExprClass:
   case OMPArrayShapingExprClass:
+  case OMPIteratorExprClass:
   case MemberExprClass:
   case ConditionalOperatorClass:
   case BinaryConditionalOperatorClass:
@@ -4617,3 +4618,118 @@ OMPArrayShapingExpr *OMPArrayShapingExpr::CreateEmpty(const ASTContext &Context,
       alignof(OMPArrayShapingExpr));
   return new (Mem) OMPArrayShapingExpr(EmptyShell(), NumDims);
 }
+
+void OMPIteratorExpr::setIteratorDeclaration(unsigned I, Decl *D) {
+  assert(I < NumIterators &&
+         "Idx is greater or equal the number of iterators definitions.");
+  getTrailingObjects<Decl *>()[I] = D;
+}
+
+void OMPIteratorExpr::setAssignmentLoc(unsigned I, SourceLocation Loc) {
+  assert(I < NumIterators &&
+         "Idx is greater or equal the number of iterators definitions.");
+  getTrailingObjects<
+      SourceLocation>()[I * static_cast<int>(RangeLocOffset::Total) +
+                        static_cast<int>(RangeLocOffset::AssignLoc)] = Loc;
+}
+
+void OMPIteratorExpr::setIteratorRange(unsigned I, Expr *Begin,
+                                       SourceLocation ColonLoc, Expr *End,
+                                       SourceLocation SecondColonLoc,
+                                       Expr *Step) {
+  assert(I < NumIterators &&
+         "Idx is greater or equal the number of iterators definitions.");
+  getTrailingObjects<Expr *>()[I * static_cast<int>(RangeExprOffset::Total) +
+                               static_cast<int>(RangeExprOffset::Begin)] =
+      Begin;
+  getTrailingObjects<Expr *>()[I * static_cast<int>(RangeExprOffset::Total) +
+                               static_cast<int>(RangeExprOffset::End)] = End;
+  getTrailingObjects<Expr *>()[I * static_cast<int>(RangeExprOffset::Total) +
+                               static_cast<int>(RangeExprOffset::Step)] = Step;
+  getTrailingObjects<
+      SourceLocation>()[I * static_cast<int>(RangeLocOffset::Total) +
+                        static_cast<int>(RangeLocOffset::FirstColonLoc)] =
+      ColonLoc;
+  getTrailingObjects<
+      SourceLocation>()[I * static_cast<int>(RangeLocOffset::Total) +
+                        static_cast<int>(RangeLocOffset::SecondColonLoc)] =
+      SecondColonLoc;
+}
+
+Decl *OMPIteratorExpr::getIteratorDecl(unsigned I) {
+  return getTrailingObjects<Decl *>()[I];
+}
+
+OMPIteratorExpr::IteratorRange OMPIteratorExpr::getIteratorRange(unsigned I) {
+  IteratorRange Res;
+  Res.Begin =
+      getTrailingObjects<Expr *>()[I * static_cast<int>(
+                                           RangeExprOffset::Total) +
+                                   static_cast<int>(RangeExprOffset::Begin)];
+  Res.End =
+      getTrailingObjects<Expr *>()[I * static_cast<int>(
+                                           RangeExprOffset::Total) +
+                                   static_cast<int>(RangeExprOffset::End)];
+  Res.Step =
+      getTrailingObjects<Expr *>()[I * static_cast<int>(
+                                           RangeExprOffset::Total) +
+                                   static_cast<int>(RangeExprOffset::Step)];
+  return Res;
+}
+
+SourceLocation OMPIteratorExpr::getAssignLoc(unsigned I) const {
+  return getTrailingObjects<
+      SourceLocation>()[I * static_cast<int>(RangeLocOffset::Total) +
+                        static_cast<int>(RangeLocOffset::AssignLoc)];
+}
+
+SourceLocation OMPIteratorExpr::getColonLoc(unsigned I) const {
+  return getTrailingObjects<
+      SourceLocation>()[I * static_cast<int>(RangeLocOffset::Total) +
+                        static_cast<int>(RangeLocOffset::FirstColonLoc)];
+}
+
+SourceLocation OMPIteratorExpr::getSecondColonLoc(unsigned I) const {
+  return getTrailingObjects<
+      SourceLocation>()[I * static_cast<int>(RangeLocOffset::Total) +
+                        static_cast<int>(RangeLocOffset::SecondColonLoc)];
+}
+
+OMPIteratorExpr::OMPIteratorExpr(
+    QualType ExprTy, SourceLocation IteratorKwLoc, SourceLocation L,
+    SourceLocation R, ArrayRef<OMPIteratorExpr::IteratorDefinition> Data)
+    : Expr(OMPIteratorExprClass, ExprTy, VK_LValue, OK_Ordinary),
+      IteratorKwLoc(IteratorKwLoc), LPLoc(L), RPLoc(R),
+      NumIterators(Data.size()) {
+  for (unsigned I = 0, E = Data.size(); I < E; ++I) {
+    const IteratorDefinition &D = Data[I];
+    setIteratorDeclaration(I, D.IteratorDecl);
+    setAssignmentLoc(I, D.AssignmentLoc);
+    setIteratorRange(I, D.Range.Begin, D.ColonLoc, D.Range.End,
+                     D.SecondColonLoc, D.Range.Step);
+  }
+  setDependence(computeDependence(this));
+}
+
+OMPIteratorExpr *
+OMPIteratorExpr::Create(const ASTContext &Context, QualType T,
+                        SourceLocation IteratorKwLoc, SourceLocation L,
+                        SourceLocation R,
+                        ArrayRef<OMPIteratorExpr::IteratorDefinition> Data) {
+  void *Mem = Context.Allocate(
+      totalSizeToAlloc<Decl *, Expr *, SourceLocation>(
+          Data.size(), Data.size() * static_cast<int>(RangeExprOffset::Total),
+          Data.size() * static_cast<int>(RangeLocOffset::Total)),
+      alignof(OMPIteratorExpr));
+  return new (Mem) OMPIteratorExpr(T, IteratorKwLoc, L, R, Data);
+}
+
+OMPIteratorExpr *OMPIteratorExpr::CreateEmpty(const ASTContext &Context,
+                                              unsigned NumIterators) {
+  void *Mem = Context.Allocate(
+      totalSizeToAlloc<Decl *, Expr *, SourceLocation>(
+          NumIterators, NumIterators * static_cast<int>(RangeExprOffset::Total),
+          NumIterators * static_cast<int>(RangeLocOffset::Total)),
+      alignof(OMPIteratorExpr));
+  return new (Mem) OMPIteratorExpr(EmptyShell(), NumIterators);
+}

diff  --git a/clang/lib/AST/ExprClassification.cpp b/clang/lib/AST/ExprClassification.cpp
index 4505626bb61f..8587a476a5d9 100644
--- a/clang/lib/AST/ExprClassification.cpp
+++ b/clang/lib/AST/ExprClassification.cpp
@@ -141,6 +141,7 @@ static Cl::Kinds ClassifyInternal(ASTContext &Ctx, const Expr *E) {
   case Expr::MSPropertySubscriptExprClass:
   case Expr::OMPArraySectionExprClass:
   case Expr::OMPArrayShapingExprClass:
+  case Expr::OMPIteratorExprClass:
     return Cl::CL_LValue;
 
     // C99 6.5.2.5p5 says that compound literals are lvalues.

diff  --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index 4a11c846f4ab..c6e1cc7b67df 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -14181,6 +14181,7 @@ static ICEDiag CheckICE(const Expr* E, const ASTContext &Ctx) {
   case Expr::ArraySubscriptExprClass:
   case Expr::OMPArraySectionExprClass:
   case Expr::OMPArrayShapingExprClass:
+  case Expr::OMPIteratorExprClass:
   case Expr::MemberExprClass:
   case Expr::CompoundAssignOperatorClass:
   case Expr::CompoundLiteralExprClass:

diff  --git a/clang/lib/AST/ItaniumMangle.cpp b/clang/lib/AST/ItaniumMangle.cpp
index 4c05990ee410..cb7bd61574ef 100644
--- a/clang/lib/AST/ItaniumMangle.cpp
+++ b/clang/lib/AST/ItaniumMangle.cpp
@@ -3715,6 +3715,7 @@ void CXXNameMangler::mangleExpression(const Expr *E, unsigned Arity) {
   case Expr::RecoveryExprClass:
   case Expr::OMPArraySectionExprClass:
   case Expr::OMPArrayShapingExprClass:
+  case Expr::OMPIteratorExprClass:
   case Expr::CXXInheritedCtorInitExprClass:
     llvm_unreachable("unexpected statement kind");
 

diff  --git a/clang/lib/AST/NSAPI.cpp b/clang/lib/AST/NSAPI.cpp
index 2bfe977a5ba5..3bb3605ea936 100644
--- a/clang/lib/AST/NSAPI.cpp
+++ b/clang/lib/AST/NSAPI.cpp
@@ -484,6 +484,7 @@ NSAPI::getNSNumberFactoryMethodKind(QualType T) const {
   case BuiltinType::BuiltinFn:
   case BuiltinType::OMPArraySection:
   case BuiltinType::OMPArrayShaping:
+  case BuiltinType::OMPIterator:
     break;
   }
 

diff  --git a/clang/lib/AST/OpenMPClause.cpp b/clang/lib/AST/OpenMPClause.cpp
index 4b7ebbb3c26d..eeb690750fb7 100644
--- a/clang/lib/AST/OpenMPClause.cpp
+++ b/clang/lib/AST/OpenMPClause.cpp
@@ -900,16 +900,19 @@ OMPDepobjClause *OMPDepobjClause::CreateEmpty(const ASTContext &C) {
 OMPDependClause *
 OMPDependClause::Create(const ASTContext &C, SourceLocation StartLoc,
                         SourceLocation LParenLoc, SourceLocation EndLoc,
-                        OpenMPDependClauseKind DepKind, SourceLocation DepLoc,
-                        SourceLocation ColonLoc, ArrayRef<Expr *> VL,
-                        unsigned NumLoops) {
-  void *Mem = C.Allocate(totalSizeToAlloc<Expr *>(VL.size() + NumLoops));
+                        Expr *DepModifier, OpenMPDependClauseKind DepKind,
+                        SourceLocation DepLoc, SourceLocation ColonLoc,
+                        ArrayRef<Expr *> VL, unsigned NumLoops) {
+  void *Mem = C.Allocate(
+      totalSizeToAlloc<Expr *>(VL.size() + /*depend-modifier*/ 1 + NumLoops),
+      alignof(OMPDependClause));
   OMPDependClause *Clause = new (Mem)
       OMPDependClause(StartLoc, LParenLoc, EndLoc, VL.size(), NumLoops);
   Clause->setVarRefs(VL);
   Clause->setDependencyKind(DepKind);
   Clause->setDependencyLoc(DepLoc);
   Clause->setColonLoc(ColonLoc);
+  Clause->setModifier(DepModifier);
   for (unsigned I = 0 ; I < NumLoops; ++I)
     Clause->setLoopData(I, nullptr);
   return Clause;
@@ -917,7 +920,9 @@ OMPDependClause::Create(const ASTContext &C, SourceLocation StartLoc,
 
 OMPDependClause *OMPDependClause::CreateEmpty(const ASTContext &C, unsigned N,
                                               unsigned NumLoops) {
-  void *Mem = C.Allocate(totalSizeToAlloc<Expr *>(N + NumLoops));
+  void *Mem =
+      C.Allocate(totalSizeToAlloc<Expr *>(N + /*depend-modifier*/ 1 + NumLoops),
+                 alignof(OMPDependClause));
   return new (Mem) OMPDependClause(N, NumLoops);
 }
 
@@ -927,7 +932,7 @@ void OMPDependClause::setLoopData(unsigned NumLoop, Expr *Cnt) {
          NumLoop < NumLoops &&
          "Expected sink or source depend + loop index must be less number of "
          "loops.");
-  auto It = std::next(getVarRefs().end(), NumLoop);
+  auto *It = std::next(getVarRefs().end(), NumLoop + 1);
   *It = Cnt;
 }
 
@@ -937,7 +942,7 @@ Expr *OMPDependClause::getLoopData(unsigned NumLoop) {
          NumLoop < NumLoops &&
          "Expected sink or source depend + loop index must be less number of "
          "loops.");
-  auto It = std::next(getVarRefs().end(), NumLoop);
+  auto *It = std::next(getVarRefs().end(), NumLoop + 1);
   return *It;
 }
 
@@ -947,10 +952,15 @@ const Expr *OMPDependClause::getLoopData(unsigned NumLoop) const {
          NumLoop < NumLoops &&
          "Expected sink or source depend + loop index must be less number of "
          "loops.");
-  auto It = std::next(getVarRefs().end(), NumLoop);
+  const auto *It = std::next(getVarRefs().end(), NumLoop + 1);
   return *It;
 }
 
+void OMPDependClause::setModifier(Expr *DepModifier) {
+  *getVarRefs().end() = DepModifier;
+}
+Expr *OMPDependClause::getModifier() { return *getVarRefs().end(); }
+
 unsigned OMPClauseMappableExprCommon::getComponentsTotalNumber(
     MappableExprComponentListsRef ComponentLists) {
   unsigned TotalNum = 0u;
@@ -1727,6 +1737,10 @@ void OMPClausePrinter::VisitOMPDepobjClause(OMPDepobjClause *Node) {
 
 void OMPClausePrinter::VisitOMPDependClause(OMPDependClause *Node) {
   OS << "depend(";
+  if (Expr *DepModifier = Node->getModifier()) {
+    DepModifier->printPretty(OS, nullptr, Policy);
+    OS << ", ";
+  }
   OS << getOpenMPSimpleClauseTypeName(Node->getClauseKind(),
                                       Node->getDependencyKind());
   if (!Node->varlist_empty()) {

diff  --git a/clang/lib/AST/StmtPrinter.cpp b/clang/lib/AST/StmtPrinter.cpp
index 3d03f3902d61..6537ca98667e 100644
--- a/clang/lib/AST/StmtPrinter.cpp
+++ b/clang/lib/AST/StmtPrinter.cpp
@@ -1361,6 +1361,26 @@ void StmtPrinter::VisitOMPArrayShapingExpr(OMPArrayShapingExpr *Node) {
   PrintExpr(Node->getBase());
 }
 
+void StmtPrinter::VisitOMPIteratorExpr(OMPIteratorExpr *Node) {
+  OS << "iterator(";
+  for (unsigned I = 0, E = Node->numOfIterators(); I < E; ++I) {
+    auto *VD = cast<ValueDecl>(Node->getIteratorDecl(I));
+    VD->getType().print(OS, Policy);
+    const OMPIteratorExpr::IteratorRange Range = Node->getIteratorRange(I);
+    OS << " " << VD->getName() << " = ";
+    PrintExpr(Range.Begin);
+    OS << ":";
+    PrintExpr(Range.End);
+    if (Range.Step) {
+      OS << ":";
+      PrintExpr(Range.Step);
+    }
+    if (I < E - 1)
+      OS << ", ";
+  }
+  OS << ")";
+}
+
 void StmtPrinter::PrintCallArgs(CallExpr *Call) {
   for (unsigned i = 0, e = Call->getNumArgs(); i != e; ++i) {
     if (isa<CXXDefaultArgExpr>(Call->getArg(i))) {

diff  --git a/clang/lib/AST/StmtProfile.cpp b/clang/lib/AST/StmtProfile.cpp
index 054276a98424..fec12ac98b4e 100644
--- a/clang/lib/AST/StmtProfile.cpp
+++ b/clang/lib/AST/StmtProfile.cpp
@@ -1198,6 +1198,12 @@ void StmtProfiler::VisitOMPArrayShapingExpr(const OMPArrayShapingExpr *S) {
   VisitExpr(S);
 }
 
+void StmtProfiler::VisitOMPIteratorExpr(const OMPIteratorExpr *S) {
+  VisitExpr(S);
+  for (unsigned I = 0, E = S->numOfIterators(); I < E; ++I)
+    VisitDecl(S->getIteratorDecl(I));
+}
+
 void StmtProfiler::VisitCallExpr(const CallExpr *S) {
   VisitExpr(S);
 }

diff  --git a/clang/lib/AST/TextNodeDumper.cpp b/clang/lib/AST/TextNodeDumper.cpp
index 6a6d8692228a..dc0dd92f09df 100644
--- a/clang/lib/AST/TextNodeDumper.cpp
+++ b/clang/lib/AST/TextNodeDumper.cpp
@@ -1086,6 +1086,23 @@ void TextNodeDumper::VisitObjCBoolLiteralExpr(const ObjCBoolLiteralExpr *Node) {
   OS << " " << (Node->getValue() ? "__objc_yes" : "__objc_no");
 }
 
+void TextNodeDumper::VisitOMPIteratorExpr(const OMPIteratorExpr *Node) {
+  OS << " ";
+  for (unsigned I = 0, E = Node->numOfIterators(); I < E; ++I) {
+    Visit(Node->getIteratorDecl(I));
+    OS << " = ";
+    const OMPIteratorExpr::IteratorRange Range = Node->getIteratorRange(I);
+    OS << " begin ";
+    Visit(Range.Begin);
+    OS << " end ";
+    Visit(Range.End);
+    if (Range.Step) {
+      OS << " step ";
+      Visit(Range.Step);
+    }
+  }
+}
+
 void TextNodeDumper::VisitRValueReferenceType(const ReferenceType *T) {
   if (T->isSpelledAsLValue())
     OS << " written as lvalue reference";

diff  --git a/clang/lib/AST/Type.cpp b/clang/lib/AST/Type.cpp
index f90eb5cb9c92..3428437c3146 100644
--- a/clang/lib/AST/Type.cpp
+++ b/clang/lib/AST/Type.cpp
@@ -2910,6 +2910,8 @@ StringRef BuiltinType::getName(const PrintingPolicy &Policy) const {
     return "<OpenMP array section type>";
   case OMPArrayShaping:
     return "<OpenMP array shaping type>";
+  case OMPIterator:
+    return "<OpenMP iterator type>";
 #define EXT_OPAQUE_TYPE(ExtType, Id, Ext) \
   case Id: \
     return #ExtType;
@@ -3917,6 +3919,7 @@ bool Type::canHaveNullability(bool ResultIfUnknown) const {
     case BuiltinType::NullPtr:
     case BuiltinType::OMPArraySection:
     case BuiltinType::OMPArrayShaping:
+    case BuiltinType::OMPIterator:
       return false;
     }
     llvm_unreachable("unknown builtin type");

diff  --git a/clang/lib/AST/TypeLoc.cpp b/clang/lib/AST/TypeLoc.cpp
index dd48ae3fc262..50391dba2a05 100644
--- a/clang/lib/AST/TypeLoc.cpp
+++ b/clang/lib/AST/TypeLoc.cpp
@@ -405,6 +405,7 @@ TypeSpecifierType BuiltinTypeLoc::getWrittenTypeSpec() const {
   case BuiltinType::BuiltinFn:
   case BuiltinType::OMPArraySection:
   case BuiltinType::OMPArrayShaping:
+  case BuiltinType::OMPIterator:
     return TST_unspecified;
   }
 

diff  --git a/clang/lib/Parse/ParseOpenMP.cpp b/clang/lib/Parse/ParseOpenMP.cpp
index 147d1b271d0c..1f5ed3d9c999 100644
--- a/clang/lib/Parse/ParseOpenMP.cpp
+++ b/clang/lib/Parse/ParseOpenMP.cpp
@@ -755,7 +755,8 @@ static bool parseDeclareSimdClauses(
                                  getOpenMPClauseKind(ClauseName), *Vars, Data))
           IsError = true;
         if (CKind == OMPC_aligned) {
-          Alignments.append(Aligneds.size() - Alignments.size(), Data.TailExpr);
+          Alignments.append(Aligneds.size() - Alignments.size(),
+                            Data.DepModOrTailExpr);
         } else if (CKind == OMPC_linear) {
           assert(0 <= Data.ExtraModifier &&
                  Data.ExtraModifier <= OMPC_LINEAR_unknown &&
@@ -766,7 +767,7 @@ static bool parseDeclareSimdClauses(
             Data.ExtraModifier = OMPC_LINEAR_val;
           LinModifiers.append(Linears.size() - LinModifiers.size(),
                               Data.ExtraModifier);
-          Steps.append(Linears.size() - Steps.size(), Data.TailExpr);
+          Steps.append(Linears.size() - Steps.size(), Data.DepModOrTailExpr);
         }
       } else
         // TODO: add parsing of other clauses.
@@ -3054,6 +3055,114 @@ static void parseMapType(Parser &P, Parser::OpenMPVarListDataTy &Data) {
   P.ConsumeToken();
 }
 
+/// Parses simple expression in parens for single-expression clauses of OpenMP
+/// constructs.
+/// \param RLoc Returned location of right paren.
+ExprResult Parser::ParseOpenMPIteratorsExpr() {
+  assert(Tok.is(tok::identifier) && PP.getSpelling(Tok) == "iterator" &&
+         "Expected 'iterator' token.");
+  SourceLocation IteratorKwLoc = ConsumeToken();
+
+  BalancedDelimiterTracker T(*this, tok::l_paren, tok::annot_pragma_openmp_end);
+  if (T.expectAndConsume(diag::err_expected_lparen_after, "iterator"))
+    return ExprError();
+
+  SourceLocation LLoc = T.getOpenLocation();
+  SmallVector<Sema::OMPIteratorData, 4> Data;
+  while (Tok.isNot(tok::r_paren) && Tok.isNot(tok::annot_pragma_openmp_end)) {
+    // Check if the type parsing is required.
+    ParsedType IteratorType;
+    if (Tok.isNot(tok::identifier) || NextToken().isNot(tok::equal)) {
+      // identifier '=' is not found - parse type.
+      TypeResult TR = ParseTypeName();
+      if (TR.isInvalid()) {
+        T.skipToEnd();
+        return ExprError();
+      }
+      IteratorType = TR.get();
+    }
+
+    // Parse identifier.
+    IdentifierInfo *II = nullptr;
+    SourceLocation IdLoc;
+    if (Tok.is(tok::identifier)) {
+      II = Tok.getIdentifierInfo();
+      IdLoc = ConsumeToken();
+    } else {
+      Diag(Tok, diag::err_expected_unqualified_id) << 0;
+    }
+
+    // Parse '='.
+    SourceLocation AssignLoc;
+    if (Tok.is(tok::equal))
+      AssignLoc = ConsumeToken();
+    else
+      Diag(Tok, diag::err_omp_expected_equal_in_iterator);
+
+    // Parse range-specification - <begin> ':' <end> [ ':' <step> ]
+    ColonProtectionRAIIObject ColonRAII(*this);
+    // Parse <begin>
+    SourceLocation Loc = Tok.getLocation();
+    ExprResult LHS = ParseCastExpression(AnyCastExpr);
+    ExprResult Begin = Actions.CorrectDelayedTyposInExpr(
+        ParseRHSOfBinaryExpression(LHS, prec::Conditional));
+    Begin = Actions.ActOnFinishFullExpr(Begin.get(), Loc,
+                                        /*DiscardedValue=*/false);
+    // Parse ':'.
+    SourceLocation ColonLoc;
+    if (Tok.is(tok::colon))
+      ColonLoc = ConsumeToken();
+
+    // Parse <end>
+    Loc = Tok.getLocation();
+    LHS = ParseCastExpression(AnyCastExpr);
+    ExprResult End = Actions.CorrectDelayedTyposInExpr(
+        ParseRHSOfBinaryExpression(LHS, prec::Conditional));
+    End = Actions.ActOnFinishFullExpr(End.get(), Loc,
+                                      /*DiscardedValue=*/false);
+
+    SourceLocation SecColonLoc;
+    ExprResult Step;
+    // Parse optional step.
+    if (Tok.is(tok::colon)) {
+      // Parse ':'
+      SecColonLoc = ConsumeToken();
+      // Parse <step>
+      Loc = Tok.getLocation();
+      LHS = ParseCastExpression(AnyCastExpr);
+      Step = Actions.CorrectDelayedTyposInExpr(
+          ParseRHSOfBinaryExpression(LHS, prec::Conditional));
+      Step = Actions.ActOnFinishFullExpr(Step.get(), Loc,
+                                         /*DiscardedValue=*/false);
+    }
+
+    // Parse ',' or ')'
+    if (Tok.isNot(tok::comma) && Tok.isNot(tok::r_paren))
+      Diag(Tok, diag::err_omp_expected_punc_after_iterator);
+    if (Tok.is(tok::comma))
+      ConsumeToken();
+
+    Sema::OMPIteratorData &D = Data.emplace_back();
+    D.DeclIdent = II;
+    D.DeclIdentLoc = IdLoc;
+    D.Type = IteratorType;
+    D.AssignLoc = AssignLoc;
+    D.ColonLoc = ColonLoc;
+    D.SecColonLoc = SecColonLoc;
+    D.Range.Begin = Begin.get();
+    D.Range.End = End.get();
+    D.Range.Step = Step.get();
+  }
+
+  // Parse ')'.
+  SourceLocation RLoc = Tok.getLocation();
+  if (!T.consumeClose())
+    RLoc = T.getCloseLocation();
+
+  return Actions.ActOnOMPIteratorExpr(getCurScope(), IteratorKwLoc, LLoc, RLoc,
+                                      Data);
+}
+
 /// Parses clauses with list.
 bool Parser::ParseOpenMPVarList(OpenMPDirectiveKind DKind,
                                 OpenMPClauseKind Kind,
@@ -3069,6 +3178,7 @@ bool Parser::ParseOpenMPVarList(OpenMPDirectiveKind DKind,
                          getOpenMPClauseName(Kind)))
     return true;
 
+  bool DependWithIterator = false;
   bool NeedRParenForLinear = false;
   BalancedDelimiterTracker LinearT(*this, tok::l_paren,
                                   tok::annot_pragma_openmp_end);
@@ -3106,6 +3216,22 @@ bool Parser::ParseOpenMPVarList(OpenMPDirectiveKind DKind,
       Data.ReductionOrMapperId =
           Actions.GetNameFromUnqualifiedId(UnqualifiedReductionId);
   } else if (Kind == OMPC_depend) {
+    if (getLangOpts().OpenMP >= 50) {
+      if (Tok.is(tok::identifier) && PP.getSpelling(Tok) == "iterator") {
+        // Handle optional dependence modifier.
+        // iterator(iterators-definition)
+        // where iterators-definition is iterator-specifier [,
+        // iterators-definition ]
+        // where iterator-specifier is [ iterator-type ] identifier =
+        // range-specification
+        DependWithIterator = true;
+        EnterScope(Scope::OpenMPDirectiveScope | Scope::DeclScope);
+        ExprResult IteratorRes = ParseOpenMPIteratorsExpr();
+        Data.DepModOrTailExpr = IteratorRes.get();
+        // Parse ','
+        ExpectAndConsume(tok::comma);
+      }
+    }
     // Handle dependency type for depend clause.
     ColonProtectionRAIIObject ColonRAII(*this);
     Data.ExtraModifier = getOpenMPSimpleClauseType(
@@ -3227,7 +3353,7 @@ bool Parser::ParseOpenMPVarList(OpenMPDirectiveKind DKind,
                                        /*DiscardedValue=*/false);
     if (Tail.isUsable()) {
       if (Tok.is(tok::colon)) {
-        Data.TailExpr = Tail.get();
+        Data.DepModOrTailExpr = Tail.get();
         Data.ColonLoc = ConsumeToken();
         TPA.Commit();
       } else {
@@ -3253,6 +3379,7 @@ bool Parser::ParseOpenMPVarList(OpenMPDirectiveKind DKind,
   const bool MayHaveTail = (Kind == OMPC_linear || Kind == OMPC_aligned);
   while (IsComma || (Tok.isNot(tok::r_paren) && Tok.isNot(tok::colon) &&
                      Tok.isNot(tok::annot_pragma_openmp_end))) {
+    ParseScope OMPListScope(this, Scope::OpenMPDirectiveScope);
     ColonProtectionRAIIObject ColonRAII(*this, MayHaveTail);
     // Parse variable
     ExprResult VarExpr =
@@ -3289,7 +3416,7 @@ bool Parser::ParseOpenMPVarList(OpenMPDirectiveKind DKind,
     Tail =
         Actions.ActOnFinishFullExpr(Tail.get(), ELoc, /*DiscardedValue*/ false);
     if (Tail.isUsable())
-      Data.TailExpr = Tail.get();
+      Data.DepModOrTailExpr = Tail.get();
     else
       SkipUntil(tok::comma, tok::r_paren, tok::annot_pragma_openmp_end,
                 StopBeforeMatch);
@@ -3299,8 +3426,11 @@ bool Parser::ParseOpenMPVarList(OpenMPDirectiveKind DKind,
   Data.RLoc = Tok.getLocation();
   if (!T.consumeClose())
     Data.RLoc = T.getCloseLocation();
+  // Exit from scope when the iterator is used in depend clause.
+  if (DependWithIterator)
+    ExitScope();
   return (Kind != OMPC_depend && Kind != OMPC_map && Vars.empty()) ||
-         (MustHaveTail && !Data.TailExpr) || InvalidReductionId ||
+         (MustHaveTail && !Data.DepModOrTailExpr) || InvalidReductionId ||
          IsInvalidMapperModifier;
 }
 
@@ -3372,7 +3502,7 @@ OMPClause *Parser::ParseOpenMPVarListClause(OpenMPDirectiveKind DKind,
     return nullptr;
   OMPVarListLocTy Locs(Loc, LOpen, Data.RLoc);
   return Actions.ActOnOpenMPVarListClause(
-      Kind, Vars, Data.TailExpr, Locs, Data.ColonLoc,
+      Kind, Vars, Data.DepModOrTailExpr, Locs, Data.ColonLoc,
       Data.ReductionOrMapperIdScopeSpec, Data.ReductionOrMapperId,
       Data.ExtraModifier, Data.MapTypeModifiers, Data.MapTypeModifiersLoc,
       Data.IsMapTypeImplicit, Data.ExtraModifierLoc);

diff  --git a/clang/lib/Sema/SemaExceptionSpec.cpp b/clang/lib/Sema/SemaExceptionSpec.cpp
index fad2ae1cc066..0dc0c68205fb 100644
--- a/clang/lib/Sema/SemaExceptionSpec.cpp
+++ b/clang/lib/Sema/SemaExceptionSpec.cpp
@@ -1300,6 +1300,7 @@ CanThrowResult Sema::canThrow(const Stmt *S) {
   case Expr::ArraySubscriptExprClass:
   case Expr::OMPArraySectionExprClass:
   case Expr::OMPArrayShapingExprClass:
+  case Expr::OMPIteratorExprClass:
   case Expr::BinaryOperatorClass:
   case Expr::DependentCoawaitExprClass:
   case Expr::CompoundAssignOperatorClass:

diff  --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index c0f8600aa0cc..8d0e97c85771 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -4873,6 +4873,131 @@ ExprResult Sema::ActOnOMPArrayShapingExpr(Expr *Base, SourceLocation LParenLoc,
                                      LParenLoc, RParenLoc, NewDims, Brackets);
 }
 
+ExprResult Sema::ActOnOMPIteratorExpr(Scope *S, SourceLocation IteratorKwLoc,
+                                      SourceLocation LLoc, SourceLocation RLoc,
+                                      ArrayRef<OMPIteratorData> Data) {
+  SmallVector<OMPIteratorExpr::IteratorDefinition, 4> ID;
+  bool IsCorrect = true;
+  for (const OMPIteratorData &D : Data) {
+    TypeSourceInfo *TInfo = nullptr;
+    SourceLocation StartLoc;
+    QualType DeclTy;
+    if (!D.Type.getAsOpaquePtr()) {
+      // OpenMP 5.0, 2.1.6 Iterators
+      // In an iterator-specifier, if the iterator-type is not specified then
+      // the type of that iterator is of int type.
+      DeclTy = Context.IntTy;
+      StartLoc = D.DeclIdentLoc;
+    } else {
+      DeclTy = GetTypeFromParser(D.Type, &TInfo);
+      StartLoc = TInfo->getTypeLoc().getBeginLoc();
+    }
+
+    bool IsDeclTyDependent = DeclTy->isDependentType() ||
+                             DeclTy->containsUnexpandedParameterPack() ||
+                             DeclTy->isInstantiationDependentType();
+    if (!IsDeclTyDependent) {
+      if (!DeclTy->isIntegralType(Context) && !DeclTy->isAnyPointerType()) {
+        // OpenMP 5.0, 2.1.6 Iterators, Restrictions, C/C++
+        // The iterator-type must be an integral or pointer type.
+        Diag(StartLoc, diag::err_omp_iterator_not_integral_or_pointer)
+            << DeclTy;
+        IsCorrect = false;
+        continue;
+      }
+      if (DeclTy.isConstant(Context)) {
+        // OpenMP 5.0, 2.1.6 Iterators, Restrictions, C/C++
+        // The iterator-type must not be const qualified.
+        Diag(StartLoc, diag::err_omp_iterator_not_integral_or_pointer)
+            << DeclTy;
+        IsCorrect = false;
+        continue;
+      }
+    }
+
+    // Iterator declaration.
+    assert(D.DeclIdent && "Identifier expected.");
+    // Always try to create iterator declarator to avoid extra error messages
+    // about unknown declarations use.
+    auto *VD = VarDecl::Create(Context, CurContext, StartLoc, D.DeclIdentLoc,
+                               D.DeclIdent, DeclTy, TInfo, SC_None);
+    VD->setImplicit();
+    if (S) {
+      // Check for conflicting previous declaration.
+      DeclarationNameInfo NameInfo(VD->getDeclName(), D.DeclIdentLoc);
+      LookupResult Previous(*this, NameInfo, LookupOrdinaryName,
+                            ForVisibleRedeclaration);
+      Previous.suppressDiagnostics();
+      LookupName(Previous, S);
+
+      FilterLookupForScope(Previous, CurContext, S, /*ConsiderLinkage=*/false,
+                           /*AllowInlineNamespace=*/false);
+      if (!Previous.empty()) {
+        NamedDecl *Old = Previous.getRepresentativeDecl();
+        Diag(D.DeclIdentLoc, diag::err_redefinition) << VD->getDeclName();
+        Diag(Old->getLocation(), diag::note_previous_definition);
+      } else {
+        PushOnScopeChains(VD, S);
+      }
+    } else {
+      CurContext->addDecl(VD);
+    }
+    Expr *Begin = D.Range.Begin;
+    if (!IsDeclTyDependent && Begin && !Begin->isTypeDependent()) {
+      ExprResult BeginRes =
+          PerformImplicitConversion(Begin, DeclTy, AA_Converting);
+      Begin = BeginRes.get();
+    }
+    Expr *End = D.Range.End;
+    if (!IsDeclTyDependent && End && !End->isTypeDependent()) {
+      ExprResult EndRes = PerformImplicitConversion(End, DeclTy, AA_Converting);
+      End = EndRes.get();
+    }
+    Expr *Step = D.Range.Step;
+    if (!IsDeclTyDependent && Step && !Step->isTypeDependent()) {
+      if (!Step->getType()->isIntegralType(Context)) {
+        Diag(Step->getExprLoc(), diag::err_omp_iterator_step_not_integral)
+            << Step << Step->getSourceRange();
+        IsCorrect = false;
+        continue;
+      }
+      llvm::APSInt Result;
+      bool IsConstant = Step->isIntegerConstantExpr(Result, Context);
+      // OpenMP 5.0, 2.1.6 Iterators, Restrictions
+      // If the step expression of a range-specification equals zero, the
+      // behavior is unspecified.
+      if (IsConstant && Result.isNullValue()) {
+        Diag(Step->getExprLoc(), diag::err_omp_iterator_step_constant_zero)
+            << Step << Step->getSourceRange();
+        IsCorrect = false;
+        continue;
+      }
+    }
+    if (!Begin || !End || !IsCorrect) {
+      IsCorrect = false;
+      continue;
+    }
+    OMPIteratorExpr::IteratorDefinition &IDElem = ID.emplace_back();
+    IDElem.IteratorDecl = VD;
+    IDElem.AssignmentLoc = D.AssignLoc;
+    IDElem.Range.Begin = Begin;
+    IDElem.Range.End = End;
+    IDElem.Range.Step = Step;
+    IDElem.ColonLoc = D.ColonLoc;
+    IDElem.SecondColonLoc = D.SecColonLoc;
+  }
+  if (!IsCorrect) {
+    // Invalidate all created iterator declarations if error is found.
+    for (const OMPIteratorExpr::IteratorDefinition &D : ID) {
+      if (Decl *ID = D.IteratorDecl)
+        ID->setInvalidDecl();
+    }
+    return ExprError();
+  }
+  return OMPIteratorExpr::Create(Context, Context.OMPIteratorTy, IteratorKwLoc,
+                                 LLoc, RLoc, ID);
+}
+
 ExprResult
 Sema::CreateBuiltinArraySubscriptExpr(Expr *Base, SourceLocation LLoc,
                                       Expr *Idx, SourceLocation RLoc) {
@@ -5634,6 +5759,7 @@ static bool isPlaceholderToRemoveAsArg(QualType type) {
   case BuiltinType::BuiltinFn:
   case BuiltinType::OMPArraySection:
   case BuiltinType::OMPArrayShaping:
+  case BuiltinType::OMPIterator:
     return true;
 
   }
@@ -18513,6 +18639,9 @@ ExprResult Sema::CheckPlaceholderExpr(Expr *E) {
   case BuiltinType::OMPArrayShaping:
     return ExprError(Diag(E->getBeginLoc(), diag::err_omp_array_shaping_use));
 
+  case BuiltinType::OMPIterator:
+    return ExprError(Diag(E->getBeginLoc(), diag::err_omp_iterator_use));
+
   // Everything else should be impossible.
 #define IMAGE_TYPE(ImgType, Id, SingletonId, Access, Suffix) \
   case BuiltinType::Id:

diff  --git a/clang/lib/Sema/SemaOpenMP.cpp b/clang/lib/Sema/SemaOpenMP.cpp
index 7d2ae172fe4d..df56c3be43fc 100644
--- a/clang/lib/Sema/SemaOpenMP.cpp
+++ b/clang/lib/Sema/SemaOpenMP.cpp
@@ -13053,7 +13053,7 @@ OMPClause *Sema::ActOnOpenMPDestroyClause(SourceLocation StartLoc,
 }
 
 OMPClause *Sema::ActOnOpenMPVarListClause(
-    OpenMPClauseKind Kind, ArrayRef<Expr *> VarList, Expr *TailExpr,
+    OpenMPClauseKind Kind, ArrayRef<Expr *> VarList, Expr *DepModOrTailExpr,
     const OMPVarListLocTy &Locs, SourceLocation ColonLoc,
     CXXScopeSpec &ReductionOrMapperIdScopeSpec,
     DeclarationNameInfo &ReductionOrMapperId, int ExtraModifier,
@@ -13103,13 +13103,13 @@ OMPClause *Sema::ActOnOpenMPVarListClause(
     assert(0 <= ExtraModifier && ExtraModifier <= OMPC_LINEAR_unknown &&
            "Unexpected linear modifier.");
     Res = ActOnOpenMPLinearClause(
-        VarList, TailExpr, StartLoc, LParenLoc,
+        VarList, DepModOrTailExpr, StartLoc, LParenLoc,
         static_cast<OpenMPLinearClauseKind>(ExtraModifier), ExtraModifierLoc,
         ColonLoc, EndLoc);
     break;
   case OMPC_aligned:
-    Res = ActOnOpenMPAlignedClause(VarList, TailExpr, StartLoc, LParenLoc,
-                                   ColonLoc, EndLoc);
+    Res = ActOnOpenMPAlignedClause(VarList, DepModOrTailExpr, StartLoc,
+                                   LParenLoc, ColonLoc, EndLoc);
     break;
   case OMPC_copyin:
     Res = ActOnOpenMPCopyinClause(VarList, StartLoc, LParenLoc, EndLoc);
@@ -13124,8 +13124,8 @@ OMPClause *Sema::ActOnOpenMPVarListClause(
     assert(0 <= ExtraModifier && ExtraModifier <= OMPC_DEPEND_unknown &&
            "Unexpected depend modifier.");
     Res = ActOnOpenMPDependClause(
-        static_cast<OpenMPDependClauseKind>(ExtraModifier), ExtraModifierLoc,
-        ColonLoc, VarList, StartLoc, LParenLoc, EndLoc);
+        DepModOrTailExpr, static_cast<OpenMPDependClauseKind>(ExtraModifier),
+        ExtraModifierLoc, ColonLoc, VarList, StartLoc, LParenLoc, EndLoc);
     break;
   case OMPC_map:
     assert(0 <= ExtraModifier && ExtraModifier <= OMPC_MAP_unknown &&
@@ -13150,8 +13150,8 @@ OMPClause *Sema::ActOnOpenMPVarListClause(
     Res = ActOnOpenMPIsDevicePtrClause(VarList, Locs);
     break;
   case OMPC_allocate:
-    Res = ActOnOpenMPAllocateClause(TailExpr, VarList, StartLoc, LParenLoc,
-                                    ColonLoc, EndLoc);
+    Res = ActOnOpenMPAllocateClause(DepModOrTailExpr, VarList, StartLoc,
+                                    LParenLoc, ColonLoc, EndLoc);
     break;
   case OMPC_nontemporal:
     Res = ActOnOpenMPNontemporalClause(VarList, StartLoc, LParenLoc, EndLoc);
@@ -15642,7 +15642,7 @@ OMPClause *Sema::ActOnOpenMPDepobjClause(Expr *Depobj, SourceLocation StartLoc,
 }
 
 OMPClause *
-Sema::ActOnOpenMPDependClause(OpenMPDependClauseKind DepKind,
+Sema::ActOnOpenMPDependClause(Expr *DepModifier, OpenMPDependClauseKind DepKind,
                               SourceLocation DepLoc, SourceLocation ColonLoc,
                               ArrayRef<Expr *> VarList, SourceLocation StartLoc,
                               SourceLocation LParenLoc, SourceLocation EndLoc) {
@@ -15664,12 +15664,26 @@ Sema::ActOnOpenMPDependClause(OpenMPDependClauseKind DepKind,
     Except.push_back(OMPC_DEPEND_sink);
     if (LangOpts.OpenMP < 50 || DSAStack->getCurrentDirective() == OMPD_depobj)
       Except.push_back(OMPC_DEPEND_depobj);
+    std::string Expected = (LangOpts.OpenMP >= 50 && !DepModifier)
+                               ? "depend modifier(iterator) or "
+                               : "";
     Diag(DepLoc, diag::err_omp_unexpected_clause_value)
-        << getListOfPossibleValues(OMPC_depend, /*First=*/0,
-                                   /*Last=*/OMPC_DEPEND_unknown, Except)
+        << Expected + getListOfPossibleValues(OMPC_depend, /*First=*/0,
+                                              /*Last=*/OMPC_DEPEND_unknown,
+                                              Except)
         << getOpenMPClauseName(OMPC_depend);
     return nullptr;
   }
+  if (DepModifier &&
+      (DepKind == OMPC_DEPEND_source || DepKind == OMPC_DEPEND_sink)) {
+    Diag(DepModifier->getExprLoc(),
+         diag::err_omp_depend_sink_source_with_modifier);
+    return nullptr;
+  }
+  if (DepModifier &&
+      !DepModifier->getType()->isSpecificBuiltinType(BuiltinType::OMPIterator))
+    Diag(DepModifier->getExprLoc(), diag::err_omp_depend_modifier_not_iterator);
+
   SmallVector<Expr *, 8> Vars;
   DSAStackTy::OperatorOffsetTy OpsOffs;
   llvm::APSInt DepCounter(/*BitWidth=*/32);
@@ -15878,8 +15892,8 @@ Sema::ActOnOpenMPDependClause(OpenMPDependClauseKind DepKind,
     return nullptr;
 
   auto *C = OMPDependClause::Create(Context, StartLoc, LParenLoc, EndLoc,
-                                    DepKind, DepLoc, ColonLoc, Vars,
-                                    TotalDepCount.getZExtValue());
+                                    DepModifier, DepKind, DepLoc, ColonLoc,
+                                    Vars, TotalDepCount.getZExtValue());
   if ((DepKind == OMPC_DEPEND_sink || DepKind == OMPC_DEPEND_source) &&
       DSAStack->isParentOrderedRegion())
     DSAStack->addDoacrossDependClause(C, OpsOffs);

diff  --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h
index 82cfa246e3f7..de05d436d3b9 100644
--- a/clang/lib/Sema/TreeTransform.h
+++ b/clang/lib/Sema/TreeTransform.h
@@ -1842,12 +1842,13 @@ class TreeTransform {
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide 
diff erent behavior.
   OMPClause *
-  RebuildOMPDependClause(OpenMPDependClauseKind DepKind, SourceLocation DepLoc,
-                         SourceLocation ColonLoc, ArrayRef<Expr *> VarList,
-                         SourceLocation StartLoc, SourceLocation LParenLoc,
-                         SourceLocation EndLoc) {
-    return getSema().ActOnOpenMPDependClause(DepKind, DepLoc, ColonLoc, VarList,
-                                             StartLoc, LParenLoc, EndLoc);
+  RebuildOMPDependClause(Expr *DepModifier, OpenMPDependClauseKind DepKind,
+                         SourceLocation DepLoc, SourceLocation ColonLoc,
+                         ArrayRef<Expr *> VarList, SourceLocation StartLoc,
+                         SourceLocation LParenLoc, SourceLocation EndLoc) {
+    return getSema().ActOnOpenMPDependClause(DepModifier, DepKind, DepLoc,
+                                             ColonLoc, VarList, StartLoc,
+                                             LParenLoc, EndLoc);
   }
 
   /// Build a new OpenMP 'device' clause.
@@ -2391,6 +2392,17 @@ class TreeTransform {
                                               BracketsRanges);
   }
 
+  /// Build a new iterator expression.
+  ///
+  /// By default, performs semantic analysis to build the new expression.
+  /// Subclasses may override this routine to provide 
diff erent behavior.
+  ExprResult RebuildOMPIteratorExpr(
+      SourceLocation IteratorKwLoc, SourceLocation LLoc, SourceLocation RLoc,
+      ArrayRef<Sema::OMPIteratorData> Data) {
+    return getSema().ActOnOMPIteratorExpr(/*Scope=*/nullptr, IteratorKwLoc,
+                                          LLoc, RLoc, Data);
+  }
+
   /// Build a new call expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
@@ -9291,6 +9303,13 @@ template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPDependClause(OMPDependClause *C) {
   llvm::SmallVector<Expr *, 16> Vars;
+  Expr *DepModifier = C->getModifier();
+  if (DepModifier) {
+    ExprResult DepModRes = getDerived().TransformExpr(DepModifier);
+    if (DepModRes.isInvalid())
+      return nullptr;
+    DepModifier = DepModRes.get();
+  }
   Vars.reserve(C->varlist_size());
   for (auto *VE : C->varlists()) {
     ExprResult EVar = getDerived().TransformExpr(cast<Expr>(VE));
@@ -9299,8 +9318,9 @@ TreeTransform<Derived>::TransformOMPDependClause(OMPDependClause *C) {
     Vars.push_back(EVar.get());
   }
   return getDerived().RebuildOMPDependClause(
-      C->getDependencyKind(), C->getDependencyLoc(), C->getColonLoc(), Vars,
-      C->getBeginLoc(), C->getLParenLoc(), C->getEndLoc());
+      DepModifier, C->getDependencyKind(), C->getDependencyLoc(),
+      C->getColonLoc(), Vars, C->getBeginLoc(), C->getLParenLoc(),
+      C->getEndLoc());
 }
 
 template <typename Derived>
@@ -10054,6 +10074,65 @@ TreeTransform<Derived>::TransformOMPArrayShapingExpr(OMPArrayShapingExpr *E) {
                                                  E->getBracketsRanges());
 }
 
+template <typename Derived>
+ExprResult
+TreeTransform<Derived>::TransformOMPIteratorExpr(OMPIteratorExpr *E) {
+  unsigned NumIterators = E->numOfIterators();
+  SmallVector<Sema::OMPIteratorData, 4> Data(NumIterators);
+
+  bool ErrorFound = false;
+  bool NeedToRebuild = getDerived().AlwaysRebuild();
+  for (unsigned I = 0; I < NumIterators; ++I) {
+    auto *D = cast<VarDecl>(E->getIteratorDecl(I));
+    Data[I].DeclIdent = D->getIdentifier();
+    Data[I].DeclIdentLoc = D->getLocation();
+    if (D->getLocation() == D->getBeginLoc()) {
+      assert(SemaRef.Context.hasSameType(D->getType(), SemaRef.Context.IntTy) &&
+             "Implicit type must be int.");
+    } else {
+      TypeSourceInfo *TSI = getDerived().TransformType(D->getTypeSourceInfo());
+      QualType DeclTy = getDerived().TransformType(D->getType());
+      Data[I].Type = SemaRef.CreateParsedType(DeclTy, TSI);
+    }
+    OMPIteratorExpr::IteratorRange Range = E->getIteratorRange(I);
+    ExprResult Begin = getDerived().TransformExpr(Range.Begin);
+    ExprResult End = getDerived().TransformExpr(Range.End);
+    ExprResult Step = getDerived().TransformExpr(Range.Step);
+    ErrorFound = ErrorFound ||
+                 !(!D->getTypeSourceInfo() || (Data[I].Type.getAsOpaquePtr() &&
+                                               !Data[I].Type.get().isNull())) ||
+                 Begin.isInvalid() || End.isInvalid() || Step.isInvalid();
+    if (ErrorFound)
+      continue;
+    Data[I].Range.Begin = Begin.get();
+    Data[I].Range.End = End.get();
+    Data[I].Range.Step = Step.get();
+    Data[I].AssignLoc = E->getAssignLoc(I);
+    Data[I].ColonLoc = E->getColonLoc(I);
+    Data[I].SecColonLoc = E->getSecondColonLoc(I);
+    NeedToRebuild =
+        NeedToRebuild ||
+        (D->getTypeSourceInfo() && Data[I].Type.get().getTypePtrOrNull() !=
+                                       D->getType().getTypePtrOrNull()) ||
+        Range.Begin != Data[I].Range.Begin || Range.End != Data[I].Range.End ||
+        Range.Step != Data[I].Range.Step;
+  }
+  if (ErrorFound)
+    return ExprError();
+  if (!NeedToRebuild)
+    return E;
+
+  ExprResult Res = getDerived().RebuildOMPIteratorExpr(
+      E->getIteratorKwLoc(), E->getLParenLoc(), E->getRParenLoc(), Data);
+  if (!Res.isUsable())
+    return Res;
+  auto *IE = cast<OMPIteratorExpr>(Res.get());
+  for (unsigned I = 0; I < NumIterators; ++I)
+    getDerived().transformedLocalDecl(E->getIteratorDecl(I),
+                                      IE->getIteratorDecl(I));
+  return Res;
+}
+
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformCallExpr(CallExpr *E) {

diff  --git a/clang/lib/Serialization/ASTCommon.cpp b/clang/lib/Serialization/ASTCommon.cpp
index 158a12f0329d..566bda2d71f7 100644
--- a/clang/lib/Serialization/ASTCommon.cpp
+++ b/clang/lib/Serialization/ASTCommon.cpp
@@ -246,6 +246,9 @@ serialization::TypeIdxFromBuiltin(const BuiltinType *BT) {
   case BuiltinType::OMPArrayShaping:
     ID = PREDEF_TYPE_OMP_ARRAY_SHAPING;
     break;
+  case BuiltinType::OMPIterator:
+    ID = PREDEF_TYPE_OMP_ITERATOR;
+    break;
   }
 
   return TypeIdx(ID);

diff  --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index bea9bdd22bab..74bb1c7f87dc 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -6960,6 +6960,9 @@ QualType ASTReader::GetType(TypeID ID) {
     case PREDEF_TYPE_OMP_ARRAY_SHAPING:
       T = Context.OMPArraySectionTy;
       break;
+    case PREDEF_TYPE_OMP_ITERATOR:
+      T = Context.OMPIteratorTy;
+      break;
 #define SVE_TYPE(Name, Id, SingletonId) \
     case PREDEF_TYPE_##Id##_ID: \
       T = Context.SingletonId; \
@@ -12307,6 +12310,7 @@ void OMPClauseReader::VisitOMPDepobjClause(OMPDepobjClause *C) {
 
 void OMPClauseReader::VisitOMPDependClause(OMPDependClause *C) {
   C->setLParenLoc(Record.readSourceLocation());
+  C->setModifier(Record.readSubExpr());
   C->setDependencyKind(
       static_cast<OpenMPDependClauseKind>(Record.readInt()));
   C->setDependencyLoc(Record.readSourceLocation());

diff  --git a/clang/lib/Serialization/ASTReaderStmt.cpp b/clang/lib/Serialization/ASTReaderStmt.cpp
index bc8c231731e8..2c915659ad7c 100644
--- a/clang/lib/Serialization/ASTReaderStmt.cpp
+++ b/clang/lib/Serialization/ASTReaderStmt.cpp
@@ -927,6 +927,26 @@ void ASTStmtReader::VisitOMPArrayShapingExpr(OMPArrayShapingExpr *E) {
   E->setRParenLoc(readSourceLocation());
 }
 
+void ASTStmtReader::VisitOMPIteratorExpr(OMPIteratorExpr *E) {
+  VisitExpr(E);
+  unsigned NumIters = Record.readInt();
+  E->setIteratorKwLoc(readSourceLocation());
+  E->setLParenLoc(readSourceLocation());
+  E->setRParenLoc(readSourceLocation());
+  for (unsigned I = 0; I < NumIters; ++I) {
+    E->setIteratorDeclaration(I, Record.readDeclRef());
+    E->setAssignmentLoc(I, readSourceLocation());
+    Expr *Begin = Record.readSubExpr();
+    Expr *End = Record.readSubExpr();
+    Expr *Step = Record.readSubExpr();
+    SourceLocation ColonLoc = readSourceLocation();
+    SourceLocation SecColonLoc;
+    if (Step)
+      SecColonLoc = readSourceLocation();
+    E->setIteratorRange(I, Begin, ColonLoc, End, SecColonLoc, Step);
+  }
+}
+
 void ASTStmtReader::VisitCallExpr(CallExpr *E) {
   VisitExpr(E);
   unsigned NumArgs = Record.readInt();
@@ -2887,6 +2907,11 @@ Stmt *ASTReader::ReadStmtFromStream(ModuleFile &F) {
           Context, Record[ASTStmtReader::NumExprFields]);
       break;
 
+    case EXPR_OMP_ITERATOR:
+      S = OMPIteratorExpr::CreateEmpty(Context,
+                                       Record[ASTStmtReader::NumExprFields]);
+      break;
+
     case EXPR_CALL:
       S = CallExpr::CreateEmpty(
           Context, /*NumArgs=*/Record[ASTStmtReader::NumExprFields], Empty);

diff  --git a/clang/lib/Serialization/ASTWriter.cpp b/clang/lib/Serialization/ASTWriter.cpp
index f7c58ed11d9f..27f44a706f9f 100644
--- a/clang/lib/Serialization/ASTWriter.cpp
+++ b/clang/lib/Serialization/ASTWriter.cpp
@@ -6379,6 +6379,7 @@ void OMPClauseWriter::VisitOMPDependClause(OMPDependClause *C) {
   Record.push_back(C->varlist_size());
   Record.push_back(C->getNumLoops());
   Record.AddSourceLocation(C->getLParenLoc());
+  Record.AddStmt(C->getModifier());
   Record.push_back(C->getDependencyKind());
   Record.AddSourceLocation(C->getDependencyLoc());
   Record.AddSourceLocation(C->getColonLoc());

diff  --git a/clang/lib/Serialization/ASTWriterStmt.cpp b/clang/lib/Serialization/ASTWriterStmt.cpp
index 840823298be7..ee8bb3e1d462 100644
--- a/clang/lib/Serialization/ASTWriterStmt.cpp
+++ b/clang/lib/Serialization/ASTWriterStmt.cpp
@@ -787,6 +787,26 @@ void ASTStmtWriter::VisitOMPArrayShapingExpr(OMPArrayShapingExpr *E) {
   Code = serialization::EXPR_OMP_ARRAY_SHAPING;
 }
 
+void ASTStmtWriter::VisitOMPIteratorExpr(OMPIteratorExpr *E) {
+  VisitExpr(E);
+  Record.push_back(E->numOfIterators());
+  Record.AddSourceLocation(E->getIteratorKwLoc());
+  Record.AddSourceLocation(E->getLParenLoc());
+  Record.AddSourceLocation(E->getRParenLoc());
+  for (unsigned I = 0, End = E->numOfIterators(); I < End; ++I) {
+    Record.AddDeclRef(E->getIteratorDecl(I));
+    Record.AddSourceLocation(E->getAssignLoc(I));
+    OMPIteratorExpr::IteratorRange Range = E->getIteratorRange(I);
+    Record.AddStmt(Range.Begin);
+    Record.AddStmt(Range.End);
+    Record.AddStmt(Range.Step);
+    Record.AddSourceLocation(E->getColonLoc(I));
+    if (Range.Step)
+      Record.AddSourceLocation(E->getSecondColonLoc(I));
+  }
+  Code = serialization::EXPR_OMP_ITERATOR;
+}
+
 void ASTStmtWriter::VisitCallExpr(CallExpr *E) {
   VisitExpr(E);
   Record.push_back(E->getNumArgs());

diff  --git a/clang/lib/StaticAnalyzer/Checkers/IdenticalExprChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/IdenticalExprChecker.cpp
index d16410a19b97..1cf81b54e77d 100644
--- a/clang/lib/StaticAnalyzer/Checkers/IdenticalExprChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/IdenticalExprChecker.cpp
@@ -352,6 +352,7 @@ static bool isIdenticalStmt(const ASTContext &Ctx, const Stmt *Stmt1,
   case Stmt::ArraySubscriptExprClass:
   case Stmt::OMPArraySectionExprClass:
   case Stmt::OMPArrayShapingExprClass:
+  case Stmt::OMPIteratorExprClass:
   case Stmt::ImplicitCastExprClass:
   case Stmt::ParenExprClass:
   case Stmt::BreakStmtClass:

diff  --git a/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp b/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp
index 4c0914628a0d..1f0d89d59120 100644
--- a/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp
+++ b/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp
@@ -1414,6 +1414,7 @@ void ExprEngine::Visit(const Stmt *S, ExplodedNode *Pred,
     case Stmt::CXXNullPtrLiteralExprClass:
     case Stmt::OMPArraySectionExprClass:
     case Stmt::OMPArrayShapingExprClass:
+    case Stmt::OMPIteratorExprClass:
     case Stmt::TypeTraitExprClass: {
       Bldr.takeNodes(Pred);
       ExplodedNodeSet preVisit;

diff  --git a/clang/test/OpenMP/depobj_messages.cpp b/clang/test/OpenMP/depobj_messages.cpp
index a33b16f985a0..1b20b1c525e7 100644
--- a/clang/test/OpenMP/depobj_messages.cpp
+++ b/clang/test/OpenMP/depobj_messages.cpp
@@ -142,7 +142,7 @@ label1 : {
 #pragma omp parallel depobj(argc) // expected-warning {{extra tokens at the end of '#pragma omp parallel' are ignored}}
   ;
 #pragma omp depobj(x) seq_cst // expected-error {{unexpected OpenMP clause 'seq_cst' in directive '#pragma omp depobj'}}
-#pragma omp depobj(x) depend(source: x) // expected-error {{expected 'in', 'out', 'inout' or 'mutexinoutset' in OpenMP clause 'depend'}}
+#pragma omp depobj(x) depend(source: x) // expected-error {{expected depend modifier(iterator) or 'in', 'out', 'inout' or 'mutexinoutset' in OpenMP clause 'depend'}}
 #pragma omp depobj(x) update // expected-error {{expected '(' after 'update'}}
 #pragma omp depobj(x) update( // expected-error {{expected ')'}} expected-note {{to match this '('}} expected-error {{expected 'in', 'out', 'inout' or 'mutexinoutset' in OpenMP clause 'update'}}
 #pragma omp depobj(x) update(sink // expected-error {{expected ')'}} expected-note {{to match this '('}} expected-error {{expected 'in', 'out', 'inout' or 'mutexinoutset' in OpenMP clause 'update'}}

diff  --git a/clang/test/OpenMP/task_ast_print.cpp b/clang/test/OpenMP/task_ast_print.cpp
index 1da6c5045934..cc569a6aab84 100644
--- a/clang/test/OpenMP/task_ast_print.cpp
+++ b/clang/test/OpenMP/task_ast_print.cpp
@@ -26,7 +26,7 @@ struct S1 {
 template <typename T>
 class S7 : public T {
 protected:
-  T a, b;
+  T a, b, c[10], d[10];
   S7() : a(0) {}
 
 public:
@@ -34,7 +34,7 @@ class S7 : public T {
     omp_depend_t x;
     omp_event_handle_t evt;
 #pragma omp taskgroup allocate(b) task_reduction(+:b)
-#pragma omp task private(a) private(this->a) private(T::a) in_reduction(+:this->b) allocate(b) depend(depobj:x) detach(evt)
+#pragma omp task private(a) private(this->a) private(T::a) in_reduction(+:this->b) allocate(b) depend(depobj:x) detach(evt) depend(iterator(i=0:10:1, T *k = &a:&b), in: c[i], d[(int)(k-&a)])
     for (int k = 0; k < a.a; ++k)
       ++this->a.a;
   }
@@ -47,9 +47,9 @@ class S7 : public T {
 };
 
 // CHECK: #pragma omp taskgroup allocate(this->b) task_reduction(+: this->b)
-// CHECK: #pragma omp task private(this->a) private(this->a) private(T::a) in_reduction(+: this->b) allocate(this->b) depend(depobj : x) detach(evt){{$}}
+// CHECK: #pragma omp task private(this->a) private(this->a) private(T::a) in_reduction(+: this->b) allocate(this->b) depend(depobj : x) detach(evt) depend(iterator(int i = 0:10:1, T * k = &this->a:&this->b), in : this->c[i],this->d[(int)(k - &this->a)]){{$}}
 // CHECK: #pragma omp task private(this->a) private(this->a)
-// CHECK: #pragma omp task private(this->a) private(this->a) private(this->S1::a)
+// CHECK: #pragma omp task private(this->a) private(this->a) private(this->S1::a) in_reduction(+: this->b) allocate(this->b) depend(depobj : x) detach(evt) depend(iterator(int i = 0:10:1, S1 * k = &this->a:&this->b), in : this->c[i],this->d[(int)(k - &this->a)])
 
 class S8 : public S7<S1> {
   S8() {}
@@ -176,10 +176,10 @@ int main(int argc, char **argv) {
   // CHECK-NEXT: foo();
 #pragma omp taskgroup task_reduction(min: arr1)
 #pragma omp parallel reduction(+:arr1)
-#pragma omp task in_reduction(min: arr1)
+#pragma omp task in_reduction(min: arr1) depend(iterator(i=0:argc, unsigned j=argc:0:a), out: argv[i][j])
   // CHECK-NEXT: #pragma omp taskgroup task_reduction(min: arr1)
   // CHECK-NEXT: #pragma omp parallel reduction(+: arr1)
-  // CHECK-NEXT: #pragma omp task in_reduction(min: arr1)
+  // CHECK-NEXT: #pragma omp task in_reduction(min: arr1) depend(iterator(int i = 0:argc, unsigned int j = argc:0:a), out : argv[i][j])
   foo();
   // CHECK-NEXT: foo();
   // CHECK-NEXT: #pragma omp task in_reduction(+: arr1)

diff  --git a/clang/test/OpenMP/task_depend_messages.cpp b/clang/test/OpenMP/task_depend_messages.cpp
index f04c167cbdcc..bfb0e771b2ca 100644
--- a/clang/test/OpenMP/task_depend_messages.cpp
+++ b/clang/test/OpenMP/task_depend_messages.cpp
@@ -28,11 +28,11 @@ int main(int argc, char **argv, char *env[]) {
 
   #pragma omp task depend(in : arr[0])
   #pragma omp task depend // expected-error {{expected '(' after 'depend'}}
-  #pragma omp task depend ( // omp45-error {{expected 'in', 'out', 'inout' or 'mutexinoutset' in OpenMP clause 'depend'}} expected-error {{expected ')'}} expected-note {{to match this '('}} expected-warning {{missing ':' after dependency type - ignoring}} omp50-error {{expected 'in', 'out', 'inout', 'mutexinoutset' or 'depobj' in OpenMP clause 'depend'}}
-  #pragma omp task depend () // omp45-error {{expected 'in', 'out', 'inout' or 'mutexinoutset' in OpenMP clause 'depend'}} expected-warning {{missing ':' after dependency type - ignoring}} omp50-error {{expected 'in', 'out', 'inout', 'mutexinoutset' or 'depobj' in OpenMP clause 'depend'}}
-  #pragma omp task depend (argc // omp45-error {{expected 'in', 'out', 'inout' or 'mutexinoutset' in OpenMP clause 'depend'}} expected-warning {{missing ':' after dependency type - ignoring}} expected-error {{expected ')'}} expected-note {{to match this '('}} omp50-error {{expected 'in', 'out', 'inout', 'mutexinoutset' or 'depobj' in OpenMP clause 'depend'}}
-  #pragma omp task depend (source : argc) // omp45-error {{expected 'in', 'out', 'inout' or 'mutexinoutset' in OpenMP clause 'depend'}} omp50-error {{expected 'in', 'out', 'inout', 'mutexinoutset' or 'depobj' in OpenMP clause 'depend'}}
-  #pragma omp task depend (source) // expected-error {{expected expression}} expected-warning {{missing ':' after dependency type - ignoring}} omp45-error {{expected 'in', 'out', 'inout' or 'mutexinoutset' in OpenMP clause 'depend'}} omp50-error {{expected 'in', 'out', 'inout', 'mutexinoutset' or 'depobj' in OpenMP clause 'depend'}}
+  #pragma omp task depend ( // omp45-error {{expected 'in', 'out', 'inout' or 'mutexinoutset' in OpenMP clause 'depend'}} expected-error {{expected ')'}} expected-note {{to match this '('}} expected-warning {{missing ':' after dependency type - ignoring}} omp50-error {{expected depend modifier(iterator) or 'in', 'out', 'inout', 'mutexinoutset' or 'depobj' in OpenMP clause 'depend'}}
+  #pragma omp task depend () // omp45-error {{expected 'in', 'out', 'inout' or 'mutexinoutset' in OpenMP clause 'depend'}} expected-warning {{missing ':' after dependency type - ignoring}} omp50-error {{expected depend modifier(iterator) or 'in', 'out', 'inout', 'mutexinoutset' or 'depobj' in OpenMP clause 'depend'}}
+  #pragma omp task depend (argc // omp45-error {{expected 'in', 'out', 'inout' or 'mutexinoutset' in OpenMP clause 'depend'}} expected-warning {{missing ':' after dependency type - ignoring}} expected-error {{expected ')'}} expected-note {{to match this '('}} omp50-error {{expected depend modifier(iterator) or 'in', 'out', 'inout', 'mutexinoutset' or 'depobj' in OpenMP clause 'depend'}}
+  #pragma omp task depend (source : argc) // omp45-error {{expected 'in', 'out', 'inout' or 'mutexinoutset' in OpenMP clause 'depend'}} omp50-error {{expected depend modifier(iterator) or 'in', 'out', 'inout', 'mutexinoutset' or 'depobj' in OpenMP clause 'depend'}}
+  #pragma omp task depend (source) // expected-error {{expected expression}} expected-warning {{missing ':' after dependency type - ignoring}} omp45-error {{expected 'in', 'out', 'inout' or 'mutexinoutset' in OpenMP clause 'depend'}} omp50-error {{expected depend modifier(iterator) or 'in', 'out', 'inout', 'mutexinoutset' or 'depobj' in OpenMP clause 'depend'}}
   #pragma omp task depend (in : argc)) // expected-warning {{extra tokens at the end of '#pragma omp task' are ignored}}
   #pragma omp task depend (out: ) // expected-error {{expected expression}}
   #pragma omp task depend (inout : foobool(argc)), depend (in, argc) // omp50-error {{expected addressable lvalue expression, array element, array section or array shaping expression}} omp45-error {{expected addressable lvalue expression, array element or array section}} expected-warning {{missing ':' after dependency type - ignoring}} expected-error {{expected expression}}
@@ -70,7 +70,19 @@ int main(int argc, char **argv, char *env[]) {
   #pragma omp task depend(in : ([a])a) // omp45-error {{expected body of lambda expression}} omp50-error {{expected expression with a pointer to a complete type as a base of an array shaping operation}}
   #pragma omp task depend(in : ([a])argc) // omp45-error {{expected body of lambda expression}} omp50-error {{expected expression with a pointer to a complete type as a base of an array shaping operation}}
   #pragma omp task depend(in : ([-1][0])argv) // omp45-error {{expected variable name or 'this' in lambda capture list}} omp45-error {{expected ')'}} omp45-note {{to match this '('}} omp50-error {{array shaping dimension is evaluated to a non-positive value -1}} omp50-error {{array shaping dimension is evaluated to a non-positive value 0}}
+  #pragma omp task depend(iterator // expected-error {{expected ')'}} omp45-error {{expected 'in', 'out', 'inout' or 'mutexinoutset' in OpenMP clause 'depend'}} expected-warning {{missing ':' after dependency type - ignoring}} expected-note {{to match this '('}} omp50-error {{expected depend modifier(iterator) or 'in', 'out', 'inout', 'mutexinoutset' or 'depobj' in OpenMP clause 'depend'}} omp50-error {{expected '(' after 'iterator'}} omp50-error {{expected ','}}
+  #pragma omp task depend(iterator():argc) // omp45-error {{expected 'in', 'out', 'inout' or 'mutexinoutset' in OpenMP clause 'depend'}} omp50-error {{expected ','}} omp50-error {{expected 'in', 'out', 'inout', 'mutexinoutset' or 'depobj' in OpenMP clause 'depend'}}
+  #pragma omp task depend(iterator(argc // expected-error {{expected ')'}} omp45-error {{expected 'in', 'out', 'inout' or 'mutexinoutset' in OpenMP clause 'depend'}} expected-warning {{missing ':' after dependency type - ignoring}} expected-note {{to match this '('}} omp50-error {{unknown type name 'argc'}} omp50-error {{expected ')'}} omp50-error {{expected depend modifier(iterator) or 'in', 'out', 'inout', 'mutexinoutset' or 'depobj' in OpenMP clause 'depend'}} omp50-error {{expected ','}} omp50-note {{to match this '('}}
+  #pragma omp task depend(iterator(unsigned argc: // expected-error {{expected ')'}} omp45-error {{expected 'in', 'out', 'inout' or 'mutexinoutset' in OpenMP clause 'depend'}} expected-warning {{missing ':' after dependency type - ignoring}} expected-note {{to match this '('}} omp50-error {{expected '=' in iterator specifier}} omp50-error 2 {{expected expression}} omp50-error {{expected ',' or ')' after iterator specifier}} omp50-error {{expected ')'}} omp50-error {{expected depend modifier(iterator) or 'in', 'out', 'inout', 'mutexinoutset' or 'depobj' in OpenMP clause 'depend'}} omp50-error {{expected ','}} omp50-note {{to match this '('}}
+  #pragma omp task depend(iterator(unsigned argc = // expected-error {{expected ')'}} omp45-error {{expected 'in', 'out', 'inout' or 'mutexinoutset' in OpenMP clause 'depend'}} expected-warning {{missing ':' after dependency type - ignoring}} expected-note {{to match this '('}} omp50-error 2 {{expected expression}} omp50-error {{expected ',' or ')' after iterator specifier}} omp50-error {{expected ')'}} omp50-error {{expected depend modifier(iterator) or 'in', 'out', 'inout', 'mutexinoutset' or 'depobj' in OpenMP clause 'depend'}} omp50-error {{expected ','}} omp50-note {{to match this '('}}
+  #pragma omp task depend(iterator(vector argc = 0:2):argc) // omp45-error {{expected 'in', 'out', 'inout' or 'mutexinoutset' in OpenMP clause 'depend'}} omp50-error {{expected integral or pointer type as the iterator-type, not 'vector'}} omp50-error {{expected depend modifier(iterator) or 'in', 'out', 'inout', 'mutexinoutset' or 'depobj' in OpenMP clause 'depend'}} omp50-error {{expected ','}}
+  #pragma omp task depend(iterator(vector *argc = nullptr:nullptr+2:0), in:argc) // omp45-error {{expected 'in', 'out', 'inout' or 'mutexinoutset' in OpenMP clause 'depend'}} omp50-error {{invalid operands to binary expression ('nullptr_t' and 'int')}} omp50-error {{iterator step expression 0 evaluates to 0}}
+  #pragma omp task depend(iterator(vector *argc = 0:vector():argc), in:argc) // omp45-error {{expected 'in', 'out', 'inout' or 'mutexinoutset' in OpenMP clause 'depend'}} omp50-error {{converting 'vector' to incompatible type 'vector *'}}
   foo();
+#pragma omp task depend(iterator(unsigned argc = 0:10), in : argc) // omp45-error {{expected 'in', 'out', 'inout' or 'mutexinoutset' in OpenMP clause 'depend'}}
+  argc = 0;
+#pragma omp task depend(iterator(i = 0:10, i = 0:10), in : argv[i]) // omp45-error {{expected 'in', 'out', 'inout' or 'mutexinoutset' in OpenMP clause 'depend'}} omp45-error {{use of undeclared identifier 'i'}} omp50-error {{redefinition of 'i'}} omp50-note {{previous definition is here}}
+  i = 0; // expected-error {{use of undeclared identifier 'i'}}
 
   return 0;
 }

diff  --git a/clang/tools/libclang/CIndex.cpp b/clang/tools/libclang/CIndex.cpp
index bb9fed165679..14814f89d97d 100644
--- a/clang/tools/libclang/CIndex.cpp
+++ b/clang/tools/libclang/CIndex.cpp
@@ -5185,6 +5185,8 @@ CXString clang_getCursorKindSpelling(enum CXCursorKind Kind) {
     return cxstring::createRef("OMPArraySectionExpr");
   case CXCursor_OMPArrayShapingExpr:
     return cxstring::createRef("OMPArrayShapingExpr");
+  case CXCursor_OMPIteratorExpr:
+    return cxstring::createRef("OMPIteratorExpr");
   case CXCursor_BinaryOperator:
     return cxstring::createRef("BinaryOperator");
   case CXCursor_CompoundAssignOperator:

diff  --git a/clang/tools/libclang/CXCursor.cpp b/clang/tools/libclang/CXCursor.cpp
index 4f4e0c4ea1d5..3bcc7cc7af05 100644
--- a/clang/tools/libclang/CXCursor.cpp
+++ b/clang/tools/libclang/CXCursor.cpp
@@ -427,6 +427,10 @@ CXCursor cxcursor::MakeCXCursor(const Stmt *S, const Decl *Parent,
     K = CXCursor_OMPArrayShapingExpr;
     break;
 
+  case Stmt::OMPIteratorExprClass:
+    K = CXCursor_OMPIteratorExpr;
+    break;
+
   case Stmt::BinaryOperatorClass:
     K = CXCursor_BinaryOperator;
     break;


        


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