xref: /freebsd/contrib/llvm-project/clang/lib/CodeGen/CGOpenMPRuntime.h (revision e1e636193db45630c7881246d25902e57c43d24e)

//===----- CGOpenMPRuntime.h - Interface to OpenMP Runtimes -----*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This provides a class for OpenMP runtime code generation.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_CLANG_LIB_CODEGEN_CGOPENMPRUNTIME_H
#define LLVM_CLANG_LIB_CODEGEN_CGOPENMPRUNTIME_H

#include "CGValue.h"
#include "clang/AST/DeclOpenMP.h"
#include "clang/AST/GlobalDecl.h"
#include "clang/AST/Type.h"
#include "clang/Basic/OpenMPKinds.h"
#include "clang/Basic/SourceLocation.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/PointerIntPair.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/ADT/StringSet.h"
#include "llvm/Frontend/OpenMP/OMPConstants.h"
#include "llvm/Frontend/OpenMP/OMPIRBuilder.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/ValueHandle.h"
#include "llvm/Support/AtomicOrdering.h"

namespace llvm {
class ArrayType;
class Constant;
class FunctionType;
class GlobalVariable;
class Type;
class Value;
class OpenMPIRBuilder;
} // namespace llvm

namespace clang {
class Expr;
class OMPDependClause;
class OMPExecutableDirective;
class OMPLoopDirective;
class VarDecl;
class OMPDeclareReductionDecl;

namespace CodeGen {
class Address;
class CodeGenFunction;
class CodeGenModule;

/// A basic class for pre|post-action for advanced codegen sequence for OpenMP
/// region.
class PrePostActionTy {
public:
  explicit PrePostActionTy() {}
  virtual void Enter(CodeGenFunction &CGF) {}
  virtual void Exit(CodeGenFunction &CGF) {}
  virtual ~PrePostActionTy() {}
};

/// Class provides a way to call simple version of codegen for OpenMP region, or
/// an advanced with possible pre|post-actions in codegen.
class RegionCodeGenTy final {
  intptr_t CodeGen;
  typedef void (*CodeGenTy)(intptr_t, CodeGenFunction &, PrePostActionTy &);
  CodeGenTy Callback;
  mutable PrePostActionTy *PrePostAction;
  RegionCodeGenTy() = delete;
  template <typename Callable>
  static void CallbackFn(intptr_t CodeGen, CodeGenFunction &CGF,
                         PrePostActionTy &Action) {
    return (*reinterpret_cast<Callable *>(CodeGen))(CGF, Action);
  }

public:
  template <typename Callable>
  RegionCodeGenTy(
      Callable &&CodeGen,
      std::enable_if_t<!std::is_same<std::remove_reference_t<Callable>,
                                     RegionCodeGenTy>::value> * = nullptr)
      : CodeGen(reinterpret_cast<intptr_t>(&CodeGen)),
        Callback(CallbackFn<std::remove_reference_t<Callable>>),
        PrePostAction(nullptr) {}
  void setAction(PrePostActionTy &Action) const { PrePostAction = &Action; }
  void operator()(CodeGenFunction &CGF) const;
};

struct OMPTaskDataTy final {
  SmallVector<const Expr *, 4> PrivateVars;
  SmallVector<const Expr *, 4> PrivateCopies;
  SmallVector<const Expr *, 4> FirstprivateVars;
  SmallVector<const Expr *, 4> FirstprivateCopies;
  SmallVector<const Expr *, 4> FirstprivateInits;
  SmallVector<const Expr *, 4> LastprivateVars;
  SmallVector<const Expr *, 4> LastprivateCopies;
  SmallVector<const Expr *, 4> ReductionVars;
  SmallVector<const Expr *, 4> ReductionOrigs;
  SmallVector<const Expr *, 4> ReductionCopies;
  SmallVector<const Expr *, 4> ReductionOps;
  SmallVector<CanonicalDeclPtr<const VarDecl>, 4> PrivateLocals;
  struct DependData {
    OpenMPDependClauseKind DepKind = OMPC_DEPEND_unknown;
    const Expr *IteratorExpr = nullptr;
    SmallVector<const Expr *, 4> DepExprs;
    explicit DependData() = default;
    DependData(OpenMPDependClauseKind DepKind, const Expr *IteratorExpr)
        : DepKind(DepKind), IteratorExpr(IteratorExpr) {}
  };
  SmallVector<DependData, 4> Dependences;
  llvm::PointerIntPair<llvm::Value *, 1, bool> Final;
  llvm::PointerIntPair<llvm::Value *, 1, bool> Schedule;
  llvm::PointerIntPair<llvm::Value *, 1, bool> Priority;
  llvm::Value *Reductions = nullptr;
  unsigned NumberOfParts = 0;
  bool Tied = true;
  bool Nogroup = false;
  bool IsReductionWithTaskMod = false;
  bool IsWorksharingReduction = false;
  bool HasNowaitClause = false;
};

/// Class intended to support codegen of all kind of the reduction clauses.
class ReductionCodeGen {
private:
  /// Data required for codegen of reduction clauses.
  struct ReductionData {
    /// Reference to the item shared between tasks to reduce into.
    const Expr *Shared = nullptr;
    /// Reference to the original item.
    const Expr *Ref = nullptr;
    /// Helper expression for generation of private copy.
    const Expr *Private = nullptr;
    /// Helper expression for generation reduction operation.
    const Expr *ReductionOp = nullptr;
    ReductionData(const Expr *Shared, const Expr *Ref, const Expr *Private,
                  const Expr *ReductionOp)
        : Shared(Shared), Ref(Ref), Private(Private), ReductionOp(ReductionOp) {
    }
  };
  /// List of reduction-based clauses.
  SmallVector<ReductionData, 4> ClausesData;

  /// List of addresses of shared variables/expressions.
  SmallVector<std::pair<LValue, LValue>, 4> SharedAddresses;
  /// List of addresses of original variables/expressions.
  SmallVector<std::pair<LValue, LValue>, 4> OrigAddresses;
  /// Sizes of the reduction items in chars.
  SmallVector<std::pair<llvm::Value *, llvm::Value *>, 4> Sizes;
  /// Base declarations for the reduction items.
  SmallVector<const VarDecl *, 4> BaseDecls;

  /// Emits lvalue for shared expression.
  LValue emitSharedLValue(CodeGenFunction &CGF, const Expr *E);
  /// Emits upper bound for shared expression (if array section).
  LValue emitSharedLValueUB(CodeGenFunction &CGF, const Expr *E);
  /// Performs aggregate initialization.
  /// \param N Number of reduction item in the common list.
  /// \param PrivateAddr Address of the corresponding private item.
  /// \param SharedAddr Address of the original shared variable.
  /// \param DRD Declare reduction construct used for reduction item.
  void emitAggregateInitialization(CodeGenFunction &CGF, unsigned N,
                                   Address PrivateAddr, Address SharedAddr,
                                   const OMPDeclareReductionDecl *DRD);

public:
  ReductionCodeGen(ArrayRef<const Expr *> Shareds, ArrayRef<const Expr *> Origs,
                   ArrayRef<const Expr *> Privates,
                   ArrayRef<const Expr *> ReductionOps);
  /// Emits lvalue for the shared and original reduction item.
  /// \param N Number of the reduction item.
  void emitSharedOrigLValue(CodeGenFunction &CGF, unsigned N);
  /// Emits the code for the variable-modified type, if required.
  /// \param N Number of the reduction item.
  void emitAggregateType(CodeGenFunction &CGF, unsigned N);
  /// Emits the code for the variable-modified type, if required.
  /// \param N Number of the reduction item.
  /// \param Size Size of the type in chars.
  void emitAggregateType(CodeGenFunction &CGF, unsigned N, llvm::Value *Size);
  /// Performs initialization of the private copy for the reduction item.
  /// \param N Number of the reduction item.
  /// \param PrivateAddr Address of the corresponding private item.
  /// \param DefaultInit Default initialization sequence that should be
  /// performed if no reduction specific initialization is found.
  /// \param SharedAddr Address of the original shared variable.
  void
  emitInitialization(CodeGenFunction &CGF, unsigned N, Address PrivateAddr,
                     Address SharedAddr,
                     llvm::function_ref<bool(CodeGenFunction &)> DefaultInit);
  /// Returns true if the private copy requires cleanups.
  bool needCleanups(unsigned N);
  /// Emits cleanup code for the reduction item.
  /// \param N Number of the reduction item.
  /// \param PrivateAddr Address of the corresponding private item.
  void emitCleanups(CodeGenFunction &CGF, unsigned N, Address PrivateAddr);
  /// Adjusts \p PrivatedAddr for using instead of the original variable
  /// address in normal operations.
  /// \param N Number of the reduction item.
  /// \param PrivateAddr Address of the corresponding private item.
  Address adjustPrivateAddress(CodeGenFunction &CGF, unsigned N,
                               Address PrivateAddr);
  /// Returns LValue for the reduction item.
  LValue getSharedLValue(unsigned N) const { return SharedAddresses[N].first; }
  /// Returns LValue for the original reduction item.
  LValue getOrigLValue(unsigned N) const { return OrigAddresses[N].first; }
  /// Returns the size of the reduction item (in chars and total number of
  /// elements in the item), or nullptr, if the size is a constant.
  std::pair<llvm::Value *, llvm::Value *> getSizes(unsigned N) const {
    return Sizes[N];
  }
  /// Returns the base declaration of the reduction item.
  const VarDecl *getBaseDecl(unsigned N) const { return BaseDecls[N]; }
  /// Returns the base declaration of the reduction item.
  const Expr *getRefExpr(unsigned N) const { return ClausesData[N].Ref; }
  /// Returns true if the initialization of the reduction item uses initializer
  /// from declare reduction construct.
  bool usesReductionInitializer(unsigned N) const;
  /// Return the type of the private item.
  QualType getPrivateType(unsigned N) const {
    return cast<VarDecl>(cast<DeclRefExpr>(ClausesData[N].Private)->getDecl())
        ->getType();
  }
};

class CGOpenMPRuntime {
public:
  /// Allows to disable automatic handling of functions used in target regions
  /// as those marked as `omp declare target`.
  class DisableAutoDeclareTargetRAII {
    CodeGenModule &CGM;
    bool SavedShouldMarkAsGlobal = false;

  public:
    DisableAutoDeclareTargetRAII(CodeGenModule &CGM);
    ~DisableAutoDeclareTargetRAII();
  };

  /// Manages list of nontemporal decls for the specified directive.
  class NontemporalDeclsRAII {
    CodeGenModule &CGM;
    const bool NeedToPush;

  public:
    NontemporalDeclsRAII(CodeGenModule &CGM, const OMPLoopDirective &S);
    ~NontemporalDeclsRAII();
  };

  /// Manages list of nontemporal decls for the specified directive.
  class UntiedTaskLocalDeclsRAII {
    CodeGenModule &CGM;
    const bool NeedToPush;

  public:
    UntiedTaskLocalDeclsRAII(
        CodeGenFunction &CGF,
        const llvm::MapVector<CanonicalDeclPtr<const VarDecl>,
                              std::pair<Address, Address>> &LocalVars);
    ~UntiedTaskLocalDeclsRAII();
  };

  /// Maps the expression for the lastprivate variable to the global copy used
  /// to store new value because original variables are not mapped in inner
  /// parallel regions. Only private copies are captured but we need also to
  /// store private copy in shared address.
  /// Also, stores the expression for the private loop counter and it
  /// threaprivate name.
  struct LastprivateConditionalData {
    llvm::MapVector<CanonicalDeclPtr<const Decl>, SmallString<16>>
        DeclToUniqueName;
    LValue IVLVal;
    llvm::Function *Fn = nullptr;
    bool Disabled = false;
  };
  /// Manages list of lastprivate conditional decls for the specified directive.
  class LastprivateConditionalRAII {
    enum class ActionToDo {
      DoNotPush,
      PushAsLastprivateConditional,
      DisableLastprivateConditional,
    };
    CodeGenModule &CGM;
    ActionToDo Action = ActionToDo::DoNotPush;

    /// Check and try to disable analysis of inner regions for changes in
    /// lastprivate conditional.
    void tryToDisableInnerAnalysis(const OMPExecutableDirective &S,
                                   llvm::DenseSet<CanonicalDeclPtr<const Decl>>
                                       &NeedToAddForLPCsAsDisabled) const;

    LastprivateConditionalRAII(CodeGenFunction &CGF,
                               const OMPExecutableDirective &S);

  public:
    explicit LastprivateConditionalRAII(CodeGenFunction &CGF,
                                        const OMPExecutableDirective &S,
                                        LValue IVLVal);
    static LastprivateConditionalRAII disable(CodeGenFunction &CGF,
                                              const OMPExecutableDirective &S);
    ~LastprivateConditionalRAII();
  };

  llvm::OpenMPIRBuilder &getOMPBuilder() { return OMPBuilder; }

protected:
  CodeGenModule &CGM;

  /// An OpenMP-IR-Builder instance.
  llvm::OpenMPIRBuilder OMPBuilder;

  /// Helper to determine the min/max number of threads/teams for \p D.
  void computeMinAndMaxThreadsAndTeams(const OMPExecutableDirective &D,
                                       CodeGenFunction &CGF,
                                       int32_t &MinThreadsVal,
                                       int32_t &MaxThreadsVal,
                                       int32_t &MinTeamsVal,
                                       int32_t &MaxTeamsVal);

  /// Helper to emit outlined function for 'target' directive.
  /// \param D Directive to emit.
  /// \param ParentName Name of the function that encloses the target region.
  /// \param OutlinedFn Outlined function value to be defined by this call.
  /// \param OutlinedFnID Outlined function ID value to be defined by this call.
  /// \param IsOffloadEntry True if the outlined function is an offload entry.
  /// \param CodeGen Lambda codegen specific to an accelerator device.
  /// An outlined function may not be an entry if, e.g. the if clause always
  /// evaluates to false.
  virtual void emitTargetOutlinedFunctionHelper(const OMPExecutableDirective &D,
                                                StringRef ParentName,
                                                llvm::Function *&OutlinedFn,
                                                llvm::Constant *&OutlinedFnID,
                                                bool IsOffloadEntry,
                                                const RegionCodeGenTy &CodeGen);

  /// Returns pointer to ident_t type.
  llvm::Type *getIdentTyPointerTy();

  /// Gets thread id value for the current thread.
  ///
  llvm::Value *getThreadID(CodeGenFunction &CGF, SourceLocation Loc);

  /// Get the function name of an outlined region.
  std::string getOutlinedHelperName(StringRef Name) const;
  std::string getOutlinedHelperName(CodeGenFunction &CGF) const;

  /// Get the function name of a reduction function.
  std::string getReductionFuncName(StringRef Name) const;

  /// Emits \p Callee function call with arguments \p Args with location \p Loc.
  void emitCall(CodeGenFunction &CGF, SourceLocation Loc,
                llvm::FunctionCallee Callee,
                ArrayRef<llvm::Value *> Args = std::nullopt) const;

  /// Emits address of the word in a memory where current thread id is
  /// stored.
  virtual Address emitThreadIDAddress(CodeGenFunction &CGF, SourceLocation Loc);

  void setLocThreadIdInsertPt(CodeGenFunction &CGF,
                              bool AtCurrentPoint = false);
  void clearLocThreadIdInsertPt(CodeGenFunction &CGF);

  /// Check if the default location must be constant.
  /// Default is false to support OMPT/OMPD.
  virtual bool isDefaultLocationConstant() const { return false; }

  /// Returns additional flags that can be stored in reserved_2 field of the
  /// default location.
  virtual unsigned getDefaultLocationReserved2Flags() const { return 0; }

  /// Returns default flags for the barriers depending on the directive, for
  /// which this barier is going to be emitted.
  static unsigned getDefaultFlagsForBarriers(OpenMPDirectiveKind Kind);

  /// Get the LLVM type for the critical name.
  llvm::ArrayType *getKmpCriticalNameTy() const {return KmpCriticalNameTy;}

  /// Returns corresponding lock object for the specified critical region
  /// name. If the lock object does not exist it is created, otherwise the
  /// reference to the existing copy is returned.
  /// \param CriticalName Name of the critical region.
  ///
  llvm::Value *getCriticalRegionLock(StringRef CriticalName);

protected:
  /// Map for SourceLocation and OpenMP runtime library debug locations.
  typedef llvm::DenseMap<SourceLocation, llvm::Value *> OpenMPDebugLocMapTy;
  OpenMPDebugLocMapTy OpenMPDebugLocMap;
  /// The type for a microtask which gets passed to __kmpc_fork_call().
  /// Original representation is:
  /// typedef void (kmpc_micro)(kmp_int32 global_tid, kmp_int32 bound_tid,...);
  llvm::FunctionType *Kmpc_MicroTy = nullptr;
  /// Stores debug location and ThreadID for the function.
  struct DebugLocThreadIdTy {
    llvm::Value *DebugLoc;
    llvm::Value *ThreadID;
    /// Insert point for the service instructions.
    llvm::AssertingVH<llvm::Instruction> ServiceInsertPt = nullptr;
  };
  /// Map of local debug location, ThreadId and functions.
  typedef llvm::DenseMap<llvm::Function *, DebugLocThreadIdTy>
      OpenMPLocThreadIDMapTy;
  OpenMPLocThreadIDMapTy OpenMPLocThreadIDMap;
  /// Map of UDRs and corresponding combiner/initializer.
  typedef llvm::DenseMap<const OMPDeclareReductionDecl *,
                         std::pair<llvm::Function *, llvm::Function *>>
      UDRMapTy;
  UDRMapTy UDRMap;
  /// Map of functions and locally defined UDRs.
  typedef llvm::DenseMap<llvm::Function *,
                         SmallVector<const OMPDeclareReductionDecl *, 4>>
      FunctionUDRMapTy;
  FunctionUDRMapTy FunctionUDRMap;
  /// Map from the user-defined mapper declaration to its corresponding
  /// functions.
  llvm::DenseMap<const OMPDeclareMapperDecl *, llvm::Function *> UDMMap;
  /// Map of functions and their local user-defined mappers.
  using FunctionUDMMapTy =
      llvm::DenseMap<llvm::Function *,
                     SmallVector<const OMPDeclareMapperDecl *, 4>>;
  FunctionUDMMapTy FunctionUDMMap;
  /// Maps local variables marked as lastprivate conditional to their internal
  /// types.
  llvm::DenseMap<llvm::Function *,
                 llvm::DenseMap<CanonicalDeclPtr<const Decl>,
                                std::tuple<QualType, const FieldDecl *,
                                           const FieldDecl *, LValue>>>
      LastprivateConditionalToTypes;
  /// Maps function to the position of the untied task locals stack.
  llvm::DenseMap<llvm::Function *, unsigned> FunctionToUntiedTaskStackMap;
  /// Type kmp_critical_name, originally defined as typedef kmp_int32
  /// kmp_critical_name[8];
  llvm::ArrayType *KmpCriticalNameTy;
  /// An ordered map of auto-generated variables to their unique names.
  /// It stores variables with the following names: 1) ".gomp_critical_user_" +
  /// <critical_section_name> + ".var" for "omp critical" directives; 2)
  /// <mangled_name_for_global_var> + ".cache." for cache for threadprivate
  /// variables.
  llvm::StringMap<llvm::AssertingVH<llvm::GlobalVariable>,
                  llvm::BumpPtrAllocator> InternalVars;
  /// Type typedef kmp_int32 (* kmp_routine_entry_t)(kmp_int32, void *);
  llvm::Type *KmpRoutineEntryPtrTy = nullptr;
  QualType KmpRoutineEntryPtrQTy;
  /// Type typedef struct kmp_task {
  ///    void *              shareds; /**< pointer to block of pointers to
  ///    shared vars   */
  ///    kmp_routine_entry_t routine; /**< pointer to routine to call for
  ///    executing task */
  ///    kmp_int32           part_id; /**< part id for the task */
  ///    kmp_routine_entry_t destructors; /* pointer to function to invoke
  ///    deconstructors of firstprivate C++ objects */
  /// } kmp_task_t;
  QualType KmpTaskTQTy;
  /// Saved kmp_task_t for task directive.
  QualType SavedKmpTaskTQTy;
  /// Saved kmp_task_t for taskloop-based directive.
  QualType SavedKmpTaskloopTQTy;
  /// Type typedef struct kmp_depend_info {
  ///    kmp_intptr_t               base_addr;
  ///    size_t                     len;
  ///    struct {
  ///             bool                   in:1;
  ///             bool                   out:1;
  ///    } flags;
  /// } kmp_depend_info_t;
  QualType KmpDependInfoTy;
  /// Type typedef struct kmp_task_affinity_info {
  ///    kmp_intptr_t base_addr;
  ///    size_t len;
  ///    struct {
  ///      bool flag1 : 1;
  ///      bool flag2 : 1;
  ///      kmp_int32 reserved : 30;
  ///   } flags;
  /// } kmp_task_affinity_info_t;
  QualType KmpTaskAffinityInfoTy;
  /// struct kmp_dim {  // loop bounds info casted to kmp_int64
  ///  kmp_int64 lo; // lower
  ///  kmp_int64 up; // upper
  ///  kmp_int64 st; // stride
  /// };
  QualType KmpDimTy;

  bool ShouldMarkAsGlobal = true;
  /// List of the emitted declarations.
  llvm::DenseSet<CanonicalDeclPtr<const Decl>> AlreadyEmittedTargetDecls;
  /// List of the global variables with their addresses that should not be
  /// emitted for the target.
  llvm::StringMap<llvm::WeakTrackingVH> EmittedNonTargetVariables;

  /// List of variables that can become declare target implicitly and, thus,
  /// must be emitted.
  llvm::SmallDenseSet<const VarDecl *> DeferredGlobalVariables;

  using NontemporalDeclsSet = llvm::SmallDenseSet<CanonicalDeclPtr<const Decl>>;
  /// Stack for list of declarations in current context marked as nontemporal.
  /// The set is the union of all current stack elements.
  llvm::SmallVector<NontemporalDeclsSet, 4> NontemporalDeclsStack;

  using UntiedLocalVarsAddressesMap =
      llvm::MapVector<CanonicalDeclPtr<const VarDecl>,
                      std::pair<Address, Address>>;
  llvm::SmallVector<UntiedLocalVarsAddressesMap, 4> UntiedLocalVarsStack;

  /// Stack for list of addresses of declarations in current context marked as
  /// lastprivate conditional. The set is the union of all current stack
  /// elements.
  llvm::SmallVector<LastprivateConditionalData, 4> LastprivateConditionalStack;

  /// Flag for keeping track of weather a requires unified_shared_memory
  /// directive is present.
  bool HasRequiresUnifiedSharedMemory = false;

  /// Atomic ordering from the omp requires directive.
  llvm::AtomicOrdering RequiresAtomicOrdering = llvm::AtomicOrdering::Monotonic;

  /// Flag for keeping track of weather a target region has been emitted.
  bool HasEmittedTargetRegion = false;

  /// Flag for keeping track of weather a device routine has been emitted.
  /// Device routines are specific to the
  bool HasEmittedDeclareTargetRegion = false;

  /// Start scanning from statement \a S and emit all target regions
  /// found along the way.
  /// \param S Starting statement.
  /// \param ParentName Name of the function declaration that is being scanned.
  void scanForTargetRegionsFunctions(const Stmt *S, StringRef ParentName);

  /// Build type kmp_routine_entry_t (if not built yet).
  void emitKmpRoutineEntryT(QualType KmpInt32Ty);

  /// Returns pointer to kmpc_micro type.
  llvm::Type *getKmpc_MicroPointerTy();

  /// If the specified mangled name is not in the module, create and
  /// return threadprivate cache object. This object is a pointer's worth of
  /// storage that's reserved for use by the OpenMP runtime.
  /// \param VD Threadprivate variable.
  /// \return Cache variable for the specified threadprivate.
  llvm::Constant *getOrCreateThreadPrivateCache(const VarDecl *VD);

  /// Set of threadprivate variables with the generated initializer.
  llvm::StringSet<> ThreadPrivateWithDefinition;

  /// Set of declare target variables with the generated initializer.
  llvm::StringSet<> DeclareTargetWithDefinition;

  /// Emits initialization code for the threadprivate variables.
  /// \param VDAddr Address of the global variable \a VD.
  /// \param Ctor Pointer to a global init function for \a VD.
  /// \param CopyCtor Pointer to a global copy function for \a VD.
  /// \param Dtor Pointer to a global destructor function for \a VD.
  /// \param Loc Location of threadprivate declaration.
  void emitThreadPrivateVarInit(CodeGenFunction &CGF, Address VDAddr,
                                llvm::Value *Ctor, llvm::Value *CopyCtor,
                                llvm::Value *Dtor, SourceLocation Loc);

  /// Emit the array initialization or deletion portion for user-defined mapper
  /// code generation.
  void emitUDMapperArrayInitOrDel(CodeGenFunction &MapperCGF,
                                  llvm::Value *Handle, llvm::Value *BasePtr,
                                  llvm::Value *Ptr, llvm::Value *Size,
                                  llvm::Value *MapType, llvm::Value *MapName,
                                  CharUnits ElementSize,
                                  llvm::BasicBlock *ExitBB, bool IsInit);

  struct TaskResultTy {
    llvm::Value *NewTask = nullptr;
    llvm::Function *TaskEntry = nullptr;
    llvm::Value *NewTaskNewTaskTTy = nullptr;
    LValue TDBase;
    const RecordDecl *KmpTaskTQTyRD = nullptr;
    llvm::Value *TaskDupFn = nullptr;
  };
  /// Emit task region for the task directive. The task region is emitted in
  /// several steps:
  /// 1. Emit a call to kmp_task_t *__kmpc_omp_task_alloc(ident_t *, kmp_int32
  /// gtid, kmp_int32 flags, size_t sizeof_kmp_task_t, size_t sizeof_shareds,
  /// kmp_routine_entry_t *task_entry). Here task_entry is a pointer to the
  /// function:
  /// kmp_int32 .omp_task_entry.(kmp_int32 gtid, kmp_task_t *tt) {
  ///   TaskFunction(gtid, tt->part_id, tt->shareds);
  ///   return 0;
  /// }
  /// 2. Copy a list of shared variables to field shareds of the resulting
  /// structure kmp_task_t returned by the previous call (if any).
  /// 3. Copy a pointer to destructions function to field destructions of the
  /// resulting structure kmp_task_t.
  /// \param D Current task directive.
  /// \param TaskFunction An LLVM function with type void (*)(i32 /*gtid*/, i32
  /// /*part_id*/, captured_struct */*__context*/);
  /// \param SharedsTy A type which contains references the shared variables.
  /// \param Shareds Context with the list of shared variables from the \p
  /// TaskFunction.
  /// \param Data Additional data for task generation like tiednsee, final
  /// state, list of privates etc.
  TaskResultTy emitTaskInit(CodeGenFunction &CGF, SourceLocation Loc,
                            const OMPExecutableDirective &D,
                            llvm::Function *TaskFunction, QualType SharedsTy,
                            Address Shareds, const OMPTaskDataTy &Data);

  /// Emit update for lastprivate conditional data.
  void emitLastprivateConditionalUpdate(CodeGenFunction &CGF, LValue IVLVal,
                                        StringRef UniqueDeclName, LValue LVal,
                                        SourceLocation Loc);

  /// Returns the number of the elements and the address of the depobj
  /// dependency array.
  /// \return Number of elements in depobj array and the pointer to the array of
  /// dependencies.
  std::pair<llvm::Value *, LValue> getDepobjElements(CodeGenFunction &CGF,
                                                     LValue DepobjLVal,
                                                     SourceLocation Loc);

  SmallVector<llvm::Value *, 4>
  emitDepobjElementsSizes(CodeGenFunction &CGF, QualType &KmpDependInfoTy,
                          const OMPTaskDataTy::DependData &Data);

  void emitDepobjElements(CodeGenFunction &CGF, QualType &KmpDependInfoTy,
                          LValue PosLVal, const OMPTaskDataTy::DependData &Data,
                          Address DependenciesArray);

public:
  explicit CGOpenMPRuntime(CodeGenModule &CGM);
  virtual ~CGOpenMPRuntime() {}
  virtual void clear();

  /// Emits object of ident_t type with info for source location.
  /// \param Flags Flags for OpenMP location.
  /// \param EmitLoc emit source location with debug-info is off.
  ///
  llvm::Value *emitUpdateLocation(CodeGenFunction &CGF, SourceLocation Loc,
                                  unsigned Flags = 0, bool EmitLoc = false);

  /// Emit the number of teams for a target directive.  Inspect the num_teams
  /// clause associated with a teams construct combined or closely nested
  /// with the target directive.
  ///
  /// Emit a team of size one for directives such as 'target parallel' that
  /// have no associated teams construct.
  ///
  /// Otherwise, return nullptr.
  const Expr *getNumTeamsExprForTargetDirective(CodeGenFunction &CGF,
                                                const OMPExecutableDirective &D,
                                                int32_t &MinTeamsVal,
                                                int32_t &MaxTeamsVal);
  llvm::Value *emitNumTeamsForTargetDirective(CodeGenFunction &CGF,
                                              const OMPExecutableDirective &D);

  /// Check for a number of threads upper bound constant value (stored in \p
  /// UpperBound), or expression (returned). If the value is conditional (via an
  /// if-clause), store the condition in \p CondExpr. Similarly, a potential
  /// thread limit expression is stored in \p ThreadLimitExpr. If \p
  /// UpperBoundOnly is true, no expression evaluation is perfomed.
  const Expr *getNumThreadsExprForTargetDirective(
      CodeGenFunction &CGF, const OMPExecutableDirective &D,
      int32_t &UpperBound, bool UpperBoundOnly,
      llvm::Value **CondExpr = nullptr, const Expr **ThreadLimitExpr = nullptr);

  /// Emit an expression that denotes the number of threads a target region
  /// shall use. Will generate "i32 0" to allow the runtime to choose.
  llvm::Value *
  emitNumThreadsForTargetDirective(CodeGenFunction &CGF,
                                   const OMPExecutableDirective &D);

  /// Return the trip count of loops associated with constructs / 'target teams
  /// distribute' and 'teams distribute parallel for'. \param SizeEmitter Emits
  /// the int64 value for the number of iterations of the associated loop.
  llvm::Value *emitTargetNumIterationsCall(
      CodeGenFunction &CGF, const OMPExecutableDirective &D,
      llvm::function_ref<llvm::Value *(CodeGenFunction &CGF,
                                       const OMPLoopDirective &D)>
          SizeEmitter);

  /// Returns true if the current target is a GPU.
  virtual bool isGPU() const { return false; }

  /// Check if the variable length declaration is delayed:
  virtual bool isDelayedVariableLengthDecl(CodeGenFunction &CGF,
                                           const VarDecl *VD) const {
    return false;
  };

  /// Get call to __kmpc_alloc_shared
  virtual std::pair<llvm::Value *, llvm::Value *>
  getKmpcAllocShared(CodeGenFunction &CGF, const VarDecl *VD) {
    llvm_unreachable("not implemented");
  }

  /// Get call to __kmpc_free_shared
  virtual void getKmpcFreeShared(
      CodeGenFunction &CGF,
      const std::pair<llvm::Value *, llvm::Value *> &AddrSizePair) {
    llvm_unreachable("not implemented");
  }

  /// Emits code for OpenMP 'if' clause using specified \a CodeGen
  /// function. Here is the logic:
  /// if (Cond) {
  ///   ThenGen();
  /// } else {
  ///   ElseGen();
  /// }
  void emitIfClause(CodeGenFunction &CGF, const Expr *Cond,
                    const RegionCodeGenTy &ThenGen,
                    const RegionCodeGenTy &ElseGen);

  /// Checks if the \p Body is the \a CompoundStmt and returns its child
  /// statement iff there is only one that is not evaluatable at the compile
  /// time.
  static const Stmt *getSingleCompoundChild(ASTContext &Ctx, const Stmt *Body);

  /// Get the platform-specific name separator.
  std::string getName(ArrayRef<StringRef> Parts) const;

  /// Emit code for the specified user defined reduction construct.
  virtual void emitUserDefinedReduction(CodeGenFunction *CGF,
                                        const OMPDeclareReductionDecl *D);
  /// Get combiner/initializer for the specified user-defined reduction, if any.
  virtual std::pair<llvm::Function *, llvm::Function *>
  getUserDefinedReduction(const OMPDeclareReductionDecl *D);

  /// Emit the function for the user defined mapper construct.
  void emitUserDefinedMapper(const OMPDeclareMapperDecl *D,
                             CodeGenFunction *CGF = nullptr);
  /// Get the function for the specified user-defined mapper. If it does not
  /// exist, create one.
  llvm::Function *
  getOrCreateUserDefinedMapperFunc(const OMPDeclareMapperDecl *D);

  /// Emits outlined function for the specified OpenMP parallel directive
  /// \a D. This outlined function has type void(*)(kmp_int32 *ThreadID,
  /// kmp_int32 BoundID, struct context_vars*).
  /// \param CGF Reference to current CodeGenFunction.
  /// \param D OpenMP directive.
  /// \param ThreadIDVar Variable for thread id in the current OpenMP region.
  /// \param InnermostKind Kind of innermost directive (for simple directives it
  /// is a directive itself, for combined - its innermost directive).
  /// \param CodeGen Code generation sequence for the \a D directive.
  virtual llvm::Function *emitParallelOutlinedFunction(
      CodeGenFunction &CGF, const OMPExecutableDirective &D,
      const VarDecl *ThreadIDVar, OpenMPDirectiveKind InnermostKind,
      const RegionCodeGenTy &CodeGen);

  /// Emits outlined function for the specified OpenMP teams directive
  /// \a D. This outlined function has type void(*)(kmp_int32 *ThreadID,
  /// kmp_int32 BoundID, struct context_vars*).
  /// \param CGF Reference to current CodeGenFunction.
  /// \param D OpenMP directive.
  /// \param ThreadIDVar Variable for thread id in the current OpenMP region.
  /// \param InnermostKind Kind of innermost directive (for simple directives it
  /// is a directive itself, for combined - its innermost directive).
  /// \param CodeGen Code generation sequence for the \a D directive.
  virtual llvm::Function *emitTeamsOutlinedFunction(
      CodeGenFunction &CGF, const OMPExecutableDirective &D,
      const VarDecl *ThreadIDVar, OpenMPDirectiveKind InnermostKind,
      const RegionCodeGenTy &CodeGen);

  /// Emits outlined function for the OpenMP task directive \a D. This
  /// outlined function has type void(*)(kmp_int32 ThreadID, struct task_t*
  /// TaskT).
  /// \param D OpenMP directive.
  /// \param ThreadIDVar Variable for thread id in the current OpenMP region.
  /// \param PartIDVar Variable for partition id in the current OpenMP untied
  /// task region.
  /// \param TaskTVar Variable for task_t argument.
  /// \param InnermostKind Kind of innermost directive (for simple directives it
  /// is a directive itself, for combined - its innermost directive).
  /// \param CodeGen Code generation sequence for the \a D directive.
  /// \param Tied true if task is generated for tied task, false otherwise.
  /// \param NumberOfParts Number of parts in untied task. Ignored for tied
  /// tasks.
  ///
  virtual llvm::Function *emitTaskOutlinedFunction(
      const OMPExecutableDirective &D, const VarDecl *ThreadIDVar,
      const VarDecl *PartIDVar, const VarDecl *TaskTVar,
      OpenMPDirectiveKind InnermostKind, const RegionCodeGenTy &CodeGen,
      bool Tied, unsigned &NumberOfParts);

  /// Cleans up references to the objects in finished function.
  ///
  virtual void functionFinished(CodeGenFunction &CGF);

  /// Emits code for parallel or serial call of the \a OutlinedFn with
  /// variables captured in a record which address is stored in \a
  /// CapturedStruct.
  /// \param OutlinedFn Outlined function to be run in parallel threads. Type of
  /// this function is void(*)(kmp_int32 *, kmp_int32, struct context_vars*).
  /// \param CapturedVars A pointer to the record with the references to
  /// variables used in \a OutlinedFn function.
  /// \param IfCond Condition in the associated 'if' clause, if it was
  /// specified, nullptr otherwise.
  /// \param NumThreads The value corresponding to the num_threads clause, if
  /// any, or nullptr.
  ///
  virtual void emitParallelCall(CodeGenFunction &CGF, SourceLocation Loc,
                                llvm::Function *OutlinedFn,
                                ArrayRef<llvm::Value *> CapturedVars,
                                const Expr *IfCond, llvm::Value *NumThreads);

  /// Emits a critical region.
  /// \param CriticalName Name of the critical region.
  /// \param CriticalOpGen Generator for the statement associated with the given
  /// critical region.
  /// \param Hint Value of the 'hint' clause (optional).
  virtual void emitCriticalRegion(CodeGenFunction &CGF, StringRef CriticalName,
                                  const RegionCodeGenTy &CriticalOpGen,
                                  SourceLocation Loc,
                                  const Expr *Hint = nullptr);

  /// Emits a master region.
  /// \param MasterOpGen Generator for the statement associated with the given
  /// master region.
  virtual void emitMasterRegion(CodeGenFunction &CGF,
                                const RegionCodeGenTy &MasterOpGen,
                                SourceLocation Loc);

  /// Emits a masked region.
  /// \param MaskedOpGen Generator for the statement associated with the given
  /// masked region.
  virtual void emitMaskedRegion(CodeGenFunction &CGF,
                                const RegionCodeGenTy &MaskedOpGen,
                                SourceLocation Loc,
                                const Expr *Filter = nullptr);

  /// Emits code for a taskyield directive.
  virtual void emitTaskyieldCall(CodeGenFunction &CGF, SourceLocation Loc);

  /// Emit __kmpc_error call for error directive
  /// extern void __kmpc_error(ident_t *loc, int severity, const char *message);
  virtual void emitErrorCall(CodeGenFunction &CGF, SourceLocation Loc, Expr *ME,
                             bool IsFatal);

  /// Emit a taskgroup region.
  /// \param TaskgroupOpGen Generator for the statement associated with the
  /// given taskgroup region.
  virtual void emitTaskgroupRegion(CodeGenFunction &CGF,
                                   const RegionCodeGenTy &TaskgroupOpGen,
                                   SourceLocation Loc);

  /// Emits a single region.
  /// \param SingleOpGen Generator for the statement associated with the given
  /// single region.
  virtual void emitSingleRegion(CodeGenFunction &CGF,
                                const RegionCodeGenTy &SingleOpGen,
                                SourceLocation Loc,
                                ArrayRef<const Expr *> CopyprivateVars,
                                ArrayRef<const Expr *> DestExprs,
                                ArrayRef<const Expr *> SrcExprs,
                                ArrayRef<const Expr *> AssignmentOps);

  /// Emit an ordered region.
  /// \param OrderedOpGen Generator for the statement associated with the given
  /// ordered region.
  virtual void emitOrderedRegion(CodeGenFunction &CGF,
                                 const RegionCodeGenTy &OrderedOpGen,
                                 SourceLocation Loc, bool IsThreads);

  /// Emit an implicit/explicit barrier for OpenMP threads.
  /// \param Kind Directive for which this implicit barrier call must be
  /// generated. Must be OMPD_barrier for explicit barrier generation.
  /// \param EmitChecks true if need to emit checks for cancellation barriers.
  /// \param ForceSimpleCall true simple barrier call must be emitted, false if
  /// runtime class decides which one to emit (simple or with cancellation
  /// checks).
  ///
  virtual void emitBarrierCall(CodeGenFunction &CGF, SourceLocation Loc,
                               OpenMPDirectiveKind Kind,
                               bool EmitChecks = true,
                               bool ForceSimpleCall = false);

  /// Check if the specified \a ScheduleKind is static non-chunked.
  /// This kind of worksharing directive is emitted without outer loop.
  /// \param ScheduleKind Schedule kind specified in the 'schedule' clause.
  /// \param Chunked True if chunk is specified in the clause.
  ///
  virtual bool isStaticNonchunked(OpenMPScheduleClauseKind ScheduleKind,
                                  bool Chunked) const;

  /// Check if the specified \a ScheduleKind is static non-chunked.
  /// This kind of distribute directive is emitted without outer loop.
  /// \param ScheduleKind Schedule kind specified in the 'dist_schedule' clause.
  /// \param Chunked True if chunk is specified in the clause.
  ///
  virtual bool isStaticNonchunked(OpenMPDistScheduleClauseKind ScheduleKind,
                                  bool Chunked) const;

  /// Check if the specified \a ScheduleKind is static chunked.
  /// \param ScheduleKind Schedule kind specified in the 'schedule' clause.
  /// \param Chunked True if chunk is specified in the clause.
  ///
  virtual bool isStaticChunked(OpenMPScheduleClauseKind ScheduleKind,
                               bool Chunked) const;

  /// Check if the specified \a ScheduleKind is static non-chunked.
  /// \param ScheduleKind Schedule kind specified in the 'dist_schedule' clause.
  /// \param Chunked True if chunk is specified in the clause.
  ///
  virtual bool isStaticChunked(OpenMPDistScheduleClauseKind ScheduleKind,
                               bool Chunked) const;

  /// Check if the specified \a ScheduleKind is dynamic.
  /// This kind of worksharing directive is emitted without outer loop.
  /// \param ScheduleKind Schedule Kind specified in the 'schedule' clause.
  ///
  virtual bool isDynamic(OpenMPScheduleClauseKind ScheduleKind) const;

  /// struct with the values to be passed to the dispatch runtime function
  struct DispatchRTInput {
    /// Loop lower bound
    llvm::Value *LB = nullptr;
    /// Loop upper bound
    llvm::Value *UB = nullptr;
    /// Chunk size specified using 'schedule' clause (nullptr if chunk
    /// was not specified)
    llvm::Value *Chunk = nullptr;
    DispatchRTInput() = default;
    DispatchRTInput(llvm::Value *LB, llvm::Value *UB, llvm::Value *Chunk)
        : LB(LB), UB(UB), Chunk(Chunk) {}
  };

  /// Call the appropriate runtime routine to initialize it before start
  /// of loop.

  /// This is used for non static scheduled types and when the ordered
  /// clause is present on the loop construct.
  /// Depending on the loop schedule, it is necessary to call some runtime
  /// routine before start of the OpenMP loop to get the loop upper / lower
  /// bounds \a LB and \a UB and stride \a ST.
  ///
  /// \param CGF Reference to current CodeGenFunction.
  /// \param Loc Clang source location.
  /// \param ScheduleKind Schedule kind, specified by the 'schedule' clause.
  /// \param IVSize Size of the iteration variable in bits.
  /// \param IVSigned Sign of the iteration variable.
  /// \param Ordered true if loop is ordered, false otherwise.
  /// \param DispatchValues struct containing llvm values for lower bound, upper
  /// bound, and chunk expression.
  /// For the default (nullptr) value, the chunk 1 will be used.
  ///
  virtual void emitForDispatchInit(CodeGenFunction &CGF, SourceLocation Loc,
                                   const OpenMPScheduleTy &ScheduleKind,
                                   unsigned IVSize, bool IVSigned, bool Ordered,
                                   const DispatchRTInput &DispatchValues);

  /// Struct with the values to be passed to the static runtime function
  struct StaticRTInput {
    /// Size of the iteration variable in bits.
    unsigned IVSize = 0;
    /// Sign of the iteration variable.
    bool IVSigned = false;
    /// true if loop is ordered, false otherwise.
    bool Ordered = false;
    /// Address of the output variable in which the flag of the last iteration
    /// is returned.
    Address IL = Address::invalid();
    /// Address of the output variable in which the lower iteration number is
    /// returned.
    Address LB = Address::invalid();
    /// Address of the output variable in which the upper iteration number is
    /// returned.
    Address UB = Address::invalid();
    /// Address of the output variable in which the stride value is returned
    /// necessary to generated the static_chunked scheduled loop.
    Address ST = Address::invalid();
    /// Value of the chunk for the static_chunked scheduled loop. For the
    /// default (nullptr) value, the chunk 1 will be used.
    llvm::Value *Chunk = nullptr;
    StaticRTInput(unsigned IVSize, bool IVSigned, bool Ordered, Address IL,
                  Address LB, Address UB, Address ST,
                  llvm::Value *Chunk = nullptr)
        : IVSize(IVSize), IVSigned(IVSigned), Ordered(Ordered), IL(IL), LB(LB),
          UB(UB), ST(ST), Chunk(Chunk) {}
  };
  /// Call the appropriate runtime routine to initialize it before start
  /// of loop.
  ///
  /// This is used only in case of static schedule, when the user did not
  /// specify a ordered clause on the loop construct.
  /// Depending on the loop schedule, it is necessary to call some runtime
  /// routine before start of the OpenMP loop to get the loop upper / lower
  /// bounds LB and UB and stride ST.
  ///
  /// \param CGF Reference to current CodeGenFunction.
  /// \param Loc Clang source location.
  /// \param DKind Kind of the directive.
  /// \param ScheduleKind Schedule kind, specified by the 'schedule' clause.
  /// \param Values Input arguments for the construct.
  ///
  virtual void emitForStaticInit(CodeGenFunction &CGF, SourceLocation Loc,
                                 OpenMPDirectiveKind DKind,
                                 const OpenMPScheduleTy &ScheduleKind,
                                 const StaticRTInput &Values);

  ///
  /// \param CGF Reference to current CodeGenFunction.
  /// \param Loc Clang source location.
  /// \param SchedKind Schedule kind, specified by the 'dist_schedule' clause.
  /// \param Values Input arguments for the construct.
  ///
  virtual void emitDistributeStaticInit(CodeGenFunction &CGF,
                                        SourceLocation Loc,
                                        OpenMPDistScheduleClauseKind SchedKind,
                                        const StaticRTInput &Values);

  /// Call the appropriate runtime routine to notify that we finished
  /// iteration of the ordered loop with the dynamic scheduling.
  ///
  /// \param CGF Reference to current CodeGenFunction.
  /// \param Loc Clang source location.
  /// \param IVSize Size of the iteration variable in bits.
  /// \param IVSigned Sign of the iteration variable.
  ///
  virtual void emitForOrderedIterationEnd(CodeGenFunction &CGF,
                                          SourceLocation Loc, unsigned IVSize,
                                          bool IVSigned);

  /// Call the appropriate runtime routine to notify that we finished
  /// all the work with current loop.
  ///
  /// \param CGF Reference to current CodeGenFunction.
  /// \param Loc Clang source location.
  /// \param DKind Kind of the directive for which the static finish is emitted.
  ///
  virtual void emitForStaticFinish(CodeGenFunction &CGF, SourceLocation Loc,
                                   OpenMPDirectiveKind DKind);

  /// Call __kmpc_dispatch_next(
  ///          ident_t *loc, kmp_int32 tid, kmp_int32 *p_lastiter,
  ///          kmp_int[32|64] *p_lower, kmp_int[32|64] *p_upper,
  ///          kmp_int[32|64] *p_stride);
  /// \param IVSize Size of the iteration variable in bits.
  /// \param IVSigned Sign of the iteration variable.
  /// \param IL Address of the output variable in which the flag of the
  /// last iteration is returned.
  /// \param LB Address of the output variable in which the lower iteration
  /// number is returned.
  /// \param UB Address of the output variable in which the upper iteration
  /// number is returned.
  /// \param ST Address of the output variable in which the stride value is
  /// returned.
  virtual llvm::Value *emitForNext(CodeGenFunction &CGF, SourceLocation Loc,
                                   unsigned IVSize, bool IVSigned,
                                   Address IL, Address LB,
                                   Address UB, Address ST);

  /// Emits call to void __kmpc_push_num_threads(ident_t *loc, kmp_int32
  /// global_tid, kmp_int32 num_threads) to generate code for 'num_threads'
  /// clause.
  /// \param NumThreads An integer value of threads.
  virtual void emitNumThreadsClause(CodeGenFunction &CGF,
                                    llvm::Value *NumThreads,
                                    SourceLocation Loc);

  /// Emit call to void __kmpc_push_proc_bind(ident_t *loc, kmp_int32
  /// global_tid, int proc_bind) to generate code for 'proc_bind' clause.
  virtual void emitProcBindClause(CodeGenFunction &CGF,
                                  llvm::omp::ProcBindKind ProcBind,
                                  SourceLocation Loc);

  /// Returns address of the threadprivate variable for the current
  /// thread.
  /// \param VD Threadprivate variable.
  /// \param VDAddr Address of the global variable \a VD.
  /// \param Loc Location of the reference to threadprivate var.
  /// \return Address of the threadprivate variable for the current thread.
  virtual Address getAddrOfThreadPrivate(CodeGenFunction &CGF,
                                         const VarDecl *VD,
                                         Address VDAddr,
                                         SourceLocation Loc);

  /// Returns the address of the variable marked as declare target with link
  /// clause OR as declare target with to clause and unified memory.
  virtual Address getAddrOfDeclareTargetVar(const VarDecl *VD);

  /// Emit a code for initialization of threadprivate variable. It emits
  /// a call to runtime library which adds initial value to the newly created
  /// threadprivate variable (if it is not constant) and registers destructor
  /// for the variable (if any).
  /// \param VD Threadprivate variable.
  /// \param VDAddr Address of the global variable \a VD.
  /// \param Loc Location of threadprivate declaration.
  /// \param PerformInit true if initialization expression is not constant.
  virtual llvm::Function *
  emitThreadPrivateVarDefinition(const VarDecl *VD, Address VDAddr,
                                 SourceLocation Loc, bool PerformInit,
                                 CodeGenFunction *CGF = nullptr);

  /// Emit code for handling declare target functions in the runtime.
  /// \param FD Declare target function.
  /// \param Addr Address of the global \a FD.
  /// \param PerformInit true if initialization expression is not constant.
  virtual void emitDeclareTargetFunction(const FunctionDecl *FD,
                                         llvm::GlobalValue *GV);

  /// Creates artificial threadprivate variable with name \p Name and type \p
  /// VarType.
  /// \param VarType Type of the artificial threadprivate variable.
  /// \param Name Name of the artificial threadprivate variable.
  virtual Address getAddrOfArtificialThreadPrivate(CodeGenFunction &CGF,
                                                   QualType VarType,
                                                   StringRef Name);

  /// Emit flush of the variables specified in 'omp flush' directive.
  /// \param Vars List of variables to flush.
  virtual void emitFlush(CodeGenFunction &CGF, ArrayRef<const Expr *> Vars,
                         SourceLocation Loc, llvm::AtomicOrdering AO);

  /// Emit task region for the task directive. The task region is
  /// emitted in several steps:
  /// 1. Emit a call to kmp_task_t *__kmpc_omp_task_alloc(ident_t *, kmp_int32
  /// gtid, kmp_int32 flags, size_t sizeof_kmp_task_t, size_t sizeof_shareds,
  /// kmp_routine_entry_t *task_entry). Here task_entry is a pointer to the
  /// function:
  /// kmp_int32 .omp_task_entry.(kmp_int32 gtid, kmp_task_t *tt) {
  ///   TaskFunction(gtid, tt->part_id, tt->shareds);
  ///   return 0;
  /// }
  /// 2. Copy a list of shared variables to field shareds of the resulting
  /// structure kmp_task_t returned by the previous call (if any).
  /// 3. Copy a pointer to destructions function to field destructions of the
  /// resulting structure kmp_task_t.
  /// 4. Emit a call to kmp_int32 __kmpc_omp_task(ident_t *, kmp_int32 gtid,
  /// kmp_task_t *new_task), where new_task is a resulting structure from
  /// previous items.
  /// \param D Current task directive.
  /// \param TaskFunction An LLVM function with type void (*)(i32 /*gtid*/, i32
  /// /*part_id*/, captured_struct */*__context*/);
  /// \param SharedsTy A type which contains references the shared variables.
  /// \param Shareds Context with the list of shared variables from the \p
  /// TaskFunction.
  /// \param IfCond Not a nullptr if 'if' clause was specified, nullptr
  /// otherwise.
  /// \param Data Additional data for task generation like tiednsee, final
  /// state, list of privates etc.
  virtual void emitTaskCall(CodeGenFunction &CGF, SourceLocation Loc,
                            const OMPExecutableDirective &D,
                            llvm::Function *TaskFunction, QualType SharedsTy,
                            Address Shareds, const Expr *IfCond,
                            const OMPTaskDataTy &Data);

  /// Emit task region for the taskloop directive. The taskloop region is
  /// emitted in several steps:
  /// 1. Emit a call to kmp_task_t *__kmpc_omp_task_alloc(ident_t *, kmp_int32
  /// gtid, kmp_int32 flags, size_t sizeof_kmp_task_t, size_t sizeof_shareds,
  /// kmp_routine_entry_t *task_entry). Here task_entry is a pointer to the
  /// function:
  /// kmp_int32 .omp_task_entry.(kmp_int32 gtid, kmp_task_t *tt) {
  ///   TaskFunction(gtid, tt->part_id, tt->shareds);
  ///   return 0;
  /// }
  /// 2. Copy a list of shared variables to field shareds of the resulting
  /// structure kmp_task_t returned by the previous call (if any).
  /// 3. Copy a pointer to destructions function to field destructions of the
  /// resulting structure kmp_task_t.
  /// 4. Emit a call to void __kmpc_taskloop(ident_t *loc, int gtid, kmp_task_t
  /// *task, int if_val, kmp_uint64 *lb, kmp_uint64 *ub, kmp_int64 st, int
  /// nogroup, int sched, kmp_uint64 grainsize, void *task_dup ), where new_task
  /// is a resulting structure from
  /// previous items.
  /// \param D Current task directive.
  /// \param TaskFunction An LLVM function with type void (*)(i32 /*gtid*/, i32
  /// /*part_id*/, captured_struct */*__context*/);
  /// \param SharedsTy A type which contains references the shared variables.
  /// \param Shareds Context with the list of shared variables from the \p
  /// TaskFunction.
  /// \param IfCond Not a nullptr if 'if' clause was specified, nullptr
  /// otherwise.
  /// \param Data Additional data for task generation like tiednsee, final
  /// state, list of privates etc.
  virtual void emitTaskLoopCall(CodeGenFunction &CGF, SourceLocation Loc,
                                const OMPLoopDirective &D,
                                llvm::Function *TaskFunction,
                                QualType SharedsTy, Address Shareds,
                                const Expr *IfCond, const OMPTaskDataTy &Data);

  /// Emit code for the directive that does not require outlining.
  ///
  /// \param InnermostKind Kind of innermost directive (for simple directives it
  /// is a directive itself, for combined - its innermost directive).
  /// \param CodeGen Code generation sequence for the \a D directive.
  /// \param HasCancel true if region has inner cancel directive, false
  /// otherwise.
  virtual void emitInlinedDirective(CodeGenFunction &CGF,
                                    OpenMPDirectiveKind InnermostKind,
                                    const RegionCodeGenTy &CodeGen,
                                    bool HasCancel = false);

  /// Emits reduction function.
  /// \param ReducerName Name of the function calling the reduction.
  /// \param ArgsElemType Array type containing pointers to reduction variables.
  /// \param Privates List of private copies for original reduction arguments.
  /// \param LHSExprs List of LHS in \a ReductionOps reduction operations.
  /// \param RHSExprs List of RHS in \a ReductionOps reduction operations.
  /// \param ReductionOps List of reduction operations in form 'LHS binop RHS'
  /// or 'operator binop(LHS, RHS)'.
  llvm::Function *emitReductionFunction(
      StringRef ReducerName, SourceLocation Loc, llvm::Type *ArgsElemType,
      ArrayRef<const Expr *> Privates, ArrayRef<const Expr *> LHSExprs,
      ArrayRef<const Expr *> RHSExprs, ArrayRef<const Expr *> ReductionOps);

  /// Emits single reduction combiner
  void emitSingleReductionCombiner(CodeGenFunction &CGF,
                                   const Expr *ReductionOp,
                                   const Expr *PrivateRef,
                                   const DeclRefExpr *LHS,
                                   const DeclRefExpr *RHS);

  struct ReductionOptionsTy {
    bool WithNowait;
    bool SimpleReduction;
    OpenMPDirectiveKind ReductionKind;
  };
  /// Emit a code for reduction clause. Next code should be emitted for
  /// reduction:
  /// \code
  ///
  /// static kmp_critical_name lock = { 0 };
  ///
  /// void reduce_func(void *lhs[<n>], void *rhs[<n>]) {
  ///  ...
  ///  *(Type<i>*)lhs[i] = RedOp<i>(*(Type<i>*)lhs[i], *(Type<i>*)rhs[i]);
  ///  ...
  /// }
  ///
  /// ...
  /// void *RedList[<n>] = {&<RHSExprs>[0], ..., &<RHSExprs>[<n>-1]};
  /// switch (__kmpc_reduce{_nowait}(<loc>, <gtid>, <n>, sizeof(RedList),
  /// RedList, reduce_func, &<lock>)) {
  /// case 1:
  ///  ...
  ///  <LHSExprs>[i] = RedOp<i>(*<LHSExprs>[i], *<RHSExprs>[i]);
  ///  ...
  /// __kmpc_end_reduce{_nowait}(<loc>, <gtid>, &<lock>);
  /// break;
  /// case 2:
  ///  ...
  ///  Atomic(<LHSExprs>[i] = RedOp<i>(*<LHSExprs>[i], *<RHSExprs>[i]));
  ///  ...
  /// break;
  /// default:;
  /// }
  /// \endcode
  ///
  /// \param Privates List of private copies for original reduction arguments.
  /// \param LHSExprs List of LHS in \a ReductionOps reduction operations.
  /// \param RHSExprs List of RHS in \a ReductionOps reduction operations.
  /// \param ReductionOps List of reduction operations in form 'LHS binop RHS'
  /// or 'operator binop(LHS, RHS)'.
  /// \param Options List of options for reduction codegen:
  ///     WithNowait true if parent directive has also nowait clause, false
  ///     otherwise.
  ///     SimpleReduction Emit reduction operation only. Used for omp simd
  ///     directive on the host.
  ///     ReductionKind The kind of reduction to perform.
  virtual void emitReduction(CodeGenFunction &CGF, SourceLocation Loc,
                             ArrayRef<const Expr *> Privates,
                             ArrayRef<const Expr *> LHSExprs,
                             ArrayRef<const Expr *> RHSExprs,
                             ArrayRef<const Expr *> ReductionOps,
                             ReductionOptionsTy Options);

  /// Emit a code for initialization of task reduction clause. Next code
  /// should be emitted for reduction:
  /// \code
  ///
  /// _taskred_item_t red_data[n];
  /// ...
  /// red_data[i].shar = &shareds[i];
  /// red_data[i].orig = &origs[i];
  /// red_data[i].size = sizeof(origs[i]);
  /// red_data[i].f_init = (void*)RedInit<i>;
  /// red_data[i].f_fini = (void*)RedDest<i>;
  /// red_data[i].f_comb = (void*)RedOp<i>;
  /// red_data[i].flags = <Flag_i>;
  /// ...
  /// void* tg1 = __kmpc_taskred_init(gtid, n, red_data);
  /// \endcode
  /// For reduction clause with task modifier it emits the next call:
  /// \code
  ///
  /// _taskred_item_t red_data[n];
  /// ...
  /// red_data[i].shar = &shareds[i];
  /// red_data[i].orig = &origs[i];
  /// red_data[i].size = sizeof(origs[i]);
  /// red_data[i].f_init = (void*)RedInit<i>;
  /// red_data[i].f_fini = (void*)RedDest<i>;
  /// red_data[i].f_comb = (void*)RedOp<i>;
  /// red_data[i].flags = <Flag_i>;
  /// ...
  /// void* tg1 = __kmpc_taskred_modifier_init(loc, gtid, is_worksharing, n,
  /// red_data);
  /// \endcode
  /// \param LHSExprs List of LHS in \a Data.ReductionOps reduction operations.
  /// \param RHSExprs List of RHS in \a Data.ReductionOps reduction operations.
  /// \param Data Additional data for task generation like tiedness, final
  /// state, list of privates, reductions etc.
  virtual llvm::Value *emitTaskReductionInit(CodeGenFunction &CGF,
                                             SourceLocation Loc,
                                             ArrayRef<const Expr *> LHSExprs,
                                             ArrayRef<const Expr *> RHSExprs,
                                             const OMPTaskDataTy &Data);

  /// Emits the following code for reduction clause with task modifier:
  /// \code
  /// __kmpc_task_reduction_modifier_fini(loc, gtid, is_worksharing);
  /// \endcode
  virtual void emitTaskReductionFini(CodeGenFunction &CGF, SourceLocation Loc,
                                     bool IsWorksharingReduction);

  /// Required to resolve existing problems in the runtime. Emits threadprivate
  /// variables to store the size of the VLAs/array sections for
  /// initializer/combiner/finalizer functions.
  /// \param RCG Allows to reuse an existing data for the reductions.
  /// \param N Reduction item for which fixups must be emitted.
  virtual void emitTaskReductionFixups(CodeGenFunction &CGF, SourceLocation Loc,
                                       ReductionCodeGen &RCG, unsigned N);

  /// Get the address of `void *` type of the privatue copy of the reduction
  /// item specified by the \p SharedLVal.
  /// \param ReductionsPtr Pointer to the reduction data returned by the
  /// emitTaskReductionInit function.
  /// \param SharedLVal Address of the original reduction item.
  virtual Address getTaskReductionItem(CodeGenFunction &CGF, SourceLocation Loc,
                                       llvm::Value *ReductionsPtr,
                                       LValue SharedLVal);

  /// Emit code for 'taskwait' directive.
  virtual void emitTaskwaitCall(CodeGenFunction &CGF, SourceLocation Loc,
                                const OMPTaskDataTy &Data);

  /// Emit code for 'cancellation point' construct.
  /// \param CancelRegion Region kind for which the cancellation point must be
  /// emitted.
  ///
  virtual void emitCancellationPointCall(CodeGenFunction &CGF,
                                         SourceLocation Loc,
                                         OpenMPDirectiveKind CancelRegion);

  /// Emit code for 'cancel' construct.
  /// \param IfCond Condition in the associated 'if' clause, if it was
  /// specified, nullptr otherwise.
  /// \param CancelRegion Region kind for which the cancel must be emitted.
  ///
  virtual void emitCancelCall(CodeGenFunction &CGF, SourceLocation Loc,
                              const Expr *IfCond,
                              OpenMPDirectiveKind CancelRegion);

  /// Emit outilined function for 'target' directive.
  /// \param D Directive to emit.
  /// \param ParentName Name of the function that encloses the target region.
  /// \param OutlinedFn Outlined function value to be defined by this call.
  /// \param OutlinedFnID Outlined function ID value to be defined by this call.
  /// \param IsOffloadEntry True if the outlined function is an offload entry.
  /// \param CodeGen Code generation sequence for the \a D directive.
  /// An outlined function may not be an entry if, e.g. the if clause always
  /// evaluates to false.
  virtual void emitTargetOutlinedFunction(const OMPExecutableDirective &D,
                                          StringRef ParentName,
                                          llvm::Function *&OutlinedFn,
                                          llvm::Constant *&OutlinedFnID,
                                          bool IsOffloadEntry,
                                          const RegionCodeGenTy &CodeGen);

  /// Emit the target offloading code associated with \a D. The emitted
  /// code attempts offloading the execution to the device, an the event of
  /// a failure it executes the host version outlined in \a OutlinedFn.
  /// \param D Directive to emit.
  /// \param OutlinedFn Host version of the code to be offloaded.
  /// \param OutlinedFnID ID of host version of the code to be offloaded.
  /// \param IfCond Expression evaluated in if clause associated with the target
  /// directive, or null if no if clause is used.
  /// \param Device Expression evaluated in device clause associated with the
  /// target directive, or null if no device clause is used and device modifier.
  /// \param SizeEmitter Callback to emit number of iterations for loop-based
  /// directives.
  virtual void emitTargetCall(
      CodeGenFunction &CGF, const OMPExecutableDirective &D,
      llvm::Function *OutlinedFn, llvm::Value *OutlinedFnID, const Expr *IfCond,
      llvm::PointerIntPair<const Expr *, 2, OpenMPDeviceClauseModifier> Device,
      llvm::function_ref<llvm::Value *(CodeGenFunction &CGF,
                                       const OMPLoopDirective &D)>
          SizeEmitter);

  /// Emit the target regions enclosed in \a GD function definition or
  /// the function itself in case it is a valid device function. Returns true if
  /// \a GD was dealt with successfully.
  /// \param GD Function to scan.
  virtual bool emitTargetFunctions(GlobalDecl GD);

  /// Emit the global variable if it is a valid device global variable.
  /// Returns true if \a GD was dealt with successfully.
  /// \param GD Variable declaration to emit.
  virtual bool emitTargetGlobalVariable(GlobalDecl GD);

  /// Checks if the provided global decl \a GD is a declare target variable and
  /// registers it when emitting code for the host.
  virtual void registerTargetGlobalVariable(const VarDecl *VD,
                                            llvm::Constant *Addr);

  /// Emit the global \a GD if it is meaningful for the target. Returns
  /// if it was emitted successfully.
  /// \param GD Global to scan.
  virtual bool emitTargetGlobal(GlobalDecl GD);

  /// Creates and returns a registration function for when at least one
  /// requires directives was used in the current module.
  llvm::Function *emitRequiresDirectiveRegFun();

  /// Creates all the offload entries in the current compilation unit
  /// along with the associated metadata.
  void createOffloadEntriesAndInfoMetadata();

  /// Emits code for teams call of the \a OutlinedFn with
  /// variables captured in a record which address is stored in \a
  /// CapturedStruct.
  /// \param OutlinedFn Outlined function to be run by team masters. Type of
  /// this function is void(*)(kmp_int32 *, kmp_int32, struct context_vars*).
  /// \param CapturedVars A pointer to the record with the references to
  /// variables used in \a OutlinedFn function.
  ///
  virtual void emitTeamsCall(CodeGenFunction &CGF,
                             const OMPExecutableDirective &D,
                             SourceLocation Loc, llvm::Function *OutlinedFn,
                             ArrayRef<llvm::Value *> CapturedVars);

  /// Emits call to void __kmpc_push_num_teams(ident_t *loc, kmp_int32
  /// global_tid, kmp_int32 num_teams, kmp_int32 thread_limit) to generate code
  /// for num_teams clause.
  /// \param NumTeams An integer expression of teams.
  /// \param ThreadLimit An integer expression of threads.
  virtual void emitNumTeamsClause(CodeGenFunction &CGF, const Expr *NumTeams,
                                  const Expr *ThreadLimit, SourceLocation Loc);

  /// Emits call to void __kmpc_set_thread_limit(ident_t *loc, kmp_int32
  /// global_tid, kmp_int32 thread_limit) to generate code for
  /// thread_limit clause on target directive
  /// \param ThreadLimit An integer expression of threads.
  virtual void emitThreadLimitClause(CodeGenFunction &CGF,
                                     const Expr *ThreadLimit,
                                     SourceLocation Loc);

  /// Struct that keeps all the relevant information that should be kept
  /// throughout a 'target data' region.
  class TargetDataInfo : public llvm::OpenMPIRBuilder::TargetDataInfo {
  public:
    explicit TargetDataInfo() : llvm::OpenMPIRBuilder::TargetDataInfo() {}
    explicit TargetDataInfo(bool RequiresDevicePointerInfo,
                            bool SeparateBeginEndCalls)
        : llvm::OpenMPIRBuilder::TargetDataInfo(RequiresDevicePointerInfo,
                                                SeparateBeginEndCalls) {}
    /// Map between the a declaration of a capture and the corresponding new
    /// llvm address where the runtime returns the device pointers.
    llvm::DenseMap<const ValueDecl *, llvm::Value *> CaptureDeviceAddrMap;
  };

  /// Emit the target data mapping code associated with \a D.
  /// \param D Directive to emit.
  /// \param IfCond Expression evaluated in if clause associated with the
  /// target directive, or null if no device clause is used.
  /// \param Device Expression evaluated in device clause associated with the
  /// target directive, or null if no device clause is used.
  /// \param Info A record used to store information that needs to be preserved
  /// until the region is closed.
  virtual void emitTargetDataCalls(CodeGenFunction &CGF,
                                   const OMPExecutableDirective &D,
                                   const Expr *IfCond, const Expr *Device,
                                   const RegionCodeGenTy &CodeGen,
                                   CGOpenMPRuntime::TargetDataInfo &Info);

  /// Emit the data mapping/movement code associated with the directive
  /// \a D that should be of the form 'target [{enter|exit} data | update]'.
  /// \param D Directive to emit.
  /// \param IfCond Expression evaluated in if clause associated with the target
  /// directive, or null if no if clause is used.
  /// \param Device Expression evaluated in device clause associated with the
  /// target directive, or null if no device clause is used.
  virtual void emitTargetDataStandAloneCall(CodeGenFunction &CGF,
                                            const OMPExecutableDirective &D,
                                            const Expr *IfCond,
                                            const Expr *Device);

  /// Marks function \a Fn with properly mangled versions of vector functions.
  /// \param FD Function marked as 'declare simd'.
  /// \param Fn LLVM function that must be marked with 'declare simd'
  /// attributes.
  virtual void emitDeclareSimdFunction(const FunctionDecl *FD,
                                       llvm::Function *Fn);

  /// Emit initialization for doacross loop nesting support.
  /// \param D Loop-based construct used in doacross nesting construct.
  virtual void emitDoacrossInit(CodeGenFunction &CGF, const OMPLoopDirective &D,
                                ArrayRef<Expr *> NumIterations);

  /// Emit code for doacross ordered directive with 'depend' clause.
  /// \param C 'depend' clause with 'sink|source' dependency kind.
  virtual void emitDoacrossOrdered(CodeGenFunction &CGF,
                                   const OMPDependClause *C);

  /// Emit code for doacross ordered directive with 'doacross' clause.
  /// \param C 'doacross' clause with 'sink|source' dependence type.
  virtual void emitDoacrossOrdered(CodeGenFunction &CGF,
                                   const OMPDoacrossClause *C);

  /// Translates the native parameter of outlined function if this is required
  /// for target.
  /// \param FD Field decl from captured record for the parameter.
  /// \param NativeParam Parameter itself.
  virtual const VarDecl *translateParameter(const FieldDecl *FD,
                                            const VarDecl *NativeParam) const {
    return NativeParam;
  }

  /// Gets the address of the native argument basing on the address of the
  /// target-specific parameter.
  /// \param NativeParam Parameter itself.
  /// \param TargetParam Corresponding target-specific parameter.
  virtual Address getParameterAddress(CodeGenFunction &CGF,
                                      const VarDecl *NativeParam,
                                      const VarDecl *TargetParam) const;

  /// Choose default schedule type and chunk value for the
  /// dist_schedule clause.
  virtual void getDefaultDistScheduleAndChunk(CodeGenFunction &CGF,
      const OMPLoopDirective &S, OpenMPDistScheduleClauseKind &ScheduleKind,
      llvm::Value *&Chunk) const {}

  /// Choose default schedule type and chunk value for the
  /// schedule clause.
  virtual void getDefaultScheduleAndChunk(CodeGenFunction &CGF,
      const OMPLoopDirective &S, OpenMPScheduleClauseKind &ScheduleKind,
      const Expr *&ChunkExpr) const;

  /// Emits call of the outlined function with the provided arguments,
  /// translating these arguments to correct target-specific arguments.
  virtual void
  emitOutlinedFunctionCall(CodeGenFunction &CGF, SourceLocation Loc,
                           llvm::FunctionCallee OutlinedFn,
                           ArrayRef<llvm::Value *> Args = std::nullopt) const;

  /// Emits OpenMP-specific function prolog.
  /// Required for device constructs.
  virtual void emitFunctionProlog(CodeGenFunction &CGF, const Decl *D);

  /// Gets the OpenMP-specific address of the local variable.
  virtual Address getAddressOfLocalVariable(CodeGenFunction &CGF,
                                            const VarDecl *VD);

  /// Marks the declaration as already emitted for the device code and returns
  /// true, if it was marked already, and false, otherwise.
  bool markAsGlobalTarget(GlobalDecl GD);

  /// Emit deferred declare target variables marked for deferred emission.
  void emitDeferredTargetDecls() const;

  /// Adjust some parameters for the target-based directives, like addresses of
  /// the variables captured by reference in lambdas.
  virtual void
  adjustTargetSpecificDataForLambdas(CodeGenFunction &CGF,
                                     const OMPExecutableDirective &D) const;

  /// Perform check on requires decl to ensure that target architecture
  /// supports unified addressing
  virtual void processRequiresDirective(const OMPRequiresDecl *D);

  /// Gets default memory ordering as specified in requires directive.
  llvm::AtomicOrdering getDefaultMemoryOrdering() const;

  /// Checks if the variable has associated OMPAllocateDeclAttr attribute with
  /// the predefined allocator and translates it into the corresponding address
  /// space.
  virtual bool hasAllocateAttributeForGlobalVar(const VarDecl *VD, LangAS &AS);

  /// Return whether the unified_shared_memory has been specified.
  bool hasRequiresUnifiedSharedMemory() const;

  /// Checks if the \p VD variable is marked as nontemporal declaration in
  /// current context.
  bool isNontemporalDecl(const ValueDecl *VD) const;

  /// Create specialized alloca to handle lastprivate conditionals.
  Address emitLastprivateConditionalInit(CodeGenFunction &CGF,
                                         const VarDecl *VD);

  /// Checks if the provided \p LVal is lastprivate conditional and emits the
  /// code to update the value of the original variable.
  /// \code
  /// lastprivate(conditional: a)
  /// ...
  /// <type> a;
  /// lp_a = ...;
  /// #pragma omp critical(a)
  /// if (last_iv_a <= iv) {
  ///   last_iv_a = iv;
  ///   global_a = lp_a;
  /// }
  /// \endcode
  virtual void checkAndEmitLastprivateConditional(CodeGenFunction &CGF,
                                                  const Expr *LHS);

  /// Checks if the lastprivate conditional was updated in inner region and
  /// writes the value.
  /// \code
  /// lastprivate(conditional: a)
  /// ...
  /// <type> a;bool Fired = false;
  /// #pragma omp ... shared(a)
  /// {
  ///   lp_a = ...;
  ///   Fired = true;
  /// }
  /// if (Fired) {
  ///   #pragma omp critical(a)
  ///   if (last_iv_a <= iv) {
  ///     last_iv_a = iv;
  ///     global_a = lp_a;
  ///   }
  ///   Fired = false;
  /// }
  /// \endcode
  virtual void checkAndEmitSharedLastprivateConditional(
      CodeGenFunction &CGF, const OMPExecutableDirective &D,
      const llvm::DenseSet<CanonicalDeclPtr<const VarDecl>> &IgnoredDecls);

  /// Gets the address of the global copy used for lastprivate conditional
  /// update, if any.
  /// \param PrivLVal LValue for the private copy.
  /// \param VD Original lastprivate declaration.
  virtual void emitLastprivateConditionalFinalUpdate(CodeGenFunction &CGF,
                                                     LValue PrivLVal,
                                                     const VarDecl *VD,
                                                     SourceLocation Loc);

  /// Emits list of dependecies based on the provided data (array of
  /// dependence/expression pairs).
  /// \returns Pointer to the first element of the array casted to VoidPtr type.
  std::pair<llvm::Value *, Address>
  emitDependClause(CodeGenFunction &CGF,
                   ArrayRef<OMPTaskDataTy::DependData> Dependencies,
                   SourceLocation Loc);

  /// Emits list of dependecies based on the provided data (array of
  /// dependence/expression pairs) for depobj construct. In this case, the
  /// variable is allocated in dynamically. \returns Pointer to the first
  /// element of the array casted to VoidPtr type.
  Address emitDepobjDependClause(CodeGenFunction &CGF,
                                 const OMPTaskDataTy::DependData &Dependencies,
                                 SourceLocation Loc);

  /// Emits the code to destroy the dependency object provided in depobj
  /// directive.
  void emitDestroyClause(CodeGenFunction &CGF, LValue DepobjLVal,
                         SourceLocation Loc);

  /// Updates the dependency kind in the specified depobj object.
  /// \param DepobjLVal LValue for the main depobj object.
  /// \param NewDepKind New dependency kind.
  void emitUpdateClause(CodeGenFunction &CGF, LValue DepobjLVal,
                        OpenMPDependClauseKind NewDepKind, SourceLocation Loc);

  /// Initializes user defined allocators specified in the uses_allocators
  /// clauses.
  void emitUsesAllocatorsInit(CodeGenFunction &CGF, const Expr *Allocator,
                              const Expr *AllocatorTraits);

  /// Destroys user defined allocators specified in the uses_allocators clause.
  void emitUsesAllocatorsFini(CodeGenFunction &CGF, const Expr *Allocator);

  /// Returns true if the variable is a local variable in untied task.
  bool isLocalVarInUntiedTask(CodeGenFunction &CGF, const VarDecl *VD) const;
};

/// Class supports emissionof SIMD-only code.
class CGOpenMPSIMDRuntime final : public CGOpenMPRuntime {
public:
  explicit CGOpenMPSIMDRuntime(CodeGenModule &CGM) : CGOpenMPRuntime(CGM) {}
  ~CGOpenMPSIMDRuntime() override {}

  /// Emits outlined function for the specified OpenMP parallel directive
  /// \a D. This outlined function has type void(*)(kmp_int32 *ThreadID,
  /// kmp_int32 BoundID, struct context_vars*).
  /// \param CGF Reference to current CodeGenFunction.
  /// \param D OpenMP directive.
  /// \param ThreadIDVar Variable for thread id in the current OpenMP region.
  /// \param InnermostKind Kind of innermost directive (for simple directives it
  /// is a directive itself, for combined - its innermost directive).
  /// \param CodeGen Code generation sequence for the \a D directive.
  llvm::Function *emitParallelOutlinedFunction(
      CodeGenFunction &CGF, const OMPExecutableDirective &D,
      const VarDecl *ThreadIDVar, OpenMPDirectiveKind InnermostKind,
      const RegionCodeGenTy &CodeGen) override;

  /// Emits outlined function for the specified OpenMP teams directive
  /// \a D. This outlined function has type void(*)(kmp_int32 *ThreadID,
  /// kmp_int32 BoundID, struct context_vars*).
  /// \param CGF Reference to current CodeGenFunction.
  /// \param D OpenMP directive.
  /// \param ThreadIDVar Variable for thread id in the current OpenMP region.
  /// \param InnermostKind Kind of innermost directive (for simple directives it
  /// is a directive itself, for combined - its innermost directive).
  /// \param CodeGen Code generation sequence for the \a D directive.
  llvm::Function *emitTeamsOutlinedFunction(
      CodeGenFunction &CGF, const OMPExecutableDirective &D,
      const VarDecl *ThreadIDVar, OpenMPDirectiveKind InnermostKind,
      const RegionCodeGenTy &CodeGen) override;

  /// Emits outlined function for the OpenMP task directive \a D. This
  /// outlined function has type void(*)(kmp_int32 ThreadID, struct task_t*
  /// TaskT).
  /// \param D OpenMP directive.
  /// \param ThreadIDVar Variable for thread id in the current OpenMP region.
  /// \param PartIDVar Variable for partition id in the current OpenMP untied
  /// task region.
  /// \param TaskTVar Variable for task_t argument.
  /// \param InnermostKind Kind of innermost directive (for simple directives it
  /// is a directive itself, for combined - its innermost directive).
  /// \param CodeGen Code generation sequence for the \a D directive.
  /// \param Tied true if task is generated for tied task, false otherwise.
  /// \param NumberOfParts Number of parts in untied task. Ignored for tied
  /// tasks.
  ///
  llvm::Function *emitTaskOutlinedFunction(
      const OMPExecutableDirective &D, const VarDecl *ThreadIDVar,
      const VarDecl *PartIDVar, const VarDecl *TaskTVar,
      OpenMPDirectiveKind InnermostKind, const RegionCodeGenTy &CodeGen,
      bool Tied, unsigned &NumberOfParts) override;

  /// Emits code for parallel or serial call of the \a OutlinedFn with
  /// variables captured in a record which address is stored in \a
  /// CapturedStruct.
  /// \param OutlinedFn Outlined function to be run in parallel threads. Type of
  /// this function is void(*)(kmp_int32 *, kmp_int32, struct context_vars*).
  /// \param CapturedVars A pointer to the record with the references to
  /// variables used in \a OutlinedFn function.
  /// \param IfCond Condition in the associated 'if' clause, if it was
  /// specified, nullptr otherwise.
  /// \param NumThreads The value corresponding to the num_threads clause, if
  /// any, or nullptr.
  ///
  void emitParallelCall(CodeGenFunction &CGF, SourceLocation Loc,
                        llvm::Function *OutlinedFn,
                        ArrayRef<llvm::Value *> CapturedVars,
                        const Expr *IfCond, llvm::Value *NumThreads) override;

  /// Emits a critical region.
  /// \param CriticalName Name of the critical region.
  /// \param CriticalOpGen Generator for the statement associated with the given
  /// critical region.
  /// \param Hint Value of the 'hint' clause (optional).
  void emitCriticalRegion(CodeGenFunction &CGF, StringRef CriticalName,
                          const RegionCodeGenTy &CriticalOpGen,
                          SourceLocation Loc,
                          const Expr *Hint = nullptr) override;

  /// Emits a master region.
  /// \param MasterOpGen Generator for the statement associated with the given
  /// master region.
  void emitMasterRegion(CodeGenFunction &CGF,
                        const RegionCodeGenTy &MasterOpGen,
                        SourceLocation Loc) override;

  /// Emits a masked region.
  /// \param MaskedOpGen Generator for the statement associated with the given
  /// masked region.
  void emitMaskedRegion(CodeGenFunction &CGF,
                        const RegionCodeGenTy &MaskedOpGen, SourceLocation Loc,
                        const Expr *Filter = nullptr) override;

  /// Emits a masked region.
  /// \param MaskedOpGen Generator for the statement associated with the given
  /// masked region.

  /// Emits code for a taskyield directive.
  void emitTaskyieldCall(CodeGenFunction &CGF, SourceLocation Loc) override;

  /// Emit a taskgroup region.
  /// \param TaskgroupOpGen Generator for the statement associated with the
  /// given taskgroup region.
  void emitTaskgroupRegion(CodeGenFunction &CGF,
                           const RegionCodeGenTy &TaskgroupOpGen,
                           SourceLocation Loc) override;

  /// Emits a single region.
  /// \param SingleOpGen Generator for the statement associated with the given
  /// single region.
  void emitSingleRegion(CodeGenFunction &CGF,
                        const RegionCodeGenTy &SingleOpGen, SourceLocation Loc,
                        ArrayRef<const Expr *> CopyprivateVars,
                        ArrayRef<const Expr *> DestExprs,
                        ArrayRef<const Expr *> SrcExprs,
                        ArrayRef<const Expr *> AssignmentOps) override;

  /// Emit an ordered region.
  /// \param OrderedOpGen Generator for the statement associated with the given
  /// ordered region.
  void emitOrderedRegion(CodeGenFunction &CGF,
                         const RegionCodeGenTy &OrderedOpGen,
                         SourceLocation Loc, bool IsThreads) override;

  /// Emit an implicit/explicit barrier for OpenMP threads.
  /// \param Kind Directive for which this implicit barrier call must be
  /// generated. Must be OMPD_barrier for explicit barrier generation.
  /// \param EmitChecks true if need to emit checks for cancellation barriers.
  /// \param ForceSimpleCall true simple barrier call must be emitted, false if
  /// runtime class decides which one to emit (simple or with cancellation
  /// checks).
  ///
  void emitBarrierCall(CodeGenFunction &CGF, SourceLocation Loc,
                       OpenMPDirectiveKind Kind, bool EmitChecks = true,
                       bool ForceSimpleCall = false) override;

  /// This is used for non static scheduled types and when the ordered
  /// clause is present on the loop construct.
  /// Depending on the loop schedule, it is necessary to call some runtime
  /// routine before start of the OpenMP loop to get the loop upper / lower
  /// bounds \a LB and \a UB and stride \a ST.
  ///
  /// \param CGF Reference to current CodeGenFunction.
  /// \param Loc Clang source location.
  /// \param ScheduleKind Schedule kind, specified by the 'schedule' clause.
  /// \param IVSize Size of the iteration variable in bits.
  /// \param IVSigned Sign of the iteration variable.
  /// \param Ordered true if loop is ordered, false otherwise.
  /// \param DispatchValues struct containing llvm values for lower bound, upper
  /// bound, and chunk expression.
  /// For the default (nullptr) value, the chunk 1 will be used.
  ///
  void emitForDispatchInit(CodeGenFunction &CGF, SourceLocation Loc,
                           const OpenMPScheduleTy &ScheduleKind,
                           unsigned IVSize, bool IVSigned, bool Ordered,
                           const DispatchRTInput &DispatchValues) override;

  /// Call the appropriate runtime routine to initialize it before start
  /// of loop.
  ///
  /// This is used only in case of static schedule, when the user did not
  /// specify a ordered clause on the loop construct.
  /// Depending on the loop schedule, it is necessary to call some runtime
  /// routine before start of the OpenMP loop to get the loop upper / lower
  /// bounds LB and UB and stride ST.
  ///
  /// \param CGF Reference to current CodeGenFunction.
  /// \param Loc Clang source location.
  /// \param DKind Kind of the directive.
  /// \param ScheduleKind Schedule kind, specified by the 'schedule' clause.
  /// \param Values Input arguments for the construct.
  ///
  void emitForStaticInit(CodeGenFunction &CGF, SourceLocation Loc,
                         OpenMPDirectiveKind DKind,
                         const OpenMPScheduleTy &ScheduleKind,
                         const StaticRTInput &Values) override;

  ///
  /// \param CGF Reference to current CodeGenFunction.
  /// \param Loc Clang source location.
  /// \param SchedKind Schedule kind, specified by the 'dist_schedule' clause.
  /// \param Values Input arguments for the construct.
  ///
  void emitDistributeStaticInit(CodeGenFunction &CGF, SourceLocation Loc,
                                OpenMPDistScheduleClauseKind SchedKind,
                                const StaticRTInput &Values) override;

  /// Call the appropriate runtime routine to notify that we finished
  /// iteration of the ordered loop with the dynamic scheduling.
  ///
  /// \param CGF Reference to current CodeGenFunction.
  /// \param Loc Clang source location.
  /// \param IVSize Size of the iteration variable in bits.
  /// \param IVSigned Sign of the iteration variable.
  ///
  void emitForOrderedIterationEnd(CodeGenFunction &CGF, SourceLocation Loc,
                                  unsigned IVSize, bool IVSigned) override;

  /// Call the appropriate runtime routine to notify that we finished
  /// all the work with current loop.
  ///
  /// \param CGF Reference to current CodeGenFunction.
  /// \param Loc Clang source location.
  /// \param DKind Kind of the directive for which the static finish is emitted.
  ///
  void emitForStaticFinish(CodeGenFunction &CGF, SourceLocation Loc,
                           OpenMPDirectiveKind DKind) override;

  /// Call __kmpc_dispatch_next(
  ///          ident_t *loc, kmp_int32 tid, kmp_int32 *p_lastiter,
  ///          kmp_int[32|64] *p_lower, kmp_int[32|64] *p_upper,
  ///          kmp_int[32|64] *p_stride);
  /// \param IVSize Size of the iteration variable in bits.
  /// \param IVSigned Sign of the iteration variable.
  /// \param IL Address of the output variable in which the flag of the
  /// last iteration is returned.
  /// \param LB Address of the output variable in which the lower iteration
  /// number is returned.
  /// \param UB Address of the output variable in which the upper iteration
  /// number is returned.
  /// \param ST Address of the output variable in which the stride value is
  /// returned.
  llvm::Value *emitForNext(CodeGenFunction &CGF, SourceLocation Loc,
                           unsigned IVSize, bool IVSigned, Address IL,
                           Address LB, Address UB, Address ST) override;

  /// Emits call to void __kmpc_push_num_threads(ident_t *loc, kmp_int32
  /// global_tid, kmp_int32 num_threads) to generate code for 'num_threads'
  /// clause.
  /// \param NumThreads An integer value of threads.
  void emitNumThreadsClause(CodeGenFunction &CGF, llvm::Value *NumThreads,
                            SourceLocation Loc) override;

  /// Emit call to void __kmpc_push_proc_bind(ident_t *loc, kmp_int32
  /// global_tid, int proc_bind) to generate code for 'proc_bind' clause.
  void emitProcBindClause(CodeGenFunction &CGF,
                          llvm::omp::ProcBindKind ProcBind,
                          SourceLocation Loc) override;

  /// Returns address of the threadprivate variable for the current
  /// thread.
  /// \param VD Threadprivate variable.
  /// \param VDAddr Address of the global variable \a VD.
  /// \param Loc Location of the reference to threadprivate var.
  /// \return Address of the threadprivate variable for the current thread.
  Address getAddrOfThreadPrivate(CodeGenFunction &CGF, const VarDecl *VD,
                                 Address VDAddr, SourceLocation Loc) override;

  /// Emit a code for initialization of threadprivate variable. It emits
  /// a call to runtime library which adds initial value to the newly created
  /// threadprivate variable (if it is not constant) and registers destructor
  /// for the variable (if any).
  /// \param VD Threadprivate variable.
  /// \param VDAddr Address of the global variable \a VD.
  /// \param Loc Location of threadprivate declaration.
  /// \param PerformInit true if initialization expression is not constant.
  llvm::Function *
  emitThreadPrivateVarDefinition(const VarDecl *VD, Address VDAddr,
                                 SourceLocation Loc, bool PerformInit,
                                 CodeGenFunction *CGF = nullptr) override;

  /// Creates artificial threadprivate variable with name \p Name and type \p
  /// VarType.
  /// \param VarType Type of the artificial threadprivate variable.
  /// \param Name Name of the artificial threadprivate variable.
  Address getAddrOfArtificialThreadPrivate(CodeGenFunction &CGF,
                                           QualType VarType,
                                           StringRef Name) override;

  /// Emit flush of the variables specified in 'omp flush' directive.
  /// \param Vars List of variables to flush.
  void emitFlush(CodeGenFunction &CGF, ArrayRef<const Expr *> Vars,
                 SourceLocation Loc, llvm::AtomicOrdering AO) override;

  /// Emit task region for the task directive. The task region is
  /// emitted in several steps:
  /// 1. Emit a call to kmp_task_t *__kmpc_omp_task_alloc(ident_t *, kmp_int32
  /// gtid, kmp_int32 flags, size_t sizeof_kmp_task_t, size_t sizeof_shareds,
  /// kmp_routine_entry_t *task_entry). Here task_entry is a pointer to the
  /// function:
  /// kmp_int32 .omp_task_entry.(kmp_int32 gtid, kmp_task_t *tt) {
  ///   TaskFunction(gtid, tt->part_id, tt->shareds);
  ///   return 0;
  /// }
  /// 2. Copy a list of shared variables to field shareds of the resulting
  /// structure kmp_task_t returned by the previous call (if any).
  /// 3. Copy a pointer to destructions function to field destructions of the
  /// resulting structure kmp_task_t.
  /// 4. Emit a call to kmp_int32 __kmpc_omp_task(ident_t *, kmp_int32 gtid,
  /// kmp_task_t *new_task), where new_task is a resulting structure from
  /// previous items.
  /// \param D Current task directive.
  /// \param TaskFunction An LLVM function with type void (*)(i32 /*gtid*/, i32
  /// /*part_id*/, captured_struct */*__context*/);
  /// \param SharedsTy A type which contains references the shared variables.
  /// \param Shareds Context with the list of shared variables from the \p
  /// TaskFunction.
  /// \param IfCond Not a nullptr if 'if' clause was specified, nullptr
  /// otherwise.
  /// \param Data Additional data for task generation like tiednsee, final
  /// state, list of privates etc.
  void emitTaskCall(CodeGenFunction &CGF, SourceLocation Loc,
                    const OMPExecutableDirective &D,
                    llvm::Function *TaskFunction, QualType SharedsTy,
                    Address Shareds, const Expr *IfCond,
                    const OMPTaskDataTy &Data) override;

  /// Emit task region for the taskloop directive. The taskloop region is
  /// emitted in several steps:
  /// 1. Emit a call to kmp_task_t *__kmpc_omp_task_alloc(ident_t *, kmp_int32
  /// gtid, kmp_int32 flags, size_t sizeof_kmp_task_t, size_t sizeof_shareds,
  /// kmp_routine_entry_t *task_entry). Here task_entry is a pointer to the
  /// function:
  /// kmp_int32 .omp_task_entry.(kmp_int32 gtid, kmp_task_t *tt) {
  ///   TaskFunction(gtid, tt->part_id, tt->shareds);
  ///   return 0;
  /// }
  /// 2. Copy a list of shared variables to field shareds of the resulting
  /// structure kmp_task_t returned by the previous call (if any).
  /// 3. Copy a pointer to destructions function to field destructions of the
  /// resulting structure kmp_task_t.
  /// 4. Emit a call to void __kmpc_taskloop(ident_t *loc, int gtid, kmp_task_t
  /// *task, int if_val, kmp_uint64 *lb, kmp_uint64 *ub, kmp_int64 st, int
  /// nogroup, int sched, kmp_uint64 grainsize, void *task_dup ), where new_task
  /// is a resulting structure from
  /// previous items.
  /// \param D Current task directive.
  /// \param TaskFunction An LLVM function with type void (*)(i32 /*gtid*/, i32
  /// /*part_id*/, captured_struct */*__context*/);
  /// \param SharedsTy A type which contains references the shared variables.
  /// \param Shareds Context with the list of shared variables from the \p
  /// TaskFunction.
  /// \param IfCond Not a nullptr if 'if' clause was specified, nullptr
  /// otherwise.
  /// \param Data Additional data for task generation like tiednsee, final
  /// state, list of privates etc.
  void emitTaskLoopCall(CodeGenFunction &CGF, SourceLocation Loc,
                        const OMPLoopDirective &D, llvm::Function *TaskFunction,
                        QualType SharedsTy, Address Shareds, const Expr *IfCond,
                        const OMPTaskDataTy &Data) override;

  /// Emit a code for reduction clause. Next code should be emitted for
  /// reduction:
  /// \code
  ///
  /// static kmp_critical_name lock = { 0 };
  ///
  /// void reduce_func(void *lhs[<n>], void *rhs[<n>]) {
  ///  ...
  ///  *(Type<i>*)lhs[i] = RedOp<i>(*(Type<i>*)lhs[i], *(Type<i>*)rhs[i]);
  ///  ...
  /// }
  ///
  /// ...
  /// void *RedList[<n>] = {&<RHSExprs>[0], ..., &<RHSExprs>[<n>-1]};
  /// switch (__kmpc_reduce{_nowait}(<loc>, <gtid>, <n>, sizeof(RedList),
  /// RedList, reduce_func, &<lock>)) {
  /// case 1:
  ///  ...
  ///  <LHSExprs>[i] = RedOp<i>(*<LHSExprs>[i], *<RHSExprs>[i]);
  ///  ...
  /// __kmpc_end_reduce{_nowait}(<loc>, <gtid>, &<lock>);
  /// break;
  /// case 2:
  ///  ...
  ///  Atomic(<LHSExprs>[i] = RedOp<i>(*<LHSExprs>[i], *<RHSExprs>[i]));
  ///  ...
  /// break;
  /// default:;
  /// }
  /// \endcode
  ///
  /// \param Privates List of private copies for original reduction arguments.
  /// \param LHSExprs List of LHS in \a ReductionOps reduction operations.
  /// \param RHSExprs List of RHS in \a ReductionOps reduction operations.
  /// \param ReductionOps List of reduction operations in form 'LHS binop RHS'
  /// or 'operator binop(LHS, RHS)'.
  /// \param Options List of options for reduction codegen:
  ///     WithNowait true if parent directive has also nowait clause, false
  ///     otherwise.
  ///     SimpleReduction Emit reduction operation only. Used for omp simd
  ///     directive on the host.
  ///     ReductionKind The kind of reduction to perform.
  void emitReduction(CodeGenFunction &CGF, SourceLocation Loc,
                     ArrayRef<const Expr *> Privates,
                     ArrayRef<const Expr *> LHSExprs,
                     ArrayRef<const Expr *> RHSExprs,
                     ArrayRef<const Expr *> ReductionOps,
                     ReductionOptionsTy Options) override;

  /// Emit a code for initialization of task reduction clause. Next code
  /// should be emitted for reduction:
  /// \code
  ///
  /// _taskred_item_t red_data[n];
  /// ...
  /// red_data[i].shar = &shareds[i];
  /// red_data[i].orig = &origs[i];
  /// red_data[i].size = sizeof(origs[i]);
  /// red_data[i].f_init = (void*)RedInit<i>;
  /// red_data[i].f_fini = (void*)RedDest<i>;
  /// red_data[i].f_comb = (void*)RedOp<i>;
  /// red_data[i].flags = <Flag_i>;
  /// ...
  /// void* tg1 = __kmpc_taskred_init(gtid, n, red_data);
  /// \endcode
  /// For reduction clause with task modifier it emits the next call:
  /// \code
  ///
  /// _taskred_item_t red_data[n];
  /// ...
  /// red_data[i].shar = &shareds[i];
  /// red_data[i].orig = &origs[i];
  /// red_data[i].size = sizeof(origs[i]);
  /// red_data[i].f_init = (void*)RedInit<i>;
  /// red_data[i].f_fini = (void*)RedDest<i>;
  /// red_data[i].f_comb = (void*)RedOp<i>;
  /// red_data[i].flags = <Flag_i>;
  /// ...
  /// void* tg1 = __kmpc_taskred_modifier_init(loc, gtid, is_worksharing, n,
  /// red_data);
  /// \endcode
  /// \param LHSExprs List of LHS in \a Data.ReductionOps reduction operations.
  /// \param RHSExprs List of RHS in \a Data.ReductionOps reduction operations.
  /// \param Data Additional data for task generation like tiedness, final
  /// state, list of privates, reductions etc.
  llvm::Value *emitTaskReductionInit(CodeGenFunction &CGF, SourceLocation Loc,
                                     ArrayRef<const Expr *> LHSExprs,
                                     ArrayRef<const Expr *> RHSExprs,
                                     const OMPTaskDataTy &Data) override;

  /// Emits the following code for reduction clause with task modifier:
  /// \code
  /// __kmpc_task_reduction_modifier_fini(loc, gtid, is_worksharing);
  /// \endcode
  void emitTaskReductionFini(CodeGenFunction &CGF, SourceLocation Loc,
                             bool IsWorksharingReduction) override;

  /// Required to resolve existing problems in the runtime. Emits threadprivate
  /// variables to store the size of the VLAs/array sections for
  /// initializer/combiner/finalizer functions + emits threadprivate variable to
  /// store the pointer to the original reduction item for the custom
  /// initializer defined by declare reduction construct.
  /// \param RCG Allows to reuse an existing data for the reductions.
  /// \param N Reduction item for which fixups must be emitted.
  void emitTaskReductionFixups(CodeGenFunction &CGF, SourceLocation Loc,
                               ReductionCodeGen &RCG, unsigned N) override;

  /// Get the address of `void *` type of the privatue copy of the reduction
  /// item specified by the \p SharedLVal.
  /// \param ReductionsPtr Pointer to the reduction data returned by the
  /// emitTaskReductionInit function.
  /// \param SharedLVal Address of the original reduction item.
  Address getTaskReductionItem(CodeGenFunction &CGF, SourceLocation Loc,
                               llvm::Value *ReductionsPtr,
                               LValue SharedLVal) override;

  /// Emit code for 'taskwait' directive.
  void emitTaskwaitCall(CodeGenFunction &CGF, SourceLocation Loc,
                        const OMPTaskDataTy &Data) override;

  /// Emit code for 'cancellation point' construct.
  /// \param CancelRegion Region kind for which the cancellation point must be
  /// emitted.
  ///
  void emitCancellationPointCall(CodeGenFunction &CGF, SourceLocation Loc,
                                 OpenMPDirectiveKind CancelRegion) override;

  /// Emit code for 'cancel' construct.
  /// \param IfCond Condition in the associated 'if' clause, if it was
  /// specified, nullptr otherwise.
  /// \param CancelRegion Region kind for which the cancel must be emitted.
  ///
  void emitCancelCall(CodeGenFunction &CGF, SourceLocation Loc,
                      const Expr *IfCond,
                      OpenMPDirectiveKind CancelRegion) override;

  /// Emit outilined function for 'target' directive.
  /// \param D Directive to emit.
  /// \param ParentName Name of the function that encloses the target region.
  /// \param OutlinedFn Outlined function value to be defined by this call.
  /// \param OutlinedFnID Outlined function ID value to be defined by this call.
  /// \param IsOffloadEntry True if the outlined function is an offload entry.
  /// \param CodeGen Code generation sequence for the \a D directive.
  /// An outlined function may not be an entry if, e.g. the if clause always
  /// evaluates to false.
  void emitTargetOutlinedFunction(const OMPExecutableDirective &D,
                                  StringRef ParentName,
                                  llvm::Function *&OutlinedFn,
                                  llvm::Constant *&OutlinedFnID,
                                  bool IsOffloadEntry,
                                  const RegionCodeGenTy &CodeGen) override;

  /// Emit the target offloading code associated with \a D. The emitted
  /// code attempts offloading the execution to the device, an the event of
  /// a failure it executes the host version outlined in \a OutlinedFn.
  /// \param D Directive to emit.
  /// \param OutlinedFn Host version of the code to be offloaded.
  /// \param OutlinedFnID ID of host version of the code to be offloaded.
  /// \param IfCond Expression evaluated in if clause associated with the target
  /// directive, or null if no if clause is used.
  /// \param Device Expression evaluated in device clause associated with the
  /// target directive, or null if no device clause is used and device modifier.
  void emitTargetCall(
      CodeGenFunction &CGF, const OMPExecutableDirective &D,
      llvm::Function *OutlinedFn, llvm::Value *OutlinedFnID, const Expr *IfCond,
      llvm::PointerIntPair<const Expr *, 2, OpenMPDeviceClauseModifier> Device,
      llvm::function_ref<llvm::Value *(CodeGenFunction &CGF,
                                       const OMPLoopDirective &D)>
          SizeEmitter) override;

  /// Emit the target regions enclosed in \a GD function definition or
  /// the function itself in case it is a valid device function. Returns true if
  /// \a GD was dealt with successfully.
  /// \param GD Function to scan.
  bool emitTargetFunctions(GlobalDecl GD) override;

  /// Emit the global variable if it is a valid device global variable.
  /// Returns true if \a GD was dealt with successfully.
  /// \param GD Variable declaration to emit.
  bool emitTargetGlobalVariable(GlobalDecl GD) override;

  /// Emit the global \a GD if it is meaningful for the target. Returns
  /// if it was emitted successfully.
  /// \param GD Global to scan.
  bool emitTargetGlobal(GlobalDecl GD) override;

  /// Emits code for teams call of the \a OutlinedFn with
  /// variables captured in a record which address is stored in \a
  /// CapturedStruct.
  /// \param OutlinedFn Outlined function to be run by team masters. Type of
  /// this function is void(*)(kmp_int32 *, kmp_int32, struct context_vars*).
  /// \param CapturedVars A pointer to the record with the references to
  /// variables used in \a OutlinedFn function.
  ///
  void emitTeamsCall(CodeGenFunction &CGF, const OMPExecutableDirective &D,
                     SourceLocation Loc, llvm::Function *OutlinedFn,
                     ArrayRef<llvm::Value *> CapturedVars) override;

  /// Emits call to void __kmpc_push_num_teams(ident_t *loc, kmp_int32
  /// global_tid, kmp_int32 num_teams, kmp_int32 thread_limit) to generate code
  /// for num_teams clause.
  /// \param NumTeams An integer expression of teams.
  /// \param ThreadLimit An integer expression of threads.
  void emitNumTeamsClause(CodeGenFunction &CGF, const Expr *NumTeams,
                          const Expr *ThreadLimit, SourceLocation Loc) override;

  /// Emit the target data mapping code associated with \a D.
  /// \param D Directive to emit.
  /// \param IfCond Expression evaluated in if clause associated with the
  /// target directive, or null if no device clause is used.
  /// \param Device Expression evaluated in device clause associated with the
  /// target directive, or null if no device clause is used.
  /// \param Info A record used to store information that needs to be preserved
  /// until the region is closed.
  void emitTargetDataCalls(CodeGenFunction &CGF,
                           const OMPExecutableDirective &D, const Expr *IfCond,
                           const Expr *Device, const RegionCodeGenTy &CodeGen,
                           CGOpenMPRuntime::TargetDataInfo &Info) override;

  /// Emit the data mapping/movement code associated with the directive
  /// \a D that should be of the form 'target [{enter|exit} data | update]'.
  /// \param D Directive to emit.
  /// \param IfCond Expression evaluated in if clause associated with the target
  /// directive, or null if no if clause is used.
  /// \param Device Expression evaluated in device clause associated with the
  /// target directive, or null if no device clause is used.
  void emitTargetDataStandAloneCall(CodeGenFunction &CGF,
                                    const OMPExecutableDirective &D,
                                    const Expr *IfCond,
                                    const Expr *Device) override;

  /// Emit initialization for doacross loop nesting support.
  /// \param D Loop-based construct used in doacross nesting construct.
  void emitDoacrossInit(CodeGenFunction &CGF, const OMPLoopDirective &D,
                        ArrayRef<Expr *> NumIterations) override;

  /// Emit code for doacross ordered directive with 'depend' clause.
  /// \param C 'depend' clause with 'sink|source' dependency kind.
  void emitDoacrossOrdered(CodeGenFunction &CGF,
                           const OMPDependClause *C) override;

  /// Emit code for doacross ordered directive with 'doacross' clause.
  /// \param C 'doacross' clause with 'sink|source' dependence type.
  void emitDoacrossOrdered(CodeGenFunction &CGF,
                           const OMPDoacrossClause *C) override;

  /// Translates the native parameter of outlined function if this is required
  /// for target.
  /// \param FD Field decl from captured record for the parameter.
  /// \param NativeParam Parameter itself.
  const VarDecl *translateParameter(const FieldDecl *FD,
                                    const VarDecl *NativeParam) const override;

  /// Gets the address of the native argument basing on the address of the
  /// target-specific parameter.
  /// \param NativeParam Parameter itself.
  /// \param TargetParam Corresponding target-specific parameter.
  Address getParameterAddress(CodeGenFunction &CGF, const VarDecl *NativeParam,
                              const VarDecl *TargetParam) const override;

  /// Gets the OpenMP-specific address of the local variable.
  Address getAddressOfLocalVariable(CodeGenFunction &CGF,
                                    const VarDecl *VD) override {
    return Address::invalid();
  }
};

} // namespace CodeGen
// Utility for openmp doacross clause kind
namespace {
template <typename T> class OMPDoacrossKind {
public:
  bool isSink(const T *) { return false; }
  bool isSource(const T *) { return false; }
};
template <> class OMPDoacrossKind<OMPDependClause> {
public:
  bool isSink(const OMPDependClause *C) {
    return C->getDependencyKind() == OMPC_DEPEND_sink;
  }
  bool isSource(const OMPDependClause *C) {
    return C->getDependencyKind() == OMPC_DEPEND_source;
  }
};
template <> class OMPDoacrossKind<OMPDoacrossClause> {
public:
  bool isSource(const OMPDoacrossClause *C) {
    return C->getDependenceType() == OMPC_DOACROSS_source ||
           C->getDependenceType() == OMPC_DOACROSS_source_omp_cur_iteration;
  }
  bool isSink(const OMPDoacrossClause *C) {
    return C->getDependenceType() == OMPC_DOACROSS_sink ||
           C->getDependenceType() == OMPC_DOACROSS_sink_omp_cur_iteration;
  }
};
} // namespace
} // namespace clang

#endif