clang/lib/CodeGen/CGOpenMPRuntimeGPU.h - llvm-project - Git at Google

 //===------ CGOpenMPRuntimeGPU.h - Interface to OpenMP GPU Runtimes ------===//
 //
 // 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 generalized class for OpenMP runtime code generation
 // specialized by GPU targets NVPTX and AMDGCN.
 //
 //===----------------------------------------------------------------------===//

 #ifndef LLVM_CLANG_LIB_CODEGEN_CGOPENMPRUNTIMEGPU_H
 #define LLVM_CLANG_LIB_CODEGEN_CGOPENMPRUNTIMEGPU_H

 #include "CGOpenMPRuntime.h"
 #include "CodeGenFunction.h"
 #include "clang/AST/StmtOpenMP.h"

 namespace clang {
 namespace CodeGen {

 class CGOpenMPRuntimeGPU : public CGOpenMPRuntime {
 public:
   /// Defines the execution mode.
   enum ExecutionMode {
     /// SPMD execution mode (all threads are worker threads).
     EM_SPMD,
     /// Non-SPMD execution mode (1 master thread, others are workers).
     EM_NonSPMD,
     /// Unknown execution mode (orphaned directive).
     EM_Unknown,
   };
 private:
   /// Parallel outlined function work for workers to execute.
   llvm::SmallVector<llvm::Function *, 16> Work;

   struct EntryFunctionState {
     SourceLocation Loc;
   };

   ExecutionMode getExecutionMode() const;

   bool requiresFullRuntime() const { return RequiresFullRuntime; }

   /// Get barrier to synchronize all threads in a block.
   void syncCTAThreads(CodeGenFunction &CGF);

   /// Helper for target directive initialization.
   void emitKernelInit(CodeGenFunction &CGF, EntryFunctionState &EST,
                       bool IsSPMD);

   /// Helper for target directive finalization.
   void emitKernelDeinit(CodeGenFunction &CGF, EntryFunctionState &EST,
                         bool IsSPMD);

   /// Helper for generic variables globalization prolog.
   void emitGenericVarsProlog(CodeGenFunction &CGF, SourceLocation Loc,
                              bool WithSPMDCheck = false);

   /// Helper for generic variables globalization epilog.
   void emitGenericVarsEpilog(CodeGenFunction &CGF, bool WithSPMDCheck = false);

   //
   // Base class overrides.
   //

   /// Creates offloading entry for the provided entry ID \a ID,
   /// address \a Addr, size \a Size, and flags \a Flags.
   void createOffloadEntry(llvm::Constant *ID, llvm::Constant *Addr,
                           uint64_t Size, int32_t Flags,
                           llvm::GlobalValue::LinkageTypes Linkage) override;

   /// Emit outlined function specialized for the Fork-Join
   /// programming model for applicable target directives on the NVPTX device.
   /// \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.
   /// An outlined function may not be an entry if, e.g. the if clause always
   /// evaluates to false.
   void emitNonSPMDKernel(const OMPExecutableDirective &D, StringRef ParentName,
                          llvm::Function *&OutlinedFn,
                          llvm::Constant *&OutlinedFnID, bool IsOffloadEntry,
                          const RegionCodeGenTy &CodeGen);

   /// Emit outlined function specialized for the Single Program
   /// Multiple Data programming model for applicable target directives on the
   /// NVPTX device.
   /// \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 Object containing the target statements.
   /// An outlined function may not be an entry if, e.g. the if clause always
   /// evaluates to false.
   void emitSPMDKernel(const OMPExecutableDirective &D, StringRef ParentName,
                       llvm::Function *&OutlinedFn,
                       llvm::Constant *&OutlinedFnID, bool IsOffloadEntry,
                       const RegionCodeGenTy &CodeGen);

   /// Emit outlined function for 'target' directive on the NVPTX
   /// device.
   /// \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.
   /// 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;

   /// Emits code for parallel or serial call of the \a OutlinedFn with
   /// variables captured in a record which address is stored in \a
   /// CapturedStruct.
   /// This call is for the Non-SPMD Execution Mode.
   /// \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.
   void emitNonSPMDParallelCall(CodeGenFunction &CGF, SourceLocation Loc,
                                llvm::Value *OutlinedFn,
                                ArrayRef<llvm::Value *> CapturedVars,
                                const Expr *IfCond);

   /// Emits code for parallel or serial call of the \a OutlinedFn with
   /// variables captured in a record which address is stored in \a
   /// CapturedStruct.
   /// This call is for a parallel directive within an SPMD target directive.
   /// \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.
   ///
   void emitSPMDParallelCall(CodeGenFunction &CGF, SourceLocation Loc,
                             llvm::Function *OutlinedFn,
                             ArrayRef<llvm::Value *> CapturedVars,
                             const Expr *IfCond);

 protected:
   /// Get the function name of an outlined region.
   //  The name can be customized depending on the target.
   //
   StringRef getOutlinedHelperName() const override {
     return "__omp_outlined__";
   }

   /// Check if the default location must be constant.
   /// Constant for NVPTX for better optimization.
   bool isDefaultLocationConstant() const override { return true; }

   /// Returns additional flags that can be stored in reserved_2 field of the
   /// default location.
   /// For NVPTX target contains data about SPMD/Non-SPMD execution mode +
   /// Full/Lightweight runtime mode. Used for better optimization.
   unsigned getDefaultLocationReserved2Flags() const override;

 public:
   explicit CGOpenMPRuntimeGPU(CodeGenModule &CGM);
   void clear() override;

   /// Declare generalized virtual functions which need to be defined
   /// by all specializations of OpenMPGPURuntime Targets like AMDGCN
   /// and NVPTX.

   /// Get the GPU warp size.
   llvm::Value *getGPUWarpSize(CodeGenFunction &CGF);

   /// Get the id of the current thread on the GPU.
   llvm::Value *getGPUThreadID(CodeGenFunction &CGF);

   /// Get the maximum number of threads in a block of the GPU.
   llvm::Value *getGPUNumThreads(CodeGenFunction &CGF);

   /// 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) 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.
   virtual void emitNumThreadsClause(CodeGenFunction &CGF,
                                     llvm::Value *NumThreads,
                                     SourceLocation Loc) override;

   /// This function ought to emit, in the general case, a call to
   // the openmp runtime kmpc_push_num_teams. In NVPTX backend it is not needed
   // as these numbers are obtained through the PTX grid and block configuration.
   /// \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;

   /// Emits inlined 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 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(const OMPExecutableDirective &D,
                                const VarDecl *ThreadIDVar,
                                OpenMPDirectiveKind InnermostKind,
                                const RegionCodeGenTy &CodeGen) override;

   /// Emits inlined 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 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(const OMPExecutableDirective &D,
                             const VarDecl *ThreadIDVar,
                             OpenMPDirectiveKind InnermostKind,
                             const RegionCodeGenTy &CodeGen) 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 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.
   void emitParallelCall(CodeGenFunction &CGF, SourceLocation Loc,
                         llvm::Function *OutlinedFn,
                         ArrayRef<llvm::Value *> CapturedVars,
                         const Expr *IfCond) 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;

   /// 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;

   /// Emit a code for reduction clause.
   ///
   /// \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) override;

   /// Returns specified OpenMP runtime function for the current OpenMP
   /// implementation.  Specialized for the NVPTX device.
   /// \param Function OpenMP runtime function.
   /// \return Specified function.
   llvm::FunctionCallee createNVPTXRuntimeFunction(unsigned Function);

   /// 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;

   /// Emits call of the outlined function with the provided arguments,
   /// translating these arguments to correct target-specific arguments.
   void emitOutlinedFunctionCall(
       CodeGenFunction &CGF, SourceLocation Loc, llvm::FunctionCallee OutlinedFn,
       ArrayRef<llvm::Value *> Args = llvm::None) const override;

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

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

   /// Target codegen is specialized based on two data-sharing modes: CUDA, in
   /// which the local variables are actually global threadlocal, and Generic, in
   /// which the local variables are placed in global memory if they may escape
   /// their declaration context.
   enum DataSharingMode {
     /// CUDA data sharing mode.
     CUDA,
     /// Generic data-sharing mode.
     Generic,
   };

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

   /// Choose a default value for the dist_schedule clause.
   void getDefaultDistScheduleAndChunk(CodeGenFunction &CGF,
       const OMPLoopDirective &S, OpenMPDistScheduleClauseKind &ScheduleKind,
       llvm::Value *&Chunk) const override;

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

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

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

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

 private:
   /// Track the execution mode when codegening directives within a target
   /// region. The appropriate mode (SPMD/NON-SPMD) is set on entry to the
   /// target region and used by containing directives such as 'parallel'
   /// to emit optimized code.
   ExecutionMode CurrentExecutionMode = EM_Unknown;

   /// Check if the full runtime is required (default - yes).
   bool RequiresFullRuntime = true;

   /// true if we're emitting the code for the target region and next parallel
   /// region is L0 for sure.
   bool IsInTargetMasterThreadRegion = false;
   /// true if currently emitting code for target/teams/distribute region, false
   /// - otherwise.
   bool IsInTTDRegion = false;
   /// true if we're definitely in the parallel region.
   bool IsInParallelRegion = false;

   /// Map between an outlined function and its wrapper.
   llvm::DenseMap<llvm::Function *, llvm::Function *> WrapperFunctionsMap;

   /// Emit function which wraps the outline parallel region
   /// and controls the parameters which are passed to this function.
   /// The wrapper ensures that the outlined function is called
   /// with the correct arguments when data is shared.
   llvm::Function *createParallelDataSharingWrapper(
       llvm::Function *OutlinedParallelFn, const OMPExecutableDirective &D);

   /// The data for the single globalized variable.
   struct MappedVarData {
     /// Corresponding field in the global record.
     llvm::Value *GlobalizedVal = nullptr;
     /// Corresponding address.
     Address PrivateAddr = Address::invalid();
   };
   /// The map of local variables to their addresses in the global memory.
   using DeclToAddrMapTy = llvm::MapVector<const Decl *, MappedVarData>;
   /// Set of the parameters passed by value escaping OpenMP context.
   using EscapedParamsTy = llvm::SmallPtrSet<const Decl *, 4>;
   struct FunctionData {
     DeclToAddrMapTy LocalVarData;
     llvm::Optional<DeclToAddrMapTy> SecondaryLocalVarData = llvm::None;
     EscapedParamsTy EscapedParameters;
     llvm::SmallVector<const ValueDecl*, 4> EscapedVariableLengthDecls;
     llvm::SmallVector<std::pair<llvm::Value *, llvm::Value *>, 4>
         EscapedVariableLengthDeclsAddrs;
     llvm::Value *IsInSPMDModeFlag = nullptr;
     std::unique_ptr<CodeGenFunction::OMPMapVars> MappedParams;
   };
   /// Maps the function to the list of the globalized variables with their
   /// addresses.
   llvm::SmallDenseMap<llvm::Function *, FunctionData> FunctionGlobalizedDecls;
   llvm::GlobalVariable *KernelTeamsReductionPtr = nullptr;
   /// List of the records with the list of fields for the reductions across the
   /// teams. Used to build the intermediate buffer for the fast teams
   /// reductions.
   /// All the records are gathered into a union `union.type` is created.
   llvm::SmallVector<const RecordDecl *, 4> TeamsReductions;
   /// Shared pointer for the global memory in the global memory buffer used for
   /// the given kernel.
   llvm::GlobalVariable *KernelStaticGlobalized = nullptr;
   /// Pair of the Non-SPMD team and all reductions variables in this team
   /// region.
   std::pair<const Decl *, llvm::SmallVector<const ValueDecl *, 4>>
       TeamAndReductions;
 };

 } // CodeGen namespace.
 } // clang namespace.

 #endif // LLVM_CLANG_LIB_CODEGEN_CGOPENMPRUNTIMEGPU_H
	//===------ CGOpenMPRuntimeGPU.h - Interface to OpenMP GPU Runtimes ------===//
	//
	// 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 generalized class for OpenMP runtime code generation
	// specialized by GPU targets NVPTX and AMDGCN.
	//
	//===----------------------------------------------------------------------===//

	#ifndef LLVM_CLANG_LIB_CODEGEN_CGOPENMPRUNTIMEGPU_H
	#define LLVM_CLANG_LIB_CODEGEN_CGOPENMPRUNTIMEGPU_H

	#include "CGOpenMPRuntime.h"
	#include "CodeGenFunction.h"
	#include "clang/AST/StmtOpenMP.h"

	namespace clang {
	namespace CodeGen {

	class CGOpenMPRuntimeGPU : public CGOpenMPRuntime {
	public:
	/// Defines the execution mode.
	enum ExecutionMode {
	/// SPMD execution mode (all threads are worker threads).
	EM_SPMD,
	/// Non-SPMD execution mode (1 master thread, others are workers).
	EM_NonSPMD,
	/// Unknown execution mode (orphaned directive).
	EM_Unknown,
	};
	private:
	/// Parallel outlined function work for workers to execute.
	llvm::SmallVector<llvm::Function *, 16> Work;

	struct EntryFunctionState {
	SourceLocation Loc;
	};

	ExecutionMode getExecutionMode() const;

	bool requiresFullRuntime() const { return RequiresFullRuntime; }

	/// Get barrier to synchronize all threads in a block.
	void syncCTAThreads(CodeGenFunction &CGF);

	/// Helper for target directive initialization.
	void emitKernelInit(CodeGenFunction &CGF, EntryFunctionState &EST,
	bool IsSPMD);

	/// Helper for target directive finalization.
	void emitKernelDeinit(CodeGenFunction &CGF, EntryFunctionState &EST,
	bool IsSPMD);

	/// Helper for generic variables globalization prolog.
	void emitGenericVarsProlog(CodeGenFunction &CGF, SourceLocation Loc,
	bool WithSPMDCheck = false);

	/// Helper for generic variables globalization epilog.
	void emitGenericVarsEpilog(CodeGenFunction &CGF, bool WithSPMDCheck = false);

	//
	// Base class overrides.
	//

	/// Creates offloading entry for the provided entry ID \a ID,
	/// address \a Addr, size \a Size, and flags \a Flags.
	void createOffloadEntry(llvm::Constant ID, llvm::Constant Addr,
	uint64_t Size, int32_t Flags,
	llvm::GlobalValue::LinkageTypes Linkage) override;

	/// Emit outlined function specialized for the Fork-Join
	/// programming model for applicable target directives on the NVPTX device.
	/// \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.
	/// An outlined function may not be an entry if, e.g. the if clause always
	/// evaluates to false.
	void emitNonSPMDKernel(const OMPExecutableDirective &D, StringRef ParentName,
	llvm::Function *&OutlinedFn,
	llvm::Constant *&OutlinedFnID, bool IsOffloadEntry,
	const RegionCodeGenTy &CodeGen);

	/// Emit outlined function specialized for the Single Program
	/// Multiple Data programming model for applicable target directives on the
	/// NVPTX device.
	/// \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 Object containing the target statements.
	/// An outlined function may not be an entry if, e.g. the if clause always
	/// evaluates to false.
	void emitSPMDKernel(const OMPExecutableDirective &D, StringRef ParentName,
	llvm::Function *&OutlinedFn,
	llvm::Constant *&OutlinedFnID, bool IsOffloadEntry,
	const RegionCodeGenTy &CodeGen);

	/// Emit outlined function for 'target' directive on the NVPTX
	/// device.
	/// \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.
	/// 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;

	/// Emits code for parallel or serial call of the \a OutlinedFn with
	/// variables captured in a record which address is stored in \a
	/// CapturedStruct.
	/// This call is for the Non-SPMD Execution Mode.
	/// \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.
	void emitNonSPMDParallelCall(CodeGenFunction &CGF, SourceLocation Loc,
	llvm::Value *OutlinedFn,
	ArrayRef<llvm::Value *> CapturedVars,
	const Expr *IfCond);

	/// Emits code for parallel or serial call of the \a OutlinedFn with
	/// variables captured in a record which address is stored in \a
	/// CapturedStruct.
	/// This call is for a parallel directive within an SPMD target directive.
	/// \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.
	///
	void emitSPMDParallelCall(CodeGenFunction &CGF, SourceLocation Loc,
	llvm::Function *OutlinedFn,
	ArrayRef<llvm::Value *> CapturedVars,
	const Expr *IfCond);

	protected:
	/// Get the function name of an outlined region.
	// The name can be customized depending on the target.
	//
	StringRef getOutlinedHelperName() const override {
	return "__omp_outlined__";
	}

	/// Check if the default location must be constant.
	/// Constant for NVPTX for better optimization.
	bool isDefaultLocationConstant() const override { return true; }

	/// Returns additional flags that can be stored in reserved_2 field of the
	/// default location.
	/// For NVPTX target contains data about SPMD/Non-SPMD execution mode +
	/// Full/Lightweight runtime mode. Used for better optimization.
	unsigned getDefaultLocationReserved2Flags() const override;

	public:
	explicit CGOpenMPRuntimeGPU(CodeGenModule &CGM);
	void clear() override;

	/// Declare generalized virtual functions which need to be defined
	/// by all specializations of OpenMPGPURuntime Targets like AMDGCN
	/// and NVPTX.

	/// Get the GPU warp size.
	llvm::Value *getGPUWarpSize(CodeGenFunction &CGF);

	/// Get the id of the current thread on the GPU.
	llvm::Value *getGPUThreadID(CodeGenFunction &CGF);

	/// Get the maximum number of threads in a block of the GPU.
	llvm::Value *getGPUNumThreads(CodeGenFunction &CGF);

	/// 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) 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.
	virtual void emitNumThreadsClause(CodeGenFunction &CGF,
	llvm::Value *NumThreads,
	SourceLocation Loc) override;

	/// This function ought to emit, in the general case, a call to
	// the openmp runtime kmpc_push_num_teams. In NVPTX backend it is not needed
	// as these numbers are obtained through the PTX grid and block configuration.
	/// \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;

	/// Emits inlined 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 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(const OMPExecutableDirective &D,
	const VarDecl *ThreadIDVar,
	OpenMPDirectiveKind InnermostKind,
	const RegionCodeGenTy &CodeGen) override;

	/// Emits inlined 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 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(const OMPExecutableDirective &D,
	const VarDecl *ThreadIDVar,
	OpenMPDirectiveKind InnermostKind,
	const RegionCodeGenTy &CodeGen) 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 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.
	void emitParallelCall(CodeGenFunction &CGF, SourceLocation Loc,
	llvm::Function *OutlinedFn,
	ArrayRef<llvm::Value *> CapturedVars,
	const Expr *IfCond) 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;

	/// 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;

	/// Emit a code for reduction clause.
	///
	/// \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) override;

	/// Returns specified OpenMP runtime function for the current OpenMP
	/// implementation. Specialized for the NVPTX device.
	/// \param Function OpenMP runtime function.
	/// \return Specified function.
	llvm::FunctionCallee createNVPTXRuntimeFunction(unsigned Function);

	/// 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;

	/// Emits call of the outlined function with the provided arguments,
	/// translating these arguments to correct target-specific arguments.
	void emitOutlinedFunctionCall(
	CodeGenFunction &CGF, SourceLocation Loc, llvm::FunctionCallee OutlinedFn,
	ArrayRef<llvm::Value *> Args = llvm::None) const override;

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

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

	/// Target codegen is specialized based on two data-sharing modes: CUDA, in
	/// which the local variables are actually global threadlocal, and Generic, in
	/// which the local variables are placed in global memory if they may escape
	/// their declaration context.
	enum DataSharingMode {
	/// CUDA data sharing mode.
	CUDA,
	/// Generic data-sharing mode.
	Generic,
	};

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

	/// Choose a default value for the dist_schedule clause.
	void getDefaultDistScheduleAndChunk(CodeGenFunction &CGF,
	const OMPLoopDirective &S, OpenMPDistScheduleClauseKind &ScheduleKind,
	llvm::Value *&Chunk) const override;

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

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

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

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

	private:
	/// Track the execution mode when codegening directives within a target
	/// region. The appropriate mode (SPMD/NON-SPMD) is set on entry to the
	/// target region and used by containing directives such as 'parallel'
	/// to emit optimized code.
	ExecutionMode CurrentExecutionMode = EM_Unknown;

	/// Check if the full runtime is required (default - yes).
	bool RequiresFullRuntime = true;

	/// true if we're emitting the code for the target region and next parallel
	/// region is L0 for sure.
	bool IsInTargetMasterThreadRegion = false;
	/// true if currently emitting code for target/teams/distribute region, false
	/// - otherwise.
	bool IsInTTDRegion = false;
	/// true if we're definitely in the parallel region.
	bool IsInParallelRegion = false;

	/// Map between an outlined function and its wrapper.
	llvm::DenseMap<llvm::Function , llvm::Function > WrapperFunctionsMap;

	/// Emit function which wraps the outline parallel region
	/// and controls the parameters which are passed to this function.
	/// The wrapper ensures that the outlined function is called
	/// with the correct arguments when data is shared.
	llvm::Function *createParallelDataSharingWrapper(
	llvm::Function *OutlinedParallelFn, const OMPExecutableDirective &D);

	/// The data for the single globalized variable.
	struct MappedVarData {
	/// Corresponding field in the global record.
	llvm::Value *GlobalizedVal = nullptr;
	/// Corresponding address.
	Address PrivateAddr = Address::invalid();
	};
	/// The map of local variables to their addresses in the global memory.
	using DeclToAddrMapTy = llvm::MapVector<const Decl *, MappedVarData>;
	/// Set of the parameters passed by value escaping OpenMP context.
	using EscapedParamsTy = llvm::SmallPtrSet<const Decl *, 4>;
	struct FunctionData {
	DeclToAddrMapTy LocalVarData;
	llvm::Optional<DeclToAddrMapTy> SecondaryLocalVarData = llvm::None;
	EscapedParamsTy EscapedParameters;
	llvm::SmallVector<const ValueDecl*, 4> EscapedVariableLengthDecls;
	llvm::SmallVector<std::pair<llvm::Value , llvm::Value >, 4>
	EscapedVariableLengthDeclsAddrs;
	llvm::Value *IsInSPMDModeFlag = nullptr;
	std::unique_ptr<CodeGenFunction::OMPMapVars> MappedParams;
	};
	/// Maps the function to the list of the globalized variables with their
	/// addresses.
	llvm::SmallDenseMap<llvm::Function *, FunctionData> FunctionGlobalizedDecls;
	llvm::GlobalVariable *KernelTeamsReductionPtr = nullptr;
	/// List of the records with the list of fields for the reductions across the
	/// teams. Used to build the intermediate buffer for the fast teams
	/// reductions.
	/// All the records are gathered into a union `union.type` is created.
	llvm::SmallVector<const RecordDecl *, 4> TeamsReductions;
	/// Shared pointer for the global memory in the global memory buffer used for
	/// the given kernel.
	llvm::GlobalVariable *KernelStaticGlobalized = nullptr;
	/// Pair of the Non-SPMD team and all reductions variables in this team
	/// region.
	std::pair<const Decl , llvm::SmallVector<const ValueDecl , 4>>
	TeamAndReductions;
	};

	} // CodeGen namespace.
	} // clang namespace.

	#endif // LLVM_CLANG_LIB_CODEGEN_CGOPENMPRUNTIMEGPU_H