text: //===---- CGOpenMPRuntimeNVPTX.cpp - Interface to OpenMP NVPTX Runtimes ---===//
  //
  //                     The LLVM Compiler Infrastructure
  //
  // This file is distributed under the University of Illinois Open Source
  // License. See LICENSE.TXT for details.
  //
  //===----------------------------------------------------------------------===//
  //
  // This provides a class for OpenMP runtime code generation specialized to NVPTX
  // targets.
  //
  //===----------------------------------------------------------------------===//
  
  #include "CGOpenMPRuntimeNVPTX.h"
  #include "CodeGenFunction.h"
  #include "clang/AST/DeclOpenMP.h"
  #include "clang/AST/StmtOpenMP.h"
  #include "clang/AST/StmtVisitor.h"
  #include "llvm/ADT/SmallPtrSet.h"
  
  using namespace clang;
  using namespace CodeGen;
  
  namespace {
  enum OpenMPRTLFunctionNVPTX {
    /// \brief Call to void __kmpc_kernel_init(kmp_int32 thread_limit,
    /// int16_t RequiresOMPRuntime);
    OMPRTL_NVPTX__kmpc_kernel_init,
    /// \brief Call to void __kmpc_kernel_deinit(int16_t IsOMPRuntimeInitialized);
    OMPRTL_NVPTX__kmpc_kernel_deinit,
    /// \brief Call to void __kmpc_spmd_kernel_init(kmp_int32 thread_limit,
    /// int16_t RequiresOMPRuntime, int16_t RequiresDataSharing);
    OMPRTL_NVPTX__kmpc_spmd_kernel_init,
    /// \brief Call to void __kmpc_spmd_kernel_deinit();
    OMPRTL_NVPTX__kmpc_spmd_kernel_deinit,
    /// \brief Call to void __kmpc_kernel_prepare_parallel(void
    /// *outlined_function, int16_t
    /// IsOMPRuntimeInitialized);
    OMPRTL_NVPTX__kmpc_kernel_prepare_parallel,
    /// \brief Call to bool __kmpc_kernel_parallel(void **outlined_function,
    /// int16_t IsOMPRuntimeInitialized);
    OMPRTL_NVPTX__kmpc_kernel_parallel,
    /// \brief Call to void __kmpc_kernel_end_parallel();
    OMPRTL_NVPTX__kmpc_kernel_end_parallel,
    /// Call to void __kmpc_serialized_parallel(ident_t *loc, kmp_int32
    /// global_tid);
    OMPRTL_NVPTX__kmpc_serialized_parallel,
    /// Call to void __kmpc_end_serialized_parallel(ident_t *loc, kmp_int32
    /// global_tid);
    OMPRTL_NVPTX__kmpc_end_serialized_parallel,
    /// \brief Call to int32_t __kmpc_shuffle_int32(int32_t element,
    /// int16_t lane_offset, int16_t warp_size);
    OMPRTL_NVPTX__kmpc_shuffle_int32,
    /// \brief Call to int64_t __kmpc_shuffle_int64(int64_t element,
    /// int16_t lane_offset, int16_t warp_size);
    OMPRTL_NVPTX__kmpc_shuffle_int64,
    /// \brief Call to __kmpc_nvptx_parallel_reduce_nowait(kmp_int32
    /// global_tid, kmp_int32 num_vars, size_t reduce_size, void* reduce_data,
    /// void (*kmp_ShuffleReductFctPtr)(void *rhsData, int16_t lane_id, int16_t
    /// lane_offset, int16_t shortCircuit),
    /// void (*kmp_InterWarpCopyFctPtr)(void* src, int32_t warp_num));
    OMPRTL_NVPTX__kmpc_parallel_reduce_nowait,
    /// \brief Call to __kmpc_nvptx_simd_reduce_nowait(kmp_int32
    /// global_tid, kmp_int32 num_vars, size_t reduce_size, void* reduce_data,
    /// void (*kmp_ShuffleReductFctPtr)(void *rhsData, int16_t lane_id, int16_t
    /// lane_offset, int16_t shortCircuit),
    /// void (*kmp_InterWarpCopyFctPtr)(void* src, int32_t warp_num));
    OMPRTL_NVPTX__kmpc_simd_reduce_nowait,
    /// \brief Call to __kmpc_nvptx_teams_reduce_nowait(int32_t global_tid,
    /// int32_t num_vars, size_t reduce_size, void *reduce_data,
    /// void (*kmp_ShuffleReductFctPtr)(void *rhs, int16_t lane_id, int16_t
    /// lane_offset, int16_t shortCircuit),
    /// void (*kmp_InterWarpCopyFctPtr)(void* src, int32_t warp_num),
    /// void (*kmp_CopyToScratchpadFctPtr)(void *reduce_data, void * scratchpad,
    /// int32_t index, int32_t width),
    /// void (*kmp_LoadReduceFctPtr)(void *reduce_data, void * scratchpad, int32_t
    /// index, int32_t width, int32_t reduce))
    OMPRTL_NVPTX__kmpc_teams_reduce_nowait,
    /// \brief Call to __kmpc_nvptx_end_reduce_nowait(int32_t global_tid);
    OMPRTL_NVPTX__kmpc_end_reduce_nowait,
    /// \brief Call to void __kmpc_data_sharing_init_stack();
    OMPRTL_NVPTX__kmpc_data_sharing_init_stack,
    /// \brief Call to void* __kmpc_data_sharing_push_stack(size_t size,
    /// int16_t UseSharedMemory);
    OMPRTL_NVPTX__kmpc_data_sharing_push_stack,
    /// \brief Call to void __kmpc_data_sharing_pop_stack(void *a);
    OMPRTL_NVPTX__kmpc_data_sharing_pop_stack,
    /// \brief Call to void __kmpc_begin_sharing_variables(void ***args,
    /// size_t n_args);
    OMPRTL_NVPTX__kmpc_begin_sharing_variables,
    /// \brief Call to void __kmpc_end_sharing_variables();
    OMPRTL_NVPTX__kmpc_end_sharing_variables,
    /// \brief Call to void __kmpc_get_shared_variables(void ***GlobalArgs)
    OMPRTL_NVPTX__kmpc_get_shared_variables,
  };
  
  /// Pre(post)-action for different OpenMP constructs specialized for NVPTX.
  class NVPTXActionTy final : public PrePostActionTy {
    llvm::Value *EnterCallee = nullptr;
    ArrayRef<llvm::Value *> EnterArgs;
    llvm::Value *ExitCallee = nullptr;
    ArrayRef<llvm::Value *> ExitArgs;
    bool Conditional = false;
    llvm::BasicBlock *ContBlock = nullptr;
  
  public:
    NVPTXActionTy(llvm::Value *EnterCallee, ArrayRef<llvm::Value *> EnterArgs,
                  llvm::Value *ExitCallee, ArrayRef<llvm::Value *> ExitArgs,
                  bool Conditional = false)
        : EnterCallee(EnterCallee), EnterArgs(EnterArgs), ExitCallee(ExitCallee),
          ExitArgs(ExitArgs), Conditional(Conditional) {}
    void Enter(CodeGenFunction &CGF) override {
      llvm::Value *EnterRes = CGF.EmitRuntimeCall(EnterCallee, EnterArgs);
      if (Conditional) {
        llvm::Value *CallBool = CGF.Builder.CreateIsNotNull(EnterRes);
        auto *ThenBlock = CGF.createBasicBlock("omp_if.then");
        ContBlock = CGF.createBasicBlock("omp_if.end");
        // Generate the branch (If-stmt)
        CGF.Builder.CreateCondBr(CallBool, ThenBlock, ContBlock);
        CGF.EmitBlock(ThenBlock);
      }
    }
    void Done(CodeGenFunction &CGF) {
      // Emit the rest of blocks/branches
      CGF.EmitBranch(ContBlock);
      CGF.EmitBlock(ContBlock, true);
    }
    void Exit(CodeGenFunction &CGF) override {
      CGF.EmitRuntimeCall(ExitCallee, ExitArgs);
    }
  };
  
  // A class to track the execution mode when codegening directives within
  // a target region. The appropriate mode (generic/spmd) is set on entry
  // to the target region and used by containing directives such as 'parallel'
  // to emit optimized code.
  class ExecutionModeRAII {
  private:
    CGOpenMPRuntimeNVPTX::ExecutionMode SavedMode;
    CGOpenMPRuntimeNVPTX::ExecutionMode &Mode;
  
  public:
    ExecutionModeRAII(CGOpenMPRuntimeNVPTX::ExecutionMode &Mode,
                      CGOpenMPRuntimeNVPTX::ExecutionMode NewMode)
        : Mode(Mode) {
      SavedMode = Mode;
      Mode = NewMode;
    }
    ~ExecutionModeRAII() { Mode = SavedMode; }
  };
  
  /// GPU Configuration:  This information can be derived from cuda registers,
  /// however, providing compile time constants helps generate more efficient
  /// code.  For all practical purposes this is fine because the configuration
  /// is the same for all known NVPTX architectures.
  enum MachineConfiguration : unsigned {
    WarpSize = 32,
    /// Number of bits required to represent a lane identifier, which is
    /// computed as log_2(WarpSize).
    LaneIDBits = 5,
    LaneIDMask = WarpSize - 1,
  
    /// Global memory alignment for performance.
    GlobalMemoryAlignment = 256,
  };
  
  enum NamedBarrier : unsigned {
    /// Synchronize on this barrier #ID using a named barrier primitive.
    /// Only the subset of active threads in a parallel region arrive at the
    /// barrier.
    NB_Parallel = 1,
  };
  
  /// Get the list of variables that can escape their declaration context.
  class CheckVarsEscapingDeclContext final
      : public ConstStmtVisitor<CheckVarsEscapingDeclContext> {
    CodeGenFunction &CGF;
    llvm::SetVector<const ValueDecl *> EscapedDecls;
    llvm::SetVector<const ValueDecl *> EscapedVariableLengthDecls;
    llvm::SmallPtrSet<const Decl *, 4> EscapedParameters;
    bool AllEscaped = false;
    RecordDecl *GlobalizedRD = nullptr;
    llvm::SmallDenseMap<const ValueDecl *, const FieldDecl *> MappedDeclsFields;
  
    static llvm::Optional<OMPDeclareTargetDeclAttr::MapTypeTy>
    isDeclareTargetDeclaration(const ValueDecl *VD) {
      for (const Decl *D : VD->redecls()) {
        if (!D->hasAttrs())
          continue;
        if (const auto *Attr = D->getAttr<OMPDeclareTargetDeclAttr>())
          return Attr->getMapType();
      }
      return llvm::None;
    }
  
    void markAsEscaped(const ValueDecl *VD) {
      // Do not globalize declare target variables.
      if (isDeclareTargetDeclaration(VD))
        return;
      VD = cast<ValueDecl>(VD->getCanonicalDecl());
      // Variables captured by value must be globalized.
      if (auto *CSI = CGF.CapturedStmtInfo) {
        if (const FieldDecl *FD = CSI->lookup(cast<VarDecl>(VD))) {
          if (!FD->hasAttrs())
            return;
          const auto *Attr = FD->getAttr<OMPCaptureKindAttr>();
          if (!Attr)
            return;
          if (!isOpenMPPrivate(
                  static_cast<OpenMPClauseKind>(Attr->getCaptureKind())) ||
              Attr->getCaptureKind() == OMPC_map)
            return;
          if (FD->getType()->isReferenceType())
            return;
          assert(!VD->getType()->isVariablyModifiedType() &&
                 "Parameter captured by value with variably modified type");
          EscapedParameters.insert(VD);
        }
      }
      if (VD->getType()->isVariablyModifiedType())
        EscapedVariableLengthDecls.insert(VD);
      else
        EscapedDecls.insert(VD);
    }
  
    void VisitValueDecl(const ValueDecl *VD) {
      if (VD->getType()->isLValueReferenceType())
        markAsEscaped(VD);
      if (const auto *VarD = dyn_cast<VarDecl>(VD)) {
        if (!isa<ParmVarDecl>(VarD) && VarD->hasInit()) {
          const bool SavedAllEscaped = AllEscaped;
          AllEscaped = VD->getType()->isLValueReferenceType();
          Visit(VarD->getInit());
          AllEscaped = SavedAllEscaped;
        }
      }
    }
    void VisitOpenMPCapturedStmt(const CapturedStmt *S) {
      if (!S)
        return;
      for (const CapturedStmt::Capture &C : S->captures()) {
        if (C.capturesVariable() && !C.capturesVariableByCopy()) {
          const ValueDecl *VD = C.getCapturedVar();
          markAsEscaped(VD);
          if (isa<OMPCapturedExprDecl>(VD))
            VisitValueDecl(VD);
        }
      }
    }
  
    typedef std::pair<CharUnits /*Align*/, const ValueDecl *> VarsDataTy;
    static bool stable_sort_comparator(const VarsDataTy P1, const VarsDataTy P2) {
      return P1.first > P2.first;
    }
  
    void buildRecordForGlobalizedVars() {
      assert(!GlobalizedRD &&
             "Record for globalized variables is built already.");
      if (EscapedDecls.empty())
        return;
      ASTContext &C = CGF.getContext();
      SmallVector<VarsDataTy, 4> GlobalizedVars;
      for (const ValueDecl *D : EscapedDecls)
        GlobalizedVars.emplace_back(C.getDeclAlign(D), D);
      std::stable_sort(GlobalizedVars.begin(), GlobalizedVars.end(),
                       stable_sort_comparator);
      // Build struct _globalized_locals_ty {
      //         /*  globalized vars  */
      //       };
      GlobalizedRD = C.buildImplicitRecord("_globalized_locals_ty");
      GlobalizedRD->startDefinition();
      for (const auto &Pair : GlobalizedVars) {
        const ValueDecl *VD = Pair.second;
        QualType Type = VD->getType();
        if (Type->isLValueReferenceType())
          Type = C.getPointerType(Type.getNonReferenceType());
        else
          Type = Type.getNonReferenceType();
        SourceLocation Loc = VD->getLocation();
        auto *Field = FieldDecl::Create(
            C, GlobalizedRD, Loc, Loc, VD->getIdentifier(), Type,
            C.getTrivialTypeSourceInfo(Type, SourceLocation()),
            /*BW=*/nullptr, /*Mutable=*/false,
            /*InitStyle=*/ICIS_NoInit);
        Field->setAccess(AS_public);
        GlobalizedRD->addDecl(Field);
        if (VD->hasAttrs()) {
          for (specific_attr_iterator<AlignedAttr> I(VD->getAttrs().begin()),
               E(VD->getAttrs().end());
               I != E; ++I)
            Field->addAttr(*I);
        }
        MappedDeclsFields.try_emplace(VD, Field);
      }
      GlobalizedRD->completeDefinition();
    }
  
  public:
    CheckVarsEscapingDeclContext(CodeGenFunction &CGF) : CGF(CGF) {}
    virtual ~CheckVarsEscapingDeclContext() = default;
    void VisitDeclStmt(const DeclStmt *S) {
      if (!S)
        return;
      for (const Decl *D : S->decls())
        if (const auto *VD = dyn_cast_or_null<ValueDecl>(D))
          VisitValueDecl(VD);
    }
    void VisitOMPExecutableDirective(const OMPExecutableDirective *D) {
      if (!D)
        return;
      if (D->hasAssociatedStmt()) {
        if (const auto *S =
                dyn_cast_or_null<CapturedStmt>(D->getAssociatedStmt()))
          VisitOpenMPCapturedStmt(S);
      }
    }
    void VisitCapturedStmt(const CapturedStmt *S) {
      if (!S)
        return;
      for (const CapturedStmt::Capture &C : S->captures()) {
        if (C.capturesVariable() && !C.capturesVariableByCopy()) {
          const ValueDecl *VD = C.getCapturedVar();
          markAsEscaped(VD);
          if (isa<OMPCapturedExprDecl>(VD))
            VisitValueDecl(VD);
        }
      }
    }
    void VisitLambdaExpr(const LambdaExpr *E) {
      if (!E)
        return;
      for (const LambdaCapture &C : E->captures()) {
        if (C.capturesVariable()) {
          if (C.getCaptureKind() == LCK_ByRef) {
            const ValueDecl *VD = C.getCapturedVar();
            markAsEscaped(VD);
            if (E->isInitCapture(&C) || isa<OMPCapturedExprDecl>(VD))
              VisitValueDecl(VD);
          }
        }
      }
    }
    void VisitBlockExpr(const BlockExpr *E) {
      if (!E)
        return;
      for (const BlockDecl::Capture &C : E->getBlockDecl()->captures()) {
        if (C.isByRef()) {
          const VarDecl *VD = C.getVariable();
          markAsEscaped(VD);
          if (isa<OMPCapturedExprDecl>(VD) || VD->isInitCapture())
            VisitValueDecl(VD);
        }
      }
    }
    void VisitCallExpr(const CallExpr *E) {
      if (!E)
        return;
      for (const Expr *Arg : E->arguments()) {
        if (!Arg)
          continue;
        if (Arg->isLValue()) {
          const bool SavedAllEscaped = AllEscaped;
          AllEscaped = true;
          Visit(Arg);
          AllEscaped = SavedAllEscaped;
        } else {
          Visit(Arg);
        }
      }
      Visit(E->getCallee());
    }
    void VisitDeclRefExpr(const DeclRefExpr *E) {
      if (!E)
        return;
      const ValueDecl *VD = E->getDecl();
      if (AllEscaped)
        markAsEscaped(VD);
      if (isa<OMPCapturedExprDecl>(VD))
        VisitValueDecl(VD);
      else if (const auto *VarD = dyn_cast<VarDecl>(VD))
        if (VarD->isInitCapture())
          VisitValueDecl(VD);
    }
    void VisitUnaryOperator(const UnaryOperator *E) {
      if (!E)
        return;
      if (E->getOpcode() == UO_AddrOf) {
        const bool SavedAllEscaped = AllEscaped;
        AllEscaped = true;
        Visit(E->getSubExpr());
        AllEscaped = SavedAllEscaped;
      } else {
        Visit(E->getSubExpr());
      }
    }
    void VisitImplicitCastExpr(const ImplicitCastExpr *E) {
      if (!E)
        return;
      if (E->getCastKind() == CK_ArrayToPointerDecay) {
        const bool SavedAllEscaped = AllEscaped;
        AllEscaped = true;
        Visit(E->getSubExpr());
        AllEscaped = SavedAllEscaped;
      } else {
        Visit(E->getSubExpr());
      }
    }
    void VisitExpr(const Expr *E) {
      if (!E)
        return;
      bool SavedAllEscaped = AllEscaped;
      if (!E->isLValue())
        AllEscaped = false;
      for (const Stmt *Child : E->children())
        if (Child)
          Visit(Child);
      AllEscaped = SavedAllEscaped;
    }
    void VisitStmt(const Stmt *S) {
      if (!S)
        return;
      for (const Stmt *Child : S->children())
        if (Child)
          Visit(Child);
    }
  
    /// Returns the record that handles all the escaped local variables and used
    /// instead of their original storage.
    const RecordDecl *getGlobalizedRecord() {
      if (!GlobalizedRD)
        buildRecordForGlobalizedVars();
      return GlobalizedRD;
    }
  
    /// Returns the field in the globalized record for the escaped variable.
    const FieldDecl *getFieldForGlobalizedVar(const ValueDecl *VD) const {
      assert(GlobalizedRD &&
             "Record for globalized variables must be generated already.");
      auto I = MappedDeclsFields.find(VD);
      if (I == MappedDeclsFields.end())
        return nullptr;
      return I->getSecond();
    }
  
    /// Returns the list of the escaped local variables/parameters.
    ArrayRef<const ValueDecl *> getEscapedDecls() const {
      return EscapedDecls.getArrayRef();
    }
  
    /// Checks if the escaped local variable is actually a parameter passed by
    /// value.
    const llvm::SmallPtrSetImpl<const Decl *> &getEscapedParameters() const {
      return EscapedParameters;
    }
  
    /// Returns the list of the escaped variables with the variably modified
    /// types.
    ArrayRef<const ValueDecl *> getEscapedVariableLengthDecls() const {
      return EscapedVariableLengthDecls.getArrayRef();
    }
  };
  } // anonymous namespace
  
  /// Get the GPU warp size.
  static llvm::Value *getNVPTXWarpSize(CodeGenFunction &CGF) {
    return CGF.EmitRuntimeCall(
        llvm::Intrinsic::getDeclaration(
            &CGF.CGM.getModule(), llvm::Intrinsic::nvvm_read_ptx_sreg_warpsize),
        "nvptx_warp_size");
  }
  
  /// Get the id of the current thread on the GPU.
  static llvm::Value *getNVPTXThreadID(CodeGenFunction &CGF) {
    return CGF.EmitRuntimeCall(
        llvm::Intrinsic::getDeclaration(
            &CGF.CGM.getModule(), llvm::Intrinsic::nvvm_read_ptx_sreg_tid_x),
        "nvptx_tid");
  }
  
  /// Get the id of the warp in the block.
  /// We assume that the warp size is 32, which is always the case
  /// on the NVPTX device, to generate more efficient code.
  static llvm::Value *getNVPTXWarpID(CodeGenFunction &CGF) {
    CGBuilderTy &Bld = CGF.Builder;
    return Bld.CreateAShr(getNVPTXThreadID(CGF), LaneIDBits, "nvptx_warp_id");
  }
  
  /// Get the id of the current lane in the Warp.
  /// We assume that the warp size is 32, which is always the case
  /// on the NVPTX device, to generate more efficient code.
  static llvm::Value *getNVPTXLaneID(CodeGenFunction &CGF) {
    CGBuilderTy &Bld = CGF.Builder;
    return Bld.CreateAnd(getNVPTXThreadID(CGF), Bld.getInt32(LaneIDMask),
                         "nvptx_lane_id");
  }
  
  /// Get the maximum number of threads in a block of the GPU.
  static llvm::Value *getNVPTXNumThreads(CodeGenFunction &CGF) {
    return CGF.EmitRuntimeCall(
        llvm::Intrinsic::getDeclaration(
            &CGF.CGM.getModule(), llvm::Intrinsic::nvvm_read_ptx_sreg_ntid_x),
        "nvptx_num_threads");
  }
  
  /// Get barrier to synchronize all threads in a block.
  static void getNVPTXCTABarrier(CodeGenFunction &CGF) {
    CGF.EmitRuntimeCall(llvm::Intrinsic::getDeclaration(
        &CGF.CGM.getModule(), llvm::Intrinsic::nvvm_barrier0));
  }
  
  /// Get barrier #ID to synchronize selected (multiple of warp size) threads in
  /// a CTA.
  static void getNVPTXBarrier(CodeGenFunction &CGF, int ID,
                              llvm::Value *NumThreads) {
    CGBuilderTy &Bld = CGF.Builder;
    llvm::Value *Args[] = {Bld.getInt32(ID), NumThreads};
    CGF.EmitRuntimeCall(llvm::Intrinsic::getDeclaration(
                            &CGF.CGM.getModule(), llvm::Intrinsic::nvvm_barrier),
                        Args);
  }
  
  /// Synchronize all GPU threads in a block.
  static void syncCTAThreads(CodeGenFunction &CGF) { getNVPTXCTABarrier(CGF); }
  
  /// Synchronize worker threads in a parallel region.
  static void syncParallelThreads(CodeGenFunction &CGF, llvm::Value *NumThreads) {
    return getNVPTXBarrier(CGF, NB_Parallel, NumThreads);
  }
  
  /// Get the value of the thread_limit clause in the teams directive.
  /// For the 'generic' execution mode, the runtime encodes thread_limit in
  /// the launch parameters, always starting thread_limit+warpSize threads per
  /// CTA. The threads in the last warp are reserved for master execution.
  /// For the 'spmd' execution mode, all threads in a CTA are part of the team.
  static llvm::Value *getThreadLimit(CodeGenFunction &CGF,
                                     bool IsInSpmdExecutionMode = false) {
    CGBuilderTy &Bld = CGF.Builder;
    return IsInSpmdExecutionMode
               ? getNVPTXNumThreads(CGF)
               : Bld.CreateNUWSub(getNVPTXNumThreads(CGF), getNVPTXWarpSize(CGF),
                                  "thread_limit");
  }
  
  /// Get the thread id of the OMP master thread.
  /// The master thread id is the first thread (lane) of the last warp in the
  /// GPU block.  Warp size is assumed to be some power of 2.
  /// Thread id is 0 indexed.
  /// E.g: If NumThreads is 33, master id is 32.
  ///      If NumThreads is 64, master id is 32.
  ///      If NumThreads is 1024, master id is 992.
  static llvm::Value *getMasterThreadID(CodeGenFunction &CGF) {
    CGBuilderTy &Bld = CGF.Builder;
    llvm::Value *NumThreads = getNVPTXNumThreads(CGF);
  
    // We assume that the warp size is a power of 2.
    llvm::Value *Mask = Bld.CreateNUWSub(getNVPTXWarpSize(CGF), Bld.getInt32(1));
  
    return Bld.CreateAnd(Bld.CreateNUWSub(NumThreads, Bld.getInt32(1)),
                         Bld.CreateNot(Mask), "master_tid");
  }
  
  CGOpenMPRuntimeNVPTX::WorkerFunctionState::WorkerFunctionState(
      CodeGenModule &CGM, SourceLocation Loc)
      : WorkerFn(nullptr), CGFI(CGM.getTypes().arrangeNullaryFunction()),
        Loc(Loc) {
    createWorkerFunction(CGM);
  }
  
  void CGOpenMPRuntimeNVPTX::WorkerFunctionState::createWorkerFunction(
      CodeGenModule &CGM) {
    // Create an worker function with no arguments.
  
    WorkerFn = llvm::Function::Create(
        CGM.getTypes().GetFunctionType(CGFI), llvm::GlobalValue::InternalLinkage,
        /*placeholder=*/"_worker", &CGM.getModule());
    CGM.SetInternalFunctionAttributes(GlobalDecl(), WorkerFn, CGFI);
    WorkerFn->setDoesNotRecurse();
  }
  
  bool CGOpenMPRuntimeNVPTX::isInSpmdExecutionMode() const {
    return CurrentExecutionMode == CGOpenMPRuntimeNVPTX::ExecutionMode::Spmd;
  }
  
  static CGOpenMPRuntimeNVPTX::ExecutionMode
  getExecutionMode(CodeGenModule &CGM) {
    return CGM.getLangOpts().OpenMPCUDAMode
               ? CGOpenMPRuntimeNVPTX::ExecutionMode::Spmd
               : CGOpenMPRuntimeNVPTX::ExecutionMode::Generic;
  }
  
  void CGOpenMPRuntimeNVPTX::emitGenericKernel(const OMPExecutableDirective &D,
                                               StringRef ParentName,
                                               llvm::Function *&OutlinedFn,
                                               llvm::Constant *&OutlinedFnID,
                                               bool IsOffloadEntry,
                                               const RegionCodeGenTy &CodeGen) {
    ExecutionModeRAII ModeRAII(CurrentExecutionMode,
                               CGOpenMPRuntimeNVPTX::ExecutionMode::Generic);
    EntryFunctionState EST;
    WorkerFunctionState WST(CGM, D.getLocStart());
    Work.clear();
    WrapperFunctionsMap.clear();
  
    // Emit target region as a standalone region.
    class NVPTXPrePostActionTy : public PrePostActionTy {
      CGOpenMPRuntimeNVPTX::EntryFunctionState &EST;
      CGOpenMPRuntimeNVPTX::WorkerFunctionState &WST;
  
    public:
      NVPTXPrePostActionTy(CGOpenMPRuntimeNVPTX::EntryFunctionState &EST,
                           CGOpenMPRuntimeNVPTX::WorkerFunctionState &WST)
          : EST(EST), WST(WST) {}
      void Enter(CodeGenFunction &CGF) override {
        static_cast<CGOpenMPRuntimeNVPTX &>(CGF.CGM.getOpenMPRuntime())
            .emitGenericEntryHeader(CGF, EST, WST);
      }
      void Exit(CodeGenFunction &CGF) override {
        static_cast<CGOpenMPRuntimeNVPTX &>(CGF.CGM.getOpenMPRuntime())
            .emitGenericEntryFooter(CGF, EST);
      }
    } Action(EST, WST);
    CodeGen.setAction(Action);
    emitTargetOutlinedFunctionHelper(D, ParentName, OutlinedFn, OutlinedFnID,
                                     IsOffloadEntry, CodeGen);
  
    // Now change the name of the worker function to correspond to this target
    // region's entry function.
    WST.WorkerFn->setName(Twine(OutlinedFn->getName(), "_worker"));
  
    // Create the worker function
    emitWorkerFunction(WST);
  }
  
  // Setup NVPTX threads for master-worker OpenMP scheme.
  void CGOpenMPRuntimeNVPTX::emitGenericEntryHeader(CodeGenFunction &CGF,
                                                    EntryFunctionState &EST,
                                                    WorkerFunctionState &WST) {
    CGBuilderTy &Bld = CGF.Builder;
  
    llvm::BasicBlock *WorkerBB = CGF.createBasicBlock(".worker");
    llvm::BasicBlock *MasterCheckBB = CGF.createBasicBlock(".mastercheck");
    llvm::BasicBlock *MasterBB = CGF.createBasicBlock(".master");
    EST.ExitBB = CGF.createBasicBlock(".exit");
  
    llvm::Value *IsWorker =
        Bld.CreateICmpULT(getNVPTXThreadID(CGF), getThreadLimit(CGF));
    Bld.CreateCondBr(IsWorker, WorkerBB, MasterCheckBB);
  
    CGF.EmitBlock(WorkerBB);
    emitCall(CGF, WST.Loc, WST.WorkerFn);
    CGF.EmitBranch(EST.ExitBB);
  
    CGF.EmitBlock(MasterCheckBB);
    llvm::Value *IsMaster =
        Bld.CreateICmpEQ(getNVPTXThreadID(CGF), getMasterThreadID(CGF));
    Bld.CreateCondBr(IsMaster, MasterBB, EST.ExitBB);
  
    CGF.EmitBlock(MasterBB);
    // SEQUENTIAL (MASTER) REGION START
    // First action in sequential region:
    // Initialize the state of the OpenMP runtime library on the GPU.
    // TODO: Optimize runtime initialization and pass in correct value.
    llvm::Value *Args[] = {getThreadLimit(CGF),
                           Bld.getInt16(/*RequiresOMPRuntime=*/1)};
    CGF.EmitRuntimeCall(
        createNVPTXRuntimeFunction(OMPRTL_NVPTX__kmpc_kernel_init), Args);
  
    // For data sharing, we need to initialize the stack.
    CGF.EmitRuntimeCall(
        createNVPTXRuntimeFunction(
            OMPRTL_NVPTX__kmpc_data_sharing_init_stack));
  
    emitGenericVarsProlog(CGF, WST.Loc);
  }
  
  void CGOpenMPRuntimeNVPTX::emitGenericEntryFooter(CodeGenFunction &CGF,
                                                    EntryFunctionState &EST) {
    emitGenericVarsEpilog(CGF);
    if (!CGF.HaveInsertPoint())
      return;
  
    if (!EST.ExitBB)
      EST.ExitBB = CGF.createBasicBlock(".exit");
  
    llvm::BasicBlock *TerminateBB = CGF.createBasicBlock(".termination.notifier");
    CGF.EmitBranch(TerminateBB);
  
    CGF.EmitBlock(TerminateBB);
    // Signal termination condition.
    // TODO: Optimize runtime initialization and pass in correct value.
    llvm::Value *Args[] = {CGF.Builder.getInt16(/*IsOMPRuntimeInitialized=*/1)};
    CGF.EmitRuntimeCall(
        createNVPTXRuntimeFunction(OMPRTL_NVPTX__kmpc_kernel_deinit), Args);
    // Barrier to terminate worker threads.
    syncCTAThreads(CGF);
    // Master thread jumps to exit point.
    CGF.EmitBranch(EST.ExitBB);
  
    CGF.EmitBlock(EST.ExitBB);
    EST.ExitBB = nullptr;
  }
  
  void CGOpenMPRuntimeNVPTX::emitSpmdKernel(const OMPExecutableDirective &D,
                                            StringRef ParentName,
                                            llvm::Function *&OutlinedFn,
                                            llvm::Constant *&OutlinedFnID,
                                            bool IsOffloadEntry,
                                            const RegionCodeGenTy &CodeGen) {
    ExecutionModeRAII ModeRAII(CurrentExecutionMode,
                               CGOpenMPRuntimeNVPTX::ExecutionMode::Spmd);
    EntryFunctionState EST;
  
    // Emit target region as a standalone region.
    class NVPTXPrePostActionTy : public PrePostActionTy {
      CGOpenMPRuntimeNVPTX &RT;
      CGOpenMPRuntimeNVPTX::EntryFunctionState &EST;
      const OMPExecutableDirective &D;
  
    public:
      NVPTXPrePostActionTy(CGOpenMPRuntimeNVPTX &RT,
                           CGOpenMPRuntimeNVPTX::EntryFunctionState &EST,
                           const OMPExecutableDirective &D)
          : RT(RT), EST(EST), D(D) {}
      void Enter(CodeGenFunction &CGF) override {
        RT.emitSpmdEntryHeader(CGF, EST, D);
      }
      void Exit(CodeGenFunction &CGF) override {
        RT.emitSpmdEntryFooter(CGF, EST);
      }
    } Action(*this, EST, D);
    CodeGen.setAction(Action);
    emitTargetOutlinedFunctionHelper(D, ParentName, OutlinedFn, OutlinedFnID,
                                     IsOffloadEntry, CodeGen);
  }
  
  void CGOpenMPRuntimeNVPTX::emitSpmdEntryHeader(
      CodeGenFunction &CGF, EntryFunctionState &EST,
      const OMPExecutableDirective &D) {
    CGBuilderTy &Bld = CGF.Builder;
  
    // Setup BBs in entry function.
    llvm::BasicBlock *ExecuteBB = CGF.createBasicBlock(".execute");
    EST.ExitBB = CGF.createBasicBlock(".exit");
  
    // Initialize the OMP state in the runtime; called by all active threads.
    // TODO: Set RequiresOMPRuntime and RequiresDataSharing parameters
    // based on code analysis of the target region.
    llvm::Value *Args[] = {getThreadLimit(CGF, /*IsInSpmdExecutionMode=*/true),
                           /*RequiresOMPRuntime=*/Bld.getInt16(1),
                           /*RequiresDataSharing=*/Bld.getInt16(1)};
    CGF.EmitRuntimeCall(
        createNVPTXRuntimeFunction(OMPRTL_NVPTX__kmpc_spmd_kernel_init), Args);
    CGF.EmitBranch(ExecuteBB);
  
    CGF.EmitBlock(ExecuteBB);
  }
  
  void CGOpenMPRuntimeNVPTX::emitSpmdEntryFooter(CodeGenFunction &CGF,
                                                 EntryFunctionState &EST) {
    if (!EST.ExitBB)
      EST.ExitBB = CGF.createBasicBlock(".exit");
  
    llvm::BasicBlock *OMPDeInitBB = CGF.createBasicBlock(".omp.deinit");
    CGF.EmitBranch(OMPDeInitBB);
  
    CGF.EmitBlock(OMPDeInitBB);
    // DeInitialize the OMP state in the runtime; called by all active threads.
    CGF.EmitRuntimeCall(
        createNVPTXRuntimeFunction(OMPRTL_NVPTX__kmpc_spmd_kernel_deinit), None);
    CGF.EmitBranch(EST.ExitBB);
  
    CGF.EmitBlock(EST.ExitBB);
    EST.ExitBB = nullptr;
  }
  
  // Create a unique global variable to indicate the execution mode of this target
  // region. The execution mode is either 'generic', or 'spmd' depending on the
  // target directive. This variable is picked up by the offload library to setup
  // the device appropriately before kernel launch. If the execution mode is
  // 'generic', the runtime reserves one warp for the master, otherwise, all
  // warps participate in parallel work.
  static void setPropertyExecutionMode(CodeGenModule &CGM, StringRef Name,
                                       CGOpenMPRuntimeNVPTX::ExecutionMode Mode) {
    auto *GVMode = new llvm::GlobalVariable(
        CGM.getModule(), CGM.Int8Ty, /*isConstant=*/true,
        llvm::GlobalValue::WeakAnyLinkage,
        llvm::ConstantInt::get(CGM.Int8Ty, Mode), Twine(Name, "_exec_mode"));
    CGM.addCompilerUsedGlobal(GVMode);
  }
  
  void CGOpenMPRuntimeNVPTX::emitWorkerFunction(WorkerFunctionState &WST) {
    ASTContext &Ctx = CGM.getContext();
  
    CodeGenFunction CGF(CGM, /*suppressNewContext=*/true);
    CGF.StartFunction(GlobalDecl(), Ctx.VoidTy, WST.WorkerFn, WST.CGFI, {},
                      WST.Loc, WST.Loc);
    emitWorkerLoop(CGF, WST);
    CGF.FinishFunction();
  }
  
  void CGOpenMPRuntimeNVPTX::emitWorkerLoop(CodeGenFunction &CGF,
                                            WorkerFunctionState &WST) {
    //
    // The workers enter this loop and wait for parallel work from the master.
    // When the master encounters a parallel region it sets up the work + variable
    // arguments, and wakes up the workers.  The workers first check to see if
    // they are required for the parallel region, i.e., within the # of requested
    // parallel threads.  The activated workers load the variable arguments and
    // execute the parallel work.
    //
  
    CGBuilderTy &Bld = CGF.Builder;
  
    llvm::BasicBlock *AwaitBB = CGF.createBasicBlock(".await.work");
    llvm::BasicBlock *SelectWorkersBB = CGF.createBasicBlock(".select.workers");
    llvm::BasicBlock *ExecuteBB = CGF.createBasicBlock(".execute.parallel");
    llvm::BasicBlock *TerminateBB = CGF.createBasicBlock(".terminate.parallel");
    llvm::BasicBlock *BarrierBB = CGF.createBasicBlock(".barrier.parallel");
    llvm::BasicBlock *ExitBB = CGF.createBasicBlock(".exit");
  
    CGF.EmitBranch(AwaitBB);
  
    // Workers wait for work from master.
    CGF.EmitBlock(AwaitBB);
    // Wait for parallel work
    syncCTAThreads(CGF);
  
    // For data sharing, we need to initialize the stack for workers.
    CGF.EmitRuntimeCall(
        createNVPTXRuntimeFunction(
            OMPRTL_NVPTX__kmpc_data_sharing_init_stack));
  
    Address WorkFn =
        CGF.CreateDefaultAlignTempAlloca(CGF.Int8PtrTy, /*Name=*/"work_fn");
    Address ExecStatus =
        CGF.CreateDefaultAlignTempAlloca(CGF.Int8Ty, /*Name=*/"exec_status");
    CGF.InitTempAlloca(ExecStatus, Bld.getInt8(/*C=*/0));
    CGF.InitTempAlloca(WorkFn, llvm::Constant::getNullValue(CGF.Int8PtrTy));
  
    // TODO: Optimize runtime initialization and pass in correct value.
    llvm::Value *Args[] = {WorkFn.getPointer(),
                           /*RequiresOMPRuntime=*/Bld.getInt16(1)};
    llvm::Value *Ret = CGF.EmitRuntimeCall(
        createNVPTXRuntimeFunction(OMPRTL_NVPTX__kmpc_kernel_parallel), Args);
    Bld.CreateStore(Bld.CreateZExt(Ret, CGF.Int8Ty), ExecStatus);
  
    // On termination condition (workid == 0), exit loop.
    llvm::Value *ShouldTerminate =
        Bld.CreateIsNull(Bld.CreateLoad(WorkFn), "should_terminate");
    Bld.CreateCondBr(ShouldTerminate, ExitBB, SelectWorkersBB);
  
    // Activate requested workers.
    CGF.EmitBlock(SelectWorkersBB);
    llvm::Value *IsActive =
        Bld.CreateIsNotNull(Bld.CreateLoad(ExecStatus), "is_active");
    Bld.CreateCondBr(IsActive, ExecuteBB, BarrierBB);
  
    // Signal start of parallel region.
    CGF.EmitBlock(ExecuteBB);
  
    // Process work items: outlined parallel functions.
    for (llvm::Function *W : Work) {
      // Try to match this outlined function.
      llvm::Value *ID = Bld.CreatePointerBitCastOrAddrSpaceCast(W, CGM.Int8PtrTy);
  
      llvm::Value *WorkFnMatch =
          Bld.CreateICmpEQ(Bld.CreateLoad(WorkFn), ID, "work_match");
  
      llvm::BasicBlock *ExecuteFNBB = CGF.createBasicBlock(".execute.fn");
      llvm::BasicBlock *CheckNextBB = CGF.createBasicBlock(".check.next");
      Bld.CreateCondBr(WorkFnMatch, ExecuteFNBB, CheckNextBB);
  
      // Execute this outlined function.
      CGF.EmitBlock(ExecuteFNBB);
  
      // Insert call to work function via shared wrapper. The shared
      // wrapper takes two arguments:
      //   - the parallelism level;
      //   - the thread ID;
      emitCall(CGF, WST.Loc, W,
               {Bld.getInt16(/*ParallelLevel=*/0), getThreadID(CGF, WST.Loc)});
  
      // Go to end of parallel region.
      CGF.EmitBranch(TerminateBB);
  
      CGF.EmitBlock(CheckNextBB);
    }
  
    // Signal end of parallel region.
    CGF.EmitBlock(TerminateBB);
    CGF.EmitRuntimeCall(
        createNVPTXRuntimeFunction(OMPRTL_NVPTX__kmpc_kernel_end_parallel),
        llvm::None);
    CGF.EmitBranch(BarrierBB);
  
    // All active and inactive workers wait at a barrier after parallel region.
    CGF.EmitBlock(BarrierBB);
    // Barrier after parallel region.
    syncCTAThreads(CGF);
    CGF.EmitBranch(AwaitBB);
  
    // Exit target region.
    CGF.EmitBlock(ExitBB);
  }
  
  /// \brief Returns specified OpenMP runtime function for the current OpenMP
  /// implementation.  Specialized for the NVPTX device.
  /// \param Function OpenMP runtime function.
  /// \return Specified function.
  llvm::Constant *
  CGOpenMPRuntimeNVPTX::createNVPTXRuntimeFunction(unsigned Function) {
    llvm::Constant *RTLFn = nullptr;
    switch (static_cast<OpenMPRTLFunctionNVPTX>(Function)) {
    case OMPRTL_NVPTX__kmpc_kernel_init: {
      // Build void __kmpc_kernel_init(kmp_int32 thread_limit, int16_t
      // RequiresOMPRuntime);
      llvm::Type *TypeParams[] = {CGM.Int32Ty, CGM.Int16Ty};
      auto *FnTy =
          llvm::FunctionType::get(CGM.VoidTy, TypeParams, /*isVarArg*/ false);
      RTLFn = CGM.CreateRuntimeFunction(FnTy, "__kmpc_kernel_init");
      break;
    }
    case OMPRTL_NVPTX__kmpc_kernel_deinit: {
      // Build void __kmpc_kernel_deinit(int16_t IsOMPRuntimeInitialized);
      llvm::Type *TypeParams[] = {CGM.Int16Ty};
      auto *FnTy =
          llvm::FunctionType::get(CGM.VoidTy, TypeParams, /*isVarArg*/ false);
      RTLFn = CGM.CreateRuntimeFunction(FnTy, "__kmpc_kernel_deinit");
      break;
    }
    case OMPRTL_NVPTX__kmpc_spmd_kernel_init: {
      // Build void __kmpc_spmd_kernel_init(kmp_int32 thread_limit,
      // int16_t RequiresOMPRuntime, int16_t RequiresDataSharing);
      llvm::Type *TypeParams[] = {CGM.Int32Ty, CGM.Int16Ty, CGM.Int16Ty};
      auto *FnTy =
          llvm::FunctionType::get(CGM.VoidTy, TypeParams, /*isVarArg*/ false);
      RTLFn = CGM.CreateRuntimeFunction(FnTy, "__kmpc_spmd_kernel_init");
      break;
    }
    case OMPRTL_NVPTX__kmpc_spmd_kernel_deinit: {
      // Build void __kmpc_spmd_kernel_deinit();
      auto *FnTy =
          llvm::FunctionType::get(CGM.VoidTy, llvm::None, /*isVarArg*/ false);
      RTLFn = CGM.CreateRuntimeFunction(FnTy, "__kmpc_spmd_kernel_deinit");
      break;
    }
    case OMPRTL_NVPTX__kmpc_kernel_prepare_parallel: {
      /// Build void __kmpc_kernel_prepare_parallel(
      /// void *outlined_function, int16_t IsOMPRuntimeInitialized);
      llvm::Type *TypeParams[] = {CGM.Int8PtrTy, CGM.Int16Ty};
      auto *FnTy =
          llvm::FunctionType::get(CGM.VoidTy, TypeParams, /*isVarArg*/ false);
      RTLFn = CGM.CreateRuntimeFunction(FnTy, "__kmpc_kernel_prepare_parallel");
      break;
    }
    case OMPRTL_NVPTX__kmpc_kernel_parallel: {
      /// Build bool __kmpc_kernel_parallel(void **outlined_function,
      /// int16_t IsOMPRuntimeInitialized);
      llvm::Type *TypeParams[] = {CGM.Int8PtrPtrTy, CGM.Int16Ty};
      llvm::Type *RetTy = CGM.getTypes().ConvertType(CGM.getContext().BoolTy);
      auto *FnTy =
          llvm::FunctionType::get(RetTy, TypeParams, /*isVarArg*/ false);
      RTLFn = CGM.CreateRuntimeFunction(FnTy, "__kmpc_kernel_parallel");
      break;
    }
    case OMPRTL_NVPTX__kmpc_kernel_end_parallel: {
      /// Build void __kmpc_kernel_end_parallel();
      auto *FnTy =
          llvm::FunctionType::get(CGM.VoidTy, llvm::None, /*isVarArg*/ false);
      RTLFn = CGM.CreateRuntimeFunction(FnTy, "__kmpc_kernel_end_parallel");
      break;
    }
    case OMPRTL_NVPTX__kmpc_serialized_parallel: {
      // Build void __kmpc_serialized_parallel(ident_t *loc, kmp_int32
      // global_tid);
      llvm::Type *TypeParams[] = {getIdentTyPointerTy(), CGM.Int32Ty};
      auto *FnTy =
          llvm::FunctionType::get(CGM.VoidTy, TypeParams, /*isVarArg*/ false);
      RTLFn = CGM.CreateRuntimeFunction(FnTy, "__kmpc_serialized_parallel");
      break;
    }
    case OMPRTL_NVPTX__kmpc_end_serialized_parallel: {
      // Build void __kmpc_end_serialized_parallel(ident_t *loc, kmp_int32
      // global_tid);
      llvm::Type *TypeParams[] = {getIdentTyPointerTy(), CGM.Int32Ty};
      auto *FnTy =
          llvm::FunctionType::get(CGM.VoidTy, TypeParams, /*isVarArg*/ false);
      RTLFn = CGM.CreateRuntimeFunction(FnTy, "__kmpc_end_serialized_parallel");
      break;
    }
    case OMPRTL_NVPTX__kmpc_shuffle_int32: {
      // Build int32_t __kmpc_shuffle_int32(int32_t element,
      // int16_t lane_offset, int16_t warp_size);
      llvm::Type *TypeParams[] = {CGM.Int32Ty, CGM.Int16Ty, CGM.Int16Ty};
      auto *FnTy =
          llvm::FunctionType::get(CGM.Int32Ty, TypeParams, /*isVarArg*/ false);
      RTLFn = CGM.CreateRuntimeFunction(FnTy, "__kmpc_shuffle_int32");
      break;
    }
    case OMPRTL_NVPTX__kmpc_shuffle_int64: {
      // Build int64_t __kmpc_shuffle_int64(int64_t element,
      // int16_t lane_offset, int16_t warp_size);
      llvm::Type *TypeParams[] = {CGM.Int64Ty, CGM.Int16Ty, CGM.Int16Ty};
      auto *FnTy =
          llvm::FunctionType::get(CGM.Int64Ty, TypeParams, /*isVarArg*/ false);
      RTLFn = CGM.CreateRuntimeFunction(FnTy, "__kmpc_shuffle_int64");
      break;
    }
    case OMPRTL_NVPTX__kmpc_parallel_reduce_nowait: {
      // Build int32_t kmpc_nvptx_parallel_reduce_nowait(kmp_int32 global_tid,
      // kmp_int32 num_vars, size_t reduce_size, void* reduce_data,
      // void (*kmp_ShuffleReductFctPtr)(void *rhsData, int16_t lane_id, int16_t
      // lane_offset, int16_t Algorithm Version),
      // void (*kmp_InterWarpCopyFctPtr)(void* src, int warp_num));
      llvm::Type *ShuffleReduceTypeParams[] = {CGM.VoidPtrTy, CGM.Int16Ty,
                                               CGM.Int16Ty, CGM.Int16Ty};
      auto *ShuffleReduceFnTy =
          llvm::FunctionType::get(CGM.VoidTy, ShuffleReduceTypeParams,
                                  /*isVarArg=*/false);
      llvm::Type *InterWarpCopyTypeParams[] = {CGM.VoidPtrTy, CGM.Int32Ty};
      auto *InterWarpCopyFnTy =
          llvm::FunctionType::get(CGM.VoidTy, InterWarpCopyTypeParams,
                                  /*isVarArg=*/false);
      llvm::Type *TypeParams[] = {CGM.Int32Ty,
                                  CGM.Int32Ty,
                                  CGM.SizeTy,
                                  CGM.VoidPtrTy,
                                  ShuffleReduceFnTy->getPointerTo(),
                                  InterWarpCopyFnTy->getPointerTo()};
      auto *FnTy =
          llvm::FunctionType::get(CGM.Int32Ty, TypeParams, /*isVarArg=*/false);
      RTLFn = CGM.CreateRuntimeFunction(
          FnTy, /*Name=*/"__kmpc_nvptx_parallel_reduce_nowait");
      break;
    }
    case OMPRTL_NVPTX__kmpc_simd_reduce_nowait: {
      // Build int32_t kmpc_nvptx_simd_reduce_nowait(kmp_int32 global_tid,
      // kmp_int32 num_vars, size_t reduce_size, void* reduce_data,
      // void (*kmp_ShuffleReductFctPtr)(void *rhsData, int16_t lane_id, int16_t
      // lane_offset, int16_t Algorithm Version),
      // void (*kmp_InterWarpCopyFctPtr)(void* src, int warp_num));
      llvm::Type *ShuffleReduceTypeParams[] = {CGM.VoidPtrTy, CGM.Int16Ty,
                                               CGM.Int16Ty, CGM.Int16Ty};
      auto *ShuffleReduceFnTy =
          llvm::FunctionType::get(CGM.VoidTy, ShuffleReduceTypeParams,
                                  /*isVarArg=*/false);
      llvm::Type *InterWarpCopyTypeParams[] = {CGM.VoidPtrTy, CGM.Int32Ty};
      auto *InterWarpCopyFnTy =
          llvm::FunctionType::get(CGM.VoidTy, InterWarpCopyTypeParams,
                                  /*isVarArg=*/false);
      llvm::Type *TypeParams[] = {CGM.Int32Ty,
                                  CGM.Int32Ty,
                                  CGM.SizeTy,
                                  CGM.VoidPtrTy,
                                  ShuffleReduceFnTy->getPointerTo(),
                                  InterWarpCopyFnTy->getPointerTo()};
      auto *FnTy =
          llvm::FunctionType::get(CGM.Int32Ty, TypeParams, /*isVarArg=*/false);
      RTLFn = CGM.CreateRuntimeFunction(
          FnTy, /*Name=*/"__kmpc_nvptx_simd_reduce_nowait");
      break;
    }
    case OMPRTL_NVPTX__kmpc_teams_reduce_nowait: {
      // Build int32_t __kmpc_nvptx_teams_reduce_nowait(int32_t global_tid,
      // int32_t num_vars, size_t reduce_size, void *reduce_data,
      // void (*kmp_ShuffleReductFctPtr)(void *rhsData, int16_t lane_id, int16_t
      // lane_offset, int16_t shortCircuit),
      // void (*kmp_InterWarpCopyFctPtr)(void* src, int32_t warp_num),
      // void (*kmp_CopyToScratchpadFctPtr)(void *reduce_data, void * scratchpad,
      // int32_t index, int32_t width),
      // void (*kmp_LoadReduceFctPtr)(void *reduce_data, void * scratchpad,
      // int32_t index, int32_t width, int32_t reduce))
      llvm::Type *ShuffleReduceTypeParams[] = {CGM.VoidPtrTy, CGM.Int16Ty,
                                               CGM.Int16Ty, CGM.Int16Ty};
      auto *ShuffleReduceFnTy =
          llvm::FunctionType::get(CGM.VoidTy, ShuffleReduceTypeParams,
                                  /*isVarArg=*/false);
      llvm::Type *InterWarpCopyTypeParams[] = {CGM.VoidPtrTy, CGM.Int32Ty};
      auto *InterWarpCopyFnTy =
          llvm::FunctionType::get(CGM.VoidTy, InterWarpCopyTypeParams,
                                  /*isVarArg=*/false);
      llvm::Type *CopyToScratchpadTypeParams[] = {CGM.VoidPtrTy, CGM.VoidPtrTy,
                                                  CGM.Int32Ty, CGM.Int32Ty};
      auto *CopyToScratchpadFnTy =
          llvm::FunctionType::get(CGM.VoidTy, CopyToScratchpadTypeParams,
                                  /*isVarArg=*/false);
      llvm::Type *LoadReduceTypeParams[] = {
          CGM.VoidPtrTy, CGM.VoidPtrTy, CGM.Int32Ty, CGM.Int32Ty, CGM.Int32Ty};
      auto *LoadReduceFnTy =
          llvm::FunctionType::get(CGM.VoidTy, LoadReduceTypeParams,
                                  /*isVarArg=*/false);
      llvm::Type *TypeParams[] = {CGM.Int32Ty,
                                  CGM.Int32Ty,
                                  CGM.SizeTy,
                                  CGM.VoidPtrTy,
                                  ShuffleReduceFnTy->getPointerTo(),
                                  InterWarpCopyFnTy->getPointerTo(),
                                  CopyToScratchpadFnTy->getPointerTo(),
                                  LoadReduceFnTy->getPointerTo()};
      auto *FnTy =
          llvm::FunctionType::get(CGM.Int32Ty, TypeParams, /*isVarArg=*/false);
      RTLFn = CGM.CreateRuntimeFunction(
          FnTy, /*Name=*/"__kmpc_nvptx_teams_reduce_nowait");
      break;
    }
    case OMPRTL_NVPTX__kmpc_end_reduce_nowait: {
      // Build __kmpc_end_reduce_nowait(kmp_int32 global_tid);
      llvm::Type *TypeParams[] = {CGM.Int32Ty};
      auto *FnTy =
          llvm::FunctionType::get(CGM.VoidTy, TypeParams, /*isVarArg=*/false);
      RTLFn = CGM.CreateRuntimeFunction(
          FnTy, /*Name=*/"__kmpc_nvptx_end_reduce_nowait");
      break;
    }
    case OMPRTL_NVPTX__kmpc_data_sharing_init_stack: {
      /// Build void __kmpc_data_sharing_init_stack();
      auto *FnTy =
          llvm::FunctionType::get(CGM.VoidTy, llvm::None, /*isVarArg*/ false);
      RTLFn = CGM.CreateRuntimeFunction(FnTy, "__kmpc_data_sharing_init_stack");
      break;
    }
    case OMPRTL_NVPTX__kmpc_data_sharing_push_stack: {
      // Build void *__kmpc_data_sharing_push_stack(size_t size,
      // int16_t UseSharedMemory);
      llvm::Type *TypeParams[] = {CGM.SizeTy, CGM.Int16Ty};
      auto *FnTy =
          llvm::FunctionType::get(CGM.VoidPtrTy, TypeParams, /*isVarArg=*/false);
      RTLFn = CGM.CreateRuntimeFunction(
          FnTy, /*Name=*/"__kmpc_data_sharing_push_stack");
      break;
    }
    case OMPRTL_NVPTX__kmpc_data_sharing_pop_stack: {
      // Build void __kmpc_data_sharing_pop_stack(void *a);
      llvm::Type *TypeParams[] = {CGM.VoidPtrTy};
      auto *FnTy =
          llvm::FunctionType::get(CGM.VoidTy, TypeParams, /*isVarArg=*/false);
      RTLFn = CGM.CreateRuntimeFunction(FnTy,
                                        /*Name=*/"__kmpc_data_sharing_pop_stack");
      break;
    }
    case OMPRTL_NVPTX__kmpc_begin_sharing_variables: {
      /// Build void __kmpc_begin_sharing_variables(void ***args,
      /// size_t n_args);
      llvm::Type *TypeParams[] = {CGM.Int8PtrPtrTy->getPointerTo(), CGM.SizeTy};
      auto *FnTy =
          llvm::FunctionType::get(CGM.VoidTy, TypeParams, /*isVarArg*/ false);
      RTLFn = CGM.CreateRuntimeFunction(FnTy, "__kmpc_begin_sharing_variables");
      break;
    }
    case OMPRTL_NVPTX__kmpc_end_sharing_variables: {
      /// Build void __kmpc_end_sharing_variables();
      auto *FnTy =
          llvm::FunctionType::get(CGM.VoidTy, llvm::None, /*isVarArg*/ false);
      RTLFn = CGM.CreateRuntimeFunction(FnTy, "__kmpc_end_sharing_variables");
      break;
    }
    case OMPRTL_NVPTX__kmpc_get_shared_variables: {
      /// Build void __kmpc_get_shared_variables(void ***GlobalArgs);
      llvm::Type *TypeParams[] = {CGM.Int8PtrPtrTy->getPointerTo()};
      auto *FnTy =
          llvm::FunctionType::get(CGM.VoidTy, TypeParams, /*isVarArg*/ false);
      RTLFn = CGM.CreateRuntimeFunction(FnTy, "__kmpc_get_shared_variables");
      break;
    }
    }
    return RTLFn;
  }
  
  void CGOpenMPRuntimeNVPTX::createOffloadEntry(llvm::Constant *ID,
                                                llvm::Constant *Addr,
                                                uint64_t Size, int32_t,
                                                llvm::GlobalValue::LinkageTypes) {
    // TODO: Add support for global variables on the device after declare target
    // support.
    if (!isa<llvm::Function>(Addr))
      return;
    llvm::Module &M = CGM.getModule();
    llvm::LLVMContext &Ctx = CGM.getLLVMContext();
  
    // Get "nvvm.annotations" metadata node
    llvm::NamedMDNode *MD = M.getOrInsertNamedMetadata("nvvm.annotations");
  
    llvm::Metadata *MDVals[] = {
        llvm::ConstantAsMetadata::get(Addr), llvm::MDString::get(Ctx, "kernel"),
        llvm::ConstantAsMetadata::get(
            llvm::ConstantInt::get(llvm::Type::getInt32Ty(Ctx), 1))};
    // Append metadata to nvvm.annotations
    MD->addOperand(llvm::MDNode::get(Ctx, MDVals));
  }
  
  void CGOpenMPRuntimeNVPTX::emitTargetOutlinedFunction(
      const OMPExecutableDirective &D, StringRef ParentName,
      llvm::Function *&OutlinedFn, llvm::Constant *&OutlinedFnID,
      bool IsOffloadEntry, const RegionCodeGenTy &CodeGen) {
    if (!IsOffloadEntry) // Nothing to do.
      return;
  
    assert(!ParentName.empty() && "Invalid target region parent name!");
  
    CGOpenMPRuntimeNVPTX::ExecutionMode Mode = getExecutionMode(CGM);
    switch (Mode) {
    case CGOpenMPRuntimeNVPTX::ExecutionMode::Generic:
      emitGenericKernel(D, ParentName, OutlinedFn, OutlinedFnID, IsOffloadEntry,
                        CodeGen);
      break;
    case CGOpenMPRuntimeNVPTX::ExecutionMode::Spmd:
      emitSpmdKernel(D, ParentName, OutlinedFn, OutlinedFnID, IsOffloadEntry,
                     CodeGen);
      break;
    case CGOpenMPRuntimeNVPTX::ExecutionMode::Unknown:
      llvm_unreachable(
          "Unknown programming model for OpenMP directive on NVPTX target.");
    }
  
    setPropertyExecutionMode(CGM, OutlinedFn->getName(), Mode);
  }
  
  CGOpenMPRuntimeNVPTX::CGOpenMPRuntimeNVPTX(CodeGenModule &CGM)
      : CGOpenMPRuntime(CGM, "_", "$"),
        CurrentExecutionMode(ExecutionMode::Unknown) {
    if (!CGM.getLangOpts().OpenMPIsDevice)
      llvm_unreachable("OpenMP NVPTX can only handle device code.");
  }
  
  void CGOpenMPRuntimeNVPTX::emitProcBindClause(CodeGenFunction &CGF,
                                                OpenMPProcBindClauseKind ProcBind,
                                                SourceLocation Loc) {
    // Do nothing in case of Spmd mode and L0 parallel.
    // TODO: If in Spmd mode and L1 parallel emit the clause.
    if (isInSpmdExecutionMode())
      return;
  
    CGOpenMPRuntime::emitProcBindClause(CGF, ProcBind, Loc);
  }
  
  void CGOpenMPRuntimeNVPTX::emitNumThreadsClause(CodeGenFunction &CGF,
                                                  llvm::Value *NumThreads,
                                                  SourceLocation Loc) {
    // Do nothing in case of Spmd mode and L0 parallel.
    // TODO: If in Spmd mode and L1 parallel emit the clause.
    if (isInSpmdExecutionMode())
      return;
  
    CGOpenMPRuntime::emitNumThreadsClause(CGF, NumThreads, Loc);
  }
  
  void CGOpenMPRuntimeNVPTX::emitNumTeamsClause(CodeGenFunction &CGF,
                                                const Expr *NumTeams,
                                                const Expr *ThreadLimit,
                                                SourceLocation Loc) {}
  
  llvm::Value *CGOpenMPRuntimeNVPTX::emitParallelOutlinedFunction(
      const OMPExecutableDirective &D, const VarDecl *ThreadIDVar,
      OpenMPDirectiveKind InnermostKind, const RegionCodeGenTy &CodeGen) {
    SourceLocation Loc = D.getLocStart();
  
    // Emit target region as a standalone region.
    class NVPTXPrePostActionTy : public PrePostActionTy {
      SourceLocation &Loc;
  
    public:
      NVPTXPrePostActionTy(SourceLocation &Loc) : Loc(Loc) {}
      void Enter(CodeGenFunction &CGF) override {
        static_cast<CGOpenMPRuntimeNVPTX &>(CGF.CGM.getOpenMPRuntime())
            .emitGenericVarsProlog(CGF, Loc);
      }
      void Exit(CodeGenFunction &CGF) override {
        static_cast<CGOpenMPRuntimeNVPTX &>(CGF.CGM.getOpenMPRuntime())
            .emitGenericVarsEpilog(CGF);
      }
    } Action(Loc);
    CodeGen.setAction(Action);
    auto *OutlinedFun =
        cast<llvm::Function>(CGOpenMPRuntime::emitParallelOutlinedFunction(
            D, ThreadIDVar, InnermostKind, CodeGen));
    if (!isInSpmdExecutionMode()) {
      llvm::Function *WrapperFun =
          createParallelDataSharingWrapper(OutlinedFun, D);
      WrapperFunctionsMap[OutlinedFun] = WrapperFun;
    }
  
    return OutlinedFun;
  }
  
  llvm::Value *CGOpenMPRuntimeNVPTX::emitTeamsOutlinedFunction(
      const OMPExecutableDirective &D, const VarDecl *ThreadIDVar,
      OpenMPDirectiveKind InnermostKind, const RegionCodeGenTy &CodeGen) {
    SourceLocation Loc = D.getLocStart();
  
    // Emit target region as a standalone region.
    class NVPTXPrePostActionTy : public PrePostActionTy {
      SourceLocation &Loc;
  
    public:
      NVPTXPrePostActionTy(SourceLocation &Loc) : Loc(Loc) {}
      void Enter(CodeGenFunction &CGF) override {
        static_cast<CGOpenMPRuntimeNVPTX &>(CGF.CGM.getOpenMPRuntime())
            .emitGenericVarsProlog(CGF, Loc);
      }
      void Exit(CodeGenFunction &CGF) override {
        static_cast<CGOpenMPRuntimeNVPTX &>(CGF.CGM.getOpenMPRuntime())
            .emitGenericVarsEpilog(CGF);
      }
    } Action(Loc);
    CodeGen.setAction(Action);
    llvm::Value *OutlinedFunVal = CGOpenMPRuntime::emitTeamsOutlinedFunction(
        D, ThreadIDVar, InnermostKind, CodeGen);
    llvm::Function *OutlinedFun = cast<llvm::Function>(OutlinedFunVal);
    OutlinedFun->removeFnAttr(llvm::Attribute::NoInline);
    OutlinedFun->removeFnAttr(llvm::Attribute::OptimizeNone);
    OutlinedFun->addFnAttr(llvm::Attribute::AlwaysInline);
  
    return OutlinedFun;
  }
  
  void CGOpenMPRuntimeNVPTX::emitGenericVarsProlog(CodeGenFunction &CGF,
                                                   SourceLocation Loc) {
    CGBuilderTy &Bld = CGF.Builder;
  
    const auto I = FunctionGlobalizedDecls.find(CGF.CurFn);
    if (I == FunctionGlobalizedDecls.end())
      return;
    if (const RecordDecl *GlobalizedVarsRecord = I->getSecond().GlobalRecord) {
      QualType RecTy = CGM.getContext().getRecordType(GlobalizedVarsRecord);
  
      // Recover pointer to this function's global record. The runtime will
      // handle the specifics of the allocation of the memory.
      // Use actual memory size of the record including the padding
      // for alignment purposes.
      unsigned Alignment =
          CGM.getContext().getTypeAlignInChars(RecTy).getQuantity();
      unsigned GlobalRecordSize =
          CGM.getContext().getTypeSizeInChars(RecTy).getQuantity();
      GlobalRecordSize = llvm::alignTo(GlobalRecordSize, Alignment);
      // TODO: allow the usage of shared memory to be controlled by
      // the user, for now, default to global.
      llvm::Value *GlobalRecordSizeArg[] = {
          llvm::ConstantInt::get(CGM.SizeTy, GlobalRecordSize),
          CGF.Builder.getInt16(/*UseSharedMemory=*/0)};
      llvm::Value *GlobalRecValue = CGF.EmitRuntimeCall(
          createNVPTXRuntimeFunction(OMPRTL_NVPTX__kmpc_data_sharing_push_stack),
          GlobalRecordSizeArg);
      llvm::Value *GlobalRecCastAddr = Bld.CreatePointerBitCastOrAddrSpaceCast(
          GlobalRecValue, CGF.ConvertTypeForMem(RecTy)->getPointerTo());
      LValue Base =
          CGF.MakeNaturalAlignPointeeAddrLValue(GlobalRecCastAddr, RecTy);
      I->getSecond().GlobalRecordAddr = GlobalRecValue;
  
      // Emit the "global alloca" which is a GEP from the global declaration
      // record using the pointer returned by the runtime.
      for (auto &Rec : I->getSecond().LocalVarData) {
        bool EscapedParam = I->getSecond().EscapedParameters.count(Rec.first);
        llvm::Value *ParValue;
        if (EscapedParam) {
          const auto *VD = cast<VarDecl>(Rec.first);
          LValue ParLVal =
              CGF.MakeAddrLValue(CGF.GetAddrOfLocalVar(VD), VD->getType());
          ParValue = CGF.EmitLoadOfScalar(ParLVal, Loc);
        }
        const FieldDecl *FD = Rec.second.first;
        LValue VarAddr = CGF.EmitLValueForField(Base, FD);
        Rec.second.second = VarAddr.getAddress();
        if (EscapedParam) {
          const auto *VD = cast<VarDecl>(Rec.first);
          CGF.EmitStoreOfScalar(ParValue, VarAddr);
          I->getSecond().MappedParams->setVarAddr(CGF, VD, VarAddr.getAddress());
        }
      }
    }
    for (const ValueDecl *VD : I->getSecond().EscapedVariableLengthDecls) {
      // Recover pointer to this function's global record. The runtime will
      // handle the specifics of the allocation of the memory.
      // Use actual memory size of the record including the padding
      // for alignment purposes.
      CGBuilderTy &Bld = CGF.Builder;
      llvm::Value *Size = CGF.getTypeSize(VD->getType());
      CharUnits Align = CGM.getContext().getDeclAlign(VD);
      Size = Bld.CreateNUWAdd(
          Size, llvm::ConstantInt::get(CGF.SizeTy, Align.getQuantity() - 1));
      llvm::Value *AlignVal =
          llvm::ConstantInt::get(CGF.SizeTy, Align.getQuantity());
      Size = Bld.CreateUDiv(Size, AlignVal);
      Size = Bld.CreateNUWMul(Size, AlignVal);
      // TODO: allow the usage of shared memory to be controlled by
      // the user, for now, default to global.
      llvm::Value *GlobalRecordSizeArg[] = {
          Size, CGF.Builder.getInt16(/*UseSharedMemory=*/0)};
      llvm::Value *GlobalRecValue = CGF.EmitRuntimeCall(
          createNVPTXRuntimeFunction(OMPRTL_NVPTX__kmpc_data_sharing_push_stack),
          GlobalRecordSizeArg);
      llvm::Value *GlobalRecCastAddr = Bld.CreatePointerBitCastOrAddrSpaceCast(
          GlobalRecValue, CGF.ConvertTypeForMem(VD->getType())->getPointerTo());
      LValue Base = CGF.MakeAddrLValue(GlobalRecCastAddr, VD->getType(),
                                       CGM.getContext().getDeclAlign(VD),
                                       AlignmentSource::Decl);
      I->getSecond().MappedParams->setVarAddr(CGF, cast<VarDecl>(VD),
                                              Base.getAddress());
      I->getSecond().EscapedVariableLengthDeclsAddrs.emplace_back(GlobalRecValue);
    }
    I->getSecond().MappedParams->apply(CGF);
  }
  
  void CGOpenMPRuntimeNVPTX::emitGenericVarsEpilog(CodeGenFunction &CGF) {
    const auto I = FunctionGlobalizedDecls.find(CGF.CurFn);
    if (I != FunctionGlobalizedDecls.end()) {
      I->getSecond().MappedParams->restore(CGF);
      if (!CGF.HaveInsertPoint())
        return;
      for (llvm::Value *Addr :
           llvm::reverse(I->getSecond().EscapedVariableLengthDeclsAddrs)) {
        CGF.EmitRuntimeCall(
            createNVPTXRuntimeFunction(OMPRTL_NVPTX__kmpc_data_sharing_pop_stack),
            Addr);
      }
      if (I->getSecond().GlobalRecordAddr) {
        CGF.EmitRuntimeCall(
            createNVPTXRuntimeFunction(OMPRTL_NVPTX__kmpc_data_sharing_pop_stack),
            I->getSecond().GlobalRecordAddr);
      }
    }
  }
  
  void CGOpenMPRuntimeNVPTX::emitTeamsCall(CodeGenFunction &CGF,
                                           const OMPExecutableDirective &D,
                                           SourceLocation Loc,
                                           llvm::Value *OutlinedFn,
                                           ArrayRef<llvm::Value *> CapturedVars) {
    if (!CGF.HaveInsertPoint())
      return;
  
    Address ZeroAddr = CGF.CreateMemTemp(
        CGF.getContext().getIntTypeForBitwidth(/*DestWidth=*/32, /*Signed=*/1),
        /*Name*/ ".zero.addr");
    CGF.InitTempAlloca(ZeroAddr, CGF.Builder.getInt32(/*C*/ 0));
    llvm::SmallVector<llvm::Value *, 16> OutlinedFnArgs;
    OutlinedFnArgs.push_back(emitThreadIDAddress(CGF, Loc).getPointer());
    OutlinedFnArgs.push_back(ZeroAddr.getPointer());
    OutlinedFnArgs.append(CapturedVars.begin(), CapturedVars.end());
    emitOutlinedFunctionCall(CGF, Loc, OutlinedFn, OutlinedFnArgs);
  }
  
  void CGOpenMPRuntimeNVPTX::emitParallelCall(
      CodeGenFunction &CGF, SourceLocation Loc, llvm::Value *OutlinedFn,
      ArrayRef<llvm::Value *> CapturedVars, const Expr *IfCond) {
    if (!CGF.HaveInsertPoint())
      return;
  
    if (isInSpmdExecutionMode())
      emitSpmdParallelCall(CGF, Loc, OutlinedFn, CapturedVars, IfCond);
    else
      emitGenericParallelCall(CGF, Loc, OutlinedFn, CapturedVars, IfCond);
  }
  
  void CGOpenMPRuntimeNVPTX::emitGenericParallelCall(
      CodeGenFunction &CGF, SourceLocation Loc, llvm::Value *OutlinedFn,
      ArrayRef<llvm::Value *> CapturedVars, const Expr *IfCond) {
    llvm::Function *Fn = cast<llvm::Function>(OutlinedFn);
    llvm::Function *WFn = WrapperFunctionsMap[Fn];
  
    assert(WFn && "Wrapper function does not exist!");
  
    // Force inline this outlined function at its call site.
    Fn->setLinkage(llvm::GlobalValue::InternalLinkage);
  
    auto &&L0ParallelGen = [this, WFn, CapturedVars](CodeGenFunction &CGF,
                                                      PrePostActionTy &) {
      CGBuilderTy &Bld = CGF.Builder;
  
      llvm::Value *ID = Bld.CreateBitOrPointerCast(WFn, CGM.Int8PtrTy);
  
      // Prepare for parallel region. Indicate the outlined function.
      llvm::Value *Args[] = {ID, /*RequiresOMPRuntime=*/Bld.getInt16(1)};
      CGF.EmitRuntimeCall(createNVPTXRuntimeFunction(
                              OMPRTL_NVPTX__kmpc_kernel_prepare_parallel),
                          Args);
  
      // Create a private scope that will globalize the arguments
      // passed from the outside of the target region.
      CodeGenFunction::OMPPrivateScope PrivateArgScope(CGF);
  
      // There's somehting to share.
      if (!CapturedVars.empty()) {
        // Prepare for parallel region. Indicate the outlined function.
        Address SharedArgs =
            CGF.CreateDefaultAlignTempAlloca(CGF.VoidPtrPtrTy, "shared_arg_refs");
        llvm::Value *SharedArgsPtr = SharedArgs.getPointer();
  
        llvm::Value *DataSharingArgs[] = {
            SharedArgsPtr,
            llvm::ConstantInt::get(CGM.SizeTy, CapturedVars.size())};
        CGF.EmitRuntimeCall(createNVPTXRuntimeFunction(
                                OMPRTL_NVPTX__kmpc_begin_sharing_variables),
                            DataSharingArgs);
  
        // Store variable address in a list of references to pass to workers.
        unsigned Idx = 0;
        ASTContext &Ctx = CGF.getContext();
        Address SharedArgListAddress = CGF.EmitLoadOfPointer(SharedArgs,
            Ctx.getPointerType(Ctx.getPointerType(Ctx.VoidPtrTy))
                .castAs<PointerType>());
        for (llvm::Value *V : CapturedVars) {
          Address Dst = Bld.CreateConstInBoundsGEP(
              SharedArgListAddress, Idx, CGF.getPointerSize());
          llvm::Value * PtrV;
          if (V->getType()->isIntegerTy())
            PtrV = Bld.CreateIntToPtr(V, CGF.VoidPtrTy);
          else
            PtrV = Bld.CreatePointerBitCastOrAddrSpaceCast(V, CGF.VoidPtrTy);
          CGF.EmitStoreOfScalar(PtrV, Dst, /*Volatile=*/false,
                                Ctx.getPointerType(Ctx.VoidPtrTy));
          ++Idx;
        }
      }
  
      // Activate workers. This barrier is used by the master to signal
      // work for the workers.
      syncCTAThreads(CGF);
  
      // OpenMP [2.5, Parallel Construct, p.49]
      // There is an implied barrier at the end of a parallel region. After the
      // end of a parallel region, only the master thread of the team resumes
      // execution of the enclosing task region.
      //
      // The master waits at this barrier until all workers are done.
      syncCTAThreads(CGF);
  
      if (!CapturedVars.empty())
        CGF.EmitRuntimeCall(
            createNVPTXRuntimeFunction(OMPRTL_NVPTX__kmpc_end_sharing_variables));
  
      // Remember for post-processing in worker loop.
      Work.emplace_back(WFn);
    };
  
    llvm::Value *RTLoc = emitUpdateLocation(CGF, Loc);
    llvm::Value *ThreadID = getThreadID(CGF, Loc);
    llvm::Value *Args[] = {RTLoc, ThreadID};
  
    auto &&SeqGen = [this, Fn, CapturedVars, &Args, Loc](CodeGenFunction &CGF,
                                                         PrePostActionTy &) {
      auto &&CodeGen = [this, Fn, CapturedVars, Loc](CodeGenFunction &CGF,
                                                     PrePostActionTy &Action) {
        Action.Enter(CGF);
  
        llvm::SmallVector<llvm::Value *, 16> OutlinedFnArgs;
        Address ZeroAddr =
            CGF.CreateMemTemp(CGF.getContext().getIntTypeForBitwidth(
                                  /*DestWidth=*/32, /*Signed=*/1),
                              ".zero.addr");
        CGF.InitTempAlloca(ZeroAddr, CGF.Builder.getInt32(/*C*/ 0));
        OutlinedFnArgs.push_back(emitThreadIDAddress(CGF, Loc).getPointer());
        OutlinedFnArgs.push_back(ZeroAddr.getPointer());
        OutlinedFnArgs.append(CapturedVars.begin(), CapturedVars.end());
        emitOutlinedFunctionCall(CGF, Loc, Fn, OutlinedFnArgs);
      };
  
      RegionCodeGenTy RCG(CodeGen);
      NVPTXActionTy Action(
          createNVPTXRuntimeFunction(OMPRTL_NVPTX__kmpc_serialized_parallel),
          Args,
          createNVPTXRuntimeFunction(OMPRTL_NVPTX__kmpc_end_serialized_parallel),
          Args);
      RCG.setAction(Action);
      RCG(CGF);
    };
  
    if (IfCond) {
      emitOMPIfClause(CGF, IfCond, L0ParallelGen, SeqGen);
    } else {
      CodeGenFunction::RunCleanupsScope Scope(CGF);
      RegionCodeGenTy ThenRCG(L0ParallelGen);
      ThenRCG(CGF);
    }
  }
  
  void CGOpenMPRuntimeNVPTX::emitSpmdParallelCall(
      CodeGenFunction &CGF, SourceLocation Loc, llvm::Value *OutlinedFn,
      ArrayRef<llvm::Value *> CapturedVars, const Expr *IfCond) {
    // Just call the outlined function to execute the parallel region.
    // OutlinedFn(&GTid, &zero, CapturedStruct);
    //
    // TODO: Do something with IfCond when support for the 'if' clause
    // is added on Spmd target directives.
    llvm::SmallVector<llvm::Value *, 16> OutlinedFnArgs;
  
    Address ZeroAddr = CGF.CreateMemTemp(
        CGF.getContext().getIntTypeForBitwidth(/*DestWidth=*/32, /*Signed=*/1),
        ".zero.addr");
    CGF.InitTempAlloca(ZeroAddr, CGF.Builder.getInt32(/*C*/ 0));
    OutlinedFnArgs.push_back(emitThreadIDAddress(CGF, Loc).getPointer());
    OutlinedFnArgs.push_back(ZeroAddr.getPointer());
    OutlinedFnArgs.append(CapturedVars.begin(), CapturedVars.end());
    emitOutlinedFunctionCall(CGF, Loc, OutlinedFn, OutlinedFnArgs);
  }
  
  /// Cast value to the specified type.
  static llvm::Value *castValueToType(CodeGenFunction &CGF, llvm::Value *Val,
                                      QualType ValTy, QualType CastTy,
                                      SourceLocation Loc) {
    assert(!CGF.getContext().getTypeSizeInChars(CastTy).isZero() &&
           "Cast type must sized.");
    assert(!CGF.getContext().getTypeSizeInChars(ValTy).isZero() &&
           "Val type must sized.");
    llvm::Type *LLVMCastTy = CGF.ConvertTypeForMem(CastTy);
    if (ValTy == CastTy)
      return Val;
    if (CGF.getContext().getTypeSizeInChars(ValTy) ==
        CGF.getContext().getTypeSizeInChars(CastTy))
      return CGF.Builder.CreateBitCast(Val, LLVMCastTy);
    if (CastTy->isIntegerType() && ValTy->isIntegerType())
      return CGF.Builder.CreateIntCast(Val, LLVMCastTy,
                                       CastTy->hasSignedIntegerRepresentation());
    Address CastItem = CGF.CreateMemTemp(CastTy);
    Address ValCastItem = CGF.Builder.CreatePointerBitCastOrAddrSpaceCast(
        CastItem, Val->getType()->getPointerTo(CastItem.getAddressSpace()));
    CGF.EmitStoreOfScalar(Val, ValCastItem, /*Volatile=*/false, ValTy);
    return CGF.EmitLoadOfScalar(CastItem, /*Volatile=*/false, CastTy, Loc);
  }
  
  /// This function creates calls to one of two shuffle functions to copy
  /// variables between lanes in a warp.
  static llvm::Value *createRuntimeShuffleFunction(CodeGenFunction &CGF,
                                                   llvm::Value *Elem,
                                                   QualType ElemType,
                                                   llvm::Value *Offset,
                                                   SourceLocation Loc) {
    CodeGenModule &CGM = CGF.CGM;
    CGBuilderTy &Bld = CGF.Builder;
    CGOpenMPRuntimeNVPTX &RT =
        *(static_cast<CGOpenMPRuntimeNVPTX *>(&CGM.getOpenMPRuntime()));
  
    CharUnits Size = CGF.getContext().getTypeSizeInChars(ElemType);
    assert(Size.getQuantity() <= 8 &&
           "Unsupported bitwidth in shuffle instruction.");
  
    OpenMPRTLFunctionNVPTX ShuffleFn = Size.getQuantity() <= 4
                                           ? OMPRTL_NVPTX__kmpc_shuffle_int32
                                           : OMPRTL_NVPTX__kmpc_shuffle_int64;
  
    // Cast all types to 32- or 64-bit values before calling shuffle routines.
    QualType CastTy = CGF.getContext().getIntTypeForBitwidth(
        Size.getQuantity() <= 4 ? 32 : 64, /*Signed=*/1);
    llvm::Value *ElemCast = castValueToType(CGF, Elem, ElemType, CastTy, Loc);
    llvm::Value *WarpSize =
        Bld.CreateIntCast(getNVPTXWarpSize(CGF), CGM.Int16Ty, /*isSigned=*/true);
  
    llvm::Value *ShuffledVal = CGF.EmitRuntimeCall(
        RT.createNVPTXRuntimeFunction(ShuffleFn), {ElemCast, Offset, WarpSize});
  
    return castValueToType(CGF, ShuffledVal, CastTy, ElemType, Loc);
  }
  
  namespace {
  enum CopyAction : unsigned {
    // RemoteLaneToThread: Copy over a Reduce list from a remote lane in
    // the warp using shuffle instructions.
    RemoteLaneToThread,
    // ThreadCopy: Make a copy of a Reduce list on the thread's stack.
    ThreadCopy,
    // ThreadToScratchpad: Copy a team-reduced array to the scratchpad.
    ThreadToScratchpad,
    // ScratchpadToThread: Copy from a scratchpad array in global memory
    // containing team-reduced data to a thread's stack.
    ScratchpadToThread,
  };
  } // namespace
  
  struct CopyOptionsTy {
    llvm::Value *RemoteLaneOffset;
    llvm::Value *ScratchpadIndex;
    llvm::Value *ScratchpadWidth;
  };
  
  /// Emit instructions to copy a Reduce list, which contains partially
  /// aggregated values, in the specified direction.
  static void emitReductionListCopy(
      CopyAction Action, CodeGenFunction &CGF, QualType ReductionArrayTy,
      ArrayRef<const Expr *> Privates, Address SrcBase, Address DestBase,
      CopyOptionsTy CopyOptions = {nullptr, nullptr, nullptr}) {
  
    CodeGenModule &CGM = CGF.CGM;
    ASTContext &C = CGM.getContext();
    CGBuilderTy &Bld = CGF.Builder;
  
    llvm::Value *RemoteLaneOffset = CopyOptions.RemoteLaneOffset;
    llvm::Value *ScratchpadIndex = CopyOptions.ScratchpadIndex;
    llvm::Value *ScratchpadWidth = CopyOptions.ScratchpadWidth;
  
    // Iterates, element-by-element, through the source Reduce list and
    // make a copy.
    unsigned Idx = 0;
    unsigned Size = Privates.size();
    for (const Expr *Private : Privates) {
      Address SrcElementAddr = Address::invalid();
      Address DestElementAddr = Address::invalid();
      Address DestElementPtrAddr = Address::invalid();
      // Should we shuffle in an element from a remote lane?
      bool ShuffleInElement = false;
      // Set to true to update the pointer in the dest Reduce list to a
      // newly created element.
      bool UpdateDestListPtr = false;
      // Increment the src or dest pointer to the scratchpad, for each
      // new element.
      bool IncrScratchpadSrc = false;
      bool IncrScratchpadDest = false;
  
      switch (Action) {
      case RemoteLaneToThread: {
        // Step 1.1: Get the address for the src element in the Reduce list.
        Address SrcElementPtrAddr =
            Bld.CreateConstArrayGEP(SrcBase, Idx, CGF.getPointerSize());
        SrcElementAddr = CGF.EmitLoadOfPointer(
            SrcElementPtrAddr,
            C.getPointerType(Private->getType())->castAs<PointerType>());
  
        // Step 1.2: Create a temporary to store the element in the destination
        // Reduce list.
        DestElementPtrAddr =
            Bld.CreateConstArrayGEP(DestBase, Idx, CGF.getPointerSize());
        DestElementAddr =
            CGF.CreateMemTemp(Private->getType(), ".omp.reduction.element");
        ShuffleInElement = true;
        UpdateDestListPtr = true;
        break;
      }
      case ThreadCopy: {
        // Step 1.1: Get the address for the src element in the Reduce list.
        Address SrcElementPtrAddr =
            Bld.CreateConstArrayGEP(SrcBase, Idx, CGF.getPointerSize());
        SrcElementAddr = CGF.EmitLoadOfPointer(
            SrcElementPtrAddr,
            C.getPointerType(Private->getType())->castAs<PointerType>());
  
        // Step 1.2: Get the address for dest element.  The destination
        // element has already been created on the thread's stack.
        DestElementPtrAddr =
            Bld.CreateConstArrayGEP(DestBase, Idx, CGF.getPointerSize());
        DestElementAddr = CGF.EmitLoadOfPointer(
            DestElementPtrAddr,
            C.getPointerType(Private->getType())->castAs<PointerType>());
        break;
      }
      case ThreadToScratchpad: {
        // Step 1.1: Get the address for the src element in the Reduce list.
        Address SrcElementPtrAddr =
            Bld.CreateConstArrayGEP(SrcBase, Idx, CGF.getPointerSize());
        SrcElementAddr = CGF.EmitLoadOfPointer(
            SrcElementPtrAddr,
            C.getPointerType(Private->getType())->castAs<PointerType>());
  
        // Step 1.2: Get the address for dest element:
        // address = base + index * ElementSizeInChars.
        llvm::Value *ElementSizeInChars = CGF.getTypeSize(Private->getType());
        llvm::Value *CurrentOffset =
            Bld.CreateNUWMul(ElementSizeInChars, ScratchpadIndex);
        llvm::Value *ScratchPadElemAbsolutePtrVal =
            Bld.CreateNUWAdd(DestBase.getPointer(), CurrentOffset);
        ScratchPadElemAbsolutePtrVal =
            Bld.CreateIntToPtr(ScratchPadElemAbsolutePtrVal, CGF.VoidPtrTy);
        DestElementAddr = Address(ScratchPadElemAbsolutePtrVal,
                                  C.getTypeAlignInChars(Private->getType()));
        IncrScratchpadDest = true;
        break;
      }
      case ScratchpadToThread: {
        // Step 1.1: Get the address for the src element in the scratchpad.
        // address = base + index * ElementSizeInChars.
        llvm::Value *ElementSizeInChars = CGF.getTypeSize(Private->getType());
        llvm::Value *CurrentOffset =
            Bld.CreateNUWMul(ElementSizeInChars, ScratchpadIndex);
        llvm::Value *ScratchPadElemAbsolutePtrVal =
            Bld.CreateNUWAdd(SrcBase.getPointer(), CurrentOffset);
        ScratchPadElemAbsolutePtrVal =
            Bld.CreateIntToPtr(ScratchPadElemAbsolutePtrVal, CGF.VoidPtrTy);
        SrcElementAddr = Address(ScratchPadElemAbsolutePtrVal,
                                 C.getTypeAlignInChars(Private->getType()));
        IncrScratchpadSrc = true;
  
        // Step 1.2: Create a temporary to store the element in the destination
        // Reduce list.
        DestElementPtrAddr =
            Bld.CreateConstArrayGEP(DestBase, Idx, CGF.getPointerSize());
        DestElementAddr =
            CGF.CreateMemTemp(Private->getType(), ".omp.reduction.element");
        UpdateDestListPtr = true;
        break;
      }
      }
  
      // Regardless of src and dest of copy, we emit the load of src
      // element as this is required in all directions
      SrcElementAddr = Bld.CreateElementBitCast(
          SrcElementAddr, CGF.ConvertTypeForMem(Private->getType()));
      llvm::Value *Elem =
          CGF.EmitLoadOfScalar(SrcElementAddr, /*Volatile=*/false,
                               Private->getType(), Private->getExprLoc());
  
      // Now that all active lanes have read the element in the
      // Reduce list, shuffle over the value from the remote lane.
      if (ShuffleInElement) {
        Elem =
            createRuntimeShuffleFunction(CGF, Elem, Private->getType(),
                                         RemoteLaneOffset, Private->getExprLoc());
      }
  
      DestElementAddr = Bld.CreateElementBitCast(DestElementAddr,
                                                 SrcElementAddr.getElementType());
  
      // Store the source element value to the dest element address.
      CGF.EmitStoreOfScalar(Elem, DestElementAddr, /*Volatile=*/false,
                            Private->getType());
  
      // Step 3.1: Modify reference in dest Reduce list as needed.
      // Modifying the reference in Reduce list to point to the newly
      // created element.  The element is live in the current function
      // scope and that of functions it invokes (i.e., reduce_function).
      // RemoteReduceData[i] = (void*)&RemoteElem
      if (UpdateDestListPtr) {
        CGF.EmitStoreOfScalar(Bld.CreatePointerBitCastOrAddrSpaceCast(
                                  DestElementAddr.getPointer(), CGF.VoidPtrTy),
                              DestElementPtrAddr, /*Volatile=*/false,
                              C.VoidPtrTy);
      }
  
      // Step 4.1: Increment SrcBase/DestBase so that it points to the starting
      // address of the next element in scratchpad memory, unless we're currently
      // processing the last one.  Memory alignment is also taken care of here.
      if ((IncrScratchpadDest || IncrScratchpadSrc) && (Idx + 1 < Size)) {
        llvm::Value *ScratchpadBasePtr =
            IncrScratchpadDest ? DestBase.getPointer() : SrcBase.getPointer();
        llvm::Value *ElementSizeInChars = CGF.getTypeSize(Private->getType());
        ScratchpadBasePtr = Bld.CreateNUWAdd(
            ScratchpadBasePtr,
            Bld.CreateNUWMul(ScratchpadWidth, ElementSizeInChars));
  
        // Take care of global memory alignment for performance
        ScratchpadBasePtr = Bld.CreateNUWSub(
            ScratchpadBasePtr, llvm::ConstantInt::get(CGM.SizeTy, 1));
        ScratchpadBasePtr = Bld.CreateUDiv(
            ScratchpadBasePtr,
            llvm::ConstantInt::get(CGM.SizeTy, GlobalMemoryAlignment));
        ScratchpadBasePtr = Bld.CreateNUWAdd(
            ScratchpadBasePtr, llvm::ConstantInt::get(CGM.SizeTy, 1));
        ScratchpadBasePtr = Bld.CreateNUWMul(
            ScratchpadBasePtr,
            llvm::ConstantInt::get(CGM.SizeTy, GlobalMemoryAlignment));
  
        if (IncrScratchpadDest)
          DestBase = Address(ScratchpadBasePtr, CGF.getPointerAlign());
        else /* IncrScratchpadSrc = true */
          SrcBase = Address(ScratchpadBasePtr, CGF.getPointerAlign());
      }
  
      ++Idx;
    }
  }
  
  /// This function emits a helper that loads data from the scratchpad array
  /// and (optionally) reduces it with the input operand.
  ///
  ///  load_and_reduce(local, scratchpad, index, width, should_reduce)
  ///  reduce_data remote;
  ///  for elem in remote:
  ///    remote.elem = Scratchpad[elem_id][index]
  ///  if (should_reduce)
  ///    local = local @ remote
  ///  else
  ///    local = remote
  static llvm::Value *emitReduceScratchpadFunction(
      CodeGenModule &CGM, ArrayRef<const Expr *> Privates,
      QualType ReductionArrayTy, llvm::Value *ReduceFn, SourceLocation Loc) {
    ASTContext &C = CGM.getContext();
    QualType Int32Ty = C.getIntTypeForBitwidth(32, /*Signed=*/1);
  
    // Destination of the copy.
    ImplicitParamDecl ReduceListArg(C, /*DC=*/nullptr, Loc, /*Id=*/nullptr,
                                    C.VoidPtrTy, ImplicitParamDecl::Other);
    // Base address of the scratchpad array, with each element storing a
    // Reduce list per team.
    ImplicitParamDecl ScratchPadArg(C, /*DC=*/nullptr, Loc, /*Id=*/nullptr,
                                    C.VoidPtrTy, ImplicitParamDecl::Other);
    // A source index into the scratchpad array.
    ImplicitParamDecl IndexArg(C, /*DC=*/nullptr, Loc, /*Id=*/nullptr, Int32Ty,
                               ImplicitParamDecl::Other);
    // Row width of an element in the scratchpad array, typically
    // the number of teams.
    ImplicitParamDecl WidthArg(C, /*DC=*/nullptr, Loc, /*Id=*/nullptr, Int32Ty,
                               ImplicitParamDecl::Other);
    // If should_reduce == 1, then it's load AND reduce,
    // If should_reduce == 0 (or otherwise), then it only loads (+ copy).
    // The latter case is used for initialization.
    ImplicitParamDecl ShouldReduceArg(C, /*DC=*/nullptr, Loc, /*Id=*/nullptr,
                                      Int32Ty, ImplicitParamDecl::Other);
  
    FunctionArgList Args;
    Args.push_back(&ReduceListArg);
    Args.push_back(&ScratchPadArg);
    Args.push_back(&IndexArg);
    Args.push_back(&WidthArg);
    Args.push_back(&ShouldReduceArg);
  
    const CGFunctionInfo &CGFI =
        CGM.getTypes().arrangeBuiltinFunctionDeclaration(C.VoidTy, Args);
    auto *Fn = llvm::Function::Create(
        CGM.getTypes().GetFunctionType(CGFI), llvm::GlobalValue::InternalLinkage,
        "_omp_reduction_load_and_reduce", &CGM.getModule());
    CGM.SetInternalFunctionAttributes(GlobalDecl(), Fn, CGFI);
    Fn->setDoesNotRecurse();
    CodeGenFunction CGF(CGM);
    CGF.StartFunction(GlobalDecl(), C.VoidTy, Fn, CGFI, Args, Loc, Loc);
  
    CGBuilderTy &Bld = CGF.Builder;
  
    // Get local Reduce list pointer.
    Address AddrReduceListArg = CGF.GetAddrOfLocalVar(&ReduceListArg);
    Address ReduceListAddr(
        Bld.CreatePointerBitCastOrAddrSpaceCast(
            CGF.EmitLoadOfScalar(AddrReduceListArg, /*Volatile=*/false,
                                 C.VoidPtrTy, Loc),
            CGF.ConvertTypeForMem(ReductionArrayTy)->getPointerTo()),
        CGF.getPointerAlign());
  
    Address AddrScratchPadArg = CGF.GetAddrOfLocalVar(&ScratchPadArg);
    llvm::Value *ScratchPadBase = CGF.EmitLoadOfScalar(
        AddrScratchPadArg, /*Volatile=*/false, C.VoidPtrTy, Loc);
  
    Address AddrIndexArg = CGF.GetAddrOfLocalVar(&IndexArg);
    llvm::Value *IndexVal = Bld.CreateIntCast(
        CGF.EmitLoadOfScalar(AddrIndexArg, /*Volatile=*/false, Int32Ty, Loc),
        CGM.SizeTy, /*isSigned=*/true);
  
    Address AddrWidthArg = CGF.GetAddrOfLocalVar(&WidthArg);
    llvm::Value *WidthVal = Bld.CreateIntCast(
        CGF.EmitLoadOfScalar(AddrWidthArg, /*Volatile=*/false, Int32Ty, Loc),
        CGM.SizeTy, /*isSigned=*/true);
  
    Address AddrShouldReduceArg = CGF.GetAddrOfLocalVar(&ShouldReduceArg);
    llvm::Value *ShouldReduceVal = CGF.EmitLoadOfScalar(
        AddrShouldReduceArg, /*Volatile=*/false, Int32Ty, Loc);
  
    // The absolute ptr address to the base addr of the next element to copy.
    llvm::Value *CumulativeElemBasePtr =
        Bld.CreatePtrToInt(ScratchPadBase, CGM.SizeTy);
    Address SrcDataAddr(CumulativeElemBasePtr, CGF.getPointerAlign());
  
    // Create a Remote Reduce list to store the elements read from the
    // scratchpad array.
    Address RemoteReduceList =
        CGF.CreateMemTemp(ReductionArrayTy, ".omp.reduction.remote_red_list");
  
    // Assemble remote Reduce list from scratchpad array.
    emitReductionListCopy(ScratchpadToThread, CGF, ReductionArrayTy, Privates,
                          SrcDataAddr, RemoteReduceList,
                          {/*RemoteLaneOffset=*/nullptr,
                           /*ScratchpadIndex=*/IndexVal,
                           /*ScratchpadWidth=*/WidthVal});
  
    llvm::BasicBlock *ThenBB = CGF.createBasicBlock("then");
    llvm::BasicBlock *ElseBB = CGF.createBasicBlock("else");
    llvm::BasicBlock *MergeBB = CGF.createBasicBlock("ifcont");
  
    llvm::Value *CondReduce = Bld.CreateIsNotNull(ShouldReduceVal);
    Bld.CreateCondBr(CondReduce, ThenBB, ElseBB);
  
    CGF.EmitBlock(ThenBB);
    // We should reduce with the local Reduce list.
    // reduce_function(LocalReduceList, RemoteReduceList)
    llvm::Value *LocalDataPtr = Bld.CreatePointerBitCastOrAddrSpaceCast(
        ReduceListAddr.getPointer(), CGF.VoidPtrTy);
    llvm::Value *RemoteDataPtr = Bld.CreatePointerBitCastOrAddrSpaceCast(
        RemoteReduceList.getPointer(), CGF.VoidPtrTy);
    CGM.getOpenMPRuntime().emitOutlinedFunctionCall(
        CGF, Loc, ReduceFn, {LocalDataPtr, RemoteDataPtr});
    Bld.CreateBr(MergeBB);
  
    CGF.EmitBlock(ElseBB);
    // No reduction; just copy:
    // Local Reduce list = Remote Reduce list.
    emitReductionListCopy(ThreadCopy, CGF, ReductionArrayTy, Privates,
                          RemoteReduceList, ReduceListAddr);
    Bld.CreateBr(MergeBB);
  
    CGF.EmitBlock(MergeBB);
  
    CGF.FinishFunction();
    return Fn;
  }
  
  /// This function emits a helper that stores reduced data from the team
  /// master to a scratchpad array in global memory.
  ///
  ///  for elem in Reduce List:
  ///    scratchpad[elem_id][index] = elem
  ///
  static llvm::Value *emitCopyToScratchpad(CodeGenModule &CGM,
                                           ArrayRef<const Expr *> Privates,
                                           QualType ReductionArrayTy,
                                           SourceLocation Loc) {
  
    ASTContext &C = CGM.getContext();
    QualType Int32Ty = C.getIntTypeForBitwidth(32, /*Signed=*/1);
  
    // Source of the copy.
    ImplicitParamDecl ReduceListArg(C, /*DC=*/nullptr, Loc, /*Id=*/nullptr,
                                    C.VoidPtrTy, ImplicitParamDecl::Other);
    // Base address of the scratchpad array, with each element storing a
    // Reduce list per team.
    ImplicitParamDecl ScratchPadArg(C, /*DC=*/nullptr, Loc, /*Id=*/nullptr,
                                    C.VoidPtrTy, ImplicitParamDecl::Other);
    // A destination index into the scratchpad array, typically the team
    // identifier.
    ImplicitParamDecl IndexArg(C, /*DC=*/nullptr, Loc, /*Id=*/nullptr, Int32Ty,
                               ImplicitParamDecl::Other);
    // Row width of an element in the scratchpad array, typically
    // the number of teams.
    ImplicitParamDecl WidthArg(C, /*DC=*/nullptr, Loc, /*Id=*/nullptr, Int32Ty,
                               ImplicitParamDecl::Other);
  
    FunctionArgList Args;
    Args.push_back(&ReduceListArg);
    Args.push_back(&ScratchPadArg);
    Args.push_back(&IndexArg);
    Args.push_back(&WidthArg);
  
    const CGFunctionInfo &CGFI =
        CGM.getTypes().arrangeBuiltinFunctionDeclaration(C.VoidTy, Args);
    auto *Fn = llvm::Function::Create(
        CGM.getTypes().GetFunctionType(CGFI), llvm::GlobalValue::InternalLinkage,
        "_omp_reduction_copy_to_scratchpad", &CGM.getModule());
    CGM.SetInternalFunctionAttributes(GlobalDecl(), Fn, CGFI);
    Fn->setDoesNotRecurse();
    CodeGenFunction CGF(CGM);
    CGF.StartFunction(GlobalDecl(), C.VoidTy, Fn, CGFI, Args, Loc, Loc);
  
    CGBuilderTy &Bld = CGF.Builder;
  
    Address AddrReduceListArg = CGF.GetAddrOfLocalVar(&ReduceListArg);
    Address SrcDataAddr(
        Bld.CreatePointerBitCastOrAddrSpaceCast(
            CGF.EmitLoadOfScalar(AddrReduceListArg, /*Volatile=*/false,
                                 C.VoidPtrTy, Loc),
            CGF.ConvertTypeForMem(ReductionArrayTy)->getPointerTo()),
        CGF.getPointerAlign());
  
    Address AddrScratchPadArg = CGF.GetAddrOfLocalVar(&ScratchPadArg);
    llvm::Value *ScratchPadBase = CGF.EmitLoadOfScalar(
        AddrScratchPadArg, /*Volatile=*/false, C.VoidPtrTy, Loc);
  
    Address AddrIndexArg = CGF.GetAddrOfLocalVar(&IndexArg);
    llvm::Value *IndexVal = Bld.CreateIntCast(
        CGF.EmitLoadOfScalar(AddrIndexArg, /*Volatile=*/false, Int32Ty, Loc),
        CGF.SizeTy, /*isSigned=*/true);
  
    Address AddrWidthArg = CGF.GetAddrOfLocalVar(&WidthArg);
    llvm::Value *WidthVal =
        Bld.CreateIntCast(CGF.EmitLoadOfScalar(AddrWidthArg, /*Volatile=*/false,
                                               Int32Ty, SourceLocation()),
                          CGF.SizeTy, /*isSigned=*/true);
  
    // The absolute ptr address to the base addr of the next element to copy.
    llvm::Value *CumulativeElemBasePtr =
        Bld.CreatePtrToInt(ScratchPadBase, CGM.SizeTy);
    Address DestDataAddr(CumulativeElemBasePtr, CGF.getPointerAlign());
  
    emitReductionListCopy(ThreadToScratchpad, CGF, ReductionArrayTy, Privates,
                          SrcDataAddr, DestDataAddr,
                          {/*RemoteLaneOffset=*/nullptr,
                           /*ScratchpadIndex=*/IndexVal,
                           /*ScratchpadWidth=*/WidthVal});
  
    CGF.FinishFunction();
    return Fn;
  }
  
  /// This function emits a helper that gathers Reduce lists from the first
  /// lane of every active warp to lanes in the first warp.
  ///
  /// void inter_warp_copy_func(void* reduce_data, num_warps)
  ///   shared smem[warp_size];
  ///   For all data entries D in reduce_data:
  ///     If (I am the first lane in each warp)
  ///       Copy my local D to smem[warp_id]
  ///     sync
  ///     if (I am the first warp)
  ///       Copy smem[thread_id] to my local D
  ///     sync
  static llvm::Value *emitInterWarpCopyFunction(CodeGenModule &CGM,
                                                ArrayRef<const Expr *> Privates,
                                                QualType ReductionArrayTy,
                                                SourceLocation Loc) {
    ASTContext &C = CGM.getContext();
    llvm::Module &M = CGM.getModule();
  
    // ReduceList: thread local Reduce list.
    // At the stage of the computation when this function is called, partially
    // aggregated values reside in the first lane of every active warp.
    ImplicitParamDecl ReduceListArg(C, /*DC=*/nullptr, Loc, /*Id=*/nullptr,
                                    C.VoidPtrTy, ImplicitParamDecl::Other);
    // NumWarps: number of warps active in the parallel region.  This could
    // be smaller than 32 (max warps in a CTA) for partial block reduction.
    ImplicitParamDecl NumWarpsArg(C, /*DC=*/nullptr, Loc, /*Id=*/nullptr,
                                  C.getIntTypeForBitwidth(32, /* Signed */ true),
                                  ImplicitParamDecl::Other);
    FunctionArgList Args;
    Args.push_back(&ReduceListArg);
    Args.push_back(&NumWarpsArg);
  
    const CGFunctionInfo &CGFI =
        CGM.getTypes().arrangeBuiltinFunctionDeclaration(C.VoidTy, Args);
    auto *Fn = llvm::Function::Create(
        CGM.getTypes().GetFunctionType(CGFI), llvm::GlobalValue::InternalLinkage,
        "_omp_reduction_inter_warp_copy_func", &CGM.getModule());
    CGM.SetInternalFunctionAttributes(GlobalDecl(), Fn, CGFI);
    Fn->setDoesNotRecurse();
    CodeGenFunction CGF(CGM);
    CGF.StartFunction(GlobalDecl(), C.VoidTy, Fn, CGFI, Args, Loc, Loc);
  
    CGBuilderTy &Bld = CGF.Builder;
  
    // This array is used as a medium to transfer, one reduce element at a time,
    // the data from the first lane of every warp to lanes in the first warp
    // in order to perform the final step of a reduction in a parallel region
    // (reduction across warps).  The array is placed in NVPTX __shared__ memory
    // for reduced latency, as well as to have a distinct copy for concurrently
    // executing target regions.  The array is declared with common linkage so
    // as to be shared across compilation units.
    StringRef TransferMediumName =
        "__openmp_nvptx_data_transfer_temporary_storage";
    llvm::GlobalVariable *TransferMedium =
        M.getGlobalVariable(TransferMediumName);
    if (!TransferMedium) {
      auto *Ty = llvm::ArrayType::get(CGM.Int64Ty, WarpSize);
      unsigned SharedAddressSpace = C.getTargetAddressSpace(LangAS::cuda_shared);
      TransferMedium = new llvm::GlobalVariable(
          M, Ty,
          /*isConstant=*/false, llvm::GlobalVariable::CommonLinkage,
          llvm::Constant::getNullValue(Ty), TransferMediumName,
          /*InsertBefore=*/nullptr, llvm::GlobalVariable::NotThreadLocal,
          SharedAddressSpace);
      CGM.addCompilerUsedGlobal(TransferMedium);
    }
  
    // Get the CUDA thread id of the current OpenMP thread on the GPU.
    llvm::Value *ThreadID = getNVPTXThreadID(CGF);
    // nvptx_lane_id = nvptx_id % warpsize
    llvm::Value *LaneID = getNVPTXLaneID(CGF);
    // nvptx_warp_id = nvptx_id / warpsize
    llvm::Value *WarpID = getNVPTXWarpID(CGF);
  
    Address AddrReduceListArg = CGF.GetAddrOfLocalVar(&ReduceListArg);
    Address LocalReduceList(
        Bld.CreatePointerBitCastOrAddrSpaceCast(
            CGF.EmitLoadOfScalar(AddrReduceListArg, /*Volatile=*/false,
                                 C.VoidPtrTy, SourceLocation()),
            CGF.ConvertTypeForMem(ReductionArrayTy)->getPointerTo()),
        CGF.getPointerAlign());
  
    unsigned Idx = 0;
    for (const Expr *Private : Privates) {
      //
      // Warp master copies reduce element to transfer medium in __shared__
      // memory.
      //
      llvm::BasicBlock *ThenBB = CGF.createBasicBlock("then");
      llvm::BasicBlock *ElseBB = CGF.createBasicBlock("else");
      llvm::BasicBlock *MergeBB = CGF.createBasicBlock("ifcont");
  
      // if (lane_id == 0)
      llvm::Value *IsWarpMaster = Bld.CreateIsNull(LaneID, "warp_master");
      Bld.CreateCondBr(IsWarpMaster, ThenBB, ElseBB);
      CGF.EmitBlock(ThenBB);
  
      // Reduce element = LocalReduceList[i]
      Address ElemPtrPtrAddr =
          Bld.CreateConstArrayGEP(LocalReduceList, Idx, CGF.getPointerSize());
      llvm::Value *ElemPtrPtr = CGF.EmitLoadOfScalar(
          ElemPtrPtrAddr, /*Volatile=*/false, C.VoidPtrTy, SourceLocation());
      // elemptr = (type[i]*)(elemptrptr)
      Address ElemPtr =
          Address(ElemPtrPtr, C.getTypeAlignInChars(Private->getType()));
      ElemPtr = Bld.CreateElementBitCast(
          ElemPtr, CGF.ConvertTypeForMem(Private->getType()));
      // elem = *elemptr
      llvm::Value *Elem = CGF.EmitLoadOfScalar(
          ElemPtr, /*Volatile=*/false, Private->getType(), SourceLocation());
  
      // Get pointer to location in transfer medium.
      // MediumPtr = &medium[warp_id]
      llvm::Value *MediumPtrVal = Bld.CreateInBoundsGEP(
          TransferMedium, {llvm::Constant::getNullValue(CGM.Int64Ty), WarpID});
      Address MediumPtr(MediumPtrVal, C.getTypeAlignInChars(Private->getType()));
      // Casting to actual data type.
      // MediumPtr = (type[i]*)MediumPtrAddr;
      MediumPtr = Bld.CreateElementBitCast(
          MediumPtr, CGF.ConvertTypeForMem(Private->getType()));
  
      //*MediumPtr = elem
      Bld.CreateStore(Elem, MediumPtr);
  
      Bld.CreateBr(MergeBB);
  
      CGF.EmitBlock(ElseBB);
      Bld.CreateBr(MergeBB);
  
      CGF.EmitBlock(MergeBB);
  
      Address AddrNumWarpsArg = CGF.GetAddrOfLocalVar(&NumWarpsArg);
      llvm::Value *NumWarpsVal = CGF.EmitLoadOfScalar(
          AddrNumWarpsArg, /*Volatile=*/false, C.IntTy, SourceLocation());
  
      llvm::Value *NumActiveThreads = Bld.CreateNSWMul(
          NumWarpsVal, getNVPTXWarpSize(CGF), "num_active_threads");
      // named_barrier_sync(ParallelBarrierID, num_active_threads)
      syncParallelThreads(CGF, NumActiveThreads);
  
      //
      // Warp 0 copies reduce element from transfer medium.
      //
      llvm::BasicBlock *W0ThenBB = CGF.createBasicBlock("then");
      llvm::BasicBlock *W0ElseBB = CGF.createBasicBlock("else");
      llvm::BasicBlock *W0MergeBB = CGF.createBasicBlock("ifcont");
  
      // Up to 32 threads in warp 0 are active.
      llvm::Value *IsActiveThread =
          Bld.CreateICmpULT(ThreadID, NumWarpsVal, "is_active_thread");
      Bld.CreateCondBr(IsActiveThread, W0ThenBB, W0ElseBB);
  
      CGF.EmitBlock(W0ThenBB);
  
      // SrcMediumPtr = &medium[tid]
      llvm::Value *SrcMediumPtrVal = Bld.CreateInBoundsGEP(
          TransferMedium, {llvm::Constant::getNullValue(CGM.Int64Ty), ThreadID});
      Address SrcMediumPtr(SrcMediumPtrVal,
                           C.getTypeAlignInChars(Private->getType()));
      // SrcMediumVal = *SrcMediumPtr;
      SrcMediumPtr = Bld.CreateElementBitCast(
          SrcMediumPtr, CGF.ConvertTypeForMem(Private->getType()));
      llvm::Value *SrcMediumValue = CGF.EmitLoadOfScalar(
          SrcMediumPtr, /*Volatile=*/false, Private->getType(), SourceLocation());
  
      // TargetElemPtr = (type[i]*)(SrcDataAddr[i])
      Address TargetElemPtrPtr =
          Bld.CreateConstArrayGEP(LocalReduceList, Idx, CGF.getPointerSize());
      llvm::Value *TargetElemPtrVal = CGF.EmitLoadOfScalar(
          TargetElemPtrPtr, /*Volatile=*/false, C.VoidPtrTy, SourceLocation());
      Address TargetElemPtr =
          Address(TargetElemPtrVal, C.getTypeAlignInChars(Private->getType()));
      TargetElemPtr = Bld.CreateElementBitCast(
          TargetElemPtr, CGF.ConvertTypeForMem(Private->getType()));
  
      // *TargetElemPtr = SrcMediumVal;
      CGF.EmitStoreOfScalar(SrcMediumValue, TargetElemPtr, /*Volatile=*/false,
                            Private->getType());
      Bld.CreateBr(W0MergeBB);
  
      CGF.EmitBlock(W0ElseBB);
      Bld.CreateBr(W0MergeBB);
  
      CGF.EmitBlock(W0MergeBB);
  
      // While warp 0 copies values from transfer medium, all other warps must
      // wait.
      syncParallelThreads(CGF, NumActiveThreads);
      ++Idx;
    }
  
    CGF.FinishFunction();
    return Fn;
  }
  
  /// Emit a helper that reduces data across two OpenMP threads (lanes)
  /// in the same warp.  It uses shuffle instructions to copy over data from
  /// a remote lane's stack.  The reduction algorithm performed is specified
  /// by the fourth parameter.
  ///
  /// Algorithm Versions.
  /// Full Warp Reduce (argument value 0):
  ///   This algorithm assumes that all 32 lanes are active and gathers
  ///   data from these 32 lanes, producing a single resultant value.
  /// Contiguous Partial Warp Reduce (argument value 1):
  ///   This algorithm assumes that only a *contiguous* subset of lanes
  ///   are active.  This happens for the last warp in a parallel region
  ///   when the user specified num_threads is not an integer multiple of
  ///   32.  This contiguous subset always starts with the zeroth lane.
  /// Partial Warp Reduce (argument value 2):
  ///   This algorithm gathers data from any number of lanes at any position.
  /// All reduced values are stored in the lowest possible lane.  The set
  /// of problems every algorithm addresses is a super set of those
  /// addressable by algorithms with a lower version number.  Overhead
  /// increases as algorithm version increases.
  ///
  /// Terminology
  /// Reduce element:
  ///   Reduce element refers to the individual data field with primitive
  ///   data types to be combined and reduced across threads.
  /// Reduce list:
  ///   Reduce list refers to a collection of local, thread-private
  ///   reduce elements.
  /// Remote Reduce list:
  ///   Remote Reduce list refers to a collection of remote (relative to
  ///   the current thread) reduce elements.
  ///
  /// We distinguish between three states of threads that are important to
  /// the implementation of this function.
  /// Alive threads:
  ///   Threads in a warp executing the SIMT instruction, as distinguished from
  ///   threads that are inactive due to divergent control flow.
  /// Active threads:
  ///   The minimal set of threads that has to be alive upon entry to this
  ///   function.  The computation is correct iff active threads are alive.
  ///   Some threads are alive but they are not active because they do not
  ///   contribute to the computation in any useful manner.  Turning them off
  ///   may introduce control flow overheads without any tangible benefits.
  /// Effective threads:
  ///   In order to comply with the argument requirements of the shuffle
  ///   function, we must keep all lanes holding data alive.  But at most
  ///   half of them perform value aggregation; we refer to this half of
  ///   threads as effective. The other half is simply handing off their
  ///   data.
  ///
  /// Procedure
  /// Value shuffle:
  ///   In this step active threads transfer data from higher lane positions
  ///   in the warp to lower lane positions, creating Remote Reduce list.
  /// Value aggregation:
  ///   In this step, effective threads combine their thread local Reduce list
  ///   with Remote Reduce list and store the result in the thread local
  ///   Reduce list.
  /// Value copy:
  ///   In this step, we deal with the assumption made by algorithm 2
  ///   (i.e. contiguity assumption).  When we have an odd number of lanes
  ///   active, say 2k+1, only k threads will be effective and therefore k
  ///   new values will be produced.  However, the Reduce list owned by the
  ///   (2k+1)th thread is ignored in the value aggregation.  Therefore
  ///   we copy the Reduce list from the (2k+1)th lane to (k+1)th lane so
  ///   that the contiguity assumption still holds.
  static llvm::Value *emitShuffleAndReduceFunction(
      CodeGenModule &CGM, ArrayRef<const Expr *> Privates,
      QualType ReductionArrayTy, llvm::Value *ReduceFn, SourceLocation Loc) {
    ASTContext &C = CGM.getContext();
  
    // Thread local Reduce list used to host the values of data to be reduced.
    ImplicitParamDecl ReduceListArg(C, /*DC=*/nullptr, Loc, /*Id=*/nullptr,
                                    C.VoidPtrTy, ImplicitParamDecl::Other);
    // Current lane id; could be logical.
    ImplicitParamDecl LaneIDArg(C, /*DC=*/nullptr, Loc, /*Id=*/nullptr, C.ShortTy,
                                ImplicitParamDecl::Other);
    // Offset of the remote source lane relative to the current lane.
    ImplicitParamDecl RemoteLaneOffsetArg(C, /*DC=*/nullptr, Loc, /*Id=*/nullptr,
                                          C.ShortTy, ImplicitParamDecl::Other);
    // Algorithm version.  This is expected to be known at compile time.
    ImplicitParamDecl AlgoVerArg(C, /*DC=*/nullptr, Loc, /*Id=*/nullptr,
                                 C.ShortTy, ImplicitParamDecl::Other);
    FunctionArgList Args;
    Args.push_back(&ReduceListArg);
    Args.push_back(&LaneIDArg);
    Args.push_back(&RemoteLaneOffsetArg);
    Args.push_back(&AlgoVerArg);
  
    const CGFunctionInfo &CGFI =
        CGM.getTypes().arrangeBuiltinFunctionDeclaration(C.VoidTy, Args);
    auto *Fn = llvm::Function::Create(
        CGM.getTypes().GetFunctionType(CGFI), llvm::GlobalValue::InternalLinkage,
        "_omp_reduction_shuffle_and_reduce_func", &CGM.getModule());
    CGM.SetInternalFunctionAttributes(GlobalDecl(), Fn, CGFI);
    Fn->setDoesNotRecurse();
    CodeGenFunction CGF(CGM);
    CGF.StartFunction(GlobalDecl(), C.VoidTy, Fn, CGFI, Args, Loc, Loc);
  
    CGBuilderTy &Bld = CGF.Builder;
  
    Address AddrReduceListArg = CGF.GetAddrOfLocalVar(&ReduceListArg);
    Address LocalReduceList(
        Bld.CreatePointerBitCastOrAddrSpaceCast(
            CGF.EmitLoadOfScalar(AddrReduceListArg, /*Volatile=*/false,
                                 C.VoidPtrTy, SourceLocation()),
            CGF.ConvertTypeForMem(ReductionArrayTy)->getPointerTo()),
        CGF.getPointerAlign());
  
    Address AddrLaneIDArg = CGF.GetAddrOfLocalVar(&LaneIDArg);
    llvm::Value *LaneIDArgVal = CGF.EmitLoadOfScalar(
        AddrLaneIDArg, /*Volatile=*/false, C.ShortTy, SourceLocation());
  
    Address AddrRemoteLaneOffsetArg = CGF.GetAddrOfLocalVar(&RemoteLaneOffsetArg);
    llvm::Value *RemoteLaneOffsetArgVal = CGF.EmitLoadOfScalar(
        AddrRemoteLaneOffsetArg, /*Volatile=*/false, C.ShortTy, SourceLocation());
  
    Address AddrAlgoVerArg = CGF.GetAddrOfLocalVar(&AlgoVerArg);
    llvm::Value *AlgoVerArgVal = CGF.EmitLoadOfScalar(
        AddrAlgoVerArg, /*Volatile=*/false, C.ShortTy, SourceLocation());
  
    // Create a local thread-private variable to host the Reduce list
    // from a remote lane.
    Address RemoteReduceList =
        CGF.CreateMemTemp(ReductionArrayTy, ".omp.reduction.remote_reduce_list");
  
    // This loop iterates through the list of reduce elements and copies,
    // element by element, from a remote lane in the warp to RemoteReduceList,
    // hosted on the thread's stack.
    emitReductionListCopy(RemoteLaneToThread, CGF, ReductionArrayTy, Privates,
                          LocalReduceList, RemoteReduceList,
                          {/*RemoteLaneOffset=*/RemoteLaneOffsetArgVal,
                           /*ScratchpadIndex=*/nullptr,
                           /*ScratchpadWidth=*/nullptr});
  
    // The actions to be performed on the Remote Reduce list is dependent
    // on the algorithm version.
    //
    //  if (AlgoVer==0) || (AlgoVer==1 && (LaneId < Offset)) || (AlgoVer==2 &&
    //  LaneId % 2 == 0 && Offset > 0):
    //    do the reduction value aggregation
    //
    //  The thread local variable Reduce list is mutated in place to host the
    //  reduced data, which is the aggregated value produced from local and
    //  remote lanes.
    //
    //  Note that AlgoVer is expected to be a constant integer known at compile
    //  time.
    //  When AlgoVer==0, the first conjunction evaluates to true, making
    //    the entire predicate true during compile time.
    //  When AlgoVer==1, the second conjunction has only the second part to be
    //    evaluated during runtime.  Other conjunctions evaluates to false
    //    during compile time.
    //  When AlgoVer==2, the third conjunction has only the second part to be
    //    evaluated during runtime.  Other conjunctions evaluates to false
    //    during compile time.
    llvm::Value *CondAlgo0 = Bld.CreateIsNull(AlgoVerArgVal);
  
    llvm::Value *Algo1 = Bld.CreateICmpEQ(AlgoVerArgVal, Bld.getInt16(1));
    llvm::Value *CondAlgo1 = Bld.CreateAnd(
        Algo1, Bld.CreateICmpULT(LaneIDArgVal, RemoteLaneOffsetArgVal));
  
    llvm::Value *Algo2 = Bld.CreateICmpEQ(AlgoVerArgVal, Bld.getInt16(2));
    llvm::Value *CondAlgo2 = Bld.CreateAnd(
        Algo2, Bld.CreateIsNull(Bld.CreateAnd(LaneIDArgVal, Bld.getInt16(1))));
    CondAlgo2 = Bld.CreateAnd(
        CondAlgo2, Bld.CreateICmpSGT(RemoteLaneOffsetArgVal, Bld.getInt16(0)));
  
    llvm::Value *CondReduce = Bld.CreateOr(CondAlgo0, CondAlgo1);
    CondReduce = Bld.CreateOr(CondReduce, CondAlgo2);
  
    llvm::BasicBlock *ThenBB = CGF.createBasicBlock("then");
    llvm::BasicBlock *ElseBB = CGF.createBasicBlock("else");
    llvm::BasicBlock *MergeBB = CGF.createBasicBlock("ifcont");
    Bld.CreateCondBr(CondReduce, ThenBB, ElseBB);
  
    CGF.EmitBlock(ThenBB);
    // reduce_function(LocalReduceList, RemoteReduceList)
    llvm::Value *LocalReduceListPtr = Bld.CreatePointerBitCastOrAddrSpaceCast(
        LocalReduceList.getPointer(), CGF.VoidPtrTy);
    llvm::Value *RemoteReduceListPtr = Bld.CreatePointerBitCastOrAddrSpaceCast(
        RemoteReduceList.getPointer(), CGF.VoidPtrTy);
    CGM.getOpenMPRuntime().emitOutlinedFunctionCall(
        CGF, Loc, ReduceFn, {LocalReduceListPtr, RemoteReduceListPtr});
    Bld.CreateBr(MergeBB);
  
    CGF.EmitBlock(ElseBB);
    Bld.CreateBr(MergeBB);
  
    CGF.EmitBlock(MergeBB);
  
    // if (AlgoVer==1 && (LaneId >= Offset)) copy Remote Reduce list to local
    // Reduce list.
    Algo1 = Bld.CreateICmpEQ(AlgoVerArgVal, Bld.getInt16(1));
    llvm::Value *CondCopy = Bld.CreateAnd(
        Algo1, Bld.CreateICmpUGE(LaneIDArgVal, RemoteLaneOffsetArgVal));
  
    llvm::BasicBlock *CpyThenBB = CGF.createBasicBlock("then");
    llvm::BasicBlock *CpyElseBB = CGF.createBasicBlock("else");
    llvm::BasicBlock *CpyMergeBB = CGF.createBasicBlock("ifcont");
    Bld.CreateCondBr(CondCopy, CpyThenBB, CpyElseBB);
  
    CGF.EmitBlock(CpyThenBB);
    emitReductionListCopy(ThreadCopy, CGF, ReductionArrayTy, Privates,
                          RemoteReduceList, LocalReduceList);
    Bld.CreateBr(CpyMergeBB);
  
    CGF.EmitBlock(CpyElseBB);
    Bld.CreateBr(CpyMergeBB);
  
    CGF.EmitBlock(CpyMergeBB);
  
    CGF.FinishFunction();
    return Fn;
  }
  
  ///
  /// Design of OpenMP reductions on the GPU
  ///
  /// Consider a typical OpenMP program with one or more reduction
  /// clauses:
  ///
  /// float foo;
  /// double bar;
  /// #pragma omp target teams distribute parallel for \
  ///             reduction(+:foo) reduction(*:bar)
  /// for (int i = 0; i < N; i++) {
  ///   foo += A[i]; bar *= B[i];
  /// }
  ///
  /// where 'foo' and 'bar' are reduced across all OpenMP threads in
  /// all teams.  In our OpenMP implementation on the NVPTX device an
  /// OpenMP team is mapped to a CUDA threadblock and OpenMP threads
  /// within a team are mapped to CUDA threads within a threadblock.
  /// Our goal is to efficiently aggregate values across all OpenMP
  /// threads such that:
  ///
  ///   - the compiler and runtime are logically concise, and
  ///   - the reduction is performed efficiently in a hierarchical
  ///     manner as follows: within OpenMP threads in the same warp,
  ///     across warps in a threadblock, and finally across teams on
  ///     the NVPTX device.
  ///
  /// Introduction to Decoupling
  ///
  /// We would like to decouple the compiler and the runtime so that the
  /// latter is ignorant of the reduction variables (number, data types)
  /// and the reduction operators.  This allows a simpler interface
  /// and implementation while still attaining good performance.
  ///
  /// Pseudocode for the aforementioned OpenMP program generated by the
  /// compiler is as follows:
  ///
  /// 1. Create private copies of reduction variables on each OpenMP
  ///    thread: 'foo_private', 'bar_private'
  /// 2. Each OpenMP thread reduces the chunk of 'A' and 'B' assigned
  ///    to it and writes the result in 'foo_private' and 'bar_private'
  ///    respectively.
  /// 3. Call the OpenMP runtime on the GPU to reduce within a team
  ///    and store the result on the team master:
  ///
  ///     __kmpc_nvptx_parallel_reduce_nowait(...,
  ///        reduceData, shuffleReduceFn, interWarpCpyFn)
  ///
  ///     where:
  ///       struct ReduceData {
  ///         double *foo;
  ///         double *bar;
  ///       } reduceData
  ///       reduceData.foo = &foo_private
  ///       reduceData.bar = &bar_private
  ///
  ///     'shuffleReduceFn' and 'interWarpCpyFn' are pointers to two
  ///     auxiliary functions generated by the compiler that operate on
  ///     variables of type 'ReduceData'.  They aid the runtime perform
  ///     algorithmic steps in a data agnostic manner.
  ///
  ///     'shuffleReduceFn' is a pointer to a function that reduces data
  ///     of type 'ReduceData' across two OpenMP threads (lanes) in the
  ///     same warp.  It takes the following arguments as input:
  ///
  ///     a. variable of type 'ReduceData' on the calling lane,
  ///     b. its lane_id,
  ///     c. an offset relative to the current lane_id to generate a
  ///        remote_lane_id.  The remote lane contains the second
  ///        variable of type 'ReduceData' that is to be reduced.
  ///     d. an algorithm version parameter determining which reduction
  ///        algorithm to use.
  ///
  ///     'shuffleReduceFn' retrieves data from the remote lane using
  ///     efficient GPU shuffle intrinsics and reduces, using the
  ///     algorithm specified by the 4th parameter, the two operands
  ///     element-wise.  The result is written to the first operand.
  ///
  ///     Different reduction algorithms are implemented in different
  ///     runtime functions, all calling 'shuffleReduceFn' to perform
  ///     the essential reduction step.  Therefore, based on the 4th
  ///     parameter, this function behaves slightly differently to
  ///     cooperate with the runtime to ensure correctness under
  ///     different circumstances.
  ///
  ///     'InterWarpCpyFn' is a pointer to a function that transfers
  ///     reduced variables across warps.  It tunnels, through CUDA
  ///     shared memory, the thread-private data of type 'ReduceData'
  ///     from lane 0 of each warp to a lane in the first warp.
  /// 4. Call the OpenMP runtime on the GPU to reduce across teams.
  ///    The last team writes the global reduced value to memory.
  ///
  ///     ret = __kmpc_nvptx_teams_reduce_nowait(...,
  ///             reduceData, shuffleReduceFn, interWarpCpyFn,
  ///             scratchpadCopyFn, loadAndReduceFn)
  ///
  ///     'scratchpadCopyFn' is a helper that stores reduced
  ///     data from the team master to a scratchpad array in
  ///     global memory.
  ///
  ///     'loadAndReduceFn' is a helper that loads data from
  ///     the scratchpad array and reduces it with the input
  ///     operand.
  ///
  ///     These compiler generated functions hide address
  ///     calculation and alignment information from the runtime.
  /// 5. if ret == 1:
  ///     The team master of the last team stores the reduced
  ///     result to the globals in memory.
  ///     foo += reduceData.foo; bar *= reduceData.bar
  ///
  ///
  /// Warp Reduction Algorithms
  ///
  /// On the warp level, we have three algorithms implemented in the
  /// OpenMP runtime depending on the number of active lanes:
  ///
  /// Full Warp Reduction
  ///
  /// The reduce algorithm within a warp where all lanes are active
  /// is implemented in the runtime as follows:
  ///
  /// full_warp_reduce(void *reduce_data,
  ///                  kmp_ShuffleReductFctPtr ShuffleReduceFn) {
  ///   for (int offset = WARPSIZE/2; offset > 0; offset /= 2)
  ///     ShuffleReduceFn(reduce_data, 0, offset, 0);
  /// }
  ///
  /// The algorithm completes in log(2, WARPSIZE) steps.
  ///
  /// 'ShuffleReduceFn' is used here with lane_id set to 0 because it is
  /// not used therefore we save instructions by not retrieving lane_id
  /// from the corresponding special registers.  The 4th parameter, which
  /// represents the version of the algorithm being used, is set to 0 to
  /// signify full warp reduction.
  ///
  /// In this version, 'ShuffleReduceFn' behaves, per element, as follows:
  ///
  /// #reduce_elem refers to an element in the local lane's data structure
  /// #remote_elem is retrieved from a remote lane
  /// remote_elem = shuffle_down(reduce_elem, offset, WARPSIZE);
  /// reduce_elem = reduce_elem REDUCE_OP remote_elem;
  ///
  /// Contiguous Partial Warp Reduction
  ///
  /// This reduce algorithm is used within a warp where only the first
  /// 'n' (n <= WARPSIZE) lanes are active.  It is typically used when the
  /// number of OpenMP threads in a parallel region is not a multiple of
  /// WARPSIZE.  The algorithm is implemented in the runtime as follows:
  ///
  /// void
  /// contiguous_partial_reduce(void *reduce_data,
  ///                           kmp_ShuffleReductFctPtr ShuffleReduceFn,
  ///                           int size, int lane_id) {
  ///   int curr_size;
  ///   int offset;
  ///   curr_size = size;
  ///   mask = curr_size/2;
  ///   while (offset>0) {
  ///     ShuffleReduceFn(reduce_data, lane_id, offset, 1);
  ///     curr_size = (curr_size+1)/2;
  ///     offset = curr_size/2;
  ///   }
  /// }
  ///
  /// In this version, 'ShuffleReduceFn' behaves, per element, as follows:
  ///
  /// remote_elem = shuffle_down(reduce_elem, offset, WARPSIZE);
  /// if (lane_id < offset)
  ///     reduce_elem = reduce_elem REDUCE_OP remote_elem
  /// else
  ///     reduce_elem = remote_elem
  ///
  /// This algorithm assumes that the data to be reduced are located in a
  /// contiguous subset of lanes starting from the first.  When there is
  /// an odd number of active lanes, the data in the last lane is not
  /// aggregated with any other lane's dat but is instead copied over.
  ///
  /// Dispersed Partial Warp Reduction
  ///
  /// This algorithm is used within a warp when any discontiguous subset of
  /// lanes are active.  It is used to implement the reduction operation
  /// across lanes in an OpenMP simd region or in a nested parallel region.
  ///
  /// void
  /// dispersed_partial_reduce(void *reduce_data,
  ///                          kmp_ShuffleReductFctPtr ShuffleReduceFn) {
  ///   int size, remote_id;
  ///   int logical_lane_id = number_of_active_lanes_before_me() * 2;
  ///   do {
  ///       remote_id = next_active_lane_id_right_after_me();
  ///       # the above function returns 0 of no active lane
  ///       # is present right after the current lane.
  ///       size = number_of_active_lanes_in_this_warp();
  ///       logical_lane_id /= 2;
  ///       ShuffleReduceFn(reduce_data, logical_lane_id,
  ///                       remote_id-1-threadIdx.x, 2);
  ///   } while (logical_lane_id % 2 == 0 && size > 1);
  /// }
  ///
  /// There is no assumption made about the initial state of the reduction.
  /// Any number of lanes (>=1) could be active at any position.  The reduction
  /// result is returned in the first active lane.
  ///
  /// In this version, 'ShuffleReduceFn' behaves, per element, as follows:
  ///
  /// remote_elem = shuffle_down(reduce_elem, offset, WARPSIZE);
  /// if (lane_id % 2 == 0 && offset > 0)
  ///     reduce_elem = reduce_elem REDUCE_OP remote_elem
  /// else
  ///     reduce_elem = remote_elem
  ///
  ///
  /// Intra-Team Reduction
  ///
  /// This function, as implemented in the runtime call
  /// '__kmpc_nvptx_parallel_reduce_nowait', aggregates data across OpenMP
  /// threads in a team.  It first reduces within a warp using the
  /// aforementioned algorithms.  We then proceed to gather all such
  /// reduced values at the first warp.
  ///
  /// The runtime makes use of the function 'InterWarpCpyFn', which copies
  /// data from each of the "warp master" (zeroth lane of each warp, where
  /// warp-reduced data is held) to the zeroth warp.  This step reduces (in
  /// a mathematical sense) the problem of reduction across warp masters in
  /// a block to the problem of warp reduction.
  ///
  ///
  /// Inter-Team Reduction
  ///
  /// Once a team has reduced its data to a single value, it is stored in
  /// a global scratchpad array.  Since each team has a distinct slot, this
  /// can be done without locking.
  ///
  /// The last team to write to the scratchpad array proceeds to reduce the
  /// scratchpad array.  One or more workers in the last team use the helper
  /// 'loadAndReduceDataFn' to load and reduce values from the array, i.e.,
  /// the k'th worker reduces every k'th element.
  ///
  /// Finally, a call is made to '__kmpc_nvptx_parallel_reduce_nowait' to
  /// reduce across workers and compute a globally reduced value.
  ///
  void CGOpenMPRuntimeNVPTX::emitReduction(
      CodeGenFunction &CGF, SourceLocation Loc, ArrayRef<const Expr *> Privates,
      ArrayRef<const Expr *> LHSExprs, ArrayRef<const Expr *> RHSExprs,
      ArrayRef<const Expr *> ReductionOps, ReductionOptionsTy Options) {
    if (!CGF.HaveInsertPoint())
      return;
  
    bool ParallelReduction = isOpenMPParallelDirective(Options.ReductionKind);
    bool TeamsReduction = isOpenMPTeamsDirective(Options.ReductionKind);
    bool SimdReduction = isOpenMPSimdDirective(Options.ReductionKind);
    assert((TeamsReduction || ParallelReduction || SimdReduction) &&
           "Invalid reduction selection in emitReduction.");
  
    ASTContext &C = CGM.getContext();
  
    // 1. Build a list of reduction variables.
    // void *RedList[<n>] = {<ReductionVars>[0], ..., <ReductionVars>[<n>-1]};
    auto Size = RHSExprs.size();
    for (const Expr *E : Privates) {
      if (E->getType()->isVariablyModifiedType())
        // Reserve place for array size.
        ++Size;
    }
    llvm::APInt ArraySize(/*unsigned int numBits=*/32, Size);
    QualType ReductionArrayTy =
        C.getConstantArrayType(C.VoidPtrTy, ArraySize, ArrayType::Normal,
                               /*IndexTypeQuals=*/0);
    Address ReductionList =
        CGF.CreateMemTemp(ReductionArrayTy, ".omp.reduction.red_list");
    auto IPriv = Privates.begin();
    unsigned Idx = 0;
    for (unsigned I = 0, E = RHSExprs.size(); I < E; ++I, ++IPriv, ++Idx) {
      Address Elem = CGF.Builder.CreateConstArrayGEP(ReductionList, Idx,
                                                     CGF.getPointerSize());
      CGF.Builder.CreateStore(
          CGF.Builder.CreatePointerBitCastOrAddrSpaceCast(
              CGF.EmitLValue(RHSExprs[I]).getPointer(), CGF.VoidPtrTy),
          Elem);
      if ((*IPriv)->getType()->isVariablyModifiedType()) {
        // Store array size.
        ++Idx;
        Elem = CGF.Builder.CreateConstArrayGEP(ReductionList, Idx,
                                               CGF.getPointerSize());
        llvm::Value *Size = CGF.Builder.CreateIntCast(
            CGF.getVLASize(
                   CGF.getContext().getAsVariableArrayType((*IPriv)->getType()))
                .NumElts,
            CGF.SizeTy, /*isSigned=*/false);
        CGF.Builder.CreateStore(CGF.Builder.CreateIntToPtr(Size, CGF.VoidPtrTy),
                                Elem);
      }
    }
  
    // 2. Emit reduce_func().
    llvm::Value *ReductionFn = emitReductionFunction(
        CGM, Loc, CGF.ConvertTypeForMem(ReductionArrayTy)->getPointerTo(),
        Privates, LHSExprs, RHSExprs, ReductionOps);
  
    // 4. Build res = __kmpc_reduce{_nowait}(<gtid>, <n>, sizeof(RedList),
    // RedList, shuffle_reduce_func, interwarp_copy_func);
    llvm::Value *ThreadId = getThreadID(CGF, Loc);
    llvm::Value *ReductionArrayTySize = CGF.getTypeSize(ReductionArrayTy);
    llvm::Value *RL = CGF.Builder.CreatePointerBitCastOrAddrSpaceCast(
        ReductionList.getPointer(), CGF.VoidPtrTy);
  
    llvm::Value *ShuffleAndReduceFn = emitShuffleAndReduceFunction(
        CGM, Privates, ReductionArrayTy, ReductionFn, Loc);
    llvm::Value *InterWarpCopyFn =
        emitInterWarpCopyFunction(CGM, Privates, ReductionArrayTy, Loc);
  
    llvm::Value *Args[] = {ThreadId,
                           CGF.Builder.getInt32(RHSExprs.size()),
                           ReductionArrayTySize,
                           RL,
                           ShuffleAndReduceFn,
                           InterWarpCopyFn};
  
    llvm::Value *Res = nullptr;
    if (ParallelReduction)
      Res = CGF.EmitRuntimeCall(
          createNVPTXRuntimeFunction(OMPRTL_NVPTX__kmpc_parallel_reduce_nowait),
          Args);
    else if (SimdReduction)
      Res = CGF.EmitRuntimeCall(
          createNVPTXRuntimeFunction(OMPRTL_NVPTX__kmpc_simd_reduce_nowait),
          Args);
  
    if (TeamsReduction) {
      llvm::Value *ScratchPadCopyFn =
          emitCopyToScratchpad(CGM, Privates, ReductionArrayTy, Loc);
      llvm::Value *LoadAndReduceFn = emitReduceScratchpadFunction(
          CGM, Privates, ReductionArrayTy, ReductionFn, Loc);
  
      llvm::Value *Args[] = {ThreadId,
                             CGF.Builder.getInt32(RHSExprs.size()),
                             ReductionArrayTySize,
                             RL,
                             ShuffleAndReduceFn,
                             InterWarpCopyFn,
                             ScratchPadCopyFn,
                             LoadAndReduceFn};
      Res = CGF.EmitRuntimeCall(
          createNVPTXRuntimeFunction(OMPRTL_NVPTX__kmpc_teams_reduce_nowait),
          Args);
    }
  
    // 5. Build switch(res)
    llvm::BasicBlock *DefaultBB = CGF.createBasicBlock(".omp.reduction.default");
    llvm::SwitchInst *SwInst =
        CGF.Builder.CreateSwitch(Res, DefaultBB, /*NumCases=*/1);
  
    // 6. Build case 1: where we have reduced values in the master
    //    thread in each team.
    //    __kmpc_end_reduce{_nowait}(<gtid>);
    //    break;
    llvm::BasicBlock *Case1BB = CGF.createBasicBlock(".omp.reduction.case1");
    SwInst->addCase(CGF.Builder.getInt32(1), Case1BB);
    CGF.EmitBlock(Case1BB);
  
    // Add emission of __kmpc_end_reduce{_nowait}(<gtid>);
    llvm::Value *EndArgs[] = {ThreadId};
    auto &&CodeGen = [Privates, LHSExprs, RHSExprs, ReductionOps,
                      this](CodeGenFunction &CGF, PrePostActionTy &Action) {
      auto IPriv = Privates.begin();
      auto ILHS = LHSExprs.begin();
      auto IRHS = RHSExprs.begin();
      for (const Expr *E : ReductionOps) {
        emitSingleReductionCombiner(CGF, E, *IPriv, cast<DeclRefExpr>(*ILHS),
                                    cast<DeclRefExpr>(*IRHS));
        ++IPriv;
        ++ILHS;
        ++IRHS;
      }
    };
    RegionCodeGenTy RCG(CodeGen);
    NVPTXActionTy Action(
        nullptr, llvm::None,
        createNVPTXRuntimeFunction(OMPRTL_NVPTX__kmpc_end_reduce_nowait),
        EndArgs);
    RCG.setAction(Action);
    RCG(CGF);
    CGF.EmitBranch(DefaultBB);
    CGF.EmitBlock(DefaultBB, /*IsFinished=*/true);
  }
  
  const VarDecl *
  CGOpenMPRuntimeNVPTX::translateParameter(const FieldDecl *FD,
                                           const VarDecl *NativeParam) const {
    if (!NativeParam->getType()->isReferenceType())
      return NativeParam;
    QualType ArgType = NativeParam->getType();
    QualifierCollector QC;
    const Type *NonQualTy = QC.strip(ArgType);
    QualType PointeeTy = cast<ReferenceType>(NonQualTy)->getPointeeType();
    if (const auto *Attr = FD->getAttr<OMPCaptureKindAttr>()) {
      if (Attr->getCaptureKind() == OMPC_map) {
        PointeeTy = CGM.getContext().getAddrSpaceQualType(PointeeTy,
                                                          LangAS::opencl_global);
      }
    }
    ArgType = CGM.getContext().getPointerType(PointeeTy);
    QC.addRestrict();
    enum { NVPTX_local_addr = 5 };
    QC.addAddressSpace(getLangASFromTargetAS(NVPTX_local_addr));
    ArgType = QC.apply(CGM.getContext(), ArgType);
    if (isa<ImplicitParamDecl>(NativeParam))
      return ImplicitParamDecl::Create(
          CGM.getContext(), /*DC=*/nullptr, NativeParam->getLocation(),
          NativeParam->getIdentifier(), ArgType, ImplicitParamDecl::Other);
    return ParmVarDecl::Create(
        CGM.getContext(),
        const_cast<DeclContext *>(NativeParam->getDeclContext()),
        NativeParam->getLocStart(), NativeParam->getLocation(),
        NativeParam->getIdentifier(), ArgType,
        /*TInfo=*/nullptr, SC_None, /*DefArg=*/nullptr);
  }
  
  Address
  CGOpenMPRuntimeNVPTX::getParameterAddress(CodeGenFunction &CGF,
                                            const VarDecl *NativeParam,
                                            const VarDecl *TargetParam) const {
    assert(NativeParam != TargetParam &&
           NativeParam->getType()->isReferenceType() &&
           "Native arg must not be the same as target arg.");
    Address LocalAddr = CGF.GetAddrOfLocalVar(TargetParam);
    QualType NativeParamType = NativeParam->getType();
    QualifierCollector QC;
    const Type *NonQualTy = QC.strip(NativeParamType);
    QualType NativePointeeTy = cast<ReferenceType>(NonQualTy)->getPointeeType();
    unsigned NativePointeeAddrSpace =
        CGF.getContext().getTargetAddressSpace(NativePointeeTy);
    QualType TargetTy = TargetParam->getType();
    llvm::Value *TargetAddr = CGF.EmitLoadOfScalar(
        LocalAddr, /*Volatile=*/false, TargetTy, SourceLocation());
    // First cast to generic.
    TargetAddr = CGF.Builder.CreatePointerBitCastOrAddrSpaceCast(
        TargetAddr, TargetAddr->getType()->getPointerElementType()->getPointerTo(
                        /*AddrSpace=*/0));
    // Cast from generic to native address space.
    TargetAddr = CGF.Builder.CreatePointerBitCastOrAddrSpaceCast(
        TargetAddr, TargetAddr->getType()->getPointerElementType()->getPointerTo(
                        NativePointeeAddrSpace));
    Address NativeParamAddr = CGF.CreateMemTemp(NativeParamType);
    CGF.EmitStoreOfScalar(TargetAddr, NativeParamAddr, /*Volatile=*/false,
                          NativeParamType);
    return NativeParamAddr;
  }
  
  void CGOpenMPRuntimeNVPTX::emitOutlinedFunctionCall(
      CodeGenFunction &CGF, SourceLocation Loc, llvm::Value *OutlinedFn,
      ArrayRef<llvm::Value *> Args) const {
    SmallVector<llvm::Value *, 4> TargetArgs;
    TargetArgs.reserve(Args.size());
    auto *FnType =
        cast<llvm::FunctionType>(OutlinedFn->getType()->getPointerElementType());
    for (unsigned I = 0, E = Args.size(); I < E; ++I) {
      if (FnType->isVarArg() && FnType->getNumParams() <= I) {
        TargetArgs.append(std::next(Args.begin(), I), Args.end());
        break;
      }
      llvm::Type *TargetType = FnType->getParamType(I);
      llvm::Value *NativeArg = Args[I];
      if (!TargetType->isPointerTy()) {
        TargetArgs.emplace_back(NativeArg);
        continue;
      }
      llvm::Value *TargetArg = CGF.Builder.CreatePointerBitCastOrAddrSpaceCast(
          NativeArg,
          NativeArg->getType()->getPointerElementType()->getPointerTo());
      TargetArgs.emplace_back(
          CGF.Builder.CreatePointerBitCastOrAddrSpaceCast(TargetArg, TargetType));
    }
    CGOpenMPRuntime::emitOutlinedFunctionCall(CGF, Loc, OutlinedFn, TargetArgs);
  }
  
  /// Emit function which wraps the outline parallel region
  /// and controls the arguments 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 *CGOpenMPRuntimeNVPTX::createParallelDataSharingWrapper(
      llvm::Function *OutlinedParallelFn, const OMPExecutableDirective &D) {
    ASTContext &Ctx = CGM.getContext();
    const auto &CS = *D.getCapturedStmt(OMPD_parallel);
  
    // Create a function that takes as argument the source thread.
    FunctionArgList WrapperArgs;
    QualType Int16QTy =
        Ctx.getIntTypeForBitwidth(/*DestWidth=*/16, /*Signed=*/false);
    QualType Int32QTy =
        Ctx.getIntTypeForBitwidth(/*DestWidth=*/32, /*Signed=*/false);
    ImplicitParamDecl ParallelLevelArg(Ctx, /*DC=*/nullptr, D.getLocStart(),
                                       /*Id=*/nullptr, Int16QTy,
                                       ImplicitParamDecl::Other);
    ImplicitParamDecl WrapperArg(Ctx, /*DC=*/nullptr, D.getLocStart(),
                                 /*Id=*/nullptr, Int32QTy,
                                 ImplicitParamDecl::Other);
    WrapperArgs.emplace_back(&ParallelLevelArg);
    WrapperArgs.emplace_back(&WrapperArg);
  
    const CGFunctionInfo &CGFI =
        CGM.getTypes().arrangeBuiltinFunctionDeclaration(Ctx.VoidTy, WrapperArgs);
  
    auto *Fn = llvm::Function::Create(
        CGM.getTypes().GetFunctionType(CGFI), llvm::GlobalValue::InternalLinkage,
        Twine(OutlinedParallelFn->getName(), "_wrapper"), &CGM.getModule());
    CGM.SetInternalFunctionAttributes(GlobalDecl(), Fn, CGFI);
    Fn->setLinkage(llvm::GlobalValue::InternalLinkage);
    Fn->setDoesNotRecurse();
  
    CodeGenFunction CGF(CGM, /*suppressNewContext=*/true);
    CGF.StartFunction(GlobalDecl(), Ctx.VoidTy, Fn, CGFI, WrapperArgs,
                      D.getLocStart(), D.getLocStart());
  
    const auto *RD = CS.getCapturedRecordDecl();
    auto CurField = RD->field_begin();
  
    Address ZeroAddr = CGF.CreateMemTemp(
        CGF.getContext().getIntTypeForBitwidth(/*DestWidth=*/32, /*Signed=*/1),
        /*Name*/ ".zero.addr");
    CGF.InitTempAlloca(ZeroAddr, CGF.Builder.getInt32(/*C*/ 0));
    // Get the array of arguments.
    SmallVector<llvm::Value *, 8> Args;
  
    Args.emplace_back(CGF.GetAddrOfLocalVar(&WrapperArg).getPointer());
    Args.emplace_back(ZeroAddr.getPointer());
  
    CGBuilderTy &Bld = CGF.Builder;
    auto CI = CS.capture_begin();
  
    // Use global memory for data sharing.
    // Handle passing of global args to workers.
    Address GlobalArgs =
        CGF.CreateDefaultAlignTempAlloca(CGF.VoidPtrPtrTy, "global_args");
    llvm::Value *GlobalArgsPtr = GlobalArgs.getPointer();
    llvm::Value *DataSharingArgs[] = {GlobalArgsPtr};
    CGF.EmitRuntimeCall(
        createNVPTXRuntimeFunction(OMPRTL_NVPTX__kmpc_get_shared_variables),
        DataSharingArgs);
  
    // Retrieve the shared variables from the list of references returned
    // by the runtime. Pass the variables to the outlined function.
    Address SharedArgListAddress = Address::invalid();
    if (CS.capture_size() > 0 ||
        isOpenMPLoopBoundSharingDirective(D.getDirectiveKind())) {
      SharedArgListAddress = CGF.EmitLoadOfPointer(
          GlobalArgs, CGF.getContext()
                          .getPointerType(CGF.getContext().getPointerType(
                              CGF.getContext().VoidPtrTy))
                          .castAs<PointerType>());
    }
    unsigned Idx = 0;
    if (isOpenMPLoopBoundSharingDirective(D.getDirectiveKind())) {
      Address Src = Bld.CreateConstInBoundsGEP(SharedArgListAddress, Idx,
                                               CGF.getPointerSize());
      Address TypedAddress = Bld.CreatePointerBitCastOrAddrSpaceCast(
          Src, CGF.SizeTy->getPointerTo());
      llvm::Value *LB = CGF.EmitLoadOfScalar(
          TypedAddress,
          /*Volatile=*/false,
          CGF.getContext().getPointerType(CGF.getContext().getSizeType()),
          cast<OMPLoopDirective>(D).getLowerBoundVariable()->getExprLoc());
      Args.emplace_back(LB);
      ++Idx;
      Src = Bld.CreateConstInBoundsGEP(SharedArgListAddress, Idx,
                                       CGF.getPointerSize());
      TypedAddress = Bld.CreatePointerBitCastOrAddrSpaceCast(
          Src, CGF.SizeTy->getPointerTo());
      llvm::Value *UB = CGF.EmitLoadOfScalar(
          TypedAddress,
          /*Volatile=*/false,
          CGF.getContext().getPointerType(CGF.getContext().getSizeType()),
          cast<OMPLoopDirective>(D).getUpperBoundVariable()->getExprLoc());
      Args.emplace_back(UB);
      ++Idx;
    }
    if (CS.capture_size() > 0) {
      ASTContext &CGFContext = CGF.getContext();
      for (unsigned I = 0, E = CS.capture_size(); I < E; ++I, ++CI, ++CurField) {
        QualType ElemTy = CurField->getType();
        Address Src = Bld.CreateConstInBoundsGEP(SharedArgListAddress, I + Idx,
                                                 CGF.getPointerSize());
        Address TypedAddress = Bld.CreatePointerBitCastOrAddrSpaceCast(
            Src, CGF.ConvertTypeForMem(CGFContext.getPointerType(ElemTy)));
        llvm::Value *Arg = CGF.EmitLoadOfScalar(TypedAddress,
                                                /*Volatile=*/false,
                                                CGFContext.getPointerType(ElemTy),
                                                CI->getLocation());
        if (CI->capturesVariableByCopy() &&
            !CI->getCapturedVar()->getType()->isAnyPointerType()) {
          Arg = castValueToType(CGF, Arg, ElemTy, CGFContext.getUIntPtrType(),
                                CI->getLocation());
        }
        Args.emplace_back(Arg);
      }
    }
  
    emitOutlinedFunctionCall(CGF, D.getLocStart(), OutlinedParallelFn, Args);
    CGF.FinishFunction();
    return Fn;
  }
  
  void CGOpenMPRuntimeNVPTX::emitFunctionProlog(CodeGenFunction &CGF,
                                                const Decl *D) {
    assert(D && "Expected function or captured|block decl.");
    assert(FunctionGlobalizedDecls.count(CGF.CurFn) == 0 &&
           "Function is registered already.");
    const Stmt *Body = nullptr;
    bool NeedToDelayGlobalization = false;
    if (const auto *FD = dyn_cast<FunctionDecl>(D)) {
      Body = FD->getBody();
    } else if (const auto *BD = dyn_cast<BlockDecl>(D)) {
      Body = BD->getBody();
    } else if (const auto *CD = dyn_cast<CapturedDecl>(D)) {
      Body = CD->getBody();
      NeedToDelayGlobalization = CGF.CapturedStmtInfo->getKind() == CR_OpenMP;
    }
    if (!Body)
      return;
    CheckVarsEscapingDeclContext VarChecker(CGF);
    VarChecker.Visit(Body);
    const RecordDecl *GlobalizedVarsRecord = VarChecker.getGlobalizedRecord();
    ArrayRef<const ValueDecl *> EscapedVariableLengthDecls =
        VarChecker.getEscapedVariableLengthDecls();
    if (!GlobalizedVarsRecord && EscapedVariableLengthDecls.empty())
      return;
    auto I = FunctionGlobalizedDecls.try_emplace(CGF.CurFn).first;
    I->getSecond().MappedParams =
        llvm::make_unique<CodeGenFunction::OMPMapVars>();
    I->getSecond().GlobalRecord = GlobalizedVarsRecord;
    I->getSecond().EscapedParameters.insert(
        VarChecker.getEscapedParameters().begin(),
        VarChecker.getEscapedParameters().end());
    I->getSecond().EscapedVariableLengthDecls.append(
        EscapedVariableLengthDecls.begin(), EscapedVariableLengthDecls.end());
    DeclToAddrMapTy &Data = I->getSecond().LocalVarData;
    for (const ValueDecl *VD : VarChecker.getEscapedDecls()) {
      assert(VD->isCanonicalDecl() && "Expected canonical declaration");
      const FieldDecl *FD = VarChecker.getFieldForGlobalizedVar(VD);
      Data.insert(std::make_pair(VD, std::make_pair(FD, Address::invalid())));
    }
    if (!NeedToDelayGlobalization) {
      emitGenericVarsProlog(CGF, D->getLocStart());
      struct GlobalizationScope final : EHScopeStack::Cleanup {
        GlobalizationScope() = default;
  
        void Emit(CodeGenFunction &CGF, Flags flags) override {
          static_cast<CGOpenMPRuntimeNVPTX &>(CGF.CGM.getOpenMPRuntime())
              .emitGenericVarsEpilog(CGF);
        }
      };
      CGF.EHStack.pushCleanup<GlobalizationScope>(NormalAndEHCleanup);
    }
  }
  
  Address CGOpenMPRuntimeNVPTX::getAddressOfLocalVariable(CodeGenFunction &CGF,
                                                          const VarDecl *VD) {
    VD = VD->getCanonicalDecl();
    auto I = FunctionGlobalizedDecls.find(CGF.CurFn);
    if (I == FunctionGlobalizedDecls.end())
      return Address::invalid();
    auto VDI = I->getSecond().LocalVarData.find(VD);
    if (VDI != I->getSecond().LocalVarData.end())
      return VDI->second.second;
    if (VD->hasAttrs()) {
      for (specific_attr_iterator<OMPReferencedVarAttr> IT(VD->attr_begin()),
           E(VD->attr_end());
           IT != E; ++IT) {
        auto VDI = I->getSecond().LocalVarData.find(
            cast<VarDecl>(cast<DeclRefExpr>(IT->getRef())->getDecl())
                ->getCanonicalDecl());
        if (VDI != I->getSecond().LocalVarData.end())
          return VDI->second.second;
      }
    }
    return Address::invalid();
  }
  
  void CGOpenMPRuntimeNVPTX::functionFinished(CodeGenFunction &CGF) {
    FunctionGlobalizedDecls.erase(CGF.CurFn);
    CGOpenMPRuntime::functionFinished(CGF);
  }
  