// SPDX-License-Identifier: MIT
// Copyright (c) 2018-2025, Advanced Micro Devices, Inc. All rights reserved.

#pragma once

#include "ck_tile/core.hpp"
#include "ck_tile/ops/common.hpp"
#include "ck_tile/ops/fmha/block/block_attention_bias_enum.hpp"
#include "ck_tile/ops/fmha/block/variants.hpp"

#include <string>
#include <type_traits>
#include <utility>
#include <variant>

#define CK_TILE_FMHA_HANDLE_XOR_LENGTH_FOLD 0
// S[seqlen_q, seqlen_k] = Q[seqlen_q, hdim_q] @ K[seqlen_k, hdim_q]
// S'[seqlen_q, seqlen_k] = S[seqlen_q, seqlen_k] * Scale[1]
// S''[seqlen_q, seqlen_k] = S'[seqlen_q, seqlen_k] + Bias[seqlen_q, seqlen_k]
// P[seqlen_q, seqlen_k] = Softmax(S''[seqlen_q, seqlen_k])
// O[seqlen_q, hdim_v] = P[seqlen_q, seqlen_k] @ V^T[hdim_v, seqlen_k]

namespace ck_tile {

template <typename FmhaPipeline_, typename EpiloguePipeline_>
struct FmhaFwdKernel
{
    using FmhaPipeline                           = ck_tile::remove_cvref_t<FmhaPipeline_>;
    using EpiloguePipeline                       = ck_tile::remove_cvref_t<EpiloguePipeline_>;
    static constexpr ck_tile::index_t kBlockSize = FmhaPipeline::kBlockSize;

    static constexpr ck_tile::index_t kBlockPerCu = FmhaPipeline::kBlockPerCu;
    static_assert(kBlockPerCu > 0);
    static constexpr ck_tile::index_t kBlockPerCuInput = FmhaPipeline::Problem::kBlockPerCu;

    using QDataType    = ck_tile::remove_cvref_t<typename FmhaPipeline::QDataType>;
    using KDataType    = ck_tile::remove_cvref_t<typename FmhaPipeline::KDataType>;
    using VDataType    = ck_tile::remove_cvref_t<typename FmhaPipeline::VDataType>;
    using BiasDataType = ck_tile::remove_cvref_t<typename FmhaPipeline::BiasDataType>;
    using RandValOutputDataType =
        ck_tile::remove_cvref_t<typename FmhaPipeline::RandValOutputDataType>;
    using LSEDataType  = ck_tile::remove_cvref_t<typename FmhaPipeline::LSEDataType>;
    using ODataType    = ck_tile::remove_cvref_t<typename FmhaPipeline::ODataType>;
    using SaccDataType = ck_tile::remove_cvref_t<typename FmhaPipeline::SaccDataType>;

    using VLayout = ck_tile::remove_cvref_t<typename FmhaPipeline::VLayout>;

    static constexpr bool kIsGroupMode      = FmhaPipeline::kIsGroupMode;
    static constexpr bool kPadSeqLenQ       = FmhaPipeline::kPadSeqLenQ;
    static constexpr bool kPadSeqLenK       = FmhaPipeline::kPadSeqLenK;
    static constexpr bool kPadHeadDimQ      = FmhaPipeline::kPadHeadDimQ;
    static constexpr bool kPadHeadDimV      = FmhaPipeline::kPadHeadDimV;
    static constexpr bool kHasLogitsSoftCap = FmhaPipeline::kHasLogitsSoftCap;
    static constexpr auto BiasEnum          = FmhaPipeline::BiasEnum;
    static constexpr bool kStoreLSE         = FmhaPipeline::kStoreLSE;
    static constexpr bool kHasDropout       = FmhaPipeline::kHasDropout;
    static constexpr bool kDoFp8StaticQuant = FmhaPipeline::Problem::kDoFp8StaticQuant;
    static constexpr bool kSkipMinSeqlenQ   = FmhaPipeline::Problem::kSkipMinSeqlenQ;

    using AttentionVariant = ck_tile::remove_cvref_t<typename FmhaPipeline::AttentionVariant>;
    using FmhaMask         = ck_tile::remove_cvref_t<typename FmhaPipeline::FmhaMask>;
    static constexpr bool kHasMask = FmhaMask::IsMasking;

    static constexpr bool kUseAsyncCopy = FmhaPipeline::Policy::AsyncCopy;

    static constexpr bool kUseTrLoad = FmhaPipeline::Problem::kUseTrLoad;
#if defined(__gfx950__)
    static constexpr bool kIsAvailable = true;
#else
    static constexpr bool kIsAvailable = !kUseTrLoad;
#endif
    static constexpr std::string_view kPipelineName = FmhaPipeline::name;

    // clang-format off
    template <typename T1, typename T2 = T1> struct t2s;
    template <> struct t2s<float> { static constexpr const char * name = "fp32"; };
    template <> struct t2s<ck_tile::fp16_t> { static constexpr const char * name = "fp16"; };
    template <> struct t2s<ck_tile::bf16_t> { static constexpr const char * name = "bf16"; };
    template <> struct t2s<ck_tile::fp8_t> { static constexpr const char * name = "fp8"; };
    template <> struct t2s<ck_tile::bf8_t> { static constexpr const char * name = "bf8"; };
    template <> struct t2s<ck_tile::fp8_t, ck_tile::bf16_t> { static constexpr const char * name = "fp8bf16"; };
    template <> struct t2s<ck_tile::fp8_t, ck_tile::fp32_t> { static constexpr const char * name = "fp8fp32"; };
    // clang-format on

    CK_TILE_HOST static std::string GetName()
    {
        // sync with generate.py
        // clang-format off
        using bfs = typename FmhaPipeline::BlockFmhaShape;
        using g0br = typename bfs::Gemm0BlockWarps;
        using g1br = typename bfs::Gemm1BlockWarps;
        using g0wt = typename bfs::Gemm0WarpTile;
        using g1wt = typename bfs::Gemm1WarpTile;
        #define _SS_  std::string
        #define _TS_  std::to_string
        auto pn = [&] () {
            std::string n;
            if (kPadSeqLenQ) n += "s";
            if (kPadSeqLenK) n += "sk";
            if (kPadHeadDimQ) n += "d";
            if (kPadHeadDimV) n += "dv";
            return n.empty() ? n : std::string("p") + n; }();
        return
            _SS_("fmha_fwd_d") + _TS_(bfs::kQKHeaddim) + "_" + _SS_(t2s<QDataType, ODataType>::name) +
            "_" + (kIsGroupMode ? "group" : "batch") + "_"
            "b" + _TS_(bfs::kM0) + "x" + _TS_(bfs::kN0) + "x" + _TS_(bfs::kK0) + "x" +
                    _TS_(bfs::kN1) + "x" + _TS_(bfs::kK1) + "x" + _TS_(bfs::kQKHeaddim) + "_" +
            "r" + _TS_(g0br::at(ck_tile::number<0>{})) + "x" + _TS_(g0br::at(ck_tile::number<1>{})) + "x" + _TS_(g0br::at(ck_tile::number<2>{})) + "_" +
            "r" + _TS_(g1br::at(ck_tile::number<0>{})) + "x" + _TS_(g1br::at(ck_tile::number<1>{})) + "x" + _TS_(g1br::at(ck_tile::number<2>{})) + "_" +
            "w" + _TS_(g0wt::at(ck_tile::number<0>{})) + "x" + _TS_(g0wt::at(ck_tile::number<1>{})) + "x" + _TS_(g0wt::at(ck_tile::number<2>{})) + "_" +
            "w" + _TS_(g1wt::at(ck_tile::number<0>{})) + "x" + _TS_(g1wt::at(ck_tile::number<1>{})) + "x" + _TS_(g1wt::at(ck_tile::number<2>{})) + "_" +
            (kBlockPerCuInput == -1 ? "" : ("o" + _TS_(kBlockPerCu) + "_")) + _SS_(FmhaPipeline::name) + "_" +
            "v" + (std::is_same_v<VLayout, ck_tile::tensor_layout::gemm::RowMajor> ? "r" : "c") + (pn.empty() ? "_npad" : "_" + pn) +
            (kHasLogitsSoftCap ? "_logits" : "_nlogits" ) + (BiasEnum == BlockAttentionBiasEnum::NO_BIAS ? _SS_("_nbias") : (_SS_("_") + BlockAttentionBiasEnumToStr<BiasEnum>::name)) +
            (kHasMask ? "_" + _SS_(FmhaMask::name) : "_nmask") + (kStoreLSE ? "_lse" : "_nlse" ) + (kHasDropout ? "_dropout" : "_ndropout" ) + (kSkipMinSeqlenQ ? "_skip" : "_nskip" ) + (kDoFp8StaticQuant ? "_squant" : "_nsquant" ) + (kUseTrLoad ? "_trload" : "_ntrload");
        #undef _SS_
        #undef _TS_
        // clang-format on
    }

    template <ck_tile::index_t I> // to avoid duplicated base class prblem, introduce an template
                                  // arg
    struct FmhaFwdEmptyKargs
    {
    };

    // kargs use aggregate initializer, so no constructor will provided
    // use inheritance to minimize karg size
    // user need to use MakeKargs() function to create kargs.
    struct FmhaFwdCommonKargs
    {
        const void* q_ptr;
        const void* k_ptr;
        const void* v_ptr;
        void* o_ptr;

        ck_tile::index_t seqlen_q;
        ck_tile::index_t seqlen_k;
        ck_tile::index_t hdim_q;
        ck_tile::index_t hdim_v;

        ck_tile::index_t num_head_q;
        // for MQA/GQA, nhead could be different. This parameter is nhead_q / nhead_k
        // if this param is larger than 1, indicate MQA/GQA case
        ck_tile::index_t nhead_ratio_qk;
        float scale_s;

        ck_tile::index_t stride_q;
        ck_tile::index_t stride_k;
        ck_tile::index_t stride_v;
        ck_tile::index_t stride_o;

        ck_tile::index_t nhead_stride_q;
        ck_tile::index_t nhead_stride_k;
        ck_tile::index_t nhead_stride_v;
        ck_tile::index_t nhead_stride_o;
    };

    struct FmhaFwdLogitsSoftCapKargs
    {
        FmhaFwdLogitsSoftCapKargs() = default;

        void init_logits_soft_cap(float logits_soft_cap_)
        {
            if(0 < logits_soft_cap_)
            {
                logits_soft_cap     = logits_soft_cap_;
                logits_soft_cap_rcp = 1.f / logits_soft_cap;
            }
            else
            {
                logits_soft_cap     = 0.f;
                logits_soft_cap_rcp = 0.f;
            }
        }

        float logits_soft_cap;
        float logits_soft_cap_rcp;
    };

    struct FmhaFwdCommonBiasKargs
    {
        const void* bias_ptr               = nullptr;
        ck_tile::index_t stride_bias       = 0;
        ck_tile::index_t nhead_stride_bias = 0;
    };

    struct FmhaFwdBatchModeBiasKargs : FmhaFwdCommonBiasKargs
    {
        ck_tile::index_t batch_stride_bias = 0;
    };

    struct FmhaFwdAlibiKargs
    {
        // alibi is batch*nhead*1, no matter in batch/group mode, they are the same
        const void* alibi_slope_ptr;
        ck_tile::index_t alibi_slope_stride; // stride in batch, or 0 for all batch share same slope
    };

    struct FmhaFwdMaskKargs
    {
        // ck_tile::index_t window_size_left, window_size_right;
        ck_tile::index_t window_size_left, window_size_right;
        ck_tile::GenericAttentionMaskEnum mask_type;
    };

    struct FmhaFwdFp8StaticQuantKargs
    {
        float scale_p;
        float scale_o;
    };

    struct FmhaFwdCommonLSEKargs
    {
        void* lse_ptr                     = nullptr;
        ck_tile::index_t nhead_stride_lse = 0;
        ck_tile::index_t batch_stride_lse = 0;
    };

    struct FmhaFwdDropoutSeedOffset
    {
        template <typename T>
        union ValueOrPointer
        {
            T val;
            const T* ptr;
        };

        ValueOrPointer<uint64_t> drop_seed;
        ValueOrPointer<uint64_t> drop_offset;
        bool is_drop_seed_offset_from_host;
    };

    struct FmhaFwdCommonDropoutKargs : FmhaFwdDropoutSeedOffset
    {
        void init_dropout(float p_drop, uint64_t seed, uint64_t offset)
        {
            float p_undrop = 1.0 - p_drop;
            p_undrop_in_uint8_t =
                uint8_t(std::floor(p_undrop * std::numeric_limits<uint8_t>::max()));
            rp_undrop = 1.0 / p_undrop;

            this->drop_seed.val                 = seed;
            this->drop_offset.val               = offset;
            this->is_drop_seed_offset_from_host = true;
        }

        void init_dropout(float p_drop, const uint64_t* seed_ptr, const uint64_t* offset_ptr)
        {
            float p_undrop = 1.0 - p_drop;
            p_undrop_in_uint8_t =
                uint8_t(std::floor(p_undrop * std::numeric_limits<uint8_t>::max()));
            rp_undrop = 1.0 / p_undrop;

            this->drop_seed.ptr                 = seed_ptr;
            this->drop_offset.ptr               = offset_ptr;
            this->is_drop_seed_offset_from_host = false;
        }

        float rp_undrop             = 1;
        uint8_t p_undrop_in_uint8_t = std::numeric_limits<uint8_t>::max();
        bool is_store_randval       = false;
        void* rand_val_ptr          = nullptr;

        ck_tile::index_t stride_randval       = 0;
        ck_tile::index_t nhead_stride_randval = 0;
    };

    struct FmhaFwdBatchModeDropoutKargs : FmhaFwdCommonDropoutKargs
    {
        ck_tile::index_t batch_stride_randval = 0;
    };

    struct FmhaFwdSkipMinSeqlenQKargs
    {
        ck_tile::index_t min_seqlen_q = 0;
    };

    struct FmhaFwdBatchModeKargs
        : FmhaFwdCommonKargs,
          std::conditional_t<BiasEnum == BlockAttentionBiasEnum::ELEMENTWISE_BIAS,
                             FmhaFwdBatchModeBiasKargs,
                             std::conditional_t<BiasEnum == BlockAttentionBiasEnum::ALIBI,
                                                FmhaFwdAlibiKargs,
                                                FmhaFwdEmptyKargs<0>>>,
          std::conditional_t<kHasMask, FmhaFwdMaskKargs, FmhaFwdEmptyKargs<1>>,
          std::conditional_t<kStoreLSE, FmhaFwdCommonLSEKargs, FmhaFwdEmptyKargs<2>>,
          std::conditional_t<kDoFp8StaticQuant, FmhaFwdFp8StaticQuantKargs, FmhaFwdEmptyKargs<3>>,
          std::conditional_t<kHasDropout, FmhaFwdBatchModeDropoutKargs, FmhaFwdEmptyKargs<4>>,
          std::conditional_t<kHasLogitsSoftCap, FmhaFwdLogitsSoftCapKargs, FmhaFwdEmptyKargs<5>>
    {
        ck_tile::index_t batch_stride_q;
        ck_tile::index_t batch_stride_k;
        ck_tile::index_t batch_stride_v;
        ck_tile::index_t batch_stride_o;

        // Optional cumulative sequence length pointers for batch mode
        // If provided, they override seqlen_q / seqlen_k per-batch to skip tail padding.
        const int32_t* cu_seqlen_q_ptr = nullptr; // cumulative, length without PAD
        const int32_t* cu_seqlen_k_ptr = nullptr; // cumulative, length without PAD
    };

    struct FmhaFwdGroupModeKargs
        : FmhaFwdCommonKargs,
          std::conditional_t<BiasEnum == BlockAttentionBiasEnum::ELEMENTWISE_BIAS,
                             FmhaFwdCommonBiasKargs,
                             std::conditional_t<BiasEnum == BlockAttentionBiasEnum::ALIBI,
                                                FmhaFwdAlibiKargs,
                                                FmhaFwdEmptyKargs<0>>>,
          std::conditional_t<kHasMask, FmhaFwdMaskKargs, FmhaFwdEmptyKargs<1>>,
          std::conditional_t<kStoreLSE, FmhaFwdCommonLSEKargs, FmhaFwdEmptyKargs<2>>,
          std::conditional_t<kDoFp8StaticQuant, FmhaFwdFp8StaticQuantKargs, FmhaFwdEmptyKargs<3>>,
          std::conditional_t<kHasDropout, FmhaFwdCommonDropoutKargs, FmhaFwdEmptyKargs<4>>,
          std::conditional_t<kHasLogitsSoftCap, FmhaFwdLogitsSoftCapKargs, FmhaFwdEmptyKargs<5>>,
          std::conditional_t<kSkipMinSeqlenQ, FmhaFwdSkipMinSeqlenQKargs, FmhaFwdEmptyKargs<6>>
    {
        const int32_t* seqstart_q_ptr;
        const int32_t* seqstart_k_ptr;
        const int32_t* seqlen_q_ptr;
        const int32_t* seqlen_k_ptr;

        // Optional per-sequence and cumulative logical (excluding padding) sequence length arrays
        const int32_t* cu_seqlen_q_ptr = nullptr;
        const int32_t* cu_seqlen_k_ptr = nullptr;
    };

    using Kargs = std::conditional_t<kIsGroupMode, FmhaFwdGroupModeKargs, FmhaFwdBatchModeKargs>;

    struct BlockIndices
    {
        ck_tile::index_t batch_idx;
        ck_tile::index_t qo_head_idx;
        ck_tile::index_t kv_head_idx;
    };

    template <bool Cond = !kIsGroupMode>
    CK_TILE_HOST static constexpr std::enable_if_t<Cond, Kargs>
    MakeKargsImpl(const void* q_ptr,
                  const void* k_ptr,
                  const void* v_ptr,
                  const void* bias_ptr,
                  void* rand_val_ptr,
                  void* lse_ptr,
                  void* o_ptr,
                  ck_tile::index_t seqlen_q,
                  ck_tile::index_t seqlen_k,
                  ck_tile::index_t hdim_q,
                  ck_tile::index_t hdim_v,
                  ck_tile::index_t num_head_q,
                  ck_tile::index_t nhead_ratio_qk,
                  float scale_s,
                  float scale_p,
                  float scale_o,
                  float logits_soft_cap,
                  ck_tile::index_t stride_q,
                  ck_tile::index_t stride_k,
                  ck_tile::index_t stride_v,
                  ck_tile::index_t stride_bias,
                  ck_tile::index_t stride_randval,
                  ck_tile::index_t stride_o,
                  ck_tile::index_t nhead_stride_q,
                  ck_tile::index_t nhead_stride_k,
                  ck_tile::index_t nhead_stride_v,
                  ck_tile::index_t nhead_stride_bias,
                  ck_tile::index_t nhead_stride_randval,
                  ck_tile::index_t nhead_stride_lse,
                  ck_tile::index_t nhead_stride_o,
                  ck_tile::index_t batch_stride_q,
                  ck_tile::index_t batch_stride_k,
                  ck_tile::index_t batch_stride_v,
                  ck_tile::index_t batch_stride_bias,
                  ck_tile::index_t batch_stride_randval,
                  ck_tile::index_t batch_stride_lse,
                  ck_tile::index_t batch_stride_o,
                  ck_tile::index_t window_size_left,
                  ck_tile::index_t window_size_right,
                  ck_tile::index_t mask_type,
                  float p_drop,
                  bool s_randval,
                  std::variant<std::pair<uint64_t, uint64_t>, std::pair<const void*, const void*>>
                      drop_seed_offset,
                  const void* cu_seqlen_q_ptr = nullptr,
                  const void* cu_seqlen_k_ptr = nullptr)
    {
        Kargs kargs{{q_ptr,
                     k_ptr,
                     v_ptr,
                     o_ptr,
                     seqlen_q,
                     seqlen_k,
                     hdim_q,
                     hdim_v,
                     num_head_q,
                     nhead_ratio_qk,
#if CK_TILE_FMHA_FWD_FAST_EXP2
                     static_cast<float>(scale_s * ck_tile::log2e_v<>),
#else
                     scale_s,
#endif
                     stride_q,
                     stride_k,
                     stride_v,
                     stride_o,
                     nhead_stride_q,
                     nhead_stride_k,
                     nhead_stride_v,
                     nhead_stride_o}, // args for common karg
                    {},               // placeholder for bias
                    {},               // placeholder for mask
                    {},               // placeholder for lse
                    {},               // placeholder for fp8_static_quant args
                    {},               // placeholder for dropout
                    {},               // placeholder for logits_soft_cap
                    batch_stride_q,
                    batch_stride_k,
                    batch_stride_v,
                    batch_stride_o};

        if constexpr(BiasEnum == BlockAttentionBiasEnum::ELEMENTWISE_BIAS)
        {
            kargs.bias_ptr          = bias_ptr;
            kargs.stride_bias       = stride_bias;
            kargs.nhead_stride_bias = nhead_stride_bias;
            kargs.batch_stride_bias = batch_stride_bias;
        }
        else if constexpr(BiasEnum == BlockAttentionBiasEnum::ALIBI)
        {
            kargs.alibi_slope_ptr    = bias_ptr;
            kargs.alibi_slope_stride = stride_bias;
        }
        if constexpr(kHasMask)
        {
            kargs.window_size_left  = window_size_left;
            kargs.window_size_right = window_size_right;
            kargs.mask_type         = static_cast<ck_tile::GenericAttentionMaskEnum>(mask_type);
        }
        if constexpr(kStoreLSE)
        {
            kargs.lse_ptr          = lse_ptr;
            kargs.nhead_stride_lse = nhead_stride_lse;
            kargs.batch_stride_lse = batch_stride_lse;
        }
        if constexpr(kDoFp8StaticQuant)
        {
            kargs.scale_p = scale_p;
            kargs.scale_o = scale_o;
        }
        if constexpr(kHasDropout)
        {
            if(drop_seed_offset.index() == 0) // seed & offset come from host
            {
                const auto& [seed, offset] = std::get<0>(drop_seed_offset);
                kargs.init_dropout(p_drop, seed, offset);
            }
            else // seed & offset come from device
            {
                const auto& [seed_ptr, offset_ptr] = std::get<1>(drop_seed_offset);
                kargs.init_dropout(p_drop,
                                   reinterpret_cast<const uint64_t*>(seed_ptr),
                                   reinterpret_cast<const uint64_t*>(offset_ptr));
            }

            kargs.rand_val_ptr         = rand_val_ptr;
            kargs.stride_randval       = stride_randval;
            kargs.nhead_stride_randval = nhead_stride_randval;
            kargs.batch_stride_randval = batch_stride_randval;
            kargs.is_store_randval     = s_randval;
        }
        if constexpr(kHasLogitsSoftCap)
        {
            kargs.init_logits_soft_cap(logits_soft_cap);
        }

        kargs.cu_seqlen_q_ptr = reinterpret_cast<const int32_t*>(cu_seqlen_q_ptr);
        kargs.cu_seqlen_k_ptr = reinterpret_cast<const int32_t*>(cu_seqlen_k_ptr);
        return kargs;
    }

    // std::variant<> can't take in a list initializer, overload for backward compatibility
    template <bool Cond = !kIsGroupMode>
    CK_TILE_HOST static constexpr std::enable_if_t<Cond, Kargs>
    MakeKargs(const void* q_ptr,
              const void* k_ptr,
              const void* v_ptr,
              const void* bias_ptr,
              void* rand_val_ptr,
              void* lse_ptr,
              void* o_ptr,
              ck_tile::index_t seqlen_q,
              ck_tile::index_t seqlen_k,
              ck_tile::index_t hdim_q,
              ck_tile::index_t hdim_v,
              ck_tile::index_t num_head_q,
              ck_tile::index_t nhead_ratio_qk,
              float scale_s,
              float scale_p,
              float scale_o,
              float logits_soft_cap,
              ck_tile::index_t stride_q,
              ck_tile::index_t stride_k,
              ck_tile::index_t stride_v,
              ck_tile::index_t stride_bias,
              ck_tile::index_t stride_randval,
              ck_tile::index_t stride_o,
              ck_tile::index_t nhead_stride_q,
              ck_tile::index_t nhead_stride_k,
              ck_tile::index_t nhead_stride_v,
              ck_tile::index_t nhead_stride_bias,
              ck_tile::index_t nhead_stride_randval,
              ck_tile::index_t nhead_stride_lse,
              ck_tile::index_t nhead_stride_o,
              ck_tile::index_t batch_stride_q,
              ck_tile::index_t batch_stride_k,
              ck_tile::index_t batch_stride_v,
              ck_tile::index_t batch_stride_bias,
              ck_tile::index_t batch_stride_randval,
              ck_tile::index_t batch_stride_lse,
              ck_tile::index_t batch_stride_o,
              ck_tile::index_t window_size_left,
              ck_tile::index_t window_size_right,
              ck_tile::index_t mask_type,
              float p_drop,
              bool s_randval,
              const std::tuple<uint64_t, uint64_t>& drop_seed_offset,
              const void* cu_seqlen_q_ptr = nullptr,
              const void* cu_seqlen_k_ptr = nullptr)
    {
        return MakeKargsImpl(
            q_ptr,
            k_ptr,
            v_ptr,
            bias_ptr,
            rand_val_ptr,
            lse_ptr,
            o_ptr,
            seqlen_q,
            seqlen_k,
            hdim_q,
            hdim_v,
            num_head_q,
            nhead_ratio_qk,
            scale_s,
            scale_p,
            scale_o,
            logits_soft_cap,
            stride_q,
            stride_k,
            stride_v,
            stride_bias,
            stride_randval,
            stride_o,
            nhead_stride_q,
            nhead_stride_k,
            nhead_stride_v,
            nhead_stride_bias,
            nhead_stride_randval,
            nhead_stride_lse,
            nhead_stride_o,
            batch_stride_q,
            batch_stride_k,
            batch_stride_v,
            batch_stride_bias,
            batch_stride_randval,
            batch_stride_lse,
            batch_stride_o,
            window_size_left,
            window_size_right,
            mask_type,
            p_drop,
            s_randval,
            std::make_pair(std::get<0>(drop_seed_offset), std::get<1>(drop_seed_offset)),
            cu_seqlen_q_ptr,
            cu_seqlen_k_ptr);
    }

    // std::variant<> can't take in a list initializer, overload for backward compatibility
    template <bool Cond = !kIsGroupMode>
    CK_TILE_HOST static constexpr std::enable_if_t<Cond, Kargs>
    MakeKargs(const void* q_ptr,
              const void* k_ptr,
              const void* v_ptr,
              const void* bias_ptr,
              void* rand_val_ptr,
              void* lse_ptr,
              void* o_ptr,
              ck_tile::index_t seqlen_q,
              ck_tile::index_t seqlen_k,
              ck_tile::index_t hdim_q,
              ck_tile::index_t hdim_v,
              ck_tile::index_t num_head_q,
              ck_tile::index_t nhead_ratio_qk,
              float scale_s,
              float scale_p,
              float scale_o,
              float logits_soft_cap,
              ck_tile::index_t stride_q,
              ck_tile::index_t stride_k,
              ck_tile::index_t stride_v,
              ck_tile::index_t stride_bias,
              ck_tile::index_t stride_randval,
              ck_tile::index_t stride_o,
              ck_tile::index_t nhead_stride_q,
              ck_tile::index_t nhead_stride_k,
              ck_tile::index_t nhead_stride_v,
              ck_tile::index_t nhead_stride_bias,
              ck_tile::index_t nhead_stride_randval,
              ck_tile::index_t nhead_stride_lse,
              ck_tile::index_t nhead_stride_o,
              ck_tile::index_t batch_stride_q,
              ck_tile::index_t batch_stride_k,
              ck_tile::index_t batch_stride_v,
              ck_tile::index_t batch_stride_bias,
              ck_tile::index_t batch_stride_randval,
              ck_tile::index_t batch_stride_lse,
              ck_tile::index_t batch_stride_o,
              ck_tile::index_t window_size_left,
              ck_tile::index_t window_size_right,
              ck_tile::index_t mask_type,
              float p_drop,
              bool s_randval,
              const std::tuple<const void*, const void*>& drop_seed_offset,
              const void* cu_seqlen_q_ptr = nullptr,
              const void* cu_seqlen_k_ptr = nullptr)
    {
        return MakeKargsImpl(
            q_ptr,
            k_ptr,
            v_ptr,
            bias_ptr,
            rand_val_ptr,
            lse_ptr,
            o_ptr,
            seqlen_q,
            seqlen_k,
            hdim_q,
            hdim_v,
            num_head_q,
            nhead_ratio_qk,
            scale_s,
            scale_p,
            scale_o,
            logits_soft_cap,
            stride_q,
            stride_k,
            stride_v,
            stride_bias,
            stride_randval,
            stride_o,
            nhead_stride_q,
            nhead_stride_k,
            nhead_stride_v,
            nhead_stride_bias,
            nhead_stride_randval,
            nhead_stride_lse,
            nhead_stride_o,
            batch_stride_q,
            batch_stride_k,
            batch_stride_v,
            batch_stride_bias,
            batch_stride_randval,
            batch_stride_lse,
            batch_stride_o,
            window_size_left,
            window_size_right,
            mask_type,
            p_drop,
            s_randval,
            std::make_pair(std::get<0>(drop_seed_offset), std::get<1>(drop_seed_offset)),
            cu_seqlen_q_ptr,
            cu_seqlen_k_ptr);
    }

    template <bool Cond = kIsGroupMode>
    CK_TILE_HOST static constexpr std::enable_if_t<Cond, Kargs>
    MakeKargsImpl(const void* q_ptr,
                  const void* k_ptr,
                  const void* v_ptr,
                  const void* bias_ptr,
                  void* rand_val_ptr,
                  void* lse_ptr,
                  void* o_ptr,
                  const void* seqstart_q_ptr,
                  const void* seqstart_k_ptr,
                  const void* seqlen_q_ptr,
                  const void* seqlen_k_ptr,
                  ck_tile::index_t hdim_q,
                  ck_tile::index_t hdim_v,
                  ck_tile::index_t num_head_q,
                  ck_tile::index_t nhead_ratio_qk,
                  float scale_s,
                  float scale_p,
                  float scale_o,
                  float logits_soft_cap,
                  ck_tile::index_t stride_q,
                  ck_tile::index_t stride_k,
                  ck_tile::index_t stride_v,
                  ck_tile::index_t stride_bias,
                  ck_tile::index_t stride_randval,
                  ck_tile::index_t stride_o,
                  ck_tile::index_t nhead_stride_q,
                  ck_tile::index_t nhead_stride_k,
                  ck_tile::index_t nhead_stride_v,
                  ck_tile::index_t nhead_stride_bias,
                  ck_tile::index_t nhead_stride_randval,
                  ck_tile::index_t nhead_stride_lse,
                  ck_tile::index_t nhead_stride_o,
                  ck_tile::index_t window_size_left,
                  ck_tile::index_t window_size_right,
                  ck_tile::index_t mask_type,
                  ck_tile::index_t min_seqlen_q,
                  float p_drop,
                  bool s_randval,
                  std::variant<std::pair<uint64_t, uint64_t>, std::pair<const void*, const void*>>
                      drop_seed_offset,
                  const void* cu_seqlen_q_ptr = nullptr,
                  const void* cu_seqlen_k_ptr = nullptr)
    {
        Kargs kargs{{q_ptr,
                     k_ptr,
                     v_ptr,
                     o_ptr,
                     -1, // seqlen will be updated by another pointer
                     -1, //
                     hdim_q,
                     hdim_v,
                     num_head_q,
                     nhead_ratio_qk,
#if CK_TILE_FMHA_FWD_FAST_EXP2
                     static_cast<float>(scale_s * ck_tile::log2e_v<>),
#else
                     scale_s,
#endif
                     stride_q,
                     stride_k,
                     stride_v,
                     stride_o,
                     nhead_stride_q,
                     nhead_stride_k,
                     nhead_stride_v,
                     nhead_stride_o}, // args for common karg
                    {},               // placeholder for bias
                    {},               // placeholder for mask
                    {},               // placeholder for lse
                    {},               // placeholder for fp8_static_quant args
                    {},               // placeholder for dropout
                    {},               // placeholder for logits_soft_cap
                    {},               // placeholder for min_seqlen_q
                    reinterpret_cast<const int32_t*>(seqstart_q_ptr),
                    reinterpret_cast<const int32_t*>(seqstart_k_ptr),
                    reinterpret_cast<const int32_t*>(seqlen_q_ptr),
                    reinterpret_cast<const int32_t*>(seqlen_k_ptr)};

        if constexpr(BiasEnum == BlockAttentionBiasEnum::ELEMENTWISE_BIAS)
        {
            kargs.bias_ptr          = bias_ptr;
            kargs.stride_bias       = stride_bias;
            kargs.nhead_stride_bias = nhead_stride_bias;
        }
        else if constexpr(BiasEnum == BlockAttentionBiasEnum::ALIBI)
        {
            kargs.alibi_slope_ptr    = bias_ptr;
            kargs.alibi_slope_stride = stride_bias;
        }
        if constexpr(kHasMask)
        {
            kargs.window_size_left  = window_size_left;
            kargs.window_size_right = window_size_right;
            kargs.mask_type         = static_cast<ck_tile::GenericAttentionMaskEnum>(mask_type);
        }
        if constexpr(kStoreLSE)
        {
            kargs.lse_ptr          = lse_ptr;
            kargs.nhead_stride_lse = nhead_stride_lse;
        }
        if constexpr(kDoFp8StaticQuant)
        {
            kargs.scale_p = scale_p;
            kargs.scale_o = scale_o;
        }
        if constexpr(kHasDropout)
        {
            if(drop_seed_offset.index() == 0) // seed & offset come from host
            {
                const auto& [seed, offset] = std::get<0>(drop_seed_offset);
                kargs.init_dropout(p_drop, seed, offset);
            }
            else // seed & offset come from device
            {
                const auto& [seed_ptr, offset_ptr] = std::get<1>(drop_seed_offset);
                kargs.init_dropout(p_drop,
                                   reinterpret_cast<const uint64_t*>(seed_ptr),
                                   reinterpret_cast<const uint64_t*>(offset_ptr));
            }

            kargs.rand_val_ptr         = rand_val_ptr;
            kargs.stride_randval       = stride_randval;
            kargs.nhead_stride_randval = nhead_stride_randval;
            kargs.is_store_randval     = s_randval;
        }
        if constexpr(kHasLogitsSoftCap)
        {
            kargs.init_logits_soft_cap(logits_soft_cap);
        }
        if constexpr(kSkipMinSeqlenQ)
        {
            kargs.min_seqlen_q = min_seqlen_q;
        }

        kargs.cu_seqlen_q_ptr = reinterpret_cast<const int32_t*>(cu_seqlen_q_ptr);
        kargs.cu_seqlen_k_ptr = reinterpret_cast<const int32_t*>(cu_seqlen_k_ptr);
        return kargs;
    }

    // std::variant<> can't take in a list initializer, overload for backward compatibility
    template <bool Cond = kIsGroupMode>
    CK_TILE_HOST static constexpr std::enable_if_t<Cond, Kargs>
    MakeKargs(const void* q_ptr,
              const void* k_ptr,
              const void* v_ptr,
              const void* bias_ptr,
              void* rand_val_ptr,
              void* lse_ptr,
              void* o_ptr,
              const void* seqstart_q_ptr,
              const void* seqstart_k_ptr,
              const void* seqlen_q_ptr,
              const void* seqlen_k_ptr,
              ck_tile::index_t hdim_q,
              ck_tile::index_t hdim_v,
              ck_tile::index_t num_head_q,
              ck_tile::index_t nhead_ratio_qk,
              float scale_s,
              float scale_p,
              float scale_o,
              float logits_soft_cap,
              ck_tile::index_t stride_q,
              ck_tile::index_t stride_k,
              ck_tile::index_t stride_v,
              ck_tile::index_t stride_bias,
              ck_tile::index_t stride_randval,
              ck_tile::index_t stride_o,
              ck_tile::index_t nhead_stride_q,
              ck_tile::index_t nhead_stride_k,
              ck_tile::index_t nhead_stride_v,
              ck_tile::index_t nhead_stride_bias,
              ck_tile::index_t nhead_stride_randval,
              ck_tile::index_t nhead_stride_lse,
              ck_tile::index_t nhead_stride_o,
              ck_tile::index_t window_size_left,
              ck_tile::index_t window_size_right,
              ck_tile::index_t mask_type,
              ck_tile::index_t min_seqlen_q,
              float p_drop,
              bool s_randval,
              const std::tuple<uint64_t, uint64_t>& drop_seed_offset,
              const void* cu_seqlen_q_ptr = nullptr,
              const void* cu_seqlen_k_ptr = nullptr)
    {
        return MakeKargsImpl(
            q_ptr,
            k_ptr,
            v_ptr,
            bias_ptr,
            rand_val_ptr,
            lse_ptr,
            o_ptr,
            seqstart_q_ptr,
            seqstart_k_ptr,
            seqlen_q_ptr,
            seqlen_k_ptr,
            hdim_q,
            hdim_v,
            num_head_q,
            nhead_ratio_qk,
            scale_s,
            scale_p,
            scale_o,
            logits_soft_cap,
            stride_q,
            stride_k,
            stride_v,
            stride_bias,
            stride_randval,
            stride_o,
            nhead_stride_q,
            nhead_stride_k,
            nhead_stride_v,
            nhead_stride_bias,
            nhead_stride_randval,
            nhead_stride_lse,
            nhead_stride_o,
            window_size_left,
            window_size_right,
            mask_type,
            min_seqlen_q,
            p_drop,
            s_randval,
            std::make_pair(std::get<0>(drop_seed_offset), std::get<1>(drop_seed_offset)),
            cu_seqlen_q_ptr,
            cu_seqlen_k_ptr);
    }

    // std::variant<> can't take in a list initializer, overload for backward compatibility
    template <bool Cond = kIsGroupMode>
    CK_TILE_HOST static constexpr std::enable_if_t<Cond, Kargs>
    MakeKargs(const void* q_ptr,
              const void* k_ptr,
              const void* v_ptr,
              const void* bias_ptr,
              void* rand_val_ptr,
              void* lse_ptr,
              void* o_ptr,
              const void* seqstart_q_ptr,
              const void* seqstart_k_ptr,
              const void* seqlen_q_ptr,
              const void* seqlen_k_ptr,
              ck_tile::index_t hdim_q,
              ck_tile::index_t hdim_v,
              ck_tile::index_t num_head_q,
              ck_tile::index_t nhead_ratio_qk,
              float scale_s,
              float scale_p,
              float scale_o,
              float logits_soft_cap,
              ck_tile::index_t stride_q,
              ck_tile::index_t stride_k,
              ck_tile::index_t stride_v,
              ck_tile::index_t stride_bias,
              ck_tile::index_t stride_randval,
              ck_tile::index_t stride_o,
              ck_tile::index_t nhead_stride_q,
              ck_tile::index_t nhead_stride_k,
              ck_tile::index_t nhead_stride_v,
              ck_tile::index_t nhead_stride_bias,
              ck_tile::index_t nhead_stride_randval,
              ck_tile::index_t nhead_stride_lse,
              ck_tile::index_t nhead_stride_o,
              ck_tile::index_t window_size_left,
              ck_tile::index_t window_size_right,
              ck_tile::index_t mask_type,
              ck_tile::index_t min_seqlen_q,
              float p_drop,
              bool s_randval,
              const std::tuple<const void*, const void*>& drop_seed_offset,
              const void* cu_seqlen_q_ptr = nullptr,
              const void* cu_seqlen_k_ptr = nullptr)
    {
        return MakeKargsImpl(
            q_ptr,
            k_ptr,
            v_ptr,
            bias_ptr,
            rand_val_ptr,
            lse_ptr,
            o_ptr,
            seqstart_q_ptr,
            seqstart_k_ptr,
            seqlen_q_ptr,
            seqlen_k_ptr,
            hdim_q,
            hdim_v,
            num_head_q,
            nhead_ratio_qk,
            scale_s,
            scale_p,
            scale_o,
            logits_soft_cap,
            stride_q,
            stride_k,
            stride_v,
            stride_bias,
            stride_randval,
            stride_o,
            nhead_stride_q,
            nhead_stride_k,
            nhead_stride_v,
            nhead_stride_bias,
            nhead_stride_randval,
            nhead_stride_lse,
            nhead_stride_o,
            window_size_left,
            window_size_right,
            mask_type,
            min_seqlen_q,
            p_drop,
            s_randval,
            std::make_pair(std::get<0>(drop_seed_offset), std::get<1>(drop_seed_offset)),
            cu_seqlen_q_ptr,
            cu_seqlen_k_ptr);
    }

    CK_TILE_HOST static constexpr auto GridSize(ck_tile::index_t batch_size_,
                                                ck_tile::index_t nhead_,
                                                ck_tile::index_t seqlen_q_,
                                                ck_tile::index_t hdim_v_,
                                                bool has_padded_seqlen_k = false)
    {
        // has_padded_seqlen_k is determined by checking (seqlen_k_ptr != nullptr)
        if(has_padded_seqlen_k)
        {
            // TODO: this may need tuning
            return dim3(nhead_,
                        batch_size_,
                        ck_tile::integer_divide_ceil(seqlen_q_, FmhaPipeline::kM0) *
                            ck_tile::integer_divide_ceil(hdim_v_, FmhaPipeline::kN1));
        }
        else
        {
            // TODO: this may need tuning
            return dim3(nhead_,
                        ck_tile::integer_divide_ceil(seqlen_q_, FmhaPipeline::kM0) *
                            ck_tile::integer_divide_ceil(hdim_v_, FmhaPipeline::kN1),
                        batch_size_);
        }
    }

    CK_TILE_DEVICE static constexpr auto GetTileIndex(const Kargs& kargs)
    {
        bool has_padded_seqlen_k = false;

        if constexpr(kIsGroupMode)
            has_padded_seqlen_k = (kargs.seqlen_k_ptr != nullptr);

        if(has_padded_seqlen_k)
        {
            // const index_t num_tile_m0 = seqlen_q / kM0;
            const index_t num_tile_n1 =
                ck_tile::integer_divide_ceil(kargs.hdim_v, FmhaPipeline::kN1);

            const index_t i_block = blockIdx.z;
            const index_t i_nhead = blockIdx.x;
            const index_t i_batch = blockIdx.y;

            const auto f = [](index_t dividend, index_t divisor) {
                index_t quotient = dividend / divisor;
                index_t modulus  = dividend - quotient * divisor;
                return ck_tile::make_tuple(quotient, modulus);
            };

            const auto [i_tile_m, i_tile_n] = f(i_block, num_tile_n1);

            if constexpr(kHasMask)
            {
                // assume that num_tile_n1 is always 1
                return ck_tile::make_tuple(gridDim.z - 1 - i_tile_m, i_tile_n, i_nhead, i_batch);
            }
            else
            {
                return ck_tile::make_tuple(i_tile_m, i_tile_n, i_nhead, i_batch);
            }
        }
        else
        {
            // const index_t num_tile_m0 = seqlen_q / kM0;
            const index_t num_tile_n1 =
                ck_tile::integer_divide_ceil(kargs.hdim_v, FmhaPipeline::kN1);

            const index_t i_block = blockIdx.y; // blockIdx.x
            const index_t i_nhead = blockIdx.x; // blockIdx.y
            const index_t i_batch = blockIdx.z;

            const auto f = [](index_t dividend, index_t divisor) {
                index_t quotient = dividend / divisor;
                index_t modulus  = dividend - quotient * divisor;
                return ck_tile::make_tuple(quotient, modulus);
            };

            const auto [i_tile_m, i_tile_n] = f(i_block, num_tile_n1);

            if constexpr(kHasMask)
            {
                // assume that num_tile_n1 is always 1
                return ck_tile::make_tuple(gridDim.y - 1 - i_tile_m, i_tile_n, i_nhead, i_batch);
            }
            else
            {
                return ck_tile::make_tuple(i_tile_m, i_tile_n, i_nhead, i_batch);
            }
        }
    }

    CK_TILE_HOST static dim3 BlockSize()
    {
        if(is_wave32())
        {
            return dim3(kBlockSize / 2);
        }
        else
        {
            return dim3(kBlockSize);
        }
    }

    CK_TILE_HOST_DEVICE static constexpr ck_tile::index_t GetSmemSize()
    {
        return ck_tile::max(FmhaPipeline::GetSmemSize(), EpiloguePipeline::GetSmemSize());
    }

    CK_TILE_DEVICE void operator()(Kargs kargs) const
    {
        if constexpr(kIsAvailable)
            run_(std::move(kargs));
    }

    CK_TILE_DEVICE void run_(Kargs kargs) const
    {
        if constexpr(kPipelineName != "qr_async_trload")
        {
            // allocate LDS
            __shared__ char smem_ptr[GetSmemSize()];

            // divide problem
            const auto [i_tile_m, i_tile_n, i_nhead, i_batch] = GetTileIndex(kargs);

            const index_t i_m0 = amd_wave_read_first_lane(i_tile_m * FmhaPipeline::kM0);
            const index_t i_n1 = amd_wave_read_first_lane(i_tile_n * FmhaPipeline::kN1);

            long_index_t batch_offset_q       = 0;
            long_index_t batch_offset_k       = 0;
            long_index_t batch_offset_v       = 0;
            long_index_t batch_offset_bias    = 0;
            long_index_t batch_offset_randval = 0;
            long_index_t batch_offset_lse     = 0;
            long_index_t batch_offset_o       = 0;

            if constexpr(kIsGroupMode)
            {
                // Use seqstart_q_ptr and seqstart_k_ptr for physical starts
                const long_index_t query_start = kargs.seqstart_q_ptr[i_batch];
                const long_index_t key_start   = kargs.seqstart_k_ptr[i_batch];

                // DRAM base offsets use physical starts
                batch_offset_q = query_start * kargs.stride_q;
                batch_offset_k = key_start * kargs.stride_k;
                if constexpr(std::is_same_v<VLayout, ck_tile::tensor_layout::gemm::RowMajor>)
                {
                    batch_offset_v = key_start * kargs.stride_v;
                }
                else
                {
                    batch_offset_v = key_start;
                }
                if constexpr(BiasEnum == BlockAttentionBiasEnum::ELEMENTWISE_BIAS)
                {
                    batch_offset_bias = query_start * kargs.stride_bias;
                }
                if constexpr(kStoreLSE)
                {
                    // LSE follows the physical layout to stay consistent with other tensors
                    batch_offset_lse = query_start;
                }
                if constexpr(kHasDropout)
                {
                    batch_offset_randval = query_start * kargs.stride_randval;
                }
                batch_offset_o = query_start * kargs.stride_o;

                // real logical lengths (exclude PAD)
                // Priority: seqlen_q_ptr > cu_seqlen_q_ptr > calculated from seqstart_q_ptr
                if(kargs.seqlen_q_ptr != nullptr)
                {
                    kargs.seqlen_q = kargs.seqlen_q_ptr[i_batch];
                }
                else if(kargs.cu_seqlen_q_ptr != nullptr)
                {
                    kargs.seqlen_q =
                        kargs.cu_seqlen_q_ptr[i_batch + 1] - kargs.cu_seqlen_q_ptr[i_batch];
                }
                else
                {
                    const auto adjusted_seqstart_q_ptr = kargs.seqstart_q_ptr + i_batch;
                    kargs.seqlen_q = adjusted_seqstart_q_ptr[1] - adjusted_seqstart_q_ptr[0];
                }

                if constexpr(kSkipMinSeqlenQ)
                {
                    if(kargs.seqlen_q <= kargs.min_seqlen_q)
                    {
                        return;
                    }
                }

                // terminate unnecessary blocks earlier
                if(kargs.seqlen_q <= i_m0)
                {
                    return;
                }

                if(kargs.seqlen_k_ptr != nullptr)
                {
                    kargs.seqlen_k = kargs.seqlen_k_ptr[i_batch];
                }
                else if(kargs.cu_seqlen_k_ptr != nullptr)
                {
                    kargs.seqlen_k =
                        kargs.cu_seqlen_k_ptr[i_batch + 1] - kargs.cu_seqlen_k_ptr[i_batch];
                }
                else
                {
                    const auto adjusted_seqstart_k_ptr = kargs.seqstart_k_ptr + i_batch;
                    kargs.seqlen_k = adjusted_seqstart_k_ptr[1] - adjusted_seqstart_k_ptr[0];
                }
            }
            else
            {
                batch_offset_q = static_cast<long_index_t>(i_batch) * kargs.batch_stride_q;
                batch_offset_k = static_cast<long_index_t>(i_batch) * kargs.batch_stride_k;
                batch_offset_v = static_cast<long_index_t>(i_batch) * kargs.batch_stride_v;
                if constexpr(BiasEnum == BlockAttentionBiasEnum::ELEMENTWISE_BIAS)
                {
                    batch_offset_bias =
                        static_cast<long_index_t>(i_batch) * kargs.batch_stride_bias;
                }
                if constexpr(kStoreLSE)
                {
                    batch_offset_lse = static_cast<long_index_t>(i_batch) * kargs.batch_stride_lse;
                }
                if constexpr(kHasDropout)
                {
                    batch_offset_randval =
                        static_cast<long_index_t>(i_batch) * kargs.batch_stride_randval;
                }
                batch_offset_o = static_cast<long_index_t>(i_batch) * kargs.batch_stride_o;

                // If cumulative seqlen pointers are provided, override per-batch effective lengths
                if(kargs.cu_seqlen_q_ptr != nullptr)
                {
                    kargs.seqlen_q =
                        kargs.cu_seqlen_q_ptr[i_batch + 1] - kargs.cu_seqlen_q_ptr[i_batch];
                }
                if(kargs.cu_seqlen_k_ptr != nullptr)
                {
                    kargs.seqlen_k =
                        kargs.cu_seqlen_k_ptr[i_batch + 1] - kargs.cu_seqlen_k_ptr[i_batch];
                }
            }

            // for simplicity, batch stride we just modify the pointer
            const QDataType* q_ptr = reinterpret_cast<const QDataType*>(kargs.q_ptr) +
                                     static_cast<long_index_t>(i_nhead) * kargs.nhead_stride_q +
                                     batch_offset_q;
            const KDataType* k_ptr =
                reinterpret_cast<const KDataType*>(kargs.k_ptr) +
                static_cast<long_index_t>(i_nhead / kargs.nhead_ratio_qk) * kargs.nhead_stride_k +
                batch_offset_k;
            const VDataType* v_ptr =
                reinterpret_cast<const VDataType*>(kargs.v_ptr) +
                static_cast<long_index_t>(i_nhead / kargs.nhead_ratio_qk) * kargs.nhead_stride_v +
                batch_offset_v;
            ODataType* o_ptr = reinterpret_cast<ODataType*>(kargs.o_ptr) +
                               static_cast<long_index_t>(i_nhead) * kargs.nhead_stride_o +
                               batch_offset_o;

            // Q/K/V DRAM and DRAM window
            const auto q_dram = [&]() {
                const auto q_dram_naive = make_naive_tensor_view<address_space_enum::global>(
                    q_ptr,
                    make_tuple(kargs.seqlen_q, kargs.hdim_q),
                    make_tuple(kargs.stride_q, 1),
                    number<FmhaPipeline::kAlignmentQ>{},
                    number<1>{});
                if constexpr(FmhaPipeline::kQLoadOnce)
                {
                    return pad_tensor_view(q_dram_naive,
                                           make_tuple(number<FmhaPipeline::kM0>{},
                                                      number<FmhaPipeline::kSubQKHeaddim>{}),
                                           sequence<kPadSeqLenQ, kPadHeadDimQ>{});
                }
                else
                {
                    return pad_tensor_view(
                        q_dram_naive,
                        make_tuple(number<FmhaPipeline::kM0>{}, number<FmhaPipeline::kK0>{}),
                        sequence<kPadSeqLenQ, kPadHeadDimQ>{});
                }
            }();
            const auto k_dram = [&]() {
                const auto k_dram_naive = make_naive_tensor_view<address_space_enum::global>(
                    k_ptr,
                    make_tuple(kargs.seqlen_k, kargs.hdim_q),
                    make_tuple(kargs.stride_k, 1),
                    number<FmhaPipeline::kAlignmentK>{},
                    number<1>{});

                constexpr bool kPadSeqLenK_ = kUseAsyncCopy ? kPadSeqLenK : false;
                return pad_tensor_view(
                    k_dram_naive,
                    make_tuple(number<FmhaPipeline::kN0>{}, number<FmhaPipeline::kK0>{}),
                    sequence<kPadSeqLenK_, kPadHeadDimQ>{});
            }();
            const auto v_dram = [&]() {
                if constexpr(std::is_same_v<VLayout, ck_tile::tensor_layout::gemm::RowMajor>)
                {
                    const auto v_dram_naive = make_naive_tensor_view<address_space_enum::global>(
                        v_ptr,
                        make_tuple(kargs.seqlen_k, kargs.hdim_v),
                        make_tuple(kargs.stride_v, 1),
                        number<FmhaPipeline::kAlignmentV>{},
                        number<1>{});

                    const auto v_dram_transposed = transform_tensor_view(
                        v_dram_naive,
                        make_tuple(make_pass_through_transform(kargs.hdim_v),
                                   make_pass_through_transform(kargs.seqlen_k)),
                        make_tuple(sequence<1>{}, sequence<0>{}),
                        make_tuple(sequence<0>{}, sequence<1>{}));

                    constexpr bool kPadSeqLenK_ = kUseAsyncCopy ? kPadSeqLenK : false;
                    return pad_tensor_view(
                        v_dram_transposed,
                        make_tuple(number<FmhaPipeline::kN1>{}, number<FmhaPipeline::kK1>{}),
                        sequence<kPadHeadDimV, kPadSeqLenK_>{});
                }
                else
                {
                    const auto v_dram_naive = make_naive_tensor_view<address_space_enum::global>(
                        v_ptr,
                        make_tuple(kargs.hdim_v, kargs.seqlen_k),
                        make_tuple(kargs.stride_v, 1),
                        number<FmhaPipeline::kAlignmentV>{},
                        number<1>{});

                    constexpr bool kPadHeadDimV_ = kUseAsyncCopy ? kPadHeadDimV : false;
                    return pad_tensor_view(
                        v_dram_naive,
                        make_tuple(number<FmhaPipeline::kN1>{}, number<FmhaPipeline::kK1>{}),
                        sequence<kPadHeadDimV_, kPadSeqLenK>{});
                }
            }();

            auto q_dram_window = make_tile_window(
                q_dram,
                [&]() {
                    if constexpr(FmhaPipeline::kQLoadOnce)
                        return make_tuple(number<FmhaPipeline::kM0>{},
                                          number<FmhaPipeline::kSubQKHeaddim>{});
                    else
                        return make_tuple(number<FmhaPipeline::kM0>{}, number<FmhaPipeline::kK0>{});
                }(),
                {i_m0, 0});

            auto k_dram_window = make_tile_window(
                k_dram,
                make_tuple(number<FmhaPipeline::kN0>{}, number<FmhaPipeline::kK0>{}),
                {0, 0});

            auto v_dram_window = make_tile_window(
                v_dram,
                make_tuple(number<FmhaPipeline::kN1>{}, number<FmhaPipeline::kK1>{}),
                {i_n1, 0});
            /// FIXME: Before C++20, capturing structured binding variables are not supported.
            /// Remove following copy capture of the 'i_nhead' if in C++20
            const auto bias_dram_window = [&, i_nhead_ = i_nhead]() {
                constexpr auto bias_dram_window_lengths =
                    make_tuple(number<FmhaPipeline::kM0>{}, number<FmhaPipeline::kN0>{});
                if constexpr(BiasEnum == BlockAttentionBiasEnum::ELEMENTWISE_BIAS)
                {
                    const BiasDataType* bias_ptr =
                        reinterpret_cast<const BiasDataType*>(kargs.bias_ptr) +
                        static_cast<long_index_t>(i_nhead_) * kargs.nhead_stride_bias +
                        batch_offset_bias;

                    const auto bias_dram = [&]() {
                        const auto bias_dram_naive =
                            make_naive_tensor_view<address_space_enum::global>(
                                bias_ptr,
                                make_tuple(kargs.seqlen_q, kargs.seqlen_k),
                                make_tuple(kargs.stride_bias, 1),
                                number<FmhaPipeline::kAlignmentBias>{},
                                number<1>{});

                        return pad_tensor_view(bias_dram_naive,
                                               bias_dram_window_lengths,
                                               sequence<kPadSeqLenQ, kPadSeqLenK>{});
                    }();

                    return make_tile_window(bias_dram, bias_dram_window_lengths, {i_m0, 0});
                }
                else
                {
                    return make_null_tile_window(bias_dram_window_lengths);
                }
            }();

            // lse
            auto lse_dram_window = [&, i_nhead_ = i_nhead]() {
                constexpr auto lse_dram_window_lengths = make_tuple(number<FmhaPipeline::kM0>{});
                if constexpr(kStoreLSE)
                {
                    LSEDataType* lse_ptr =
                        reinterpret_cast<LSEDataType*>(kargs.lse_ptr) +
                        static_cast<long_index_t>(i_nhead_) * kargs.nhead_stride_lse +
                        batch_offset_lse;

                    const auto lse_dram = [&]() {
                        const auto lse_dram_naive =
                            make_naive_tensor_view<address_space_enum::global>(
                                lse_ptr,
                                make_tuple(kargs.seqlen_q),
                                make_tuple(1),
                                number<1>{},
                                number<1>{});

                        return pad_tensor_view(
                            lse_dram_naive, lse_dram_window_lengths, sequence<kPadSeqLenQ>{});
                    }();

                    return make_tile_window(lse_dram, lse_dram_window_lengths, {i_m0});
                }
                else
                {
                    return make_null_tile_window(lse_dram_window_lengths);
                }
            }();

            auto dropout = [&, i_nhead_ = i_nhead, i_batch_ = i_batch]() {
                if constexpr(kHasDropout)
                {
                    return BlockDropout{i_batch_,
                                        i_nhead_,
                                        kargs.num_head_q,
                                        kargs.is_drop_seed_offset_from_host ? kargs.drop_seed.val
                                                                            : *kargs.drop_seed.ptr,
                                        kargs.is_drop_seed_offset_from_host
                                            ? kargs.drop_offset.val
                                            : *kargs.drop_offset.ptr,
                                        kargs.rp_undrop,
                                        kargs.p_undrop_in_uint8_t,
                                        kargs.is_store_randval};
                }
                else
                {
                    return NullBlockDropout{};
                };
            }();

            auto randval_dram_window = [&, i_nhead_ = i_nhead]() {
                constexpr auto randval_dram_window_lengths =
                    make_tuple(number<FmhaPipeline::kM0>{}, number<FmhaPipeline::kN0>{});
                if constexpr(kHasDropout)
                {
                    RandValOutputDataType* rand_val_ptr =
                        reinterpret_cast<RandValOutputDataType*>(kargs.rand_val_ptr) +
                        static_cast<long_index_t>(i_nhead_) * kargs.nhead_stride_randval +
                        batch_offset_randval;

                    const auto randval_dram = [&]() {
                        const auto randval_dram_naive =
                            make_naive_tensor_view<address_space_enum::global>(
                                rand_val_ptr,
                                make_tuple(kargs.seqlen_q, kargs.seqlen_k),
                                make_tuple(kargs.stride_randval, 1),
                                number<1>{},
                                number<1>{});

                        return pad_tensor_view(randval_dram_naive,
                                               randval_dram_window_lengths,
                                               sequence<kPadSeqLenQ, kPadSeqLenK>{});
                    }();

                    return make_tile_window(randval_dram, randval_dram_window_lengths, {i_m0, 0});
                }
                else
                {
                    return make_null_tile_window(randval_dram_window_lengths);
                }
            }();

            FmhaMask mask = [&]() {
                if constexpr(kHasMask)
                    return ck_tile::make_generic_attention_mask_from_lr_window<FmhaMask>(
                        kargs.window_size_left,
                        kargs.window_size_right,
                        kargs.seqlen_q,
                        kargs.seqlen_k,
                        kargs.mask_type == GenericAttentionMaskEnum::MASK_FROM_TOP_LEFT);
                else
                    return FmhaMask{kargs.seqlen_q, kargs.seqlen_k};
            }();

            // WA i_batch capture structure binding before c++20
            auto position_encoding = [&, i_batch_ = i_batch, i_nhead_ = i_nhead]() {
                if constexpr(BiasEnum == BlockAttentionBiasEnum::ALIBI)
                {
                    // data loading, shared by entire wg
                    // TODO: how to use s_read?
                    SaccDataType slope =
                        *(reinterpret_cast<const SaccDataType*>(kargs.alibi_slope_ptr) +
                          i_batch_ * kargs.alibi_slope_stride + i_nhead_);
#if CK_TILE_FMHA_FWD_FAST_EXP2
                    slope *= ck_tile::log2e_v<>;
#endif
                    if constexpr(kHasMask)
                    {
                        return make_alibi_from_lr_mask<SaccDataType, true>(slope,
                                                                           kargs.window_size_left,
                                                                           kargs.window_size_right,
                                                                           kargs.seqlen_q,
                                                                           kargs.seqlen_k,
                                                                           kargs.mask_type);
                    }
                    else
                    {
                        return Alibi<SaccDataType, true>{
                            slope, kargs.seqlen_q, kargs.seqlen_k, AlibiMode::FROM_BOTTOM_RIGHT};
                    }
                }
                else
                {
                    return EmptyPositionEncoding<SaccDataType>{};
                }
            }();

            AttentionVariant variant;
            const auto variant_params = [&] {
                if constexpr(kHasLogitsSoftCap)
                {
                    return ck_tile::LogitsSoftCapParams<FmhaMask, CK_TILE_FMHA_FWD_FAST_EXP2>{
                        mask, kargs.scale_s, kargs.logits_soft_cap, kargs.logits_soft_cap_rcp};
                }
                else
                {
                    return ck_tile::StandardAttentionParams<FmhaMask>{mask, kargs.scale_s};
                }
            }();

            BlockIndices block_indices{i_batch, i_nhead, i_nhead / kargs.nhead_ratio_qk};

            auto o_acc_tile = [&]() {
                if constexpr(kDoFp8StaticQuant)
                {
                    auto o_acc_element_func = [&]() {
                        if constexpr(std::is_same_v<ODataType, ck_tile::fp8_t>)
                            return ck_tile::composes(ck_tile::saturates<ck_tile::fp8_t>{},
                                                     ck_tile::scales{kargs.scale_o});
                        else
                            return ck_tile::scales{kargs.scale_o};
                    }();
                    return FmhaPipeline{}(q_dram_window,
                                          identity{}, // q_element_func
                                          k_dram_window,
                                          identity{}, // k_element_func
                                          v_dram_window,
                                          identity{}, // v_element_func
                                          bias_dram_window,
                                          identity{}, // bias_element_func
                                          randval_dram_window,
                                          lse_dram_window,
                                          identity{},            // lse_element_func
                                          identity{},            // s_acc_element_func
                                          scales{kargs.scale_p}, // p_compute_element_func
                                          o_acc_element_func,    // o_acc_element_func
                                          mask,
                                          position_encoding,
                                          kargs.scale_s,
                                          variant,
                                          variant_params,
                                          block_indices,
                                          smem_ptr,
                                          dropout);
                }
                else
                {
                    return FmhaPipeline{}(q_dram_window,
                                          k_dram_window,
                                          v_dram_window,
                                          bias_dram_window,
                                          randval_dram_window,
                                          lse_dram_window,
                                          mask,
                                          position_encoding,
                                          kargs.scale_s,
                                          variant,
                                          variant_params,
                                          block_indices,
                                          smem_ptr,
                                          dropout);
                }
            }();

            // O DRAM and O DRAM window
            auto o_dram = [&]() {
                const auto o_dram_naive = make_naive_tensor_view<address_space_enum::global>(
                    o_ptr,
                    make_tuple(kargs.seqlen_q, kargs.hdim_v),
                    make_tuple(kargs.stride_o, 1),
                    number<FmhaPipeline::kAlignmentO>{},
                    number<1>{});

                return pad_tensor_view(
                    o_dram_naive,
                    make_tuple(number<FmhaPipeline::kM0>{}, number<FmhaPipeline::kN1>{}),
                    sequence<kPadSeqLenQ, kPadHeadDimV>{});
            }();

            auto o_dram_window = make_tile_window(
                o_dram,
                make_tuple(number<FmhaPipeline::kM0>{}, number<FmhaPipeline::kN1>{}),
                {i_m0, i_n1});

            EpiloguePipeline{}(o_dram_window, o_acc_tile, nullptr);
        }
        else
        {
            // TODO: Refine the logical here.
            // In Decode case
            //     1. we don't expect KV data reused by different ThreadGroups, bypass the cache
            //     2. limit the LDS usage, as we want higher occupancy
            // In Prefill case
            //     1. we expect KV data reused by different ThreadGroups, use cache
            //     2. use more LDS, as we want better memory latency hiding
            // If SplitKV off, we don't expect Q data reused by different ThreadGroups, bypass the
            // cache
            constexpr bool PrefillCase = FmhaPipeline::kM0 >= 128;
            // divide problem
            const auto [i_tile_m, i_tile_n, i_nhead, i_batch] = GetTileIndex(kargs);

            const index_t i_m0 = i_tile_m * FmhaPipeline::kM0;
            const index_t i_n1 = i_tile_n * FmhaPipeline::kN1;

            long_index_t batch_offset_q    = 0;
            long_index_t batch_offset_k    = 0; // unused for paged-kvcache
            long_index_t batch_offset_v    = 0; // unused for paged-kvcache
            long_index_t batch_offset_bias = 0;
            long_index_t batch_offset_lse  = 0;
            long_index_t batch_offset_o    = 0;
            // index_t kv_l2p_offset =
            //     0; // logical-to-physical offset of seqlen_k coordinate. only used for
            //     paged-kvcache

            if constexpr(kIsGroupMode)
            {
                // get starting offset for each batch - use seqstart_q_ptr/seqstart_k_ptr for
                // physical starts
                const long_index_t query_start = kargs.seqstart_q_ptr[i_batch];
                const long_index_t key_start   = kargs.seqstart_k_ptr[i_batch];

                batch_offset_q = query_start * kargs.stride_q;
                batch_offset_k = key_start * kargs.stride_k;
                if constexpr(std::is_same_v<VLayout, ck_tile::tensor_layout::gemm::RowMajor>)
                {
                    batch_offset_v = key_start * kargs.stride_v;
                }
                else
                {
                    // col-major V: offset along seqlen dimension is scalar index
                    batch_offset_v = key_start;
                }
                if constexpr(BiasEnum == BlockAttentionBiasEnum::ELEMENTWISE_BIAS)
                {
                    batch_offset_bias = query_start * kargs.stride_bias;
                }

                // LSE layout is [nhead, total_seqlen] following the physical layout for Q/O
                batch_offset_lse = query_start;
                batch_offset_o   = query_start * kargs.stride_o;

                // get real # queries & # keys under group mode
                if(kargs.seqlen_q_ptr != nullptr)
                {
                    kargs.seqlen_q = kargs.seqlen_q_ptr[i_batch];
                }
                else if(kargs.cu_seqlen_q_ptr != nullptr)
                {
                    kargs.seqlen_q =
                        kargs.cu_seqlen_q_ptr[i_batch + 1] - kargs.cu_seqlen_q_ptr[i_batch];
                }
                else
                {
                    kargs.seqlen_q =
                        kargs.seqstart_q_ptr[i_batch + 1] - kargs.seqstart_q_ptr[i_batch];
                }

                // # of required blocks is different in each groups, terminate unnecessary blocks
                // earlier
                if(kargs.seqlen_q <= i_m0)
                {
                    return;
                }

                if(kargs.seqlen_k_ptr != nullptr)
                {
                    kargs.seqlen_k = kargs.seqlen_k_ptr[i_batch];
                }
                else if(kargs.cu_seqlen_k_ptr != nullptr)
                {
                    kargs.seqlen_k =
                        kargs.cu_seqlen_k_ptr[i_batch + 1] - kargs.cu_seqlen_k_ptr[i_batch];
                }
                else
                {
                    kargs.seqlen_k =
                        kargs.seqstart_k_ptr[i_batch + 1] - kargs.seqstart_k_ptr[i_batch];
                }
            }
            else
            {
                batch_offset_q = static_cast<long_index_t>(i_batch) * kargs.batch_stride_q;
                batch_offset_k = static_cast<long_index_t>(i_batch) * kargs.batch_stride_k;
                batch_offset_v = static_cast<long_index_t>(i_batch) * kargs.batch_stride_v;
                if constexpr(kStoreLSE)
                {
                    batch_offset_lse = static_cast<long_index_t>(i_batch) * kargs.batch_stride_lse;
                }
                batch_offset_o = static_cast<long_index_t>(i_batch) * kargs.batch_stride_o;

                if constexpr(BiasEnum == BlockAttentionBiasEnum::ELEMENTWISE_BIAS)
                {
                    batch_offset_bias =
                        static_cast<long_index_t>(i_batch) * kargs.batch_stride_bias;
                }

                // If cumulative seqlen pointers are provided, override per-batch effective lengths
                if(kargs.cu_seqlen_q_ptr != nullptr)
                {
                    kargs.seqlen_q =
                        kargs.cu_seqlen_q_ptr[i_batch + 1] - kargs.cu_seqlen_q_ptr[i_batch];
                }
                if(kargs.cu_seqlen_k_ptr != nullptr)
                {
                    kargs.seqlen_k =
                        kargs.cu_seqlen_k_ptr[i_batch + 1] - kargs.cu_seqlen_k_ptr[i_batch];
                }
            }

            // for simplicity, batch stride we just modify the pointer
            const index_t i_nhead_k = i_nhead / kargs.nhead_ratio_qk;

            const QDataType* q_ptr = reinterpret_cast<const QDataType*>(kargs.q_ptr) +
                                     static_cast<long_index_t>(i_nhead) * kargs.nhead_stride_q +
                                     batch_offset_q;
            const KDataType* k_ptr = reinterpret_cast<const KDataType*>(kargs.k_ptr) +
                                     static_cast<long_index_t>(i_nhead_k) * kargs.nhead_stride_k +
                                     batch_offset_k;
            const VDataType* v_ptr = reinterpret_cast<const VDataType*>(kargs.v_ptr) +
                                     static_cast<long_index_t>(i_nhead_k) * kargs.nhead_stride_v +
                                     batch_offset_v;

            ODataType* o_ptr = reinterpret_cast<ODataType*>(kargs.o_ptr) +
                               static_cast<long_index_t>(i_nhead) * kargs.nhead_stride_o +
                               batch_offset_o;

            // Q/K/V DRAM and DRAM window
            const auto q_dram = [&] {
                const auto q_dram_naive = [&] {
                    {
                        return make_naive_tensor_view<address_space_enum::global,
                                                      memory_operation_enum::set,
                                                      amd_buffer_coherence_enum::SYSTEM_NT1>(
                            q_ptr,
                            make_tuple(kargs.seqlen_q, kargs.hdim_q),
                            make_tuple(kargs.stride_q, 1),
                            number<FmhaPipeline::kAlignmentQ>{},
                            number<1>{});
                    }
                }();

                if constexpr(FmhaPipeline::kQLoadOnce)
                {
                    const auto seqlen_q   = kargs.seqlen_q;
                    const auto q_dram_pad = pad_tensor_view(
                        q_dram_naive,
                        make_tuple(number<FmhaPipeline::kM0>{}, number<FmhaPipeline::kK0>{}),
                        sequence<false, kPadHeadDimQ>{});
#if CK_TILE_FMHA_HANDLE_XOR_LENGTH_FOLD
                    constexpr index_t LDSLayerSize  = 256 / sizeof(QDataType);
                    constexpr index_t XorLengthFold = LDSLayerSize / (FmhaPipeline::kQKHeaddim);

                    if constexpr(XorLengthFold > 1)
                    {
                        const auto q_dram_unmerged = transform_tensor_view(
                            q_dram_pad,
                            make_tuple(
                                make_unmerge_transform(
                                    make_tuple(seqlen_q / XorLengthFold, XorLengthFold)),
                                make_pass_through_transform(number<FmhaPipeline::kQKHeaddim>{})),
                            make_tuple(sequence<0>{}, sequence<1>{}),
                            make_tuple(sequence<0, 1>{}, sequence<2>{}));

                        const auto q_dram_merged = transform_tensor_view(
                            q_dram_unmerged,
                            make_tuple(make_pass_through_transform(seqlen_q / XorLengthFold),
                                       make_merge_transform_v3_division_mod(make_tuple(
                                           XorLengthFold, number<FmhaPipeline::kQKHeaddim>{}))),
                            make_tuple(sequence<0>{}, sequence<1, 2>{}),
                            make_tuple(sequence<0>{}, sequence<1>{}));

                        const auto q_dram_unmerged_xor = transform_tensor_view(
                            q_dram_merged,
                            make_tuple(make_pass_through_transform(seqlen_q / XorLengthFold),
                                       make_unmerge_transform(make_tuple(
                                           number<LDSLayerSize / FmhaPipeline::kAlignmentQ>{},
                                           number<FmhaPipeline::kAlignmentQ>{}))),
                            make_tuple(sequence<0>{}, sequence<1>{}),
                            make_tuple(sequence<0>{}, sequence<1, 2>{}));

                        const auto q_dram_permuted = transform_tensor_view(
                            q_dram_unmerged_xor,
                            make_tuple(
                                make_xor_transform(
                                    make_tuple(seqlen_q / XorLengthFold,
                                               number<LDSLayerSize / FmhaPipeline::kAlignmentQ>{})),
                                make_pass_through_transform(number<FmhaPipeline::kAlignmentQ>{})),
                            make_tuple(sequence<0, 1>{}, sequence<2>{}),
                            make_tuple(sequence<0, 1>{}, sequence<2>{}));

                        const auto q_dram_tmp = transform_tensor_view(
                            q_dram_permuted,
                            make_tuple(
                                make_pass_through_transform(seqlen_q / XorLengthFold),
                                make_unmerge_transform(
                                    make_tuple(number<XorLengthFold>{},
                                               number<FmhaPipeline::kQKHeaddim /
                                                      FmhaPipeline::kAlignmentQ>{})),
                                make_pass_through_transform(number<FmhaPipeline::kAlignmentQ>{})),
                            make_tuple(sequence<0>{}, sequence<1>{}, sequence<2>{}),
                            make_tuple(sequence<0>{}, sequence<1, 2>{}, sequence<3>{}));

                        return transform_tensor_view(
                            q_dram_tmp,
                            make_tuple(
                                make_merge_transform_v3_division_mod(
                                    make_tuple(seqlen_q / XorLengthFold, number<XorLengthFold>{})),
                                make_merge_transform_v3_division_mod(make_tuple(
                                    number<FmhaPipeline::kQKHeaddim / FmhaPipeline::kAlignmentQ>{},
                                    number<FmhaPipeline::kAlignmentQ>{}))),
                            make_tuple(sequence<0, 1>{}, sequence<2, 3>{}),
                            make_tuple(sequence<0>{}, sequence<1>{}));
                    }
                    else
#endif // CK_TILE_FMHA_HANDLE_XOR_LENGTH_FOLD
                    {
                        const auto q_dram_unmerged = transform_tensor_view(
                            q_dram_pad,
                            make_tuple(
                                make_pass_through_transform(seqlen_q),
                                make_unmerge_transform(make_tuple(
                                    number<FmhaPipeline::kQKHeaddim / FmhaPipeline::kAlignmentQ>{},
                                    number<FmhaPipeline::kAlignmentQ>{}))),
                            make_tuple(sequence<0>{}, sequence<1>{}),
                            make_tuple(sequence<0>{}, sequence<1, 2>{}));

                        const auto q_dram_permuted = transform_tensor_view(
                            q_dram_unmerged,
                            make_tuple(
                                make_xor_transform(make_tuple(seqlen_q,
                                                              number<FmhaPipeline::kQKHeaddim /
                                                                     FmhaPipeline::kAlignmentQ>{})),
                                make_pass_through_transform(number<FmhaPipeline::kAlignmentQ>{})),
                            make_tuple(sequence<0, 1>{}, sequence<2>{}),
                            make_tuple(sequence<0, 1>{}, sequence<2>{}));

                        return transform_tensor_view(
                            q_dram_permuted,
                            make_tuple(
                                make_pass_through_transform(seqlen_q),
                                make_merge_transform_v3_division_mod(make_tuple(
                                    number<FmhaPipeline::kQKHeaddim / FmhaPipeline::kAlignmentQ>{},
                                    number<FmhaPipeline::kAlignmentQ>{}))),
                            make_tuple(sequence<0>{}, sequence<1, 2>{}),
                            make_tuple(sequence<0>{}, sequence<1>{}));
                    }
                }
                else
                {
                    return pad_tensor_view(
                        q_dram_naive,
                        make_tuple(number<FmhaPipeline::kM0>{}, number<FmhaPipeline::kK0>{}),
                        sequence<false, kPadHeadDimQ>{});
                }
            }();

            const auto make_k_dram = [&](const KDataType* data, index_t height) {
                const auto k_dram_naive = make_naive_tensor_view<address_space_enum::global>(
                    data, // will update this pointer if using paged-kvcache
                    make_tuple(height, kargs.hdim_q),
                    make_tuple(kargs.stride_k, 1),
                    number<FmhaPipeline::kAlignmentK>{},
                    number<1>{});

                const auto k_dram_pad = pad_tensor_view(
                    k_dram_naive,
                    make_tuple(number<FmhaPipeline::kN0>{}, number<FmhaPipeline::kK0>{}),
                    sequence<false, kPadHeadDimQ>{});

                constexpr auto kDramTileK =
                    FmhaPipeline::kKLoadOnce ? FmhaPipeline::kQKHeaddim : FmhaPipeline::kK0;

#if CK_TILE_FMHA_HANDLE_XOR_LENGTH_FOLD
                constexpr index_t LDSLayerSize  = 256 / sizeof(KDataType);
                constexpr index_t XorLengthFold = LDSLayerSize / (FmhaPipeline::kQKHeaddim);

                if constexpr(XorLengthFold > 1)
                {
                    const auto k_dram_unmerged = transform_tensor_view(
                        k_dram_pad,
                        make_tuple(make_unmerge_transform(
                                       make_tuple(height / XorLengthFold, XorLengthFold)),
                                   make_pass_through_transform(number<FmhaPipeline::kQKHeaddim>{})),
                        make_tuple(sequence<0>{}, sequence<1>{}),
                        make_tuple(sequence<0, 1>{}, sequence<2>{}));

                    const auto k_dram_merged = transform_tensor_view(
                        k_dram_unmerged,
                        make_tuple(make_pass_through_transform(height / XorLengthFold),
                                   make_merge_transform_v3_division_mod(make_tuple(
                                       XorLengthFold, number<FmhaPipeline::kQKHeaddim>{}))),
                        make_tuple(sequence<0>{}, sequence<1, 2>{}),
                        make_tuple(sequence<0>{}, sequence<1>{}));

                    const auto k_dram_unmerged_xor = transform_tensor_view(
                        k_dram_merged,
                        make_tuple(make_pass_through_transform(height / XorLengthFold),
                                   make_unmerge_transform(make_tuple(
                                       number<LDSLayerSize / FmhaPipeline::kAlignmentK>{},
                                       number<FmhaPipeline::kAlignmentK>{}))),
                        make_tuple(sequence<0>{}, sequence<1>{}),
                        make_tuple(sequence<0>{}, sequence<1, 2>{}));

                    const auto k_dram_permuted = transform_tensor_view(
                        k_dram_unmerged_xor,
                        make_tuple(
                            make_xor_transform(
                                make_tuple(height / XorLengthFold,
                                           number<LDSLayerSize / FmhaPipeline::kAlignmentK>{})),
                            make_pass_through_transform(number<FmhaPipeline::kAlignmentK>{})),
                        make_tuple(sequence<0, 1>{}, sequence<2>{}),
                        make_tuple(sequence<0, 1>{}, sequence<2>{}));

                    const auto k_dram_tmp = transform_tensor_view(
                        k_dram_permuted,
                        make_tuple(
                            make_pass_through_transform(height / XorLengthFold),
                            make_unmerge_transform(make_tuple(
                                number<XorLengthFold>{},
                                number<FmhaPipeline::kQKHeaddim / FmhaPipeline::kAlignmentK>{})),
                            make_pass_through_transform(number<FmhaPipeline::kAlignmentK>{})),
                        make_tuple(sequence<0>{}, sequence<1>{}, sequence<2>{}),
                        make_tuple(sequence<0>{}, sequence<1, 2>{}, sequence<3>{}));

                    return transform_tensor_view(
                        k_dram_tmp,
                        make_tuple(
                            make_merge_transform_v3_division_mod(
                                make_tuple(height / XorLengthFold, number<XorLengthFold>{})),
                            make_merge_transform_v3_division_mod(make_tuple(
                                number<FmhaPipeline::kQKHeaddim / FmhaPipeline::kAlignmentK>{},
                                number<FmhaPipeline::kAlignmentK>{}))),
                        make_tuple(sequence<0, 1>{}, sequence<2, 3>{}),
                        make_tuple(sequence<0>{}, sequence<1>{}));
                }
                else
#endif // CK_TILE_FMHA_HANDLE_XOR_LENGTH_FOLD
                {
                    const auto k_dram_unmerged = transform_tensor_view(
                        k_dram_pad,
                        make_tuple(make_pass_through_transform(height),
                                   make_unmerge_transform(
                                       make_tuple(number<FmhaPipeline::kQKHeaddim / kDramTileK /
                                                         FmhaPipeline::kAlignmentK>{},
                                                  number<kDramTileK / FmhaPipeline::kAlignmentK>{},
                                                  number<FmhaPipeline::kAlignmentK>{}))),
                        make_tuple(sequence<0>{}, sequence<1>{}),
                        make_tuple(sequence<0>{}, sequence<1, 2, 3>{}));

                    const auto k_dram_permuted = transform_tensor_view(
                        k_dram_unmerged,
                        make_tuple(
                            make_xor_transform(make_tuple(
                                height, number<kDramTileK / FmhaPipeline::kAlignmentK>{})),
                            make_pass_through_transform(
                                number<FmhaPipeline::kQKHeaddim / kDramTileK /
                                       FmhaPipeline::kAlignmentK>{}),
                            make_pass_through_transform(number<FmhaPipeline::kAlignmentK>{})),
                        make_tuple(sequence<0, 2>{}, sequence<1>{}, sequence<3>{}),
                        make_tuple(sequence<0, 2>{}, sequence<1>{}, sequence<3>{}));

                    return transform_tensor_view(
                        k_dram_permuted,
                        make_tuple(make_pass_through_transform(height),
                                   make_merge_transform_v3_division_mod(
                                       make_tuple(number<FmhaPipeline::kQKHeaddim / kDramTileK /
                                                         FmhaPipeline::kAlignmentK>{},
                                                  number<kDramTileK / FmhaPipeline::kAlignmentK>{},
                                                  number<FmhaPipeline::kAlignmentK>{}))),
                        make_tuple(sequence<0>{}, sequence<1, 2, 3>{}),
                        make_tuple(sequence<0>{}, sequence<1>{}));
                }
            };
            const auto k_dram = [&]() {
                {
                    return make_k_dram(k_ptr, kargs.seqlen_k);
                }
            }();

            const auto make_v_dram = [&](const VDataType* data, index_t length) {
                const auto v_dram_naive = make_naive_tensor_view<address_space_enum::global>(
                    data, // will update this pointer if using paged-kvcache
                    make_tuple(length, kargs.hdim_v),
                    make_tuple(kargs.stride_v, 1),
                    number<FmhaPipeline::kAlignmentV>{},
                    number<1>{});

                // TODO: Add kVHeadDim
                constexpr index_t XorGroupSize =
                    FmhaPipeline::Problem::BlockFmhaShape::Gemm1WarpTile::at(number<0>{});

                const auto v_dram_pad = pad_tensor_view(
                    v_dram_naive,
                    make_tuple(number<FmhaPipeline::kK1>{}, number<FmhaPipeline::kN1>{}),
                    sequence<kPadSeqLenK, false>{});

#if CK_TILE_FMHA_HANDLE_XOR_LENGTH_FOLD
                constexpr index_t LDSLayerSize  = 256 / sizeof(VDataType);
                constexpr index_t XorLengthFold = LDSLayerSize / (FmhaPipeline::kQKHeaddim);

                if constexpr(XorLengthFold > 1)
                {
                    const auto v_dram_unmerged = transform_tensor_view(
                        v_dram_pad,
                        make_tuple(make_unmerge_transform(
                                       make_tuple(length / XorLengthFold, XorLengthFold)),
                                   make_pass_through_transform(number<FmhaPipeline::kQKHeaddim>{})),
                        make_tuple(sequence<0>{}, sequence<1>{}),
                        make_tuple(sequence<0, 1>{}, sequence<2>{}));

                    const auto v_dram_merged = transform_tensor_view(
                        v_dram_unmerged,
                        make_tuple(make_pass_through_transform(length / XorLengthFold),
                                   make_merge_transform_v3_division_mod(make_tuple(
                                       XorLengthFold, number<FmhaPipeline::kQKHeaddim>{}))),
                        make_tuple(sequence<0>{}, sequence<1, 2>{}),
                        make_tuple(sequence<0>{}, sequence<1>{}));

                    const auto v_dram_unmerged_xor = transform_tensor_view(
                        v_dram_merged,
                        make_tuple(
                            make_pass_through_transform(length / XorLengthFold),
                            make_unmerge_transform(make_tuple(number<LDSLayerSize / XorGroupSize>{},
                                                              number<XorGroupSize>{}))),
                        make_tuple(sequence<0>{}, sequence<1>{}),
                        make_tuple(sequence<0>{}, sequence<1, 2>{}));

                    const auto v_dram_permuted = transform_tensor_view(
                        v_dram_unmerged_xor,
                        make_tuple(
                            make_xor_transform(make_tuple(length / XorLengthFold,
                                                          number<LDSLayerSize / XorGroupSize>{})),
                            make_pass_through_transform(number<XorGroupSize>{})),
                        make_tuple(sequence<0, 1>{}, sequence<2>{}),
                        make_tuple(sequence<0, 1>{}, sequence<2>{}));

                    const auto v_dram_tmp = transform_tensor_view(
                        v_dram_permuted,
                        make_tuple(make_pass_through_transform(length / XorLengthFold),
                                   make_unmerge_transform(make_tuple(
                                       number<XorLengthFold>{},
                                       number<FmhaPipeline::kQKHeaddim / XorGroupSize>{})),
                                   make_pass_through_transform(number<XorGroupSize>{})),
                        make_tuple(sequence<0>{}, sequence<1>{}, sequence<2>{}),
                        make_tuple(sequence<0>{}, sequence<1, 2>{}, sequence<3>{}));

                    return transform_tensor_view(
                        v_dram_tmp,
                        make_tuple(make_merge_transform_v3_division_mod(
                                       make_tuple(length / XorLengthFold, number<XorLengthFold>{})),
                                   make_merge_transform_v3_division_mod(
                                       make_tuple(number<FmhaPipeline::kQKHeaddim / XorGroupSize>{},
                                                  number<XorGroupSize>{}))),
                        make_tuple(sequence<0, 1>{}, sequence<2, 3>{}),
                        make_tuple(sequence<0>{}, sequence<1>{}));
                }
                else
#endif // CK_TILE_FMHA_HANDLE_XOR_LENGTH_FOLD
                {
                    const auto v_dram_unmerged = transform_tensor_view(
                        v_dram_pad,
                        make_tuple(make_pass_through_transform(length),
                                   make_unmerge_transform(
                                       make_tuple(number<FmhaPipeline::kQKHeaddim / XorGroupSize>{},
                                                  number<XorGroupSize>{}))),
                        make_tuple(sequence<0>{}, sequence<1>{}),
                        make_tuple(sequence<0>{}, sequence<1, 2>{}));

                    const auto v_dram_permuted = transform_tensor_view(
                        v_dram_unmerged,
                        make_tuple(make_xor_transform(make_tuple(
                                       length, number<FmhaPipeline::kQKHeaddim / XorGroupSize>{})),
                                   make_pass_through_transform(number<XorGroupSize>{})),
                        make_tuple(sequence<0, 1>{}, sequence<2>{}),
                        make_tuple(sequence<0, 1>{}, sequence<2>{}));

                    return transform_tensor_view(
                        v_dram_permuted,
                        make_tuple(make_pass_through_transform(length),
                                   make_merge_transform_v3_division_mod(
                                       make_tuple(number<FmhaPipeline::kQKHeaddim / XorGroupSize>{},
                                                  number<XorGroupSize>{}))),
                        make_tuple(sequence<0>{}, sequence<1, 2>{}),
                        make_tuple(sequence<0>{}, sequence<1>{}));
                }
            };

            const auto v_dram = [&]() {
                {
                    return make_v_dram(v_ptr, kargs.seqlen_k);
                }
            }();

            auto q_dram_window = make_tile_window(
                q_dram,
                [&]() {
                    if constexpr(FmhaPipeline::kQLoadOnce)
                        return make_tuple(number<FmhaPipeline::kM0>{},
                                          number<FmhaPipeline::kSubQKHeaddim>{});
                    else
                        return make_tuple(number<FmhaPipeline::kM0>{}, number<FmhaPipeline::kK0>{});
                }(),
                {i_m0, 0});

            auto k_dram_window = make_tile_window(
                k_dram,
                make_tuple(number<FmhaPipeline::kN0>{}, number<FmhaPipeline::kK0>{}),
                {0, 0});

            auto v_dram_window = make_tile_window(
                v_dram,
                make_tuple(number<FmhaPipeline::kN1>{}, number<FmhaPipeline::kK1>{}),
                {0, 0});

            /// FIXME: Before C++20, capturing structured binding variables are not supported.
            /// Remove following copy capture of the 'i_nhead' if in C++20
            const auto bias_dram_window = [&, i_nhead_ = i_nhead]() {
                constexpr auto bias_dram_window_lengths =
                    make_tuple(number<FmhaPipeline::kM0>{}, number<FmhaPipeline::kN0>{});
                if constexpr(BiasEnum == BlockAttentionBiasEnum::ELEMENTWISE_BIAS)
                {
                    const BiasDataType* bias_ptr =
                        reinterpret_cast<const BiasDataType*>(kargs.bias_ptr) +
                        static_cast<long_index_t>(i_nhead_) * kargs.nhead_stride_bias +
                        batch_offset_bias;

                    const auto bias_dram = [&]() {
                        const auto bias_dram_naive =
                            make_naive_tensor_view<address_space_enum::global>(
                                bias_ptr,
                                make_tuple(kargs.seqlen_q, kargs.seqlen_k),
                                make_tuple(kargs.stride_bias, 1),
                                number<FmhaPipeline::kAlignmentBias>{},
                                number<1>{});

                        return pad_tensor_view(bias_dram_naive,
                                               bias_dram_window_lengths,
                                               sequence<false, kPadSeqLenK>{});
                    }();

                    return make_tile_window(bias_dram, bias_dram_window_lengths, {i_m0, 0});
                }
                else
                {
                    return make_null_tile_window(bias_dram_window_lengths);
                }
            }();

            // lse acc
            auto lse_dram_window = [&, i_nhead_ = i_nhead]() {
                constexpr auto lse_dram_window_lengths = make_tuple(number<FmhaPipeline::kM0>{});
                if constexpr(kStoreLSE)
                {
                    LSEDataType* lse_ptr =
                        reinterpret_cast<LSEDataType*>(kargs.lse_ptr) +
                        static_cast<long_index_t>(i_nhead_) * kargs.nhead_stride_lse +
                        batch_offset_lse;

                    const auto lse_dram = [&] {
                        const auto lse_dram_naive = [&] {
                            {
                                return make_naive_tensor_view<address_space_enum::global>(
                                    lse_ptr,
                                    make_tuple(kargs.seqlen_q),
                                    make_tuple(1),
                                    number<1>{},
                                    number<1>{});
                            }
                        }();
                        return pad_tensor_view(
                            lse_dram_naive, lse_dram_window_lengths, sequence<kPadSeqLenQ>{});
                    }();

                    return make_tile_window(lse_dram, lse_dram_window_lengths, {i_m0});
                }
                else
                {
                    return make_null_tile_window(lse_dram_window_lengths);
                }
            }();

            FmhaMask mask = [&]() {
                if constexpr(kHasMask)
                    return ck_tile::make_generic_attention_mask_from_lr_window<FmhaMask>(
                        kargs.window_size_left,
                        kargs.window_size_right,
                        kargs.seqlen_q,
                        kargs.seqlen_k,
                        kargs.mask_type == GenericAttentionMaskEnum::MASK_FROM_TOP_LEFT);
                else
                    return FmhaMask{kargs.seqlen_q, kargs.seqlen_k};
            }();

            // WA i_batch capture structure binding before c++20
            auto position_encoding = [&, i_batch_ = i_batch, i_nhead_ = i_nhead]() {
                if constexpr(BiasEnum == BlockAttentionBiasEnum::ALIBI)
                {
                    // data loading, shared by entire wg
                    // TODO: how to use s_read?
                    SaccDataType slope =
                        *(reinterpret_cast<const SaccDataType*>(kargs.alibi_slope_ptr) +
                          i_batch_ * kargs.alibi_slope_stride + i_nhead_);
#if CK_TILE_FMHA_FWD_FAST_EXP2
                    slope *= ck_tile::log2e_v<>;
#endif
                    if constexpr(kHasMask)
                    {
                        return make_alibi_from_lr_mask<SaccDataType, true, 32>(
                            slope,
                            kargs.window_size_left,
                            kargs.window_size_right,
                            kargs.seqlen_q,
                            kargs.seqlen_k,
                            kargs.mask_type);
                    }
                    else
                    {
                        return Alibi<SaccDataType, true, 32>{
                            slope, kargs.seqlen_q, kargs.seqlen_k, AlibiMode::FROM_BOTTOM_RIGHT};
                    }
                }
                else
                {
                    return EmptyPositionEncoding<SaccDataType>{};
                }
            }();

            auto o_acc_tile = [&]() {
                if constexpr(PrefillCase)
                {
                    // allocate double lds
                    // add __restrict__ here to avoid aliasing
                    __shared__ char smem_ptrk0
                        [FmhaPipeline::Policy::template GetSmemSizeK<typename FmhaPipeline::Problem,
                                                                     true>()];
                    __shared__ char smem_ptrk1
                        [FmhaPipeline::Policy::template GetSmemSizeK<typename FmhaPipeline::Problem,
                                                                     true>()];
                    __shared__ char smem_ptrv0[FmhaPipeline::Policy::template GetSmemSizeV<
                        typename FmhaPipeline::Problem>()];
                    __shared__ char smem_ptrv1[FmhaPipeline::Policy::template GetSmemSizeV<
                        typename FmhaPipeline::Problem>()];

                    return FmhaPipeline{}(q_dram_window,
                                          k_dram_window,
                                          v_dram_window,
                                          bias_dram_window,
                                          lse_dram_window,
                                          mask,
                                          position_encoding,
                                          kargs.scale_s,
                                          smem_ptrk0,
                                          smem_ptrk1,
                                          smem_ptrv0,
                                          smem_ptrv1);
                }
                else
                {
                    __shared__ char smem_ptr[GetSmemSize()];
                    return FmhaPipeline{}(q_dram_window,
                                          k_dram_window,
                                          v_dram_window,
                                          bias_dram_window,
                                          lse_dram_window,
                                          mask,
                                          position_encoding,
                                          kargs.scale_s,
                                          smem_ptr);
                }
            }();

            // Oacc DRAM and Oacc DRAM window
            auto o_dram = [&] {
                const auto o_dram_naive = [&] {
                    {
                        return make_naive_tensor_view<address_space_enum::global>(
                            o_ptr,
                            make_tuple(kargs.seqlen_q, kargs.hdim_v),
                            make_tuple(kargs.stride_o, 1),
                            number<FmhaPipeline::kAlignmentOacc>{},
                            number<1>{});
                    }
                }();

                return pad_tensor_view(
                    o_dram_naive,
                    make_tuple(number<FmhaPipeline::kM0>{}, number<FmhaPipeline::kN1>{}),
                    sequence<kPadSeqLenQ, kPadHeadDimV>{});
            }();

            auto o_dram_window = make_tile_window(
                o_dram,
                make_tuple(number<FmhaPipeline::kM0>{}, number<FmhaPipeline::kN1>{}),
                {i_m0, i_n1});

            EpiloguePipeline{}(o_dram_window, o_acc_tile, nullptr);
        }
    }
};

} // namespace ck_tile
