import torch
import torch.nn.functional as F
import tilelang
from tilelang.autotuner import *
import tilelang.language as T
from einops import rearrange, einsum
import argparse


@tilelang.jit(
    out_idx=[6],
    pass_configs={
        tilelang.PassConfigKey.TL_ENABLE_FAST_MATH: True,
    },
    compile_flags=[
        "-O3", "-Wno-deprecated-declarations", "-U__CUDA_NO_HALF_OPERATORS__",
        "-U__CUDA_NO_HALF_CONVERSIONS__", "-U__CUDA_NO_HALF2_OPERATORS__",
        "-U__CUDA_NO_BFLOAT16_CONVERSIONS__", "--expt-relaxed-constexpr", "--expt-extended-lambda",
        "--ptxas-options=-v,--register-usage-level=10", "-DNDEBUG"
    ],
)
def flashattn(batch, heads, kv_head_num, seqlen_kv, dim, pe_dim, block_N, block_H, num_split,
              softmax_scale):
    sm_scale = float(softmax_scale * 1.44269504)  # log2(e)
    dtype = "float16"
    accum_dtype = "float"
    kv_group_num = heads // kv_head_num
    VALID_BLOCK_H = min(block_H, kv_group_num)
    assert kv_head_num == 1, "kv_head_num must be 1"

    @T.macro
    def flash_attn(
            Q: T.Tensor([batch, heads, dim], dtype),
            Q_pe: T.Tensor([batch, heads, pe_dim], dtype),
            KV: T.Tensor([batch, seqlen_kv, kv_head_num, dim], dtype),
            K_pe: T.Tensor([batch, seqlen_kv, kv_head_num, pe_dim], dtype),
            Output: T.Tensor([batch, heads, dim], dtype),
    ):
        with T.Kernel(heads // min(block_H, kv_group_num), batch, threads=384) as (hid, bid):
            Q_shared_l = T.alloc_shared([block_H, dim // 2], dtype)
            Q_shared_r = T.alloc_shared([block_H, dim // 2], dtype)
            Q_tail_shared = T.alloc_shared([block_H, pe_dim], dtype)
            KV_shared_0_l = T.alloc_shared([block_N, dim // 2], dtype)
            KV_shared_0_r = T.alloc_shared([block_N, dim // 2], dtype)
            KV_shared_1_l = T.alloc_shared([block_N, dim // 2], dtype)
            KV_shared_1_r = T.alloc_shared([block_N, dim // 2], dtype)
            K_tail_shared_0 = T.alloc_shared([block_N, pe_dim], dtype)
            K_tail_shared_1 = T.alloc_shared([block_N, pe_dim], dtype)
            O_shared_l = Q_shared_l
            O_shared_r = Q_shared_r

            acc_o_l = T.alloc_fragment([block_H, dim // 2], accum_dtype)
            acc_o_r = T.alloc_fragment([block_H, dim // 2], accum_dtype)
            acc_s = T.alloc_fragment([block_H, block_N], accum_dtype)
            S_shared = T.alloc_shared([block_H, block_N], dtype)
            sumexp = T.alloc_fragment([block_H], accum_dtype)
            sum_exp_shared = T.alloc_shared([block_H], accum_dtype)
            sumexp_i = T.alloc_fragment([block_H], accum_dtype)
            alpha_shared = T.alloc_shared([block_H], accum_dtype, scope="shared")
            alpha_local = T.alloc_fragment([block_H], accum_dtype)
            m_i = T.alloc_fragment([block_H], accum_dtype)
            m_i_prev = T.alloc_fragment([block_H], accum_dtype)

            # TODO: Multi buffer
            bar_q = T.alloc_barrier(arrive_count=384)
            bar_k_0_ready = T.alloc_barrier(arrive_count=128)
            bar_k_1_ready = T.alloc_barrier(arrive_count=128)
            bar_k_0_free = T.alloc_barrier(arrive_count=256)
            bar_k_1_free = T.alloc_barrier(arrive_count=256)
            bar_sScale_and_sS_ready = T.alloc_barrier(arrive_count=256)
            bar_sScale_and_sS_free = T.alloc_barrier(arrive_count=256)

            cur_kv_head = hid // (kv_group_num // block_H)
            NI = T.ceildiv((seqlen_kv // num_split), block_N)

            tx = T.get_thread_binding()

            T.copy(Q[bid, hid * VALID_BLOCK_H:(hid + 1) * VALID_BLOCK_H, 0:dim // 2], Q_shared_l)
            T.copy(Q[bid, hid * VALID_BLOCK_H:(hid + 1) * VALID_BLOCK_H, dim // 2:dim], Q_shared_r)
            T.copy(Q_pe[bid, hid * VALID_BLOCK_H:(hid + 1) * VALID_BLOCK_H, :], Q_tail_shared)

            T.barrier_arrive(bar_q)

            if tx < 128:
                T.set_max_nreg(240, 1)
                T.fill(sumexp, 0)
                T.fill(m_i, -2**30)  # avoid -inf - inf to cause nan
                T.fill(acc_o_l, 0)
                T.barrier_wait(bar_q, 0)

                for i_i in T.serial(T.ceildiv(NI, 2)):
                    # Buffer 0
                    T.barrier_wait(bar_k_0_ready[0], (i_i & 1))

                    T.clear(acc_s)
                    T.gemm(Q_shared_l, KV_shared_0_l, acc_s, transpose_B=True, wg_wait=-1)
                    T.gemm(Q_shared_r, KV_shared_0_r, acc_s, transpose_B=True, wg_wait=-1)
                    T.gemm(Q_tail_shared, K_tail_shared_0, acc_s, transpose_B=True, wg_wait=-1)

                    T.wait_wgmma(0)

                    if i_i != 0:
                        T.barrier_arrive(bar_sScale_and_sS_free)
                        T.barrier_wait(bar_sScale_and_sS_free, ((i_i * 2) & 1) ^ 1)

                    T.copy(m_i, m_i_prev)
                    T.reduce_max(acc_s, out=m_i, dim=1, clear=False)
                    for h_i in T.Parallel(block_H):
                        m_i[h_i] = T.max(m_i[h_i], m_i_prev[h_i])
                    for h_i in T.Parallel(block_H):
                        alpha_local[h_i] = T.exp2((m_i_prev[h_i] - m_i[h_i]) * sm_scale)
                    for h_i, bi_i in T.Parallel(block_H, block_N):
                        acc_s[h_i, bi_i] = T.exp2(acc_s[h_i, bi_i] * sm_scale - m_i[h_i] * sm_scale)
                    T.reduce_sum(acc_s, sumexp_i, dim=1)  # is this a accumulate operator?
                    for h_i in T.Parallel(block_H):
                        sumexp[h_i] = sumexp[h_i] * alpha_local[h_i] + sumexp_i[h_i]
                    for h_i, d_i in T.Parallel(block_H, dim // 2):
                        acc_o_l[h_i, d_i] *= alpha_local[h_i]
                    T.copy(alpha_local, alpha_shared)

                    T.copy(acc_s, S_shared)
                    T.gemm(S_shared, KV_shared_0_l, acc_o_l)

                    T.barrier_arrive(bar_sScale_and_sS_ready)
                    T.barrier_arrive(bar_k_0_free[0])

                    # Buffer 1
                    T.barrier_wait(bar_k_1_ready[0], (i_i & 1))

                    T.clear(acc_s)
                    T.gemm(Q_shared_l, KV_shared_1_l, acc_s, transpose_B=True, wg_wait=-1)
                    T.gemm(Q_shared_r, KV_shared_1_r, acc_s, transpose_B=True, wg_wait=-1)
                    T.gemm(Q_tail_shared, K_tail_shared_1, acc_s, transpose_B=True, wg_wait=-1)

                    T.wait_wgmma(0)

                    T.barrier_arrive(bar_sScale_and_sS_free)
                    T.barrier_wait(bar_sScale_and_sS_free, ((i_i * 2 + 1) & 1) ^ 1)

                    T.copy(m_i, m_i_prev)
                    T.reduce_max(acc_s, m_i, dim=1, clear=False)
                    for h_i in T.Parallel(block_H):
                        m_i[h_i] = T.max(m_i[h_i], m_i_prev[h_i])
                    for h_i in T.Parallel(block_H):
                        alpha_local[h_i] = T.exp2((m_i_prev[h_i] - m_i[h_i]) * sm_scale)
                    for h_i, bi_i in T.Parallel(block_H, block_N):
                        acc_s[h_i, bi_i] = T.exp2(acc_s[h_i, bi_i] * sm_scale - m_i[h_i] * sm_scale)
                    T.reduce_sum(acc_s, sumexp_i, dim=1)  # is this a accumulate operator?
                    for h_i in T.Parallel(block_H):
                        sumexp[h_i] = sumexp[h_i] * alpha_local[h_i] + sumexp_i[h_i]
                    for h_i, d_i in T.Parallel(block_H, dim // 2):
                        acc_o_l[h_i, d_i] *= alpha_local[h_i]
                    T.copy(alpha_local, alpha_shared)

                    T.copy(acc_s, S_shared)
                    T.gemm(S_shared, KV_shared_1_l, acc_o_l)

                    T.barrier_arrive(bar_sScale_and_sS_ready)
                    T.barrier_arrive(bar_k_1_free[0])

                # Rescale
                for h_i in T.Parallel(block_H):
                    sum_exp_shared[h_i] = sumexp[h_i]
                for h_i, d_i in T.Parallel(block_H, dim // 2):
                    acc_o_l[h_i, d_i] /= sumexp[h_i]
                for h_i in T.Parallel(block_H):
                    sumexp[h_i] = T.log2(sumexp[h_i]) + m_i[h_i] * sm_scale
                T.copy(acc_o_l, O_shared_l)
                T.copy(O_shared_l, Output[bid, hid * VALID_BLOCK_H:(hid + 1) * VALID_BLOCK_H,
                                          0:dim // 2])

            elif tx >= 128 and tx < 256:
                T.set_max_nreg(168, 1)
                T.fill(acc_o_r, 0)
                for i_i in T.serial(T.ceildiv(NI, 2)):
                    # Buffer 0
                    T.barrier_arrive(bar_sScale_and_sS_ready)
                    T.barrier_wait(bar_sScale_and_sS_ready, ((i_i * 2) & 1))
                    for h_i, d_i in T.Parallel(block_H, dim // 2):
                        acc_o_r[h_i, d_i] *= alpha_shared[h_i]
                    T.gemm(S_shared, KV_shared_0_r, acc_o_r)
                    T.barrier_arrive(bar_k_0_free[0])
                    T.barrier_arrive(bar_sScale_and_sS_free)

                    # Buffer 1
                    T.barrier_arrive(bar_sScale_and_sS_ready)
                    T.barrier_wait(bar_sScale_and_sS_ready, ((i_i * 2 + 1) & 1))
                    for h_i, d_i in T.Parallel(block_H, dim // 2):
                        acc_o_r[h_i, d_i] *= alpha_shared[h_i]
                    T.gemm(S_shared, KV_shared_1_r, acc_o_r)
                    T.barrier_arrive(bar_k_1_free[0])
                    if i_i != T.ceildiv(NI, 2) - 1:
                        T.barrier_arrive(bar_sScale_and_sS_free)

                # Rescale
                for h_i, d_i in T.Parallel(block_H, dim // 2):
                    acc_o_r[h_i, d_i] /= sum_exp_shared[h_i]

                T.copy(acc_o_r, O_shared_r)
                T.copy(O_shared_r, Output[bid, hid * VALID_BLOCK_H:(hid + 1) * VALID_BLOCK_H,
                                          dim // 2:dim])

            elif tx >= 256:
                # producer
                T.set_max_nreg(80, 0)
                for i_i in T.serial(T.ceildiv(NI, 2)):
                    # Buffer 0
                    T.barrier_wait(bar_k_0_free[0], ((i_i & 1) ^ 1))
                    for r in T.serial(4):
                        kv_indices = (i_i * 2) * block_N + r * 16 + (tx - 256) // 8
                        with T.attr("default", "async_scope", 1):
                            for u in T.serial(4):
                                for v in T.vectorized(8):
                                    KV_shared_0_l[r * 16 + (tx - 256) // 8,
                                                  64 * u + (tx - 256) % 8 * 8 +
                                                  v] = KV[bid, kv_indices, cur_kv_head,
                                                          64 * u + (tx - 256) % 8 * 8 + v]
                                    KV_shared_0_r[r * 16 + (tx - 256) // 8,
                                                  64 * u + (tx - 256) % 8 * 8 +
                                                  v] = KV[bid, kv_indices, cur_kv_head, dim // 2 +
                                                          64 * u + (tx - 256) % 8 * 8 + v]
                        with T.attr("default", "async_scope", 1):
                            for v in T.vectorized(8):
                                K_tail_shared_0[r * 16 + (tx - 256) // 8, (tx - 256) % 8 * 8 +
                                                v] = K_pe[bid, kv_indices, cur_kv_head,
                                                          (tx - 256) % 8 * 8 + v]
                    T.cp_async_barrier_noinc(bar_k_0_ready[0])

                    # Buffer 1
                    T.barrier_wait(bar_k_1_free[0], ((i_i & 1) ^ 1))
                    for r in T.serial(4):
                        kv_indices = (i_i * 2 + 1) * block_N + r * 16 + (tx - 256) // 8
                        with T.attr("default", "async_scope", 1):
                            for u in T.serial(4):
                                for v in T.vectorized(8):
                                    KV_shared_1_l[r * 16 + (tx - 256) // 8,
                                                  64 * u + (tx - 256) % 8 * 8 +
                                                  v] = KV[bid, kv_indices, cur_kv_head,
                                                          64 * u + (tx - 256) % 8 * 8 + v]
                                    KV_shared_1_r[r * 16 + (tx - 256) // 8,
                                                  64 * u + (tx - 256) % 8 * 8 +
                                                  v] = KV[bid, kv_indices, cur_kv_head, dim // 2 +
                                                          64 * u + (tx - 256) % 8 * 8 + v]
                        with T.attr("default", "async_scope", 1):
                            for v in T.vectorized(8):
                                K_tail_shared_1[r * 16 + (tx - 256) // 8, (tx - 256) % 8 * 8 +
                                                v] = K_pe[bid, kv_indices, cur_kv_head,
                                                          (tx - 256) % 8 * 8 + v]
                    T.cp_async_barrier_noinc(bar_k_1_ready[0])

    @T.macro
    def flash_attn_split(
            Q: T.Tensor([batch, heads, dim], dtype),
            Q_pe: T.Tensor([batch, heads, pe_dim], dtype),
            KV: T.Tensor([batch, seqlen_kv, kv_head_num, dim], dtype),
            K_pe: T.Tensor([batch, seqlen_kv, kv_head_num, pe_dim], dtype),
            glse: T.Tensor([batch, heads, num_split], dtype),
            Output_partial: T.Tensor([batch, heads, num_split, dim], dtype),
    ):
        with T.Kernel(
                batch, heads // min(block_H, kv_group_num), num_split,
                threads=384) as (bid, hid, bz):
            Q_shared_l = T.alloc_shared([block_H, dim // 2], dtype)
            Q_shared_r = T.alloc_shared([block_H, dim // 2], dtype)
            Q_tail_shared = T.alloc_shared([block_H, pe_dim], dtype)
            KV_shared_0_l = T.alloc_shared([block_N, dim // 2], dtype)
            KV_shared_0_r = T.alloc_shared([block_N, dim // 2], dtype)
            KV_shared_1_l = T.alloc_shared([block_N, dim // 2], dtype)
            KV_shared_1_r = T.alloc_shared([block_N, dim // 2], dtype)
            K_tail_shared_0 = T.alloc_shared([block_N, pe_dim], dtype)
            K_tail_shared_1 = T.alloc_shared([block_N, pe_dim], dtype)
            O_shared_l = Q_shared_l
            O_shared_r = Q_shared_r

            acc_o_l = T.alloc_fragment([block_H, dim // 2], accum_dtype)
            acc_o_r = T.alloc_fragment([block_H, dim // 2], accum_dtype)
            acc_s = T.alloc_fragment([block_H, block_N], accum_dtype)
            S_shared = T.alloc_shared([block_H, block_N], dtype)
            sumexp = T.alloc_fragment([block_H], accum_dtype)
            sum_exp_shared = T.alloc_shared([block_H], accum_dtype)
            sumexp_i = T.alloc_fragment([block_H], accum_dtype)
            alpha_shared = T.alloc_shared([block_H], accum_dtype, scope="shared")
            alpha_local = T.alloc_fragment([block_H], accum_dtype)
            m_i = T.alloc_fragment([block_H], accum_dtype)
            m_i_prev = T.alloc_fragment([block_H], accum_dtype)

            # TODO: Multi buffer
            bar_q = T.alloc_barrier(arrive_count=384)
            bar_k_0_ready = T.alloc_barrier(arrive_count=128)
            bar_k_1_ready = T.alloc_barrier(arrive_count=128)
            bar_k_0_free = T.alloc_barrier(arrive_count=256)
            bar_k_1_free = T.alloc_barrier(arrive_count=256)
            bar_sScale_and_sS_ready = T.alloc_barrier(arrive_count=256)
            bar_sScale_and_sS_free = T.alloc_barrier(arrive_count=256)

            cur_kv_head = hid // (kv_group_num // block_H)
            NI = T.ceildiv((seqlen_kv // num_split), block_N)

            tx = T.get_thread_binding()

            T.copy(Q[bid, hid * VALID_BLOCK_H:(hid + 1) * VALID_BLOCK_H, 0:dim // 2], Q_shared_l)
            T.copy(Q[bid, hid * VALID_BLOCK_H:(hid + 1) * VALID_BLOCK_H, dim // 2:dim], Q_shared_r)
            T.copy(Q_pe[bid, hid * VALID_BLOCK_H:(hid + 1) * VALID_BLOCK_H, :], Q_tail_shared)

            T.barrier_arrive(bar_q)

            if tx < 128:
                T.set_max_nreg(240, 1)
                T.fill(sumexp, 0)
                T.fill(m_i, -2**30)  # avoid -inf - inf to cause nan
                T.fill(acc_o_l, 0)
                T.barrier_wait(bar_q, 0)

                for i_i in T.serial(T.ceildiv(NI, 2)):
                    # Buffer 0
                    T.barrier_wait(bar_k_0_ready[0], (i_i & 1))

                    T.clear(acc_s)
                    T.gemm(Q_shared_l, KV_shared_0_l, acc_s, transpose_B=True, wg_wait=-1)
                    T.gemm(Q_shared_r, KV_shared_0_r, acc_s, transpose_B=True, wg_wait=-1)
                    T.gemm(Q_tail_shared, K_tail_shared_0, acc_s, transpose_B=True, wg_wait=-1)

                    T.wait_wgmma(0)

                    if i_i != 0:
                        T.barrier_arrive(bar_sScale_and_sS_free)
                        T.barrier_wait(bar_sScale_and_sS_free, ((i_i * 2) & 1) ^ 1)

                    T.copy(m_i, m_i_prev)
                    T.reduce_max(acc_s, m_i, dim=1, clear=False)
                    for h_i in T.Parallel(block_H):
                        m_i[h_i] = T.max(m_i[h_i], m_i_prev[h_i])
                    for h_i in T.Parallel(block_H):
                        alpha_local[h_i] = T.exp2((m_i_prev[h_i] - m_i[h_i]) * sm_scale)
                    for h_i, bi_i in T.Parallel(block_H, block_N):
                        acc_s[h_i, bi_i] = T.exp2(acc_s[h_i, bi_i] * sm_scale - m_i[h_i] * sm_scale)
                    T.reduce_sum(acc_s, sumexp_i, dim=1)  # is this a accumulate operator?
                    for h_i in T.Parallel(block_H):
                        sumexp[h_i] = sumexp[h_i] * alpha_local[h_i] + sumexp_i[h_i]
                    for h_i, d_i in T.Parallel(block_H, dim // 2):
                        acc_o_l[h_i, d_i] *= alpha_local[h_i]
                    T.copy(alpha_local, alpha_shared)

                    T.copy(acc_s, S_shared)
                    T.gemm(S_shared, KV_shared_0_l, acc_o_l)

                    T.barrier_arrive(bar_sScale_and_sS_ready)
                    T.barrier_arrive(bar_k_0_free[0])

                    # Buffer 1
                    T.barrier_wait(bar_k_1_ready[0], (i_i & 1))

                    T.clear(acc_s)
                    T.gemm(Q_shared_l, KV_shared_1_l, acc_s, transpose_B=True, wg_wait=-1)
                    T.gemm(Q_shared_r, KV_shared_1_r, acc_s, transpose_B=True, wg_wait=-1)
                    T.gemm(Q_tail_shared, K_tail_shared_1, acc_s, transpose_B=True, wg_wait=-1)

                    T.wait_wgmma(0)

                    T.barrier_arrive(bar_sScale_and_sS_free)
                    T.barrier_wait(bar_sScale_and_sS_free, ((i_i * 2 + 1) & 1) ^ 1)

                    T.copy(m_i, m_i_prev)
                    T.reduce_max(acc_s, m_i, dim=1, clear=False)
                    for h_i in T.Parallel(block_H):
                        m_i[h_i] = T.max(m_i[h_i], m_i_prev[h_i])
                    for h_i in T.Parallel(block_H):
                        alpha_local[h_i] = T.exp2((m_i_prev[h_i] - m_i[h_i]) * sm_scale)
                    for h_i, bi_i in T.Parallel(block_H, block_N):
                        acc_s[h_i, bi_i] = T.exp2(acc_s[h_i, bi_i] * sm_scale - m_i[h_i] * sm_scale)
                    T.reduce_sum(acc_s, sumexp_i, dim=1)  # is this a accumulate operator?
                    for h_i in T.Parallel(block_H):
                        sumexp[h_i] = sumexp[h_i] * alpha_local[h_i] + sumexp_i[h_i]
                    for h_i, d_i in T.Parallel(block_H, dim // 2):
                        acc_o_l[h_i, d_i] *= alpha_local[h_i]
                    T.copy(alpha_local, alpha_shared)

                    T.copy(acc_s, S_shared)
                    T.gemm(S_shared, KV_shared_1_l, acc_o_l)

                    T.barrier_arrive(bar_sScale_and_sS_ready)
                    T.barrier_arrive(bar_k_1_free[0])

                # Rescale
                for h_i in T.Parallel(block_H):
                    sum_exp_shared[h_i] = sumexp[h_i]
                for h_i, d_i in T.Parallel(block_H, dim // 2):
                    acc_o_l[h_i, d_i] /= sumexp[h_i]
                for h_i in T.Parallel(block_H):
                    sumexp[h_i] = T.log2(sumexp[h_i]) + m_i[h_i] * sm_scale
                T.copy(acc_o_l, O_shared_l)
                T.copy(
                    O_shared_l, Output_partial[bid, hid * VALID_BLOCK_H:(hid + 1) * VALID_BLOCK_H,
                                               bz, 0:dim // 2])
                T.copy(sumexp, glse[bid, hid * VALID_BLOCK_H:(hid + 1) * VALID_BLOCK_H, bz])

            elif tx >= 128 and tx < 256:
                T.set_max_nreg(168, 1)
                T.fill(acc_o_r, 0)
                for i_i in T.serial(T.ceildiv(NI, 2)):
                    # Buffer 0
                    T.barrier_arrive(bar_sScale_and_sS_ready)
                    T.barrier_wait(bar_sScale_and_sS_ready, ((i_i * 2) & 1))
                    for h_i, d_i in T.Parallel(block_H, dim // 2):
                        acc_o_r[h_i, d_i] *= alpha_shared[h_i]
                    T.gemm(S_shared, KV_shared_0_r, acc_o_r)
                    T.barrier_arrive(bar_k_0_free[0])
                    T.barrier_arrive(bar_sScale_and_sS_free)

                    # Buffer 1
                    T.barrier_arrive(bar_sScale_and_sS_ready)
                    T.barrier_wait(bar_sScale_and_sS_ready, ((i_i * 2 + 1) & 1))
                    for h_i, d_i in T.Parallel(block_H, dim // 2):
                        acc_o_r[h_i, d_i] *= alpha_shared[h_i]
                    T.gemm(S_shared, KV_shared_1_r, acc_o_r)
                    T.barrier_arrive(bar_k_1_free[0])
                    if i_i != T.ceildiv(NI, 2) - 1:
                        T.barrier_arrive(bar_sScale_and_sS_free)

                # Rescale
                for h_i, d_i in T.Parallel(block_H, dim // 2):
                    acc_o_r[h_i, d_i] /= sum_exp_shared[h_i]

                T.copy(acc_o_r, O_shared_r)
                T.copy(
                    O_shared_r, Output_partial[bid, hid * VALID_BLOCK_H:(hid + 1) * VALID_BLOCK_H,
                                               bz, dim // 2:dim])

            elif tx >= 256:
                # producer
                T.set_max_nreg(80, 0)
                for i_i in T.serial(T.ceildiv(NI, 2)):
                    # Buffer 0
                    T.barrier_wait(bar_k_0_free[0], ((i_i & 1) ^ 1))
                    for r in T.serial(4):
                        kv_indices = (seqlen_kv // num_split) * bz + (
                            i_i * 2) * block_N + r * 16 + (tx - 256) // 8
                        with T.attr("default", "async_scope", 1):
                            for u in T.serial(4):
                                for v in T.vectorized(8):
                                    KV_shared_0_l[r * 16 + (tx - 256) // 8,
                                                  64 * u + (tx - 256) % 8 * 8 +
                                                  v] = KV[bid, kv_indices, cur_kv_head,
                                                          64 * u + (tx - 256) % 8 * 8 + v]
                                    KV_shared_0_r[r * 16 + (tx - 256) // 8,
                                                  64 * u + (tx - 256) % 8 * 8 +
                                                  v] = KV[bid, kv_indices, cur_kv_head, dim // 2 +
                                                          64 * u + (tx - 256) % 8 * 8 + v]
                        with T.attr("default", "async_scope", 1):
                            for v in T.vectorized(8):
                                K_tail_shared_0[r * 16 + (tx - 256) // 8, (tx - 256) % 8 * 8 +
                                                v] = K_pe[bid, kv_indices, cur_kv_head,
                                                          (tx - 256) % 8 * 8 + v]
                    T.cp_async_barrier_noinc(bar_k_0_ready[0])

                    # Buffer 1
                    T.barrier_wait(bar_k_1_free[0], ((i_i & 1) ^ 1))
                    for r in T.serial(4):
                        kv_indices = (seqlen_kv // num_split) * bz + (
                            i_i * 2 + 1) * block_N + r * 16 + (tx - 256) // 8
                        with T.attr("default", "async_scope", 1):
                            for u in T.serial(4):
                                for v in T.vectorized(8):
                                    KV_shared_1_l[r * 16 + (tx - 256) // 8,
                                                  64 * u + (tx - 256) % 8 * 8 +
                                                  v] = KV[bid, kv_indices, cur_kv_head,
                                                          64 * u + (tx - 256) % 8 * 8 + v]
                                    KV_shared_1_r[r * 16 + (tx - 256) // 8,
                                                  64 * u + (tx - 256) % 8 * 8 +
                                                  v] = KV[bid, kv_indices, cur_kv_head, dim // 2 +
                                                          64 * u + (tx - 256) % 8 * 8 + v]
                        with T.attr("default", "async_scope", 1):
                            for v in T.vectorized(8):
                                K_tail_shared_1[r * 16 + (tx - 256) // 8, (tx - 256) % 8 * 8 +
                                                v] = K_pe[bid, kv_indices, cur_kv_head,
                                                          (tx - 256) % 8 * 8 + v]
                    T.cp_async_barrier_noinc(bar_k_1_ready[0])

    @T.macro
    def combine(
            glse: T.Tensor([batch, heads, num_split], dtype),
            Output_partial: T.Tensor([batch, heads, num_split, dim], dtype),
            Output: T.Tensor([batch, heads, dim], dtype),
    ):
        with T.Kernel(heads, batch, threads=128) as (hid, bz):
            po_local = T.alloc_fragment([dim], dtype)
            o_accum_local = T.alloc_fragment([dim], accum_dtype)
            lse_local_split = T.alloc_local([1], accum_dtype)
            lse_logsum_local = T.alloc_local([1], accum_dtype)
            lse_max_local = T.alloc_local([1], accum_dtype)
            scale_local = T.alloc_local([1], accum_dtype)

            T.annotate_layout({
                lse_logsum_local: T.Fragment(lse_logsum_local.shape, forward_thread_fn=lambda i: i),
            })

            T.clear(lse_logsum_local)
            T.clear(o_accum_local)
            lse_max_local[0] = -T.infinity(accum_dtype)
            for k in T.serial(num_split):
                lse_max_local[0] = T.max(lse_max_local[0], glse[bz, hid, k])
            for k in T.Pipelined(num_split, num_stages=1):
                lse_local_split[0] = glse[bz, hid, k]
                lse_logsum_local[0] += T.exp2(lse_local_split[0] - lse_max_local[0])
            lse_logsum_local[0] = T.log2(lse_logsum_local[0]) + lse_max_local[0]
            for k in T.serial(num_split):
                for i in T.Parallel(dim):
                    po_local[i] = Output_partial[bz, hid, k, i]
                lse_local_split[0] = glse[bz, hid, k]
                scale_local[0] = T.exp2(lse_local_split[0] - lse_logsum_local[0])
                for i in T.Parallel(dim):
                    o_accum_local[i] += po_local[i] * scale_local[0]
            for i in T.Parallel(dim):
                Output[bz, hid, i] = o_accum_local[i]

    @T.prim_func
    def main_split(
            Q: T.Tensor([batch, heads, dim], dtype),
            Q_pe: T.Tensor([batch, heads, pe_dim], dtype),
            KV: T.Tensor([batch, seqlen_kv, kv_head_num, dim], dtype),
            K_pe: T.Tensor([batch, seqlen_kv, kv_head_num, pe_dim], dtype),
            glse: T.Tensor([batch, heads, num_split], dtype),
            Output_partial: T.Tensor([batch, heads, num_split, dim], dtype),
            Output: T.Tensor([batch, heads, dim], dtype),
    ):
        flash_attn_split(Q, Q_pe, KV, K_pe, glse, Output_partial)
        combine(glse, Output_partial, Output)

    @T.prim_func
    def main_no_split(
            Q: T.Tensor([batch, heads, dim], dtype),
            Q_pe: T.Tensor([batch, heads, pe_dim], dtype),
            KV: T.Tensor([batch, seqlen_kv, kv_head_num, dim], dtype),
            K_pe: T.Tensor([batch, seqlen_kv, kv_head_num, pe_dim], dtype),
            glse: T.Tensor([batch, heads, num_split], dtype),
            Output_partial: T.Tensor([batch, heads, num_split, dim], dtype),
            Output: T.Tensor([batch, heads, dim], dtype),
    ):
        flash_attn(Q, Q_pe, KV, K_pe, Output)

    if num_split > 1:
        return main_split
    else:
        return main_no_split


def ref_program(q, q_pe, kv, k_pe, glse, Output_partial):
    #     """
    #     Inputs:
    #     - q (Tensor): [batch, heads, dim]
    #     - q_pe (Tensor): [batch, heads, pe_dim]
    #     - kv (Tensor): [batch, seqlen_kv, kv_head_num, dim]
    #     - k_pe (Tensor): [batch, seqlen_kv, kv_head_num, pe_dim]
    #     - glse (Tensor): [batch, heads, num_split]
    #     - Output_partial (Tensor): [batch, heads, num_split, dim]
    #     Outputs:
    #     - output (Tensor): [batch, heads, dim]
    #     """
    dim = q.shape[-1]
    pe_dim = q_pe.shape[-1]
    num_head_groups = q.shape[1] // kv.shape[2]
    scale = (dim + pe_dim)**0.5
    q = rearrange(
        q, 'b (h g) d -> b g h d', g=num_head_groups)  # [batch_size, num_head_groups, groups, dim]

    q_pe = rearrange(
        q_pe, 'b (h g) d -> b g h d',
        g=num_head_groups)  # [batch_size, num_head_groups, groups, pe_dim]

    kv = rearrange(kv, 'b n h d -> b h n d')  # [batch_size, groups, seqlen_kv, dim]

    k_pe = rearrange(k_pe, 'b n h d -> b h n d')  # [batch_size, num_head_groups, groups, pe_dim]

    query = torch.concat([q, q_pe], dim=-1)
    key = torch.concat([kv, k_pe], dim=-1)

    scores = einsum(
        query, key,
        'b g h d, b h s d -> b g h s')  # [batch_size, num_head_groups, groups, seqlen_kv]

    attention = F.softmax(
        scores / scale, dim=-1)  # [batch_size, num_head_groups, groups, seqlen_kv]

    out = einsum(attention, kv,
                 'b g h s, b h s d -> b g h d')  # [batch_size, num_head_groups, groups, dim]
    out = rearrange(out, 'b g h d -> b (h g) d')  # [batch_size, heads, dim]
    return out


def main(
    batch=1,
    heads=128,
    kv_heads=1,
    kv_ctx=8192,
    dim=512,
    pe_dim=64,
):
    qk_flops = 2 * batch * heads * kv_ctx * (dim + pe_dim)
    pv_flops = 2 * batch * heads * kv_ctx * dim
    total_flops = qk_flops + pv_flops
    BLOCK_N = 64
    BLOCK_H = min(64, heads // kv_heads)
    num_split = 1
    softmax_scale = (dim + pe_dim)**-0.5

    kernel = flashattn(batch, heads, kv_heads, kv_ctx, dim, pe_dim, BLOCK_N, BLOCK_H, num_split,
                       softmax_scale)
    profiler = kernel.get_profiler(tensor_supply_type=tilelang.TensorSupplyType.Randn)
    profiler.assert_allclose(ref_program, rtol=1e-4, atol=1e-4)
    latency = profiler.do_bench(warmup=500)
    print(f"Latency: {latency} ms")
    print(f"TFlops: {total_flops / latency * 1e-9} TFlops")


if __name__ == "__main__":
    parser = argparse.ArgumentParser()
    parser.add_argument('--batch', type=int, default=132, help='batch size')
    parser.add_argument('--heads', type=int, default=128, help='q heads number')
    parser.add_argument('--kv_heads', type=int, default=1, help='kv heads number')
    parser.add_argument('--kv_ctx', type=int, default=8192, help='kv context length')
    parser.add_argument('--dim', type=int, default=512, help='head dim')
    parser.add_argument('--pe_dim', type=int, default=64, help='pe head dim')
    args = parser.parse_args()
    batch, heads, kv_heads, kv_ctx, dim, pe_dim = args.batch, args.heads, args.kv_heads, args.kv_ctx, args.dim, args.pe_dim
    main(batch, heads, kv_heads, kv_ctx, dim, pe_dim)
