{{def_kernel("Q", "K", "V", "LSE", "DELTA", "DO", "DQ", "DV", "KV_NUM_BLKS", "KV_IDX", "Q_NUM_BLKS", "Q_IDX", "FULL_KV_NUM_BLKS", "FULL_KV_IDX", "FULL_Q_NUM_BLKS", "FULL_Q_IDX")}}
    # Sub notation for this kernel:
    #
    # Q: Query, K: Key, V: Value
    # LSE: logsumexp (logsumexp is always stored in fp32 regardless of the input dtype)
    # DELTA: Precomputed sum(OUT*DO, axis=-1)
    # DO: Derivative of Output, DQ: Derivative of Query, DV: Derivative of Value
    # DK: Derivative of Key, is the written to via the store_output call due to some limitations with
    # inductor codegen
    # M: Number of queries, N: Number of keys/values
    # QK_HEAD_DIM: The dimension of the query and key embeddings
    # V_HEAD_DIM: The dimension of the value embeddings
    # z: Batch size, h: Number of heads, m: Number of queries or keys/values, d: Head dim
    # GQA_SHARED_HEADS: number of query heads sharing one kv head in GQA setups.
    # (Modifiable) Performance tuning options
    # BLOCK_M1: when calculating DK & DV, iterate over BLOCK_M1 across the seqlen dim of Q in each thread block.
    # BLOCK_N1: when calculating DK & DV, the thread block size across the seqlen dim of K/V.
    # BLOCK_M2: when calculating DQ, the thread block size across the seqlen dim of Q.
    # BLOCK_N2: when calculating DQ, iterate over BLOCK_N2 across the seqlen dim of K/V in each thread block.
    #
    # The following FULL_* and PARTIAL_* is defined in the block sparse mask grid, rather than the thread block grid.
    # KV_NUM_BLKS: The number of KV blocks (that may or may not require masking) for each query.
    # KV_IDX: The indices of KV blocks (that may or may not require masking) for each query.
    # Q_NUM_BLKS: The number of Q blocks (that may or may not require masking) for each query.
    # Q_IDX: The indices of Q blocks (that may or may not require masking) for each query.
    # FULL_KV_NUM_BLKS: The number of fully unmasked KV blocks (so we don't need masking) for each query.
    # FULL_KV_IDX: The indices of fully unmasked KV blocks (so we don't need masking) for each query.
    # FULL_Q_NUM_BLKS: The number of fully unmasked Q blocks (so we don't need masking) for each query.
    # FULL_Q_IDX: The indices of fully unmasked Q blocks (so we don't need masking) for each query.

    # The below are kernel options that can be applied for certain score_mods,
    # or involve a numerics vs. perf tradeoff
    # PRESCALE_QK: Whether to pre-scale QK by 1/sqrt(d) and change of base. Has
    # about 20% more numerical error, but slightly faster.

    # Define strides of inputs
    stride_qz, stride_qh, stride_qm, stride_qd = {{stride("Q")}}
    stride_kz, stride_kh, stride_kn, stride_kd = {{stride("K")}}
    stride_vz, stride_vh, stride_vn, stride_vd = {{stride("V")}}
    stride_doz, stride_doh, stride_dom, stride_dod = {{stride("DO")}}

    stride_dqz, stride_dqh, stride_dqm, stride_dqd = {{stride("DQ")}}
    stride_dvz, stride_dvh, stride_dvm, stride_dvd = {{stride("DV")}}

    ZQ = {{size("Q", 0)}}
    HQ = {{size("Q", 1)}}
    HKV = {{size("K", 1)}}
    Q_LEN = {{size("Q", 2)}}
    ZKV = {{size("K", 0)}}
    KV_LEN = {{size("K", 2)}}

    MATMUL_PRECISION = Q.dtype.element_ty

    pid = tl.program_id(0).to(INDEX_DTYPE)
    NUM_KV_BLOCKS = tl.cdiv(KV_LEN, BLOCK_N1)
    NUM_Q_BLOCKS = tl.cdiv(Q_LEN, BLOCK_M2)

    off_zq = tl.program_id(1).to(INDEX_DTYPE) # q batch idx
    off_hkv = tl.program_id(2).to(INDEX_DTYPE) # kv head idx
    off_zkv = off_zq % ZKV # kv batch idx

    SPARSE_Z = {{size("KV_NUM_BLKS", 0)}}
    SPARSE_HQ = {{size("KV_NUM_BLKS", 1)}}

    sparse_idx_z = off_zq % SPARSE_Z

    k_adj = (stride_kh * off_hkv + stride_kz * off_zkv).to(tl.int64)
    v_adj = (stride_vh * off_hkv + stride_vz * off_zkv).to(tl.int64)
    # first compute broadcasted dv of shape [Bq, Hkv, KV_LEN, V_HEAD_DIM]
    # then reduce to dv of shape [Bkv, Hkv, KV_LEN, V_HEAD_DIM]
    dv_adj = (stride_dvh * off_hkv + stride_dvz * off_zq).to(tl.int64)

    # offset K, V, DV pointers for batch/kv-head
    K += k_adj
    V += v_adj
    DV += dv_adj

    RCP_LN2 = 1.44269504
    offs_k = tl.arange(0, QK_HEAD_DIM_ROUNDED)
    offs_v = tl.arange(0, V_HEAD_DIM_ROUNDED)

    if pid >= NUM_KV_BLOCKS:
        off_pid = pid - NUM_KV_BLOCKS
        # THIS BLOCK DOES DQ
        SPARSE_Q_MULTIPLE = (SPARSE_Q_BLOCK_SIZE // BLOCK_M2)
        SPARSE_KV_MULTIPLE = (SPARSE_KV_BLOCK_SIZE // BLOCK_N2)
        off_hq2 = off_pid // NUM_Q_BLOCKS + off_hkv * GQA_SHARED_HEADS
        start_m2_block = off_pid % NUM_Q_BLOCKS
        off_pid_mask = start_m2_block // SPARSE_Q_MULTIPLE
        stride_kv_num_blks_h = {{stride("KV_NUM_BLKS", 1)}}
        stride_kv_idx_h = {{stride("KV_IDX", 1)}}
        stride_kv_idx_m = {{stride("KV_IDX", 2)}}

        sparse_idx_hq2 = off_hq2 % SPARSE_HQ
        sparse_hz_offset = sparse_idx_z * SPARSE_HQ + sparse_idx_hq2

        sparse_kv_num_blks_offset = sparse_hz_offset * stride_kv_num_blks_h + off_pid_mask
        sparse_kv_idx_offset = sparse_hz_offset * stride_kv_idx_h + off_pid_mask * stride_kv_idx_m  # noqa: B950

        # Offset Q, DQ, DO, DELTA & LSE. These inputs are offsetted by query heads.
        q_adj2 = (stride_qh * off_hq2 + stride_qz * off_zq).to(tl.int64)
        do_adj2 = (stride_doh * off_hq2 + stride_doz * off_zq).to(tl.int64)
        dq_adj2 = (stride_dqh * off_hq2 + stride_dqz * off_zq).to(tl.int64)
        off_chz2 = ((off_zq * HQ + off_hq2) * Q_LEN).to(tl.int64)

        Q2 = Q + q_adj2
        DO2 = DO + do_adj2
        # TODO: This does not work if DQ is not the same layout as Q (for example,
        # if Q is broadcasted)
        DQ2 = DQ + dq_adj2
        LSE2 = LSE + off_chz2
        DELTA2 = DELTA + off_chz2

        # dq = tl.zeros([BLOCK_M2, QK_HEAD_DIM], dtype=tl.float32)
        dq = tl.zeros([BLOCK_M2, QK_HEAD_DIM_ROUNDED], dtype=tl.float32)

        start_m2 = start_m2_block * BLOCK_M2
        offs_m2 = start_m2 + tl.arange(0, BLOCK_M2)

        # load Q and do: they stay in SRAM throughout the inner loop.
        q = load_checked_2d(Q2, offs_m2, offs_k, stride_qm, stride_qd, IS_DIVISIBLE, SAFE_HEAD_DIM, Q_LEN, QK_HEAD_DIM)
        do = load_checked_2d(DO2, offs_m2, offs_v, stride_dom, stride_dod, IS_DIVISIBLE, SAFE_HEAD_DIM, Q_LEN, V_HEAD_DIM)

        if PRESCALE_QK:
            q = (q * SM_SCALE * RCP_LN2).to(MATMUL_PRECISION)

        if IS_DIVISIBLE:
            Di = tl.load(DELTA2 + offs_m2)
            lse = tl.load(LSE2 + offs_m2)
        else:
            Di = tl.load(DELTA2 + offs_m2, mask=offs_m2 < Q_LEN)
            lse = tl.load(LSE2 + offs_m2, mask=offs_m2 < Q_LEN)
        lse = tl.where(lse == -float("inf"), 0.0, lse)
        lse = lse[:, None]

        # ~~~~~~~~~~~ fully unmasked blocks ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
        # KV_IDX and KV_NUM_BLKS are always contiguous.
        kv_indices = KV_IDX + sparse_kv_idx_offset
        kv_start = tl.load(kv_indices) * SPARSE_KV_BLOCK_SIZE # first kv block we're loading
        sparse_kv_num_blocks = tl.load(KV_NUM_BLKS + sparse_kv_num_blks_offset)

        offs_n2 = kv_start + tl.arange(0, BLOCK_N2)
        dq = bwd_dq_inner(
            {{gen_argdefs()}},
            K, V,
            dq, q, do, Di, lse,
            off_zq, off_hq2, offs_m2, offs_n2,
            stride_kn, stride_kd, stride_vn, stride_vd,
            kv_indices, sparse_kv_num_blocks,
            MATMUL_PRECISION,
            IS_FULL_BLOCKS=False,
        )

        if HAS_FULL_BLOCKS:
            # ~~~~~~~~~~~ partial unmasked blocks ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
            # FULL_KV_IDX and FULL_KV_NUM_BLKS are always contiguous.
            kv_indices = FULL_KV_IDX + sparse_kv_idx_offset
            kv_start = tl.load(kv_indices) * SPARSE_KV_BLOCK_SIZE # first kv block we're loading
            sparse_kv_num_blocks = tl.load(FULL_KV_NUM_BLKS + sparse_kv_num_blks_offset)

            offs_n2 = kv_start + tl.arange(0, BLOCK_N2)
            dq = bwd_dq_inner(
                {{gen_argdefs()}},
                K, V,
                dq, q, do, Di, lse,
                off_zq, off_hq2, offs_m2, offs_n2,
                stride_kn, stride_kd, stride_vn, stride_vd,
                kv_indices, sparse_kv_num_blocks,
                MATMUL_PRECISION,
                IS_FULL_BLOCKS=True,
            )

        # Write back dQ.
        dq_ptrs = DQ2 + offs_m2[:, None] * stride_dqm + offs_k[None, :] * stride_dqd
        dq *= SM_SCALE
        if IS_DIVISIBLE and SAFE_HEAD_DIM:
            tl.store(dq_ptrs, dq)
        else:
            tl.store(dq_ptrs, dq, mask=(offs_m2[:, None] < Q_LEN) & (offs_k[None, :] < QK_HEAD_DIM))
    else:
        # THIS BLOCK DOES DK & DV
        SPARSE_Q_MULTIPLE = (SPARSE_Q_BLOCK_SIZE // BLOCK_M1)
        SPARSE_KV_MULTIPLE = (SPARSE_KV_BLOCK_SIZE // BLOCK_N1)

        pid_mask = pid // SPARSE_KV_MULTIPLE

        stride_q_num_blks_h = {{stride("Q_NUM_BLKS", 1)}}
        stride_q_idx_h = {{stride("Q_IDX", 1)}}
        stride_q_idx_n = {{stride("Q_IDX", 2)}}


        dv = tl.zeros([BLOCK_N1, V_HEAD_DIM_ROUNDED], dtype=tl.float32)
        dk = tl.zeros([BLOCK_N1, QK_HEAD_DIM_ROUNDED], dtype=tl.float32)

        start_n1 = pid * BLOCK_N1
        offs_n1 = start_n1 + tl.arange(0, BLOCK_N1)

        # load K and V: they stay in SRAM throughout the inner loop.
        k = load_checked_2d(K, offs_n1, offs_k, stride_kn, stride_kd, IS_DIVISIBLE, SAFE_HEAD_DIM, KV_LEN, QK_HEAD_DIM)
        v = load_checked_2d(V, offs_n1, offs_v, stride_vn, stride_vd, IS_DIVISIBLE, SAFE_HEAD_DIM, KV_LEN, V_HEAD_DIM)

        if PRESCALE_QK:
            k = (k * SM_SCALE * RCP_LN2).to(MATMUL_PRECISION)

        for off_g in range(0, GQA_SHARED_HEADS):
            off_hq1 = off_hkv * GQA_SHARED_HEADS + off_g

            # Offset Q, DQ, DO, DELTA & LSE. These inputs are offsetted by query heads.
            q_adj1 = (stride_qh * off_hq1 + stride_qz * off_zq).to(tl.int64)
            do_adj1 = (stride_doh * off_hq1 + stride_doz * off_zq).to(tl.int64)
            dq_adj1 = (stride_dqh * off_hq1 + stride_dqz * off_zq).to(tl.int64)
            off_chz1 = ((off_zq * HQ + off_hq1) * Q_LEN).to(tl.int64)

            Q1 = Q + q_adj1
            DO1 = DO + do_adj1
            # TODO: This does not work if DQ is not the same layout as Q (for example,
            # if Q is broadcasted)
            LSE1 = LSE + off_chz1
            DELTA1 = DELTA + off_chz1

            sparse_idx_hq1 = off_hq1 % SPARSE_HQ
            sparse_hz_offset = sparse_idx_z * SPARSE_HQ + sparse_idx_hq1

            sparse_q_num_blks_offset = sparse_hz_offset * stride_q_num_blks_h + pid_mask
            sparse_q_idx_offset = sparse_hz_offset * stride_q_idx_h + pid_mask * stride_q_idx_n  # noqa: B950

            # ~~~~~~~~~~~~~~~ fully unmasked blocks ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
            # Q_IDX and Q_NUM_BLKS are always contiguous.
            q_indices = Q_IDX + sparse_q_idx_offset
            q_start = tl.load(q_indices) * SPARSE_Q_BLOCK_SIZE # first q block we're loading
            sparse_q_num_blocks = tl.load(Q_NUM_BLKS + sparse_q_num_blks_offset)

            offs_m1 = q_start + tl.arange(0, BLOCK_M1)
            dk, dv = bwd_dkdv_inner(
                {{gen_argdefs()}},
                Q1, DO1, DELTA1, LSE1,
                dk, dv, k, v,
                off_zq, off_hq1, offs_n1, offs_m1,
                stride_qm, stride_qd, stride_dom, stride_dod,
                q_indices, sparse_q_num_blocks,
                MATMUL_PRECISION,
                IS_FULL_BLOCKS=False,
            )


            if HAS_FULL_BLOCKS:
                # ~~~~~~~~~~~~~~~ fully unmasked blocks ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                # FULL_Q_IDX and FULL_Q_NUM_BLKS are always contiguous.
                q_indices = FULL_Q_IDX + sparse_q_idx_offset
                q_start = tl.load(q_indices) * SPARSE_Q_BLOCK_SIZE # first q block we're loading
                sparse_q_num_blocks = tl.load(FULL_Q_NUM_BLKS + sparse_q_num_blks_offset)

                offs_m1 = q_start + tl.arange(0, BLOCK_M1)
                dk, dv = bwd_dkdv_inner(
                    {{gen_argdefs()}},
                    Q1, DO1, DELTA1, LSE1,
                    dk, dv, k, v,
                    off_zq, off_hq1, offs_n1, offs_m1,
                    stride_qm, stride_qd, stride_dom, stride_dod,
                    q_indices, sparse_q_num_blocks,
                    MATMUL_PRECISION,
                    IS_FULL_BLOCKS=True,
                )

        # Write back dV and dK.
        dv_ptrs = DV + offs_n1[:, None] * stride_dvm + offs_v[None, :] * stride_dvd

        index_n = offs_n1[:, None]
        index_k = offs_k[None, :]
        index_v = offs_v[None, :]

        if IS_DIVISIBLE and SAFE_HEAD_DIM:
            tl.store(dv_ptrs, dv)
        else:
            tl.store(dv_ptrs, dv, mask=(index_n < KV_LEN) & (index_v < V_HEAD_DIM))

        dk *= SM_SCALE

        if SAFE_HEAD_DIM:
            mask = index_n < KV_LEN
        else:
            mask = (index_n < KV_LEN) & (index_k < QK_HEAD_DIM)

        # first compute broadcasted dk of shape [Bq, Hkv, KV_LEN, V_HEAD_DIM]
        # then reduce to dk of shape [Bkv, Hkv, KV_LEN, V_HEAD_DIM]
        tl.static_assert(dk.shape == [BLOCK_N1, QK_HEAD_DIM_ROUNDED])
        {{store_output(("off_zq", "off_hkv", "index_n", "index_k"), "dk", "mask", indent_width=8, val_shape=("BLOCK_N1", "QK_HEAD_DIM_ROUNDED"))}}

@triton.jit
def bwd_dq_inner(
    {{gen_argdefs()}},
    K, V,  # pointers
    dq, q, do, Di, lse,
    off_z, off_hq, offs_m2, offs_n2,
    stride_kn, stride_kd, stride_vn, stride_vd,
    kv_indices, sparse_kv_num_blocks,
    MATMUL_PRECISION,
    IS_FULL_BLOCKS,
):
    {{gen_defines() | indent_except_first(1) }}
    SPARSE_KV_MULTIPLE: tl.constexpr = (SPARSE_KV_BLOCK_SIZE // BLOCK_N2)
    RCP_LN2: tl.constexpr = 1.44269504
    Q_LEN = {{size("Q", 2)}}
    KV_LEN = {{size("K", 2)}}

    offs_k = tl.arange(0, QK_HEAD_DIM_ROUNDED)
    offs_v = tl.arange(0, V_HEAD_DIM_ROUNDED)

    kT_ptrs = K + offs_n2[None, :] * stride_kn + offs_k[:, None] * stride_kd
    vT_ptrs = V + offs_n2[None, :] * stride_vn + offs_v[:, None] * stride_vd
    # BLOCK_M2 must be a multiple of BLOCK_N2, otherwise the code wouldn't work.
    tl.static_assert(BLOCK_M2 % BLOCK_N2 == 0)

    hi = tl.minimum(sparse_kv_num_blocks * SPARSE_KV_MULTIPLE, tl.maximum(tl.cdiv(KV_LEN, BLOCK_N2), 1))

    for start_n in range(0, hi):
        dq = bwd_dq_block_mn(
            {{gen_argdefs()}},
            dq, q, kT_ptrs, vT_ptrs, do, Di, lse, Q_LEN, KV_LEN,
            off_z, off_hq, offs_m2, offs_n2, offs_k, offs_v,
            stride_kn, stride_kd, stride_vn, stride_vd,
            kv_indices, sparse_kv_num_blocks,
            MATMUL_PRECISION, RCP_LN2,
            IS_FULL_BLOCKS,
        )

        # Increment pointers.
        offset = get_offset_for_next_block(
            start_n, kv_indices, sparse_kv_num_blocks,
            SPARSE_KV_BLOCK_SIZE, SPARSE_KV_MULTIPLE, BLOCK_N2, BLOCKS_ARE_CONTIGUOUS
        )

        kT_ptrs += offset * stride_kn
        vT_ptrs += offset * stride_vn

        offs_n2 += offset

    return dq


@triton.jit
def bwd_dq_block_mn(
    {{gen_argdefs()}},
    dq, q, kT_ptrs, vT_ptrs, do, Di, lse, Q_LEN, KV_LEN,
    off_z, off_hq, offs_m2, offs_n2, offs_k, offs_v,
    stride_kn, stride_kd, stride_vn, stride_vd,
    kv_indices, sparse_kv_num_blocks,
    MATMUL_PRECISION, RCP_LN2,
    IS_FULL_BLOCKS,
):
    {{gen_defines() | indent_except_first(1)}}

    # NB reversed order to since K is transposed
    kT = load_checked_2d(kT_ptrs, offs_k, offs_n2, None, None, SAFE_HEAD_DIM, IS_DIVISIBLE, QK_HEAD_DIM, KV_LEN)
    qk = tl.dot(q, kT, input_precision=FLOAT32_PRECISION)
    if not PRESCALE_QK:
        qk *= SM_SCALE
    # ~~~~~~~~~~~~~~~~~~~ Apply score modification  ~~~~~~~~~~~~~~~~~~~
    pre_mod_scores = qk
    n = get_bounded_indices(offs_n2[None, :], KV_LEN if not IS_DIVISIBLE else None)
    # The boundary check is done for the outer loop, but here it's possible since we're iterating across N dim
    # that the M reads out of bounds for the PIDS spanning the Q_LEN boundary
    m = get_bounded_indices(offs_m2[:, None], Q_LEN if not IS_DIVISIBLE else None)

    {{ modification(
        subgraph_number=0,
        output_name="post_mod_scores",
        score="qk",
        b="off_z",
        h="off_hq",
        m="m",
        n="n",
        out="qk"
    ) | indent_except_first(1) }}


    {# Note: Selective masking DQ
    We load elements beyond KV_LEN w/ zero, some score mods may convert this elements to NaN
    Example: lambda x, *_: 1 / score, this NaN would propagate regardless of other masking
    We only need to do this on the m1 dim since these elements take part in the final reduction
    for DQ #}
    if not IS_DIVISIBLE:
        post_mod_scores = tl.where(offs_n2[None, :] < KV_LEN, post_mod_scores, float("-inf"))

    if not IS_FULL_BLOCKS:
        {{ modification(
            subgraph_number=2,
            output_name="mask_mod_output",
            score="qk",
            b="off_z",
            h="off_hq",
            m="m",
            n="n",
        ) | indent_except_first(2) }}

        # apply mask for partial masked block
        post_mod_scores = tl.where(mask_mod_output, post_mod_scores, float("-inf"))
    # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    if not PRESCALE_QK:
        post_mod_scores *= RCP_LN2
    p = tl.math.exp2(post_mod_scores - lse)
    # Compute dP and dS.
    # NB reversed order to since V is transposed
    vT = load_checked_2d(vT_ptrs, offs_v, offs_n2, None, None, SAFE_HEAD_DIM, IS_DIVISIBLE, V_HEAD_DIM, KV_LEN)

    dp = tl.dot(do, vT, input_precision=FLOAT32_PRECISION)
    ds = p * (dp - Di[:, None])
    # ~~~~~~~~~~~~~~~~~~~ Apply joint modification  ~~~~~~~~~~~~~~~~~~~
    {{ modification(
        subgraph_number=1,
        output_name = "grad_scores",
        score="pre_mod_scores",
        b="off_z",
        h="off_hq",
        m="m",
        n="n",
        grad_score_mod="ds"
    ) | indent_except_first(1) }}
    {# See Note Selective masking DQ #}
    if not IS_DIVISIBLE:
        grad_scores = tl.where(offs_n2[None, :] < KV_LEN, grad_scores, 0.0)

    # ~~~~~~~~~~~~~~~~~~~ Apply other buffer grad writes ~~~~~~~~~~~~~
    if WRITE_DQ:
        scatter_mask = (offs_m2[:, None] < Q_LEN ) & (offs_n2[None, :] < KV_LEN)
        {{ modification(
            subgraph_number=3,
            output_name=None,
            mask="scatter_mask",
            score="pre_mod_scores",
            b="off_z",
            h="off_hq",
            m="m",
            n="n",
            grad_score_mod="ds"
        ) | indent_except_first(2) }}
    # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    ds = grad_scores

    if not IS_FULL_BLOCKS:
        # (grads) apply mask for partially unmasked block
        ds = tl.where(mask_mod_output, ds, 0.0)
    # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    ds = ds.to(MATMUL_PRECISION)
    # Compute dQ.
    dq += tl.dot(ds, tl.trans(kT), input_precision=FLOAT32_PRECISION)

    return dq


@triton.jit
def bwd_dkdv_inner(
    {{gen_argdefs()}},
    Q, DO, DELTA, LSE, # pointers
    dk, dv, k, v,
    off_z, off_hq, offs_n1, offs_m1,
    stride_qm, stride_qd, stride_dom, stride_dod,
    q_indices, sparse_q_num_blocks,
    MATMUL_PRECISION,
    IS_FULL_BLOCKS,
):
    {{gen_defines() | indent_except_first(1) }}
    SPARSE_Q_MULTIPLE: tl.constexpr = (SPARSE_Q_BLOCK_SIZE // BLOCK_M1)
    RCP_LN2: tl.constexpr = 1.44269504
    Q_LEN = {{size("Q", 2)}}
    KV_LEN = {{size("K", 2)}}

    offs_k = tl.arange(0, QK_HEAD_DIM_ROUNDED)
    offs_v = tl.arange(0, V_HEAD_DIM_ROUNDED)

    qT_ptrs = Q + offs_m1[None, :] * stride_qm + offs_k[:, None] * stride_qd
    do_ptrs = DO + offs_m1[:, None] * stride_dom + offs_v[None, :] * stride_dod
    # BLOCK_N1 must be a multiple of BLOCK_M1, otherwise the code wouldn't work.
    tl.static_assert(BLOCK_N1 % BLOCK_M1 == 0)

    # The minimum is needed to handle the case where we run with a super large
    # SPARSE_BLOCK_SIZE (i.e. no block-mask!)
    hi = tl.minimum(sparse_q_num_blocks * SPARSE_Q_MULTIPLE, tl.maximum(tl.cdiv(Q_LEN, BLOCK_M1), 1))

    for start_m in range(0, hi):
        dk, dv = bwd_dkdv_block_mn(
            {{gen_argdefs()}},
            dk, dv, qT_ptrs, k, v, do_ptrs, DELTA, LSE, Q_LEN, KV_LEN,
            off_z, off_hq, offs_n1, offs_m1, offs_k, offs_v,
            stride_qm, stride_qd, stride_dom, stride_dod,
            q_indices, sparse_q_num_blocks,
            MATMUL_PRECISION, RCP_LN2,
            IS_FULL_BLOCKS,
        )
        # Increment pointers.
        offset = get_offset_for_next_block(
            start_m, q_indices, sparse_q_num_blocks,
            SPARSE_Q_BLOCK_SIZE, SPARSE_Q_MULTIPLE, BLOCK_M1, BLOCKS_ARE_CONTIGUOUS
        )

        qT_ptrs += offset * stride_qm
        do_ptrs += offset * stride_dom
        offs_m1 += offset

    return dk, dv


@triton.jit
def bwd_dkdv_block_mn(
    {{gen_argdefs()}},
    dk, dv, qT_ptrs, k, v, do_ptrs, DELTA, LSE, Q_LEN, KV_LEN,
    off_z, off_hq, offs_n1, offs_m1, offs_k, offs_v,
    stride_qm, stride_qd, stride_dom, stride_dod,
    q_indices, sparse_q_num_blocks,
    MATMUL_PRECISION, RCP_LN2,
    IS_FULL_BLOCKS,
):
    {{gen_defines() | indent_except_first(1) }}

    # NB reversed order since Q is transposed
    qT = load_checked_2d(qT_ptrs, offs_k, offs_m1, None, None, SAFE_HEAD_DIM, IS_DIVISIBLE, QK_HEAD_DIM, Q_LEN)
    # Load LSE before computing qk to reduce pipeline stall.
    if IS_DIVISIBLE:
        lse = tl.load(LSE + offs_m1)
    else:
        lse = tl.load(LSE + offs_m1, mask=offs_m1 < Q_LEN)
    lse = tl.where(lse == -float("inf"), 0.0, lse)
    qkT = tl.dot(k, qT, input_precision=FLOAT32_PRECISION)
    if not PRESCALE_QK:
        qkT *= SM_SCALE
    # ~~~~~~~~~~~~~~~~~~~ Apply score modification  ~~~~~~~~~~~~~~~~~~~
    m = get_bounded_indices(offs_m1[None, :], Q_LEN if not IS_DIVISIBLE else None)
    # The boundary check is done for the outer loop, but here it's possible since we're iterating across M dim
    # that the n reads out of bounds for the PIDS spanning the KV_LEN boundary
    n = get_bounded_indices(offs_n1[:, None], KV_LEN if not IS_DIVISIBLE else None)

    pre_mod_scores = qkT
    {{ modification(
        subgraph_number=0,
        output_name="post_mod_scores",
        score="qkT",
        b="off_z",
        h="off_hq",
        m="m",
        n="n",
        out="qkT"
    ) | indent_except_first(1) }}

    {# Note: Selective masking DK/DV
    We load elements beyond Q_LEN w/ zero, some score mods may convert this elements to NaN
    Example: lambda x, *_: 1 / score, this NaN would propagate regardless of other masking
    We only need to do this on the m1 dim since these elements take part in the final reduction
    for DK/DV #}
    if not IS_DIVISIBLE:
        post_mod_scores = tl.where(offs_m1[None, :] < Q_LEN, post_mod_scores, float("-inf"))

    if not IS_FULL_BLOCKS:
        {{ modification(
            subgraph_number=2,
            output_name="mask_mod_output",
            b="off_z",
            h="off_hq",
            m="m",
            n="n",
        ) | indent_except_first(2) }}
        # (grads) apply mask for fully masked block
        post_mod_scores = tl.where(mask_mod_output, post_mod_scores, float("-inf"))
    # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    if not PRESCALE_QK:
        post_mod_scores *= RCP_LN2
    pT = tl.math.exp2(post_mod_scores - lse[None, :])
    do = load_checked_2d(do_ptrs, offs_m1, offs_v, None, None, IS_DIVISIBLE, SAFE_HEAD_DIM, Q_LEN, V_HEAD_DIM)
    # Compute dV.
    ppT = pT
    dv += tl.dot(ppT.to(MATMUL_PRECISION), do, input_precision=FLOAT32_PRECISION)
    if IS_DIVISIBLE:
        Di = tl.load(DELTA + offs_m1)
    else:
        Di = tl.load(DELTA + offs_m1, mask=offs_m1 < Q_LEN)
    # Compute dP and dS.
    dpT = tl.dot(v, tl.trans(do), input_precision=FLOAT32_PRECISION)
    dsT = pT * (dpT - Di[None, :])
    # ~~~~~~~~~~~~~~~~~~~ Apply joint modification  ~~~~~~~~~~~~~~~~~~~
    {{ modification(
        subgraph_number=1,
        output_name = "grad_scores",
        score="pre_mod_scores",
        b="off_z",
        h="off_hq",
        m="m",
        n="n",
        grad_score_mod="dsT"
    ) | indent_except_first(1) }}

    {# See Note: Selective masking DK/DV#}
    if not IS_DIVISIBLE:
        grad_scores = tl.where(offs_m1[None, :] < Q_LEN, grad_scores, 0.0)

    # ~~~~~~~~~~~~~~~~~~~ Apply other buffer grad writes ~~~~~~~~~~~~~
    if not WRITE_DQ:
        idx_b = off_z
        idx_h = off_hq
        idx_m = m
        idx_n = n
        scatter_mask = (offs_m1[None, :] < Q_LEN) & (offs_n1[:, None] < KV_LEN)
        {{ modification(
            subgraph_number=3,
            output_name=None,
            mask="scatter_mask",
            score="pre_mod_scores",
            b="idx_b",
            h="idx_h",
            m="idx_m",
            n="idx_n",
            grad_score_mod="dsT"
        ) | indent_except_first(2) }}
    # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    dsT = grad_scores
    if not IS_FULL_BLOCKS:
        # (grads) apply mask for partially unmasked block
        dsT = tl.where(mask_mod_output, dsT, 0.0)
    # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    dk += tl.dot(dsT.to(MATMUL_PRECISION), tl.trans(qT), input_precision=FLOAT32_PRECISION)

    return dk, dv
