submission 411478

from __future__ import annotations

import os
from typing import List

import torch
from torch.utils.cpp_extension import load_inline











_FORCE_NO_GROUPED = False
_FORCE_BN64 = False
_FORCE_RAW_SF = False
_USE_BN128_LD16 = False

_EXT_READY = False
_OPS_READY = False

_GEMM = None
_GEMM_GROUPED = None

_SCRATCH_A: dict = {}
_SCRATCH_A_G: dict = {}


def _load_ext() -> None:
    global _EXT_READY, _OPS_READY, _GEMM, _GEMM_GROUPED
    if _EXT_READY:
        return

    cuda_src = r"""
#include <cuda.h>
#include <cudaTypedefs.h>
#include <cuda_runtime.h>
#include <cuda_fp16.h>

#include <torch/extension.h>
#include <torch/library.h>
#include <ATen/ATen.h>

#include <cstdint>
#include <vector>
#include <array>

// BN128 epilogue 选择：0=2×.x8（更低寄存器），1=.x16（更少指令）
#ifndef USE_BN128_LD16
#define USE_BN128_LD16 0
#endif

// 默认关闭检查，极致压缩 host 热路径分支
#ifndef NVFP4_GGEMM_CHECK
#define NVFP4_GGEMM_CHECK 0
#endif

#if NVFP4_GGEMM_CHECK
#define GG_CHECK(x, msg) TORCH_CHECK((x), msg)
#else
#define GG_CHECK(x, msg) ((void)0)
#endif

constexpr int WARP_SIZE = 32;
constexpr int MMA_K = 64;

constexpr uint64_t EVICT_FIRST = 0x12F0000000000000ULL;
constexpr uint64_t EVICT_LAST  = 0x14F0000000000000ULL;

__device__ __forceinline__ constexpr uint64_t desc_encode(uint64_t x) { return (x & 0x3FFFFULL) >> 4ULL; }

__device__ __forceinline__ uint32_t elect_sync() {
  uint32_t pred = 0;
  asm volatile(
    "{\n\t"
    ".reg .pred %%px;\n\t"
    "elect.sync _|%%px, %1;\n\t"
    "@%%px mov.s32 %0, 1;\n\t"
    "}"
    : "+r"(pred)
    : "r"(0xFFFFFFFF)
  );
  return pred;
}

__device__ __forceinline__ void mbarrier_init(int mbar_addr, int count) {
  asm volatile("mbarrier.init.shared::cta.b64 [%0], %1;" :: "r"(mbar_addr), "r"(count));
}

__device__ __forceinline__ void mbarrier_wait(int mbar_addr, int phase) {
  uint32_t ticks = 0x989680;
  asm volatile(
    "{\n\t"
    ".reg .pred P1;\n\t"
    "LAB_WAIT:\n\t"
    "mbarrier.try_wait.parity.acquire.cta.shared::cta.b64 P1, [%0], %1, %2;\n\t"
    "@P1 bra.uni DONE;\n\t"
    "bra.uni LAB_WAIT;\n\t"
    "DONE:\n\t"
    "}"
    :: "r"(mbar_addr), "r"(phase), "r"(ticks)
  );
}

__device__ __forceinline__ void tma_gmem2smem(int dst, const void *src, int size, int mbar_addr, uint64_t cache_policy) {
  asm volatile(
    "cp.async.bulk.shared::cta.global.mbarrier::complete_tx::bytes.L2::cache_hint "
    "[%0], [%1], %2, [%3], %4;"
    :: "r"(dst), "l"(src), "r"(size), "r"(mbar_addr), "l"(cache_policy)
  );
}

__device__ __forceinline__ void tma_3d_gmem2smem(int dst, const void *tmap_ptr, int x, int y, int z, int mbar_addr, uint64_t cache_policy) {
  asm volatile(
    "cp.async.bulk.tensor.3d.shared::cta.global.mbarrier::complete_tx::bytes.cta_group::1.L2::cache_hint "
    "[%0], [%1, {%2, %3, %4}], [%5], %6;"
    :: "r"(dst), "l"(tmap_ptr), "r"(x), "r"(y), "r"(z), "r"(mbar_addr), "l"(cache_policy)
    : "memory"
  );
}

__device__ __forceinline__ void tcgen05_cp_nvfp4(int taddr, uint64_t s_desc) {
  asm volatile("tcgen05.cp.cta_group::1.32x128b.warpx4 [%0], %1;" :: "r"(taddr), "l"(s_desc));
}

__device__ __forceinline__ void tcgen05_mma_nvfp4(
  uint64_t a_desc,
  uint64_t b_desc,
  uint32_t i_desc,
  int scale_A_tmem,
  int scale_B_tmem,
  int enable_input_d
) {
  const int d_tmem = 0;
  asm volatile(
    "{\n\t"
    ".reg .pred p;\n\t"
    "setp.ne.b32 p, %6, 0;\n\t"
    "tcgen05.mma.cta_group::1.kind::mxf4nvf4.block_scale.block16 [%0], %1, %2, %3, [%4], [%5], p;\n\t"
    "}"
    :: "r"(d_tmem), "l"(a_desc), "l"(b_desc), "r"(i_desc),
       "r"(scale_A_tmem), "r"(scale_B_tmem), "r"(enable_input_d)
  );
}

struct SHAPE {
  static constexpr char _16x256b[] = ".16x256b";
};
struct NUM {
  static constexpr char x8[]  = ".x8";
  static constexpr char x16[] = ".x16";
};

template <const char *SHAPE_V, const char *NUM_V>
__device__ __forceinline__ void tcgen05_ld_32regs(float *tmp, int row, int col) {
  asm volatile(
    "tcgen05.ld.sync.aligned%33%34.b32 "
    "{ %0,  %1,  %2,  %3,  %4,  %5,  %6,  %7, "
    "  %8,  %9, %10, %11, %12, %13, %14, %15, "
    " %16, %17, %18, %19, %20, %21, %22, %23, "
    " %24, %25, %26, %27, %28, %29, %30, %31}, [%32];"
    : "=f"(tmp[ 0]), "=f"(tmp[ 1]), "=f"(tmp[ 2]), "=f"(tmp[ 3]), "=f"(tmp[ 4]), "=f"(tmp[ 5]), "=f"(tmp[ 6]), "=f"(tmp[ 7]),
      "=f"(tmp[ 8]), "=f"(tmp[ 9]), "=f"(tmp[10]), "=f"(tmp[11]), "=f"(tmp[12]), "=f"(tmp[13]), "=f"(tmp[14]), "=f"(tmp[15]),
      "=f"(tmp[16]), "=f"(tmp[17]), "=f"(tmp[18]), "=f"(tmp[19]), "=f"(tmp[20]), "=f"(tmp[21]), "=f"(tmp[22]), "=f"(tmp[23]),
      "=f"(tmp[24]), "=f"(tmp[25]), "=f"(tmp[26]), "=f"(tmp[27]), "=f"(tmp[28]), "=f"(tmp[29]), "=f"(tmp[30]), "=f"(tmp[31])
    : "r"((row << 16) | col), "C"(SHAPE_V), "C"(NUM_V));
}

template <const char *SHAPE_V, const char *NUM_V>
__device__ __forceinline__ void tcgen05_ld_64regs(float *tmp, int row, int col) {
  asm volatile(
    "tcgen05.ld.sync.aligned%65%66.b32 "
    "{ %0,  %1,  %2,  %3,  %4,  %5,  %6,  %7, "
    "  %8,  %9, %10, %11, %12, %13, %14, %15, "
    " %16, %17, %18, %19, %20, %21, %22, %23, "
    " %24, %25, %26, %27, %28, %29, %30, %31, "
    " %32, %33, %34, %35, %36, %37, %38, %39, "
    " %40, %41, %42, %43, %44, %45, %46, %47, "
    " %48, %49, %50, %51, %52, %53, %54, %55, "
    " %56, %57, %58, %59, %60, %61, %62, %63}, [%64];"
    : "=f"(tmp[ 0]), "=f"(tmp[ 1]), "=f"(tmp[ 2]), "=f"(tmp[ 3]), "=f"(tmp[ 4]), "=f"(tmp[ 5]), "=f"(tmp[ 6]), "=f"(tmp[ 7]),
      "=f"(tmp[ 8]), "=f"(tmp[ 9]), "=f"(tmp[10]), "=f"(tmp[11]), "=f"(tmp[12]), "=f"(tmp[13]), "=f"(tmp[14]), "=f"(tmp[15]),
      "=f"(tmp[16]), "=f"(tmp[17]), "=f"(tmp[18]), "=f"(tmp[19]), "=f"(tmp[20]), "=f"(tmp[21]), "=f"(tmp[22]), "=f"(tmp[23]),
      "=f"(tmp[24]), "=f"(tmp[25]), "=f"(tmp[26]), "=f"(tmp[27]), "=f"(tmp[28]), "=f"(tmp[29]), "=f"(tmp[30]), "=f"(tmp[31]),
      "=f"(tmp[32]), "=f"(tmp[33]), "=f"(tmp[34]), "=f"(tmp[35]), "=f"(tmp[36]), "=f"(tmp[37]), "=f"(tmp[38]), "=f"(tmp[39]),
      "=f"(tmp[40]), "=f"(tmp[41]), "=f"(tmp[42]), "=f"(tmp[43]), "=f"(tmp[44]), "=f"(tmp[45]), "=f"(tmp[46]), "=f"(tmp[47]),
      "=f"(tmp[48]), "=f"(tmp[49]), "=f"(tmp[50]), "=f"(tmp[51]), "=f"(tmp[52]), "=f"(tmp[53]), "=f"(tmp[54]), "=f"(tmp[55]),
      "=f"(tmp[56]), "=f"(tmp[57]), "=f"(tmp[58]), "=f"(tmp[59]), "=f"(tmp[60]), "=f"(tmp[61]), "=f"(tmp[62]), "=f"(tmp[63])
    : "r"((row << 16) | col), "C"(SHAPE_V), "C"(NUM_V));
}

__device__ __forceinline__ void tcgen05_ld_16x256bx8(float *tmp, int row, int col) {
  tcgen05_ld_32regs<SHAPE::_16x256b, NUM::x8>(tmp, row, col);
}
__device__ __forceinline__ void tcgen05_ld_16x256bx16(float *tmp, int row, int col) {
  tcgen05_ld_64regs<SHAPE::_16x256b, NUM::x16>(tmp, row, col);
}

static __forceinline__ void check_cu(CUresult err) {
  if (err == CUDA_SUCCESS) return;
  const char *msg = "unknown";
  cuGetErrorString(err, &msg);
  TORCH_CHECK(false, msg);
}

struct TmapKey {
  uint64_t ptr;
  uint64_t global_height;
  uint64_t global_width;
  uint32_t shared_height;
  uint32_t shared_width;
  int32_t dev;
};

static __forceinline__ bool tmap_key_eq(const TmapKey &a, const TmapKey &b) {
  return a.ptr == b.ptr
      && a.global_height == b.global_height
      && a.global_width == b.global_width
      && a.shared_height == b.shared_height
      && a.shared_width == b.shared_width
      && a.dev == b.dev;
}

template <int CAP>
struct TmapCache {
  std::array<TmapKey, CAP> keys;
  std::array<CUtensorMap, CAP> vals;
  std::array<uint8_t, CAP> used;
  int head;

  TmapCache() : used{}, head(0) {}

  bool lookup(const TmapKey &k, CUtensorMap *out) {
    #pragma unroll
    for (int i = 0; i < CAP; i++) {
      if (used[(size_t)i] && tmap_key_eq(keys[(size_t)i], k)) {
        *out = vals[(size_t)i];
        return true;
      }
    }
    return false;
  }

  void insert(const TmapKey &k, const CUtensorMap &v) {
    keys[(size_t)head] = k;
    vals[(size_t)head] = v;
    used[(size_t)head] = 1;
    head++;
    if (head >= CAP) head = 0;
  }
};

static TmapCache<64> g_tmap_cache;

static __forceinline__ void init_AB_tmap(
  CUtensorMap *tmap,
  const char *ptr,
  uint64_t global_height,
  uint64_t global_width,
  uint32_t shared_height,
  uint32_t shared_width
) {
  int dev = 0;
  cudaGetDevice(&dev);
  TmapKey key;
  key.ptr = (uint64_t)ptr;
  key.global_height = global_height;
  key.global_width = global_width;
  key.shared_height = shared_height;
  key.shared_width = shared_width;
  key.dev = (int32_t)dev;

  if (g_tmap_cache.lookup(key, tmap)) return;

  constexpr uint32_t rank = 3;
  uint64_t globalDim[rank]       = {256, global_height, global_width / 256};
  uint64_t globalStrides[rank-1] = {global_width / 2, 128};
  uint32_t boxDim[rank]          = {256, shared_height, shared_width / 256};
  uint32_t elementStrides[rank]  = {1, 1, 1};

  auto err = cuTensorMapEncodeTiled(
    tmap,
    CUtensorMapDataType::CU_TENSOR_MAP_DATA_TYPE_16U4_ALIGN8B,
    rank,
    (void *)ptr,
    globalDim,
    globalStrides,
    boxDim,
    elementStrides,
    CUtensorMapInterleave::CU_TENSOR_MAP_INTERLEAVE_NONE,
    CUtensorMapSwizzle::CU_TENSOR_MAP_SWIZZLE_128B,
    CUtensorMapL2promotion::CU_TENSOR_MAP_L2_PROMOTION_NONE,
    CUtensorMapFloatOOBfill::CU_TENSOR_MAP_FLOAT_OOB_FILL_NONE
  );
  check_cu(err);
  g_tmap_cache.insert(key, *tmap);
}

// grouped 元数据：一次性搬到 device，kernel 只读 descs[gid]
struct __align__(16) GroupDesc {
  CUtensorMap A_tmap;
  CUtensorMap B_tmap;
  uint64_t SFA_ptr;
  uint64_t SFB_ptr;
  uint64_t C_ptr;
  int M;
  int N;
  int K;
};

__device__ __forceinline__ int active_threads_128(int M, int off_m) {
  int rem = M - off_m;
  if (rem <= 0) return 0;
  int thr = (rem + 31) & ~31;
  if (thr > 128) thr = 128;
  return thr;
}

template <int BLOCK_N, int NUM_STAGES, bool FULL_N>
__global__ __launch_bounds__(128 + 2 * WARP_SIZE)
void kernel(
  const __grid_constant__ CUtensorMap A_tmap,
  const __grid_constant__ CUtensorMap B_tmap,
  const char *SFA_ptr,
  const char *SFB_ptr,
  half *C_ptr,
  int M, int N, int K
) {
  constexpr int BLOCK_M = 128;
  constexpr int BLOCK_K = 256;

  const int tid = (int)threadIdx.x;
  const int bid_n = (int)blockIdx.x;
  const int bid_m = (int)blockIdx.y;

  const int lane_id = tid & (WARP_SIZE - 1);
  const int warp_id = tid >> 5;

  const int off_m = bid_m * BLOCK_M;
  const int off_n = bid_n * BLOCK_N;

  constexpr int NUM_WARPS = BLOCK_M / WARP_SIZE + 2;

  extern __shared__ __align__(1024) char smem_ptr[];
  const int smem = (int)__cvta_generic_to_shared(smem_ptr);
  constexpr int A_size   = BLOCK_M * BLOCK_K / 2;
  constexpr int B_size   = BLOCK_N * BLOCK_K / 2;
  constexpr int SFA_size = 128 * BLOCK_K / 16;
  constexpr int SFB_size = 128 * BLOCK_K / 16;
  constexpr int STAGE_SIZE = A_size + B_size + SFA_size + SFB_size;

  #pragma nv_diag_suppress static_var_with_dynamic_init
  __shared__ int64_t mbars[NUM_STAGES * 2 + 1];
  const int tma_mbar_addr = (int)__cvta_generic_to_shared(mbars);
  const int mma_mbar_addr = tma_mbar_addr + NUM_STAGES * 8;
  const int mainloop_mbar_addr = mma_mbar_addr + NUM_STAGES * 8;

  constexpr int SFA_tmem = BLOCK_N;
  constexpr int SFB_tmem = SFA_tmem + 4 * (BLOCK_K / MMA_K);

  if (warp_id == 0 && elect_sync()) {
    #pragma unroll
    for (int i = 0; i < NUM_STAGES * 2 + 1; i++) mbarrier_init(tma_mbar_addr + i * 8, 1);
    asm volatile("fence.mbarrier_init.release.cluster;");
  } else if (warp_id == 1) {
    asm volatile("tcgen05.alloc.cta_group::1.sync.aligned.shared::cta.b32 [%0], %1;" :: "r"(smem), "r"(BLOCK_N * 2));
  }
  __syncthreads();

  const int num_iters = K / BLOCK_K;

  if (warp_id == NUM_WARPS - 2 && elect_sync()) {
    uint64_t cache_A, cache_B;
    const int grid_m = (M + 127) >> 7;
    const int grid_n = (N + BLOCK_N - 1) / BLOCK_N;
    if (grid_n >= grid_m) { cache_A = EVICT_LAST; cache_B = EVICT_FIRST; }
    else { cache_A = EVICT_FIRST; cache_B = EVICT_LAST; }

    auto issue_tma = [&](int iter_k, int stage_id) {
      const int mbar_addr = tma_mbar_addr + stage_id * 8;
      const int A_smem = smem + stage_id * STAGE_SIZE;
      const int B_smem = A_smem + A_size;
      const int SFA_smem = B_smem + B_size;
      const int SFB_smem = SFA_smem + SFA_size;

      const int off_k = iter_k * BLOCK_K;
      tma_3d_gmem2smem(A_smem, &A_tmap, 0, off_m, off_k / 256, mbar_addr, cache_A);
      tma_3d_gmem2smem(B_smem, &B_tmap, 0, off_n, off_k / 256, mbar_addr, cache_B);

      const int rest_k = K / 16 / 4;
      const char *SFA_src = SFA_ptr + ((off_m / 128) * rest_k + off_k / (16 * 4)) * 512;
      const char *SFB_src = SFB_ptr + ((off_n / 128) * rest_k + off_k / (16 * 4)) * 512;
      tma_gmem2smem(SFA_smem, SFA_src, SFA_size, mbar_addr, cache_A);
      tma_gmem2smem(SFB_smem, SFB_src, SFB_size, mbar_addr, cache_B);

      asm volatile("mbarrier.arrive.expect_tx.release.cta.shared::cta.b64 _, [%0], %1;"
                   :: "r"(mbar_addr), "r"(STAGE_SIZE) : "memory");
    };

    const int init_stage = (num_iters < NUM_STAGES) ? num_iters : NUM_STAGES;
    for (int iter_k = 0; iter_k < init_stage; iter_k++) issue_tma(iter_k, iter_k);

    for (int iter_k = NUM_STAGES; iter_k < num_iters; iter_k++) {
      const int stage_id = iter_k % NUM_STAGES;
      const int mma_phase = (iter_k / NUM_STAGES - 1) & 1;
      mbarrier_wait(mma_mbar_addr + stage_id * 8, mma_phase);
      issue_tma(iter_k, stage_id);
    }
  } else if (warp_id == NUM_WARPS - 1 && elect_sync()) {
    constexpr int MMA_N = BLOCK_N;
    constexpr int MMA_M = 128;
    constexpr uint32_t i_desc = (1U << 7U)
                              | (1U << 10U)
                              | ((uint32_t)MMA_N >> 3U << 17U)
                              | ((uint32_t)MMA_M >> 7U << 27U);

    auto make_desc_AB = [] __device__ (int addr) -> uint64_t {
      const int SBO = 8 * 128;
      return desc_encode((uint64_t)addr) | (desc_encode((uint64_t)SBO) << 32ULL) | (1ULL << 46ULL) | (2ULL << 61ULL);
    };
    auto make_desc_SF = [] __device__ (int addr) -> uint64_t {
      const int SBO = 8 * 16;
      return desc_encode((uint64_t)addr) | (desc_encode((uint64_t)SBO) << 32ULL) | (1ULL << 46ULL);
    };

    for (int iter_k = 0; iter_k < num_iters; iter_k++) {
      const int stage_id = iter_k % NUM_STAGES;
      const int tma_phase = (iter_k / NUM_STAGES) & 1;
      mbarrier_wait(tma_mbar_addr + stage_id * 8, tma_phase);

      const int A_smem = smem + stage_id * STAGE_SIZE;
      const int B_smem = A_smem + A_size;
      const int SFA_smem = B_smem + B_size;
      const int SFB_smem = SFA_smem + SFA_size;

      const uint64_t SFA_desc = make_desc_SF(0) + ((uint64_t)SFA_smem >> 4ULL);
      const uint64_t SFB_desc = make_desc_SF(0) + ((uint64_t)SFB_smem >> 4ULL);

      #pragma unroll
      for (int k = 0; k < BLOCK_K / MMA_K; k++) {
        uint64_t sfa_desc = SFA_desc + (uint64_t)k * (512ULL >> 4ULL);
        uint64_t sfb_desc = SFB_desc + (uint64_t)k * (512ULL >> 4ULL);
        tcgen05_cp_nvfp4(SFA_tmem + k * 4, sfa_desc);
        tcgen05_cp_nvfp4(SFB_tmem + k * 4, sfb_desc);
      }

      #pragma unroll
      for (int k1 = 0; k1 < BLOCK_K / 256; k1++) {
        #pragma unroll
        for (int k2 = 0; k2 < 256 / MMA_K; k2++) {
          uint64_t a_desc = make_desc_AB(A_smem + k1 * BLOCK_M * 128 + k2 * 32);
          uint64_t b_desc = make_desc_AB(B_smem + k1 * BLOCK_N * 128 + k2 * 32);

          const int k_sf = k1 * 4 + k2;
          const int scale_A_tmem = SFA_tmem + k_sf * 4;
          const int scale_B_tmem = SFB_tmem + k_sf * 4 + (bid_n % (128 / BLOCK_N)) * (BLOCK_N / 32);
          const int enable_input_d = (k1 == 0 && k2 == 0) ? iter_k : 1;
          tcgen05_mma_nvfp4(a_desc, b_desc, i_desc, scale_A_tmem, scale_B_tmem, enable_input_d);
        }
      }

      asm volatile("tcgen05.commit.cta_group::1.mbarrier::arrive::one.shared::cluster.b64 [%0];"
                   :: "r"(mma_mbar_addr + stage_id * 8) : "memory");
    }

    asm volatile("tcgen05.commit.cta_group::1.mbarrier::arrive::one.shared::cluster.b64 [%0];"
                 :: "r"(mainloop_mbar_addr) : "memory");
  } else if (tid < BLOCK_M) {
    const int thr = active_threads_128(M, off_m);
    if (tid >= thr) return;

    mbarrier_wait(mainloop_mbar_addr, 0);
    asm volatile("tcgen05.fence::after_thread_sync;");

    if constexpr (FULL_N) {
      #pragma unroll
      for (int m = 0; m < 2; m++) {
        const int row = off_m + warp_id * 32 + m * 16 + (lane_id >> 2);
        const int row2 = row + 8;

        if constexpr (BLOCK_N == 128) {
          #if USE_BN128_LD16
          float tmp[64];
          tcgen05_ld_16x256bx16(tmp, warp_id * 32 + m * 16, 0);
          asm volatile("tcgen05.wait::ld.sync.aligned;");

          #pragma unroll
          for (int i = 0; i < 16; i++) {
            const int col = off_n + i * 8 + ((lane_id & 3) << 1);
            if (row < M) {
              reinterpret_cast<half2 *>(C_ptr + row * N + col)[0] =
                  __float22half2_rn({tmp[i * 4 + 0], tmp[i * 4 + 1]});
            }
            if (row2 < M) {
              reinterpret_cast<half2 *>(C_ptr + row2 * N + col)[0] =
                  __float22half2_rn({tmp[i * 4 + 2], tmp[i * 4 + 3]});
            }
          }
          #else
          float tmp[32];

          tcgen05_ld_16x256bx8(tmp, warp_id * 32 + m * 16, 0);
          asm volatile("tcgen05.wait::ld.sync.aligned;");

          #pragma unroll
          for (int i = 0; i < 8; i++) {
            const int col = off_n + i * 8 + ((lane_id & 3) << 1);
            if (row < M) {
              reinterpret_cast<half2 *>(C_ptr + row * N + col)[0] =
                  __float22half2_rn({tmp[i * 4 + 0], tmp[i * 4 + 1]});
            }
            if (row2 < M) {
              reinterpret_cast<half2 *>(C_ptr + row2 * N + col)[0] =
                  __float22half2_rn({tmp[i * 4 + 2], tmp[i * 4 + 3]});
            }
          }

          tcgen05_ld_16x256bx8(tmp, warp_id * 32 + m * 16, 64);
          asm volatile("tcgen05.wait::ld.sync.aligned;");

          #pragma unroll
          for (int i = 0; i < 8; i++) {
            const int col = off_n + 64 + i * 8 + ((lane_id & 3) << 1);
            if (row < M) {
              reinterpret_cast<half2 *>(C_ptr + row * N + col)[0] =
                  __float22half2_rn({tmp[i * 4 + 0], tmp[i * 4 + 1]});
            }
            if (row2 < M) {
              reinterpret_cast<half2 *>(C_ptr + row2 * N + col)[0] =
                  __float22half2_rn({tmp[i * 4 + 2], tmp[i * 4 + 3]});
            }
          }
          #endif
        } else {
          float tmp[BLOCK_N / 2];
          tcgen05_ld_16x256bx8(tmp, warp_id * 32 + m * 16, 0);
          asm volatile("tcgen05.wait::ld.sync.aligned;");

          #pragma unroll
          for (int i = 0; i < BLOCK_N / 8; i++) {
            const int col = off_n + i * 8 + ((lane_id & 3) << 1);
            if (row < M) {
              reinterpret_cast<half2 *>(C_ptr + row * N + col)[0] =
                  __float22half2_rn({tmp[i * 4 + 0], tmp[i * 4 + 1]});
            }
            if (row2 < M) {
              reinterpret_cast<half2 *>(C_ptr + row2 * N + col)[0] =
                  __float22half2_rn({tmp[i * 4 + 2], tmp[i * 4 + 3]});
            }
          }
        }
      }
    } else {
      const bool full_n = (off_n + BLOCK_N) <= N;

      #pragma unroll
      for (int m = 0; m < 2; m++) {
        const int row = off_m + warp_id * 32 + m * 16 + (lane_id >> 2);
        const int row2 = row + 8;

        if constexpr (BLOCK_N == 128) {
          #if USE_BN128_LD16
          float tmp[64];
          tcgen05_ld_16x256bx16(tmp, warp_id * 32 + m * 16, 0);
          asm volatile("tcgen05.wait::ld.sync.aligned;");

          #pragma unroll
          for (int i = 0; i < 16; i++) {
            const int col = off_n + i * 8 + ((lane_id & 3) << 1);

            if (row < M) {
              if (full_n || (col + 1) < N) {
                reinterpret_cast<half2 *>(C_ptr + row * N + col)[0] =
                    __float22half2_rn({tmp[i * 4 + 0], tmp[i * 4 + 1]});
              } else if (col < N) {
                C_ptr[row * N + col] = __float2half_rn(tmp[i * 4 + 0]);
              }
            }

            if (row2 < M) {
              if (full_n || (col + 1) < N) {
                reinterpret_cast<half2 *>(C_ptr + row2 * N + col)[0] =
                    __float22half2_rn({tmp[i * 4 + 2], tmp[i * 4 + 3]});
              } else if (col < N) {
                C_ptr[row2 * N + col] = __float2half_rn(tmp[i * 4 + 2]);
              }
            }
          }
          #else
          float tmp[32];

          tcgen05_ld_16x256bx8(tmp, warp_id * 32 + m * 16, 0);
          asm volatile("tcgen05.wait::ld.sync.aligned;");

          #pragma unroll
          for (int i = 0; i < 8; i++) {
            const int col = off_n + i * 8 + ((lane_id & 3) << 1);

            if (row < M) {
              if (full_n || (col + 1) < N) {
                reinterpret_cast<half2 *>(C_ptr + row * N + col)[0] =
                    __float22half2_rn({tmp[i * 4 + 0], tmp[i * 4 + 1]});
              } else if (col < N) {
                C_ptr[row * N + col] = __float2half_rn(tmp[i * 4 + 0]);
              }
            }

            if (row2 < M) {
              if (full_n || (col + 1) < N) {
                reinterpret_cast<half2 *>(C_ptr + row2 * N + col)[0] =
                    __float22half2_rn({tmp[i * 4 + 2], tmp[i * 4 + 3]});
              } else if (col < N) {
                C_ptr[row2 * N + col] = __float2half_rn(tmp[i * 4 + 2]);
              }
            }
          }

          tcgen05_ld_16x256bx8(tmp, warp_id * 32 + m * 16, 64);
          asm volatile("tcgen05.wait::ld.sync.aligned;");

          #pragma unroll
          for (int i = 0; i < 8; i++) {
            const int col = off_n + 64 + i * 8 + ((lane_id & 3) << 1);

            if (row < M) {
              if (full_n || (col + 1) < N) {
                reinterpret_cast<half2 *>(C_ptr + row * N + col)[0] =
                    __float22half2_rn({tmp[i * 4 + 0], tmp[i * 4 + 1]});
              } else if (col < N) {
                C_ptr[row * N + col] = __float2half_rn(tmp[i * 4 + 0]);
              }
            }

            if (row2 < M) {
              if (full_n || (col + 1) < N) {
                reinterpret_cast<half2 *>(C_ptr + row2 * N + col)[0] =
                    __float22half2_rn({tmp[i * 4 + 2], tmp[i * 4 + 3]});
              } else if (col < N) {
                C_ptr[row2 * N + col] = __float2half_rn(tmp[i * 4 + 2]);
              }
            }
          }
          #endif
        } else {
          float tmp[BLOCK_N / 2];
          tcgen05_ld_16x256bx8(tmp, warp_id * 32 + m * 16, 0);
          asm volatile("tcgen05.wait::ld.sync.aligned;");

          #pragma unroll
          for (int i = 0; i < BLOCK_N / 8; i++) {
            const int col = off_n + i * 8 + ((lane_id & 3) << 1);

            if (row < M) {
              if (full_n || (col + 1) < N) {
                reinterpret_cast<half2 *>(C_ptr + row * N + col)[0] =
                    __float22half2_rn({tmp[i * 4 + 0], tmp[i * 4 + 1]});
              } else if (col < N) {
                C_ptr[row * N + col] = __float2half_rn(tmp[i * 4 + 0]);
              }
            }

            if (row2 < M) {
              if (full_n || (col + 1) < N) {
                reinterpret_cast<half2 *>(C_ptr + row2 * N + col)[0] =
                    __float22half2_rn({tmp[i * 4 + 2], tmp[i * 4 + 3]});
              } else if (col < N) {
                C_ptr[row2 * N + col] = __float2half_rn(tmp[i * 4 + 2]);
              }
            }
          }
        }
      }
    }

    asm volatile("bar.sync 1, %0;" :: "r"(thr) : "memory");
    if (warp_id == 0) asm volatile("tcgen05.dealloc.cta_group::1.sync.aligned.b32 %0, %1;" :: "r"(0), "r"(BLOCK_N * 2));
  }
}

template <int BLOCK_N, int NUM_STAGES, bool FULL_N>
__global__ __launch_bounds__(128 + 2 * WARP_SIZE)
void kernel_grouped(const GroupDesc *descs) {
  constexpr int BLOCK_M = 128;
  constexpr int BLOCK_K = 256;

  const int gid = (int)blockIdx.z;
  const GroupDesc *desc = descs + gid;
  const int M = desc->M;
  const int N = desc->N;
  const int K = desc->K;

  const int grid_m = (M + 127) / 128;
  const int grid_n = (N + BLOCK_N - 1) / BLOCK_N;

  const int bid_n = (int)blockIdx.x;
  const int bid_m = (int)blockIdx.y;
  if (bid_n >= grid_n || bid_m >= grid_m) return;

  const CUtensorMap *A_tmap = &desc->A_tmap;
  const CUtensorMap *B_tmap = &desc->B_tmap;
  const char *SFA_ptr = (const char *)desc->SFA_ptr;
  const char *SFB_ptr = (const char *)desc->SFB_ptr;
  half *C_ptr = (half *)desc->C_ptr;

  const int tid = (int)threadIdx.x;
  const int lane_id = tid & (WARP_SIZE - 1);
  const int warp_id = tid >> 5;

  const int off_m = bid_m * BLOCK_M;
  const int off_n = bid_n * BLOCK_N;

  constexpr int NUM_WARPS = BLOCK_M / WARP_SIZE + 2;

  extern __shared__ __align__(1024) char smem_ptr[];
  const int smem = (int)__cvta_generic_to_shared(smem_ptr);
  constexpr int A_size   = BLOCK_M * BLOCK_K / 2;
  constexpr int B_size   = BLOCK_N * BLOCK_K / 2;
  constexpr int SFA_size = 128 * BLOCK_K / 16;
  constexpr int SFB_size = 128 * BLOCK_K / 16;
  constexpr int STAGE_SIZE = A_size + B_size + SFA_size + SFB_size;

  #pragma nv_diag_suppress static_var_with_dynamic_init
  __shared__ int64_t mbars[NUM_STAGES * 2 + 1];
  const int tma_mbar_addr = (int)__cvta_generic_to_shared(mbars);
  const int mma_mbar_addr = tma_mbar_addr + NUM_STAGES * 8;
  const int mainloop_mbar_addr = mma_mbar_addr + NUM_STAGES * 8;

  constexpr int SFA_tmem = BLOCK_N;
  constexpr int SFB_tmem = SFA_tmem + 4 * (BLOCK_K / MMA_K);

  if (warp_id == 0 && elect_sync()) {
    #pragma unroll
    for (int i = 0; i < NUM_STAGES * 2 + 1; i++) mbarrier_init(tma_mbar_addr + i * 8, 1);
    asm volatile("fence.mbarrier_init.release.cluster;");
  } else if (warp_id == 1) {
    asm volatile("tcgen05.alloc.cta_group::1.sync.aligned.shared::cta.b32 [%0], %1;" :: "r"(smem), "r"(BLOCK_N * 2));
  }
  __syncthreads();

  const int num_iters = K / BLOCK_K;

  if (warp_id == NUM_WARPS - 2 && elect_sync()) {
    uint64_t cache_A, cache_B;
    if (grid_n >= grid_m) { cache_A = EVICT_LAST; cache_B = EVICT_FIRST; }
    else { cache_A = EVICT_FIRST; cache_B = EVICT_LAST; }

    auto issue_tma = [&](int iter_k, int stage_id) {
      const int mbar_addr = tma_mbar_addr + stage_id * 8;
      const int A_smem = smem + stage_id * STAGE_SIZE;
      const int B_smem = A_smem + A_size;
      const int SFA_smem = B_smem + B_size;
      const int SFB_smem = SFA_smem + SFA_size;

      const int off_k = iter_k * BLOCK_K;
      tma_3d_gmem2smem(A_smem, A_tmap, 0, off_m, off_k / 256, mbar_addr, cache_A);
      tma_3d_gmem2smem(B_smem, B_tmap, 0, off_n, off_k / 256, mbar_addr, cache_B);

      const int rest_k = K / 16 / 4;
      const char *SFA_src = SFA_ptr + ((off_m / 128) * rest_k + off_k / (16 * 4)) * 512;
      const char *SFB_src = SFB_ptr + ((off_n / 128) * rest_k + off_k / (16 * 4)) * 512;
      tma_gmem2smem(SFA_smem, SFA_src, SFA_size, mbar_addr, cache_A);
      tma_gmem2smem(SFB_smem, SFB_src, SFB_size, mbar_addr, cache_B);

      asm volatile("mbarrier.arrive.expect_tx.release.cta.shared::cta.b64 _, [%0], %1;"
                   :: "r"(mbar_addr), "r"(STAGE_SIZE) : "memory");
    };

    const int init_stage = (num_iters < NUM_STAGES) ? num_iters : NUM_STAGES;
    for (int iter_k = 0; iter_k < init_stage; iter_k++) issue_tma(iter_k, iter_k);

    for (int iter_k = NUM_STAGES; iter_k < num_iters; iter_k++) {
      const int stage_id = iter_k % NUM_STAGES;
      const int mma_phase = (iter_k / NUM_STAGES - 1) & 1;
      mbarrier_wait(mma_mbar_addr + stage_id * 8, mma_phase);
      issue_tma(iter_k, stage_id);
    }
  } else if (warp_id == NUM_WARPS - 1 && elect_sync()) {
    constexpr int MMA_N = BLOCK_N;
    constexpr int MMA_M = 128;
    constexpr uint32_t i_desc = (1U << 7U)
                              | (1U << 10U)
                              | ((uint32_t)MMA_N >> 3U << 17U)
                              | ((uint32_t)MMA_M >> 7U << 27U);

    auto make_desc_AB = [] __device__ (int addr) -> uint64_t {
      const int SBO = 8 * 128;
      return desc_encode((uint64_t)addr) | (desc_encode((uint64_t)SBO) << 32ULL) | (1ULL << 46ULL) | (2ULL << 61ULL);
    };
    auto make_desc_SF = [] __device__ (int addr) -> uint64_t {
      const int SBO = 8 * 16;
      return desc_encode((uint64_t)addr) | (desc_encode((uint64_t)SBO) << 32ULL) | (1ULL << 46ULL);
    };

    for (int iter_k = 0; iter_k < num_iters; iter_k++) {
      const int stage_id = iter_k % NUM_STAGES;
      const int tma_phase = (iter_k / NUM_STAGES) & 1;
      mbarrier_wait(tma_mbar_addr + stage_id * 8, tma_phase);

      const int A_smem = smem + stage_id * STAGE_SIZE;
      const int B_smem = A_smem + A_size;
      const int SFA_smem = B_smem + B_size;
      const int SFB_smem = SFA_smem + SFA_size;

      const uint64_t SFA_desc = make_desc_SF(0) + ((uint64_t)SFA_smem >> 4ULL);
      const uint64_t SFB_desc = make_desc_SF(0) + ((uint64_t)SFB_smem >> 4ULL);

      #pragma unroll
      for (int k = 0; k < BLOCK_K / MMA_K; k++) {
        uint64_t sfa_desc = SFA_desc + (uint64_t)k * (512ULL >> 4ULL);
        uint64_t sfb_desc = SFB_desc + (uint64_t)k * (512ULL >> 4ULL);
        tcgen05_cp_nvfp4(SFA_tmem + k * 4, sfa_desc);
        tcgen05_cp_nvfp4(SFB_tmem + k * 4, sfb_desc);
      }

      #pragma unroll
      for (int k1 = 0; k1 < BLOCK_K / 256; k1++) {
        #pragma unroll
        for (int k2 = 0; k2 < 256 / MMA_K; k2++) {
          uint64_t a_desc = make_desc_AB(A_smem + k1 * BLOCK_M * 128 + k2 * 32);
          uint64_t b_desc = make_desc_AB(B_smem + k1 * BLOCK_N * 128 + k2 * 32);

          const int k_sf = k1 * 4 + k2;
          const int scale_A_tmem = SFA_tmem + k_sf * 4;
          const int scale_B_tmem = SFB_tmem + k_sf * 4 + (bid_n % (128 / BLOCK_N)) * (BLOCK_N / 32);
          const int enable_input_d = (k1 == 0 && k2 == 0) ? iter_k : 1;
          tcgen05_mma_nvfp4(a_desc, b_desc, i_desc, scale_A_tmem, scale_B_tmem, enable_input_d);
        }
      }

      asm volatile("tcgen05.commit.cta_group::1.mbarrier::arrive::one.shared::cluster.b64 [%0];"
                   :: "r"(mma_mbar_addr + stage_id * 8) : "memory");
    }

    asm volatile("tcgen05.commit.cta_group::1.mbarrier::arrive::one.shared::cluster.b64 [%0];"
                 :: "r"(mainloop_mbar_addr) : "memory");
  } else if (tid < BLOCK_M) {
    const int thr = active_threads_128(M, off_m);
    if (tid >= thr) return;

    mbarrier_wait(mainloop_mbar_addr, 0);
    asm volatile("tcgen05.fence::after_thread_sync;");

    if constexpr (FULL_N) {
      #pragma unroll
      for (int m = 0; m < 2; m++) {
        const int row = off_m + warp_id * 32 + m * 16 + (lane_id >> 2);
        const int row2 = row + 8;

        if constexpr (BLOCK_N == 128) {
          #if USE_BN128_LD16
          float tmp[64];
          tcgen05_ld_16x256bx16(tmp, warp_id * 32 + m * 16, 0);
          asm volatile("tcgen05.wait::ld.sync.aligned;");

          #pragma unroll
          for (int i = 0; i < 16; i++) {
            const int col = off_n + i * 8 + ((lane_id & 3) << 1);
            if (row < M) {
              reinterpret_cast<half2 *>(C_ptr + row * N + col)[0] =
                  __float22half2_rn({tmp[i * 4 + 0], tmp[i * 4 + 1]});
            }
            if (row2 < M) {
              reinterpret_cast<half2 *>(C_ptr + row2 * N + col)[0] =
                  __float22half2_rn({tmp[i * 4 + 2], tmp[i * 4 + 3]});
            }
          }
          #else
          float tmp[32];

          tcgen05_ld_16x256bx8(tmp, warp_id * 32 + m * 16, 0);
          asm volatile("tcgen05.wait::ld.sync.aligned;");

          #pragma unroll
          for (int i = 0; i < 8; i++) {
            const int col = off_n + i * 8 + ((lane_id & 3) << 1);
            if (row < M) {
              reinterpret_cast<half2 *>(C_ptr + row * N + col)[0] =
                  __float22half2_rn({tmp[i * 4 + 0], tmp[i * 4 + 1]});
            }
            if (row2 < M) {
              reinterpret_cast<half2 *>(C_ptr + row2 * N + col)[0] =
                  __float22half2_rn({tmp[i * 4 + 2], tmp[i * 4 + 3]});
            }
          }

          tcgen05_ld_16x256bx8(tmp, warp_id * 32 + m * 16, 64);
          asm volatile("tcgen05.wait::ld.sync.aligned;");

          #pragma unroll
          for (int i = 0; i < 8; i++) {
            const int col = off_n + 64 + i * 8 + ((lane_id & 3) << 1);
            if (row < M) {
              reinterpret_cast<half2 *>(C_ptr + row * N + col)[0] =
                  __float22half2_rn({tmp[i * 4 + 0], tmp[i * 4 + 1]});
            }
            if (row2 < M) {
              reinterpret_cast<half2 *>(C_ptr + row2 * N + col)[0] =
                  __float22half2_rn({tmp[i * 4 + 2], tmp[i * 4 + 3]});
            }
          }
          #endif
        } else {
          float tmp[BLOCK_N / 2];
          tcgen05_ld_16x256bx8(tmp, warp_id * 32 + m * 16, 0);
          asm volatile("tcgen05.wait::ld.sync.aligned;");

          #pragma unroll
          for (int i = 0; i < BLOCK_N / 8; i++) {
            const int col = off_n + i * 8 + ((lane_id & 3) << 1);
            if (row < M) {
              reinterpret_cast<half2 *>(C_ptr + row * N + col)[0] =
                  __float22half2_rn({tmp[i * 4 + 0], tmp[i * 4 + 1]});
            }
            if (row2 < M) {
              reinterpret_cast<half2 *>(C_ptr + row2 * N + col)[0] =
                  __float22half2_rn({tmp[i * 4 + 2], tmp[i * 4 + 3]});
            }
          }
        }
      }
    } else {
      const bool full_n = (off_n + BLOCK_N) <= N;

      #pragma unroll
      for (int m = 0; m < 2; m++) {
        const int row = off_m + warp_id * 32 + m * 16 + (lane_id >> 2);
        const int row2 = row + 8;

        if constexpr (BLOCK_N == 128) {
          #if USE_BN128_LD16
          float tmp[64];
          tcgen05_ld_16x256bx16(tmp, warp_id * 32 + m * 16, 0);
          asm volatile("tcgen05.wait::ld.sync.aligned;");

          #pragma unroll
          for (int i = 0; i < 16; i++) {
            const int col = off_n + i * 8 + ((lane_id & 3) << 1);

            if (row < M) {
              if (full_n || (col + 1) < N) {
                reinterpret_cast<half2 *>(C_ptr + row * N + col)[0] =
                    __float22half2_rn({tmp[i * 4 + 0], tmp[i * 4 + 1]});
              } else if (col < N) {
                C_ptr[row * N + col] = __float2half_rn(tmp[i * 4 + 0]);
              }
            }

            if (row2 < M) {
              if (full_n || (col + 1) < N) {
                reinterpret_cast<half2 *>(C_ptr + row2 * N + col)[0] =
                    __float22half2_rn({tmp[i * 4 + 2], tmp[i * 4 + 3]});
              } else if (col < N) {
                C_ptr[row2 * N + col] = __float2half_rn(tmp[i * 4 + 2]);
              }
            }
          }
          #else
          float tmp[32];

          tcgen05_ld_16x256bx8(tmp, warp_id * 32 + m * 16, 0);
          asm volatile("tcgen05.wait::ld.sync.aligned;");

          #pragma unroll
          for (int i = 0; i < 8; i++) {
            const int col = off_n + i * 8 + ((lane_id & 3) << 1);

            if (row < M) {
              if (full_n || (col + 1) < N) {
                reinterpret_cast<half2 *>(C_ptr + row * N + col)[0] =
                    __float22half2_rn({tmp[i * 4 + 0], tmp[i * 4 + 1]});
              } else if (col < N) {
                C_ptr[row * N + col] = __float2half_rn(tmp[i * 4 + 0]);
              }
            }

            if (row2 < M) {
              if (full_n || (col + 1) < N) {
                reinterpret_cast<half2 *>(C_ptr + row2 * N + col)[0] =
                    __float22half2_rn({tmp[i * 4 + 2], tmp[i * 4 + 3]});
              } else if (col < N) {
                C_ptr[row2 * N + col] = __float2half_rn(tmp[i * 4 + 2]);
              }
            }
          }

          tcgen05_ld_16x256bx8(tmp, warp_id * 32 + m * 16, 64);
          asm volatile("tcgen05.wait::ld.sync.aligned;");

          #pragma unroll
          for (int i = 0; i < 8; i++) {
            const int col = off_n + 64 + i * 8 + ((lane_id & 3) << 1);

            if (row < M) {
              if (full_n || (col + 1) < N) {
                reinterpret_cast<half2 *>(C_ptr + row * N + col)[0] =
                    __float22half2_rn({tmp[i * 4 + 0], tmp[i * 4 + 1]});
              } else if (col < N) {
                C_ptr[row * N + col] = __float2half_rn(tmp[i * 4 + 0]);
              }
            }

            if (row2 < M) {
              if (full_n || (col + 1) < N) {
                reinterpret_cast<half2 *>(C_ptr + row2 * N + col)[0] =
                    __float22half2_rn({tmp[i * 4 + 2], tmp[i * 4 + 3]});
              } else if (col < N) {
                C_ptr[row2 * N + col] = __float2half_rn(tmp[i * 4 + 2]);
              }
            }
          }
          #endif
        } else {
          float tmp[BLOCK_N / 2];
          tcgen05_ld_16x256bx8(tmp, warp_id * 32 + m * 16, 0);
          asm volatile("tcgen05.wait::ld.sync.aligned;");

          #pragma unroll
          for (int i = 0; i < BLOCK_N / 8; i++) {
            const int col = off_n + i * 8 + ((lane_id & 3) << 1);

            if (row < M) {
              if (full_n || (col + 1) < N) {
                reinterpret_cast<half2 *>(C_ptr + row * N + col)[0] =
                    __float22half2_rn({tmp[i * 4 + 0], tmp[i * 4 + 1]});
              } else if (col < N) {
                C_ptr[row * N + col] = __float2half_rn(tmp[i * 4 + 0]);
              }
            }

            if (row2 < M) {
              if (full_n || (col + 1) < N) {
                reinterpret_cast<half2 *>(C_ptr + row2 * N + col)[0] =
                    __float22half2_rn({tmp[i * 4 + 2], tmp[i * 4 + 3]});
              } else if (col < N) {
                C_ptr[row2 * N + col] = __float2half_rn(tmp[i * 4 + 2]);
              }
            }
          }
        }
      }
    }

    asm volatile("bar.sync 1, %0;" :: "r"(thr) : "memory");
    if (warp_id == 0) asm volatile("tcgen05.dealloc.cta_group::1.sync.aligned.b32 %0, %1;" :: "r"(0), "r"(BLOCK_N * 2));
  }
}

template <int BLOCK_N, int NUM_STAGES, bool FULL_N>
static __forceinline__ void gemm_launch(
  const at::Tensor& A,
  const at::Tensor& B,
  const at::Tensor& SFA,
  const at::Tensor& SFB,
        at::Tensor& C,
  int M, int N, int K
) {
  const int Apad = (int)A.size(0);
  const char *A_ptr = (const char *)A.data_ptr();
  const char *B_ptr = (const char *)B.data_ptr();
  const char *SFA_ptr = (const char *)SFA.data_ptr();
  const char *SFB_ptr = (const char *)SFB.data_ptr();
  half *C_ptr = (half *)C.data_ptr<at::Half>();

  CUtensorMap A_tmap, B_tmap;
  init_AB_tmap(&A_tmap, A_ptr, (uint64_t)Apad, (uint64_t)K, 128, 256);
  init_AB_tmap(&B_tmap, B_ptr, (uint64_t)N,    (uint64_t)K, (uint32_t)BLOCK_N, 256);

  const int grid_m = (M + 127) / 128;
  const int grid_n = (N + BLOCK_N - 1) / BLOCK_N;

  const int tb_size = 128 + 2 * WARP_SIZE;
  const int A_size = 128 * 256 / 2;
  const int B_size = BLOCK_N * 256 / 2;
  const int SF_size = 128 * 256 / 16;
  const int smem_size = (A_size + B_size + SF_size * 2) * NUM_STAGES;

  auto k = kernel<BLOCK_N, NUM_STAGES, FULL_N>;
  // 只在首次使用该设备时设置一次，避免每次调用都走一次 runtime API
  static int last_dev = -1;
  int dev = -1;
  cudaGetDevice(&dev);
  if (dev != last_dev) {
    auto err = cudaFuncSetAttribute(k, cudaFuncAttributeMaxDynamicSharedMemorySize, smem_size);
    GG_CHECK(err == cudaSuccess, "cudaFuncSetAttribute failed");
    last_dev = dev;
  }

  dim3 grid((unsigned)grid_n, (unsigned)grid_m, 1);
  k<<<grid, tb_size, smem_size>>>(A_tmap, B_tmap, SFA_ptr, SFB_ptr, C_ptr, M, N, K);
}

static __forceinline__ int pick_stage_from_K(int K) {
  // K 一定是 256 的倍数
  const int iters = K >> 8;
  if (iters <= 8) return 2;
  if (iters <= 16) return 3;
  return 4;
}

static __forceinline__ int get_sm_count_cached(int dev) {
  // 只在切换设备时查询一次，避免 host 热路径额外开销
  static int cached_dev = -1;
  static int cached_sm = 0;
  if (dev != cached_dev) {
    int sm = 0;
    cudaDeviceGetAttribute(&sm, cudaDevAttrMultiProcessorCount, dev);
    cached_sm = sm;
    cached_dev = dev;
  }
  return cached_sm;
}

static __forceinline__ int pick_stage_bn128(int K, int total_cta, int sm_count) {
  // 目标：避免 stage=4 在“并行 CTA 数不足以覆盖占用率损失”的区间退化
  const int iters = K >> 8;
  if (iters <= 8) return 2;
  if (iters < 24) return 3;
  if (sm_count <= 0) return 4;
  // 经验启发式：只有当 total_cta 落在 [SM, 2*SM) 时，stage=3 更可能占优
  if (total_cta >= sm_count && total_cta < (sm_count << 1)) return 3;
  return 4;
}

at::Tensor gemm(
  const at::Tensor& A,
  const at::Tensor& B,
  const at::Tensor& SFA,
  const at::Tensor& SFB,
        at::Tensor& C,
  int64_t M,
  int64_t N,
  int64_t K
) {
  const int Mi = (int)M;
  const int Ni = (int)N;
  const int Ki = (int)K;

  if (((Ni & 127) == 0) && (Ni >= 128)) {
    // BN128：N 对齐时可用 FULL_N 变体，去掉 N 尾分支
    const int grid_m = (Mi + 127) / 128;
    const int grid_n = Ni >> 7;
    int dev = -1;
    cudaGetDevice(&dev);
    const int sm_count = get_sm_count_cached(dev);
    const int stage = pick_stage_bn128(Ki, grid_m * grid_n, sm_count);
    if (stage == 2) gemm_launch<128, 2, true>(A, B, SFA, SFB, C, Mi, Ni, Ki);
    else if (stage == 3) gemm_launch<128, 3, true>(A, B, SFA, SFB, C, Mi, Ni, Ki);
    else gemm_launch<128, 4, true>(A, B, SFA, SFB, C, Mi, Ni, Ki);
  } else {
    const int stage = pick_stage_from_K(Ki);
    const bool full_n = ((Ni & 63) == 0);
    if (stage == 2) {
      if (full_n) gemm_launch<64, 2, true>(A, B, SFA, SFB, C, Mi, Ni, Ki);
      else gemm_launch<64, 2, false>(A, B, SFA, SFB, C, Mi, Ni, Ki);
    } else if (stage == 3) {
      if (full_n) gemm_launch<64, 3, true>(A, B, SFA, SFB, C, Mi, Ni, Ki);
      else gemm_launch<64, 3, false>(A, B, SFA, SFB, C, Mi, Ni, Ki);
    } else {
      if (full_n) gemm_launch<64, 4, true>(A, B, SFA, SFB, C, Mi, Ni, Ki);
      else gemm_launch<64, 4, false>(A, B, SFA, SFB, C, Mi, Ni, Ki);
    }
  }

  GG_CHECK(cudaGetLastError() == cudaSuccess, "kernel launch failed");
  return C;
}

struct GroupWorkspace {
  at::Tensor descs_d;
  int64_t cap_G;
  int64_t dev;
  uint64_t last_hash;
  uint64_t last_hash2;
  uint64_t last_sentinel0;
  uint64_t last_sentinel1;
  int64_t last_G;
  int last_block_n;
  int last_max_grid_m;
  int last_max_grid_n;
  int last_stage;
  std::vector<GroupDesc> host_descs;
  GroupWorkspace()
      : cap_G(0),
        dev(-1),
        last_hash(0),
        last_hash2(0),
        last_sentinel0(0),
        last_sentinel1(0),
        last_G(0),
        last_block_n(0),
        last_max_grid_m(0),
        last_max_grid_n(0),
        last_stage(0) {}
};

static GroupWorkspace g_ws;

static __forceinline__ void ensure_ws(int64_t dev, int64_t G) {
  if (g_ws.dev != dev || g_ws.cap_G < G || !g_ws.descs_d.defined()) {
    g_ws.dev = dev;
    g_ws.cap_G = G;
    at::TensorOptions opt_u8 = at::TensorOptions().device(at::kCUDA, (int)dev).dtype(at::kByte);
    g_ws.descs_d = at::empty({G, (int64_t)sizeof(GroupDesc)}, opt_u8);
    g_ws.last_hash = 0;
    g_ws.last_hash2 = 0;
    g_ws.last_sentinel0 = 0;
    g_ws.last_sentinel1 = 0;
    g_ws.last_G = 0;
  }
}

static __forceinline__ uint64_t fnv1a_mix_u64(uint64_t h, uint64_t x) {
  h ^= x;
  h *= 1099511628211ULL;
  return h;
}

template <int BLOCK_N, int NUM_STAGES, bool FULL_N>
static __forceinline__ void grouped_launch(
  int64_t dev,
  int max_grid_m,
  int max_grid_n,
  int64_t G
) {
  const int tb_size = 128 + 2 * WARP_SIZE;
  const int A_size = 128 * 256 / 2;
  const int B_size = BLOCK_N * 256 / 2;
  const int SF_size = 128 * 256 / 16;
  const int smem_size = (A_size + B_size + SF_size * 2) * NUM_STAGES;

  auto k = kernel_grouped<BLOCK_N, NUM_STAGES, FULL_N>;
  static int last_dev = -1;
  if ((int)dev != last_dev) {
    auto err = cudaFuncSetAttribute(k, cudaFuncAttributeMaxDynamicSharedMemorySize, smem_size);
    GG_CHECK(err == cudaSuccess, "cudaFuncSetAttribute failed");
    last_dev = (int)dev;
  }

  dim3 grid((unsigned)max_grid_n, (unsigned)max_grid_m, (unsigned)G);
  k<<<grid, tb_size, smem_size>>>((const GroupDesc *)g_ws.descs_d.data_ptr());
}

void gemm_grouped(
  at::TensorList A_list,
  at::TensorList B_list,
  at::TensorList SFA_list,
  at::TensorList SFB_list,
  at::TensorList C_list,
  bool force_bn64
) {
  const int64_t G = (int64_t)A_list.size();
  if (G <= 0) return;

  const auto &A0 = A_list[0];
  const int64_t dev = (int64_t)A0.get_device();
  if (g_ws.dev != dev) cudaSetDevice((int)dev);
  ensure_ws(dev, G);

  bool use_bn128 = !force_bn64;
  for (int i = 0; i < (int)G; i++) {
    const auto &C = C_list[i];
    const int N = (int)C.size(1);
    if (N < 128 || ((N & 127) != 0)) { use_bn128 = false; break; }
  }
  const int block_n = use_bn128 ? 128 : 64;

  bool full_n_all = true;

  uint64_t h = 1469598103934665603ULL;
  uint64_t h2 = 0x9e3779b97f4a7c15ULL;
  uint64_t sent0 = 0;
  uint64_t sent1 = 0;
  const int last_i = (int)G - 1;
  h = fnv1a_mix_u64(h, (uint64_t)G);
  h = fnv1a_mix_u64(h, (uint64_t)block_n);
  h2 = fnv1a_mix_u64(h2, (uint64_t)G);
  h2 = fnv1a_mix_u64(h2, (uint64_t)block_n);

  int max_grid_m = 0;
  int max_grid_n = 0;
  int max_K = 0;

  for (int i = 0; i < (int)G; i++) {
    const auto &A = A_list[i];
    const auto &B = B_list[i];
    const auto &SFA = SFA_list[i];
    const auto &SFB = SFB_list[i];
    const auto &C = C_list[i];

    const int M = (int)C.size(0);
    const int N = (int)C.size(1);
    const int K = (int)A.size(1) * 2;
    const int Apad = (int)A.size(0);
    if ((N & (block_n - 1)) != 0) full_n_all = false;

    const int grid_m = (M + 127) / 128;
    const int grid_n = (N + block_n - 1) / block_n;
    if (grid_m > max_grid_m) max_grid_m = grid_m;
    if (grid_n > max_grid_n) max_grid_n = grid_n;
    if (K > max_K) max_K = K;

    const uint64_t A_ptr = (uint64_t)A.data_ptr();
    const uint64_t B_ptr = (uint64_t)B.data_ptr();
    const uint64_t SFA_ptr = (uint64_t)SFA.data_ptr();
    const uint64_t SFB_ptr = (uint64_t)SFB.data_ptr();
    const uint64_t C_ptr = (uint64_t)C.data_ptr<at::Half>();

    h = fnv1a_mix_u64(h, A_ptr);
    h = fnv1a_mix_u64(h, B_ptr);
    h = fnv1a_mix_u64(h, SFA_ptr);
    h = fnv1a_mix_u64(h, SFB_ptr);
    h = fnv1a_mix_u64(h, C_ptr);
    h = fnv1a_mix_u64(h, (uint64_t)M);
    h = fnv1a_mix_u64(h, (uint64_t)N);
    h = fnv1a_mix_u64(h, ((uint64_t)K << 32) | (uint64_t)(uint32_t)Apad);

    h2 = fnv1a_mix_u64(h2, A_ptr);
    h2 = fnv1a_mix_u64(h2, B_ptr);
    h2 = fnv1a_mix_u64(h2, SFA_ptr);
    h2 = fnv1a_mix_u64(h2, SFB_ptr);
    h2 = fnv1a_mix_u64(h2, C_ptr);
    h2 = fnv1a_mix_u64(h2, (uint64_t)M);
    h2 = fnv1a_mix_u64(h2, (uint64_t)N);
    h2 = fnv1a_mix_u64(h2, ((uint64_t)K << 32) | (uint64_t)(uint32_t)Apad);

    if (i == 0) {
      uint64_t s = 1469598103934665603ULL;
      s = fnv1a_mix_u64(s, A_ptr);
      s = fnv1a_mix_u64(s, B_ptr);
      s = fnv1a_mix_u64(s, C_ptr);
      s = fnv1a_mix_u64(s, ((uint64_t)M << 32) | (uint64_t)(uint32_t)N);
      s = fnv1a_mix_u64(s, ((uint64_t)K << 32) | (uint64_t)(uint32_t)Apad);
      sent0 = s;
    }
    if (i == last_i) {
      uint64_t s = 1469598103934665603ULL;
      s = fnv1a_mix_u64(s, SFA_ptr);
      s = fnv1a_mix_u64(s, SFB_ptr);
      s = fnv1a_mix_u64(s, C_ptr);
      s = fnv1a_mix_u64(s, ((uint64_t)M << 32) | (uint64_t)(uint32_t)N);
      s = fnv1a_mix_u64(s, ((uint64_t)K << 32) | (uint64_t)(uint32_t)Apad);
      sent1 = s;
    }
  }

  const int sm_count = get_sm_count_cached((int)dev);
  const int64_t total_cta64 = (int64_t)max_grid_m * (int64_t)max_grid_n * G;
  const int total_cta = (total_cta64 > 0x7fffffffLL) ? 0x7fffffff : (int)total_cta64;
  const int stage = use_bn128 ? pick_stage_bn128(max_K, total_cta, sm_count) : pick_stage_from_K(max_K);
  const bool hit = (g_ws.last_hash == h)
                && (g_ws.last_hash2 == h2)
                && (g_ws.last_sentinel0 == sent0)
                && (g_ws.last_sentinel1 == sent1)
                && (g_ws.last_G == G)
                && (g_ws.last_block_n == block_n)
                && (g_ws.last_stage == stage)
                && g_ws.descs_d.defined();

  if (!hit) {
    g_ws.host_descs.resize((size_t)G);
    GroupDesc *descs = g_ws.host_descs.data();
    for (int i = 0; i < (int)G; i++) {
      const auto &A = A_list[i];
      const auto &B = B_list[i];
      const auto &SFA = SFA_list[i];
      const auto &SFB = SFB_list[i];
      const auto &C = C_list[i];

      const int M = (int)C.size(0);
      const int N = (int)C.size(1);
      const int K = (int)A.size(1) * 2;
      const int Apad = (int)A.size(0);

      GroupDesc d;
      init_AB_tmap(&d.A_tmap, (const char *)A.data_ptr(), (uint64_t)Apad, (uint64_t)K, 128, 256);
      init_AB_tmap(&d.B_tmap, (const char *)B.data_ptr(), (uint64_t)N,    (uint64_t)K, (uint32_t)block_n, 256);
      d.SFA_ptr = (uint64_t)SFA.data_ptr();
      d.SFB_ptr = (uint64_t)SFB.data_ptr();
      d.C_ptr = (uint64_t)C.data_ptr<at::Half>();
      d.M = M;
      d.N = N;
      d.K = K;
      descs[(size_t)i] = d;
    }

    // 单次 memcpy：避免多次 Host→GPU 调用与同步点
    cudaError_t cperr = cudaMemcpy(
      g_ws.descs_d.data_ptr(),
      descs,
      (size_t)G * sizeof(GroupDesc),
      cudaMemcpyHostToDevice
    );
    GG_CHECK(cperr == cudaSuccess, "memcpy fail");

    g_ws.last_hash = h;
    g_ws.last_hash2 = h2;
    g_ws.last_sentinel0 = sent0;
    g_ws.last_sentinel1 = sent1;
    g_ws.last_G = G;
    g_ws.last_block_n = block_n;
    g_ws.last_max_grid_m = max_grid_m;
    g_ws.last_max_grid_n = max_grid_n;
    g_ws.last_stage = stage;
  } else {
    max_grid_m = g_ws.last_max_grid_m;
    max_grid_n = g_ws.last_max_grid_n;
  }

  if (use_bn128) {
    // use_bn128 时已保证所有 group 的 N 都是 128 对齐，理论上 FULL_N 恒为 true
    if (stage == 2) grouped_launch<128, 2, true>(dev, max_grid_m, max_grid_n, G);
    else if (stage == 3) grouped_launch<128, 3, true>(dev, max_grid_m, max_grid_n, G);
    else grouped_launch<128, 4, true>(dev, max_grid_m, max_grid_n, G);
  } else {
    if (stage == 2) {
      if (full_n_all) grouped_launch<64, 2, true>(dev, max_grid_m, max_grid_n, G);
      else grouped_launch<64, 2, false>(dev, max_grid_m, max_grid_n, G);
    } else if (stage == 3) {
      if (full_n_all) grouped_launch<64, 3, true>(dev, max_grid_m, max_grid_n, G);
      else grouped_launch<64, 3, false>(dev, max_grid_m, max_grid_n, G);
    } else {
      if (full_n_all) grouped_launch<64, 4, true>(dev, max_grid_m, max_grid_n, G);
      else grouped_launch<64, 4, false>(dev, max_grid_m, max_grid_n, G);
    }
  }

  GG_CHECK(cudaGetLastError() == cudaSuccess, "kernel launch failed");
}

TORCH_LIBRARY(nvfp4_group_gemm_opt, m) {
  m.def("gemm(Tensor A, Tensor B, Tensor SFA, Tensor SFB, Tensor(a!) C, int M, int N, int K) -> Tensor");
  m.impl("gemm", &gemm);
  m.def("gemm_grouped(Tensor[] A, Tensor[] B, Tensor[] SFA, Tensor[] SFB, Tensor[] C, bool force_bn64) -> ()");
  m.impl("gemm_grouped", &gemm_grouped);
}
"""

    build_dir = os.path.join(os.path.dirname(__file__), ".build_nvfp4_group_gemm_opt")
    os.makedirs(build_dir, exist_ok=True)

    load_inline(
        name="nvfp4_group_gemm_opt_ext",
        cpp_sources="",
        cuda_sources=cuda_src,
        functions=None,
        extra_cflags=["-O3"],
        extra_cuda_cflags=[
            "-O3",
            f"-DUSE_BN128_LD16={1 if _USE_BN128_LD16 else 0}",
            "-gencode=arch=compute_100a,code=sm_100a",
            "--use_fast_math",
            "--expt-extended-lambda",
            "--expt-relaxed-constexpr",
            "--relocatable-device-code=false",
            "-std=c++17",
        ],
        extra_ldflags=["-lcuda"],
        with_cuda=True,
        is_python_module=False,
        no_implicit_headers=True,
        build_directory=build_dir,
        verbose=False,
    )

    _EXT_READY = True
    _OPS_READY = False
    _GEMM = None
    _GEMM_GROUPED = None


def _get_ops():
    global _OPS_READY, _GEMM, _GEMM_GROUPED
    if not _EXT_READY:
        _load_ext()
    if not _OPS_READY:
        _GEMM = torch.ops.nvfp4_group_gemm_opt.gemm
        _GEMM_GROUPED = torch.ops.nvfp4_group_gemm_opt.gemm_grouped
        _OPS_READY = True
    return _GEMM, _GEMM_GROUPED


def _as_u8(x: torch.Tensor) -> torch.Tensor:
    if x.dtype == torch.uint8:
        return x
    if x.element_size() != 1:
        raise RuntimeError("packed tensor must have 1-byte elements")
    return x.view(torch.uint8)


def _reorder_scale_from_raw(scale_u8_2d: torch.Tensor, rows_pad: int) -> torch.Tensor:
    if scale_u8_2d.dim() != 2:
        raise RuntimeError("scale must be 2D")
    rows = int(scale_u8_2d.size(0))
    k16 = int(scale_u8_2d.size(1))
    if (k16 & 3) != 0:
        raise RuntimeError("K//16 must be multiple of 4")
    if (rows_pad & 127) != 0:
        raise RuntimeError("rows_pad must be multiple of 128")
    blk_m = rows_pad // 128
    blk_k = k16 // 4
    buf = torch.empty((rows_pad, k16), device=scale_u8_2d.device, dtype=torch.uint8)
    buf[:rows].copy_(scale_u8_2d)
    v = buf.view(blk_m, 32, 4, blk_k, 4).permute(0, 3, 1, 2, 4).contiguous()
    return v


def _get_scratch_a(device: torch.device, m_pad: int, k2: int) -> torch.Tensor:
    key = (int(device.index), int(m_pad), int(k2))
    buf = _SCRATCH_A.get(key)
    if buf is None or (not buf.is_cuda) or buf.numel() != (m_pad * k2):
        buf = torch.empty((m_pad, k2, 1), device=device, dtype=torch.uint8)
        _SCRATCH_A[key] = buf
    return buf


def _get_scratch_a_grouped(device: torch.device, group_i: int, m_pad: int, k2: int) -> torch.Tensor:
    key = (int(device.index), int(group_i), int(m_pad), int(k2))
    buf = _SCRATCH_A_G.get(key)
    if buf is None or (not buf.is_cuda) or buf.numel() != (m_pad * k2):
        buf = torch.empty((m_pad, k2, 1), device=device, dtype=torch.uint8)
        _SCRATCH_A_G[key] = buf
    return buf


def _must_sfp_layout(x: torch.Tensor) -> None:
    
    if (not x.is_cuda) or (x.dim() != 6) or (x.element_size() != 1) or (int(x.storage_offset()) != 0):
        raise RuntimeError("bad sfx_p layout")
    if int(x.size(0)) != 32 or int(x.size(1)) != 4 or int(x.size(3)) != 4:
        raise RuntimeError("bad sfx_p shape")


def custom_kernel(data):
    abc_tensors, sfasfb_tensors, sfasfb_reordered_tensors, problem_sizes = data

    gemm, gemm_grouped = _get_ops()

    g = len(problem_sizes)
    if g == 0:
        return []

    dev0 = int(abc_tensors[0][0].device.index)
    all_l1 = True
    for i in range(g):
        if int(problem_sizes[i][3]) != 1:
            all_l1 = False
            break
        if int(abc_tensors[i][0].device.index) != dev0:
            all_l1 = False
            break

    outs: List[torch.Tensor] = []

    if all_l1 and (not _FORCE_NO_GROUPED):
        a_list: List[torch.Tensor] = []
        b_list: List[torch.Tensor] = []
        sfa_list: List[torch.Tensor] = []
        sfb_list: List[torch.Tensor] = []
        c_list: List[torch.Tensor] = []

        for i in range(g):
            a, b, c = abc_tensors[i]
            sfa, sfb = sfasfb_tensors[i]
            sfa_p, sfb_p = sfasfb_reordered_tensors[i]
            m, n, _k, _l = problem_sizes[i]

            m_int = int(m)
            n_int = int(n)

            if (not a.is_contiguous()) or (not b.is_contiguous()) or (not c.is_contiguous()):
                raise RuntimeError("grouped fast path requires contiguous a/b/c")

            c_tmp = c
            a_u8 = _as_u8(a)
            b_u8 = _as_u8(b)

            m_pad = ((m_int + 127) // 128) * 128
            if a_u8.size(0) != m_pad:
                a_pad = _get_scratch_a_grouped(a_u8.device, i, m_pad, int(a_u8.size(1)))
                a_pad[: a_u8.size(0)].copy_(a_u8)
            else:
                a_pad = a_u8

            if _FORCE_RAW_SF:
                sfa2 = _as_u8(sfa[..., 0]).contiguous()
                sfb2 = _as_u8(sfb[..., 0]).contiguous()
                sfa_arg = _reorder_scale_from_raw(sfa2, m_pad)
                sfb_arg = _reorder_scale_from_raw(sfb2, ((n_int + 127) // 128) * 128)
            else:
                _must_sfp_layout(sfa_p)
                _must_sfp_layout(sfb_p)
                sfa_arg = sfa_p
                sfb_arg = sfb_p

            a_list.append(a_pad)
            b_list.append(b_u8)
            sfa_list.append(sfa_arg)
            sfb_list.append(sfb_arg)
            c_list.append(c_tmp)

        gemm_grouped(a_list, b_list, sfa_list, sfb_list, c_list, _FORCE_BN64)
        return c_list

    for i in range(g):
        a, b, c = abc_tensors[i]
        sfa, sfb = sfasfb_tensors[i]
        sfa_p, sfb_p = sfasfb_reordered_tensors[i]
        m, n, k, l = problem_sizes[i]

        m_int = int(m)
        n_int = int(n)
        k_int = int(k)
        l_int = int(l)

        c_out = c
        if not c_out.is_contiguous():
            c_tmp = torch.empty_like(c_out, memory_format=torch.contiguous_format)
        else:
            c_tmp = c_out

        if l_int == 1:
            a_u8 = _as_u8(a).contiguous()
            b_u8 = _as_u8(b).contiguous()

            m_pad = ((m_int + 127) // 128) * 128
            if a_u8.size(0) != m_pad:
                a_pad = _get_scratch_a(a_u8.device, m_pad, int(a_u8.size(1)))
                a_pad[: a_u8.size(0)].copy_(a_u8)
            else:
                a_pad = a_u8

            if _FORCE_RAW_SF:
                sfa2 = _as_u8(sfa[..., 0]).contiguous()
                sfb2 = _as_u8(sfb[..., 0]).contiguous()
                sfa_arg = _reorder_scale_from_raw(sfa2, m_pad)
                sfb_arg = _reorder_scale_from_raw(sfb2, ((n_int + 127) // 128) * 128)
            else:
                _must_sfp_layout(sfa_p)
                _must_sfp_layout(sfb_p)
                sfa_arg = sfa_p
                sfb_arg = sfb_p

            gemm(a_pad, b_u8, sfa_arg, sfb_arg, c_tmp, m_int, n_int, k_int)
        else:
            for li in range(l_int):
                a2 = _as_u8(a[..., li]).contiguous().unsqueeze(-1)
                b2 = _as_u8(b[..., li]).contiguous().unsqueeze(-1)

                m_pad = ((m_int + 127) // 128) * 128
                if a2.size(0) != m_pad:
                    a_pad = _get_scratch_a(a2.device, m_pad, int(a2.size(1)))
                    a_pad[: a2.size(0)].copy_(a2)
                else:
                    a_pad = a2

                sfa2 = _as_u8(sfa[..., li]).contiguous()
                sfb2 = _as_u8(sfb[..., li]).contiguous()
                sfa_r = _reorder_scale_from_raw(sfa2, m_pad)
                sfb_r = _reorder_scale_from_raw(sfb2, ((n_int + 127) // 128) * 128)

                c2 = torch.empty((m_int, n_int, 1), device=c_tmp.device, dtype=torch.float16)
                gemm(a_pad, b2, sfa_r, sfb_r, c2, m_int, n_int, k_int)
                c_tmp[..., li].copy_(c2[..., 0])

        if c_tmp is not c_out:
            c_out.copy_(c_tmp)
        outs.append(c_out)

    return outs


__all__ = ["custom_kernel"]