# -*- coding: utf-8 -*- # Copyright (c) 2023-2025, Songlin Yang, Yu Zhang import triton import triton.language as tl from fla.ops.utils.op import exp, log @triton.autotune( configs=[ triton.Config({'BT': BT}, num_warps=num_warps) for BT in [16, 32, 64] for num_warps in [2, 4, 8] ], key=['S'] ) @triton.jit(do_not_specialize=['T']) def logcumsumexp_fwd_kernel( s, z, T, S: tl.constexpr, BT: tl.constexpr ): i_bh = tl.program_id(0) o_i = tl.arange(0, BT) m_s = tl.where(o_i[:, None] >= o_i[None, :], 1., 0.) b_mp = tl.full([S,], float('-inf'), dtype=tl.float32) b_zp = tl.zeros([S,], dtype=tl.float32) for i_t in range(tl.cdiv(T, BT)): p_s = tl.make_block_ptr(s + i_bh * T*S, (T, S), (S, 1), (i_t * BT, 0), (BT, S), (1, 0)) p_z = tl.make_block_ptr(z + i_bh * T*S, (T, S), (S, 1), (i_t * BT, 0), (BT, S), (1, 0)) # [BT, S] b_s = tl.load(p_s, boundary_check=(0, 1)).to(tl.float32) # [S,] b_mc = tl.max(b_s, 0) b_mc = tl.maximum(b_mp, b_mc) b_zp = b_zp * exp(b_mp - b_mc) # [BT, S] b_s = exp(b_s - b_mc) b_z = tl.dot(m_s, b_s, allow_tf32=False) + b_zp # [S,] b_zc = tl.max(b_z, 0) b_mp = b_mc b_zp = b_zc # [BT, BS] # small eps to prevent underflows b_z = log(tl.where(b_z != 0, b_z, 1e-20)) + b_mc tl.store(p_z, b_z.to(p_z.dtype.element_ty), boundary_check=(0, 1))