File size: 16,377 Bytes
306b4ac
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
# Copyright (c) 2024, Tri Dao, Albert Gu.

"""We want triton==2.1.0 or 2.2.0 for this
"""

import math
import torch
import torch.nn.functional as F

import triton
import triton.language as tl

from einops import rearrange, repeat


@triton.autotune(
    configs=[
        triton.Config({'BLOCK_SIZE': 64}),
        triton.Config({'BLOCK_SIZE': 128}),
        triton.Config({'BLOCK_SIZE': 256}),
        triton.Config({'BLOCK_SIZE': 512}),
        triton.Config({'BLOCK_SIZE': 1024}),
        triton.Config({'BLOCK_SIZE': 2048}),
    ],
    key=['dim'],
)
@triton.jit
def _state_passing_fwd_kernel(
    # Pointers to matrices
    states_ptr, out_ptr, final_states_ptr, dA_cs_ptr, initstates_ptr, seq_idx_ptr,
    # Matrix dimensions
    dim, nchunks, seqlen, chunk_size,
    # Strides
    stride_states_batch, stride_states_chunk, stride_states_head, stride_states_dim,
    stride_out_batch, stride_out_chunk, stride_out_head, stride_out_dim,
    stride_final_states_batch, stride_final_states_head, stride_final_states_dim,
    stride_dA_cs_batch, stride_dA_cs_chunk, stride_dA_cs_head,
    stride_initstates_batch, stride_initstates_head, stride_initstates_dim,
    stride_seq_idx_batch, stride_seq_idx_seqlen,
    # Meta-parameters
    HAS_INITSTATES: tl.constexpr,
    HAS_SEQ_IDX: tl.constexpr,
    BLOCK_SIZE: tl.constexpr,
):
    pid_b = tl.program_id(axis=1)
    pid_h = tl.program_id(axis=2)
    pid_m = tl.program_id(axis=0)
    states_ptr += pid_b * stride_states_batch + pid_h * stride_states_head
    dA_cs_ptr += pid_b * stride_dA_cs_batch + pid_h * stride_dA_cs_head
    out_ptr += pid_b * stride_out_batch + pid_h * stride_out_head
    final_states_ptr += pid_b * stride_final_states_batch + pid_h * stride_final_states_head
    if HAS_INITSTATES:
        initstates_ptr += pid_b * stride_initstates_batch + pid_h * stride_initstates_head
    if HAS_SEQ_IDX:
        seq_idx_ptr += pid_b * stride_seq_idx_batch

    offs_m = pid_m * BLOCK_SIZE + tl.arange(0, BLOCK_SIZE)
    states_ptrs = states_ptr + offs_m * stride_states_dim
    out_ptrs = out_ptr + offs_m * stride_out_dim
    final_states_ptrs = final_states_ptr + offs_m * stride_final_states_dim

    if not HAS_INITSTATES:
        states = tl.zeros((BLOCK_SIZE, ), dtype=tl.float32)
    else:
        initstates_ptrs = initstates_ptr + offs_m * stride_initstates_dim
        states = tl.load(initstates_ptrs, mask=offs_m < dim, other=0.0).to(tl.float32)
    tl.store(out_ptrs, states, mask=offs_m < dim)
    out_ptrs += stride_out_chunk
    seq_idx = 0
    for c in range(nchunks):
        new_states = tl.load(states_ptrs, mask=offs_m < dim, other=0.0).to(tl.float32)
        dA_cs = tl.load(dA_cs_ptr).to(tl.float32)
        scale = tl.exp(dA_cs)
        if HAS_SEQ_IDX:
            seq_idx_new = tl.load(seq_idx_ptr + (min((c + 1) * chunk_size, seqlen) - 1) * stride_seq_idx_seqlen)
            scale = tl.where(seq_idx_new == seq_idx, scale, 0.0)
            seq_idx = seq_idx_new
        states = scale * states + new_states
        if c < nchunks - 1:
            tl.store(out_ptrs, states, mask=offs_m < dim)
        else:
            tl.store(final_states_ptrs, states, mask=offs_m < dim)
        states_ptrs += stride_states_chunk
        dA_cs_ptr += stride_dA_cs_chunk
        out_ptrs += stride_out_chunk


@triton.autotune(
    configs=[
        triton.Config({'BLOCK_SIZE': 64}),
        triton.Config({'BLOCK_SIZE': 128}),
        triton.Config({'BLOCK_SIZE': 256}),
        triton.Config({'BLOCK_SIZE': 512}),
        triton.Config({'BLOCK_SIZE': 1024}),
        triton.Config({'BLOCK_SIZE': 2048}),
    ],
    key=['dim'],
)
@triton.jit
def _state_passing_bwd_kernel(
    # Pointers to matrices
    dout_ptr, out_ptr, dA_cs_ptr, dfinal_states_ptr, seq_idx_ptr,
    dstates_ptr, ddA_cs_ptr, dinitstates_ptr, states_converted_ptr,
    # Matrix dimensions
    dim, nchunks, seqlen, chunk_size,
    # Strides
    stride_dout_batch, stride_dout_chunk, stride_dout_head, stride_dout_dim,
    stride_out_batch, stride_out_chunk, stride_out_head, stride_out_dim,
    stride_dA_cs_batch, stride_dA_cs_chunk, stride_dA_cs_head,
    stride_dfinal_states_batch, stride_dfinal_states_head, stride_dfinal_states_dim,
    stride_seq_idx_batch, stride_seq_idx_seqlen,
    stride_dstates_batch, stride_dstates_chunk, stride_dstates_head, stride_dstates_dim,
    stride_ddA_cs_batch, stride_ddA_cs_chunk, stride_ddA_cs_head,
    stride_dinitstates_batch, stride_dinitstates_head, stride_dinitstates_dim,
    # Meta-parameters
    CONVERT_STATES: tl.constexpr,
    HAS_DFINAL_STATES: tl.constexpr,
    HAS_DINITSTATES: tl.constexpr,
    HAS_SEQ_IDX: tl.constexpr,
    BLOCK_SIZE: tl.constexpr,
):
    pid_b = tl.program_id(axis=1)
    pid_h = tl.program_id(axis=2)
    pid_m = tl.program_id(axis=0)
    dstates_ptr += pid_b * stride_dstates_batch + pid_h * stride_dstates_head + (nchunks - 1) * stride_dstates_chunk
    dA_cs_ptr += pid_b * stride_dA_cs_batch + pid_h * stride_dA_cs_head + (nchunks - 1) * stride_dA_cs_chunk
    ddA_cs_ptr += pid_b * stride_ddA_cs_batch + pid_h * stride_ddA_cs_head + (nchunks - 1) * stride_ddA_cs_chunk + pid_m
    out_ptr += pid_b * stride_out_batch + pid_h * stride_out_head + (nchunks - 1) * stride_out_chunk
    dout_ptr += pid_b * stride_dout_batch + pid_h * stride_dout_head + (nchunks - 1) * stride_dout_chunk
    if CONVERT_STATES:
        states_converted_ptr += pid_b * stride_out_batch + pid_h * stride_out_head + (nchunks - 1) * stride_out_chunk
    if HAS_DFINAL_STATES:
        dfinal_states_ptr += pid_b * stride_dfinal_states_batch + pid_h * stride_dfinal_states_head
    if HAS_DINITSTATES:
        dinitstates_ptr += pid_b * stride_dinitstates_batch + pid_h * stride_dinitstates_head
    if HAS_SEQ_IDX:
        seq_idx_ptr += pid_b * stride_seq_idx_batch

    offs_m = pid_m * BLOCK_SIZE + tl.arange(0, BLOCK_SIZE)
    dstates_ptrs = dstates_ptr + offs_m * stride_dstates_dim
    out_ptrs = out_ptr + offs_m * stride_out_dim
    dout_ptrs = dout_ptr + offs_m * stride_dout_dim
    if CONVERT_STATES:
        states_converted_ptrs = states_converted_ptr + offs_m * stride_out_dim

    if HAS_DFINAL_STATES:
        dstates = tl.load(dfinal_states_ptr + offs_m * stride_dfinal_states_dim, mask=offs_m < dim, other=0.0).to(tl.float32)
    else:
        dstates = tl.zeros((BLOCK_SIZE, ), dtype=tl.float32)
    tl.store(dstates_ptrs, dstates, mask=offs_m < dim)
    if HAS_SEQ_IDX:
        seq_idx = tl.load(seq_idx_ptr + (seqlen - 1) * stride_seq_idx_seqlen)
    dstates_ptrs -= stride_dstates_chunk
    for c in range(nchunks - 1):
        dA_cs = tl.load(dA_cs_ptr).to(tl.float32)
        scale = tl.exp(dA_cs)
        if HAS_SEQ_IDX:
            seq_idx_new = tl.load(seq_idx_ptr + (((nchunks - c - 1) * chunk_size - 1) * stride_seq_idx_seqlen))
            scale = tl.where(seq_idx_new == seq_idx, scale, 0.0)
            seq_idx = seq_idx_new
        out = tl.load(out_ptrs, mask=offs_m < dim, other=0.0).to(tl.float32)
        if CONVERT_STATES:
            tl.store(states_converted_ptrs, out, mask=offs_m < dim)
        ddA = tl.sum(out * dstates) * scale
        tl.store(ddA_cs_ptr, ddA)
        dout = tl.load(dout_ptrs, mask=offs_m < dim, other=0.0).to(tl.float32)
        dstates = scale * dstates + dout
        tl.store(dstates_ptrs, dstates, mask=offs_m < dim)
        dout_ptrs -= stride_dout_chunk
        dstates_ptrs -= stride_dstates_chunk
        dA_cs_ptr -= stride_dA_cs_chunk
        ddA_cs_ptr -= stride_ddA_cs_chunk
        out_ptrs -= stride_out_chunk
        if CONVERT_STATES:
            states_converted_ptrs -= stride_out_chunk
    if CONVERT_STATES:
        out = tl.load(out_ptrs, mask=offs_m < dim, other=0.0).to(tl.float32)
        tl.store(states_converted_ptrs, out, mask=offs_m < dim)
    if not HAS_DINITSTATES:
        tl.store(ddA_cs_ptr, 0.0)
    else:
        dA_cs = tl.load(dA_cs_ptr).to(tl.float32)
        scale = tl.exp(dA_cs)
        if HAS_SEQ_IDX:
            scale = tl.where(seq_idx == 0, scale, 0.0)
        out = tl.load(out_ptrs, mask=offs_m < dim, other=0.0).to(tl.float32)
        ddA = tl.sum(out * dstates) * scale
        tl.store(ddA_cs_ptr, ddA)
        dout = tl.load(dout_ptrs, mask=offs_m < dim, other=0.0).to(tl.float32)
        dstates = scale * dstates + dout
        tl.store(dinitstates_ptr + offs_m * stride_dinitstates_dim, dstates, mask=offs_m < dim)


def _state_passing_fwd(states, dA_chunk_cumsum, initial_states=None, seq_idx=None, chunk_size=None,
                       out_dtype=None):
    batch, nchunks, nheads, dim = states.shape
    assert dA_chunk_cumsum.shape == (batch, nheads, nchunks)
    if initial_states is not None:
        assert initial_states.shape == (batch, nheads, dim)
    if seq_idx is not None:
        assert chunk_size is not None
        seqlen = seq_idx.shape[-1]
        assert seq_idx.shape == (batch, seqlen)
    out_dtype = states.dtype if out_dtype is None else out_dtype
    out = torch.empty((batch, nchunks, nheads, dim), device=states.device, dtype=out_dtype)
    final_states = torch.empty((batch, nheads, dim), device=states.device, dtype=torch.float32)
    grid = lambda META: (triton.cdiv(dim, META['BLOCK_SIZE']), batch, nheads)
    with torch.cuda.device(states.device.index):
        _state_passing_fwd_kernel[grid](
            states, out, final_states, dA_chunk_cumsum, initial_states, seq_idx,
            dim, nchunks, seqlen if seq_idx is not None else 0, chunk_size if seq_idx is not None else 0,
            states.stride(0), states.stride(1), states.stride(2), states.stride(3),
            out.stride(0), out.stride(1), out.stride(2), out.stride(3),
            final_states.stride(0), final_states.stride(1), final_states.stride(2),
            dA_chunk_cumsum.stride(0), dA_chunk_cumsum.stride(2), dA_chunk_cumsum.stride(1),
            *((initial_states.stride(0), initial_states.stride(1), initial_states.stride(2))
              if initial_states is not None else (0, 0, 0)),
            *((seq_idx.stride(0), seq_idx.stride(1)) if seq_idx is not None else (0, 0)),
            HAS_INITSTATES=initial_states is not None,
            HAS_SEQ_IDX=seq_idx is not None,
        )
    return out, final_states


def _state_passing_bwd(
        states, dA_chunk_cumsum, dout, dfinal_states=None, seq_idx=None, has_initial_states=None,
        dstates_dtype=None, states_dtype=None, chunk_size=None
):
    """
    states contains the initial_states at index 0. The final states are not included in states.
    """
    batch, nchunks, nheads, dim = states.shape
    assert dA_chunk_cumsum.shape == (batch, nheads, nchunks)
    assert dout.shape == (batch, nchunks, nheads, dim)
    if seq_idx is not None:
        assert chunk_size is not None
        seqlen = seq_idx.shape[-1]
        assert seq_idx.shape == (batch, seqlen)
    dstates = torch.empty_like(dout, dtype=dstates_dtype if dstates_dtype is not None else dout.dtype)
    if states_dtype is not None and states_dtype != states.dtype:
        states_converted = torch.empty_like(states, dtype=dstates_dtype if dstates_dtype is not None else dout.dtype)
        assert states_converted.stride() == states.stride()
    else:
        states_converted = None
    if has_initial_states:
        dinitstates = torch.empty_like(dstates[:, 0])
    else:
        dinitstates = None
    if dfinal_states is not None:
        assert dfinal_states.shape == (batch, nheads, dim)
    BLOCK_SIZE_min = 64
    n_blocks = (dim + BLOCK_SIZE_min - 1) // BLOCK_SIZE_min
    ddA_chunk_cumsum = torch.empty(batch, nheads, nchunks, n_blocks,
                                    dtype=torch.float32, device=dA_chunk_cumsum.device)
    grid = lambda META: (triton.cdiv(dim, META['BLOCK_SIZE']), batch, nheads)
    with torch.cuda.device(dout.device.index):
        _state_passing_bwd_kernel[grid](
            dout, states, dA_chunk_cumsum, dfinal_states, seq_idx,
            dstates, ddA_chunk_cumsum, dinitstates, states_converted,
            dim, nchunks, seqlen if seq_idx is not None else 0, chunk_size if seq_idx is not None else 0,
            dout.stride(0), dout.stride(1), dout.stride(2), dout.stride(3),
            states.stride(0), states.stride(1), states.stride(2), states.stride(3),
            dA_chunk_cumsum.stride(0), dA_chunk_cumsum.stride(2), dA_chunk_cumsum.stride(1),
            *((dfinal_states.stride(0), dfinal_states.stride(1), dfinal_states.stride(2))
                if dfinal_states is not None else (0, 0, 0)),
            *((seq_idx.stride(0), seq_idx.stride(1)) if seq_idx is not None else (0, 0)),
            dstates.stride(0), dstates.stride(1), dstates.stride(2), dstates.stride(3),
            ddA_chunk_cumsum.stride(0), ddA_chunk_cumsum.stride(2), ddA_chunk_cumsum.stride(1),
            *((dinitstates.stride(0), dinitstates.stride(1), dinitstates.stride(2))
              if dinitstates is not None else (0, 0, 0)),
            CONVERT_STATES=states_converted is not None,
            HAS_DFINAL_STATES=dfinal_states is not None,
            HAS_DINITSTATES=dinitstates is not None,
            HAS_SEQ_IDX=seq_idx is not None,
        )
    BLOCK_SIZE_actual = _state_passing_bwd_kernel.best_config.kwargs["BLOCK_SIZE"]
    n_valid_blocks = (dim + BLOCK_SIZE_actual - 1) // BLOCK_SIZE_actual
    ddA_chunk_cumsum = ddA_chunk_cumsum[..., :n_valid_blocks].sum(dim=-1).to(dtype=dA_chunk_cumsum.dtype)
    if states_dtype is not None and states_dtype == states.dtype:
        states_converted = states
    return (dstates, ddA_chunk_cumsum, dinitstates) if states_dtype is None else (dstates, ddA_chunk_cumsum, dinitstates, states_converted)


class StatePassingFn(torch.autograd.Function):

    @staticmethod
    def forward(ctx, states, dA_chunk_cumsum, initial_states=None):
        batch, nchunks, nheads, dim = states.shape
        assert dA_chunk_cumsum.shape == (batch, nheads, nchunks)
        if states.stride(-1) != 1:
            states = states.contiguous()
        out, final_states = _state_passing_fwd(states, dA_chunk_cumsum, initial_states)
        ctx.save_for_backward(out, dA_chunk_cumsum)
        ctx.has_initial_states = initial_states is not None
        return out, final_states

    @staticmethod
    def backward(ctx, dout, dfinal_states):
        out, dA_chunk_cumsum = ctx.saved_tensors
        batch, nchunks, nheads, dim = out.shape
        assert dout.shape == (batch, nchunks, nheads, dim)
        assert dA_chunk_cumsum.shape == (batch, nheads, nchunks)
        assert dfinal_states.shape == (batch, nheads, dim)
        if dout.stride(-1) != 1:
            dout = dout.contiguous()
        dstates, ddA_chunk_cumsum, dinitstates = _state_passing_bwd(
            out, dA_chunk_cumsum, dout, dfinal_states=dfinal_states , has_initial_states=ctx.has_initial_states
        )
        return dstates, ddA_chunk_cumsum, dinitstates


def state_passing(states, dA_chunk_cumsum, initial_states=None):
    """
    Argument:
        states: (batch, nchunks, nheads, dim)
        dA_chunk_cumsum: (batch, nheads, nchunks)
        initial_states: (batch, nheads, dim)
    Return:
        out: (batch, nchunks, nheads, dim)
        final_states: (batch, nheads, dim)
    """
    return StatePassingFn.apply(states, dA_chunk_cumsum, initial_states)


def state_passing_ref(states, dA_chunk_cumsum, initial_states=None):
    """
    Argument:
        states: (batch, nchunks, nheads, dim)
        dA_chunk_cumsum: (batch, nheads, nchunks)
        initial_states: (batch, nheads, dim)
    Return:
        out: (batch, nchunks, nheads, dim)
        final_states: (batch, nheads, dim)
    """
    if initial_states is None:
        initial_states = torch.zeros_like(states[:, 0])
    states = torch.cat([rearrange(initial_states, "b h d -> b 1 h d"), states], dim=1)
    dA_chunk_cumsum = F.pad(dA_chunk_cumsum, (1, 0))
    dA_chunk_cumsum = torch.cumsum(dA_chunk_cumsum, dim=-1)
    nchunks = dA_chunk_cumsum.shape[-1]
    # (batch, nheads, nchunks, nchunks)
    dt_chunk_segment_sum = dA_chunk_cumsum[:, :, :, None] - dA_chunk_cumsum[:, :, None, :]
    # (batch, nheads, nchunks, nchunks)
    decay_chunk = torch.exp(dt_chunk_segment_sum)
    causal_mask = torch.tril(torch.ones(nchunks, nchunks, device=states.device, dtype=bool), diagonal=0)
    decay_chunk = decay_chunk.masked_fill(~causal_mask, 0)
    out = torch.einsum("bhzc,bchd->bzhd", decay_chunk.to(dtype=states.dtype), states)
    return out[:, :-1], out[:, -1]