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| import torch |
| from einops import rearrange |
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| def torch_simple_gla(q, k, v, g, chunk_size=64): |
| q = rearrange(q, 'b h (n c) d -> b h n c d', c = chunk_size) * (q.shape[-1] ** -0.5) |
| k = rearrange(k, 'b h (n c) d -> b h n c d', c = chunk_size) |
| v = rearrange(v, 'b h (n c) d -> b h n c d', c = chunk_size) |
| g = rearrange(g, 'b h (n c) -> b h n c', c = chunk_size) |
| g = g.cumsum(-1) |
| kv = k.transpose(-1, -2) @ (v * (-g + g[:, :, :, -1, None]).exp()[..., None]) |
| S = torch.zeros_like(kv) |
|
|
| for i in range(1, g.shape[-2]): |
| S[:, :, i] = S[:, :, i-1].clone() * g[:, :, i-1, -1, None, None].exp() + kv[:, :, i-1] |
| |
| inter = (q * g[..., None].exp()) @ S |
| attn = q @ k.transpose(-1, -2) |
| attn = attn * (g[..., None] - g[..., None, :]).exp() |
| attn = attn.masked_fill(torch.triu(torch.ones(chunk_size, chunk_size, dtype=bool, device=q.device), diagonal=1), 0) |
| intra = attn @ v |
| o = inter + intra |
| return rearrange(o, 'b h n c d -> b h (n c) d') |
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|
| def torch_simple_gla_recurrent(q, k, v, g, chunk_size=64): |
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| B, H, T, DK = q.shape |
| q = q * (DK ** -0.5) |
| _, _, _, DV = v.shape |
| S = torch.zeros(B, H, DK, DV).to(q) |
| o = torch.zeros(B, H, T, DV).to(q) |
| for i in range(T): |
| gate = g[:, :, i].exp() |
| key = k[:, :, i] |
| value = v[:, :, i] |
| kv = key.unsqueeze(-1) * value.unsqueeze(-2) |
| S = S.clone() * gate.unsqueeze(-1).unsqueeze(-1) + kv |
| q_i = q[:, :, i, :] |
| o_i = (q_i.unsqueeze(-1) * S).sum(-2) |
| o[:, :, i] = o_i |
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| return o |
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