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Fix the rotary embeddings for the new phi implementation. #1582

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merged 4 commits into from
Jan 13, 2024
Merged

Fix the rotary embeddings for the new phi implementation. #1582

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f8cc0ba
Fix the rotary embeddings for the new phi implementation.
LaurentMazare Jan 13, 2024
81422af
Match the activation.
LaurentMazare Jan 13, 2024
816c114
KV cache fix.
LaurentMazare Jan 13, 2024
1602cc4
Use the config activation function.
LaurentMazare Jan 13, 2024
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34 changes: 16 additions & 18 deletions candle-transformers/src/models/phi.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -38,6 +38,7 @@ impl Config {

#[derive(Debug, Clone)]
struct RotaryEmbedding {
dim: usize,
sin: Tensor,
cos: Tensor,
}
Expand All @@ -55,29 +56,24 @@ impl RotaryEmbedding {
.to_dtype(DType::F32)?
.reshape((cfg.max_position_embeddings, 1))?;
let freqs = t.matmul(&inv_freq)?;
let emb = Tensor::cat(&[&freqs, &freqs], D::Minus1)?;
Ok(Self {
sin: freqs.sin()?,
cos: freqs.cos()?,
dim,
sin: emb.sin()?,
cos: emb.cos()?,
})
}

fn apply_rotary_emb(&self, xs: &Tensor, seqlen_offset: usize) -> Result<Tensor> {
let (_b_size, seqlen, _, _headdim) = xs.dims4()?;
let (_rotary_seqlen, rotary_dim) = self.cos.dims2()?;
let rotary_dim = rotary_dim * 2;
let xs_rot = xs.i((.., .., .., ..rotary_dim))?;
let xs_pass = xs.i((.., .., .., rotary_dim..))?;
let (_b_size, _num_heads, seq_len, _headdim) = xs.dims4()?;
let xs_rot = xs.i((.., .., .., ..self.dim))?;
let xs_pass = xs.i((.., .., .., self.dim..))?;
let xs12 = xs_rot.chunk(2, D::Minus1)?;
let (xs1, xs2) = (&xs12[0], &xs12[1]);
let c = self.cos.narrow(0, seqlen_offset, seqlen)?.unsqueeze(1)?;
let s = self.sin.narrow(0, seqlen_offset, seqlen)?.unsqueeze(1)?;
let xs_rot = Tensor::cat(
&[
(xs1.broadcast_mul(&c)? - xs2.broadcast_mul(&s)?)?,
(xs1.broadcast_mul(&s)? + xs2.broadcast_mul(&c)?)?,
],
D::Minus1,
)?;
let c = self.cos.narrow(0, seqlen_offset, seq_len)?;
let s = self.sin.narrow(0, seqlen_offset, seq_len)?;
let rotate_half = Tensor::cat(&[&xs2.neg()?, &xs1], D::Minus1)?;
let xs_rot = (xs_rot.broadcast_mul(&c)? + rotate_half.broadcast_mul(&s)?)?;
Tensor::cat(&[&xs_rot, &xs_pass], D::Minus1)
}
}
Expand All @@ -97,6 +93,8 @@ impl MLP {
Ok(Self {
fc1,
fc2,
// This does not match the mixformers implementation where Gelu is used rather than
// GeluNew.
act: cfg.hidden_act,
})
}
Expand Down Expand Up @@ -216,7 +214,7 @@ impl Attention {
// Rotary embeddings.
let seqlen_offset = match &self.kv_cache {
None => 0,
Some((prev_k, _)) => prev_k.dim(1)?,
Some((prev_k, _)) => prev_k.dim(2)?,
};
let query_states = self
.rotary_emb
Expand Down Expand Up @@ -351,7 +349,7 @@ impl Model {
Some(get_mask(seq_len, xs.device())?)
};
for layer in self.layers.iter_mut() {
xs = layer.forward(&xs, mask.as_ref())?
xs = layer.forward(&xs, mask.as_ref())?;
}
xs.apply(&self.final_layernorm)?
.narrow(1, seq_len - 1, 1)?
Expand Down
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