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https://github.com/huggingface/candle.git
synced 2025-06-15 10:26:33 +00:00
Sketch the stable-lm model. (#1045)
This commit is contained in:
Laurent Mazare
@ -12,6 +12,7 @@ pub mod quantized_mixformer;
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pub mod quantized_t5;
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pub mod segment_anything;
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pub mod stable_diffusion;
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pub mod stable_lm;
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pub mod t5;
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pub mod whisper;
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pub mod with_tracing;
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364
candle-transformers/src/models/stable_lm.rs
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364
candle-transformers/src/models/stable_lm.rs
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@ -0,0 +1,364 @@
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#![allow(unused)]
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use crate::models::with_tracing::{linear_no_bias, Linear};
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use candle::{DType, Device, Module, Result, Tensor, D};
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use candle_nn::{Activation, LayerNorm, VarBuilder};
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use std::sync::Arc;
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// https://huggingface.co/stabilityai/stablelm-3b-4e1t/blob/main/configuration_stablelm_epoch.py
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#[derive(Debug, Clone, PartialEq)]
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pub struct Config {
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pub(crate) vocab_size: usize,
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pub(crate) intermediate_size: usize,
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pub(crate) hidden_size: usize,
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pub(crate) num_hidden_layers: usize,
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pub(crate) num_attention_heads: usize,
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pub(crate) num_key_value_heads: usize,
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pub(crate) hidden_act: Activation,
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pub(crate) rope_pct: f64,
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pub(crate) rope_theta: f64,
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pub(crate) max_position_embeddings: usize,
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pub(crate) norm_eps: f64,
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pub(crate) use_cache: bool,
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}
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impl Config {
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pub fn stablelm_3b_4e1t() -> Self {
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Self {
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vocab_size: 50304,
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intermediate_size: 6912,
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hidden_size: 2560,
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num_hidden_layers: 32,
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num_attention_heads: 32,
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num_key_value_heads: 32,
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hidden_act: Activation::Silu,
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rope_pct: 0.25,
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rope_theta: 10_000.,
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max_position_embeddings: 4096,
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norm_eps: 1e-5,
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use_cache: true,
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}
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}
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fn head_dim(&self) -> usize {
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self.hidden_size / self.num_attention_heads
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}
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fn rotary_ndims(&self) -> usize {
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(self.head_dim() as f64 * self.rope_pct) as usize
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}
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fn num_kv_groups(&self) -> usize {
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self.num_attention_heads / self.num_key_value_heads
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}
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}
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#[derive(Debug)]
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struct RotaryEmbedding {
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sin: Tensor,
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cos: Tensor,
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}
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fn rotate_half(xs: &Tensor) -> Result<Tensor> {
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let xs = xs.chunk(2, D::Minus1)?;
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Tensor::cat(&[&xs[1].neg()?, &xs[0]], D::Minus1)
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}
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impl RotaryEmbedding {
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fn new(dtype: DType, cfg: &Config, dev: &Device) -> Result<Self> {
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let dim = cfg.rotary_ndims();
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let max_seq_len = cfg.max_position_embeddings;
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let inv_freq: Vec<_> = (0..dim)
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.step_by(2)
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.map(|i| 1f32 / cfg.rope_theta.powf(i as f64 / dim as f64) as f32)
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.collect();
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let inv_freq_len = inv_freq.len();
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let inv_freq = Tensor::from_vec(inv_freq, (1, inv_freq_len), dev)?.to_dtype(dtype)?;
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let t = Tensor::arange(0u32, max_seq_len as u32, dev)?
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.to_dtype(dtype)?
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.reshape((max_seq_len, 1))?;
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let freqs = t.matmul(&inv_freq)?;
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let freqs = Tensor::cat(&[&freqs, &freqs], D::Minus1)?;
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Ok(Self {
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sin: freqs.sin()?,
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cos: freqs.cos()?,
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})
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}
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fn apply_rotary_emb_qkv(
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&self,
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q: &Tensor,
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k: &Tensor,
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seqlen_offset: usize,
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) -> Result<(Tensor, Tensor)> {
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let (_b_sz, _h, seq_len, _n_embd) = q.dims4()?;
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let cos = self.cos.narrow(0, seqlen_offset, seq_len)?;
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let sin = self.sin.narrow(0, seqlen_offset, seq_len)?;
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let cos = cos.unsqueeze(0)?.unsqueeze(0)?; // (1, 1, seq_len, dim)
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let sin = sin.unsqueeze(0)?.unsqueeze(0)?; // (1, 1, seq_len, dim)
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let q_embed = (q.broadcast_mul(&cos)? + rotate_half(q)?.broadcast_mul(&sin))?;
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let k_embed = (k.broadcast_mul(&cos)? + rotate_half(k)?.broadcast_mul(&sin))?;
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Ok((q_embed, k_embed))
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}
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}
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#[derive(Debug)]
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#[allow(clippy::upper_case_acronyms)]
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struct MLP {
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gate_proj: Linear,
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up_proj: Linear,
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down_proj: Linear,
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act_fn: Activation,
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}
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impl MLP {
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fn new(cfg: &Config, vb: VarBuilder) -> Result<Self> {
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let hidden_sz = cfg.hidden_size;
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let intermediate_sz = cfg.intermediate_size;
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let gate_proj = linear_no_bias(hidden_sz, intermediate_sz, vb.pp("gate_proj"))?;
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let up_proj = linear_no_bias(hidden_sz, intermediate_sz, vb.pp("up_proj"))?;
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let down_proj = linear_no_bias(intermediate_sz, hidden_sz, vb.pp("down_proj"))?;
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Ok(Self {
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gate_proj,
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up_proj,
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down_proj,
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act_fn: cfg.hidden_act,
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})
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}
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}
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impl Module for MLP {
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fn forward(&self, xs: &Tensor) -> Result<Tensor> {
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let lhs = xs.apply(&self.gate_proj)?.apply(&self.act_fn)?;
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let rhs = xs.apply(&self.up_proj)?;
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(lhs * rhs)?.apply(&self.down_proj)
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}
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}
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#[derive(Debug)]
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struct Attention {
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q_proj: Linear,
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k_proj: Linear,
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v_proj: Linear,
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o_proj: Linear,
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num_heads: usize,
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num_kv_heads: usize,
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num_kv_groups: usize,
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head_dim: usize,
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hidden_size: usize,
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rotary_emb: Arc<RotaryEmbedding>,
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kv_cache: Option<(Tensor, Tensor)>,
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use_cache: bool,
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}
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impl Attention {
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fn new(rotary_emb: Arc<RotaryEmbedding>, cfg: &Config, vb: VarBuilder) -> Result<Self> {
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let hidden_sz = cfg.hidden_size;
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let head_dim = cfg.head_dim();
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let num_heads = cfg.num_attention_heads;
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let num_kv_heads = cfg.num_key_value_heads;
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let q_proj = linear_no_bias(hidden_sz, num_heads * head_dim, vb.pp("q_proj"))?;
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let k_proj = linear_no_bias(hidden_sz, num_kv_heads * head_dim, vb.pp("k_proj"))?;
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let v_proj = linear_no_bias(hidden_sz, num_kv_heads * head_dim, vb.pp("v_proj"))?;
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let o_proj = linear_no_bias(num_heads * head_dim, hidden_sz, vb.pp("o_proj"))?;
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Ok(Self {
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q_proj,
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k_proj,
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v_proj,
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o_proj,
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num_heads,
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num_kv_heads,
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num_kv_groups: cfg.num_kv_groups(),
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head_dim,
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hidden_size: hidden_sz,
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rotary_emb,
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kv_cache: None,
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use_cache: cfg.use_cache,
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})
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}
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fn repeat_kv(&self, xs: Tensor) -> Result<Tensor> {
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let n_rep = self.num_kv_groups;
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if n_rep == 1 {
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Ok(xs)
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} else {
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let (b_sz, num_kv_heads, seq_len, head_dim) = xs.dims4()?;
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xs.unsqueeze(2)?
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.expand((b_sz, num_kv_heads, n_rep, seq_len, head_dim))?
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.reshape((b_sz, num_kv_heads * n_rep, seq_len, head_dim))
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}
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}
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fn forward(
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&mut self,
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xs: &Tensor,
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attention_mask: Option<&Tensor>,
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seqlen_offset: usize,
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) -> Result<Tensor> {
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let (b_sz, q_len, _) = xs.dims3()?;
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let query_states = self.q_proj.forward(xs)?;
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let key_states = self.k_proj.forward(xs)?;
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let value_states = self.v_proj.forward(xs)?;
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let query_states = query_states
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.reshape((b_sz, q_len, self.num_heads, self.head_dim))?
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.transpose(1, 2)?;
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let key_states = key_states
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.reshape((b_sz, q_len, self.num_kv_heads, self.head_dim))?
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.transpose(1, 2)?;
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let value_states = value_states
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.reshape((b_sz, q_len, self.num_kv_heads, self.head_dim))?
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.transpose(1, 2)?;
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let (query_states, key_states) =
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self.rotary_emb
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.apply_rotary_emb_qkv(&query_states, &key_states, seqlen_offset)?;
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let (key_states, value_states) = match &self.kv_cache {
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None => (key_states, value_states),
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Some((prev_k, prev_v)) => {
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let key_states = Tensor::cat(&[prev_k, &key_states], 2)?;
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let value_states = Tensor::cat(&[prev_v, &value_states], 2)?;
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(key_states, value_states)
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}
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};
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if self.use_cache {
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self.kv_cache = Some((key_states.clone(), value_states.clone()));
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}
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let key_states = self.repeat_kv(key_states)?;
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let value_states = self.repeat_kv(value_states)?;
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let attn_output = {
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let scale = 1f64 / f64::sqrt(self.head_dim as f64);
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let attn_weights = (query_states.matmul(&key_states.transpose(2, 3)?)? * scale)?;
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let attn_weights = match attention_mask {
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None => attn_weights,
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Some(mask) => attn_weights.broadcast_add(mask)?,
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};
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let attn_weights = candle_nn::ops::softmax_last_dim(&attn_weights)?;
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attn_weights.matmul(&value_states)?
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};
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attn_output
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.transpose(1, 2)?
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.reshape((b_sz, q_len, self.hidden_size))?
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.apply(&self.o_proj)
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}
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}
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#[derive(Debug)]
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struct DecoderLayer {
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self_attn: Attention,
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mlp: MLP,
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input_layernorm: LayerNorm,
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post_attention_layernorm: LayerNorm,
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}
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impl DecoderLayer {
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fn new(rotary_emb: Arc<RotaryEmbedding>, cfg: &Config, vb: VarBuilder) -> Result<Self> {
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let self_attn = Attention::new(rotary_emb, cfg, vb.pp("self_attn"))?;
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let mlp = MLP::new(cfg, vb.pp("mlp"))?;
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let input_layernorm =
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candle_nn::layer_norm(cfg.hidden_size, cfg.norm_eps, vb.pp("input_layernorm"))?;
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let post_attention_layernorm = candle_nn::layer_norm(
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cfg.hidden_size,
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cfg.norm_eps,
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vb.pp("post_attention_layernorm"),
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)?;
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Ok(Self {
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self_attn,
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mlp,
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input_layernorm,
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post_attention_layernorm,
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})
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}
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fn forward(
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&mut self,
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xs: &Tensor,
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attention_mask: Option<&Tensor>,
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seqlen_offset: usize,
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) -> Result<Tensor> {
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let residual = xs;
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let xs = self.input_layernorm.forward(xs)?;
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let xs = self.self_attn.forward(&xs, attention_mask, seqlen_offset)?;
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let xs = (xs + residual)?;
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let residual = &xs;
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let xs = xs.apply(&self.post_attention_layernorm)?.apply(&self.mlp)?;
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residual + xs
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}
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}
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#[derive(Debug)]
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pub struct Model {
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embed_tokens: candle_nn::Embedding,
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layers: Vec<DecoderLayer>,
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norm: LayerNorm,
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lm_head: Linear,
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device: Device,
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dtype: DType,
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}
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impl Model {
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pub fn new(cfg: &Config, vb: VarBuilder) -> Result<Self> {
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let vb_m = vb.pp("model");
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let embed_tokens =
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candle_nn::embedding(cfg.vocab_size, cfg.hidden_size, vb_m.pp("embed_tokens"))?;
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let rotary_emb = Arc::new(RotaryEmbedding::new(vb.dtype(), cfg, vb_m.device())?);
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let mut layers = Vec::with_capacity(cfg.num_hidden_layers);
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let vb_l = vb_m.pp("layers");
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for layer_idx in 0..cfg.num_hidden_layers {
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let layer = DecoderLayer::new(rotary_emb.clone(), cfg, vb_l.pp(layer_idx))?;
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layers.push(layer)
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}
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let norm = candle_nn::layer_norm(cfg.hidden_size, cfg.norm_eps, vb_m.pp("norm"))?;
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let lm_head = linear_no_bias(cfg.hidden_size, cfg.vocab_size, vb.pp("lm_head"))?;
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Ok(Self {
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embed_tokens,
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layers,
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norm,
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lm_head,
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device: vb.device().clone(),
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dtype: vb.dtype(),
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})
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}
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fn prepare_decoder_attention_mask(
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&self,
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b_size: usize,
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tgt_len: usize,
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seqlen_offset: usize,
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) -> Result<Tensor> {
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// Sliding window mask?
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let mask: Vec<_> = (0..tgt_len)
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.flat_map(|i| (0..tgt_len).map(move |j| if i < j { f32::NEG_INFINITY } else { 0. }))
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.collect();
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let mask = Tensor::from_slice(&mask, (tgt_len, tgt_len), &self.device)?;
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let mask = if seqlen_offset > 0 {
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let mask0 = Tensor::zeros((tgt_len, seqlen_offset), DType::F32, &self.device)?;
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Tensor::cat(&[&mask0, &mask], D::Minus1)?
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} else {
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mask
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};
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mask.expand((b_size, 1, tgt_len, tgt_len + seqlen_offset))?
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.to_dtype(self.dtype)
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}
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pub fn forward(&mut self, input_ids: &Tensor, seqlen_offset: usize) -> Result<Tensor> {
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let (b_size, seq_len) = input_ids.dims2()?;
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let attention_mask = if seq_len <= 1 {
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None
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} else {
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let mask = self.prepare_decoder_attention_mask(b_size, seq_len, seqlen_offset)?;
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Some(mask)
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};
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let mut xs = self.embed_tokens.forward(input_ids)?;
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for layer in self.layers.iter_mut() {
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xs = layer.forward(&xs, attention_mask.as_ref(), seqlen_offset)?
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}
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xs.narrow(1, seq_len - 1, 1)?
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.apply(&self.norm)?
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.apply(&self.lm_head)
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}
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}
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