MPT alibi fixes. (#1120)

* MPT alibi fixes.

* Some more fixes.

* Finally get the model to return some sensible outputs.

* Add a readme.

candle-examples/examples/replit-code/README.md

@@ -0,0 +1,45 @@
+# candle-replit-code: code completion specialized model.
+
+[replit-code-v1_5-3b](https://huggingface.co/replit/replit-code-v1_5-3b) is a
+language model specialized for code completion. This model uses 3.3B parameters
+in `bfloat16` (so the GPU version will only work on recent nvidia cards).
+
+## Running some example
+
+```bash
+cargo run --example replit-code --release -- --prompt 'def fibonacci(n): '
+```
+This produces the following output which actually doesn't generate the fibonacci
+series properly.
+
+```
+def fibonacci(n):  # write Fibonacci series up to n
+    """Print a Fibonacci series up to n."""
+
+    assert type(n) == int, "n must be an integer"
+    
+    if (type(fib_list)==None or len==0 ):
+        fib_list = [1]
+        
+    for i in range((len-2)):  # start at 2nd element of list and go until end. 
+        n += 1
+        
+        print("Fibonacci number",n,"is:",i)
+        
+def main():
+    """Call the functions."""
+
+    userInput=input('Enter a positive integer: ')
+    
+    fibonacci(userInput)
+    
+
+
+    
+    
+    
+
+if __name__ == '__main__':  # only run if this file is called directly. 
+    print("This program prints out Fibonacci numbers.")
+    main()
+```

candle-examples/examples/replit-code/main.rs

@@ -139,7 +139,7 @@ struct Args {
     seed: u64,
 
     /// The length of the sample to generate (in tokens).
-    #[arg(long, short = 'n', default_value_t = 100)]
+    #[arg(long, short = 'n', default_value_t = 1000)]
     sample_len: usize,
 
     #[arg(long)]

candle-transformers/src/models/mpt.rs

@@ -103,23 +103,25 @@ impl GroupedQueryAttention {
                 (k, v)
             }
         };
-        let key = repeat_kv(key, self.n_heads / self.kv_n_heads)?;
-        let value = repeat_kv(value, self.n_heads / self.kv_n_heads)?;
+        self.kv_cache = Some((key.clone(), value.clone()));
+        let query = query.contiguous()?;
+        let key = repeat_kv(key, self.n_heads / self.kv_n_heads)?.contiguous()?;
+        let value = repeat_kv(value, self.n_heads / self.kv_n_heads)?.contiguous()?;
         let attn_weights = (query.matmul(&key)? * self.softmax_scale)?;
         let attn_bias = {
             let s_q = query.dim(D::Minus2)?;
             let s_k = key.dim(D::Minus1)?;
             let (_, _, a_q, a_k) = self.attn_bias.dims4()?;
-            self.attn_bias
-                .narrow(2, a_q - s_q, s_q)?
-                .narrow(3, a_k - s_k, s_k)?
+            let start_q = a_q.saturating_sub(s_q);
+            let start_k = a_k.saturating_sub(s_k);
+            self.attn_bias.i((.., .., start_q.., start_k..))?
         };
-        let attn_weights = (attn_weights + attn_bias)?;
+        let attn_weights = attn_weights.broadcast_add(&attn_bias)?;
         let attn_weights = match mask {
             None => attn_weights,
             Some(mask) => masked_fill(
                 &attn_weights,
-                &mask.broadcast_left(b_size * self.n_heads)?,
+                &mask.broadcast_as(attn_weights.shape())?,
                 f32::NEG_INFINITY,
             )?,
         };
@@ -128,7 +130,8 @@ impl GroupedQueryAttention {
             .matmul(&value)?
             .transpose(1, 2)?
             .flatten_from(D::Minus2)?;
-        attn_output.apply(&self.out_proj)
+        let out = attn_output.apply(&self.out_proj)?;
+        Ok(out)
     }
 }
 
@@ -199,7 +202,7 @@ impl MPTBlock {
         let xs = self.attn.forward(&xs, mask)?;
         let xs = (xs + residual)?;
         let residual = &xs;
-        let xs = xs.apply(&self.norm2)?.apply(&self.ffn);
+        let xs = xs.apply(&self.norm2)?.apply(&self.ffn)?;
         xs + residual
     }
 }
@@ -275,12 +278,15 @@ impl Model {
             Some(get_mask(seq_len, xs.device())?)
         };
         for block in self.blocks.iter_mut() {
-            xs = block.forward(&xs, mask.as_ref())?
+            xs = block.forward(&xs, mask.as_ref())?;
         }
-        xs.narrow(1, seq_len - 1, 1)?
+        let xs = xs.apply(&self.norm_f)?;
+        let logits = xs
+            .narrow(1, seq_len - 1, 1)?
             .squeeze(1)?
             .matmul(&self.wte.embeddings().t()?)?
-            .squeeze(1)
+            .squeeze(1)?;
+        Ok(logits)
     }
 }