Update modeling_pharia.py

Adds loss computation for Pharia model

modeling_pharia.py

@@ -764,9 +764,22 @@ class PhariaForCausalLM(PhariaPreTrainedModel):
 
         hidden_states = outputs[0]
         logits = self.lm_head(hidden_states)
-
+        loss = 0.0
+        if labels is not None:
+            # Shift logits and labels for causal language modeling
+            shift_logits = logits[..., :-1, :].contiguous()
+            shift_labels = outputs['labels'][..., 1:].contiguous()
+    
+            # Flatten the tokens
+            shift_logits = shift_logits.view(-1, shift_logits.size(-1))
+            shift_labels = shift_labels.view(-1)
+    
+            # Compute loss
+            loss_fct = torch.nn.CrossEntropyLoss(ignore_index=1)  # Pad token ID for Pharia is 1
+            loss = loss_fct(shift_logits, shift_labels)    
+        
         return CausalLMOutputWithPast(
-            loss=0.0,
+            loss=loss,
             logits=logits,
             past_key_values=outputs.past_key_values,
             hidden_states=outputs.hidden_states,