Support for CumSum in ONNX models. (#1340)

candle-onnx/src/eval.rs

@@ -741,6 +741,25 @@ pub fn simple_eval(
                 let output = input.to_dtype(dtype)?;
                 values.insert(node.output[0].clone(), output);
             }
+            // https://github.com/onnx/onnx/blob/main/docs/Operators.md#CumSum
+            "CumSum" => {
+                let exclusive = get_attr_opt::<i64>(node, "exclusive")?
+                    .copied()
+                    .unwrap_or(0);
+                let reverse = get_attr_opt::<i64>(node, "reverse")?.copied().unwrap_or(0);
+                if exclusive != 0 {
+                    bail!("only exclusive == 0 is supported in CumSum")
+                }
+                if reverse != 0 {
+                    bail!("only reverse == 0 is supported in CumSum")
+                }
+                let input = get(&node.input[0])?;
+                let axis = get(&node.input[1])?
+                    .to_dtype(DType::U32)?
+                    .to_vec0::<u32>()?;
+                let output = input.cumsum(axis as usize)?;
+                values.insert(node.output[0].clone(), output);
+            }
             op_type => bail!("unsupported op_type {op_type} for op {node:?}"),
         }
     }