fix typo and handle negative dims

Author: llFreetimell

tico/passes/convert_permute_to_reshape.py

@@ -63,17 +63,18 @@ def call(self, exported_program: ExportedProgram) -> PassResult:
             dims = args.dims
 
             input_shape = extract_shape(input)
+            normalized_dims = [(d if d >= 0 else d + len(input_shape)) for d in dims]
 
             # When permute dims with non-1 values have same order,
             # we can replace permute to reshape
             #
             # For example, if
             # - input.shape = [1, x, 1, y]
             # - torch.permute(input, [1, 2, 3, 0])
-            # then permute dims 2 and 0 keeps same order for 'x' and 'y'.
+            # then permute dims 1 and 3 keeps same order for 'x' and 'y'.
             is_same_order = True
             last_dim = -1
-            for dim in dims:
+            for dim in normalized_dims:
                 if input_shape[dim] == 1:
                     continue
 
@@ -88,7 +89,7 @@ def call(self, exported_program: ExportedProgram) -> PassResult:
                     reshape = create_node(
                         graph,
                         torch.ops.aten.reshape.default,
-                        args=(input, [input_shape[dim] for dim in dims]),
+                        args=(input, [input_shape[dim] for dim in normalized_dims]),
                         origin=node,
                     )