Set out_mut to None as default on from_hlo instead of in `__init_…

…_` of `MeshComputation` and correct the types too.

PiperOrigin-RevId: 611814102

jax/_src/interpreters/pxla.py

@@ -891,7 +891,7 @@ def build_execute_fun(self):
                                     self.unordered_effects,
                                     self.ordered_effects, self.keepalive,
                                     bool(self.host_callbacks),
-                                    set(range(len(input_indices))), [])
+                                    set(range(len(input_indices))), None)
     return execute_fun
 
   def load(self) -> PmapExecutable:
@@ -1155,7 +1155,7 @@ def __init__(self, xla_executable, name, backend, in_handler: InputsHandler,
                unordered_effects: list[core.Effect],
                ordered_effects: list[core.Effect], keepalive: Any,
                has_host_callbacks: bool, kept_var_idx: set[int],
-               out_mut: Sequence[int | None]):
+               out_mut: Sequence[int | None] | None):
     self.xla_executable = xla_executable
     self.name = name
     self.backend = backend
@@ -1210,7 +1210,7 @@ def __call__(self, *args):
       out = self.out_handler(out_arrays)
     else:
       out = results.consume_with_handlers(self.out_handler.handlers)
-    if not self.out_mut:
+    if self.out_mut is None:
       return out
     else:
       out_ = []
@@ -2282,7 +2282,6 @@ def lower_mesh_computation(
       host_callbacks=lowering_result.host_callbacks,
       keepalive=lowering_result.keepalive,
       kept_var_idx=set(range(len(global_in_avals))),
-      out_mut=None,
       backend=backend,
       device_assignment=_create_da_object(tuple(mesh.devices.flat)),
       committed=True,
@@ -2297,7 +2296,6 @@ class MeshComputation(stages.XlaLowering):
 
   def __init__(self, name: str, hlo: ir.Module | None,
                donated_invars: Sequence[bool], **compile_args):
-    compile_args.setdefault('out_mut', None)  # TODO(mattjj): remove default
     self._name = name
     self._hlo = hlo
     self._donated_invars = donated_invars
@@ -2763,7 +2761,7 @@ class UnloadedMeshExecutable:
   keepalive: Sequence[Any]
   host_callbacks: Sequence[Any]
   kept_var_idx: set[int]
-  out_mut: Sequence[None | int]
+  out_mut: Sequence[None | int] | None
   auto_spmd_lowering: bool
   in_layouts: Sequence[SpecifiedLayout | None]
   out_layouts: Sequence[SpecifiedLayout | None]
@@ -2802,7 +2800,7 @@ def from_hlo(name: str,
                global_out_avals: Sequence[ShapedArray],
                in_shardings: Sequence[sharding_impls.XLACompatibleSharding | AUTO],
                out_shardings: Sequence[(sharding_impls.XLACompatibleSharding | AUTO |
-                                             UnspecifiedValue)],
+                                        UnspecifiedValue)],
                spmd_lowering: bool,
                tuple_args: bool,
                auto_spmd_lowering: bool,
@@ -2811,13 +2809,13 @@ def from_hlo(name: str,
                host_callbacks: list[Any],
                keepalive: Any,
                kept_var_idx: set[int],
-               out_mut: Sequence[None | int],
                backend: xb.XlaBackend,
                device_assignment: xc.DeviceList | Sequence[xc.Device],  # type: ignore
                committed: bool,
                in_layouts: MaybeLayout,
                out_layouts: MaybeLayout,
                pmap_nreps: int = 1,
+               out_mut: Sequence[None | int] | None = None,
                shape_poly_state: mlir.ShapePolyLoweringState | None = None,
                all_default_mem_kind: bool = True,
                all_args_info: AllArgsInfo | None = None,