[roll forward 2] Remove the `jax_require_devices_during_lowering flag since it was temporary. Added the semi-breaking change to Changelog.md.

Reverts b52bcc1639368069075284eefc763f824ca155f1

PiperOrigin-RevId: 590959383

CHANGELOG.md

@@ -8,6 +8,16 @@ Remember to align the itemized text with the first line of an item within a list
 
 ## jax 0.4.24
 
+* Changes
+  * JAX lowering to StableHLO does not depend on physical devices anymore.
+    If your primitive wraps custom_paritioning or JAX callbacks in the lowering
+    rule i.e. function passed to `rule` parameter of `mlir.register_lowering` then add your
+    primitive to `jax._src.dispatch.prim_requires_devices_during_lowering` set.
+    This is needed because custom_partitioning and JAX callbacks need physical
+    devices to create `Sharding`s during lowering.
+    This is a temporary state until we can create `Sharding`s without physical
+    devices.
+
 ## jaxlib 0.4.24
 
 ## jax 0.4.23 (Dec 13, 2023)

jax/_src/interpreters/pxla.py

@@ -102,12 +102,6 @@ MeshAxisName = sharding_impls.MeshAxisName
 MeshDimAssignment = Union[ShardedAxis, Replicated]
 ShardingSpec = sharding_specs.ShardingSpec
 
-# TODO(yashkatariya): Remove this flag when nvidia's use cases are fixed.
-_JAX_REQUIRE_DEVICES_DURING_LOWERING = config.DEFINE_bool(
-    "jax_require_devices_during_lowering",
-    True,
-    help="Forces physical devices to be passed during lowering to stablehlo.")
-
 ### util
 
 def identity(x): return x
@@ -1977,17 +1971,13 @@ def lower_sharding_computation(
   semantic_in_shardings = SemanticallyEqualShardings(in_shardings)  # type: ignore
   semantic_out_shardings = SemanticallyEqualShardings(out_shardings)  # type: ignore
   prim_requires_devices = dispatch.jaxpr_has_prim_requiring_devices(jaxpr)
-  materialized_da = (
-      tuple(da_object)
-      if prim_requires_devices or _JAX_REQUIRE_DEVICES_DURING_LOWERING.value
-      else None)
 
   (module, keepalive, host_callbacks, unordered_effects, ordered_effects,
    nreps, tuple_args, shape_poly_state) = _cached_lowering_to_hlo(
        closed_jaxpr, api_name, fun_name, backend, semantic_in_shardings,
        semantic_out_shardings, in_layouts, out_layouts, len(da_object),
-       materialized_da, donated_invars, name_stack, all_default_mem_kind,
-       lowering_parameters=lowering_parameters)
+       tuple(da_object) if prim_requires_devices else None, donated_invars,
+       name_stack, all_default_mem_kind, lowering_parameters=lowering_parameters)
 
   # backend and device_assignment is passed through to MeshExecutable because
   # if keep_unused=False and all in_shardings are pruned, then there is no way

tests/pjit_test.py

@@ -3802,14 +3802,9 @@ class ArrayPjitTest(jtu.JaxTestCase):
       b = jax.device_put(out_a, NamedSharding(mesh2, P('y')))
       f(b)  # lowering cache *hit*
 
-    prev_value = pxla._JAX_REQUIRE_DEVICES_DURING_LOWERING.value
-    try:
-      jax.config.update('jax_require_devices_during_lowering', False)
-      with jtu.count_jit_and_pmap_compiles() as count:
-        g(np.arange(8))
-      self.assertEqual(count[0], 1)
-    finally:
-      jax.config.update('jax_require_devices_during_lowering', prev_value)
+    with jtu.count_jit_and_pmap_compiles() as count:
+      g(np.arange(8))
+    self.assertEqual(count[0], 1)
 
   def test_lowering_cache_miss_different_devices_and_sharding(self):
     if jax.device_count() < 4: