Merge pull request #18138 from mattjj:shmap-axis-env-fix

PiperOrigin-RevId: 574540561

Author: jax authors

jax/experimental/shard_map.py

@@ -1429,7 +1429,7 @@ def _partial_eval_jaxpr_custom_rule(
   with core.extend_axis_env_nd(mesh.shape.items()):
     jaxpr_known, jaxpr_staged, unks_out, inst_out, num_res = \
         pe.partial_eval_jaxpr_custom(jaxpr, unks_in, inst_in, False, False, saveable)
-  jaxpr_known, jaxpr_staged = _add_reshapes(num_res, jaxpr_known, jaxpr_staged)
+    jaxpr_known, jaxpr_staged = _add_reshapes(num_res, jaxpr_known, jaxpr_staged)
   ins_known, _ = partition_list(unks_in, eqn.invars)
   out_binders_known, _ = partition_list(unks_out, eqn.outvars)
   _, ins_staged = partition_list(inst_in, eqn.invars)

tests/shard_map_test.py

@@ -1135,6 +1135,18 @@ def body(q, k, v):
 
     jtu.check_grads(f, (q, k, v), order=1, modes=['rev'], rtol=1e-2)
 
+  def test_axis_env_extension_regression(self):
+    def foo(x):
+      i = jax.lax.axis_index('x')
+      return jnp.exp(x) + i.astype('float')
+
+    @partial(jax.remat, policy=lambda *args, **kwargs: True)
+    def bar(x):
+      return shard_map(foo, mesh=Mesh(jax.devices(), ['x']), in_specs=(P('x'),),
+                       out_specs=P('x'), check_rep=False)(x)
+
+    jax.jit(jax.grad(lambda x: bar(x).sum()))(jnp.arange(8.))  # doesn't crash
+
 
 class FunSpec(NamedTuple):
   name: str