simplify the provenance logic to prepare for the removal of jax named…

…_shape (#1837)

numpyro/ops/provenance.py

@@ -14,7 +14,6 @@
 
 from jax.interpreters.partial_eval import trace_to_jaxpr_dynamic
 from jax.interpreters.pxla import xla_pmap_p
-import jax.numpy as jnp
 
 
 def eval_provenance(fn, **kwargs):
@@ -53,18 +52,11 @@ def eval_provenance(fn, **kwargs):
     # get provenances of flatten kwargs
     aval_kwargs = {}
     for n, v in kwargs.items():
-        aval = jax.ShapeDtypeStruct((), jnp.bool_, {"provenance": frozenset({n})})
-        aval_kwargs[n] = jax.tree.map(lambda _: aval, v)
-    aval_args, _ = jax.tree.flatten(((), aval_kwargs))
-    provenance_inputs = jax.tree.map(lambda x: x.named_shape["provenance"], aval_args)
+        aval_kwargs[n] = jax.tree.map(lambda _: frozenset({n}), v)
+    provenance_inputs, _ = jax.tree.flatten(((), aval_kwargs))
 
     provenance_outputs = track_deps_jaxpr(jaxpr, provenance_inputs)
-    out_flat = []
-    for v, p in zip(avals_out, provenance_outputs):
-        val = jax.ShapeDtypeStruct(jnp.shape(v), jnp.result_type(v), {"provenance": p})
-        out_flat.append(val)
-    out = jax.tree.unflatten(out_tree(), out_flat)
-    return jax.tree.map(lambda x: x.named_shape["provenance"], out)
+    return jax.tree.unflatten(out_tree(), provenance_outputs)
 
 
 def track_deps_jaxpr(jaxpr, provenance_inputs):