[Pallas TPU] Add lowerings for bf16 jnp.ceil and jnp.floor in TPU v6+

This PR is similar to jax-ml#24284

Note that `np.testing.assert_allclose()` is changed to `self.assertAllClose()` because the latter is a wrapper with bfloat16 support.

PiperOrigin-RevId: 688581914

Author: ayaka14732

tests/pallas/ops_test.py

@@ -742,7 +742,7 @@ def kernel(x_ref, o_ref):
           [jnp.abs, jnp.negative],
           ["int16", "int32", "int64", "float16", "float32", "float64"],
       ),
-      ([jnp.ceil, jnp.floor], ["float32", "float64", "int32"]),
+      ([jnp.ceil, jnp.floor], ["bfloat16", "float32", "float64", "int32"]),
       (
           [jnp.exp, jnp.exp2, jnp.sin, jnp.cos, jnp.log, jnp.sqrt],
           ["float16", "float32", "float64"],
@@ -767,8 +767,23 @@ def test_elementwise(self, fn, dtype):
     if not jax.config.x64_enabled and jnp.dtype(dtype).itemsize == 8:
       self.skipTest("64-bit types require x64_enabled")
 
-    if jtu.test_device_matches(["tpu"]) and jnp.dtype(dtype).itemsize == 2:
-      self.skipTest("16-bit types are not supported on TPU")
+    if jtu.test_device_matches(["tpu"]) and dtype in ("int16", "float16"):
+      self.skipTest("int16 and float16 are not supported on TPU")
+
+    if (
+        jtu.test_device_matches(["gpu"])
+        and fn in (jnp.ceil, jnp.floor)
+        and dtype == "bfloat16"
+    ):
+      self.skipTest(f"bfloat16 {fn.__name__} is not supported on GPU")
+
+    if (
+        jtu.test_device_matches(["tpu"])
+        and not jtu.is_device_tpu_at_least(6)
+        and fn in (jnp.ceil, jnp.floor)
+        and dtype == "bfloat16"
+    ):
+      self.skipTest(f"bfloat16 {fn.__name__} is only supported on TPU v6+")
 
     # TODO(b/370578663): implement these lowerings on TPU
     if jtu.test_device_matches(["tpu"]) and fn in (
@@ -784,7 +799,7 @@ def kernel(x_ref, o_ref):
       o_ref[:] = fn(x_ref[...])
 
     x = jnp.array([0.42, 2.4]).astype(dtype)
-    np.testing.assert_allclose(kernel(x), fn(x), rtol=1e-6)
+    self.assertAllClose(kernel(x), fn(x), rtol=1e-6)
 
   @parameterized.named_parameters(
       (f"{fn.__name__}_{dtype}", fn, dtype)
@@ -798,6 +813,13 @@ def test_elementwise_scalar(self, fn, dtype):
     if jtu.test_device_matches(["tpu"]) and jnp.dtype(dtype).itemsize == 2:
       self.skipTest("16-bit types are not supported on TPU")
 
+    if (
+        jtu.test_device_matches(["gpu"])
+        and fn in (jnp.ceil, jnp.floor)
+        and dtype == "bfloat16"
+    ):
+      self.skipTest(f"bfloat16 {fn.__name__} is not supported on GPU")
+
     if (
         jtu.test_device_matches(["tpu"])
         and fn == lax.population_count
@@ -826,7 +848,7 @@ def kernel(x_ref, o_ref):
       o_ref[1] = fn(x_ref[1])
 
     x = jnp.array([0.42, 2.4]).astype(dtype)
-    np.testing.assert_allclose(kernel(x), fn(x), rtol=1e-6)
+    self.assertAllClose(kernel(x), fn(x), rtol=1e-6)
 
   def test_abs_weak_type(self):
     # see https://github.com/jax-ml/jax/issues/23191