Makes Optimizer._zeros_slot() copy XLA sharding from variable.

Adds a test to confirm that Adam's slots are sharded the same way as corresponding variables.

PiperOrigin-RevId: 355176017
Change-Id: I8776bd8e0a70d812230b6de6041d752387706456

tensorflow/python/training/adam_test.py

@@ -20,6 +20,7 @@ from __future__ import print_function
 
 import numpy as np
 
+from tensorflow.compiler.xla.experimental.xla_sharding import xla_sharding
 from tensorflow.python.client import session
 from tensorflow.python.eager import context
 from tensorflow.python.framework import constant_op
@@ -377,6 +378,45 @@ class AdamOptimizerTest(test.TestCase):
       # for v1 and v2 respectively.
       self.assertEqual(6, len({id(v) for v in opt.variables()}))
 
+  @test_util.deprecated_graph_mode_only
+  def testXlaSharding(self):
+    dtype = dtypes.float32
+    with self.session(graph=ops.Graph()):
+      # Initialize variables for numpy implementation.
+      var0_np = np.array([1.0, 2.0], dtype=dtype.as_numpy_dtype)
+      grads0_np = np.array([0.1, 0.1], dtype=dtype.as_numpy_dtype)
+      var1_np = np.array([3.0, 4.0], dtype=dtype.as_numpy_dtype)
+      grads1_np = np.array([0.01, 0.01], dtype=dtype.as_numpy_dtype)
+
+      var0 = resource_variable_ops.ResourceVariable(var0_np, name="var0")
+      var1 = resource_variable_ops.ResourceVariable(var1_np, name="var1")
+      var0, var1 = [
+          xla_sharding.mesh_split(
+              v, np.array([0, 1]), [0], use_sharding_op=False)
+          for v in (var0, var1)
+      ]
+      grads0 = constant_op.constant(grads0_np)
+      grads1 = constant_op.constant(grads1_np)
+
+      learning_rate = lambda: 0.001
+
+      opt = adam.AdamOptimizer(learning_rate=learning_rate)
+      update = opt.apply_gradients(zip([grads0, grads1], [var0, var1]))
+
+      self.evaluate(variables.global_variables_initializer())
+      self.evaluate(update)
+      # The beta accumulators are not sharded.
+      beta1_power, beta2_power = opt._get_beta_accumulators()
+      self.assertIsNone(xla_sharding.get_tensor_sharding(beta1_power))
+      self.assertIsNone(xla_sharding.get_tensor_sharding(beta2_power))
+
+      # Variables and slots are sharded.
+      for v in (var0, var1):
+        self.assertIsNotNone(xla_sharding.get_tensor_sharding(v))
+        for slot_name in ("m", "v"):
+          slot = opt.get_slot(v, slot_name)
+          self.assertIsNotNone(xla_sharding.get_tensor_sharding(slot))
+
 
 if __name__ == "__main__":
   test.main()

tensorflow/python/training/optimizer.py

@@ -1153,7 +1153,8 @@ class Optimizer(
     """
     named_slots = self._slot_dict(slot_name)
     if _var_key(var) not in named_slots:
-      new_slot_variable = slot_creator.create_zeros_slot(var, op_name)
+      new_slot_variable = slot_creator.create_zeros_slot(
+          var, op_name, copy_xla_sharding=True)
       self._restore_slot_variable(
           slot_name=slot_name, variable=var,
           slot_variable=new_slot_variable)