Update tf.InfeedDequeueTuple -> xla_hlo.infeed legalization to insert a default sharding (device 0) to account for token result.

Compared to tf.InfeedDequeueTuple, xla_hlo.infeed has an additional token result. As number of results must match the number of shardings, a sharding is inserted at the end when legalizing to xla_hlo.infeed.

PiperOrigin-RevId: 307861971
Change-Id: I8f2828cc6036afc41a72dae88a2218771745e441

tensorflow/compiler/mlir/xla/BUILD

@@ -138,6 +138,7 @@ cc_library(
         "//tensorflow/compiler/mlir/tensorflow:lower_tf_lib",
         "//tensorflow/compiler/xla:xla_data_proto_cc",
         "//tensorflow/compiler/xla/client:padding",
+        "//tensorflow/compiler/xla/client:sharding_builder",
         "//tensorflow/core:framework",
         "//tensorflow/core/kernels:conv_grad_shape_utils",
         "@llvm-project//llvm:support",

tensorflow/compiler/mlir/xla/tests/legalize-tf.mlir

@@ -1171,17 +1171,21 @@ func @infeed_dequeue_tuple() -> (tensor<3xi32>, tensor<4xf32>) {
 
 // The following op sharding is used:
 // Proto debug string:
+//   type: TUPLE
+//   tuple_shardings {
 //     type: MAXIMAL
 //     tile_assignment_dimensions: 1
 //     tile_assignment_devices: 0
+//   }
 // Serialized string:
-//   "\08\01\1A\01\01\22\01\00"
+//   "\08\02*\08\08\01\1A\01\01\22\01\00"
 
 // CHECK-LABEL: infeed_dequeue_tuple_sharding
 func @infeed_dequeue_tuple_sharding() -> tensor<8xi32> {
   // CHECK: "xla_hlo.infeed"
-  // CHECK-SAME: xla_hlo.sharding = "type: MAXIMAL\0Atile_assignment_dimensions: 1\0Atile_assignment_devices: 0\0A"
+  // An additional sharding is added at the end to account for token result.
-  %0 = "tf.InfeedDequeueTuple"() {_XlaSharding = "\08\01\1A\01\01\22\01\00"} : () -> tensor<8xi32>
+  // CHECK-SAME: xla_hlo.sharding = "type: TUPLE\0Atuple_shardings {\0A type: MAXIMAL\0A tile_assignment_dimensions: 1\0A tile_assignment_devices: 0\0A}\0Atuple_shardings {\0A type: MAXIMAL\0A tile_assignment_dimensions: 1\0A tile_assignment_devices: 0\0A}\0A"
+  %0 = "tf.InfeedDequeueTuple"() {_XlaSharding = "\08\02*\08\08\01\1A\01\01\22\01\00"} : () -> tensor<8xi32>
   return %0 : tensor<8xi32>
 }
 

tensorflow/compiler/mlir/xla/transforms/legalize_tf.cc

@@ -46,6 +46,7 @@ limitations under the License.
 #include "tensorflow/compiler/mlir/xla/ir/hlo_utils.h"
 #include "tensorflow/compiler/mlir/xla/transforms/passes.h"
 #include "tensorflow/compiler/xla/client/padding.h"
+#include "tensorflow/compiler/xla/client/sharding_builder.h"
 #include "tensorflow/compiler/xla/xla_data.pb.h"
 #include "tensorflow/core/framework/kernel_shape_util.h"
 #include "tensorflow/core/kernels/conv_grad_shape_utils.h"
@@ -3376,9 +3377,17 @@ class ConvertInfeedDequeueTupleOp
       // _XlaSharding attribute in TF is a serialized string of the OpSharding
       // proto, so convert to a text form here.
       ::xla::OpSharding sharding_proto;
+      if (!sharding_proto.ParseFromString(op._XlaSharding().getValue().str()))
+        return failure();
+
+      // Token is a control signal and not a real data, so arbitrarily assign
+      // the token to device 0.
+      if (sharding_proto.type() == ::xla::OpSharding::TUPLE)
+        *sharding_proto.add_tuple_shardings() =
+            ::xla::sharding_builder::AssignDevice(0);
+
       std::string sharding_str;
-      if (!sharding_proto.ParseFromString(op._XlaSharding().getValue().str()) ||
+      if (!::tensorflow::protobuf::TextFormat::PrintToString(sharding_proto,
-          !::tensorflow::protobuf::TextFormat::PrintToString(sharding_proto,
                                                              &sharding_str))
         return failure();