[XLA] Cleanup Alltoall.

- Remove unused field 'cross_replica_sum_barrier' for Alltoall.
- Update cost analysis. There's no computation in Alltoall.
- Cleanup stale TODOs.

PiperOrigin-RevId: 209814190

1 files changed, 5 insertions, 14 deletions

diff --git a/tensorflow/compiler/xla/service/hlo_instructions.cc b/tensorflow/compiler/xla/service/hlo_instructions.cc
index 36fac4a266..345ca0053a 100644
--- a/tensorflow/compiler/xla/service/hlo_instructions.cc
+++ b/tensorflow/compiler/xla/service/hlo_instructions.cc
@@ -371,11 +371,9 @@ HloAllReduceInstruction::CloneWithNewOperandsImpl(
 
 HloAllToAllInstruction::HloAllToAllInstruction(
     const Shape& shape, tensorflow::gtl::ArraySlice<HloInstruction*> operands,
-    const std::vector<ReplicaGroup>& replica_groups,
-    tensorflow::StringPiece barrier)
+    const std::vector<ReplicaGroup>& replica_groups)
     : HloInstruction(HloOpcode::kAllToAll, shape),
-      replica_groups_(replica_groups),
-      cross_replica_sum_barrier_(barrier.begin(), barrier.end()) {
+      replica_groups_(replica_groups) {
   for (auto operand : operands) {
     AppendOperand(operand);
   }
@@ -390,9 +388,7 @@ bool HloAllToAllInstruction::IdenticalSlowPath(
                          [](const ReplicaGroup& a, const ReplicaGroup& b) {
                            return ContainersEqual(a.replica_ids(),
                                                   b.replica_ids());
-                         }) &&
-         cross_replica_sum_barrier() ==
-             casted_other.cross_replica_sum_barrier();
+                         });
 }
 
 std::unique_ptr<HloInstruction>
@@ -400,8 +396,8 @@ HloAllToAllInstruction::CloneWithNewOperandsImpl(
     const Shape& shape,
     tensorflow::gtl::ArraySlice<HloInstruction*> new_operands,
     HloCloneContext* /*context*/) const {
-  return absl::make_unique<HloAllToAllInstruction>(
-      shape, new_operands, replica_groups(), cross_replica_sum_barrier());
+  return absl::make_unique<HloAllToAllInstruction>(shape, new_operands,
+                                                   replica_groups());
 }
 
 std::vector<string> HloAllToAllInstruction::ExtraAttributesToStringImpl(
@@ -415,10 +411,6 @@ std::vector<string> HloAllToAllInstruction::ExtraAttributesToStringImpl(
   result.push_back(
       StrCat("replica_groups={", Join(replica_group_str, ","), "}"));
 
-  if (!cross_replica_sum_barrier().empty()) {
-    result.push_back(StrCat("barrier=\"", cross_replica_sum_barrier(), "\""));
-  }
-
   return result;
 }
 
@@ -426,7 +418,6 @@ HloInstructionProto HloAllToAllInstruction::ToProto() const {
   HloInstructionProto proto = HloInstruction::ToProto();
   *proto.mutable_replica_groups() = {replica_groups_.begin(),
                                      replica_groups_.end()};
-  proto.set_cross_replica_sum_barrier(cross_replica_sum_barrier_);
   return proto;
 }