message: [XLA:GPU] Do not fuse into bitcast ops.
  Bitcasts are no-ops that do not produce any code. Hence, we're better off keeping them unfused.
diff: @@ -201,7 +201,10 @@ Status FusionInstructionMerger::HandleFusion(HloInstruction* fusion) {
  // Merging into all users enables the removal of 'fusion' from the
  // computation.
  if (!absl::c_all_of(fusion->users(), [&](const HloInstruction* user) {
  - return IsProducerConsumerFusible(*fusion, *user);
  + return IsProducerConsumerFusible(*fusion, *user) &&
  + // Do not fuse into bitcast ops, which are no-ops and do not
  + // generate any GPU code.
  + user->opcode() != HloOpcode::kBitcast;
  })) {
  VLOG(3) << "Not merging " << fusion->name()
  << ": Some of its users are not loop/input fusion kernels.";
  