message: Added a log to help trac the creation of fusion and what they contain.
diff: @@ -615,6 +615,9 @@ HloInstruction* InstructionFusion::Fuse(HloInstruction* producer,
  << consumer->ToString();
  HloInstruction* fusion_instruction = AddFusionInstruction(producer, consumer);
  fusion_instruction->FuseInstruction(producer);
  + if (fusion_instruction != producer && fusion_instruction != consumer) {
  + VLOG(2) << " created new fusion: " << fusion_instruction->ToString();
  + }
  return fusion_instruction;
  }
  