message: [XLA:CPU] Fusion: Only check for reuse on expensive instructions
  The reuse condition walks over all instructions in the fusion, the fusion pass
  walks over all instructions, making this essentially quadratic. Moving the
  is_expensive check up doesn't completely avoid this behavior, but makes it much
  more unlikely.
diff: @@ -94,9 +94,8 @@ bool CpuInstructionFusion::ShouldFuse(HloInstruction* consumer,
  // Cost condition: not fuse (simple, expensive producers) and (consumers who
  // reuse operand elements).
  - if (producer->opcode() != HloOpcode::kFusion &&
  - consumer->ReusesOperandElements(operand_index) &&
  - is_expensive(*producer)) {
  + if (producer->opcode() != HloOpcode::kFusion && is_expensive(*producer) &&
  + consumer->ReusesOperandElements(operand_index)) {
  VLOG(2) << "Fusion is not profitable.";
  return false;
  }
  