message: Fix the constructor parameter in InstructionList to be pass-by-reference.
diff: @@ -83,7 +83,7 @@ bool IsRematerializable(const HloInstruction* instruction) {
  // before arbitrary elements.
  class InstructionList {
  public:
  - explicit InstructionList(const std::vector<const HloInstruction*> order) {
  + explicit InstructionList(const std::vector<const HloInstruction*>& order) {
  int64 position = 0;
  for (const HloInstruction* inst : order) {
  instructions_.push_back(const_cast<HloInstruction*>(inst));
  