message: llvm2alive: cache agg constants
diff: @@ -337,7 +337,7 @@ Value* get_operand(llvm::Value *v,
  if (all_of(cnst->op_begin(), cnst->op_end(), [](auto &V) -> bool
  { return isa<llvm::ConstantData>(V); })) {
  current_fn->addConstant(move(val));
  - return ret;
  + RETURN_CACHE(ret);
  } else {
  current_fn->addAggregate(move(val));
  return copy_inserter(ret);
  @@ -353,7 +353,7 @@ Value* get_operand(llvm::Value *v,
  auto val = make_unique<AggregateValue>(*ty, move(vals));
  auto ret = val.get();
  current_fn->addConstant(move(val));
  - return ret;
  + RETURN_CACHE(ret);
  }
  if (auto cnst = dyn_cast<llvm::ConstantAggregateZero>(v)) {
  