// Operation::eraseArguments does (but for results).
// This is a lengthy bit of code, since it has to recreate the operation.
// TODO(kramm): Move this under utils/ somewhere.
void EraseResults(Operation* op, llvm::BitVector erase) {
  assert(!op->getNumRegions());
  std::vector<Type> result_types;
  for (auto result : op->getResults()) {
    if (!erase[result.getResultNumber()]) {