int num_args = cloned_branches[0].getNumArguments();
  llvm::BitVector used_args(num_args);
  for (func::FuncOp func : branches) {
    for (BlockArgument arg : func.getArguments()) {
      if (!arg.use_empty()) used_args.set(arg.getArgNumber());
    }
  }

  // There are some unused args that we can drop. Also drop the corresponding
  // input operand.
  if (used_args.count() != num_args) {

      // TODO(b/246310765): This doesn't fully handle recursion.
      if (!use_count[arg.getArgNumber()]) unused_args.set(arg.getArgNumber());
    }

    EraseReturnOperands(region, unused_results);
    func.eraseResults(unused_results);
    func.eraseArguments(unused_args);

    args_to_erase.insert(std::make_pair(op, unused_args));
    results_to_erase.insert(std::make_pair(op, unused_results));

		p := s.Prog(obj.ACALL)
		p.To.Type = obj.TYPE_MEM
		p.To.Name = obj.NAME_EXTERN
		p.To.Sym = ssagen.BoundsCheckFunc[v.AuxInt]
		s.UseArgs(16) // space used in callee args area by assembly stubs

	case ssa.OpPPC64LoweredNilCheck:
		if buildcfg.GOOS == "aix" {
			// CMP Rarg0, $0
			// BNE 2(PC)
			// STW R0, 0(R0)

		}
	}

	if s.maxarg < v.AuxInt {
		s.maxarg = v.AuxInt
	}
}

// UseArgs records the fact that an instruction needs a certain amount of
// callee args space for its use.
func (s *State) UseArgs(n int64) {
	if s.maxarg < n {
		s.maxarg = n
	}
}

// fieldIdx finds the index of the field referred to by the ODOT node n.