def mk_range_block(typemap, start, stop, step, calltypes, scope, loc):
    """make a block that initializes loop range and iteration variables.
    target label in jump needs to be set.
    """
    # g_range_var = Global(range)
    g_range_var = ir.Var(scope, mk_unique_var("$range_g_var"), loc)
    typemap[g_range_var.name] = get_global_func_typ(range)
    g_range = ir.Global('range', range, loc)
    g_range_assign = ir.Assign(g_range, g_range_var, loc)
    arg_nodes, args = _mk_range_args(typemap, start, stop, step, scope, loc)
    # range_call_var = call g_range_var(start, stop, step)
    range_call = ir.Expr.call(g_range_var, args, (), loc)
    calltypes[range_call] = typemap[g_range_var.name].get_call_type(
        typing.Context(), [types.intp] * len(args), {})
    #signature(types.range_state64_type, types.intp)
    range_call_var = ir.Var(scope, mk_unique_var("$range_c_var"), loc)
    typemap[range_call_var.name] = types.iterators.RangeType(types.intp)
    range_call_assign = ir.Assign(range_call, range_call_var, loc)
    # iter_var = getiter(range_call_var)
    iter_call = ir.Expr.getiter(range_call_var, loc)
    if config.USE_LEGACY_TYPE_SYSTEM:
        calltype_sig = signature(types.range_iter64_type, types.range_state64_type)
    else:
        calltype_sig = signature(types.range_iter_type, types.range_state_type)
    calltypes[iter_call] = calltype_sig
    iter_var = ir.Var(scope, mk_unique_var("$iter_var"), loc)
    typemap[iter_var.name] = types.iterators.RangeIteratorType(types.intp)
    iter_call_assign = ir.Assign(iter_call, iter_var, loc)
    # $phi = iter_var
    phi_var = ir.Var(scope, mk_unique_var("$phi"), loc)
    typemap[phi_var.name] = types.iterators.RangeIteratorType(types.intp)
    phi_assign = ir.Assign(iter_var, phi_var, loc)
    # jump to header
    jump_header = ir.Jump(-1, loc)
    range_block = ir.Block(scope, loc)
    range_block.body = arg_nodes + [g_range_assign, range_call_assign,
                                    iter_call_assign, phi_assign, jump_header]
    return range_block
make a block that initializes loop range and iteration variables.
    target label in jump needs to be set.
    
numba/core/ir_utils.py