Instance __setslice__ implementation

setslice.cpp

Box* instanceSetslice(Box* _inst, Box* i, Box* j, Box** sequence) {
    RELEASE_ASSERT(_inst->cls == instance_cls, "");
    BoxedInstance* inst = static_cast<BoxedInstance*>(_inst);

    static BoxedString* setslice_str = internStringImmortal("__setslice__");
    Box* setslice_func = NULL;

    try {
        setslice_func = _instanceGetattribute(inst, setslice_str, false);
    } catch (ExcInfo e) {
        if (!e.matches(AttributeError))
            throw e;
    }

    if (setslice_func == NULL) {
        Box* slice = static_cast<Box*>(createSlice(i, j, None));
        return instanceSetitem(inst, slice, sequence);
    }

    return runtimeCall(setslice_func, ArgPassSpec(3), i, j, *sequence, NULL, NULL);
}

Here is the backtrace:
#4  0x00000000015849a4 in pyston::rearrangeArguments (paramspec=..., param_names=0x7ffff387b2d0, 
    func_name=0x1270040af9 "__setslice__", defaults=0x0, rewrite_args=0x0, rewrite_success=@0x7fffffffba87: false, 
    argspec=..., arg1=0x12701bed98, arg2=0x1270014148, arg3=0x12700141a8, args=0x7fffffffbcf0, keyword_names=0x0, 
    oarg1=@0x7fffffffbaa0: 0x1270183808, oarg2=@0x7fffffffba98: 0x0, oarg3=@0x7fffffffba90: 0x15ecc00, 
    oargs=0x7fffffffb7f0) at ../../src/runtime/objmodel.cpp:3259
#5  0x00000000008c4b81 in pyston::callFunc (func=0x12701b4be8, rewrite_args=0x0, argspec=..., arg1=0x12701bed98, 
    arg2=0x1270014148, arg3=0x12700141a8, args=0x7fffffffbcf0, keyword_names=0x0)
    at ../../src/runtime/objmodel.cpp:3595
#6  0x00000000008c2ff8 in pyston::runtimeCallInternal (obj=0x12701b4be8, rewrite_args=0x0, argspec=..., 
    arg1=0x12701bed98, arg2=0x1270014148, arg3=0x12700141a8, args=0x7fffffffbcf0, keyword_names=0x0)
    at ../../src/runtime/objmodel.cpp:3878
#7  0x00000000008c3339 in pyston::runtimeCallInternal (obj=0x12701bf188, rewrite_args=0x0, argspec=..., 
    arg1=0x12701bed98, arg2=0x1270014148, arg3=0x12700141a8, args=0x0, keyword_names=0x0)
    at ../../src/runtime/objmodel.cpp:3922
#8  0x00000000008c8b64 in runtimeCall (obj=0x12701bf188, argspec=..., arg1=0x1270014148, arg2=0x12700141a8, 
    arg3=0x7fffffffc500, args=0x0, keyword_names=0x0) at ../../src/runtime/objmodel.cpp:3990
#9  0x000000000085c8fd in pyston::instanceSetslice (_inst=0x12701bed98, i=0x1270014148, j=0x12700141a8, 
    sequence=0x7fffffffc500) at ../../src/runtime/classobj.cpp:577