def builtin_lookup(self, mod, name):
        """
        Args
        ----
        mod:
            The __builtins__ dictionary or module, as looked up in
            a module's globals.
        name: str
            The object to lookup
        """
        fromdict = self.pyapi.dict_getitem(mod, self._freeze_string(name))
        self.incref(fromdict)       # fromdict is borrowed
        bbifdict = self.builder.basic_block

        with cgutils.if_unlikely(self.builder, self.is_null(fromdict)):
            # This happen if we are using the __main__ module
            frommod = self.pyapi.object_getattr(mod, self._freeze_string(name))

            with cgutils.if_unlikely(self.builder, self.is_null(frommod)):
                self.pyapi.raise_missing_global_error(name)
                self.return_exception_raised()

            bbifmod = self.builder.basic_block

        builtin = self.builder.phi(self.pyapi.pyobj)
        builtin.add_incoming(fromdict, bbifdict)
        builtin.add_incoming(frommod, bbifmod)

        return builtin

def _define_nrt_decref(module, atomic_decr):
    """
    Implement NRT_decref in the module
    """
    fn_decref = module.get_or_insert_function(incref_decref_ty,
                                              name="NRT_decref")
    calldtor = module.add_function(ir.FunctionType(ir.VoidType(), [_pointer_type]),
                                   name="NRT_MemInfo_call_dtor")

    builder = ir.IRBuilder(fn_decref.append_basic_block())
    [ptr] = fn_decref.args
    is_null = builder.icmp_unsigned("==", ptr, cgutils.get_null_value(ptr.type))
    with cgutils.if_unlikely(builder, is_null):
        builder.ret_void()

    if _debug_print:
        cgutils.printf(builder, "*** NRT_Decref %zu [%p]\n", builder.load(ptr),
                       ptr)
    newrefct = builder.call(atomic_decr,
                            [builder.bitcast(ptr, atomic_decr.args[0].type)])

    refct_eq_0 = builder.icmp_unsigned("==", newrefct,
                                       ir.Constant(newrefct.type, 0))
    with cgutils.if_unlikely(builder, refct_eq_0):
        builder.call(calldtor, [ptr])
    builder.ret_void()

def _define_decref(module, atomic_decr):
    """
    Implement NRT_decref in the module
    """
    if "NRT_decref" not in module.globals:
        return
    fn_decref = module.get_global_variable_named("NRT_decref")
    fn_decref.linkage = 'linkonce_odr'
    calldtor = module.add_function(ir.FunctionType(ir.VoidType(),
        [ir.IntType(8).as_pointer(), ir.IntType(32)]),
        name="NRT_MemInfo_call_dtor")

    builder = ir.IRBuilder(fn_decref.append_basic_block())
    [ptr] = fn_decref.args
    is_null = builder.icmp_unsigned("==", ptr, cgutils.get_null_value(ptr.type))
    with cgutils.if_unlikely(builder, is_null):
        builder.ret_void()
    newrefct = builder.call(atomic_decr,
                            [builder.bitcast(ptr, atomic_decr.args[0].type)])

    refct_eq_0 = builder.icmp_unsigned("==", newrefct,
                                       ir.Constant(newrefct.type, 0))
    with cgutils.if_unlikely(builder, refct_eq_0):
        do_defer = ir.Constant(ir.IntType(32), 0)
        builder.call(calldtor, [ptr, do_defer])
    builder.ret_void()

def iternext_zip(context, builder, sig, args, result):
    genty, = sig.args
    gen, = args
    # XXX We should link with the generator's library.
    # Currently, this doesn't make a difference as the library has already
    # been linked for the generator init function.
    impl = context.get_generator_impl(genty)
    status, retval = impl(context, builder, sig, args)
    with cgutils.if_likely(builder, status.is_ok):
        result.set_valid(True)
        result.yield_(retval)
    with cgutils.if_unlikely(builder, status.is_stop_iteration):
        result.set_exhausted()
    with cgutils.if_unlikely(builder, builder.and_(status.is_error, builder.not_(status.is_stop_iteration))):
        context.call_conv.return_status_propagate(builder, status)

def getitem_array1d(context, builder, sig, args):
    aryty, _ = sig.args
    if aryty.ndim != 1:
        # TODO
        raise NotImplementedError("1D indexing into %dD array" % aryty.ndim)

    ary, idx = args

    arystty = make_array(aryty)
    ary = arystty(context, builder, ary)
    dataptr = ary.data

    if True or WARPAROUND:  # TODO target flag
        ZERO = context.get_constant(types.intp, 0)
        negative = builder.icmp(lc.ICMP_SLT, idx, ZERO)
        bbnormal = builder.basic_block
        with cgutils.if_unlikely(builder, negative):
            # Index is negative, wraparound
            [nelem] = cgutils.unpack_tuple(builder, ary.shape, 1)
            wrapped = builder.add(nelem, idx)
            bbwrapped = builder.basic_block

        where = builder.phi(idx.type)
        where.add_incoming(idx, bbnormal)
        where.add_incoming(wrapped, bbwrapped)

        ptr = builder.gep(dataptr, [where])
    else:
        # No wraparound
        ptr = builder.gep(dataptr, [idx])

    if context.is_struct_type(aryty.dtype):
        return ptr
    else:
        return builder.load(ptr)

    def to_native_arg(self, obj, typ):
        if isinstance(typ, types.Record):
            # Generate a dummy integer type that has the size of Py_buffer
            dummy_py_buffer_type = Type.int(_helperlib.py_buffer_size * 8)
            # Allocate the Py_buffer
            py_buffer = cgutils.alloca_once(self.builder, dummy_py_buffer_type)

            # Zero-fill the py_buffer. where the obj field in Py_buffer is NULL
            # PyBuffer_Release has no effect.
            zeroed_buffer = lc.Constant.null(dummy_py_buffer_type)
            self.builder.store(zeroed_buffer, py_buffer)

            buf_as_voidptr = self.builder.bitcast(py_buffer, self.voidptr)
            ptr = self.extract_record_data(obj, buf_as_voidptr)

            with cgutils.if_unlikely(self.builder,
                                     cgutils.is_null(self.builder, ptr)):
                self.builder.ret(ptr)

            ltyp = self.context.get_value_type(typ)
            val = cgutils.init_record_by_ptr(self.builder, ltyp, ptr)

            def dtor():
                self.release_record_buffer(buf_as_voidptr)

        else:
            val = self.to_native_value(obj, typ)

            def dtor():
                pass

        return val, dtor

def iternext_zip(context, builder, sig, args, result):
    genty, = sig.args
    gen, = args
    impl = context.get_generator_impl(genty)
    status, retval = impl(context, builder, sig, args)
    context.add_linking_libs(getattr(impl, 'libs', ()))

    with cgutils.if_likely(builder, status.is_ok):
        result.set_valid(True)
        result.yield_(retval)
    with cgutils.if_unlikely(builder, status.is_stop_iteration):
        result.set_exhausted()
    with cgutils.if_unlikely(builder,
                             builder.and_(status.is_error,
                                          builder.not_(status.is_stop_iteration))):
        context.call_conv.return_status_propagate(builder, status)

    def lower_global(self, name, value):
        """
        1) Check global scope dictionary.
        2) Check __builtins__.
            2a) is it a dictionary (for non __main__ module)
            2b) is it a module (for __main__ module)
        """
        moddict = self.pyapi.get_module_dict()
        obj = self.pyapi.dict_getitem_string(moddict, name)
        self.incref(obj)  # obj is borrowed

        if hasattr(builtins, name):
            obj_is_null = self.is_null(obj)
            bbelse = self.builder.basic_block

            with cgutils.ifthen(self.builder, obj_is_null):
                mod = self.pyapi.dict_getitem_string(moddict, "__builtins__")
                builtin = self.builtin_lookup(mod, name)
                bbif = self.builder.basic_block

            retval = self.builder.phi(self.pyapi.pyobj)
            retval.add_incoming(obj, bbelse)
            retval.add_incoming(builtin, bbif)

        else:
            retval = obj
            with cgutils.if_unlikely(self.builder, self.is_null(retval)):
                self.pyapi.raise_missing_global_error(name)
                self.return_exception_raised()

        self.incref(retval)
        return retval

def getiter_range_generic(context, builder, iterobj, start, stop, step):
    diff = builder.sub(stop, start)
    intty = start.type
    zero = Constant.int(intty, 0)
    one = Constant.int(intty, 1)
    pos_diff = builder.icmp(lc.ICMP_SGT, diff, zero)
    pos_step = builder.icmp(lc.ICMP_SGT, step, zero)
    sign_differs = builder.xor(pos_diff, pos_step)
    zero_step = builder.icmp(lc.ICMP_EQ, step, zero)

    with cgutils.if_unlikely(builder, zero_step):
        # step shouldn't be zero
        context.return_errcode(builder, 1)

    with cgutils.ifelse(builder, sign_differs) as (then, orelse):
        with then:
            builder.store(zero, iterobj.count)

        with orelse:
            rem = builder.srem(diff, step)
            uneven = builder.icmp(lc.ICMP_SGT, rem, zero)
            newcount = builder.add(builder.sdiv(diff, step),
                                   builder.select(uneven, one, zero))
            builder.store(newcount, iterobj.count)

    return iterobj._getvalue()

def get_next_int32(context, builder, state_ptr):
    """
    Get the next int32 generated by the PRNG at *state_ptr*.
    """
    idxptr = get_index_ptr(builder, state_ptr)
    idx = builder.load(idxptr)
    need_reshuffle = builder.icmp_unsigned('>=', idx, N_const)
    with cgutils.if_unlikely(builder, need_reshuffle):
        fnty = ir.FunctionType(ir.VoidType(), (rnd_state_ptr_t,))
        fn = builder.function.module.get_or_insert_function(fnty, "numba_rnd_shuffle")
        builder.call(fn, (state_ptr,))
        builder.store(const_int(0), idxptr)
    idx = builder.load(idxptr)
    array_ptr = get_array_ptr(builder, state_ptr)
    y = builder.load(cgutils.gep(builder, array_ptr, 0, idx))
    idx = builder.add(idx, const_int(1))
    builder.store(idx, idxptr)
    # Tempering
    y = builder.xor(y, builder.lshr(y, const_int(11)))
    y = builder.xor(y, builder.and_(builder.shl(y, const_int(7)),
                                    const_int(0x9d2c5680)))
    y = builder.xor(y, builder.and_(builder.shl(y, const_int(15)),
                                    const_int(0xefc60000)))
    y = builder.xor(y, builder.lshr(y, const_int(18)))
    return y

            def init_specific(self, context, builder, arrty, arr):
                zero = context.get_constant(types.intp, 0)
                data = arr.data
                ndim = arrty.ndim
                shapes = cgutils.unpack_tuple(builder, arr.shape, ndim)

                indices = cgutils.alloca_once(builder, zero.type,
                                              size=context.get_constant(types.intp,
                                                                        arrty.ndim))
                pointers = cgutils.alloca_once(builder, data.type,
                                               size=context.get_constant(types.intp,
                                                                         arrty.ndim))
                strides = cgutils.unpack_tuple(builder, arr.strides, ndim)
                exhausted = cgutils.alloca_once_value(builder, cgutils.false_byte)

                # Initialize indices and pointers with their start values.
                for dim in range(ndim):
                    idxptr = cgutils.gep(builder, indices, dim)
                    ptrptr = cgutils.gep(builder, pointers, dim)
                    builder.store(data, ptrptr)
                    builder.store(zero, idxptr)
                    # 0-sized dimensions really indicate an empty array,
                    # but we have to catch that condition early to avoid
                    # a bug inside the iteration logic (see issue #846).
                    dim_size = shapes[dim]
                    dim_is_empty = builder.icmp(lc.ICMP_EQ, dim_size, zero)
                    with cgutils.if_unlikely(builder, dim_is_empty):
                        builder.store(cgutils.true_byte, exhausted)

                self.indices = indices
                self.pointers = pointers
                self.exhausted = exhausted

 def imp(context, builder, sig, args):
     func = context.declare_function(cgutils.get_module(builder), fndesc)
     status, retval = context.call_function(builder, func, fndesc.restype,
                                            fndesc.argtypes, args)
     with cgutils.if_unlikely(builder, status.err):
         context.return_errcode_propagate(builder, status.code)
     return retval

    def add_arg(self, obj, ty):
        """
        Unbox argument and emit code that handles any error during unboxing.
        Args are cleaned up in reverse order of the parameter list, and
        cleanup begins as soon as unboxing of any argument fails. E.g. failure
        on arg2 will result in control flow going through:

            arg2.err -> arg1.err -> arg0.err -> arg.end (returns)
        """
        # Unbox argument
        val, dtor = self.api.to_native_arg(self.builder.load(obj), ty)

        # check for Python C-API Error
        error_check = self.api.err_occurred()
        err_happened = self.builder.icmp(lc.ICMP_NE, error_check,
                                         self.api.get_null_object())

        # Write the cleanup block
        cleanupblk = cgutils.append_basic_block(self.builder,
                                                "arg%d.err" % self.arg_count)
        with cgutils.goto_block(self.builder, cleanupblk):
            dtor()
            # Go to next cleanup block
            self.builder.branch(self.nextblk)

        # If an error occurred, go to the cleanup block
        with cgutils.if_unlikely(self.builder, err_happened):
            self.builder.branch(cleanupblk)

        self.cleanups.append(dtor)
        self.nextblk = cleanupblk
        self.arg_count += 1
        return val

    def add_arg(self, obj, ty):
        """
        Unbox argument and emit code that handles any error during unboxing.
        Args are cleaned up in reverse order of the parameter list, and
        cleanup begins as soon as unboxing of any argument fails. E.g. failure
        on arg2 will result in control flow going through:

            arg2.err -> arg1.err -> arg0.err -> arg.end (returns)
        """
        # Unbox argument
        native = self.api.to_native_value(self.builder.load(obj), ty)

        # If an error occurred, go to the cleanup block for the previous argument.
        with cgutils.if_unlikely(self.builder, native.is_error):
            self.builder.branch(self.nextblk)

        # Write the cleanup block for this argument
        cleanupblk = cgutils.append_basic_block(self.builder,
                                                "arg%d.err" % self.arg_count)
        with cgutils.goto_block(self.builder, cleanupblk):
            if native.cleanup is not None:
                native.cleanup()
                self.cleanups.append(native.cleanup)
            # Go to next cleanup block
            self.builder.branch(self.nextblk)

        self.nextblk = cleanupblk
        self.arg_count += 1
        return native.value

    def set_iter_valid(self, state, item):
        iterstate = PyIterState(self.context, self.builder, ref=state)
        iterstate.valid = cgutils.as_bool_byte(self.builder,
                                               cgutils.is_not_null(self.builder,
                                                                   item))

        with cgutils.if_unlikely(self.builder, self.is_null(item)):
            self.check_occurred()

 def check_int_status(self, num, ok_value=0):
     """
     Raise an exception if *num* is smaller than *ok_value*.
     """
     ok = lc.Constant.int(num.type, ok_value)
     pred = self.builder.icmp(lc.ICMP_SLT, num, ok)
     with cgutils.if_unlikely(self.builder, pred):
         self.return_exception_raised()

def getrandbits_impl(context, builder, sig, args):
    nbits, = args
    too_large = builder.icmp_unsigned(">=", nbits, const_int(65))
    too_small = builder.icmp_unsigned("==", nbits, const_int(0))
    with cgutils.if_unlikely(builder, builder.or_(too_large, too_small)):
        msg = "getrandbits() limited to 64 bits"
        context.call_conv.return_user_exc(builder, OverflowError, (msg,))
    state_ptr = get_state_ptr(context, builder, "py")
    return get_next_int(context, builder, state_ptr, nbits)

    def build_wrapper(self, api, builder, closure, args, kws):
        nargs = len(self.fndesc.argtypes)

        objs = [api.alloca_obj() for _ in range(nargs)]
        parseok = api.unpack_tuple(args, self.fndesc.qualname,
                                   nargs, nargs, *objs)

        pred = builder.icmp(lc.ICMP_EQ, parseok, Constant.null(parseok.type))
        with cgutils.if_unlikely(builder, pred):
            builder.ret(api.get_null_object())

        # Block that returns after erroneous argument unboxing/cleanup
        endblk = builder.append_basic_block("arg.end")
        with builder.goto_block(endblk):
            builder.ret(api.get_null_object())

        # Extract the Environment object from the Closure
        envptr, env_manager = self.get_env(api, builder, closure)

        cleanup_manager = _ArgManager(self.context, builder, api,
                                      env_manager, endblk, nargs)

        # Compute the arguments to the compiled Numba function.
        innerargs = []
        for obj, ty in zip(objs, self.fndesc.argtypes):
            if isinstance(ty, types.Omitted):
                # It's an omitted value => ignore dummy Python object
                innerargs.append(None)
            else:
                val = cleanup_manager.add_arg(builder.load(obj), ty)
                innerargs.append(val)

        if self.release_gil:
            cleanup_manager = _GilManager(builder, api, cleanup_manager)

        status, retval = self.context.call_conv.call_function(
            builder, self.func, self.fndesc.restype, self.fndesc.argtypes,
            innerargs, env=envptr)
        # Do clean up
        self.debug_print(builder, "# callwrapper: emit_cleanup")
        cleanup_manager.emit_cleanup()
        self.debug_print(builder, "# callwrapper: emit_cleanup end")

        # Determine return status
        with builder.if_then(status.is_ok, likely=True):
            # Ok => return boxed Python value
            with builder.if_then(status.is_none):
                api.return_none()

            retty = self._simplified_return_type()
            obj = api.from_native_return(retty, retval, env_manager)
            builder.ret(obj)

        # Error out
        self.context.call_conv.raise_error(builder, api, status)
        builder.ret(api.get_null_object())

def iternext_numpy_flatiter(context, builder, sig, args, result):
    [flatiterty] = sig.args
    [flatiter] = args

    flatitercls = make_array_flat_cls(flatiterty)
    flatiter = flatitercls(context, builder, value=flatiter)

    arrty = flatiterty.array_type
    arrcls = context.make_array(arrty)
    arr = arrcls(context, builder, value=builder.load(flatiter.array))

    ndim = arrty.ndim
    shapes = cgutils.unpack_tuple(builder, arr.shape, ndim)
    indptr = flatiter.iters

    # Load indices and check if they are valid
    indices = []
    is_valid = cgutils.true_bit
    zero = context.get_constant(types.intp, 0)
    one = context.get_constant(types.intp, 1)
    for ax in range(ndim):
        axsize = shapes[ax]
        idxptr = builder.gep(indptr, [context.get_constant(types.intp, ax)])
        idx = builder.load(idxptr)
        ax_valid = builder.icmp(lc.ICMP_SLT, idx, axsize)

        indices.append(idx)
        is_valid = builder.and_(is_valid, ax_valid)

    result.set_valid(is_valid)

    with cgutils.if_likely(builder, is_valid):
        # Get yielded value
        valptr = cgutils.get_item_pointer(builder, arrty, arr, indices)
        yield_value = builder.load(valptr)
        result.yield_(yield_value)

        # Increment iterator indices
        carry_flags = [cgutils.true_bit]
        for ax, (idx, axsize) in reversed(list(enumerate(zip(indices,
                                                             shapes)))):
            idxptr = builder.gep(indptr, [context.get_constant(types.intp, ax)])
            lastcarry = carry_flags[-1]
            idxp1 = builder.add(idx, one)
            carry = builder.icmp(lc.ICMP_SGE, idxp1, axsize)
            idxfinal = builder.select(lastcarry,
                                      builder.select(carry, zero, idxp1),
                                      idx)
            builder.store(idxfinal, idxptr)
            carry_flags.append(builder.and_(carry, lastcarry))

        with cgutils.if_unlikely(builder, carry_flags[-1]):
            # If we have iterated all elements,
            # Set first index to out-of-bound
            idxptr = builder.gep(indptr, [context.get_constant(types.intp, 0)])
            builder.store(shapes[0], idxptr)

 def pre_lower(self):
     # Store environment argument for later use
     self.envarg = self.context.get_env_argument(self.function)
     with cgutils.if_unlikely(self.builder, self.is_null(self.envarg)):
         self.pyapi.err_set_string(
             "PyExc_SystemError",
             "Numba internal error: object mode function called "
             "without an environment")
         self.return_exception_raised()
     self.env_body = self.context.get_env_body(self.builder, self.envarg)