test_multi3.py

import random

import numpy as np

from numba import njit
from numba.core import types
import unittest

class TestMulti3(unittest.TestCase):
    """
    This test is only relevant for 32-bit architectures.

    Test __multi3 implementation in _helperlib.c.
    The symbol defines a i128 multiplication.
    It is necessary for working around an issue in LLVM (see issue #969).
    The symbol does not exist in 32-bit platform, and should not be used by
    LLVM.  However, optimization passes will create i65 multiplication that
    is then lowered to __multi3.
    """
    def test_multi3(self):
        @njit("(int64,)")
        def func(x):
            res = 0
            for i in range(x):
                res += i
            return res

        x_cases = [-1, 0, 1, 3, 4, 8,
                   0xffffffff - 1, 0xffffffff, 0xffffffff + 1,
                   0x123456789abcdef, -0x123456789abcdef]
        for _ in range(500):
            x_cases.append(random.randint(0, 0xffffffff))

        def expected(x):
            if x <= 0: return 0
            return ((x * (x - 1)) // 2) & (2**64 - 1)

        for x in x_cases:
            self.assertEqual(expected(x), func(x))


if __name__ == '__main__':
    unittest.main()