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BUG: Integer overflow in remainder for Windows #19260

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BUG: Integer overflow in remainder for Windows #19260

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8b0f1ad
BUG: Restored old FIXME message removed during SIMD changes
ganesh-k13 Jun 15, 2021
e5df385
TST: Remainder test cases for signed integers
ganesh-k13 Jun 21, 2021
35789c0
BUG: Added MIN and -1 check for remainder
ganesh-k13 Jun 21, 2021
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10 changes: 8 additions & 2 deletions numpy/core/src/umath/loops.c.src
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Original file line number Diff line number Diff line change
Expand Up @@ -849,7 +849,7 @@ NPY_NO_EXPORT void
BINARY_LOOP {
const @type@ in1 = *(@type@ *)ip1;
const @type@ in2 = *(@type@ *)ip2;
if (in2 == 0) {
if (in2 == 0 || (in1 == NPY_MIN_@TYPE@ && in2 == -1)) {
npy_set_floatstatus_divbyzero();
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Do we have to set the error flag for the second branch?

*((@type@ *)op1) = 0;
}
Expand All @@ -872,7 +872,13 @@ NPY_NO_EXPORT void
BINARY_LOOP_TWO_OUT {
const @type@ in1 = *(@type@ *)ip1;
const @type@ in2 = *(@type@ *)ip2;
/* see FIXME note for divide above */
/*
* FIXME: On x86 at least, dividing the smallest representable integer
* by -1 causes a SIFGPE (division overflow). We treat this case here
* (to avoid a SIGFPE crash at python level), but a good solution would
* be to treat integer division problems separately from FPU exceptions
* (i.e. a different approach than npy_set_floatstatus_divbyzero()).
*/
if (in2 == 0 || (in1 == NPY_MIN_@TYPE@ && in2 == -1)) {
npy_set_floatstatus_divbyzero();
*((@type@ *)op1) = 0;
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29 changes: 29 additions & 0 deletions numpy/core/tests/test_umath.py
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Original file line number Diff line number Diff line change
Expand Up @@ -516,6 +516,35 @@ def test_remainder_basic(self):
else:
assert_(b > rem >= 0, msg)

@pytest.mark.parametrize("input_dtype",
np.sctypes['int'])
def test_remainder_integer(self, input_dtype):
iinfo = np.iinfo(input_dtype)

# Create list with min, 25th percentile, 0, 75th percentile, max
lst = [iinfo.min, iinfo.min//2, iinfo.max//2, iinfo.max]
divisors = [iinfo.min, iinfo.min//2, iinfo.max//2, iinfo.max]
a = np.array(lst, dtype=input_dtype)

for divisor in divisors:
rem_a = np.remainder(a, divisor)
rem_lst = [i % divisor for i in lst]

msg = "Integer arrays remainder check"
assert all(rem_a == rem_lst), msg

for l in lst:
msg = "Integer scalar remainder check"
assert input_dtype(l) % divisor == l % divisor, msg

with np.errstate(divide='raise'):
with pytest.raises(FloatingPointError):
np.remainder(a, 0)
with pytest.raises(FloatingPointError):
np.remainder(a, -1)
with pytest.raises(FloatingPointError):
np.remainder(iinfo.min, -1)

def test_float_remainder_exact(self):
# test that float results are exact for small integers. This also
# holds for the same integers scaled by powers of two.
Expand Down