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Add modulo constant folding #411

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merged 3 commits into from
Jun 19, 2024
Merged

Add modulo constant folding #411

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14c7254
Add modulo constant folding
rihi Apr 24, 2024
7b7323f
black
rihi May 15, 2024
122cb97
Merge branch 'main' into module-constant-folding
steffenenders Jun 19, 2024
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Add modulo constant folding
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@rihi
rihi committed Apr 24, 2024
commit 14c7254d8d168c5f06514edf700448cd6f6ddad6
15 changes: 13 additions & 2 deletions decompiler/pipeline/controlflowanalysis/expression_simplification/constant_folding.py
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Original file line number Diff line number Diff line change
Expand Up @@ -65,7 +65,12 @@ def constant_fold(operation: OperationType, constants: list[Constant], result_ty
)


def _constant_fold_arithmetic_binary(constants: list[Constant], fun: Callable[[int, int], int], norm_sign: Optional[bool] = None) -> int:
def _constant_fold_arithmetic_binary(
constants: list[Constant],
fun: Callable[[int, int], int],
norm_sign: Optional[bool] = None,
allow_mismatched_sizes: bool = False,
) -> int:
"""
Fold an arithmetic binary operation with constants as operands.

Expand All @@ -84,7 +89,7 @@ def _constant_fold_arithmetic_binary(constants: list[Constant], fun: Callable[[i

if len(constants) != 2:
raise IncompatibleOperandCount(f"Expected exactly 2 constants to fold, got {len(constants)}.")
if not all(constant.type.size == constants[0].type.size for constant in constants):
if not allow_mismatched_sizes and not all(constant.type.size == constants[0].type.size for constant in constants):
raise UnsupportedMismatchedSizes(f"Can not fold constants with different sizes: {[constant.type for constant in constants]}")

left, right = constants
Expand Down Expand Up @@ -137,13 +142,19 @@ def _constant_fold_shift(constants: list[Constant], fun: Callable[[int, int], in
return fun(normalize_int(left.value, left.type.size, norm_signed), right.value)


def remainder(n, d):
return (-1 if n < 0 else 1) * (n % d)


_OPERATION_TO_FOLD_FUNCTION: dict[OperationType, Callable[[list[Constant]], int]] = {
OperationType.minus: partial(_constant_fold_arithmetic_binary, fun=operator.sub),
OperationType.plus: partial(_constant_fold_arithmetic_binary, fun=operator.add),
OperationType.multiply: partial(_constant_fold_arithmetic_binary, fun=operator.mul, norm_sign=True),
OperationType.multiply_us: partial(_constant_fold_arithmetic_binary, fun=operator.mul, norm_sign=False),
OperationType.divide: partial(_constant_fold_arithmetic_binary, fun=operator.floordiv, norm_sign=True),
OperationType.divide_us: partial(_constant_fold_arithmetic_binary, fun=operator.floordiv, norm_sign=False),
OperationType.modulo: partial(_constant_fold_arithmetic_binary, fun=remainder, norm_sign=True, allow_mismatched_sizes=True),
OperationType.modulo_us: partial(_constant_fold_arithmetic_binary, fun=operator.mod, norm_sign=False, allow_mismatched_sizes=True),
OperationType.negate: partial(_constant_fold_arithmetic_unary, fun=operator.neg),
OperationType.left_shift: partial(_constant_fold_shift, fun=operator.lshift, signed=True),
OperationType.right_shift: partial(_constant_fold_shift, fun=operator.rshift, signed=True),
Expand Down
12 changes: 12 additions & 0 deletions tests/pipeline/controlflowanalysis/expression_simplification/test_constant_folding.py
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Expand Up @@ -93,6 +93,18 @@ def test_constant_fold_invalid_value_type(
(OperationType.divide_us, [_c_i32(3), _c_i16(4)], Integer.int32_t(), None, pytest.raises(UnsupportedMismatchedSizes)),
(OperationType.divide_us, [_c_i32(3)], Integer.int32_t(), None, pytest.raises(IncompatibleOperandCount)),
(OperationType.divide_us, [_c_i32(3), _c_i32(3), _c_i32(3)], Integer.int32_t(), None, pytest.raises(IncompatibleOperandCount)),
(OperationType.modulo, [_c_i32(13), _c_i32(4)], Integer.int32_t(), _c_i32(1), nullcontext()),
(OperationType.modulo, [_c_i32(-2147483647), _c_i32(2)], Integer.int32_t(), _c_i32(-1), nullcontext()),
(OperationType.modulo, [_c_u32(4), _c_i32(3)], Integer.int32_t(), _c_i32(1), nullcontext()),
(OperationType.modulo, [_c_i32(4), _c_i16(3)], Integer.int32_t(), _c_i32(1), nullcontext()),
(OperationType.modulo, [_c_i32(3)], Integer.int32_t(), None, pytest.raises(IncompatibleOperandCount)),
(OperationType.modulo, [_c_i32(3), _c_i32(3), _c_i32(3)], Integer.int32_t(), None, pytest.raises(IncompatibleOperandCount)),
(OperationType.modulo_us, [_c_i32(13), _c_i32(4)], Integer.int32_t(), _c_i32(1), nullcontext()),
(OperationType.modulo_us, [_c_i32(-2147483647), _c_i32(2)], Integer.int32_t(), _c_i32(1), nullcontext()),
(OperationType.modulo_us, [_c_u32(4), _c_i32(3)], Integer.int32_t(), _c_i32(1), nullcontext()),
(OperationType.modulo_us, [_c_i32(4), _c_i16(3)], Integer.int32_t(), _c_i32(1), nullcontext()),
(OperationType.modulo_us, [_c_i32(3)], Integer.int32_t(), None, pytest.raises(IncompatibleOperandCount)),
(OperationType.modulo_us, [_c_i32(3), _c_i32(3), _c_i32(3)], Integer.int32_t(), None, pytest.raises(IncompatibleOperandCount)),
(OperationType.negate, [_c_i32(3)], Integer.int32_t(), _c_i32(-3), nullcontext()),
(OperationType.negate, [_c_i32(-2147483648)], Integer.int32_t(), _c_i32(-2147483648), nullcontext()),
(OperationType.negate, [], Integer.int32_t(), None, pytest.raises(IncompatibleOperandCount)),
Expand Down
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