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Improve collapse_add_neg simplifcation rule #355

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merged 3 commits into from
Oct 26, 2023
+27 −16
Merged

Improve collapse_add_neg simplifcation rule #355

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aa42dcb
Improve collapse_add_neg.py
rihi Oct 18, 2023
8a172ee
Merge branch 'main' into improve-collapse-add-neg
blattm Oct 26, 2023
e29ea08
fix formatting
blattm Oct 26, 2023
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35 changes: 19 additions & 16 deletions decompiler/pipeline/controlflowanalysis/expression_simplification/rules/collapse_add_neg.py
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Original file line number Diff line number Diff line change
@@ -1,3 +1,5 @@
from typing import Optional

from decompiler.pipeline.controlflowanalysis.expression_simplification.rules.rule import SimplificationRule
from decompiler.structures.pseudo import BinaryOperation, Expression, Operation, OperationType, UnaryOperation

Expand All @@ -8,25 +10,26 @@ class CollapseAddNeg(SimplificationRule):

- `e0 + -(e1) -> e0 - e1`
- `e0 - -(e1) -> e0 + e1`
- `-(e0) + e1 -> e1 - e0`
- `-(e0) - e1 -> -(e0 + e1)`
"""

def apply(self, operation: Operation) -> list[tuple[Expression, Expression]]:
if operation.operation not in [OperationType.plus, OperationType.minus]:
return []
if not isinstance(operation, BinaryOperation):
raise TypeError(f"Expected BinaryOperation, got {type(operation)}")
replacement: Optional[Expression] = None
match operation:
case BinaryOperation(operation=OperationType.plus, left=e0, right=UnaryOperation(operation=OperationType.negate, operand=e1)):
replacement = BinaryOperation(OperationType.minus, [e0, e1], operation.type)

case BinaryOperation(operation=OperationType.minus, left=e0, right=UnaryOperation(operation=OperationType.negate, operand=e1)):
replacement = BinaryOperation(OperationType.plus, [e0, e1], operation.type)

case BinaryOperation(operation=OperationType.plus, left=UnaryOperation(operation=OperationType.negate, operand=e0), right=e1):
replacement = BinaryOperation(OperationType.minus, [e1, e0], operation.type)

case BinaryOperation(operation=OperationType.minus, left=UnaryOperation(operation=OperationType.negate, operand=e0), right=e1):
replacement = UnaryOperation(OperationType.negate, [BinaryOperation(OperationType.plus, [e0, e1], operation.type)])

right = operation.right
if not isinstance(right, UnaryOperation) or right.operation != OperationType.negate:
if replacement is None:
return []

return [
(
operation,
BinaryOperation(
OperationType.minus if operation.operation == OperationType.plus else OperationType.plus,
[operation.left, right.operand],
operation.type,
),
)
]
return [(operation, replacement)]
8 changes: 8 additions & 0 deletions tests/pipeline/controlflowanalysis/expression_simplification/rules/test_collapse_add_neg.py
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Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,14 @@
BinaryOperation(OperationType.minus, [var_x, UnaryOperation(OperationType.negate, [var_y])]),
[BinaryOperation(OperationType.plus, [var_x, var_y])],
),
(
BinaryOperation(OperationType.plus, [UnaryOperation(OperationType.negate, [var_x]), var_y]),
[BinaryOperation(OperationType.minus, [var_y, var_x])],
),
(
BinaryOperation(OperationType.minus, [UnaryOperation(OperationType.negate, [var_x]), var_y]),
[UnaryOperation(OperationType.negate, [BinaryOperation(OperationType.plus, [var_x, var_y])])],
),
],
)
def test_collapse_add_neg(operation: Operation, result: list[Expression]):
Expand Down
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