import logging
from ailment import Expr
from .engine_base import SimplifierAILEngine, SimplifierAILState
from .optimization_pass import OptimizationPass, OptimizationPassStage
_l = logging.getLogger(name=__name__)
[docs]class ModSimplifierAILEngine(SimplifierAILEngine):
def _ail_handle_Sub(self, expr):
operand_0 = self._expr(expr.operands[0])
operand_1 = self._expr(expr.operands[1])
x_0, c_0, x_1, c_1 = None, None, None, None
if isinstance(operand_1, Expr.BinaryOp) and isinstance(operand_1.operands[1], Expr.Const):
if operand_1.op == "Mul":
if (
isinstance(operand_1.operands[0], Expr.BinaryOp)
and isinstance(operand_1.operands[0].operands[1], Expr.Const)
and operand_1.operands[0].op in ["Div", "Mod"]
):
x_0 = operand_1.operands[0].operands[0]
x_1 = operand_0
c_0 = operand_1.operands[1]
c_1 = operand_1.operands[0].operands[1]
elif (
isinstance(operand_1.operands[0], Expr.Convert)
and isinstance(operand_1.operands[0].operand, Expr.BinaryOp)
and operand_1.operands[0].operand.op in ["Div", "Mod"]
):
x_0 = operand_1.operands[0].operand.operands[0]
x_1 = operand_0
c_0 = operand_1.operands[1]
c_1 = operand_1.operands[0].operand.operands[1]
if x_0 is not None and x_1 is not None and x_0.likes(x_1) and c_0.value == c_1.value:
return Expr.BinaryOp(expr.idx, "Mod", [x_0, c_0], expr.signed, **expr.tags)
if (operand_0, operand_1) != (expr.operands[0], expr.operands[1]):
return Expr.BinaryOp(expr.idx, "Sub", [operand_0, operand_1], expr.signed, **expr.tags)
return expr
[docs]class ModSimplifier(OptimizationPass):
"""
Simplifies optimized forms of modulo computation back to "mod".
"""
ARCHES = [
"X86",
"AMD64",
"ARMCortexM",
"ARMHF",
"ARMEL",
]
PLATFORMS = ["linux", "windows"]
STAGE = OptimizationPassStage.AFTER_GLOBAL_SIMPLIFICATION
NAME = "Simplify optimized mod forms"
DESCRIPTION = __doc__.strip()
[docs] def __init__(self, func, **kwargs):
super().__init__(func, **kwargs)
self.state = SimplifierAILState(self.project.arch)
self.engine = ModSimplifierAILEngine()
self.analyze()
def _check(self):
return True, None
def _analyze(self, cache=None):
for block in list(self._graph.nodes()):
new_block = block
old_block = None
while new_block != old_block:
old_block = new_block
new_block = self.engine.process(state=self.state.copy(), block=old_block.copy())
_l.debug("new block: %s", new_block.statements)
self._update_block(block, new_block)