small snippet written on the July 14 2023 Binary Ninja live stream

fixmuls.py

def myvisit(opName, op, opType, parentInstruction):
  if (op.operation == MediumLevelILOperation.MLIL_MULU_DP) and isinstance(op.right, Constant) and isinstance(op.left, Constant):
    nextInstruction = op.function[op.instr_index + 1]
    leftVal = op.left.value.value
    rightVal = op.right.value.value
    upper = leftVal * rightVal >> 32
    lower = leftVal * rightVal & 0xffffffff
    if isinstance(nextInstruction, SetVar):
      nextVar = nextInstruction.src.operands[0]
      if hasattr(nextVar, "name"):
        if nextInstruction.src.operands[0].name == parentInstruction.high.name:
          result = upper
        else:
          result = lower
        val = PossibleValueSet.constant(result)
        theVar = nextInstruction.dest
        addr = nextInstruction.address
        op.function.source_function.set_user_var_value(theVar, addr, val)
        log_info(f"Set user value of {val} at {hex(addr)}")

for mf in bv.mlil_functions():
  mf.visit(myvisit)