mirror of
https://github.com/DragonMinded/bemaniutils.git
synced 2026-10-06 22:08:20 +03:00
764 lines
34 KiB
Python
764 lines
34 KiB
Python
import os
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from typing import Any, Dict, List, Sequence, Tuple, Set, Union, Optional, cast
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from .types import AP2Action, JumpAction, IfAction, DefineFunction2Action
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from .util import VerboseOutput
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class ByteCode:
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# A list of bytecodes to execute.
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def __init__(self, actions: Sequence[AP2Action], end_offset: int) -> None:
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self.actions = list(actions)
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self.end_offset = end_offset
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def as_dict(self, *args: Any, **kwargs: Any) -> Dict[str, Any]:
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if kwargs.get('decompile_bytecode', False):
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decompiler = ByteCodeDecompiler(self)
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code = decompiler.decompile(verbose=True)
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return {
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'code': code,
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}
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else:
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return {
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'actions': [a.as_dict(*args, **kwargs) for a in self.actions],
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'end_offset': self.end_offset,
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}
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def __repr__(self) -> str:
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entries: List[str] = []
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for action in self.actions:
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entries.extend([f" {s}" for s in str(action).split(os.linesep)])
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return f"ByteCode({os.linesep}{os.linesep.join(entries)}{os.linesep} {self.end_offset}: END{os.linesep})"
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class ControlFlow:
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def __init__(self, beginning: int, end: int, next_flow: List[int]) -> None:
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self.beginning = beginning
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self.end = end
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self.next_flow = next_flow
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def contains(self, offset: int) -> bool:
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return (self.beginning <= offset) and (offset < self.end)
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def is_first(self, offset: int) -> bool:
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return self.beginning == offset
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def is_last(self, offset: int) -> bool:
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return self.end == (offset + 1)
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def split(self, offset: int, link: bool = False) -> Tuple["ControlFlow", "ControlFlow"]:
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if not self.contains(offset):
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raise Exception(f"This ControlFlow does not contain offset {offset}")
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# First, make the second half that the first half will point to.
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second = ControlFlow(
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offset,
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self.end,
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self.next_flow,
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)
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# Now, make the first half that we can point to.
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first = ControlFlow(
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self.beginning,
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offset,
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[second.beginning] if link else [],
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)
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return (first, second)
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def __repr__(self) -> str:
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return f"ControlFlow(beginning={self.beginning}, end={self.end}, next={(', '.join(str(n) for n in self.next_flow)) or 'N/A'}"
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class ConvertedAction:
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# An action that has been analyzed and converted to an intermediate representation.
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pass
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ArbitraryOpcode = Union[AP2Action, ConvertedAction]
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class BreakStatement(ConvertedAction):
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# A break from a loop (forces execution to the next line after the loop).
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def __repr__(self) -> str:
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return "break;"
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class ContinueStatement(ConvertedAction):
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# A continue in a loop (forces execution to the top of the loop).
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def __repr__(self) -> str:
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return "continue;"
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class GotoStatement(ConvertedAction):
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# A goto, including the ID of the chunk we want to jump to.
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def __init__(self, location: int) -> None:
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self.location = location
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def __repr__(self) -> str:
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return f"goto label_{self.location};"
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class IntermediateIfStatement(ConvertedAction):
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def __init__(self, parent_action: IfAction, true_actions: Sequence[ArbitraryOpcode], false_actions: Sequence[ArbitraryOpcode], negate: bool) -> None:
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self.parent_action = parent_action
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self.true_actions = list(true_actions)
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self.false_actions = list(false_actions)
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self.negate = negate
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def __repr__(self) -> str:
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true_entries: List[str] = []
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for action in self.true_actions:
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true_entries.extend([f" {s}" for s in str(action).split(os.linesep)])
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false_entries: List[str] = []
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for action in self.false_actions:
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false_entries.extend([f" {s}" for s in str(action).split(os.linesep)])
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if self.false_actions:
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return os.linesep.join([
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f"if <{'!' if self.negate else ''}{self.parent_action}> {{",
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os.linesep.join(true_entries),
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"} else {",
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os.linesep.join(false_entries),
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"}"
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])
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else:
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return os.linesep.join([
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f"if <{'!' if self.negate else ''}{self.parent_action}> {{",
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os.linesep.join(true_entries),
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"}"
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])
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class ByteCodeChunk:
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def __init__(self, id: int, actions: Sequence[ArbitraryOpcode], next_chunks: List[int], previous_chunks: List[int] = []) -> None:
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self.id = id
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self.actions = list(actions)
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self.next_chunks = next_chunks
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self.previous_chunks = previous_chunks or []
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def __repr__(self) -> str:
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entries: List[str] = []
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for action in self.actions:
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if isinstance(action, DefineFunction2Action):
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# Special case, since we will decompile this later, we don't want to print it now.
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entries.append(f" {action.offset}: {AP2Action.action_to_name(action.opcode)}, Name: {action.name or '<anonymous function>'}, Flags: {hex(action.flags)}")
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else:
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entries.extend([f" {s}" for s in str(action).split(os.linesep)])
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return (
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f"ByteCodeChunk({os.linesep}" +
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f" ID: {self.id}{os.linesep}" +
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(f" Previous Chunks: {', '.join(str(n) for n in self.previous_chunks)}{os.linesep}" if self.previous_chunks else f" Start Chunk{os.linesep}") +
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f"{os.linesep.join(entries)}{os.linesep}" +
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(f" Next Chunks: {', '.join(str(n) for n in self.next_chunks)}{os.linesep}" if self.next_chunks else f" End Chunk{os.linesep}") +
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")"
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)
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ArbitraryCodeChunk = Union[ByteCodeChunk, "Loop"]
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class Loop:
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def __init__(self, id: int, chunks: Sequence[ArbitraryCodeChunk]) -> None:
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# The ID is usually the chunk that other chunks point into.
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self.id = id
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# Calculate predecessors (who points into it) and successors (who we point out of).
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ided_chunks: Dict[int, ArbitraryCodeChunk] = {chunk.id: chunk for chunk in chunks}
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self.previous_chunks: List[int] = []
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self.next_chunks: List[int] = []
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self.chunks = list(chunks)
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for chunk in chunks:
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for nextid in chunk.next_chunks:
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if nextid not in ided_chunks:
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self.next_chunks.append(nextid)
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for previd in chunk.previous_chunks:
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if previd not in ided_chunks:
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self.previous_chunks.append(previd)
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def __repr__(self) -> str:
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entries: List[str] = []
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for chunk in self.chunks:
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entries.extend([f" {s}" for s in str(chunk).split(os.linesep)])
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return (
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f"Loop({os.linesep}" +
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f" ID: {self.id}{os.linesep}" +
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(f" Previous Chunks: {', '.join(str(n) for n in self.previous_chunks)}{os.linesep}" if self.previous_chunks else f" Start Chunk{os.linesep}") +
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f"{os.linesep.join(entries)}{os.linesep}" +
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(f" Next Chunks: {', '.join(str(n) for n in self.next_chunks)}{os.linesep}" if self.next_chunks else f" End Chunk{os.linesep}") +
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")"
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)
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class BitVector:
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def __init__(self, length: int, init: bool = False) -> None:
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self.__bits: Dict[int, bool] = {i: init for i in range(length)}
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def clone(self) -> "BitVector":
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new = BitVector(len(self.__bits))
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new.__bits = {i: self.__bits[i] for i in self.__bits}
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return new
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def setAllBitsTo(self, val: bool) -> "BitVector":
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self.__bits = {i: val for i in self.__bits}
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return self
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def setBit(self, bit: int) -> "BitVector":
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self.__bits[bit] = True
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return self
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def clearBit(self, bit: int) -> "BitVector":
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self.__bits[bit] = False
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return self
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def orVector(self, other: "BitVector") -> "BitVector":
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if len(self.__bits) != len(other.__bits):
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raise Exception("Cannot or different-sized bitvectors!")
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self.__bits = {i: (self.__bits[i] or other.__bits[i]) for i in self.__bits}
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return self
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def andVector(self, other: "BitVector") -> "BitVector":
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if len(self.__bits) != len(other.__bits):
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raise Exception("Cannot and different-sized bitvectors!")
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self.__bits = {i: (self.__bits[i] and other.__bits[i]) for i in self.__bits}
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return self
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def __eq__(self, other: object) -> bool:
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if not isinstance(other, BitVector):
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return NotImplemented
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if len(self.__bits) != len(other.__bits):
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raise Exception("Cannot compare different-sized bitvectors!")
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for i in self.__bits:
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if self.__bits[i] != other.__bits[i]:
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return False
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return True
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def __ne__(self, other: object) -> bool:
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return not self.__eq__(other)
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@property
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def bitsSet(self) -> Set[int]:
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return {i for i in self.__bits if self.__bits[i]}
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class ByteCodeDecompiler(VerboseOutput):
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def __init__(self, bytecode: ByteCode) -> None:
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super().__init__()
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self.bytecode = bytecode
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def __graph_control_flow(self) -> Tuple[List[ByteCodeChunk], Dict[int, int]]:
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# Start by assuming that the whole bytecode never directs flow. This is, confusingly,
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# indexed by AP2Action offset, not by actual bytecode offset, so we can avoid the
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# prickly problem of opcodes that take more than one byte in the data.
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flows: Dict[int, ControlFlow] = {}
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end = len(self.bytecode.actions)
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beginning = 0
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# The end of the program.
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flows[end] = ControlFlow(end, end + 1, [])
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# The rest of the program.
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flows[beginning] = ControlFlow(beginning, end, [end])
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# Function that helps us find a flow by position.
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def find(opcodeno: int) -> int:
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for start, cf in flows.items():
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if cf.contains(opcodeno):
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return start
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raise Exception(f"Offset {opcodeno} somehow not in our control flow graph!")
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# Now, walk the entire bytecode, and every control flow point split the graph at that point.
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for i, action in enumerate(self.bytecode.actions):
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current_action = i
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next_action = i + 1
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if action.opcode in [AP2Action.THROW, AP2Action.RETURN]:
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# This should end execution, so we should cap off the current execution
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# and send it to the end.
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current_action_flow = find(current_action)
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next_action_flow = find(next_action)
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if current_action_flow == next_action_flow:
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# We need to split this on the next_action boundary.
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first, second = flows[current_action_flow].split(next_action)
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first.next_flow = [end]
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self.vprint(f"{action} action split {flows[current_action_flow]} into {first}, {second}")
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flows[current_action_flow] = first
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flows[next_action] = second
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else:
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# This already was split in two, presumably by something
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# earlier in the chain jumping to the opcode after this.
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# We need to unlink the current flow from the second and
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# link it to the end.
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flows[current_action_flow].next_flow = [end]
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self.vprint(f"{action} action repointed {flows[current_action_flow]} to end")
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elif action.opcode == AP2Action.JUMP:
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# Unconditional control flow redirection after this, we should split the
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# section if necessary and point this section at the new offset.
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# First, we need to find the jump point and make sure that its the start
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# of a section.
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action = cast(JumpAction, action)
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for j, dest in enumerate(self.bytecode.actions):
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if dest.offset == action.jump_offset:
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dest_action = j
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break
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else:
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raise Exception(f"{action} jumps to an opcode that doesn't exist!")
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# If the destination action flow already starts with the jump offset,
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# then we're good, we just need to point our current split at this new
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# offset. If it doesn't start with the jump offset, then we need to split
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# that flow so we can point to the opcode directly.
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dest_action_flow = find(dest_action)
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if not flows[dest_action_flow].is_first(dest_action):
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first, second = flows[dest_action_flow].split(dest_action, link=True)
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self.vprint(f"{action} action required split of {flows[dest_action_flow]} into {first, second}")
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flows[dest_action_flow] = first
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flows[dest_action] = second
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# Now, the second is what we want to point at in the next section.
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dest_action_flow = dest_action
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# Now, we must split the current flow at the point of this jump.
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current_action_flow = find(current_action)
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next_action_flow = find(next_action)
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if current_action_flow == next_action_flow:
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# We need to split this on the next_action boundary.
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first, second = flows[current_action_flow].split(next_action)
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first.next_flow = [dest_action_flow]
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self.vprint(f"{action} action split {flows[current_action_flow]} into {first}, {second}")
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flows[current_action_flow] = first
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flows[next_action] = second
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else:
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# This already was split in two, presumably by something
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# earlier in the chain jumping to the opcode after this.
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# We need to unlink the current flow from the second and
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# link it to the end.
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flows[current_action_flow].next_flow = [dest_action_flow]
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self.vprint(f"{action} action repointed {flows[current_action_flow]} to new chunk")
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elif action.opcode == AP2Action.IF:
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# Conditional control flow redirection after this, we should split the
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# section if necessary and point this section at the new offset as well
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# as the second half of the split section.
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# First, we need to find the jump point and make sure that its the start
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# of a section.
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action = cast(IfAction, action)
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for j, dest in enumerate(self.bytecode.actions):
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if dest.offset == action.jump_if_true_offset:
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dest_action = j
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break
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else:
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raise Exception(f"{action} conditional jumps to an opcode that doesn't exist!")
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# If the destination action flow already starts with the jump offset,
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# then we're good, we just need to point our current split at this new
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# offset. If it doesn't start with the jump offset, then we need to split
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# that flow so we can point to the opcode directly.
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dest_action_flow = find(dest_action)
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if not flows[dest_action_flow].is_first(dest_action):
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first, second = flows[dest_action_flow].split(dest_action, link=True)
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self.vprint(f"{action} action required split of {flows[dest_action_flow]} into {first, second}")
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flows[dest_action_flow] = first
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flows[dest_action] = second
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# Now, the second is what we want to point at in the next section.
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dest_action_flow = dest_action
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# Now, we must split the current flow at the point of this jump.
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current_action_flow = find(current_action)
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next_action_flow = find(next_action)
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if current_action_flow == next_action_flow:
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# We need to split this on the next_action boundary.
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first, second = flows[current_action_flow].split(next_action)
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first.next_flow = [next_action, dest_action_flow]
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self.vprint(f"{action} action split {flows[current_action_flow]} into {first}, {second}")
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flows[current_action_flow] = first
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flows[next_action] = second
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else:
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# This already was split in two, presumably by something
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# earlier in the chain jumping to the opcode after this.
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# We need to unlink the current flow from the second and
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# link it to the end.
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flows[current_action_flow].next_flow = [next_action, dest_action_flow]
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self.vprint(f"{action} action repointed {flows[current_action_flow]} to new chunk")
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elif action.opcode == AP2Action.IF2:
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# We don't emit this anymore, so this is a problem.
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raise Exception("Logic error!")
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# Finally, return chunks of contiguous execution.
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chunks: List[ByteCodeChunk] = []
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chunkid: int = 0
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for start, flow in flows.items():
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if start == end:
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# We don't want to render out the end of the graph, it was only there to make
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# the above algorithm easier.
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continue
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if len(flow.next_flow) == 1 and flow.next_flow[0] == end:
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# This flow is a termination state.
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chunks.append(ByteCodeChunk(chunkid, self.bytecode.actions[flow.beginning:flow.end], []))
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chunkid += 1
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else:
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next_chunks: List[int] = []
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for ano in flow.next_flow:
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if ano == end:
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raise Exception("Logic error!")
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next_chunks.append(self.bytecode.actions[ano].offset)
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chunks.append(ByteCodeChunk(chunkid, self.bytecode.actions[flow.beginning:flow.end], next_chunks))
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chunkid += 1
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# Calculate who points to us as well, for posterity.
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entries: Dict[int, List[int]] = {}
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offset_to_id: Dict[int, int] = {}
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for chunk in chunks:
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# We haven't emitted any non-AP2Actions yet, so we are safe in casting here.
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chunk_offset = cast(AP2Action, chunk.actions[0]).offset
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offset_to_id[chunk_offset] = chunk.id
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for next_chunk in chunk.next_chunks:
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entries[next_chunk] = entries.get(next_chunk, []) + [chunk_offset]
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for chunk in chunks:
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# We haven't emitted any non-AP2Actions yet, so we are safe in casting here.
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chunk_offset = cast(AP2Action, chunk.actions[0]).offset
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chunk.previous_chunks = entries.get(chunk_offset, [])
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# Now, convert the offsets to chunk ID pointers.
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end_previous_chunks: List[int] = []
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for chunk in chunks:
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if chunk.next_chunks:
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# Normal chunk.
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chunk.next_chunks = [offset_to_id[c] for c in chunk.next_chunks]
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else:
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# Point this chunk at the end of bytecode sentinel.
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chunk.next_chunks = [chunkid]
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end_previous_chunks.append(chunk.id)
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chunk.previous_chunks = [offset_to_id[c] for c in chunk.previous_chunks]
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|
|
# Add the "return" chunk now that we've converted everything.
|
|
chunks.append(ByteCodeChunk(chunkid, [], [], previous_chunks=end_previous_chunks))
|
|
offset_to_id[self.bytecode.end_offset] = chunkid
|
|
|
|
return (sorted(chunks, key=lambda c: c.id), offset_to_id)
|
|
|
|
def __get_entry_block(self, chunks: Sequence[ByteCodeChunk]) -> int:
|
|
start_id: int = -1
|
|
for chunk in chunks:
|
|
if not chunk.previous_chunks:
|
|
if start_id != -1:
|
|
# This should never happen, we have one entrypoint. If we run into
|
|
# this we might need to do dead code analysis and discarding.
|
|
raise Exception("Logic error!")
|
|
start_id = chunk.id
|
|
|
|
if start_id == -1:
|
|
# We should never get to this as we always have at least one entrypoint.
|
|
raise Exception("Logic error!")
|
|
return start_id
|
|
|
|
def __compute_dominators(self, chunks: Sequence[ByteCodeChunk]) -> Dict[int, Set[int]]:
|
|
# Find the start of the graph (the node with no previous entries).
|
|
start_id = self.__get_entry_block(chunks)
|
|
|
|
# Compute dominators recursively
|
|
chunklen = len(chunks)
|
|
dominators: Dict[int, BitVector] = {chunk.id: BitVector(chunklen, init=True) for chunk in chunks}
|
|
dominators[start_id].setAllBitsTo(False).setBit(start_id)
|
|
|
|
changed = True
|
|
while changed:
|
|
changed = False
|
|
|
|
for chunk in chunks:
|
|
if chunk.id == start_id:
|
|
continue
|
|
|
|
for previd in chunk.previous_chunks:
|
|
comparison = dominators[chunk.id].clone()
|
|
dominators[chunk.id].andVector(dominators[previd]).setBit(chunk.id)
|
|
if dominators[chunk.id] != comparison:
|
|
changed = True
|
|
|
|
return {chunk.id: dominators[chunk.id].bitsSet for chunk in chunks}
|
|
|
|
def __analyze_loop_jumps(self, loop: Loop, offset_map: Dict[int, int]) -> Loop:
|
|
# Go through and try to determine which jumps are "break" and "continue" statements based on
|
|
# where they point (to the header or to the exit point). First, let's try to identify all
|
|
# exits, and which one is the break point and which ones are possibly goto statements
|
|
# (break out of multiple loop depths).
|
|
internal_jump_points = {c.id for c in loop.chunks}
|
|
|
|
header_chunks = [c for c in loop.chunks if c.id == loop.id]
|
|
if len(header_chunks) != 1:
|
|
# Should never happen, only one should match ID.
|
|
raise Exception("Logic error!")
|
|
header_chunk = header_chunks[0]
|
|
|
|
# Identify external jumps from the header.
|
|
break_points = [i for i in header_chunk.next_chunks if i not in internal_jump_points]
|
|
if len(break_points) > 1:
|
|
# We should not have two exits here, if so this isn't a loop!
|
|
raise Exception("Logic error!")
|
|
|
|
# Identify the break and continue jump points.
|
|
if not break_points:
|
|
# This might be possible, but I don't know how to deal with it.
|
|
raise Exception("Logic error!")
|
|
break_point = break_points[0]
|
|
continue_point = header_chunk.id
|
|
|
|
self.vprint(f"Loop breaks to {break_point} and continues to {continue_point}")
|
|
|
|
# Now, go through each chunk, identify whether it has an if, and fix up the
|
|
# if statements.
|
|
for chunk in loop.chunks:
|
|
if not chunk.next_chunks:
|
|
# All chunks need a next chunk of some type, the only one that doesn't
|
|
# is the end chunk which should never be part of a loop.
|
|
raise Exception("Logic error!")
|
|
if not isinstance(chunk, ByteCodeChunk):
|
|
# We don't need to fix up loops, we already did this in a previous
|
|
# fixup.
|
|
continue
|
|
|
|
last_action = chunk.actions[-1]
|
|
if isinstance(last_action, AP2Action):
|
|
if last_action.opcode in [AP2Action.THROW, AP2Action.RETURN]:
|
|
# Ignore these for now, we'll fix these up in a later stage.
|
|
continue
|
|
|
|
if last_action.opcode == AP2Action.JUMP:
|
|
# This is either an unconditional break/continue or an
|
|
# internal jump.
|
|
if len(chunk.next_chunks) != 1:
|
|
raise Exception("Logic error!")
|
|
next_chunk = chunk.next_chunks[0]
|
|
|
|
if next_chunk == break_point:
|
|
self.vprint("Converting jump to loop break into break statement.")
|
|
chunk.actions[-1] = BreakStatement()
|
|
chunk.next_chunks = []
|
|
elif next_chunk == continue_point:
|
|
self.vprint("Converting jump to loop continue into continue statement.")
|
|
chunk.actions[-1] = ContinueStatement()
|
|
chunk.next_chunks = []
|
|
elif next_chunk not in internal_jump_points:
|
|
self.vprint("Converting jump to external point into goto statement.")
|
|
chunk.actions[-1] = GotoStatement(next_chunk)
|
|
chunk.next_chunks = []
|
|
continue
|
|
|
|
if last_action.opcode == AP2Action.IF:
|
|
# Calculate true and false jump points.
|
|
true_jump_point = offset_map[cast(IfAction, last_action).jump_if_true_offset]
|
|
false_jump_points = [n for n in chunk.next_chunks if n != true_jump_point]
|
|
if len(false_jump_points) != 1:
|
|
raise Exception("Logic error!")
|
|
false_jump_point = false_jump_points[0]
|
|
|
|
# Calculate true and false jump points, see if they are break/continue/goto.
|
|
true_action: Optional[ConvertedAction] = None
|
|
if true_jump_point == break_point:
|
|
self.vprint("Converting jump if true to loop break into break statement.")
|
|
true_action = BreakStatement()
|
|
chunk.next_chunks = [n for n in chunk.next_chunks if n != true_jump_point]
|
|
elif true_jump_point == continue_point:
|
|
self.vprint("Converting jump if true to loop continue into continue statement.")
|
|
true_action = ContinueStatement()
|
|
chunk.next_chunks = [n for n in chunk.next_chunks if n != true_jump_point]
|
|
elif true_jump_point not in internal_jump_points:
|
|
self.vprint("Converting jump if true to external point into goto statement.")
|
|
true_action = GotoStatement(true_jump_point)
|
|
chunk.next_chunks = [n for n in chunk.next_chunks if n != true_jump_point]
|
|
|
|
false_action: Optional[ConvertedAction] = None
|
|
if false_jump_point == break_point:
|
|
self.vprint("Converting jump if false to loop break into break statement.")
|
|
false_action = BreakStatement()
|
|
chunk.next_chunks = [n for n in chunk.next_chunks if n != false_jump_point]
|
|
elif false_jump_point == continue_point:
|
|
self.vprint("Converting jump if false to loop continue into continue statement.")
|
|
false_action = ContinueStatement()
|
|
chunk.next_chunks = [n for n in chunk.next_chunks if n != false_jump_point]
|
|
elif false_jump_point not in internal_jump_points:
|
|
self.vprint("Converting jump if false to external point into goto statement.")
|
|
false_action = GotoStatement(false_jump_point)
|
|
chunk.next_chunks = [n for n in chunk.next_chunks if n != false_jump_point]
|
|
|
|
if true_action is None and false_action is not None:
|
|
true_action = false_action
|
|
false_action = None
|
|
negate = True
|
|
else:
|
|
negate = False
|
|
|
|
if true_action is None and false_action is None:
|
|
# This is an internal-only if statement, we don't care.
|
|
continue
|
|
|
|
chunk.actions[-1] = IntermediateIfStatement(
|
|
cast(IfAction, last_action),
|
|
[true_action],
|
|
[false_action] if false_action else [],
|
|
negate=negate,
|
|
)
|
|
continue
|
|
|
|
# Now, we have converted all external jumps to either break or goto, so we don't
|
|
# need to keep track of the next chunk aside from the break location.
|
|
loop.next_chunks = [break_point]
|
|
|
|
return loop
|
|
|
|
def __separate_loops(self, chunks: Sequence[ByteCodeChunk], dominators: Dict[int, Set[int]], offset_map: Dict[int, int]) -> List[Union[ByteCodeChunk, Loop]]:
|
|
# Find the start of the graph (the node with no previous entries).
|
|
start_id = self.__get_entry_block(chunks)
|
|
chunks_by_id: Dict[int, Union[ByteCodeChunk, Loop]] = {chunk.id: chunk for chunk in chunks}
|
|
|
|
# Go through and gather up all loops in the chunks.
|
|
loops: Dict[int, Set[int]] = {}
|
|
for chunk in chunks:
|
|
if chunk.id == start_id:
|
|
continue
|
|
|
|
for nextid in chunk.next_chunks:
|
|
# If this next chunk dominates us, then that means we found a loop.
|
|
if nextid in dominators[chunk.id]:
|
|
# Calculate the blocks that are in this loop.
|
|
header = nextid
|
|
tail = chunk.id
|
|
blocks = {header}
|
|
|
|
# If we don't already have a loop of one block,
|
|
# we need to walk backwards to find all blocks in this
|
|
# loop.
|
|
if header != tail:
|
|
blocks.add(tail)
|
|
blocks_to_examine = [tail]
|
|
|
|
while blocks_to_examine:
|
|
block = blocks_to_examine.pop()
|
|
for predecessor in chunks_by_id[block].previous_chunks:
|
|
if predecessor not in blocks:
|
|
blocks.add(predecessor)
|
|
blocks_to_examine.append(predecessor)
|
|
|
|
self.vprint(f"Found loop with header {header} and blocks {', '.join(str(b) for b in blocks)}.")
|
|
|
|
# We found a loop!
|
|
if header in loops:
|
|
raise Exception("Logic error!")
|
|
loops[header] = blocks
|
|
|
|
# Now, we need to reduce our list of chunks down to non-loops only. We do this
|
|
# by recursively trying to find inner loops until we find a loop that has no
|
|
# inner loops, and converting that. Once we do that, we remove the chunks from
|
|
# our list, add it to that new loop, and convert all other loops that might
|
|
# reference it to point at the loop instead.
|
|
while loops:
|
|
delete_header: Optional[int] = None
|
|
delete_blocks: Set[int] = set()
|
|
for header, blocks in loops.items():
|
|
# See if any of the blocks in this loop are the header of any other loop.
|
|
for block in blocks:
|
|
if block in loops and loops[block] is not blocks:
|
|
# This particular block of code is the header of another loop,
|
|
# so we shouldn't convert this loop until we handle the inner
|
|
# loop.
|
|
break
|
|
else:
|
|
# This loop does not contain any loops of its own. It is safe to
|
|
# convert.
|
|
self.vprint(f"Converting loop with header {header} and blocks {', '.join(str(b) for b in blocks)}.")
|
|
new_loop = Loop(header, [chunks_by_id[i] for i in blocks])
|
|
|
|
# Eliminate jumps that are to the beginning/end of the loop to
|
|
# make if statement detection later on easier.
|
|
new_loop = self.__analyze_loop_jumps(new_loop, offset_map)
|
|
chunks_by_id[header] = new_loop
|
|
|
|
# These blocks are now part of the loop, so we need to remove them
|
|
# from the IDed chunks as well as from existing loops.
|
|
delete_blocks = {block for block in blocks if block != header}
|
|
delete_header = header
|
|
break
|
|
|
|
if delete_header is None:
|
|
# We must find at LEAST one loop that has no inner loops of its own.
|
|
raise Exception("Logic error!")
|
|
|
|
# Remove this loop from the processing list
|
|
del loops[delete_header]
|
|
|
|
# Go through and remove the rest of the chunks from the rest of the loops
|
|
loops = {header: {block for block in blocks if block not in delete_blocks} for (header, blocks) in loops.items()}
|
|
|
|
# Also remove the rest of the chunks from our IDed chunks as they are part of this loop now.
|
|
for block in delete_blocks:
|
|
del chunks_by_id[block]
|
|
|
|
# Verify that we don't have any existing chunks that point at the non-header portion of the loop.
|
|
for _, chunk_or_loop in chunks_by_id.items():
|
|
for nextid in chunk_or_loop.next_chunks:
|
|
if nextid in delete_blocks:
|
|
# Woah, we point at a chunk inside this loop that isn't the header!
|
|
raise Exception("Logic error!")
|
|
|
|
return [chunks_by_id[i] for i in chunks_by_id]
|
|
|
|
def __separate_ifs(self, chunks: Sequence[Union[ByteCodeChunk, Loop]], offset_map: Dict[int, int]) -> List[ArbitraryCodeChunk]:
|
|
return [c for c in chunks]
|
|
|
|
def __decompile(self) -> str:
|
|
# First, we need to construct a control flow graph.
|
|
self.vprint("Generating control flow graph...")
|
|
chunks, offset_map = self.__graph_control_flow()
|
|
|
|
# Now, compute dominators so we can locate back-refs.
|
|
self.vprint("Generating dominator list...")
|
|
dominators = self.__compute_dominators(chunks)
|
|
|
|
# Now, separate chunks out into chunks and loops.
|
|
self.vprint("Identifying and separating loops...")
|
|
chunks_and_loops = self.__separate_loops(chunks, dominators, offset_map)
|
|
|
|
# Now, identify any remaining control flow logic.
|
|
self.vprint("Identifying and separating ifs...")
|
|
chunks_loops_and_ifs = self.__separate_ifs(chunks_and_loops, offset_map)
|
|
|
|
# At this point, we *should* have a directed graph where there are no
|
|
# backwards refs and every fork has been identified as an if. This means
|
|
# we can now walk and recursively generate pseudocode in one pass.
|
|
self.vprint(chunks_loops_and_ifs)
|
|
|
|
return "TODO"
|
|
|
|
def decompile(self, verbose: bool = False) -> str:
|
|
with self.debugging(verbose):
|
|
return self.__decompile()
|