Cool_Tools/bemaniutils
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mirror of synced 2024-11-24 06:20:12 +01:00
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Add a graph walker at the very end to verify that we've handled all control paths correctly, fix an edge case in If detection.

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Jennifer Taylor 2021-04-24 18:03:24 +00:00
parent 6aa04b0c1b
commit aebc277b62
1 changed files with 61 additions and 11 deletions
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70
bemani/format/afp/decompile.py
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@ -171,7 +171,7 @@ ArbitraryCodeChunk = Union[ByteCodeChunk, "Loop", "IfBody"]
class Loop:
def __init__(self, id: int, chunks: Sequence[ArbitraryCodeChunk]) -> None:
# The ID is usually the chunk that other chunks point into.
# The ID is the chunk that other chunks point into, aka the loop header.
self.id = id
# Calculate predecessors (who points into it) and successors (who we point out of).
@ -206,7 +206,8 @@ class Loop:
class IfBody:
def __init__(self, id: int, true_chunks: Sequence[ArbitraryCodeChunk], false_chunks: Sequence[ArbitraryCodeChunk], next_chunk: Optional[int], previous_chunk: int, negate: bool) -> None:
# The ID is usually the chunk that other chunks point into.
# The ID in this case is what the previous block points at. It does not
# have any bearing on the ID of the true and false chunks.
self.id = id
# If bodies are a bit special compared to Loops, we know the previous and next chunks
@ -509,7 +510,7 @@ class ByteCodeDecompiler(VerboseOutput):
return (sorted(chunks, key=lambda c: c.id), offset_to_id)
def __get_entry_block(self, chunks: Sequence[Union[ByteCodeChunk, Loop]]) -> int:
def __get_entry_block(self, chunks: Sequence[ArbitraryCodeChunk]) -> int:
start_id: int = -1
for chunk in chunks:
if not chunk.previous_chunks:
@ -872,9 +873,11 @@ class ByteCodeDecompiler(VerboseOutput):
candidates.extend(chunks_by_id[first_candidate].next_chunks)
# The chunk list is all chunks that belong in this sequence. Now, kill any pointers to the end chunk.
if end_chunk is not None:
for chunk in chunks:
if end_chunk is not None:
chunk.next_chunks = [n for n in chunk.next_chunks if n != end_chunk]
if chunk.id == start_chunk:
chunk.previous_chunks = []
return chunks
@ -884,13 +887,17 @@ class ByteCodeDecompiler(VerboseOutput):
self.vprint(f"Separating if statements out of graph starting at {start_id}")
while chunks_by_id[cur_id].next_chunks:
while True:
cur_chunk = chunks_by_id[cur_id]
if isinstance(cur_chunk, Loop):
self.vprint(f"Examining loop {cur_chunk.id} body for if statements...")
cur_chunk.chunks = self.__separate_ifs(cur_chunk.id, cur_chunk.chunks, offset_map)
self.vprint(f"Finished examining loop {cur_chunk.id} body for if statements...")
if not chunks_by_id[cur_id].next_chunks:
# We're done!
break
if len(chunks_by_id[cur_id].next_chunks) == 1:
# This is just a goto/chunk, move on to the next one.
cur_id = chunks_by_id[cur_id].next_chunks[0]
@ -918,9 +925,6 @@ class ByteCodeDecompiler(VerboseOutput):
true_jump_point = offset_map[last_action.jump_if_true_offset]
false_jump_points = [n for n in cur_chunk.next_chunks if n != true_jump_point]
if len(false_jump_points) != 1:
self.vprint(chunks)
self.vprint(f"Jump has {last_action.jump_if_true_offset} which maps to {offset_map[last_action.jump_if_true_offset]}")
self.vprint(f"Jump branches to {cur_chunk.next_chunks}")
raise Exception("Logic error!")
false_jump_point = false_jump_points[0]
@ -936,7 +940,6 @@ class ByteCodeDecompiler(VerboseOutput):
# First, grab all the chunks in this if statement body.
true_chunks = self.__gather_chunks(true_jump_point, if_end, chunks_by_id)
self.vprint(true_chunks)
# Delete these chunks from our chunk mapping since we're putting them in an if body.
for chunk in true_chunks:
@ -951,7 +954,6 @@ class ByteCodeDecompiler(VerboseOutput):
# First, grab all the chunks in this if statement body.
false_chunks = self.__gather_chunks(false_jump_point, if_end, chunks_by_id)
self.vprint(false_chunks)
# Delete these chunks from our chunk mapping since we're putting them in an if body.
for chunk in false_chunks:
@ -990,6 +992,50 @@ class ByteCodeDecompiler(VerboseOutput):
self.vprint(f"Finished separating if statements out of graph starting at {start_id}")
return [c for _, c in chunks_by_id.items()]
def __check_graph(self, start_id: int, chunks: Sequence[ArbitraryCodeChunk]) -> List[ArbitraryCodeChunk]:
# Recursively go through and verify that all entries to the graph have only one link.
# Also, clean up the graph.
chunks_by_id: Dict[int, ArbitraryCodeChunk] = {chunk.id: chunk for chunk in chunks}
new_chunks: List[ArbitraryCodeChunk] = []
while True:
cur_chunk = chunks_by_id[start_id]
# First, clean up any code in chunks that contain other chunks.
if isinstance(cur_chunk, Loop):
# Clean up the loop's chunks
self.vprint(f"Cleaning up graph of Loop {cur_chunk.id}")
cur_chunk.chunks = self.__check_graph(cur_chunk.id, cur_chunk.chunks)
elif isinstance(cur_chunk, IfBody):
# Clean up the if's chunks
if cur_chunk.true_chunks:
self.vprint(f"Cleaning up graph of IfBody {cur_chunk.id} true case")
true_start = self.__get_entry_block(cur_chunk.true_chunks)
cur_chunk.true_chunks = self.__check_graph(true_start, cur_chunk.true_chunks)
if cur_chunk.false_chunks:
self.vprint(f"Cleaning up graph of IfBody {cur_chunk.id} false case")
false_start = self.__get_entry_block(cur_chunk.false_chunks)
cur_chunk.false_chunks = self.__check_graph(false_start, cur_chunk.false_chunks)
# Now, check to make sure that we have only one exit pointer.
num_exits = len(cur_chunk.next_chunks)
if num_exits > 1:
self.vprint(chunks)
raise Exception("Logic error!")
# Now, we know this chunk is visited, so we can keep it.
new_chunks.append(cur_chunk)
# Finally, bail if we've hit the end of the list.
if num_exits == 0:
break
# Go to the next one!
start_id = cur_chunk.next_chunks[0]
# Return the tree, stripped of all dead code (most likely just the return sentinel).
return new_chunks
def __decompile(self) -> str:
# First, we need to construct a control flow graph.
self.vprint("Generating control flow graph...")
@ -1016,6 +1062,10 @@ class ByteCodeDecompiler(VerboseOutput):
# 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("Cleaning up and checking graph...")
chunks_loops_and_ifs = self.__check_graph(start_id, chunks_loops_and_ifs)
# TODO: Need to go through and start actually converting statements now.
self.vprint(chunks_loops_and_ifs)
return "TODO"