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It seems that some bytecode leaves extra stuff on the stack sometimes, I think this is fine?

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This commit is contained in:
Jennifer Taylor
2021-05-04 02:29:27 +00:00
parent 70c7448aa0
commit 54b4c88d65
1 changed files with 30 additions and 6 deletions
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36
bemani/format/afp/decompile.py
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@@ -143,7 +143,7 @@ class Statement(ConvertedAction):
def object_ref(obj: Any, parent_prefix: str) -> str:
if isinstance(obj, (GenericObject, Variable, TempVariable, BorrowedStackEntry, Member, MethodCall, FunctionCall, Register)):
if isinstance(obj, (GenericObject, Variable, TempVariable, Member, MethodCall, FunctionCall, Register)):
return obj.render(parent_prefix, nested=True)
else:
raise Exception(f"Unsupported objectref {obj} ({type(obj)})")
@@ -2742,11 +2742,31 @@ class ByteCodeDecompiler(VerboseOutput):
def reconcile_stacks(cur_chunk: int, new_stack_id: int, new_stack: List[Any]) -> List[Statement]:
if new_stack_id in stacks:
if len(stacks[new_stack_id]) != len(new_stack):
raise Exception(f"Logic error, cannot reconcile {stacks[new_stack_id]} with {new_stack}!")
if cur_chunk == other_stack_locs[new_stack_id]:
raise Exception("Logic error, cannot reconcile variable names with self!")
other_chunk = other_stack_locs[new_stack_id]
if len(stacks[new_stack_id]) != len(new_stack):
min_len = min(len(stacks[new_stack_id]), len(new_stack))
max_len = max(len(stacks[new_stack_id]), len(new_stack))
borrows = max_len - min_len
if borrows <= 0:
raise Exception("Logic error!")
# It doesn't matter what it is, just mark the stack entry as being poisoned since
# we couldn't reconcile it. We want to throw an exception down the line if we
# run into this value, as we needed it but only sometimes got it.
borrow_vals = [BorrowedStackEntry(new_stack_id, -1) for _ in range(borrows)]
if min_len > 0:
stacks[new_stack_id] = [*borrow_vals, *stacks[new_stack_id][-min_len:]]
new_stack = [*borrow_vals, new_stack[-min_len:]]
else:
stacks[new_stack_id] = [*borrow_vals]
new_stack = [*borrow_vals]
self.vprint(f"Chopped off {borrows} values from longest stack and replaced with BorrowedStackEntry for {new_stack_id}")
if len(new_stack) != len(stacks[new_stack_id]):
raise Exception(f"Logic error, expected {new_stack} and {stacks[new_stack_id]} to be equal length!")
self.vprint(
f"Merging stack {stacks[new_stack_id]} for chunk ID {new_stack_id} with {new_stack}, " +
@@ -2782,10 +2802,11 @@ class ByteCodeDecompiler(VerboseOutput):
else:
stack.append(new_entry)
self.vprint(f"Redefining stack for chunk ID {new_stack_id} to be {stack} after merging multiple paths")
stacks[new_stack_id] = stack
return definitions
else:
self.vprint(f"Defining stack for chunk ID {new_stack_id} to be {new_stack}")
self.vprint(f"Defining stack for chunk ID {new_stack_id} to be {new_stack} based on evaluation of {cur_chunk}")
other_stack_locs[new_stack_id] = cur_chunk
stacks[new_stack_id] = new_stack
return []
@@ -2821,7 +2842,7 @@ class ByteCodeDecompiler(VerboseOutput):
del stacks[chunk.id]
# Calculate the statements for this chunk, as well as the leftover stack entries and any borrows.
self.vprint(f"Evaluating graph of ByteCodeChunk {chunk.id}")
self.vprint(f"Evaluating graph of ByteCodeChunk {chunk.id} with stack {stack}")
new_statements, stack_leftovers, new_borrowed_entries = self.__eval_stack(chunk, stack, offset_map)
borrowed_entries.extend(new_borrowed_entries)
@@ -2860,6 +2881,7 @@ class ByteCodeDecompiler(VerboseOutput):
# The stack for both of these is the leftovers from the previous evaluation as they
# rollover.
stacks[true_start] = [s for s in stack_leftovers]
self.vprint(f"True start {true_start} of IfBody has stack {stacks[true_start]}")
true_statements, true_borrowed_entries = self.__eval_chunks_impl(
true_start,
if_body_chunk.true_chunks,
@@ -2881,6 +2903,7 @@ class ByteCodeDecompiler(VerboseOutput):
# The stack for both of these is the leftovers from the previous evaluation as they
# rollover.
stacks[false_start] = [s for s in stack_leftovers]
self.vprint(f"False start {false_start} of IfBody has stack {stacks[false_start]}")
false_statements, false_borrowed_entries = self.__eval_chunks_impl(
false_start,
if_body_chunk.false_chunks,
@@ -2908,7 +2931,7 @@ class ByteCodeDecompiler(VerboseOutput):
last_new_statement = new_statements[-1]
if isinstance(last_new_statement, GotoStatement):
new_next_id = last_new_statement.location
if isinstance(last_new_statement, ReturnStatement):
if isinstance(last_new_statement, (ThrowStatement, NullReturnStatement, ReturnStatement)):
new_next_id = None
if new_next_id:
@@ -2919,6 +2942,7 @@ class ByteCodeDecompiler(VerboseOutput):
new_statements = new_statements[:-1]
new_statements.extend(sentinels)
else:
stack_leftovers = [s for s in stack_leftovers if not isinstance(s, BorrowedStackEntry)]
if stack_leftovers:
raise Exception(f"Logic error, reached execution end and have stack entries {stack_leftovers} still!")