Cool_Tools/bemaniutils
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mirror of synced 2024-09-24 03:18:22 +02:00
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Several more code output optimizations done.

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This commit is contained in:
Jennifer Taylor 2021-05-04 02:32:04 +00:00
parent 44b3628a85
commit eddb8dc208
2 changed files with 124 additions and 16 deletions
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132
bemani/format/afp/decompile.py
View File

@ -1057,7 +1057,7 @@ class BitVector:
class ByteCodeDecompiler(VerboseOutput):
def __init__(self, bytecode: ByteCode, optimize: bool = False) -> None:
def __init__(self, bytecode: ByteCode, optimize: bool = True) -> None:
super().__init__()
self.bytecode = bytecode
@ -3015,6 +3015,89 @@ class ByteCodeDecompiler(VerboseOutput):
return statements
def __remove_goto_return(self, statements: Sequence[Statement]) -> Tuple[List[Statement], bool]:
# Go through and find labels that point at returns, convert any gotos pointing
# at them to returns.
def find_labels(statements: Sequence[Statement], next_statement: Optional[Statement]) -> Set[int]:
labels: Set[int] = set()
for i in range(len(statements)):
cur_statement = statements[i]
next_statement = statements[i + 1] if (i < len(statements) - 1) else next_statement
if (
isinstance(cur_statement, DefineLabelStatement) and
isinstance(next_statement, NullReturnStatement)
):
labels.add(cur_statement.location)
elif isinstance(cur_statement, DoWhileStatement):
labels.update(find_labels(cur_statement.body, next_statement))
elif isinstance(cur_statement, IfStatement):
labels.update(find_labels(cur_statement.true_statements, next_statement))
labels.update(find_labels(cur_statement.false_statements, next_statement))
return labels
labels = find_labels(statements, None)
updated: bool = False
def update_gotos(statement: Statement) -> Statement:
nonlocal updated
if isinstance(statement, GotoStatement):
if statement.location in labels:
return NullReturnStatement()
updated = True
return statement
statements = self.__walk(statements, update_gotos)
return statements, updated
def __eliminate_useless_returns(self, statements: Sequence[Statement]) -> Tuple[List[Statement], bool]:
# Go through and find returns that are on the "last" line. Basically, any
# return statement where the next return statement is another return statement
# or the end of a function.
def find_returns(statements: Sequence[Statement], next_statement: Statement) -> Set[NullReturnStatement]:
returns: Set[NullReturnStatement] = set()
for i in range(len(statements)):
cur_statement = statements[i]
next_statement = statements[i + 1] if (i < len(statements) - 1) else next_statement
if (
isinstance(cur_statement, NullReturnStatement) and
isinstance(next_statement, NullReturnStatement)
):
returns.add(cur_statement)
elif isinstance(cur_statement, DoWhileStatement):
returns.update(find_returns(cur_statement.body, next_statement))
elif isinstance(cur_statement, IfStatement):
returns.update(find_returns(cur_statement.true_statements, next_statement))
returns.update(find_returns(cur_statement.false_statements, next_statement))
return returns
# Instead of an empty next statement, make up a return so we catch anything
# without needing multiple conditionals above.
returns = find_returns(statements, NullReturnStatement())
updated: bool = False
def remove_returns(statement: Statement) -> Statement:
nonlocal updated
for removable in returns:
if removable is statement:
updated = True
return None
return statement
statements = self.__walk(statements, remove_returns)
return statements, updated
def __remove_useless_gotos(self, statements: Sequence[Statement]) -> Tuple[List[Statement], bool]:
# Go through and find gotos that point at the very next line and remove them.
# This can happen due to the way we analyze if statements.
@ -3092,33 +3175,49 @@ class ByteCodeDecompiler(VerboseOutput):
return self.__walk(statements, remove_label), changed
def __eliminate_useless_control_flows(self, statements: Sequence[Statement]) -> List[Statement]:
def __eliminate_useless_continues(self, statements: Sequence[Statement]) -> Tuple[List[Statement], bool]:
# Go through and find continue statements on the last line of a do-while.
changed: bool = False
def remove_continue(statement: Statement) -> Optional[Statement]:
nonlocal changed
if isinstance(statement, DoWhileStatement):
if statement.body and isinstance(statement.body[-1], ContinueStatement):
changed = True
statement.body.pop()
return statement
statements = self.__walk(statements, remove_continue)
if isinstance(statements[-1], NullReturnStatement):
return statements[:-1]
return statements
return statements, changed
def __swap_empty_ifs(self, statements: Sequence[Statement]) -> List[Statement]:
# Go through and find continue statements on the last line of a do-while.
changed: bool = False
def swap_empty_ifs(statement: Statement) -> Optional[Statement]:
nonlocal changed
if isinstance(statement, IfStatement):
if statement.false_statements and (not statement.true_statements):
# Swap this, invert the conditional
changed = True
return IfStatement(
statement.cond.invert(),
statement.false_statements,
statement.true_statements,
)
elif (not statement.true_statements) and (not statement.false_statements):
# Drop the if, it has no body.
changed = True
return None
return statement
return self.__walk(statements, swap_empty_ifs)
while True:
changed = False
statements = self.__walk(statements, swap_empty_ifs)
if not changed:
return statements
def __verify_balanced_labels(self, statements: Sequence[Statement]) -> None:
gotos: Set[int] = set()
@ -3199,12 +3298,25 @@ class ByteCodeDecompiler(VerboseOutput):
# Now, let's do some clean-up passes.
if self.optimize:
statements = self.__collapse_identical_labels(statements)
statements = self.__eliminate_useless_control_flows(statements)
while True:
statements, changed1 = self.__eliminate_unused_labels(statements)
statements, changed2 = self.__remove_useless_gotos(statements)
any_changed = False
if not changed1 and not changed2:
statements, changed = self.__eliminate_useless_continues(statements)
any_changed = any_changed or changed
statements, changed = self.__eliminate_unused_labels(statements)
any_changed = any_changed or changed
statements, changed = self.__remove_useless_gotos(statements)
any_changed = any_changed or changed
statements, changed = self.__remove_goto_return(statements)
any_changed = any_changed or changed
statements, changed = self.__eliminate_useless_returns(statements)
any_changed = any_changed or changed
if not any_changed:
break
statements = self.__swap_empty_ifs(statements)

8
bemani/tests/test_afp_decompile.py
View File

@ -663,9 +663,7 @@ class TestAFPDecompile(ExtendedTestCase):
AP2Action(104, AP2Action.PLAY),
])
statements = self.__call_decompile(bytecode)
# TODO: The output should be optimized to remove redundant return statements.
self.assertEqual(self.__equiv(statements), ["if (True) {\n builtin_StartPlaying()\n return\n} else {\n builtin_StopPlaying()\n return\n}"])
self.assertEqual(self.__equiv(statements), ["if (True) {\n builtin_StartPlaying()\n} else {\n builtin_StopPlaying()\n}"])
def test_if_handling_diamond_return_to_end(self) -> None:
# If true-false diamond case but the cases never converge.
@ -747,9 +745,7 @@ class TestAFPDecompile(ExtendedTestCase):
AP2Action(105, AP2Action.END),
])
statements = self.__call_decompile(bytecode)
# TODO: The output should be optimized to remove redundant return statements.
self.assertEqual(self.__equiv(statements), ["if (True) {\n builtin_StartPlaying()\n return\n} else {\n builtin_StopPlaying()\n return\n}"])
self.assertEqual(self.__equiv(statements), ["if (True) {\n builtin_StartPlaying()\n} else {\n builtin_StopPlaying()\n}"])
def test_if_handling_or(self) -> None:
# Two ifs that together make an or (if register == 1 or register == 3)