Enable many more types of switch statements to be detected.
This commit is contained in:
Jennifer Taylor
parent
a8f8b82768
commit
7ca9e6920f
@ -3111,11 +3111,35 @@ class ByteCodeDecompiler(VerboseOutput):
|
||||
statement.false_statements and
|
||||
isinstance(
|
||||
statement.true_statements[-1],
|
||||
(BreakStatement, ContinueStatement, ReturnStatement, NullReturnStatement, ThrowStatement, GotoStatement),
|
||||
(ReturnStatement, NullReturnStatement, ThrowStatement, GotoStatement),
|
||||
) and
|
||||
not isinstance(
|
||||
statement.false_statements[-1],
|
||||
(BreakStatement, ContinueStatement, ReturnStatement, NullReturnStatement, ThrowStatement, GotoStatement),
|
||||
(ReturnStatement, NullReturnStatement, ThrowStatement, GotoStatement),
|
||||
)
|
||||
):
|
||||
# We need to walk both halves still, but once we're done, swap the true/false
|
||||
# locations of the statements, so that the false value can be eliminated at
|
||||
# some later optimization stage.
|
||||
changed = True
|
||||
false_statements, _ = update_ifs(statement.true_statements)
|
||||
true_statements, _ = update_ifs(statement.false_statements)
|
||||
|
||||
# Now, append the if statement, and follow up with the body.
|
||||
statement.true_statements = true_statements
|
||||
statement.false_statements = false_statements
|
||||
statement.cond = statement.cond.invert()
|
||||
new_statements.append(statement)
|
||||
elif (
|
||||
statement.true_statements and
|
||||
statement.false_statements and
|
||||
isinstance(
|
||||
statement.true_statements[-1],
|
||||
(BreakStatement, ContinueStatement),
|
||||
) and
|
||||
not isinstance(
|
||||
statement.false_statements[-1],
|
||||
(BreakStatement, ContinueStatement),
|
||||
)
|
||||
):
|
||||
# We need to walk both halves still, but once we're done, hoist the false
|
||||
@ -3283,8 +3307,6 @@ class ByteCodeDecompiler(VerboseOutput):
|
||||
# First, is the current combination a valid combined or statement?
|
||||
candidate_true_expr = get_compound_if(candidate_statements)
|
||||
candidate_false_expr = candidate_true_expr.invert().simplify()
|
||||
|
||||
true_cond = AndIf(conditional, candidate_true_expr).simplify()
|
||||
false_cond = AndIf(conditional, candidate_false_expr).simplify()
|
||||
|
||||
if false_cond in paths:
|
||||
@ -3482,7 +3504,7 @@ class ByteCodeDecompiler(VerboseOutput):
|
||||
def get_lhs(statement: IfStatement) -> Optional[Expression]:
|
||||
if not isinstance(statement.cond, TwoParameterIf):
|
||||
return None
|
||||
if statement.cond.comp not in {TwoParameterIf.EQUALS, TwoParameterIf.NOT_EQUALS}:
|
||||
if statement.cond.comp not in {TwoParameterIf.EQUALS, TwoParameterIf.NOT_EQUALS, TwoParameterIf.STRICT_EQUALS, TwoParameterIf.STRICT_NOT_EQUALS}:
|
||||
return None
|
||||
if not isinstance(statement.cond.conditional1, (Variable, Register, Member)):
|
||||
return None
|
||||
@ -3573,7 +3595,7 @@ class ByteCodeDecompiler(VerboseOutput):
|
||||
cond = cast(TwoParameterIf, statement.cond)
|
||||
|
||||
# If its already switched, leave it alone.
|
||||
if cond.comp == TwoParameterIf.EQUALS:
|
||||
if cond.comp in {TwoParameterIf.EQUALS, TwoParameterIf.STRICT_EQUALS}:
|
||||
new_batch.append(statement)
|
||||
return statement
|
||||
|
||||
@ -3681,6 +3703,85 @@ class ByteCodeDecompiler(VerboseOutput):
|
||||
statements = self.__walk(statements, replace_if_with_switch)
|
||||
return statements, changed
|
||||
|
||||
def __convert_if_gotos(self, statements: Sequence[Statement]) -> Tuple[List[Statement], bool]:
|
||||
# Find if statements in the middle of a chunk of code whose last true statement is
|
||||
# a return/goto/throw. Take all the following statements and put them in the if
|
||||
# statement's false clause. We do this because it allows us to recognize other
|
||||
# optimizations we could do on the code, including switch folding and redundant
|
||||
# statement eliminiation. It also often helps get rid of gotos that were only used
|
||||
# to skip the false path of an if statement.
|
||||
new_statements: List[Statement] = []
|
||||
changed: bool = False
|
||||
|
||||
i = 0
|
||||
while i < len(statements):
|
||||
cur_statement = statements[i]
|
||||
|
||||
if isinstance(cur_statement, IfStatement):
|
||||
if (
|
||||
cur_statement.true_statements and
|
||||
not cur_statement.false_statements and
|
||||
isinstance(cur_statement.true_statements[-1], (NullReturnStatement, ReturnStatement, ThrowStatement, GotoStatement))
|
||||
):
|
||||
# This is a candidate! Take all following statements up until the possible label we jump to and
|
||||
# make them into the false chunk.
|
||||
last_true_statement = cur_statement.true_statements[-1]
|
||||
stop_at_label: Optional[int] = None
|
||||
if isinstance(last_true_statement, GotoStatement):
|
||||
stop_at_label = last_true_statement.location
|
||||
|
||||
# We skip past this statement because its the one we're updating.
|
||||
i += 1
|
||||
|
||||
false_statements: List[Statement] = []
|
||||
while i < len(statements):
|
||||
false_statement = statements[i]
|
||||
if stop_at_label is not None and isinstance(false_statement, DefineLabelStatement):
|
||||
if stop_at_label == false_statement.location:
|
||||
# Exit early, the rest of the code including this
|
||||
# label is not part of the else case.
|
||||
break
|
||||
|
||||
false_statements.append(false_statement)
|
||||
i += 1
|
||||
|
||||
# Add all of these to the false case.
|
||||
if false_statements:
|
||||
cur_statement.false_statements = false_statements
|
||||
changed = True
|
||||
else:
|
||||
# Skip past this statement, we have nothing to do aside from walk its children.
|
||||
i += 1
|
||||
|
||||
# Regardless of whether we modified the if statement, recurse down its true and false path.
|
||||
cur_statement.true_statements, new_changed = self.__convert_if_gotos(cur_statement.true_statements)
|
||||
changed = changed or new_changed
|
||||
|
||||
cur_statement.false_statements, new_changed = self.__convert_if_gotos(cur_statement.false_statements)
|
||||
changed = changed or new_changed
|
||||
|
||||
new_statements.append(cur_statement)
|
||||
|
||||
elif isinstance(cur_statement, SwitchStatement):
|
||||
for case in cur_statement.cases:
|
||||
case.statements, new_changed = self.__convert_if_gotos(case.statements)
|
||||
changed = changed or new_changed
|
||||
new_statements.append(cur_statement)
|
||||
i += 1
|
||||
|
||||
elif isinstance(cur_statement, DoWhileStatement):
|
||||
cur_statement.body, new_changed = self.__convert_if_gotos(cur_statement.body)
|
||||
changed = changed or new_changed
|
||||
|
||||
new_statements.append(cur_statement)
|
||||
i += 1
|
||||
|
||||
else:
|
||||
new_statements.append(cur_statement)
|
||||
i += 1
|
||||
|
||||
return new_statements, changed
|
||||
|
||||
def _optimize_code(self, statements: Sequence[Statement]) -> List[Statement]:
|
||||
statements = list(statements)
|
||||
|
||||
@ -3693,6 +3794,7 @@ class ByteCodeDecompiler(VerboseOutput):
|
||||
self.__remove_goto_return,
|
||||
self.__eliminate_useless_returns,
|
||||
self.__convert_loops,
|
||||
self.__convert_if_gotos,
|
||||
self.__swap_empty_ifs,
|
||||
self.__drop_unneeded_else,
|
||||
self.__swap_ugly_ifexprs,
|
||||
|
||||
@ -660,7 +660,7 @@ class TestAFPDecompile(ExtendedTestCase):
|
||||
# "returning" early from a function.
|
||||
])
|
||||
statements = self.__call_decompile(bytecode)
|
||||
self.assertEqual(self.__equiv(statements), [f"if (not True) {OPEN_BRACKET}{os.linesep} return{os.linesep}{CLOSE_BRACKET}", "builtin_StartPlaying()"])
|
||||
self.assertEqual(self.__equiv(statements), [f"if (True) {OPEN_BRACKET}{os.linesep} builtin_StartPlaying(){os.linesep}{CLOSE_BRACKET}"])
|
||||
|
||||
def test_if_handling_diamond(self) -> None:
|
||||
# If true-false diamond case.
|
||||
|
||||
Loading…
Reference in New Issue
Block a user