Cool_Tools/bemaniutils
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mirror of synced 2025-02-17 19:19:19 +01:00
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Fix a few edge cases in a few of the decompilation optimizers.

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This commit is contained in:
Jennifer Taylor 2021-07-15 00:14:48 +00:00
parent 7ca9e6920f
commit 392a5e5133
1 changed files with 58 additions and 7 deletions
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65
bemani/format/afp/decompile.py
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@ -2721,9 +2721,35 @@ class ByteCodeDecompiler(VerboseOutput):
elif isinstance(cur_statement, SwitchStatement):
# Switch cases do not "flow" into the next line, they flow into the next switch
# case.
for case in cur_statement.cases:
gotos.extend(find_goto_next_line(case.statements, NopStatement()))
# case. Only if they have a 'break' statement do they flow to the parent. So
# we check for this case, removing breaks when we find them (to simulate falling
# out of the execution to the parent) and setting the next statement to the next
# switch case first instruction when we don't. This isn't perfect, but eliminates
# a lot of gotos in practice.
cases = cur_statement.cases
def get_next_instruction(case: SwitchCase) -> Statement:
found = False
for newcase in cases:
if found:
# If we identified the case, grab the next statement
# from the next available case that has statements.
if case.statements:
return case.statements[0]
if newcase is case:
# We found our case, so the next case with statements
# is the one we care about.
found = True
# We failed to find our case, or we failed to find a case
# after ours with statements.
return NopStatement()
for case in cases:
if case.statements and isinstance(case.statements[-1], BreakStatement):
gotos.extend(find_goto_next_line(case.statements[:-1], next_statement))
else:
gotos.extend(find_goto_next_line(case.statements, get_next_instruction(case)))
return gotos
@ -3564,6 +3590,25 @@ class ByteCodeDecompiler(VerboseOutput):
return statement
def has_break(statements: Sequence[Statement]) -> bool:
# We intentionally ignore switch/while/for statements here, because
# if there is a break inside one of those, it applies to that statement.
# We only want to know if there are any break statements in our children.
for statement in statements:
if isinstance(statement, BreakStatement):
# This is a break statement.
return True
elif isinstance(statement, IfStatement):
# Need to check the true and false cases.
if has_break(statement.true_statements):
return True
if has_break(statement.false_statements):
return True
# We found no break statements, we're solid.
return False
def replace_if_with_switch(statement: Statement) -> Optional[Statement]:
nonlocal changed
nonlocal batches
@ -3622,13 +3667,19 @@ class ByteCodeDecompiler(VerboseOutput):
if new_batch[i] is not cur_statement:
raise Exception("Logic error!")
if not isinstance(cur_statement, IfStatement):
# This isn't even an if statement. We should never hit
# this but the type checker wants to be happy.
return statement
if has_break(cur_statement.true_statements) or has_break(cur_statement.false_statements):
# This code already uses a 'break' statement. If we stuck it
# in a switch, it would change the sematics of this statement
# so we have no choice but to ignore this.
return statement
if i < (len(new_batch) - 1):
# We dont check for the final case, since this will include
# the 'default' case in the else body.
if not isinstance(cur_statement, IfStatement):
# This isn't even an if statement. We should never hit
# this but the type checker wants to be happy.
return statement
if len(cur_statement.false_statements) != 1:
# This can't be a switch, it needs to be an embedded if.
return statement