""" Programming Language for 6502/6510 microprocessors, codename 'Sick' This is the optimizer that applies various optimizations to the parse tree, eliminates statements that have no effect, optimizes calculations etc. Written by Irmen de Jong (irmen@razorvine.net) - license: GNU GPL 3.0 """ import sys from typing import List, no_type_check, Union, Any from .plyparse import * from .plylex import print_warning, print_bold, SourceRef from .datatypes import DataType, VarType class Optimizer: def __init__(self, mod: Module) -> None: self.num_warnings = 0 self.module = mod self.optimizations_performed = False def optimize(self) -> None: self.num_warnings = 0 self.optimizations_performed = True # keep optimizing as long as there were changes made while self.optimizations_performed: self.optimizations_performed = False self._optimize() # remaining optimizations that have to be done just once: self.remove_unused_subroutines() self.remove_empty_blocks() def _optimize(self) -> None: self.constant_folding() # @todo expression optimization: reduce expression nesting # @todo expression optimization: simplify logical expression when a term makes it always true or false self.create_aug_assignments() self.optimize_assignments() self.remove_superfluous_assignments() self.combine_assignments_into_multi() self.optimize_multiassigns() # @todo optimize some simple multiplications into shifts (A*=8 -> A<<3) # @todo optimize addition with self into shift 1 (A+=A -> A<<=1) self.optimize_goto_compare_with_zero() self.join_incrdecrs() # @todo analyse for unreachable code and remove that (f.i. code after goto or return that has no label so can never be jumped to) def handle_internal_error(self, exc: Exception, msg: str="") -> None: out = sys.stdout if out.isatty(): print("\x1b[1m", file=out) print("\nERROR: internal parser/optimizer error: ", exc, file=out) if msg: print(" Message:", msg, end="\n\n") if out.isatty(): print("\x1b[0m", file=out, end="", flush=True) raise exc def constant_folding(self) -> None: for expression in self.module.all_nodes(Expression): if isinstance(expression, LiteralValue): continue try: evaluated = process_expression(expression) # type: ignore if evaluated is not expression: # replace the node with the newly evaluated result parent = expression.parent parent.replace_node(expression, evaluated) self.optimizations_performed = True except ParseError: raise except Exception as x: self.handle_internal_error(x, "process_expressions of node {}".format(expression)) def join_incrdecrs(self) -> None: for scope in self.module.all_nodes(Scope): incrdecrs = [] # type: List[IncrDecr] target = None for node in list(scope.nodes): if isinstance(node, IncrDecr): if target is None: target = node.target incrdecrs.append(node) continue if self._same_target(target, node.target): incrdecrs.append(node) continue if len(incrdecrs) > 1: # optimize... replaced = False total = 0 for i in incrdecrs: if i.operator == "++": total += i.howmuch else: total -= i.howmuch if total == 0: replaced = True for x in incrdecrs: scope.remove_node(x) else: is_float = False if isinstance(target, SymbolName): symdef = target.my_scope().lookup(target.name) if isinstance(symdef, VarDef) and symdef.datatype == DataType.FLOAT: is_float = True elif isinstance(target, Dereference): is_float = target.datatype == DataType.FLOAT if is_float: replaced = True for x in incrdecrs[1:]: scope.remove_node(x) incrdecr = self._make_incrdecr(incrdecrs[0], target, abs(total), "++" if total >= 0 else "--") scope.replace_node(incrdecrs[0], incrdecr) elif 0 < total <= 255: replaced = True for x in incrdecrs[1:]: scope.remove_node(x) incrdecr = self._make_incrdecr(incrdecrs[0], target, total, "++") scope.replace_node(incrdecrs[0], incrdecr) elif -255 <= total < 0: replaced = True total = -total for x in incrdecrs[1:]: scope.remove_node(x) incrdecr = self._make_incrdecr(incrdecrs[0], target, total, "--") scope.replace_node(incrdecrs[0], incrdecr) if replaced: self.optimizations_performed = True self.num_warnings += 1 print_warning("{}: merged a sequence of incr/decrs or augmented assignments".format(incrdecrs[0].sourceref)) incrdecrs.clear() target = None if isinstance(node, IncrDecr): incrdecrs.append(node) target = node.target def _same_target(self, node1: Union[TargetRegisters, Register, SymbolName, Dereference], node2: Union[TargetRegisters, Register, SymbolName, Dereference]) -> bool: if isinstance(node1, Register) and isinstance(node2, Register) and node1.name == node2.name: return True if isinstance(node1, SymbolName) and isinstance(node2, SymbolName) and node1.name == node2.name: return True if isinstance(node1, Dereference) and isinstance(node2, Dereference) and node1.operand == node2.operand: return True return False @no_type_check def create_aug_assignments(self) -> None: # create augmented assignments from regular assignment that only refers to the lvalue # A=A+10, A=10+A -> A+=10, A=A*4, A=4*A -> A*=4, etc for assignment in self.module.all_nodes(Assignment): if len(assignment.left.nodes) > 1: continue if not isinstance(assignment.right, ExpressionWithOperator) or assignment.right.unary: continue expr = assignment.right if expr.operator in ('-', '/', '//', '**', '<<', '>>', '&'): # non-associative operators if isinstance(expr.right, (LiteralValue, SymbolName)) and self._same_target(assignment.left.nodes[0], expr.left): num_val = expr.right.const_value() operator = expr.operator + '=' aug_assign = self._make_aug_assign(assignment, assignment.left.nodes[0], num_val, operator) assignment.my_scope().replace_node(assignment, aug_assign) self.optimizations_performed = True continue if expr.operator not in ('+', '*', '|', '^'): # associative operators continue if isinstance(expr.right, (LiteralValue, SymbolName)) and self._same_target(assignment.left.nodes[0], expr.left): num_val = expr.right.const_value() operator = expr.operator + '=' aug_assign = self._make_aug_assign(assignment, assignment.left.nodes[0], num_val, operator) assignment.my_scope().replace_node(assignment, aug_assign) self.optimizations_performed = True elif isinstance(expr.left, (LiteralValue, SymbolName)) and self._same_target(assignment.left.nodes[0], expr.right): num_val = expr.left.const_value() operator = expr.operator + '=' aug_assign = self._make_aug_assign(assignment, assignment.left.nodes[0], num_val, operator) assignment.my_scope().replace_node(assignment, aug_assign) self.optimizations_performed = True def remove_superfluous_assignments(self) -> None: # remove consecutive assignment statements to the same target, only keep the last value (only if its a constant!) # this is NOT done for memory mapped variables because these often represent a volatile register of some sort! for scope in self.module.all_nodes(Scope): prev_node = None # type: AstNode for node in list(scope.nodes): if isinstance(node, Assignment) and isinstance(prev_node, Assignment): if isinstance(node.right, (LiteralValue, Register)) and node.left.same_targets(prev_node.left): if not node.left.has_memvalue(): scope.remove_node(prev_node) self.optimizations_performed = True self.num_warnings += 1 print_warning("{}: removed superfluous assignment".format(prev_node.sourceref)) prev_node = node @no_type_check def optimize_assignments(self) -> None: # remove assignment statements that do nothing (A=A) # remove augmented assignments that have no effect (x+=0, x-=0, x/=1, x//=1, x*=1) # convert augmented assignments to simple incr/decr if possible (A+=10 => A++ by 10) # simplify some calculations (x*=0, x**=0) to simple constant value assignment # @todo remove or simplify logical aug assigns like A |= 0, A |= true, A |= false (or perhaps turn them into byte values first?) for assignment in self.module.all_nodes(): if isinstance(assignment, Assignment): if all(lv == assignment.right for lv in assignment.left.nodes): assignment.my_scope().remove_node(assignment) self.optimizations_performed = True self.num_warnings += 1 print_warning("{}: removed statement that has no effect".format(assignment.sourceref)) elif isinstance(assignment, AugAssignment): if isinstance(assignment.right, LiteralValue) and isinstance(assignment.right.value, (int, float)): if assignment.right.value == 0: if assignment.operator in ("+=", "-=", "|=", "<<=", ">>=", "^="): self.num_warnings += 1 print_warning("{}: removed statement that has no effect".format(assignment.sourceref)) assignment.my_scope().remove_node(assignment) self.optimizations_performed = True elif assignment.operator == "*=": self.num_warnings += 1 print_warning("{}: statement replaced by = 0".format(assignment.sourceref)) new_assignment = self._make_new_assignment(assignment, 0) assignment.my_scope().replace_node(assignment, new_assignment) self.optimizations_performed = True elif assignment.operator == "**=": self.num_warnings += 1 print_warning("{}: statement replaced by = 1".format(assignment.sourceref)) new_assignment = self._make_new_assignment(assignment, 1) assignment.my_scope().replace_node(assignment, new_assignment) self.optimizations_performed = True if assignment.right.value >= 8 and assignment.operator in ("<<=", ">>="): print("{}: shifting result is always zero".format(assignment.sourceref)) new_stmt = Assignment(sourceref=assignment.sourceref) new_stmt.nodes.append(AssignmentTargets(nodes=[assignment.left], sourceref=assignment.sourceref)) new_stmt.nodes.append(LiteralValue(value=0, sourceref=assignment.sourceref)) assignment.my_scope().replace_node(assignment, new_stmt) self.optimizations_performed = True if assignment.operator in ("+=", "-=") and 0 < assignment.right.value < 256: howmuch = assignment.right if howmuch.value not in (0, 1): _, howmuch = coerce_constant_value(datatype_of(assignment.left, assignment.my_scope()), howmuch, assignment.sourceref) new_stmt = IncrDecr(operator="++" if assignment.operator == "+=" else "--", howmuch=howmuch.value, sourceref=assignment.sourceref) new_stmt.target = assignment.left new_stmt.target.parent = new_stmt assignment.my_scope().replace_node(assignment, new_stmt) self.optimizations_performed = True if assignment.right.value == 1 and assignment.operator in ("/=", "//=", "*="): self.num_warnings += 1 print_warning("{}: removed statement that has no effect".format(assignment.sourceref)) assignment.my_scope().remove_node(assignment) self.optimizations_performed = True @no_type_check def _make_new_assignment(self, old_aug_assignment: AugAssignment, constantvalue: int) -> Assignment: new_assignment = Assignment(sourceref=old_aug_assignment.sourceref) new_assignment.parent = old_aug_assignment.parent left = AssignmentTargets(nodes=[old_aug_assignment.left], sourceref=old_aug_assignment.sourceref) left.parent = new_assignment new_assignment.nodes.append(left) value = LiteralValue(value=constantvalue, sourceref=old_aug_assignment.sourceref) value.parent = new_assignment new_assignment.nodes.append(value) return new_assignment @no_type_check def _make_aug_assign(self, old_assign: Assignment, target: Union[TargetRegisters, Register, SymbolName, Dereference], value: Union[int, float], operator: str) -> AugAssignment: assert isinstance(target, (TargetRegisters, Register, SymbolName, Dereference)) a = AugAssignment(operator=operator, sourceref=old_assign.sourceref) a.nodes.append(target) target.parent = a lv = LiteralValue(value=value, sourceref=old_assign.sourceref) a.nodes.append(lv) lv.parent = a a.parent = old_assign.parent return a @no_type_check def _make_incrdecr(self, old_stmt: AstNode, target: Union[TargetRegisters, Register, SymbolName, Dereference], howmuch: Union[int, float], operator: str) -> IncrDecr: assert isinstance(target, (TargetRegisters, Register, SymbolName, Dereference)) a = IncrDecr(operator=operator, howmuch=howmuch, sourceref=old_stmt.sourceref) a.nodes.append(target) target.parent = a a.parent = old_stmt.parent return a def combine_assignments_into_multi(self) -> None: # fold multiple consecutive assignments with the same rvalue into one multi-assignment for scope in self.module.all_nodes(Scope): rvalue = None assignments = [] # type: List[Assignment] for stmt in list(scope.nodes): if isinstance(stmt, Assignment): if assignments: if stmt.right == rvalue: assignments.append(stmt) continue elif len(assignments) > 1: # replace the first assignment by a multi-assign with all the others for assignment in assignments[1:]: print("{}: joined with previous assignment".format(assignment.sourceref)) assignments[0].left.nodes.extend(assignment.left.nodes) scope.remove_node(assignment) self.optimizations_performed = True rvalue = None assignments.clear() else: rvalue = stmt.right assignments.append(stmt) else: rvalue = None assignments.clear() @no_type_check def optimize_multiassigns(self) -> None: # optimize multi-assign statements (remove duplicate targets, optimize order) for assignment in self.module.all_nodes(Assignment): if len(assignment.left.nodes) > 1: # remove duplicates lvalues = set(assignment.left.nodes) if len(lvalues) != len(assignment.left.nodes): print("{}: removed duplicate assignment targets".format(assignment.sourceref)) # @todo change order: first registers, then zp addresses, then non-zp addresses, then the rest (if any) assignment.left.nodes = list(lvalues) self.optimizations_performed = True @no_type_check def remove_unused_subroutines(self) -> None: # some symbols are used by the emitted assembly code from the code generator, # and should never be removed or the assembler will fail never_remove = {"c64.FREADUY", "c64.FTOMEMXY", "c64.FADD", "c64.FSUB", "c64flt.GIVUAYF", "c64flt.copy_mflt", "c64flt.float_add_one", "c64flt.float_sub_one", "c64flt.float_add_SW1_to_XY", "c64flt.float_sub_SW1_from_XY"} num_discarded = 0 for sub in self.module.all_nodes(Subroutine): usages = self.module.subroutine_usage[(sub.parent.name, sub.name)] if not usages and sub.parent.name + '.' + sub.name not in never_remove: sub.parent.remove_node(sub) num_discarded += 1 if num_discarded: print("discarded {:d} unused subroutines".format(num_discarded)) @no_type_check def optimize_goto_compare_with_zero(self) -> None: # a conditional goto that compares a value with zero will be simplified # the comparison operator and rvalue (0) will be removed and the if-status changed accordingly for goto in self.module.all_nodes(Goto): if isinstance(goto.condition, Expression): pass # @todo optimize goto conditionals # if cond and isinstance(cond.rvalue, (int, float)) and cond.rvalue.value == 0: # simplified = False # if cond.ifstatus in ("true", "ne"): # if cond.comparison_op == "==": # # if_true something == 0 -> if_not something # cond.ifstatus = "not" # cond.comparison_op, cond.rvalue = "", None # simplified = True # elif cond.comparison_op == "!=": # # if_true something != 0 -> if_true something # cond.comparison_op, cond.rvalue = "", None # simplified = True # elif cond.ifstatus in ("not", "eq"): # if cond.comparison_op == "==": # # if_not something == 0 -> if_true something # cond.ifstatus = "true" # cond.comparison_op, cond.rvalue = "", None # simplified = True # elif cond.comparison_op == "!=": # # if_not something != 0 -> if_not something # cond.comparison_op, cond.rvalue = "", None # simplified = True # if simplified: # print("{}: simplified comparison with zero".format(stmt.sourceref)) def remove_empty_blocks(self) -> None: # remove blocks without name and without address, or that are empty for node in self.module.all_nodes(): if isinstance(node, (Subroutine, Block)): if not node.scope: continue if all(isinstance(n, Directive) for n in node.scope.nodes): empty = True for n in node.scope.nodes: empty = empty and n.name not in {"asmbinary", "asminclude"} if empty: self.num_warnings += 1 print_warning("ignoring empty block or subroutine", node.sourceref) assert isinstance(node.parent, (Block, Module)) node.my_scope().nodes.remove(node) if isinstance(node, Block): if not node.name and node.address is None: self.num_warnings += 1 print_warning("ignoring block without name and address", node.sourceref) assert isinstance(node.parent, Module) node.my_scope().nodes.remove(node) def process_expression(expr: Expression) -> Expression: # process/simplify all expressions (constant folding etc) result = None # type: Expression if expr.is_compile_constant() or isinstance(expr, ExpressionWithOperator) and expr.must_be_constant: result = _process_constant_expression(expr, expr.sourceref) else: result = _process_dynamic_expression(expr, expr.sourceref) result.parent = expr.parent return result def _process_constant_expression(expr: Expression, sourceref: SourceRef) -> LiteralValue: # the expression must result in a single (constant) value (int, float, whatever) wrapped as LiteralValue. if isinstance(expr, LiteralValue): return expr if expr.is_compile_constant(): return LiteralValue(value=expr.const_value(), sourceref=sourceref) # type: ignore elif isinstance(expr, SymbolName): value = check_symbol_definition(expr.name, expr.my_scope(), expr.sourceref) if isinstance(value, VarDef): if value.vartype == VarType.MEMORY: raise ExpressionEvaluationError("can't take a memory value, must be a constant", expr.sourceref) value = value.value if isinstance(value, ExpressionWithOperator): raise ExpressionEvaluationError("circular reference?", expr.sourceref) elif isinstance(value, LiteralValue): return value elif isinstance(value, (int, float, str, bool)): raise TypeError("symbol value node should not be a python primitive value", expr) else: raise ExpressionEvaluationError("constant symbol required, not {}".format(value.__class__.__name__), expr.sourceref) elif isinstance(expr, AddressOf): assert isinstance(expr.name, str) value = check_symbol_definition(expr.name, expr.my_scope(), expr.sourceref) if isinstance(value, VarDef): if value.vartype == VarType.MEMORY: if isinstance(value.value, LiteralValue): return value.value else: raise ExpressionEvaluationError("constant literal value required", value.sourceref) if value.vartype == VarType.CONST: raise ExpressionEvaluationError("can't take the address of a constant", expr.sourceref) raise ExpressionEvaluationError("address-of this {} isn't a compile-time constant" .format(value.__class__.__name__), expr.sourceref) else: raise ExpressionEvaluationError("constant address required, not {}" .format(value.__class__.__name__), expr.sourceref) elif isinstance(expr, SubCall): if isinstance(expr.target, SymbolName): # 'function(1,2,3)' funcname = expr.target.name if funcname in math_functions or funcname in builtin_functions: func_args = [] for a in (_process_constant_expression(callarg.value, sourceref) for callarg in list(expr.arguments.nodes)): if isinstance(a, LiteralValue): func_args.append(a.value) else: func_args.append(a) func = math_functions.get(funcname, builtin_functions.get(funcname)) try: return LiteralValue(value=func(*func_args), sourceref=expr.arguments.sourceref) # type: ignore except Exception as x: raise ExpressionEvaluationError(str(x), expr.sourceref) else: raise ExpressionEvaluationError("can only use math- or builtin function", expr.sourceref) elif isinstance(expr.target, Dereference): # '[...](1,2,3)' raise ExpressionEvaluationError("dereferenced value call is not a constant value", expr.sourceref) elif isinstance(expr.target, LiteralValue) and type(expr.target.value) is int: # '64738()' raise ExpressionEvaluationError("immediate address call is not a constant value", expr.sourceref) else: raise NotImplementedError("weird call target", expr.target) elif isinstance(expr, ExpressionWithOperator): if expr.unary: left_sourceref = expr.left.sourceref if isinstance(expr.left, AstNode) else sourceref expr.left = _process_constant_expression(expr.left, left_sourceref) expr.left.parent = expr if isinstance(expr.left, LiteralValue) and type(expr.left.value) in (int, float): try: if expr.operator == '-': return LiteralValue(value=-expr.left.value, sourceref=expr.left.sourceref) # type: ignore elif expr.operator == '~': return LiteralValue(value=~expr.left.value, sourceref=expr.left.sourceref) # type: ignore elif expr.operator in ("++", "--"): raise ValueError("incr/decr should not be an expression") raise ValueError("invalid unary operator", expr.operator) except TypeError as x: raise ParseError(str(x), expr.sourceref) from None raise ValueError("invalid operand type for unary operator", expr.left, expr.operator) else: left_sourceref = expr.left.sourceref if isinstance(expr.left, AstNode) else sourceref expr.left = _process_constant_expression(expr.left, left_sourceref) expr.left.parent = expr right_sourceref = expr.right.sourceref if isinstance(expr.right, AstNode) else sourceref expr.right = _process_constant_expression(expr.right, right_sourceref) expr.right.parent = expr if isinstance(expr.left, LiteralValue): if isinstance(expr.right, LiteralValue): return expr.evaluate_primitive_constants(expr.right.sourceref) else: raise ExpressionEvaluationError("constant literal value required on right, not {}" .format(expr.right.__class__.__name__), right_sourceref) else: raise ExpressionEvaluationError("constant literal value required on left, not {}" .format(expr.left.__class__.__name__), left_sourceref) else: raise ExpressionEvaluationError("constant value required, not {}".format(expr.__class__.__name__), expr.sourceref) def _process_dynamic_expression(expr: Expression, sourceref: SourceRef) -> Expression: # constant-fold a dynamic expression if isinstance(expr, LiteralValue): return expr if expr.is_compile_constant(): return LiteralValue(value=expr.const_value(), sourceref=sourceref) # type: ignore elif isinstance(expr, SymbolName): if expr.is_compile_constant(): try: return _process_constant_expression(expr, sourceref) except ExpressionEvaluationError: pass return expr elif isinstance(expr, AddressOf): if expr.is_compile_constant(): try: return _process_constant_expression(expr, sourceref) except ExpressionEvaluationError: pass return expr elif isinstance(expr, SubCall): try: return _process_constant_expression(expr, sourceref) except ExpressionEvaluationError: if isinstance(expr.target, SymbolName): check_symbol_definition(expr.target.name, expr.my_scope(), expr.target.sourceref) return expr elif isinstance(expr, (Register, Dereference)): return expr elif isinstance(expr, ExpressionWithOperator): if expr.unary: left_sourceref = expr.left.sourceref if isinstance(expr.left, AstNode) else sourceref expr.left = _process_dynamic_expression(expr.left, left_sourceref) expr.left.parent = expr if expr.is_compile_constant(): try: return _process_constant_expression(expr, sourceref) except ExpressionEvaluationError: pass return expr else: left_sourceref = expr.left.sourceref if isinstance(expr.left, AstNode) else sourceref expr.left = _process_dynamic_expression(expr.left, left_sourceref) expr.left.parent = expr right_sourceref = expr.right.sourceref if isinstance(expr.right, AstNode) else sourceref expr.right = _process_dynamic_expression(expr.right, right_sourceref) expr.right.parent = expr if expr.is_compile_constant(): try: return _process_constant_expression(expr, sourceref) except ExpressionEvaluationError: pass return expr else: raise ParseError("expression required, not {}".format(expr.__class__.__name__), expr.sourceref) def optimize(mod: Module) -> None: opt = Optimizer(mod) opt.optimize() if opt.num_warnings: print_bold("There are {:d} optimization warnings.".format(opt.num_warnings))