mirror of
https://github.com/irmen/prog8.git
synced 2024-09-11 15:55:55 +00:00
207 lines
12 KiB
Python
207 lines
12 KiB
Python
"""
|
|
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
|
|
"""
|
|
|
|
from typing import List, no_type_check
|
|
from .plyparse import Module, Subroutine, Block, Directive, Assignment, AugAssignment, Goto, Expression, IncrDecr,\
|
|
datatype_of, coerce_constant_value, AssignmentTargets, LiteralValue, Scope
|
|
from .plylex import print_warning, print_bold
|
|
|
|
|
|
class Optimizer:
|
|
def __init__(self, mod: Module) -> None:
|
|
self.num_warnings = 0
|
|
self.module = mod
|
|
|
|
def optimize(self) -> None:
|
|
self.num_warnings = 0
|
|
self.optimize_assignments()
|
|
self.combine_assignments_into_multi()
|
|
self.optimize_multiassigns()
|
|
self.remove_unused_subroutines()
|
|
self.optimize_goto_compare_with_zero()
|
|
# @todo join multiple incr/decr of same var into one (if value stays < 256)
|
|
# @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)
|
|
self.remove_empty_blocks()
|
|
|
|
def optimize_assignments(self) -> None:
|
|
# remove assignment statements that do nothing (A=A)
|
|
# and augmented assignments that have no effect (A+=0)
|
|
# convert augmented assignments to simple incr/decr if possible (A+=10 => A++ by 10)
|
|
# @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 any(lv != assignment.right for lv in assignment.left.nodes):
|
|
assignment.left.nodes = [lv for lv in assignment.left.nodes if lv != assignment.right]
|
|
if not assignment.left:
|
|
assignment.my_scope().remove_node(assignment)
|
|
self.num_warnings += 1
|
|
print_warning("{}: removed statement that has no effect".format(assignment.sourceref))
|
|
if 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)
|
|
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)
|
|
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)
|
|
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(0) # XXX literalvalue?
|
|
assignment.my_scope().replace_node(assignment, new_stmt)
|
|
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
|
|
assignment.my_scope().replace_node(assignment, new_stmt)
|
|
if assignment.operator in ("/=", "//=", "*=") and assignment.right.value == 1:
|
|
self.num_warnings += 1
|
|
print_warning("{}: removed statement that has no effect".format(assignment.sourceref))
|
|
assignment.my_scope().remove_node(assignment)
|
|
|
|
@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
|
|
|
|
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)
|
|
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)
|
|
|
|
@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):
|
|
print("NOT IMPLEMENTED YET: optimize goto conditionals", goto.condition) # @todo
|
|
# 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 optimize(mod: Module) -> None:
|
|
opt = Optimizer(mod)
|
|
opt.optimize()
|
|
if opt.num_warnings:
|
|
print_bold("There are {:d} optimization warnings.".format(opt.num_warnings))
|