49 lines
1.6 KiB
Python
49 lines
1.6 KiB
Python
"""The optimizer tries to constant fold expressions and modify the AST
|
|
in place so that it should be faster to evaluate.
|
|
|
|
Because the AST does not contain all the scoping information and the
|
|
compiler has to find that out, we cannot do all the optimizations we
|
|
want. For example, loop unrolling doesn't work because unrolled loops
|
|
would have a different scope. The solution would be a second syntax tree
|
|
that stored the scoping rules.
|
|
"""
|
|
|
|
import typing as t
|
|
|
|
from . import nodes
|
|
from .visitor import NodeTransformer
|
|
|
|
if t.TYPE_CHECKING:
|
|
from .environment import Environment
|
|
|
|
|
|
def optimize(node: nodes.Node, environment: "Environment") -> nodes.Node:
|
|
"""The context hint can be used to perform an static optimization
|
|
based on the context given."""
|
|
optimizer = Optimizer(environment)
|
|
return t.cast(nodes.Node, optimizer.visit(node))
|
|
|
|
|
|
class Optimizer(NodeTransformer):
|
|
def __init__(self, environment: "t.Optional[Environment]") -> None:
|
|
self.environment = environment
|
|
|
|
def generic_visit(
|
|
self, node: nodes.Node, *args: t.Any, **kwargs: t.Any
|
|
) -> nodes.Node:
|
|
node = super().generic_visit(node, *args, **kwargs)
|
|
|
|
# Do constant folding. Some other nodes besides Expr have
|
|
# as_const, but folding them causes errors later on.
|
|
if isinstance(node, nodes.Expr):
|
|
try:
|
|
return nodes.Const.from_untrusted(
|
|
node.as_const(args[0] if args else None),
|
|
lineno=node.lineno,
|
|
environment=self.environment,
|
|
)
|
|
except nodes.Impossible:
|
|
pass
|
|
|
|
return node
|