Commit a9072286 authored by Stefan Behnel's avatar Stefan Behnel

avoid unnecessary None checks based on control flow analysis (ticket #743)

parent 8ddf15a3
......@@ -1481,6 +1481,16 @@ class NameNode(AtomicExprNode):
# If it's not a C variable, it'll be in a temp.
return 1
def may_be_none(self):
if self.cf_state:
# evaluate control flow state to see if there were any
# potential None values assigned to the node so far
for assignment in self.cf_state:
if assignment.rhs.may_be_none():
return True
return False
return super(NameNode, self).may_be_none()
def nonlocally_immutable(self):
if ExprNode.nonlocally_immutable(self):
return True
......
......@@ -14,11 +14,16 @@ from Visitor import TreeVisitor, CythonTransform
from Errors import error, warning, CompileError, InternalError
class TypedExprNode(ExprNodes.ExprNode):
# Used for declaring assignments of a specified type whithout a known entry.
def __init__(self, type):
# Used for declaring assignments of a specified type without a known entry.
def __init__(self, type, may_be_none=None):
self.type = type
self._may_be_none = may_be_none
object_expr = TypedExprNode(py_object_type)
def may_be_none(self):
return self._may_be_none != False
object_expr = TypedExprNode(py_object_type, may_be_none=True)
object_expr_not_none = TypedExprNode(py_object_type, may_be_none=False)
class ControlBlock(object):
"""Control flow graph node. Sequence of assignments and name references.
......@@ -588,11 +593,13 @@ class CreateControlFlowGraph(CythonTransform):
if node.star_arg:
self.flow.mark_argument(node.star_arg,
TypedExprNode(Builtin.tuple_type),
TypedExprNode(Builtin.tuple_type,
may_be_none=False),
node.star_arg.entry)
if node.starstar_arg:
self.flow.mark_argument(node.starstar_arg,
TypedExprNode(Builtin.dict_type),
TypedExprNode(Builtin.dict_type,
may_be_none=False),
node.starstar_arg.entry)
self.visitchildren(node)
# Workaround for generators
......@@ -621,7 +628,7 @@ class CreateControlFlowGraph(CythonTransform):
if entry.is_anonymous:
entry = self.env.lookup(node.name)
if entry:
self.flow.mark_assignment(node, object_expr, entry)
self.flow.mark_assignment(node, object_expr_not_none, entry)
return self.visit_FuncDefNode(node)
def visit_GeneratorBodyDefNode(self, node):
......@@ -717,7 +724,8 @@ class CreateControlFlowGraph(CythonTransform):
def visit_CArgDeclNode(self, node):
entry = self.env.lookup(node.name)
if entry:
self.flow.mark_argument(node, TypedExprNode(entry.type), entry)
may_be_none = not node.not_none
self.flow.mark_argument(node, TypedExprNode(entry.type, may_be_none), entry)
return node
def visit_NameNode(self, node):
......@@ -1091,7 +1099,7 @@ class CreateControlFlowGraph(CythonTransform):
def visit_PyClassDefNode(self, node):
self.flow.mark_assignment(node.target,
object_expr, self.env.lookup(node.name))
object_expr_not_none, self.env.lookup(node.name))
# TODO: add negative attribute list to "visitchildren"?
self.visitchildren(node, attrs=['dict', 'metaclass',
'mkw', 'bases', 'classobj'])
......
......@@ -3530,3 +3530,12 @@ class FinalOptimizePhase(Visitor.CythonTransform):
if not node.arg.may_be_none():
node.notnone = True
return node
def visit_NoneCheckNode(self, node):
"""Remove None checks from expressions that definitely do not
carry a None value.
"""
self.visitchildren(node)
if not node.arg.may_be_none():
return node.arg
return node
cimport cython
@cython.test_fail_if_path_exists('//NoneCheckNode')
def none_checks(a):
"""
>>> none_checks(1)
22
>>> none_checks(None)
True
"""
c = None
d = {11:22}
if a is c:
return True
else:
return d.get(11)
@cython.test_assert_path_exists('//NoneCheckNode')
def dict_arg(dict a):
"""
>>> dict_arg({})
>>> dict_arg({1:2})
2
"""
return a.get(1)
@cython.test_fail_if_path_exists('//NoneCheckNode')
def dict_arg_not_none(dict a not None):
"""
>>> dict_arg_not_none({})
>>> dict_arg_not_none({1:2})
2
"""
return a.get(1)
@cython.test_assert_path_exists('//NoneCheckNode')
def reassignment(dict d):
"""
>>> reassignment({})
(None, 2)
>>> reassignment({1:3})
(3, 2)
"""
a = d.get(1)
d = {1:2}
b = d.get(1)
return a, b
@cython.test_fail_if_path_exists('//NoneCheckNode')
def conditional(a):
"""
>>> conditional(True)
2
>>> conditional(False)
3
"""
if a:
d = {1:2}
else:
d = {1:3}
return d.get(1)
@cython.test_assert_path_exists('//NoneCheckNode')
def conditional_arg(a, dict d):
"""
>>> conditional_arg(True, {1:2})
>>> conditional_arg(False, {1:2})
2
"""
if a:
d = {}
return d.get(1)
@cython.test_fail_if_path_exists('//NoneCheckNode')
def conditional_not_none(a, dict d not None):
"""
>>> conditional_not_none(True, {1:2})
>>> conditional_not_none(False, {1:2})
2
"""
if a:
d = {}
return d.get(1)
......@@ -57,7 +57,6 @@ def test_list_sort_reversed():
l1.sort(reversed=True)
return l1
@cython.test_assert_path_exists("//SimpleCallNode//NoneCheckNode")
def test_list_reverse():
"""
>>> test_list_reverse()
......@@ -68,7 +67,6 @@ def test_list_reverse():
l1.reverse()
return l1
@cython.test_assert_path_exists("//SimpleCallNode//NoneCheckNode")
def test_list_append():
"""
>>> test_list_append()
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment