Commit 670cda8e authored by Robert Bradshaw's avatar Robert Bradshaw

Basic control flow state processing

parent cf77ad03
import bisect
# This module keeps track of arbitrary "states" at any point of the code.
# A state is considered known if every path to the given point agrees on
# its state, otherwise it is None (i.e. unknown).
# It might be useful to be able to "freeze" the set of states by pushing
# all state changes to the tips of the trees for fast reading. Perhaps this
# could be done on get_state, clearing the cache on set_state (assuming
# incoming is immutable).
class ControlFlow:
def __init__(self, start_pos, incoming, parent):
self.start_pos = start_pos
self.incoming = incoming
if parent is None and incoming is not None:
parent = incoming.parent
self.parent = parent
self.tip = {}
self.end_pos = ((),)
def start_branch(self, pos):
self.end_pos = pos
branch_point = BranchingControlFlow(pos, self)
if self.parent is not None:
self.parent.branches[-1] = branch_point
return branch_point.branches[0]
def next_branch(self, pos):
self.end_pos = pos
return self.parent.new_branch(pos)
def finish_branch(self, pos):
self.end_pos = pos
self.parent.end_pos = pos
return LinearControlFlow(pos, self.parent)
def get_state(self, pos, item):
return self.get_pos_state(pos, item)[1]
def get_pos_state(self, pos, item):
# do some caching
if pos > self.end_pos:
try:
return self.tip[item]
except KeyError:
self.tip[item] = pos_state = self._get_pos_state(pos, item)
return pos_state
else:
return self._get_pos_state(pos, item)
class LinearControlFlow(ControlFlow):
def __init__(self, start_pos=(), incoming=None, parent=None):
ControlFlow.__init__(self, start_pos, incoming, parent)
self.events = {}
def set_state(self, pos, item, state):
if self.tip.has_key(item):
del self.tip[item]
if pos < self.start_pos:
if self.incoming is not None:
self.incoming.set_state(pos, item, state)
else:
if self.events.has_key(item):
event_list = self.events[item]
else:
event_list = []
self.events[item] = event_list
bisect.insort(event_list, (pos, state))
def _get_pos_state(self, pos, item):
if pos > self.start_pos:
if self.events.has_key(item):
event_list = self.events[item]
for event in event_list[::-1]:
if event[0] < pos:
return event
if self.incoming is not None:
return self.incoming.get_pos_state(pos, item)
else:
return None, None
def to_string(self, indent, limit=None):
if len(self.events) == 0:
s = indent + "[no state changes]"
else:
all = []
for item, event_list in self.events.items():
for pos, state in event_list:
all.append((indent, pos, item, state))
all.sort()
all = ["%s%s: %s <- %s" % data for data in all]
s = "\n".join(all)
if self.incoming is not limit and self.incoming is not None:
s = "%s\n%s" % (self.incoming.to_string(indent, limit=limit), s)
return s
class BranchingControlFlow(ControlFlow):
def __init__(self, start_pos, incoming, parent=None):
ControlFlow.__init__(self, start_pos, incoming, parent)
self.branches = [LinearControlFlow(start_pos, incoming, parent=self)]
self.branch_starts = [start_pos]
def set_state(self, pos, item, state):
if self.tip.has_key(item):
del self.tip[item]
if pos < self.start_pos:
self.incoming.set_state(pos, item, state)
else:
for branch_pos, branch in zip(self.branch_starts[::-1], self.branches[::-1]):
if pos >= branch_pos:
branch.set_state(pos, item, state)
return
def _get_pos_state(self, pos, item):
if pos <= self.start_pos:
return self.incoming.get_pos_state(pos, item)
elif pos < self.end_pos:
for branch_pos, branch in zip(self.branch_starts[::-1], self.branches[::-1]):
if pos >= branch_pos:
return branch.get_pos_state(pos, item)
else:
last_pos, last_state = self.branches[0].get_pos_state(pos, item)
if last_state is None:
return None, None
for branch in self.branches[1:]:
other_pos, other_state = branch.get_pos_state(pos, item)
if other_state is None or other_state != last_state:
return None, None
elif last_pos is not other_pos:
last_pos = max(last_pos, other_pos)
return last_pos, last_state
def new_branch(self, pos):
self.branches.append(LinearControlFlow(pos, self.incoming, parent=self))
self.branch_starts.append(pos)
return self.branches[-1]
def to_string(self, indent, limit=None):
join = "\n%sor\n" % indent
s = join.join([branch.to_string(indent+" ", limit=self.incoming) for branch in self.branches])
if self.incoming is not limit and self.incoming is not None:
s = "%s\n%s" % (self.incoming.to_string(indent, limit=limit), s)
return s
\ No newline at end of file
......@@ -817,6 +817,7 @@ class NameNode(AtomicExprNode):
self.entry = env.lookup_here(self.name)
if not self.entry:
self.entry = env.declare_var(self.name, py_object_type, self.pos)
env.control_flow.set_state(self.pos, (self.name, 'initalized'), True)
if self.entry.is_declared_generic:
self.result_ctype = py_object_type
......@@ -945,6 +946,12 @@ class NameNode(AtomicExprNode):
namespace,
self.entry.name,
code.error_goto_if_null(self.result_code, self.pos)))
elif entry.is_local:
assigned = entry.scope.control_flow.get_state(self.pos, (entry.name, 'initalized'))
if assigned is False:
error(self.pos, "local variable '%s' referenced before assignment" % entry.name)
elif assigned is None:
code.putln('/* check %s */' % entry.cname)
def generate_assignment_code(self, rhs, code):
#print "NameNode.generate_assignment_code:", self.name ###
......
......@@ -14,6 +14,7 @@ from Symtab import ModuleScope, LocalScope, \
StructOrUnionScope, PyClassScope, CClassScope
from Cython.Utils import open_new_file, replace_suffix
import Options
import ControlFlow
from DebugFlags import debug_disposal_code
......@@ -119,9 +120,13 @@ class Node:
#
# There are 3 phases of parse tree processing, applied in order to
# There are 4 phases of parse tree processing, applied in order to
# all the statements in a given scope-block:
#
# (0) analyse_control_flow
# Create the control flow tree into which state can be asserted and
# queried.
#
# (1) analyse_declarations
# Make symbol table entries for all declarations at the current
# level, both explicit (def, cdef, etc.) and implicit (assignment
......@@ -141,6 +146,9 @@ class Node:
# functions.
#
def analyse_control_flow(self, env):
pass
def analyse_declarations(self, env):
pass
......@@ -157,6 +165,26 @@ class Node:
if isinstance(self, BlockNode):
self.body.annotate(code)
def end_pos(self):
try:
return self._end_pos
except AttributeError:
children = [acc.get() for acc in self.get_child_accessors()]
if len(children) == 0:
self._end_pos = self.pos
else:
# Sometimes lists, sometimes nodes
flat = []
for child in children:
if child is None:
pass
elif isinstance(child, list):
flat += child
else:
flat.append(child)
self._end_pos = max([child.end_pos() for child in flat])
return self._end_pos
class BlockNode:
# Mixin class for nodes representing a declaration block.
......@@ -215,6 +243,10 @@ class StatListNode(Node):
child_attrs = ["stats"]
def analyse_control_flow(self, env):
for stat in self.stats:
stat.analyse_control_flow(env)
def analyse_declarations(self, env):
#print "StatListNode.analyse_declarations" ###
for stat in self.stats:
......@@ -313,6 +345,7 @@ class CDeclaratorNode(Node):
class CNameDeclaratorNode(CDeclaratorNode):
# name string The Pyrex name being declared
# cname string or None C name, if specified
# rhs ExprNode or None the value assigned on declaration
child_attrs = []
......@@ -323,6 +356,7 @@ class CNameDeclaratorNode(CDeclaratorNode):
def analyse_expressions(self, env):
self.entry = env.lookup(self.name)
if self.rhs is not None:
env.control_flow.set_state(self.rhs.end_pos(), (self.entry.name, 'initalized'), True)
self.entry.used = 1
if self.type.is_pyobject:
self.entry.init_to_none = False
......@@ -770,6 +804,7 @@ class FuncDefNode(StatNode, BlockNode):
code.init_labels()
self.declare_arguments(lenv)
transforms.run('before_analyse_function', self, env=env, lenv=lenv, genv=genv)
self.body.analyse_control_flow(lenv)
self.body.analyse_declarations(lenv)
self.body.analyse_expressions(lenv)
transforms.run('after_analyse_function', self, env=env, lenv=lenv, genv=genv)
......@@ -865,7 +900,9 @@ class FuncDefNode(StatNode, BlockNode):
# ----- Return cleanup
code.put_label(code.return_label)
code.put_var_decrefs(lenv.var_entries, used_only = 1)
code.put_var_decrefs(lenv.arg_entries)
for entry in lenv.arg_entries:
# if len(entry.assignments) > 0:
code.put_var_decref(entry)
self.put_stararg_decrefs(code)
if acquire_gil:
code.putln("PyGILState_Release(_save);")
......@@ -894,6 +931,7 @@ class FuncDefNode(StatNode, BlockNode):
# This is necessary, because if the argument is
# assigned to, it will be decrefed.
for entry in env.arg_entries:
# if len(entry.assignments) > 0:
code.put_var_incref(entry)
def generate_optarg_wrapper_function(self, env, code):
......@@ -2714,6 +2752,15 @@ class IfStatNode(StatNode):
child_attrs = ["if_clauses", "else_clause"]
def analyse_control_flow(self, env):
env.start_branching(self.pos)
for if_clause in self.if_clauses:
if_clause.analyse_control_flow(env)
env.next_branch(if_clause.end_pos())
if self.else_clause:
self.else_clause.analyse_control_flow(env)
env.finish_branching(self.end_pos())
def analyse_declarations(self, env):
for if_clause in self.if_clauses:
if_clause.analyse_declarations(env)
......@@ -2752,6 +2799,9 @@ class IfClauseNode(Node):
child_attrs = ["condition", "body"]
def analyse_control_flow(self, env):
self.body.analyse_control_flow(env)
def analyse_declarations(self, env):
self.condition.analyse_declarations(env)
self.body.analyse_declarations(env)
......@@ -2780,7 +2830,18 @@ class IfClauseNode(Node):
self.body.annotate(code)
class WhileStatNode(StatNode):
class LoopNode:
def analyse_control_flow(self, env):
env.start_branching(self.pos)
self.body.analyse_control_flow(env)
env.next_branch(self.body.end_pos())
if self.else_clause:
self.else_clause.analyse_control_flow(env)
env.finish_branching(self.end_pos())
class WhileStatNode(LoopNode, StatNode):
# while statement
#
# condition ExprNode
......@@ -2835,7 +2896,7 @@ def ForStatNode(pos, **kw):
else:
return ForFromStatNode(pos, **kw)
class ForInStatNode(StatNode):
class ForInStatNode(LoopNode, StatNode):
# for statement
#
# target ExprNode
......@@ -2943,7 +3004,7 @@ class ForInStatNode(StatNode):
self.item.annotate(code)
class ForFromStatNode(StatNode):
class ForFromStatNode(LoopNode, StatNode):
# for name from expr rel name rel expr
#
# target NameNode
......@@ -2962,12 +3023,6 @@ class ForFromStatNode(StatNode):
# py_loopvar_node PyTempNode or None
child_attrs = ["target", "bound1", "bound2", "step", "body", "else_clause", "py_loopvar_node"]
def analyse_declarations(self, env):
self.target.analyse_target_declaration(env)
self.body.analyse_declarations(env)
if self.else_clause:
self.else_clause.analyse_declarations(env)
def analyse_expressions(self, env):
import ExprNodes
self.target.analyse_target_types(env)
......@@ -3084,7 +3139,20 @@ class TryExceptStatNode(StatNode):
# else_clause StatNode or None
# cleanup_list [Entry] temps to clean up on error
child_attrs = ["body", "except_clauses", "else_clause", "cleanup_list"]
child_attrs = ["body", "except_clauses", "else_clause"]
def analyse_control_flow(self, env):
env.start_branching(self.pos)
self.body.analyse_control_flow(env)
for except_clause in self.except_clauses:
env.next_branch(except_clause.pos)
except_clause.analyse_control_flow(env)
if self.else_clause:
env.next_branch(self.except_clauses[-1].end_pos())
# the else cause it executed only when the try clause finishes
env.control_flow.incoming = env.control_flow.parent.branches[0]
self.else_clause.analyse_control_flow(env)
env.finish_branching(self.end_pos())
def analyse_declarations(self, env):
self.body.analyse_declarations(env)
......@@ -3239,7 +3307,7 @@ class TryFinallyStatNode(StatNode):
# exception on entry to the finally block and restore
# it on exit.
child_attrs = ["body", "finally_clause", "cleanup_list"]
child_attrs = ["body", "finally_clause"]
preserve_exception = 1
......@@ -3248,6 +3316,13 @@ class TryFinallyStatNode(StatNode):
# continue in the try block, since we have no problem
# handling it.
def analyse_control_flow(self, env):
env.start_branching(self.pos)
self.body.analyse_control_flow(env)
env.next_branch(self.body.end_pos())
self.finally_clause.analyse_control_flow(env)
env.finish_branching(self.end_pos())
def analyse_declarations(self, env):
self.body.analyse_declarations(env)
self.finally_clause.analyse_declarations(env)
......
......@@ -1162,10 +1162,13 @@ def p_try_statement(s):
if s.sy == 'else':
s.next()
else_clause = p_suite(s)
return Nodes.TryExceptStatNode(pos,
body = Nodes.TryExceptStatNode(pos,
body = body, except_clauses = except_clauses,
else_clause = else_clause)
elif s.sy == 'finally':
if s.sy != 'finally':
return body
# try-except-finally is equivalent to nested try-except/try-finally
if s.sy == 'finally':
s.next()
finally_clause = p_suite(s)
return Nodes.TryFinallyStatNode(pos,
......
......@@ -3,6 +3,8 @@
#
import re
import bisect
from Errors import warning, error, InternalError
import Options
import Naming
......@@ -12,6 +14,7 @@ import TypeSlots
from TypeSlots import \
pyfunction_signature, pymethod_signature, \
get_special_method_signature, get_property_accessor_signature
import ControlFlow
import __builtin__
identifier_pattern = re.compile(r"[A-Za-z_][A-Za-z0-9_]*$")
......@@ -43,6 +46,7 @@ class Entry:
# setter_cname string C func for setting or deleting property
# is_self_arg boolean Is the "self" arg of an exttype method
# is_arg boolean Is the arg of a method
# is_local boolean Is a local variable
# is_readonly boolean Can't be assigned to
# func_cname string C func implementing Python func
# pos position Source position where declared
......@@ -91,6 +95,7 @@ class Entry:
setter_cname = None
is_self_arg = 0
is_arg = 0
is_local = 0
is_declared_generic = 0
is_readonly = 0
func_cname = None
......@@ -145,6 +150,7 @@ class Scope:
# qualified_name string "modname" or "modname.classname"
# pystring_entries [Entry] String const entries newly used as
# Python strings in this scope
# control_flow ControlFlow Used for keeping track of environment state
is_py_class_scope = 0
is_c_class_scope = 0
......@@ -187,6 +193,16 @@ class Scope:
self.num_to_entry = {}
self.obj_to_entry = {}
self.pystring_entries = []
self.control_flow = ControlFlow.LinearControlFlow()
def start_branching(self, pos):
self.control_flow = self.control_flow.start_branch(pos)
def next_branch(self, pos):
self.control_flow = self.control_flow.next_branch(pos)
def finish_branching(self, pos):
self.control_flow = self.control_flow.finish_branch(pos)
def __str__(self):
return "<%s %s>" % (self.__class__.__name__, self.qualified_name)
......@@ -233,6 +249,7 @@ class Scope:
if name:
entry.qualified_name = self.qualify_name(name)
dict[name] = entry
entry.scope = self
return entry
def qualify_name(self, name):
......@@ -341,6 +358,7 @@ class Scope:
entry = self.declare(name, cname, type, pos)
entry.is_variable = 1
entry.visibility = visibility
self.control_flow.set_state((), (name, 'initalized'), False)
return entry
def declare_builtin(self, name, pos):
......@@ -1025,6 +1043,7 @@ class LocalScope(Scope):
entry = Scope.declare_var(self, name, type, pos,
cname, visibility, is_cdef)
entry.init_to_none = type.is_pyobject
entry.is_local = 1
self.var_entries.append(entry)
return entry
......
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