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from rpython.flowspace.model import Variable, Constant, FSException
from rpython.rlib.unroll import SpecTag
def _copy(v):
from rpython.flowspace.flowcontext import FlowSignal
if isinstance(v, Variable):
return Variable(v)
elif isinstance(v, FlowSignal):
vars = [_copy(var) for var in v.args]
return v.rebuild(*vars)
else:
return v
def _union(seq1, seq2):
return [union(v1, v2) for v1, v2 in zip(seq1, seq2)]
class FrameState(object):
def __init__(self, locals_w, stack, last_exception, blocklist, next_offset):
self.locals_w = locals_w
self.stack = stack
self.last_exception = last_exception
self.blocklist = blocklist
self.next_offset = next_offset
self._mergeable = None
@property
def mergeable(self):
from rpython.flowspace.flowcontext import FlowSignal
if self._mergeable is not None:
return self._mergeable
self._mergeable = data = self.locals_w + recursively_flatten(self.stack)
if self.last_exception is None:
data.append(Constant(None))
data.append(Constant(None))
else:
data.append(self.last_exception.w_type)
data.append(self.last_exception.w_value)
return data
def copy(self):
"Make a copy of this state in which all Variables are fresh."
exc = self.last_exception
if exc is not None:
exc = FSException(_copy(exc.w_type), _copy(exc.w_value))
return FrameState(map(_copy, self.locals_w), map(_copy, self.stack),
exc, self.blocklist, self.next_offset)
def getvariables(self):
return [w for w in self.mergeable if isinstance(w, Variable)]
def matches(self, other):
"""Two states match if they only differ by using different Variables
at the same place"""
# safety check, don't try to compare states with different
# nonmergeable states
assert self.blocklist == other.blocklist
assert self.next_offset == other.next_offset
for w1, w2 in zip(self.mergeable, other.mergeable):
if not (w1 == w2 or (isinstance(w1, Variable) and
isinstance(w2, Variable))):
return False
return True
def _exc_args(self):
if self.last_exception is None:
return [Constant(None), Constant(None)]
else:
return [self.last_exception.w_type,
self.last_exception.w_value]
def union(self, other):
"""Compute a state that is at least as general as both self and other.
A state 'a' is more general than a state 'b' if all Variables in 'b'
are also Variables in 'a', but 'a' may have more Variables.
"""
try:
locals = _union(self.locals_w, other.locals_w)
stack = _union(self.stack, other.stack)
if self.last_exception is None and other.last_exception is None:
exc = None
else:
args1 = self._exc_args()
args2 = other._exc_args()
exc = FSException(union(args1[0], args2[0]),
union(args1[1], args2[1]))
except UnionError:
return None
return FrameState(locals, stack, exc, self.blocklist, self.next_offset)
def getoutputargs(self, targetstate):
"Return the output arguments needed to link self to targetstate."
result = []
mergeable = self.mergeable
for i, w_target in enumerate(targetstate.mergeable):
if isinstance(w_target, Variable):
result.append(mergeable[i])
return result
class UnionError(Exception):
"The two states should be merged."
def union(w1, w2):
"Union of two variables or constants."
from rpython.flowspace.flowcontext import FlowSignal
if w1 == w2:
return w1
if w1 is None or w2 is None:
return None # if w1 or w2 is an undefined local, we "kill" the value
# coming from the other path and return an undefined local
if isinstance(w1, Variable) or isinstance(w2, Variable):
return Variable() # new fresh Variable
if isinstance(w1, Constant) and isinstance(w2, Constant):
if isinstance(w1.value, SpecTag) or isinstance(w2.value, SpecTag):
raise UnionError
else:
return Variable() # generalize different constants
if isinstance(w1, FlowSignal) and isinstance(w2, FlowSignal):
if type(w1) is not type(w2):
raise UnionError
vars = [union(v1, v2) for v1, v2 in zip(w1.args, w2.args)]
return w1.rebuild(*vars)
if isinstance(w1, FlowSignal) or isinstance(w2, FlowSignal):
raise UnionError
raise TypeError('union of %r and %r' % (w1.__class__.__name__,
w2.__class__.__name__))
def recursively_flatten(lst):
from rpython.flowspace.flowcontext import FlowSignal
if not lst:
return lst
i = -1
for i in range(len(lst)):
if isinstance(lst[i], FlowSignal):
break
else:
return lst
lst = lst[:]
while i < len(lst):
unroller = lst[i]
if not isinstance(unroller, FlowSignal):
i += 1
else:
lst[i:i + 1] = unroller.args
return lst
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