On 05/23/2011 10:50 AM, Vitja Makarov wrote:
2011/5/23 Stefan Behnel<stefan...@behnel.de>:
Vitja Makarov, 23.05.2011 10:13:
With live variable analysis that should be easy to save/restore only
active variables at the yield point.
"Active" in the sense of "modified", I suppose? That's what I was expecting.
Active means that variable value will be used. In my example after
'print a' a isn't used anymore.
Btw now only reaching definitions analysis is implemented. I'm going
to optimize by replacing sets with bitsets. And then try to implement
live varaiables.
I'm going to delete variable reference using active variable info, but
that could introduce small incompatiblity with CPython:
a = X
print a #<- a will be decrefed here
print 'the end'
That incompatibility is not small at all. It breaks this code:
x = b'abc'
cdef char* c = x
Even if 'x' is no longer used after this point, it *must not* get freed
before 'c' is going away as well. That's basically impossible to decide, as
users may pass 'c' into a function that stores it away for alter use.
Yeah. That's hard to detect. But x could be marked as "don't decref
when not-active"
def f(object o):
cdef char* buf
buf = get_buffer_of_obj(o)
call_c_func(buf)
So there's a lot of variables that would have to be marked this way (but
not all, I can see that).
Dag Sverre
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