Hello William,
Thanks for the comments. I see now (also from Ronan's reply) that it
only handles RPython, so I guess ends the question right about there :).
Basically I just wanted to see if I was missing some framework that
handled transforming Python code into a CFG for the purposes of analysis.
Otherwise I can just grab the bytecode or AST and do it myself, but I
didn't want to replicate any work if I didn't have to :)
Regards,
Scott
On 07/09/14 05:35 PM, William ML Leslie wrote:
Ugh, thanks Gmail (:
On 8 September 2014 01:33, William ML Leslie
<william.leslie....@gmail.com <mailto:william.leslie....@gmail.com>> wrote:
On 7 September 2014 21:42, Scott West <scott.gregory.w...@gmail.com
<mailto:scott.gregory.w...@gmail.com>> wrote:
Hello all,
I was looking recently into trying to do some simple static
analysis of Python programs (to experiment with what is
possible), and came across PyPy. Reading some of the
documentation it seems that PyPy forms a control flow graph and
does some abstract interpretation, which seems to indicate that
it could be used for other forms of static analysis!
Static analysis of python programs is not difficult, weather you use
ast or code objects. The flow object space really only works on
rpython though, using it to analyse python code generally is not
sensible.
I do think pypy is a great platform for associating axioms with
builtin functions and bytecodes (and sometimes other weird stuff
like exception handling, depending on your analysis) which you would
otherwise have to write by hand. If you want to do that, target
the llgraph stage of the compiler, as there is nothing 'outside' it
that you need to rely upon. You can possibly even generate the
app-level analyser from the interpreter, but in order to do this I
had to rewrite the eval loop - I could never figure out how to
extract semantics from the frame object.
I did at one point have something like a points-to analysis for
interp-level code working (a region polymorphic effects analysis),
but it has bitrotten beyond repair. I would still say pypy is a
great place to start, however.
I had a couple questions:
1) Would PyPy (seem) to be a good place to start for a
general analysis framework? If so, would it be of general interest?
2) If one doesn't care about code generation, can the build
time be reduced? I tried just using pyinteractive.py and that
_seemed_ to work, though even that compiles a few things to start.
By about 40% if you target llgraph by my last count. You could
avoid building the jit, since it should not have any semantic impact.
3) What is a good way to get into modifying the internals
(adding analyses, skipping code gen.)? I have read the chapter
of the Open Source Architecture book, and some of the
documentation pages.
0) Write lots of tests.
The existing tests make for good starting points.
1)
Start with a very small interpreter, not the full pypy
interpreter. IIRC there was a language called TL which was for
testing the JIT, use it as the target until everything works.
2) Dumping the llgraph to disk somewhere - perhaps into a logic or
relational database - will make little experiments easier.
I w
ould be most grateful if anyone could provide any comments on
these issues, or pointers to other similar works.
Unfortunately I have no idea what state my work was in when I left
it, I don't even have it on my current box; I would like to get back
to it at some point but Armin suggested I look at better low level
languages to target and I'm still working in that space.
--
William Leslie
Notice:
Likely much of this email is, by the nature of copyright, covered
under copyright law. You absolutely MAY reproduce any part of it in
accordance with the copyright law of the nation you are reading this
in. Any attempt to DENY YOU THOSE RIGHTS would be illegal without
prior contractual agreement.
--
William Leslie
Notice:
Likely much of this email is, by the nature of copyright, covered under
copyright law. You absolutely MAY reproduce any part of it in
accordance with the copyright law of the nation you are reading this in.
Any attempt to DENY YOU THOSE RIGHTS would be illegal without prior
contractual agreement.
_______________________________________________
pypy-dev mailing list
pypy-dev@python.org
https://mail.python.org/mailman/listinfo/pypy-dev
