Armin Rigo <arigo@tunes.org> writes:
Hi all,
Two days ago, we got our first JITing version of pypy-c!
This was mostly thanks to Arre, who compiled a version even though we knew it would segfault due to missing support for C structures with non-int-sized fields. Writing to a 1-byte-sized Bool field would overwrite the next 3 bytes of memory with zeroes... Nevertheless, the result managed to successfully run one function (and indeed segfault on many other functions). Our first JIT-run function! A recursive factorial.
Hooray!
- the above PYPYJITLOG env var causes a file called 'log' to be produced, containing the generated assembler code. It can be viewed in a flowgraph-like fashion with pypy/jit/codegen/i386/viewcode.py. Don't ask me yet to describe the result, nor where the while loop is :-) If you are familiar with i386 assembler, you'll laugh at the obviously bad code, too. That's where your help would be appreciated! Making the backend produce more reasonable code, starting with some basic register allocation, is a mostly-independent project. The PPC backend, btw, has already got this kind of techniques (I wonder what speed-ups we get on PPC from a jitting pypy-c).
Well, I guess so far it just plain doesn't work, but also the PPC register allocation is pretty horrible, especially around function calls. We've talked about the backend change needed to make this sensible (giving the list of live values to the block-ending builder methods), I guess it just has to be done at some point... Cheers, mwh -- You can lead an idiot to knowledge but you cannot make him think. You can, however, rectally insert the information, printed on stone tablets, using a sharpened poker. -- Nicolai -- http://home.xnet.com/~raven/Sysadmin/ASR.Quotes.html