Hum, I read again my old REGISTERVM.txt that I wrote a few years ago. A little bit more context. In my "registervm" fork I also tried to implement further optimizations like moving invariants out of the loop. Some optimizations could change the Python semantics, like remove "duplicated" LOAD_GLOBAL whereas the global might be modified in the middle. I wanted to experiment such optimizations. Maybe it was a bad idea to convert stack-based bytecode to register-based bytecode and experiment these optimizations at the same time.
Victor Le mar. 26 févr. 2019 à 22:42, Victor Stinner <vstin...@redhat.com> a écrit : > > No, I wasn't aware of this project. My starting point was: > > http://static.usenix.org/events/vee05/full_papers/p153-yunhe.pdf > Yunhe Shi, David Gregg, Andrew Beatty, M. Anton Ertl, 2005 > > See also my email to python-dev that I sent in 2012: > https://mail.python.org/pipermail/python-dev/2012-November/122777.html > > Ah, my main issue was my implementation is that I started without > taking care of clearing registers when the stack-based bytecode > implicitly cleared a reference (decref), like "POP_TOP" operation. > > I added "CLEAR_REG" late in the development and it caused me troubles, > and the "correct" register-based bytecode was less efficient than > bytecode without CLEAR_REG. But my optimizer was very limited, too > limited. > > Another implementation issue that I had was to understand some > "implicit usage" of the stack like try/except which do black magic, > whereas I wanted to make everything explicit for registers. I'm > talking about things like "POP_BLOCK" and "SETUP_EXCEPT". In my > implementation, I kept support for stack-based bytecode, and so I had > some inefficient code and some corner cases. > > My approach was to convert stack-based bytecode to register-based > bytecode on the fly. Having both in the same code allowed to me run > some benchmarks. Maybe it wasn't the best approach, but I didn't feel > able to write a real compiler (AST => bytecode). > > Victor > > Le mar. 26 févr. 2019 à 21:58, Neil Schemenauer <nas-pyt...@python.ca> a > écrit : > > > > On 2019-02-26, Victor Stinner wrote: > > > I made an attempt once and it was faster: > > > https://faster-cpython.readthedocs.io/registervm.html > > > > Interesting. I don't think I have seen that before. Were you aware > > of "Rattlesnake" before you started on that? It seems your approach > > is similar. Probably not because I don't think it is easy to find. > > I uploaded a tarfile I had on my PC to my web site: > > > > http://python.ca/nas/python/rattlesnake20010813/ > > > > It seems his name doesn't appear in the readme or source but I think > > Rattlesnake was Skip Montanaro's project. I suppose my idea of > > unifying the local variables and the registers could have came from > > Rattlesnake. Very little new in the world. ;-P > > > > Cheers, > > > > Neil > > > > -- > Night gathers, and now my watch begins. It shall not end until my death. -- Night gathers, and now my watch begins. It shall not end until my death. _______________________________________________ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
