-On [20111024 09:22], Stefan Behnel (stefan_ml at behnel.de) wrote: >>I agree. Given that the analysis shows that the libc memcmp() is >>particularly fast on many Linux systems, it should be up to the Python >>package maintainers for these systems to set that option externally through >>the optimisation CFLAGS. Indeed, this is how I constructed my Python 3.3 and Python 2.7 : setenv CFLAGS '-fno-builtin-memcmp' just before I configured. I would like to revisit changing unicode_compare: adding a special arm for using memcmp when the "unicode kinds" are the same will only work in two specific instances: (1) the strings are the same kind, the char size is 1 * We could add THIS to unicode_compare, but it seems extremely specialized by itself (2) the strings are the same kind, the char size is >1, and checking for equality * Since unicode_compare can't detect equality checking, we can't really add this to unicode_compare at all The problem is, of course, that memcmp won't compare for less-than or greater-than correctly (unless on a BIG ENDIAN machine) for char sizes of 2 or 4. If we wanted to put memcmp in unicodeobject.c, it would probably need to go into PyUnicode_RichCompare (so we would have some more semantic information). I may try to put together a patch for that, if people think that's a good idea? It would be JUST adding a call to memcmp for two instances specified above. >From: Jeroen Ruigrok van der Werven <asmodai at in-nomine.org> >In the same stretch, stuff like this needs to be documented. Package >maintainers cannot be expected to follow each and every mailinglist's posts >for nuggets of information like this. Been there, done that, it's impossible >to keep track. I would like to second that: the whole point of a Makefile/configuration file is to capture knowledge like this so it doesn't get lost. I would prefer the option would be part of a standard build Python distributes, but as long as the information gets captured SOMEWHERE so that (say) Fedora Core 17 has Python 2.7 built with -fno-builtin-memcmp, I would be happy. Gooday, Richie -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://mail.python.org/pipermail/python-dev/attachments/20111024/5c4355b8/attachment.html>
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