Christian Heimes added the comment: I'm a bit worried that the patch might slow down the general case of SipHash24. When I was working on SipHash24 I made sure that the general case in PyBytes_Object and PyUnicode_Object are fast and always aligned. Do all compilers optimize that case? For MSVC we still have a specialized Py_MEMCPY() variant in pyports.h.
I can see three more ways to fix the issue: 1) Have two loops, one for the aligned case with memcpy() and one for the unaligned case w/o memcpy() 2) Add a special variant of _le64toh() for PY_LITTLE_ENDIAN on ARM and use the current variant on X86_64. 3) Make it illegal to call _Py_HashBytes() with non-aligned pointer and require the caller to provide an aligned buffer. It's easy for datetime but requires an extra buffer memoryview. Memoryview already uses a buffer for all but single-strided C contiguous views. We can easily add another case for non-aligned buffers. ---------- stage: -> needs patch type: -> crash _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue28055> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
