Inada Naoki <songofaca...@gmail.com> added the comment:
> In 3.8, the union used to ensure alignment on a C double is gone. Note that two uintptr_t is aligned 16bytes on 64bit platforms and 8bytes on 32bit platforms. Python 3.7 is worse than 3.8. It used "double dummy" to align by 8 bytes, not 16 bytes. We should use "long double" to align by 16 bytes. https://software.intel.com/sites/default/files/article/402129/mpx-linux64-abi.pdf But it means +8 bytes for all tuples. If we backport PR-12850 to 3.7, +8 bytes for 1/2 tuples, and +16 bytes for remaining tuples. Any ideas about reduce impact for Python 3.7? For example, can we add 8byte dummy to PyGC_Head, and tuple use the dummy for hash? Maybe, it breaks ABI.... Not a chance... I wonder if we can add -fmax-type-align=8 for extension types... ---------- _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue27987> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
