
July 25, 2009
3:44 p.m.
Martin v. Löwis:
Yes: alignof(PyGC_HEAD) would be specified as being the maximum alignment on a platform; sizeof(PyGC_HEAD) would be frozen.
Maximum alignment currently on x86 is 16 bytes for SSE vector types. Next year AVX will add 32 byte types and while they are supposed to work OK with 16 byte alignment, performance will be better with 32 byte alignment. It is possible that some use could be found for vector instructions in core Python but it is more likely that they will only be used in specialized extensions that can take care of alignment issues for their own cases. http://en.wikipedia.org/wiki/Advanced_Vector_Extensions http://software.intel.com/en-us/forums/intel-avx-and-cpu-instructions/topic/... Neil