http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50661
--- Comment #16 from Andreas Krebbel <krebbel at gcc dot gnu.org> 2011-10-11 11:41:12 UTC --- (In reply to comment #15) > Andreas, can I have your feedback about this? Is it safe or not to compare > s390 > pointers with memcmp? On s390 with 31 bit addressing the uppermost bit indicates to the hardware that 31 bit addressing is used instead of just 24 bit. This indeed is a problem when creating pointers from integers, what is anyway not backed by the C standard, or when using __builtin_return_address without masking the bits. However GCC does *not* mask the bits when comparing two pointer values. So (void*)0x00000000 == (void*)0x80000000 does *not* evaluate to true on s390. To my understanding using a memcmp would not break things for s390. If it is broken with memcmp it was broken before as well. I don't know how this works with ARM. I think they put their THUMB markers into the lower order bits of an address and perhaps we should better check how they implement a pointer compare.
