https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120780
--- Comment #15 from Siddhesh Poyarekar <siddhesh at gcc dot gnu.org> --- (In reply to Jakub Jelinek from comment #14) > > So, __bdos returns something larger than that? That would be weird. > Or do the two calls result in different results? It's basically comment 9; __bdos returns 0 because it thinks the negative offset to access the parent struct using the child pointer is an invalid access. That will basically happen at runtime too, with the MAX(sz, offset) - offset pattern we emit. What we basically need is a way to identify the MEM_REF in such cases and use the parent struct to get the size: _1 = MEM[(struct container *)ifmsh_5 + -24B] recognize that TREE_TYPE(_1) contains TREE_TYPE(ifmsh_5) and adjust for it.
