On Thu, Jan 24, 2019 at 10:15 AM Richard Biener <richard.guent...@gmail.com> wrote: > > Ah, I missed that pt is probably a pointer type as well, then the code > simply aligns the pointed-to type (note dependent on how pt was built > this seems prone to wreck the TYPE_POINTER_TO/TYPE_NEXT_PTR_TO > chains which link pointer types to a type.
Right. In fact, set_placeholder_pointer_type asserts that both pt and tt are pointer types. It's true that, after a call to set_placeholder_pointer_type, pt becomes a distinct pointer type to T, yet is not part of the TYPE_POINTER_TO/TYPE_NEXT_PTR_TO chain for T. As far as I can tell, that's fine. The chain for T remains intact, as placeholder pointer types are careful to always point to a distinct dummy object (see the Gcc_backend::placeholder_pointer_type method) that nothing cares about. The only consequence I see is the increased memory usage of having multiple distinct but semantically identical pointer types to T.
