https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83729
--- Comment #2 from Georg-Johann Lay <gjl at gcc dot gnu.org> --- ...and this is a middle-end flaw because POINTERS_EXTEND_UNSIGNED states: [...] You need not define this macro [which is the case for avr] if the ptr_mode, Pmode and word_mode are all the same width [which is also true for avr]. https://gcc.gnu.org/onlinedocs/gcc-7.2.0/gccint/Storage-Layout.html#index-POINTERS_005fEXTEND_005fUNSIGNED Actually I don't see any readon for why an extension should be needed here as both targetm.addr_space.pointer_mode (__memx) and targetm.addr_space.address_mode (__memx) are PSImode.
