https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105023
--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> --- But reg:BLK is exactly what the backend emits. Both on the 2 testcases mentioned above (on which there is an ICE afterwards) and say on: struct a { short b : 2048; }; void c(...) { c(a()); } which doesn't ICE. rs6000_function_arg still returns (reg:BLK 3 3).