https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88587
--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> --- I think the problem is that while we make TYPE_MODE something dynamic for vector types (which takes into account whether the current function supports in hw such vectors or not): #define TYPE_MODE(NODE) \ (VECTOR_TYPE_P (TYPE_CHECK (NODE)) \ ? vector_type_mode (NODE) : (NODE)->type_common.mode) we don't do the same thing for DECL_MODE: /* Holds the machine mode corresponding to the declaration of a variable or field. Always equal to TYPE_MODE (TREE_TYPE (decl)) except for a FIELD_DECL. */ #define DECL_MODE(NODE) (DECL_COMMON_CHECK (NODE)->decl_common.mode) #define SET_DECL_MODE(NODE, MODE) \ (DECL_COMMON_CHECK (NODE)->decl_common.mode = (MODE)) We've run into this several times in the past already. See e.g. PR78643. It is probably not the right time to change the DECL_MODE macro definition in stage4, so that leaves us to do some hacks where needed.
