https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102989
--- Comment #62 from Jakub Jelinek <jakub at gcc dot gnu.org> --- What the patch including incremental one currently does is: 1) small _BitInt (on x86-64 N <= 64) - the BITINT_TYPEs are kept as is in the IL and expanded, they always have non-BLKmode (QI/HI/SI/DI) and are handled like any other INTEGER_TYPEs (except preserved in calls to ensure correct ABI passing) 2) middle _BitInt (on x86-64 N <= 128) - I keep in the IL just copy operations and casts between them and INTEGER_TYPE (TImode in this case), actual arithmetics is done on the INTEGER_TYPE 3) large _BitInt (on x86-64 that will be <= 255) - the intent was using BIT_FIELD_REFs/BIT_INSERT_EXPR to make the IL simple and perform stuff on the up to 4 limbs in this case in straight line code 4) huge _BitInt (on x86-64 N > 255) use loops, VAR_DECL destination, VCE+ARRAY_REF on the sources, dunno yet if I can get good code by making the VAR_DECL clobbered immediately after I load a SSA_NAME from it (whether out of SSA/expansion could then extend the lifetime of the VAR_DECL, or if I should have some pass do that, or the bitint pass figure out the last use and put clobber only after that, or even replace the SSA_NAME uses with accesses to VAR_DECL Anyway, I think I'll work now on the add/sub with carry now and continue on _BitInt only after that.
