On Fri, 20 Jan 2012, Georg-Johann Lay wrote: > Hi. > > avr-gcc implements a 24-bit scalar integer types __int24 and __uint24 in > avr.c:TARGET_INIT_BUILTINS like so: > > tree int24_type = make_signed_type (GET_MODE_BITSIZE (PSImode)); > tree uint24_type = make_unsigned_type (GET_MODE_BITSIZE (PSImode)); > > (*lang_hooks.types.register_builtin_type) (int24_type, "__int24"); > (*lang_hooks.types.register_builtin_type) (uint24_type, "__uint24"); > > PSImode is defined in avr-modes.c: > > FRACTIONAL_INT_MODE (PSI, 24, 3); > > Is this the right definition of a built-in type?
FRACTIONAL_INT_MODE should work after Bernd's patch series from last July relating to 40-bit types, though it's certainly possible there are issues that appear with 24-bit types but not 40-bit types. > The question is because __int24 shreds the compiler, see PR51527 > > So the question is if there is something missing or broken in the definition > above or if it's actually a flaw in the front-end. > > For the __int128 there is much more code sprinkled over the compiler sources, > so maybe it's not that easy to introduce a new, built-in type completely in > the > back-end? See my discussions with Bernd from last July. In essence, I don't think we should spread such code across the compiler for each non-power-of-2 size; ultimately we should go the other way, stop having any TImode or __int128 references in files outside config/, libgcc/config/ etc. and have targets using those modes and types choose to use the relevant source files for them. (And, further along, the existence of HImode, SImode, DImode ought to be target-dependent as well, with files in config/ that are used by targets with 8-bit bytes but maybe not by any targets with wider bytes.) -- Joseph S. Myers jos...@codesourcery.com
