On Sun, 18 Feb 2018, Sandra Loosemore wrote: > So what is the purpose of having a separate $target-protos.h?
It looks like the original explanation was <https://gcc.gnu.org/ml/gcc-patches/1999-09n/msg00866.html>, "Because tm_p.h needs to be included after tree.h and rtl.h.". It's certainly still true that rtl.h requires tm.h to have been included first. It's also true that tm_p.h depends on types beyond those for which simple forward declarations suffice - for example, the machine_mode enum (and now the various classes related to machine modes). So maybe in 1999 there would have been circular dependencies on types from tree.h and rtl.h. Now more things are included in coretypes.h (including e.g. the machine_mode enum via insn-modes.h). I don't know if circular dependency issues would still arise; any global move of prototypes into tm.h would require building cc1 for all architectures to locate any such problems. (Presumably the prototypes would also all need to be disabled for USED_FOR_TARGET.) An alternative to adding more tm_p.h includes or moving prototypes into tm.h would be, if there are only a few target macros involved, converting those target macros into hooks. -- Joseph S. Myers jos...@codesourcery.com
