On Wed, 10 Jun 2015, Pierre-Marie de Rodat wrote: > Thank you for your answer, Richard! > > On 06/10/2015 08:58 AM, Richard Biener wrote: > > Hmm, so the underlying issue is that we don't associate comp_unit_die () > > with any TRANSLATION_UNIT_DECL. > > Indeed. > > > For the LTO early debug work I did the following at the very > > beginning of dwarf2out_early_finish: > > > > /* Pick the first TRANSLATION_UNIT_DECL we didn't create a DIE for > > and equate it with our default CU DIE. LTO output needs to be > > able to lookup DIEs for translation unit decls. */ > > unsigned i; > > tree decl; > > FOR_EACH_VEC_SAFE_ELT (all_translation_units, i, decl) > > if (!lookup_decl_die (decl)) > > equate_decl_number_to_die (decl, comp_unit_die ()); > > If I understand correctly, this does not only "pick the first" (as the comment > says) but do equate for all DIE-less units, right? Why isn't this hunk in > mainline yet by the way?
Hmm, yes. It meant to break after the first ;) (without LTO there usually is only one TU decl, apart from Java I think). The hunk isn't in mainline because it was part of an experimental patch I did on the early-debug branch. > > > We create some DIEs for builtin types too early before frontends > > got a chance to build their TRANSLATION_UNIT_DECL, so comp_unit_die > > gets created before there is any TRANSLATION_UNIT_DECL. Another > > approach would of course be that the Frontends register their main > > TRANSLATION_UNIT_DECL with dwarf2out via a debug hook. > > > > But - does the above work for you and fix the regression? If so > > adding a debug hook would probably be the cleaner solution still. > > Yes it does, thanks! However we need to fix this on the 4.9 branch as well and > this patch would need reworking to be applied there (no debug early). So > here's a patch that introduce a register_main_translation_unit debug hook: is > this what you had in mind? This works for me on the 4.9 branch and on mainline > as well, regtested on x86_64-linux. Yeah, that looks great! Of course I wonder about Java (builds multiple ones, one for each input file) and Go (no idea). I suppose Java would need to build another one where all the "defaults" go (or it doesn't have any such entities). In theory we could have changed dwarf2out_init to get a translation-unit-decl argument as well. But your patch looks like we don't have such at the point of dwarf2out_init in all frontends. Your patch is ok (and ok to backport) IMHO, though please give others the chance to chime in. Thanks, Richard.
