https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84213
--- Comment #11 from rguenther at suse dot de <rguenther at suse dot de> --- On Thu, 8 Feb 2018, derodat at adacore dot com wrote: > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84213 > > --- Comment #10 from Pierre-Marie de Rodat <derodat at adacore dot com> --- > (In reply to Richard Biener from comment #8) > > Yeah, setting DECL_PRESERVE_P would make it possible to add the > > location late since we'd not remove the decl. Currently it's simply > > gone and the early dwarf2out_"late"_global_decl is the last thing > > we see from it... > Ok, understood. > > > Currently struggling in getting a debuggable gnat1 built .. it looks > > like ./configure --enable-languages=c++,ada --disable-bootstrap > > no longer works with a host compiler that doesn't understand some > > C++ specs that appear to be used (GCC 4.8). > I’m using GCC 7.2.1. It’s odd that you get this issue only with gnat1, though… > > (In reply to Richard Biener from comment #9) > > Another possibility would be to add the info symbolically by refering to the > > early DIE of the other entity. Not sure if that works for the Ada cases? > > We have > > DW_OP_GNU_variable_value but in this case we want the DIEs address. > In the original ADa use case, there is no other entity: the variable for which > we want to emit a location is around only for its name, so instead of > allocating a memory slot for it, we produce a “dummy” location (DW_OP_const1s: > -1). So I don’t know: would what you have in mind work? (just keeping > producing > a location is enough for Ada, I think) Ah, ok. A DW_OP_const1s location is fine early ;) > > Btw, if you compile any of your testcases for the issue with -g -flto > > can you verify if the generated object files contain relocations in the > > early LTO debug sections? Those should not refer to real symbols... > > else the problem will manifest with Ada as well. > I’m confused: is this query for myself or for one Martin? ;-) For you but the above clears it - a DW_OP_const1s doesn't produce a relocation ;) This means you should be able to arrange for this to be emitted by tree_add_const_value_attribute_for_decl as well, no? > > So I think we do have to revert the revision in question (or put in the > > above hack). > Either way, in the end we need a solution that fixes the SPEC build error and > that does not make Ada debugging regress. :-) > > I’m still not familiar with LTO and how early/late passes are supposed to > work, > so I lack judgment about what is a hack and what isn’t. Do you think we can > find a clean way to delay location production from the “early late” pass to > the > “truly late” one? See above - I think we should emit this special value from tree_add_const_value_attribute_for_decl instead, reverting the original patch. As I can't seem to get a gnat1 debugged right now can you try to see what would be necessary to do that? How's the DECL_VALUE_EXPR looking like?
