https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68860
--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> --- (In reply to Jakub Jelinek from comment #4) > Created attachment 37097 [details] > gcc6-pr68860-lto.patch > > I've noticed that the new tests still fail with LTO. > It seems the reason is that LTO ignores DECL_HAS_DEBUG_ARGS_P etc., so this > stuff is just lost. > I've added some changes so that this is streamed, but it seems that is not > enough, DECL_ORIGIN of the decls is wrong, so it isn't used anyway. > BTW, Honza, why is: > if (code == VAR_DECL > && DECL_HAS_DEBUG_EXPR_P (t)) > visit (DECL_DEBUG_EXPR (t)); > used in hash_tree? Depends on what the function is used for, if it is for > code generation or something like that, better it should not depend on the > debug info stuff... So, the reason why nothing is emitted on the callee side with this patch is that LTO does never stream DECL_ABSTRACT_ORIGIN, and this is used to double check the data before actually trying to emit anything. Perhaps this could be bypassed by some lto condition, but in any case we'd need a way how to find out the correspondence between those decl_debug_args decls and the original arguments that were optimized away. The reason why nothing is emitted on the caller sides is that for some reason when streaming in the decl_debug_args, all the DEBUG_EXPR_DECLs turn out to be D#1, while they really should be D#1, D#2 etc. and the DEBUG_EXPR_DECLs emitted in the callers before those calls should match them, while they are assigned independently.
