> >Usually the things stay to make DECL_UID stable across -g and -g0. > > Only DECL_UID order needs to be stable I think.
Well, when you remove a reference to a declaration, the DECL_UID order will change. We stream declarations in the order they are inserted to the encoder and that depends on specific references from the IL. Creating the decl and not inserting it to il/optimizing it out early is safe. We do so with debug statements, block local vars and other stuff. The difference to non-LTO is that in non-LTO you only need to be sure you create same decls in the same order. With LTO we need to be sure to keep all references streamed in the same order. I suppose we could avoid some of it by streaming DECL_UIDs and merging them same way as we do symbol_table->order but that will still have fun effects wrt merging. > > >This is not > >the case with LTO, > > I don't see how LTO does behave differently here. > > so ATM we do not have same codegen with lto and > >-g/-g0. I > >guess it is something we can start shooting for once early debug is in. > >> > >> That said - improve remove_unused_locals instead please? I looked into remove_unused_locals and in fact it is removing those decls aready to some degree, it just keeps all TYPE_DECLs when debug info is on. I will extend it to skip redundant typedefs. Honza
