2015-04-03 21:49 GMT+03:00 Jan Hubicka <[email protected]>:
>> Assembler name of instrumented function is a transparent alias of
>> original function's name. Alias chains are not taken into account by
>> analysis. Thus we see no conflict between instrumented function's name
>> and a variable name but emit them with the same assembler name. To
>> detect name conflict I keep original function node alive.
>
> Hmm, so lets see if I understand your situation. You always have transparent
> alias TA
> and function F connected by IPA_REF_CHKP and because TA is represented as
> thunk
> you also have a fake call from TA to F?
>
> I do not understand how you can miss the link these days. I extended
> lto-cgraph to
> always keep thunk and its target in every unit that reffers to thunk. That
> should
> solve you problem? How IPA_REF_CHKP can link get lost?
References are not streamed out for nodes which are referenced in a
partition but don't belong to it ('continue' condition in output_refs
loop).
>
> I suppose we still need to
> 1) write_symbol and lto-symtab should know that transparent aliases are not
> real
> symbols and ignore them. We have predicate symtab_node::real_symbol_p,
> I suppose it should return true.
>
> I think cgraph_merge and varpool_merge in lto-symtab needs to know what
> to do
> when merging two symbols with transparent aliases.
> 2) At some point we need to populate transparent alias links as discussed in
> the
> other thread.
> 3) For safety, I guess we want symbol_table::change_decl_assembler_name to
> either
> sanity check there are no trasparent alias links pointing to old assembler
> names or update it.
Wouldn't search for possible referring via transparent aliases nodes
be too expensive?
> 4) I think we want verify_node to check that transparent alias links and
> chkp points
> as intended and only on those symbols where they need to be
>
> There is also logic in lto-partition to always insert alias target
>> > OK, so you have the chkp references that links to instrumented_version.
>> > You do not stream them for boundary symbols but for some reason they are
>> > needed,
>> > but when you can end up with wrong CHKP link?
>>
>> Wrong links may appear when cgraph nodes are merged.
>
> I see, I think you really want to fix these at merging time as sugested in 1).
> In this case even the node->instrumented_version pointer may be out of date
> and
> point to a node that lost in merging?
node->instrumented_version is redirected and never points to lost
symbol. But during merge we may have situations when
(node->instrumented_version->instrumented_version != node) because of
multiple not merged (yet) symbols referencing the same merged target.
Thanks,
Ilya
>
> Honza
>>
>> Thanks
>> Ilya
