[Bug lto/65536] LTO line number information garbled

[manu at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65536

--- Comment #25 from Manuel López-Ibáñez <manu at gcc dot gnu.org> ---
(In reply to Jan Hubicka from comment #24)
> Manuel, you may be right person to implement the streaming of linemaps then

I have in fact considered it already, since I think it should be fairly easy
and it can be done incrementally. However, as always in GCC, things are never
as trivial as they seem. I just tried following
https://gcc.gnu.org/wiki/DebuggingGCC#Debugging_LTO to see what
dump_line_table_statistics reports before and after my patch above, but it
doesn't print the lto1 invokation. The debugx scripts
(https://gcc.gnu.org/ml/gcc/2004-03/msg01195.html) do not seem to work with
lto1 (why those scripts are not in contrib/?). I feel like a new contributor
again! :)

Thus, sorry I don't really have the necessary free time to dedicate to this.
I'm too busy with my real job at the moment. If/When I have time to dedicate to
develop GCC, I will finish the transition of Fortran to the common diagnostics
machinery, and then I will focus on C/C++ diagnostics.

I still think that a patch similar to the one in comment #21 (+libcpp parts in
comment #17) may improve the situation for GCC 5 and fix PR54962.