[Bug sanitizer/83388] reference statement index not found error with -fsanitize=null

["jakub at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83388

--- Comment #8 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
(In reply to Jan Hubicka from comment #7)
> I believe we do not stream any references to references and once we start to
> do we will need to invent machinery to keep them intact like we have for
> edges and symbols. So I would go for removal of the refernece.
> 
> I however wonder if this is the best place to remove statements from
> function. I would expect either fixup_cfg or one of the IPA transform stages
> to be responsible for this instead.

So where exactly?  Ideally in something that has to walk the whole IL again.

> Why flag_sanitize is not optimization and not streamed along with function
> bodies? It seems to make sense to mix sanitized and unsanitized units.

We've tried that (merging options on lto reads) and it just didn't work and was
a complete nightmare.
There are many different sanitizers, and they are discovered and lowered and
handled at different stages (FEs, gimplifier, ubsan pass, asan pass, tsan pass,
sanopt pass, ...).