[Bug c++/66487] New: [6 Regression] Firefox segfault with LTO enabled

[Bug c++/66487] New: [6 Regression] Firefox segfault with LTO enabled

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66487

            Bug ID: 66487
           Summary: [6 Regression] Firefox segfault with LTO enabled
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: marxin at gcc dot gnu.org
  Target Milestone: ---

Hi.

This if follow-up of PR66163, where I fixed all -fsanitize=null errors and give
another build spin.

Starting from r222135 Firefox built with -flto and -O2 crashed during start-up.
Unfortunately, back-trace looks completely corrupted.

Is there any way I can somehow isolate the issue?

Thanks,
Martin

[Bug c++/66487] [6 Regression] Firefox segfault with LTO enabled

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66487

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |6.0

[Bug c++/66487] [6 Regression] Firefox segfault with LTO enabled

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66487

--- Comment #1 from Jason Merrill <jason at gcc dot gnu.org> ---
Compiling with -fno-lifetime-dse should make it work again. 
-fsanitize=undefined doesn't currently catch this issue (relying on the value
of storage persisting into the lifetime of an object created there).

[Bug c++/66487] [6 Regression] Firefox segfault with LTO enabled

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66487

--- Comment #4 from Jason Merrill <jason at gcc dot gnu.org> ---
Actually, I guess checking for this is more of a fit for an uninitialized read
detector such as MemorySanitizer or Valgrind memcheck.

[Bug c++/66487] sanitizer/warnings for lifetime DSE

[egallager at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66487

Eric Gallager <egallager at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           See Also|                            |https://gcc.gnu.org/bugzill
                   |                            |a/show_bug.cgi?id=66163
                 CC|                            |egallager at gcc dot gnu.org

--- Comment #25 from Eric Gallager <egallager at gcc dot gnu.org> ---
this came up on the gcc-help mailing list here:
https://gcc.gnu.org/pipermail/gcc-help/2023-August/142848.html

[Bug c++/66487] sanitizer/warnings for lifetime DSE

[amonakov at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66487

Alexander Monakov <amonakov at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |amonakov at gcc dot gnu.org

--- Comment #26 from Alexander Monakov <amonakov at gcc dot gnu.org> ---
RFC patch for detecting lifetime-dse issues via Valgrind (rather than MSan):
https://inbox.sourceware.org/gcc-patches/20231024141124.210708-1-exactlywb@ispras.ru/

[Bug c++/66487] sanitizer/warnings for lifetime DSE

[egallager at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66487

--- Comment #27 from Eric Gallager <egallager at gcc dot gnu.org> ---
(In reply to Alexander Monakov from comment #26)
> RFC patch for detecting lifetime-dse issues via Valgrind (rather than MSan):
> https://inbox.sourceware.org/gcc-patches/20231024141124.210708-1-exactlywb@ispras.ru/

So, if this bug is now specifically for the valgrind approach, is there a
separate one for MSan?

[Bug c++/66487] sanitizer/warnings for lifetime DSE

[amonakov at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66487

--- Comment #28 from Alexander Monakov <amonakov at gcc dot gnu.org> ---
The bug is about the issue of lacking diagnostics, it should be fine to make
note of various approaches to remedy the problem in one bug report.

(in any case, all discussion of the Valgrind-based approach happened on the
gcc-patches mailing list, not here)

[Bug c++/66487] sanitizer/warnings for lifetime DSE

[egallager at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66487

--- Comment #29 from Eric Gallager <egallager at gcc dot gnu.org> ---
(In reply to Alexander Monakov from comment #28)
> The bug is about the issue of lacking diagnostics, it should be fine to make
> note of various approaches to remedy the problem in one bug report.
> 

OK, well, in this case, I'd like to make this the bug report for MSan support
in general, too, then; it's documented here:
https://github.com/google/sanitizers/wiki/MemorySanitizer

(In reply to Martin Liška from comment #20)
> (In reply to Jan Hubicka from comment #19)
> > Martin, I suppose the sanitizer bits can be tracked as enhancement and not
> > regression. It is a firefox bug so I suppose we can declare this a
> > non-regression.
> 
> Sure, maybe I would return to support of MSAN in GCC 7.

Maybe for GCC 14 now?

[Bug c++/66487] sanitizer/warnings for lifetime DSE

[egallager at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66487

--- Comment #30 from Eric Gallager <egallager at gcc dot gnu.org> ---
(In reply to Eric Gallager from comment #29)
> (In reply to Alexander Monakov from comment #28)
> > The bug is about the issue of lacking diagnostics, it should be fine to make
> > note of various approaches to remedy the problem in one bug report.
> > 
> 
> OK, well, in this case, I'd like to make this the bug report for MSan
> support in general, too, then; it's documented here:
> https://github.com/google/sanitizers/wiki/MemorySanitizer

...see also this wiki page, since GCC supports building with libc++ now:
https://github.com/google/sanitizers/wiki/MemorySanitizerLibcxxHowTo
...although, be aware that it's outdated, as per this issue: 
https://github.com/google/sanitizers/issues/1685