Andrew, Thank you for your kind reply. You alerted me to the fact that the bug I am seeing is likely limited to a version or a small range of versions of GCC. I have thus tinkered with my project's CMakeLists.txt and discovered the following: * The compiler was originally set to `gcc-11`, whereas in my previous email I incorrectly reported the version of the default `gcc` executable, which happens to be version 11.2. * Switching the compiler in CMakeLists.txt to `gcc-10` fixed the issue for me.
Here is the output of the --version option for both compilers. $ gcc-10 --version gcc-10 (Debian 10.2.1-6) 10.2.1 20210110 $ gcc-11 --version gcc-11 (Debian 11.2.0-12) 11.2.0 I have thus concluded that the bug causing the segfaults that I described affects version 11.2 but not 10.2. I was unable to find deb packages for neither version 10.4, which you suggested might have a fix for this bug, nor 10.3. Hence, I cannot report on the presence of this bug in any other version. How I might help diagnose and fix this bug? For instance, how does one run gcc from inside gdb? I know that gcc is just the driver and cc1plus is the actual compiler, so I presume I'd have to run cc1plus inside gdb, but as far as I know cc1plus cannot be called directly. Suggestions? -- Alex On Wed, Dec 22, 2021 at 5:16 PM Andrew Pinski <pins...@gmail.com> wrote: > > On Wed, Dec 22, 2021 at 5:07 PM Alessandro Baretta via Gcc > <gcc@gcc.gnu.org> wrote: > > > > Hello GCC hackers, and thank you very much for your precious work here. > > > > I've been observing somewhat random GCC segfaults in my C++ 20 > > codebase for a while. By "random" I mean that if I rerun the cmake > > build after a failure, 75% out of the time it will succeed, and it > > might fail again the next time I try running the build. I have every > > reason to believe that the issue is not with my code because: > > 1) At the second (or more rarely third) attempt at running the build, > > it succeeds. > > 2) Clang does not segfault on the same codebase, and indeed produces > > correct code. > > Maybe https://gcc.gnu.org/PR99831 Which was fixed in GCC 10.4 but was > broken in GCC 10.2.x. > This is a garbage collector related Internal compiler error which can > seem to randomly appear and disappear even. > > Thanks, > Andrew Pinski > > > > > The codebase is fairly large and heavily templatized, so I know that > > the the compiler allocates a seemingly inordinate amount of memory > > (using top, I've seen it reach a RES size of 1.6GB and a VIRT size of > > 4GB), so I initially attributed the segfaults to lack of enough memory > > on my computer (16GB, with chrome running...). Now I turned on swap > > (32GB), and I see that even when gcc is running, there is plenty of > > available memory, so this is not a plausible cause. > > > > The possibility of a hardware glitch in my system also does not hold > > much water, as neither clang nor any other piece of software seems to > > exhibit any instability. > > > > It'd be great if I could get some guidance on how to investigate this > > issue further. If it were of value to the developers, I'd be happy to > > file a bug report, but given the randomness of the issue, I doubt that > > they'd be able to reproduce the problem even with a preprocessed file. > > What then is my path forward? > > > > Here's some information that might be relevant: > > > > $ cat /etc/debian_version > > 11.1 > > $ gcc --version > > gcc (Debian 10.2.1-6) 10.2.1 20210110 > > Copyright (C) 2020 Free Software Foundation, Inc. > > This is free software; see the source for copying conditions. There is NO > > warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. > > > > > > Thanks for any help! > > > > -- > > Alex Baretta > > t: 650-383-0227 -- Alex Baretta t: 650-383-0227
