On 3/18/19 6:35 PM, James Hilliard wrote: > On Mon, Mar 18, 2019 at 5:46 PM Jeff Law <l...@redhat.com> wrote: >> >> On 3/18/19 5:07 PM, James Hilliard wrote: >>> On Mon, Mar 18, 2019 at 4:51 PM Jakub Jelinek <ja...@redhat.com> wrote: >>>> >>>> On Mon, Mar 18, 2019 at 04:41:05PM -0600, James Hilliard wrote: >>>>>> Thanks, but I'm saying that if you look at the code you can see that >>>>>> st is clearly initialized, by the call to lstat. I would like to see >>>>>> an explanation for why you are seeing that warning before changing the >>>>>> code to disable it. Initializing st should not be necessary here. >>>>>> For example, perhaps lstat is a macro when compiling libsanitizer; if >>>>>> that is the underlying problem, then we should fix the macro, not this >>>>>> code. >>>>> Yeah, I'm not sure why the compiler thinks lstat isn't initializing st. >>>>> What should I do to debug this further? >>>> >>>> Guess you should start by telling us which OS it is on (I can't reproduce >>>> this warning on x86_64-linux nor i686-linux with glibc 2.28), looking at >>>> preprocessed source to see what exactly lstat does (e.g. if it is some >>>> macro >>>> or inline function and what exactly it is doing). >>> I am cross compiling with buildroot master branch using ubuntu 18.10. >>> I am building gcc 8.3.0 and glibc 2.29 for the cross toolchain. >>> The build and target systems are both x86_64. >> Add "-save-temps" to the command line. That will create a .i file, send >> the .i file along with the command line. > I added --save-temps to the cflags for the gcc package build. > Here's the command line log: > https://gist.githubusercontent.com/jameshilliard/015d972c26d1ec7bbbd1ad2d57d5dd3b/raw/7c848cdfba0967a681401de24ed6f4c86315d2d9/cli.log > Here's the elf.i fille: > https://gist.githubusercontent.com/jameshilliard/2a391d7292f3ba7412fe80e166c0f0e3/raw/63eb16ba9eff0b3ee668b16257b0948b2ca894a0/elf.i Jakub -- I haven't looked at it in any detail, but the first thing that jumps out at me is the -Og and the message:
> ../../../../libsanitizer/libbacktrace/../../libbacktrace/elf.c: In function > ‘elf_is_symlink’: > ../../../../libsanitizer/libbacktrace/../../libbacktrace/elf.c:772:21: error: > ‘st.st_mode’ may be used uninitialized in this function > [-Werror=maybe-uninitialized] > return S_ISLNK (st.st_mode); It could be the issues we've see with SRA and aggregates that have led to the discussion around breaking those into a distinct class of uninit warnings because we don't handle them well. I wouldn't be at all surprised if it goes away at -O1 or -O2. jeff
