Re: [FFmpeg-devel] [PATCH] configure: remove false positives with valgrind-memcheck

[Pierre-Anthony Lemieux <pal@sandflow.com>]

On Sun, Jun 9, 2024 at 6:41 AM James Almer <jamrial@gmail.com> wrote:
>
> On 6/9/2024 2:56 AM, Pierre-Anthony Lemieux wrote:
> > On Sat, Jun 8, 2024 at 6:13 PM James Almer <jamrial@gmail.com> wrote:
> >>
> >> On 6/8/2024 9:59 PM, pal@sandflow.com wrote:
> >>> From: Pierre-Anthony Lemieux <pal@palemieux.com>
> >>>
> >>> If  `--toolchain=valgrind-memcheck` is selected, fate-lavf-asf fails on a false positive.
> >>
> >> I can't reproduce this. Tried with both --disable-optimizations and
> >> without it, on Ubuntu 22.04 x86_64.
> >> How are you getting these false positives?
> >
> > Command and log at https://pastebin.com/3TKk0RF4
>
> But that command is missing all the extra args configure adds to the
> invocation, before and after your patch.

Full story.

Before the proposed patch, "./configure --toolchain=valgrind-memcheck;
make fate-lavf-asf" results in "Conditional jump or move depends on
uninitialised value(s)" being emitted on my system (gcc (Ubuntu
9.4.0-1ubuntu1~20.04.1) 9.4.0).

The proposed patch only adds  "--expensive-definedness-checks=yes" to
the "valgrind-memcheck" command line -- this was the result of a
discussion on the mailing list.

After the proposed patch, "./configure --toolchain=valgrind-memcheck;
make fate-lavf-asf" does not result in any error being emitted.

The pastebin is intended to isolate the issue/solution. On my system,
adding/removing "--expensive-definedness-checks=yes" to the command
line removes/triggers the issue.

Let me know if you need additional information.

Thanks for reviewing.

>
> >
> >>
> >>> ---
> >>>    configure | 2 +-
> >>>    1 file changed, 1 insertion(+), 1 deletion(-)
> >>>
> >>> diff --git a/configure b/configure
> >>> index 6c5b8aab9a..c708f2e38c 100755
> >>> --- a/configure
> >>> +++ b/configure
> >>> @@ -4571,7 +4571,7 @@ case "$toolchain" in
> >>>                    target_exec_args="--tool=massif --alloc-fn=av_malloc --alloc-fn=av_mallocz --alloc-fn=av_calloc --alloc-fn=av_fast_padded_malloc --alloc-fn=av_fast_malloc --alloc-fn=av_realloc_f --alloc-fn=av_fast_realloc --alloc-fn=av_realloc"
> >>>                    ;;
> >>>                valgrind-memcheck)
> >>> -                target_exec_args="--error-exitcode=1 --malloc-fill=0x2a --track-origins=yes --leak-check=full --gen-suppressions=all --suppressions=$source_path/tests/fate-valgrind.supp"
> >>> +                target_exec_args="--error-exitcode=1 --expensive-definedness-checks=yes --malloc-fill=0x2a --track-origins=yes --leak-check=full --gen-suppressions=all --suppressions=$source_path/tests/fate-valgrind.supp"
> >>>                    ;;
> >>>            esac
> >>>        ;;
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