Re: [PATCH] plugins: fix -Werror=maybe-uninitialized false-positive

[Pierrick Bouvier]

Hi Marc-André,

I could successfully build all targets with gcc 14.2.0 (using a debian 
sid container) with ubsan and asan enabled, and with -O2.

Pierrick

On 1/14/25 22:40, Marc-André Lureau wrote:
> Hi
>
> On Tue, Jan 14, 2025 at 8:00 PM Pierrick Bouvier
> <pierrick.bouvier@linaro.org> wrote:
> > On 1/14/25 02:48, marcandre.lureau@redhat.com wrote:
> > > From: Marc-André Lureau <marcandre.lureau@redhat.com>
> > >
> > > ../contrib/plugins/cache.c:638:9: error: ‘l2_cache’ may be used uninitialized 
> > > [-Werror=maybe-uninitialized]
> > >     638 |         append_stats_line(rep, l1_dmem_accesses, l1_dmisses,
> > >         |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > >
> > > Is a false-positive, since cores > 1, so the variable is set in the
> > > above loop.
> > >
> > > Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> > > ---
> > >    contrib/plugins/cache.c | 2 +-
> > >    1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/contrib/plugins/cache.c b/contrib/plugins/cache.c
> > > index 512ef6776b..c2c274cfcd 100644
> > > --- a/contrib/plugins/cache.c
> > > +++ b/contrib/plugins/cache.c
> > > @@ -609,7 +609,7 @@ static int l2_cmp(gconstpointer a, gconstpointer b)
> > >    static void log_stats(void)
> > >    {
> > >        int i;
> > > -    Cache *icache, *dcache, *l2_cache;
> > > +    Cache *icache, *dcache, *l2_cache = NULL;
> > >
> > >        g_autoptr(GString) rep = g_string_new("core #, data accesses, data 
> > > misses,"
> > >                                              " dmiss rate, insn accesses,"
> >
> > By the way,
> >
> > which compiler (version?) are you using?
> > Just curious to check if we don't have any other false positives in the
> > code base with it if it's a newer version.
>
>
> GCC v14.2.1 from fc41.
> I use '--enable-debug' '--enable-asan' '-Doptimization=g'
> '-Ddebug=true' in my configure flags.
> All targets do not compile with those flags.
> ASAN reports various errors during make test.
>
> Help welcome!