On 02.03.2022 23:42:53, Vincent MAILHOL wrote:
> On Wed. 2 Mar 2022 at 22:04, Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx> wrote:
> > I was thinking of this:
> >
> > | void *foo = bar->baz;
> > |
> > | if (!bar)
> > | return;
> > |
> > | printf("%p", foo);
> >
> > There were/are compilers that optimize the bar NULL pointer check away,
> > because bar has already been de-referenced.
>
> Sorry, I do not get your example. If bar is NULL,
> | void *foo = bar->baz;
> would segfault and thus the check is not reached.
ACK
> If bar is not NULL, the check succeeds.
>
> In both cases, the return statement of the if branch is never
> executed making this some dead code. So I do not see why this is
> an issue if the compiler removes it.
IIRC in some cases the code was shuffled around by the compiler and the
NULL pointer check was done....and with a new compiler version it
stopped working :)
regards,
Marc
--
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