Re: [PATCH v2] softmmu/physmem: Silence GCC 10 maybe-uninitialized error

[Thomas Huth]

On 17/01/2021 18.04, Philippe Mathieu-Daudé wrote:
> When building with GCC 10.2 configured with --extra-cflags=-Os, we get:
>
>    softmmu/physmem.c: In function ‘address_space_translate_for_iotlb’:
>    softmmu/physmem.c:643:26: error: ‘notifier’ may be used uninitialized in 
> this function [-Werror=maybe-uninitialized]
>      643 |         notifier->active = true;
>          |                          ^
>    softmmu/physmem.c:608:23: note: ‘notifier’ was declared here
>      608 |     TCGIOMMUNotifier *notifier;
>          |                       ^~~~~~~~
>
> Initialize 'notifier' to silence the warning.
>
> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
> ---
> v2: Remove pointless assert (Peter Maydell)
>
> Yet another hole in our CI.


I wouldn't call this a hole in the CI. AFAIU we don't support compiling with 
anything else than the default -O2 (and maybe -O0 for debugging?). -O3 is 
known to produce a lot of compiler warnings, and apparently -Os has such 
"problems", too. As far as I can see, it's a false positive warning here, 
"notifier" should always get initialized, the compiler just fails to see it 
correctly. Anyway, initializing the variable also can not hurt, so:

Reviewed-by: Thomas Huth <thuth@redhat.com>