[PING][PATCH] Update auxv cache when there is no auxv cached data

[Luis Machado <luis.machado@arm.com>]

On 7/19/22 15:45, Luis Machado via Gdb-patches wrote:
> While adding support for MTE corefiles and running the MTE corefile tests,
> I noticed a strange situation where loading the symbol file + core file
> through the command line has a different behavior compared to firing up
> GDB, loading the symbol file with the "file" command and then loading the
> core file with the "core" command.
> 
> I tracked this down to gdb/auxv.c:get_auxv_inferior_data returning a valid
> info struct, but with no auxv data.
> 
> We've been doing the auxv caching for a while now, but sometime between
> enabling auxv data caching and now, we turned the auxv data into an optional
> value.
> 
> My guess is that these two modes of opening a symbol file + core file take
> slightly different paths in GDB, and in the latter case where we issue
> separate "file" and "core" commands, we first cache empty auxv data (no core
> file data yet) and later we just return that empty data as if it were valid.
> 
> The following patch checks for an empty info->data field, and forces a re-fetch
> of auxv data if that is the case.
> 
> With this patch, I see full passes for the gdb.arch/aarch64-mte-core testcase.
> ---
>   gdb/auxv.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/gdb/auxv.c b/gdb/auxv.c
> index 8e175138f5d..0d6a860e5f4 100644
> --- a/gdb/auxv.c
> +++ b/gdb/auxv.c
> @@ -361,7 +361,7 @@ get_auxv_inferior_data (struct target_ops *ops)
>     struct inferior *inf = current_inferior ();
>   
>     info = auxv_inferior_data.get (inf);
> -  if (info == NULL)
> +  if (info == NULL || !info->data.has_value ())
>       {
>         info = auxv_inferior_data.emplace (inf);
>         info->data = target_read_alloc (ops, TARGET_OBJECT_AUXV, NULL);