Re: [PATCH 2/2] [gdb/build] Return const reference in thread_info_to_thread_handle

[Pedro Alves <pedro@palves.net>]

On 22/08/23 18:34, Tom de Vries wrote:

> I've given the gdb::array_view<const gdb_byte> a try, and that works fine, and greatly simplifies the patch, so thanks for that suggestion.

Great!

> The first patch is no longer necessary, but we could consider committing it nevertheless, since the work is done and may be needed in the future.

I agree.

>  
> -gdb::byte_vector
> +gdb::array_view<const gdb_byte>
>  remote_target::thread_info_to_thread_handle (struct thread_info *tp)
>  {
>    remote_thread_info *priv = get_remote_thread_info (tp);
> diff --git a/gdb/target-debug.h b/gdb/target-debug.h
> index acb01d47e7c..31c25e9aefd 100644
> --- a/gdb/target-debug.h
> +++ b/gdb/target-debug.h
> @@ -236,4 +236,18 @@ target_debug_print_gdb_byte_vector_r (gdb::byte_vector &vector)
>  {
>    target_debug_print_const_gdb_byte_vector_r (vector);
>  }
> +
> +static void
> +target_debug_print_gdb_array_view_const_gdb_byte (gdb::array_view<const gdb_byte> &vector)

array_views should be passed by value normally (because they're small).  Did you run into something
that forced this to be a reference?  Or was it just copied from the vector case?  If it
works, we should just drop the &.

Also, one of the points of array_view is that you can pass a vector as array_view
argument, like you can pass std::string as string_view argument -- would it work to make
target_debug_print_const_gdb_byte_vector_r call this new
target_debug_print_gdb_array_view_const_gdb_byte instead of duplicating that code?

> +{
> +  gdb_puts ("{", gdb_stdlog);
> +
> +  for (size_t i = 0; i < vector.size (); i++)
> +    {
> +      gdb_printf (gdb_stdlog, " %s",
> +		  phex_nz (vector[i], 1));
> +    }
> +  gdb_puts (" }", gdb_stdlog);
> +}
> +
>  #endif /* TARGET_DEBUG_H */

...

> diff --git a/gdb/target.c b/gdb/target.c
> index 16f43d072cd..8b1d48d91d9 100644
> --- a/gdb/target.c
> +++ b/gdb/target.c
> @@ -2640,7 +2640,7 @@ target_thread_handle_to_thread_info (const gdb_byte *thread_handle,
>  
>  /* See target.h.  */
>  
> -gdb::byte_vector
> +gdb::array_view<const gdb_byte>
>  target_thread_info_to_thread_handle (struct thread_info *tip)
>  {
>    target_ops *target = current_inferior ()->top_target ();
> diff --git a/gdb/target.h b/gdb/target.h
> index 6ae400e2cc2..0cea955cbd7 100644
> --- a/gdb/target.h
> +++ b/gdb/target.h
> @@ -39,6 +39,10 @@ struct expression;
>  struct dcache_struct;
>  struct inferior;
>  
> +/* Define const gdb_byte using one identifier, to make it easy for
> +   make-target-delegates.py to parse.  */
> +typedef const gdb_byte const_gdb_byte;

That's unfortunate, but I can live with it.