[PATCH/RFC] options: Make --help= to emit values post-overrided

Segher Boessenkool segher@kernel.crashing.org
Fri Aug 7 14:42:12 GMT 2020


Hi!

On Fri, Aug 07, 2020 at 10:44:10AM +0800, Kewen.Lin wrote:
> > I think this makes a lot of sense.
> > 
> >> btw, not sure whether it's a good idea to move target_option_override_hook
> >> call into print_specific_help and use one function local static
> >> variable to control it's called once for all kinds of help dumping
> >> (possible combination), then can remove the calls in function 
> >> common_handle_option.
> > 
> > I cannot easily imagine what that will look like...  it could easily be
> > worse than what you have here (callbacks aren't so nice, but there are
> > worse things).
> > 
> 
> I attached opts_alt2.diff to be more specific for this, both alt1 and alt2
> follow the existing callback scheme, alt2 aims to avoid possible multiple
> times target_option_override_hook calls when we have several --help= or
> similar, but I guess alt1 is also fine since the hook should be allowed to
> be called more than once.

It could take quadratic time in alt1...  Mostly a theoretical problem I
think, but still.

All options look fine to me, but you need someone else to approve this ;-)

One thing:

> @@ -1664,6 +1665,14 @@ print_specific_help (unsigned int include_flags,
>  	}
>      }
>  
> +  static bool call_override_once_p = false;
> +  if (!call_override_once_p)
> +    {
> +      gcc_assert (target_option_override_hook);
> +      target_option_override_hook ();
> +      call_override_once_p = true;
> +    }

That assert is pretty random, nothing else using the hook assert it
isn't zero; it immediately and always calls the hook right away, so you
will get a nice ICE with backtrace if it is zero *anyway*.

Cheers,


Segher


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