Re: [Emacs-diffs] master 19e09cf: Ensure redisplay after evaluation

[Stefan Monnier]

> @@ -1240,6 +1240,7 @@ set_internal (Lisp_Object symbol, Lisp_Object newval, 
> Lisp_Object where,
>       return;
>      }
 
> +  maybe_set_redisplay (symbol);
>    sym = XSYMBOL (symbol);
 
>   start:

In dynamic-binding code, this is a chunk of code that's executed *very*
often, so I expect your change could have a measurable performance impact
(e.g. on Gnus code).

The write-barrier discussed in the past moved this check to within the
SYMBOL_CONSTANT_P test.  More specifically, it turned the
SYMBOL_CONSTANT_P boolean into a field with 3 different values,
depending on whether a write can:
- go through at full-speed
- goes through a watcher function (or call it a "barrier")
- is not allowed at all

This way, assignments to most variables is unaffected.


        Stefan