bug#54532: [PATCH] sorting

[Eli Zaretskii]

> From: Andrew Cohen <acohen@ust.hk>
> Date: Wed, 23 Mar 2022 07:59:11 +0800
> 
> 1. Add a new `record_unwind_protect_ptr_mark` function for use with C data
>     structures that use the specpdl for clean-up but also contain possibly
>     unique references to Lisp objects. This is needed for the dynamic
>     memory management that the new algorithm uses.

Can you tell more why this was needed?  Emacs has conservative stack
marking, so any Lisp object that is referred by some stack-based
variable should be protected from GC.  Why isn't that enough in this
case?

> 4. An optimization that resolves the sorting comparison symbol into the
>     corresponding function before starting the sort.

Any reasons this is a separate patch?

Thanks a lot for working on this.