Re: Mips delay slot optimization

[Paul Cercueil]

Hi Paulo,

Le jeudi 23 février 2023 à 13:34 -0300, Paulo César Pereira de Andrade
a écrit :
>  Hi Paul,
> 
>   I wrote a new logic to optimize delay slot usage for the mips port.
> 
>  It was broken for mips6_p() anyway, so now there is  basically a
> full decoder to check if an instruction can be added to the delay
> slot,
> and a few new helpers to it.
> 
>   A basic documentation of how it works is in the commit changelog.
> 
>   I want to believe it is far more complete than your previous set of
> patches, and it also forces adding extra logic to the decoder if
> implementing new lightning functionality.
> 
>   To disable it in a hacky mode, just change instr() to never keep
> a pending() instruction.
> 
>   Please let me know if you see any regressions, or if somehow it
> is missing some delay slot usage optimization that was done in
> your patches.

There are definitely regressions, my emulator just hangs when running
8032a68, while 2.2.1 worked fine.

If I can find some time I will try to generate a small program that
reproduces the problem.

Cheers,
-Paul