Standard way to supply hints to branches

[Quirin Schroll]

On Friday, 13 September 2024 at 11:18:59 UTC, Zoadian wrote:
> On Friday, 13 September 2024 at 10:57:56 UTC, Quirin Schroll 
> wrote:
>> On Friday, 13 September 2024 at 10:26:48 UTC, Richard (Rikki) 
>> Andrew Cattermole wrote:
>> Let’s say you have a big switch in a hot loop. You profiled 
>> and now the data tells you how likely each branch was. What 
>> would you prefer? Reordering the branches by likelihood, 
>> leading to a diff that’s basically impossible to understand or 
>> even vet that it’s just a reordering, or the pure addition of 
>> likelihood annotations, for which in the diff it’s absolutely 
>> clear nothing else changes. And if there’s a fallthrough, you 
>> have to jump to the right case now.
>
> i'd prefer handing the compiler a profile log, and the compiler 
> just optimizing based on that file without the need to do any 
> annotations by hand.

Sure, that’s way easier for devs. You just can’t do that if you 
also want to distribute the code with the branch hints.