Trying to create a regression test for #20261

[Alexis Praga]

Hi,

As a intermediate beginner in Haskell, I want to try to tackle a small
issue for contributing to GHC.

I've looked into https://gitlab.haskell.org/ghc/ghc/-/issues/20261, but
it's not clear how to integrate a running time in a regression test.

>From what I understand, regression tests should be compared against
sucess/failure or a given output.
Should there be a hard-coded limit ? If that's the case, how could I
create such a test ?  I could not find a similar test in the source
code.

Any help is appreciated, thanks !

-- 
Alexis Praga