[llvm] Reenable JumpTableToSwitch pass by default (PR #83229)

[Florian Hahn via llvm-commits]

fhahn wrote:

> Remembering to rebuild this time, I tried a few thresholds:
> 
> * 5, takes at least half an hour on a single file, killed it before it could finish since that's going to break the 20 minute timeout anyway.
> * 4, same.
> * 3, longest time on a single file is around 10 minutes and the build completes in a reasonable time.
> 
> Not sure that a jump table size of 3 even worth looking at, but it's what tames the build.

How do the build times change relative to without the pass being enabled, i.e. what does the pass contribute to the overall compile-time.

> It does not seem like a good idea to introduce something that even high end hardware struggles with, even if Flang's design might not be ideal.

yeah, I don't think we should enable something by default that causes excessive compile-time increases for valid input.

https://github.com/llvm/llvm-project/pull/83229