[llvm] [DAGCombiner] Freeze maybe poison operands when folding select to logic (PR #84924)

[Björn Pettersson via llvm-commits]

bjope wrote:

> > ```
> > * Would it help if I split it up in one patch for foldBoolSelectToLogic and another one for foldVSelectToSignBitSplatMask?
> > ```
> 
> Probably, especially if the latter has less test regressions?
> 
> > ```
> > * Should I pre-commit [e57c143](https://github.com/llvm/llvm-project/commit/e57c1432d57227969a9d6a4f19fd5469a39a4a14) (not sure if there would be any motivating test cases for that one if doing it as a pre-commit, that is why I added it as a second patch in the patch-stack here).
> > ```
> 
> Yes, please. If there are no test changes as-is, you could add a test with explicit freeze.

Thanks for the advice! I'll split this patch in smaller pieces (at least breaking out the "Push freeze through SETCC and SELECT_CC" part).

https://github.com/llvm/llvm-project/pull/84924