[llvm-branch-commits] [llvm] release/18.x: [DAGCombiner] In mergeTruncStore, make sure we aren't storing shifted in bits. (#90939) (PR #91038)

[Simon Pilgrim via llvm-branch-commits]

RKSimon wrote:

> > @AtariDreams I've noticed you've filed a lot of backport requests.  How are you choosing which fixes to backport? Is there a specific use case you care about?
> 
> There a particular LLVM miscompile bug in WebKit I'm trying to figure out. It's been there since 2019. Backports is literally just avoiding miscompilations

@AtariDreams Has the bug disappeared in llvm trunk and you think a recent commit has fixed/hidden it? Has this bug been reported either to WebKit or LLVM that we can track please? Have you been able to confirm if its a llvm bug or UB in WebKit?

https://github.com/llvm/llvm-project/pull/91038