[llvm] [LV] Check isPredInst instead of isScalarWithPred in uniform analysis. (PR #98892)

[via llvm-commits]

https://github.com/ayalz commented:

Does this suggest that isScalarWithPredication misses some candidates, namely isPredicatedInst()'s considered - and now turned down - by addToWorklistIfAllowed()? There may be a phase ordering issue in how scalars, uniforms, and predicated instructions are classified.

Adding some thoughts inline.

https://github.com/llvm/llvm-project/pull/98892