[llvm] [InstSimplify] Handle trunc to i1 in Select with bit test folds. (PR #122944)

[Andreas Jonson via llvm-commits]

andjo403 wrote:

As there is a lot of regressions when adding handling for trunk in foldLogOpOfMaskedICmps I instead added the update of decomposeBitTest in this PR.

Still results in no changes in local run of llvm-opt-benchmark, this can be due to trunc to i1 is not that common yet, but also at least the test bittest_trunc_or is folded to the same with instcombine as this InstSimplify fold.

https://github.com/llvm/llvm-project/pull/122944