[llvm] [InstCombine] Fold `(trunc X)` into `X & Mask` inside `decomposeBitTestICmp` (PR #171195)

[Nikita Popov via llvm-commits]

nikic wrote:

> It looks like my changes affected a lot of tests. What is the protocol for determining whether these changes are regressions or not?

Regenerate the failing tests (you can use something like `build/bin/llvm-lit --update-tests llvm/test/Transforms/InstCombine`) and look at the diffs. (Feel free to push the changes.)


https://github.com/llvm/llvm-project/pull/171195