[AggressiveInstCombine] convert a chain of 'and-shift' bits into masked compare
This is a follow-up to D45986. As suggested there, we should match the "all-bits-set"
pattern in addition to "any-bits-set".
This was a little more complicated than I thought it would be initially because the
"and 1" instruction can be anywhere in the chain. Hopefully, the code comments make
that logic understandable, but if you see a way to simplify or improve that, it's
This transforms patterns that emerge from bitfield tests as seen in PR37098:
Differential Revision: https://reviews.llvm.org/D46649