Unlike instcombine, we currently don't turn and+shift into shift+and.
We probably should, likely unconditionally.
While i'm adding only all-ones (potentially shifted) mask,
this obviously isn't limited to any particular mask pattern:
https://rise4fun.com/Alive/kmX
Related to https://bugs.llvm.org/show_bug.cgi?id=41874
llvm-svn: 360706
Roman Lebedev