[Bug rtl-optimization/82192] [5/6/7/8 Regression] gcc produces incorrect code with -O2 and bit-field

[segher at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82192

--- Comment #12 from Segher Boessenkool <segher at gcc dot gnu.org> ---
As far as I know this is undefined; combine should avoid making such
out-of-range patterns (unless the existing insns are already like that,
it will happily make even bigger garbage then).