[Bug rtl-optimization/89195] [7/8/9 regression] Corrupted stack offset after combine

[segher at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89195

--- Comment #6 from Segher Boessenkool <segher at gcc dot gnu.org> ---
pos should be always non-negative.  pos is the offset (in bits, counted from
the right) in the *field*.