[Bug rtl-optimization/93565] [9/10 regression] Combine duplicates instructions

[segher at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93565

--- Comment #11 from Segher Boessenkool <segher at gcc dot gnu.org> ---
(The original problem I have an idea for -- don't generate a parallel of
two SETs with equal SET_SRC -- but that doesn't handle the new case).