[Bug rtl-optimization/122215] Nondeterminism in ra on riscv32

[law at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122215

--- Comment #11 from Jeffrey A. Law <law at gcc dot gnu.org> ---
Been in meetings all day, but I think this is likely latent on the trunk.  I
can trigger the valgrind warning on the trunk in the same spot.  Essentially
we're getting back a value for hregno that is out of range for the costs array.
 The case where it's happening?  Register "s1".