[Bug rtl-optimization/66420] valgrind error in improve_allocation

["vmakarov at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66420

--- Comment #2 from Vladimir Makarov <vmakarov at gcc dot gnu.org> ---
  I reproduced the problem with --eanble-checking=valgrind.  The valgrind
message refers for 

      if ((hregno = ALLOCNO_HARD_REGNO (a)) < 0)
        base_cost = ALLOCNO_UPDATED_MEMORY_COST (a);

  I checked all ALL_ALLOCNO_HARD_REGNO in gdb (the test is not big) and I see
that hard regnos are always setup before their usage.

  I also built the same GCC modifying Makefile the same way but *without*
--eanble-checking=valgrind and then used valgrind directly.  I have no valgrind
messages.

  So I don't know is it IRA, GCC in whole, or valgrind problem.  Probably, it
is not an IRA problem.