[Bug rtl-optimization/78664] LRA must honor REG_ALLOC_ORDER to pick reload registers

[vmakarov at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78664

--- Comment #2 from Vladimir Makarov <vmakarov at gcc dot gnu.org> ---
During register assignment subpass LRA processes hard regs from
ira_class_hard_regs.  Under the same conditions (e.g. costs), LRA chooses regs
processed first.

ira_class_hard_regs contains regs according REG_ALLOC_ORDER.

LRA has code for balanced use of hard regs (controlled by hook
register_usage_leveling_p).  But now by default it is switched off.  Probably
the issue occurred when the code was switched on. 

To be sure I tried the test case and I was not able to reproduce the problem.

So I think the problem has been solved.