https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63762
--- Comment #2 from Renlin Li <renlin.li at arm dot com> --- r278 is derived from r224 which is a VFP_LO_REGS. find_cost_and_classes assigns r278's class as GENERAL_REGS, and assign it hard_reg 2. Another new pseudo register r290 is created from r278, and assigned to the same hard_register and register class (GENERAL_REGS). The pref_class of r290 is derived from its original reg (r224), which is VFP_LO_REGS In lra during the hard register assignment process, conflict is checked for r302 which is a GENERAL_REGS. r290 is not considered, because of different register classes(reg_pref[290].pref_class == VFP_LO_REGS ). Hard register number 2 is chosen in this case.
