https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64537
kugan at gcc dot gnu.org changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |kugan at gcc dot gnu.org --- Comment #1 from kugan at gcc dot gnu.org --- According to AAPCS64 (http://infocenter.arm.com/help/topic/com.arm.doc.ihi0055c/IHI0055C_beta_aapcs64.pdf), the unused parm register bits have "unspecified value".So I think it is needede.