[Bug rtl-optimization/64537] Aarch64 redundant sxth instruction gets generated

[kugan at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64537

kugan at gcc dot gnu.org changed:

           What    |Removed                     |Added
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                 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.