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Enhancement
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Resolution: Fixed
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P4
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17
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b17
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aarch64
HotSpot generates an FMOV from ZR to zero a floating point register:
fmov d0, xzr
This used to be recommended by the Arm ARM, but that advice was removed in revision A.j and subsequent revisions (section C.5.3).
Integer->FP moves may be slow on some cores. Instead the preferred instruction is MOVI with immediate zero:
movi d0, #0x0
Some micro-architectures special-case FMOV from ZR, and on those cores this change will have no effect, but in any case FMOV won't be faster than MOVI.
fmov d0, xzr
This used to be recommended by the Arm ARM, but that advice was removed in revision A.j and subsequent revisions (section C.5.3).
Integer->FP moves may be slow on some cores. Instead the preferred instruction is MOVI with immediate zero:
movi d0, #0x0
Some micro-architectures special-case FMOV from ZR, and on those cores this change will have no effect, but in any case FMOV won't be faster than MOVI.