Messages in this thread | | | Date | Wed, 09 Apr 2008 17:47:21 -0700 | From | "H. Peter Anvin" <> | Subject | Re: [patch 13/17] Immediate Values - x86 Optimization |
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Mathieu Desnoyers wrote: > > Ok. Sorry, it's been a few months since we looked at this. So the =q > opcode lets the compiler choose instructions with or without REX prefix. > We can allow this because > > - We don't need the opcode length in the stop_machine_run() version > - we support variable length opcode in the nmi-safe version > > Am I remembering correctly now ? >
Yes. Both =r and =q allow REX opcodes.
-hpa
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