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Re: [XenPPC] [xenppc-unstable] [ppc] Turn on Save and Restore of VMX reg

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Subject: Re: [XenPPC] [xenppc-unstable] [ppc] Turn on Save and Restore of VMX registers
From: Segher Boessenkool <segher@xxxxxxxxxxxxxxxxxxx>
Date: Wed, 14 Jun 2006 01:09:32 +0200
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 /* So you might think that we could use the VRSAVE register to
  * streamline this but "If this [VRSAVE] approach is taken it must be
  * applied rigorously".

I have no idea what this comment is supposed to mean.  If you use
VRSAVE to select which regs to save and which not, it often hurts
to do that selection per register; but doing it per block of four
stil pays off.  (About equal to blocks of eight in my profiling,
btw.  Do you own profiling!)

        /* r0 as the second operand is considered 0 */

NOT AT ALL.  Binary pattern 0b00000 for RA means literal 0 instead
of GPR0, sure.  And the assembler you use just uses CCCP to
translate "r0" into a literal 0.  But some other assemblers
do not.  So please just write "0" when you mean "0".

-       addi r0,r3,CT_VR0 ;     stvxl   vr0,r0,r0

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