[PATCH] powerpc: Optimise the 64bit optimised __clear_user
Michael Neuling
mikey at neuling.org
Thu Jun 7 16:05:04 EST 2012
Benjamin Herrenschmidt <benh at kernel.crashing.org> wrote:
> On Wed, 2012-06-06 at 18:40 +0200, Segher Boessenkool wrote:
> > > +err1; dcbz r0,r3
> >
> > There is no such instruction, you probably meant "dcbz 0,r3"?
>
> This reminds me... what would happen if we changed all our
>
> #define r0 0
> #define r1 1
>
> etc... to:
>
> #define r0 %r0
> #define r1 %r1
>
> ?
>
> I'm thinking it might help catch that sort of nasties (and some of them
> can be really nasty, such as inverting mfspr/mtspr arguments, or vs ori,
> etc... ). I'm sure we'd have a problem with a few macros & inline
> constructs but nothing we can't fix..
One problem with this is when we construct the instructions, like using
anything from ppc-opcode.h. eg. using PPC_POPCNTB would need to go from:
PPC_POPCNTB(r3,r3)
to:
PPC_POPCNTB(3,3)
Which is less readable IMHO.
Mikey
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