Re: [PATCH] powerpc: Optimise the 64bit optimised __clear_user

On Thu, 2012-06-07 at 16:12 +1000, Michael Neuling wrote:

Michael Ellerman [off-list ref] wrote:

quoted

On Thu, 2012-06-07 at 16:05 +1000, Michael Neuling wrote:

quoted

Benjamin Herrenschmidt [off-list ref] wrote:

quoted

On Wed, 2012-06-06 at 18:40 +0200, Segher Boessenkool wrote:

quoted

quoted

+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) 

#define R(x)	x

#define R(x)	(x) 

quoted

#define PPC_POPCNTB(R(3), R(3))

Maybe, looks pretty gross but you're the maintainer! :-)

No I am not!


I agree it's fairly gross. But I'll take gross and correct over ungross
and buggy.

cheers