[PATCH][ARM] Discourage use of NEON on Cortex-A8

Richard Earnshaw rearnsha@arm.com
Mon Mar 14 18:18:00 GMT 2011


On Mon, 2011-03-14 at 17:55 +0000, Andrew Stubbs wrote:
> On 14/03/11 17:10, Richard Earnshaw wrote:
> > Finally, alternatives from an insn are normally selected left-to-right
> > from those available in a pattern, all other things being equal.  So
> > really the A8-only alternative should come after the core registers
> > alternatives if its less preferable.
> 
> OK, I can do that, but I'm not exactly sure how far to the right you 
> want them moved?
> 
> Do you want the onlya8 alternatives moved the the right of all 
> alternatives without a '?' modifier (so, changing only iordi3_neon and 
> anddi3_neon)? Or do you mean moving it all the way to the right hand end?
> 
> Or something completely different?
> 
> Andrew
> 
So taking the current adddi3 pattern we have alternatives (in order of
preference): not-a8, only-a8, core-regs, core-regs.

I think the order should be: not-a8, core-regs, core-regs, only-a8.

R.




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