Re: [PATCH 1/2] arm64: bpf: add 'store immediate' instruction

[Shi, Yang]

On 11/11/2015 4:39 AM, Will Deacon wrote:
> On Wed, Nov 11, 2015 at 12:12:56PM +0000, Will Deacon wrote:
> > On Tue, Nov 10, 2015 at 06:45:39PM -0800, Z Lim wrote:
> > > On Tue, Nov 10, 2015 at 2:41 PM, Yang Shi <yang.shi@xxxxxxxxxx> wrote:
> > > > aarch64 doesn't have native store immediate instruction, such operation
> > >
> > > Actually, aarch64 does have "STR (immediate)". For arm64 JIT, we can
> > > consider using it as an optimization.
> >
> > Yes, I'd definitely like to see that in preference to moving via a
> > temporary register.
>
> Wait a second, we're both talking rubbish here :) The STR (immediate)
> form is referring to the addressing mode, whereas this patch wants to
> store an immediate value to memory, which does need moving to a register
> first.

Yes, the immediate means immediate offset for addressing index. Doesn't 
mean to store immediate to memory.

I don't think any load-store architecture has store immediate instruction.

Thanks,
Yang

> So the original patch is fine.
>
> Will

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/