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

Will Deacon
2015-11-11T12:39:56Z

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@linaro.org> 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.

So the original patch is fine.

Will