Re: [PATCH 09/15] irq: arm: perform irqentry in entry code

Marc Zyngier
2021-12-01T07:56:36Z

On 2021-11-30 08:49, Vladimir Murzin wrote:

> One month and a week later...
>
> I observe that in terms of performance
>
> MRS r0, ipsr
>
> is equivalent to readl_relaxed(BASEADDR_V7M_SCB + V7M_SCB_ICSR)
>
> MOV.W r3, #3758153728
> LDR.W r0, [r3, #3332]
>
> Old compilers can produce less performant sequence like
>
> LDR r3,0xbcc0
> ADD.W r3,r3,#0xaf00
> LDR r0,[r3,#0]
>
> So, what would be your preference?

If there is no significant overhead to reading the MMIO register
and that you see a benefit in enabling COMPILE_TEST, then this
probably is the way to go.

Thanks,

M.
--
Jazz is not dead. It just smells funny...