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Re: [Qemu-arm] [Qemu-devel] [PATCH 5/7] target-arm: Add isread parameter
From: |
Peter Maydell |
Subject: |
Re: [Qemu-arm] [Qemu-devel] [PATCH 5/7] target-arm: Add isread parameter to CPAccessFns |
Date: |
Fri, 5 Feb 2016 16:27:14 +0000 |
On 5 February 2016 at 16:17, Alex Bennée <address@hidden> wrote:
>
> Peter Maydell <address@hidden> writes:
>> I haven't measured, no, but since there are only 3 arguments the
>> third argument is going to be in a register on any host architecture
>> we care about, which means the overhead is just going to be a single
>> "load constant 0 or 1 into register before the call". I think that's
>> going to be lost in the noise compared to actually having to make
>> the function call at all, the work the function call does, and then
>> the second function call later to do the read or write.
>
> I was thinking of knock on effects on spilling other registers in the
> TCG code. I guess this depends on how complex the code is around system
> register access.
The register in question is going to be caller-saves anyway, so no
effect on spilling in the TCG code I think.
thanks
-- PMM
- [Qemu-arm] [PATCH 2/7] target-arm: Implement MDCR_EL3 and SDCR, (continued)
Re: [Qemu-arm] [PATCH 5/7] target-arm: Add isread parameter to CPAccessFns, Edgar E. Iglesias, 2016/02/06
Re: [Qemu-arm] [Qemu-devel] [PATCH 5/7] target-arm: Add isread parameter to CPAccessFns, Sergey Fedorov, 2016/02/06
[Qemu-arm] [PATCH 6/7] target-arm: Implement NSACR trapping behaviour, Peter Maydell, 2016/02/03
[Qemu-arm] [PATCH 1/7] target-arm: Fix typo in comment in arm_is_secure_below_el3(), Peter Maydell, 2016/02/03