Re: [Qemu-devel] [PATCH v2 0/6] ARM: AREG0 conversion

[Blue Swirl]

On Mon, Mar 26, 2012 at 13:05, Paul Brook <address@hidden> wrote:
>> On 24 March 2012 18:58, Blue Swirl <address@hidden> wrote:
>> > v2: fix patch 1, tweak patch 2 and rebase to master.
>> >
>> > URL     git://repo.or.cz/qemu/blueswirl.git
>> >        http://repo.or.cz/r/qemu/blueswirl.git
>> >
>> > Blue Swirl (6):
>> >  arm: move neon_tbl to neon_helper.c
>> >  arm: move saturating arithmetic to helper.c
>> >  arm: move other arithmetic to helper.c
>> >  arm: move cpsr and banked register access to helper.c
>> >  arm: move exception and wfi helpers to helper.c
>> >  arm: move load and store helpers, switch to AREG0 free mode
>>
>> The patches themselves look OK, but do we really want to take
>> a 5% performance hit for this cleanup?
>
> I have a similar concern.  I'd like to at least have some idea where this
> slowdown is coming from.

At least stack protector is protecting more code than before (for
example TLB miss handler), but could overhead from that amount to 5%?

Otherwise there should be just a few extra register moves here and
there, that should be cheap on modern processors.