From: Segher Boessenkool <segher@kernel.crashing.org>
To: Nicholas Piggin <npiggin@gmail.com>
Cc: linuxppc-dev@lists.ozlabs.org,
Adhemerval Zanella <adhemerval.zanella@linaro.org>
Subject: Re: powerpc Linux scv support and scv system call ABI proposal
Date: Wed, 29 Jan 2020 07:20:19 -0600 [thread overview]
Message-ID: <20200129132019.GL22482@gate.crashing.org> (raw)
In-Reply-To: <1580273424.ea818exa2c.astroid@bobo.none>
On Wed, Jan 29, 2020 at 02:58:44PM +1000, Nicholas Piggin wrote:
> Adhemerval Zanella's on January 29, 2020 3:26 am:
> > __asm__ __volatile__ \
> > ("sc\n\t" \
> > "bns+ 1f\n\t" \
> > "neg %1, %1\n\t" \
> > "1:\n\t" \
> True, but the taken branch would be a 1 cycle bubble in fetch. Could
> avoid that by branching out of line then back for the error case. But
> mfocrf is fine (only sources one register), that's what should be used
> here I think.
neg %9,%1 ; isel %1,%9,%1,so
> That probably makes the performance argument for avoiding CR[SO] for
> error return indication less significant. Commonality with other
> architectures is probably the bigger reason for it.
Yes, and to have the syscall calling convention closer to the normal
function calling convention would be good, too.
Segher
next prev parent reply other threads:[~2020-01-29 13:24 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-28 10:50 powerpc Linux scv support and scv system call ABI proposal Nicholas Piggin
2020-01-28 13:09 ` Florian Weimer
2020-01-28 14:05 ` Nicholas Piggin
2020-01-28 15:40 ` Segher Boessenkool
2020-01-28 16:04 ` Florian Weimer
2020-01-28 20:01 ` Segher Boessenkool
2020-01-29 16:19 ` Florian Weimer
2020-01-29 16:29 ` Segher Boessenkool
2020-01-29 17:02 ` Florian Weimer
2020-01-29 17:51 ` Segher Boessenkool
2020-01-30 10:42 ` Florian Weimer
2020-01-30 11:25 ` Segher Boessenkool
2020-01-30 12:03 ` Florian Weimer
2020-01-30 13:50 ` Segher Boessenkool
2020-01-30 17:04 ` Adhemerval Zanella
2020-01-30 21:41 ` Segher Boessenkool
2020-01-31 11:30 ` Adhemerval Zanella
2020-01-31 11:55 ` Segher Boessenkool
2020-01-28 15:58 ` Florian Weimer
2020-01-29 4:41 ` Nicholas Piggin
2020-01-28 17:26 ` Adhemerval Zanella
2020-01-29 4:58 ` Nicholas Piggin
2020-01-29 13:20 ` Segher Boessenkool [this message]
2020-01-29 15:51 ` Tulio Magno Quites Machado Filho
2020-02-19 11:03 ` Nicholas Piggin
2020-01-28 22:14 ` Joseph Myers
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