From: Richard Henderson <rth@twiddle.net>
To: David Miller <davem@davemloft.net>
Cc: libffi-discuss@sourceware.org
Subject: Re: [PATCH 3/8] sparc: Rewrite everything
Date: Wed, 29 Oct 2014 20:44:00 -0000 [thread overview]
Message-ID: <545151B5.6040103@twiddle.net> (raw)
In-Reply-To: <20141029.161058.1101864756322678040.davem@davemloft.net>
On 10/29/2014 01:10 PM, David Miller wrote:
> From: Richard Henderson <rth@twiddle.net>
> Date: Wed, 29 Oct 2014 13:01:45 -0700
>
>> On 10/29/2014 11:10 AM, David Miller wrote:
>>> Maybe I'm missing something?
>>
>> The two limits are in fact different. In gcc, see sparc_return_in_memory and
>> sparc_pass_by_reference.
>
> My bad, thanks for clarifying.
>
> That's the only thing that caught my eye. I think for most v9 chips a
> 'return' is slightly more expensive than a 'ret/restore'. 'return' is
> good for saving an instruction when you can put something in that
> delay slot, but if you can't then you might as well do 'ret/restore'.
Ah right, thanks.
The one other microarchitecture question I had was wrt call/ret paring.
I was assuming that, for predition purposes, "ret" vs "jmp" must be based on
the register used -- %i7 or %o7. Thus my call ... jmp %o7+const hopefully
keeps any call/return prediction stack in sync?
r~
next prev parent reply other threads:[~2014-10-29 20:44 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-28 19:46 [PATCH 0/8] Go closures for Sparc Richard Henderson
2014-10-28 19:46 ` [PATCH 6/8] sparc: Add support for complex types Richard Henderson
2014-10-28 19:46 ` [PATCH 7/8] sparc: Add support for Go closures Richard Henderson
2014-10-28 19:46 ` [PATCH 5/8] sparc: Handle more cases of structure return directly Richard Henderson
2014-10-28 19:46 ` [PATCH 8/8] sparc: Re-add abi compliant structure support Richard Henderson
2014-10-28 19:46 ` [PATCH 2/8] sparc: Tidy up symbols Richard Henderson
2014-10-28 19:46 ` [PATCH 4/8] sparc: Preprocess float point struct return Richard Henderson
2014-10-28 19:46 ` [PATCH 1/8] sparc: Eliminate long double ifdefs Richard Henderson
2014-10-28 19:46 ` [PATCH 3/8] sparc: Rewrite everything Richard Henderson
2014-10-29 18:10 ` David Miller
2014-10-29 20:01 ` Richard Henderson
2014-10-29 20:11 ` David Miller
2014-10-29 20:44 ` Richard Henderson [this message]
2014-10-30 4:52 ` David Miller
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