From: Aldy Hernandez <aldyh@redhat.com>
To: Michael Matz <matz@suse.de>
Cc: Richard Guenther <richard.guenther@gmail.com>,
Richard Henderson <rth@redhat.com>,
Jeff Law <law@redhat.com>,
gcc-patches <gcc-patches@gcc.gnu.org>,
Jakub Jelinek <jakub@redhat.com>
Subject: Re: [cxx-mem-model] bitfield tests
Date: Wed, 06 Apr 2011 17:16:00 -0000 [thread overview]
Message-ID: <4D9C9FEA.4000609@redhat.com> (raw)
In-Reply-To: <Pine.LNX.4.64.1104061728420.19760@wotan.suse.de>
On 04/06/11 10:29, Michael Matz wrote:
> Hi,
>
> On Mon, 4 Apr 2011, Aldy Hernandez wrote:
>
>>
>>>> (5) Do we agree that all such cpus use a byte-granular modification mask?
>>
>>> Now, as of (0) I might agree to disregard the original Alpha, but as the
>>> embedded world moves to SMP I'm not sure we can disregard
>>> non-cache coherent NUMA setups or even CPUs without a byte store.
>>
>> As per 5, it doesn't matter if the CPU lacks a byte store, since the
>> cache has a byte-granular modification mask.
>
> If it doesn't have byte stores there's no need for byte-granular
> modification masks :)
I was talking about a CPU with a byte store that is implemented in the
microcode with a wider operation and logical operations that may touch
adjacent fields. If adjacent bytes were touched, the cache would be
updated accordingly, hence the byte-granular modification mask. That's
my understanding anyhow.
next prev parent reply other threads:[~2011-04-06 17:16 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-03-29 17:28 Aldy Hernandez
2011-03-30 10:50 ` Richard Guenther
2011-03-30 14:24 ` Aldy Hernandez
2011-03-30 14:25 ` Richard Guenther
2011-03-30 14:41 ` Aldy Hernandez
2011-03-30 14:43 ` Richard Guenther
2011-03-30 15:13 ` Mike Stump
2011-03-31 14:58 ` Jeff Law
2011-03-31 15:35 ` Richard Guenther
2011-04-01 16:24 ` Richard Henderson
2011-04-01 19:42 ` Andrew Pinski
2011-04-02 7:56 ` Richard Guenther
2011-04-04 12:56 ` Aldy Hernandez
2011-04-04 12:58 ` Aldy Hernandez
2011-04-06 15:29 ` Michael Matz
2011-04-06 17:16 ` Aldy Hernandez [this message]
2011-04-04 18:06 ` Jeff Law
2011-03-30 14:39 ` Michael Matz
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