From: David Laight <David.Laight@ACULAB.COM>
To: 'Segher Boessenkool' <segher@kernel.crashing.org>,
"Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>
Cc: "ravi.bangoria@linux.ibm.com" <ravi.bangoria@linux.ibm.com>,
"ananth@linux.ibm.com" <ananth@linux.ibm.com>,
"jniethe5@gmail.com" <jniethe5@gmail.com>,
"paulus@samba.org" <paulus@samba.org>,
Sandipan Das <sandipan@linux.ibm.com>,
"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
"dja@axtens.net" <dja@axtens.net>
Subject: RE: [PATCH v2 1/3] powerpc: sstep: Fix load and update emulation
Date: Thu, 4 Feb 2021 10:29:00 +0000 [thread overview]
Message-ID: <10d7cf245bb744739de063d452065e94@AcuMS.aculab.com> (raw)
In-Reply-To: <20210203211732.GD30983@gate.crashing.org>
From: Segher Boessenkool
> Sent: 03 February 2021 21:18
...
> Power9 does:
>
> Load with Update Instructions (RA = 0)
> EA is placed into R0.
Does that change the value of 0?
Rather reminds me of some 1960s era systems that had the small integers
at fixed (global) addresses.
FORTRAN always passes by reference, pass 0 and the address of the global
zero location was passed, the called function could change 0 to 1 for
the entire computer!
> Load with Update Instructions (RA = RT)
> The storage operand addressed by EA is accessed. The displacement
> field is added to the data returned by the load and placed into RT.
Shame that isn't standard - could be used to optimise some code.
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
prev parent reply other threads:[~2021-02-04 10:31 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-03 6:38 [PATCH v2 1/3] powerpc: sstep: Fix load and update emulation Sandipan Das
2021-02-03 6:38 ` [PATCH v2 2/3] powerpc: sstep: Fix store " Sandipan Das
2021-02-03 6:38 ` [PATCH v2 3/3] powerpc: sstep: Fix darn emulation Sandipan Das
2021-02-03 9:49 ` [PATCH v2 1/3] powerpc: sstep: Fix load and update emulation Naveen N. Rao
2021-02-03 10:35 ` Sandipan Das
2021-02-03 11:37 ` Sandipan Das
2021-02-04 0:53 ` Michael Ellerman
2021-02-03 21:17 ` Segher Boessenkool
2021-02-04 8:27 ` Naveen N. Rao
2021-03-02 2:37 ` Segher Boessenkool
2021-03-03 16:31 ` Naveen N. Rao
2021-03-04 15:45 ` Segher Boessenkool
2021-03-04 1:06 ` Naveen N. Rao
2021-02-04 10:29 ` David Laight [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=10d7cf245bb744739de063d452065e94@AcuMS.aculab.com \
--to=david.laight@aculab.com \
--cc=ananth@linux.ibm.com \
--cc=dja@axtens.net \
--cc=jniethe5@gmail.com \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=naveen.n.rao@linux.vnet.ibm.com \
--cc=paulus@samba.org \
--cc=ravi.bangoria@linux.ibm.com \
--cc=sandipan@linux.ibm.com \
--cc=segher@kernel.crashing.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).