From: "Paul Edwards" <mutazilah@gmail.com>
To: "Ulrich Weigand" <Ulrich.Weigand@de.ibm.com>
Cc: <gcc@gcc.gnu.org>, "Ulrich Weigand" <uweigand@de.ibm.com>
Subject: Re: s390 port
Date: Fri, 3 Sep 2021 22:38:36 +1000 [thread overview]
Message-ID: <0A22522993EB4341AFA02779328F247D@DESKTOP0OKG1VA> (raw)
In-Reply-To: <OFD715CBA8.348BA26E-ONC1258745.0041E541-C1258745.00430622@ibm.com>
>> > Also, the compiler
>> > will assume the base + index (+ displacement) arithmetic
>> > will operate in 32 bits -- I'm pretty sure this is
>> > actually the root cause of your "negative index" problem.
>> Where is this logic please? Can I do a #if 0 or similar
>> to disable it?
> This is not in one single place, but spread throughout the
> compiler, both common code and back-end. I do not think it will
> be possible to get the compiler to generate correct code if
> you do not specify the address size correctly.
1. Is there any way to put a constraint on index
registers, to say that a particular machine can
only index in the range of –512 to +512 or some
other arbitrary set? If so, I can do 0 to 2 GiB.
2. Is there a way of saying a machine doesn’t
support indexing at all?
>> > If you want to go for an "x32" like mode, I think this
>> > is wrong approach. The right approach would be to
>> > start from "-m64", and simply modify the pointer size
>> > to be 32 bits.
>> > This would work by setting POINTER_SIZE to 32, while
>> > leaving everything else like for -m64.
>
>> That will generate 64-bit z/Arch instructions.
>> I wish to generate ESA/390 instructions.
> Why? AMODE64 exists only in z/Arch, so of course there
> will be z/Arch instructions available ...
For the same reason people constructed Babbage’s
invention, I wish to demonstrate the minor changes
that would have been required to the S/360 so that
we would never have arrived at a 31-bit black hole,
and we could have in fact had the perfect 32-bit
machine. Almost identical to the 31-bit machine.
A S/360+, a S/370+ and a S/390+.
>> > We've thought about implementing this mode for Linux,
>> > but decided not to do it, since it would only provide
>> > marginal performance improvements, and has the drawback
>> > of being another new ABI that would be incompatible to
>> > the whole existing software ecosystem.
>> Shouldn’t the end user be able to decide this
>> for themselves?
> It's open source, of course everybode can decide what they
> want to work on themselves. But we decide what we spend
> our own time on based on we think is useful ...
Sure.
>> No-one at all is interested in 32-bit mainframes?
> Not any more, at least not in Linux. Linux is pretty much
> 64-bit only at this point.
I think z/OS is pretty much still 31-bit only,
as far as apps are concerned, right? I’d like to
bump that up to 32-bit.
BFN. Paul.
next prev parent reply other threads:[~2021-09-03 12:38 UTC|newest]
Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-06-05 12:45 i370 port Paul Edwards
2009-06-05 14:33 ` Joseph S. Myers
2009-06-05 14:57 ` Paul Edwards
2009-06-05 15:03 ` Joseph S. Myers
2009-06-05 15:24 ` Paul Edwards
2009-06-05 15:47 ` Joseph S. Myers
2009-09-11 17:35 ` i370 port - in search of hooks Paul Edwards
2017-03-31 10:34 ` i370 port Paul Edwards
2009-09-12 12:41 ` Paul Edwards
2009-06-05 15:21 ` Ulrich Weigand
2009-06-05 15:39 ` Paul Edwards
2009-06-05 15:49 ` Daniel Jacobowitz
2009-06-05 15:57 ` Paul Edwards
2009-06-05 20:20 ` Joseph S. Myers
2009-06-05 20:45 ` Paul Edwards
2009-06-06 15:00 ` Paul Edwards
2009-06-15 17:46 ` Ulrich Weigand
2009-06-19 0:06 ` Paul Edwards
2009-06-19 12:28 ` Ulrich Weigand
2009-07-18 11:28 ` Paul Edwards
2009-07-20 14:27 ` Ulrich Weigand
2009-08-08 12:04 ` Paul Edwards
2009-08-10 21:25 ` Ulrich Weigand
2009-08-11 0:34 ` Paul Edwards
2009-08-11 15:21 ` Ulrich Weigand
2009-08-12 11:52 ` Paul Edwards
2009-08-12 15:27 ` Paolo Bonzini
2009-08-12 16:35 ` Ulrich Weigand
2009-08-12 17:27 ` Paul Edwards
2009-08-12 17:56 ` Paolo Bonzini
2009-08-12 19:46 ` Ulrich Weigand
2009-08-12 20:31 ` Paul Edwards
2009-08-19 12:07 ` Paul Edwards
2009-08-19 12:27 ` Paolo Bonzini
2009-08-20 12:49 ` Paul Edwards
2009-08-20 22:48 ` Ulrich Weigand
2009-08-21 2:37 ` Paul Edwards
2009-08-21 16:46 ` Ulrich Weigand
2009-06-05 15:44 ` Joseph S. Myers
2009-06-05 15:52 ` Paul Edwards
2009-09-08 15:55 ` Paul Edwards
2009-09-14 15:32 ` Ulrich Weigand
2021-09-02 8:15 ` s390 port Paul Edwards
2021-09-02 14:34 ` Ulrich Weigand
2021-09-02 14:50 ` Paul Edwards
2021-09-02 14:53 ` Ulrich Weigand
2021-09-02 15:01 ` Paul Edwards
2021-09-02 15:13 ` Ulrich Weigand
2021-09-02 15:26 ` Paul Edwards
2021-09-02 19:46 ` Ulrich Weigand
2021-09-02 20:05 ` Paul Edwards
2021-09-02 20:16 ` Andreas Schwab
2021-09-03 11:18 ` Ulrich Weigand
2021-09-03 11:35 ` Paul Edwards
2021-09-03 12:12 ` Ulrich Weigand
2021-09-03 12:38 ` Paul Edwards [this message]
2021-09-03 12:53 ` Jakub Jelinek
2021-09-03 13:12 ` Paul Edwards
2022-12-20 4:27 ` Paul Edwards
2021-09-02 10:56 Paul Edwards
2021-09-06 22:44 Build gcc question Gary Oblock
2021-09-07 7:21 ` s390 port Joe Monk
2021-09-08 3:46 ` Paul Edwards
2021-09-30 0:08 Paul Edwards
2021-09-30 0:59 ` Joe Monk
2021-09-30 21:39 Paul Edwards
2023-01-28 18:51 Paul Edwards
2023-01-29 13:08 ` Joe Monk
2023-01-29 14:30 ` Paul Edwards
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