From: Segher Boessenkool <segher@kernel.crashing.org>
To: Iain Sandoe <iain@sandoe.co.uk>
Cc: "Kewen.Lin" <linkw@linux.ibm.com>, GCC Patches <gcc-patches@gcc.gnu.org>
Subject: Re: [PATCH] rs6000: Rework option -mpowerpc64 handling [PR106680]
Date: Thu, 29 Sep 2022 12:18:58 -0500 [thread overview]
Message-ID: <20220929171858.GZ25951@gate.crashing.org> (raw)
In-Reply-To: <AF38D5F3-E87E-4CCA-B20E-E6BAACF60E02@sandoe.co.uk>
On Thu, Sep 29, 2022 at 12:04:05AM +0100, Iain Sandoe wrote:
> > On 28 Sep 2022, at 22:30, Segher Boessenkool <segher@kernel.crashing.org> wrote:
> > That works on Linux as well. What still does not work is user-mode
> > context switches in 32-bit processes (so setjmp and getcontext stuff).
>
> AFAIU the Darwin impl. it is the same - the user context only contains 32b
> register images.
Huh, I thought Darwin did this properly.
> Since one can only use the feature between function calls,
You still have to preserve the non-volatile GPRs. All 64 bits of it.
> I guess that the
> setjmp/longjmp stuff is not so critical on Darwin***. However, even being able
> to use 64b insns between calls could give a massive win in allowing, for
> example, lock-free 64b atomics.
But that is not how GCC with -mpowerpc64 works: the calling convention
is the usual 32-bit one, but the functions are 64-bit otherwise; it uses
all 64 bits of GPRs everywhere except in function calls.
Segher
next prev parent reply other threads:[~2022-09-29 17:20 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-28 5:30 Kewen.Lin
2022-09-28 6:37 ` Iain Sandoe
2022-09-28 16:18 ` Iain Sandoe
2022-09-28 19:09 ` Iain Sandoe
2022-09-29 5:45 ` Kewen.Lin
2022-09-29 8:16 ` Iain Sandoe
2022-09-29 9:12 ` Kewen.Lin
2022-09-29 16:14 ` Iain Sandoe
2022-09-29 17:04 ` Segher Boessenkool
2022-09-29 18:25 ` Iain Sandoe
2022-09-29 18:37 ` Segher Boessenkool
2022-09-30 9:26 ` Kewen.Lin
2022-09-29 17:11 ` Segher Boessenkool
2022-09-30 12:15 ` Kewen.Lin
2022-10-03 21:15 ` Segher Boessenkool
2022-10-10 2:15 ` Kewen.Lin
2022-10-10 13:58 ` Segher Boessenkool
2022-10-12 8:26 ` Kewen.Lin
2022-09-28 21:30 ` Segher Boessenkool
2022-09-28 23:04 ` Iain Sandoe
2022-09-28 23:16 ` Iain Sandoe
2022-09-29 17:26 ` Segher Boessenkool
2022-09-29 17:18 ` Segher Boessenkool [this message]
2022-09-29 18:33 ` Iain Sandoe
2022-09-29 18:50 ` Segher Boessenkool
2022-09-28 22:04 ` Segher Boessenkool
2022-09-29 6:16 ` Kewen.Lin
2022-09-29 18:56 ` Segher Boessenkool
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