From: Segher Boessenkool <segher@kernel.crashing.org>
To: Florian Weimer <fweimer@redhat.com>
Cc: libc-alpha@sourceware.org,
Tulio Magno Quites Machado Filho <tuliom@linux.ibm.com>,
linuxppc-dev@lists.ozlabs.org,
Nicholas Piggin <npiggin@gmail.com>
Subject: Re: powerpc Linux scv support and scv system call ABI proposal
Date: Wed, 29 Jan 2020 10:29:47 -0600 [thread overview]
Message-ID: <20200129162947.GN22482@gate.crashing.org> (raw)
In-Reply-To: <87wo9a8cc8.fsf@oldenburg2.str.redhat.com>
On Wed, Jan 29, 2020 at 05:19:19PM +0100, Florian Weimer wrote:
> * Segher Boessenkool:
> >> But GCC doesn't expose them as integers to C code, so you can't do much
> >> without them.
> >
> > Sure, it doesn't expose any other registers directly, either.
>
> I can use r0 & 1 with a register variable r0 to check a bit.
That is not reliable, or supported, and it *will* break. This is
explicit for local register asm, and global register asm is
underdefined.
> I don't
> think writing a similar check against a condition register is possible
> today.
That's right. You cannot express CCmode (MODE_CC) values in C at all.
Segher
next prev parent reply other threads:[~2020-01-29 16:32 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-28 10:50 powerpc Linux scv support and scv system call ABI proposal Nicholas Piggin
2020-01-28 13:09 ` Florian Weimer
2020-01-28 14:05 ` Nicholas Piggin
2020-01-28 15:40 ` Segher Boessenkool
2020-01-28 16:04 ` Florian Weimer
2020-01-28 20:01 ` Segher Boessenkool
2020-01-29 16:19 ` Florian Weimer
2020-01-29 16:29 ` Segher Boessenkool [this message]
2020-01-29 17:02 ` Florian Weimer
2020-01-29 17:51 ` Segher Boessenkool
2020-01-30 10:42 ` Florian Weimer
2020-01-30 11:25 ` Segher Boessenkool
2020-01-30 12:03 ` Florian Weimer
2020-01-30 13:50 ` Segher Boessenkool
2020-01-30 17:04 ` Adhemerval Zanella
2020-01-30 21:41 ` Segher Boessenkool
2020-01-31 11:30 ` Adhemerval Zanella
2020-01-31 11:55 ` Segher Boessenkool
2020-01-28 15:58 ` Florian Weimer
2020-01-29 4:41 ` Nicholas Piggin
2020-01-28 17:26 ` Adhemerval Zanella
2020-01-29 4:58 ` Nicholas Piggin
2020-01-29 13:20 ` Segher Boessenkool
2020-01-29 15:51 ` Tulio Magno Quites Machado Filho
2020-02-19 11:03 ` Nicholas Piggin
2020-01-28 22:14 ` Joseph Myers
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