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Message-ID: <20131202074806.GG24286@brightrain.aerifal.cx>
Date: Mon, 2 Dec 2013 02:48:06 -0500
From: Rich Felker <dalias@...ifal.cx>
To: musl@...ts.openwall.com
Subject: Re: Clang powerpc pthread_arch.h patch.
On Sun, Nov 24, 2013 at 04:46:48PM -0600, Richard Pennington wrote:
> On 11/24/2013 04:31 PM, Rich Felker wrote:
> >On Sun, Nov 24, 2013 at 01:23:44PM -0600, Richard Pennington wrote:
> >>I had a problem with clang and __pthread_self() on the powerpc. This
> >>is the patch I applied to work around it.
> >>
> >>Index: pthread_arch.h
> >>===================================================================
> >>--- pthread_arch.h (revision 3604)
> >>+++ pthread_arch.h (working copy)
> >>@@ -1,6 +1,11 @@
> >> static inline struct pthread *__pthread_self()
> >> {
> >>+#ifdef __clang__
> >>+ char *tp;
> >>+ __asm__ __volatile__ ("mr %0, 2" : "=r" (tp) : : "2" );
> >>+#else
> >Why is "2" in the clobberlist? It's just read, not written. In
> >principle there should be some way to indicate that the asm has hidden
> >state it reads so that it couldn't be reordered before the initial asm
> >call that initializes the register, but that would be massive
> >reordering that's not likely to happen anyway. I'm not sure what the
> >right way to encode this as a constraint is...
> >
> >Rich
> Hi Rich,
>
> You're right about the clobber list. Not that it matters much in
> this case I think.
Committed a fix based on your patch; let me know if you still have
problems with it.
Rich
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