[cfe-dev] mpfr 3.1.0 vs clang 3.0svn

Jack Howarth howarth at bromo.med.uc.edu
Tue Oct 11 17:26:30 PDT 2011

On Tue, Oct 11, 2011 at 05:11:06PM -0700, Eric Christopher wrote:
> On Oct 11, 2011, at 5:07 PM, Jack Howarth wrote:
> > On Tue, Oct 11, 2011 at 04:52:37PM -0700, Eric Christopher wrote:
> >> 
> >> On Oct 11, 2011, at 7:48 AM, Jack Howarth wrote:
> >> 
> >>>  Another data point on this problem. Using current llvm/dragonegg svn, I can compile libmpfr 3.1.0
> >>> using FSF gcc 4.6.2svn and the dragonegg plugin without any testsuite failures in libmpfr. Thus
> >>> it seems unlikely that the issue is in llvm but rather a problem introduced in clang itself.
> >>>      Jack
> >>> ps Interestingly, I can even compile libmpfr using llvm/dragonegg svn with the flags
> >>> -msse4 -fplugin-arg-dragonegg-enable-gcc-optzns to fully vectorize the code without
> >>> any failures in the libmpfr test suite.
> >> 
> >> As we discussed it's likely a problem with TLS support in clang. I'm uncertain what the problem is, but I'll see if any of the TLS support tests I've got here have randomly started failing.
> >> 
> >> -eric
> > 
> > Eric,
> >   I doubt that would work as I can reproduce the problem with llvm.org's clang 2.9 release using Xcode 4.1.1's
> > cctools.
> I don't know what you mean here? That said, I'd need more information to try to debug anything.

   From your comment above, "I'll see if any of the TLS support tests I've got here have randomly started failing.", I assumed
that you thought this was recent breakage in clang. My point was that I can reproduce this TLS breakage in MPFR 3.1.10 when
built with the fink llvm29 package (which is the llvm.org clang 2.9 release) under Xcode 4.1. This suggests that the problem
has existed as far back as clang 2.9 and is not recent breakage.

> > I suspect we will shortly have a load of additional examples for you as fink 10.7 builds with the Xcode's
> > clang. Once Xcode 4.2 is released, every fink package which supports TLS will suddenly start to use it new builds.
> >                 Jack
> > ps Is there a clang flag to disable the TLS support (short of resorting to -mmacosx-version-min=10.6)?
> Nope, but it could be added.
> -eric

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