r228253 - [PowerPC] Revert workaround for TLS linker bug

[Bill Schmidt]

On Thu, 2015-02-05 at 18:52 -0600, Bill Schmidt wrote:
> On Wed, 2015-02-04 at 18:30 -0800, Chandler Carruth wrote:
> > 
> > On Wed, Feb 4, 2015 at 5:12 PM, Bill Schmidt
> > <wschmidt at linux.vnet.ibm.com> wrote:
> >         Author: wschmidt
> >         Date: Wed Feb  4 19:12:24 2015
> >         New Revision: 228253
> >         
> >         URL: http://llvm.org/viewvc/llvm-project?rev=228253&view=rev
> >         Log:
> >         [PowerPC] Revert workaround for TLS linker bug
> >         
> >         In r227480, Ulrich Weigand introduced a workaround for a
> >         linker
> >         optimization bug that can create mis-optimized code for
> >         accesses to
> >         general-dynamic or local-dynamic TLS variables.  The linker
> >         optimization bug only occurred for Clang/LLVM because of some
> >         inefficient code being generated for these TLS accesses.  I
> >         have
> >         recently corrected LLVM to produce the efficient code sequence
> >         expected by the linkers, so this workaround is no longer
> >         needed.
> >         Therefore this patch reverts r227480.
> >         
> >         I've tested that the previous bootstrap failure no longer
> >         occurs with
> >         the workaround reverted.
> > 
> > This is awesome Bill, thanks again for tackling all of this.
> 
> Well, unfortunately it isn't going to stick. :(
> 
> A bootstrap with -O3 still fails, and there is a further, different, and
> more horrible linker optimization error to blame.  I'm going to
> re-disable the linker optimizations for now.  I'm unwilling to handcuff
> the compiler as much as would be required to let the linker optimization
> operate in its present state.

Correction: Still too soon to blame the linker here.  My eyes were
playing tricks on me.  Will take a fresh look at the cause of the
bootstrap error in the morning.

Bill

> 
> Details to follow.
> 
> Bill