[LLVMdev] Issue with std::call_once in PPC64 platform

[Bill Schmidt]

On Tue, 2014-11-04 at 12:17 -0500, Samuel F Antao wrote:
> Ok, I'll put a patch together to fix this later today. I'll probably
> do what Reid was suggesting and use what is already in there for
> Windows.

Hm, better hold off on that.  Ulrich Weigand has noted that there is
invalid code generation occurring around a TLS call.  Looks like is is
probably a PPC back end problem at the moment.

Thanks,
Bill

> 
> Thanks,
> Samuel
> 
> Bill Schmidt <wschmidt at linux.vnet.ibm.com> wrote on 11/04/2014
> 12:11:08 PM:
> 
> > From: Bill Schmidt <wschmidt at linux.vnet.ibm.com>
> > To: Samuel F Antao/Watson/IBM at IBMUS
> > Cc: azanella at linux.vnet.ibm.com, beanz at apple.com, Hal Finkel 
> > <hfinkel at anl.gov>, LLVM Dev <llvmdev at cs.uiuc.edu>
> > Date: 11/04/2014 12:11 PM
> > Subject: Re: Issue with std::call_once in PPC64 platform
> > 
> > On Tue, 2014-11-04 at 11:59 -0500, Samuel F Antao wrote:
> > > Hi Bill,
> > > 
> > > You can find the same issue in the buildbot:
> > > 
> > > http://lab.llvm.org:8011/builders/clang-ppc64-elf-linux2/builds/
> > 16444/steps/compile.llvm.stage2/logs/stdio
> > > 
> > > It is failing for me both in BE (gcc 4.8.2) and LE(4.9.1). I am
> > > compiling with clang 3.5, but those are the gcc toolchains I am
> using.
> > > 
> > > What do you think is the best way to fix this?
> > 
> > I don't know what the best fix is, but clearly a fix or revert is
> needed
> > since the patch is breaking some platforms.
> > 
> > Thanks,
> > Bill
> > 
> > > 
> > > Thanks!
> > > Samuel 
> > > 
> > > Bill Schmidt <wschmidt at linux.vnet.ibm.com> wrote on 11/04/2014
> > > 11:45:06 AM:
> > > 
> > > > From: Bill Schmidt <wschmidt at linux.vnet.ibm.com>
> > > > To: Samuel F Antao/Watson/IBM at IBMUS
> > > > Cc: LLVM Dev <llvmdev at cs.uiuc.edu>, beanz at apple.com, Hal Finkel 
> > > > <hfinkel at anl.gov>, azanella at linux.vnet.ibm.com
> > > > Date: 11/04/2014 11:45 AM
> > > > Subject: Re: Issue with std::call_once in PPC64 platform
> > > > 
> > > > Hi Samuel,
> > > > 
> > > > I haven't encountered this problem.  What gcc/libstdc++ are you
> > > using?
> > > > BE or LE?
> > > > 
> > > > Copying Adhemerval in case he has heard of any related issues.
> > > > 
> > > > Thanks,
> > > > Bill
> > > > 
> > > > On Mon, 2014-11-03 at 20:19 -0500, Samuel F Antao wrote:
> > > > > Hi all,
> > > > > 
> > > > > I observe that r220932 (Removing the static initializer in
> > > > > ManagedStatic.cpp by using llvm_call_once to initialize the
> > > > > ManagedStatic mutex.) is causing tablegen to segfault in PPC
> > > platforms
> > > > > during static initialization. The crash happens while calling
> > > > >  std::call_once introduced by this patch in the wrapper used
> in
> > > > > getManagedStaticMutex. 
> > > > > 
> > > > > I understand this call is buggy for some platforms (or
> probably
> > > some
> > > > > oldish libstdc++ versions). Is this a known issue? Should we
> guard
> > > > > LLVM_DEFINE_ONCE_FLAG definition with platform specific macros
> to
> > > > > avoid the crash, at least for the moment?
> > > > > 
> > > > > Thanks!
> > > > > Samuel
> > > > > 
> > > > > 
> > > > 
> > > > 
> > > 
> > > 
> > 
> > 
> 
>