[llvm] r227414 - [LPM] Try again to appease powerpc64 in its self host. I've been unable

[Ulrich Weigand]

Hal Finkel <hfinkel at anl.gov> wrote on 29.01.2015 13:49:21:

> I was able to reproduce the problem with r227415 on my PPC64 P7 box,
> and setting:
>   CMAKE_EXE_LINKER_FLAGS:STRING=-Wl,--no-tls-get-addr-optimize -
> Wl,--no-tls-optimize
>   CMAKE_MODULE_LINKER_FLAGS:STRING=-Wl,--no-tls-get-addr-optimize -
> Wl,--no-tls-optimize
> made the problem go away. Given that the bug is actually in the
> linker, I think this is really the proper solution. Can we add these
> to our build flags for PPC64 for now?

It's probably indeed the best to use the linker flag for now.

However, I think adding them to the LLVM build flags is the wrong
place; there is nothing special about compiling the LLVM code base
as such.  Rather, the problem is using clang/LLVM to compile *any*
coding using general-/local-dynamics TLS variables.

So I think the flags should be added by the clang compiler driver
whenever it invokes the linker on PowerPC.  (At least for now,
and in 3.6.  They can be removed again once Bill has changed the
code generation to again ensure use of r3 as expected by broken
linkers ...)

Bye,
Ulrich