llvm dev - Mar 2017 - CMake Cache PGO error

I was trying to build llvm + clang with cmake cache PGO.cmake and ninja
stage2. I used the 4.0.0 final tag vfrom svn.

This seems to work for me.

I added libcxx, libcxxabi, llld etc.

And now I get the following cmake error.

-- Performing Test LIBCXX_SUPPORTS_STD_EQ_CXX11_FLAG
-- Performing Test LIBCXX_SUPPORTS_STD_EQ_CXX11_FLAG - Failed
CMake Error at projects/libcxx/CMakeLists.txt:396 (message):
  C++11 or greater is required but the compiler does not support c++11

I don't understand the error. Why shouldn't the cxx11 flag work.

I only use cmake -GNInja -C path/to//PGO.cmake  path/to/llvm.


So my Question is if the cache file are still maintained. And if I
shouldn't compile libcxx and the others with this cache file?

Thanks
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Haven't given the PGO cache file a shot, but I ran into a similar problem
today, and solved the issue by making sure that my host compiler had access to a
working copy of the profiling runtime.

For me, that's: ninja libclang_rt.profile_osx.a

If that's not your issue, try checking the CMake{Error,Output}.log files,
and figure out why exactly the check is failing (most likely it has nothing to
do with the "c++11 unsupported" error message).

vedant
> On Mar 15, 2017, at 3:09 PM, Timo Janssen via llvm-dev <llvm-dev at
lists.llvm.org> wrote:
> 
> I was trying to build llvm + clang with cmake cache PGO.cmake and ninja
stage2. I used the 4.0.0 final tag vfrom svn.
> 
> This seems to work for me.
> 
> I added libcxx, libcxxabi, llld etc. 
> 
> And now I get the following cmake error.
> 
> -- Performing Test LIBCXX_SUPPORTS_STD_EQ_CXX11_FLAG
> -- Performing Test LIBCXX_SUPPORTS_STD_EQ_CXX11_FLAG - Failed
> CMake Error at projects/libcxx/CMakeLists.txt:396 (message):
>   C++11 or greater is required but the compiler does not support c++11
> 
> I don't understand the error. Why shouldn't the cxx11 flag work.
> 
> I only use cmake -GNInja -C path/to//PGO.cmake  path/to/llvm.
> 
> 
> So my Question is if the cache file are still maintained. And if I
shouldn't compile libcxx and the others with this cache file?
> 
> Thanks
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev

> -----Original Message-----
> From: llvm-dev [mailto:llvm-dev-bounces at lists.llvm.org] On Behalf Of
Vedant
> Kumar via llvm-dev
...
> Haven't given the PGO cache file a shot, but I ran into a similar
problem today,
> and solved the issue by making sure that my host compiler had access to a
> working copy of the profiling runtime.
> 
> For me, that's: ninja libclang_rt.profile_osx.a
> 
> If that's not your issue, try checking the CMake{Error,Output}.log
files, and
> figure out why exactly the check is failing (most likely it has nothing to
do with
> the "c++11 unsupported" error message).
When I build with ASan+sanitizer coverage I get the same error as Timo.  For me,
it's due to undefined references to pthread_*/dlsym/__dynamic_cast/typeinfo
for __cxxabi, etc.  I'm using Ubuntu 14.04.

I think I understand that the problem is somehow related to my host compiler but
it's not clear to me how to address it.

This bug hints at the fact that the underlying problem might be a need for a
static libc++: https://bugs.llvm.org/show_bug.cgi?id=30919

The dynamic_cast test case w/-static-libstdc++ fails for me:
https://bugs.llvm.org/show_bug.cgi?id=30919#c3 but my build is after the fix (r
287373).   I haven't tried it with LIBCXX_ENABLE_STATIC_ABI_LIBRARY yet,
I'll try that next.  I suppose that must be applied to my stage0/host
compiler first before running my ASan build.

-Brian