[cfe-dev] clang miscompile prevents ATLAS build

[Evan Cheng]

Are you using tot clang and llvm? We are just about done with -mavx. It has passed all of Intel's test suite. 

Evan

On Sep 4, 2011, at 12:52 PM, Eli Friedman <eli.friedman at gmail.com> wrote:

> On Sun, Sep 4, 2011 at 12:40 PM, Clint Whaley <whaley at cs.utsa.edu> wrote:
>> Eli,
>> 
>>> Don't use -mavx with clang... the support is incomplete at best.  (I'm
>>> actually not entirely sure why exactly the option exists.)
>> 
>> People want to compile ATLAS with clang.  ATLAS is in the performance
>> business.  Not using AVX cuts your peak in half compared to SSE on
>> sandy bridge.  I'm aware clang itself is probably not using AVX well, but
>> ATLAS contains intrinsics code that people want to compile with clang.
>> Without -mavx flag, clang is not a competitive compiler for ATLAS.
> 
> Proper AVX support is non-trivial, and it simply isn't in a working
> state.  We are making progress...
> 
> -Eli
> 
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