problem installing Vc

[Matthias Kretz]

Hi,

On Friday 26 September 2014 19:30:31 Walter Dehnen wrote:
> However, one of your Cmake files seems faulty, here is the output:
> > cmake -DCMAKE_INSTALL_PREFIX=~/Vc -DBUILD_TESTING=OFF ../
> 
> -- The C compiler identification is GNU 4.4.7
> -- The CXX compiler identification is GNU 4.8.1

Well, that looks like your CC and CXX variables don't match. Maybe there 
should be a sanity check that errors out in that case. In any case, I don't 
want to support such a setup. (Need to keep the number of dimensions of 
parameters for testing at a minimum... and it's already way too large.)

> I noticed some nonsense
> messages such as testing the C compiler for -ftemplate_depth.

I know. Does it bother you? I don't want to make the cmake code more 
complicated just to get rid of this. If you have an idea how to fix this, 
though, I'd be happy to apply a patch.

> However, the subsequent make failed. It obviously tried to use AVX2
> instructions which are not available on my hardware.

This has nothing to do with your hardware. Only with the version of your 
assembler (i.e. binutils). I'm not sure I have a binutils version check for 
AVX2 in place - though I thought I have.

> Please advise me how to proceed,

In addition to setting CXX, please set CC to the 4.8.1 gcc binary. And then 
check your binutils version and whether you might be able to use a newer one. 
Your cmake output says you have 2.20.51 which can't do XOP. So it probably 
can't do AVX2 either. Seems like there's some cmake code missing to disable 
AVX2 then. Check the vc_check_assembler macro in VcMacros.cmake:158. I think a 
simple "set(Vc_AVX2_INTRINSICS_BROKEN true)" is missing.

Cheers,
	Matthias

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 Dipl.-Phys. Matthias Kretz

 Web:   http://compeng.uni-frankfurt.de/?mkretz

 SIMD easy and portable: http://compeng.uni-frankfurt.de/?vc
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