[Pw_forum] patch to allow compilation with MKL FFTW3

[Yi Wang]

Hi, Dear  David Strubbe,


If you use the DFLAG "-D__DFTI" for mkl-fftw, there will be no such  
problem. I encountered this too, because the flag D__FFTW3 worked in QE  
5.0.3, but then I realized that was just luck. Since the fftw interface  
seems to be systematically improved, it is better to use the more suitable  
flag.

-- 
Yi Wang
Ph.D candidate at Nanjing University of Science and Technology


On Thu, 21 Apr 2016 07:25:15 +0800, David Strubbe <dstrubbe at berkeley.edu>  
wrote:

> In trying to compile version 5.3.0 with Intel compilers (version 16.0.0  
> 20150815) and Intel MPI, using MKL >version 2016.0.109 for FFTW3, I got  
> the following error for linking pw.x:
>
> mpiifort  -o pw.x \
>           pwscf.o  libpw.a ../../Modules/libqemod.a  
> ../../FFTXlib/libqefft.a ../../flib/ptools.a ../../flib/>flib.a  
> ../../clib/clib.a ../../iotk/src/libiotk.a -lmkl_scalapack_lp64    
> -Wl,--start-group  
> /opt/intel/>compilers_and_libraries_2016.0.109/linux/mkl/lib/intel64/libmkl_intel_lp64.a  
> /opt/intel/>compilers_and_libraries_2016.0.109/linux/mkl/lib/intel64/libmkl_sequential.a  
> /opt/intel/>compilers_and_libraries_2016.0.109/linux/mkl/lib/intel64/libmkl_core.a  
> /opt/intel/>compilers_and_libraries_2016.0.109/linux/mkl/lib/intel64/libmkl_blacs_intelmpi_lp64.a  
> -Wl,--end-group   
> /opt/intel/compilers_and_libraries_2016.0.109/linux/mkl/lib/intel64/libmkl_intel_lp64.a(fftw_version.o):(.rodata>+0x0):  
> multiple definition of `fftw_version'
> ../../FFTXlib/libqefft.a(fft_stick.o):(.data+0x430): first defined here
> ld: Warning: size of symbol `fftw_version' changed from 8 in  
> ../../FFTXlib/libqefft.a(fft_stick.o) to 27 in  
> />opt/intel/compilers_and_libraries_2016.0.109/linux/mkl/lib/intel64/libmkl_intel_lp64.a(fftw_version.o)
>
>
> I solved this problem by removing the following three offending lines:
>
> clib/fftw.h:129:extern char *fftw_version;
> FFTXlib/fftw.h:136:extern char *fftw_version;
> FFTXlib/fftw.c:348:char *fftw_version = "FFTW V1.1 ($Id: fftw.c,v 1.3  
> 2010-01-26 14:06:59 giannozz Exp $)";
>
> Then compilation and running of pw.x are successful. As far as I can  
> tell, those fftw_version lines do not serve >any purpose at least for  
> pw, pp, or ph, since I do not find this variable being used anywhere  
> else in those >parts of the code. I recommend the removal of these  
> lines, or if in some plugin I have not downloaded the >fftw_version is  
> actually used, I suggest you rename it to avoid this name clash.
>
> Cheers,
> David Strubbe
> MIT
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