Re: [vsipl++] patch: enable/disable fftwf, fftw, and fftwl individually

[Jules Bergmann <jules@xxxxxxxxxxxxxxxx>]

Stefan Seefeld wrote:
> The attached patch probes at configure-time for those three libraries, 
> defines VSIP_IMPL_FFTW3_HAVE_{FLOAT, DOUBLE, LONG_DOUBLE} appropriately, 
> and then only enables and defines bindings for the available types.
> OK to check in ?
Stefan,

The provide_fft_{float,double,long_double} variables advertise to the
program what FFT types are supported.  They are global across all the
different backends.

provide_fft_{float,double,long_double} are initially set to 0.  If a
backend is enabled that provides a certain FFT (say SAL provides float
FFT, or IPP provides double), then the appropriate variable is set to
1.  This gets used to set the VSIP_IMPL_PROVIDE_FFT_{TYPE} macros in
configure.ac.

If the FFTW3 BE clears these flags back to 0 as part of its 
configuration logic, any 1's set by FFT BEs earlier in the list will be 
overwritten.
An easy way to resolve this is to use a new set of variables specific
to FFTW3.  "fftw3_has_{type}" for example.

				-- Jules



> Index: m4/fft.m4
> ===================================================================
> --- m4/fft.m4	(revision 209798)
> +++ m4/fft.m4	(working copy)
> @@ -184,7 +184,6 @@
>         LIBS=$keep_LIBS])
>    fi
>  fi
> -
>  if test "$enable_builtin_fft" != "no"; then
>  
>    AC_MSG_NOTICE([Using built-in FFTW3 support.])
> @@ -206,15 +205,19 @@
>        AC_MSG_RESULT([not a supported type.])
>        AC_MSG_NOTICE([Disabling FFT support (--disable-fft-long-double).])
>        enable_fft_long_double=no 
> +      provide_fft_long_double=0
This may hide a '1' set by another BE.

>      elif test $ac_cv_sizeof_long_double = $ac_cv_sizeof_double; then
>        AC_MSG_RESULT([same size as double.])
>        AC_MSG_NOTICE([Disabling FFT support (--disable-fft-long-double).])
>        enable_fft_long_double=no 
> +      provide_fft_long_double=0
Likewise.

>      else
>        AC_MSG_RESULT([supported.])
> +      provide_fft_long_double=1
>      fi
> +    provide_fft_float=1
> +    provide_fft_double=1
The idea is that provide_fft_{type} is initialized to 0, then set to
1 when BE support is discovered.  Setting to 1 first, then clearing if
FFTW3 doesn't support the type won't play nicely with other backends.





> Index: src/vsip/opt/fftw3/fft.hpp
These changes look good.

> Index: src/vsip/opt/fftw3/fft.cpp
Likewise.



--
Jules Bergmann
CodeSourcery
jules@xxxxxxxxxxxxxxxx
(650) 331-3385 x705