[patch] Add toplevel configure check for MPFR

[Joseph S. Myers]

On Sun, 25 Jul 2004, Gabriel Dos Reis wrote:

> | it would complicate importing GMP into GCC (i.e. we'd need to import both
> | GMP and MPFR) if we wish to use it outside the Fortran front end (for more
> | general constant folding of built-in functions).
> 
> Why would we need it all at? (apart from Gfortran is using it at the
> moment?).

For constant folding more <math.h> and <complex.h> functions than we do at
the moment without many error-prone ad hoc reimplementations of the
functions which MPFR already does.  (See the various past discussions
about how we don't always round the result of sqrtl correctly on systems
with long double with 106-bit mantissa.)

-- 
Joseph S. Myers               http://www.srcf.ucam.org/~jsm28/gcc/
    jsm@polyomino.org.uk (personal mail)
    jsm28@gcc.gnu.org (Bugzilla assignments and CCs)