[gfortran] use numerically safe algorithm for folding CABS

[Tobias Schlüter]

Joseph S. Myers wrote:
> On Thu, 7 Oct 2004, [ISO-8859-1] Tobias Schlüter wrote:
>>>Can't you use mpfr_hypot?
>>
>>No, I can't because the version of mpfr distributed with GMP doesn't have it.
>>One more reason to import mpfr into the GCC tree, I assume. I will add a
>>comment pointing out that this code can be replaced when we import mpfr into
>>the tree.
> 
> 
> It looks to me to be in GMP 4.1,

Silly me! I had only checked the documentation, but not looked at mpfr.h.
Indeed, even the version of mpfr supplied with gmp has mpfr_hypot. So I
propose this revised patch, which simply uses the mpfr_hypot function.

Built and tested. Ok?

- Tobi

2004-10-06  Tobias Schlueter  <tobias.schlueter@physik.uni-muenchen.de>

	* simplify.c (gfc_simplify_abs): Use mpfr_hypot for CABS.
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