[RFC] Quad-float support for gfortran

[Dennis Wassel]

2010/5/24 FX <fxcoudert@gmail.com>:
> Dear gfortranners,
>
> For some work-related issue, I find the need to switch my code regularly between double precision real arithmetics and quad-float. I currently do that with a proprietary compiler whose brand name matches the regexp "^In{1,}[t]\x65l$", but I'd be even more happy to do that with gfortran (my usual compiler) and that gives me an excuse to get to do something I've long wanted to achieve for fun: quad-float integration in gfortran.

Nice!
I have occasionally missed it as well, and had to resort to things like XBLAS.

> [...] There is one more issue, which is how to best integrate this? [...]

I think it would be a boon to gfortran if this also supported
cross-compiling to targets which support mpfr, or at least does not
pursue an approach that makes this more difficult that it has to be.
Thus, option 2 has my vote, because people out there have built mpfr
for all kinds of targets where gcc runs natively, so the results of
their efforts can easily be re-used. Actually I like option 3, but
only as long as it does not collect bit-rot: I would always prefer
building mpfr myself over debugging the GCC build system.

Thinking about this some more, option 3 might actually make more
sense, because then the regular bootstrap is enough to produce a
quad-capable cross-gfortran, where otherwise you would have to
bootstrap, build target-mpfr and then edit the specs file accordingly
(assuming you don't have the crosstools lying around to build
target-mpfr before bootstrap). Yuck!

Cheers,
Dennis