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Re: Preprocessor arithmetic
- To: Joern Rennecke <amylaar at redhat dot com>
- Subject: Re: Preprocessor arithmetic
- From: Torbjorn Granlund <tege at swox dot com>
- Date: 15 Nov 2000 22:55:07 +0100
- Cc: zackw at Stanford dot EDU (Zack Weinberg),neilb at earthling dot net (Neil Booth), rth at redhat dot com (Richard Henderson),gcc at gcc dot gnu dot org
- References: <200011151734.eAFHYuP20398@tantra.cygnus.co.uk>
Joern Rennecke <amylaar@redhat.com> writes:
> Hm, g95 presently uses libgmp for integer and floating point
> arithmetic simulation. It might not be a bad idea to scrap what we
> have and use libgmp everywhere - particularly the floating point
> emulator.
I think that doing tree and rtl arithmetic (e.g. for fold-const.c, (g)cse.c
and combine.c) with gmp would slow the compiler down.
Yes, using GMP, at least it high-level functions is not a good idea.
It is better to implement a little special library for fixed
precision. After all, fixed precision is what the compiler really
needs.
Regarding using GMP's float functions instead of real.c, I'd vote
against that too. GMP's floats are heavy weight, and only a new
experimental function calls supports true IEEE rounding.
But my ieeelib.c which I contributed years ago might be a starting
point for a fast real.c replacement.
--
Torbjörn
(GMP author)