Re: DECstation 2100 floating point

On Fri, 25 Mar 2011 09:00:30 +1100
Simon Burge <[email protected]> wrote:

> George Harvey wrote:
> 
> > On Mon, 21 Mar 2011 20:40:14 +0000
> > George Harvey <[email protected]> wrote:
> > 
> > If I compile 'flops' with no optimisation then it works on my 2100, if
> > I use -O or -O2 then it produces 'nan' and 'inf' results. However, if I
> > copy the binaries over to my 5000/133 then both optimised versions work
> > normally. So it looks as though GCC is generating code that works on a
> > R3000/R3010 combo but doesn't work on a R2000/R2010. 
> 
> Hopefully you've just proved that the problem isn't inside libc or
> the kernel since just changing the compile options of the program
> itself gets the right results.
> 
> There are some R2000-specific options to gcc.  Can you try the
> -march=r2000 and/or -mtune=r2000 options and see if that makes any
> difference?

No difference when applied to 'flops.c'. I tried:

-O
-O -march=r2000
-O -mtune=r2000
-O -march=r2000 -mtune=r2000

And all four produced exactly the same binary.

George