Float commands for 64bit data

Fabian Cenedese Cenedese@indel.ch
Mon Dec 11 12:18:00 GMT 2006


> > The best thing for us would be some kind of -msoft-float-ll which
> > would only affect the (mis)use of the FPU for moving 64bit long
> > longs around but leave the real float calculations intact. The
> > second best may be a pragma or attribute for explicit code
> > sections. If there is no such thing we would also change the gcc
> > code itself if this code generation is in a central place. Of
> > course we would prefer to use the vanilla gcc.
>
>OK, all that makes sense.
>
>The easiest way to do that is simply to disable the patterns that
>generate the floating-point operations.  I think the pattern is this
>one:
>
>You'd want to remove the operations with "f" in their constraint
>pattern: that is, no. 8 and 9.  An alternative idea would be to alter
>the cost of the opration so that the compiler never chooses to put a
>float in an int register.

Thanks for the directions. We'll try it out and let you know how it
works once we find our way around the gcc source code, but that
may take some time.

Thanks again

bye  Fabi




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