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Re: why not consfold sin(const)



On Sep 19, 2004, at 5:31 PM, Robert Dewar wrote:


Yes; but someone (I forget who) early in this thread said it was "impossible" since you couldn't simulate target-specific elementary functions (presumably they were assuming that the target would have ill-defined or buggy routines).

Ah, now I see the discussion. This thread is actually specifically about the possibility of doing this in -ffast-math mode. My "impossible" comment was a note about doing it without this mode being turned on, and yes it is impossible to simulate target routines and precompute at compile-time the exact values you will get at run-time (because the algorithms are not documented -- which is not quite the same as ill-defined :-)

Well, they *could* be reverse engineered, as there are a finite number of possible inputs. You'd have to want this an awful lot to attempt it, though.


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