[PATCH]: PR middle-end/30447 handle builtin csin

Ian Lance Taylor iant@google.com
Fri Jan 19 15:52:00 GMT 2007


"Richard Guenther" <richard.guenther@gmail.com> writes:

> As to the required precision you only need one more bit to compensate
> for one intermediate rounding step.

My understanding is that for some operations you need two guard bits
and a sticky bit.  You can increase the precision of the intermediate
operations all you want, but without a sticky bit you may not get the
exact rounded result if all the extra bits are 1.

http://docs.sun.com/source/806-3568/ncg_goldberg.html

But I am not an expert either.

Whether we care about a rare 1 ULP error in the implementation of csin
is a different question.

Ian



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