Re: sincos CSE (was: quot/mod CSE...)

> I can understand how the above optimizations work, but I now don't
> understand how a sin(x) or cos(x) _by itself_ gets optimized. Perhaps
> the tree gets decorated with 'reference count' information saying how
> many nodes depend upon the sincos(x) node, so that if this refcount =
> 1, then the expression 'sinpart(sincos(x))' => 'sin(x)', as before ??


One approach is that the sincos(x) is treated as an operator that
generates a 16-byte value that has both sinpart and cospart. This
gets a cse created for it, so in this case, the actual code looks like:


                  temp=sincos(x)
                  ...sinpart(temp)...
                  ...cospart(temp)...


When such a CSE isn't created, then the sinpart(sincos(x)) gets folded
down to sin(x) and a regular sin operation takes place.




--
Jeffrey Glen Jackson
jgj@ssd.csd.harris.com
--

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