🚀 go-pugleaf

In article <WK=A6.G@xds13.ferranti.com> peter@ficc.ferranti.com (peter da silva) writes:
>If you want to specify a boolean operation on a float, do the following:
>
>	f * 2.0
>
>It's up to the compiler to determine if this multiplication by a constant
>two can be handled by incrementing the exponent or if you have to do a real
>floating multiply (say, for example, that it's m * e ^ 16).

The problem with this is that the compiler rarely has enough
information to determine if it's "safe" to just bump the exponent.
Therefore it's left with the choice of doing a number of runtime
checks (is f equal to zero? Is exponent already at upper limit?), or
just punting and generating the naive "multiply by 2.0" instruction.

I suspect most compilers will do the latter because it's ultimately
more important to get the right answer.

-- 
Jim Patterson                              Cognos Incorporated
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