CALL STORE(); widening; perfect conversions

[David Keaton]

     Thanks, Tim, for your analysis.  I am disappointed that the
prospect for well-behaved performance in perfect conversions is not
good.  Still, I can imagine offering it to customers as an option,
just not the default.  (It would become the default if most customers
change their minds and decide in favor of perfect conversions instead
of performance.)  As such, I would not object to having perfect
conversions listed as a "common extension."

>  Unsurprisingly, the *real*
>headaches are caused by large-magnitude exponents, and because Cray's
>64-bit format has about eight times the dynamic range of 754's 64-bit
>format, the worst cases would oblige you to fake exact integer
>arithmetic on operands exceeding 8,000 bits . . . .

     This may give rise to another problem.  If you can tell the
magnitude of a number by how long it takes to print it out, that opens
up a security hole in formerly secure systems.  I don't expect it to
cause problems in most cases, but there are some customers who will
need to be aware of it.

					David Keaton
					Cray Computer
					dmkacraycos.com