Second Draft "Unsafe fp optimizations" project description.

[dewar@gnat.com]

<<E.g., if we want to say that optimization -fblah will cause overflow
when the inputs to the (transformed) expression are in the subset X of
all representable floating point numbers, we have to assume a model - my
suggestion is to use the IEEE-754 model.
>>

But this is meaningless, there *is* no "IEEE-754" model for evaluation of
floating-point expressions in high level languages. So this model needs
a lot of filling out. I refer again to Sam Figueroa's PhD thesis which is
all about such models.