[llvm-commits] patch: go crazy, compute bits for an entire add instruction

[Jay Foad]

> In general though, will I be
> allowed to use an O(n) loop in ComputeMaskedBits if needed? I don't think
> we'll be able to solve multiply without it--though we can try!

I'd be very surprised if you get any real world benefit from trying to
calculate the middle bits of the result of a multiply. Surely it's
good enough to calculate just the low bits and the high bits?

Or maybe you do want the middle bits, but only in the special case
where one operand is a completely known constant. That might be easier
to solve than the completely general case, but I haven't thought about
it much.

Jay.