IA32: printing FP register variables

[Jim Blandy]

> > STABS's live range splitting notation can certainly do the job
> > correctly, but I wonder whether it can do it efficiently.  For every
> > instruction that changes TOP, you have to start a new range for every
> > variable.  So the size of debug info is O(number of insns * average
> > number of live variables).
> 
> You only have to care about variables that are live in the register stack
> before or after the operation.  So you can use an upper bound of 8.
> Hence the deubg info is O(number of insns).

Okay, but do you really want to emit up to eight stabs at every FP
instruction that changes the stack?

I dunno --- maybe it's not a big deal.  It may not be worth creating a
whole new form of debugging info to save that space.  It is certainly
a problem the various LRS representations handle.  I'd certainly agree
we should try it first.