IA32: printing FP register variables

[Jim Blandy]

> At each instruction, the invariant that a is 0 from the bottom and b is 1
> from the bottom holds.  Note, the bottom of the stack can be known by the
> debugger via scanning the FPU tag word from the TOP element looking for a FP
> register that is empty.  All this info is provided by an FSAVE or FSTENV.

That could work, but what if you happen to have all eight registers in
use?