When gdb is debugging the PowerPC architecture, it provides a set of
pseudo-registers to enable inspection of 128-bit wide Decimal Floating Point
numbers stored in the floating point registers. These values must be stored
in two consecutive registers, always starting at an even register like
f0 or f2.
The pseudo-registers go from $dl0 through $dl15, and are formed
by joining the even/odd register pairs f0 and f1 for $dl0,
f2 and f3 for $dl1 and so on.
For POWER7 processors, gdb provides a set of pseudo-registers, the 64-bit wide Extended Floating Point Registers (‘f32’ through ‘f63’).