Abort backtrace when consecutive zero PCs?

[Andrew Cagney]

Hello,

One backtrace infinite loop case I've noticed (especially on ia64) is 
where successive frames all have a zero PC.

While we definitly need to allow a backtrace through a single zero PC 
(for a NULL pointer call - signull.exp) should we make GDB abort when 
two or more consecutive frames have a zero PC?

(mumble something about a runtime option)

thoughts?
Andrew