(remote) hellishly slow single stepping over library calls

["Kris Warkentin" <kewarken@qnx.com>]

When debugging using our QNX pdebug remote protocol and single stepping over
a library call like printf, it takes a LOOOONG time.  I'm talking like two
or three minutes.  A 'next' is fine but looking at the output of running our
pdebug server in verbose mode, gdb is doing step, step, step, all the way
through the whole library call.  Every single step results in fetching
registers and there is a huge amount of wire traffic generated.

This didn't happen with older (ie 5.0) gdbs which didn't seem to know how to
single step through our shared lib code but now that it does, this is pretty
painful.  Obviously it makes more sense to 'next' over a library call,
especially if you don't want to go into it but the question is, can anyone
think of a way to optimize this?  I though of putting in a hack like:

if (reg == PC_REGNUM)
    only_get_pc();

to avoid fetching the whole regset but it probably won't make that much
difference since there's still a packet over the wire each time and most
regsets fit in one packet anyway.

Would this problem also exist with the normal remote protocol?  (stupid
users...clicking step instead of next....;-)

cheers,

Kris