Obscure .eh_frame debug info question.

[Tom Horsley]

On Thu, 21 May 2009 09:25:20 -0700
Ulrich Drepper wrote:

> It's really all pretty simple, just read the DWARF specification.

I've read the dwarf spec, I've even written dwarf reader code, what
I can't figure out is the specific frame descriptions in the pthread
library. The main problem being that reg16 is defined in terms of
reg16, and no initial value is given in the CIE entry for what
reg16 starts with :-). I've tried working backward from the
expressions given to evaluate it, and the value I have to start
with for the arithmetic in the frame to produce the correct
result makes no sense at all. It isn't anything like any value
that I can imagine comes from any place in the vicinity of the
code I'm looking at. I even have a vague idea what the fanatical
macro defs for these little "inline" routines are trying to accomplish,
I just can't make the arithmetic work.