Re: Question about blockframe.c:inside_main_func()

[Jason Molenda <jmolenda@apple.com>]

On Apr 28, 2004, at 6:02 PM, Joel Brobecker wrote:

> Indeed, it seems that we could improve a bit this code: It really looks
> like we are trying to compute the low/high addresses for function main
> twice! Even when main is found within the debug info, we go through the
> through the trouble of finding the bounds of function "main" from the
> min syms anyway. A missing condition somewhere?

Yeah, if I'm not mistaken we'll look up main() twice for each frame in 
a backtrace every time.  With a GUI front end keeping a stack view 
up-to-date on each step, and apps with deep stacks, that will add up 
pretty fast.  Here at Apple we found some real performance problems 
with this type of code path - things that slowed down with deep stacks 
and frequent 'backtraces' from the UI - so it's work fixing.

Looking at the individual changes to inside_main_func, I'm pretty well 
convinced this is just a combination of edits that didn't look at the 
function's behavior overall.  But it's worth checking with Andrew to 
see if there is some edge-case that isn't immediately obvious which 
would cause us to do this recomputation all the time..

J