Re: The cost of stack traces

[Casey Marshall <csm at gnu dot org>]

Something I wanted to do in the DWARF reader I wrote (but never did,  
since the patch wasn't accepted) was to cache *approximate*  
information about where to look for debug info for an address. So  
you'd have a range of PC values that would map to regions in  
the .debug_line section where you would find the debug info you were  
looking for. That would probably help lookup times, at least in a  
long-running application, and the map wouldn't need to contain too  
much data.

The big slowdown, from what I can tell, is that you have to scan from  
the very beginning of the debug info to find the address, and that  
can be slow for huge libraries like libgcj. You could probably  
optimize the hell out of this, by scanning a library just once and  
building a good, approximate cache of where to look things up.

Shall I post my patch for this again? :-)

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