Re: [rfc, frame] Move the corrupt frame checks earlier

[Mark Kettenis <mark dot kettenis at xs4all dot nl>]

> Date: Sat, 19 Aug 2006 11:56:54 -0400
> From: Daniel Jacobowitz <drow@false.org>
> 
> This patch is a follow-on to the unwind_stop_reason patch, although not
> actually dependent.  It moves the frame-went-inner and frame-same-ID
> checks earlier in the backtrace process.  Although they move down
> in the function, they also check PREV rather than THIS.
> 
> The benefit of doing this is that we display the stop reason before,
> rather than after, the frame we've decided is corrupt.  For instance,
> suppose we have two frames with the same ID.  That means they have the
> same CFA and the same function.  In other words, the same stack frame.
> So the second backtrace entry will be a duplicate of the first. There's
> no added value in displaying it, and logically it doesn't need to exist
> on the frame chain.

Sorry it's not clear to me what exactly the effect is.  Does it make
frames disappear that are there now?  I wouldn't like that, since it
the past I clearly remember getting useful information out of the last
frame printed in a bad backtrace.

Perhaps you can give an example of the old & new behaviour?

Mark