Re: [tree-ssa] [PATCH]: Fix DCE not updating bb->end_tree_p

[Daniel Berlin <dberlin at dberlin dot org>]

> bsi_last() has a speed hack in it that predates bsi_prev(), or at least
> doesnt work with bsi_prev(). I dont recall saying anything about using
> bsi_last() :-).

Then how does one iterate through a basic block in reverse, if not 
starting with bsi_last and using bsi_prev until we hit the start?
:)

> bsi_last(), for better or for worse, will attempt to set the iterator 
> to
> whatever the end pointer is. If it succeeds in doing this, it doesnt
> have the iterator history required when we decend down into 
> BIND_EXPR's.
> It was never really intended for use with bsi_prev(). It was really
> intended for when you simply wanted a BSI object for the last stmt.
>
> I didnt suggest using bsi_last(). I suggested changing your loop which
> is going to pass through the previous stmt before it terminates anyway,
This would require two iterators, rahter than one, since we don't know 
what the previous statement is before we start.

So if I did what you said, i'd have effectively copied and pasted what 
bsi_prev's code is to do this exact same thing, which seems like a very 
silly thing to do.
>