Re: About standard_iv_increment_position

[Sebastian Pop <sebastian dot pop at cri dot ensmp dot fr>]

Zdenek Dvorak wrote:
> > The first remark is that this function is not used in mainline nor in
> > autovect.  It seems to me that the arguments of create_iv should be
> > computed using standard_iv_increment_position, thus some cleanup
> > changes should be considered to tree-loop-linear.c and to
> > tree-vectorizer.c.
> 
> this indeed might be a good idea.
> 

I'll prepare a patch for mainline.

> > The second remark is that standard_iv_increment_position will return a
> > block_stmt_iterator and a position that is invalid for verify_flow_info, 
> > as shown in the following case that fails:
> > 
> >       if (_n_413 < N_60) goto <L5>; else goto <L23>;
> >       ivtmp.1076_499 = ivtmp.1076_498 + 1;
> 
> I don't think this can ever happen.  

This occured during a bootstrap of gcc in autovect branch.

> The piece of code your patch
> changes is only executed with bsi in latch block.  Latch block always
> has precisely one successor, and therefore it cannot end with
> conditional expression.
> 
> This reasoning is a bit fragile, so the following might be better
> 
>   *insert_after = !last || !stmt_ends_bb_p (last);
> 

Indeed this works.  Thanks.