------- Additional Comments From ebotcazou at gcc dot gnu dot org 2004-11-16
08:05 -------
> There has only been one patch to combine after 3.3 which might have caused
> this:
>
> 2003-10-06 Eric Botcazou <[EMAIL PROTECTED]>
>
> PR optimization/11637
> * combine.c (adjust_for_new_dest): New function to adjust the
> notes and LOG_LINKS when the dest of an insn has changed.
> (try_combine): Use it when deleting the first insn of a two-insn
> parallel or splitting a two-load parallel.
No, this patch is not responsible for the quadratic behaviour, which is still
present as of today on AMD64: reverting it doesn't change anything on mainline.
Digging a little further would have showed that the patch only adds a call to
distribute_links, not distribute_notes, which contains this comment:
Note that this correctly handles the link that used to point from
I3 to I2. Also note that not much searching is typically done here
since most links don't point very far away. */
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13931
