[Bug rtl-optimization/24814] unrolling doesn't put loop notes in right place

[amylaar at gcc dot gnu dot org]

------- Comment #5 from amylaar at gcc dot gnu dot org  2006-03-07 20:52 -------
(In reply to comment #4)
> Actually there is nothing that uses LOOP_NOTEs other than the old RTL loop
> optimizer.  At least, nothing that _should_ use it.  Wanna know about loops? 
> Find natural loops instead of depending on the notes.

So you are saying I should put natural loop detection into the SH backend so
that it can decide if it should save all target registers?

Note that the branch probability estimation machinery does not set estimated
execution counts, so the execution counts are unusable without profile data.

> But the point is moot, the old RTL loop optimizer is no more.

It had its weaknesses, but at least it was well-tuned for a wide range of
target architectures and operated generally well together with the rest of the
compiler.  What we have now is a collection of passes that often work at
cross-purposes.  E.g. web, loop strength reduction/unrolling and
auto-increment generation are completely out of sync.


-- 

amylaar at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |UNCONFIRMED
         Resolution|WONTFIX                     |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24814