[Bug rtl-optimization/50904] [4.7 regression] pessimization when -fno-protect-parens is enabled by -Ofast

[ebotcazou at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50904

Eric Botcazou <ebotcazou at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
                 CC|ebotcazou at gcc dot        |
                   |gnu.org                     |
          Component|tree-optimization           |rtl-optimization
         AssignedTo|unassigned at gcc dot       |ebotcazou at gcc dot
                   |gnu.org                     |gnu.org

--- Comment #19 from Eric Botcazou <ebotcazou at gcc dot gnu.org> 2011-12-01 19:53:15 UTC ---
> lim3 was added as a "hack", now yes, cunroll needs ccp after it (but it's
> there in the form of DOM and VRP).  It's a pass ordering issue that we
> cannot ever solve.

OK, but that doesn't explain why LIM isn't able to hoist the loads...

> Please - it seems like a missed optimization there, too.

More of an acknowledged limitation I'd say.  And RTL passes aren't supposed to
be enhanced to plug holes in the Tree passes, but let's try anyway.