Re: [tree-ssa] Loop header copying on trees

[Zdenek Dvorak <rakdver at atrey dot karlin dot mff dot cuni dot cz>]

Hello,

>  > The jump threading on tree-ssa does this kind of loop header copying
>  >already, so I assume it might no longer be true (although I haven't
>  >tested it).
> Yes, we get a certain amount of virtual header copying via jump threading.
> 
> It would certainly be interesting to see if loop header copying at the
> tree level generally makes things larger or smaller so that we could
> make an informed decision :-)

on gcc from specint benchmark:

-O2 -ftree-ch: 1447502
-O2 -fno-tree-ch: 1429678

-Os -ftree-ch: 1175935
-Os -fno-tree-ch: 1160095

Zdenek