Re: Will tree-ssa be GCC 3.5?

[Ian Lance Taylor <ian at wasabisystems dot com>]

law@redhat.com writes:

> In message <87oeusnfwp.fsf@egil.codesourcery.com>, "Zack Weinberg" writes:
>  >kenner@vlsi1.ultra.nyu.edu (Richard Kenner) writes:
>  >
>  >> We don't yet know that it will be *replacing* anything.  For the moment,
>  >> it'll be adding a new class of optimizations.
>  >
>  >This strikes me as disingenuous.  The people working on the tree-ssa
>  >project have clearly and repeatedly stated their intention to replace
>  >several (perhaps most) of the RTL optimizers.  That this has not
>  >happened yet merely indicates that the project is not done yet.
> More correctly, it is our intention to either replace or significantly
> simplify some of the RTL optimizations.  In particular, null pointer
> check elimination, CSE, GCSE, jump opts (including jump threading).

It seems to me that you still want CSE to handle little stuff like
parts of addresses on machines which need to build up addresses by
parts (e.g., MIPS), or for that matter parts of constants on machines
which need to build constants by parts (e.g., ARM).

Conversely, I would think that tree-ssa might be able to get rid of
the RTL loop optimization pass.  On the other hand, then how do you
handle prefetch generation?

But perhaps I misunderstand.

Ian