Re: [tcb] Incremental SSA updates

[Diego Novillo <dnovillo at redhat dot com>]

On Fri, Mar 18, 2005 at 01:03:30PM -0500, Kazu Hirata wrote:

> In other words, DOM figures out a taken edge using conditional
> equivalences it creates while following a dominator tree.  With VRP,
> these conditional equivalences are stored in the combination of
> ASSERT_EXPRs and PHI nodes.  Plus, these conditional equivalences are
> pretty easy to get at.  Just follow a ud chain and you will hit an
> ASSERT_EXPR.
> 
OK.  If that's all the information needed by the jump threader,
then it should be straightforward to replace the tables built by
DOM with the information already present in the IL.

Now that we can have VRP insert PHI nodes again, it should be a
matter of trying then.

> Jeff seems to want to thread edges through a block that contains some
> statements before a COND_EXPR or SWITCH_EXPR.  In that case, DOM would
> only need to build various tables starting at the beginning of the
> block being threaded through.
> 
Got an example?  Not sure I follow what you're saying here.


Diego.