[tree-ssa] reaching def. question

[Diego Novillo]

On Tue, 2004-03-16 at 19:27, law@redhat.com wrote:

> Which is not a safe thing to do if you've done things like copy propagation
> since you can have overlapping lifetimes.
> 
We do this all the time.  Passes just mark the variables they want to be
renamed and the SSA renamer is run as a cleanup.

> You also have to be damn careful about marking something to be rewritten
> which is used in a mixed PHI node.  ie
> 
> a_3 = PHI (a_2, b_1)
> 
> Marking just a or b to be written is a recipe for disaster.
> 
More context, with concrete examples, please.  Are you talking about
copyprop *while* doing if-conversion?


Diego.