Hi, > b) If any PHI node has count zero it can be inserted back and its > corresponding computations removed, iff the argument of the PHI node > still exists as an SSA variable. This means that we can insert > a_1 = PHI <D.10_1> if D.10_1 still exists and hasnt been removed by > any of the passes between the scalar evolution pass and the > loopdone pass.
this does not work: -- we reuse ssa names, so it can happen that the argument of the PHI node is eliminated, then reused for a different purpose -- in case more complex loop transformations were performed (e.g., loop reversal), the final value of the ssa name might have changed. Zdenek
