Richard Biener
1e1fdb729d
In many cases loops have only one exit or a variable is only live across one of the exits. In this case we know that all uses outside of the loop will be dominated by the single LC PHI node we insert. If that holds for all variables requiring LC SSA PHIs then we can simplify the update_ssa process, avoiding the (iterated) dominance frontier computations. * tree-ssa-loop-manip.cc (add_exit_phis_var): Return the number of LC PHIs inserted. (add_exit_phis): Return whether any variable required multiple LC PHI nodes. (rewrite_into_loop_closed_ssa_1): Use TODO_update_ssa_no_phi when possible.
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