Xavier Routh · rarbore2
--- a/hercules_opt/src/forkify.rs
+++ b/hercules_opt/src/forkify.rs
            // PHIs on the frontier of the uses by the candidate phi, i.e in uses_for_dependance need
            // to have headers that postdominate the loop continue latch. The value of the PHI used needs to be defined
            // by the time the reduce is triggered (at the end of the loop's internal control).
+            // If anything in the intersection is a phi (that isn't this own phi), then the reduction cycle depends on control.
+            // Which is not allowed.
+            if intersection.iter().any(|cycle_node| editor.node(cycle_node).is_phi() && *cycle_node != *phi) || editor.node(loop_continue_latch).is_phi() {
+                return LoopPHI::ControlDependant(*phi);
+            }