--- a/hotspot/src/share/vm/opto/ifnode.cpp Tue Jan 12 12:55:09 2016 +0100
+++ b/hotspot/src/share/vm/opto/ifnode.cpp Tue Jan 12 12:55:37 2016 +0100
@@ -1530,13 +1530,16 @@
Node* IfProjNode::Identity(PhaseGVN* phase) {
// Can only optimize if cannot go the other way
const TypeTuple *t = phase->type(in(0))->is_tuple();
- if (t == TypeTuple::IFNEITHER ||
- // kill dead branch first otherwise the IfNode's control will
- // have 2 control uses (the IfNode that doesn't go away because
- // it still has uses and this branch of the
- // If). Node::has_special_unique_user() will cause this node to
- // be reprocessed once the dead branch is killed.
- (always_taken(t) && in(0)->outcnt() == 1)) {
+ if (t == TypeTuple::IFNEITHER || (always_taken(t) &&
+ // During parsing (GVN) we don't remove dead code aggressively.
+ // Cut off dead branch and let PhaseRemoveUseless take care of it.
+ (!phase->is_IterGVN() ||
+ // During IGVN, first wait for the dead branch to be killed.
+ // Otherwise, the IfNode's control will have two control uses (the IfNode
+ // that doesn't go away because it still has uses and this branch of the
+ // If) which breaks other optimizations. Node::has_special_unique_user()
+ // will cause this node to be reprocessed once the dead branch is killed.
+ in(0)->outcnt() == 1))) {
// IfNode control
return in(0)->in(0);
}