public void reduceTrivialMerge(AbstractMergeNode merge) {
assert merge.forwardEndCount() == 1;
assert !(merge instanceof LoopBeginNode) || ((LoopBeginNode) merge).loopEnds().isEmpty();
for (PhiNode phi : merge.phis().snapshot()) {
assert phi.valueCount() == 1;
ValueNode singleValue = phi.valueAt(0);
phi.replaceAtUsagesAndDelete(singleValue);
}
// remove loop exits
if (merge instanceof LoopBeginNode) {
((LoopBeginNode) merge).removeExits();
}
AbstractEndNode singleEnd = merge.forwardEndAt(0);
FixedNode sux = merge.next();
FrameState stateAfter = merge.stateAfter();
// evacuateGuards
merge.prepareDelete((FixedNode) singleEnd.predecessor());
merge.safeDelete();
if (stateAfter != null && stateAfter.isAlive() && stateAfter.hasNoUsages()) {
GraphUtil.killWithUnusedFloatingInputs(stateAfter);
}
if (sux == null) {
singleEnd.replaceAtPredecessor(null);
singleEnd.safeDelete();
} else {
singleEnd.replaceAndDelete(sux);
}
}
public static void checkRedundantPhi(PhiNode phiNode) {
if (phiNode.isDeleted() || phiNode.valueCount() == 1) {
return;
}
ValueNode singleValue = phiNode.singleValue();
if (singleValue != null) {
Collection<PhiNode> phiUsages = phiNode.usages().filter(PhiNode.class).snapshot();
Collection<ProxyNode> proxyUsages = phiNode.usages().filter(ProxyNode.class).snapshot();
phiNode.graph().replaceFloating(phiNode, singleValue);
for (PhiNode phi : phiUsages) {
checkRedundantPhi(phi);
}
for (ProxyNode proxy : proxyUsages) {
checkRedundantProxy(proxy);
}
}
}