With JDK-8348959 we see that there can be some issues when RangeCheck smearing happens in the same IGVN phase as MergeStores. It means that some RangeChecks are still around as we do MergeStores, and then we cannot merge as many stores as we would like. We should ensure that RangeCheck smearing happens during post-loop-opts, and then MergeStores happens in a separate dedicated IGVN round afterwards.