--- old/src/hotspot/share/memory/metaspace.cpp 2019-03-27 16:10:32.927079503 +0100 +++ new/src/hotspot/share/memory/metaspace.cpp 2019-03-27 16:10:32.623074473 +0100 @@ -952,7 +952,8 @@ higher_address = metaspace_base + compressed_class_space_size(); lower_base = metaspace_base; - uint64_t klass_encoding_max = UnscaledClassSpaceMax << LogKlassAlignmentInBytes; + // Using oopDesc::_metadata high bits so LogKlassAlignmentInBytes shift is no longer possible + uint64_t klass_encoding_max = UnscaledClassSpaceMax; // If compressed class space fits in lower 32G, we don't need a base. if (higher_address <= (address)klass_encoding_max) { lower_base = 0; // Effectively lower base is zero.