AOT cache uses pointer compression to store 64-bit pointers in 32 bits. Currently the compression algorithm is simply (base + narrowPtr). However, in JDK-8376125, we may change it to (base + narrowPtr << 3).

This RFE changed the encoded pointer from an u4 to

    enum class narrowPtr : u4;

This allows us better tracking of where the encoded pointers are stored. Also, we can better distinguish between byte offsets vs encoded pointers -- they currently have the same numerical values but after JDK-8376125, they will be different.