On Tue, 10 Sep 2024 12:19:32 GMT, Coleen Phillimore <cole...@openjdk.org> wrote:
>> This is tricky. We are already deep in initialization and have done a couple >> of decisions based on +UseCompressedClassPointers (e.g. CDS setup). I >> *think* we could still go with -UseCCP, but I wonder whether this is wise. >> >> Note that this error is not new. In the old code, we simply asserted. That >> left us with UB in release builds, which remains unresolved. I simply made >> the error explicit in release too. > > Ok, in this case, that's fine if we already asserted. A fatal error is > better. Actually, a lot of the old code had dusty side corners that were UB. Making narrowKlass smaller than 32bit exposed a lot of them, and a lot of the changes in and around CompressedKlassPointers are about cleanly making explicit what before had been implicit or just broken (e.g. a clear distinction between encoding range and Klass range, and a clear handling of narrowKlass bit width as a runtime value). ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/20677#discussion_r1758522844
