On Thu, 15 Jul 2021 15:54:50 GMT, Jorn Vernee <jver...@openjdk.org> wrote:
>> This patch rewrites the prologue and epilogue of panama upcalls, in order to >> fix the test failure from the title. >> >> Previously, we did a call to potentially attach the current thread to the >> VM, and then afterwards did the same suspend and stack reguard checks that >> we do on the back-edge of a native downcall. Then, on the back edge of the >> upcall we did another conditional call to detach the thread. >> >> The suspend and reguard checks on the front-edge are incorrect, so I've >> changed the 2 calls to mimic what is done by JavaCallWrapper instead (with >> attach and detach included), and removed the old suspend and stack reguard >> checks. >> >> FWIW, this removes the JavaFrameAnchor save/restore MacroAssembler code. >> This is now written in C++. Also, MacroAssembler code was added to >> save/restore the result of the upcall around the call on the back-edge, >> which was previously missing. Since the new code allocates a handle block as >> well, I've added handling for those oops to frame & OptimizedUpcallBlob. >> >> Testing: local running of `jdk_foreign` on Windows and Linux (WSL). Tier 1-3 > > Jorn Vernee has updated the pull request incrementally with one additional > commit since the last revision: > > Address David's review comments David, I've addressed your review comments. For now I went with changing the return type of `on_entry` to `JavaThread*`, assuming the potential pointer conversion is not an issue. I tried for a while to implement a static assert to check that `Thread*` is trivial convertible to `JavaThread*` as well, but couldn't find a way to do that at compile time, so left it for now. It looks like C++ 20 has a type trait to check this: https://en.cppreference.com/w/cpp/types/is_pointer_interconvertible_base_of (I think this does what we want). I thought maybe we could just mimic the reference implementation, but looking at for instance the MSVC STL implementation, this type trait is implemented as a compiler intrinsic, so I think we'll have to wait until we are on C++ 20 before adding such a static assert. ------------- PR: https://git.openjdk.java.net/jdk17/pull/149
