[jdk17] RFR: 8269240: java/foreign/stackwalk/TestAsyncStackWalk.java test failed with concurrent GC

[Vladimir Ivanov]

On Fri, 25 Jun 2021 17:38:32 GMT, Jorn Vernee <jvernee at 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

Looks good.

src/hotspot/cpu/x86/frame_x86.cpp line 356:

> 354: }
> 355: 
> 356: OptimizedEntryBlob::FrameData* OptimizedEntryBlob::frame_data_for_frame(const frame& frame) const {

It makes sense to assert that `frame` refers to optimized entry frame (`assert(frame->is_optimized_entry_frame(), "wrong frame");`.

src/hotspot/share/runtime/thread.hpp line 1128:

> 1126: 
> 1127:  private:
> 1128:   DEBUG_ONLY(void verify_frame_info();)

If you declare `verify_frame_info` as returning a `bool` (and just put a `return true;` at the end of `JavaThread::verify_frame_info()`), you can call it as:

assert(verify_frame_info(), "unexpected frame info");

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Marked as reviewed by vlivanov (Reviewer).

PR: https://git.openjdk.java.net/jdk17/pull/149