8263375: Support stack watermarks in Zero VM

Reviewed-by: eosterlund

src/hotspot/cpu/zero/frame_zero.cpp

@@ -34,6 +34,7 @@
 #include "runtime/frame.inline.hpp"
 #include "runtime/handles.inline.hpp"
 #include "runtime/signature.hpp"
+#include "runtime/stackWatermarkSet.hpp"
 #include "vmreg_zero.inline.hpp"
 
 #ifdef ASSERT
@@ -82,10 +83,15 @@ frame frame::sender(RegisterMap* map) const {
   // sender_for_xxx methods update this accordingly.
   map->set_include_argument_oops(false);
 
-  if (is_entry_frame())
+  frame result = zeroframe()->is_entry_frame() ?
-    return sender_for_entry_frame(map);
+                 sender_for_entry_frame(map) :
-  else
+                 sender_for_nonentry_frame(map);
-    return sender_for_nonentry_frame(map);
+
+  if (map->process_frames()) {
+    StackWatermarkSet::on_iteration(map->thread(), result);
+  }
+
+  return result;
 }
 
 BasicObjectLock* frame::interpreter_frame_monitor_begin() const {

src/hotspot/cpu/zero/vm_version_zero.hpp

@@ -32,6 +32,8 @@
 class VM_Version : public Abstract_VM_Version {
  public:
   static void initialize();
+
+  constexpr static bool supports_stack_watermark_barrier() { return true; }
 };
 
 #endif // CPU_ZERO_VM_VERSION_ZERO_HPP

src/hotspot/cpu/zero/zeroInterpreter_zero.cpp

@@ -200,6 +200,18 @@ void ZeroInterpreter::main_loop(int recurse, TRAPS) {
     }
     fixup_after_potential_safepoint();
 
+    // If we are unwinding, notify the stack watermarks machinery.
+    // Should do this before resetting the frame anchor.
+    if (istate->msg() == BytecodeInterpreter::return_from_method ||
+        istate->msg() == BytecodeInterpreter::do_osr) {
+      stack_watermark_unwind_check(thread);
+    } else {
+      assert(istate->msg() == BytecodeInterpreter::call_method ||
+             istate->msg() == BytecodeInterpreter::more_monitors ||
+             istate->msg() == BytecodeInterpreter::throwing_exception,
+             "Should be one of these otherwise");
+    }
+
     // Clear the frame anchor
     thread->reset_last_Java_frame();
 
@@ -436,6 +448,10 @@ int ZeroInterpreter::native_entry(Method* method, intptr_t UNUSED, TRAPS) {
   thread->set_thread_state(_thread_in_Java);
   fixup_after_potential_safepoint();
 
+  // Notify the stack watermarks machinery that we are unwinding.
+  // Should do this before resetting the frame anchor.
+  stack_watermark_unwind_check(thread);
+
   // Clear the frame anchor
   thread->reset_last_Java_frame();
 
@@ -869,3 +885,13 @@ address ZeroInterpreter::remove_activation_early_entry(TosState state) {
 bool ZeroInterpreter::contains(address pc) {
   return false; // make frame::print_value_on work
 }
+
+void ZeroInterpreter::stack_watermark_unwind_check(JavaThread* thread) {
+  // If frame pointer is in the danger zone, notify the runtime that
+  // it needs to act before continuing the unwinding.
+  uintptr_t fp = (uintptr_t)thread->last_Java_fp();
+  uintptr_t watermark = thread->poll_data()->get_polling_word();
+  if (fp > watermark) {
+    InterpreterRuntime::at_unwind(thread);
+  }
+}

src/hotspot/cpu/zero/zeroInterpreter_zero.hpp

@@ -39,6 +39,9 @@
   static int empty_entry(Method* method, intptr_t UNUSED, TRAPS);
   static int Reference_get_entry(Method* method, intptr_t UNUSED, TRAPS);
 
+  // Stack watermark machinery
+  static void stack_watermark_unwind_check(JavaThread* thread);
+
  public:
   // Main loop of normal_entry
   static void main_loop(int recurse, TRAPS);

src/hotspot/share/interpreter/zero/bytecodeInterpreter.cpp

@@ -107,7 +107,7 @@
   There really shouldn't be any handles remaining to trash but this is cheap
   in relation to a safepoint.
 */
-#define SAFEPOINT                                                                                         \
+#define RETURN_SAFEPOINT                                                                                  \
     if (SafepointMechanism::should_process(THREAD)) {                                                     \
       HandleMarkCleaner __hmc(THREAD);                                                                    \
       CALL_VM(SafepointMechanism::process_if_requested_with_exit_check(THREAD, true /* check asyncs */),  \
@@ -1331,23 +1331,15 @@ run:
       CASE(_areturn):
       CASE(_ireturn):
       CASE(_freturn):
-      {
-          // Allow a safepoint before returning to frame manager.
-          SAFEPOINT;
-
-          goto handle_return;
-      }
-
       CASE(_lreturn):
       CASE(_dreturn):
-      {
+      CASE(_return): {
           // Allow a safepoint before returning to frame manager.
-          SAFEPOINT;
+          RETURN_SAFEPOINT;
           goto handle_return;
       }
 
       CASE(_return_register_finalizer): {
-
           oop rcvr = LOCALS_OBJECT(0);
           VERIFY_OOP(rcvr);
           if (rcvr->klass()->has_finalizer()) {
@@ -1355,12 +1347,6 @@ run:
           }
           goto handle_return;
       }
-      CASE(_return): {
-
-          // Allow a safepoint before returning to frame manager.
-          SAFEPOINT;
-          goto handle_return;
-      }
 
       /* Array access byte-codes */