src/hotspot/cpu/x86/stubGenerator_x86_64.cpp

*** 33,10 ***
--- 33,11 ---
  #include "gc/shared/gc_globals.hpp"
  #include "memory/universe.hpp"
  #include "prims/jvmtiExport.hpp"
  #include "prims/upcallLinker.hpp"
  #include "runtime/arguments.hpp"
+ #include "runtime/continuationEntry.hpp"
  #include "runtime/javaThread.hpp"
  #include "runtime/sharedRuntime.hpp"
  #include "runtime/stubRoutines.hpp"
  #include "stubGenerator_x86_64.hpp"
  #ifdef COMPILER2

*** 3777,10 ***
--- 3778,63 ---
  
  address StubGenerator::generate_cont_returnBarrier_exception() {
    return generate_cont_thaw("Cont thaw return barrier exception", Continuation::thaw_return_barrier_exception);
  }
  
+ address StubGenerator::generate_cont_preempt_stub() {
+   if (!Continuations::enabled()) return nullptr;
+   StubCodeMark mark(this, "StubRoutines","Continuation preempt stub");
+   address start = __ pc();
+ 
+ #ifdef ASSERT
+   __ push(rax);
+   { Label L;
+     __ get_thread(rax);
+     __ cmpptr(r15_thread, rax);
+     __ jcc(Assembler::equal, L);
+     __ stop("r15 should have been preserved across VM call");
+     __ bind(L);
+   }
+   __ pop(rax);
+ #endif
+ 
+   __ reset_last_Java_frame(true);
+ 
+   // reset _preempting flag
+ #ifdef ASSERT
+   { Label L;
+     __ movbool(rscratch1, Address(r15_thread, JavaThread::preempting_offset()));
+     __ testbool(rscratch1);
+     __ jcc(Assembler::notZero, L);
+     __ stop("preempting flag should be set");
+     __ bind(L);
+   }
+ #endif
+   __ movbool(Address(r15_thread, JavaThread::preempting_offset()), false);
+ 
+   // Set rsp to enterSpecial frame
+   __ movptr(rsp, Address(r15_thread, JavaThread::cont_entry_offset()));
+ 
+   Label preemption_cancelled;
+   __ movbool(rscratch1, Address(r15_thread, JavaThread::preemption_cancelled_offset()));
+   __ testbool(rscratch1);
+   __ jcc(Assembler::notZero, preemption_cancelled);
+ 
+   // Remove enterSpecial frame from the stack and return to Continuation.run()
+   SharedRuntime::continuation_enter_cleanup(_masm);
+   __ pop(rbp);
+   __ ret(0);
+ 
+   __ bind(preemption_cancelled);
+   __ movbool(Address(r15_thread, JavaThread::preemption_cancelled_offset()), false);
+   __ lea(rbp, Address(rsp, checked_cast<int32_t>(ContinuationEntry::size())));
+   __ movptr(rscratch1, ExternalAddress(ContinuationEntry::thaw_call_pc_address()));
+   __ jmp(rscratch1);
+ 
+   return start;
+ }
+ 
  // exception handler for upcall stubs
  address StubGenerator::generate_upcall_stub_exception_handler() {
    StubCodeMark mark(this, "StubRoutines", "upcall stub exception handler");
    address start = __ pc();
  

*** 3949,10 ***
--- 4003,11 ---
  void StubGenerator::generate_continuation_stubs() {
    // Continuation stubs:
    StubRoutines::_cont_thaw          = generate_cont_thaw();
    StubRoutines::_cont_returnBarrier = generate_cont_returnBarrier();
    StubRoutines::_cont_returnBarrierExc = generate_cont_returnBarrier_exception();
+   StubRoutines::_cont_preempt_stub = generate_cont_preempt_stub();
  }
  
  void StubGenerator::generate_final_stubs() {
    // Generates the rest of stubs and initializes the entry points