src/hotspot/share/gc/shared/barrierSet.cpp

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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#include "precompiled.hpp"
#include "gc/shared/barrierSet.hpp"
#include "gc/shared/barrierSetAssembler.hpp"
#include "gc/shared/barrierSetNMethod.hpp"
#include "gc/shared/barrierSetStackChunk.hpp"
#include "runtime/continuation.hpp"
#include "runtime/javaThread.hpp"
#include "utilities/debug.hpp"
#include "utilities/macros.hpp"

BarrierSet* BarrierSet::_barrier_set = nullptr;

void BarrierSet::set_barrier_set(BarrierSet* barrier_set) {
  assert(_barrier_set == nullptr, "Already initialized");
  _barrier_set = barrier_set;

  // Notify barrier set of the current (main) thread.  Normally the
  // Thread constructor deals with this, but the main thread is
  // created before we get here.  Verify it isn't yet on the thread
  // list, else we'd also need to call BarrierSet::on_thread_attach.
  // This is the only thread that can exist at this point; the Thread
  // constructor objects to other threads being created before the
  // barrier set is available.
  assert(Thread::current()->is_Java_thread(),
         "Expected main thread to be a JavaThread");
  assert(!JavaThread::current()->on_thread_list(),
         "Main thread already on thread list.");
  _barrier_set->on_thread_create(Thread::current());
}

static BarrierSetNMethod* select_barrier_set_nmethod(BarrierSetNMethod* barrier_set_nmethod) {
  if (barrier_set_nmethod != nullptr) {
    // The GC needs nmethod entry barriers to do concurrent GC
    return barrier_set_nmethod;
  } else {
    // The GC needs nmethod entry barriers to deal with continuations
    // and code cache unloading
    return new BarrierSetNMethod();
  }
}

static BarrierSetStackChunk* select_barrier_set_stack_chunk(BarrierSetStackChunk* barrier_set_stack_chunk) {
  if (barrier_set_stack_chunk != nullptr) {
    return barrier_set_stack_chunk;
  } else {
    return new BarrierSetStackChunk();
  }
}

BarrierSet::BarrierSet(BarrierSetAssembler* barrier_set_assembler,
                       BarrierSetC1* barrier_set_c1,
                       BarrierSetC2* barrier_set_c2,
                       BarrierSetNMethod* barrier_set_nmethod,
                       BarrierSetStackChunk* barrier_set_stack_chunk,
                       const FakeRtti& fake_rtti) :
    _fake_rtti(fake_rtti),
    _barrier_set_assembler(barrier_set_assembler),
    _barrier_set_c1(barrier_set_c1),
    _barrier_set_c2(barrier_set_c2),
    _barrier_set_nmethod(select_barrier_set_nmethod(barrier_set_nmethod)),
    _barrier_set_stack_chunk(select_barrier_set_stack_chunk(barrier_set_stack_chunk)) {
}

void BarrierSet::on_thread_attach(Thread* thread) {
  BarrierSetNMethod* bs_nm = barrier_set_nmethod();
  if (bs_nm != nullptr) {
    thread->set_nmethod_disarmed_guard_value(bs_nm->disarmed_guard_value());
  }
}

// Called from init.cpp
void gc_barrier_stubs_init() {
  BarrierSet* bs = BarrierSet::barrier_set();
#ifndef ZERO
  BarrierSetAssembler* bs_assembler = bs->barrier_set_assembler();
  bs_assembler->barrier_stubs_init();
#endif
}