1 /*
  2  * Copyright (c) 2021, Red Hat, Inc. All rights reserved.
  3  * Copyright (c) 2020, Oracle and/or its affiliates. All rights reserved.
  4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  5  *
  6  * This code is free software; you can redistribute it and/or modify it
  7  * under the terms of the GNU General Public License version 2 only, as
  8  * published by the Free Software Foundation.
  9  *
 10  * This code is distributed in the hope that it will be useful, but WITHOUT
 11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 13  * version 2 for more details (a copy is included in the LICENSE file that
 14  * accompanied this code).
 15  *
 16  * You should have received a copy of the GNU General Public License version
 17  * 2 along with this work; if not, write to the Free Software Foundation,
 18  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 19  *
 20  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 21  * or visit www.oracle.com if you need additional information or have any
 22  * questions.
 23  *
 24  */
 25 
 26 #include "precompiled.hpp"
 27 
 28 #include "gc/shenandoah/shenandoahAsserts.hpp"
 29 #include "gc/shenandoah/shenandoahClosures.inline.hpp"
 30 #include "gc/shenandoah/shenandoahCodeRoots.hpp"
 31 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
 32 #include "gc/shenandoah/shenandoahStackWatermark.hpp"
 33 #include "gc/shenandoah/shenandoahUtils.hpp"
 34 #include "runtime/safepointVerifiers.hpp"
 35 
 36 uint32_t ShenandoahStackWatermark::_epoch_id = 1;
 37 
 38 ShenandoahOnStackCodeBlobClosure::ShenandoahOnStackCodeBlobClosure() :
 39     _bs_nm(BarrierSet::barrier_set()->barrier_set_nmethod()) {}
 40 
 41 void ShenandoahOnStackCodeBlobClosure::do_code_blob(CodeBlob* cb) {
 42   nmethod* const nm = cb->as_nmethod_or_null();
 43   if (nm != NULL) {
 44     const bool result = _bs_nm->nmethod_entry_barrier(nm);
 45     assert(result, "NMethod on-stack must be alive");
 46   }
 47 }
 48 
 49 ThreadLocalAllocStats& ShenandoahStackWatermark::stats() {
 50   return _stats;
 51 }
 52 
 53 uint32_t ShenandoahStackWatermark::epoch_id() const {
 54   return _epoch_id;
 55 }
 56 
 57 void ShenandoahStackWatermark::change_epoch_id() {
 58   shenandoah_assert_safepoint();
 59   _epoch_id++;
 60 }
 61 
 62 ShenandoahStackWatermark::ShenandoahStackWatermark(JavaThread* jt) :
 63   StackWatermark(jt, StackWatermarkKind::gc, _epoch_id),
 64   _heap(ShenandoahHeap::heap()),
 65   _stats(),
 66   _keep_alive_cl(),
 67   _evac_update_oop_cl(),
 68   _cb_cl() {}
 69 
 70 OopClosure* ShenandoahStackWatermark::closure_from_context(void* context) {
 71   if (context != NULL) {
 72     assert(_heap->is_concurrent_weak_root_in_progress() ||
 73            _heap->is_concurrent_mark_in_progress(),
 74            "Only these two phases");
 75     assert(Thread::current()->is_Worker_thread(), "Unexpected thread passing in context: " PTR_FORMAT, p2i(context));
 76     return reinterpret_cast<OopClosure*>(context);
 77   } else {
 78     if (_heap->is_concurrent_mark_in_progress()) {
 79       return &_keep_alive_cl;
 80     } else if (_heap->is_concurrent_weak_root_in_progress()) {
 81       assert(_heap->is_evacuation_in_progress(), "Nothing to evacuate");
 82       return &_evac_update_oop_cl;
 83     } else {
 84       ShouldNotReachHere();
 85       return NULL;
 86     }
 87   }
 88 }
 89 
 90 void ShenandoahStackWatermark::start_processing_impl(void* context) {
 91   NoSafepointVerifier nsv;
 92   ShenandoahHeap* const heap = ShenandoahHeap::heap();
 93 
 94   // Process the non-frame part of the thread
 95   if (heap->is_concurrent_mark_in_progress()) {
 96     // We need to reset all TLABs because they might be below the TAMS, and we need to mark
 97     // the objects in them. Do not let mutators allocate any new objects in their current TLABs.
 98     // It is also a good place to resize the TLAB sizes for future allocations.
 99     retire_tlab();
100 
101     _jt->oops_do_no_frames(closure_from_context(context), &_cb_cl);
102   } else if (heap->is_concurrent_weak_root_in_progress()) {
103     assert(heap->is_evacuation_in_progress(), "Should not be armed");
104     // Retire the TLABs, which will force threads to reacquire their TLABs.
105     // This is needed for two reasons. Strong one: new allocations would be with new freeset,
106     // which would be outside the collection set, so no cset writes would happen there.
107     // Weaker one: new allocations would happen past update watermark, and so less work would
108     // be needed for reference updates (would update the large filler instead).
109     retire_tlab();
110 
111     _jt->oops_do_no_frames(closure_from_context(context), &_cb_cl);
112   } else {
113     ShouldNotReachHere();
114   }
115 
116   // Publishes the processing start to concurrent threads
117   StackWatermark::start_processing_impl(context);
118 }
119 
120 void ShenandoahStackWatermark::retire_tlab() {
121   // Retire TLAB
122   if (UseTLAB) {
123     _stats.reset();
124     _jt->tlab().retire(&_stats);
125     if (ResizeTLAB) {
126       _jt->tlab().resize();
127     }
128   }
129 }
130 
131 void ShenandoahStackWatermark::process(const frame& fr, RegisterMap& register_map, void* context) {
132   OopClosure* oops = closure_from_context(context);
133   assert(oops != NULL, "Should not get to here");
134   ShenandoahHeap* const heap = ShenandoahHeap::heap();
135   assert((heap->is_concurrent_weak_root_in_progress() && heap->is_evacuation_in_progress()) ||
136          heap->is_concurrent_mark_in_progress(),
137          "Only these two phases");
138   fr.oops_do(oops, &_cb_cl, &register_map, DerivedPointerIterationMode::_directly);
139 }