286 lines
11 KiB
C++
286 lines
11 KiB
C++
/*
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* Copyright (c) 2015, 2020, Red Hat, Inc. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*
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*/
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#ifndef SHARE_GC_SHENANDOAH_SHENANDOAHCONCURRENTMARK_INLINE_HPP
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#define SHARE_GC_SHENANDOAH_SHENANDOAHCONCURRENTMARK_INLINE_HPP
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#include "gc/shenandoah/shenandoahAsserts.hpp"
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#include "gc/shenandoah/shenandoahBarrierSet.inline.hpp"
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#include "gc/shenandoah/shenandoahConcurrentMark.hpp"
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#include "gc/shenandoah/shenandoahHeap.inline.hpp"
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#include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
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#include "gc/shenandoah/shenandoahStringDedup.inline.hpp"
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#include "gc/shenandoah/shenandoahTaskqueue.inline.hpp"
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#include "memory/iterator.inline.hpp"
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#include "oops/compressedOops.inline.hpp"
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#include "oops/oop.inline.hpp"
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#include "runtime/prefetch.inline.hpp"
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template <class T>
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void ShenandoahConcurrentMark::do_task(ShenandoahObjToScanQueue* q, T* cl, ShenandoahLiveData* live_data, ShenandoahMarkTask* task) {
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oop obj = task->obj();
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shenandoah_assert_not_forwarded(NULL, obj);
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shenandoah_assert_marked(NULL, obj);
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shenandoah_assert_not_in_cset_except(NULL, obj, _heap->cancelled_gc());
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// Are we in weak subgraph scan?
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bool weak = task->is_weak();
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cl->set_weak(weak);
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if (task->is_not_chunked()) {
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if (obj->is_instance()) {
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// Case 1: Normal oop, process as usual.
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obj->oop_iterate(cl);
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} else if (obj->is_objArray()) {
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// Case 2: Object array instance and no chunk is set. Must be the first
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// time we visit it, start the chunked processing.
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do_chunked_array_start<T>(q, cl, obj, weak);
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} else {
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// Case 3: Primitive array. Do nothing, no oops there. We use the same
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// performance tweak TypeArrayKlass::oop_oop_iterate_impl is using:
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// We skip iterating over the klass pointer since we know that
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// Universe::TypeArrayKlass never moves.
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assert (obj->is_typeArray(), "should be type array");
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}
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// Count liveness the last: push the outstanding work to the queues first
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// Avoid double-counting objects that are visited twice due to upgrade
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// from final- to strong mark.
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if (task->count_liveness()) {
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count_liveness(live_data, obj);
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}
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} else {
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// Case 4: Array chunk, has sensible chunk id. Process it.
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do_chunked_array<T>(q, cl, obj, task->chunk(), task->pow(), weak);
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}
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}
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inline void ShenandoahConcurrentMark::count_liveness(ShenandoahLiveData* live_data, oop obj) {
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size_t region_idx = _heap->heap_region_index_containing(obj);
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ShenandoahHeapRegion* region = _heap->get_region(region_idx);
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size_t size = obj->size();
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if (!region->is_humongous_start()) {
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assert(!region->is_humongous(), "Cannot have continuations here");
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ShenandoahLiveData cur = live_data[region_idx];
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size_t new_val = size + cur;
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if (new_val >= SHENANDOAH_LIVEDATA_MAX) {
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// overflow, flush to region data
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region->increase_live_data_gc_words(new_val);
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live_data[region_idx] = 0;
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} else {
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// still good, remember in locals
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live_data[region_idx] = (ShenandoahLiveData) new_val;
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}
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} else {
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shenandoah_assert_in_correct_region(NULL, obj);
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size_t num_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize);
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for (size_t i = region_idx; i < region_idx + num_regions; i++) {
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ShenandoahHeapRegion* chain_reg = _heap->get_region(i);
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assert(chain_reg->is_humongous(), "Expecting a humongous region");
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chain_reg->increase_live_data_gc_words(chain_reg->used() >> LogHeapWordSize);
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}
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}
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}
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template <class T>
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inline void ShenandoahConcurrentMark::do_chunked_array_start(ShenandoahObjToScanQueue* q, T* cl, oop obj, bool weak) {
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assert(obj->is_objArray(), "expect object array");
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objArrayOop array = objArrayOop(obj);
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int len = array->length();
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if (len <= (int) ObjArrayMarkingStride*2) {
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// A few slices only, process directly
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array->oop_iterate_range(cl, 0, len);
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} else {
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int bits = log2_long((size_t) len);
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// Compensate for non-power-of-two arrays, cover the array in excess:
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if (len != (1 << bits)) bits++;
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// Only allow full chunks on the queue. This frees do_chunked_array() from checking from/to
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// boundaries against array->length(), touching the array header on every chunk.
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//
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// To do this, we cut the prefix in full-sized chunks, and submit them on the queue.
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// If the array is not divided in chunk sizes, then there would be an irregular tail,
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// which we will process separately.
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int last_idx = 0;
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int chunk = 1;
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int pow = bits;
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// Handle overflow
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if (pow >= 31) {
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assert (pow == 31, "sanity");
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pow--;
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chunk = 2;
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last_idx = (1 << pow);
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bool pushed = q->push(ShenandoahMarkTask(array, true, weak, 1, pow));
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assert(pushed, "overflow queue should always succeed pushing");
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}
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// Split out tasks, as suggested in ShenandoahMarkTask docs. Record the last
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// successful right boundary to figure out the irregular tail.
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while ((1 << pow) > (int)ObjArrayMarkingStride &&
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(chunk*2 < ShenandoahMarkTask::chunk_size())) {
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pow--;
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int left_chunk = chunk*2 - 1;
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int right_chunk = chunk*2;
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int left_chunk_end = left_chunk * (1 << pow);
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if (left_chunk_end < len) {
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bool pushed = q->push(ShenandoahMarkTask(array, true, weak, left_chunk, pow));
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assert(pushed, "overflow queue should always succeed pushing");
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chunk = right_chunk;
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last_idx = left_chunk_end;
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} else {
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chunk = left_chunk;
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}
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}
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// Process the irregular tail, if present
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int from = last_idx;
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if (from < len) {
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array->oop_iterate_range(cl, from, len);
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}
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}
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}
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template <class T>
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inline void ShenandoahConcurrentMark::do_chunked_array(ShenandoahObjToScanQueue* q, T* cl, oop obj, int chunk, int pow, bool weak) {
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assert(obj->is_objArray(), "expect object array");
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objArrayOop array = objArrayOop(obj);
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assert (ObjArrayMarkingStride > 0, "sanity");
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// Split out tasks, as suggested in ShenandoahMarkTask docs. Avoid pushing tasks that
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// are known to start beyond the array.
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while ((1 << pow) > (int)ObjArrayMarkingStride && (chunk*2 < ShenandoahMarkTask::chunk_size())) {
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pow--;
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chunk *= 2;
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bool pushed = q->push(ShenandoahMarkTask(array, true, weak, chunk - 1, pow));
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assert(pushed, "overflow queue should always succeed pushing");
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}
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int chunk_size = 1 << pow;
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int from = (chunk - 1) * chunk_size;
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int to = chunk * chunk_size;
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#ifdef ASSERT
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int len = array->length();
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assert (0 <= from && from < len, "from is sane: %d/%d", from, len);
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assert (0 < to && to <= len, "to is sane: %d/%d", to, len);
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#endif
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array->oop_iterate_range(cl, from, to);
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}
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class ShenandoahSATBBufferClosure : public SATBBufferClosure {
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private:
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ShenandoahObjToScanQueue* _queue;
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ShenandoahHeap* _heap;
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ShenandoahMarkingContext* const _mark_context;
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public:
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ShenandoahSATBBufferClosure(ShenandoahObjToScanQueue* q) :
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_queue(q),
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_heap(ShenandoahHeap::heap()),
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_mark_context(_heap->marking_context())
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{
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}
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void do_buffer(void **buffer, size_t size) {
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assert(size == 0 || !_heap->has_forwarded_objects(), "Forwarded objects are not expected here");
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if (ShenandoahStringDedup::is_enabled()) {
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do_buffer_impl<ENQUEUE_DEDUP>(buffer, size);
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} else {
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do_buffer_impl<NO_DEDUP>(buffer, size);
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}
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}
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template<StringDedupMode STRING_DEDUP>
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void do_buffer_impl(void **buffer, size_t size) {
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for (size_t i = 0; i < size; ++i) {
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oop *p = (oop *) &buffer[i];
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ShenandoahConcurrentMark::mark_through_ref<oop, NONE, STRING_DEDUP>(p, _heap, _queue, _mark_context, false);
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}
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}
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};
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template<class T, UpdateRefsMode UPDATE_REFS, StringDedupMode STRING_DEDUP>
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inline void ShenandoahConcurrentMark::mark_through_ref(T *p, ShenandoahHeap* heap, ShenandoahObjToScanQueue* q, ShenandoahMarkingContext* const mark_context, bool weak) {
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T o = RawAccess<>::oop_load(p);
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if (!CompressedOops::is_null(o)) {
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oop obj = CompressedOops::decode_not_null(o);
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switch (UPDATE_REFS) {
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case NONE:
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break;
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case RESOLVE:
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obj = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
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break;
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case SIMPLE:
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// We piggy-back reference updating to the marking tasks.
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obj = heap->update_with_forwarded_not_null(p, obj);
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break;
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case CONCURRENT:
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obj = heap->maybe_update_with_forwarded_not_null(p, obj);
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break;
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default:
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ShouldNotReachHere();
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}
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// Note: Only when concurrently updating references can obj be different
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// (that is, really different, not just different from-/to-space copies of the same)
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// from the one we originally loaded. Mutator thread can beat us by writing something
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// else into the location. In that case, we would mark through that updated value,
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// on the off-chance it is not handled by other means (e.g. via SATB). However,
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// if that write was NULL, we don't need to do anything else.
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if (UPDATE_REFS != CONCURRENT || !CompressedOops::is_null(obj)) {
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shenandoah_assert_not_forwarded(p, obj);
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shenandoah_assert_not_in_cset_except(p, obj, heap->cancelled_gc());
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bool skip_live = false;
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bool marked;
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if (weak) {
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marked = mark_context->mark_weak(obj);
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} else {
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marked = mark_context->mark_strong(obj, /* was_upgraded = */ skip_live);
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}
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if (marked) {
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bool pushed = q->push(ShenandoahMarkTask(obj, skip_live, weak));
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assert(pushed, "overflow queue should always succeed pushing");
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if ((STRING_DEDUP == ENQUEUE_DEDUP) && ShenandoahStringDedup::is_candidate(obj)) {
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assert(ShenandoahStringDedup::is_enabled(), "Must be enabled");
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ShenandoahStringDedup::enqueue_candidate(obj);
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}
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}
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shenandoah_assert_marked(p, obj);
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}
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}
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}
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#endif // SHARE_GC_SHENANDOAH_SHENANDOAHCONCURRENTMARK_INLINE_HPP
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