/*

 * Copyright (c) 2018, Red Hat, Inc. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 *

 */

#include "precompiled.hpp"

#include "gc/shared/gcArguments.inline.hpp"

#include "gc/shared/workerPolicy.hpp"

#include "gc/shenandoah/shenandoahArguments.hpp"

#include "gc/shenandoah/shenandoahCollectorPolicy.hpp"

#include "gc/shenandoah/shenandoahHeap.hpp"

#include "gc/shenandoah/shenandoahHeapRegion.hpp"

#include "gc/shenandoah/shenandoahTaskqueue.hpp"

#include "utilities/defaultStream.hpp"

void ShenandoahArguments::initialize() {

#if !(defined AARCH64 || defined AMD64 || defined IA32)

  vm_exit_during_initialization("Shenandoah GC is not supported on this platform.");

#endif

#ifdef IA32

  log_warning(gc)("Shenandoah GC is not fully supported on this platform:");

  log_warning(gc)("  concurrent modes are not supported, only STW cycles are enabled;");

  log_warning(gc)("  arch-specific barrier code is not implemented, disabling barriers;");

  FLAG_SET_DEFAULT(ShenandoahGCHeuristics,           "passive");

  FLAG_SET_DEFAULT(ShenandoahSATBBarrier,            false);

  FLAG_SET_DEFAULT(ShenandoahKeepAliveBarrier,       false);

  FLAG_SET_DEFAULT(ShenandoahWriteBarrier,           false);

  FLAG_SET_DEFAULT(ShenandoahReadBarrier,            false);

  FLAG_SET_DEFAULT(ShenandoahStoreValEnqueueBarrier, false);

  FLAG_SET_DEFAULT(ShenandoahStoreValReadBarrier,    false);

  FLAG_SET_DEFAULT(ShenandoahCASBarrier,             false);

  FLAG_SET_DEFAULT(ShenandoahAcmpBarrier,            false);

  FLAG_SET_DEFAULT(ShenandoahCloneBarrier,           false);

#endif

#ifdef _LP64

  // The optimized ObjArrayChunkedTask takes some bits away from the full 64 addressable

  // bits, fail if we ever attempt to address more than we can. Only valid on 64bit.

  if (MaxHeapSize >= ObjArrayChunkedTask::max_addressable()) {

    jio_fprintf(defaultStream::error_stream(),

                "Shenandoah GC cannot address more than " SIZE_FORMAT " bytes, and " SIZE_FORMAT " bytes heap requested.",

                ObjArrayChunkedTask::max_addressable(), MaxHeapSize);

    vm_exit(1);

  }

#endif

  if (UseLargePages && (MaxHeapSize / os::large_page_size()) < ShenandoahHeapRegion::MIN_NUM_REGIONS) {

    warning("Large pages size (" SIZE_FORMAT "K) is too large to afford page-sized regions, disabling uncommit",

            os::large_page_size() / K);

    FLAG_SET_DEFAULT(ShenandoahUncommit, false);

  }

  // Enable NUMA by default. While Shenandoah is not NUMA-aware, enabling NUMA makes

  // storage allocation code NUMA-aware, and NUMA interleaving makes the storage

  // allocated in consistent manner (interleaving) to minimize run-to-run variance.

  if (FLAG_IS_DEFAULT(UseNUMA)) {

    FLAG_SET_DEFAULT(UseNUMA, true);

    FLAG_SET_DEFAULT(UseNUMAInterleaving, true);

  }

  FLAG_SET_DEFAULT(ParallelGCThreads,

                   WorkerPolicy::parallel_worker_threads());

  if (FLAG_IS_DEFAULT(ConcGCThreads)) {

    uint conc_threads = MAX2((uint) 1, ParallelGCThreads);

    FLAG_SET_DEFAULT(ConcGCThreads, conc_threads);

  }

  if (FLAG_IS_DEFAULT(ParallelRefProcEnabled)) {

    FLAG_SET_DEFAULT(ParallelRefProcEnabled, true);

  }

  if (ShenandoahRegionSampling && FLAG_IS_DEFAULT(PerfDataMemorySize)) {

    // When sampling is enabled, max out the PerfData memory to get more

    // Shenandoah data in, including Matrix.

    FLAG_SET_DEFAULT(PerfDataMemorySize, 2048*K);

  }

#ifdef COMPILER2

  // Shenandoah cares more about pause times, rather than raw throughput.

  if (FLAG_IS_DEFAULT(UseCountedLoopSafepoints)) {

    FLAG_SET_DEFAULT(UseCountedLoopSafepoints, true);

    if (FLAG_IS_DEFAULT(LoopStripMiningIter)) {

      FLAG_SET_DEFAULT(LoopStripMiningIter, 1000);

    }

  }

#ifdef ASSERT

  // C2 barrier verification is only reliable when all default barriers are enabled

  if (ShenandoahVerifyOptoBarriers &&

          (!FLAG_IS_DEFAULT(ShenandoahSATBBarrier)            ||

           !FLAG_IS_DEFAULT(ShenandoahKeepAliveBarrier)       ||

           !FLAG_IS_DEFAULT(ShenandoahWriteBarrier)           ||

           !FLAG_IS_DEFAULT(ShenandoahReadBarrier)            ||

           !FLAG_IS_DEFAULT(ShenandoahStoreValEnqueueBarrier) ||

           !FLAG_IS_DEFAULT(ShenandoahStoreValReadBarrier)    ||

           !FLAG_IS_DEFAULT(ShenandoahCASBarrier)             ||

           !FLAG_IS_DEFAULT(ShenandoahAcmpBarrier)            ||

           !FLAG_IS_DEFAULT(ShenandoahCloneBarrier)

          )) {

    warning("Unusual barrier configuration, disabling C2 barrier verification");

    FLAG_SET_DEFAULT(ShenandoahVerifyOptoBarriers, false);

  }

#else

  guarantee(!ShenandoahVerifyOptoBarriers, "Should be disabled");

#endif // ASSERT

#endif // COMPILER2

  if (AlwaysPreTouch) {

    // Shenandoah handles pre-touch on its own. It does not let the

    // generic storage code to do the pre-touch before Shenandoah has

    // a chance to do it on its own.

    FLAG_SET_DEFAULT(AlwaysPreTouch, false);

    FLAG_SET_DEFAULT(ShenandoahAlwaysPreTouch, true);

  }

  // Shenandoah C2 optimizations apparently dislike the shape of thread-local handshakes.

  // Disable it by default, unless we enable it specifically for debugging.

  if (FLAG_IS_DEFAULT(ThreadLocalHandshakes)) {

    if (ThreadLocalHandshakes) {

      FLAG_SET_DEFAULT(ThreadLocalHandshakes, false);

    }

  } else {

    if (ThreadLocalHandshakes) {

      warning("Thread-local handshakes are not working correctly with Shenandoah at the moment. Enable at your own risk.");

    }

  }

  // Record more information about previous cycles for improved debugging pleasure

  if (FLAG_IS_DEFAULT(LogEventsBufferEntries)) {

    FLAG_SET_DEFAULT(LogEventsBufferEntries, 250);

  }

  if (ShenandoahAlwaysPreTouch) {

    if (!FLAG_IS_DEFAULT(ShenandoahUncommit)) {

      warning("AlwaysPreTouch is enabled, disabling ShenandoahUncommit");

    }

    FLAG_SET_DEFAULT(ShenandoahUncommit, false);

  }

  // If class unloading is disabled, no unloading for concurrent cycles as well.

  // If class unloading is enabled, users should opt-in for unloading during

  // concurrent cycles.

  if (!ClassUnloading || !FLAG_IS_CMDLINE(ClassUnloadingWithConcurrentMark)) {

    log_info(gc)("Consider -XX:+ClassUnloadingWithConcurrentMark if large pause times "

                 "are observed on class-unloading sensitive workloads");

    FLAG_SET_DEFAULT(ClassUnloadingWithConcurrentMark, false);

  }

  // AOT is not supported yet

  if (UseAOT) {

    if (!FLAG_IS_DEFAULT(UseAOT)) {

      warning("Shenandoah does not support AOT at this moment, disabling UseAOT");

    }

    FLAG_SET_DEFAULT(UseAOT, false);

  }

  // JNI fast get field stuff is not currently supported by Shenandoah.

  // It would introduce another heap memory access for reading the forwarding

  // pointer, which would have to be guarded by the signal handler machinery.

  // See:

  // http://mail.openjdk.java.net/pipermail/hotspot-dev/2018-June/032763.html

  FLAG_SET_DEFAULT(UseFastJNIAccessors, false);

  // TLAB sizing policy makes resizing decisions before each GC cycle. It averages

  // historical data, assigning more recent data the weight according to TLABAllocationWeight.

  // Current default is good for generational collectors that run frequent young GCs.

  // With Shenandoah, GC cycles are much less frequent, so we need we need sizing policy

  // to converge faster over smaller number of resizing decisions.

  if (FLAG_IS_DEFAULT(TLABAllocationWeight)) {

    FLAG_SET_DEFAULT(TLABAllocationWeight, 90);

  }

  // Shenandoah needs more C2 nodes to compile some methods with lots of barriers.

  // NodeLimitFudgeFactor needs to stay the same relative to MaxNodeLimit.

#ifdef COMPILER2

  if (FLAG_IS_DEFAULT(MaxNodeLimit)) {

    FLAG_SET_DEFAULT(MaxNodeLimit, MaxNodeLimit * 3);

    FLAG_SET_DEFAULT(NodeLimitFudgeFactor, NodeLimitFudgeFactor * 3);

  }

#endif

  // Make sure safepoint deadlocks are failing predictably. This sets up VM to report

  // fatal error after 10 seconds of wait for safepoint syncronization (not the VM

  // operation itself). There is no good reason why Shenandoah would spend that

  // much time synchronizing.

#ifdef ASSERT

  FLAG_SET_DEFAULT(SafepointTimeout, true);

  FLAG_SET_DEFAULT(SafepointTimeoutDelay, 10000);

  FLAG_SET_DEFAULT(AbortVMOnSafepointTimeout, true);

#endif

}

size_t ShenandoahArguments::conservative_max_heap_alignment() {

  size_t align = ShenandoahMaxRegionSize;

  if (UseLargePages) {

    align = MAX2(align, os::large_page_size());

  }

  return align;

}

CollectedHeap* ShenandoahArguments::create_heap() {

  return create_heap_with_policy<ShenandoahHeap, ShenandoahCollectorPolicy>();

}