runtime/gc/heap-inl.h - platform/art - Git at Google

 /*
  * Copyright (C) 2013 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 #ifndef ART_RUNTIME_GC_HEAP_INL_H_
 #define ART_RUNTIME_GC_HEAP_INL_H_

 #include "heap.h"

 #include "allocation_listener.h"
 #include "base/quasi_atomic.h"
 #include "base/time_utils.h"
 #include "gc/accounting/atomic_stack.h"
 #include "gc/accounting/card_table-inl.h"
 #include "gc/allocation_record.h"
 #include "gc/collector/semi_space.h"
 #include "gc/space/bump_pointer_space-inl.h"
 #include "gc/space/dlmalloc_space-inl.h"
 #include "gc/space/large_object_space.h"
 #include "gc/space/region_space-inl.h"
 #include "gc/space/rosalloc_space-inl.h"
 #include "handle_scope-inl.h"
 #include "obj_ptr-inl.h"
 #include "runtime.h"
 #include "thread-inl.h"
 #include "verify_object.h"
 #include "write_barrier-inl.h"

 namespace art {
 namespace gc {

 template <bool kInstrumented, bool kCheckLargeObject, typename PreFenceVisitor>
 inline mirror::Object* Heap::AllocObjectWithAllocator(Thread* self,
                                                       ObjPtr<mirror::Class> klass,
                                                       size_t byte_count,
                                                       AllocatorType allocator,
                                                       const PreFenceVisitor& pre_fence_visitor) {
   auto no_suspend_pre_fence_visitor =
       [&pre_fence_visitor](auto... x) REQUIRES_SHARED(Locks::mutator_lock_) {
         ScopedAssertNoThreadSuspension sants("No thread suspension during pre-fence visitor");
         pre_fence_visitor(x...);
       };

   if (kIsDebugBuild) {
     CheckPreconditionsForAllocObject(klass, byte_count);
     // Since allocation can cause a GC which will need to SuspendAll, make sure all allocations are
     // done in the runnable state where suspension is expected.
     CHECK_EQ(self->GetState(), ThreadState::kRunnable);
     self->AssertThreadSuspensionIsAllowable();
     self->AssertNoPendingException();
     // Make sure to preserve klass.
     StackHandleScope<1> hs(self);
     HandleWrapperObjPtr<mirror::Class> h = hs.NewHandleWrapper(&klass);
     self->PoisonObjectPointers();
   }
   auto pre_object_allocated = [&]() REQUIRES_SHARED(Locks::mutator_lock_)
       REQUIRES(!Roles::uninterruptible_ /* only suspends if kInstrumented */) {
     if constexpr (kInstrumented) {
       AllocationListener* l = alloc_listener_.load(std::memory_order_seq_cst);
       if (UNLIKELY(l != nullptr) && UNLIKELY(l->HasPreAlloc())) {
         StackHandleScope<1> hs(self);
         HandleWrapperObjPtr<mirror::Class> h_klass(hs.NewHandleWrapper(&klass));
         l->PreObjectAllocated(self, h_klass, &byte_count);
       }
     }
   };
   ObjPtr<mirror::Object> obj;
   // bytes allocated for the (individual) object.
   size_t bytes_allocated;
   size_t usable_size;
   size_t new_num_bytes_allocated = 0;
   bool need_gc = false;
   uint32_t starting_gc_num;  // o.w. GC number at which we observed need for GC.
   {
     // Bytes allocated that includes bulk thread-local buffer allocations in addition to direct
     // non-TLAB object allocations. Only set for non-thread-local allocation,
     size_t bytes_tl_bulk_allocated = 0u;
     // Do the initial pre-alloc
     // TODO: Consider what happens if the allocator is switched while suspended here.
     pre_object_allocated();

     // Need to check that we aren't the large object allocator since the large object allocation
     // code path includes this function. If we didn't check we would have an infinite loop.
     if (kCheckLargeObject && UNLIKELY(ShouldAllocLargeObject(klass, byte_count))) {
       // AllocLargeObject can suspend and will recall PreObjectAllocated if needed.
       obj = AllocLargeObject<kInstrumented, PreFenceVisitor>(self, &klass, byte_count,
                                                              pre_fence_visitor);
       if (obj != nullptr) {
         return obj.Ptr();
       }
       // There should be an OOM exception, since we are retrying, clear it.
       self->ClearException();

       // If the large object allocation failed, try to use the normal spaces (main space,
       // non moving space). This can happen if there is significant virtual address space
       // fragmentation.
       // kInstrumented may be out of date, so recurse without large object checking, rather than
       // continue.
       return AllocObjectWithAllocator</*kInstrumented=*/ true, /*kCheckLargeObject=*/ false>
           (self, klass, byte_count, GetUpdatedAllocator(allocator), pre_fence_visitor);
     }
     ScopedAssertNoThreadSuspension ants("Called PreObjectAllocated, no suspend until alloc");
     if (IsTLABAllocator(allocator)) {
       byte_count = RoundUp(byte_count, space::BumpPointerSpace::kAlignment);
     }
     // If we have a thread local allocation we don't need to update bytes allocated.
     if (IsTLABAllocator(allocator) && byte_count <= self->TlabSize()) {
       obj = self->AllocTlab(byte_count);
       DCHECK(obj != nullptr) << "AllocTlab can't fail";
       obj->SetClass(klass);
       if (kUseBakerReadBarrier) {
         obj->AssertReadBarrierState();
       }
       bytes_allocated = byte_count;
       usable_size = bytes_allocated;
       no_suspend_pre_fence_visitor(obj, usable_size);
       QuasiAtomic::ThreadFenceForConstructor();
     } else if (
         !kInstrumented && allocator == kAllocatorTypeRosAlloc &&
         (obj = rosalloc_space_->AllocThreadLocal(self, byte_count, &bytes_allocated)) != nullptr &&
         LIKELY(obj != nullptr)) {
       DCHECK(!is_running_on_memory_tool_);
       obj->SetClass(klass);
       if (kUseBakerReadBarrier) {
         obj->AssertReadBarrierState();
       }
       usable_size = bytes_allocated;
       no_suspend_pre_fence_visitor(obj, usable_size);
       QuasiAtomic::ThreadFenceForConstructor();
     } else {
       obj = TryToAllocate<kInstrumented, false>(self, allocator, byte_count, &bytes_allocated,
                                                 &usable_size, &bytes_tl_bulk_allocated);
       if (UNLIKELY(obj == nullptr)) {
         // AllocateInternalWithGc internally re-allows, and can cause, thread suspension, if
         // someone instruments the entrypoints or changes the allocator in a suspend point here,
         // we need to retry the allocation. It will send the pre-alloc event again.
         obj = AllocateInternalWithGc(self,
                                      allocator,
                                      kInstrumented,
                                      byte_count,
                                      &bytes_allocated,
                                      &usable_size,
                                      &bytes_tl_bulk_allocated,
                                      &klass);
         if (obj == nullptr) {
           // The only way that we can get a null return if there is no pending exception is if the
           // allocator or instrumentation changed.
           if (!self->IsExceptionPending()) {
             // Since we are restarting, allow thread suspension.
             ScopedAllowThreadSuspension ats;
             // Get the new class size in case class redefinition changed the class size since alloc
             // started.
             int new_byte_count = klass->IsVariableSize()? byte_count : klass->GetObjectSize();
             // AllocObject will pick up the new allocator type, and instrumented as true is the safe
             // default.
             return AllocObjectWithAllocator</*kInstrumented=*/true>(self,
                                                                     klass,
                                                                     new_byte_count,
                                                                     GetUpdatedAllocator(allocator),
                                                                     pre_fence_visitor);
           }
           return nullptr;
         }
         // Non-null result implies neither instrumentation nor allocator changed.
       }
       DCHECK_GT(bytes_allocated, 0u);
       DCHECK_GT(usable_size, 0u);
       obj->SetClass(klass);
       if (kUseBakerReadBarrier) {
         obj->AssertReadBarrierState();
       }
       if (collector::SemiSpace::kUseRememberedSet &&
           UNLIKELY(allocator == kAllocatorTypeNonMoving)) {
         // (Note this if statement will be constant folded away for the fast-path quick entry
         // points.) Because SetClass() has no write barrier, the GC may need a write barrier in the
         // case the object is non movable and points to a recently allocated movable class.
         WriteBarrier::ForFieldWrite(obj, mirror::Object::ClassOffset(), klass);
       }
       no_suspend_pre_fence_visitor(obj, usable_size);
       QuasiAtomic::ThreadFenceForConstructor();
     }
     if (bytes_tl_bulk_allocated > 0) {
       starting_gc_num = GetCurrentGcNum();
       size_t num_bytes_allocated_before =
           num_bytes_allocated_.fetch_add(bytes_tl_bulk_allocated, std::memory_order_relaxed);
       new_num_bytes_allocated = num_bytes_allocated_before + bytes_tl_bulk_allocated;
       // Only trace when we get an increase in the number of bytes allocated. This happens when
       // obtaining a new TLAB and isn't often enough to hurt performance according to golem.
       if (region_space_) {
         // With CC collector, during a GC cycle, the heap usage increases as
         // there are two copies of evacuated objects. Therefore, add evac-bytes
         // to the heap size. When the GC cycle is not running, evac-bytes
         // are 0, as required.
         TraceHeapSize(new_num_bytes_allocated + region_space_->EvacBytes());
       } else {
         TraceHeapSize(new_num_bytes_allocated);
       }
       // IsGcConcurrent() isn't known at compile time so we can optimize by not checking it for the
       // BumpPointer or TLAB allocators. This is nice since it allows the entire if statement to be
       // optimized out.
       if (IsGcConcurrent() && UNLIKELY(ShouldConcurrentGCForJava(new_num_bytes_allocated))) {
         need_gc = true;
       }
       GetMetrics()->TotalBytesAllocated()->Add(bytes_tl_bulk_allocated);
       GetMetrics()->TotalBytesAllocatedDelta()->Add(bytes_tl_bulk_allocated);
     }
   }
   if (kIsDebugBuild && Runtime::Current()->IsStarted()) {
     CHECK_LE(obj->SizeOf(), usable_size);
   }
   // TODO: Deprecate.
   if (kInstrumented) {
     if (Runtime::Current()->HasStatsEnabled()) {
       RuntimeStats* thread_stats = self->GetStats();
       ++thread_stats->allocated_objects;
       thread_stats->allocated_bytes += bytes_allocated;
       RuntimeStats* global_stats = Runtime::Current()->GetStats();
       ++global_stats->allocated_objects;
       global_stats->allocated_bytes += bytes_allocated;
     }
   } else {
     DCHECK(!Runtime::Current()->HasStatsEnabled());
   }
   if (kInstrumented) {
     if (IsAllocTrackingEnabled()) {
       // allocation_records_ is not null since it never becomes null after allocation tracking is
       // enabled.
       DCHECK(allocation_records_ != nullptr);
       allocation_records_->RecordAllocation(self, &obj, bytes_allocated);
     }
     AllocationListener* l = alloc_listener_.load(std::memory_order_seq_cst);
     if (l != nullptr) {
       // Same as above. We assume that a listener that was once stored will never be deleted.
       // Otherwise we'd have to perform this under a lock.
       l->ObjectAllocated(self, &obj, bytes_allocated);
     }
   } else {
     DCHECK(!IsAllocTrackingEnabled());
   }
   if (AllocatorHasAllocationStack(allocator)) {
     PushOnAllocationStack(self, &obj);
   }
   if (kInstrumented) {
     if (gc_stress_mode_) {
       CheckGcStressMode(self, &obj);
     }
   } else {
     DCHECK(!gc_stress_mode_);
   }
   if (need_gc) {
     // Do this only once thread suspension is allowed again, and we're done with kInstrumented.
     RequestConcurrentGCAndSaveObject(self, /*force_full=*/ false, starting_gc_num, &obj);
   }
   VerifyObject(obj);
   self->VerifyStack();
   return obj.Ptr();
 }

 // The size of a thread-local allocation stack in the number of references.
 static constexpr size_t kThreadLocalAllocationStackSize = 128;

 inline void Heap::PushOnAllocationStack(Thread* self, ObjPtr<mirror::Object>* obj) {
   if (kUseThreadLocalAllocationStack) {
     if (UNLIKELY(!self->PushOnThreadLocalAllocationStack(obj->Ptr()))) {
       PushOnThreadLocalAllocationStackWithInternalGC(self, obj);
     }
   } else if (UNLIKELY(!allocation_stack_->AtomicPushBack(obj->Ptr()))) {
     PushOnAllocationStackWithInternalGC(self, obj);
   }
 }

 template <bool kInstrumented, typename PreFenceVisitor>
 inline mirror::Object* Heap::AllocLargeObject(Thread* self,
                                               ObjPtr<mirror::Class>* klass,
                                               size_t byte_count,
                                               const PreFenceVisitor& pre_fence_visitor) {
   // Save and restore the class in case it moves.
   StackHandleScope<1> hs(self);
   auto klass_wrapper = hs.NewHandleWrapper(klass);
   mirror::Object* obj = AllocObjectWithAllocator<kInstrumented, false, PreFenceVisitor>
                         (self, *klass, byte_count, kAllocatorTypeLOS, pre_fence_visitor);
   // Java Heap Profiler check and sample allocation.
   JHPCheckNonTlabSampleAllocation(self, obj, byte_count);
   return obj;
 }

 template <const bool kInstrumented, const bool kGrow>
 inline mirror::Object* Heap::TryToAllocate(Thread* self,
                                            AllocatorType allocator_type,
                                            size_t alloc_size,
                                            size_t* bytes_allocated,
                                            size_t* usable_size,
                                            size_t* bytes_tl_bulk_allocated) {
   if (allocator_type != kAllocatorTypeRegionTLAB &&
       allocator_type != kAllocatorTypeTLAB &&
       allocator_type != kAllocatorTypeRosAlloc &&
       UNLIKELY(IsOutOfMemoryOnAllocation(allocator_type, alloc_size, kGrow))) {
     return nullptr;
   }
   mirror::Object* ret;
   switch (allocator_type) {
     case kAllocatorTypeBumpPointer: {
       DCHECK(bump_pointer_space_ != nullptr);
       alloc_size = RoundUp(alloc_size, space::BumpPointerSpace::kAlignment);
       ret = bump_pointer_space_->AllocNonvirtual(alloc_size);
       if (LIKELY(ret != nullptr)) {
         *bytes_allocated = alloc_size;
         *usable_size = alloc_size;
         *bytes_tl_bulk_allocated = alloc_size;
       }
       break;
     }
     case kAllocatorTypeRosAlloc: {
       if (kInstrumented && UNLIKELY(is_running_on_memory_tool_)) {
         // If running on ASan, we should be using the instrumented path.
         size_t max_bytes_tl_bulk_allocated = rosalloc_space_->MaxBytesBulkAllocatedFor(alloc_size);
         if (UNLIKELY(IsOutOfMemoryOnAllocation(allocator_type,
                                                max_bytes_tl_bulk_allocated,
                                                kGrow))) {
           return nullptr;
         }
         ret = rosalloc_space_->Alloc(self, alloc_size, bytes_allocated, usable_size,
                                      bytes_tl_bulk_allocated);
       } else {
         DCHECK(!is_running_on_memory_tool_);
         size_t max_bytes_tl_bulk_allocated =
             rosalloc_space_->MaxBytesBulkAllocatedForNonvirtual(alloc_size);
         if (UNLIKELY(IsOutOfMemoryOnAllocation(allocator_type,
                                                max_bytes_tl_bulk_allocated,
                                                kGrow))) {
           return nullptr;
         }
         if (!kInstrumented) {
           DCHECK(!rosalloc_space_->CanAllocThreadLocal(self, alloc_size));
         }
         ret = rosalloc_space_->AllocNonvirtual(self,
                                                alloc_size,
                                                bytes_allocated,
                                                usable_size,
                                                bytes_tl_bulk_allocated);
       }
       break;
     }
     case kAllocatorTypeDlMalloc: {
       if (kInstrumented && UNLIKELY(is_running_on_memory_tool_)) {
         // If running on ASan, we should be using the instrumented path.
         ret = dlmalloc_space_->Alloc(self,
                                      alloc_size,
                                      bytes_allocated,
                                      usable_size,
                                      bytes_tl_bulk_allocated);
       } else {
         DCHECK(!is_running_on_memory_tool_);
         ret = dlmalloc_space_->AllocNonvirtual(self,
                                                alloc_size,
                                                bytes_allocated,
                                                usable_size,
                                                bytes_tl_bulk_allocated);
       }
       break;
     }
     case kAllocatorTypeNonMoving: {
       ret = non_moving_space_->Alloc(self,
                                      alloc_size,
                                      bytes_allocated,
                                      usable_size,
                                      bytes_tl_bulk_allocated);
       break;
     }
     case kAllocatorTypeLOS: {
       ret = large_object_space_->Alloc(self,
                                        alloc_size,
                                        bytes_allocated,
                                        usable_size,
                                        bytes_tl_bulk_allocated);
       // Note that the bump pointer spaces aren't necessarily next to
       // the other continuous spaces like the non-moving alloc space or
       // the zygote space.
       DCHECK(ret == nullptr || large_object_space_->Contains(ret));
       break;
     }
     case kAllocatorTypeRegion: {
       DCHECK(region_space_ != nullptr);
       alloc_size = RoundUp(alloc_size, space::RegionSpace::kAlignment);
       ret = region_space_->AllocNonvirtual<false>(alloc_size,
                                                   bytes_allocated,
                                                   usable_size,
                                                   bytes_tl_bulk_allocated);
       break;
     }
     case kAllocatorTypeTLAB:
       FALLTHROUGH_INTENDED;
     case kAllocatorTypeRegionTLAB: {
       DCHECK_ALIGNED(alloc_size, kObjectAlignment);
       static_assert(space::RegionSpace::kAlignment == space::BumpPointerSpace::kAlignment,
                     "mismatched alignments");
       static_assert(kObjectAlignment == space::BumpPointerSpace::kAlignment,
                     "mismatched alignments");
       if (UNLIKELY(self->TlabSize() < alloc_size)) {
         return AllocWithNewTLAB(self,
                                 allocator_type,
                                 alloc_size,
                                 kGrow,
                                 bytes_allocated,
                                 usable_size,
                                 bytes_tl_bulk_allocated);
       }
       // The allocation can't fail.
       ret = self->AllocTlab(alloc_size);
       DCHECK(ret != nullptr);
       *bytes_allocated = alloc_size;
       *bytes_tl_bulk_allocated = 0;  // Allocated in an existing buffer.
       *usable_size = alloc_size;
       break;
     }
     default: {
       LOG(FATAL) << "Invalid allocator type";
       ret = nullptr;
     }
   }
   return ret;
 }

 inline bool Heap::ShouldAllocLargeObject(ObjPtr<mirror::Class> c, size_t byte_count) const {
   // We need to have a zygote space or else our newly allocated large object can end up in the
   // Zygote resulting in it being prematurely freed.
   // We can only do this for primitive objects since large objects will not be within the card table
   // range. This also means that we rely on SetClass not dirtying the object's card.
   return byte_count >= large_object_threshold_ && (c->IsPrimitiveArray() || c->IsStringClass());
 }

 inline bool Heap::IsOutOfMemoryOnAllocation(AllocatorType allocator_type ATTRIBUTE_UNUSED,
                                             size_t alloc_size,
                                             bool grow) {
   size_t old_target = target_footprint_.load(std::memory_order_relaxed);
   while (true) {
     size_t old_allocated = num_bytes_allocated_.load(std::memory_order_relaxed);
     size_t new_footprint = old_allocated + alloc_size;
     // Tests against heap limits are inherently approximate, since multiple allocations may
     // race, and this is not atomic with the allocation.
     if (UNLIKELY(new_footprint <= old_target)) {
       return false;
     } else if (UNLIKELY(new_footprint > growth_limit_)) {
       return true;
     }
     // We are between target_footprint_ and growth_limit_ .
     if (IsGcConcurrent()) {
       return false;
     } else {
       if (grow) {
         if (target_footprint_.compare_exchange_weak(/*inout ref*/old_target, new_footprint,
                                                     std::memory_order_relaxed)) {
           VlogHeapGrowth(old_target, new_footprint, alloc_size);
           return false;
         }  // else try again.
       } else {
         return true;
       }
     }
   }
 }

 inline bool Heap::ShouldConcurrentGCForJava(size_t new_num_bytes_allocated) {
   // For a Java allocation, we only check whether the number of Java allocated bytes excceeds a
   // threshold. By not considering native allocation here, we (a) ensure that Java heap bounds are
   // maintained, and (b) reduce the cost of the check here.
   return new_num_bytes_allocated >= concurrent_start_bytes_;
 }

 }  // namespace gc
 }  // namespace art

 #endif  // ART_RUNTIME_GC_HEAP_INL_H_
	/*
	* Copyright (C) 2013 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	#ifndef ART_RUNTIME_GC_HEAP_INL_H_
	#define ART_RUNTIME_GC_HEAP_INL_H_

	#include "heap.h"

	#include "allocation_listener.h"
	#include "base/quasi_atomic.h"
	#include "base/time_utils.h"
	#include "gc/accounting/atomic_stack.h"
	#include "gc/accounting/card_table-inl.h"
	#include "gc/allocation_record.h"
	#include "gc/collector/semi_space.h"
	#include "gc/space/bump_pointer_space-inl.h"
	#include "gc/space/dlmalloc_space-inl.h"
	#include "gc/space/large_object_space.h"
	#include "gc/space/region_space-inl.h"
	#include "gc/space/rosalloc_space-inl.h"
	#include "handle_scope-inl.h"
	#include "obj_ptr-inl.h"
	#include "runtime.h"
	#include "thread-inl.h"
	#include "verify_object.h"
	#include "write_barrier-inl.h"

	namespace art {
	namespace gc {

	template <bool kInstrumented, bool kCheckLargeObject, typename PreFenceVisitor>
	inline mirror::Object* Heap::AllocObjectWithAllocator(Thread* self,
	ObjPtr<mirror::Class> klass,
	size_t byte_count,
	AllocatorType allocator,
	const PreFenceVisitor& pre_fence_visitor) {
	auto no_suspend_pre_fence_visitor =
	[&pre_fence_visitor](auto... x) REQUIRES_SHARED(Locks::mutator_lock_) {
	ScopedAssertNoThreadSuspension sants("No thread suspension during pre-fence visitor");
	pre_fence_visitor(x...);
	};

	if (kIsDebugBuild) {
	CheckPreconditionsForAllocObject(klass, byte_count);
	// Since allocation can cause a GC which will need to SuspendAll, make sure all allocations are
	// done in the runnable state where suspension is expected.
	CHECK_EQ(self->GetState(), ThreadState::kRunnable);
	self->AssertThreadSuspensionIsAllowable();
	self->AssertNoPendingException();
	// Make sure to preserve klass.
	StackHandleScope<1> hs(self);
	HandleWrapperObjPtr<mirror::Class> h = hs.NewHandleWrapper(&klass);
	self->PoisonObjectPointers();
	}
	auto pre_object_allocated = [&]() REQUIRES_SHARED(Locks::mutator_lock_)
	REQUIRES(!Roles::uninterruptible_ /* only suspends if kInstrumented */) {
	if constexpr (kInstrumented) {
	AllocationListener* l = alloc_listener_.load(std::memory_order_seq_cst);
	if (UNLIKELY(l != nullptr) && UNLIKELY(l->HasPreAlloc())) {
	StackHandleScope<1> hs(self);
	HandleWrapperObjPtr<mirror::Class> h_klass(hs.NewHandleWrapper(&klass));
	l->PreObjectAllocated(self, h_klass, &byte_count);
	}
	}
	};
	ObjPtr<mirror::Object> obj;
	// bytes allocated for the (individual) object.
	size_t bytes_allocated;
	size_t usable_size;
	size_t new_num_bytes_allocated = 0;
	bool need_gc = false;
	uint32_t starting_gc_num; // o.w. GC number at which we observed need for GC.
	{
	// Bytes allocated that includes bulk thread-local buffer allocations in addition to direct
	// non-TLAB object allocations. Only set for non-thread-local allocation,
	size_t bytes_tl_bulk_allocated = 0u;
	// Do the initial pre-alloc
	// TODO: Consider what happens if the allocator is switched while suspended here.
	pre_object_allocated();

	// Need to check that we aren't the large object allocator since the large object allocation
	// code path includes this function. If we didn't check we would have an infinite loop.
	if (kCheckLargeObject && UNLIKELY(ShouldAllocLargeObject(klass, byte_count))) {
	// AllocLargeObject can suspend and will recall PreObjectAllocated if needed.
	obj = AllocLargeObject<kInstrumented, PreFenceVisitor>(self, &klass, byte_count,
	pre_fence_visitor);
	if (obj != nullptr) {
	return obj.Ptr();
	}
	// There should be an OOM exception, since we are retrying, clear it.
	self->ClearException();

	// If the large object allocation failed, try to use the normal spaces (main space,
	// non moving space). This can happen if there is significant virtual address space
	// fragmentation.
	// kInstrumented may be out of date, so recurse without large object checking, rather than
	// continue.
	return AllocObjectWithAllocator</kInstrumented=/ true, /kCheckLargeObject=/ false>
	(self, klass, byte_count, GetUpdatedAllocator(allocator), pre_fence_visitor);
	}
	ScopedAssertNoThreadSuspension ants("Called PreObjectAllocated, no suspend until alloc");
	if (IsTLABAllocator(allocator)) {
	byte_count = RoundUp(byte_count, space::BumpPointerSpace::kAlignment);
	}
	// If we have a thread local allocation we don't need to update bytes allocated.
	if (IsTLABAllocator(allocator) && byte_count <= self->TlabSize()) {
	obj = self->AllocTlab(byte_count);
	DCHECK(obj != nullptr) << "AllocTlab can't fail";
	obj->SetClass(klass);
	if (kUseBakerReadBarrier) {
	obj->AssertReadBarrierState();
	}
	bytes_allocated = byte_count;
	usable_size = bytes_allocated;
	no_suspend_pre_fence_visitor(obj, usable_size);
	QuasiAtomic::ThreadFenceForConstructor();
	} else if (
	!kInstrumented && allocator == kAllocatorTypeRosAlloc &&
	(obj = rosalloc_space_->AllocThreadLocal(self, byte_count, &bytes_allocated)) != nullptr &&
	LIKELY(obj != nullptr)) {
	DCHECK(!is_running_on_memory_tool_);
	obj->SetClass(klass);
	if (kUseBakerReadBarrier) {
	obj->AssertReadBarrierState();
	}
	usable_size = bytes_allocated;
	no_suspend_pre_fence_visitor(obj, usable_size);
	QuasiAtomic::ThreadFenceForConstructor();
	} else {
	obj = TryToAllocate<kInstrumented, false>(self, allocator, byte_count, &bytes_allocated,
	&usable_size, &bytes_tl_bulk_allocated);
	if (UNLIKELY(obj == nullptr)) {
	// AllocateInternalWithGc internally re-allows, and can cause, thread suspension, if
	// someone instruments the entrypoints or changes the allocator in a suspend point here,
	// we need to retry the allocation. It will send the pre-alloc event again.
	obj = AllocateInternalWithGc(self,
	allocator,
	kInstrumented,
	byte_count,
	&bytes_allocated,
	&usable_size,
	&bytes_tl_bulk_allocated,
	&klass);
	if (obj == nullptr) {
	// The only way that we can get a null return if there is no pending exception is if the
	// allocator or instrumentation changed.
	if (!self->IsExceptionPending()) {
	// Since we are restarting, allow thread suspension.
	ScopedAllowThreadSuspension ats;
	// Get the new class size in case class redefinition changed the class size since alloc
	// started.
	int new_byte_count = klass->IsVariableSize()? byte_count : klass->GetObjectSize();
	// AllocObject will pick up the new allocator type, and instrumented as true is the safe
	// default.
	return AllocObjectWithAllocator</kInstrumented=/true>(self,
	klass,
	new_byte_count,
	GetUpdatedAllocator(allocator),
	pre_fence_visitor);
	}
	return nullptr;
	}
	// Non-null result implies neither instrumentation nor allocator changed.
	}
	DCHECK_GT(bytes_allocated, 0u);
	DCHECK_GT(usable_size, 0u);
	obj->SetClass(klass);
	if (kUseBakerReadBarrier) {
	obj->AssertReadBarrierState();
	}
	if (collector::SemiSpace::kUseRememberedSet &&
	UNLIKELY(allocator == kAllocatorTypeNonMoving)) {
	// (Note this if statement will be constant folded away for the fast-path quick entry
	// points.) Because SetClass() has no write barrier, the GC may need a write barrier in the
	// case the object is non movable and points to a recently allocated movable class.
	WriteBarrier::ForFieldWrite(obj, mirror::Object::ClassOffset(), klass);
	}
	no_suspend_pre_fence_visitor(obj, usable_size);
	QuasiAtomic::ThreadFenceForConstructor();
	}
	if (bytes_tl_bulk_allocated > 0) {
	starting_gc_num = GetCurrentGcNum();
	size_t num_bytes_allocated_before =
	num_bytes_allocated_.fetch_add(bytes_tl_bulk_allocated, std::memory_order_relaxed);
	new_num_bytes_allocated = num_bytes_allocated_before + bytes_tl_bulk_allocated;
	// Only trace when we get an increase in the number of bytes allocated. This happens when
	// obtaining a new TLAB and isn't often enough to hurt performance according to golem.
	if (region_space_) {
	// With CC collector, during a GC cycle, the heap usage increases as
	// there are two copies of evacuated objects. Therefore, add evac-bytes
	// to the heap size. When the GC cycle is not running, evac-bytes
	// are 0, as required.
	TraceHeapSize(new_num_bytes_allocated + region_space_->EvacBytes());
	} else {
	TraceHeapSize(new_num_bytes_allocated);
	}
	// IsGcConcurrent() isn't known at compile time so we can optimize by not checking it for the
	// BumpPointer or TLAB allocators. This is nice since it allows the entire if statement to be
	// optimized out.
	if (IsGcConcurrent() && UNLIKELY(ShouldConcurrentGCForJava(new_num_bytes_allocated))) {
	need_gc = true;
	}
	GetMetrics()->TotalBytesAllocated()->Add(bytes_tl_bulk_allocated);
	GetMetrics()->TotalBytesAllocatedDelta()->Add(bytes_tl_bulk_allocated);
	}
	}
	if (kIsDebugBuild && Runtime::Current()->IsStarted()) {
	CHECK_LE(obj->SizeOf(), usable_size);
	}
	// TODO: Deprecate.
	if (kInstrumented) {
	if (Runtime::Current()->HasStatsEnabled()) {
	RuntimeStats* thread_stats = self->GetStats();
	++thread_stats->allocated_objects;
	thread_stats->allocated_bytes += bytes_allocated;
	RuntimeStats* global_stats = Runtime::Current()->GetStats();
	++global_stats->allocated_objects;
	global_stats->allocated_bytes += bytes_allocated;
	}
	} else {
	DCHECK(!Runtime::Current()->HasStatsEnabled());
	}
	if (kInstrumented) {
	if (IsAllocTrackingEnabled()) {
	// allocation_records_ is not null since it never becomes null after allocation tracking is
	// enabled.
	DCHECK(allocation_records_ != nullptr);
	allocation_records_->RecordAllocation(self, &obj, bytes_allocated);
	}
	AllocationListener* l = alloc_listener_.load(std::memory_order_seq_cst);
	if (l != nullptr) {
	// Same as above. We assume that a listener that was once stored will never be deleted.
	// Otherwise we'd have to perform this under a lock.
	l->ObjectAllocated(self, &obj, bytes_allocated);
	}
	} else {
	DCHECK(!IsAllocTrackingEnabled());
	}
	if (AllocatorHasAllocationStack(allocator)) {
	PushOnAllocationStack(self, &obj);
	}
	if (kInstrumented) {
	if (gc_stress_mode_) {
	CheckGcStressMode(self, &obj);
	}
	} else {
	DCHECK(!gc_stress_mode_);
	}
	if (need_gc) {
	// Do this only once thread suspension is allowed again, and we're done with kInstrumented.
	RequestConcurrentGCAndSaveObject(self, /force_full=/ false, starting_gc_num, &obj);
	}
	VerifyObject(obj);
	self->VerifyStack();
	return obj.Ptr();
	}

	// The size of a thread-local allocation stack in the number of references.
	static constexpr size_t kThreadLocalAllocationStackSize = 128;

	inline void Heap::PushOnAllocationStack(Thread* self, ObjPtr<mirror::Object>* obj) {
	if (kUseThreadLocalAllocationStack) {
	if (UNLIKELY(!self->PushOnThreadLocalAllocationStack(obj->Ptr()))) {
	PushOnThreadLocalAllocationStackWithInternalGC(self, obj);
	}
	} else if (UNLIKELY(!allocation_stack_->AtomicPushBack(obj->Ptr()))) {
	PushOnAllocationStackWithInternalGC(self, obj);
	}
	}

	template <bool kInstrumented, typename PreFenceVisitor>
	inline mirror::Object* Heap::AllocLargeObject(Thread* self,
	ObjPtr<mirror::Class>* klass,
	size_t byte_count,
	const PreFenceVisitor& pre_fence_visitor) {
	// Save and restore the class in case it moves.
	StackHandleScope<1> hs(self);
	auto klass_wrapper = hs.NewHandleWrapper(klass);
	mirror::Object* obj = AllocObjectWithAllocator<kInstrumented, false, PreFenceVisitor>
	(self, *klass, byte_count, kAllocatorTypeLOS, pre_fence_visitor);
	// Java Heap Profiler check and sample allocation.
	JHPCheckNonTlabSampleAllocation(self, obj, byte_count);
	return obj;
	}

	template <const bool kInstrumented, const bool kGrow>
	inline mirror::Object* Heap::TryToAllocate(Thread* self,
	AllocatorType allocator_type,
	size_t alloc_size,
	size_t* bytes_allocated,
	size_t* usable_size,
	size_t* bytes_tl_bulk_allocated) {
	if (allocator_type != kAllocatorTypeRegionTLAB &&
	allocator_type != kAllocatorTypeTLAB &&
	allocator_type != kAllocatorTypeRosAlloc &&
	UNLIKELY(IsOutOfMemoryOnAllocation(allocator_type, alloc_size, kGrow))) {
	return nullptr;
	}
	mirror::Object* ret;
	switch (allocator_type) {
	case kAllocatorTypeBumpPointer: {
	DCHECK(bump_pointer_space_ != nullptr);
	alloc_size = RoundUp(alloc_size, space::BumpPointerSpace::kAlignment);
	ret = bump_pointer_space_->AllocNonvirtual(alloc_size);
	if (LIKELY(ret != nullptr)) {
	*bytes_allocated = alloc_size;
	*usable_size = alloc_size;
	*bytes_tl_bulk_allocated = alloc_size;
	}
	break;
	}
	case kAllocatorTypeRosAlloc: {
	if (kInstrumented && UNLIKELY(is_running_on_memory_tool_)) {
	// If running on ASan, we should be using the instrumented path.
	size_t max_bytes_tl_bulk_allocated = rosalloc_space_->MaxBytesBulkAllocatedFor(alloc_size);
	if (UNLIKELY(IsOutOfMemoryOnAllocation(allocator_type,
	max_bytes_tl_bulk_allocated,
	kGrow))) {
	return nullptr;
	}
	ret = rosalloc_space_->Alloc(self, alloc_size, bytes_allocated, usable_size,
	bytes_tl_bulk_allocated);
	} else {
	DCHECK(!is_running_on_memory_tool_);
	size_t max_bytes_tl_bulk_allocated =
	rosalloc_space_->MaxBytesBulkAllocatedForNonvirtual(alloc_size);
	if (UNLIKELY(IsOutOfMemoryOnAllocation(allocator_type,
	max_bytes_tl_bulk_allocated,
	kGrow))) {
	return nullptr;
	}
	if (!kInstrumented) {
	DCHECK(!rosalloc_space_->CanAllocThreadLocal(self, alloc_size));
	}
	ret = rosalloc_space_->AllocNonvirtual(self,
	alloc_size,
	bytes_allocated,
	usable_size,
	bytes_tl_bulk_allocated);
	}
	break;
	}
	case kAllocatorTypeDlMalloc: {
	if (kInstrumented && UNLIKELY(is_running_on_memory_tool_)) {
	// If running on ASan, we should be using the instrumented path.
	ret = dlmalloc_space_->Alloc(self,
	alloc_size,
	bytes_allocated,
	usable_size,
	bytes_tl_bulk_allocated);
	} else {
	DCHECK(!is_running_on_memory_tool_);
	ret = dlmalloc_space_->AllocNonvirtual(self,
	alloc_size,
	bytes_allocated,
	usable_size,
	bytes_tl_bulk_allocated);
	}
	break;
	}
	case kAllocatorTypeNonMoving: {
	ret = non_moving_space_->Alloc(self,
	alloc_size,
	bytes_allocated,
	usable_size,
	bytes_tl_bulk_allocated);
	break;
	}
	case kAllocatorTypeLOS: {
	ret = large_object_space_->Alloc(self,
	alloc_size,
	bytes_allocated,
	usable_size,
	bytes_tl_bulk_allocated);
	// Note that the bump pointer spaces aren't necessarily next to
	// the other continuous spaces like the non-moving alloc space or
	// the zygote space.
	DCHECK(ret == nullptr \|\| large_object_space_->Contains(ret));
	break;
	}
	case kAllocatorTypeRegion: {
	DCHECK(region_space_ != nullptr);
	alloc_size = RoundUp(alloc_size, space::RegionSpace::kAlignment);
	ret = region_space_->AllocNonvirtual<false>(alloc_size,
	bytes_allocated,
	usable_size,
	bytes_tl_bulk_allocated);
	break;
	}
	case kAllocatorTypeTLAB:
	FALLTHROUGH_INTENDED;
	case kAllocatorTypeRegionTLAB: {
	DCHECK_ALIGNED(alloc_size, kObjectAlignment);
	static_assert(space::RegionSpace::kAlignment == space::BumpPointerSpace::kAlignment,
	"mismatched alignments");
	static_assert(kObjectAlignment == space::BumpPointerSpace::kAlignment,
	"mismatched alignments");
	if (UNLIKELY(self->TlabSize() < alloc_size)) {
	return AllocWithNewTLAB(self,
	allocator_type,
	alloc_size,
	kGrow,
	bytes_allocated,
	usable_size,
	bytes_tl_bulk_allocated);
	}
	// The allocation can't fail.
	ret = self->AllocTlab(alloc_size);
	DCHECK(ret != nullptr);
	*bytes_allocated = alloc_size;
	*bytes_tl_bulk_allocated = 0; // Allocated in an existing buffer.
	*usable_size = alloc_size;
	break;
	}
	default: {
	LOG(FATAL) << "Invalid allocator type";
	ret = nullptr;
	}
	}
	return ret;
	}

	inline bool Heap::ShouldAllocLargeObject(ObjPtr<mirror::Class> c, size_t byte_count) const {
	// We need to have a zygote space or else our newly allocated large object can end up in the
	// Zygote resulting in it being prematurely freed.
	// We can only do this for primitive objects since large objects will not be within the card table
	// range. This also means that we rely on SetClass not dirtying the object's card.
	return byte_count >= large_object_threshold_ && (c->IsPrimitiveArray() \|\| c->IsStringClass());
	}

	inline bool Heap::IsOutOfMemoryOnAllocation(AllocatorType allocator_type ATTRIBUTE_UNUSED,
	size_t alloc_size,
	bool grow) {
	size_t old_target = target_footprint_.load(std::memory_order_relaxed);
	while (true) {
	size_t old_allocated = num_bytes_allocated_.load(std::memory_order_relaxed);
	size_t new_footprint = old_allocated + alloc_size;
	// Tests against heap limits are inherently approximate, since multiple allocations may
	// race, and this is not atomic with the allocation.
	if (UNLIKELY(new_footprint <= old_target)) {
	return false;
	} else if (UNLIKELY(new_footprint > growth_limit_)) {
	return true;
	}
	// We are between target_footprint_ and growth_limit_ .
	if (IsGcConcurrent()) {
	return false;
	} else {
	if (grow) {
	if (target_footprint_.compare_exchange_weak(/inout ref/old_target, new_footprint,
	std::memory_order_relaxed)) {
	VlogHeapGrowth(old_target, new_footprint, alloc_size);
	return false;
	} // else try again.
	} else {
	return true;
	}
	}
	}
	}

	inline bool Heap::ShouldConcurrentGCForJava(size_t new_num_bytes_allocated) {
	// For a Java allocation, we only check whether the number of Java allocated bytes excceeds a
	// threshold. By not considering native allocation here, we (a) ensure that Java heap bounds are
	// maintained, and (b) reduce the cost of the check here.
	return new_num_bytes_allocated >= concurrent_start_bytes_;
	}

	} // namespace gc
	} // namespace art

	#endif // ART_RUNTIME_GC_HEAP_INL_H_