dart::Page Class Reference

#include <page.h>

Public Types
enum	PageFlags : uword {   kExecutable = 1 << 0 , kLarge = 1 << 1 , kImage = 1 << 2 , kVMIsolate = 1 << 3 ,   kNew = 1 << 4 , kEvacuationCandidate = 1 << 5 }

Public Member Functions
bool	is_executable () const
bool	is_large () const
bool	is_image () const
bool	is_vm_isolate () const
bool	is_new () const
bool	is_old () const
bool	is_evacuation_candidate () const
Page *	next () const
void	set_next (Page *next)
uword	start () const
uword	end () const
bool	Contains (uword addr) const
uword	object_start () const
uword	old_object_start () const
uword	new_object_start () const
uword	object_end () const
intptr_t	used () const
ForwardingPage *	forwarding_page () const
void	RegisterUnwindingRecords ()
void	UnregisterUnwindingRecords ()
void	AllocateForwardingPage ()
void	VisitObjects (ObjectVisitor *visitor) const
void	VisitObjectsUnsafe (ObjectVisitor *visitor) const
void	VisitObjectPointers (ObjectPointerVisitor *visitor) const
void	WriteProtect (bool read_only)
uword	original_top () const
uword	original_end () const
intptr_t	card_table_size () const
void	RememberCard (ObjectPtr const *slot)
bool	IsCardRemembered (ObjectPtr const *slot)
void	VisitRememberedCards (ObjectPointerVisitor *visitor)
void	ResetProgressBar ()
Thread *	owner () const
void	RecordSurvivors ()
void	EarlyTenure ()
uword	promo_candidate_words () const
void	Acquire (Thread *thread)
intptr_t	Release (Thread *thread)
void	Release ()
uword	TryAllocateGC (intptr_t size)
void	Unallocate (uword addr, intptr_t size)
bool	IsSurvivor (uword raw_addr) const
bool	IsResolved () const

Static Public Member Functions
static void	Init ()
static void	ClearCache ()
static intptr_t	CachedSize ()
static void	Cleanup ()
static constexpr intptr_t	OldObjectStartOffset ()
static constexpr intptr_t	NewObjectStartOffset ()
static intptr_t	original_top_offset ()
static intptr_t	original_end_offset ()
static Page *	Of (ObjectPtr obj)
static Page *	Of (uword addr)
static intptr_t	card_table_offset ()

Static Public Attributes
static constexpr intptr_t	kSlotsPerCardLog2 = 5
static constexpr intptr_t	kBytesPerCardLog2

Friends
class	CheckStoreBufferVisitor
class	GCCompactor
class	PageSpace
template<bool >
class	ScavengerVisitorBase
class	SemiSpace
class	UnwindingRecords

Detailed Description

Definition at line 61 of file page.h.

Member Enumeration Documentation

PageFlags

enum dart::Page::PageFlags : uword

Enumerator
kExecutable
kLarge
kImage
kVMIsolate
kNew
kEvacuationCandidate

Definition at line 68 of file page.h.

                 : uword {
    kExecutable = 1 << 0,
    kLarge = 1 << 1,
    kImage = 1 << 2,
    kVMIsolate = 1 << 3,
    kNew = 1 << 4,
    kEvacuationCandidate = 1 << 5,
  };

Member Function Documentation

Acquire()

void dart::Page::Acquire ( Thread *  thread )

inline

Definition at line 192 of file page.h.

                               {
    ASSERT(owner_ == nullptr);
    owner_ = thread;
    ASSERT(thread->top() == 0);
    ASSERT(thread->end() == 0);
    thread->set_top(top_);
    thread->set_end(end_);
    thread->set_true_end(end_);
  }

AllocateForwardingPage()

void dart::Page::AllocateForwardingPage

(

)

Definition at line 112 of file compactor.cc.

                                  {
  ASSERT(forwarding_page_ == nullptr);
  ASSERT((object_start() + sizeof(ForwardingPage)) < object_end());
  ASSERT(Utils::IsAligned(sizeof(ForwardingPage), kObjectAlignment));
  top_ -= sizeof(ForwardingPage);
  forwarding_page_ = reinterpret_cast<ForwardingPage*>(top_.load());
}

CachedSize()

intptr_t dart::Page::CachedSize ( )

static

Definition at line 51 of file page.cc.

                          {
  MutexLocker ml(page_cache_mutex);
  return page_cache_size * kPageSize;
}

card_table_offset()

static intptr_t dart::Page::card_table_offset ( )

inlinestatic

Definition at line 160 of file page.h.

{ return OFFSET_OF(Page, card_table_); }

card_table_size()

intptr_t dart::Page::card_table_size ( ) const

inline

Definition at line 156 of file page.h.

                                   {
    return memory_->size() >> kBytesPerCardLog2;
  }

Cleanup()

void dart::Page::Cleanup ( )

static

Definition at line 45 of file page.cc.

                   {
  ClearCache();
  delete page_cache_mutex;
  page_cache_mutex = nullptr;
}

ClearCache()

void dart::Page::ClearCache ( )

static

Definition at line 36 of file page.cc.

                      {
  MutexLocker ml(page_cache_mutex);
  ASSERT(page_cache_size >= 0);
  ASSERT(page_cache_size <= kPageCacheCapacity);
  while (page_cache_size > 0) {
    delete page_cache[--page_cache_size];
  }
}

Contains()

bool dart::Page::Contains ( uword  addr ) const

inline

Definition at line 91 of file page.h.

{ return memory_->Contains(addr); }

EarlyTenure()

void dart::Page::EarlyTenure ( )

inline

Definition at line 186 of file page.h.

{ survivor_end_ = end_; }

end()

uword dart::Page::end ( ) const

inline

Definition at line 90 of file page.h.

{ return memory_->end(); }

forwarding_page()

ForwardingPage * dart::Page::forwarding_page ( ) const

inline

Definition at line 108 of file page.h.

{ return forwarding_page_; }

Init()

void dart::Page::Init ( )

static

Definition at line 31 of file page.cc.

                {
  ASSERT(page_cache_mutex == nullptr);
  page_cache_mutex = new Mutex(NOT_IN_PRODUCT("page_cache_mutex"));
}

is_evacuation_candidate()

bool dart::Page::is_evacuation_candidate ( ) const

inline

Definition at line 82 of file page.h.

                                       {
    return (flags_ & kEvacuationCandidate) != 0;
  }

is_executable()

bool dart::Page::is_executable ( ) const

inline

Definition at line 76 of file page.h.

{ return (flags_ & kExecutable) != 0; }

is_image()

bool dart::Page::is_image ( ) const

inline

Definition at line 78 of file page.h.

{ return (flags_ & kImage) != 0; }

is_large()

bool dart::Page::is_large ( ) const

inline

Definition at line 77 of file page.h.

{ return (flags_ & kLarge) != 0; }

is_new()

bool dart::Page::is_new ( ) const

inline

Definition at line 80 of file page.h.

{ return (flags_ & kNew) != 0; }

is_old()

bool dart::Page::is_old ( ) const

inline

Definition at line 81 of file page.h.

{ return !is_new(); }

is_vm_isolate()

bool dart::Page::is_vm_isolate ( ) const

inline

Definition at line 79 of file page.h.

{ return (flags_ & kVMIsolate) != 0; }

IsCardRemembered()

bool dart::Page::IsCardRemembered ( ObjectPtr const *  slot )

inline

Definition at line 165 of file page.h.

                                               {
    return IsCardRemembered(reinterpret_cast<uword>(slot));
  }

IsResolved()

bool dart::Page::IsResolved ( ) const

inline

Definition at line 248 of file page.h.

{ return top_ == resolved_top_; }

IsSurvivor()

bool dart::Page::IsSurvivor ( uword  raw_addr ) const

inline

Definition at line 247 of file page.h.

{ return raw_addr < survivor_end_; }

new_object_start()

uword dart::Page::new_object_start ( ) const

inline

Definition at line 99 of file page.h.

                                 {
    return memory_->start() + NewObjectStartOffset();
  }

NewObjectStartOffset()

static constexpr intptr_t dart::Page::NewObjectStartOffset ( )

inlinestaticconstexpr

Definition at line 123 of file page.h.

                                                   {
    // Note weaker alignment because the bool/null offset tricks don't apply to
    // new-space.
    return Utils::RoundUp(sizeof(Page), kObjectAlignment,
                          kNewObjectAlignmentOffset);
  }

next()

Page * dart::Page::next ( ) const

inline

Definition at line 86 of file page.h.

{ return next_; }

object_end()

uword dart::Page::object_end ( ) const

inline

Definition at line 102 of file page.h.

                           {
    if (owner_ != nullptr) return owner_->top();
    return top_;
  }

object_start()

uword dart::Page::object_start ( ) const

inline

Definition at line 93 of file page.h.

                             {
    return is_new() ? new_object_start() : old_object_start();
  }

Of() [1/2]

static Page * dart::Page::Of ( ObjectPtr  obj )

inlinestatic

Definition at line 141 of file page.h.

                                 {
    ASSERT(obj->IsHeapObject());
    return reinterpret_cast<Page*>(static_cast<uword>(obj) & kPageMask);
  }

Of() [2/2]

static Page * dart::Page::Of ( uword  addr )

inlinestatic

Definition at line 147 of file page.h.

                              {
    return reinterpret_cast<Page*>(addr & kPageMask);
  }

old_object_start()

uword dart::Page::old_object_start ( ) const

inline

Definition at line 96 of file page.h.

                                 {
    return memory_->start() + OldObjectStartOffset();
  }

OldObjectStartOffset()

static constexpr intptr_t dart::Page::OldObjectStartOffset ( )

inlinestaticconstexpr

Definition at line 119 of file page.h.

                                                   {
    return Utils::RoundUp(sizeof(Page), kObjectStartAlignment,
                          kOldObjectAlignmentOffset);
  }

original_end()

uword dart::Page::original_end ( ) const

inline

Definition at line 134 of file page.h.

{ return end_.load(std::memory_order_relaxed); }

original_end_offset()

static intptr_t dart::Page::original_end_offset ( )

inlinestatic

Definition at line 136 of file page.h.

{ return OFFSET_OF(Page, end_); }

original_top()

uword dart::Page::original_top ( ) const

inline

Definition at line 133 of file page.h.

{ return top_.load(std::memory_order_acquire); }

original_top_offset()

static intptr_t dart::Page::original_top_offset ( )

inlinestatic

Definition at line 135 of file page.h.

{ return OFFSET_OF(Page, top_); }

owner()

Thread * dart::Page::owner ( ) const

inline

Definition at line 179 of file page.h.

{ return owner_; }

promo_candidate_words()

uword dart::Page::promo_candidate_words ( ) const

inline

Definition at line 188 of file page.h.

                                      {
    return (survivor_end_ - object_start()) / kWordSize;
  }

RecordSurvivors()

void dart::Page::RecordSurvivors ( )

inline

Definition at line 182 of file page.h.

{ survivor_end_ = object_end(); }

RegisterUnwindingRecords()

void dart::Page::RegisterUnwindingRecords

(

)

Release() [1/2]

void dart::Page::Release ( )

inline

Definition at line 216 of file page.h.

                 {
    if (owner_ != nullptr) {
      Release(owner_);
    }
  }

Release() [2/2]

intptr_t dart::Page::Release ( Thread *  thread )

inline

Definition at line 201 of file page.h.

                                   {
    ASSERT(owner_ == thread);
    owner_ = nullptr;
    uword old_top = top_;
    uword new_top = thread->top();
    top_.store(new_top, std::memory_order_release);
    thread->set_top(0);
    thread->set_end(0);
    thread->set_true_end(0);
#if !defined(PRODUCT) || defined(FORCE_INCLUDE_SAMPLING_HEAP_PROFILER)
    thread->heap_sampler().HandleReleasedTLAB(Thread::Current());
#endif
    ASSERT(new_top >= old_top);
    return new_top - old_top;
  }

RememberCard()

void dart::Page::RememberCard ( ObjectPtr const *  slot )

inline

Definition at line 162 of file page.h.

                                           {
    RememberCard(reinterpret_cast<uword>(slot));
  }

ResetProgressBar()

void dart::Page::ResetProgressBar

(

)

Definition at line 278 of file page.cc.

                            {
  progress_bar_ = 0;
}

set_next()

void dart::Page::set_next ( Page *  next )

inline

Definition at line 87 of file page.h.

{ next_ = next; }

start()

uword dart::Page::start ( ) const

inline

Definition at line 89 of file page.h.

{ return memory_->start(); }

TryAllocateGC()

uword dart::Page::TryAllocateGC ( intptr_t  size )

inline

Definition at line 222 of file page.h.

                                     {
    ASSERT(owner_ == nullptr);
    uword result = top_;
    uword new_top = result + size;
    if (LIKELY(new_top <= end_)) {
      top_ = new_top;
      return result;
    }
    return 0;
  }

Unallocate()

void dart::Page::Unallocate ( uword  addr, intptr_t  size  )

inline

Definition at line 233 of file page.h.

                                             {
    ASSERT((addr + size) == top_);
 
#if defined(DEBUG)
    uword* cursor = reinterpret_cast<uword*>(addr);
    uword* end = reinterpret_cast<uword*>(addr + size);
    while (cursor < end) {
      *cursor++ = kAllocationCanary;
    }
#endif
 
    top_ -= size;
  }

UnregisterUnwindingRecords()

void dart::Page::UnregisterUnwindingRecords

(

)

used()

intptr_t dart::Page::used ( ) const

inline

Definition at line 106 of file page.h.

{ return object_end() - object_start(); }

VisitObjectPointers()

void dart::Page::VisitObjectPointers

(

ObjectPointerVisitor *

visitor

)

const

Definition at line 196 of file page.cc.

                                                                  {
  ASSERT(Thread::Current()->OwnsGCSafepoint() ||
         (Thread::Current()->task_kind() == Thread::kCompactorTask) ||
         (Thread::Current()->task_kind() == Thread::kMarkerTask));
  NoSafepointScope no_safepoint;
  uword obj_addr = object_start();
  uword end_addr = object_end();
  while (obj_addr < end_addr) {
    ObjectPtr raw_obj = UntaggedObject::FromAddr(obj_addr);
    obj_addr += raw_obj->untag()->VisitPointers(visitor);
  }
  ASSERT(obj_addr == end_addr);
}

VisitObjects()

void dart::Page::VisitObjects

(

ObjectVisitor *

visitor

)

const

Definition at line 173 of file page.cc.

                                                    {
  ASSERT(Thread::Current()->OwnsGCSafepoint());
  NoSafepointScope no_safepoint;
  uword obj_addr = object_start();
  uword end_addr = object_end();
  while (obj_addr < end_addr) {
    ObjectPtr raw_obj = UntaggedObject::FromAddr(obj_addr);
    visitor->VisitObject(raw_obj);
    obj_addr += raw_obj->untag()->HeapSize();
  }
  ASSERT(obj_addr == end_addr);
}

VisitObjectsUnsafe()

void dart::Page::VisitObjectsUnsafe

(

ObjectVisitor *

visitor

)

const

Definition at line 186 of file page.cc.

                                                          {
  uword obj_addr = object_start();
  uword end_addr = object_end();
  while (obj_addr < end_addr) {
    ObjectPtr raw_obj = UntaggedObject::FromAddr(obj_addr);
    visitor->VisitObject(raw_obj);
    obj_addr += raw_obj->untag()->HeapSize();
  }
}

VisitRememberedCards()

void dart::Page::VisitRememberedCards

(

ObjectPointerVisitor *

visitor

)

Definition at line 210 of file page.cc.

                                                             {
  ASSERT(Thread::Current()->OwnsGCSafepoint() ||
         (Thread::Current()->task_kind() == Thread::kScavengerTask));
  NoSafepointScope no_safepoint;
 
  if (card_table_ == nullptr) {
    return;
  }
 
  ArrayPtr obj =
      static_cast<ArrayPtr>(UntaggedObject::FromAddr(object_start()));
  ASSERT(obj->IsArray() || obj->IsImmutableArray());
  ASSERT(obj->untag()->IsCardRemembered());
  CompressedObjectPtr* obj_from = obj->untag()->from();
  CompressedObjectPtr* obj_to =
      obj->untag()->to(Smi::Value(obj->untag()->length()));
  uword heap_base = obj.heap_base();
 
  const size_t size_in_bits = card_table_size();
  const size_t size_in_words =
      Utils::RoundUp(size_in_bits, kBitsPerWord) >> kBitsPerWordLog2;
  for (;;) {
    const size_t word_offset = progress_bar_.fetch_add(1);
    if (word_offset >= size_in_words) break;
 
    uword cell = card_table_[word_offset];
    if (cell == 0) continue;
 
    for (intptr_t bit_offset = 0; bit_offset < kBitsPerWord; bit_offset++) {
      const uword bit_mask = static_cast<uword>(1) << bit_offset;
      if ((cell & bit_mask) == 0) continue;
      const intptr_t i = (word_offset << kBitsPerWordLog2) + bit_offset;
 
      CompressedObjectPtr* card_from =
          reinterpret_cast<CompressedObjectPtr*>(this) +
          (i << kSlotsPerCardLog2);
      CompressedObjectPtr* card_to =
          reinterpret_cast<CompressedObjectPtr*>(card_from) +
          (1 << kSlotsPerCardLog2) - 1;
      // Minus 1 because to is inclusive.
 
      if (card_from < obj_from) {
        // First card overlaps with header.
        card_from = obj_from;
      }
      if (card_to > obj_to) {
        // Last card(s) may extend past the object. Array truncation can make
        // this happen for more than one card.
        card_to = obj_to;
      }
 
      visitor->VisitCompressedPointers(heap_base, card_from, card_to);
 
      bool has_new_target = false;
      for (CompressedObjectPtr* slot = card_from; slot <= card_to; slot++) {
        if ((*slot)->IsNewObjectMayBeSmi()) {
          has_new_target = true;
          break;
        }
      }
      if (!has_new_target) {
        cell ^= bit_mask;
      }
    }
    card_table_[word_offset] = cell;
  }
}

WriteProtect()

void dart::Page::WriteProtect

(

bool

read_only

)

Definition at line 282 of file page.cc.

                                      {
  ASSERT(!is_image());
 
  VirtualMemory::Protection prot;
  if (read_only) {
    if (is_executable()) {
      prot = VirtualMemory::kReadExecute;
    } else {
      prot = VirtualMemory::kReadOnly;
    }
  } else {
    prot = VirtualMemory::kReadWrite;
  }
  memory_->Protect(prot);
}

Friends And Related Symbol Documentation

CheckStoreBufferVisitor

friend class CheckStoreBufferVisitor

friend

Definition at line 319 of file page.h.

GCCompactor

friend class GCCompactor

friend

Definition at line 320 of file page.h.

PageSpace

friend class PageSpace

friend

Definition at line 321 of file page.h.

ScavengerVisitorBase

template<bool >

friend class ScavengerVisitorBase

friend

Definition at line 323 of file page.h.

SemiSpace

friend class SemiSpace

friend

Definition at line 324 of file page.h.

UnwindingRecords

friend class UnwindingRecords

friend

Definition at line 325 of file page.h.

Member Data Documentation

kBytesPerCardLog2

constexpr intptr_t dart::Page::kBytesPerCardLog2

staticconstexpr

Initial value:

=
      kCompressedWordSizeLog2 + kSlotsPerCardLog2

Definition at line 153 of file page.h.

kSlotsPerCardLog2

constexpr intptr_t dart::Page::kSlotsPerCardLog2 = 5

staticconstexpr

Definition at line 152 of file page.h.

---

The documentation for this class was generated from the following files:

• third_party/dart-lang/sdk/runtime/vm/heap/page.h
• third_party/dart-lang/sdk/runtime/vm/heap/compactor.cc
• third_party/dart-lang/sdk/runtime/vm/heap/page.cc