https://github.com/mozilla/gecko-dev
Tip revision: 162b63a813c1d8520882154b58254a2dbdae3709 authored by ffxbld on 16 January 2013, 15:19:02 UTC
Added FENNEC_19_0b2_RELEASE FENNEC_19_0b2_BUILD1 tag(s) for changeset 46305160fb3c. DONTBUILD CLOSED TREE a=release
Added FENNEC_19_0b2_RELEASE FENNEC_19_0b2_BUILD1 tag(s) for changeset 46305160fb3c. DONTBUILD CLOSED TREE a=release
Tip revision: 162b63a
jsgc.cpp
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* vim: set ts=8 sw=4 et tw=78:
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/* JS Mark-and-Sweep Garbage Collector. */
#include "mozilla/Attributes.h"
#include "mozilla/Util.h"
/*
* This code implements a mark-and-sweep garbage collector. The mark phase is
* incremental. Most sweeping is done on a background thread. A GC is divided
* into slices as follows:
*
* Slice 1: Roots pushed onto the mark stack. The mark stack is processed by
* popping an element, marking it, and pushing its children.
* ... JS code runs ...
* Slice 2: More mark stack processing.
* ... JS code runs ...
* Slice n-1: More mark stack processing.
* ... JS code runs ...
* Slice n: Mark stack is completely drained. Some sweeping is done.
* ... JS code runs, remaining sweeping done on background thread ...
*
* When background sweeping finishes the GC is complete.
*
* Incremental GC requires close collaboration with the mutator (i.e., JS code):
*
* 1. During an incremental GC, if a memory location (except a root) is written
* to, then the value it previously held must be marked. Write barriers ensure
* this.
* 2. Any object that is allocated during incremental GC must start out marked.
* 3. Roots are special memory locations that don't need write
* barriers. However, they must be marked in the first slice. Roots are things
* like the C stack and the VM stack, since it would be too expensive to put
* barriers on them.
*/
#include <math.h>
#include <string.h> /* for memset used when DEBUG */
#include "jstypes.h"
#include "jsutil.h"
#include "jsclist.h"
#include "jsprf.h"
#include "jsapi.h"
#include "jsatom.h"
#include "jscompartment.h"
#include "jscrashreport.h"
#include "jscrashformat.h"
#include "jscntxt.h"
#include "jsversion.h"
#include "jsdbgapi.h"
#include "jsexn.h"
#include "jsfun.h"
#include "jsgc.h"
#include "jsinterp.h"
#include "jsiter.h"
#include "jslock.h"
#include "jsnum.h"
#include "jsobj.h"
#include "jsprobes.h"
#include "jsproxy.h"
#include "jsscope.h"
#include "jsscript.h"
#include "jswatchpoint.h"
#include "jsweakmap.h"
#if JS_HAS_XML_SUPPORT
#include "jsxml.h"
#endif
#include "builtin/MapObject.h"
#include "frontend/Parser.h"
#include "gc/Marking.h"
#include "gc/Memory.h"
#include "methodjit/MethodJIT.h"
#include "vm/Debugger.h"
#include "vm/String.h"
#include "ion/IonCode.h"
#ifdef JS_ION
# include "ion/IonMacroAssembler.h"
#include "ion/IonFrameIterator.h"
#endif
#include "jsinterpinlines.h"
#include "jsobjinlines.h"
#include "vm/ScopeObject-inl.h"
#include "vm/String-inl.h"
#ifdef MOZ_VALGRIND
# define JS_VALGRIND
#endif
#ifdef JS_VALGRIND
# include <valgrind/memcheck.h>
#endif
#ifdef XP_WIN
# include "jswin.h"
#else
# include <unistd.h>
#endif
#if JS_TRACE_LOGGING
#include "TraceLogging.h"
#endif
using namespace js;
using namespace js::gc;
using mozilla::ArrayEnd;
using mozilla::DebugOnly;
using mozilla::Maybe;
namespace js {
namespace gc {
/* Perform a Full GC every 20 seconds if MaybeGC is called */
static const uint64_t GC_IDLE_FULL_SPAN = 20 * 1000 * 1000;
/* Increase the IGC marking slice time if we are in highFrequencyGC mode. */
const int IGC_MARK_SLICE_MULTIPLIER = 2;
#ifdef JS_GC_ZEAL
static void
StartVerifyPreBarriers(JSRuntime *rt);
static void
EndVerifyPreBarriers(JSRuntime *rt);
static void
StartVerifyPostBarriers(JSRuntime *rt);
static void
EndVerifyPostBarriers(JSRuntime *rt);
void
FinishVerifier(JSRuntime *rt);
#endif
/* This array should be const, but that doesn't link right under GCC. */
AllocKind slotsToThingKind[] = {
/* 0 */ FINALIZE_OBJECT0, FINALIZE_OBJECT2, FINALIZE_OBJECT2, FINALIZE_OBJECT4,
/* 4 */ FINALIZE_OBJECT4, FINALIZE_OBJECT8, FINALIZE_OBJECT8, FINALIZE_OBJECT8,
/* 8 */ FINALIZE_OBJECT8, FINALIZE_OBJECT12, FINALIZE_OBJECT12, FINALIZE_OBJECT12,
/* 12 */ FINALIZE_OBJECT12, FINALIZE_OBJECT16, FINALIZE_OBJECT16, FINALIZE_OBJECT16,
/* 16 */ FINALIZE_OBJECT16
};
JS_STATIC_ASSERT(JS_ARRAY_LENGTH(slotsToThingKind) == SLOTS_TO_THING_KIND_LIMIT);
const uint32_t Arena::ThingSizes[] = {
sizeof(JSObject), /* FINALIZE_OBJECT0 */
sizeof(JSObject), /* FINALIZE_OBJECT0_BACKGROUND */
sizeof(JSObject_Slots2), /* FINALIZE_OBJECT2 */
sizeof(JSObject_Slots2), /* FINALIZE_OBJECT2_BACKGROUND */
sizeof(JSObject_Slots4), /* FINALIZE_OBJECT4 */
sizeof(JSObject_Slots4), /* FINALIZE_OBJECT4_BACKGROUND */
sizeof(JSObject_Slots8), /* FINALIZE_OBJECT8 */
sizeof(JSObject_Slots8), /* FINALIZE_OBJECT8_BACKGROUND */
sizeof(JSObject_Slots12), /* FINALIZE_OBJECT12 */
sizeof(JSObject_Slots12), /* FINALIZE_OBJECT12_BACKGROUND */
sizeof(JSObject_Slots16), /* FINALIZE_OBJECT16 */
sizeof(JSObject_Slots16), /* FINALIZE_OBJECT16_BACKGROUND */
sizeof(JSScript), /* FINALIZE_SCRIPT */
sizeof(Shape), /* FINALIZE_SHAPE */
sizeof(BaseShape), /* FINALIZE_BASE_SHAPE */
sizeof(types::TypeObject), /* FINALIZE_TYPE_OBJECT */
#if JS_HAS_XML_SUPPORT
sizeof(JSXML), /* FINALIZE_XML */
#endif
sizeof(JSShortString), /* FINALIZE_SHORT_STRING */
sizeof(JSString), /* FINALIZE_STRING */
sizeof(JSExternalString), /* FINALIZE_EXTERNAL_STRING */
sizeof(ion::IonCode), /* FINALIZE_IONCODE */
};
#define OFFSET(type) uint32_t(sizeof(ArenaHeader) + (ArenaSize - sizeof(ArenaHeader)) % sizeof(type))
const uint32_t Arena::FirstThingOffsets[] = {
OFFSET(JSObject), /* FINALIZE_OBJECT0 */
OFFSET(JSObject), /* FINALIZE_OBJECT0_BACKGROUND */
OFFSET(JSObject_Slots2), /* FINALIZE_OBJECT2 */
OFFSET(JSObject_Slots2), /* FINALIZE_OBJECT2_BACKGROUND */
OFFSET(JSObject_Slots4), /* FINALIZE_OBJECT4 */
OFFSET(JSObject_Slots4), /* FINALIZE_OBJECT4_BACKGROUND */
OFFSET(JSObject_Slots8), /* FINALIZE_OBJECT8 */
OFFSET(JSObject_Slots8), /* FINALIZE_OBJECT8_BACKGROUND */
OFFSET(JSObject_Slots12), /* FINALIZE_OBJECT12 */
OFFSET(JSObject_Slots12), /* FINALIZE_OBJECT12_BACKGROUND */
OFFSET(JSObject_Slots16), /* FINALIZE_OBJECT16 */
OFFSET(JSObject_Slots16), /* FINALIZE_OBJECT16_BACKGROUND */
OFFSET(JSScript), /* FINALIZE_SCRIPT */
OFFSET(Shape), /* FINALIZE_SHAPE */
OFFSET(BaseShape), /* FINALIZE_BASE_SHAPE */
OFFSET(types::TypeObject), /* FINALIZE_TYPE_OBJECT */
#if JS_HAS_XML_SUPPORT
OFFSET(JSXML), /* FINALIZE_XML */
#endif
OFFSET(JSShortString), /* FINALIZE_SHORT_STRING */
OFFSET(JSString), /* FINALIZE_STRING */
OFFSET(JSExternalString), /* FINALIZE_EXTERNAL_STRING */
OFFSET(ion::IonCode), /* FINALIZE_IONCODE */
};
#undef OFFSET
/*
* Finalization order for incrementally swept things.
*/
static const AllocKind FinalizePhaseStrings[] = {
FINALIZE_EXTERNAL_STRING
};
static const AllocKind FinalizePhaseScripts[] = {
FINALIZE_SCRIPT
};
static const AllocKind FinalizePhaseShapes[] = {
FINALIZE_SHAPE,
FINALIZE_BASE_SHAPE,
FINALIZE_TYPE_OBJECT
};
static const AllocKind* FinalizePhases[] = {
FinalizePhaseStrings,
FinalizePhaseScripts,
FinalizePhaseShapes
};
static const int FinalizePhaseCount = sizeof(FinalizePhases) / sizeof(AllocKind*);
static const int FinalizePhaseLength[] = {
sizeof(FinalizePhaseStrings) / sizeof(AllocKind),
sizeof(FinalizePhaseScripts) / sizeof(AllocKind),
sizeof(FinalizePhaseShapes) / sizeof(AllocKind)
};
static const gcstats::Phase FinalizePhaseStatsPhase[] = {
gcstats::PHASE_SWEEP_STRING,
gcstats::PHASE_SWEEP_SCRIPT,
gcstats::PHASE_SWEEP_SHAPE
};
/*
* Finalization order for things swept in the background.
*/
static const AllocKind BackgroundPhaseObjects[] = {
FINALIZE_OBJECT0_BACKGROUND,
FINALIZE_OBJECT2_BACKGROUND,
FINALIZE_OBJECT4_BACKGROUND,
FINALIZE_OBJECT8_BACKGROUND,
FINALIZE_OBJECT12_BACKGROUND,
FINALIZE_OBJECT16_BACKGROUND
};
static const AllocKind BackgroundPhaseStrings[] = {
FINALIZE_SHORT_STRING,
FINALIZE_STRING
};
static const AllocKind* BackgroundPhases[] = {
BackgroundPhaseObjects,
BackgroundPhaseStrings
};
static const int BackgroundPhaseCount = sizeof(BackgroundPhases) / sizeof(AllocKind*);
static const int BackgroundPhaseLength[] = {
sizeof(BackgroundPhaseObjects) / sizeof(AllocKind),
sizeof(BackgroundPhaseStrings) / sizeof(AllocKind)
};
#ifdef DEBUG
void
ArenaHeader::checkSynchronizedWithFreeList() const
{
/*
* Do not allow to access the free list when its real head is still stored
* in FreeLists and is not synchronized with this one.
*/
JS_ASSERT(allocated());
/*
* We can be called from the background finalization thread when the free
* list in the compartment can mutate at any moment. We cannot do any
* checks in this case.
*/
if (!compartment->rt->isHeapBusy())
return;
FreeSpan firstSpan = FreeSpan::decodeOffsets(arenaAddress(), firstFreeSpanOffsets);
if (firstSpan.isEmpty())
return;
const FreeSpan *list = compartment->arenas.getFreeList(getAllocKind());
if (list->isEmpty() || firstSpan.arenaAddress() != list->arenaAddress())
return;
/*
* Here this arena has free things, FreeList::lists[thingKind] is not
* empty and also points to this arena. Thus they must the same.
*/
JS_ASSERT(firstSpan.isSameNonEmptySpan(list));
}
#endif
/* static */ void
Arena::staticAsserts()
{
JS_STATIC_ASSERT(sizeof(Arena) == ArenaSize);
JS_STATIC_ASSERT(JS_ARRAY_LENGTH(ThingSizes) == FINALIZE_LIMIT);
JS_STATIC_ASSERT(JS_ARRAY_LENGTH(FirstThingOffsets) == FINALIZE_LIMIT);
}
template<typename T>
inline bool
Arena::finalize(FreeOp *fop, AllocKind thingKind, size_t thingSize)
{
/* Enforce requirements on size of T. */
JS_ASSERT(thingSize % Cell::CellSize == 0);
JS_ASSERT(thingSize <= 255);
JS_ASSERT(aheader.allocated());
JS_ASSERT(thingKind == aheader.getAllocKind());
JS_ASSERT(thingSize == aheader.getThingSize());
JS_ASSERT(!aheader.hasDelayedMarking);
JS_ASSERT(!aheader.markOverflow);
JS_ASSERT(!aheader.allocatedDuringIncremental);
uintptr_t thing = thingsStart(thingKind);
uintptr_t lastByte = thingsEnd() - 1;
FreeSpan nextFree(aheader.getFirstFreeSpan());
nextFree.checkSpan();
FreeSpan newListHead;
FreeSpan *newListTail = &newListHead;
uintptr_t newFreeSpanStart = 0;
bool allClear = true;
DebugOnly<size_t> nmarked = 0;
for (;; thing += thingSize) {
JS_ASSERT(thing <= lastByte + 1);
if (thing == nextFree.first) {
JS_ASSERT(nextFree.last <= lastByte);
if (nextFree.last == lastByte)
break;
JS_ASSERT(Arena::isAligned(nextFree.last, thingSize));
if (!newFreeSpanStart)
newFreeSpanStart = thing;
thing = nextFree.last;
nextFree = *nextFree.nextSpan();
nextFree.checkSpan();
} else {
T *t = reinterpret_cast<T *>(thing);
if (t->isMarked()) {
allClear = false;
nmarked++;
if (newFreeSpanStart) {
JS_ASSERT(thing >= thingsStart(thingKind) + thingSize);
newListTail->first = newFreeSpanStart;
newListTail->last = thing - thingSize;
newListTail = newListTail->nextSpanUnchecked(thingSize);
newFreeSpanStart = 0;
}
} else {
if (!newFreeSpanStart)
newFreeSpanStart = thing;
t->finalize(fop);
JS_POISON(t, JS_FREE_PATTERN, thingSize);
}
}
}
if (allClear) {
JS_ASSERT(newListTail == &newListHead);
JS_ASSERT(newFreeSpanStart == thingsStart(thingKind));
return true;
}
newListTail->first = newFreeSpanStart ? newFreeSpanStart : nextFree.first;
JS_ASSERT(Arena::isAligned(newListTail->first, thingSize));
newListTail->last = lastByte;
#ifdef DEBUG
size_t nfree = 0;
for (const FreeSpan *span = &newListHead; span != newListTail; span = span->nextSpan()) {
span->checkSpan();
JS_ASSERT(Arena::isAligned(span->first, thingSize));
JS_ASSERT(Arena::isAligned(span->last, thingSize));
nfree += (span->last - span->first) / thingSize + 1;
JS_ASSERT(nfree + nmarked <= thingsPerArena(thingSize));
}
nfree += (newListTail->last + 1 - newListTail->first) / thingSize;
JS_ASSERT(nfree + nmarked == thingsPerArena(thingSize));
#endif
aheader.setFirstFreeSpan(&newListHead);
return false;
}
/*
* Insert an arena into the list in appropriate position and update the cursor
* to ensure that any arena before the cursor is full.
*/
void ArenaList::insert(ArenaHeader *a)
{
JS_ASSERT(a);
JS_ASSERT_IF(!head, cursor == &head);
a->next = *cursor;
*cursor = a;
if (!a->hasFreeThings())
cursor = &a->next;
}
template<typename T>
inline bool
FinalizeTypedArenas(FreeOp *fop,
ArenaHeader **src,
ArenaList &dest,
AllocKind thingKind,
SliceBudget &budget)
{
/*
* Finalize arenas from src list, releasing empty arenas and inserting the
* others into dest in an appropriate position.
*/
size_t thingSize = Arena::thingSize(thingKind);
while (ArenaHeader *aheader = *src) {
*src = aheader->next;
bool allClear = aheader->getArena()->finalize<T>(fop, thingKind, thingSize);
if (allClear)
aheader->chunk()->releaseArena(aheader);
else
dest.insert(aheader);
budget.step(Arena::thingsPerArena(thingSize));
if (budget.isOverBudget())
return false;
}
return true;
}
/*
* Finalize the list. On return al->cursor points to the first non-empty arena
* after the al->head.
*/
static bool
FinalizeArenas(FreeOp *fop,
ArenaHeader **src,
ArenaList &dest,
AllocKind thingKind,
SliceBudget &budget)
{
switch(thingKind) {
case FINALIZE_OBJECT0:
case FINALIZE_OBJECT0_BACKGROUND:
case FINALIZE_OBJECT2:
case FINALIZE_OBJECT2_BACKGROUND:
case FINALIZE_OBJECT4:
case FINALIZE_OBJECT4_BACKGROUND:
case FINALIZE_OBJECT8:
case FINALIZE_OBJECT8_BACKGROUND:
case FINALIZE_OBJECT12:
case FINALIZE_OBJECT12_BACKGROUND:
case FINALIZE_OBJECT16:
case FINALIZE_OBJECT16_BACKGROUND:
return FinalizeTypedArenas<JSObject>(fop, src, dest, thingKind, budget);
case FINALIZE_SCRIPT:
return FinalizeTypedArenas<JSScript>(fop, src, dest, thingKind, budget);
case FINALIZE_SHAPE:
return FinalizeTypedArenas<Shape>(fop, src, dest, thingKind, budget);
case FINALIZE_BASE_SHAPE:
return FinalizeTypedArenas<BaseShape>(fop, src, dest, thingKind, budget);
case FINALIZE_TYPE_OBJECT:
return FinalizeTypedArenas<types::TypeObject>(fop, src, dest, thingKind, budget);
#if JS_HAS_XML_SUPPORT
case FINALIZE_XML:
return FinalizeTypedArenas<JSXML>(fop, src, dest, thingKind, budget);
#endif
case FINALIZE_STRING:
return FinalizeTypedArenas<JSString>(fop, src, dest, thingKind, budget);
case FINALIZE_SHORT_STRING:
return FinalizeTypedArenas<JSShortString>(fop, src, dest, thingKind, budget);
case FINALIZE_EXTERNAL_STRING:
return FinalizeTypedArenas<JSExternalString>(fop, src, dest, thingKind, budget);
case FINALIZE_IONCODE:
#ifdef JS_ION
return FinalizeTypedArenas<ion::IonCode>(fop, src, dest, thingKind, budget);
#endif
default:
JS_NOT_REACHED("Invalid alloc kind");
return true;
}
}
static inline Chunk *
AllocChunk() {
return static_cast<Chunk *>(MapAlignedPages(ChunkSize, ChunkSize));
}
static inline void
FreeChunk(Chunk *p) {
UnmapPages(static_cast<void *>(p), ChunkSize);
}
inline bool
ChunkPool::wantBackgroundAllocation(JSRuntime *rt) const
{
/*
* To minimize memory waste we do not want to run the background chunk
* allocation if we have empty chunks or when the runtime needs just few
* of them.
*/
return rt->gcHelperThread.canBackgroundAllocate() &&
emptyCount == 0 &&
rt->gcChunkSet.count() >= 4;
}
/* Must be called with the GC lock taken. */
inline Chunk *
ChunkPool::get(JSRuntime *rt)
{
JS_ASSERT(this == &rt->gcChunkPool);
Chunk *chunk = emptyChunkListHead;
if (chunk) {
JS_ASSERT(emptyCount);
emptyChunkListHead = chunk->info.next;
--emptyCount;
} else {
JS_ASSERT(!emptyCount);
chunk = Chunk::allocate(rt);
if (!chunk)
return NULL;
JS_ASSERT(chunk->info.numArenasFreeCommitted == ArenasPerChunk);
rt->gcNumArenasFreeCommitted += ArenasPerChunk;
}
JS_ASSERT(chunk->unused());
JS_ASSERT(!rt->gcChunkSet.has(chunk));
if (wantBackgroundAllocation(rt))
rt->gcHelperThread.startBackgroundAllocationIfIdle();
return chunk;
}
/* Must be called either during the GC or with the GC lock taken. */
inline void
ChunkPool::put(Chunk *chunk)
{
chunk->info.age = 0;
chunk->info.next = emptyChunkListHead;
emptyChunkListHead = chunk;
emptyCount++;
}
/* Must be called either during the GC or with the GC lock taken. */
Chunk *
ChunkPool::expire(JSRuntime *rt, bool releaseAll)
{
JS_ASSERT(this == &rt->gcChunkPool);
/*
* Return old empty chunks to the system while preserving the order of
* other chunks in the list. This way, if the GC runs several times
* without emptying the list, the older chunks will stay at the tail
* and are more likely to reach the max age.
*/
Chunk *freeList = NULL;
for (Chunk **chunkp = &emptyChunkListHead; *chunkp; ) {
JS_ASSERT(emptyCount);
Chunk *chunk = *chunkp;
JS_ASSERT(chunk->unused());
JS_ASSERT(!rt->gcChunkSet.has(chunk));
JS_ASSERT(chunk->info.age <= MAX_EMPTY_CHUNK_AGE);
if (releaseAll || chunk->info.age == MAX_EMPTY_CHUNK_AGE) {
*chunkp = chunk->info.next;
--emptyCount;
chunk->prepareToBeFreed(rt);
chunk->info.next = freeList;
freeList = chunk;
} else {
/* Keep the chunk but increase its age. */
++chunk->info.age;
chunkp = &chunk->info.next;
}
}
JS_ASSERT_IF(releaseAll, !emptyCount);
return freeList;
}
static void
FreeChunkList(Chunk *chunkListHead)
{
while (Chunk *chunk = chunkListHead) {
JS_ASSERT(!chunk->info.numArenasFreeCommitted);
chunkListHead = chunk->info.next;
FreeChunk(chunk);
}
}
void
ChunkPool::expireAndFree(JSRuntime *rt, bool releaseAll)
{
FreeChunkList(expire(rt, releaseAll));
}
/* static */ Chunk *
Chunk::allocate(JSRuntime *rt)
{
Chunk *chunk = static_cast<Chunk *>(AllocChunk());
#ifdef JSGC_ROOT_ANALYSIS
// Our poison pointers are not guaranteed to be invalid on 64-bit
// architectures, and often are valid. We can't just reserve the full
// poison range, because it might already have been taken up by something
// else (shared library, previous allocation). So we'll just loop and
// discard poison pointers until we get something valid.
//
// This leaks all of these poisoned pointers. It would be better if they
// were marked as uncommitted, but it's a little complicated to avoid
// clobbering pre-existing unrelated mappings.
while (IsPoisonedPtr(chunk))
chunk = static_cast<Chunk *>(AllocChunk());
#endif
if (!chunk)
return NULL;
chunk->init();
rt->gcStats.count(gcstats::STAT_NEW_CHUNK);
return chunk;
}
/* Must be called with the GC lock taken. */
/* static */ inline void
Chunk::release(JSRuntime *rt, Chunk *chunk)
{
JS_ASSERT(chunk);
chunk->prepareToBeFreed(rt);
FreeChunk(chunk);
}
inline void
Chunk::prepareToBeFreed(JSRuntime *rt)
{
JS_ASSERT(rt->gcNumArenasFreeCommitted >= info.numArenasFreeCommitted);
rt->gcNumArenasFreeCommitted -= info.numArenasFreeCommitted;
rt->gcStats.count(gcstats::STAT_DESTROY_CHUNK);
#ifdef DEBUG
/*
* Let FreeChunkList detect a missing prepareToBeFreed call before it
* frees chunk.
*/
info.numArenasFreeCommitted = 0;
#endif
}
void
Chunk::init()
{
JS_POISON(this, JS_FREE_PATTERN, ChunkSize);
/*
* We clear the bitmap to guard against xpc_IsGrayGCThing being called on
* uninitialized data, which would happen before the first GC cycle.
*/
bitmap.clear();
/* Initialize the arena tracking bitmap. */
decommittedArenas.clear(false);
/* Initialize the chunk info. */
info.freeArenasHead = &arenas[0].aheader;
info.lastDecommittedArenaOffset = 0;
info.numArenasFree = ArenasPerChunk;
info.numArenasFreeCommitted = ArenasPerChunk;
info.age = 0;
/* Initialize the arena header state. */
for (unsigned i = 0; i < ArenasPerChunk; i++) {
arenas[i].aheader.setAsNotAllocated();
arenas[i].aheader.next = (i + 1 < ArenasPerChunk)
? &arenas[i + 1].aheader
: NULL;
}
/* The rest of info fields are initialized in PickChunk. */
}
inline Chunk **
GetAvailableChunkList(JSCompartment *comp)
{
JSRuntime *rt = comp->rt;
return comp->isSystemCompartment
? &rt->gcSystemAvailableChunkListHead
: &rt->gcUserAvailableChunkListHead;
}
inline void
Chunk::addToAvailableList(JSCompartment *comp)
{
insertToAvailableList(GetAvailableChunkList(comp));
}
inline void
Chunk::insertToAvailableList(Chunk **insertPoint)
{
JS_ASSERT(hasAvailableArenas());
JS_ASSERT(!info.prevp);
JS_ASSERT(!info.next);
info.prevp = insertPoint;
Chunk *insertBefore = *insertPoint;
if (insertBefore) {
JS_ASSERT(insertBefore->info.prevp == insertPoint);
insertBefore->info.prevp = &info.next;
}
info.next = insertBefore;
*insertPoint = this;
}
inline void
Chunk::removeFromAvailableList()
{
JS_ASSERT(info.prevp);
*info.prevp = info.next;
if (info.next) {
JS_ASSERT(info.next->info.prevp == &info.next);
info.next->info.prevp = info.prevp;
}
info.prevp = NULL;
info.next = NULL;
}
/*
* Search for and return the next decommitted Arena. Our goal is to keep
* lastDecommittedArenaOffset "close" to a free arena. We do this by setting
* it to the most recently freed arena when we free, and forcing it to
* the last alloc + 1 when we allocate.
*/
uint32_t
Chunk::findDecommittedArenaOffset()
{
/* Note: lastFreeArenaOffset can be past the end of the list. */
for (unsigned i = info.lastDecommittedArenaOffset; i < ArenasPerChunk; i++)
if (decommittedArenas.get(i))
return i;
for (unsigned i = 0; i < info.lastDecommittedArenaOffset; i++)
if (decommittedArenas.get(i))
return i;
JS_NOT_REACHED("No decommitted arenas found.");
return -1;
}
ArenaHeader *
Chunk::fetchNextDecommittedArena()
{
JS_ASSERT(info.numArenasFreeCommitted == 0);
JS_ASSERT(info.numArenasFree > 0);
unsigned offset = findDecommittedArenaOffset();
info.lastDecommittedArenaOffset = offset + 1;
--info.numArenasFree;
decommittedArenas.unset(offset);
Arena *arena = &arenas[offset];
MarkPagesInUse(arena, ArenaSize);
arena->aheader.setAsNotAllocated();
return &arena->aheader;
}
inline ArenaHeader *
Chunk::fetchNextFreeArena(JSRuntime *rt)
{
JS_ASSERT(info.numArenasFreeCommitted > 0);
JS_ASSERT(info.numArenasFreeCommitted <= info.numArenasFree);
JS_ASSERT(info.numArenasFreeCommitted <= rt->gcNumArenasFreeCommitted);
ArenaHeader *aheader = info.freeArenasHead;
info.freeArenasHead = aheader->next;
--info.numArenasFreeCommitted;
--info.numArenasFree;
--rt->gcNumArenasFreeCommitted;
return aheader;
}
ArenaHeader *
Chunk::allocateArena(JSCompartment *comp, AllocKind thingKind)
{
JS_ASSERT(hasAvailableArenas());
JSRuntime *rt = comp->rt;
JS_ASSERT(rt->gcBytes <= rt->gcMaxBytes);
if (rt->gcMaxBytes - rt->gcBytes < ArenaSize)
return NULL;
ArenaHeader *aheader = JS_LIKELY(info.numArenasFreeCommitted > 0)
? fetchNextFreeArena(rt)
: fetchNextDecommittedArena();
aheader->init(comp, thingKind);
if (JS_UNLIKELY(!hasAvailableArenas()))
removeFromAvailableList();
Probes::resizeHeap(comp, rt->gcBytes, rt->gcBytes + ArenaSize);
rt->gcBytes += ArenaSize;
comp->gcBytes += ArenaSize;
if (comp->gcBytes >= comp->gcTriggerBytes)
TriggerCompartmentGC(comp, gcreason::ALLOC_TRIGGER);
return aheader;
}
inline void
Chunk::addArenaToFreeList(JSRuntime *rt, ArenaHeader *aheader)
{
JS_ASSERT(!aheader->allocated());
aheader->next = info.freeArenasHead;
info.freeArenasHead = aheader;
++info.numArenasFreeCommitted;
++info.numArenasFree;
++rt->gcNumArenasFreeCommitted;
}
void
Chunk::releaseArena(ArenaHeader *aheader)
{
JS_ASSERT(aheader->allocated());
JS_ASSERT(!aheader->hasDelayedMarking);
JSCompartment *comp = aheader->compartment;
JSRuntime *rt = comp->rt;
AutoLockGC maybeLock;
if (rt->gcHelperThread.sweeping())
maybeLock.lock(rt);
Probes::resizeHeap(comp, rt->gcBytes, rt->gcBytes - ArenaSize);
JS_ASSERT(rt->gcBytes >= ArenaSize);
JS_ASSERT(comp->gcBytes >= ArenaSize);
if (rt->gcHelperThread.sweeping())
comp->reduceGCTriggerBytes(comp->gcHeapGrowthFactor * ArenaSize);
rt->gcBytes -= ArenaSize;
comp->gcBytes -= ArenaSize;
aheader->setAsNotAllocated();
addArenaToFreeList(rt, aheader);
if (info.numArenasFree == 1) {
JS_ASSERT(!info.prevp);
JS_ASSERT(!info.next);
addToAvailableList(comp);
} else if (!unused()) {
JS_ASSERT(info.prevp);
} else {
rt->gcChunkSet.remove(this);
removeFromAvailableList();
rt->gcChunkPool.put(this);
}
}
} /* namespace gc */
} /* namespace js */
/* The caller must hold the GC lock. */
static Chunk *
PickChunk(JSCompartment *comp)
{
JSRuntime *rt = comp->rt;
Chunk **listHeadp = GetAvailableChunkList(comp);
Chunk *chunk = *listHeadp;
if (chunk)
return chunk;
chunk = rt->gcChunkPool.get(rt);
if (!chunk)
return NULL;
rt->gcChunkAllocationSinceLastGC = true;
/*
* FIXME bug 583732 - chunk is newly allocated and cannot be present in
* the table so using ordinary lookupForAdd is suboptimal here.
*/
GCChunkSet::AddPtr p = rt->gcChunkSet.lookupForAdd(chunk);
JS_ASSERT(!p);
if (!rt->gcChunkSet.add(p, chunk)) {
Chunk::release(rt, chunk);
return NULL;
}
chunk->info.prevp = NULL;
chunk->info.next = NULL;
chunk->addToAvailableList(comp);
return chunk;
}
/* Lifetime for type sets attached to scripts containing observed types. */
static const int64_t JIT_SCRIPT_RELEASE_TYPES_INTERVAL = 60 * 1000 * 1000;
JSBool
js_InitGC(JSRuntime *rt, uint32_t maxbytes)
{
if (!rt->gcChunkSet.init(INITIAL_CHUNK_CAPACITY))
return false;
if (!rt->gcRootsHash.init(256))
return false;
if (!rt->gcLocksHash.init(256))
return false;
#ifdef JS_THREADSAFE
rt->gcLock = PR_NewLock();
if (!rt->gcLock)
return false;
#endif
if (!rt->gcHelperThread.init())
return false;
/*
* Separate gcMaxMallocBytes from gcMaxBytes but initialize to maxbytes
* for default backward API compatibility.
*/
rt->gcMaxBytes = maxbytes;
rt->setGCMaxMallocBytes(maxbytes);
#ifndef JS_MORE_DETERMINISTIC
rt->gcJitReleaseTime = PRMJ_Now() + JIT_SCRIPT_RELEASE_TYPES_INTERVAL;
#endif
return true;
}
namespace js {
inline bool
InFreeList(ArenaHeader *aheader, uintptr_t addr)
{
if (!aheader->hasFreeThings())
return false;
FreeSpan firstSpan(aheader->getFirstFreeSpan());
for (const FreeSpan *span = &firstSpan;;) {
/* If the thing comes fore the current span, it's not free. */
if (addr < span->first)
return false;
/*
* If we find it inside the span, it's dead. We use here "<=" and not
* "<" even for the last span as we know that thing is inside the
* arena. Thus for the last span thing < span->end.
*/
if (addr <= span->last)
return true;
/*
* The last possible empty span is an the end of the arena. Here
* span->end < thing < thingsEnd and so we must have more spans.
*/
span = span->nextSpan();
}
}
#ifdef JSGC_USE_EXACT_ROOTING
static inline void
MarkExactStackRooter(JSTracer *trc, Rooted<void*> rooter, ThingRootKind kind)
{
void **addr = (void **)rooter->address();
if (!*addr)
return;
switch (kind) {
case THING_ROOT_OBJECT: MarkObjectRoot(trc, (JSObject **)addr, "exact-object"); break;
case THING_ROOT_STRING: MarkStringRoot(trc, (JSSTring **)addr, "exact-string"); break;
case THING_ROOT_SCRIPT: MarkScriptRoot(trc, (JSScript **)addr, "exact-script"); break;
case THING_ROOT_SHAPE: MarkShapeRoot(trc, (Shape **)addr, "exact-shape"); break;
case THING_ROOT_BASE_SHAPE: MarkBaseShapeRoot(trc, (BaseShape **)addr, "exact-baseshape"); break;
case THING_ROOT_TYPE: MarkTypeRoot(trc, (types::Type *)addr, "exact-type"); break;
case THING_ROOT_TYPE_OBJECT: MarkTypeObjectRoot(trc, (types::TypeObject **)addr, "exact-typeobject"); break;
case THING_ROOT_VALUE: MarkValueRoot(trc, (Value *)addr, "exact-value"); break;
case THING_ROOT_ID: MarkIdRoot(trc, (jsid *)addr, "exact-id"); break;
case THING_ROOT_PROPERTY_ID: MarkIdRoot(trc, &((js::PropertyId *)addr)->asId(), "exact-propertyid"); break;
case THING_ROOT_BINDINGS: ((Bindings *)addr)->trace(trc); break;
default: JS_NOT_REACHED("Invalid THING_ROOT kind"); break;
}
}
static inline void
MarkExactStackRooters(JSTracer *trc, Rooted<void*> rooter, ThingRootKind kind)
{
Rooted<void*> *rooter = cx->thingGCRooters[i];
while (rooter) {
MarkExactStackRoot(trc, rooter, ThingRootKind(i));
rooter = rooter->previous();
}
}
static void
MarkExactStackRoots(JSTracer *trc)
{
for (unsigned i = 0; i < THING_ROOT_LIMIT; i++) {
for (ContextIter cx(trc->runtime); !cx.done(); cx.next()) {
MarkExactStackRooters(trc, cx->thingGCRooters[i], ThingRootKind(i));
}
MarkExactStackRooters(trc, rt->mainThread.thingGCRooters[i], ThingRootKind(i));
}
}
#endif /* JSGC_USE_EXACT_ROOTING */
enum ConservativeGCTest
{
CGCT_VALID,
CGCT_LOWBITSET, /* excluded because one of the low bits was set */
CGCT_NOTARENA, /* not within arena range in a chunk */
CGCT_OTHERCOMPARTMENT, /* in another compartment */
CGCT_NOTCHUNK, /* not within a valid chunk */
CGCT_FREEARENA, /* within arena containing only free things */
CGCT_NOTLIVE, /* gcthing is not allocated */
CGCT_END
};
/*
* Tests whether w is a (possibly dead) GC thing. Returns CGCT_VALID and
* details about the thing if so. On failure, returns the reason for rejection.
*/
inline ConservativeGCTest
IsAddressableGCThing(JSRuntime *rt, uintptr_t w,
bool skipUncollectedCompartments,
gc::AllocKind *thingKindPtr,
ArenaHeader **arenaHeader,
void **thing)
{
/*
* We assume that the compiler never uses sub-word alignment to store
* pointers and does not tag pointers on its own. Additionally, the value
* representation for all values and the jsid representation for GC-things
* do not touch the low two bits. Thus any word with the low two bits set
* is not a valid GC-thing.
*/
JS_STATIC_ASSERT(JSID_TYPE_STRING == 0 && JSID_TYPE_OBJECT == 4);
if (w & 0x3)
return CGCT_LOWBITSET;
/*
* An object jsid has its low bits tagged. In the value representation on
* 64-bit, the high bits are tagged.
*/
const uintptr_t JSID_PAYLOAD_MASK = ~uintptr_t(JSID_TYPE_MASK);
#if JS_BITS_PER_WORD == 32
uintptr_t addr = w & JSID_PAYLOAD_MASK;
#elif JS_BITS_PER_WORD == 64
uintptr_t addr = w & JSID_PAYLOAD_MASK & JSVAL_PAYLOAD_MASK;
#endif
Chunk *chunk = Chunk::fromAddress(addr);
if (!rt->gcChunkSet.has(chunk))
return CGCT_NOTCHUNK;
/*
* We query for pointers outside the arena array after checking for an
* allocated chunk. Such pointers are rare and we want to reject them
* after doing more likely rejections.
*/
if (!Chunk::withinArenasRange(addr))
return CGCT_NOTARENA;
/* If the arena is not currently allocated, don't access the header. */
size_t arenaOffset = Chunk::arenaIndex(addr);
if (chunk->decommittedArenas.get(arenaOffset))
return CGCT_FREEARENA;
ArenaHeader *aheader = &chunk->arenas[arenaOffset].aheader;
if (!aheader->allocated())
return CGCT_FREEARENA;
if (skipUncollectedCompartments && !aheader->compartment->isCollecting())
return CGCT_OTHERCOMPARTMENT;
AllocKind thingKind = aheader->getAllocKind();
uintptr_t offset = addr & ArenaMask;
uintptr_t minOffset = Arena::firstThingOffset(thingKind);
if (offset < minOffset)
return CGCT_NOTARENA;
/* addr can point inside the thing so we must align the address. */
uintptr_t shift = (offset - minOffset) % Arena::thingSize(thingKind);
addr -= shift;
if (thing)
*thing = reinterpret_cast<void *>(addr);
if (arenaHeader)
*arenaHeader = aheader;
if (thingKindPtr)
*thingKindPtr = thingKind;
return CGCT_VALID;
}
/*
* Returns CGCT_VALID and mark it if the w can be a live GC thing and sets
* thingKind accordingly. Otherwise returns the reason for rejection.
*/
inline ConservativeGCTest
MarkIfGCThingWord(JSTracer *trc, uintptr_t w)
{
void *thing;
ArenaHeader *aheader;
AllocKind thingKind;
ConservativeGCTest status =
IsAddressableGCThing(trc->runtime, w, IS_GC_MARKING_TRACER(trc),
&thingKind, &aheader, &thing);
if (status != CGCT_VALID)
return status;
/*
* Check if the thing is free. We must use the list of free spans as at
* this point we no longer have the mark bits from the previous GC run and
* we must account for newly allocated things.
*/
if (InFreeList(aheader, uintptr_t(thing)))
return CGCT_NOTLIVE;
JSGCTraceKind traceKind = MapAllocToTraceKind(thingKind);
#ifdef DEBUG
const char pattern[] = "machine_stack %p";
char nameBuf[sizeof(pattern) - 2 + sizeof(thing) * 2];
JS_snprintf(nameBuf, sizeof(nameBuf), pattern, thing);
JS_SET_TRACING_NAME(trc, nameBuf);
#endif
JS_SET_TRACING_LOCATION(trc, (void *)w);
void *tmp = thing;
MarkKind(trc, &tmp, traceKind);
JS_ASSERT(tmp == thing);
#ifdef DEBUG
if (trc->runtime->gcIncrementalState == MARK_ROOTS)
trc->runtime->mainThread.gcSavedRoots.append(
PerThreadData::SavedGCRoot(thing, traceKind));
#endif
return CGCT_VALID;
}
static void
MarkWordConservatively(JSTracer *trc, uintptr_t w)
{
/*
* The conservative scanner may access words that valgrind considers as
* undefined. To avoid false positives and not to alter valgrind view of
* the memory we make as memcheck-defined the argument, a copy of the
* original word. See bug 572678.
*/
#ifdef JS_VALGRIND
JS_SILENCE_UNUSED_VALUE_IN_EXPR(VALGRIND_MAKE_MEM_DEFINED(&w, sizeof(w)));
#endif
MarkIfGCThingWord(trc, w);
}
MOZ_ASAN_BLACKLIST
static void
MarkRangeConservatively(JSTracer *trc, const uintptr_t *begin, const uintptr_t *end)
{
JS_ASSERT(begin <= end);
for (const uintptr_t *i = begin; i < end; ++i)
MarkWordConservatively(trc, *i);
}
#ifndef JSGC_USE_EXACT_ROOTING
static void
MarkRangeConservativelyAndSkipIon(JSTracer *trc, JSRuntime *rt, const uintptr_t *begin, const uintptr_t *end)
{
const uintptr_t *i = begin;
#if JS_STACK_GROWTH_DIRECTION < 0 && defined(JS_ION)
// Walk only regions in between Ion activations. Note that non-volatile
// registers are spilled to the stack before the entry Ion frame, ensuring
// that the conservative scanner will still see them.
for (ion::IonActivationIterator ion(rt); ion.more(); ++ion) {
uintptr_t *ionMin, *ionEnd;
ion.ionStackRange(ionMin, ionEnd);
MarkRangeConservatively(trc, i, ionMin);
i = ionEnd;
}
#endif
// Mark everything after the most recent Ion activation.
MarkRangeConservatively(trc, i, end);
}
static JS_NEVER_INLINE void
MarkConservativeStackRoots(JSTracer *trc, bool useSavedRoots)
{
JSRuntime *rt = trc->runtime;
#ifdef DEBUG
if (useSavedRoots) {
for (PerThreadData::SavedGCRoot *root = rt->mainThread.gcSavedRoots.begin();
root != rt->mainThread.gcSavedRoots.end();
root++)
{
JS_SET_TRACING_NAME(trc, "cstack");
MarkKind(trc, &root->thing, root->kind);
}
return;
}
if (rt->gcIncrementalState == MARK_ROOTS)
rt->mainThread.gcSavedRoots.clearAndFree();
#endif
ConservativeGCData *cgcd = &rt->conservativeGC;
if (!cgcd->hasStackToScan()) {
#ifdef JS_THREADSAFE
JS_ASSERT(!rt->requestDepth);
#endif
return;
}
uintptr_t *stackMin, *stackEnd;
#if JS_STACK_GROWTH_DIRECTION > 0
stackMin = rt->nativeStackBase;
stackEnd = cgcd->nativeStackTop;
#else
stackMin = cgcd->nativeStackTop + 1;
stackEnd = reinterpret_cast<uintptr_t *>(rt->nativeStackBase);
#endif
JS_ASSERT(stackMin <= stackEnd);
MarkRangeConservativelyAndSkipIon(trc, rt, stackMin, stackEnd);
MarkRangeConservatively(trc, cgcd->registerSnapshot.words,
ArrayEnd(cgcd->registerSnapshot.words));
}
#endif /* JSGC_USE_EXACT_ROOTING */
void
MarkStackRangeConservatively(JSTracer *trc, Value *beginv, Value *endv)
{
const uintptr_t *begin = beginv->payloadUIntPtr();
const uintptr_t *end = endv->payloadUIntPtr();
#ifdef JS_NUNBOX32
/*
* With 64-bit jsvals on 32-bit systems, we can optimize a bit by
* scanning only the payloads.
*/
JS_ASSERT(begin <= end);
for (const uintptr_t *i = begin; i < end; i += sizeof(Value) / sizeof(uintptr_t))
MarkWordConservatively(trc, *i);
#else
MarkRangeConservatively(trc, begin, end);
#endif
}
JS_NEVER_INLINE void
ConservativeGCData::recordStackTop()
{
/* Update the native stack pointer if it points to a bigger stack. */
uintptr_t dummy;
nativeStackTop = &dummy;
/*
* To record and update the register snapshot for the conservative scanning
* with the latest values we use setjmp.
*/
#if defined(_MSC_VER)
# pragma warning(push)
# pragma warning(disable: 4611)
#endif
(void) setjmp(registerSnapshot.jmpbuf);
#if defined(_MSC_VER)
# pragma warning(pop)
#endif
}
static void
RecordNativeStackTopForGC(JSRuntime *rt)
{
ConservativeGCData *cgcd = &rt->conservativeGC;
#ifdef JS_THREADSAFE
/* Record the stack top here only if we are called from a request. */
if (!rt->requestDepth)
return;
#endif
cgcd->recordStackTop();
}
} /* namespace js */
void
js_FinishGC(JSRuntime *rt)
{
/*
* Wait until the background finalization stops and the helper thread
* shuts down before we forcefully release any remaining GC memory.
*/
rt->gcHelperThread.finish();
#ifdef JS_GC_ZEAL
/* Free memory associated with GC verification. */
FinishVerifier(rt);
#endif
/* Delete all remaining Compartments. */
for (CompartmentsIter c(rt); !c.done(); c.next())
js_delete(c.get());
rt->compartments.clear();
rt->atomsCompartment = NULL;
rt->gcSystemAvailableChunkListHead = NULL;
rt->gcUserAvailableChunkListHead = NULL;
for (GCChunkSet::Range r(rt->gcChunkSet.all()); !r.empty(); r.popFront())
Chunk::release(rt, r.front());
rt->gcChunkSet.clear();
rt->gcChunkPool.expireAndFree(rt, true);
rt->gcRootsHash.clear();
rt->gcLocksHash.clear();
}
JSBool
js_AddRoot(JSContext *cx, Value *vp, const char *name)
{
JSBool ok = js_AddRootRT(cx->runtime, vp, name);
if (!ok)
JS_ReportOutOfMemory(cx);
return ok;
}
JSBool
js_AddGCThingRoot(JSContext *cx, void **rp, const char *name)
{
JSBool ok = js_AddGCThingRootRT(cx->runtime, rp, name);
if (!ok)
JS_ReportOutOfMemory(cx);
return ok;
}
JS_FRIEND_API(JSBool)
js_AddRootRT(JSRuntime *rt, jsval *vp, const char *name)
{
/*
* Sometimes Firefox will hold weak references to objects and then convert
* them to strong references by calling AddRoot (e.g., via PreserveWrapper,
* or ModifyBusyCount in workers). We need a read barrier to cover these
* cases.
*/
if (rt->gcIncrementalState == MARK)
IncrementalValueBarrier(*vp);
return !!rt->gcRootsHash.put((void *)vp,
RootInfo(name, JS_GC_ROOT_VALUE_PTR));
}
JS_FRIEND_API(JSBool)
js_AddGCThingRootRT(JSRuntime *rt, void **rp, const char *name)
{
/*
* Sometimes Firefox will hold weak references to objects and then convert
* them to strong references by calling AddRoot (e.g., via PreserveWrapper,
* or ModifyBusyCount in workers). We need a read barrier to cover these
* cases.
*/
if (rt->gcIncrementalState == MARK)
IncrementalReferenceBarrier(*rp);
return !!rt->gcRootsHash.put((void *)rp,
RootInfo(name, JS_GC_ROOT_GCTHING_PTR));
}
JS_FRIEND_API(void)
js_RemoveRoot(JSRuntime *rt, void *rp)
{
rt->gcRootsHash.remove(rp);
rt->gcPoke = true;
}
typedef RootedValueMap::Range RootRange;
typedef RootedValueMap::Entry RootEntry;
typedef RootedValueMap::Enum RootEnum;
static size_t
ComputeTriggerBytes(JSCompartment *comp, size_t lastBytes, size_t maxBytes, JSGCInvocationKind gckind)
{
size_t base = gckind == GC_SHRINK ? lastBytes : Max(lastBytes, comp->rt->gcAllocationThreshold);
float trigger = float(base) * comp->gcHeapGrowthFactor;
return size_t(Min(float(maxBytes), trigger));
}
void
JSCompartment::setGCLastBytes(size_t lastBytes, size_t lastMallocBytes, JSGCInvocationKind gckind)
{
/*
* The heap growth factor depends on the heap size after a GC and the GC frequency.
* For low frequency GCs (more than 1sec between GCs) we let the heap grow to 150%.
* For high frequency GCs we let the heap grow depending on the heap size:
* lastBytes < highFrequencyLowLimit: 300%
* lastBytes > highFrequencyHighLimit: 150%
* otherwise: linear interpolation between 150% and 300% based on lastBytes
*/
if (!rt->gcDynamicHeapGrowth) {
gcHeapGrowthFactor = 3.0;
} else if (lastBytes < 1 * 1024 * 1024) {
gcHeapGrowthFactor = rt->gcLowFrequencyHeapGrowth;
} else {
JS_ASSERT(rt->gcHighFrequencyHighLimitBytes > rt->gcHighFrequencyLowLimitBytes);
uint64_t now = PRMJ_Now();
if (rt->gcLastGCTime && rt->gcLastGCTime + rt->gcHighFrequencyTimeThreshold * PRMJ_USEC_PER_MSEC > now) {
if (lastBytes <= rt->gcHighFrequencyLowLimitBytes) {
gcHeapGrowthFactor = rt->gcHighFrequencyHeapGrowthMax;
} else if (lastBytes >= rt->gcHighFrequencyHighLimitBytes) {
gcHeapGrowthFactor = rt->gcHighFrequencyHeapGrowthMin;
} else {
double k = (rt->gcHighFrequencyHeapGrowthMin - rt->gcHighFrequencyHeapGrowthMax)
/ (double)(rt->gcHighFrequencyHighLimitBytes - rt->gcHighFrequencyLowLimitBytes);
gcHeapGrowthFactor = (k * (lastBytes - rt->gcHighFrequencyLowLimitBytes)
+ rt->gcHighFrequencyHeapGrowthMax);
JS_ASSERT(gcHeapGrowthFactor <= rt->gcHighFrequencyHeapGrowthMax
&& gcHeapGrowthFactor >= rt->gcHighFrequencyHeapGrowthMin);
}
rt->gcHighFrequencyGC = true;
} else {
gcHeapGrowthFactor = rt->gcLowFrequencyHeapGrowth;
rt->gcHighFrequencyGC = false;
}
}
gcTriggerBytes = ComputeTriggerBytes(this, lastBytes, rt->gcMaxBytes, gckind);
gcTriggerMallocAndFreeBytes = ComputeTriggerBytes(this, lastMallocBytes, SIZE_MAX, gckind);
}
void
JSCompartment::reduceGCTriggerBytes(size_t amount)
{
JS_ASSERT(amount > 0);
JS_ASSERT(gcTriggerBytes >= amount);
if (gcTriggerBytes - amount < rt->gcAllocationThreshold * gcHeapGrowthFactor)
return;
gcTriggerBytes -= amount;
}
namespace js {
namespace gc {
inline void
ArenaLists::prepareForIncrementalGC(JSRuntime *rt)
{
for (size_t i = 0; i != FINALIZE_LIMIT; ++i) {
FreeSpan *headSpan = &freeLists[i];
if (!headSpan->isEmpty()) {
ArenaHeader *aheader = headSpan->arenaHeader();
aheader->allocatedDuringIncremental = true;
rt->gcMarker.delayMarkingArena(aheader);
}
}
}
static inline void
PushArenaAllocatedDuringSweep(JSRuntime *runtime, ArenaHeader *arena)
{
arena->setNextAllocDuringSweep(runtime->gcArenasAllocatedDuringSweep);
runtime->gcArenasAllocatedDuringSweep = arena;
}
inline void *
ArenaLists::allocateFromArena(JSCompartment *comp, AllocKind thingKind)
{
Chunk *chunk = NULL;
ArenaList *al = &arenaLists[thingKind];
AutoLockGC maybeLock;
JS_ASSERT(!comp->scheduledForDestruction);
#ifdef JS_THREADSAFE
volatile uintptr_t *bfs = &backgroundFinalizeState[thingKind];
if (*bfs != BFS_DONE) {
/*
* We cannot search the arena list for free things while the
* background finalization runs and can modify head or cursor at any
* moment. So we always allocate a new arena in that case.
*/
maybeLock.lock(comp->rt);
if (*bfs == BFS_RUN) {
JS_ASSERT(!*al->cursor);
chunk = PickChunk(comp);
if (!chunk) {
/*
* Let the caller to wait for the background allocation to
* finish and restart the allocation attempt.
*/
return NULL;
}
} else if (*bfs == BFS_JUST_FINISHED) {
/* See comments before BackgroundFinalizeState definition. */
*bfs = BFS_DONE;
} else {
JS_ASSERT(*bfs == BFS_DONE);
}
}
#endif /* JS_THREADSAFE */
if (!chunk) {
if (ArenaHeader *aheader = *al->cursor) {
JS_ASSERT(aheader->hasFreeThings());
/*
* The empty arenas are returned to the chunk and should not present on
* the list.
*/
JS_ASSERT(!aheader->isEmpty());
al->cursor = &aheader->next;
/*
* Move the free span stored in the arena to the free list and
* allocate from it.
*/
freeLists[thingKind] = aheader->getFirstFreeSpan();
aheader->setAsFullyUsed();
if (JS_UNLIKELY(comp->wasGCStarted())) {
if (comp->needsBarrier()) {
aheader->allocatedDuringIncremental = true;
comp->rt->gcMarker.delayMarkingArena(aheader);
} else if (comp->isGCSweeping()) {
PushArenaAllocatedDuringSweep(comp->rt, aheader);
}
}
return freeLists[thingKind].infallibleAllocate(Arena::thingSize(thingKind));
}
/* Make sure we hold the GC lock before we call PickChunk. */
if (!maybeLock.locked())
maybeLock.lock(comp->rt);
chunk = PickChunk(comp);
if (!chunk)
return NULL;
}
/*
* While we still hold the GC lock get an arena from some chunk, mark it
* as full as its single free span is moved to the free lits, and insert
* it to the list as a fully allocated arena.
*
* We add the arena before the the head, not after the tail pointed by the
* cursor, so after the GC the most recently added arena will be used first
* for allocations improving cache locality.
*/
JS_ASSERT(!*al->cursor);
ArenaHeader *aheader = chunk->allocateArena(comp, thingKind);
if (!aheader)
return NULL;
if (JS_UNLIKELY(comp->wasGCStarted())) {
if (comp->needsBarrier()) {
aheader->allocatedDuringIncremental = true;
comp->rt->gcMarker.delayMarkingArena(aheader);
} else if (comp->isGCSweeping()) {
PushArenaAllocatedDuringSweep(comp->rt, aheader);
}
}
aheader->next = al->head;
if (!al->head) {
JS_ASSERT(al->cursor == &al->head);
al->cursor = &aheader->next;
}
al->head = aheader;
/* See comments before allocateFromNewArena about this assert. */
JS_ASSERT(!aheader->hasFreeThings());
uintptr_t arenaAddr = aheader->arenaAddress();
return freeLists[thingKind].allocateFromNewArena(arenaAddr,
Arena::firstThingOffset(thingKind),
Arena::thingSize(thingKind));
}
void
ArenaLists::finalizeNow(FreeOp *fop, AllocKind thingKind)
{
JS_ASSERT(!IsBackgroundFinalized(thingKind));
JS_ASSERT(backgroundFinalizeState[thingKind] == BFS_DONE ||
backgroundFinalizeState[thingKind] == BFS_JUST_FINISHED);
ArenaHeader *arenas = arenaLists[thingKind].head;
arenaLists[thingKind].clear();
SliceBudget budget;
FinalizeArenas(fop, &arenas, arenaLists[thingKind], thingKind, budget);
JS_ASSERT(!arenas);
}
void
ArenaLists::queueForForegroundSweep(FreeOp *fop, AllocKind thingKind)
{
JS_ASSERT(!IsBackgroundFinalized(thingKind));
JS_ASSERT(backgroundFinalizeState[thingKind] == BFS_DONE);
JS_ASSERT(!arenaListsToSweep[thingKind]);
arenaListsToSweep[thingKind] = arenaLists[thingKind].head;
arenaLists[thingKind].clear();
}
inline void
ArenaLists::queueForBackgroundSweep(FreeOp *fop, AllocKind thingKind)
{
JS_ASSERT(IsBackgroundFinalized(thingKind));
#ifdef JS_THREADSAFE
JS_ASSERT(!fop->runtime()->gcHelperThread.sweeping());
#endif
ArenaList *al = &arenaLists[thingKind];
if (!al->head) {
JS_ASSERT(backgroundFinalizeState[thingKind] == BFS_DONE);
JS_ASSERT(al->cursor == &al->head);
return;
}
/*
* The state can be done, or just-finished if we have not allocated any GC
* things from the arena list after the previous background finalization.
*/
JS_ASSERT(backgroundFinalizeState[thingKind] == BFS_DONE ||
backgroundFinalizeState[thingKind] == BFS_JUST_FINISHED);
arenaListsToSweep[thingKind] = al->head;
al->clear();
backgroundFinalizeState[thingKind] = BFS_RUN;
}
/*static*/ void
ArenaLists::backgroundFinalize(FreeOp *fop, ArenaHeader *listHead, bool onBackgroundThread)
{
JS_ASSERT(listHead);
AllocKind thingKind = listHead->getAllocKind();
JSCompartment *comp = listHead->compartment;
ArenaList finalized;
SliceBudget budget;
FinalizeArenas(fop, &listHead, finalized, thingKind, budget);
JS_ASSERT(!listHead);
/*
* After we finish the finalization al->cursor must point to the end of
* the head list as we emptied the list before the background finalization
* and the allocation adds new arenas before the cursor.
*/
ArenaLists *lists = &comp->arenas;
ArenaList *al = &lists->arenaLists[thingKind];
AutoLockGC lock(fop->runtime());
JS_ASSERT(lists->backgroundFinalizeState[thingKind] == BFS_RUN);
JS_ASSERT(!*al->cursor);
if (finalized.head) {
*al->cursor = finalized.head;
if (finalized.cursor != &finalized.head)
al->cursor = finalized.cursor;
}
/*
* We must set the state to BFS_JUST_FINISHED if we are running on the
* background thread and we have touched arenaList list, even if we add to
* the list only fully allocated arenas without any free things. It ensures
* that the allocation thread takes the GC lock and all writes to the free
* list elements are propagated. As we always take the GC lock when
* allocating new arenas from the chunks we can set the state to BFS_DONE if
* we have released all finalized arenas back to their chunks.
*/
if (onBackgroundThread && finalized.head)
lists->backgroundFinalizeState[thingKind] = BFS_JUST_FINISHED;
else
lists->backgroundFinalizeState[thingKind] = BFS_DONE;
lists->arenaListsToSweep[thingKind] = NULL;
}
void
ArenaLists::queueObjectsForSweep(FreeOp *fop)
{
gcstats::AutoPhase ap(fop->runtime()->gcStats, gcstats::PHASE_SWEEP_OBJECT);
finalizeNow(fop, FINALIZE_OBJECT0);
finalizeNow(fop, FINALIZE_OBJECT2);
finalizeNow(fop, FINALIZE_OBJECT4);
finalizeNow(fop, FINALIZE_OBJECT8);
finalizeNow(fop, FINALIZE_OBJECT12);
finalizeNow(fop, FINALIZE_OBJECT16);
queueForBackgroundSweep(fop, FINALIZE_OBJECT0_BACKGROUND);
queueForBackgroundSweep(fop, FINALIZE_OBJECT2_BACKGROUND);
queueForBackgroundSweep(fop, FINALIZE_OBJECT4_BACKGROUND);
queueForBackgroundSweep(fop, FINALIZE_OBJECT8_BACKGROUND);
queueForBackgroundSweep(fop, FINALIZE_OBJECT12_BACKGROUND);
queueForBackgroundSweep(fop, FINALIZE_OBJECT16_BACKGROUND);
#if JS_HAS_XML_SUPPORT
finalizeNow(fop, FINALIZE_XML);
#endif
}
void
ArenaLists::queueStringsForSweep(FreeOp *fop)
{
gcstats::AutoPhase ap(fop->runtime()->gcStats, gcstats::PHASE_SWEEP_STRING);
queueForBackgroundSweep(fop, FINALIZE_SHORT_STRING);
queueForBackgroundSweep(fop, FINALIZE_STRING);
queueForForegroundSweep(fop, FINALIZE_EXTERNAL_STRING);
}
void
ArenaLists::queueScriptsForSweep(FreeOp *fop)
{
gcstats::AutoPhase ap(fop->runtime()->gcStats, gcstats::PHASE_SWEEP_SCRIPT);
queueForForegroundSweep(fop, FINALIZE_SCRIPT);
}
void
ArenaLists::queueShapesForSweep(FreeOp *fop)
{
gcstats::AutoPhase ap(fop->runtime()->gcStats, gcstats::PHASE_SWEEP_SHAPE);
queueForForegroundSweep(fop, FINALIZE_SHAPE);
queueForForegroundSweep(fop, FINALIZE_BASE_SHAPE);
queueForForegroundSweep(fop, FINALIZE_TYPE_OBJECT);
}
void
ArenaLists::queueIonCodeForSweep(FreeOp *fop)
{
finalizeNow(fop, FINALIZE_IONCODE);
}
static void
RunLastDitchGC(JSContext *cx, gcreason::Reason reason)
{
JSRuntime *rt = cx->runtime;
/* The last ditch GC preserves all atoms. */
AutoKeepAtoms keep(rt);
GC(rt, GC_NORMAL, reason);
}
/* static */ void *
ArenaLists::refillFreeList(JSContext *cx, AllocKind thingKind)
{
JS_ASSERT(cx->compartment->arenas.freeLists[thingKind].isEmpty());
JSCompartment *comp = cx->compartment;
JSRuntime *rt = comp->rt;
JS_ASSERT(!rt->isHeapBusy());
bool runGC = rt->gcIncrementalState != NO_INCREMENTAL && comp->gcBytes > comp->gcTriggerBytes;
for (;;) {
if (JS_UNLIKELY(runGC)) {
PrepareCompartmentForGC(comp);
RunLastDitchGC(cx, gcreason::LAST_DITCH);
/*
* The JSGC_END callback can legitimately allocate new GC
* things and populate the free list. If that happens, just
* return that list head.
*/
size_t thingSize = Arena::thingSize(thingKind);
if (void *thing = comp->arenas.allocateFromFreeList(thingKind, thingSize))
return thing;
}
/*
* allocateFromArena may fail while the background finalization still
* run. In that case we want to wait for it to finish and restart.
* However, checking for that is racy as the background finalization
* could free some things after allocateFromArena decided to fail but
* at this point it may have already stopped. To avoid this race we
* always try to allocate twice.
*/
for (bool secondAttempt = false; ; secondAttempt = true) {
void *thing = comp->arenas.allocateFromArena(comp, thingKind);
if (JS_LIKELY(!!thing))
return thing;
if (secondAttempt)
break;
rt->gcHelperThread.waitBackgroundSweepEnd();
}
/*
* We failed to allocate. Run the GC if we haven't done it already.
* Otherwise report OOM.
*/
if (runGC)
break;
runGC = true;
}
js_ReportOutOfMemory(cx);
return NULL;
}
} /* namespace gc */
} /* namespace js */
JSGCTraceKind
js_GetGCThingTraceKind(void *thing)
{
return GetGCThingTraceKind(thing);
}
JSBool
js_LockGCThingRT(JSRuntime *rt, void *thing)
{
if (!thing)
return true;
/*
* Sometimes Firefox will hold weak references to objects and then convert
* them to strong references by calling AddRoot (e.g., via PreserveWrapper,
* or ModifyBusyCount in workers). We need a read barrier to cover these
* cases.
*/
if (rt->gcIncrementalState == MARK)
IncrementalReferenceBarrier(thing);
if (GCLocks::Ptr p = rt->gcLocksHash.lookupWithDefault(thing, 0)) {
p->value++;
return true;
}
return false;
}
void
js_UnlockGCThingRT(JSRuntime *rt, void *thing)
{
if (!thing)
return;
if (GCLocks::Ptr p = rt->gcLocksHash.lookup(thing)) {
rt->gcPoke = true;
if (--p->value == 0)
rt->gcLocksHash.remove(p);
}
}
namespace js {
void
InitTracer(JSTracer *trc, JSRuntime *rt, JSTraceCallback callback)
{
trc->runtime = rt;
trc->callback = callback;
trc->debugPrinter = NULL;
trc->debugPrintArg = NULL;
trc->debugPrintIndex = size_t(-1);
trc->eagerlyTraceWeakMaps = true;
#ifdef JS_GC_ZEAL
trc->realLocation = NULL;
#endif
}
/* static */ int64_t
SliceBudget::TimeBudget(int64_t millis)
{
return millis * PRMJ_USEC_PER_MSEC;
}
/* static */ int64_t
SliceBudget::WorkBudget(int64_t work)
{
/* For work = 0 not to mean Unlimited, we subtract 1. */
return -work - 1;
}
SliceBudget::SliceBudget()
: deadline(INT64_MAX),
counter(INTPTR_MAX)
{
}
SliceBudget::SliceBudget(int64_t budget)
{
if (budget == Unlimited) {
deadline = INT64_MAX;
counter = INTPTR_MAX;
} else if (budget > 0) {
deadline = PRMJ_Now() + budget;
counter = CounterReset;
} else {
deadline = 0;
counter = -budget - 1;
}
}
bool
SliceBudget::checkOverBudget()
{
bool over = PRMJ_Now() > deadline;
if (!over)
counter = CounterReset;
return over;
}
GCMarker::GCMarker()
: stack(size_t(-1)),
color(BLACK),
started(false),
unmarkedArenaStackTop(NULL),
markLaterArenas(0),
grayFailed(false)
{
}
bool
GCMarker::init()
{
return stack.init(MARK_STACK_LENGTH);
}
void
GCMarker::start(JSRuntime *rt)
{
InitTracer(this, rt, NULL);
JS_ASSERT(!started);
started = true;
color = BLACK;
JS_ASSERT(!unmarkedArenaStackTop);
JS_ASSERT(markLaterArenas == 0);
JS_ASSERT(grayRoots.empty());
JS_ASSERT(!grayFailed);
/*
* The GC is recomputing the liveness of WeakMap entries, so we delay
* visting entries.
*/
eagerlyTraceWeakMaps = JS_FALSE;
}
void
GCMarker::stop()
{
JS_ASSERT(isDrained());
JS_ASSERT(started);
started = false;
JS_ASSERT(!unmarkedArenaStackTop);
JS_ASSERT(markLaterArenas == 0);
JS_ASSERT(grayRoots.empty());
grayFailed = false;
/* Free non-ballast stack memory. */
stack.reset();
grayRoots.clearAndFree();
}
void
GCMarker::reset()
{
color = BLACK;
stack.reset();
JS_ASSERT(isMarkStackEmpty());
while (unmarkedArenaStackTop) {
ArenaHeader *aheader = unmarkedArenaStackTop;
JS_ASSERT(aheader->hasDelayedMarking);
JS_ASSERT(markLaterArenas);
unmarkedArenaStackTop = aheader->getNextDelayedMarking();
aheader->unsetDelayedMarking();
aheader->markOverflow = 0;
aheader->allocatedDuringIncremental = 0;
markLaterArenas--;
}
JS_ASSERT(isDrained());
JS_ASSERT(!markLaterArenas);
grayRoots.clearAndFree();
grayFailed = false;
}
/*
* When the native stack is low, the GC does not call JS_TraceChildren to mark
* the reachable "children" of the thing. Rather the thing is put aside and
* JS_TraceChildren is called later with more space on the C stack.
*
* To implement such delayed marking of the children with minimal overhead for
* the normal case of sufficient native stack, the code adds a field per
* arena. The field markingDelay->link links all arenas with delayed things
* into a stack list with the pointer to stack top in
* GCMarker::unmarkedArenaStackTop. delayMarkingChildren adds
* arenas to the stack as necessary while markDelayedChildren pops the arenas
* from the stack until it empties.
*/
inline void
GCMarker::delayMarkingArena(ArenaHeader *aheader)
{
if (aheader->hasDelayedMarking) {
/* Arena already scheduled to be marked later */
return;
}
aheader->setNextDelayedMarking(unmarkedArenaStackTop);
unmarkedArenaStackTop = aheader;
markLaterArenas++;
}
void
GCMarker::delayMarkingChildren(const void *thing)
{
const Cell *cell = reinterpret_cast<const Cell *>(thing);
cell->arenaHeader()->markOverflow = 1;
delayMarkingArena(cell->arenaHeader());
}
void
GCMarker::markDelayedChildren(ArenaHeader *aheader)
{
if (aheader->markOverflow) {
bool always = aheader->allocatedDuringIncremental;
aheader->markOverflow = 0;
for (CellIterUnderGC i(aheader); !i.done(); i.next()) {
Cell *t = i.getCell();
if (always || t->isMarked()) {
t->markIfUnmarked();
JS_TraceChildren(this, t, MapAllocToTraceKind(aheader->getAllocKind()));
}
}
} else {
JS_ASSERT(aheader->allocatedDuringIncremental);
PushArena(this, aheader);
}
aheader->allocatedDuringIncremental = 0;
/*
* Note that during an incremental GC we may still be allocating into
* aheader. However, prepareForIncrementalGC sets the
* allocatedDuringIncremental flag if we continue marking.
*/
}
bool
GCMarker::markDelayedChildren(SliceBudget &budget)
{
gcstats::AutoPhase ap(runtime->gcStats, gcstats::PHASE_MARK_DELAYED);
JS_ASSERT(unmarkedArenaStackTop);
do {
/*
* If marking gets delayed at the same arena again, we must repeat
* marking of its things. For that we pop arena from the stack and
* clear its hasDelayedMarking flag before we begin the marking.
*/
ArenaHeader *aheader = unmarkedArenaStackTop;
JS_ASSERT(aheader->hasDelayedMarking);
JS_ASSERT(markLaterArenas);
unmarkedArenaStackTop = aheader->getNextDelayedMarking();
aheader->unsetDelayedMarking();
markLaterArenas--;
markDelayedChildren(aheader);
budget.step(150);
if (budget.isOverBudget())
return false;
} while (unmarkedArenaStackTop);
JS_ASSERT(!markLaterArenas);
return true;
}
#ifdef DEBUG
void
GCMarker::checkCompartment(void *p)
{
JS_ASSERT(started);
JS_ASSERT(static_cast<Cell *>(p)->compartment()->isCollecting());
}
#endif
bool
GCMarker::hasBufferedGrayRoots() const
{
return !grayFailed;
}
void
GCMarker::startBufferingGrayRoots()
{
JS_ASSERT(!callback);
callback = GrayCallback;
JS_ASSERT(IS_GC_MARKING_TRACER(this));
}
void
GCMarker::endBufferingGrayRoots()
{
JS_ASSERT(callback == GrayCallback);
callback = NULL;
JS_ASSERT(IS_GC_MARKING_TRACER(this));
}
void
GCMarker::markBufferedGrayRoots()
{
JS_ASSERT(!grayFailed);
for (GrayRoot *elem = grayRoots.begin(); elem != grayRoots.end(); elem++) {
#ifdef DEBUG
debugPrinter = elem->debugPrinter;
debugPrintArg = elem->debugPrintArg;
debugPrintIndex = elem->debugPrintIndex;
#endif
JS_SET_TRACING_LOCATION(this, (void *)&elem->thing);
void *tmp = elem->thing;
MarkKind(this, &tmp, elem->kind);
JS_ASSERT(tmp == elem->thing);
}
grayRoots.clearAndFree();
}
void
GCMarker::markBufferedGrayRootCompartmentsAlive()
{
for (GrayRoot *elem = grayRoots.begin(); elem != grayRoots.end(); elem++) {
Cell *thing = static_cast<Cell *>(elem->thing);
thing->compartment()->maybeAlive = true;
}
}
void
GCMarker::appendGrayRoot(void *thing, JSGCTraceKind kind)
{
JS_ASSERT(started);
if (grayFailed)
return;
GrayRoot root(thing, kind);
#ifdef DEBUG
root.debugPrinter = debugPrinter;
root.debugPrintArg = debugPrintArg;
root.debugPrintIndex = debugPrintIndex;
#endif
if (!grayRoots.append(root)) {
grayRoots.clearAndFree();
grayFailed = true;
}
}
void
GCMarker::GrayCallback(JSTracer *trc, void **thingp, JSGCTraceKind kind)
{
GCMarker *gcmarker = static_cast<GCMarker *>(trc);
gcmarker->appendGrayRoot(*thingp, kind);
}
size_t
GCMarker::sizeOfExcludingThis(JSMallocSizeOfFun mallocSizeOf) const
{
return stack.sizeOfExcludingThis(mallocSizeOf) +
grayRoots.sizeOfExcludingThis(mallocSizeOf);
}
void
SetMarkStackLimit(JSRuntime *rt, size_t limit)
{
JS_ASSERT(!rt->isHeapBusy());
rt->gcMarker.setSizeLimit(limit);
}
} /* namespace js */
namespace js {
void
MarkCompartmentActive(StackFrame *fp)
{
fp->script()->compartment()->active = true;
}
} /* namespace js */
void
AutoIdArray::trace(JSTracer *trc)
{
JS_ASSERT(tag == IDARRAY);
gc::MarkIdRange(trc, idArray->length, idArray->vector, "JSAutoIdArray.idArray");
}
inline void
AutoGCRooter::trace(JSTracer *trc)
{
switch (tag) {
case JSVAL:
MarkValueRoot(trc, &static_cast<AutoValueRooter *>(this)->val, "JS::AutoValueRooter.val");
return;
case PARSER:
static_cast<frontend::Parser *>(this)->trace(trc);
return;
case IDARRAY: {
JSIdArray *ida = static_cast<AutoIdArray *>(this)->idArray;
MarkIdRange(trc, ida->length, ida->vector, "JS::AutoIdArray.idArray");
return;
}
case DESCRIPTORS: {
PropDescArray &descriptors =
static_cast<AutoPropDescArrayRooter *>(this)->descriptors;
for (size_t i = 0, len = descriptors.length(); i < len; i++) {
PropDesc &desc = descriptors[i];
MarkValueRoot(trc, &desc.pd_, "PropDesc::pd_");
MarkValueRoot(trc, &desc.value_, "PropDesc::value_");
MarkValueRoot(trc, &desc.get_, "PropDesc::get_");
MarkValueRoot(trc, &desc.set_, "PropDesc::set_");
}
return;
}
case DESCRIPTOR : {
PropertyDescriptor &desc = *static_cast<AutoPropertyDescriptorRooter *>(this);
if (desc.obj)
MarkObjectRoot(trc, &desc.obj, "Descriptor::obj");
MarkValueRoot(trc, &desc.value, "Descriptor::value");
if ((desc.attrs & JSPROP_GETTER) && desc.getter) {
JSObject *tmp = JS_FUNC_TO_DATA_PTR(JSObject *, desc.getter);
MarkObjectRoot(trc, &tmp, "Descriptor::get");
desc.getter = JS_DATA_TO_FUNC_PTR(JSPropertyOp, tmp);
}
if (desc.attrs & JSPROP_SETTER && desc.setter) {
JSObject *tmp = JS_FUNC_TO_DATA_PTR(JSObject *, desc.setter);
MarkObjectRoot(trc, &tmp, "Descriptor::set");
desc.setter = JS_DATA_TO_FUNC_PTR(JSStrictPropertyOp, tmp);
}
return;
}
#if JS_HAS_XML_SUPPORT
case NAMESPACES: {
JSXMLArray<JSObject> &array = static_cast<AutoNamespaceArray *>(this)->array;
MarkObjectRange(trc, array.length, array.vector, "JSXMLArray.vector");
js_XMLArrayCursorTrace(trc, array.cursors);
return;
}
case XML:
js_TraceXML(trc, static_cast<AutoXMLRooter *>(this)->xml);
return;
#endif
case OBJECT:
if (static_cast<AutoObjectRooter *>(this)->obj)
MarkObjectRoot(trc, &static_cast<AutoObjectRooter *>(this)->obj,
"JS::AutoObjectRooter.obj");
return;
case ID:
MarkIdRoot(trc, &static_cast<AutoIdRooter *>(this)->id_, "JS::AutoIdRooter.id_");
return;
case VALVECTOR: {
AutoValueVector::VectorImpl &vector = static_cast<AutoValueVector *>(this)->vector;
MarkValueRootRange(trc, vector.length(), vector.begin(), "js::AutoValueVector.vector");
return;
}
case STRING:
if (static_cast<AutoStringRooter *>(this)->str)
MarkStringRoot(trc, &static_cast<AutoStringRooter *>(this)->str,
"JS::AutoStringRooter.str");
return;
case IDVECTOR: {
AutoIdVector::VectorImpl &vector = static_cast<AutoIdVector *>(this)->vector;
MarkIdRootRange(trc, vector.length(), vector.begin(), "js::AutoIdVector.vector");
return;
}
case SHAPEVECTOR: {
AutoShapeVector::VectorImpl &vector = static_cast<js::AutoShapeVector *>(this)->vector;
MarkShapeRootRange(trc, vector.length(), const_cast<Shape **>(vector.begin()),
"js::AutoShapeVector.vector");
return;
}
case OBJVECTOR: {
AutoObjectVector::VectorImpl &vector = static_cast<AutoObjectVector *>(this)->vector;
MarkObjectRootRange(trc, vector.length(), vector.begin(), "js::AutoObjectVector.vector");
return;
}
case STRINGVECTOR: {
AutoStringVector::VectorImpl &vector = static_cast<AutoStringVector *>(this)->vector;
MarkStringRootRange(trc, vector.length(), vector.begin(), "js::AutoStringVector.vector");
return;
}
case NAMEVECTOR: {
AutoNameVector::VectorImpl &vector = static_cast<AutoNameVector *>(this)->vector;
MarkStringRootRange(trc, vector.length(), vector.begin(), "js::AutoNameVector.vector");
return;
}
case VALARRAY: {
AutoValueArray *array = static_cast<AutoValueArray *>(this);
MarkValueRootRange(trc, array->length(), array->start(), "js::AutoValueArray");
return;
}
case SCRIPTVECTOR: {
AutoScriptVector::VectorImpl &vector = static_cast<AutoScriptVector *>(this)->vector;
for (size_t i = 0; i < vector.length(); i++)
MarkScriptRoot(trc, &vector[i], "AutoScriptVector element");
return;
}
case PROPDESC: {
PropDesc::AutoRooter *rooter = static_cast<PropDesc::AutoRooter *>(this);
MarkValueRoot(trc, &rooter->pd->pd_, "PropDesc::AutoRooter pd");
MarkValueRoot(trc, &rooter->pd->value_, "PropDesc::AutoRooter value");
MarkValueRoot(trc, &rooter->pd->get_, "PropDesc::AutoRooter get");
MarkValueRoot(trc, &rooter->pd->set_, "PropDesc::AutoRooter set");
return;
}
case SHAPERANGE: {
Shape::Range::AutoRooter *rooter = static_cast<Shape::Range::AutoRooter *>(this);
rooter->trace(trc);
return;
}
case STACKSHAPE: {
StackShape::AutoRooter *rooter = static_cast<StackShape::AutoRooter *>(this);
if (rooter->shape->base)
MarkBaseShapeRoot(trc, (BaseShape**) &rooter->shape->base, "StackShape::AutoRooter base");
MarkIdRoot(trc, (jsid*) &rooter->shape->propid, "StackShape::AutoRooter id");
return;
}
case STACKBASESHAPE: {
StackBaseShape::AutoRooter *rooter = static_cast<StackBaseShape::AutoRooter *>(this);
if (rooter->base->parent)
MarkObjectRoot(trc, (JSObject**) &rooter->base->parent, "StackBaseShape::AutoRooter parent");
if ((rooter->base->flags & BaseShape::HAS_GETTER_OBJECT) && rooter->base->rawGetter) {
MarkObjectRoot(trc, (JSObject**) &rooter->base->rawGetter,
"StackBaseShape::AutoRooter getter");
}
if ((rooter->base->flags & BaseShape::HAS_SETTER_OBJECT) && rooter->base->rawSetter) {
MarkObjectRoot(trc, (JSObject**) &rooter->base->rawSetter,
"StackBaseShape::AutoRooter setter");
}
return;
}
case GETTERSETTER: {
AutoRooterGetterSetter::Inner *rooter = static_cast<AutoRooterGetterSetter::Inner *>(this);
if ((rooter->attrs & JSPROP_GETTER) && *rooter->pgetter)
MarkObjectRoot(trc, (JSObject**) rooter->pgetter, "AutoRooterGetterSetter getter");
if ((rooter->attrs & JSPROP_SETTER) && *rooter->psetter)
MarkObjectRoot(trc, (JSObject**) rooter->psetter, "AutoRooterGetterSetter setter");
return;
}
case REGEXPSTATICS: {
/*
RegExpStatics::AutoRooter *rooter = static_cast<RegExpStatics::AutoRooter *>(this);
rooter->trace(trc);
*/
return;
}
case HASHABLEVALUE: {
/*
HashableValue::AutoRooter *rooter = static_cast<HashableValue::AutoRooter *>(this);
rooter->trace(trc);
*/
return;
}
case IONMASM: {
#ifdef JS_ION
static_cast<js::ion::MacroAssembler::AutoRooter *>(this)->masm()->trace(trc);
#endif
return;
}
case IONALLOC: {
#ifdef JS_ION
static_cast<js::ion::AutoTempAllocatorRooter *>(this)->trace(trc);
#endif
return;
}
case WRAPPER: {
/*
* We need to use MarkValueUnbarriered here because we mark wrapper
* roots in every slice. This is because of some rule-breaking in
* RemapAllWrappersForObject; see comment there.
*/
MarkValueUnbarriered(trc, &static_cast<AutoWrapperRooter *>(this)->value.get(),
"JS::AutoWrapperRooter.value");
return;
}
case WRAPVECTOR: {
AutoWrapperVector::VectorImpl &vector = static_cast<AutoWrapperVector *>(this)->vector;
/*
* We need to use MarkValueUnbarriered here because we mark wrapper
* roots in every slice. This is because of some rule-breaking in
* RemapAllWrappersForObject; see comment there.
*/
for (WrapperValue *p = vector.begin(); p < vector.end(); p++)
MarkValueUnbarriered(trc, &p->get(), "js::AutoWrapperVector.vector");
return;
}
}
JS_ASSERT(tag >= 0);
MarkValueRootRange(trc, tag, static_cast<AutoArrayRooter *>(this)->array,
"JS::AutoArrayRooter.array");
}
/* static */ void
AutoGCRooter::traceAll(JSTracer *trc)
{
for (js::AutoGCRooter *gcr = trc->runtime->autoGCRooters; gcr; gcr = gcr->down)
gcr->trace(trc);
}
/* static */ void
AutoGCRooter::traceAllWrappers(JSTracer *trc)
{
for (js::AutoGCRooter *gcr = trc->runtime->autoGCRooters; gcr; gcr = gcr->down) {
if (gcr->tag == WRAPVECTOR || gcr->tag == WRAPPER)
gcr->trace(trc);
}
}
void
Shape::Range::AutoRooter::trace(JSTracer *trc)
{
if (r->cursor)
MarkShapeRoot(trc, const_cast<Shape**>(&r->cursor), "Shape::Range::AutoRooter");
}
void
RegExpStatics::AutoRooter::trace(JSTracer *trc)
{
if (statics->matchPairsInput)
MarkStringRoot(trc, reinterpret_cast<JSString**>(&statics->matchPairsInput),
"RegExpStatics::AutoRooter matchPairsInput");
if (statics->pendingInput)
MarkStringRoot(trc, reinterpret_cast<JSString**>(&statics->pendingInput),
"RegExpStatics::AutoRooter pendingInput");
}
void
HashableValue::AutoRooter::trace(JSTracer *trc)
{
MarkValueRoot(trc, reinterpret_cast<Value*>(&v->value), "HashableValue::AutoRooter");
}
namespace js {
static void
MarkRuntime(JSTracer *trc, bool useSavedRoots = false)
{
JSRuntime *rt = trc->runtime;
JS_ASSERT(trc->callback != GCMarker::GrayCallback);
if (IS_GC_MARKING_TRACER(trc)) {
for (CompartmentsIter c(rt); !c.done(); c.next()) {
if (!c->isCollecting())
c->markCrossCompartmentWrappers(trc);
}
Debugger::markCrossCompartmentDebuggerObjectReferents(trc);
}
AutoGCRooter::traceAll(trc);
if (rt->hasContexts()) {
#ifdef JSGC_USE_EXACT_ROOTING
MarkExactStackRoots(trc);
#else
MarkConservativeStackRoots(trc, useSavedRoots);
#endif
rt->markSelfHostedGlobal(trc);
}
for (RootRange r = rt->gcRootsHash.all(); !r.empty(); r.popFront()) {
const RootEntry &entry = r.front();
const char *name = entry.value.name ? entry.value.name : "root";
if (entry.value.type == JS_GC_ROOT_GCTHING_PTR)
MarkGCThingRoot(trc, reinterpret_cast<void **>(entry.key), name);
else
MarkValueRoot(trc, reinterpret_cast<Value *>(entry.key), name);
}
for (GCLocks::Range r = rt->gcLocksHash.all(); !r.empty(); r.popFront()) {
const GCLocks::Entry &entry = r.front();
JS_ASSERT(entry.value >= 1);
JS_SET_TRACING_LOCATION(trc, (void *)&entry.key);
void *tmp = entry.key;
MarkGCThingRoot(trc, &tmp, "locked object");
JS_ASSERT(tmp == entry.key);
}
if (rt->scriptAndCountsVector) {
ScriptAndCountsVector &vec = *rt->scriptAndCountsVector;
for (size_t i = 0; i < vec.length(); i++)
MarkScriptRoot(trc, &vec[i].script, "scriptAndCountsVector");
}
if (!IS_GC_MARKING_TRACER(trc) || rt->atomsCompartment->isCollecting()) {
MarkAtoms(trc);
#ifdef JS_ION
/* Any Ion wrappers survive until the runtime is being torn down. */
if (rt->hasContexts())
ion::IonRuntime::Mark(trc);
#endif
}
rt->staticStrings.trace(trc);
for (ContextIter acx(rt); !acx.done(); acx.next())
acx->mark(trc);
/* We can't use GCCompartmentsIter if we're called from TraceRuntime. */
for (CompartmentsIter c(rt); !c.done(); c.next()) {
if (IS_GC_MARKING_TRACER(trc) && !c->isCollecting())
continue;
if ((c->activeAnalysis || c->isPreservingCode()) && IS_GC_MARKING_TRACER(trc)) {
gcstats::AutoPhase ap(rt->gcStats, gcstats::PHASE_MARK_TYPES);
c->markTypes(trc);
}
/* During a GC, these are treated as weak pointers. */
if (!IS_GC_MARKING_TRACER(trc)) {
if (c->watchpointMap)
c->watchpointMap->markAll(trc);
}
/* Do not discard scripts with counts while profiling. */
if (rt->profilingScripts) {
for (CellIterUnderGC i(c, FINALIZE_SCRIPT); !i.done(); i.next()) {
JSScript *script = i.get<JSScript>();
if (script->hasScriptCounts) {
MarkScriptRoot(trc, &script, "profilingScripts");
JS_ASSERT(script == i.get<JSScript>());
}
}
}
}
#ifdef JS_METHODJIT
/* We need to expand inline frames before stack scanning. */
for (CompartmentsIter c(rt); !c.done(); c.next())
mjit::ExpandInlineFrames(c);
#endif
rt->stackSpace.mark(trc);
rt->debugScopes->mark(trc);
#ifdef JS_ION
ion::MarkIonActivations(rt, trc);
#endif
for (CompartmentsIter c(rt); !c.done(); c.next())
c->mark(trc);
/* The embedding can register additional roots here. */
if (JSTraceDataOp op = rt->gcBlackRootsTraceOp)
(*op)(trc, rt->gcBlackRootsData);
/* During GC, this buffers up the gray roots and doesn't mark them. */
if (JSTraceDataOp op = rt->gcGrayRootsTraceOp) {
if (IS_GC_MARKING_TRACER(trc)) {
GCMarker *gcmarker = static_cast<GCMarker *>(trc);
gcmarker->startBufferingGrayRoots();
(*op)(trc, rt->gcGrayRootsData);
gcmarker->endBufferingGrayRoots();
} else {
(*op)(trc, rt->gcGrayRootsData);
}
}
}
static void
TriggerOperationCallback(JSRuntime *rt, gcreason::Reason reason)
{
if (rt->gcIsNeeded)
return;
rt->gcIsNeeded = true;
rt->gcTriggerReason = reason;
rt->triggerOperationCallback();
}
void
TriggerGC(JSRuntime *rt, gcreason::Reason reason)
{
rt->assertValidThread();
if (rt->isHeapBusy())
return;
PrepareForFullGC(rt);
TriggerOperationCallback(rt, reason);
}
void
TriggerCompartmentGC(JSCompartment *comp, gcreason::Reason reason)
{
JSRuntime *rt = comp->rt;
rt->assertValidThread();
if (rt->isHeapBusy())
return;
if (rt->gcZeal() == ZealAllocValue) {
TriggerGC(rt, reason);
return;
}
if (comp == rt->atomsCompartment) {
/* We can't do a compartmental GC of the default compartment. */
TriggerGC(rt, reason);
return;
}
PrepareCompartmentForGC(comp);
TriggerOperationCallback(rt, reason);
}
void
MaybeGC(JSContext *cx)
{
JSRuntime *rt = cx->runtime;
rt->assertValidThread();
if (rt->gcZeal() == ZealAllocValue || rt->gcZeal() == ZealPokeValue) {
PrepareForFullGC(rt);
GC(rt, GC_NORMAL, gcreason::MAYBEGC);
return;
}
if (rt->gcIsNeeded) {
GCSlice(rt, GC_NORMAL, gcreason::MAYBEGC);
return;
}
double factor = rt->gcHighFrequencyGC ? 0.75 : 0.9;
JSCompartment *comp = cx->compartment;
if (comp->gcBytes > 1024 * 1024 &&
comp->gcBytes >= factor * comp->gcTriggerBytes &&
rt->gcIncrementalState == NO_INCREMENTAL &&
!rt->gcHelperThread.sweeping())
{
PrepareCompartmentForGC(comp);
GCSlice(rt, GC_NORMAL, gcreason::MAYBEGC);
return;
}
if (comp->gcMallocAndFreeBytes > comp->gcTriggerMallocAndFreeBytes) {
PrepareCompartmentForGC(comp);
GCSlice(rt, GC_NORMAL, gcreason::MAYBEGC);
return;
}
#ifndef JS_MORE_DETERMINISTIC
/*
* Access to the counters and, on 32 bit, setting gcNextFullGCTime below
* is not atomic and a race condition could trigger or suppress the GC. We
* tolerate this.
*/
int64_t now = PRMJ_Now();
if (rt->gcNextFullGCTime && rt->gcNextFullGCTime <= now) {
if (rt->gcChunkAllocationSinceLastGC ||
rt->gcNumArenasFreeCommitted > FreeCommittedArenasThreshold)
{
PrepareForFullGC(rt);
GCSlice(rt, GC_SHRINK, gcreason::MAYBEGC);
} else {
rt->gcNextFullGCTime = now + GC_IDLE_FULL_SPAN;
}
}
#endif
}
static void
DecommitArenasFromAvailableList(JSRuntime *rt, Chunk **availableListHeadp)
{
Chunk *chunk = *availableListHeadp;
if (!chunk)
return;
/*
* Decommit is expensive so we avoid holding the GC lock while calling it.
*
* We decommit from the tail of the list to minimize interference with the
* main thread that may start to allocate things at this point.
*
* The arena that is been decommitted outside the GC lock must not be
* available for allocations either via the free list or via the
* decommittedArenas bitmap. For that we just fetch the arena from the
* free list before the decommit pretending as it was allocated. If this
* arena also is the single free arena in the chunk, then we must remove
* from the available list before we release the lock so the allocation
* thread would not see chunks with no free arenas on the available list.
*
* After we retake the lock, we mark the arena as free and decommitted if
* the decommit was successful. We must also add the chunk back to the
* available list if we removed it previously or when the main thread
* have allocated all remaining free arenas in the chunk.
*
* We also must make sure that the aheader is not accessed again after we
* decommit the arena.
*/
JS_ASSERT(chunk->info.prevp == availableListHeadp);
while (Chunk *next = chunk->info.next) {
JS_ASSERT(next->info.prevp == &chunk->info.next);
chunk = next;
}
for (;;) {
while (chunk->info.numArenasFreeCommitted != 0) {
ArenaHeader *aheader = chunk->fetchNextFreeArena(rt);
Chunk **savedPrevp = chunk->info.prevp;
if (!chunk->hasAvailableArenas())
chunk->removeFromAvailableList();
size_t arenaIndex = Chunk::arenaIndex(aheader->arenaAddress());
bool ok;
{
/*
* If the main thread waits for the decommit to finish, skip
* potentially expensive unlock/lock pair on the contested
* lock.
*/
Maybe<AutoUnlockGC> maybeUnlock;
if (!rt->isHeapBusy())
maybeUnlock.construct(rt);
ok = MarkPagesUnused(aheader->getArena(), ArenaSize);
}
if (ok) {
++chunk->info.numArenasFree;
chunk->decommittedArenas.set(arenaIndex);
} else {
chunk->addArenaToFreeList(rt, aheader);
}
JS_ASSERT(chunk->hasAvailableArenas());
JS_ASSERT(!chunk->unused());
if (chunk->info.numArenasFree == 1) {
/*
* Put the chunk back to the available list either at the
* point where it was before to preserve the available list
* that we enumerate, or, when the allocation thread has fully
* used all the previous chunks, at the beginning of the
* available list.
*/
Chunk **insertPoint = savedPrevp;
if (savedPrevp != availableListHeadp) {
Chunk *prev = Chunk::fromPointerToNext(savedPrevp);
if (!prev->hasAvailableArenas())
insertPoint = availableListHeadp;
}
chunk->insertToAvailableList(insertPoint);
} else {
JS_ASSERT(chunk->info.prevp);
}
if (rt->gcChunkAllocationSinceLastGC) {
/*
* The allocator thread has started to get new chunks. We should stop
* to avoid decommitting arenas in just allocated chunks.
*/
return;
}
}
/*
* chunk->info.prevp becomes null when the allocator thread consumed
* all chunks from the available list.
*/
JS_ASSERT_IF(chunk->info.prevp, *chunk->info.prevp == chunk);
if (chunk->info.prevp == availableListHeadp || !chunk->info.prevp)
break;
/*
* prevp exists and is not the list head. It must point to the next
* field of the previous chunk.
*/
chunk = chunk->getPrevious();
}
}
static void
DecommitArenas(JSRuntime *rt)
{
DecommitArenasFromAvailableList(rt, &rt->gcSystemAvailableChunkListHead);
DecommitArenasFromAvailableList(rt, &rt->gcUserAvailableChunkListHead);
}
/* Must be called with the GC lock taken. */
static void
ExpireChunksAndArenas(JSRuntime *rt, bool shouldShrink)
{
if (Chunk *toFree = rt->gcChunkPool.expire(rt, shouldShrink)) {
AutoUnlockGC unlock(rt);
FreeChunkList(toFree);
}
if (shouldShrink)
DecommitArenas(rt);
}
static void
SweepBackgroundThings(JSRuntime* rt, bool onBackgroundThread)
{
/*
* We must finalize in the correct order, see comments in
* finalizeObjects.
*/
FreeOp fop(rt, false);
for (int phase = 0 ; phase < BackgroundPhaseCount ; ++phase) {
for (JSCompartment *c = rt->gcSweepingCompartments; c; c = c->gcNextCompartment) {
for (int index = 0 ; index < BackgroundPhaseLength[phase] ; ++index) {
AllocKind kind = BackgroundPhases[phase][index];
ArenaHeader *arenas = c->arenas.arenaListsToSweep[kind];
if (arenas) {
ArenaLists::backgroundFinalize(&fop, arenas, onBackgroundThread);
}
}
}
}
while (JSCompartment *c = rt->gcSweepingCompartments) {
rt->gcSweepingCompartments = c->gcNextCompartment;
c->gcNextCompartment = NULL;
}
}
#ifdef JS_THREADSAFE
static void
AssertBackgroundSweepingFinished(JSRuntime *rt)
{
for (CompartmentsIter c(rt); !c.done(); c.next()) {
JS_ASSERT(!c->gcNextCompartment);
for (unsigned i = 0 ; i < FINALIZE_LIMIT ; ++i) {
JS_ASSERT(!c->arenas.arenaListsToSweep[i]);
JS_ASSERT(c->arenas.doneBackgroundFinalize(AllocKind(i)));
}
}
}
unsigned
GetCPUCount()
{
static unsigned ncpus = 0;
if (ncpus == 0) {
# ifdef XP_WIN
SYSTEM_INFO sysinfo;
GetSystemInfo(&sysinfo);
ncpus = unsigned(sysinfo.dwNumberOfProcessors);
# else
long n = sysconf(_SC_NPROCESSORS_ONLN);
ncpus = (n > 0) ? unsigned(n) : 1;
# endif
}
return ncpus;
}
#endif /* JS_THREADSAFE */
bool
GCHelperThread::init()
{
if (!rt->useHelperThreads()) {
backgroundAllocation = false;
return true;
}
#ifdef JS_THREADSAFE
if (!(wakeup = PR_NewCondVar(rt->gcLock)))
return false;
if (!(done = PR_NewCondVar(rt->gcLock)))
return false;
thread = PR_CreateThread(PR_USER_THREAD, threadMain, this, PR_PRIORITY_NORMAL,
PR_GLOBAL_THREAD, PR_JOINABLE_THREAD, 0);
if (!thread)
return false;
backgroundAllocation = (GetCPUCount() >= 2);
#endif /* JS_THREADSAFE */
return true;
}
void
GCHelperThread::finish()
{
if (!rt->useHelperThreads()) {
JS_ASSERT(state == IDLE);
return;
}
#ifdef JS_THREADSAFE
PRThread *join = NULL;
{
AutoLockGC lock(rt);
if (thread && state != SHUTDOWN) {
/*
* We cannot be in the ALLOCATING or CANCEL_ALLOCATION states as
* the allocations should have been stopped during the last GC.
*/
JS_ASSERT(state == IDLE || state == SWEEPING);
if (state == IDLE)
PR_NotifyCondVar(wakeup);
state = SHUTDOWN;
join = thread;
}
}
if (join) {
/* PR_DestroyThread is not necessary. */
PR_JoinThread(join);
}
if (wakeup)
PR_DestroyCondVar(wakeup);
if (done)
PR_DestroyCondVar(done);
#endif /* JS_THREADSAFE */
}
#ifdef JS_THREADSAFE
/* static */
void
GCHelperThread::threadMain(void *arg)
{
PR_SetCurrentThreadName("JS GC Helper");
static_cast<GCHelperThread *>(arg)->threadLoop();
}
void
GCHelperThread::threadLoop()
{
AutoLockGC lock(rt);
/*
* Even on the first iteration the state can be SHUTDOWN or SWEEPING if
* the stop request or the GC and the corresponding startBackgroundSweep call
* happen before this thread has a chance to run.
*/
for (;;) {
switch (state) {
case SHUTDOWN:
return;
case IDLE:
PR_WaitCondVar(wakeup, PR_INTERVAL_NO_TIMEOUT);
break;
case SWEEPING:
doSweep();
if (state == SWEEPING)
state = IDLE;
PR_NotifyAllCondVar(done);
break;
case ALLOCATING:
do {
Chunk *chunk;
{
AutoUnlockGC unlock(rt);
chunk = Chunk::allocate(rt);
}
/* OOM stops the background allocation. */
if (!chunk)
break;
JS_ASSERT(chunk->info.numArenasFreeCommitted == ArenasPerChunk);
rt->gcNumArenasFreeCommitted += ArenasPerChunk;
rt->gcChunkPool.put(chunk);
} while (state == ALLOCATING && rt->gcChunkPool.wantBackgroundAllocation(rt));
if (state == ALLOCATING)
state = IDLE;
break;
case CANCEL_ALLOCATION:
state = IDLE;
PR_NotifyAllCondVar(done);
break;
}
}
}
#endif /* JS_THREADSAFE */
void
GCHelperThread::startBackgroundSweep(bool shouldShrink)
{
JS_ASSERT(rt->useHelperThreads());
#ifdef JS_THREADSAFE
AutoLockGC lock(rt);
JS_ASSERT(state == IDLE);
JS_ASSERT(!sweepFlag);
sweepFlag = true;
shrinkFlag = shouldShrink;
state = SWEEPING;
PR_NotifyCondVar(wakeup);
#endif /* JS_THREADSAFE */
}
/* Must be called with the GC lock taken. */
void
GCHelperThread::startBackgroundShrink()
{
JS_ASSERT(rt->useHelperThreads());
#ifdef JS_THREADSAFE
switch (state) {
case IDLE:
JS_ASSERT(!sweepFlag);
shrinkFlag = true;
state = SWEEPING;
PR_NotifyCondVar(wakeup);
break;
case SWEEPING:
shrinkFlag = true;
break;
case ALLOCATING:
case CANCEL_ALLOCATION:
/*
* If we have started background allocation there is nothing to
* shrink.
*/
break;
case SHUTDOWN:
JS_NOT_REACHED("No shrink on shutdown");
}
#endif /* JS_THREADSAFE */
}
void
GCHelperThread::waitBackgroundSweepEnd()
{
if (!rt->useHelperThreads()) {
JS_ASSERT(state == IDLE);
return;
}
#ifdef JS_THREADSAFE
AutoLockGC lock(rt);
while (state == SWEEPING)
PR_WaitCondVar(done, PR_INTERVAL_NO_TIMEOUT);
if (rt->gcIncrementalState == NO_INCREMENTAL)
AssertBackgroundSweepingFinished(rt);
#endif /* JS_THREADSAFE */
}
void
GCHelperThread::waitBackgroundSweepOrAllocEnd()
{
if (!rt->useHelperThreads()) {
JS_ASSERT(state == IDLE);
return;
}
#ifdef JS_THREADSAFE
AutoLockGC lock(rt);
if (state == ALLOCATING)
state = CANCEL_ALLOCATION;
while (state == SWEEPING || state == CANCEL_ALLOCATION)
PR_WaitCondVar(done, PR_INTERVAL_NO_TIMEOUT);
if (rt->gcIncrementalState == NO_INCREMENTAL)
AssertBackgroundSweepingFinished(rt);
#endif /* JS_THREADSAFE */
}
/* Must be called with the GC lock taken. */
inline void
GCHelperThread::startBackgroundAllocationIfIdle()
{
JS_ASSERT(rt->useHelperThreads());
#ifdef JS_THREADSAFE
if (state == IDLE) {
state = ALLOCATING;
PR_NotifyCondVar(wakeup);
}
#endif /* JS_THREADSAFE */
}
void
GCHelperThread::replenishAndFreeLater(void *ptr)
{
JS_ASSERT(freeCursor == freeCursorEnd);
do {
if (freeCursor && !freeVector.append(freeCursorEnd - FREE_ARRAY_LENGTH))
break;
freeCursor = (void **) js_malloc(FREE_ARRAY_SIZE);
if (!freeCursor) {
freeCursorEnd = NULL;
break;
}
freeCursorEnd = freeCursor + FREE_ARRAY_LENGTH;
*freeCursor++ = ptr;
return;
} while (false);
js_free(ptr);
}
#ifdef JS_THREADSAFE
/* Must be called with the GC lock taken. */
void
GCHelperThread::doSweep()
{
if (sweepFlag) {
sweepFlag = false;
AutoUnlockGC unlock(rt);
SweepBackgroundThings(rt, true);
if (freeCursor) {
void **array = freeCursorEnd - FREE_ARRAY_LENGTH;
freeElementsAndArray(array, freeCursor);
freeCursor = freeCursorEnd = NULL;
} else {
JS_ASSERT(!freeCursorEnd);
}
for (void ***iter = freeVector.begin(); iter != freeVector.end(); ++iter) {
void **array = *iter;
freeElementsAndArray(array, array + FREE_ARRAY_LENGTH);
}
freeVector.resize(0);
rt->freeLifoAlloc.freeAll();
}
bool shrinking = shrinkFlag;
ExpireChunksAndArenas(rt, shrinking);
/*
* The main thread may have called ShrinkGCBuffers while
* ExpireChunksAndArenas(rt, false) was running, so we recheck the flag
* afterwards.
*/
if (!shrinking && shrinkFlag) {
shrinkFlag = false;
ExpireChunksAndArenas(rt, true);
}
}
#endif /* JS_THREADSAFE */
} /* namespace js */
static bool
ReleaseObservedTypes(JSRuntime *rt)
{
bool releaseTypes = rt->gcZeal() != 0;
#ifndef JS_MORE_DETERMINISTIC
int64_t now = PRMJ_Now();
if (now >= rt->gcJitReleaseTime)
releaseTypes = true;
if (releaseTypes)
rt->gcJitReleaseTime = now + JIT_SCRIPT_RELEASE_TYPES_INTERVAL;
#endif
return releaseTypes;
}
static void
SweepCompartments(FreeOp *fop, bool lastGC)
{
JSRuntime *rt = fop->runtime();
JS_ASSERT_IF(lastGC, !rt->hasContexts());
JSDestroyCompartmentCallback callback = rt->destroyCompartmentCallback;
/* Skip the atomsCompartment. */
JSCompartment **read = rt->compartments.begin() + 1;
JSCompartment **end = rt->compartments.end();
JSCompartment **write = read;
JS_ASSERT(rt->compartments.length() >= 1);
JS_ASSERT(*rt->compartments.begin() == rt->atomsCompartment);
while (read < end) {
JSCompartment *compartment = *read++;
if (!compartment->hold && compartment->wasGCStarted() &&
(compartment->arenas.arenaListsAreEmpty() || lastGC))
{
compartment->arenas.checkEmptyFreeLists();
if (callback)
callback(fop, compartment);
if (compartment->principals)
JS_DropPrincipals(rt, compartment->principals);
fop->delete_(compartment);
continue;
}
*write++ = compartment;
}
rt->compartments.resize(write - rt->compartments.begin());
}
static void
PurgeRuntime(JSRuntime *rt)
{
for (GCCompartmentsIter c(rt); !c.done(); c.next())
c->purge();
rt->freeLifoAlloc.transferUnusedFrom(&rt->tempLifoAlloc);
rt->gsnCache.purge();
rt->propertyCache.purge(rt);
rt->newObjectCache.purge();
rt->nativeIterCache.purge();
rt->sourceDataCache.purge();
rt->evalCache.clear();
for (ContextIter acx(rt); !acx.done(); acx.next())
acx->purge();
}
static bool
ShouldPreserveJITCode(JSCompartment *c, int64_t currentTime)
{
if (c->rt->gcShouldCleanUpEverything || !c->types.inferenceEnabled)
return false;
if (c->rt->alwaysPreserveCode)
return true;
if (c->lastAnimationTime + PRMJ_USEC_PER_SEC >= currentTime &&
c->lastCodeRelease + (PRMJ_USEC_PER_SEC * 300) >= currentTime) {
return true;
}
c->lastCodeRelease = currentTime;
return false;
}
#ifdef DEBUG
struct CompartmentCheckTracer : public JSTracer
{
Cell *src;
JSGCTraceKind srcKind;
JSCompartment *compartment;
};
static bool
InCrossCompartmentMap(JSObject *src, Cell *dst, JSGCTraceKind dstKind)
{
JSCompartment *srccomp = src->compartment();
if (dstKind == JSTRACE_OBJECT) {
Value key = ObjectValue(*static_cast<JSObject *>(dst));
if (WrapperMap::Ptr p = srccomp->crossCompartmentWrappers.lookup(key)) {
if (*p->value.unsafeGet() == ObjectValue(*src))
return true;
}
}
/*
* If the cross-compartment edge is caused by the debugger, then we don't
* know the right hashtable key, so we have to iterate.
*/
for (WrapperMap::Enum e(srccomp->crossCompartmentWrappers); !e.empty(); e.popFront()) {
if (e.front().key.wrapped == dst && ToMarkable(e.front().value) == src)
return true;
}
return false;
}
static void
CheckCompartmentCallback(JSTracer *trcArg, void **thingp, JSGCTraceKind kind)
{
CompartmentCheckTracer *trc = static_cast<CompartmentCheckTracer *>(trcArg);
Cell *thing = (Cell *)*thingp;
JS_ASSERT(thing->compartment() == trc->compartment ||
thing->compartment() == trc->runtime->atomsCompartment ||
(trc->srcKind == JSTRACE_OBJECT &&
InCrossCompartmentMap((JSObject *)trc->src, thing, kind)));
}
static void
CheckForCompartmentMismatches(JSRuntime *rt)
{
if (rt->gcDisableStrictProxyCheckingCount)
return;
CompartmentCheckTracer trc;
JS_TracerInit(&trc, rt, CheckCompartmentCallback);
for (CompartmentsIter c(rt); !c.done(); c.next()) {
trc.compartment = c;
for (size_t thingKind = 0; thingKind < FINALIZE_LAST; thingKind++) {
for (CellIterUnderGC i(c, AllocKind(thingKind)); !i.done(); i.next()) {
trc.src = i.getCell();
trc.srcKind = MapAllocToTraceKind(AllocKind(thingKind));
JS_TraceChildren(&trc, trc.src, trc.srcKind);
}
}
}
}
#endif
static void
BeginMarkPhase(JSRuntime *rt)
{
int64_t currentTime = PRMJ_Now();
#ifdef DEBUG
CheckForCompartmentMismatches(rt);
#endif
rt->gcIsFull = true;
DebugOnly<bool> any = false;
for (CompartmentsIter c(rt); !c.done(); c.next()) {
/* Assert that compartment state is as we expect */
JS_ASSERT(!c->isCollecting());
for (unsigned i = 0; i < FINALIZE_LIMIT; ++i)
JS_ASSERT(!c->arenas.arenaListsToSweep[i]);
/* Set up which compartments will be collected. */
if (c->isGCScheduled()) {
any = true;
if (c != rt->atomsCompartment)
c->setGCState(JSCompartment::Mark);
} else {
rt->gcIsFull = false;
}
c->setPreservingCode(ShouldPreserveJITCode(c, currentTime));
c->scheduledForDestruction = false;
c->maybeAlive = false;
}
/* Check that at least one compartment is scheduled for collection. */
JS_ASSERT(any);
/*
* Atoms are not in the cross-compartment map. So if there are any
* compartments that are not being collected, we are not allowed to collect
* atoms. Otherwise, the non-collected compartments could contain pointers
* to atoms that we would miss.
*/
if (rt->atomsCompartment->isGCScheduled() && rt->gcIsFull && !rt->gcKeepAtoms)
rt->atomsCompartment->setGCState(JSCompartment::Mark);
/*
* At the end of each incremental slice, we call prepareForIncrementalGC,
* which marks objects in all arenas that we're currently allocating
* into. This can cause leaks if unreachable objects are in these
* arenas. This purge call ensures that we only mark arenas that have had
* allocations after the incremental GC started.
*/
if (rt->gcIsIncremental) {
for (GCCompartmentsIter c(rt); !c.done(); c.next())
c->arenas.purge();
}
rt->gcMarker.start(rt);
JS_ASSERT(!rt->gcMarker.callback);
JS_ASSERT(IS_GC_MARKING_TRACER(&rt->gcMarker));
/* For non-incremental GC the following sweep discards the jit code. */
if (rt->gcIsIncremental) {
for (GCCompartmentsIter c(rt); !c.done(); c.next()) {
gcstats::AutoPhase ap(rt->gcStats, gcstats::PHASE_MARK_DISCARD_CODE);
c->discardJitCode(rt->defaultFreeOp(), false);
}
}
GCMarker *gcmarker = &rt->gcMarker;
rt->gcStartNumber = rt->gcNumber;
/* Reset weak map list. */
WeakMapBase::resetWeakMapList(rt);
/*
* We must purge the runtime at the beginning of an incremental GC. The
* danger if we purge later is that the snapshot invariant of incremental
* GC will be broken, as follows. If some object is reachable only through
* some cache (say the dtoaCache) then it will not be part of the snapshot.
* If we purge after root marking, then the mutator could obtain a pointer
* to the object and start using it. This object might never be marked, so
* a GC hazard would exist.
*/
{
gcstats::AutoPhase ap(rt->gcStats, gcstats::PHASE_PURGE);
PurgeRuntime(rt);
}
/*
* Mark phase.
*/
gcstats::AutoPhase ap1(rt->gcStats, gcstats::PHASE_MARK);
gcstats::AutoPhase ap2(rt->gcStats, gcstats::PHASE_MARK_ROOTS);
/* Unmark everything in the compartments being collected. */
for (GCCompartmentsIter c(rt); !c.done(); c.next())
c->arenas.unmarkAll();
MarkRuntime(gcmarker);
/*
* This code ensures that if a compartment is "dead", then it will be
* collected in this GC. A compartment is considered dead if its maybeAlive
* flag is false. The maybeAlive flag is set if:
* (1) the compartment has incoming cross-compartment edges, or
* (2) an object in the compartment was marked during root marking, either
* as a black root or a gray root.
* If the maybeAlive is false, then we set the scheduledForDestruction flag.
* At any time later in the GC, if we try to mark an object whose
* compartment is scheduled for destruction, we will assert.
*
* The purpose of this check is to ensure that a compartment that we would
* normally destroy is not resurrected by a read barrier or an
* allocation. This might happen during a function like JS_TransplantObject,
* which iterates over all compartments, live or dead, and operates on their
* objects. See bug 803376 for details on this problem. To avoid the
* problem, we are very careful to avoid allocation and read barriers during
* JS_TransplantObject and the like. The code here ensures that we don't
* regress.
*
* Note that there are certain cases where allocations or read barriers in
* dead compartments are difficult to avoid. We detect such cases (via the
* gcObjectsMarkedInDeadCompartment counter) and redo any ongoing GCs after
* the JS_TransplantObject function has finished. This ensures that the dead
* compartments will be cleaned up. See AutoMarkInDeadCompartment and
* AutoMaybeTouchDeadCompartments for details.
*/
/* Set the maybeAlive flag based on cross-compartment edges. */
for (CompartmentsIter c(rt); !c.done(); c.next()) {
for (WrapperMap::Enum e(c->crossCompartmentWrappers); !e.empty(); e.popFront()) {
Cell *dst = e.front().key.wrapped;
dst->compartment()->maybeAlive = true;
}
if (c->hold)
c->maybeAlive = true;
}
/* Set the maybeAlive flag based on gray roots. */
rt->gcMarker.markBufferedGrayRootCompartmentsAlive();
/*
* For black roots, code in gc/Marking.cpp will already have set maybeAlive
* during MarkRuntime.
*/
for (GCCompartmentsIter c(rt); !c.done(); c.next()) {
if (!c->maybeAlive)
c->scheduledForDestruction = true;
}
}
void
MarkWeakReferences(GCMarker *gcmarker)
{
JS_ASSERT(gcmarker->isDrained());
while (WatchpointMap::markAllIteratively(gcmarker) ||
WeakMapBase::markAllIteratively(gcmarker) ||
Debugger::markAllIteratively(gcmarker))
{
SliceBudget budget;
gcmarker->drainMarkStack(budget);
}
JS_ASSERT(gcmarker->isDrained());
}
static void
MarkGrayAndWeak(JSRuntime *rt)
{
GCMarker *gcmarker = &rt->gcMarker;
{
gcstats::AutoPhase ap(rt->gcStats, gcstats::PHASE_MARK_WEAK);
JS_ASSERT(gcmarker->isDrained());
MarkWeakReferences(gcmarker);
}
{
gcstats::AutoPhase ap(rt->gcStats, gcstats::PHASE_MARK_GRAY);
gcmarker->setMarkColorGray();
if (gcmarker->hasBufferedGrayRoots()) {
gcmarker->markBufferedGrayRoots();
} else {
if (JSTraceDataOp op = rt->gcGrayRootsTraceOp)
(*op)(gcmarker, rt->gcGrayRootsData);
}
SliceBudget budget;
gcmarker->drainMarkStack(budget);
}
{
gcstats::AutoPhase ap(rt->gcStats, gcstats::PHASE_MARK_GRAY_WEAK);
MarkWeakReferences(gcmarker);
}
JS_ASSERT(gcmarker->isDrained());
}
#ifdef DEBUG
static void
ValidateIncrementalMarking(JSRuntime *rt);
#endif
static void
EndMarkPhase(JSRuntime *rt)
{
{
gcstats::AutoPhase ap1(rt->gcStats, gcstats::PHASE_MARK);
MarkGrayAndWeak(rt);
}
JS_ASSERT(rt->gcMarker.isDrained());
#ifdef DEBUG
if (rt->gcIsIncremental && rt->gcValidate)
ValidateIncrementalMarking(rt);
#endif
/*
* Having black->gray edges violates our promise to the cycle
* collector. This can happen if we're collecting a compartment and it has
* an edge to an uncollected compartment: it's possible that the source and
* destination of the cross-compartment edge should be gray, but the source
* was marked black by the conservative scanner.
*/
bool foundBlackGray = false;
for (GCCompartmentsIter c(rt); !c.done(); c.next()) {
for (WrapperMap::Enum e(c->crossCompartmentWrappers); !e.empty(); e.popFront()) {
Cell *dst = e.front().key.wrapped;
Cell *src = ToMarkable(e.front().value);
JS_ASSERT(src->compartment() == c.get());
if (IsCellMarked(&src) && !src->isMarked(GRAY) && dst->isMarked(GRAY)) {
JS_ASSERT(!dst->compartment()->isCollecting());
foundBlackGray = true;
}
}
}
/*
* To avoid the black->gray edge, we completely clear the mark bits of all
* uncollected compartments. This is safe, although it may prevent the
* cycle collector from collecting some dead objects.
*/
if (foundBlackGray) {
for (CompartmentsIter c(rt); !c.done(); c.next()) {
if (!c->isCollecting())
c->arenas.unmarkAll();
}
}
/* We do not discard JIT here code as the following sweeping does that. */
}
#ifdef DEBUG
static void
ValidateIncrementalMarking(JSRuntime *rt)
{
typedef HashMap<Chunk *, uintptr_t *, GCChunkHasher, SystemAllocPolicy> BitmapMap;
BitmapMap map;
if (!map.init())
return;
GCMarker *gcmarker = &rt->gcMarker;
/* Save existing mark bits. */
for (GCChunkSet::Range r(rt->gcChunkSet.all()); !r.empty(); r.popFront()) {
ChunkBitmap *bitmap = &r.front()->bitmap;
uintptr_t *entry = (uintptr_t *)js_malloc(sizeof(bitmap->bitmap));
if (!entry)
return;
memcpy(entry, bitmap->bitmap, sizeof(bitmap->bitmap));
if (!map.putNew(r.front(), entry))
return;
}
/* Save the existing weakmaps. */
WeakMapVector weakmaps;
if (!WeakMapBase::saveWeakMapList(rt, weakmaps))
return;
/*
* After this point, the function should run to completion, so we shouldn't
* do anything fallible.
*/
/* Re-do all the marking, but non-incrementally. */
js::gc::State state = rt->gcIncrementalState;
rt->gcIncrementalState = MARK_ROOTS;
/* As we're re-doing marking, we need to reset the weak map list. */
WeakMapBase::resetWeakMapList(rt);
JS_ASSERT(gcmarker->isDrained());
gcmarker->reset();
for (GCChunkSet::Range r(rt->gcChunkSet.all()); !r.empty(); r.popFront())
r.front()->bitmap.clear();
MarkRuntime(gcmarker, true);
SliceBudget budget;
rt->gcIncrementalState = MARK;
rt->gcMarker.drainMarkStack(budget);
MarkGrayAndWeak(rt);
/* Now verify that we have the same mark bits as before. */
for (GCChunkSet::Range r(rt->gcChunkSet.all()); !r.empty(); r.popFront()) {
Chunk *chunk = r.front();
ChunkBitmap *bitmap = &chunk->bitmap;
uintptr_t *entry = map.lookup(r.front())->value;
ChunkBitmap incBitmap;
memcpy(incBitmap.bitmap, entry, sizeof(incBitmap.bitmap));
js_free(entry);
for (size_t i = 0; i < ArenasPerChunk; i++) {
if (chunk->decommittedArenas.get(i))
continue;
Arena *arena = &chunk->arenas[i];
if (!arena->aheader.allocated())
continue;
if (!arena->aheader.compartment->isCollecting())
continue;
if (arena->aheader.allocatedDuringIncremental)
continue;
AllocKind kind = arena->aheader.getAllocKind();
uintptr_t thing = arena->thingsStart(kind);
uintptr_t end = arena->thingsEnd();
while (thing < end) {
Cell *cell = (Cell *)thing;
JS_ASSERT_IF(bitmap->isMarked(cell, BLACK), incBitmap.isMarked(cell, BLACK));
thing += Arena::thingSize(kind);
}
}
memcpy(bitmap->bitmap, incBitmap.bitmap, sizeof(incBitmap.bitmap));
}
/* Restore the weak map list. */
WeakMapBase::resetWeakMapList(rt);
WeakMapBase::restoreWeakMapList(rt, weakmaps);
rt->gcIncrementalState = state;
}
#endif
/*
* If compartment A has an edge to an unmarked object in compartment B, then we
* must not sweep A in a later slice than we sweep B. That's because a write
* barrier in A that could lead to the unmarked object in B becoming
* marked. However, if we had already swept that object, we would be in trouble.
*
* If we consider these dependencies as a graph, then all the compartments in
* any strongly-connected component of this graph must be swept in the same
* slice. This class is used to compute these strongly connected components via
* Tarjan's algorithm.
*/
class PartitionCompartments
{
typedef unsigned Node;
typedef Vector<Node, 0, SystemAllocPolicy> NodeVector;
typedef Vector<bool, 0, SystemAllocPolicy> BoolVector;
static const Node Undefined = Node(-1);
JSRuntime *runtime;
/*
* The value of clock ticks monotonically upward as each new compartment is
* discovered by the algorithm. When a new SCC is found, it is assigned a
* number from nextSCC.
*/
Node clock, nextSCC;
/*
* Compartments have an index based on their order in rt->compartments. The
* index is used as a subscript into the arrays below.
*
* discoveryTime[comp]: The |clock| value when comp was first explored.
* lowLink[comp]: The minimal discovery time of any compartment reachable
* from |comp|.
* stack: List of explored compartments that haven't been assigned to an SCC.
* scc[comp]: SCC number that |comp| is in.
* onStack[comp]: Whether |comp| in in |stack|.
*/
NodeVector discoveryTime, lowLink, stack, scc;
BoolVector onStack;
bool fail_;
void processNode(Node v);
void fail() { fail_ = true; }
bool failed() { return fail_; }
public:
PartitionCompartments(JSRuntime *rt);
void partition();
unsigned getSCC(JSCompartment *comp) { return failed() ? 0 : scc[comp->index]; }
};
const PartitionCompartments::Node PartitionCompartments::Undefined;
PartitionCompartments::PartitionCompartments(JSRuntime *rt)
: runtime(rt), clock(0), nextSCC(0), fail_(false)
{
size_t n = runtime->compartments.length();
if (!discoveryTime.reserve(n) ||
!lowLink.reserve(n) ||
!scc.reserve(n) ||
!onStack.reserve(n) ||
!stack.reserve(n))
{
fail();
return;
}
for (Node v = 0; v < runtime->compartments.length(); v++) {
runtime->compartments[v]->index = v;
discoveryTime.infallibleAppend(Undefined);
lowLink.infallibleAppend(Undefined);
scc.infallibleAppend(Undefined);
onStack.infallibleAppend(false);
}
}
/* See the Wikipedia article "Tarjan's strongly connected components algorithm". */
void
PartitionCompartments::processNode(Node v)
{
int stackDummy;
if (failed() || !JS_CHECK_STACK_SIZE(js::GetNativeStackLimit(runtime), &stackDummy)) {
fail();
return;
}
discoveryTime[v] = clock;
lowLink[v] = clock;
clock++;
stack.infallibleAppend(v);
onStack[v] = true;
JSCompartment *comp = runtime->compartments[v];
for (WrapperMap::Enum e(comp->crossCompartmentWrappers); !e.empty(); e.popFront()) {
if (e.front().key.kind == CrossCompartmentKey::StringWrapper)
continue;
Cell *other = e.front().key.wrapped;
if (other->isMarked(BLACK) && !other->isMarked(GRAY))
continue;
Node w = other->compartment()->index;
if (discoveryTime[w] == Undefined) {
processNode(w);
lowLink[v] = Min(lowLink[v], lowLink[w]);
} else if (onStack[w]) {
lowLink[v] = Min(lowLink[v], discoveryTime[w]);
}
}
if (lowLink[v] == discoveryTime[v]) {
Node w;
do {
w = stack.popCopy();
onStack[w] = false;
scc[w] = nextSCC;
} while (w != v);
nextSCC++;
}
}
void
PartitionCompartments::partition()
{
if (failed())
return;
for (Node n = 0; n < runtime->compartments.length(); n++) {
if (discoveryTime[n] == Undefined)
processNode(n);
}
}
static void
BeginSweepPhase(JSRuntime *rt)
{
/*
* Sweep phase.
*
* Finalize as we sweep, outside of rt->gcLock but with rt->isHeapBusy()
* true so that any attempt to allocate a GC-thing from a finalizer will
* fail, rather than nest badly and leave the unmarked newborn to be swept.
*
* We first sweep atom state so we can use IsAboutToBeFinalized on
* JSString held in a hashtable to check if the hashtable entry can be
* freed. Note that even after the entry is freed, JSObject finalizers can
* continue to access the corresponding JSString* assuming that they are
* unique. This works since the atomization API must not be called during
* the GC.
*/
gcstats::AutoPhase ap(rt->gcStats, gcstats::PHASE_SWEEP);
/*
* Although there is a runtime-wide gcIsFull flag, it is set in
* BeginMarkPhase. More compartments may have been created since then.
*/
bool isFull = true;
for (CompartmentsIter c(rt); !c.done(); c.next()) {
if (c->isCollecting()) {
if (c != rt->atomsCompartment)
c->setGCState(JSCompartment::Sweep);
} else {
isFull = false;
}
}
JS_ASSERT_IF(isFull, rt->gcIsFull);
#ifdef JS_THREADSAFE
rt->gcSweepOnBackgroundThread = rt->hasContexts() && rt->useHelperThreads();
#endif
/* Purge the ArenaLists before sweeping. */
for (GCCompartmentsIter c(rt); !c.done(); c.next()) {
if (c->isGCSweeping())
c->arenas.purge();
}
FreeOp fop(rt, rt->gcSweepOnBackgroundThread);
{
gcstats::AutoPhase ap(rt->gcStats, gcstats::PHASE_FINALIZE_START);
if (rt->gcFinalizeCallback)
rt->gcFinalizeCallback(&fop, JSFINALIZE_START, !isFull);
}
/* Finalize unreachable (key,value) pairs in all weak maps. */
WeakMapBase::sweepAll(&rt->gcMarker);
rt->debugScopes->sweep();
/* Prune out dead views from ArrayBuffer's view lists. */
ArrayBufferObject::sweepAll(rt);
/* Collect watch points associated with unreachable objects. */
WatchpointMap::sweepAll(rt);
/* Detach unreachable debuggers and global objects from each other. */
Debugger::sweepAll(&fop);
PartitionCompartments partition(rt);
partition.partition();
{
gcstats::AutoPhase ap(rt->gcStats, gcstats::PHASE_SWEEP_COMPARTMENTS);
bool releaseTypes = ReleaseObservedTypes(rt);
for (CompartmentsIter c(rt); !c.done(); c.next()) {
gcstats::AutoSCC scc(rt->gcStats, partition.getSCC(c));
if (c->isCollecting())
c->sweep(&fop, releaseTypes);
else
c->sweepCrossCompartmentWrappers();
}
}
/*
* Queue all GC things in all compartments for sweeping, either in the
* foreground or on the background thread.
*
* Note that order is important here for the background case.
*
* Objects are finalized immediately but this may change in the future.
*/
for (GCCompartmentsIter c(rt); !c.done(); c.next()) {
if (c->isGCSweeping()) {
gcstats::AutoSCC scc(rt->gcStats, partition.getSCC(c));
c->arenas.queueObjectsForSweep(&fop);
}
}
for (GCCompartmentsIter c(rt); !c.done(); c.next()) {
if (c->isGCSweeping()) {
gcstats::AutoSCC scc(rt->gcStats, partition.getSCC(c));
c->arenas.queueStringsForSweep(&fop);
}
}
for (GCCompartmentsIter c(rt); !c.done(); c.next()) {
if (c->isGCSweeping()) {
gcstats::AutoSCC scc(rt->gcStats, partition.getSCC(c));
c->arenas.queueScriptsForSweep(&fop);
}
}
for (GCCompartmentsIter c(rt); !c.done(); c.next()) {
if (c->isGCSweeping()) {
gcstats::AutoSCC scc(rt->gcStats, partition.getSCC(c));
c->arenas.queueShapesForSweep(&fop);
}
}
#ifdef JS_ION
for (GCCompartmentsIter c(rt); !c.done(); c.next()) {
if (c->isGCSweeping()) {
gcstats::AutoSCC scc(rt->gcStats, partition.getSCC(c));
c->arenas.queueIonCodeForSweep(&fop);
}
}
#endif
rt->gcSweepPhase = 0;
rt->gcSweepCompartmentIndex = 0;
rt->gcSweepKindIndex = 0;
{
gcstats::AutoPhase ap(rt->gcStats, gcstats::PHASE_FINALIZE_END);
if (rt->gcFinalizeCallback)
rt->gcFinalizeCallback(&fop, JSFINALIZE_END, !isFull);
}
}
bool
ArenaLists::foregroundFinalize(FreeOp *fop, AllocKind thingKind, SliceBudget &sliceBudget)
{
if (!arenaListsToSweep[thingKind])
return true;
ArenaList &dest = arenaLists[thingKind];
return FinalizeArenas(fop, &arenaListsToSweep[thingKind], dest, thingKind, sliceBudget);
}
static bool
SweepPhase(JSRuntime *rt, SliceBudget &sliceBudget)
{
gcstats::AutoPhase ap(rt->gcStats, gcstats::PHASE_SWEEP);
FreeOp fop(rt, rt->gcSweepOnBackgroundThread);
for (; rt->gcSweepPhase < FinalizePhaseCount ; ++rt->gcSweepPhase) {
gcstats::AutoPhase ap(rt->gcStats, FinalizePhaseStatsPhase[rt->gcSweepPhase]);
ptrdiff_t len = rt->compartments.end() - rt->compartments.begin();
for (; rt->gcSweepCompartmentIndex < len ; ++rt->gcSweepCompartmentIndex) {
JSCompartment *c = rt->compartments.begin()[rt->gcSweepCompartmentIndex];
if (c->wasGCStarted()) {
while (rt->gcSweepKindIndex < FinalizePhaseLength[rt->gcSweepPhase]) {
AllocKind kind = FinalizePhases[rt->gcSweepPhase][rt->gcSweepKindIndex];
if (!c->arenas.foregroundFinalize(&fop, kind, sliceBudget))
return false;
++rt->gcSweepKindIndex;
}
}
rt->gcSweepKindIndex = 0;
}
rt->gcSweepCompartmentIndex = 0;
}
return true;
}
static void
SweepAtomsCompartment(JSRuntime *rt)
{
JSCompartment *c = rt->atomsCompartment;
JS_ASSERT(rt->gcMarker.isDrained());
JS_ASSERT(c->isGCMarking());
c->setGCState(JSCompartment::Sweep);
c->arenas.purge();
{
gcstats::AutoPhase ap2(rt->gcStats, gcstats::PHASE_SWEEP_ATOMS);
SweepAtoms(rt);
}
FreeOp fop(rt, rt->gcSweepOnBackgroundThread);
c->arenas.queueStringsForSweep(&fop);
}
static void
EndSweepPhase(JSRuntime *rt, JSGCInvocationKind gckind, bool lastGC)
{
gcstats::AutoPhase ap(rt->gcStats, gcstats::PHASE_SWEEP);
FreeOp fop(rt, rt->gcSweepOnBackgroundThread);
JS_ASSERT_IF(lastGC, !rt->gcSweepOnBackgroundThread);
JS_ASSERT(rt->gcMarker.isDrained());
rt->gcMarker.stop();
#ifdef DEBUG
PropertyTree::dumpShapes(rt);
#endif
{
gcstats::AutoPhase ap(rt->gcStats, gcstats::PHASE_DESTROY);
/*
* Sweep script filenames after sweeping functions in the generic loop
* above. In this way when a scripted function's finalizer destroys the
* script and calls rt->destroyScriptHook, the hook can still access the
* script's filename. See bug 323267.
*/
if (rt->gcIsFull)
SweepScriptFilenames(rt);
/* Clear out any small pools that we're hanging on to. */
if (JSC::ExecutableAllocator *execAlloc = rt->maybeExecAlloc())
execAlloc->purge();
/*
* This removes compartments from rt->compartment, so we do it last to make
* sure we don't miss sweeping any compartments.
*/
if (!lastGC)
SweepCompartments(&fop, lastGC);
if (!rt->gcSweepOnBackgroundThread) {
/*
* Destroy arenas after we finished the sweeping so finalizers can
* safely use IsAboutToBeFinalized(). This is done on the
* GCHelperThread if possible. We acquire the lock only because
* Expire needs to unlock it for other callers.
*/
AutoLockGC lock(rt);
ExpireChunksAndArenas(rt, gckind == GC_SHRINK);
}
}
/*
* Reset the list of arenas marked as being allocated during sweep phase.
*/
while (ArenaHeader *arena = rt->gcArenasAllocatedDuringSweep) {
rt->gcArenasAllocatedDuringSweep = arena->getNextAllocDuringSweep();
arena->unsetAllocDuringSweep();
}
/* Set up list of compartments for sweeping of background things. */
JS_ASSERT(!rt->gcSweepingCompartments);
for (GCCompartmentsIter c(rt); !c.done(); c.next()) {
c->gcNextCompartment = rt->gcSweepingCompartments;
rt->gcSweepingCompartments = c;
}
/* If not sweeping on background thread then we must do it here. */
if (!rt->gcSweepOnBackgroundThread) {
gcstats::AutoPhase ap(rt->gcStats, gcstats::PHASE_DESTROY);
SweepBackgroundThings(rt, false);
rt->freeLifoAlloc.freeAll();
/* Ensure the compartments get swept if it's the last GC. */
if (lastGC)
SweepCompartments(&fop, lastGC);
}
for (CompartmentsIter c(rt); !c.done(); c.next()) {
c->setGCLastBytes(c->gcBytes, c->gcMallocAndFreeBytes, gckind);
if (c->wasGCStarted())
c->setGCState(JSCompartment::NoGC);
JS_ASSERT(!c->isCollecting());
JS_ASSERT(!c->wasGCStarted());
for (unsigned i = 0 ; i < FINALIZE_LIMIT ; ++i) {
JS_ASSERT_IF(!IsBackgroundFinalized(AllocKind(i)) ||
!rt->gcSweepOnBackgroundThread,
!c->arenas.arenaListsToSweep[i]);
}
}
rt->gcLastGCTime = PRMJ_Now();
}
/*
* This class should be used by any code that needs to exclusive access to the
* heap in order to trace through it...
*/
class AutoTraceSession {
public:
AutoTraceSession(JSRuntime *rt, JSRuntime::HeapState state = JSRuntime::Tracing);
~AutoTraceSession();
protected:
JSRuntime *runtime;
private:
AutoTraceSession(const AutoTraceSession&) MOZ_DELETE;
void operator=(const AutoTraceSession&) MOZ_DELETE;
JSRuntime::HeapState prevState;
};
/* ...while this class is to be used only for garbage collection. */
class AutoGCSession : AutoTraceSession {
public:
explicit AutoGCSession(JSRuntime *rt);
~AutoGCSession();
};
/* Start a new heap session. */
AutoTraceSession::AutoTraceSession(JSRuntime *rt, JSRuntime::HeapState heapState)
: runtime(rt),
prevState(rt->heapState)
{
JS_ASSERT(!rt->noGCOrAllocationCheck);
JS_ASSERT(!rt->isHeapBusy());
JS_ASSERT(heapState == JSRuntime::Collecting || heapState == JSRuntime::Tracing);
rt->heapState = heapState;
}
AutoTraceSession::~AutoTraceSession()
{
JS_ASSERT(runtime->isHeapBusy());
runtime->heapState = prevState;
}
AutoGCSession::AutoGCSession(JSRuntime *rt)
: AutoTraceSession(rt, JSRuntime::Collecting)
{
runtime->gcIsNeeded = false;
runtime->gcInterFrameGC = true;
runtime->gcNumber++;
}
AutoGCSession::~AutoGCSession()
{
#ifndef JS_MORE_DETERMINISTIC
runtime->gcNextFullGCTime = PRMJ_Now() + GC_IDLE_FULL_SPAN;
#endif
runtime->gcChunkAllocationSinceLastGC = false;
#ifdef JS_GC_ZEAL
/* Keeping these around after a GC is dangerous. */
runtime->gcSelectedForMarking.clearAndFree();
#endif
/* Clear gcMallocBytes for all compartments */
for (CompartmentsIter c(runtime); !c.done(); c.next()) {
c->resetGCMallocBytes();
c->unscheduleGC();
}
runtime->resetGCMallocBytes();
}
class AutoCopyFreeListToArenas {
JSRuntime *rt;
public:
AutoCopyFreeListToArenas(JSRuntime *rt)
: rt(rt) {
for (CompartmentsIter c(rt); !c.done(); c.next())
c->arenas.copyFreeListsToArenas();
}
~AutoCopyFreeListToArenas() {
for (CompartmentsIter c(rt); !c.done(); c.next())
c->arenas.clearFreeListsInArenas();
}
};
static void
IncrementalCollectSlice(JSRuntime *rt,
int64_t budget,
gcreason::Reason gcReason,
JSGCInvocationKind gcKind);
static void
ResetIncrementalGC(JSRuntime *rt, const char *reason)
{
if (rt->gcIncrementalState == NO_INCREMENTAL)
return;
/* Cancel and ongoing marking. */
bool wasMarking = false;
{
AutoCopyFreeListToArenas copy(rt);
for (GCCompartmentsIter c(rt); !c.done(); c.next()) {
if (c->isGCMarking()) {
c->setNeedsBarrier(false, JSCompartment::UpdateIon);
c->setGCState(JSCompartment::NoGC);
wasMarking = true;
}
}
}
if (wasMarking)
rt->gcMarker.reset();
if (rt->gcIncrementalState >= SWEEP) {
/* If we had started sweeping then sweep to completion here. */
IncrementalCollectSlice(rt, SliceBudget::Unlimited, gcreason::RESET, GC_NORMAL);
gcstats::AutoPhase ap(rt->gcStats, gcstats::PHASE_WAIT_BACKGROUND_THREAD);
rt->gcHelperThread.waitBackgroundSweepOrAllocEnd();
} else {
JS_ASSERT(rt->gcIncrementalState == MARK);
rt->gcIncrementalState = NO_INCREMENTAL;
rt->gcMarker.stop();
JS_ASSERT(!rt->gcStrictCompartmentChecking);
rt->gcStats.reset(reason);
}
#ifdef DEBUG
for (GCCompartmentsIter c(rt); !c.done(); c.next()) {
JS_ASSERT(c->isCollecting());
JS_ASSERT(!c->needsBarrier());
JS_ASSERT(!c->gcNextCompartment);
for (unsigned i = 0 ; i < FINALIZE_LIMIT ; ++i)
JS_ASSERT(!c->arenas.arenaListsToSweep[i]);
}
#endif
}
class AutoGCSlice {
public:
AutoGCSlice(JSRuntime *rt);
~AutoGCSlice();
private:
JSRuntime *runtime;
};
AutoGCSlice::AutoGCSlice(JSRuntime *rt)
: runtime(rt)
{
/*
* During incremental GC, the compartment's active flag determines whether
* there are stack frames active for any of its scripts. Normally this flag
* is set at the beginning of the mark phase. During incremental GC, we also
* set it at the start of every phase.
*/
rt->stackSpace.markActiveCompartments();
for (GCCompartmentsIter c(rt); !c.done(); c.next()) {
/*
* Clear needsBarrier early so we don't do any write barriers during
* GC. We don't need to update the Ion barriers (which is expensive)
* because Ion code doesn't run during GC. If need be, we'll update the
* Ion barriers in ~AutoGCSlice.
*/
if (c->isGCMarking()) {
JS_ASSERT(c->needsBarrier());
c->setNeedsBarrier(false, JSCompartment::DontUpdateIon);
} else {
JS_ASSERT(!c->needsBarrier());
}
}
}
AutoGCSlice::~AutoGCSlice()
{
/* We can't use GCCompartmentsIter if this is the end of the last slice. */
for (CompartmentsIter c(runtime); !c.done(); c.next()) {
if (c->isGCMarking()) {
c->setNeedsBarrier(true, JSCompartment::UpdateIon);
c->arenas.prepareForIncrementalGC(runtime);
} else {
c->setNeedsBarrier(false, JSCompartment::UpdateIon);
}
}
}
static void
PushZealSelectedObjects(JSRuntime *rt)
{
#ifdef JS_GC_ZEAL
/* Push selected objects onto the mark stack and clear the list. */
for (JSObject **obj = rt->gcSelectedForMarking.begin();
obj != rt->gcSelectedForMarking.end(); obj++)
{
MarkObjectUnbarriered(&rt->gcMarker, obj, "selected obj");
}
#endif
}
static bool
DrainMarkStack(JSRuntime *rt, SliceBudget &sliceBudget)
{
/* Run a marking slice and return whether the stack is now empty. */
gcstats::AutoPhase ap(rt->gcStats, gcstats::PHASE_MARK);
return rt->gcMarker.drainMarkStack(sliceBudget);
}
static void
IncrementalCollectSlice(JSRuntime *rt,
int64_t budget,
gcreason::Reason reason,
JSGCInvocationKind gckind)
{
AutoCopyFreeListToArenas copy(rt);
AutoGCSlice slice(rt);
gc::State initialState = rt->gcIncrementalState;
SliceBudget sliceBudget(budget);
int zeal = 0;
#ifdef JS_GC_ZEAL
if (reason == gcreason::DEBUG_GC && budget != SliceBudget::Unlimited) {
/*
* Do the incremental collection type specified by zeal mode if the
* collection was triggered by RunDebugGC() and incremental GC has not
* been cancelled by ResetIncrementalGC.
*/
zeal = rt->gcZeal();
}
#endif
rt->gcIsIncremental = budget != SliceBudget::Unlimited;
if (zeal == ZealIncrementalRootsThenFinish || zeal == ZealIncrementalMarkAllThenFinish) {
/*
* Yields between slices occurs at predetermined points in these
* modes. sliceBudget is not used.
*/
sliceBudget.reset();
}
if (rt->gcIncrementalState == NO_INCREMENTAL) {
rt->gcIncrementalState = MARK_ROOTS;
rt->gcLastMarkSlice = false;
}
if (rt->gcIncrementalState == MARK)
AutoGCRooter::traceAllWrappers(&rt->gcMarker);
switch (rt->gcIncrementalState) {
case MARK_ROOTS:
BeginMarkPhase(rt);
if (rt->hasContexts())
PushZealSelectedObjects(rt);
rt->gcIncrementalState = MARK;
if (zeal == ZealIncrementalRootsThenFinish)
break;
/* fall through */
case MARK: {
/* If we needed delayed marking for gray roots, then collect until done. */
if (!rt->gcMarker.hasBufferedGrayRoots())
sliceBudget.reset();
bool finished = DrainMarkStack(rt, sliceBudget);
if (!finished)
break;
JS_ASSERT(rt->gcMarker.isDrained());
if (!rt->gcLastMarkSlice &&
((initialState == MARK && budget != SliceBudget::Unlimited) ||
zeal == ZealIncrementalMarkAllThenFinish))
{
/*
* Yield with the aim of starting the sweep in the next
* slice. We will need to mark anything new on the stack
* when we resume, so we stay in MARK state.
*/
rt->gcLastMarkSlice = true;
break;
}
EndMarkPhase(rt);
rt->gcIncrementalState = SWEEP;
/*
* This runs to completion, but we don't continue if the budget is
* now exhasted.
*/
BeginSweepPhase(rt);
if (sliceBudget.isOverBudget())
break;
/*
* Always yield here when running in incremental multi-slice zeal
* mode, so RunDebugGC can reset the slice buget.
*/
if (budget != SliceBudget::Unlimited && zeal == ZealIncrementalMultipleSlices)
break;
/* fall through */
}
case SWEEP: {
bool finished = SweepPhase(rt, sliceBudget);
if (!finished)
break;
rt->gcIncrementalState = SWEEP_END;
if (rt->gcIsIncremental)
break;
}
case SWEEP_END:
if (rt->atomsCompartment->isGCMarking()) {
bool finished = DrainMarkStack(rt, sliceBudget);
if (!finished)
break;
SweepAtomsCompartment(rt);
if (rt->gcIsIncremental)
break;
}
EndSweepPhase(rt, gckind, reason == gcreason::LAST_CONTEXT);
if (rt->gcSweepOnBackgroundThread)
rt->gcHelperThread.startBackgroundSweep(gckind == GC_SHRINK);
rt->gcIncrementalState = NO_INCREMENTAL;
break;
default:
JS_ASSERT(false);
}
}
class IncrementalSafety
{
const char *reason_;
IncrementalSafety(const char *reason) : reason_(reason) {}
public:
static IncrementalSafety Safe() { return IncrementalSafety(NULL); }
static IncrementalSafety Unsafe(const char *reason) { return IncrementalSafety(reason); }
typedef void (IncrementalSafety::* ConvertibleToBool)();
void nonNull() {}
operator ConvertibleToBool() const {
return reason_ == NULL ? &IncrementalSafety::nonNull : 0;
}
const char *reason() {
JS_ASSERT(reason_);
return reason_;
}
};
static IncrementalSafety
IsIncrementalGCSafe(JSRuntime *rt)
{
if (rt->gcKeepAtoms)
return IncrementalSafety::Unsafe("gcKeepAtoms set");
for (CompartmentsIter c(rt); !c.done(); c.next()) {
if (c->activeAnalysis)
return IncrementalSafety::Unsafe("activeAnalysis set");
}
if (!rt->gcIncrementalEnabled)
return IncrementalSafety::Unsafe("incremental permanently disabled");
return IncrementalSafety::Safe();
}
static void
BudgetIncrementalGC(JSRuntime *rt, int64_t *budget)
{
IncrementalSafety safe = IsIncrementalGCSafe(rt);
if (!safe) {
ResetIncrementalGC(rt, safe.reason());
*budget = SliceBudget::Unlimited;
rt->gcStats.nonincremental(safe.reason());
return;
}
if (rt->gcMode != JSGC_MODE_INCREMENTAL) {
ResetIncrementalGC(rt, "GC mode change");
*budget = SliceBudget::Unlimited;
rt->gcStats.nonincremental("GC mode");
return;
}
if (rt->isTooMuchMalloc()) {
*budget = SliceBudget::Unlimited;
rt->gcStats.nonincremental("malloc bytes trigger");
}
bool reset = false;
for (CompartmentsIter c(rt); !c.done(); c.next()) {
if (c->gcBytes >= c->gcTriggerBytes) {
*budget = SliceBudget::Unlimited;
rt->gcStats.nonincremental("allocation trigger");
}
if (c->isTooMuchMalloc()) {
*budget = SliceBudget::Unlimited;
rt->gcStats.nonincremental("malloc bytes trigger");
}
if (rt->gcIncrementalState != NO_INCREMENTAL &&
c->isGCScheduled() != c->wasGCStarted()) {
reset = true;
}
}
if (reset)
ResetIncrementalGC(rt, "compartment change");
}
/*
* GC, repeatedly if necessary, until we think we have not created any new
* garbage. We disable inlining to ensure that the bottom of the stack with
* possible GC roots recorded in MarkRuntime excludes any pointers we use during
* the marking implementation.
*/
static JS_NEVER_INLINE void
GCCycle(JSRuntime *rt, bool incremental, int64_t budget, JSGCInvocationKind gckind, gcreason::Reason reason)
{
/* If we attempt to invoke the GC while we are running in the GC, assert. */
AutoAssertNoGC nogc;
#ifdef DEBUG
for (CompartmentsIter c(rt); !c.done(); c.next())
JS_ASSERT_IF(rt->gcMode == JSGC_MODE_GLOBAL, c->isGCScheduled());
#endif
/* Don't GC if we are reporting an OOM. */
if (rt->inOOMReport)
return;
AutoGCSession gcsession(rt);
/*
* As we about to purge caches and clear the mark bits we must wait for
* any background finalization to finish. We must also wait for the
* background allocation to finish so we can avoid taking the GC lock
* when manipulating the chunks during the GC.
*/
{
gcstats::AutoPhase ap(rt->gcStats, gcstats::PHASE_WAIT_BACKGROUND_THREAD);
rt->gcHelperThread.waitBackgroundSweepOrAllocEnd();
}
{
if (!incremental) {
/* If non-incremental GC was requested, reset incremental GC. */
ResetIncrementalGC(rt, "requested");
rt->gcStats.nonincremental("requested");
budget = SliceBudget::Unlimited;
} else {
BudgetIncrementalGC(rt, &budget);
}
IncrementalCollectSlice(rt, budget, reason, gckind);
}
}
#ifdef JS_GC_ZEAL
static bool
IsDeterministicGCReason(gcreason::Reason reason)
{
if (reason > gcreason::DEBUG_GC && reason != gcreason::CC_FORCED)
return false;
if (reason == gcreason::MAYBEGC)
return false;
return true;
}
#endif
static bool
ShouldCleanUpEverything(JSRuntime *rt, gcreason::Reason reason, JSGCInvocationKind gckind)
{
// During shutdown, we must clean everything up, for the sake of leak
// detection. When a runtime has no contexts, or we're doing a GC before a
// shutdown CC, those are strong indications that we're shutting down.
//
// DEBUG_MODE_GC indicates we're discarding code because the debug mode
// has changed; debug mode affects the results of bytecode analysis, so
// we need to clear everything away.
return !rt->hasContexts() ||
reason == gcreason::SHUTDOWN_CC ||
reason == gcreason::DEBUG_MODE_GC ||
gckind == GC_SHRINK;
}
static void
Collect(JSRuntime *rt, bool incremental, int64_t budget,
JSGCInvocationKind gckind, gcreason::Reason reason)
{
JS_AbortIfWrongThread(rt);
#if JS_TRACE_LOGGING
AutoTraceLog logger(TraceLogging::defaultLogger(),
TraceLogging::GC_START,
TraceLogging::GC_STOP);
#endif
ContextIter cx(rt);
if (!cx.done())
MaybeCheckStackRoots(cx);
#ifdef JS_GC_ZEAL
if (rt->gcDeterministicOnly && !IsDeterministicGCReason(reason))
return;
#endif
JS_ASSERT_IF(!incremental || budget != SliceBudget::Unlimited, JSGC_INCREMENTAL);
#ifdef JS_GC_ZEAL
bool isShutdown = reason == gcreason::SHUTDOWN_CC || !rt->hasContexts();
struct AutoVerifyBarriers {
JSRuntime *runtime;
bool restartPreVerifier;
bool restartPostVerifier;
AutoVerifyBarriers(JSRuntime *rt, bool isShutdown)
: runtime(rt)
{
restartPreVerifier = !isShutdown && rt->gcVerifyPreData;
restartPostVerifier = !isShutdown && rt->gcVerifyPostData;
if (rt->gcVerifyPreData)
EndVerifyPreBarriers(rt);
if (rt->gcVerifyPostData)
EndVerifyPostBarriers(rt);
}
~AutoVerifyBarriers() {
if (restartPreVerifier)
StartVerifyPreBarriers(runtime);
if (restartPostVerifier)
StartVerifyPostBarriers(runtime);
}
} av(rt, isShutdown);
#endif
RecordNativeStackTopForGC(rt);
int compartmentCount = 0;
int collectedCount = 0;
for (CompartmentsIter c(rt); !c.done(); c.next()) {
if (rt->gcMode == JSGC_MODE_GLOBAL)
c->scheduleGC();
/* This is a heuristic to avoid resets. */
if (rt->gcIncrementalState != NO_INCREMENTAL && c->needsBarrier())
c->scheduleGC();
compartmentCount++;
if (c->isGCScheduled())
collectedCount++;
}
rt->gcShouldCleanUpEverything = ShouldCleanUpEverything(rt, reason, gckind);
gcstats::AutoGCSlice agc(rt->gcStats, collectedCount, compartmentCount, reason);
do {
/*
* Let the API user decide to defer a GC if it wants to (unless this
* is the last context). Invoke the callback regardless.
*/
if (rt->gcIncrementalState == NO_INCREMENTAL) {
gcstats::AutoPhase ap(rt->gcStats, gcstats::PHASE_GC_BEGIN);
if (JSGCCallback callback = rt->gcCallback)
callback(rt, JSGC_BEGIN);
}
rt->gcPoke = false;
GCCycle(rt, incremental, budget, gckind, reason);
if (rt->gcIncrementalState == NO_INCREMENTAL) {
gcstats::AutoPhase ap(rt->gcStats, gcstats::PHASE_GC_END);
if (JSGCCallback callback = rt->gcCallback)
callback(rt, JSGC_END);
}
/* Need to re-schedule all compartments for GC. */
if (rt->gcPoke && rt->gcShouldCleanUpEverything)
PrepareForFullGC(rt);
/*
* On shutdown, iterate until finalizers or the JSGC_END callback
* stop creating garbage.
*/
} while (rt->gcPoke && rt->gcShouldCleanUpEverything);
}
namespace js {
void
GC(JSRuntime *rt, JSGCInvocationKind gckind, gcreason::Reason reason)
{
AssertCanGC();
Collect(rt, false, SliceBudget::Unlimited, gckind, reason);
}
void
GCSlice(JSRuntime *rt, JSGCInvocationKind gckind, gcreason::Reason reason, int64_t millis)
{
AssertCanGC();
int64_t sliceBudget;
if (millis)
sliceBudget = SliceBudget::TimeBudget(millis);
else if (rt->gcHighFrequencyGC && rt->gcDynamicMarkSlice)
sliceBudget = rt->gcSliceBudget * IGC_MARK_SLICE_MULTIPLIER;
else
sliceBudget = rt->gcSliceBudget;
Collect(rt, true, sliceBudget, gckind, reason);
}
void
GCFinalSlice(JSRuntime *rt, JSGCInvocationKind gckind, gcreason::Reason reason)
{
AssertCanGC();
Collect(rt, true, SliceBudget::Unlimited, gckind, reason);
}
void
GCDebugSlice(JSRuntime *rt, bool limit, int64_t objCount)
{
AssertCanGC();
int64_t budget = limit ? SliceBudget::WorkBudget(objCount) : SliceBudget::Unlimited;
PrepareForDebugGC(rt);
Collect(rt, true, budget, GC_NORMAL, gcreason::API);
}
/* Schedule a full GC unless a compartment will already be collected. */
void
PrepareForDebugGC(JSRuntime *rt)
{
for (CompartmentsIter c(rt); !c.done(); c.next()) {
if (c->isGCScheduled())
return;
}
PrepareForFullGC(rt);
}
void
ShrinkGCBuffers(JSRuntime *rt)
{
AutoLockGC lock(rt);
JS_ASSERT(!rt->isHeapBusy());
if (!rt->useHelperThreads())
ExpireChunksAndArenas(rt, true);
else
rt->gcHelperThread.startBackgroundShrink();
}
struct AutoFinishGC
{
AutoFinishGC(JSRuntime *rt) {
if (IsIncrementalGCInProgress(rt)) {
PrepareForIncrementalGC(rt);
FinishIncrementalGC(rt, gcreason::API);
}
rt->gcHelperThread.waitBackgroundSweepEnd();
}
};
struct AutoPrepareForTracing
{
AutoFinishGC finish;
AutoTraceSession session;
AutoCopyFreeListToArenas copy;
AutoPrepareForTracing(JSRuntime *rt)
: finish(rt),
session(rt),
copy(rt)
{}
};
void
TraceRuntime(JSTracer *trc)
{
JS_ASSERT(!IS_GC_MARKING_TRACER(trc));
AutoPrepareForTracing prep(trc->runtime);
RecordNativeStackTopForGC(trc->runtime);
MarkRuntime(trc);
}
struct IterateArenaCallbackOp
{
JSRuntime *rt;
void *data;
IterateArenaCallback callback;
JSGCTraceKind traceKind;
size_t thingSize;
IterateArenaCallbackOp(JSRuntime *rt, void *data, IterateArenaCallback callback,
JSGCTraceKind traceKind, size_t thingSize)
: rt(rt), data(data), callback(callback), traceKind(traceKind), thingSize(thingSize)
{}
void operator()(Arena *arena) { (*callback)(rt, data, arena, traceKind, thingSize); }
};
struct IterateCellCallbackOp
{
JSRuntime *rt;
void *data;
IterateCellCallback callback;
JSGCTraceKind traceKind;
size_t thingSize;
IterateCellCallbackOp(JSRuntime *rt, void *data, IterateCellCallback callback,
JSGCTraceKind traceKind, size_t thingSize)
: rt(rt), data(data), callback(callback), traceKind(traceKind), thingSize(thingSize)
{}
void operator()(Cell *cell) { (*callback)(rt, data, cell, traceKind, thingSize); }
};
void
IterateCompartmentsArenasCells(JSRuntime *rt, void *data,
JSIterateCompartmentCallback compartmentCallback,
IterateArenaCallback arenaCallback,
IterateCellCallback cellCallback)
{
AutoPrepareForTracing prop(rt);
for (CompartmentsIter c(rt); !c.done(); c.next()) {
(*compartmentCallback)(rt, data, c);
for (size_t thingKind = 0; thingKind != FINALIZE_LIMIT; thingKind++) {
JSGCTraceKind traceKind = MapAllocToTraceKind(AllocKind(thingKind));
size_t thingSize = Arena::thingSize(AllocKind(thingKind));
IterateArenaCallbackOp arenaOp(rt, data, arenaCallback, traceKind, thingSize);
IterateCellCallbackOp cellOp(rt, data, cellCallback, traceKind, thingSize);
ForEachArenaAndCell(c, AllocKind(thingKind), arenaOp, cellOp);
}
}
}
void
IterateChunks(JSRuntime *rt, void *data, IterateChunkCallback chunkCallback)
{
AutoPrepareForTracing prep(rt);
for (js::GCChunkSet::Range r = rt->gcChunkSet.all(); !r.empty(); r.popFront())
chunkCallback(rt, data, r.front());
}
void
IterateCells(JSRuntime *rt, JSCompartment *compartment, AllocKind thingKind,
void *data, IterateCellCallback cellCallback)
{
AutoPrepareForTracing prep(rt);
JSGCTraceKind traceKind = MapAllocToTraceKind(thingKind);
size_t thingSize = Arena::thingSize(thingKind);
if (compartment) {
for (CellIterUnderGC i(compartment, thingKind); !i.done(); i.next())
cellCallback(rt, data, i.getCell(), traceKind, thingSize);
} else {
for (CompartmentsIter c(rt); !c.done(); c.next()) {
for (CellIterUnderGC i(c, thingKind); !i.done(); i.next())
cellCallback(rt, data, i.getCell(), traceKind, thingSize);
}
}
}
void
IterateGrayObjects(JSCompartment *compartment, GCThingCallback *cellCallback, void *data)
{
JS_ASSERT(compartment);
AutoPrepareForTracing prep(compartment->rt);
for (size_t finalizeKind = 0; finalizeKind <= FINALIZE_OBJECT_LAST; finalizeKind++) {
for (CellIterUnderGC i(compartment, AllocKind(finalizeKind)); !i.done(); i.next()) {
Cell *cell = i.getCell();
if (cell->isMarked(GRAY))
cellCallback(data, cell);
}
}
}
namespace gc {
JSCompartment *
NewCompartment(JSContext *cx, JSPrincipals *principals)
{
JSRuntime *rt = cx->runtime;
JS_AbortIfWrongThread(rt);
JSCompartment *compartment = cx->new_<JSCompartment>(rt);
if (compartment && compartment->init(cx)) {
// Set up the principals.
JS_SetCompartmentPrincipals(compartment, principals);
compartment->setGCLastBytes(8192, 8192, GC_NORMAL);
/*
* Before reporting the OOM condition, |lock| needs to be cleaned up,
* hence the scoping.
*/
{
AutoLockGC lock(rt);
if (rt->compartments.append(compartment))
return compartment;
}
js_ReportOutOfMemory(cx);
}
js_delete(compartment);
return NULL;
}
void
RunDebugGC(JSContext *cx)
{
#ifdef JS_GC_ZEAL
JSRuntime *rt = cx->runtime;
PrepareForDebugGC(cx->runtime);
int type = rt->gcZeal();
if (type == ZealIncrementalRootsThenFinish ||
type == ZealIncrementalMarkAllThenFinish ||
type == ZealIncrementalMultipleSlices)
{
js::gc::State initialState = rt->gcIncrementalState;
int64_t budget;
if (type == ZealIncrementalMultipleSlices) {
/*
* Start with a small slice limit and double it every slice. This
* ensure that we get multiple slices, and collection runs to
* completion.
*/
if (initialState == NO_INCREMENTAL)
rt->gcIncrementalLimit = rt->gcZealFrequency / 2;
else
rt->gcIncrementalLimit *= 2;
budget = SliceBudget::WorkBudget(rt->gcIncrementalLimit);
} else {
// This triggers incremental GC but is actually ignored by IncrementalMarkSlice.
budget = SliceBudget::WorkBudget(1);
}
Collect(rt, true, budget, GC_NORMAL, gcreason::DEBUG_GC);
/*
* For multi-slice zeal, reset the slice size when we get to the sweep
* phase.
*/
if (type == ZealIncrementalMultipleSlices &&
initialState == MARK && rt->gcIncrementalState == SWEEP)
{
rt->gcIncrementalLimit = rt->gcZealFrequency / 2;
}
} else if (type == ZealPurgeAnalysisValue) {
if (!cx->compartment->activeAnalysis)
cx->compartment->types.maybePurgeAnalysis(cx, /* force = */ true);
} else {
Collect(rt, false, SliceBudget::Unlimited, GC_NORMAL, gcreason::DEBUG_GC);
}
#endif
}
void
SetDeterministicGC(JSContext *cx, bool enabled)
{
#ifdef JS_GC_ZEAL
JSRuntime *rt = cx->runtime;
rt->gcDeterministicOnly = enabled;
#endif
}
void
SetValidateGC(JSContext *cx, bool enabled)
{
JSRuntime *rt = cx->runtime;
rt->gcValidate = enabled;
}
} /* namespace gc */
} /* namespace js */
#if defined(DEBUG) && defined(JS_GC_ZEAL) && defined(JSGC_ROOT_ANALYSIS) && !defined(JS_THREADSAFE)
JS_ALWAYS_INLINE bool
CheckStackRootThing(uintptr_t *w, void *address, ThingRootKind kind)
{
if (kind != THING_ROOT_BINDINGS)
return address == static_cast<void*>(w);
Bindings *bp = static_cast<Bindings*>(address);
return w >= (uintptr_t*)bp && w < (uintptr_t*)(bp + 1);
}
JS_ALWAYS_INLINE void
CheckStackRootThings(uintptr_t *w, Rooted<void*> *rooter, ThingRootKind kind, bool *matched)
{
while (rooter) {
if (CheckStackRootThing(w, rooter->address(), kind))
*matched = true;
rooter = rooter->previous();
}
}
static void
CheckStackRoot(JSTracer *trc, uintptr_t *w)
{
/* Mark memory as defined for valgrind, as in MarkWordConservatively. */
#ifdef JS_VALGRIND
VALGRIND_MAKE_MEM_DEFINED(&w, sizeof(w));
#endif
ConservativeGCTest test = MarkIfGCThingWord(trc, *w);
if (test == CGCT_VALID) {
bool matched = false;
JSRuntime *rt = trc->runtime;
for (unsigned i = 0; i < THING_ROOT_LIMIT; i++) {
CheckStackRootThings(w, rt->mainThread.thingGCRooters[i],
ThingRootKind(i), &matched);
for (ContextIter cx(rt); !cx.done(); cx.next()) {
CheckStackRootThings(w, cx->thingGCRooters[i], ThingRootKind(i), &matched);
SkipRoot *skip = cx->skipGCRooters;
while (skip) {
if (skip->contains(reinterpret_cast<uint8_t*>(w), sizeof(w)))
matched = true;
skip = skip->previous();
}
}
}
if (!matched) {
/*
* Only poison the last byte in the word. It is easy to get
* accidental collisions when a value that does not occupy a full
* word is used to overwrite a now-dead GC thing pointer. In this
* case we want to avoid damaging the smaller value.
*/
PoisonPtr(w);
}
}
}
static void
CheckStackRootsRange(JSTracer *trc, uintptr_t *begin, uintptr_t *end)
{
JS_ASSERT(begin <= end);
for (uintptr_t *i = begin; i != end; ++i)
CheckStackRoot(trc, i);
}
static void
CheckStackRootsRangeAndSkipIon(JSRuntime *rt, JSTracer *trc, uintptr_t *begin, uintptr_t *end)
{
/*
* Regions of the stack between Ion activiations are marked exactly through
* a different mechanism. We need to skip these regions when checking the
* stack so that we do not poison IonMonkey's things.
*/
uintptr_t *i = begin;
#if JS_STACK_GROWTH_DIRECTION < 0 && defined(JS_ION)
for (ion::IonActivationIterator ion(rt); ion.more(); ++ion) {
uintptr_t *ionMin, *ionEnd;
ion.ionStackRange(ionMin, ionEnd);
CheckStackRootsRange(trc, i, ionMin);
i = ionEnd;
}
#endif
/* The topmost Ion activiation may be beyond our prior top. */
if (i <= end)
CheckStackRootsRange(trc, i, end);
}
static void
EmptyMarkCallback(JSTracer *jstrc, void **thingp, JSGCTraceKind kind)
{}
void
JS::CheckStackRoots(JSContext *cx)
{
JSRuntime *rt = cx->runtime;
if (rt->gcZeal_ != ZealStackRootingSafeValue && rt->gcZeal_ != ZealStackRootingValue)
return;
if (rt->gcZeal_ == ZealStackRootingSafeValue && !rt->gcExactScanningEnabled)
return;
// If this assertion fails, it means that an AutoAssertNoGC was placed
// around code that could trigger GC, and is therefore wrong. The
// AutoAssertNoGC should be removed and the code it was guarding should be
// modified to properly root any gcthings, and very possibly any code
// calling that function should also be modified if it was improperly
// assuming that GC could not happen at all within the called function.
// (The latter may not apply if the AutoAssertNoGC only protected a portion
// of a function, so the callers were already assuming that GC could
// happen.)
JS_ASSERT(!InNoGCScope());
// GCs can't happen when analysis/inference/compilation are active.
if (cx->compartment->activeAnalysis)
return;
// Can switch to the atoms compartment during analysis.
if (IsAtomsCompartment(cx->compartment)) {
for (CompartmentsIter c(rt); !c.done(); c.next()) {
if (c.get()->activeAnalysis)
return;
}
}
AutoCopyFreeListToArenas copy(rt);
JSTracer checker;
JS_TracerInit(&checker, rt, EmptyMarkCallback);
ConservativeGCData *cgcd = &rt->conservativeGC;
cgcd->recordStackTop();
JS_ASSERT(cgcd->hasStackToScan());
uintptr_t *stackMin, *stackEnd;
#if JS_STACK_GROWTH_DIRECTION > 0
stackMin = rt->nativeStackBase;
stackEnd = cgcd->nativeStackTop;
#else
stackMin = cgcd->nativeStackTop + 1;
stackEnd = reinterpret_cast<uintptr_t *>(rt->nativeStackBase);
uintptr_t *&oldStackMin = cgcd->oldStackMin, *&oldStackEnd = cgcd->oldStackEnd;
uintptr_t *&oldStackData = cgcd->oldStackData;
uintptr_t &oldStackCapacity = cgcd->oldStackCapacity;
/*
* Adjust the stack to remove regions which have not changed since the
* stack was last scanned, and update the last scanned state.
*/
if (stackEnd != oldStackEnd) {
js_free(oldStackData);
oldStackCapacity = rt->nativeStackQuota / sizeof(uintptr_t);
oldStackData = (uintptr_t *) rt->malloc_(oldStackCapacity * sizeof(uintptr_t));
if (!oldStackData) {
oldStackCapacity = 0;
} else {
uintptr_t *existing = stackEnd - 1, *copy = oldStackData;
while (existing >= stackMin && size_t(copy - oldStackData) < oldStackCapacity)
*copy++ = *existing--;
oldStackEnd = stackEnd;
oldStackMin = existing + 1;
}
} else {
uintptr_t *existing = stackEnd - 1, *copy = oldStackData;
while (existing >= stackMin && existing >= oldStackMin && *existing == *copy) {
copy++;
existing--;
}
stackEnd = existing + 1;
while (existing >= stackMin && size_t(copy - oldStackData) < oldStackCapacity)
*copy++ = *existing--;
oldStackMin = existing + 1;
}
#endif
JS_ASSERT(stackMin <= stackEnd);
CheckStackRootsRangeAndSkipIon(rt, &checker, stackMin, stackEnd);
CheckStackRootsRange(&checker, cgcd->registerSnapshot.words,
ArrayEnd(cgcd->registerSnapshot.words));
}
#endif /* DEBUG && JS_GC_ZEAL && JSGC_ROOT_ANALYSIS && !JS_THREADSAFE */
namespace js {
namespace gc {
#ifdef JS_GC_ZEAL
/*
* Write barrier verification
*
* The next few functions are for write barrier verification.
*
* The VerifyBarriers function is a shorthand. It checks if a verification phase
* is currently running. If not, it starts one. Otherwise, it ends the current
* phase and starts a new one.
*
* The user can adjust the frequency of verifications, which causes
* VerifyBarriers to be a no-op all but one out of N calls. However, if the
* |always| parameter is true, it starts a new phase no matter what.
*
* Pre-Barrier Verifier:
* When StartVerifyBarriers is called, a snapshot is taken of all objects in
* the GC heap and saved in an explicit graph data structure. Later,
* EndVerifyBarriers traverses the heap again. Any pointer values that were in
* the snapshot and are no longer found must be marked; otherwise an assertion
* triggers. Note that we must not GC in between starting and finishing a
* verification phase.
*
* Post-Barrier Verifier:
* When StartVerifyBarriers is called, we create a virtual "Nursery Set" which
* future allocations are recorded in and turn on the StoreBuffer. Later,
* EndVerifyBarriers traverses the heap and ensures that the set of cross-
* generational pointers we find is a subset of the pointers recorded in our
* StoreBuffer.
*/
struct EdgeValue
{
void *thing;
JSGCTraceKind kind;
char *label;
};
struct VerifyNode
{
void *thing;
JSGCTraceKind kind;
uint32_t count;
EdgeValue edges[1];
};
typedef HashMap<void *, VerifyNode *, DefaultHasher<void *>, SystemAllocPolicy> NodeMap;
/*
* The verifier data structures are simple. The entire graph is stored in a
* single block of memory. At the beginning is a VerifyNode for the root
* node. It is followed by a sequence of EdgeValues--the exact number is given
* in the node. After the edges come more nodes and their edges.
*
* The edgeptr and term fields are used to allocate out of the block of memory
* for the graph. If we run out of memory (i.e., if edgeptr goes beyond term),
* we just abandon the verification.
*
* The nodemap field is a hashtable that maps from the address of the GC thing
* to the VerifyNode that represents it.
*/
struct VerifyPreTracer : JSTracer {
/* The gcNumber when the verification began. */
uint64_t number;
/* This counts up to gcZealFrequency to decide whether to verify. */
int count;
/* This graph represents the initial GC "snapshot". */
VerifyNode *curnode;
VerifyNode *root;
char *edgeptr;
char *term;
NodeMap nodemap;
VerifyPreTracer() : root(NULL) {}
~VerifyPreTracer() { js_free(root); }
};
/*
* This function builds up the heap snapshot by adding edges to the current
* node.
*/
static void
AccumulateEdge(JSTracer *jstrc, void **thingp, JSGCTraceKind kind)
{
VerifyPreTracer *trc = (VerifyPreTracer *)jstrc;
trc->edgeptr += sizeof(EdgeValue);
if (trc->edgeptr >= trc->term) {
trc->edgeptr = trc->term;
return;
}
VerifyNode *node = trc->curnode;
uint32_t i = node->count;
node->edges[i].thing = *thingp;
node->edges[i].kind = kind;
node->edges[i].label = trc->debugPrinter ? NULL : (char *)trc->debugPrintArg;
node->count++;
}
static VerifyNode *
MakeNode(VerifyPreTracer *trc, void *thing, JSGCTraceKind kind)
{
NodeMap::AddPtr p = trc->nodemap.lookupForAdd(thing);
if (!p) {
VerifyNode *node = (VerifyNode *)trc->edgeptr;
trc->edgeptr += sizeof(VerifyNode) - sizeof(EdgeValue);
if (trc->edgeptr >= trc->term) {
trc->edgeptr = trc->term;
return NULL;
}
node->thing = thing;
node->count = 0;
node->kind = kind;
trc->nodemap.add(p, thing, node);
return node;
}
return NULL;
}
static
VerifyNode *
NextNode(VerifyNode *node)
{
if (node->count == 0)
return (VerifyNode *)((char *)node + sizeof(VerifyNode) - sizeof(EdgeValue));
else
return (VerifyNode *)((char *)node + sizeof(VerifyNode) +
sizeof(EdgeValue)*(node->count - 1));
}
static void
StartVerifyPreBarriers(JSRuntime *rt)
{
if (rt->gcVerifyPreData || rt->gcIncrementalState != NO_INCREMENTAL)
return;
AutoTraceSession session(rt);
if (!IsIncrementalGCSafe(rt))
return;
rt->gcHelperThread.waitBackgroundSweepOrAllocEnd();
AutoCopyFreeListToArenas copy(rt);
RecordNativeStackTopForGC(rt);
for (GCChunkSet::Range r(rt->gcChunkSet.all()); !r.empty(); r.popFront())
r.front()->bitmap.clear();
VerifyPreTracer *trc = js_new<VerifyPreTracer>();
rt->gcNumber++;
trc->number = rt->gcNumber;
trc->count = 0;
JS_TracerInit(trc, rt, AccumulateEdge);
const size_t size = 64 * 1024 * 1024;
trc->root = (VerifyNode *)js_malloc(size);
JS_ASSERT(trc->root);
trc->edgeptr = (char *)trc->root;
trc->term = trc->edgeptr + size;
if (!trc->nodemap.init())
return;
/* Create the root node. */
trc->curnode = MakeNode(trc, NULL, JSGCTraceKind(0));
/* We want MarkRuntime to save the roots to gcSavedRoots. */
rt->gcIncrementalState = MARK_ROOTS;
/* Make all the roots be edges emanating from the root node. */
MarkRuntime(trc);
VerifyNode *node = trc->curnode;
if (trc->edgeptr == trc->term)
goto oom;
/* For each edge, make a node for it if one doesn't already exist. */
while ((char *)node < trc->edgeptr) {
for (uint32_t i = 0; i < node->count; i++) {
EdgeValue &e = node->edges[i];
VerifyNode *child = MakeNode(trc, e.thing, e.kind);
if (child) {
trc->curnode = child;
JS_TraceChildren(trc, e.thing, e.kind);
}
if (trc->edgeptr == trc->term)
goto oom;
}
node = NextNode(node);
}
rt->gcVerifyPreData = trc;
rt->gcIncrementalState = MARK;
rt->gcMarker.start(rt);
for (CompartmentsIter c(rt); !c.done(); c.next()) {
PurgeJITCaches(c);
c->setNeedsBarrier(true, JSCompartment::UpdateIon);
c->arenas.purge();
}
return;
oom:
rt->gcIncrementalState = NO_INCREMENTAL;
trc->~VerifyPreTracer();
js_free(trc);
}
static bool
IsMarkedOrAllocated(Cell *cell)
{
return cell->isMarked() || cell->arenaHeader()->allocatedDuringIncremental;
}
const static uint32_t MAX_VERIFIER_EDGES = 1000;
/*
* This function is called by EndVerifyBarriers for every heap edge. If the edge
* already existed in the original snapshot, we "cancel it out" by overwriting
* it with NULL. EndVerifyBarriers later asserts that the remaining non-NULL
* edges (i.e., the ones from the original snapshot that must have been
* modified) must point to marked objects.
*/
static void
CheckEdge(JSTracer *jstrc, void **thingp, JSGCTraceKind kind)
{
VerifyPreTracer *trc = (VerifyPreTracer *)jstrc;
VerifyNode *node = trc->curnode;
/* Avoid n^2 behavior. */
if (node->count > MAX_VERIFIER_EDGES)
return;
for (uint32_t i = 0; i < node->count; i++) {
if (node->edges[i].thing == *thingp) {
JS_ASSERT(node->edges[i].kind == kind);
node->edges[i].thing = NULL;
return;
}
}
}
static void
AssertMarkedOrAllocated(const EdgeValue &edge)
{
if (!edge.thing || IsMarkedOrAllocated(static_cast<Cell *>(edge.thing)))
return;
char msgbuf[1024];
const char *label = edge.label ? edge.label : "<unknown>";
JS_snprintf(msgbuf, sizeof(msgbuf), "[barrier verifier] Unmarked edge: %s", label);
MOZ_ReportAssertionFailure(msgbuf, __FILE__, __LINE__);
MOZ_CRASH();
}
static void
EndVerifyPreBarriers(JSRuntime *rt)
{
AutoTraceSession session(rt);
rt->gcHelperThread.waitBackgroundSweepOrAllocEnd();
AutoCopyFreeListToArenas copy(rt);
RecordNativeStackTopForGC(rt);
VerifyPreTracer *trc = (VerifyPreTracer *)rt->gcVerifyPreData;
if (!trc)
return;
bool compartmentCreated = false;
/* We need to disable barriers before tracing, which may invoke barriers. */
for (CompartmentsIter c(rt); !c.done(); c.next()) {
if (!c->needsBarrier())
compartmentCreated = true;
PurgeJITCaches(c);
c->setNeedsBarrier(false, JSCompartment::UpdateIon);
}
/*
* We need to bump gcNumber so that the methodjit knows that jitcode has
* been discarded.
*/
JS_ASSERT(trc->number == rt->gcNumber);
rt->gcNumber++;
rt->gcVerifyPreData = NULL;
rt->gcIncrementalState = NO_INCREMENTAL;
if (!compartmentCreated && IsIncrementalGCSafe(rt)) {
JS_TracerInit(trc, rt, CheckEdge);
/* Start after the roots. */
VerifyNode *node = NextNode(trc->root);
while ((char *)node < trc->edgeptr) {
trc->curnode = node;
JS_TraceChildren(trc, node->thing, node->kind);
if (node->count <= MAX_VERIFIER_EDGES) {
for (uint32_t i = 0; i < node->count; i++)
AssertMarkedOrAllocated(node->edges[i]);
}
node = NextNode(node);
}
}
rt->gcMarker.reset();
rt->gcMarker.stop();
trc->~VerifyPreTracer();
js_free(trc);
}
/*** Post-Barrier Verifyier ***/
struct VerifyPostTracer : JSTracer {
/* The gcNumber when the verification began. */
uint64_t number;
/* This counts up to gcZealFrequency to decide whether to verify. */
int count;
};
/*
* The post-barrier verifier runs the full store buffer and a fake nursery when
* running and when it stops, walks the full heap to ensure that all the
* important edges were inserted into the storebuffer.
*/
static void
StartVerifyPostBarriers(JSRuntime *rt)
{
#ifdef JSGC_GENERATIONAL
if (!rt->gcExactScanningEnabled ||
rt->gcVerifyPostData ||
rt->gcIncrementalState != NO_INCREMENTAL)
{
return;
}
VerifyPostTracer *trc = js_new<VerifyPostTracer>();
rt->gcVerifyPostData = trc;
rt->gcNumber++;
trc->number = rt->gcNumber;
trc->count = 0;
for (CompartmentsIter c(rt); !c.done(); c.next()) {
if (IsAtomsCompartment(c))
continue;
if (!c->gcNursery.enable())
goto oom;
if (!c->gcStoreBuffer.enable())
goto oom;
}
return;
oom:
trc->~VerifyPostTracer();
js_free(trc);
rt->gcVerifyPostData = NULL;
for (CompartmentsIter c(rt); !c.done(); c.next()) {
c->gcNursery.disable();
c->gcStoreBuffer.disable();
}
#endif
}
#ifdef JSGC_GENERATIONAL
static void
AssertStoreBufferContainsEdge(StoreBuffer *storebuf, void *loc, void *dst)
{
if (storebuf->containsEdgeAt(loc))
return;
char msgbuf[1024];
JS_snprintf(msgbuf, sizeof(msgbuf), "[post-barrier verifier] Missing edge @ %p to %p",
loc, dst);
MOZ_ReportAssertionFailure(msgbuf, __FILE__, __LINE__);
MOZ_CRASH();
}
static void
PostVerifierVisitEdge(JSTracer *jstrc, void **thingp, JSGCTraceKind kind)
{
VerifyPostTracer *trc = (VerifyPostTracer *)jstrc;
Cell *dst = (Cell *)*thingp;
JSCompartment *comp = dst->compartment();
/*
* Note: watchpoint markAll will give us cross-compartment pointers into the
* atoms compartment.
*/
if (IsAtomsCompartment(comp))
return;
/* Filter out non cross-generational edges. */
if (!comp->gcNursery.isInside(dst))
return;
/*
* Note: since Value travels through the stack to get Cell**, we need to use
* the annotated location in the tracer instead of the indirect location for
* these edges.
*/
Cell *loc = (Cell *)(trc->realLocation != NULL ? trc->realLocation : thingp);
AssertStoreBufferContainsEdge(&comp->gcStoreBuffer, loc, dst);
}
#endif
static void
EndVerifyPostBarriers(JSRuntime *rt)
{
#ifdef JSGC_GENERATIONAL
AutoTraceSession session(rt);
rt->gcHelperThread.waitBackgroundSweepOrAllocEnd();
AutoCopyFreeListToArenas copy(rt);
RecordNativeStackTopForGC(rt);
VerifyPostTracer *trc = (VerifyPostTracer *)rt->gcVerifyPostData;
JS_TracerInit(trc, rt, PostVerifierVisitEdge);
trc->count = 0;
if (!rt->gcExactScanningEnabled)
goto oom;
for (CompartmentsIter c(rt); !c.done(); c.next()) {
if (c->gcStoreBuffer.hasOverflowed())
continue;
if (!c->gcStoreBuffer.coalesceForVerification())
goto oom;
}
/* Walk the heap. */
for (CompartmentsIter c(rt); !c.done(); c.next()) {
if (!c->gcStoreBuffer.isEnabled() ||
c->gcStoreBuffer.hasOverflowed() ||
IsAtomsCompartment(c))
{
continue;
}
if (c->watchpointMap)
c->watchpointMap->markAll(trc);
for (size_t kind = 0; kind < FINALIZE_LIMIT; ++kind) {
for (CellIterUnderGC cells(c, AllocKind(kind)); !cells.done(); cells.next()) {
Cell *src = cells.getCell();
if (!c->gcNursery.isInside(src))
JS_TraceChildren(trc, src, MapAllocToTraceKind(AllocKind(kind)));
}
}
}
oom:
trc->~VerifyPostTracer();
js_free(trc);
rt->gcVerifyPostData = NULL;
for (CompartmentsIter c(rt); !c.done(); c.next()) {
c->gcNursery.disable();
c->gcStoreBuffer.disable();
c->gcStoreBuffer.releaseVerificationData();
}
#endif
}
/*** Barrier Verifier Scheduling ***/
static void
VerifyPreBarriers(JSRuntime *rt)
{
if (rt->gcVerifyPreData)
EndVerifyPreBarriers(rt);
else
StartVerifyPreBarriers(rt);
}
static void
VerifyPostBarriers(JSRuntime *rt)
{
if (rt->gcVerifyPostData)
EndVerifyPostBarriers(rt);
else
StartVerifyPostBarriers(rt);
}
void
VerifyBarriers(JSRuntime *rt, VerifierType type)
{
if (type == PreBarrierVerifier)
VerifyPreBarriers(rt);
else
VerifyPostBarriers(rt);
}
static void
MaybeVerifyPreBarriers(JSRuntime *rt, bool always)
{
if (rt->gcZeal() != ZealVerifierPreValue)
return;
if (VerifyPreTracer *trc = (VerifyPreTracer *)rt->gcVerifyPreData) {
if (++trc->count < rt->gcZealFrequency && !always)
return;
EndVerifyPreBarriers(rt);
}
StartVerifyPreBarriers(rt);
}
static void
MaybeVerifyPostBarriers(JSRuntime *rt, bool always)
{
if (rt->gcZeal() != ZealVerifierPostValue)
return;
if (VerifyPostTracer *trc = (VerifyPostTracer *)rt->gcVerifyPostData) {
if (++trc->count < rt->gcZealFrequency && !always)
return;
EndVerifyPostBarriers(rt);
}
StartVerifyPostBarriers(rt);
}
void
MaybeVerifyBarriers(JSContext *cx, bool always)
{
MaybeVerifyPreBarriers(cx->runtime, always);
MaybeVerifyPostBarriers(cx->runtime, always);
}
void
FinishVerifier(JSRuntime *rt)
{
if (VerifyPreTracer *trc = (VerifyPreTracer *)rt->gcVerifyPreData) {
trc->~VerifyPreTracer();
js_free(trc);
}
#ifdef JSGC_GENERATIONAL
if (VerifyPostTracer *trc = (VerifyPostTracer *)rt->gcVerifyPostData) {
trc->~VerifyPostTracer();
js_free(trc);
for (CompartmentsIter c(rt); !c.done(); c.next()) {
c->gcNursery.disable();
c->gcStoreBuffer.disable();
}
}
#endif
}
#endif /* JS_GC_ZEAL */
} /* namespace gc */
void ReleaseAllJITCode(FreeOp *fop)
{
#ifdef JS_METHODJIT
for (CompartmentsIter c(fop->runtime()); !c.done(); c.next()) {
mjit::ClearAllFrames(c);
# ifdef JS_ION
ion::InvalidateAll(fop, c);
# endif
for (CellIter i(c, FINALIZE_SCRIPT); !i.done(); i.next()) {
JSScript *script = i.get<JSScript>();
mjit::ReleaseScriptCode(fop, script);
# ifdef JS_ION
ion::FinishInvalidation(fop, script);
# endif
}
}
#endif
}
/*
* There are three possible PCCount profiling states:
*
* 1. None: Neither scripts nor the runtime have count information.
* 2. Profile: Active scripts have count information, the runtime does not.
* 3. Query: Scripts do not have count information, the runtime does.
*
* When starting to profile scripts, counting begins immediately, with all JIT
* code discarded and recompiled with counts as necessary. Active interpreter
* frames will not begin profiling until they begin executing another script
* (via a call or return).
*
* The below API functions manage transitions to new states, according
* to the table below.
*
* Old State
* -------------------------
* Function None Profile Query
* --------
* StartPCCountProfiling Profile Profile Profile
* StopPCCountProfiling None Query Query
* PurgePCCounts None None None
*/
static void
ReleaseScriptCounts(FreeOp *fop)
{
JSRuntime *rt = fop->runtime();
JS_ASSERT(rt->scriptAndCountsVector);
ScriptAndCountsVector &vec = *rt->scriptAndCountsVector;
for (size_t i = 0; i < vec.length(); i++)
vec[i].scriptCounts.destroy(fop);
fop->delete_(rt->scriptAndCountsVector);
rt->scriptAndCountsVector = NULL;
}
JS_FRIEND_API(void)
StartPCCountProfiling(JSContext *cx)
{
JSRuntime *rt = cx->runtime;
if (rt->profilingScripts)
return;
if (rt->scriptAndCountsVector)
ReleaseScriptCounts(rt->defaultFreeOp());
ReleaseAllJITCode(rt->defaultFreeOp());
rt->profilingScripts = true;
}
JS_FRIEND_API(void)
StopPCCountProfiling(JSContext *cx)
{
JSRuntime *rt = cx->runtime;
if (!rt->profilingScripts)
return;
JS_ASSERT(!rt->scriptAndCountsVector);
ReleaseAllJITCode(rt->defaultFreeOp());
ScriptAndCountsVector *vec = cx->new_<ScriptAndCountsVector>(SystemAllocPolicy());
if (!vec)
return;
for (CompartmentsIter c(rt); !c.done(); c.next()) {
for (CellIter i(c, FINALIZE_SCRIPT); !i.done(); i.next()) {
JSScript *script = i.get<JSScript>();
if (script->hasScriptCounts && script->types) {
ScriptAndCounts sac;
sac.script = script;
sac.scriptCounts.set(script->releaseScriptCounts());
if (!vec->append(sac))
sac.scriptCounts.destroy(rt->defaultFreeOp());
}
}
}
rt->profilingScripts = false;
rt->scriptAndCountsVector = vec;
}
JS_FRIEND_API(void)
PurgePCCounts(JSContext *cx)
{
JSRuntime *rt = cx->runtime;
if (!rt->scriptAndCountsVector)
return;
JS_ASSERT(!rt->profilingScripts);
ReleaseScriptCounts(rt->defaultFreeOp());
}
void
PurgeJITCaches(JSCompartment *c)
{
#ifdef JS_METHODJIT
mjit::ClearAllFrames(c);
for (CellIterUnderGC i(c, FINALIZE_SCRIPT); !i.done(); i.next()) {
JSScript *script = i.get<JSScript>();
/* Discard JM caches. */
mjit::PurgeCaches(script);
#ifdef JS_ION
/* Discard Ion caches. */
ion::PurgeCaches(script, c);
#endif
}
#endif
}
AutoMaybeTouchDeadCompartments::AutoMaybeTouchDeadCompartments(JSContext *cx)
: runtime(cx->runtime),
markCount(runtime->gcObjectsMarkedInDeadCompartments),
inIncremental(IsIncrementalGCInProgress(runtime)),
manipulatingDeadCompartments(runtime->gcManipulatingDeadCompartments)
{
runtime->gcManipulatingDeadCompartments = true;
}
AutoMaybeTouchDeadCompartments::AutoMaybeTouchDeadCompartments(JSObject *obj)
: runtime(obj->compartment()->rt),
markCount(runtime->gcObjectsMarkedInDeadCompartments),
inIncremental(IsIncrementalGCInProgress(runtime)),
manipulatingDeadCompartments(runtime->gcManipulatingDeadCompartments)
{
runtime->gcManipulatingDeadCompartments = true;
}
AutoMaybeTouchDeadCompartments::~AutoMaybeTouchDeadCompartments()
{
if (inIncremental && runtime->gcObjectsMarkedInDeadCompartments != markCount) {
PrepareForFullGC(runtime);
js::GC(runtime, GC_NORMAL, gcreason::TRANSPLANT);
}
runtime->gcManipulatingDeadCompartments = manipulatingDeadCompartments;
}
} /* namespace js */
JS_PUBLIC_API(void)
JS_IterateCompartments(JSRuntime *rt, void *data,
JSIterateCompartmentCallback compartmentCallback)
{
JS_ASSERT(!rt->isHeapBusy());
AutoTraceSession session(rt);
rt->gcHelperThread.waitBackgroundSweepOrAllocEnd();
for (CompartmentsIter c(rt); !c.done(); c.next())
(*compartmentCallback)(rt, data, c);
}
#if JS_HAS_XML_SUPPORT
extern size_t sE4XObjectsCreated;
JSXML *
js_NewGCXML(JSContext *cx)
{
if (!cx->runningWithTrustedPrincipals())
++sE4XObjectsCreated;
return NewGCThing<JSXML>(cx, js::gc::FINALIZE_XML, sizeof(JSXML));
}
#endif
