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Backed out changeset 617df479fac1 (bug 1167452)
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MANUAL PUSH: manually backing out https://phabricator.services.mozilla.com/D31955 and I don't know how to juggle phabricator revisions for this purpose

--HG--
extra : rebase_source : 223fb45141b98fe5b81546f4a6335082504b35b3
extra : source : 01dbc21154a9f77c5b15d9e6f14d608ef2cc9d39
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@hotsphink
hotsphink committed Jul 24, 2019
1 parent 98bb6c0 commit 60139b0
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Showing 3 changed files with 39 additions and 70 deletions.
33 changes: 11 additions & 22 deletions js/src/gc/GCMarker.h
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Original file line number Diff line number Diff line change
Expand Up @@ -231,11 +231,8 @@ class GCMarker : public JSTracer {
explicit GCMarker(JSRuntime* rt);
MOZ_MUST_USE bool init(JSGCMode gcMode);

void setMaxCapacity(size_t maxCap) {
blackStack.setMaxCapacity(maxCap);
grayStack.setMaxCapacity(maxCap);
}
size_t maxCapacity() const { return blackStack.maxCapacity(); }
void setMaxCapacity(size_t maxCap) { stack.setMaxCapacity(maxCap); }
size_t maxCapacity() const { return stack.maxCapacity(); }

void start();
void stop();
Expand Down Expand Up @@ -311,10 +308,7 @@ class GCMarker : public JSTracer {

MOZ_MUST_USE bool markUntilBudgetExhausted(SliceBudget& budget);

void setGCMode(JSGCMode mode) {
blackStack.setGCMode(mode);
grayStack.setGCMode(mode);
}
void setGCMode(JSGCMode mode) { stack.setGCMode(mode); }

size_t sizeOfExcludingThis(mozilla::MallocSizeOf mallocSizeOf) const;

Expand Down Expand Up @@ -376,13 +370,11 @@ class GCMarker : public JSTracer {

inline void pushValueArray(JSObject* obj, HeapSlot* start, HeapSlot* end);

bool isMarkStackEmpty() {
return blackStack.isEmpty() && grayStack.isEmpty();
}
bool isMarkStackEmpty() { return stack.isEmpty(); }

bool hasBlackEntries() const { return !blackStack.isEmpty(); }
bool hasBlackEntries() const { return stack.position() > grayPosition; }

bool hasGrayEntries() const { return !grayStack.isEmpty(); }
bool hasGrayEntries() const { return grayPosition > 0 && !stack.isEmpty(); }

MOZ_MUST_USE bool restoreValueArray(
const gc::MarkStack::SavedValueArray& array, HeapSlot** vpp,
Expand All @@ -406,18 +398,15 @@ class GCMarker : public JSTracer {
template <typename F>
void forEachDelayedMarkingArena(F&& f);

/* The stack of items to mark black. */
gc::MarkStack blackStack;
/* The stack of items to mark (CC) gray. */
gc::MarkStack grayStack;
/* The mark stack. Pointers in this stack are "gray" in the GC sense. */
gc::MarkStack stack;

/* Stack entries at positions below this are considered gray. */
MainThreadData<size_t> grayPosition;

/* The color is only applied to objects and functions. */
MainThreadData<gc::MarkColor> color;

gc::MarkStack& currentStack() {
return color == gc::MarkColor::Black ? blackStack : grayStack;
}

/* Pointer to the top of the stack of arenas we are delaying marking on. */
MainThreadData<js::gc::Arena*> delayedMarkingList;

Expand Down
74 changes: 28 additions & 46 deletions js/src/gc/Marking.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1131,7 +1131,6 @@ inline void js::GCMarker::eagerlyMarkChildren(JSRope* rope) {
// users of the stack. This also assumes that a rope can only point to
// other ropes or linear strings, it cannot refer to GC things of other
// types.
gc::MarkStack& stack = currentStack();
size_t savedPos = stack.position();
JS_DIAGNOSTICS_ASSERT(rope->getTraceKind() == JS::TraceKind::String);
#ifdef JS_DEBUG
Expand Down Expand Up @@ -1624,25 +1623,14 @@ bool GCMarker::markUntilBudgetExhausted(SliceBudget& budget) {
if (hasGrayEntries()) {
AutoSetMarkColor autoSetGray(*this, MarkColor::Gray);
do {
MOZ_ASSERT(!hasBlackEntries());
processMarkStackTop(budget);
if (budget.isOverBudget()) {
return false;
}
} while (hasGrayEntries());
}

if (hasBlackEntries()) {
// We can end up marking black during gray marking in the following case:
// we have a WeakMap with a CCW key whose delegate is black, and during
// gray marking we mark the map (gray). The delegate's color will be
// propagated to the key. (And we can't avoid this by marking the key
// gray, because even though the value will end up gray in either case,
// the WeakMap entry must be (strongly) preserved because the CCW could
// get collected and then we could re-wrap the delegate and look it up in
// the map again.)
continue;
}

if (!hasDelayedChildren()) {
break;
}
Expand Down Expand Up @@ -1723,8 +1711,6 @@ inline void GCMarker::processMarkStackTop(SliceBudget& budget) {
HeapSlot* end;
JSObject* obj;

gc::MarkStack& stack = currentStack();

switch (stack.peekTag()) {
case MarkStack::ValueArrayTag: {
auto array = stack.popValueArray();
Expand Down Expand Up @@ -1891,26 +1877,23 @@ scan_obj : {
*/

void GCMarker::saveValueRanges() {
gc::MarkStack* stacks[2] = {&blackStack, &grayStack};
for (auto& stack : stacks) {
MarkStackIter iter(*stack);
while (!iter.done()) {
auto tag = iter.peekTag();
if (tag == MarkStack::ValueArrayTag) {
const auto& array = iter.peekValueArray();
auto savedArray = saveValueRange(array);
iter.saveValueArray(savedArray);
iter.nextArray();
} else if (tag == MarkStack::SavedValueArrayTag) {
iter.nextArray();
} else {
iter.nextPtr();
}
MarkStackIter iter(stack);
while (!iter.done()) {
auto tag = iter.peekTag();
if (tag == MarkStack::ValueArrayTag) {
const auto& array = iter.peekValueArray();
auto savedArray = saveValueRange(array);
iter.saveValueArray(savedArray);
iter.nextArray();
} else if (tag == MarkStack::SavedValueArrayTag) {
iter.nextArray();
} else {
iter.nextPtr();
}

// This is also a convenient point to poison unused stack memory.
stack->poisonUnused();
}

// This is also a convenient point to poison unused stack memory.
stack.poisonUnused();
}

bool GCMarker::restoreValueArray(const MarkStack::SavedValueArray& savedArray,
Expand Down Expand Up @@ -2386,8 +2369,8 @@ void MarkStackIter::saveValueArray(
*/
GCMarker::GCMarker(JSRuntime* rt)
: JSTracer(rt, JSTracer::TracerKindTag::Marking, ExpandWeakMaps),
blackStack(),
grayStack(),
stack(),
grayPosition(0),
color(MarkColor::Black),
delayedMarkingList(nullptr),
delayedMarkingWorkAdded(false)
Expand All @@ -2402,9 +2385,7 @@ GCMarker::GCMarker(JSRuntime* rt)
{
}

bool GCMarker::init(JSGCMode gcMode) {
return blackStack.init(gcMode) && grayStack.init(gcMode);
}
bool GCMarker::init(JSGCMode gcMode) { return stack.init(gcMode); }

void GCMarker::start() {
#ifdef DEBUG
Expand Down Expand Up @@ -2435,8 +2416,7 @@ void GCMarker::stop() {
#endif

/* Free non-ballast stack memory. */
blackStack.clear();
grayStack.clear();
stack.clear();
AutoEnterOOMUnsafeRegion oomUnsafe;
for (GCZonesIter zone(runtime()); !zone.done(); zone.next()) {
if (!zone->gcWeakKeys().clear()) {
Expand All @@ -2462,8 +2442,7 @@ inline void GCMarker::forEachDelayedMarkingArena(F&& f) {
void GCMarker::reset() {
color = MarkColor::Black;

blackStack.clear();
grayStack.clear();
stack.clear();
MOZ_ASSERT(isMarkStackEmpty());

forEachDelayedMarkingArena([&](Arena* arena) {
Expand Down Expand Up @@ -2492,23 +2471,27 @@ void GCMarker::setMarkColor(gc::MarkColor newColor) {
}

void GCMarker::setMarkColorGray() {
MOZ_ASSERT(!hasBlackEntries());
MOZ_ASSERT(color == gc::MarkColor::Black);
MOZ_ASSERT(runtime()->gc.state() == State::Sweep);

color = gc::MarkColor::Gray;
grayPosition = SIZE_MAX;
}

void GCMarker::setMarkColorBlack() {
MOZ_ASSERT(!hasBlackEntries());
MOZ_ASSERT(color == gc::MarkColor::Gray);
MOZ_ASSERT(runtime()->gc.state() == State::Sweep);

color = gc::MarkColor::Black;
grayPosition = stack.position();
}

template <typename T>
void GCMarker::pushTaggedPtr(T* ptr) {
checkZone(ptr);
if (!currentStack().push(ptr)) {
if (!stack.push(ptr)) {
delayMarkingChildren(ptr);
}
}
Expand All @@ -2520,7 +2503,7 @@ void GCMarker::pushValueArray(JSObject* obj, HeapSlot* start, HeapSlot* end) {
return;
}

if (!currentStack().push(obj, start, end)) {
if (!stack.push(obj, start, end)) {
delayMarkingChildren(obj);
}
}
Expand Down Expand Up @@ -2732,8 +2715,7 @@ void GCMarker::checkZone(void* p) {
#endif

size_t GCMarker::sizeOfExcludingThis(mozilla::MallocSizeOf mallocSizeOf) const {
size_t size = blackStack.sizeOfExcludingThis(mallocSizeOf);
size += grayStack.sizeOfExcludingThis(mallocSizeOf);
size_t size = stack.sizeOfExcludingThis(mallocSizeOf);
for (ZonesIter zone(runtime(), WithAtoms); !zone.done(); zone.next()) {
size += zone->gcGrayRoots().SizeOfExcludingThis(mallocSizeOf);
}
Expand Down
2 changes: 0 additions & 2 deletions js/src/gc/Zone.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -6,8 +6,6 @@

#include "gc/Zone-inl.h"

#include "jsutil.h"

#include "gc/FreeOp.h"
#include "gc/Policy.h"
#include "gc/PublicIterators.h"
Expand Down

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