Rename MarkedSpace::version/MarkedBlock::version to MarkedSpace::markingVersion/Marke...
authorfpizlo@apple.com <fpizlo@apple.com@268f45cc-cd09-0410-ab3c-d52691b4dbfc>
Tue, 20 Sep 2016 21:04:06 +0000 (21:04 +0000)
committerfpizlo@apple.com <fpizlo@apple.com@268f45cc-cd09-0410-ab3c-d52691b4dbfc>
Tue, 20 Sep 2016 21:04:06 +0000 (21:04 +0000)
commit4d29fa1bce4dad0c8eca2bda299598a92e2f7b08
treeeeeb9f3c1b3d844770464f9c2b26cba96792d36a
parent654a116296f1e95dcdfd61ed1087b07562db49f8
Rename MarkedSpace::version/MarkedBlock::version to MarkedSpace::markingVersion/MarkedBlock::markingVersion
https://bugs.webkit.org/show_bug.cgi?id=162310

Reviewed by Geoffrey Garen.

In bug 162309, which is part of my concurrent GC work, I'll need to introduce a second
version-based flip. This one will be for newlyAllocated bits. This will allow me to
cheaply preserve per-object live state during marking. MarkedBlock::aboutToMarkSlow() will
do this instead of clearMarks():

    - Walk the mark bits, simultaneously counting the number of set bits and clearing
      them.
    - If the count is zero, then we're done.
    - If the count is equal to the max number of cells in the block, then set the
      allocated bit for the block.
    - If the count is something else, create a newlyAllocated vector.

The hope is that the last mode is going to be rare, since most blocks are not fragmented
at end of GC. Usually, we will fill them in with objects by allocating! But if we do
create newlyAllocated bits then we need to have some way of blowing them away later.

This is where a second version comes in. We can have a version for newlyAllocated bits,
which we increment at the end of marking, at around the same time that we clear all
allocated bits.

This means that the MarkedBlock will have two different version-based flips, so terms like
"flip" and "version" aren't enough.

This patch gets rid of the term "flip" entirely. It's a term of art in GCs that refers to
the state change at the beginning or end of GC. It refers to the logical state change, not
the physical one. It doesn't actually make sense to speak of a block being flipped
independently of other blocks. It's true that our implementation of the flip makes some
state updates happen lazily, but the block updating itself in some way (like clearing mark
bits) isn't the flip - the flip already happened when the version was incremented.

We no longer refer to a version without qualifying what kind of version it is. The type is
HeapVersion. All of the version members were renamed to markingVersion, to reflect the
fact that this version is just used for doing things to marking state. Instead of asking
if the block needsFlip(), we ask if areMarksStale().

This will let us introduce a second version for newlyAllocated, and will let us speak of
the two versions unambiguously.

* heap/CellContainer.h:
* heap/CellContainerInlines.h:
(JSC::CellContainer::isMarked):
(JSC::CellContainer::isMarkedOrNewlyAllocated):
(JSC::CellContainer::aboutToMark):
(JSC::CellContainer::areMarksStale):
(JSC::CellContainer::needsFlip): Deleted.
* heap/ConservativeRoots.cpp:
(JSC::ConservativeRoots::genericAddPointer):
(JSC::ConservativeRoots::genericAddSpan):
* heap/HeapInlines.h:
(JSC::Heap::isMarked):
(JSC::Heap::isMarkedConcurrently):
(JSC::Heap::testAndSetMarked):
* heap/HeapUtil.h:
(JSC::HeapUtil::findGCObjectPointersForMarking):
* heap/MarkedAllocator.cpp:
(JSC::MarkedAllocator::isPagedOut):
* heap/MarkedBlock.cpp:
(JSC::MarkedBlock::MarkedBlock):
(JSC::MarkedBlock::Handle::specializedSweep):
(JSC::MarkedBlock::Handle::sweepHelperSelectSweepMode):
(JSC::MarkedBlock::Handle::sweepHelperSelectMarksMode):
(JSC::MarkedBlock::aboutToMarkSlow):
(JSC::MarkedBlock::clearMarks):
(JSC::MarkedBlock::assertMarksNotStale):
(JSC::MarkedBlock::areMarksStale):
(JSC::MarkedBlock::Handle::areMarksStale):
(JSC::MarkedBlock::isMarked):
(JSC::MarkedBlock::Handle::isMarkedOrNewlyAllocated):
(JSC::MarkedBlock::isMarkedOrNewlyAllocated):
(JSC::MarkedBlock::markCount):
(JSC::MarkedBlock::Handle::isLive):
(JSC::MarkedBlock::Handle::isLiveCell):
(JSC::MarkedBlock::Handle::sweepHelperSelectFlipMode): Deleted.
(JSC::MarkedBlock::assertFlipped): Deleted.
(JSC::MarkedBlock::needsFlip): Deleted.
(JSC::MarkedBlock::Handle::needsFlip): Deleted.
* heap/MarkedBlock.h:
(JSC::MarkedBlock::areMarksStale):
(JSC::MarkedBlock::aboutToMark):
(JSC::MarkedBlock::assertMarksNotStale):
(JSC::MarkedBlock::Handle::assertMarksNotStale):
(JSC::MarkedBlock::isMarked):
(JSC::MarkedBlock::isMarkedConcurrently):
(JSC::MarkedBlock::testAndSetMarked):
(JSC::MarkedBlock::Handle::isMarkedOrNewlyAllocated):
(JSC::MarkedBlock::isMarkedOrNewlyAllocated):
(JSC::MarkedBlock::needsFlip): Deleted.
(JSC::MarkedBlock::assertFlipped): Deleted.
(JSC::MarkedBlock::Handle::assertFlipped): Deleted.
* heap/MarkedBlockInlines.h:
(JSC::MarkedBlock::Handle::isLive):
(JSC::MarkedBlock::Handle::isLiveCell):
(JSC::MarkedBlock::resetMarkingVersion):
(JSC::MarkedBlock::resetVersion): Deleted.
* heap/MarkedSpace.cpp:
(JSC::MarkedSpace::beginMarking):
* heap/MarkedSpace.h:
(JSC::MarkedSpace::markingVersion):
(JSC::MarkedSpace::version): Deleted.
* heap/SlotVisitor.cpp:
(JSC::SlotVisitor::SlotVisitor):
(JSC::SlotVisitor::didStartMarking):
(JSC::SlotVisitor::appendJSCellOrAuxiliary):
(JSC::SlotVisitor::setMarkedAndAppendToMarkStack):
(JSC::SlotVisitor::markAuxiliary):
* heap/SlotVisitor.h:
(JSC::SlotVisitor::markingVersion):
(JSC::SlotVisitor::version): Deleted.
* heap/WeakBlock.cpp:
(JSC::WeakBlock::specializedVisit):
(JSC::WeakBlock::reap):

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@206172 268f45cc-cd09-0410-ab3c-d52691b4dbfc
15 files changed:
Source/JavaScriptCore/ChangeLog
Source/JavaScriptCore/heap/CellContainer.h
Source/JavaScriptCore/heap/CellContainerInlines.h
Source/JavaScriptCore/heap/ConservativeRoots.cpp
Source/JavaScriptCore/heap/HeapInlines.h
Source/JavaScriptCore/heap/HeapUtil.h
Source/JavaScriptCore/heap/MarkedAllocator.cpp
Source/JavaScriptCore/heap/MarkedBlock.cpp
Source/JavaScriptCore/heap/MarkedBlock.h
Source/JavaScriptCore/heap/MarkedBlockInlines.h
Source/JavaScriptCore/heap/MarkedSpace.cpp
Source/JavaScriptCore/heap/MarkedSpace.h
Source/JavaScriptCore/heap/SlotVisitor.cpp
Source/JavaScriptCore/heap/SlotVisitor.h
Source/JavaScriptCore/heap/WeakBlock.cpp