Changeset 226010 in webkit for trunk/Source/JavaScriptCore/heap/MarkingConstraintSet.h

Timestamp:

Dec 17, 2017, 2:53:51 AM (8 years ago)

Author:

Yusuke Suzuki

Message:

[JSC] Number of SlotVisitors can increase after setting up m_visitCounters
​https://bugs.webkit.org/show_bug.cgi?id=180906

Reviewed by Filip Pizlo.

The number of SlotVisitors can increase after setting up m_visitCounters.
If it happens, our m_visitCounters misses the visit count of newly added
SlotVisitors. It accidentally decides that constraints are converged.
This leads to random assertion hits in Linux environment.

In this patch, we compare the number of SlotVisitors in didVisitSomething().
If the number of SlotVisitors is changed, we conservatively say we did
visit something.

• heap/Heap.h:
• heap/HeapInlines.h:

(JSC::Heap::numberOfSlotVisitors):

• heap/MarkingConstraintSet.h:
• heap/MarkingConstraintSolver.cpp:

(JSC::MarkingConstraintSolver::didVisitSomething const):

File:

• trunk/Source/JavaScriptCore/heap/MarkingConstraintSet.h (modified) (1 diff)

trunk/Source/JavaScriptCore/heap/MarkingConstraintSet.h

@@ -68 +68 @@
     bool executeConvergenceImpl(SlotVisitor&);
     
-    bool drain(SlotVisitor&, BitVector& unexecuted, BitVector& executed, bool& didVisitSomething);
-    
     Heap& m_heap;
     BitVector m_unexecutedRoots;