Don't grow GC memory after an incremental GC

If the last GC was incremental, it would not clean up all garbage.
Thus we should not look at the used memory after such a GC to determine
whether we need to allocate additional memory.

Change-Id: I57c33eeec63c16310920bc3dae074f4dcbb73d27
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

2 files changed, 5 insertions, 2 deletions

diff --git a/src/qml/memory/qv4mm.cpp b/src/qml/memory/qv4mm.cpp
index 233b83fcc0..1a1d92aa0e 100644
--- a/src/qml/memory/qv4mm.cpp
+++ b/src/qml/memory/qv4mm.cpp
@@ -1010,8 +1010,7 @@ void MemoryManager::sweep(bool lastSweep)
 bool MemoryManager::shouldRunGC() const
 {
     size_t total = blockAllocator.totalSlots();
-    size_t usedSlots = blockAllocator.usedSlotsAfterLastSweep;
-    if (total > MinSlotsGCLimit && usedSlots * GCOverallocation < total * 100)
+    if (total > MinSlotsGCLimit && usedSlotsAfterLastFullSweep * GCOverallocation < total * 100)
         return true;
     return false;
 }
@@ -1124,6 +1123,9 @@ void MemoryManager::runGC(bool forceFullCollection)
         Q_ASSERT(blockAllocator.allocatedMem() == getUsedMem() + dumpBins(&blockAllocator, false));
     }
 
+    if (!nextGCIsIncremental)
+        usedSlotsAfterLastFullSweep = blockAllocator.usedSlotsAfterLastSweep;
+
 #if WRITEBARRIER(steele)
     static int count = 0;
     ++count;
diff --git a/src/qml/memory/qv4mm_p.h b/src/qml/memory/qv4mm_p.h
index 437e50cbe7..7f02a4f929 100644
--- a/src/qml/memory/qv4mm_p.h
+++ b/src/qml/memory/qv4mm_p.h
@@ -463,6 +463,7 @@ public:
 
     std::size_t unmanagedHeapSize = 0; // the amount of bytes of heap that is not managed by the memory manager, but which is held onto by managed items.
     std::size_t unmanagedHeapSizeGCLimit;
+    std::size_t usedSlotsAfterLastFullSweep = 0;
 
     bool gcBlocked = false;
     bool aggressiveGC = false;