Statistics of LayoutBox rare data reasons

third_party/WebKit/Source/core/layout/LayoutObject.h

Index: third_party/WebKit/Source/core/layout/LayoutObject.h
diff --git a/third_party/WebKit/Source/core/layout/LayoutObject.h b/third_party/WebKit/Source/core/layout/LayoutObject.h
index ac9462f73910d0dbe23ccc828005c2807dda3866..80279b478075591638d70290ed3d97e07d9f696c 100644
--- a/third_party/WebKit/Source/core/layout/LayoutObject.h
+++ b/third_party/WebKit/Source/core/layout/LayoutObject.h
@@ -75,6 +75,109 @@ struct PaintInvalidatorContext;
 
 enum VisualRectFlags { DefaultVisualRectFlags = 0, EdgeInclusive = 1 };
 
+enum RareDataReason {
+  // LayoutObject
+  ReasonLOAll,
+  ReasonLOInFlowSelfPaintingLayer,
+  ReasonLOInFlowSelfPaintingLayerDiffPC,
+  ReasonLOPreviousLocation,
+  ReasonLOFloatLayerBug1,
+  ReasonLOFloatLayerBug2,
+  ReasonLOSVGForeignBug,
+  // LayoutInline
+  ReasonLIAll,
+  ReasonLICreatesLineBoxes,
+  // LayoutText
+  ReasonLTAll,
+  ReasonLTCanUseParentVisualRect,
+  ReasonLTZeroOrOneLineBox,
+  ReasonLTZeroOrOneLineBoxCanUse,
+  // LayoutBox
+  ReasonLBAll,
+  ReasonLBRareData,
+  ReasonLBInlineBoxWrapper,
+  ReasonLBSpannerPlaceholder,
+  ReasonLBOverrideSize,
+  ReasonLBPageOffset,
+  ReasonLBPaginationStrut,
+  ReasonLBPreviousSize,
+  ReasonLBPreviousLayoutOverflow,
+  ReasonLBPreviousContentBox,
+  ReasonLBPreviousContentBoxSizeIfDiff,
+  ReasonLBPositionedContainer,
+  ReasonLBPositionedDiffPC,
+  ReasonLBPercentHeightContainer,
+  ReasonLBContentBoxDiff,
+  ReasonLBLayoutOverflowDiff,
+  // LayoutBlock
+  ReasonLBLAll,
+  ReasonLBLPositionedDescendants,
+  ReasonLBLPercentHeightDescendants,
+  // LayoutBlockFlow
+  ReasonLBFAll,
+  ReasonLBFRareData,
+  ReasonLBFPaginationStrutFromChild,
+  ReasonLBFLineBreakToAvoidWidow,
+  ReasonLBFDiscardMargin,
+  ReasonLBFMargin,
+  ReasonLBFMultiColumnFlowThread,
+  // LayoutTableSection
+  ReasonLTSAll,
+  ReasonLTSComposited,
+  ReasonLTSNonComposited,
+  ReasonLTSCompositedWithContainerBackground,
+  // LayoutTableRow
+  ReasonLTRAll,
+  ReasonLTRComposited,
+  ReasonLTRNonComposited,
+  ReasonLTRCompositedWithContainerBackground,
+  // LayoutTableCell
+  ReasonLTCAll,
+  ReasonLTCInvisibleCollapsedBorders,
+  ReasonLTCCollapsedBorders,
+  ReasonLTCComposited,
+  ReasonLTCNonComposited,
+  ReasonLTCCompositedWithContainerBackground,
+  // LocationOffset
+  ReasonLocationOffsetObject,
+  ReasonLocationOffsetBox,
+  ReasonLocationOffsetText,
+  ReasonLocationOffsetInline,
+  ReasonLocationOffsetSVG,
+
+  MaxReason,
+  ReasonNone = -1,
+};
+
+static_assert(MaxReason == 58, "keep consistent");
+
+struct RareDataStat {
+ public:
+  RareDataStat() : m_reasons(0) {}
+#if 0
+    ~RareDataStat()
+    {
+        for (int reason = 0; reason < MaxReason; ++reason) {
+            if (m_reasons & ((uint64_t)1 << reason))
+                s_reasonCounts[reason]--;
+        }
+    }
+#endif
+
+  void addReason(RareDataReason reason) {
+    if (reason == ReasonNone)
+      return;
+    uint64_t reasonBit = (uint64_t)1 << reason;
+    if (!(m_reasons & reasonBit)) {
+      m_reasons |= reasonBit;
+      s_reasonCounts[reason]++;
+    }
+  }
+
+  uint64_t m_reasons;
+  static int s_reasonCounts[MaxReason];
+};
+
 enum CursorDirective { SetCursorBasedOnStyle, SetCursor, DoNotSetCursor };
 
 enum HitTestFilter { HitTestAll, HitTestSelf, HitTestDescendants };
@@ -2564,6 +2667,9 @@ class CORE_EXPORT LayoutObject : public ImageResourceObserver,
   // For SPv2 only. The ObjectPaintProperties structure holds references to the
   // property tree nodes that are created by the layout object for painting.
   std::unique_ptr<ObjectPaintProperties> m_paintProperties;
+
+ public:
+  mutable RareDataStat m_rareStat;
 };
 
 // FIXME: remove this once the layout object lifecycle ASSERTS are no longer