Issue #1355 - Make nsTableCellFrame::GetColIndex/GetRowIndex faster

We can devirtualize it, remove some branches.

9 files changed, 77 insertions, 123 deletions

diff --git a/layout/generic/nsSelection.cpp b/layout/generic/nsSelection.cpp
index ff75ab85dc..f2959dc9dd 100644
--- a/layout/generic/nsSelection.cpp
+++ b/layout/generic/nsSelection.cpp
@@ -2882,16 +2882,15 @@ nsFrameSelection::UnselectCells(nsIContent *aTableContent,
         nsTableCellFrame* cellFrame =
           tableFrame->GetCellFrameAt(curRowIndex, curColIndex);
 
-        int32_t origRowIndex, origColIndex;
-        cellFrame->GetRowIndex(origRowIndex);
-        cellFrame->GetColIndex(origColIndex);
+        uint32_t origRowIndex = cellFrame->RowIndex();
+        uint32_t origColIndex = cellFrame->ColIndex();
         uint32_t actualRowSpan =
           tableFrame->GetEffectiveRowSpanAt(origRowIndex, origColIndex);
         uint32_t actualColSpan =
           tableFrame->GetEffectiveColSpanAt(curRowIndex, curColIndex);
-        if (origRowIndex <= maxRowIndex && maxRowIndex >= 0 &&
+        if (origRowIndex <= static_cast<uint32_t>(maxRowIndex) && maxRowIndex >= 0 &&
             origRowIndex + actualRowSpan - 1 >= static_cast<uint32_t>(minRowIndex) &&
-            origColIndex <= maxColIndex && maxColIndex >= 0 &&
+            origColIndex <= static_cast<uint32_t>(maxColIndex) && maxColIndex >= 0 &&
             origColIndex + actualColSpan - 1 >= static_cast<uint32_t>(minColIndex)) {
 
           mDomSelections[index]->RemoveRange(range);
@@ -2925,33 +2924,32 @@ nsFrameSelection::AddCellsToSelection(nsIContent *aTableContent,
     return NS_ERROR_FAILURE;
 
   nsresult result = NS_OK;
-  int32_t row = aStartRowIndex;
+  uint32_t row = aStartRowIndex;
   while(true)
   {
-    int32_t col = aStartColumnIndex;
+    uint32_t col = aStartColumnIndex;
     while(true)
     {
       nsTableCellFrame* cellFrame = tableFrame->GetCellFrameAt(row, col);
 
       // Skip cells that are spanned from previous locations or are already selected
       if (cellFrame) {
-        int32_t origRow, origCol;
-        cellFrame->GetRowIndex(origRow);
-        cellFrame->GetColIndex(origCol);
+        uint32_t origRow = cellFrame->RowIndex();
+        uint32_t origCol = cellFrame->ColIndex();
         if (origRow == row && origCol == col && !cellFrame->IsSelected()) {
           result = SelectCellElement(cellFrame->GetContent());
           if (NS_FAILED(result)) return result;
         }
       }
       // Done when we reach end column
-      if (col == aEndColumnIndex) break;
+      if (col == static_cast<uint32_t>(aEndColumnIndex)) break;
 
       if (aStartColumnIndex < aEndColumnIndex)
         col ++;
       else
         col--;
     }
-    if (row == aEndRowIndex) break;
+    if (row == static_cast<uint32_t>(aEndRowIndex)) break;
 
     if (aStartRowIndex < aEndRowIndex)
       row++;
diff --git a/layout/mathml/nsMathMLmtableFrame.cpp b/layout/mathml/nsMathMLmtableFrame.cpp
index 1ff8a28ef0..4bd7d43951 100644
--- a/layout/mathml/nsMathMLmtableFrame.cpp
+++ b/layout/mathml/nsMathMLmtableFrame.cpp
@@ -183,10 +183,8 @@ static void
 ApplyBorderToStyle(const nsMathMLmtdFrame* aFrame,
                    nsStyleBorder& aStyleBorder)
 {
-  int32_t rowIndex;
-  int32_t columnIndex;
-  aFrame->GetRowIndex(rowIndex);
-  aFrame->GetColIndex(columnIndex);
+  uint32_t rowIndex = aFrame->RowIndex();
+  uint32_t columnIndex = aFrame->ColIndex();
 
   nscoord borderWidth =
     aFrame->PresContext()->GetBorderWidthTable()[NS_STYLE_BORDER_WIDTH_THIN];
@@ -201,7 +199,7 @@ ApplyBorderToStyle(const nsMathMLmtdFrame* aFrame,
   if (rowIndex > 0 && rowLinesList) {
     // If the row number is greater than the number of provided rowline
     // values, we simply repeat the last value.
-    int32_t listLength = rowLinesList->Length();
+    uint32_t listLength = rowLinesList->Length();
     if (rowIndex < listLength) {
       aStyleBorder.SetBorderStyle(NS_SIDE_TOP,
                     rowLinesList->ElementAt(rowIndex - 1));
@@ -216,7 +214,7 @@ ApplyBorderToStyle(const nsMathMLmtdFrame* aFrame,
   if (columnIndex > 0 && columnLinesList) {
     // If the column number is greater than the number of provided columline
     // values, we simply repeat the last value.
-    int32_t listLength = columnLinesList->Length();
+    uint32_t listLength = columnLinesList->Length();
     if (columnIndex < listLength) {
       aStyleBorder.SetBorderStyle(NS_SIDE_LEFT,
                     columnLinesList->ElementAt(columnIndex - 1));
@@ -1202,12 +1200,11 @@ nsMathMLmtdFrame::GetVerticalAlign() const
   nsTArray<int8_t>* alignmentList = FindCellProperty(this, RowAlignProperty());
 
   if (alignmentList) {
-    int32_t rowIndex;
-    GetRowIndex(rowIndex);
+    uint32_t rowIndex = RowIndex();
 
     // If the row number is greater than the number of provided rowalign values,
     // we simply repeat the last value.
-    if (rowIndex < (int32_t)alignmentList->Length())
+    if (rowIndex < alignmentList->Length())
       alignment = alignmentList->ElementAt(rowIndex);
     else
       alignment = alignmentList->ElementAt(alignmentList->Length() - 1);
@@ -1294,12 +1291,11 @@ nsStyleText* nsMathMLmtdInnerFrame::StyleTextForLineLayout()
 
   if (alignmentList) {
     nsMathMLmtdFrame* cellFrame = (nsMathMLmtdFrame*)GetParent();
-    int32_t columnIndex;
-    cellFrame->GetColIndex(columnIndex);
+    uint32_t columnIndex = cellFrame->ColIndex();
 
     // If the column number is greater than the number of provided columalign
     // values, we simply repeat the last value.
-    if (columnIndex < (int32_t)alignmentList->Length())
+    if (columnIndex < alignmentList->Length())
       alignment = alignmentList->ElementAt(columnIndex);
     else
       alignment = alignmentList->ElementAt(alignmentList->Length() - 1);
diff --git a/layout/tables/nsCellMap.cpp b/layout/tables/nsCellMap.cpp
index bdd12cf70b..4852a4bdde 100644
--- a/layout/tables/nsCellMap.cpp
+++ b/layout/tables/nsCellMap.cpp
@@ -2431,9 +2431,8 @@ void nsCellMap::Dump(bool aIsBorderCollapse) const
       if (cd) {
         if (cd->IsOrig()) {
           nsTableCellFrame* cellFrame = cd->GetCellFrame();
-          int32_t cellFrameColIndex;
-          cellFrame->GetColIndex(cellFrameColIndex);
-          printf("C%d,%d=%p(%d)  ", rIndex, colIndex, (void*)cellFrame,
+          uint32_t cellFrameColIndex = cellFrame->ColIndex();
+          printf("C%d,%d=%p(%u)  ", rIndex, colIndex, (void*)cellFrame,
                  cellFrameColIndex);
           cellCount++;
         }
@@ -2520,8 +2519,7 @@ nsCellMap::GetCellInfoAt(const nsTableCellMap& aMap,
       cellFrame = GetCellFrame(aRowX, aColX, *data, true);
     }
     if (cellFrame && aColSpan) {
-      int32_t initialColIndex;
-      cellFrame->GetColIndex(initialColIndex);
+      uint32_t initialColIndex = cellFrame->ColIndex();
       *aColSpan = GetEffectiveColSpan(aMap, aRowX, initialColIndex);
     }
   }
diff --git a/layout/tables/nsITableCellLayout.h b/layout/tables/nsITableCellLayout.h
index a366b150eb..fdf693b060 100644
--- a/layout/tables/nsITableCellLayout.h
+++ b/layout/tables/nsITableCellLayout.h
@@ -14,6 +14,7 @@
 /**
  * nsITableCellLayout
  * interface for layout objects that act like table cells.
+ * XXX: This interface should really go away...
  *
  * @author  sclark
  */
@@ -26,11 +27,6 @@ public:
   /** return the mapped cell's row and column indexes (starting at 0 for each) */
   NS_IMETHOD GetCellIndexes(int32_t &aRowIndex, int32_t &aColIndex)=0;
 
-  /** return the mapped cell's row index (starting at 0 for the first row) */
-  virtual nsresult GetRowIndex(int32_t &aRowIndex) const = 0;
-  
-  /** return the mapped cell's column index (starting at 0 for the first column) */
-  virtual nsresult GetColIndex(int32_t &aColIndex) const = 0;
 };
 
 #endif
diff --git a/layout/tables/nsTableCellFrame.cpp b/layout/tables/nsTableCellFrame.cpp
index cd846efa24..8b811df1e3 100644
--- a/layout/tables/nsTableCellFrame.cpp
+++ b/layout/tables/nsTableCellFrame.cpp
@@ -74,8 +74,7 @@ nsTableCellFrame::Init(nsIContent*       aContent,
   if (aPrevInFlow) {
     // Set the column index
     nsTableCellFrame* cellFrame = (nsTableCellFrame*)aPrevInFlow;
-    int32_t           colIndex;
-    cellFrame->GetColIndex(colIndex);
+    uint32_t colIndex = cellFrame->ColIndex();
     SetColIndex(colIndex);
   }
 }
@@ -169,34 +168,6 @@ nsTableCellFrame::NeedsToObserve(const ReflowInput& aReflowInput)
 }
 
 nsresult
-nsTableCellFrame::GetRowIndex(int32_t &aRowIndex) const
-{
-  nsresult result;
-  nsTableRowFrame* row = static_cast<nsTableRowFrame*>(GetParent());
-  if (row) {
-    aRowIndex = row->GetRowIndex();
-    result = NS_OK;
-  }
-  else {
-    aRowIndex = 0;
-    result = NS_ERROR_NOT_INITIALIZED;
-  }
-  return result;
-}
-
-nsresult
-nsTableCellFrame::GetColIndex(int32_t &aColIndex) const
-{
-  if (GetPrevInFlow()) {
-    return static_cast<nsTableCellFrame*>(FirstInFlow())->GetColIndex(aColIndex);
-  }
-  else {
-    aColIndex = mColIndex;
-    return  NS_OK;
-  }
-}
-
-nsresult
 nsTableCellFrame::AttributeChanged(int32_t         aNameSpaceID,
                                    nsIAtom*        aAttribute,
                                    int32_t         aModType)
@@ -224,13 +195,13 @@ nsTableCellFrame::DidSetStyleContext(nsStyleContext* aOldStyleContext)
   nsTableFrame* tableFrame = GetTableFrame();
   if (tableFrame->IsBorderCollapse() &&
       tableFrame->BCRecalcNeeded(aOldStyleContext, StyleContext())) {
-    int32_t colIndex, rowIndex;
-    GetColIndex(colIndex);
-    GetRowIndex(rowIndex);
+    uint32_t colIndex = ColIndex();
+    uint32_t rowIndex = RowIndex();
     // row span needs to be clamped as we do not create rows in the cellmap
     // which do not have cells originating in them
     TableArea damageArea(colIndex, rowIndex, GetColSpan(),
-      std::min(GetRowSpan(), tableFrame->GetRowCount() - rowIndex));
+      std::min(static_cast<uint32_t>(GetRowSpan()),
+               tableFrame->GetRowCount() - rowIndex));
     tableFrame->AddBCDamageArea(damageArea);
   }
 }
@@ -820,14 +791,13 @@ CalcUnpaginatedBSize(nsTableCellFrame& aCellFrame,
   nsTableRowGroupFrame* firstRGInFlow =
     static_cast<nsTableRowGroupFrame*>(row->GetParent());
 
-  int32_t rowIndex;
-  firstCellInFlow->GetRowIndex(rowIndex);
+  uint32_t rowIndex = firstCellInFlow->RowIndex();
   int32_t rowSpan = aTableFrame.GetEffectiveRowSpan(*firstCellInFlow);
 
   nscoord computedBSize = firstTableInFlow->GetRowSpacing(rowIndex,
                                                           rowIndex + rowSpan - 1);
   computedBSize -= aBlockDirBorderPadding;
-  int32_t rowX;
+  uint32_t rowX;
   for (row = firstRGInFlow->GetFirstRow(), rowX = 0; row; row = row->GetNextRow(), rowX++) {
     if (rowX > rowIndex + rowSpan - 1) {
       break;
@@ -1042,12 +1012,7 @@ nsTableCellFrame::AccessibleType()
 NS_IMETHODIMP
 nsTableCellFrame::GetCellIndexes(int32_t &aRowIndex, int32_t &aColIndex)
 {
-  nsresult res = GetRowIndex(aRowIndex);
-  if (NS_FAILED(res))
-  {
-    aColIndex = 0;
-    return res;
-  }
+  aRowIndex = RowIndex();
   aColIndex = mColIndex;
   return  NS_OK;
 }
diff --git a/layout/tables/nsTableCellFrame.h b/layout/tables/nsTableCellFrame.h
index ea527b3c59..f626a45b0c 100644
--- a/layout/tables/nsTableCellFrame.h
+++ b/layout/tables/nsTableCellFrame.h
@@ -183,7 +183,10 @@ public:
   NS_IMETHOD GetCellIndexes(int32_t &aRowIndex, int32_t &aColIndex) override;
 
   /** return the mapped cell's row index (starting at 0 for the first row) */
-  virtual nsresult GetRowIndex(int32_t &aRowIndex) const override;
+  uint32_t RowIndex() const
+  {
+    return static_cast<nsTableRowFrame*>(GetParent())->GetRowIndex();
+  }
 
   /**
    * return the cell's specified col span. this is what was specified in the
@@ -194,7 +197,16 @@ public:
   int32_t GetColSpan();
 
   /** return the cell's column index (starting at 0 for the first column) */
-  virtual nsresult GetColIndex(int32_t &aColIndex) const override;
+  uint32_t ColIndex() const
+  {
+    // NOTE: We copy this from previous continuations, and we don't ever have
+    // dynamic updates when tables split, so our mColIndex always matches our
+    // first continuation's.
+    MOZ_ASSERT(static_cast<nsTableCellFrame*>(FirstContinuation())->mColIndex ==
+               mColIndex,
+               "mColIndex out of sync with first continuation");
+    return mColIndex;
+  }
   void SetColIndex(int32_t aColIndex);
 
   /** return the available isize given to this frame during its last reflow */
@@ -246,9 +258,9 @@ public:
   virtual void InvalidateFrame(uint32_t aDisplayItemKey = 0) override;
   virtual void InvalidateFrameWithRect(const nsRect& aRect, uint32_t aDisplayItemKey = 0) override;
   virtual void InvalidateFrameForRemoval() override { InvalidateFrameSubtree(); }
-  
+
   bool ShouldPaintBordersAndBackgrounds() const;
-  
+
   bool ShouldPaintBackground(nsDisplayListBuilder* aBuilder);
 
 protected:
diff --git a/layout/tables/nsTableFrame.cpp b/layout/tables/nsTableFrame.cpp
index 868f83bda2..4257c9c579 100644
--- a/layout/tables/nsTableFrame.cpp
+++ b/layout/tables/nsTableFrame.cpp
@@ -368,9 +368,8 @@ nsTableFrame::AttributeChangedFor(nsIFrame*       aFrame,
       nsTableCellMap* cellMap = GetCellMap();
       if (cellMap) {
         // for now just remove the cell from the map and reinsert it
-        int32_t rowIndex, colIndex;
-        cellFrame->GetRowIndex(rowIndex);
-        cellFrame->GetColIndex(colIndex);
+        uint32_t rowIndex = cellFrame->RowIndex();
+        uint32_t colIndex = cellFrame->ColIndex();
         RemoveCell(cellFrame, rowIndex);
         AutoTArray<nsTableCellFrame*, 1> cells;
         cells.AppendElement(cellFrame);
@@ -447,9 +446,7 @@ nsTableFrame::GetEffectiveRowSpan(int32_t                 aRowIndex,
   nsTableCellMap* cellMap = GetCellMap();
   NS_PRECONDITION (nullptr != cellMap, "bad call, cellMap not yet allocated.");
 
-  int32_t colIndex;
-  aCell.GetColIndex(colIndex);
-  return cellMap->GetEffectiveRowSpan(aRowIndex, colIndex);
+  return cellMap->GetEffectiveRowSpan(aRowIndex, aCell.ColIndex());
 }
 
 int32_t
@@ -458,9 +455,8 @@ nsTableFrame::GetEffectiveRowSpan(const nsTableCellFrame& aCell,
 {
   nsTableCellMap* tableCellMap = GetCellMap(); if (!tableCellMap) ABORT1(1);
 
-  int32_t colIndex, rowIndex;
-  aCell.GetColIndex(colIndex);
-  aCell.GetRowIndex(rowIndex);
+  uint32_t colIndex = aCell.ColIndex();
+  uint32_t rowIndex = aCell.RowIndex();
 
   if (aCellMap)
     return aCellMap->GetRowSpan(rowIndex, colIndex, true);
@@ -474,9 +470,8 @@ nsTableFrame::GetEffectiveColSpan(const nsTableCellFrame& aCell,
 {
   nsTableCellMap* tableCellMap = GetCellMap(); if (!tableCellMap) ABORT1(1);
 
-  int32_t colIndex, rowIndex;
-  aCell.GetColIndex(colIndex);
-  aCell.GetRowIndex(rowIndex);
+  uint32_t colIndex = aCell.ColIndex();
+  uint32_t rowIndex = aCell.RowIndex();
 
   if (aCellMap)
     return aCellMap->GetEffectiveColSpan(*tableCellMap, rowIndex, colIndex);
@@ -1221,9 +1216,9 @@ PaintRowGroupBackground(nsTableRowGroupFrame* aRowGroup,
                         const nsRect& aDirtyRect)
 {
   for (nsTableRowFrame* row = aRowGroup->GetFirstRow(); row; row = row->GetNextRow()) {
-     if (!aDirtyRect.Intersects(nsRect(row->GetNormalPosition(), row->GetSize()))) {
-       continue;
-     }
+    if (!aDirtyRect.Intersects(nsRect(row->GetNormalPosition(), row->GetSize()))) {
+      continue;
+    }
     PaintRowBackground(row, aFrame, aBuilder, aLists, aDirtyRect, row->GetNormalPosition());
   }
 }
@@ -1234,7 +1229,7 @@ PaintRowGroupBackgroundByColIdx(nsTableRowGroupFrame* aRowGroup,
                                 nsDisplayListBuilder* aBuilder,
                                 const nsDisplayListSet& aLists,
                                 const nsRect& aDirtyRect,
-                                const nsTArray<int32_t>& aColIdx,
+                                const nsTArray<uint32_t>& aColIdx,
                                 const nsPoint& aOffset)
 {
   MOZ_DIAGNOSTIC_ASSERT(!aColIdx.IsEmpty(),
@@ -1246,8 +1241,7 @@ PaintRowGroupBackgroundByColIdx(nsTableRowGroupFrame* aRowGroup,
     }
     for (nsTableCellFrame* cell = row->GetFirstCell(); cell; cell = cell->GetNextCell()) {
 
-      int32_t curColIdx;
-      cell->GetColIndex(curColIdx);
+      uint32_t curColIdx = cell->ColIndex();
       if (!aColIdx.Contains(curColIdx)) {
         if (curColIdx > aColIdx.LastElement()) {
           // We can just stop looking at this row.
@@ -1318,10 +1312,10 @@ nsTableFrame::DisplayGenericTablePart(nsDisplayListBuilder* aBuilder,
     // Compute background rect by iterating all cell frame.
     nsTableColGroupFrame* colGroup = static_cast<nsTableColGroupFrame*>(aFrame);
     // Collecting column index.
-    AutoTArray<int32_t, 1> colIdx;
+    AutoTArray<uint32_t, 1> colIdx;
     for (nsTableColFrame* col = colGroup->GetFirstColumn(); col; col = col->GetNextCol()) {
       MOZ_ASSERT(colIdx.IsEmpty() ||
-                 col->GetColIndex() > colIdx.LastElement());
+                 static_cast<uint32_t>(col->GetColIndex()) > colIdx.LastElement());
       colIdx.AppendElement(col->GetColIndex());
     }
 
@@ -1341,7 +1335,7 @@ nsTableFrame::DisplayGenericTablePart(nsDisplayListBuilder* aBuilder,
   } else if (aFrame->GetType() == nsGkAtoms::tableColFrame) {
     // Compute background rect by iterating all cell frame.
     nsTableColFrame* col = static_cast<nsTableColFrame*>(aFrame);
-    AutoTArray<int32_t, 1> colIdx;
+    AutoTArray<uint32_t, 1> colIdx;
     colIdx.AppendElement(col->GetColIndex());
 
     nsTableFrame* table = col->GetTableFrame();
@@ -3973,9 +3967,8 @@ nsTableFrame::DumpRowGroup(nsIFrame* aKidFrame)
       for (nsIFrame* childFrame : cFrame->PrincipalChildList()) {
         nsTableCellFrame *cellFrame = do_QueryFrame(childFrame);
         if (cellFrame) {
-          int32_t colIndex;
-          cellFrame->GetColIndex(colIndex);
-          printf("cell(%d)=%p ", colIndex, static_cast<void*>(childFrame));
+          uint32_t colIndex = cellFrame->ColIndex();
+          printf("cell(%u)=%p ", colIndex, static_cast<void*>(childFrame));
         }
       }
       printf("\n");
diff --git a/layout/tables/nsTableRowFrame.cpp b/layout/tables/nsTableRowFrame.cpp
index 8bbaf50f5f..02b85a141f 100644
--- a/layout/tables/nsTableRowFrame.cpp
+++ b/layout/tables/nsTableRowFrame.cpp
@@ -235,7 +235,7 @@ nsTableRowFrame::InsertFrames(ChildListID  aListID,
   // insert the cells into the cell map
   int32_t colIndex = -1;
   if (prevCellFrame) {
-    prevCellFrame->GetColIndex(colIndex);
+    colIndex = prevCellFrame->ColIndex();
   }
   tableFrame->InsertCells(cellChildren, GetRowIndex(), colIndex);
 
@@ -647,8 +647,7 @@ CalcAvailISize(nsTableFrame&     aTableFrame,
                nsTableCellFrame& aCellFrame)
 {
   nscoord cellAvailISize = 0;
-  int32_t colIndex;
-  aCellFrame.GetColIndex(colIndex);
+  uint32_t colIndex = aCellFrame.ColIndex();
   int32_t colspan = aTableFrame.GetEffectiveColSpan(aCellFrame);
   NS_ASSERTION(colspan > 0, "effective colspan should be positive");
   nsTableFrame* fifTable =
@@ -787,12 +786,12 @@ nsTableRowFrame::ReflowChildren(nsPresContext*           aPresContext,
       }
     }
 
-    int32_t cellColIndex;
-    cellFrame->GetColIndex(cellColIndex);
+    uint32_t cellColIndex = cellFrame->ColIndex();
     cellColSpan = aTableFrame.GetEffectiveColSpan(*cellFrame);
 
     // If the adjacent cell is in a prior row (because of a rowspan) add in the space
-    if (prevColIndex != (cellColIndex - 1)) {
+    // NOTE: prevColIndex can be -1 here.
+    if (prevColIndex != (static_cast<int32_t>(cellColIndex) - 1)) {
       iCoord += GetSpaceBetween(prevColIndex, cellColIndex, cellColSpan, aTableFrame,
                                 false);
     }
@@ -1160,8 +1159,7 @@ nsTableRowFrame::CollapseRowIfNecessary(nscoord aRowOffset,
     shift = rowRect.BSize(wm);
     nsTableCellFrame* cellFrame = GetFirstCell();
     if (cellFrame) {
-      int32_t rowIndex;
-      cellFrame->GetRowIndex(rowIndex);
+      uint32_t rowIndex = cellFrame->RowIndex();
       shift += tableFrame->GetRowSpacing(rowIndex);
       while (cellFrame) {
         LogicalRect cRect = cellFrame->GetLogicalRect(wm, containerSize);
@@ -1192,13 +1190,13 @@ nsTableRowFrame::CollapseRowIfNecessary(nscoord aRowOffset,
     for (nsIFrame* kidFrame : mFrames) {
       nsTableCellFrame *cellFrame = do_QueryFrame(kidFrame);
       if (cellFrame) {
-        int32_t cellColIndex;
-        cellFrame->GetColIndex(cellColIndex);
+        uint32_t cellColIndex = cellFrame->ColIndex();
         int32_t cellColSpan = tableFrame->GetEffectiveColSpan(*cellFrame);
 
         // If the adjacent cell is in a prior row (because of a rowspan) add in
         // the space
-        if (prevColIndex != (cellColIndex - 1)) {
+        // NOTE: prevColIndex can be -1 here.
+        if (prevColIndex != (static_cast<int32_t>(cellColIndex) - 1)) {
           iPos += GetSpaceBetween(prevColIndex, cellColIndex, cellColSpan,
                                   *tableFrame, true);
         }
@@ -1311,9 +1309,9 @@ nsTableRowFrame::InsertCellFrame(nsTableCellFrame* aFrame,
   for (nsIFrame* child : mFrames) {
     nsTableCellFrame *cellFrame = do_QueryFrame(child);
     if (cellFrame) {
-      int32_t colIndex;
-      cellFrame->GetColIndex(colIndex);
-      if (colIndex < aColIndex) {
+      uint32_t colIndex = cellFrame->ColIndex();
+      // Can aColIndex be -1 here?  Let's assume it can for now.
+      if (static_cast<int32_t>(colIndex) < aColIndex) {
         priorCell = cellFrame;
       }
       else break;
diff --git a/layout/tables/nsTableRowGroupFrame.cpp b/layout/tables/nsTableRowGroupFrame.cpp
index f613c8b798..37f577f5ca 100644
--- a/layout/tables/nsTableRowGroupFrame.cpp
+++ b/layout/tables/nsTableRowGroupFrame.cpp
@@ -137,8 +137,7 @@ nsTableRowGroupFrame::InitRepeatedFrame(nsTableRowGroupFrame* aHeaderFooterFrame
     while (copyCellFrame && originalCellFrame) {
       NS_ASSERTION(originalCellFrame->GetContent() == copyCellFrame->GetContent(),
                    "cell frames have different content");
-      int32_t colIndex;
-      originalCellFrame->GetColIndex(colIndex);
+      uint32_t colIndex = originalCellFrame->ColIndex();
       copyCellFrame->SetColIndex(colIndex);
 
       // Move to the next cell frame
@@ -998,8 +997,7 @@ nsTableRowGroupFrame::SplitSpanningCells(nsPresContext&           aPresContext,
               nsTableCellFrame* contCell = static_cast<nsTableCellFrame*>(
                 aPresContext.PresShell()->FrameConstructor()->
                   CreateContinuingFrame(&aPresContext, cell, &aLastRow));
-              int32_t colIndex;
-              cell->GetColIndex(colIndex);
+              uint32_t colIndex = cell->ColIndex();
               aContRow->InsertCellFrame(contCell, colIndex);
             }
           }