r=troy; Reworked nsLineBox api to allow for reduced storage overhead; fixed bug 16252 while keeping bug 12709 fixed

layout/generic/nsLineBox.cpp

@@ -30,25 +30,37 @@
 MOZ_DECL_CTOR_COUNTER(nsLineBox);
 
 nsLineBox::nsLineBox(nsIFrame* aFrame, PRInt32 aCount, PRBool aIsBlock)
+  : mFirstChild(aFrame),
+    mNext(nsnull),
+    mBounds(0, 0, 0, 0),
+    mMaxElementWidth(0),
+    mData(nsnull)
 {
   MOZ_COUNT_CTOR(nsLineBox);
-  mFirstChild = aFrame;
+
-  mChildCount = aCount;
   mAllFlags = 0;
-  MarkDirty();
+#if NS_STYLE_CLEAR_NONE > 0
-  SetIsBlock(aIsBlock);
-  mNext = nsnull;
-  mBounds.SetRect(0,0,0,0);
-  mCombinedArea.SetRect(0,0,0,0);
-//XXX  mCarriedOutTopMargin = 0;
-  mCarriedOutBottomMargin = 0;
   mFlags.mBreakType = NS_STYLE_CLEAR_NONE;
-  mMaxElementWidth = 0;
+#endif
+  SetChildCount(aCount);
+  MarkDirty();
+  mFlags.mBlock = aIsBlock;
 }
 
 nsLineBox::~nsLineBox()
 {
   MOZ_COUNT_DTOR(nsLineBox);
+
+  if (IsBlock()) {
+    if (mBlockData) {
+      delete mBlockData;
+    }
+  }
+  else {
+    if (mInlineData) {
+      delete mInlineData;
+    }
+  }
 }
 
 static void
@@ -82,9 +94,11 @@ ListFloaters(FILE* out, PRInt32 aIndent, const nsFloaterCacheList& aFloaters)
 char*
 nsLineBox::StateToString(char* aBuf, PRInt32 aBufSize) const
 {
-  PR_snprintf(aBuf, aBufSize, "%s,%s[0x%x]",
+  PR_snprintf(aBuf, aBufSize, "%s,%s,%s,%s[0x%x]",
-              IsDirty() ? "dirty" : "clean",
               IsBlock() ? "block" : "inline",
+              IsDirty() ? "dirty" : "",
+              IsImpactedByFloater() ? "impacted" : "",
+              IsTrimmed() ? "trimmed" : "",
               mAllFlags);
   return aBuf;
 }
@@ -97,30 +111,33 @@ nsLineBox::List(FILE* out, PRInt32 aIndent) const
   for (i = aIndent; --i >= 0; ) fputs("  ", out);
   char cbuf[100];
   fprintf(out, "line %p: count=%d state=%s ",
-          this, ChildCount(), StateToString(cbuf, sizeof(cbuf)));
+          this, GetChildCount(), StateToString(cbuf, sizeof(cbuf)));
-  if (0 != mCarriedOutBottomMargin) {
+  if (0 != GetCarriedOutBottomMargin()) {
-    fprintf(out, "bm=%d ", mCarriedOutBottomMargin);
+    fprintf(out, "bm=%d ", GetCarriedOutBottomMargin());
   }
   if (0 != mMaxElementWidth) {
     fprintf(out, "mew=%d ", mMaxElementWidth);
   }
-  fprintf(out, "{%d,%d,%d,%d} ca={%d,%d,%d,%d}",
+  fprintf(out, "{%d,%d,%d,%d} ",
-          mBounds.x, mBounds.y, mBounds.width, mBounds.height,
+          mBounds.x, mBounds.y, mBounds.width, mBounds.height);
-          mCombinedArea.x, mCombinedArea.y,
+  if (mData) {
-          mCombinedArea.width, mCombinedArea.height);
+    fprintf(out, "ca={%d,%d,%d,%d} ",
-  fprintf(out, " <\n");
+            mData->mCombinedArea.x, mData->mCombinedArea.y,
+            mData->mCombinedArea.width, mData->mCombinedArea.height);
+  }
+  fprintf(out, "<\n");
 
   nsIFrame* frame = mFirstChild;
-  PRInt32 n = ChildCount();
+  PRInt32 n = GetChildCount();
   while (--n >= 0) {
     frame->List(out, aIndent + 1);
     frame->GetNextSibling(&frame);
   }
 
   for (i = aIndent; --i >= 0; ) fputs("  ", out);
-  if (mFloaters.NotEmpty()) {
+  if (HasFloaters()) {
     fputs("> floaters <\n", out);
-    ListFloaters(out, aIndent + 1, mFloaters);
+    ListFloaters(out, aIndent + 1, mInlineData->mFloaters);
     for (i = aIndent; --i >= 0; ) fputs("  ", out);
   }
   fputs(">\n", out);
@@ -130,7 +147,7 @@ nsIFrame*
 nsLineBox::LastChild() const
 {
   nsIFrame* frame = mFirstChild;
-  PRInt32 n = ChildCount() - 1;
+  PRInt32 n = GetChildCount() - 1;
   while (--n >= 0) {
     frame->GetNextSibling(&frame);
   }
@@ -147,7 +164,7 @@ nsLineBox::IsLastChild(nsIFrame* aFrame) const
 PRInt32
 nsLineBox::IndexOf(nsIFrame* aFrame) const
 {
-  PRInt32 i, n = ChildCount();
+  PRInt32 i, n = GetChildCount();
   nsIFrame* frame = mFirstChild;
   for (i = 0; i < n; i++) {
     if (frame == aFrame) {
@@ -208,39 +225,172 @@ nsLineBox::FindLineContaining(nsLineBox* aLine, nsIFrame* aFrame,
   return nsnull;
 }
 
-#ifdef NS_DEBUG
+nscoord
-PRBool
+nsLineBox::GetCarriedOutBottomMargin() const
-nsLineBox::CheckIsBlock() const
 {
-  PRBool isBlock = nsLineLayout::TreatFrameAsBlock(mFirstChild);
+  return (IsBlock() && mBlockData) ? mBlockData->mCarriedOutBottomMargin : 0;
-  return isBlock == IsBlock();
+}
+
+void
+nsLineBox::SetCarriedOutBottomMargin(nscoord aValue)
+{
+  if (IsBlock()) {
+    if (aValue) {
+      if (!mBlockData) {
+        mBlockData = new ExtraBlockData(mBounds);
+      }
+      if (mBlockData) {
+        mBlockData->mCarriedOutBottomMargin = aValue;
+      }
+    }
+    else if (mBlockData) {
+      mBlockData->mCarriedOutBottomMargin = aValue;
+      MaybeFreeData();
+    }
+  }
+}
+
+void
+nsLineBox::MaybeFreeData()
+{
+  if (mData && (mData->mCombinedArea == mBounds)) {
+    if (IsInline()) {
+      if (mInlineData->mFloaters.IsEmpty()) {
+        delete mInlineData;
+        mInlineData = nsnull;
+      }
+    }
+    else if (0 == mBlockData->mCarriedOutBottomMargin) {
+      delete mBlockData;
+      mBlockData = nsnull;
+    }
+  }
+}
+
+// XXX get rid of this???
+nsFloaterCache*
+nsLineBox::GetFirstFloater()
+{
+  if (NS_WARN_IF_FALSE(IsInline(), "block line can't have floaters")) {
+    return nsnull;
+  }
+  return mInlineData ? mInlineData->mFloaters.Head() : nsnull;
+}
+
+// XXX this might be too eager to free memory
+void
+nsLineBox::FreeFloaters(nsFloaterCacheFreeList& aFreeList)
+{
+  NS_WARN_IF_FALSE(IsInline(), "block line can't have floaters");
+  if (IsInline()) {
+    if (mInlineData) {
+      aFreeList.Append(mInlineData->mFloaters);
+      MaybeFreeData();
+    }
+  }
+}
+
+void
+nsLineBox::AppendFloaters(nsFloaterCacheFreeList& aFreeList)
+{
+  NS_WARN_IF_FALSE(IsInline(), "block line can't have floaters");
+  if (IsInline()) {
+    if (aFreeList.NotEmpty()) {
+      if (!mInlineData) {
+        mInlineData = new ExtraInlineData(mBounds);
+      }
+      if (mInlineData) {
+        mInlineData->mFloaters.Append(aFreeList);
+      }
+    }
+  }
+}
+
+PRBool
+nsLineBox::RemoveFloater(nsIFrame* aFrame)
+{
+  NS_WARN_IF_FALSE(IsInline(), "block line can't have floaters");
+  if (IsInline() && mInlineData) {
+    nsFloaterCache* fc = mInlineData->mFloaters.Find(aFrame);
+    if (fc) {
+      // Note: the placeholder is part of the line's child list
+      // and will be removed later.
+      fc->mPlaceholder->SetOutOfFlowFrame(nsnull);
+      mInlineData->mFloaters.Remove(fc);
+      MaybeFreeData();
+    }
+  }
+  return PR_FALSE;
+}
+
+void
+nsLineBox::SetCombinedArea(const nsRect& aCombinedArea)
+{
+  if (aCombinedArea != mBounds) {
+    if (mData) {
+      mData->mCombinedArea = aCombinedArea;
+    }
+    else {
+      if (IsInline()) {
+        mInlineData = new ExtraInlineData(aCombinedArea);
+      }
+      else {
+        mBlockData = new ExtraBlockData(aCombinedArea);
+      }
+    }
+  }
+  else {
+    if (mData) {
+      // Store away new value so that MaybeFreeData compares against
+      // the right value.
+      mData->mCombinedArea = aCombinedArea;
+    }
+    MaybeFreeData();
+  }
+}
+
+void
+nsLineBox::GetCombinedArea(nsRect* aResult)
+{
+  if (aResult) {
+    *aResult = mData ? mData->mCombinedArea : mBounds;
+  }
 }
-#endif
 
 #ifdef DEBUG
-PRBool
+nsIAtom*
 nsLineBox::SizeOf(nsISizeOfHandler* aHandler, PRUint32* aResult) const
 {
   NS_PRECONDITION(aResult, "null OUT parameter pointer");
   *aResult = sizeof(*this);
 
-  PRBool big = PR_TRUE;
+  nsIAtom* atom;
-  if ((IsBlock() || mFloaters.IsEmpty()) &&
+  if (IsBlock()) {
-      (mBounds == mCombinedArea)) {
+    atom = nsLayoutAtoms::lineBoxBlockSmall;
-    big = PR_FALSE;
+    if (mBlockData) {
+      atom = nsLayoutAtoms::lineBoxBlockBig;
+      *aResult += sizeof(*mBlockData);
     }
+  }
+  else {
+    atom = nsLayoutAtoms::lineBoxSmall;
+    if (mInlineData) {
+      atom = nsLayoutAtoms::lineBoxBig;
+      *aResult += sizeof(*mInlineData);
 
       // Add in the size needed for floaters associated with this line
-  if (mFloaters.NotEmpty()) {
+      if (HasFloaters()) {
         PRUint32  floatersSize;
+        mInlineData->mFloaters.SizeOf(aHandler, &floatersSize);
 
-    mFloaters.SizeOf(aHandler, &floatersSize);
         // Base size of embedded object was included in sizeof(*this) above
-    floatersSize -= sizeof(mFloaters);
+        floatersSize -= sizeof(mInlineData->mFloaters);
         aHandler->AddSize(nsLayoutAtoms::lineBoxFloaters, floatersSize);
       }
+    }
+  }
 
-  return big;
+  return atom;
 }
 #endif
 
@@ -346,7 +496,7 @@ nsLineIterator::GetLine(PRInt32 aLineNumber,
   }
   nsLineBox* line = mLines[aLineNumber];
   *aFirstFrameOnLine = line->mFirstChild;
-  *aNumFramesOnLine = line->mChildCount;
+  *aNumFramesOnLine = line->GetChildCount();
   aLineBounds = line->mBounds;
 
   PRUint32 flags = 0;
@@ -462,7 +612,7 @@ nsLineIterator::FindFrameAt(PRInt32 aLineNumber,
   *aXIsAfterLastFrame = PR_FALSE;
   nsRect r1, r2;
   nsIFrame* frame = line->mFirstChild;
-  PRInt32 n = line->mChildCount;
+  PRInt32 n = line->GetChildCount();
   if (mRightToLeft) {
     while (--n >= 0) {
       nsIFrame* nextFrame;
@@ -528,6 +678,7 @@ nsFloaterCacheList::~nsFloaterCacheList()
     delete floater;
     floater = next;
   }
+  mHead = nsnull;
 }
 
 nsFloaterCache*

layout/generic/nsLineBox.h

@@ -26,9 +26,6 @@
 
 class nsISpaceManager;
 class nsLineBox;
-
-//----------------------------------------------------------------------
-
 class nsFloaterCache;
 class nsFloaterCacheList;
 class nsFloaterCacheFreeList;
@@ -135,6 +132,13 @@ protected:
 
 //----------------------------------------------------------------------
 
+#define LINE_MAX_BREAK_TYPE  ((1 << 4) - 1)
+#define LINE_MAX_CHILD_COUNT ((1 << 24) - 1)
+
+#if NS_STYLE_CLEAR_LAST_VALUE > 15
+need to rearrange the mBits bitfield;
+#endif
+
 /**
  * The nsLineBox class represents a horizontal line of frames. It contains
  * enough state to support incremental reflow of the frames, event handling
@@ -145,44 +149,96 @@ public:
   nsLineBox(nsIFrame* aFrame, PRInt32 aCount, PRBool aIsBlock);
   ~nsLineBox();
 
+  // mBlock bit
   PRBool IsBlock() const {
     return mFlags.mBlock;
   }
-
   PRBool IsInline() const {
     return 0 == mFlags.mBlock;
   }
 
-  // XXX Turn into a bit-field to simplify this code
+  // mDirty bit
+  void MarkDirty() {
+    mFlags.mDirty = 1;
+  }
+  void ClearDirty() {
+    mFlags.mDirty = 0;
+  }
+  PRBool IsDirty() const {
+    return mFlags.mDirty;
+  }
+
+  // mImpactedByFloater bit
+  void SetLineIsImpactedByFloater(PRBool aValue) {
+    mFlags.mImpactedByFloater = aValue;
+  }
+  PRBool IsImpactedByFloater() const {
+    return mFlags.mImpactedByFloater;
+  }
+
+  // mTrimmed bit
   void SetTrimmed(PRBool aOn) {
     mFlags.mTrimmed = aOn;
   }
-
   PRBool IsTrimmed() const {
     return mFlags.mTrimmed;
   }
 
+  // mChildCount value
+  PRInt32 GetChildCount() const {
+    return (PRInt32) mFlags.mChildCount;
+  }
+  void SetChildCount(PRInt32 aNewCount) {
+    if (NS_WARN_IF_FALSE(aNewCount >= 0, "negative child count")) {
+      aNewCount = 0;
+    }
+    if (aNewCount > LINE_MAX_CHILD_COUNT) {
+      aNewCount = LINE_MAX_CHILD_COUNT;
+    }
+    mFlags.mChildCount = aNewCount;
+  }
+
+  // mBreakType value
   PRBool HasBreak() const {
     return NS_STYLE_CLEAR_NONE != mFlags.mBreakType;
   }
-
   void SetBreakType(PRUint8 aBreakType) {
+    NS_WARN_IF_FALSE(aBreakType <= LINE_MAX_BREAK_TYPE, "bad break type");
     mFlags.mBreakType = aBreakType;
   }
-
   PRUint8 GetBreakType() const {
     return mFlags.mBreakType;
   }
 
-  nscoord GetCarriedOutBottomMargin() const {
+  // mCarriedOutBottomMargin value
-    return mCarriedOutBottomMargin;
+  nscoord GetCarriedOutBottomMargin() const;
+  void SetCarriedOutBottomMargin(nscoord aValue);
+
+  // mFloaters
+  PRBool HasFloaters() const {
+    return (IsInline() && mInlineData) && mInlineData->mFloaters.NotEmpty();
+  }
+  nsFloaterCache* GetFirstFloater();
+  void FreeFloaters(nsFloaterCacheFreeList& aFreeList);
+  void AppendFloaters(nsFloaterCacheFreeList& aFreeList);
+  PRBool RemoveFloater(nsIFrame* aFrame);
+
+  void SetCombinedArea(const nsRect& aCombinedArea);
+
+  void GetCombinedArea(nsRect* aResult);
+
+  void SlideBy(nscoord aDY) {
+    mBounds.y += aDY;
+    if (mData) {
+      mData->mCombinedArea.y += aDY;
+    }
   }
 
-  nscoord GetHeight() const { return mBounds.height; }
+  //----------------------------------------
-
-  //----------------------------------------------------------------------
-  // XXX old junk
 
+  nscoord GetHeight() const {
+    return mBounds.height;
+  }
 
   static void DeleteLineList(nsIPresContext& aPresContext, nsLineBox* aLine);
 
@@ -193,38 +249,10 @@ public:
 
   void List(FILE* out, PRInt32 aIndent) const;
 
-  PRInt32 ChildCount() const {
-    return PRInt32(mChildCount);
-  }
-
   nsIFrame* LastChild() const;
 
   PRBool IsLastChild(nsIFrame* aFrame) const;
 
-  void SetIsBlock(PRBool aValue) {
-    mFlags.mBlock = aValue;
-  }
-
-  void SetLineIsImpactedByFloater(PRBool aValue) {
-    mFlags.mImpactedByFloater = aValue;
-  }
-
-  PRBool IsImpactedByFloater() const {
-    return mFlags.mImpactedByFloater;
-  }
-
-  void MarkDirty() {
-    mFlags.mDirty = 1;
-  }
-
-  void ClearDirty() {
-    mFlags.mDirty = 0;
-  }
-
-  PRBool IsDirty() const {
-    return mFlags.mDirty;
-  }
-
   char* StateToString(char* aBuf, PRInt32 aBufSize) const;
 
   PRInt32 IndexOf(nsIFrame* aFrame) const;
@@ -233,21 +261,14 @@ public:
     return IndexOf(aFrame) >= 0;
   }
 
-#ifdef NS_DEBUG
-  PRBool CheckIsBlock() const;
-#endif
-
 #ifdef DEBUG
-  PRBool SizeOf(nsISizeOfHandler* aHandler, PRUint32* aResult) const;
+  nsIAtom* SizeOf(nsISizeOfHandler* aHandler, PRUint32* aResult) const;
 #endif
 
   nsIFrame* mFirstChild;
-  PRUint16 mChildCount;
-  nsRect mBounds;
-  nsRect mCombinedArea;
-  nscoord mCarriedOutBottomMargin;/* XXX switch to 16 bits */
-  nsFloaterCacheList mFloaters;
   nsLineBox* mNext;
+
+  nsRect mBounds;
   nscoord mMaxElementWidth;  // width part of max-element-size
 
   struct FlagBits {
@@ -256,9 +277,28 @@ public:
     PRUint32 mImpactedByFloater : 1;
     PRUint32 mTrimmed : 1;
 
-    PRUint32 reserved : 20;
+    PRUint32 mBreakType : 4;
 
-    PRUint32 mBreakType : 8;
+    PRUint32 mChildCount : 24;
+  };
+
+  struct ExtraData {
+    ExtraData(const nsRect& aBounds) : mCombinedArea(aBounds) {
+    }
+    nsRect mCombinedArea;
+  };
+
+  struct ExtraBlockData : public ExtraData {
+    ExtraBlockData(const nsRect& aBounds) : ExtraData(aBounds) {
+      mCarriedOutBottomMargin = 0;
+    }
+    nscoord mCarriedOutBottomMargin;
+  };
+
+  struct ExtraInlineData : public ExtraData {
+    ExtraInlineData(const nsRect& aBounds) : ExtraData(aBounds) {
+    }
+    nsFloaterCacheList mFloaters;
   };
 
 protected:
@@ -266,6 +306,14 @@ protected:
     PRUint32 mAllFlags;
     FlagBits mFlags;
   };
+
+  union {
+    ExtraData* mData;
+    ExtraBlockData* mBlockData;
+    ExtraInlineData* mInlineData;
+  };
+
+  void MaybeFreeData();
 };
 
 //----------------------------------------------------------------------

layout/html/base/src/nsLineBox.cpp

@@ -30,25 +30,37 @@
 MOZ_DECL_CTOR_COUNTER(nsLineBox);
 
 nsLineBox::nsLineBox(nsIFrame* aFrame, PRInt32 aCount, PRBool aIsBlock)
+  : mFirstChild(aFrame),
+    mNext(nsnull),
+    mBounds(0, 0, 0, 0),
+    mMaxElementWidth(0),
+    mData(nsnull)
 {
   MOZ_COUNT_CTOR(nsLineBox);
-  mFirstChild = aFrame;
+
-  mChildCount = aCount;
   mAllFlags = 0;
-  MarkDirty();
+#if NS_STYLE_CLEAR_NONE > 0
-  SetIsBlock(aIsBlock);
-  mNext = nsnull;
-  mBounds.SetRect(0,0,0,0);
-  mCombinedArea.SetRect(0,0,0,0);
-//XXX  mCarriedOutTopMargin = 0;
-  mCarriedOutBottomMargin = 0;
   mFlags.mBreakType = NS_STYLE_CLEAR_NONE;
-  mMaxElementWidth = 0;
+#endif
+  SetChildCount(aCount);
+  MarkDirty();
+  mFlags.mBlock = aIsBlock;
 }
 
 nsLineBox::~nsLineBox()
 {
   MOZ_COUNT_DTOR(nsLineBox);
+
+  if (IsBlock()) {
+    if (mBlockData) {
+      delete mBlockData;
+    }
+  }
+  else {
+    if (mInlineData) {
+      delete mInlineData;
+    }
+  }
 }
 
 static void
@@ -82,9 +94,11 @@ ListFloaters(FILE* out, PRInt32 aIndent, const nsFloaterCacheList& aFloaters)
 char*
 nsLineBox::StateToString(char* aBuf, PRInt32 aBufSize) const
 {
-  PR_snprintf(aBuf, aBufSize, "%s,%s[0x%x]",
+  PR_snprintf(aBuf, aBufSize, "%s,%s,%s,%s[0x%x]",
-              IsDirty() ? "dirty" : "clean",
               IsBlock() ? "block" : "inline",
+              IsDirty() ? "dirty" : "",
+              IsImpactedByFloater() ? "impacted" : "",
+              IsTrimmed() ? "trimmed" : "",
               mAllFlags);
   return aBuf;
 }
@@ -97,30 +111,33 @@ nsLineBox::List(FILE* out, PRInt32 aIndent) const
   for (i = aIndent; --i >= 0; ) fputs("  ", out);
   char cbuf[100];
   fprintf(out, "line %p: count=%d state=%s ",
-          this, ChildCount(), StateToString(cbuf, sizeof(cbuf)));
+          this, GetChildCount(), StateToString(cbuf, sizeof(cbuf)));
-  if (0 != mCarriedOutBottomMargin) {
+  if (0 != GetCarriedOutBottomMargin()) {
-    fprintf(out, "bm=%d ", mCarriedOutBottomMargin);
+    fprintf(out, "bm=%d ", GetCarriedOutBottomMargin());
   }
   if (0 != mMaxElementWidth) {
     fprintf(out, "mew=%d ", mMaxElementWidth);
   }
-  fprintf(out, "{%d,%d,%d,%d} ca={%d,%d,%d,%d}",
+  fprintf(out, "{%d,%d,%d,%d} ",
-          mBounds.x, mBounds.y, mBounds.width, mBounds.height,
+          mBounds.x, mBounds.y, mBounds.width, mBounds.height);
-          mCombinedArea.x, mCombinedArea.y,
+  if (mData) {
-          mCombinedArea.width, mCombinedArea.height);
+    fprintf(out, "ca={%d,%d,%d,%d} ",
-  fprintf(out, " <\n");
+            mData->mCombinedArea.x, mData->mCombinedArea.y,
+            mData->mCombinedArea.width, mData->mCombinedArea.height);
+  }
+  fprintf(out, "<\n");
 
   nsIFrame* frame = mFirstChild;
-  PRInt32 n = ChildCount();
+  PRInt32 n = GetChildCount();
   while (--n >= 0) {
     frame->List(out, aIndent + 1);
     frame->GetNextSibling(&frame);
   }
 
   for (i = aIndent; --i >= 0; ) fputs("  ", out);
-  if (mFloaters.NotEmpty()) {
+  if (HasFloaters()) {
     fputs("> floaters <\n", out);
-    ListFloaters(out, aIndent + 1, mFloaters);
+    ListFloaters(out, aIndent + 1, mInlineData->mFloaters);
     for (i = aIndent; --i >= 0; ) fputs("  ", out);
   }
   fputs(">\n", out);
@@ -130,7 +147,7 @@ nsIFrame*
 nsLineBox::LastChild() const
 {
   nsIFrame* frame = mFirstChild;
-  PRInt32 n = ChildCount() - 1;
+  PRInt32 n = GetChildCount() - 1;
   while (--n >= 0) {
     frame->GetNextSibling(&frame);
   }
@@ -147,7 +164,7 @@ nsLineBox::IsLastChild(nsIFrame* aFrame) const
 PRInt32
 nsLineBox::IndexOf(nsIFrame* aFrame) const
 {
-  PRInt32 i, n = ChildCount();
+  PRInt32 i, n = GetChildCount();
   nsIFrame* frame = mFirstChild;
   for (i = 0; i < n; i++) {
     if (frame == aFrame) {
@@ -208,39 +225,172 @@ nsLineBox::FindLineContaining(nsLineBox* aLine, nsIFrame* aFrame,
   return nsnull;
 }
 
-#ifdef NS_DEBUG
+nscoord
-PRBool
+nsLineBox::GetCarriedOutBottomMargin() const
-nsLineBox::CheckIsBlock() const
 {
-  PRBool isBlock = nsLineLayout::TreatFrameAsBlock(mFirstChild);
+  return (IsBlock() && mBlockData) ? mBlockData->mCarriedOutBottomMargin : 0;
-  return isBlock == IsBlock();
+}
+
+void
+nsLineBox::SetCarriedOutBottomMargin(nscoord aValue)
+{
+  if (IsBlock()) {
+    if (aValue) {
+      if (!mBlockData) {
+        mBlockData = new ExtraBlockData(mBounds);
+      }
+      if (mBlockData) {
+        mBlockData->mCarriedOutBottomMargin = aValue;
+      }
+    }
+    else if (mBlockData) {
+      mBlockData->mCarriedOutBottomMargin = aValue;
+      MaybeFreeData();
+    }
+  }
+}
+
+void
+nsLineBox::MaybeFreeData()
+{
+  if (mData && (mData->mCombinedArea == mBounds)) {
+    if (IsInline()) {
+      if (mInlineData->mFloaters.IsEmpty()) {
+        delete mInlineData;
+        mInlineData = nsnull;
+      }
+    }
+    else if (0 == mBlockData->mCarriedOutBottomMargin) {
+      delete mBlockData;
+      mBlockData = nsnull;
+    }
+  }
+}
+
+// XXX get rid of this???
+nsFloaterCache*
+nsLineBox::GetFirstFloater()
+{
+  if (NS_WARN_IF_FALSE(IsInline(), "block line can't have floaters")) {
+    return nsnull;
+  }
+  return mInlineData ? mInlineData->mFloaters.Head() : nsnull;
+}
+
+// XXX this might be too eager to free memory
+void
+nsLineBox::FreeFloaters(nsFloaterCacheFreeList& aFreeList)
+{
+  NS_WARN_IF_FALSE(IsInline(), "block line can't have floaters");
+  if (IsInline()) {
+    if (mInlineData) {
+      aFreeList.Append(mInlineData->mFloaters);
+      MaybeFreeData();
+    }
+  }
+}
+
+void
+nsLineBox::AppendFloaters(nsFloaterCacheFreeList& aFreeList)
+{
+  NS_WARN_IF_FALSE(IsInline(), "block line can't have floaters");
+  if (IsInline()) {
+    if (aFreeList.NotEmpty()) {
+      if (!mInlineData) {
+        mInlineData = new ExtraInlineData(mBounds);
+      }
+      if (mInlineData) {
+        mInlineData->mFloaters.Append(aFreeList);
+      }
+    }
+  }
+}
+
+PRBool
+nsLineBox::RemoveFloater(nsIFrame* aFrame)
+{
+  NS_WARN_IF_FALSE(IsInline(), "block line can't have floaters");
+  if (IsInline() && mInlineData) {
+    nsFloaterCache* fc = mInlineData->mFloaters.Find(aFrame);
+    if (fc) {
+      // Note: the placeholder is part of the line's child list
+      // and will be removed later.
+      fc->mPlaceholder->SetOutOfFlowFrame(nsnull);
+      mInlineData->mFloaters.Remove(fc);
+      MaybeFreeData();
+    }
+  }
+  return PR_FALSE;
+}
+
+void
+nsLineBox::SetCombinedArea(const nsRect& aCombinedArea)
+{
+  if (aCombinedArea != mBounds) {
+    if (mData) {
+      mData->mCombinedArea = aCombinedArea;
+    }
+    else {
+      if (IsInline()) {
+        mInlineData = new ExtraInlineData(aCombinedArea);
+      }
+      else {
+        mBlockData = new ExtraBlockData(aCombinedArea);
+      }
+    }
+  }
+  else {
+    if (mData) {
+      // Store away new value so that MaybeFreeData compares against
+      // the right value.
+      mData->mCombinedArea = aCombinedArea;
+    }
+    MaybeFreeData();
+  }
+}
+
+void
+nsLineBox::GetCombinedArea(nsRect* aResult)
+{
+  if (aResult) {
+    *aResult = mData ? mData->mCombinedArea : mBounds;
+  }
 }
-#endif
 
 #ifdef DEBUG
-PRBool
+nsIAtom*
 nsLineBox::SizeOf(nsISizeOfHandler* aHandler, PRUint32* aResult) const
 {
   NS_PRECONDITION(aResult, "null OUT parameter pointer");
   *aResult = sizeof(*this);
 
-  PRBool big = PR_TRUE;
+  nsIAtom* atom;
-  if ((IsBlock() || mFloaters.IsEmpty()) &&
+  if (IsBlock()) {
-      (mBounds == mCombinedArea)) {
+    atom = nsLayoutAtoms::lineBoxBlockSmall;
-    big = PR_FALSE;
+    if (mBlockData) {
+      atom = nsLayoutAtoms::lineBoxBlockBig;
+      *aResult += sizeof(*mBlockData);
     }
+  }
+  else {
+    atom = nsLayoutAtoms::lineBoxSmall;
+    if (mInlineData) {
+      atom = nsLayoutAtoms::lineBoxBig;
+      *aResult += sizeof(*mInlineData);
 
       // Add in the size needed for floaters associated with this line
-  if (mFloaters.NotEmpty()) {
+      if (HasFloaters()) {
         PRUint32  floatersSize;
+        mInlineData->mFloaters.SizeOf(aHandler, &floatersSize);
 
-    mFloaters.SizeOf(aHandler, &floatersSize);
         // Base size of embedded object was included in sizeof(*this) above
-    floatersSize -= sizeof(mFloaters);
+        floatersSize -= sizeof(mInlineData->mFloaters);
         aHandler->AddSize(nsLayoutAtoms::lineBoxFloaters, floatersSize);
       }
+    }
+  }
 
-  return big;
+  return atom;
 }
 #endif
 
@@ -346,7 +496,7 @@ nsLineIterator::GetLine(PRInt32 aLineNumber,
   }
   nsLineBox* line = mLines[aLineNumber];
   *aFirstFrameOnLine = line->mFirstChild;
-  *aNumFramesOnLine = line->mChildCount;
+  *aNumFramesOnLine = line->GetChildCount();
   aLineBounds = line->mBounds;
 
   PRUint32 flags = 0;
@@ -462,7 +612,7 @@ nsLineIterator::FindFrameAt(PRInt32 aLineNumber,
   *aXIsAfterLastFrame = PR_FALSE;
   nsRect r1, r2;
   nsIFrame* frame = line->mFirstChild;
-  PRInt32 n = line->mChildCount;
+  PRInt32 n = line->GetChildCount();
   if (mRightToLeft) {
     while (--n >= 0) {
       nsIFrame* nextFrame;
@@ -528,6 +678,7 @@ nsFloaterCacheList::~nsFloaterCacheList()
     delete floater;
     floater = next;
   }
+  mHead = nsnull;
 }
 
 nsFloaterCache*

layout/html/base/src/nsLineBox.h

@@ -26,9 +26,6 @@
 
 class nsISpaceManager;
 class nsLineBox;
-
-//----------------------------------------------------------------------
-
 class nsFloaterCache;
 class nsFloaterCacheList;
 class nsFloaterCacheFreeList;
@@ -135,6 +132,13 @@ protected:
 
 //----------------------------------------------------------------------
 
+#define LINE_MAX_BREAK_TYPE  ((1 << 4) - 1)
+#define LINE_MAX_CHILD_COUNT ((1 << 24) - 1)
+
+#if NS_STYLE_CLEAR_LAST_VALUE > 15
+need to rearrange the mBits bitfield;
+#endif
+
 /**
  * The nsLineBox class represents a horizontal line of frames. It contains
  * enough state to support incremental reflow of the frames, event handling
@@ -145,44 +149,96 @@ public:
   nsLineBox(nsIFrame* aFrame, PRInt32 aCount, PRBool aIsBlock);
   ~nsLineBox();
 
+  // mBlock bit
   PRBool IsBlock() const {
     return mFlags.mBlock;
   }
-
   PRBool IsInline() const {
     return 0 == mFlags.mBlock;
   }
 
-  // XXX Turn into a bit-field to simplify this code
+  // mDirty bit
+  void MarkDirty() {
+    mFlags.mDirty = 1;
+  }
+  void ClearDirty() {
+    mFlags.mDirty = 0;
+  }
+  PRBool IsDirty() const {
+    return mFlags.mDirty;
+  }
+
+  // mImpactedByFloater bit
+  void SetLineIsImpactedByFloater(PRBool aValue) {
+    mFlags.mImpactedByFloater = aValue;
+  }
+  PRBool IsImpactedByFloater() const {
+    return mFlags.mImpactedByFloater;
+  }
+
+  // mTrimmed bit
   void SetTrimmed(PRBool aOn) {
     mFlags.mTrimmed = aOn;
   }
-
   PRBool IsTrimmed() const {
     return mFlags.mTrimmed;
   }
 
+  // mChildCount value
+  PRInt32 GetChildCount() const {
+    return (PRInt32) mFlags.mChildCount;
+  }
+  void SetChildCount(PRInt32 aNewCount) {
+    if (NS_WARN_IF_FALSE(aNewCount >= 0, "negative child count")) {
+      aNewCount = 0;
+    }
+    if (aNewCount > LINE_MAX_CHILD_COUNT) {
+      aNewCount = LINE_MAX_CHILD_COUNT;
+    }
+    mFlags.mChildCount = aNewCount;
+  }
+
+  // mBreakType value
   PRBool HasBreak() const {
     return NS_STYLE_CLEAR_NONE != mFlags.mBreakType;
   }
-
   void SetBreakType(PRUint8 aBreakType) {
+    NS_WARN_IF_FALSE(aBreakType <= LINE_MAX_BREAK_TYPE, "bad break type");
     mFlags.mBreakType = aBreakType;
   }
-
   PRUint8 GetBreakType() const {
     return mFlags.mBreakType;
   }
 
-  nscoord GetCarriedOutBottomMargin() const {
+  // mCarriedOutBottomMargin value
-    return mCarriedOutBottomMargin;
+  nscoord GetCarriedOutBottomMargin() const;
+  void SetCarriedOutBottomMargin(nscoord aValue);
+
+  // mFloaters
+  PRBool HasFloaters() const {
+    return (IsInline() && mInlineData) && mInlineData->mFloaters.NotEmpty();
+  }
+  nsFloaterCache* GetFirstFloater();
+  void FreeFloaters(nsFloaterCacheFreeList& aFreeList);
+  void AppendFloaters(nsFloaterCacheFreeList& aFreeList);
+  PRBool RemoveFloater(nsIFrame* aFrame);
+
+  void SetCombinedArea(const nsRect& aCombinedArea);
+
+  void GetCombinedArea(nsRect* aResult);
+
+  void SlideBy(nscoord aDY) {
+    mBounds.y += aDY;
+    if (mData) {
+      mData->mCombinedArea.y += aDY;
+    }
   }
 
-  nscoord GetHeight() const { return mBounds.height; }
+  //----------------------------------------
-
-  //----------------------------------------------------------------------
-  // XXX old junk
 
+  nscoord GetHeight() const {
+    return mBounds.height;
+  }
 
   static void DeleteLineList(nsIPresContext& aPresContext, nsLineBox* aLine);
 
@@ -193,38 +249,10 @@ public:
 
   void List(FILE* out, PRInt32 aIndent) const;
 
-  PRInt32 ChildCount() const {
-    return PRInt32(mChildCount);
-  }
-
   nsIFrame* LastChild() const;
 
   PRBool IsLastChild(nsIFrame* aFrame) const;
 
-  void SetIsBlock(PRBool aValue) {
-    mFlags.mBlock = aValue;
-  }
-
-  void SetLineIsImpactedByFloater(PRBool aValue) {
-    mFlags.mImpactedByFloater = aValue;
-  }
-
-  PRBool IsImpactedByFloater() const {
-    return mFlags.mImpactedByFloater;
-  }
-
-  void MarkDirty() {
-    mFlags.mDirty = 1;
-  }
-
-  void ClearDirty() {
-    mFlags.mDirty = 0;
-  }
-
-  PRBool IsDirty() const {
-    return mFlags.mDirty;
-  }
-
   char* StateToString(char* aBuf, PRInt32 aBufSize) const;
 
   PRInt32 IndexOf(nsIFrame* aFrame) const;
@@ -233,21 +261,14 @@ public:
     return IndexOf(aFrame) >= 0;
   }
 
-#ifdef NS_DEBUG
-  PRBool CheckIsBlock() const;
-#endif
-
 #ifdef DEBUG
-  PRBool SizeOf(nsISizeOfHandler* aHandler, PRUint32* aResult) const;
+  nsIAtom* SizeOf(nsISizeOfHandler* aHandler, PRUint32* aResult) const;
 #endif
 
   nsIFrame* mFirstChild;
-  PRUint16 mChildCount;
-  nsRect mBounds;
-  nsRect mCombinedArea;
-  nscoord mCarriedOutBottomMargin;/* XXX switch to 16 bits */
-  nsFloaterCacheList mFloaters;
   nsLineBox* mNext;
+
+  nsRect mBounds;
   nscoord mMaxElementWidth;  // width part of max-element-size
 
   struct FlagBits {
@@ -256,9 +277,28 @@ public:
     PRUint32 mImpactedByFloater : 1;
     PRUint32 mTrimmed : 1;
 
-    PRUint32 reserved : 20;
+    PRUint32 mBreakType : 4;
 
-    PRUint32 mBreakType : 8;
+    PRUint32 mChildCount : 24;
+  };
+
+  struct ExtraData {
+    ExtraData(const nsRect& aBounds) : mCombinedArea(aBounds) {
+    }
+    nsRect mCombinedArea;
+  };
+
+  struct ExtraBlockData : public ExtraData {
+    ExtraBlockData(const nsRect& aBounds) : ExtraData(aBounds) {
+      mCarriedOutBottomMargin = 0;
+    }
+    nscoord mCarriedOutBottomMargin;
+  };
+
+  struct ExtraInlineData : public ExtraData {
+    ExtraInlineData(const nsRect& aBounds) : ExtraData(aBounds) {
+    }
+    nsFloaterCacheList mFloaters;
   };
 
 protected:
@@ -266,6 +306,14 @@ protected:
     PRUint32 mAllFlags;
     FlagBits mFlags;
   };
+
+  union {
+    ExtraData* mData;
+    ExtraBlockData* mBlockData;
+    ExtraInlineData* mInlineData;
+  };
+
+  void MaybeFreeData();
 };
 
 //----------------------------------------------------------------------