Change LayoutState to be stack-allocated

Source/core/rendering/LayoutState.h

 /*
  * Copyright (C) 2007 Apple Inc.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 15 matching lines @@
 #ifndef LayoutState_h
 #define LayoutState_h
 
 #include "core/rendering/ColumnInfo.h"
 #include "platform/geometry/LayoutRect.h"
 #include "wtf/HashMap.h"
 #include "wtf/Noncopyable.h"
 
 namespace WebCore {
 
+class ForceHorriblySlowRectMapping;
 class RenderBlockFlow;
 class RenderBox;
 class RenderObject;
 class RenderFlowThread;
+class RenderView;
 
 class LayoutState {
     WTF_MAKE_NONCOPYABLE(LayoutState);
 public:
     // Constructor for root LayoutState created by RenderView
-    LayoutState(LayoutUnit pageLogicalHeight, bool pageLogicalHeightChanged)
-        : m_clipped(false)
-        , m_isPaginated(pageLogicalHeight)
-        , m_pageLogicalHeightChanged(pageLogicalHeightChanged)
-#if ASSERT_ENABLED
-        , m_layoutDeltaXSaturated(false)
-        , m_layoutDeltaYSaturated(false)
-#endif
-        , m_columnInfo(0)
-        , m_next(0)
-        , m_pageLogicalHeight(pageLogicalHeight)
-#ifndef NDEBUG
-        , m_renderer(0)
-#endif
-    {
-    }
+    LayoutState(LayoutUnit pageLogicalHeight, bool pageLogicalHeightChanged, RenderView&);
+    // Constructor for sub-tree Layout and RenderTableSections
+    explicit LayoutState(RenderObject& root);
 
-    LayoutState(LayoutState*, RenderBox&, const LayoutSize& offset, LayoutUnit pageLogicalHeight, bool pageHeightLogicalChanged, ColumnInfo*);
-    explicit LayoutState(RenderObject&);
+    LayoutState(RenderBox&, const LayoutSize& offset, LayoutUnit pageLogicalHeight = 0, bool pageHeightLogicalChanged = false, ColumnInfo* = 0);
 
-    // LayoutState is allocated out of the rendering partition.
-    void* operator new(size_t);
-    void operator delete(void*);
+    ~LayoutState();
 
     void clearPaginationInformation();
     bool isPaginatingColumns() const { return m_columnInfo; }
     bool isPaginated() const { return m_isPaginated; }
     bool isClipped() const { return m_clipped; }
 
     // The page logical offset is the object's offset from the top of the page in the page progression
     // direction (so an x-offset in vertical text and a y-offset for horizontal text).
     LayoutUnit pageLogicalOffset(const RenderBox&, const LayoutUnit& childLogicalOffset) const;
 
@@ skipping 15 matching lines @@
     const LayoutSize& pageOffset() const { return m_pageOffset; }
     LayoutUnit pageLogicalHeight() const { return m_pageLogicalHeight; }
     bool pageLogicalHeightChanged() const { return m_pageLogicalHeightChanged; }
 
     LayoutState* next() const { return m_next; }
 
     bool needsBlockDirectionLocationSetBeforeLayout() const { return m_isPaginated && m_pageLogicalHeight; }
 
     ColumnInfo* columnInfo() const { return m_columnInfo; }
 
-    const LayoutRect& clipRect() const { return m_clipRect; }
-    const LayoutSize& paintOffset() const { return m_paintOffset; }
+    bool cachedOffsetsEnabled() const { return m_cachedOffsetsEnabled; }
 
-#ifndef NDEBUG
-    RenderObject* renderer() const { return m_renderer; }
-#endif
+    const LayoutRect& clipRect() const
+    {
+        ASSERT(m_cachedOffsetsEnabled);
+        return m_clipRect;
+    }
+    const LayoutSize& paintOffset() const
+    {
+        ASSERT(m_cachedOffsetsEnabled);
+        return m_paintOffset;
+    }
+
+
+    RenderObject& renderer() const { return m_renderer; }
+
 #if ASSERT_ENABLED
     bool layoutDeltaXSaturated() const { return m_layoutDeltaXSaturated; }
     bool layoutDeltaYSaturated() const { return m_layoutDeltaYSaturated; }
 #endif
 
 private:
+    friend class ForceHorriblySlowRectMapping;
+
     // Do not add anything apart from bitfields until after m_columnInfo. See https://bugs.webkit.org/show_bug.cgi?id=100173
     bool m_clipped:1;
     bool m_isPaginated:1;
     // If our page height has changed, this will force all blocks to relayout.
     bool m_pageLogicalHeightChanged:1;
+
+    bool m_cachedOffsetsEnabled:1;
 #if ASSERT_ENABLED
     bool m_layoutDeltaXSaturated:1;
     bool m_layoutDeltaYSaturated:1;

[esprehn, 2014/06/14 03:08:27]

We should switch all these back to real bools instead of bitfields after this
lands. Since we always make these on the stack now using bitfields just makes it
slower.

 #endif
     // If the enclosing pagination model is a column model, then this will store column information for easy retrieval/manipulation.
     ColumnInfo* m_columnInfo;
     LayoutState* m_next;
 
     // FIXME: Distinguish between the layout clip rect and the paint clip rect which may be larger,
     // e.g., because of composited scrolling.
     LayoutRect m_clipRect;
 
     // x/y offset from container. Includes relative positioning and scroll offsets.
     LayoutSize m_paintOffset;
     // x/y offset from container. Does not include relative positioning or scroll offsets.
     LayoutSize m_layoutOffset;
     // Transient offset from the final position of the object
     // used to ensure that repaints happen in the correct place.
     // This is a total delta accumulated from the root.
     LayoutSize m_layoutDelta;
 
     // The current page height for the pagination model that encloses us.
     LayoutUnit m_pageLogicalHeight;
     // The offset of the start of the first page in the nearest enclosing pagination model.
     LayoutSize m_pageOffset;
 
-#ifndef NDEBUG
-    RenderObject* m_renderer;
-#endif
+    RenderObject& m_renderer;
 };
 
 } // namespace WebCore
 
 #endif // LayoutState_h