Backed out changeset c872cc627115 (bug 1558937) for reftest failures at 1558937-1.html.

layout/generic/nsPageFrame.cpp

@@ -405,8 +405,8 @@ static void BuildDisplayListForExtraPage(nsDisplayListBuilder* aBuilder,
                                          nsPageFrame* aPage,
                                          nsIFrame* aExtraPage,
                                          nsDisplayList* aList) {
-  // The only content in aExtraPage we care about is out-of-flow content from
-  // aPage, whose placeholders have occurred in aExtraPage. If
+  // The only content in aExtraPage we care about is out-of-flow content whose
+  // placeholders have occurred in aPage. If
   // NS_FRAME_FORCE_DISPLAY_LIST_DESCEND_INTO is not set, then aExtraPage has
   // no such content.
   if (!aExtraPage->HasAnyStateBits(NS_FRAME_FORCE_DISPLAY_LIST_DESCEND_INTO)) {
@@ -520,27 +520,13 @@ void nsPageFrame::BuildDisplayList(nsDisplayListBuilder* aBuilder,
     // these extra pages are pruned so that only display items for the
     // page we currently care about (which we would have reached by
     // following placeholders to their out-of-flows) end up on the list.
-    //
-    // Stacking context frames that wrap content on their normal page,
-    // as well as OOF content for this page will have their container
-    // items duplicated. We tell the builder to include our page number
-    // in the unique key for any extra page items so that they can be
-    // differentiated from the ones created on the normal page.
-    NS_ASSERTION(mPageNum <= 255, "Too many pages to handle OOFs");
-    if (mPageNum <= 255) {
-      uint8_t oldPageNum = aBuilder->GetBuildingExtraPagesForPageNum();
-      aBuilder->SetBuildingExtraPagesForPageNum(mPageNum);
+    nsIFrame* page = child;
+    while ((page = GetNextPage(page)) != nullptr) {
+      nsRect childVisible = visibleRect + child->GetOffsetTo(page);
 
-      nsIFrame* page = child;
-      while ((page = GetNextPage(page)) != nullptr) {
-        nsRect childVisible = visibleRect + child->GetOffsetTo(page);
-
-        nsDisplayListBuilder::AutoBuildingDisplayList buildingForChild(
-            aBuilder, page, childVisible, childVisible);
-        BuildDisplayListForExtraPage(aBuilder, this, page, &content);
-      }
-
-      aBuilder->SetBuildingExtraPagesForPageNum(oldPageNum);
+      nsDisplayListBuilder::AutoBuildingDisplayList buildingForChild(
+          aBuilder, page, childVisible, childVisible);
+      BuildDisplayListForExtraPage(aBuilder, this, page, &content);
     }
 
     // Invoke AutoBuildingDisplayList to ensure that the correct visibleRect

layout/painting/nsDisplayList.cpp

@@ -1221,7 +1221,6 @@ nsDisplayListBuilder::nsDisplayListBuilder(nsIFrame* aReferenceFrame,
       mRootAGR(AnimatedGeometryRoot::CreateAGRForFrame(
           aReferenceFrame, nullptr, true, aRetainingDisplayList)),
       mCurrentAGR(mRootAGR),
-      mBuildingExtraPagesForPageNum(0),
       mUsedAGRBudget(0),
       mDirtyRect(-1, -1, -1, -1),
       mGlassDisplayItem(nullptr),

layout/painting/nsDisplayList.h

@@ -1699,13 +1699,6 @@ class nsDisplayListBuilder {
     mBuildingInvisibleItems = aBuildingInvisibleItems;
   }
 
-  void SetBuildingExtraPagesForPageNum(uint8_t aPageNum) {
-    mBuildingExtraPagesForPageNum = aPageNum;
-  }
-  uint8_t GetBuildingExtraPagesForPageNum() const {
-    return mBuildingExtraPagesForPageNum;
-  }
-
   /**
    * This is a convenience function to ease the transition until AGRs and ASRs
    * are unified.
@@ -1896,8 +1889,6 @@ class nsDisplayListBuilder {
   nsDataHashtable<nsPtrHashKey<nsIFrame>, FrameWillChangeBudget>
       mWillChangeBudgetSet;
 
-  uint8_t mBuildingExtraPagesForPageNum;
-
   // Area of animated geometry root budget already allocated
   uint32_t mUsedAGRBudget;
   // Set of frames already counted in budget
@@ -2074,7 +2065,6 @@ MOZ_ALWAYS_INLINE T* MakeDisplayItem(nsDisplayListBuilder* aBuilder, F* aFrame,
   }
 
   item->SetPerFrameKey(item->CalculatePerFrameKey());
-  item->SetExtraPageForPageNum(aBuilder->GetBuildingExtraPagesForPageNum());
 
   nsPaintedDisplayItem* paintedItem = item->AsPaintedDisplayItem();
   if (paintedItem) {
@@ -2087,7 +2077,8 @@ MOZ_ALWAYS_INLINE T* MakeDisplayItem(nsDisplayListBuilder* aBuilder, F* aFrame,
   }
 
 #ifdef MOZ_DIAGNOSTIC_ASSERT_ENABLED
-  if (aBuilder->IsRetainingDisplayList() && aBuilder->IsBuilding()) {
+  if (aBuilder->IsRetainingDisplayList() && !aBuilder->IsInPageSequence() &&
+      aBuilder->IsBuilding()) {
     AssertUniqueItem(item);
   }
 
@@ -2229,12 +2220,11 @@ class nsDisplayItemBase : public nsDisplayItemLink {
    * uniquely identifies this display item in the display item tree.
    */
   uint32_t GetPerFrameKey() const {
-    // The top 8 bits are the page index
+    // The top 8 bits are currently unused.
     // The middle 16 bits of the per frame key uniquely identify the display
     // item when there are more than one item of the same type for a frame.
     // The low 8 bits are the display item type.
-    return (static_cast<uint32_t>(mExtraPageForPageNum) << (TYPE_BITS + (sizeof(mKey) * 8))) |
-           (static_cast<uint32_t>(mKey) << TYPE_BITS) |
+    return (static_cast<uint32_t>(mKey) << TYPE_BITS) |
            static_cast<uint32_t>(mType);
   }
 
@@ -2341,7 +2331,6 @@ class nsDisplayItemBase : public nsDisplayItemLink {
       : mFrame(aOther.mFrame),
         mItemFlags(aOther.mItemFlags),
         mType(aOther.mType),
-        mExtraPageForPageNum(aOther.mExtraPageForPageNum),
         mKey(aOther.mKey) {
     MOZ_COUNT_CTOR(nsDisplayItemBase);
   }
@@ -2356,15 +2345,6 @@ class nsDisplayItemBase : public nsDisplayItemLink {
   void SetType(const DisplayItemType aType) { mType = aType; }
   void SetPerFrameKey(const uint16_t aKey) { mKey = aKey; }
 
-  // Display list building for printing can build duplicate
-  // container display items when they contain a mixture of
-  // OOF and normal content that is spread across multiple
-  // pages. We include the page number for the duplicates
-  // to make our GetPerFrameKey unique.
-  void SetExtraPageForPageNum(const uint8_t aPageNum) {
-    mExtraPageForPageNum = aPageNum;
-  }
-
   void SetDeletedFrame();
 
   nsIFrame* mFrame;  // 8
@@ -2383,7 +2363,6 @@ class nsDisplayItemBase : public nsDisplayItemLink {
 
   mozilla::EnumSet<ItemBaseFlag, uint8_t> mItemFlags;  // 1
   DisplayItemType mType;                               // 1
-  uint8_t mExtraPageForPageNum = 0;                    // 1
   uint16_t mKey;                                       // 2
   OldListIndex mOldListIndex;                          // 4
   uintptr_t mOldList = 0;                              // 8

layout/reftests/bugs/1558937-1-ref.html

@@ -1,9 +0,0 @@
-<!DOCTYPE html>
-<html class="reftest-paged">
-<body>
-<div style="height:400px;"></div>
-<div style="height:1000px">
-  <div style="width:100px; height:100px; background:black;">Hi</div>
-</div>
-</body>
-</html>

layout/reftests/bugs/1558937-1.html

@@ -1,10 +0,0 @@
-<!DOCTYPE html>
-<html class="reftest-paged">
-<body>
-<div style="height:400px;"></div>
-<div style="height:1000px; clip-path:border-box">
-  <div style="position:absolute; top:0; left:0; width:100px; height:100px; background:black;">Hi</div>
-  <div style="width:100px; height:100px; background:black;">Hi</div>
-</div>
-</body>
-</html>

layout/reftests/bugs/reftest.list

@@ -2109,4 +2109,3 @@ fuzzy-if(!webrender,0-6,0-34) fails-if(webrender) fuzzy-if(geckoview,9-9,44-44)
 skip-if(!asyncPan) fuzzy-if(geckoview,1-1,165-165) == 1544895.html 1544895-ref.html
 == 1548809.html 1548809-ref.html
 != 1552789-1.html 1552789-ref-1.html
-== 1558937-1.html 1558937-1-ref.html