Remove legacy layout diffing

Summary:
This removes some unused flags which will cause Yoga to layout every tree twice, then diffing the tree, reporting whether the whole tree is different. This is too expensive to run outside of local experimentation, but we have more nuanced ways to implement the `YGNodeLayoutAffectedByQuirk` I am wanting to add.

Changelog: [Internal]

Reviewed By: lunaleaps

Differential Revision: D42406917

fbshipit-source-id: b415ed02768f6b59de3a6fa90c60c750d56fd4b0

yoga/Yoga.cpp

@@ -180,10 +180,6 @@ YOGA_EXPORT bool YGNodeIsDirty(YGNodeRef node) {
   return node->isDirty();
 }
 
-YOGA_EXPORT bool YGNodeLayoutGetDidUseLegacyFlag(const YGNodeRef node) {
-  return node->didUseLegacyFlag();
-}
-
 YOGA_EXPORT void YGNodeMarkDirtyAndPropogateToDescendants(
     const YGNodeRef node) {
   return node->markDirtyAndPropogateDownwards();
@@ -220,32 +216,6 @@ YOGA_EXPORT YGNodeRef YGNodeClone(YGNodeRef oldNode) {
   return node;
 }
 
-static YGConfigRef YGConfigClone(const YGConfig& oldConfig) {
-  const YGConfigRef config = new YGConfig(oldConfig);
-  YGAssert(config != nullptr, "Could not allocate memory for config");
-  gConfigInstanceCount++;
-  return config;
-}
-
-static YGNodeRef YGNodeDeepClone(YGNodeRef oldNode) {
-  auto config = YGConfigClone(*oldNode->getConfig());
-  auto node = new YGNode{*oldNode, config};
-  node->setOwner(nullptr);
-  Event::publish<Event::NodeAllocation>(node, {node->getConfig()});
-
-  YGVector vec = YGVector();
-  vec.reserve(oldNode->getChildren().size());
-  YGNodeRef childNode = nullptr;
-  for (auto* item : oldNode->getChildren()) {
-    childNode = YGNodeDeepClone(item);
-    childNode->setOwner(node);
-    vec.push_back(childNode);
-  }
-  node->setChildren(vec);
-
-  return node;
-}
-
 YOGA_EXPORT void YGNodeFree(const YGNodeRef node) {
   if (YGNodeRef owner = node->getOwner()) {
     owner->removeChild(node);
@@ -263,17 +233,6 @@ YOGA_EXPORT void YGNodeFree(const YGNodeRef node) {
   delete node;
 }
 
-static void YGConfigFreeRecursive(const YGNodeRef root) {
-  if (root->getConfig() != nullptr) {
-    gConfigInstanceCount--;
-    delete root->getConfig();
-  }
-  // Delete configs recursively for childrens
-  for (auto* child : root->getChildren()) {
-    YGConfigFreeRecursive(child);
-  }
-}
-
 YOGA_EXPORT void YGNodeFreeRecursiveWithCleanupFunc(
     const YGNodeRef root,
     YGNodeCleanupFunc cleanup) {
@@ -993,11 +952,6 @@ YG_NODE_LAYOUT_RESOLVED_PROPERTY_IMPL(float, Margin, margin);
 YG_NODE_LAYOUT_RESOLVED_PROPERTY_IMPL(float, Border, border);
 YG_NODE_LAYOUT_RESOLVED_PROPERTY_IMPL(float, Padding, padding);
 
-YOGA_EXPORT bool YGNodeLayoutGetDidLegacyStretchFlagAffectLayout(
-    const YGNodeRef node) {
-  return node->getLayout().doesLegacyStretchFlagAffectsLayout();
-}
-
 std::atomic<uint32_t> gCurrentGenerationCount(0);
 
 bool YGLayoutNodeInternal(
@@ -3051,9 +3005,6 @@ static void YGNodelayoutImpl(
               collectedFlexItemsValues.sizeConsumedOnCurrentLine;
         }
 
-        if (node->getConfig()->useLegacyStretchBehaviour) {
-          node->setLayoutDidUseLegacyFlag(true);
-        }
         sizeBasedOnContent = !node->getConfig()->useLegacyStretchBehaviour;
       }
     }
@@ -4205,13 +4156,6 @@ static void YGRoundToPixelGrid(
   }
 }
 
-static void unsetUseLegacyFlagRecursively(YGNodeRef node) {
-  node->getConfig()->useLegacyStretchBehaviour = false;
-  for (auto child : node->getChildren()) {
-    unsetUseLegacyFlagRecursively(child);
-  }
-}
-
 YOGA_EXPORT void YGNodeCalculateLayoutWithContext(
     const YGNodeRef node,
     const float ownerWidth,
@@ -4297,67 +4241,6 @@ YOGA_EXPORT void YGNodeCalculateLayoutWithContext(
   }
 
   Event::publish<Event::LayoutPassEnd>(node, {layoutContext, &markerData});
-
-  // We want to get rid off `useLegacyStretchBehaviour` from YGConfig. But we
-  // aren't sure whether client's of yoga have gotten rid off this flag or not.
-  // So logging this in YGLayout would help to find out the call sites depending
-  // on this flag. This check would be removed once we are sure no one is
-  // dependent on this flag anymore. The flag
-  // `shouldDiffLayoutWithoutLegacyStretchBehaviour` in YGConfig will help to
-  // run experiments.
-  if (node->getConfig()->shouldDiffLayoutWithoutLegacyStretchBehaviour &&
-      node->didUseLegacyFlag()) {
-    const YGNodeRef nodeWithoutLegacyFlag = YGNodeDeepClone(node);
-    nodeWithoutLegacyFlag->resolveDimension();
-    // Recursively mark nodes as dirty
-    nodeWithoutLegacyFlag->markDirtyAndPropogateDownwards();
-    gCurrentGenerationCount.fetch_add(1, std::memory_order_relaxed);
-    // Rerun the layout, and calculate the diff
-    unsetUseLegacyFlagRecursively(nodeWithoutLegacyFlag);
-    LayoutData layoutMarkerData = {};
-    if (YGLayoutNodeInternal(
-            nodeWithoutLegacyFlag,
-            width,
-            height,
-            ownerDirection,
-            widthMeasureMode,
-            heightMeasureMode,
-            ownerWidth,
-            ownerHeight,
-            true,
-            LayoutPassReason::kInitial,
-            nodeWithoutLegacyFlag->getConfig(),
-            layoutMarkerData,
-            layoutContext,
-            0, // tree root
-            gCurrentGenerationCount.load(std::memory_order_relaxed))) {
-      nodeWithoutLegacyFlag->setPosition(
-          nodeWithoutLegacyFlag->getLayout().direction(),
-          ownerWidth,
-          ownerHeight,
-          ownerWidth);
-      YGRoundToPixelGrid(
-          nodeWithoutLegacyFlag,
-          nodeWithoutLegacyFlag->getConfig()->pointScaleFactor,
-          0.0f,
-          0.0f);
-
-      // Set whether the two layouts are different or not.
-      auto neededLegacyStretchBehaviour =
-          !nodeWithoutLegacyFlag->isLayoutTreeEqualToNode(*node);
-      node->setLayoutDoesLegacyFlagAffectsLayout(neededLegacyStretchBehaviour);
-
-#ifdef DEBUG
-      if (nodeWithoutLegacyFlag->getConfig()->printTree) {
-        YGNodePrint(
-            nodeWithoutLegacyFlag,
-            (YGPrintOptions) (YGPrintOptionsLayout | YGPrintOptionsChildren | YGPrintOptionsStyle));
-      }
-#endif
-    }
-    YGConfigFreeRecursive(nodeWithoutLegacyFlag);
-    YGNodeFreeRecursive(nodeWithoutLegacyFlag);
-  }
 }
 
 YOGA_EXPORT void YGNodeCalculateLayout(
@@ -4381,12 +4264,6 @@ YOGA_EXPORT void YGConfigSetLogger(const YGConfigRef config, YGLogger logger) {
   }
 }
 
-YOGA_EXPORT void YGConfigSetShouldDiffLayoutWithoutLegacyStretchBehaviour(
-    const YGConfigRef config,
-    const bool shouldDiffLayout) {
-  config->shouldDiffLayoutWithoutLegacyStretchBehaviour = shouldDiffLayout;
-}
-
 void YGAssert(const bool condition, const char* message) {
   if (!condition) {
     Log::log(YGNodeRef{nullptr}, YGLogLevelFatal, nullptr, "%s\n", message);