Remove BitUtils Usage in YGNode (#1250)

Summary:
Pull Request resolved: https://github.com/facebook/yoga/pull/1250

X-link: https://github.com/facebook/react-native/pull/36988

BitUtils functions in Yoga are like bit fields, with more steps, and more error prone (you need to work with explicit offsets which can be tricky for anything variable length). Replace usage with a bitfield struct. Eventually I'd like to remove the BitUtils functions in general.

Changelog: [Internal]

Reviewed By: rshest

Differential Revision: D45133645

fbshipit-source-id: aa1430df5e2fb71ed9d2a5f5b1a35429b71c7069

yoga/YGNode.cpp

@@ -8,7 +8,6 @@
 #include "YGNode.h"
 #include <algorithm>
 #include <iostream>
-#include "CompactValue.h"
 #include "Utils.h"
 
 using namespace facebook;
@@ -16,7 +15,7 @@ using facebook::yoga::detail::CompactValue;
 
 YGNode::YGNode(YGNode&& node) {
   context_ = node.context_;
-  flags = node.flags;
+  flags_ = node.flags_;
   measure_ = node.measure_;
   baseline_ = node.baseline_;
   print_ = node.print_;
@@ -42,7 +41,7 @@ YGNode::YGNode(const YGNode& node, YGConfigRef config) : YGNode{node} {
 
 void YGNode::print(void* printContext) {
   if (print_.noContext != nullptr) {
-    if (facebook::yoga::detail::getBooleanData(flags, printUsesContext_)) {
+    if (flags_.printUsesContext) {
       print_.withContext(this, printContext);
     } else {
       print_.noContext(this);
@@ -202,14 +201,14 @@ YGSize YGNode::measure(
     float height,
     YGMeasureMode heightMode,
     void* layoutContext) {
-  return facebook::yoga::detail::getBooleanData(flags, measureUsesContext_)
+  return flags_.measureUsesContext
       ? measure_.withContext(
             this, width, widthMode, height, heightMode, layoutContext)
       : measure_.noContext(this, width, widthMode, height, heightMode);
 }
 
 float YGNode::baseline(float width, float height, void* layoutContext) {
-  return facebook::yoga::detail::getBooleanData(flags, baselineUsesContext_)
+  return flags_.baselineUsesContext
       ? baseline_.withContext(this, width, height, layoutContext)
       : baseline_.noContext(this, width, height);
 }
@@ -236,14 +235,14 @@ void YGNode::setMeasureFunc(decltype(YGNode::measure_) measureFunc) {
 }
 
 void YGNode::setMeasureFunc(YGMeasureFunc measureFunc) {
-  facebook::yoga::detail::setBooleanData(flags, measureUsesContext_, false);
+  flags_.measureUsesContext = false;
   decltype(YGNode::measure_) m;
   m.noContext = measureFunc;
   setMeasureFunc(m);
 }
 
 YOGA_EXPORT void YGNode::setMeasureFunc(MeasureWithContextFn measureFunc) {
-  facebook::yoga::detail::setBooleanData(flags, measureUsesContext_, true);
+  flags_.measureUsesContext = true;
   decltype(YGNode::measure_) m;
   m.withContext = measureFunc;
   setMeasureFunc(m);
@@ -262,10 +261,10 @@ void YGNode::insertChild(YGNodeRef child, uint32_t index) {
 }
 
 void YGNode::setDirty(bool isDirty) {
-  if (isDirty == facebook::yoga::detail::getBooleanData(flags, isDirty_)) {
+  if (isDirty == flags_.isDirty) {
     return;
   }
-  facebook::yoga::detail::setBooleanData(flags, isDirty_, isDirty);
+  flags_.isDirty = isDirty;
   if (isDirty && dirtied_) {
     dirtied_(this);
   }
@@ -408,9 +407,7 @@ YGValue YGNode::resolveFlexBasisPtr() const {
     return flexBasis;
   }
   if (!style_.flex().isUndefined() && style_.flex().unwrap() > 0.0f) {
-    return facebook::yoga::detail::getBooleanData(flags, useWebDefaults_)
-        ? YGValueAuto
-        : YGValueZero;
+    return flags_.useWebDefaults ? YGValueAuto : YGValueZero;
   }
   return YGValueAuto;
 }
@@ -449,7 +446,7 @@ void YGNode::cloneChildrenIfNeeded(void* cloneContext) {
 }
 
 void YGNode::markDirtyAndPropagate() {
-  if (!facebook::yoga::detail::getBooleanData(flags, isDirty_)) {
+  if (!flags_.isDirty) {
     setDirty(true);
     setLayoutComputedFlexBasis(YGFloatOptional());
     if (owner_) {
@@ -459,7 +456,7 @@ void YGNode::markDirtyAndPropagate() {
 }
 
 void YGNode::markDirtyAndPropagateDownwards() {
-  facebook::yoga::detail::setBooleanData(flags, isDirty_, true);
+  flags_.isDirty = true;
   for_each(children_.begin(), children_.end(), [](YGNodeRef childNode) {
     childNode->markDirtyAndPropagateDownwards();
   });
@@ -486,13 +483,11 @@ float YGNode::resolveFlexShrink() const {
   if (!style_.flexShrink().isUndefined()) {
     return style_.flexShrink().unwrap();
   }
-  if (!facebook::yoga::detail::getBooleanData(flags, useWebDefaults_) &&
-      !style_.flex().isUndefined() && style_.flex().unwrap() < 0.0f) {
+  if (!flags_.useWebDefaults && !style_.flex().isUndefined() &&
+      style_.flex().unwrap() < 0.0f) {
     return -style_.flex().unwrap();
   }
-  return facebook::yoga::detail::getBooleanData(flags, useWebDefaults_)
-      ? kWebDefaultFlexShrink
-      : kDefaultFlexShrink;
+  return flags_.useWebDefaults ? kWebDefaultFlexShrink : kDefaultFlexShrink;
 }
 
 bool YGNode::isNodeFlexible() {
@@ -570,8 +565,7 @@ void YGNode::reset() {
 
   clearChildren();
 
-  auto webDefaults =
-      facebook::yoga::detail::getBooleanData(flags, useWebDefaults_);
+  auto webDefaults = flags_.useWebDefaults;
   *this = YGNode{getConfig()};
   if (webDefaults) {
     useWebDefaults();

yoga/YGNode.h

@@ -11,7 +11,6 @@
 
 #include <cstdint>
 #include <stdio.h>
-#include "BitUtils.h"
 #include "CompactValue.h"
 #include "YGConfig.h"
 #include "YGLayout.h"
@@ -20,6 +19,20 @@
 
 YGConfigRef YGConfigGetDefault();
 
+#pragma pack(push)
+#pragma pack(1)
+struct YGNodeFlags {
+  bool hasNewLayout : 1;
+  bool isReferenceBaseline : 1;
+  bool isDirty : 1;
+  uint8_t nodeType : 1;
+  bool measureUsesContext : 1;
+  bool baselineUsesContext : 1;
+  bool printUsesContext : 1;
+  bool useWebDefaults : 1;
+};
+#pragma pack(pop)
+
 struct YOGA_EXPORT YGNode {
   using MeasureWithContextFn =
       YGSize (*)(YGNode*, float, YGMeasureMode, float, YGMeasureMode, void*);
@@ -27,17 +40,8 @@ struct YOGA_EXPORT YGNode {
   using PrintWithContextFn = void (*)(YGNode*, void*);
 
 private:
-  static constexpr size_t hasNewLayout_ = 0;
-  static constexpr size_t isReferenceBaseline_ = 1;
-  static constexpr size_t isDirty_ = 2;
-  static constexpr size_t nodeType_ = 3;
-  static constexpr size_t measureUsesContext_ = 4;
-  static constexpr size_t baselineUsesContext_ = 5;
-  static constexpr size_t printUsesContext_ = 6;
-  static constexpr size_t useWebDefaults_ = 7;
-
   void* context_ = nullptr;
-  uint8_t flags = 1;
+  YGNodeFlags flags_ = {};
   uint8_t reserved_ = 0;
   union {
     YGMeasureFunc noContext;
@@ -69,7 +73,7 @@ private:
   void setBaselineFunc(decltype(baseline_));
 
   void useWebDefaults() {
-    facebook::yoga::detail::setBooleanData(flags, useWebDefaults_, true);
+    flags_.useWebDefaults = true;
     style_.flexDirection() = YGFlexDirectionRow;
     style_.alignContent() = YGAlignStretch;
   }
@@ -86,6 +90,8 @@ private:
 public:
   YGNode() : YGNode{YGConfigGetDefault()} {}
   explicit YGNode(const YGConfigRef config) : config_{config} {
+    flags_.hasNewLayout = true;
+
     if (config->useWebDefaults) {
       useWebDefaults();
     }
@@ -113,12 +119,10 @@ public:
 
   void print(void*);
 
-  bool getHasNewLayout() const {
-    return facebook::yoga::detail::getBooleanData(flags, hasNewLayout_);
-  }
+  bool getHasNewLayout() const { return flags_.hasNewLayout; }
 
   YGNodeType getNodeType() const {
-    return facebook::yoga::detail::getEnumData<YGNodeType>(flags, nodeType_);
+    return static_cast<YGNodeType>(flags_.nodeType);
   }
 
   bool hasMeasureFunc() const noexcept { return measure_.noContext != nullptr; }
@@ -145,9 +149,7 @@ public:
 
   uint32_t getLineIndex() const { return lineIndex_; }
 
-  bool isReferenceBaseline() {
-    return facebook::yoga::detail::getBooleanData(flags, isReferenceBaseline_);
-  }
+  bool isReferenceBaseline() { return flags_.isReferenceBaseline; }
 
   // returns the YGNodeRef that owns this YGNode. An owner is used to identify
   // the YogaTree that a YGNode belongs to. This method will return the parent
@@ -180,9 +182,7 @@ public:
 
   YGConfigRef getConfig() const { return config_; }
 
-  bool isDirty() const {
-    return facebook::yoga::detail::getBooleanData(flags, isDirty_);
-  }
+  bool isDirty() const { return flags_.isDirty; }
 
   std::array<YGValue, 2> getResolvedDimensions() const {
     return resolvedDimensions_;
@@ -252,21 +252,20 @@ public:
 
   void setPrintFunc(YGPrintFunc printFunc) {
     print_.noContext = printFunc;
-    facebook::yoga::detail::setBooleanData(flags, printUsesContext_, false);
+    flags_.printUsesContext = false;
   }
   void setPrintFunc(PrintWithContextFn printFunc) {
     print_.withContext = printFunc;
-    facebook::yoga::detail::setBooleanData(flags, printUsesContext_, true);
+    flags_.printUsesContext = true;
   }
   void setPrintFunc(std::nullptr_t) { setPrintFunc(YGPrintFunc{nullptr}); }
 
   void setHasNewLayout(bool hasNewLayout) {
-    facebook::yoga::detail::setBooleanData(flags, hasNewLayout_, hasNewLayout);
+    flags_.hasNewLayout = hasNewLayout;
   }
 
   void setNodeType(YGNodeType nodeType) {
-    return facebook::yoga::detail::setEnumData<YGNodeType>(
-        flags, nodeType_, nodeType);
+    flags_.nodeType = static_cast<uint8_t>(nodeType);
   }
 
   void setMeasureFunc(YGMeasureFunc measureFunc);
@@ -276,11 +275,11 @@ public:
   }
 
   void setBaselineFunc(YGBaselineFunc baseLineFunc) {
-    facebook::yoga::detail::setBooleanData(flags, baselineUsesContext_, false);
+    flags_.baselineUsesContext = false;
     baseline_.noContext = baseLineFunc;
   }
   void setBaselineFunc(BaselineWithContextFn baseLineFunc) {
-    facebook::yoga::detail::setBooleanData(flags, baselineUsesContext_, true);
+    flags_.baselineUsesContext = true;
     baseline_.withContext = baseLineFunc;
   }
   void setBaselineFunc(std::nullptr_t) {
@@ -296,8 +295,7 @@ public:
   void setLineIndex(uint32_t lineIndex) { lineIndex_ = lineIndex; }
 
   void setIsReferenceBaseline(bool isReferenceBaseline) {
-    facebook::yoga::detail::setBooleanData(
-        flags, isReferenceBaseline_, isReferenceBaseline);
+    flags_.isReferenceBaseline = isReferenceBaseline;
   }
 
   void setOwner(YGNodeRef owner) { owner_ = owner; }