FED-4215 Low-hanging dart2js code side optimizations #989

greglittlefield-wf · 2025-10-08T18:10:22Z

Motivation

The amount of code generated by the over_react builder is non-negligible, and has some opportunities to be optimized, ultimately reducing the size of compiled dart2js in apps with many components.

Changes

Perform low-hanging optimizations. Note: there are some more potential opportunities for optimization that require more investigation and may involve breakages, which we may revisit later.

Since they affect generated code, changes are easiest to to review commit-by-commit, and the main ones are described below:

4668279
1. Remove specialized $PlainMap and $JsMap generated classes, reducing the number of generated concrete props classes from 3 to 1, which translates to similar reductions in the count of dart2js-compiled class representations
  - Note: this does not include generated mixin classes
  - The $JsMap class was originally included as a potential performance optimization when reading/writing props, but there's no evidence that it's helpful, and it's unlikely to be worth the code size increase
2. Remove workaround for an old DDC bug that required an additional field and constructor body (added in CPLAT-4674: Add workaround for ddc bug via props/state impl constructor #256)
  - This also has the side effect of allowing get$props calls to get inlined, and their results to be reused when reading props
235add1 Move $isClassGenerated check into an assert so it can be compiled out
edd6bc5 Change aria/dom to getters to optimize dart2js output size
This way, they don't get compiled as fields, which emit extra code in each props class's dart2js constructor.
235add1 Move $isClassGenerated check into an assert so it can be compiled out

Effects on build output

This saves ~577 bytes per component (when using -03 --csp --minify), which was calculated by comparing a benchmark component via the benchmark added in #991:

dart run benchmark/dart2js_output.dart compare-code --head='{"git":{"url":"https://github.com/Workiva/over_react.git/","ref":"clean-up-and-optimize-generated-props"}}'

dart2js output changes, obtained by running:

dart run benchmark/dart2js_output.dart compare-code --head='{"git":{"url":"https://github.com/Workiva/over_react.git/","ref":"clean-up-and-optimize-generated-props"}}'

This diff is compares optimized, non-minified dart2js (-03 --csp --no-minify), which has been normalized to allow for better diffing.

Full dart2js diff:

@ -459,3 +459,3 @@
       t#.names = "";
-      if (namedArguments != null && namedArguments.__js_helper$_length !== ###)
+      if (namedArguments != null && namedArguments._length !== ###)
         namedArguments.forEach$###(###, new A.Primitives_functionNoSuchMethod_closure(t#, namedArgumentList, $arguments));
@@ -466,3 +466,3 @@
       if (Array.isArray(positionalArguments))
-        t# = namedArguments == null || namedArguments.__js_helper$_length === ###;
+        t# = namedArguments == null || namedArguments._length === ###;
       else
@@ -510,3 +510,3 @@
       if (t#) {
-        if (namedArguments != null && namedArguments.__js_helper$_length !== ###)
+        if (namedArguments != null && namedArguments._length !== ###)
           return A.Primitives_functionNoSuchMethod($function, $arguments, namedArguments);
@@ -517,3 +517,3 @@
       if (Array.isArray(defaultValues)) {
-        if (namedArguments != null && namedArguments.__js_helper$_length !== ###)
+        if (namedArguments != null && namedArguments._length !== ###)
           return A.Primitives_functionNoSuchMethod($function, $arguments, namedArguments);
@@ -555,3 +555,3 @@
           }
-          if (used !== namedArguments.__js_helper$_length)
+          if (used !== namedArguments._length)
             return A.Primitives_functionNoSuchMethod($function, $arguments, namedArguments);
@@ -1213,3 +1213,3 @@
       var _ = this;
-      _.__js_helper$_length = t#;
+      _._length = t#;
       _._jsObject = t#;
@@ -1288,3 +1288,3 @@
       var _ = this;
-      _.__js_helper$_length = ###;
+      _._length = ###;
       _._last = _._first = _.__js_helper$_rest = _._nums = _._strings = null;
@@ -3266,3 +3266,3 @@
       var _ = this;
-      _.__js_helper$_length = ###;
+      _._length = ###;
       _._last = _._first = _.__js_helper$_rest = _._nums = _._strings = null;
@@ -3276,3 +3276,3 @@
       _._validKey = t#;
-      _.__js_helper$_length = ###;
+      _._length = ###;
       _._last = _._first = _.__js_helper$_rest = _._nums = _._strings = null;
@@ -3672,3 +3672,3 @@
       _._array = t#;
-      _._length = t#;
+      _._html$_length = t#;
       _._position = -###;
@@ -3746,21 +3746,6 @@
     _$ResizeSensor(backingProps) {
-      return backingProps == null ? A._$$ResizeSensorProps$JsMap$(new A.JsBackedMap({})) : A._$$ResizeSensorProps__$$ResizeSensorProps(backingProps);
+      return A._$$ResizeSensorProps$(backingProps);
     },
-    _$$ResizeSensorProps__$$ResizeSensorProps(backingMap) {
-      var t#;
-      if (backingMap instanceof A.JsBackedMap)
-        return A._$$ResizeSensorProps$JsMap$(type$.nullable_JsBackedMap._as(backingMap));
-      else {
-        t# = type$.dynamic;
-        t# = new A._$$ResizeSensorProps$PlainMap(A.LinkedHashMap_LinkedHashMap$_empty(t#, t#), $, $);
-        t#.get$$$isClassGenerated();
-        t#._props = backingMap;
-        return t#;
-      }
-    },
-    _$$ResizeSensorProps$JsMap$(backingMap) {
-      var t# = new A._$$ResizeSensorProps$JsMap(new A.JsBackedMap({}), $, $);
-      t#.get$$$isClassGenerated();
-      t#._props = backingMap == null ? new A.JsBackedMap({}) : backingMap;
-      return t#;
+    _$$ResizeSensorProps$(backingMap) {
+      return new A._$$ResizeSensorProps(backingMap == null ? new A.JsBackedMap({}) : backingMap);
     },
@@ -3776,18 +3761,7 @@
     _$ResizeSensorPropsAccessorsMixin: function _$ResizeSensorPropsAccessorsMixin() {},
-    _$$ResizeSensorProps: function _$$ResizeSensorProps() {},
-    _$$ResizeSensorProps_$getPropKey_closure: function _$$ResizeSensorProps_$getPropKey_closure() {},
-    _$$ResizeSensorProps$PlainMap: function _$$ResizeSensorProps$PlainMap(t#, t#, t#) {
-      var _ = this;
-      _._props = t#;
-      _.componentFactory = null;
-      _.UbiquitousDomPropsMixin___UbiquitousDomPropsMixin_aria_FI = t#;
-      _.UbiquitousDomPropsMixin___UbiquitousDomPropsMixin_dom_FI = t#;
-    },
-    _$$ResizeSensorProps$JsMap: function _$$ResizeSensorProps$JsMap(t#, t#, t#) {
-      var _ = this;
-      _._props = t#;
-      _.componentFactory = null;
-      _.UbiquitousDomPropsMixin___UbiquitousDomPropsMixin_aria_FI = t#;
-      _.UbiquitousDomPropsMixin___UbiquitousDomPropsMixin_dom_FI = t#;
+    _$$ResizeSensorProps: function _$$ResizeSensorProps(t#) {
+      this.props = t#;
+      this.componentFactory = null;
     },
+    _$$ResizeSensorProps_$getPropKey_closure: function _$$ResizeSensorProps_$getPropKey_closure() {},
     _$ResizeSensorComponent: function _$ResizeSensorComponent(t#, t#, t#, t#) {
@@ -3808,13 +3782,8 @@
     DomProps$(componentFactory, props) {
-      var t# = new A.DomProps(componentFactory, props == null ? new A.JsBackedMap({}) : props, $, $);
-      t#.get$$$isClassGenerated();
-      return t#;
+      return new A.DomProps(componentFactory, props == null ? new A.JsBackedMap({}) : props);
     },
-    DomProps: function DomProps(t#, t#, t#, t#) {
-      var _ = this;
-      _.DomProps_componentFactory = t#;
-      _.props = t#;
-      _.componentFactory = null;
-      _.UbiquitousDomPropsMixin___UbiquitousDomPropsMixin_aria_FI = t#;
-      _.UbiquitousDomPropsMixin___UbiquitousDomPropsMixin_dom_FI = t#;
+    DomProps: function DomProps(t#, t#) {
+      this.DomProps_componentFactory = t#;
+      this.props = t#;
+      this.componentFactory = null;
     },
@@ -3873,3 +3842,3 @@
       t# = consumedProps;
-      A.forwardUnconsumedPropsV2(_this.get$props(_this), new A.MappedListIterable(t#, new A.PropsToForward__propsToForward_closure(), A.instanceType(t#)._eval$###("MappedListIterable<###,List<String>>")), false, propsToUpdate);
+      A.forwardUnconsumedPropsV2(_this.props, new A.MappedListIterable(t#, new A.PropsToForward__propsToForward_closure(), A.instanceType(t#)._eval$###("MappedListIterable<###,List<String>>")), false, propsToUpdate);
       return propsToUpdate;
@@ -3969,8 +3938,5 @@
     },
-    GenericUiProps: function GenericUiProps(t#, t#, t#) {
-      var _ = this;
-      _.props = t#;
-      _.componentFactory = null;
-      _.UbiquitousDomPropsMixin___UbiquitousDomPropsMixin_aria_FI = t#;
-      _.UbiquitousDomPropsMixin___UbiquitousDomPropsMixin_dom_FI = t#;
+    GenericUiProps: function GenericUiProps(t#) {
+      this.props = t#;
+      this.componentFactory = null;
     },
@@ -4695,3 +4661,3 @@
     main() {
-      var t#,
+      var t#, t#,
         t# = A.DomProps$($.$get$div(), null);
@@ -4702,27 +4668,13 @@
       t# = $.$get$Foo0().call$###();
-      t# = J.getInterceptor$x(t#);
-      J.$indexSet$ax(t#.get$props(t#), "Foo0Props.foo0", "");
-      J.$indexSet$ax(t#.get$props(t#), "Foo0Props.foo1", "");
-      J.$indexSet$ax(t#.get$props(t#), "Foo0Props.foo2", "");
-      J.$indexSet$ax(t#.get$props(t#), "Foo0Props.foo3", "");
-      J.$indexSet$ax(t#.get$props(t#), "Foo0Props.foo4", "");
+      t# = t#.props;
+      t# = J.getInterceptor$ax(t#);
+      t#.$indexSet(t#, "Foo0Props.foo0", "");
+      t#.$indexSet(t#, "Foo0Props.foo1", "");
+      t#.$indexSet(t#, "Foo0Props.foo2", "");
+      t#.$indexSet(t#, "Foo0Props.foo3", "");
+      t#.$indexSet(t#, "Foo0Props.foo4", "");
       t#.call$###();
     },
-    _$$Foo0Props__$$Foo0Props(backingMap) {
-      var t#;
-      if (backingMap instanceof A.JsBackedMap)
-        return A._$$Foo0Props$JsMap$(type$.nullable_JsBackedMap._as(backingMap));
-      else {
-        t# = type$.dynamic;
-        t# = new A._$$Foo0Props$PlainMap(A.LinkedHashMap_LinkedHashMap$_empty(t#, t#), $, $, $, $, $, $, $);
-        t#.get$$$isClassGenerated();
-        t#._main$_props = backingMap;
-        return t#;
-      }
-    },
-    _$$Foo0Props$JsMap$(backingMap) {
-      var t# = new A._$$Foo0Props$JsMap(new A.JsBackedMap({}), $, $, $, $, $, $, $);
-      t#.get$$$isClassGenerated();
-      t#._main$_props = backingMap == null ? new A.JsBackedMap({}) : backingMap;
-      return t#;
+    _$$Foo0Props$(backingMap) {
+      return new A._$$Foo0Props(backingMap, $, $, $, $, $);
     },
@@ -4734,18 +4686,5 @@
     _$Foo0Config_closure0: function _$Foo0Config_closure0() {},
-    _$$Foo0Props: function _$$Foo0Props() {},
-    _$$Foo0Props$PlainMap: function _$$Foo0Props$PlainMap(t#, t#, t#, t#, t#, t#, t#, t#) {
+    _$$Foo0Props: function _$$Foo0Props(t#, t#, t#, t#, t#, t#) {
       var _ = this;
-      _._main$_props = t#;
-      _.Foo0Props___Foo0Props_foo0_A = t#;
-      _.Foo0Props___Foo0Props_foo1_A = t#;
-      _.Foo0Props___Foo0Props_foo2_A = t#;
-      _.Foo0Props___Foo0Props_foo3_A = t#;
-      _.Foo0Props___Foo0Props_foo4_A = t#;
-      _.componentFactory = null;
-      _.UbiquitousDomPropsMixin___UbiquitousDomPropsMixin_aria_FI = t#;
-      _.UbiquitousDomPropsMixin___UbiquitousDomPropsMixin_dom_FI = t#;
-    },
-    _$$Foo0Props$JsMap: function _$$Foo0Props$JsMap(t#, t#, t#, t#, t#, t#, t#, t#) {
-      var _ = this;
-      _._main$_props = t#;
+      _.props = t#;
       _.Foo0Props___Foo0Props_foo0_A = t#;
@@ -4756,4 +4695,2 @@
       _.componentFactory = null;
-      _.UbiquitousDomPropsMixin___UbiquitousDomPropsMixin_aria_FI = t#;
-      _.UbiquitousDomPropsMixin___UbiquitousDomPropsMixin_dom_FI = t#;
     },
@@ -4858,4 +4795,4 @@
     forwardUnconsumedProps(props, keySetsToOmit, onlyCopyDomProps, propsToUpdate) {
-      var t#, key, t#;
-      for (t# = props.get$props(props), t# = J.get$iterator$ax(t#.get$keys(t#)); t#.moveNext$###();) {
+      var t#, t#, t#, key, t#;
+      for (t# = props.props, t# = J.getInterceptor$x(t#), t# = J.get$iterator$ax(t#.get$keys(t#)); t#.moveNext$###();) {
         key = t#.get$current(t#);
@@ -4866,3 +4803,3 @@
         if (t# || $.$get$_validDomProps().contains$###(###, key)) {
-          t# = props.get$props(props).$index(###, key);
+          t# = t#.$index(t#, key);
           J.$indexSet$ax(propsToUpdate.get$props(propsToUpdate), key, t#);
@@ -6035,3 +5972,3 @@
     get$length(_) {
-      return this.__js_helper$_length;
+      return this._length;
     },
@@ -6114,3 +6051,3 @@
     get$length(_) {
-      return this._getMap$###().__js_helper$_length;
+      return this._getMap$###()._length;
     }
@@ -6299,6 +6236,6 @@
     get$length(_) {
-      return this.__js_helper$_length;
+      return this._length;
     },
     get$isEmpty(_) {
-      return this.__js_helper$_length === ###;
+      return this._length === ###;
     },
@@ -6428,3 +6365,3 @@
         _this._last = _this._last._next = cell;
-      ++_this.__js_helper$_length;
+      ++_this._length;
       _this._modifications = _this._modifications + ### & ###;
@@ -6476,6 +6413,6 @@
     get$length(_) {
-      return this._map.__js_helper$_length;
+      return this._map._length;
     },
     get$isEmpty(_) {
-      return this._map.__js_helper$_length === ###;
+      return this._map._length === ###;
     },
@@ -8920,3 +8857,3 @@
         nextPosition = _this._position + ###,
-        t# = _this._length;
+        t# = _this._html$_length;
       if (nextPosition < t#) {
@@ -9265,3 +9202,3 @@
     get$defaultProps(_) {
-      var t# = A._$$ResizeSensorProps$JsMap$(new A.JsBackedMap({}));
+      var t# = A._$$ResizeSensorProps$(new A.JsBackedMap({}));
       t#.addProps$###($.$get$ResizeSensorPropsMixin_defaultProps());
@@ -9280,3 +9217,3 @@
       t# === $ && A.throwUnnamedLateFieldNI();
-      t# = t#.get$props(t#).$index(###, "ResizeSensorPropsMixin.quickMount");
+      t# = J.$index$asx(t#.props, "ResizeSensorPropsMixin.quickMount");
       t# = A._asBoolQ(t# == null ? null : t#);
@@ -9323,4 +9260,3 @@
       resizeSensor = t#.call$###(expandSensor, collapseSensor);
-      t# = _this.___$ResizeSensorComponent__cachedTypedProps_A;
-      t# = t#.get$props(t#).$index(###, "ResizeSensorPropsMixin.isFlexChild");
+      t# = J.$index$asx(_this.___$ResizeSensorComponent__cachedTypedProps_A.props, "ResizeSensorPropsMixin.isFlexChild");
       t# = A._asBoolQ(t# == null ? _null : t#);
@@ -9330,4 +9266,3 @@
       else {
-        t# = _this.___$ResizeSensorComponent__cachedTypedProps_A;
-        t# = t#.get$props(t#).$index(###, "ResizeSensorPropsMixin.isFlexContainer");
+        t# = J.$index$asx(_this.___$ResizeSensorComponent__cachedTypedProps_A.props, "ResizeSensorPropsMixin.isFlexContainer");
         t# = A._asBoolQ(t# == null ? _null : t#);
@@ -9396,3 +9331,3 @@
       t# === $ && A.throwUnnamedLateFieldNI();
-      t# = t#.get$props(t#).$index(###, "ResizeSensorPropsMixin.onDidReset");
+      t# = J.$index$asx(t#.props, "ResizeSensorPropsMixin.onDidReset");
       if (t# == null)
@@ -9446,5 +9381,2 @@
   A._$$ResizeSensorProps.prototype = {
-    get$$$isClassGenerated() {
-      return true;
-    },
     get$componentFactory() {
@@ -9456,3 +9388,6 @@
     },
-    $isResizeSensorProps: ###
+    $isResizeSensorProps: ###,
+    get$props(receiver) {
+      return this.props;
+    }
   };
@@ -9460,3 +9395,3 @@
     call$###(map) {
-      return A._$$ResizeSensorProps__$$ResizeSensorProps(map);
+      return A._$$ResizeSensorProps$(map);
     },
@@ -9464,12 +9399,2 @@
   };
-  A._$$ResizeSensorProps$PlainMap.prototype = {
-    get$props(_) {
-      return this._props;
-    }
-  };
-  A._$$ResizeSensorProps$JsMap.prototype = {
-    get$props(_) {
-      return this._props;
-    }
-  };
   A._$ResizeSensorComponent.prototype = {
@@ -9477,3 +9402,3 @@
       this.super$Component2$props(###, value);
-      this.___$ResizeSensorComponent__cachedTypedProps_A = A._$$ResizeSensorProps$JsMap$(A.getBackingMap(value));
+      this.___$ResizeSensorComponent__cachedTypedProps_A = A._$$ResizeSensorProps$(A.getBackingMap(value));
     },
@@ -9512,5 +9437,2 @@
   A.DomProps.prototype = {
-    get$$$isClassGenerated() {
-      return true;
-    },
     get$componentFactory() {
@@ -9778,4 +9700,3 @@
     call$###(backingMap) {
-      var t# = new A.GenericUiProps(backingMap == null ? new A.JsBackedMap({}) : backingMap, $, $);
-      t#.get$$$isClassGenerated();
+      var t# = new A.GenericUiProps(backingMap == null ? new A.JsBackedMap({}) : backingMap);
       t#.componentFactory = this.factory;
@@ -9818,5 +9739,2 @@
   A.GenericUiProps.prototype = {
-    get$$$isClassGenerated() {
-      return true;
-    },
     get$props(receiver) {
@@ -10410,12 +10328,14 @@
     call$###(props) {
-      var t#, t#, t#, t#, _null = null,
-        t# = J.$index$asx(props.get$props(props), "Foo0Props.foo0");
+      var t#, t#, t#, _null = null,
+        t# = props.props,
+        t# = J.getInterceptor$asx(t#),
+        t# = t#.$index(t#, "Foo0Props.foo0");
       t# = A._asString(t# == null ? _null : t#);
-      t# = J.$index$asx(props.get$props(props), "Foo0Props.foo1");
+      t# = t#.$index(t#, "Foo0Props.foo1");
       t# = A._asString(t# == null ? _null : t#);
-      t# = J.$index$asx(props.get$props(props), "Foo0Props.foo2");
+      t# = t#.$index(t#, "Foo0Props.foo2");
       t# = A._asString(t# == null ? _null : t#);
-      t# = J.$index$asx(props.get$props(props), "Foo0Props.foo3");
+      t# = t#.$index(t#, "Foo0Props.foo3");
       t# = A._asString(t# == null ? _null : t#);
-      t# = J.$index$asx(props.get$props(props), "Foo0Props.foo4");
+      t# = t#.$index(t#, "Foo0Props.foo4");
       A.print(A._setArrayType([t#, t#, t#, t#, A._asString(t# == null ? _null : t#)], type$.JSArray_String));
@@ -10431,3 +10351,3 @@
     call$###(p) {
-      var t# = J.$index$asx(p.get$props(p), "id");
+      var t# = J.$index$asx(p.props, "id");
       return A._asStringQ(t# == null ? null : t#);
@@ -10439,3 +10359,3 @@
     call$###(map) {
-      return A._$$Foo0Props__$$Foo0Props(map);
+      return A._$$Foo0Props$(map);
     },
@@ -10445,3 +10365,3 @@
     call$###(map) {
-      return A._$$Foo0Props$JsMap$(map);
+      return A._$$Foo0Props$(map);
     },
@@ -10450,14 +10370,4 @@
   A._$$Foo0Props.prototype = {
-    get$$$isClassGenerated() {
-      return true;
-    }
-  };
-  A._$$Foo0Props$PlainMap.prototype = {
-    get$props(_) {
-      return this._main$_props;
-    }
-  };
-  A._$$Foo0Props$JsMap.prototype = {
-    get$props(_) {
-      return this._main$_props;
+    get$props(receiver) {
+      return this.props;
     }
@@ -11053,6 +10963,2 @@
     _inherit(A._$$ResizeSensorProps, A.__$$ResizeSensorProps__$ResizeSensorProps__$ResizeSensorPropsAccessorsMixin);
-    _inheritMany(A._$$ResizeSensorProps,
-      [A._$$ResizeSensorProps$PlainMap,
-      A._$$ResizeSensorProps$JsMap,
-    ]);
     _inherit(A._$ResizeSensorComponent, A.ResizeSensorComponent);
@@ -11094,6 +11000,2 @@
     _inherit(A._$$Foo0Props, A.__$$Foo0Props_UiProps_Foo0Props_$Foo0Props);
-    _inheritMany(A._$$Foo0Props,
-      [A._$$Foo0Props$PlainMap,
-      A._$$Foo0Props$JsMap,
-    ]);
     _mixin(A._NativeTypedArrayOfDouble_NativeTypedArray_ListMixin, A.ListMixin);
@@ -11216,3 +11118,3 @@
   "Version(NavigatorProvider{namePrefix:String})",
-  "_$$Foo0Props$JsMap(JsBackedMap)",
+  "_$$Foo0Props(JsBackedMap)",
   "_$$Foo0Props(Map<@,@>)",
@@ -12265,26 +12167,2 @@
  "_$$Foo0Props": {
-  "Foo0Props": [],
-  "Map": [
-   "@",
-   "@"
-  ],
-  "MapMixin": [
-   "@",
-   "@"
-  ]
- },
- "_$$Foo0Props$JsMap": {
-  "Foo0Props": [],
-  "Map": [
-   "@",
-   "@"
-  ],
-  "MapMixin": [
-   "@",
-   "@"
-  ],
-  "MapMixin.K": "@",
-  "MapMixin.V": "@"
- },
- "_$$Foo0Props$PlainMap": {
   "Foo0Props": [],
@@ -12302,26 +12180,2 @@
  "_$$ResizeSensorProps": {
-  "Map": [
-   "@",
-   "@"
-  ],
-  "MapMixin": [
-   "@",
-   "@"
-  ],
-  "ResizeSensorProps": []
- },
- "_$$ResizeSensorProps$JsMap": {
-  "Map": [
-   "@",
-   "@"
-  ],
-  "MapMixin": [
-   "@",
-   "@"
-  ],
-  "MapMixin.K": "@",
-  "MapMixin.V": "@",
-  "ResizeSensorProps": []
- },
- "_$$ResizeSensorProps$PlainMap": {
   "Map": [
@@ -12692,3 +12546,2 @@
       nullable_Future_Null: findType("Future<Null>?"),
-      nullable_JsBackedMap: findType("JsBackedMap?"),
       nullable_Object: findType("Object?"),
@@ -13044,6 +12897,6 @@
   };
-  Function.prototype.call$###$### = function(a) {
+  Function.prototype.call$### = function(a) {
     return this(a);
   };
-  Function.prototype.call$### = function(a) {
+  Function.prototype.call$###$### = function(a) {
     return this(a);

Release Notes

Review

See CONTRIBUTING.md for more details on review types (+1 / QA +1 / +10) and code review process.

Please review:

QA Checklist

Tests were updated and provide good coverage of the changeset and other affected code
Manual testing was performed if needed
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The JsBackedMap specialized subclass was implemented to potentially improve performance by allowing dart2js to inline/optimize backing map operations, but from inspecting compiled code, it doesn't seem to have much of an effect. These two specialized subclasses result in a significant amount of extra compiled code, so removing it at this time is worth the tradeoff. This commit also removes workarounds for an old DDC bug.

This way, they don't get compiled as fields, which emit extra code in each props class's constructor. In the future, if we wanted to reuse these objects for successive calls in builders, we could use an expando instead.

kealjones-wk

one comment for posterity

kealjones-wk · 2025-12-08T21:14:36Z

lib/src/component/error_boundary.over_react.g.dart

+  _$$ErrorBoundaryState typedStateFactoryJs(JsBackedMap? backingMap) =>
+      _$$ErrorBoundaryState(backingMap);

  @override
  _$$ErrorBoundaryState typedStateFactory(Map? backingMap) =>


For posterity sake:

The only thing that stuck out to me was another possible optimization maybe? typed[State|Props]Factory and typed[State|Props]FactoryJs are identical implementations.

After talking with greg in person about this he validated that the generated JS code does in fact double generate this in js as well, we were hoping it might optimize it out but no luck. However @greglittlefield-wf believes he might be able to do something to remove the need for both.

All other changes seem really good and very beneficial. I am still reviewing a bit more but so far looking good.

Another thought came to mind when reviewing the generated JS thats semi related to the above.

return A.UiFactoryConfig$("Foo2", A.PropsFactory$(new A._$Foo2Config_closure(), new A._$Foo2Config_closure0(), t#), t#);

Because tyepedPropsFactory is used within PropsFactory (used twice, once for map and once for jsMap) another possible gain could be making the jsMap argument optional allowing us to remove the second instantiation of the same props class.

@greglittlefield-wf if this comment and the one above are actually a big lift. these should not hold up this PR. This is good work already as is so we could add these to another follow up PR.

Ooh good ideas! I took a look and these won't be too bad, but will be non-trivial to implement, so I'll make a ticket to follow up

kealjones-wk

+1
Generation changes look good and dart2js generation looks good. Waiting on wdesk branch using these changes CI to pass for QA.

…ze-generated-props

Not sure what was going on here, but "ddc" was definitely correct This reverts commit 5d2d820.

kealjones-wk

+10

greglittlefield-wf · 2025-12-09T18:06:25Z

@Workiva/release-management-p

rmconsole-wf

+1 from RM

greglittlefield-wf added 5 commits August 16, 2025 09:19

Update generated code

a941e6b

Move $isClassGenerated check into an assert so it can be compiled out

235add1

Update tests

bfd43e8

Change aria/dom to getters to optimize dart2js output size

edd6bc5

This way, they don't get compiled as fields, which emit extra code in each props class's constructor. In the future, if we wanted to reuse these objects for successive calls in builders, we could use an expando instead.

btr-rmconsole-2 bot added the Merge Requirements Unmet label Oct 8, 2025

greglittlefield-wf added 5 commits December 2, 2025 16:57

Format

2e546c4

Fix builder tests to expect new output

3004cc2

Add changelog entry

3273bf3

Fix typo in condition resulting in check always getting skipped

da3d7ad

Fix nonexistent test tag

5d2d820

btr-rmconsole-5 bot added the Merge Conflicts label Dec 3, 2025

greglittlefield-wf changed the title ~~Optimize generated code size~~ FED-4215 Low-hanging dart2js code side optimizations Dec 3, 2025

greglittlefield-wf marked this pull request as ready for review December 3, 2025 19:28

greglittlefield-wf requested a review from kealjones-wk December 3, 2025 19:28

kealjones-wk reviewed Dec 8, 2025

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kealjones-wk previously approved these changes Dec 8, 2025

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greglittlefield-wf dismissed kealjones-wk’s stale review via 66c17c0 December 8, 2025 22:04

Merge remote-tracking branch 'origin/master' into clean-up-and-optimi…

de8bcce

…ze-generated-props

greglittlefield-wf force-pushed the clean-up-and-optimize-generated-props branch from 66c17c0 to de8bcce Compare December 8, 2025 22:22

btr-rmconsole-3 bot removed the Merge Conflicts label Dec 8, 2025

greglittlefield-wf added 4 commits December 8, 2025 15:25

Update gold files

1bd6c52

Revert "Fix nonexistent test tag"

e28443f

Not sure what was going on here, but "ddc" was definitely correct This reverts commit 5d2d820.

Remove tests that getters always returns same instance

5b16ccf

Fix wrong arg used for DDC-only tests

57c6845

greglittlefield-wf requested a review from kealjones-wk December 8, 2025 23:01

kealjones-wk approved these changes Dec 9, 2025

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btr-rmconsole-2 bot added Merge Requirements Met and removed Merge Requirements Unmet labels Dec 9, 2025

btr-rmconsole-1 bot added the RM Ready label Dec 9, 2025

rmconsole-wf approved these changes Dec 9, 2025

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btr-rmconsole-1 bot merged commit 57004a7 into master Dec 9, 2025
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btr-rmconsole-1 bot deleted the clean-up-and-optimize-generated-props branch December 9, 2025 18:06

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