refactor(ivy): move all of the instruction state into a singe object (#33093)

Turns out that writing to global state is more expensive than writing to
a property on an object.

Slower:
````
let count = 0;

function increment() {
  count++;
}
```

Faster:
````
const state = {
  count: 0
};

function increment() {
  state.count++;
}
```

This change moves all of the instruction state into a single state object.

`noop_change_detection` benchmark
Pre refactoring: 16.7 us
Post refactoring: 14.523 us (-13.3%)

PR Close #33093

integration/_payload-limits.json

@@ -12,7 +12,7 @@
     "master": {
       "uncompressed": {
         "runtime": 1440,
-        "main": 13415,
+        "main": 14228,
         "polyfills": 45340
       }
     }
@@ -21,7 +21,7 @@
     "master": {
       "uncompressed": {
         "runtime": 1440,
-        "main": 123904,
+        "main": 125674,
         "polyfills": 45340
       }
     }

packages/core/src/render3/instructions/styling.ts

@@ -184,7 +184,7 @@ function stylingProp(
       // it's important we remove the current style sanitizer once the
       // element exits, otherwise it will be used by the next styling
       // instructions for the next element.
-      setElementExitFn(resetCurrentStyleSanitizer);
+      setElementExitFn(stylingApply);
     }
   } else {
     // Context Resolution (or first update) Case: save the value
@@ -354,7 +354,7 @@ function _stylingMap(
       // it's important we remove the current style sanitizer once the
       // element exits, otherwise it will be used by the next styling
       // instructions for the next element.
-      setElementExitFn(resetCurrentStyleSanitizer);
+      setElementExitFn(stylingApply);
     }
   } else {
     updated = valueHasChanged;

packages/core/src/render3/state.ts

@@ -7,48 +7,77 @@
  */
 
 import {StyleSanitizeFn} from '../sanitization/style_sanitizer';
-import {assertDefined} from '../util/assert';
+import {assertDefined, assertEqual} from '../util/assert';
 
 import {assertLViewOrUndefined} from './assert';
 import {ComponentDef, DirectiveDef} from './interfaces/definition';
 import {TElementNode, TNode, TViewNode} from './interfaces/node';
 import {CONTEXT, DECLARATION_VIEW, LView, OpaqueViewState} from './interfaces/view';
 
-
 /**
- * Store the element depth count. This is used to identify the root elements of the template
- * so that we can than attach `LView` to only those elements.
+ * All implicit instruction state is stored here.
+ *
+ * It is useful to have a single object where all of the state is stored as a mental model
+ * (rather it being spread across many different variables.)
+ *
+ * PERF NOTE: Turns out that writing to a true global variable is slower than
+ * having an intermediate object with properties.
  */
-let elementDepthCount !: number;
+interface InstructionState {
+  /**
+   * State of the current view being processed.
+   *
+   * An array of nodes (text, element, container, etc), pipes, their bindings, and
+   * any local variables that need to be stored between invocations.
+   */
+  lView: LView;
 
-export function getElementDepthCount() {
-  // top level variables should not be exported for performance reasons (PERF_NOTES.md)
-  return elementDepthCount;
-}
+  /**
+   * Used to set the parent property when nodes are created and track query results.
+   *
+   * This is used in conjection with `isParent`.
+   */
+  previousOrParentTNode: TNode;
 
-export function increaseElementDepthCount() {
-  elementDepthCount++;
-}
+  /**
+   * If `isParent` is:
+   *  - `true`: then `previousOrParentTNode` points to a parent node.
+   *  - `false`: then `previousOrParentTNode` points to previous node (sibling).
+   */
+  isParent: boolean;
 
-export function decreaseElementDepthCount() {
-  elementDepthCount--;
-}
+  /**
+   * Index of currently selected element in LView.
+   *
+   * Used by binding instructions. Updated as part of advance instruction.
+   */
+  selectedIndex: number;
 
-let currentDirectiveDef: DirectiveDef<any>|ComponentDef<any>|null = null;
+  /**
+   * The last viewData retrieved by nextContext().
+   * Allows building nextContext() and reference() calls.
+   *
+   * e.g. const inner = x().$implicit; const outer = x().$implicit;
+   */
+  contextLView: LView;
 
-export function getCurrentDirectiveDef(): DirectiveDef<any>|ComponentDef<any>|null {
-  // top level variables should not be exported for performance reasons (PERF_NOTES.md)
-  return currentDirectiveDef;
-}
+  /**
+   * In this mode, any changes in bindings will throw an ExpressionChangedAfterChecked error.
+   *
+   * Necessary to support ChangeDetectorRef.checkNoChanges().
+   */
+  checkNoChangesMode: boolean;
 
-export function setCurrentDirectiveDef(def: DirectiveDef<any>| ComponentDef<any>| null): void {
-  currentDirectiveDef = def;
-}
+  /**
+   * Store the element depth count. This is used to identify the root elements of the template
+   * so that we can then attach `LView` to only those elements.
+   */
+  elementDepthCount: number;
 
-/**
+  /**
    * Stores whether directives should be matched to elements.
    *
- * When template contains `ngNonBindable` than we need to prevent the runtime form matching
+   * When template contains `ngNonBindable` then we need to prevent the runtime form matching
    * directives on children of that element.
    *
    * Example:
@@ -63,11 +92,100 @@ export function setCurrentDirectiveDef(def: DirectiveDef<any>| ComponentDef<any>
    * </div>
    * ```
    */
-let bindingsEnabled !: boolean;
+  bindingsEnabled: boolean;
+
+  /**
+   * Current namespace to be used when creating elements
+   */
+  currentNamespace: string|null;
+
+  /**
+   * Current sanitizer
+   */
+  currentSanitizer: StyleSanitizeFn|null;
+
+
+  /**
+   * Used when processing host bindings.
+   */
+  currentDirectiveDef: DirectiveDef<any>|ComponentDef<any>|null;
+
+  /**
+   * Used as the starting directive id value.
+   *
+   * All subsequent directives are incremented from this value onwards.
+   * The reason why this value is `1` instead of `0` is because the `0`
+   * value is reserved for the template.
+   */
+  activeDirectiveId: number;
+
+  /**
+   * The root index from which pure function instructions should calculate their binding
+   * indices. In component views, this is TView.bindingStartIndex. In a host binding
+   * context, this is the TView.expandoStartIndex + any dirs/hostVars before the given dir.
+   */
+  bindingRootIndex: number;
+
+  /**
+   * Current index of a View or Content Query which needs to be processed next.
+   * We iterate over the list of Queries and increment current query index at every step.
+   */
+  currentQueryIndex: number;
+
+
+  /**
+   * Function to be called when the element is exited.
+   *
+   * NOTE: The function is here for tree shakable purposes since it is only needed by styling.
+   */
+  elementExitFn: (() => void)|null;
+}
+
+export const instructionState: InstructionState = {
+  previousOrParentTNode: null !,
+  isParent: null !,
+  lView: null !,
+  // tslint:disable-next-line: no-toplevel-property-access
+  selectedIndex: -1 << ActiveElementFlags.Size,
+  contextLView: null !,
+  checkNoChangesMode: false,
+  elementDepthCount: 0,
+  bindingsEnabled: true,
+  currentNamespace: null,
+  currentSanitizer: null,
+  currentDirectiveDef: null,
+  activeDirectiveId: 0,
+  bindingRootIndex: -1,
+  currentQueryIndex: 0,
+  elementExitFn: null,
+};
+
+
+export function getElementDepthCount() {
+  // top level variables should not be exported for performance reasons (PERF_NOTES.md)
+  return instructionState.elementDepthCount;
+}
+
+export function increaseElementDepthCount() {
+  instructionState.elementDepthCount++;
+}
+
+export function decreaseElementDepthCount() {
+  instructionState.elementDepthCount--;
+}
+
+export function getCurrentDirectiveDef(): DirectiveDef<any>|ComponentDef<any>|null {
+  // top level variables should not be exported for performance reasons (PERF_NOTES.md)
+  return instructionState.currentDirectiveDef;
+}
+
+export function setCurrentDirectiveDef(def: DirectiveDef<any>| ComponentDef<any>| null): void {
+  instructionState.currentDirectiveDef = def;
+}
 
 export function getBindingsEnabled(): boolean {
   // top level variables should not be exported for performance reasons (PERF_NOTES.md)
-  return bindingsEnabled;
+  return instructionState.bindingsEnabled;
 }
 
 
@@ -91,7 +209,7 @@ export function getBindingsEnabled(): boolean {
  * @codeGenApi
  */
 export function ɵɵenableBindings(): void {
-  bindingsEnabled = true;
+  instructionState.bindingsEnabled = true;
 }
 
 /**
@@ -114,22 +232,13 @@ export function ɵɵenableBindings(): void {
  * @codeGenApi
  */
 export function ɵɵdisableBindings(): void {
-  bindingsEnabled = false;
+  instructionState.bindingsEnabled = false;
 }
 
 export function getLView(): LView {
-  return lView;
+  return instructionState.lView;
 }
 
-/**
- * Used as the starting directive id value.
- *
- * All subsequent directives are incremented from this value onwards.
- * The reason why this value is `1` instead of `0` is because the `0`
- * value is reserved for the template.
- */
-let activeDirectiveId = 0;
-
 /**
  * Flags used for an active element during change detection.
  *
@@ -150,14 +259,14 @@ export const enum ActiveElementFlags {
  * Determines whether or not a flag is currently set for the active element.
  */
 export function hasActiveElementFlag(flag: ActiveElementFlags) {
-  return (_selectedIndex & flag) === flag;
+  return (instructionState.selectedIndex & flag) === flag;
 }
 
 /**
  * Sets a flag is for the active element.
  */
 export function setActiveElementFlag(flag: ActiveElementFlags) {
-  _selectedIndex |= flag;
+  instructionState.selectedIndex |= flag;
 }
 
 /**
@@ -173,16 +282,15 @@ export function setActiveHostElement(elementIndex: number | null = null) {
       executeElementExitFn();
     }
     setSelectedIndex(elementIndex === null ? -1 : elementIndex);
-    activeDirectiveId = 0;
+    instructionState.activeDirectiveId = 0;
   }
 }
 
-let _elementExitFn: Function|null = null;
 export function executeElementExitFn() {
-  _elementExitFn !();
+  instructionState.elementExitFn !();
   // TODO (matsko|misko): remove this unassignment once the state management of
   //                      global variables are better managed.
-  _selectedIndex &= ~ActiveElementFlags.RunExitFn;
+  instructionState.selectedIndex &= ~ActiveElementFlags.RunExitFn;
 }
 
 /**
@@ -198,9 +306,13 @@ export function executeElementExitFn() {
  *
  * @param fn
  */
-export function setElementExitFn(fn: Function): void {
+export function setElementExitFn(fn: () => void): void {
   setActiveElementFlag(ActiveElementFlags.RunExitFn);
-  _elementExitFn = fn;
+  if (instructionState.elementExitFn == null) {
+    instructionState.elementExitFn = fn;
+  }
+  ngDevMode &&
+      assertEqual(instructionState.elementExitFn, fn, 'Expecting to always get the same function');
 }
 
 /**
@@ -219,7 +331,7 @@ export function setElementExitFn(fn: Function): void {
  * different set of directives).
  */
 export function getActiveDirectiveId() {
-  return activeDirectiveId;
+  return instructionState.activeDirectiveId;
 }
 
 /**
@@ -248,7 +360,7 @@ export function incrementActiveDirectiveId() {
   // directive uniqueId is not set anywhere--it is just incremented between
   // each hostBindings call and is useful for helping instruction code
   // uniquely determine which directive is currently active when executed.
-  activeDirectiveId += 1;
+  instructionState.activeDirectiveId += 1;
 }
 
 /**
@@ -263,113 +375,67 @@ export function incrementActiveDirectiveId() {
  * @codeGenApi
  */
 export function ɵɵrestoreView(viewToRestore: OpaqueViewState) {
-  contextLView = viewToRestore as any as LView;
+  instructionState.contextLView = viewToRestore as any as LView;
 }
 
-/** Used to set the parent property when nodes are created and track query results. */
-let previousOrParentTNode: TNode;
-
 export function getPreviousOrParentTNode(): TNode {
   // top level variables should not be exported for performance reasons (PERF_NOTES.md)
-  return previousOrParentTNode;
+  return instructionState.previousOrParentTNode;
 }
 
 export function setPreviousOrParentTNode(tNode: TNode, _isParent: boolean) {
-  previousOrParentTNode = tNode;
-  isParent = _isParent;
+  instructionState.previousOrParentTNode = tNode;
+  instructionState.isParent = _isParent;
 }
 
 export function setTNodeAndViewData(tNode: TNode, view: LView) {
   ngDevMode && assertLViewOrUndefined(view);
-  previousOrParentTNode = tNode;
-  lView = view;
+  instructionState.previousOrParentTNode = tNode;
+  instructionState.lView = view;
 }
 
-/**
- * If `isParent` is:
- *  - `true`: then `previousOrParentTNode` points to a parent node.
- *  - `false`: then `previousOrParentTNode` points to previous node (sibling).
- */
-let isParent: boolean;
-
 export function getIsParent(): boolean {
   // top level variables should not be exported for performance reasons (PERF_NOTES.md)
-  return isParent;
+  return instructionState.isParent;
 }
 
 export function setIsNotParent(): void {
-  isParent = false;
+  instructionState.isParent = false;
 }
 export function setIsParent(): void {
-  isParent = true;
+  instructionState.isParent = true;
 }
 
-/**
- * State of the current view being processed.
- *
- * An array of nodes (text, element, container, etc), pipes, their bindings, and
- * any local variables that need to be stored between invocations.
- */
-let lView: LView;
-
-/**
- * The last viewData retrieved by nextContext().
- * Allows building nextContext() and reference() calls.
- *
- * e.g. const inner = x().$implicit; const outer = x().$implicit;
- */
-let contextLView: LView = null !;
-
 export function getContextLView(): LView {
   // top level variables should not be exported for performance reasons (PERF_NOTES.md)
-  return contextLView;
+  return instructionState.contextLView;
 }
 
-/**
- * In this mode, any changes in bindings will throw an ExpressionChangedAfterChecked error.
- *
- * Necessary to support ChangeDetectorRef.checkNoChanges().
- */
-let checkNoChangesMode = false;
-
 export function getCheckNoChangesMode(): boolean {
   // top level variables should not be exported for performance reasons (PERF_NOTES.md)
-  return checkNoChangesMode;
+  return instructionState.checkNoChangesMode;
 }
 
 export function setCheckNoChangesMode(mode: boolean): void {
-  checkNoChangesMode = mode;
+  instructionState.checkNoChangesMode = mode;
 }
 
-/**
- * The root index from which pure function instructions should calculate their binding
- * indices. In component views, this is TView.bindingStartIndex. In a host binding
- * context, this is the TView.expandoStartIndex + any dirs/hostVars before the given dir.
- */
-let bindingRootIndex: number = -1;
-
 // top level variables should not be exported for performance reasons (PERF_NOTES.md)
 export function getBindingRoot() {
-  return bindingRootIndex;
+  return instructionState.bindingRootIndex;
 }
 
 export function setBindingRoot(value: number) {
-  bindingRootIndex = value;
+  instructionState.bindingRootIndex = value;
 }
 
-/**
- * Current index of a View or Content Query which needs to be processed next.
- * We iterate over the list of Queries and increment current query index at every step.
- */
-let currentQueryIndex: number = 0;
-
 export function getCurrentQueryIndex(): number {
   // top level variables should not be exported for performance reasons (PERF_NOTES.md)
-  return currentQueryIndex;
+  return instructionState.currentQueryIndex;
 }
 
 export function setCurrentQueryIndex(value: number): void {
-  currentQueryIndex = value;
+  instructionState.currentQueryIndex = value;
 }
 
 /**
@@ -390,18 +456,18 @@ export function selectView(newView: LView, hostTNode: TElementNode | TViewNode |
   }
 
   ngDevMode && assertLViewOrUndefined(newView);
-  const oldView = lView;
+  const oldView = instructionState.lView;
 
-  previousOrParentTNode = hostTNode !;
-  isParent = true;
+  instructionState.previousOrParentTNode = hostTNode !;
+  instructionState.isParent = true;
 
-  lView = contextLView = newView;
+  instructionState.lView = instructionState.contextLView = newView;
   return oldView;
 }
 
 export function nextContextImpl<T = any>(level: number = 1): T {
-  contextLView = walkUpViews(level, contextLView !);
-  return contextLView[CONTEXT] as T;
+  instructionState.contextLView = walkUpViews(level, instructionState.contextLView !);
+  return instructionState.contextLView[CONTEXT] as T;
 }
 
 function walkUpViews(nestingLevel: number, currentView: LView): LView {
@@ -419,16 +485,13 @@ function walkUpViews(nestingLevel: number, currentView: LView): LView {
  * Resets the application state.
  */
 export function resetComponentState() {
-  isParent = false;
-  previousOrParentTNode = null !;
-  elementDepthCount = 0;
-  bindingsEnabled = true;
+  instructionState.isParent = false;
+  instructionState.previousOrParentTNode = null !;
+  instructionState.elementDepthCount = 0;
+  instructionState.bindingsEnabled = true;
   setCurrentStyleSanitizer(null);
 }
 
-/* tslint:disable */
-let _selectedIndex = -1 << ActiveElementFlags.Size;
-
 /**
  * Gets the most recent index passed to {@link select}
  *
@@ -436,7 +499,7 @@ let _selectedIndex = -1 << ActiveElementFlags.Size;
  * current `LView` to act on.
  */
 export function getSelectedIndex() {
-  return _selectedIndex >> ActiveElementFlags.Size;
+  return instructionState.selectedIndex >> ActiveElementFlags.Size;
 }
 
 /**
@@ -449,19 +512,17 @@ export function getSelectedIndex() {
  * run if and when the provided `index` value is different from the current selected index value.)
  */
 export function setSelectedIndex(index: number) {
-  _selectedIndex = index << ActiveElementFlags.Size;
+  instructionState.selectedIndex = index << ActiveElementFlags.Size;
 }
 
 
-let _currentNamespace: string|null = null;
-
 /**
  * Sets the namespace used to create elements to `'http://www.w3.org/2000/svg'` in global state.
  *
  * @codeGenApi
  */
 export function ɵɵnamespaceSVG() {
-  _currentNamespace = 'http://www.w3.org/2000/svg';
+  instructionState.currentNamespace = 'http://www.w3.org/2000/svg';
 }
 
 /**
@@ -470,7 +531,7 @@ export function ɵɵnamespaceSVG() {
  * @codeGenApi
  */
 export function ɵɵnamespaceMathML() {
-  _currentNamespace = 'http://www.w3.org/1998/MathML/';
+  instructionState.currentNamespace = 'http://www.w3.org/1998/MathML/';
 }
 
 /**
@@ -488,16 +549,15 @@ export function ɵɵnamespaceHTML() {
  * `createElement` rather than `createElementNS`.
  */
 export function namespaceHTMLInternal() {
-  _currentNamespace = null;
+  instructionState.currentNamespace = null;
 }
 
 export function getNamespace(): string|null {
-  return _currentNamespace;
+  return instructionState.currentNamespace;
 }
 
-let _currentSanitizer: StyleSanitizeFn|null;
 export function setCurrentStyleSanitizer(sanitizer: StyleSanitizeFn | null) {
-  _currentSanitizer = sanitizer;
+  instructionState.currentSanitizer = sanitizer;
 }
 
 export function resetCurrentStyleSanitizer() {
@@ -505,5 +565,5 @@ export function resetCurrentStyleSanitizer() {
 }
 
 export function getCurrentStyleSanitizer() {
-  return _currentSanitizer;
+  return instructionState.currentSanitizer;
 }

packages/core/test/bundling/cyclic_import/bundle.golden_symbols.json

@@ -140,21 +140,12 @@
   {
     "name": "__window"
   },
-  {
-    "name": "_currentNamespace"
-  },
-  {
-    "name": "_elementExitFn"
-  },
   {
     "name": "_global"
   },
   {
     "name": "_renderCompCount"
   },
-  {
-    "name": "_selectedIndex"
-  },
   {
     "name": "addComponentLogic"
   },
@@ -188,9 +179,6 @@
   {
     "name": "callHooks"
   },
-  {
-    "name": "checkNoChangesMode"
-  },
   {
     "name": "concatString"
   },
@@ -431,6 +419,9 @@
   {
     "name": "instantiateRootComponent"
   },
+  {
+    "name": "instructionState"
+  },
   {
     "name": "invertObject"
   },

packages/core/test/bundling/hello_world/bundle.golden_symbols.json

@@ -125,18 +125,12 @@
   {
     "name": "__window"
   },
-  {
-    "name": "_elementExitFn"
-  },
   {
     "name": "_global"
   },
   {
     "name": "_renderCompCount"
   },
-  {
-    "name": "_selectedIndex"
-  },
   {
     "name": "addToViewTree"
   },
@@ -158,9 +152,6 @@
   {
     "name": "callHooks"
   },
-  {
-    "name": "checkNoChangesMode"
-  },
   {
     "name": "createLView"
   },
@@ -332,6 +323,9 @@
   {
     "name": "instantiateRootComponent"
   },
+  {
+    "name": "instructionState"
+  },
   {
     "name": "invertObject"
   },

packages/core/test/bundling/todo/bundle.golden_symbols.json

@@ -326,33 +326,21 @@
   {
     "name": "_currentInjector"
   },
-  {
-    "name": "_currentNamespace"
-  },
   {
     "name": "_devMode"
   },
-  {
-    "name": "_elementExitFn"
-  },
   {
     "name": "_global"
   },
   {
     "name": "_renderCompCount"
   },
-  {
-    "name": "_selectedIndex"
-  },
   {
     "name": "_state"
   },
   {
     "name": "_symbolIterator"
   },
-  {
-    "name": "activeDirectiveId"
-  },
   {
     "name": "addBindingIntoContext"
   },
@@ -446,9 +434,6 @@
   {
     "name": "checkNoChangesInternal"
   },
-  {
-    "name": "checkNoChangesMode"
-  },
   {
     "name": "cleanUpView"
   },
@@ -461,9 +446,6 @@
   {
     "name": "containerInternal"
   },
-  {
-    "name": "contextLView"
-  },
   {
     "name": "createContainerRef"
   },
@@ -899,6 +881,9 @@
   {
     "name": "instantiateRootComponent"
   },
+  {
+    "name": "instructionState"
+  },
   {
     "name": "interpolation1"
   },