perf(ivy): attempt to coalesce listeners only in presence of directives

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

@@ -14,7 +14,7 @@ import {GlobalTargetResolver, RElement, Renderer3, isProceduralRenderer} from '.
 import {CLEANUP, FLAGS, LView, LViewFlags, RENDERER, TVIEW} from '../interfaces/view';
 import {assertNodeOfPossibleTypes} from '../node_assert';
 import {getLView, getPreviousOrParentTNode} from '../state';
-import {getComponentViewByIndex, getNativeByTNode, unwrapRNode} from '../util/view_utils';
+import {getComponentViewByIndex, getNativeByTNode, hasDirectives, unwrapRNode} from '../util/view_utils';
 import {BindingDirection, generatePropertyAliases, getCleanup, handleError, loadComponentRenderer, markViewDirty} from './shared';
 
 /**
@@ -132,12 +132,16 @@ function listenerInternal(
       // In order to have just one native event handler in presence of multiple handler functions,
       // we just register a first handler function as a native event listener and then chain
       // (coalesce) other handler functions on top of the first native handler function.
-      //
+      let existingListener = null;
       // Please note that the coalescing described here doesn't happen for events specifying an
       // alternative target (ex. (document:click)) - this is to keep backward compatibility with the
       // view engine.
-      const existingListener =
-          eventTargetResolver ? null : findExistingListener(lView, eventName, tNode.index);
+      // Also, we don't have to search for existing listeners is there are no directives
+      // matching on a given node as we can't register multiple event handlers for the same event in
+      // a template (this would mean having duplicate attributes).
+      if (!eventTargetResolver && hasDirectives(tNode)) {
+        existingListener = findExistingListener(lView, eventName, tNode.index);
+      }
       if (existingListener !== null) {
         // Attach a new listener at the head of the coalesced listeners list.
         (<any>listenerFn).__ngNextListenerFn__ = (<any>existingListener).__ngNextListenerFn__;

packages/core/src/render3/util/view_utils.ts

@@ -131,6 +131,13 @@ export function getNativeByTNode(tNode: TNode, hostView: LView): RNode {
   return unwrapRNode(hostView[tNode.index]);
 }
 
+/**
+ * A helper function that returns `true` if a given `TNode` has any matching directives.
+ */
+export function hasDirectives(tNode: TNode): boolean {
+  return tNode.directiveEnd > tNode.directiveStart;
+}
+
 export function getTNode(index: number, view: LView): TNode {
   ngDevMode && assertGreaterThan(index, -1, 'wrong index for TNode');
   ngDevMode && assertLessThan(index, view[TVIEW].data.length, 'wrong index for TNode');

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

@@ -848,6 +848,9 @@
   {
     "name": "hasClassInput"
   },
+  {
+    "name": "hasDirectives"
+  },
   {
     "name": "hasParentInjector"
   },