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perf(ivy): remove unused event argument in listener instructions (#35097)

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Currently Ivy always generates the `$event` function argument, even if it isn't being used by the listener expressions. This can lead to unnecessary bytes being generated, because optimizers won't remove unused arguments by default. These changes add some logic to avoid adding the argument when it isn't required.

PR Close #35097
This commit is contained in:
Kristiyan Kostadinov
2020-02-01 13:19:31 +01:00
committed by Miško Hevery
parent 39ef57971c
commit 9228d7f15d
9 changed files with 149 additions and 29 deletions
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13
packages/compiler/src/render3/view/template.ts
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@ -69,13 +69,14 @@ export function prepareEventListenerParameters(
Supported list of global targets: ${Array.from(GLOBAL_TARGET_RESOLVERS.keys())}.`);
}
const eventArgumentName = '$event';
const implicitReceiverAccesses = new Set<string>();
const implicitReceiverExpr = (scope === null || scope.bindingLevel === 0) ?
o.variable(CONTEXT_NAME) :
scope.getOrCreateSharedContextVar(0);
const bindingExpr = convertActionBinding(
scope, implicitReceiverExpr, handler, 'b', () => error('Unexpected interpolation'),
eventAst.handlerSpan);
eventAst.handlerSpan, implicitReceiverAccesses);
const statements = [];
if (scope) {
statements.push(...scope.restoreViewStatement());
@ -86,9 +87,13 @@ export function prepareEventListenerParameters(
const eventName: string =
type === ParsedEventType.Animation ? prepareSyntheticListenerName(name, phase !) : name;
const fnName = handlerName && sanitizeIdentifier(handlerName);
const fnArgs = [new o.FnParam('$event', o.DYNAMIC_TYPE)];
const handlerFn = o.fn(fnArgs, statements, o.INFERRED_TYPE, null, fnName);
const fnArgs: o.FnParam[] = [];
if (implicitReceiverAccesses.has(eventArgumentName)) {
fnArgs.push(new o.FnParam(eventArgumentName, o.DYNAMIC_TYPE));
}
const handlerFn = o.fn(fnArgs, statements, o.INFERRED_TYPE, null, fnName);
const params: o.Expression[] = [o.literal(eventName), handlerFn];
if (target) {
params.push(