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fix(ivy): avoid type coercion in binding-related instruction asserts (#29470) 

ivy's bindingUpdated instruction is using the assertNotEqual check to make
sure that NO_CHANGE value (of type Object) is not passed as a value to be
dirty-checked. In practice it means that any value passed as a binding
value would be compared to the NO_CHANGE object.

It turns out that the assertNotEqual is using == and given
that binding values are of different type and we always compare it to the
NO_CHANGE object we were doing lots of type coercion. It resulted in calls
to expensive types conversions and calls to Object.toString().

A profiler reported ~15% of the self time spent in the assertNotEqual
but it turns out that removing type coercion speeds up Material Chips with
input scenario much more (~40ms down to ~20ms).

This PR introduces new assert method `assertNotSame` that uses strict equality
check. The new assertion is used in binding instructions to compare to
NO_CHANGE object reference.

PR Close #29470
This commit is contained in:
Pawel Kozlowski 2019-03-22 14:29:45 +01:00 committed by Misko Hevery
parent 26a8c5961e
commit c34c223122
2 changed files with 9 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
packages/core/src/render3/bindings.ts
View File

@ -7,7 +7,7 @@
*/
import {devModeEqual} from '../change_detection/change_detection_util';
import {assertDataInRange, assertLessThan, assertNotEqual} from '../util/assert';
import {assertDataInRange, assertLessThan, assertNotSame} from '../util/assert';
import {throwErrorIfNoChangesMode} from './errors';
import {LView} from './interfaces/view';
import {getCheckNoChangesMode} from './state';
@ -27,13 +27,13 @@ export function updateBinding(lView: LView, bindingIndex: number, value: any): a
export function getBinding(lView: LView, bindingIndex: number): any {
ngDevMode && assertDataInRange(lView, bindingIndex);
ngDevMode &&
assertNotEqual(lView[bindingIndex], NO_CHANGE, 'Stored value should never be NO_CHANGE.');
assertNotSame(lView[bindingIndex], NO_CHANGE, 'Stored value should never be NO_CHANGE.');
return lView[bindingIndex];
}
/** Updates binding if changed, then returns whether it was updated. */
export function bindingUpdated(lView: LView, bindingIndex: number, value: any): boolean {
ngDevMode && assertNotEqual(value, NO_CHANGE, 'Incoming value should never be NO_CHANGE.');
ngDevMode && assertNotSame(value, NO_CHANGE, 'Incoming value should never be NO_CHANGE.');
ngDevMode &&
assertLessThan(bindingIndex, lView.length, `Slot should have been initialized to NO_CHANGE`);

6
packages/core/src/util/assert.ts
View File

@ -34,6 +34,12 @@ export function assertSame<T>(actual: T, expected: T, msg: string) {
}
}
export function assertNotSame<T>(actual: T, expected: T, msg: string) {
if (actual === expected) {
throwError(msg);
}
}
export function assertLessThan<T>(actual: T, expected: T, msg: string) {
if (actual >= expected) {
throwError(msg);