Changeset 273605 in webkit

Timestamp:

Feb 26, 2021 4:37:31 PM (17 months ago)

Author:

ysuzuki@apple.com

Message:

[JSC] Avoid function allocations for non-user-provided Promise then callbacks
​https://bugs.webkit.org/show_bug.cgi?id=222490

Reviewed by Keith Miller.

At @performPromiseThen point, callback function objects themselves are not accessible from users
if they are not passed from users. So, we can reuse functions if users do not pass functions.

• builtins/PromiseOperations.js:

(globalPrivate.promiseEmptyOnFulfilled):
(globalPrivate.promiseEmptyOnRejected):
(globalPrivate.performPromiseThen):
(onFulfilled): Deleted.
(onRejected): Deleted.

Location:

trunk/Source/JavaScriptCore

Files:

• ChangeLog (modified) (1 diff)
• builtins/PromiseOperations.js (modified) (2 diffs)

trunk/Source/JavaScriptCore/ChangeLog

@@ +1 @@
+2021-02-26  Yusuke Suzuki  <ysuzuki@apple.com>
+
+        [JSC] Avoid function allocations for non-user-provided Promise then callbacks
+        https://bugs.webkit.org/show_bug.cgi?id=222490
+
+        Reviewed by Keith Miller.
+
+        At @performPromiseThen point, callback function objects themselves are not accessible from users
+        if they are not passed from users. So, we can reuse functions if users do not pass functions.
+
+        * builtins/PromiseOperations.js:
+        (globalPrivate.promiseEmptyOnFulfilled):
+        (globalPrivate.promiseEmptyOnRejected):
+        (globalPrivate.performPromiseThen):
+        (onFulfilled): Deleted.
+        (onRejected): Deleted.
+
 2021-02-26  Michael Saboff  <msaboff@apple.com>
 

trunk/Source/JavaScriptCore/builtins/PromiseOperations.js

@@ -521 +521 @@
 
 @globalPrivate
+function promiseEmptyOnFulfilled(argument)
+{
+    "use strict";
+
+    return argument;
+}
+
+@globalPrivate
+function promiseEmptyOnRejected(argument)
+{
+    "use strict";
+
+    throw argument;
+}
+
+@globalPrivate
 function performPromiseThen(promise, onFulfilled, onRejected, promiseOrCapability)
 {
@@ -526 +542 @@
 
     if (!@isCallable(onFulfilled))
-        onFulfilled = function (argument) { return argument; };
+        onFulfilled = @promiseEmptyOnFulfilled;
 
     if (!@isCallable(onRejected))
-        onRejected = function (argument) { throw argument; };
+        onRejected = @promiseEmptyOnRejected;
 
     var reaction = @newPromiseReaction(promiseOrCapability, onFulfilled, onRejected);