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Experiment with using an object literal for Fiber creation #28734
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Awesome! It definitely makes sense to proceed if we can confirm that this is a perf win on Hermes. It should be given our earlier profiling results but let's check first? |
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The RN code from prod looks like this: function FiberNode(tag, pendingProps, key, mode) {
this.tag = tag;
this.key = key;
this.sibling =
this.child =
this.return =
this.stateNode =
this.type =
this.elementType =
null;
this.index = 0;
this.refCleanup = this.ref = null;
this.pendingProps = pendingProps;
this.dependencies =
this.memoizedState =
this.updateQueue =
this.memoizedProps =
null;
this.mode = mode;
this.subtreeFlags = this.flags = 0;
this.deletions = null;
this.childLanes = this.lanes = 0;
this.alternate = null;
}
function createFiberImplClass(tag, pendingProps, key, mode) {
return new FiberNode(tag, pendingProps, key, mode);
}
function createFiberImplObject(tag, pendingProps, key, mode) {
return {
tag: tag,
key: key,
elementType: null,
type: null,
stateNode: null,
return: null,
child: null,
sibling: null,
index: 0,
ref: null,
refCleanup: null,
pendingProps: pendingProps,
memoizedProps: null,
updateQueue: null,
memoizedState: null,
dependencies: null,
mode: mode,
flags: 0,
subtreeFlags: 0,
deletions: null,
lanes: 0,
childLanes: 0,
alternate: null
};
}
var createFiber = enableObjectFiber
? createFiberImplObject
: createFiberImplClass; |
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Looks good! I wonder if we should just unify it to be an object literal -- is the object literal slower on v8? I'm happy to profile this in v8 too
Object literals should be faster at least on React Native with Hermes as the JS engine. It might also be interesting to confirm the old comments in this file from years ago are even still valid. Creating an object from a literal should be a simpler operation. It's a bit unfortunate that this introduces a bunch of copied code, but since we rearely update the fields on fibers, this seems like an okay tradeoff for a hot code path. An alternative would be some sort of macro system, but that doesn't seem worth the extra complexity.
Object literals should be faster at least on React Native with Hermes as the JS engine. It might also be interesting to confirm the old comments in this file from years ago are even still valid. Creating an object from a literal should be a simpler operation. It's a bit unfortunate that this introduces a bunch of copied code, but since we rearely update the fields on fibers, this seems like an okay tradeoff for a hot code path. An alternative would be some sort of macro system, but that doesn't seem worth the extra complexity. DiffTrain build for [fe98289](fe98289)
Object literals should be faster at least on React Native with Hermes as the JS engine. It might also be interesting to confirm the old comments in this file from years ago are even still valid. Creating an object from a literal should be a simpler operation. It's a bit unfortunate that this introduces a bunch of copied code, but since we rearely update the fields on fibers, this seems like an okay tradeoff for a hot code path. An alternative would be some sort of macro system, but that doesn't seem worth the extra complexity. DiffTrain build for commit fe98289.
Object literals should be faster at least on React Native with Hermes as the JS engine.
It might also be interesting to confirm the old comments in this file from years ago are even still valid. Creating an object from a literal should be a simpler operation.
It's a bit unfortunate that this introduces a bunch of copied code, but since we rearely update the fields on fibers, this seems like an okay tradeoff for a hot code path. An alternative would be some sort of macro system, but that doesn't seem worth the extra complexity.