Glimmer optimizations #11338
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Glimmer optimizations #11338
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Apparently, v8’s JIT engineers require that we, as JavaScript developers perform this very simple transformation, since they do not seem capable of performing it themselves.
Previously, `parentView` and `ownerView` were set based on `scope`,
which is the “owner tree”. However, it should be based on the
component tree instead.
This commit properly wires up `parentView` and `ownerView`, while
maintaining the correct semantics for the `{{view.foo}}` keyword in
both legacy views and components.
Previously, the `env` was a bag of properties, and got frequently extended or modified (in largely predictable ways). The consequence is that even though the environment is conceptually a single concept, it got treated internally as a megamorphic shapeless entity. For what it’s worth, this JIT confusion was somewhat mirrored by a confusion when reading the code: it was never precisely clear what the `env` would look like from the perspective of a human reader. This commit changes the environment to be a single class. There are only two kinds of child environments (a change in the `view` and a change to `outletState`), and there are now methods on `env` to make that simple and predictable. The consequence is that all methods that take an `env` now go down a fast path when accessing it, and human readers of the code can feel confident about what the environment looks like.
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A handful of optimizations for Glimmer. Several of these are tweak that help the V8 JIT to maintain the shape of internal bookkeeping structures. We also fixed a bug that fixes several related issues, where
parentView/ownerViewwere not maintained properly. There were likely teardown bugs related to this. Lastly, we made an improvement to the algorithm used by{{#each}}and other helpers on subsequent re-renders that should reduce the number of DOM operations needed in most situations. (That work happened in the tildeio/htmlbars.)