From eed8c08479b969ba22352cd467e42d0d07119952 Mon Sep 17 00:00:00 2001 From: Joe Savona Date: Sat, 8 Jun 2024 16:10:46 -0700 Subject: [PATCH] compiler: Known hooks/nonescaping scopes dont count as pruned There are two cases where it's legit/intended to remove scopes, and we can inline the scope rather than reify a "pruned" scope: * Scopes that contain a single instruction with a hook call. The fact that we create a scope in this case at all is just an artifact of it being simpler to do this and remove the scope later rather than try to avoid creating it in the first place. So for these scopes, we can just inline them. * Scopes that are provably non-escaping. Removing the scope is an optimization, not a case of us having to prune away something that should be there. So again, its fine to inline in this case. I found this from syncing the stack internally and looking at differences in compiled output. The latter case was most common but the first case is just an obvious improvement. ghstack-source-id: 75559d25ab3d3af6a330d91e69e4331006aa97c3 Pull Request resolved: https://github.com/facebook/react/pull/29820 --- .../FlattenScopesWithHooksOrUse.ts | 10 ++++ .../ReactiveScopes/PruneNonEscapingScopes.ts | 8 +--- ...-can-inline-into-consuming-scope.expect.md | 46 +++++++++++++++++++ ...endency-can-inline-into-consuming-scope.js | 13 ++++++ ...om-interleaved-reactivity-for-of.expect.md | 9 ++-- 5 files changed, 75 insertions(+), 11 deletions(-) create mode 100644 compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/nonreactive-noescaping-dependency-can-inline-into-consuming-scope.expect.md create mode 100644 compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/nonreactive-noescaping-dependency-can-inline-into-consuming-scope.js diff --git a/compiler/packages/babel-plugin-react-compiler/src/ReactiveScopes/FlattenScopesWithHooksOrUse.ts b/compiler/packages/babel-plugin-react-compiler/src/ReactiveScopes/FlattenScopesWithHooksOrUse.ts index 06282baa0e362..d7f2ad42daad3 100644 --- a/compiler/packages/babel-plugin-react-compiler/src/ReactiveScopes/FlattenScopesWithHooksOrUse.ts +++ b/compiler/packages/babel-plugin-react-compiler/src/ReactiveScopes/FlattenScopesWithHooksOrUse.ts @@ -66,6 +66,16 @@ class Transform extends ReactiveFunctionTransform { this.visitScope(scope, innerState); outerState.hasHook ||= innerState.hasHook; if (innerState.hasHook) { + if (scope.instructions.length === 1) { + // This was a scope just for a hook call, which doesn't need memoization. + // flatten it away + return { + kind: "replace-many", + value: scope.instructions, + }; + } + // else this scope had multiple instructions and produced some other value: + // mark it as pruned return { kind: "replace", value: { diff --git a/compiler/packages/babel-plugin-react-compiler/src/ReactiveScopes/PruneNonEscapingScopes.ts b/compiler/packages/babel-plugin-react-compiler/src/ReactiveScopes/PruneNonEscapingScopes.ts index 205eb07c7dd7d..da7d71c6dd99b 100644 --- a/compiler/packages/babel-plugin-react-compiler/src/ReactiveScopes/PruneNonEscapingScopes.ts +++ b/compiler/packages/babel-plugin-react-compiler/src/ReactiveScopes/PruneNonEscapingScopes.ts @@ -951,12 +951,8 @@ class PruneScopesTransform extends ReactiveFunctionTransform< } else { this.prunedScopes.add(scopeBlock.scope.id); return { - kind: "replace", - value: { - kind: "pruned-scope", - scope: scopeBlock.scope, - instructions: scopeBlock.instructions, - }, + kind: "replace-many", + value: scopeBlock.instructions, }; } } diff --git a/compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/nonreactive-noescaping-dependency-can-inline-into-consuming-scope.expect.md b/compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/nonreactive-noescaping-dependency-can-inline-into-consuming-scope.expect.md new file mode 100644 index 0000000000000..1e380f2fde693 --- /dev/null +++ b/compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/nonreactive-noescaping-dependency-can-inline-into-consuming-scope.expect.md @@ -0,0 +1,46 @@ + +## Input + +```javascript +// @flow +function Component() { + return ( +
+ ); +} + +``` + +## Code + +```javascript +import { c as _c } from "react/compiler-runtime"; +function Component() { + const $ = _c(1); + let t0; + if ($[0] === Symbol.for("react.memo_cache_sentinel")) { + t0 = ( +
+ ); + $[0] = t0; + } else { + t0 = $[0]; + } + return t0; +} + +``` + +### Eval output +(kind: exception) Fixture not implemented \ No newline at end of file diff --git a/compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/nonreactive-noescaping-dependency-can-inline-into-consuming-scope.js b/compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/nonreactive-noescaping-dependency-can-inline-into-consuming-scope.js new file mode 100644 index 0000000000000..4b2f3e47cd6f8 --- /dev/null +++ b/compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/nonreactive-noescaping-dependency-can-inline-into-consuming-scope.js @@ -0,0 +1,13 @@ +// @flow +function Component() { + return ( +
+ ); +} diff --git a/compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/reactive-control-dependency-from-interleaved-reactivity-for-of.expect.md b/compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/reactive-control-dependency-from-interleaved-reactivity-for-of.expect.md index a8b2da0491eae..e0441ff680e5c 100644 --- a/compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/reactive-control-dependency-from-interleaved-reactivity-for-of.expect.md +++ b/compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/reactive-control-dependency-from-interleaved-reactivity-for-of.expect.md @@ -39,7 +39,7 @@ export const FIXTURE_ENTRYPOINT = { ```javascript import { c as _c } from "react/compiler-runtime"; function Component(props) { - const $ = _c(2); + const $ = _c(1); const a = []; const b = []; @@ -53,12 +53,11 @@ function Component(props) { x = 1; } let t0; - if ($[0] !== x) { + if ($[0] === Symbol.for("react.memo_cache_sentinel")) { t0 = [x]; - $[0] = x; - $[1] = t0; + $[0] = t0; } else { - t0 = $[1]; + t0 = $[0]; } return t0; }