Update on "[compiler] Instruction reordering"

Adds a pass just after DCE to reorder safely reorderable instructions (jsx, primitives, globals) closer to where they are used, to allow other optimization passes to be more effective. Notably, the reordering allows scope merging to be more effective, since that pass relies on two scopes not having intervening instructions — in many cases we can now reorder such instructions out of the way and unlock merging, as demonstrated in the changed fixtures.

The algorithm itself is described in the docblock.

note: This is a cleaned up version of #29579 that is ready for review.

[ghstack-poisoned]

Author: josephsavona

.eslintrc.js

@@ -245,7 +245,7 @@ module.exports = {
       },
     ],
     'no-shadow': ERROR,
-    'no-unused-vars': [ERROR, {args: 'none'}],
+    'no-unused-vars': [ERROR, {args: 'none', ignoreRestSiblings: true}],
     'no-use-before-define': OFF,
     'no-useless-concat': OFF,
     quotes: [ERROR, 'single', {avoidEscape: true, allowTemplateLiterals: true}],
@@ -571,6 +571,7 @@ module.exports = {
     TimeoutID: 'readonly',
     WheelEventHandler: 'readonly',
     FinalizationRegistry: 'readonly',
+    Omit: 'readonly',
 
     spyOnDev: 'readonly',
     spyOnDevAndProd: 'readonly',

compiler/.vscode/settings.json

@@ -8,7 +8,6 @@
     "vercel-build": "yarn workspaces run build",
     "start": "next start",
     "lint": "next lint",
-    "postinstall": "yarn playwright install",
     "test": "playwright test"
   },
   "dependencies": {

compiler/apps/playground/package.json

@@ -15,8 +15,6 @@
     "url": "git+https://github.com/facebook/react-forget.git"
   },
   "scripts": {
-    "bundle:meta": "scripts/bundle-meta.sh",
-    "bundle:oss": "scripts/bundle-oss.sh",
     "copyright": "node scripts/copyright.js",
     "hash": "scripts/hash.sh",
     "start": "yarn workspace playground run start",

compiler/package.json

@@ -131,6 +131,8 @@ const CompilationModeSchema = z.enum([
    * This is the default mode
    */
   "infer",
+  // Compile only components using Flow component syntax and hooks using hook syntax.
+  "syntax",
   // Compile only functions which are explicitly annotated with "use forget"
   "annotation",
   // Compile all top-level functions

compiler/packages/babel-plugin-react-compiler/src/Entrypoint/Options.ts

@@ -71,6 +71,8 @@ import {
 } from "../ReactiveScopes";
 import { alignMethodCallScopes } from "../ReactiveScopes/AlignMethodCallScopes";
 import { alignReactiveScopesToBlockScopesHIR } from "../ReactiveScopes/AlignReactiveScopesToBlockScopesHIR";
+import { flattenReactiveLoopsHIR } from "../ReactiveScopes/FlattenReactiveLoopsHIR";
+import { flattenScopesWithHooksOrUseHIR } from "../ReactiveScopes/FlattenScopesWithHooksOrUseHIR";
 import { pruneAlwaysInvalidatingScopes } from "../ReactiveScopes/PruneAlwaysInvalidatingScopes";
 import pruneInitializationDependencies from "../ReactiveScopes/PruneInitializationDependencies";
 import { stabilizeBlockIds } from "../ReactiveScopes/StabilizeBlockIds";
@@ -203,8 +205,10 @@ function* runWithEnvironment(
   deadCodeElimination(hir);
   yield log({ kind: "hir", name: "DeadCodeElimination", value: hir });
 
-  instructionReordering(hir);
-  yield log({ kind: "hir", name: "InstructionReordering", value: hir });
+  if (env.config.enableInstructionReordering) {
+    instructionReordering(hir);
+    yield log({ kind: "hir", name: "InstructionReordering", value: hir });
+  }
 
   pruneMaybeThrows(hir);
   yield log({ kind: "hir", name: "PruneMaybeThrows", value: hir });
@@ -285,6 +289,20 @@ function* runWithEnvironment(
     });
 
     assertValidBlockNesting(hir);
+
+    flattenReactiveLoopsHIR(hir);
+    yield log({
+      kind: "hir",
+      name: "FlattenReactiveLoopsHIR",
+      value: hir,
+    });
+
+    flattenScopesWithHooksOrUseHIR(hir);
+    yield log({
+      kind: "hir",
+      name: "FlattenScopesWithHooksOrUseHIR",
+      value: hir,
+    });
   }
 
   const reactiveFunction = buildReactiveFunction(hir);
@@ -324,23 +342,23 @@ function* runWithEnvironment(
       name: "BuildReactiveBlocks",
       value: reactiveFunction,
     });
-  }
 
-  flattenReactiveLoops(reactiveFunction);
-  yield log({
-    kind: "reactive",
-    name: "FlattenReactiveLoops",
-    value: reactiveFunction,
-  });
+    flattenReactiveLoops(reactiveFunction);
+    yield log({
+      kind: "reactive",
+      name: "FlattenReactiveLoops",
+      value: reactiveFunction,
+    });
 
-  assertScopeInstructionsWithinScopes(reactiveFunction);
+    flattenScopesWithHooksOrUse(reactiveFunction);
+    yield log({
+      kind: "reactive",
+      name: "FlattenScopesWithHooks",
+      value: reactiveFunction,
+    });
+  }
 
-  flattenScopesWithHooksOrUse(reactiveFunction);
-  yield log({
-    kind: "reactive",
-    name: "FlattenScopesWithHooks",
-    value: reactiveFunction,
-  });
+  assertScopeInstructionsWithinScopes(reactiveFunction);
 
   propagateScopeDependencies(reactiveFunction);
   yield log({