[compiler] Add Identifier.declarationId

ghstack-source-id: 54973a034bf9ca2e778326a5b0bf367113a63736
Pull Request resolved: #30569

compiler/packages/babel-plugin-react-compiler/src/HIR/HIR.ts

@@ -1174,11 +1174,19 @@ export type NonLocalBinding =
 
 // Represents a user-defined variable (has a name) or a temporary variable (no name).
 export type Identifier = {
-  /*
-   * unique value to distinguish a variable, since name is not guaranteed to
-   * exist or be unique
+  /**
+   * After EnterSSA, `id` uniquely identifies an SSA instance of a variable.
+   * Before EnterSSA, `id` matches `declarationId`.
    */
   id: IdentifierId;
+
+  /**
+   * Uniquely identifies a given variable in the original program. If a value is
+   * reassigned in the original program each reassigned value will have a distinct
+   * `id` (after EnterSSA), but they will still have the same `declarationId`.
+   */
+  declarationId: DeclarationId;
+
   // null for temporaries. name is primarily used for debugging.
   name: IdentifierName | null;
   // The range for which this variable is mutable
@@ -1494,6 +1502,23 @@ export function makeIdentifierId(id: number): IdentifierId {
   return id as IdentifierId;
 }
 
+/*
+ * Simulated opaque type for IdentifierId to prevent using normal numbers as ids
+ * accidentally.
+ */
+const opageDeclarationId = Symbol();
+export type DeclarationId = number & {[opageDeclarationId]: 'DeclarationId'};
+
+export function makeDeclarationId(id: number): DeclarationId {
+  CompilerError.invariant(id >= 0 && Number.isInteger(id), {
+    reason: 'Expected declaration id to be a non-negative integer',
+    description: null,
+    loc: null,
+    suggestions: null,
+  });
+  return id as DeclarationId;
+}
+
 /*
  * Simulated opaque type for InstructionId to prevent using normal numbers as ids
  * accidentally.

compiler/packages/babel-plugin-react-compiler/src/HIR/HIRBuilder.ts

@@ -25,6 +25,7 @@ import {
   Terminal,
   VariableBinding,
   makeBlockId,
+  makeDeclarationId,
   makeIdentifierName,
   makeInstructionId,
   makeType,
@@ -184,6 +185,7 @@ export default class HIRBuilder {
     const id = this.nextIdentifierId;
     return {
       id,
+      declarationId: makeDeclarationId(id),
       name: null,
       mutableRange: {start: makeInstructionId(0), end: makeInstructionId(0)},
       scope: null,
@@ -326,6 +328,7 @@ export default class HIRBuilder {
         const id = this.nextIdentifierId;
         const identifier: Identifier = {
           id,
+          declarationId: makeDeclarationId(id),
           name: makeIdentifierName(name),
           mutableRange: {
             start: makeInstructionId(0),
@@ -895,10 +898,12 @@ export function createTemporaryPlace(
   env: Environment,
   loc: SourceLocation,
 ): Place {
+  const id = env.nextIdentifierId;
   return {
     kind: 'Identifier',
     identifier: {
-      id: env.nextIdentifierId,
+      id,
+      declarationId: makeDeclarationId(id),
       mutableRange: {start: makeInstructionId(0), end: makeInstructionId(0)},
       name: null,
       scope: null,

compiler/packages/babel-plugin-react-compiler/src/Inference/InlineImmediatelyInvokedFunctionExpressions.ts

@@ -23,7 +23,11 @@ import {
   promoteTemporary,
   reversePostorderBlocks,
 } from '../HIR';
-import {markInstructionIds, markPredecessors} from '../HIR/HIRBuilder';
+import {
+  createTemporaryPlace,
+  markInstructionIds,
+  markPredecessors,
+} from '../HIR/HIRBuilder';
 import {eachInstructionValueOperand} from '../HIR/visitors';
 import {retainWhere} from '../Utils/utils';
 
@@ -225,23 +229,7 @@ function rewriteBlock(
   block.instructions.push({
     id: makeInstructionId(0),
     loc: terminal.loc,
-    lvalue: {
-      effect: Effect.Unknown,
-      identifier: {
-        id: env.nextIdentifierId,
-        mutableRange: {
-          start: makeInstructionId(0),
-          end: makeInstructionId(0),
-        },
-        name: null,
-        scope: null,
-        type: makeType(),
-        loc: terminal.loc,
-      },
-      kind: 'Identifier',
-      reactive: false,
-      loc: terminal.loc,
-    },
+    lvalue: createTemporaryPlace(env, terminal.loc),
     value: {
       kind: 'StoreLocal',
       lvalue: {kind: InstructionKind.Reassign, place: {...returnValue}},
@@ -267,23 +255,7 @@ function declareTemporary(
   block.instructions.push({
     id: makeInstructionId(0),
     loc: GeneratedSource,
-    lvalue: {
-      effect: Effect.Unknown,
-      identifier: {
-        id: env.nextIdentifierId,
-        mutableRange: {
-          start: makeInstructionId(0),
-          end: makeInstructionId(0),
-        },
-        name: null,
-        scope: null,
-        type: makeType(),
-        loc: result.loc,
-      },
-      kind: 'Identifier',
-      reactive: false,
-      loc: GeneratedSource,
-    },
+    lvalue: createTemporaryPlace(env, result.loc),
     value: {
       kind: 'DeclareLocal',
       lvalue: {

compiler/packages/babel-plugin-react-compiler/src/SSA/EnterSSA.ts

@@ -79,6 +79,7 @@ class SSABuilder {
   makeId(oldId: Identifier): Identifier {
     return {
       id: this.nextSsaId,
+      declarationId: oldId.declarationId,
       name: oldId.name,
       mutableRange: {
         start: makeInstructionId(0),