{"body":"With this PR we now no longer emit copy instructions during LeaveSSA, and \nrestore the original identifier name.","parents":["d1fd0449eeb5207649e0d202081d971bf486cab8"],"patch":"diff --git a\/compiler\/forget\/src\/ReactiveScopes\/InferReactiveScopeVariables.ts b\/compiler\/forget\/src\/ReactiveScopes\/InferReactiveScopeVariables.ts\nindex a3674bd2c4..1c7a5d5acf 100644\n--- a\/compiler\/forget\/src\/ReactiveScopes\/InferReactiveScopeVariables.ts\n+++ b\/compiler\/forget\/src\/ReactiveScopes\/InferReactiveScopeVariables.ts\n@@ -5,7 +5,6 @@\n * LICENSE file in the root directory of this source tree.\n *\/\n \n-import invariant from \"invariant\";\n import {\n HIRFunction,\n Identifier,\n@@ -81,10 +80,21 @@ export function inferReactiveScopeVariables(fn: HIRFunction): void {\n \/\/ that mutate together.\n const scopeIdentifiers = new DisjointSet();\n for (const [_, block] of fn.body.blocks) {\n- invariant(\n- block.phis.size === 0,\n- \"Expected phis to be cleared by LeaveSSA pass\"\n- );\n+ \/\/ If a phi is mutated after creation, then we need to alias all of its operands such that they\n+ \/\/ are assigned to the same scope.\n+ for (const phi of block.phis) {\n+ if (\n+ \/\/ The phi was reset because it was not mutated after creation\n+ phi.id.mutableRange.start + 1 !== phi.id.mutableRange.end &&\n+ phi.id.mutableRange.end >\n+ (block.instructions.at(0)?.id ?? block.terminal.id)\n+ ) {\n+ for (const [, phiId] of phi.operands) {\n+ scopeIdentifiers.union([phi.id, phiId]);\n+ }\n+ }\n+ block.phis.clear();\n+ }\n \n for (const instr of block.instructions) {\n const operands: Array = [];\ndiff --git a\/compiler\/forget\/src\/ReactiveScopes\/PropagateScopeDependencies.ts b\/compiler\/forget\/src\/ReactiveScopes\/PropagateScopeDependencies.ts\nindex 5b96f742dd..d4b9af87d7 100644\n--- a\/compiler\/forget\/src\/ReactiveScopes\/PropagateScopeDependencies.ts\n+++ b\/compiler\/forget\/src\/ReactiveScopes\/PropagateScopeDependencies.ts\n@@ -65,6 +65,7 @@ type Scopes = Array;\n \n class Context {\n #declarations: DeclMap = new Map();\n+ #reassignments: Map = new Map();\n #dependencies: Set = new Set();\n \/\/ Produces a de-duplicated mapping of Id -> ReactiveScopeDependency\n \/\/ This helps with.. temporaries that are created only for property loads\n@@ -90,7 +91,10 @@ class Context {\n * on itself.\n *\/\n declare(identifier: Identifier, decl: Decl): void {\n- this.#declarations.set(identifier.id, decl);\n+ if (!this.#declarations.has(identifier.id)) {\n+ this.#declarations.set(identifier.id, decl);\n+ }\n+ this.#reassignments.set(identifier, decl);\n }\n \n declareProperty(lvalue: Place, object: Place, property: string): void {\n@@ -150,22 +154,23 @@ class Context {\n }\n }\n \n- const decl = this.#declarations.get(maybeDependency.place.identifier.id);\n-\n- \/\/ if decl is undefined here, then this is a free var\n- \/\/ (all other decls e.g. `let x;` should be initialized in BuildHIR)\n-\n- \/\/ Any value used after its defining scope has concluded must be added as an\n+ \/\/ Any value used after its originally defining scope has concluded must be added as an\n \/\/ output of its defining scope. Regardless of whether its a const or not,\n \/\/ some later code needs access to the value. If the current\n- \/\/ scope we are visiting is the same scope where the value originates,\n- \/\/ it can't be a dependency on itself.\n+ \/\/ scope we are visiting is the same scope where the value originates, it can't be a dependency\n+ \/\/ on itself.\n+\n+ \/\/ if originalDeclaration is undefined here, then this is a free var\n+ \/\/ (all other decls e.g. `let x;` should be initialized in BuildHIR)\n+ const originalDeclaration = this.#declarations.get(\n+ maybeDependency.place.identifier.id\n+ );\n if (\n- decl !== undefined &&\n- decl.scope !== null &&\n- !this.#isScopeActive(decl.scope)\n+ originalDeclaration !== undefined &&\n+ originalDeclaration.scope !== null &&\n+ !this.#isScopeActive(originalDeclaration.scope)\n ) {\n- decl.scope.declarations.set(\n+ originalDeclaration.scope.declarations.set(\n maybeDependency.place.identifier.id,\n maybeDependency.place.identifier\n );\n@@ -173,13 +178,17 @@ class Context {\n \n \/\/ If this operand is used in a scope, has a dynamic value, and was defined\n \/\/ before this scope, then its a dependency of the scope.\n+ const currentDeclaration =\n+ this.#reassignments.get(maybeDependency.place.identifier) ??\n+ this.#declarations.get(maybeDependency.place.identifier.id);\n const currentScope = this.currentScope;\n if (\n currentScope != null &&\n- decl !== undefined &&\n- decl.kind !== DeclKind.Const &&\n- decl.id < currentScope.range.start &&\n- (decl.scope == null || !this.#isScopeActive(decl.scope))\n+ currentDeclaration !== undefined &&\n+ currentDeclaration.kind !== DeclKind.Const &&\n+ currentDeclaration.id < currentScope.range.start &&\n+ (currentDeclaration.scope == null ||\n+ !this.#isScopeActive(currentDeclaration.scope))\n ) {\n \/\/ Check if there is an existing dependency that describes this operand\n for (const dep of this.#dependencies) {\n@@ -374,11 +383,10 @@ function visitInstruction(context: Context, instr: ReactiveInstruction): void {\n }\n if (lvalue.kind === InstructionKind.Reassign) {\n context.visitReassignment(lvalue);\n- } else {\n- context.declare(lvalue.place.identifier, {\n- kind: DeclKind.Dynamic,\n- id: instr.id,\n- scope: context.currentScope,\n- });\n }\n+ context.declare(lvalue.place.identifier, {\n+ kind: DeclKind.Dynamic,\n+ id: instr.id,\n+ scope: context.currentScope,\n+ });\n }\ndiff --git a\/compiler\/forget\/src\/SSA\/LeaveSSA.ts b\/compiler\/forget\/src\/SSA\/LeaveSSA.ts\nindex cec4eb19bc..d55ed26cf9 100644\n--- a\/compiler\/forget\/src\/SSA\/LeaveSSA.ts\n+++ b\/compiler\/forget\/src\/SSA\/LeaveSSA.ts\n@@ -15,6 +15,7 @@ import {\n Instruction,\n InstructionId,\n InstructionKind,\n+ LValue,\n makeInstructionId,\n Phi,\n Place,\n@@ -87,10 +88,8 @@ import {\n * ```\n *\/\n export function leaveSSA(fn: HIRFunction): void {\n- \/\/ For \"memoizable\" phis (see docblock), this maps the original identifiers to the identifier they\n- \/\/ should be reassigned to. The keys are phi operands, and the values are the phi id to which\n- \/\/ they are being explicitly reassigned.\n- const reassignments: Map = new Map();\n+ \/\/ Maps identifier names to their original declaration.\n+ const declarations: Map = new Map();\n \n \/\/ For non-memoizable phis, this maps original identifiers to the identifier they should be\n \/\/ *rewritten* to. The keys are the original identifiers, and the value will be _either_ the\n@@ -108,17 +107,48 @@ export function leaveSSA(fn: HIRFunction): void {\n }\n \n for (const [, block] of fn.body.blocks) {\n- invariant(\n- block.phis.size === 0,\n- \"Expected all phis to be cleared by predecessors\"\n- );\n+ for (const instr of block.instructions) {\n+ \/\/ Iterate the instructions and perform any rewrites as well as promoting SSA variables to\n+ \/\/ `let` or `reassign` where possible.\n+ const { lvalue } = instr;\n+ if (\n+ lvalue.kind === InstructionKind.Const &&\n+ rewrites.has(lvalue.place.identifier)\n+ ) {\n+ \/\/ For rewrites, the declaration of the canonical identifier has to be `let`,\n+ \/\/ all other assignments are reassignments (which we annotate for codegen\n+ \/\/ purposes).\n+ lvalue.kind =\n+ rewrites.get(lvalue.place.identifier) === lvalue.place.identifier\n+ ? InstructionKind.Let\n+ : InstructionKind.Reassign;\n+ } else if (lvalue.place.identifier.name != null) {\n+ const originalLVal = declarations.get(lvalue.place.identifier.name);\n+ if (originalLVal === undefined) {\n+ declarations.set(lvalue.place.identifier.name, lvalue);\n+ } else {\n+ \/\/ This is an instance of the original id, so we need to promote the original declaration\n+ \/\/ to a `let` and the current lval to a `reassign`\n+ originalLVal.kind = InstructionKind.Let;\n+ lvalue.kind = InstructionKind.Reassign;\n+ }\n+ }\n+ rewritePlace(lvalue.place, rewrites, declarations);\n+ for (const operand of eachInstructionValueOperand(instr.value)) {\n+ rewritePlace(operand, rewrites, declarations);\n+ }\n+ }\n+\n+ const terminal = block.terminal;\n+ for (const operand of eachTerminalOperand(terminal)) {\n+ rewritePlace(operand, rewrites, declarations);\n+ }\n \n \/\/ Find any phi nodes which need a variable declaration in the current block\n \/\/ This includes phis in fallthrough nodes, or blocks that form part of control flow\n \/\/ such as for or while (and later if\/switch).\n const reassignmentPhis: Array = [];\n const rewritePhis: Array = [];\n- const terminal = block.terminal;\n if (\n (terminal.kind === \"if\" ||\n terminal.kind === \"switch\" ||\n@@ -127,8 +157,13 @@ export function leaveSSA(fn: HIRFunction): void {\n terminal.fallthrough !== null\n ) {\n const fallthrough = fn.body.blocks.get(terminal.fallthrough)!;\n- pushPhis(reassignmentPhis, fallthrough);\n- fallthrough.phis.clear();\n+ for (const phi of fallthrough.phis) {\n+ if (phi.id.name == null) {\n+ rewritePhis.push({ phi, block: fallthrough });\n+ } else {\n+ reassignmentPhis.push({ phi, block: fallthrough });\n+ }\n+ }\n }\n if (terminal.kind === \"while\" || terminal.kind === \"for\") {\n const test = fn.body.blocks.get(terminal.test)!;\n@@ -160,52 +195,34 @@ export function leaveSSA(fn: HIRFunction): void {\n \/\/ an if but not another. In this case we populate the let binding with this initial\n \/\/ value rather than generate an extra assignment.\n let initOperand: Identifier | null = null;\n-\n- \/\/ Determine the canonical id to use for this phi. In general this is the phi id,\n- \/\/ but if one phi flows into another as an operand, this will be the final phi.\n- let canonicalId = reassignments.get(phi.id);\n- if (canonicalId === undefined) {\n- canonicalId = phi.id;\n- canonicalId.mutableRange.start = Math.min(\n- canonicalId.mutableRange.start,\n- terminal.id\n- ) as InstructionId;\n- reassignments.set(phi.id, canonicalId);\n- }\n-\n- \/\/ all versions of the variable need to be remapped to the canonical id\n for (const [, operand] of phi.operands) {\n- reassignments.set(operand, canonicalId);\n if (operand.mutableRange.start < terminal.id) {\n- invariant(\n- initOperand === null,\n- \"A phi cannot have two operands initialized before its declaration\"\n- );\n- initOperand = operand;\n+ if (initOperand == null) {\n+ initOperand = operand;\n+ }\n }\n }\n \n- \/\/ If there are no instructions in the block then there's just a terminal\n- \/\/ node, which has no mutation, so that should be false.\n- \/\/\n- \/\/ TODO(joe): This above statement is true, right? Could there be a value\n- \/\/ block with instructions in terminals?\n+ \/\/ If the phi is mutated after its creation, then any values which flow into the phi\n+ \/\/ must also have their ranges extended accordingly.\n const isPhiMutatedAfterCreation: boolean =\n phi.id.mutableRange.end >\n (phiBlock.instructions.at(0)?.id ?? phiBlock.terminal.id);\n \n \/\/ If a phi is never mutated after creation, reset its mutable range to be itself\n if (!isPhiMutatedAfterCreation) {\n- canonicalId.mutableRange.start = phiBlock.terminal.id;\n- canonicalId.mutableRange.end = makeInstructionId(\n- phiBlock.terminal.id + 1\n- );\n+ phi.id.mutableRange.start = terminal.id;\n+ phi.id.mutableRange.end = makeInstructionId(terminal.id + 1);\n }\n \n- \/\/ If this phi id is the canonical id we need to generate a let binding for it\n- \/\/ (otherwise, it means this phi merges into some other phi which already generated\n- \/\/ a binding\n- if (canonicalId === phi.id) {\n+ \/\/ If we never saw a declaration for this phi, it may have been pruned by DCE, so synthesize\n+ \/\/ a new Let binding\n+ invariant(\n+ phi.id.name != null,\n+ \"Expected reassignment phis to have a name\"\n+ );\n+ const declaration = declarations.get(phi.id.name);\n+ if (declaration === undefined) {\n const instr: Instruction = {\n \/\/ NOTE: reuse the terminal id since these lets must be scoped with the terminal anyway.\n \/\/ the mutable range of this canonical id must by definition span from the binding (before\n@@ -214,7 +231,7 @@ export function leaveSSA(fn: HIRFunction): void {\n lvalue: {\n place: {\n kind: \"Identifier\",\n- identifier: canonicalId,\n+ identifier: phi.id,\n effect: Effect.Mutate,\n loc: GeneratedSource,\n },\n@@ -237,37 +254,19 @@ export function leaveSSA(fn: HIRFunction): void {\n loc: GeneratedSource,\n };\n block.instructions.push(instr);\n+ declarations.set(phi.id.name, instr.lvalue);\n+ phi.id.mutableRange.start = terminal.id;\n+ if (!isPhiMutatedAfterCreation) {\n+ phi.id.mutableRange.end = makeInstructionId(terminal.id + 1);\n+ }\n+ } else if (isPhiMutatedAfterCreation) {\n+ declaration.place.identifier.mutableRange.end = phi.id.mutableRange.end;\n }\n \n- \/\/ Generate an assignment in each predecessor\n- for (const [predecessorId, operand] of phi.operands) {\n+ for (const [, operand] of phi.operands) {\n if (isPhiMutatedAfterCreation) {\n operand.mutableRange.end = phi.id.mutableRange.end;\n }\n- if (operand === initOperand) {\n- continue;\n- }\n- const predecessor = fn.body.blocks.get(predecessorId)!;\n- const instr: Instruction = {\n- id: predecessor.terminal.id,\n- lvalue: {\n- place: {\n- kind: \"Identifier\",\n- identifier: canonicalId,\n- effect: Effect.Mutate,\n- loc: GeneratedSource,\n- },\n- kind: InstructionKind.Reassign,\n- },\n- value: {\n- kind: \"Identifier\",\n- identifier: operand,\n- effect: Effect.Read,\n- loc: GeneratedSource,\n- },\n- loc: GeneratedSource,\n- };\n- predecessor.instructions.push(instr);\n }\n }\n \n@@ -289,6 +288,13 @@ export function leaveSSA(fn: HIRFunction): void {\n terminal.id\n ) as InstructionId;\n rewrites.set(phi.id, canonicalId);\n+\n+ if (canonicalId.name !== null) {\n+ const declaration = declarations.get(canonicalId.name);\n+ if (declaration !== undefined) {\n+ declaration.kind = InstructionKind.Let;\n+ }\n+ }\n }\n \n \/\/ all versions of the variable need to be remapped to the canonical id\n@@ -304,31 +310,6 @@ export function leaveSSA(fn: HIRFunction): void {\n canonicalId.mutableRange.start = makeInstructionId(start);\n canonicalId.mutableRange.end = makeInstructionId(end);\n }\n-\n- \/\/ Finally, iterate the instructions and perform any rewrites as well as converting\n- \/\/ SSA variables to `const` where possible\n- for (const instr of block.instructions) {\n- const { lvalue } = instr;\n- if (\n- lvalue.kind === InstructionKind.Const &&\n- rewrites.has(lvalue.place.identifier)\n- ) {\n- \/\/ For rewrites, the declaration of the canonical identifier has to be `let`,\n- \/\/ all other assignments are reassignments (which we annotate for codegen\n- \/\/ purposes).\n- lvalue.kind =\n- rewrites.get(lvalue.place.identifier) === lvalue.place.identifier\n- ? InstructionKind.Let\n- : InstructionKind.Reassign;\n- }\n- rewritePlace(lvalue.place, rewrites);\n- for (const operand of eachInstructionValueOperand(instr.value)) {\n- rewritePlace(operand, rewrites);\n- }\n- }\n- for (const operand of eachTerminalOperand(terminal)) {\n- rewritePlace(operand, rewrites);\n- }\n }\n }\n \n@@ -337,21 +318,29 @@ export function leaveSSA(fn: HIRFunction): void {\n \/\/ place's range.\n function rewritePlace(\n place: Place,\n- rewrites: Map\n+ rewrites: Map,\n+ declarations: Map\n ): void {\n const prevIdentifier = place.identifier;\n const nextIdentifier = rewrites.get(prevIdentifier);\n- if (nextIdentifier === undefined || nextIdentifier === prevIdentifier) {\n- return;\n+\n+ if (nextIdentifier !== undefined) {\n+ if (nextIdentifier === prevIdentifier) return;\n+ nextIdentifier.mutableRange.start = makeInstructionId(\n+ Math.min(\n+ nextIdentifier.mutableRange.start,\n+ prevIdentifier.mutableRange.start\n+ )\n+ );\n+ nextIdentifier.mutableRange.end = makeInstructionId(\n+ Math.max(nextIdentifier.mutableRange.end, prevIdentifier.mutableRange.end)\n+ );\n+ place.identifier = nextIdentifier;\n+ } else if (prevIdentifier.name != null) {\n+ const declaration = declarations.get(prevIdentifier.name);\n+ if (declaration === undefined) return;\n+ \/\/ Only rewrite identifiers that were declared within the function\n+ const originalIdentifier = declaration.place.identifier;\n+ prevIdentifier.id = originalIdentifier.id;\n }\n- nextIdentifier.mutableRange.start = makeInstructionId(\n- Math.min(\n- nextIdentifier.mutableRange.start,\n- prevIdentifier.mutableRange.start\n- )\n- );\n- nextIdentifier.mutableRange.end = makeInstructionId(\n- Math.max(nextIdentifier.mutableRange.end, prevIdentifier.mutableRange.end)\n- );\n- place.identifier = nextIdentifier;\n }\ndiff --git a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/assignment-in-nested-if.expect.md b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/assignment-in-nested-if.expect.md\nnew file mode 100644\nindex 0000000000..df1fe5c8b8\n--- \/dev\/null\n+++ b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/assignment-in-nested-if.expect.md\n@@ -0,0 +1,39 @@\n+\n+## Input\n+\n+```javascript\n+function useBar(props) {\n+ let z;\n+\n+ if (props.a) {\n+ if (props.b) {\n+ z = baz();\n+ }\n+ }\n+\n+ return z;\n+}\n+\n+```\n+\n+## Code\n+\n+```javascript\n+function useBar(props) {\n+ const $ = React.unstable_useMemoCache();\n+ let z = undefined;\n+ if (props.a) {\n+ if (props.b) {\n+ if ($[0] === Symbol.for(\"react.memo_cache_sentinel\")) {\n+ z = baz();\n+ $[0] = z;\n+ } else {\n+ z = $[0];\n+ }\n+ }\n+ }\n+ return z;\n+}\n+\n+```\n+ \n\\ No newline at end of file\ndiff --git a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/error.assignment-in-nested-if.js b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/assignment-in-nested-if.js\nsimilarity index 100%\nrename from compiler\/forget\/src\/__tests__\/fixtures\/hir\/error.assignment-in-nested-if.js\nrename to compiler\/forget\/src\/__tests__\/fixtures\/hir\/assignment-in-nested-if.js\ndiff --git a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/assignment-variations.expect.md b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/assignment-variations.expect.md\nindex 15f9566526..1d31fd3a44 100644\n--- a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/assignment-variations.expect.md\n+++ b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/assignment-variations.expect.md\n@@ -16,9 +16,9 @@ function f() {\n \n ```javascript\n function f() {\n- const x = 3;\n- const x$0 = x >>> 1;\n- return x$0;\n+ let x = 3;\n+ x = x >>> 1;\n+ return x;\n }\n \n ```\ndiff --git a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/error.assignment-in-nested-if.expect.md b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/error.assignment-in-nested-if.expect.md\ndeleted file mode 100644\nindex d5f3965b47..0000000000\n--- a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/error.assignment-in-nested-if.expect.md\n+++ \/dev\/null\n@@ -1,26 +0,0 @@\n-\n-## Input\n-\n-```javascript\n-function useBar(props) {\n- let z;\n-\n- if (props.a) {\n- if (props.b) {\n- z = baz();\n- }\n- }\n-\n- return z;\n-}\n-\n-```\n-\n-\n-## Error\n-\n-```\n-A phi cannot have two operands initialized before its declaration\n-```\n- \n- \n\\ No newline at end of file\ndiff --git a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/error.inverted-if-else.expect.md b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/error.inverted-if-else.expect.md\nindex 4c0bb21f3a..fea88eedb2 100644\n--- a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/error.inverted-if-else.expect.md\n+++ b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/error.inverted-if-else.expect.md\n@@ -20,7 +20,7 @@ function foo(a, b, c) {\n ## Error\n \n ```\n-Expected all phis to be cleared by predecessors\n+Expected a break target\n ```\n \n \n\\ No newline at end of file\ndiff --git a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/hooks-freeze-possibly-mutable-arguments.expect.md b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/hooks-freeze-possibly-mutable-arguments.expect.md\nindex 5c66dadd3e..4cf4aa5865 100644\n--- a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/hooks-freeze-possibly-mutable-arguments.expect.md\n+++ b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/hooks-freeze-possibly-mutable-arguments.expect.md\n@@ -31,17 +31,14 @@ function Component(props) {\n const x = props.x;\n let a = undefined;\n if (cond) {\n- const a$0 = x;\n- a = a$0;\n+ a = x;\n } else {\n- let a$1;\n if ($[0] === Symbol.for(\"react.memo_cache_sentinel\")) {\n- a$1 = [];\n- $[0] = a$1;\n+ a = [];\n+ $[0] = a;\n } else {\n- a$1 = $[0];\n+ a = $[0];\n }\n- a = a$1;\n }\n \n useFreeze(a);\ndiff --git a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/infer-phi-primitive.expect.md b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/infer-phi-primitive.expect.md\nindex 5c2a1044ae..03d61f3923 100644\n--- a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/infer-phi-primitive.expect.md\n+++ b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/infer-phi-primitive.expect.md\n@@ -22,11 +22,9 @@ function foo(a, b) {\n function foo(a, b) {\n let x = undefined;\n if (a) {\n- const x$0 = 1;\n- x = x$0;\n+ x = 1;\n } else {\n- const x$1 = 2;\n- x = x$1;\n+ x = 2;\n }\n \n const y = x;\ndiff --git a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/mutable-lifetime-loops.expect.md b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/mutable-lifetime-loops.expect.md\nindex 92ebe9cdbb..53759f7a3d 100644\n--- a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/mutable-lifetime-loops.expect.md\n+++ b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/mutable-lifetime-loops.expect.md\n@@ -50,10 +50,6 @@ function Component(props) {\n let b = {};\n let c = {};\n let d = {};\n- let a$0 = a;\n- let b$1 = b;\n- let c$2 = c;\n- let d$3 = d;\n while (true) {\n const z = a;\n a = b;\n@@ -61,24 +57,20 @@ function Component(props) {\n c = d;\n d = z;\n mutate(a, b);\n- a$0 = a;\n- b$1 = b;\n- c$2 = c;\n- d$3 = d;\n if (cond(a)) {\n break;\n }\n }\n- if (a$0) {\n+ if (a) {\n }\n- if (b$1) {\n+ if (b) {\n }\n- if (c$2) {\n+ if (c) {\n }\n- if (d$3) {\n+ if (d) {\n }\n \n- mutate(d$3, null);\n+ mutate(d, null);\n }\n \n ```\ndiff --git a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/obj-literal-cached-in-if-else.expect.md b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/obj-literal-cached-in-if-else.expect.md\nindex 02a22b8c47..79293cd39b 100644\n--- a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/obj-literal-cached-in-if-else.expect.md\n+++ b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/obj-literal-cached-in-if-else.expect.md\n@@ -23,26 +23,22 @@ function foo(a, b, c, d) {\n let x = undefined;\n if (someVal) {\n const c_0 = $[0] !== b;\n- let x$0;\n if (c_0) {\n- x$0 = { b: b };\n+ x = { b: b };\n $[0] = b;\n- $[1] = x$0;\n+ $[1] = x;\n } else {\n- x$0 = $[1];\n+ x = $[1];\n }\n- x = x$0;\n } else {\n const c_2 = $[2] !== c;\n- let x$1;\n if (c_2) {\n- x$1 = { c: c };\n+ x = { c: c };\n $[2] = c;\n- $[3] = x$1;\n+ $[3] = x;\n } else {\n- x$1 = $[3];\n+ x = $[3];\n }\n- x = x$1;\n }\n return x;\n }\ndiff --git a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/obj-literal-mutated-after-if-else.expect.md b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/obj-literal-mutated-after-if-else.expect.md\nindex 93c70e5629..2e1a95dab0 100644\n--- a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/obj-literal-mutated-after-if-else.expect.md\n+++ b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/obj-literal-mutated-after-if-else.expect.md\n@@ -27,11 +27,9 @@ function foo(a, b, c, d) {\n if (c_0 || c_1) {\n x = undefined;\n if (someVal) {\n- const x$0 = { b: b };\n- x = x$0;\n+ x = { b: b };\n } else {\n- const x$1 = { c: c };\n- x = x$1;\n+ x = { c: c };\n }\n x.f = 1;\n $[0] = b;\ndiff --git a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/obj-mutated-after-if-else.expect.md b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/obj-mutated-after-if-else.expect.md\nindex a65a733ad5..68f8560f94 100644\n--- a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/obj-mutated-after-if-else.expect.md\n+++ b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/obj-mutated-after-if-else.expect.md\n@@ -21,25 +21,22 @@ function foo(a, b, c, d) {\n ```javascript\n function foo(a, b, c, d) {\n const $ = React.unstable_useMemoCache();\n- const x = someObj();\n const c_0 = $[0] !== a;\n- let x$0;\n+ let x;\n if (c_0) {\n- x$0 = undefined;\n+ x = someObj();\n if (a) {\n- const x$1 = someObj();\n- x$0 = x$1;\n+ x = someObj();\n } else {\n- const x$2 = someObj();\n- x$0 = x$2;\n+ x = someObj();\n }\n- x$0.f = 1;\n+ x.f = 1;\n $[0] = a;\n- $[1] = x$0;\n+ $[1] = x;\n } else {\n- x$0 = $[1];\n+ x = $[1];\n }\n- return x$0;\n+ return x;\n }\n \n ```\ndiff --git a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/primitive-alias-mutate.expect.md b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/primitive-alias-mutate.expect.md\nindex 0014449a79..01e67a8fd4 100644\n--- a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/primitive-alias-mutate.expect.md\n+++ b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/primitive-alias-mutate.expect.md\n@@ -22,11 +22,9 @@ function component(a) {\n function component(a) {\n let x = undefined;\n if (a) {\n- const x$0 = \"bar\";\n- x = x$0;\n+ x = \"bar\";\n } else {\n- const x$1 = \"baz\";\n- x = x$1;\n+ x = \"baz\";\n }\n \n const y = x;\ndiff --git a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/reassignment-conditional.expect.md b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/reassignment-conditional.expect.md\nindex 6b70c68314..5ed27ef15e 100644\n--- a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/reassignment-conditional.expect.md\n+++ b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/reassignment-conditional.expect.md\n@@ -35,25 +35,22 @@ function Component(props) {\n x = $[1];\n }\n const y = x;\n- let x$0 = x;\n if (props.p1) {\n- let x$1;\n if ($[2] === Symbol.for(\"react.memo_cache_sentinel\")) {\n- x$1 = [];\n- $[2] = x$1;\n+ x = [];\n+ $[2] = x;\n } else {\n- x$1 = $[2];\n+ x = $[2];\n }\n- x$0 = x$1;\n }\n \n y.push(props.p2);\n- const c_3 = $[3] !== x$0;\n+ const c_3 = $[3] !== x;\n const c_4 = $[4] !== y;\n let t0;\n if (c_3 || c_4) {\n- t0 = <\/Component>;\n- $[3] = x$0;\n+ t0 = <\/Component>;\n+ $[3] = x;\n $[4] = y;\n $[5] = t0;\n } else {\ndiff --git a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/reassignment-separate-scopes.expect.md b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/reassignment-separate-scopes.expect.md\nindex f3304c07cd..75eb1aa336 100644\n--- a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/reassignment-separate-scopes.expect.md\n+++ b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/reassignment-separate-scopes.expect.md\n@@ -56,48 +56,43 @@ function foo(a, b, c) {\n } else {\n y = $[3];\n }\n- let x$0 = undefined;\n bb3: switch (b) {\n case 0: {\n const c_4 = $[4] !== b;\n- let x$1;\n if (c_4) {\n- x$1 = [];\n- x$1.push(b);\n+ x = [];\n+ x.push(b);\n $[4] = b;\n- $[5] = x$1;\n+ $[5] = x;\n } else {\n- x$1 = $[5];\n+ x = $[5];\n }\n- x$0 = x$1;\n break bb3;\n }\n default: {\n const c_6 = $[6] !== c;\n- let x$2;\n if (c_6) {\n- x$2 = [];\n- x$2.push(c);\n+ x = [];\n+ x.push(c);\n $[6] = c;\n- $[7] = x$2;\n+ $[7] = x;\n } else {\n- x$2 = $[7];\n+ x = $[7];\n }\n- x$0 = x$2;\n }\n }\n const c_8 = $[8] !== y;\n- const c_9 = $[9] !== x$0;\n+ const c_9 = $[9] !== x;\n let t0;\n if (c_8 || c_9) {\n t0 = (\n

\n {y}\n- {x$0}\n+ {x}\n <\/div>\n );\n $[8] = y;\n- $[9] = x$0;\n+ $[9] = x;\n $[10] = t0;\n } else {\n t0 = $[10];\ndiff --git a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/reassignment.expect.md b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/reassignment.expect.md\nindex bdfbb575f2..3e98a65af9 100644\n--- a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/reassignment.expect.md\n+++ b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/reassignment.expect.md\n@@ -24,34 +24,38 @@ function Component(props) {\n const $ = React.unstable_useMemoCache();\n const c_0 = $[0] !== props.p0;\n const c_1 = $[1] !== props.p1;\n+ let x;\n let y;\n if (c_0 || c_1) {\n- const x = [];\n+ x = [];\n x.push(props.p0);\n y = x;\n- let x$0;\n- if ($[3] === Symbol.for(\"react.memo_cache_sentinel\")) {\n- x$0 = [];\n- $[3] = x$0;\n+ if ($[4] === Symbol.for(\"react.memo_cache_sentinel\")) {\n+ x = [];\n+ $[4] = x;\n } else {\n- x$0 = $[3];\n+ x = $[4];\n }\n \n y.push(props.p1);\n $[0] = props.p0;\n $[1] = props.p1;\n- $[2] = y;\n+ $[2] = x;\n+ $[3] = y;\n } else {\n- y = $[2];\n+ x = $[2];\n+ y = $[3];\n }\n- const c_4 = $[4] !== y;\n+ const c_5 = $[5] !== x;\n+ const c_6 = $[6] !== y;\n let t0;\n- if (c_4) {\n- t0 = <\/Component>;\n- $[4] = y;\n- $[5] = t0;\n+ if (c_5 || c_6) {\n+ t0 = <\/Component>;\n+ $[5] = x;\n+ $[6] = y;\n+ $[7] = t0;\n } else {\n- t0 = $[5];\n+ t0 = $[7];\n }\n return t0;\n }\ndiff --git a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/same-variable-as-dep-and-redeclare-maybe-frozen.expect.md b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/same-variable-as-dep-and-redeclare-maybe-frozen.expect.md\nindex 50fae20d8d..42d6158669 100644\n--- a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/same-variable-as-dep-and-redeclare-maybe-frozen.expect.md\n+++ b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/same-variable-as-dep-and-redeclare-maybe-frozen.expect.md\n@@ -72,33 +72,32 @@ function foo(props) {\n const c_5 = $[5] !== x;\n const c_6 = $[6] !== props.b;\n const c_7 = $[7] !== props.c;\n- let x$0;\n let y;\n if (c_5 || c_6 || c_7) {\n y = [x];\n- x$0 = [];\n+ x = [];\n y.push(props.b);\n- x$0.push(props.c);\n+ x.push(props.c);\n $[5] = x;\n $[6] = props.b;\n $[7] = props.c;\n- $[8] = x$0;\n- $[9] = y;\n+ $[8] = y;\n+ $[9] = x;\n } else {\n- x$0 = $[8];\n- y = $[9];\n+ y = $[8];\n+ x = $[9];\n }\n- const c_10 = $[10] !== x$0;\n+ const c_10 = $[10] !== x;\n const c_11 = $[11] !== y;\n let content;\n if (c_10 || c_11) {\n content = (\n

\n- {x$0}\n+ {x}\n {y}\n <\/div>\n );\n- $[10] = x$0;\n+ $[10] = x;\n $[11] = y;\n $[12] = content;\n } else {\ndiff --git a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/same-variable-as-dep-and-redeclare.expect.md b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/same-variable-as-dep-and-redeclare.expect.md\nindex f975bb3535..db8640faea 100644\n--- a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/same-variable-as-dep-and-redeclare.expect.md\n+++ b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/same-variable-as-dep-and-redeclare.expect.md\n@@ -69,33 +69,32 @@ function foo(props) {\n const c_4 = $[4] !== x;\n const c_5 = $[5] !== props.b;\n const c_6 = $[6] !== props.c;\n- let x$0;\n let y;\n if (c_4 || c_5 || c_6) {\n y = [x];\n- x$0 = [];\n+ x = [];\n y.push(props.b);\n- x$0.push(props.c);\n+ x.push(props.c);\n $[4] = x;\n $[5] = props.b;\n $[6] = props.c;\n- $[7] = x$0;\n- $[8] = y;\n+ $[7] = y;\n+ $[8] = x;\n } else {\n- x$0 = $[7];\n- y = $[8];\n+ y = $[7];\n+ x = $[8];\n }\n- const c_9 = $[9] !== x$0;\n+ const c_9 = $[9] !== x;\n const c_10 = $[10] !== y;\n let content;\n if (c_9 || c_10) {\n content = (\n

\n- {x$0}\n+ {x}\n {y}\n <\/div>\n );\n- $[9] = x$0;\n+ $[9] = x;\n $[10] = y;\n $[11] = content;\n } else {\ndiff --git a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/simple-alias.expect.md b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/simple-alias.expect.md\nindex 5653804149..ae3c97d477 100644\n--- a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/simple-alias.expect.md\n+++ b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/simple-alias.expect.md\n@@ -22,19 +22,19 @@ function foo() {\n function mutate() {}\n function foo() {\n const $ = React.unstable_useMemoCache();\n- let c$1;\n+ let c;\n if ($[0] === Symbol.for(\"react.memo_cache_sentinel\")) {\n- const b = {};\n- const c = {};\n+ let b = {};\n+ c = {};\n const a = b;\n- const b$0 = c;\n- c$1 = a;\n- mutate(a, b$0);\n- $[0] = c$1;\n+ b = c;\n+ c = a;\n+ mutate(a, b);\n+ $[0] = c;\n } else {\n- c$1 = $[0];\n+ c = $[0];\n }\n- return c$1;\n+ return c;\n }\n \n ```\ndiff --git a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/ssa-leave-case.expect.md b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/ssa-leave-case.expect.md\nindex 4c7225c6d8..2923122019 100644\n--- a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/ssa-leave-case.expect.md\n+++ b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/ssa-leave-case.expect.md\n@@ -27,36 +27,34 @@ function Component(props) {\n const c_0 = $[0] !== props.p0;\n const c_1 = $[1] !== props.p1;\n let x;\n- let y$0;\n+ let y;\n if (c_0 || c_1) {\n x = [];\n- const y = undefined;\n- y$0 = y;\n+ y = undefined;\n if (props.p0) {\n x.push(props.p1);\n- const y$1 = x;\n- y$0 = y$1;\n+ y = x;\n }\n $[0] = props.p0;\n $[1] = props.p1;\n $[2] = x;\n- $[3] = y$0;\n+ $[3] = y;\n } else {\n x = $[2];\n- y$0 = $[3];\n+ y = $[3];\n }\n const c_4 = $[4] !== x;\n- const c_5 = $[5] !== y$0;\n+ const c_5 = $[5] !== y;\n let t0;\n if (c_4 || c_5) {\n t0 = (\n \n {x}\n- {y$0}\n+ {y}\n <\/Component>\n );\n $[4] = x;\n- $[5] = y$0;\n+ $[5] = y;\n $[6] = t0;\n } else {\n t0 = $[6];\ndiff --git a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/ssa-nested-partial-phi.expect.md b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/ssa-nested-partial-phi.expect.md\nindex f6c4b97fb7..e8320437f5 100644\n--- a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/ssa-nested-partial-phi.expect.md\n+++ b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/ssa-nested-partial-phi.expect.md\n@@ -19,14 +19,12 @@ function foo(a, b, c) {\n \n ```javascript\n function foo(a, b, c) {\n- const x = a;\n+ let x = a;\n if (b) {\n- let x$0 = x;\n if (c) {\n- const x$1 = c;\n- x$0 = x$1;\n+ x = c;\n }\n- return x$0;\n+ return x;\n }\n }\n \ndiff --git a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/ssa-nested-partial-reassignment.expect.md b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/ssa-nested-partial-reassignment.expect.md\nindex 735903f228..3945cb5fed 100644\n--- a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/ssa-nested-partial-reassignment.expect.md\n+++ b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/ssa-nested-partial-reassignment.expect.md\n@@ -20,18 +20,15 @@ function foo(a, b, c, d, e) {\n \n ```javascript\n function foo(a, b, c, d, e) {\n- const x = null;\n- let x$0 = x;\n+ let x = null;\n if (a) {\n- const x$1 = b;\n- x$0 = x$1;\n+ x = b;\n } else {\n if (c) {\n- const x$2 = d;\n- x$0 = x$2;\n+ x = d;\n }\n }\n- return x$0;\n+ return x;\n }\n \n ```\ndiff --git a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/ssa-non-empty-initializer.expect.md b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/ssa-non-empty-initializer.expect.md\nnew file mode 100644\nindex 0000000000..52f6067f0f\n--- \/dev\/null\n+++ b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/ssa-non-empty-initializer.expect.md\n@@ -0,0 +1,38 @@\n+\n+## Input\n+\n+```javascript\n+function foo(a, b) {\n+ let x = [];\n+ if (a) {\n+ x = 1;\n+ }\n+\n+ let y = x;\n+ return y;\n+}\n+\n+```\n+\n+## Code\n+\n+```javascript\n+function foo(a, b) {\n+ const $ = React.unstable_useMemoCache();\n+ let x;\n+ if ($[0] === Symbol.for(\"react.memo_cache_sentinel\")) {\n+ x = [];\n+ $[0] = x;\n+ } else {\n+ x = $[0];\n+ }\n+ if (a) {\n+ x = 1;\n+ }\n+\n+ const y = x;\n+ return y;\n+}\n+\n+```\n+ \n\\ No newline at end of file\ndiff --git a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/ssa-non-empty-initializer.js b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/ssa-non-empty-initializer.js\nnew file mode 100644\nindex 0000000000..bac6d77518\n--- \/dev\/null\n+++ b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/ssa-non-empty-initializer.js\n@@ -0,0 +1,9 @@\n+function foo(a, b) {\n+ let x = [];\n+ if (a) {\n+ x = 1;\n+ }\n+\n+ let y = x;\n+ return y;\n+}\ndiff --git a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/ssa-renaming-with-mutation.expect.md b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/ssa-renaming-with-mutation.expect.md\nindex 3c5e38086d..0a9ba21030 100644\n--- a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/ssa-renaming-with-mutation.expect.md\n+++ b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/ssa-renaming-with-mutation.expect.md\n@@ -24,26 +24,24 @@ function foo(props) {\n const c_0 = $[0] !== props.bar;\n const c_1 = $[1] !== props.cond;\n const c_2 = $[2] !== props.foo;\n- let x$0;\n+ let x;\n if (c_0 || c_1 || c_2) {\n- const x = [];\n+ x = [];\n x.push(props.bar);\n- x$0 = x;\n if (props.cond) {\n- const x$1 = [];\n- x$1.push(props.foo);\n- x$0 = x$1;\n+ x = [];\n+ x.push(props.foo);\n }\n \n- mut(x$0);\n+ mut(x);\n $[0] = props.bar;\n $[1] = props.cond;\n $[2] = props.foo;\n- $[3] = x$0;\n+ $[3] = x;\n } else {\n- x$0 = $[3];\n+ x = $[3];\n }\n- return x$0;\n+ return x;\n }\n \n ```\ndiff --git a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/ssa-renaming.expect.md b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/ssa-renaming.expect.md\nindex 8e9ec02af8..0dba4e0e3f 100644\n--- a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/ssa-renaming.expect.md\n+++ b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/ssa-renaming.expect.md\n@@ -30,21 +30,18 @@ function foo(props) {\n } else {\n x = $[1];\n }\n- let x$0 = x;\n if (props.cond) {\n const c_2 = $[2] !== props.foo;\n- let x$1;\n if (c_2) {\n- x$1 = [];\n- x$1.push(props.foo);\n+ x = [];\n+ x.push(props.foo);\n $[2] = props.foo;\n- $[3] = x$1;\n+ $[3] = x;\n } else {\n- x$1 = $[3];\n+ x = $[3];\n }\n- x$0 = x$1;\n }\n- return x$0;\n+ return x;\n }\n \n ```\ndiff --git a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/ssa-shadowing.expect.md b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/ssa-shadowing.expect.md\nindex 6e0b1b7f56..0d979655dd 100644\n--- a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/ssa-shadowing.expect.md\n+++ b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/ssa-shadowing.expect.md\n@@ -23,17 +23,15 @@ function Foo(cond) {\n function log() {}\n \n function Foo(cond) {\n- const str = \"\";\n- let str$0 = str;\n+ let str = \"\";\n if (cond) {\n const str_0 = \"other test\";\n log(str_0);\n } else {\n- const str$1 = \"fallthrough test\";\n- str$0 = str$1;\n+ str = \"fallthrough test\";\n }\n \n- log(str$0);\n+ log(str);\n }\n \n ```\ndiff --git a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/switch-non-final-default.expect.md b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/switch-non-final-default.expect.md\nindex 9ddb49f74d..ccdc10f96e 100644\n--- a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/switch-non-final-default.expect.md\n+++ b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/switch-non-final-default.expect.md\n@@ -36,42 +36,38 @@ function Component(props) {\n const c_0 = $[0] !== props.p0;\n const c_1 = $[1] !== props.p2;\n let x;\n- let y$0;\n+ let y;\n if (c_0 || c_1) {\n x = [];\n- const y = undefined;\n- y$0 = y;\n+ y = undefined;\n bb1: switch (props.p0) {\n case 1: {\n break bb1;\n }\n case true: {\n x.push(props.p2);\n- let y$1;\n if ($[4] === Symbol.for(\"react.memo_cache_sentinel\")) {\n- y$1 = [];\n- $[4] = y$1;\n+ y = [];\n+ $[4] = y;\n } else {\n- y$1 = $[4];\n+ y = $[4];\n }\n- y$0 = y$1;\n break bb1;\n }\n default: {\n break bb1;\n }\n case false: {\n- const y$2 = x;\n- y$0 = y$2;\n+ y = x;\n }\n }\n $[0] = props.p0;\n $[1] = props.p2;\n $[2] = x;\n- $[3] = y$0;\n+ $[3] = y;\n } else {\n x = $[2];\n- y$0 = $[3];\n+ y = $[3];\n }\n const c_5 = $[5] !== x;\n let child;\n@@ -82,13 +78,13 @@ function Component(props) {\n } else {\n child = $[6];\n }\n- y$0.push(props.p4);\n- const c_7 = $[7] !== y$0;\n+ y.push(props.p4);\n+ const c_7 = $[7] !== y;\n const c_8 = $[8] !== child;\n let t0;\n if (c_7 || c_8) {\n- t0 = {child}<\/Component>;\n- $[7] = y$0;\n+ t0 = {child}<\/Component>;\n+ $[7] = y;\n $[8] = child;\n $[9] = t0;\n } else {\ndiff --git a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/switch.expect.md b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/switch.expect.md\nindex fa5f40ea80..8234bc3c1f 100644\n--- a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/switch.expect.md\n+++ b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/switch.expect.md\n@@ -32,29 +32,27 @@ function Component(props) {\n const c_1 = $[1] !== props.p2;\n const c_2 = $[2] !== props.p3;\n let x;\n- let y$0;\n+ let y;\n if (c_0 || c_1 || c_2) {\n x = [];\n- const y = undefined;\n- y$0 = y;\n+ y = undefined;\n switch (props.p0) {\n case true: {\n x.push(props.p2);\n x.push(props.p3);\n }\n case false: {\n- const y$1 = x;\n- y$0 = y$1;\n+ y = x;\n }\n }\n $[0] = props.p0;\n $[1] = props.p2;\n $[2] = props.p3;\n $[3] = x;\n- $[4] = y$0;\n+ $[4] = y;\n } else {\n x = $[3];\n- y$0 = $[4];\n+ y = $[4];\n }\n const c_5 = $[5] !== x;\n let child;\n@@ -65,13 +63,13 @@ function Component(props) {\n } else {\n child = $[6];\n }\n- y$0.push(props.p4);\n- const c_7 = $[7] !== y$0;\n+ y.push(props.p4);\n+ const c_7 = $[7] !== y;\n const c_8 = $[8] !== child;\n let t0;\n if (c_7 || c_8) {\n- t0 = {child}<\/Component>;\n- $[7] = y$0;\n+ t0 = {child}<\/Component>;\n+ $[7] = y;\n $[8] = child;\n $[9] = t0;\n } else {\ndiff --git a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/template-literal.expect.md b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/template-literal.expect.md\nindex 9d68dce234..ffdc91c8c3 100644\n--- a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/template-literal.expect.md\n+++ b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/template-literal.expect.md\n@@ -19,9 +19,9 @@ function componentB(props) {\n \n ```javascript\n function componentA(props) {\n- const t = `hello ${props.a}, ${props.b}!`;\n- const t$0 = t + ``;\n- return t$0;\n+ let t = `hello ${props.a}, ${props.b}!`;\n+ t = t + ``;\n+ return t;\n }\n \n function componentB(props) {\ndiff --git a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/update-expression.expect.md b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/update-expression.expect.md\nindex 5e02eb14ff..37a15bf6ec 100644\n--- a\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/update-expression.expect.md\n+++ b\/compiler\/forget\/src\/__tests__\/fixtures\/hir\/update-expression.expect.md\n@@ -16,18 +16,18 @@ function foo(props) {\n ```javascript\n function foo(props) {\n const $ = React.unstable_useMemoCache();\n- const x = props.x;\n- const x$0 = x + 1;\n- const y = x$0;\n- const x$1 = x$0 - 1;\n- const z = x$1;\n- const c_0 = $[0] !== x$1;\n+ let x = props.x;\n+ x = x + 1;\n+ const y = x;\n+ x = x - 1;\n+ const z = x;\n+ const c_0 = $[0] !== x;\n const c_1 = $[1] !== y;\n const c_2 = $[2] !== z;\n let t0;\n if (c_0 || c_1 || c_2) {\n- t0 = { x: x$1, y: y, z: z };\n- $[0] = x$1;\n+ t0 = { x: x, y: y, z: z };\n+ $[0] = x;\n $[1] = y;\n $[2] = z;\n $[3] = t0;\n","files":[{"status":"M","path":"compiler\/forget\/src\/ReactiveScopes\/InferReactiveScopeVariables.ts"},{"status":"M","path":"compiler\/forget\/src\/ReactiveScopes\/PropagateScopeDependencies.ts"},{"status":"M","path":"compiler\/forget\/src\/SSA\/LeaveSSA.ts"},{"status":"A","path":"compiler\/forget\/src\/__tests__\/fixtures\/hir\/assignment-in-nested-if.expect.md"},{"status":"R100","path":"compiler\/forget\/src\/__tests__\/fixtures\/hir\/assignment-in-nested-if.js","previousPath":"compiler\/forget\/src\/__tests__\/fixtures\/hir\/error.assignment-in-nested-if.js"},{"status":"M","path":"compiler\/forget\/src\/__tests__\/fixtures\/hir\/assignment-variations.expect.md"},{"status":"D","path":"compiler\/forget\/src\/__tests__\/fixtures\/hir\/error.assignment-in-nested-if.expect.md"},{"status":"M","path":"compiler\/forget\/src\/__tests__\/fixtures\/hir\/error.inverted-if-else.expect.md"},{"status":"M","path":"compiler\/forget\/src\/__tests__\/fixtures\/hir\/hooks-freeze-possibly-mutable-arguments.expect.md"},{"status":"M","path":"compiler\/forget\/src\/__tests__\/fixtures\/hir\/infer-phi-primitive.expect.md"},{"status":"M","path":"compiler\/forget\/src\/__tests__\/fixtures\/hir\/mutable-lifetime-loops.expect.md"},{"status":"M","path":"compiler\/forget\/src\/__tests__\/fixtures\/hir\/obj-literal-cached-in-if-else.expect.md"},{"status":"M","path":"compiler\/forget\/src\/__tests__\/fixtures\/hir\/obj-literal-mutated-after-if-else.expect.md"},{"status":"M","path":"compiler\/forget\/src\/__tests__\/fixtures\/hir\/obj-mutated-after-if-else.expect.md"},{"status":"M","path":"compiler\/forget\/src\/__tests__\/fixtures\/hir\/primitive-alias-mutate.expect.md"},{"status":"M","path":"compiler\/forget\/src\/__tests__\/fixtures\/hir\/reassignment-conditional.expect.md"},{"status":"M","path":"compiler\/forget\/src\/__tests__\/fixtures\/hir\/reassignment-separate-scopes.expect.md"},{"status":"M","path":"compiler\/forget\/src\/__tests__\/fixtures\/hir\/reassignment.expect.md"},{"status":"M","path":"compiler\/forget\/src\/__tests__\/fixtures\/hir\/same-variable-as-dep-and-redeclare-maybe-frozen.expect.md"},{"status":"M","path":"compiler\/forget\/src\/__tests__\/fixtures\/hir\/same-variable-as-dep-and-redeclare.expect.md"},{"status":"M","path":"compiler\/forget\/src\/__tests__\/fixtures\/hir\/simple-alias.expect.md"},{"status":"M","path":"compiler\/forget\/src\/__tests__\/fixtures\/hir\/ssa-leave-case.expect.md"},{"status":"M","path":"compiler\/forget\/src\/__tests__\/fixtures\/hir\/ssa-nested-partial-phi.expect.md"},{"status":"M","path":"compiler\/forget\/src\/__tests__\/fixtures\/hir\/ssa-nested-partial-reassignment.expect.md"},{"status":"A","path":"compiler\/forget\/src\/__tests__\/fixtures\/hir\/ssa-non-empty-initializer.expect.md"},{"status":"A","path":"compiler\/forget\/src\/__tests__\/fixtures\/hir\/ssa-non-empty-initializer.js"},{"status":"M","path":"compiler\/forget\/src\/__tests__\/fixtures\/hir\/ssa-renaming-with-mutation.expect.md"},{"status":"M","path":"compiler\/forget\/src\/__tests__\/fixtures\/hir\/ssa-renaming.expect.md"},{"status":"M","path":"compiler\/forget\/src\/__tests__\/fixtures\/hir\/ssa-shadowing.expect.md"},{"status":"M","path":"compiler\/forget\/src\/__tests__\/fixtures\/hir\/switch-non-final-default.expect.md"},{"status":"M","path":"compiler\/forget\/src\/__tests__\/fixtures\/hir\/switch.expect.md"},{"status":"M","path":"compiler\/forget\/src\/__tests__\/fixtures\/hir\/template-literal.expect.md"},{"status":"M","path":"compiler\/forget\/src\/__tests__\/fixtures\/hir\/update-expression.expect.md"}],"commit":{"revision":"0d0d3a4038574ba221d88da83b4cadca51757a34","authorEmail":"poteto@users.noreply.github.com","authorName":"Lauren Tan","shortRevision":"0d0d3a4038","authoredAt":"2023-02-15T15:22:03-05:00","subject":"Ensure stable variable names after leaving SSA"}}

dillon1000/react

Files changed