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Omit effects-free conditional constructs from control flow graph #58013

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merged 3 commits into from
Apr 4, 2024
Merged

Omit effects-free conditional constructs from control flow graph #58013

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154a057
Omit effects-free conditional constructs from control flow graph
ahejlsberg Mar 31, 2024
107c5ff
Optimize isNarrowableReference
ahejlsberg Mar 31, 2024
6bdaaf7
Merge branch 'main' into optimizeFlowGraph
ahejlsberg Apr 1, 2024
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50 changes: 39 additions & 11 deletions src/compiler/binder.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -146,7 +146,6 @@ import {
isDeclarationStatement,
isDestructuringAssignment,
isDottedName,
isElementAccessExpression,
isEmptyObjectLiteral,
isEntityNameExpression,
isEnumConst,
Expand Down Expand Up @@ -188,7 +187,6 @@ import {
isModuleExportsAccessExpression,
isNamedDeclaration,
isNamespaceExport,
isNonNullExpression,
isNullishCoalesce,
isObjectLiteralExpression,
isObjectLiteralMethod,
Expand Down Expand Up @@ -540,6 +538,7 @@ function createBinder(): (file: SourceFile, options: CompilerOptions) => void {
var preSwitchCaseFlow: FlowNode | undefined;
var activeLabelList: ActiveLabel | undefined;
var hasExplicitReturn: boolean;
var hasFlowEffects: boolean;

// state used for emit helpers
var emitFlags: NodeFlags;
Expand Down Expand Up @@ -618,6 +617,7 @@ function createBinder(): (file: SourceFile, options: CompilerOptions) => void {
currentExceptionTarget = undefined;
activeLabelList = undefined;
hasExplicitReturn = false;
hasFlowEffects = false;
inAssignmentPattern = false;
emitFlags = NodeFlags.None;
}
Expand Down Expand Up @@ -1223,8 +1223,8 @@ function createBinder(): (file: SourceFile, options: CompilerOptions) => void {
function isNarrowingExpression(expr: Expression): boolean {
switch (expr.kind) {
case SyntaxKind.Identifier:
case SyntaxKind.PrivateIdentifier:
case SyntaxKind.ThisKeyword:
return true;
case SyntaxKind.PropertyAccessExpression:
case SyntaxKind.ElementAccessExpression:
return containsNarrowableReference(expr);
Expand All @@ -1248,11 +1248,24 @@ function createBinder(): (file: SourceFile, options: CompilerOptions) => void {
}

function isNarrowableReference(expr: Expression): boolean {
return isDottedName(expr)
|| (isPropertyAccessExpression(expr) || isNonNullExpression(expr) || isParenthesizedExpression(expr)) && isNarrowableReference(expr.expression)
|| isBinaryExpression(expr) && expr.operatorToken.kind === SyntaxKind.CommaToken && isNarrowableReference(expr.right)
|| isElementAccessExpression(expr) && (isStringOrNumericLiteralLike(expr.argumentExpression) || isEntityNameExpression(expr.argumentExpression)) && isNarrowableReference(expr.expression)
|| isAssignmentExpression(expr) && isNarrowableReference(expr.left);
switch (expr.kind) {
case SyntaxKind.Identifier:
case SyntaxKind.ThisKeyword:
case SyntaxKind.SuperKeyword:
case SyntaxKind.MetaProperty:
return true;
case SyntaxKind.PropertyAccessExpression:
case SyntaxKind.ParenthesizedExpression:
case SyntaxKind.NonNullExpression:
return isNarrowableReference((expr as PropertyAccessExpression | ParenthesizedExpression | NonNullExpression).expression);
case SyntaxKind.ElementAccessExpression:
return (isStringOrNumericLiteralLike((expr as ElementAccessExpression).argumentExpression) || isEntityNameExpression((expr as ElementAccessExpression).argumentExpression)) &&
isNarrowableReference((expr as ElementAccessExpression).expression);
case SyntaxKind.BinaryExpression:
return (expr as BinaryExpression).operatorToken.kind === SyntaxKind.CommaToken && isNarrowableReference((expr as BinaryExpression).right) ||
isAssignmentOperator((expr as BinaryExpression).operatorToken.kind) && isLeftHandSideExpression((expr as BinaryExpression).left);
}
return false;
}

function containsNarrowableReference(expr: Expression): boolean {
Expand Down Expand Up @@ -1371,6 +1384,7 @@ function createBinder(): (file: SourceFile, options: CompilerOptions) => void {

function createFlowMutation(flags: FlowFlags, antecedent: FlowNode, node: Expression | VariableDeclaration | ArrayBindingElement): FlowNode {
setFlowNodeReferenced(antecedent);
hasFlowEffects = true;
const result = initFlowNode({ flags, antecedent, node });
if (currentExceptionTarget) {
addAntecedent(currentExceptionTarget, result);
Expand All @@ -1380,6 +1394,7 @@ function createBinder(): (file: SourceFile, options: CompilerOptions) => void {

function createFlowCall(antecedent: FlowNode, node: CallExpression): FlowNode {
setFlowNodeReferenced(antecedent);
hasFlowEffects = true;
return initFlowNode({ flags: FlowFlags.Call, antecedent, node });
}

Expand Down Expand Up @@ -1559,6 +1574,7 @@ function createBinder(): (file: SourceFile, options: CompilerOptions) => void {
}
}
currentFlow = unreachableFlow;
hasFlowEffects = true;
}

function findActiveLabel(name: __String) {
Expand All @@ -1575,6 +1591,7 @@ function createBinder(): (file: SourceFile, options: CompilerOptions) => void {
if (flowLabel) {
addAntecedent(flowLabel, currentFlow);
currentFlow = unreachableFlow;
hasFlowEffects = true;
}
}

Expand Down Expand Up @@ -1904,8 +1921,12 @@ function createBinder(): (file: SourceFile, options: CompilerOptions) => void {
if (isLogicalOrCoalescingBinaryOperator(operator) || isLogicalOrCoalescingAssignmentOperator(operator)) {
if (isTopLevelLogicalExpression(node)) {
const postExpressionLabel = createBranchLabel();
const saveCurrentFlow = currentFlow;
const saveHasFlowEffects = hasFlowEffects;
hasFlowEffects = false;
bindLogicalLikeExpression(node, postExpressionLabel, postExpressionLabel);
currentFlow = finishFlowLabel(postExpressionLabel);
currentFlow = hasFlowEffects ? finishFlowLabel(postExpressionLabel) : saveCurrentFlow;
hasFlowEffects ||= saveHasFlowEffects;
}
else {
bindLogicalLikeExpression(node, currentTrueTarget!, currentFalseTarget!);
Expand Down Expand Up @@ -1985,6 +2006,9 @@ function createBinder(): (file: SourceFile, options: CompilerOptions) => void {
const trueLabel = createBranchLabel();
const falseLabel = createBranchLabel();
const postExpressionLabel = createBranchLabel();
const saveCurrentFlow = currentFlow;
const saveHasFlowEffects = hasFlowEffects;
hasFlowEffects = false;
bindCondition(node.condition, trueLabel, falseLabel);
currentFlow = finishFlowLabel(trueLabel);
bind(node.questionToken);
Expand All @@ -1994,7 +2018,8 @@ function createBinder(): (file: SourceFile, options: CompilerOptions) => void {
bind(node.colonToken);
bind(node.whenFalse);
addAntecedent(postExpressionLabel, currentFlow);
currentFlow = finishFlowLabel(postExpressionLabel);
currentFlow = hasFlowEffects ? finishFlowLabel(postExpressionLabel) : saveCurrentFlow;
hasFlowEffects ||= saveHasFlowEffects;
}

function bindInitializedVariableFlow(node: VariableDeclaration | ArrayBindingElement) {
Expand Down Expand Up @@ -2134,8 +2159,11 @@ function createBinder(): (file: SourceFile, options: CompilerOptions) => void {
function bindOptionalChainFlow(node: OptionalChain) {
if (isTopLevelLogicalExpression(node)) {
const postExpressionLabel = createBranchLabel();
const saveCurrentFlow = currentFlow;
const saveHasFlowEffects = hasFlowEffects;
bindOptionalChain(node, postExpressionLabel, postExpressionLabel);
currentFlow = finishFlowLabel(postExpressionLabel);
currentFlow = hasFlowEffects ? finishFlowLabel(postExpressionLabel) : saveCurrentFlow;
hasFlowEffects ||= saveHasFlowEffects;
}
else {
bindOptionalChain(node, currentTrueTarget!, currentFalseTarget!);
Expand Down