Skip to content

fix: simplify && and || when the LHS is constant #2947

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 2 commits into from
Sep 8, 2025
Merged

fix: simplify && and || when the LHS is constant #2947

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
2ea0db0
fix: simplify && and || when the LHS is constant
CountBleck Sep 7, 2025
fd9c479
Add tests for simplifying non-boolean && and ||
CountBleck Sep 7, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
44 changes: 34 additions & 10 deletions src/compiler.ts
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -4574,19 +4574,31 @@ export class Compiler extends DiagnosticEmitter {
}
leftExpr = this.convertExpression(leftExpr, leftType, commonType, false, left);
leftType = commonType;

// This is sometimes needed to make the left trivial
let leftPrecompExpr = module.runExpression(leftExpr, ExpressionRunnerFlags.PreserveSideeffects);
if (leftPrecompExpr) leftExpr = leftPrecompExpr;

rightExpr = this.convertExpression(rightExpr, rightType, commonType, false, right);
rightType = commonType;

// simplify if copying left is trivial
if (expr = module.tryCopyTrivialExpression(leftExpr)) {
let condExpr = this.makeIsTrueish(leftExpr, this.currentType, left);
let condKind = this.evaluateCondition(condExpr);

if (condKind != ConditionKind.Unknown) {
// simplify if left is a constant
expr = condKind == ConditionKind.True
? rightExpr
: leftExpr;
} else if (expr = module.tryCopyTrivialExpression(leftExpr)) {
// simplify if copying left is trivial
expr = module.if(
this.makeIsTrueish(leftExpr, this.currentType, left),
condExpr,
rightExpr,
expr
);

// if not possible, tee left to a temp
} else {
// if not possible, tee left to a temp
let tempLocal = flow.getTempLocal(leftType);
if (!flow.canOverflow(leftExpr, leftType)) flow.setLocalFlag(tempLocal.index, LocalFlags.Wrapped);
if (flow.isNonnull(leftExpr, leftType)) flow.setLocalFlag(tempLocal.index, LocalFlags.NonNull);
Expand Down Expand Up @@ -4654,19 +4666,31 @@ export class Compiler extends DiagnosticEmitter {
let possiblyNull = leftType.is(TypeFlags.Nullable) && rightType.is(TypeFlags.Nullable);
leftExpr = this.convertExpression(leftExpr, leftType, commonType, false, left);
leftType = commonType;

// This is sometimes needed to make the left trivial
let leftPrecompExpr = module.runExpression(leftExpr, ExpressionRunnerFlags.PreserveSideeffects);
if (leftPrecompExpr) leftExpr = leftPrecompExpr;

rightExpr = this.convertExpression(rightExpr, rightType, commonType, false, right);
rightType = commonType;

// simplify if copying left is trivial
if (expr = module.tryCopyTrivialExpression(leftExpr)) {
let condExpr = this.makeIsTrueish(leftExpr, this.currentType, left);
let condKind = this.evaluateCondition(condExpr);

if (condKind != ConditionKind.Unknown) {
// simplify if left is a constant
expr = condKind == ConditionKind.True
? leftExpr
: rightExpr;
} else if (expr = module.tryCopyTrivialExpression(leftExpr)) {
// otherwise, simplify if copying left is trivial
expr = module.if(
this.makeIsTrueish(leftExpr, leftType, left),
condExpr,
expr,
rightExpr
);

// if not possible, tee left to a temp. local
} else {
// if not possible, tee left to a temp. local
let temp = flow.getTempLocal(leftType);
let tempIndex = temp.index;
if (!flow.canOverflow(leftExpr, leftType)) flow.setLocalFlag(tempIndex, LocalFlags.Wrapped);
Expand Down
Loading
Loading