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refactor(minifier): clean up remove_unused_expression #13080

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Merged
merged 1 commit into from
Aug 14, 2025
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refactor(minifier): clean up remove_unused_expression #13080

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10 changes: 4 additions & 6 deletions crates/oxc_ecmascript/src/side_effects/may_have_side_effects.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -529,20 +529,18 @@ fn get_array_minimum_length(arr: &ArrayExpression) -> usize {
impl<'a> MayHaveSideEffects<'a> for CallExpression<'a> {
fn may_have_side_effects(&self, ctx: &impl MayHaveSideEffectsContext<'a>) -> bool {
if (self.pure && ctx.annotations()) || ctx.manual_pure_functions(&self.callee) {
self.arguments.iter().any(|e| e.may_have_side_effects(ctx))
} else {
true
return self.arguments.iter().any(|e| e.may_have_side_effects(ctx));
}
true
}
}

impl<'a> MayHaveSideEffects<'a> for NewExpression<'a> {
fn may_have_side_effects(&self, ctx: &impl MayHaveSideEffectsContext<'a>) -> bool {
if (self.pure && ctx.annotations()) || ctx.manual_pure_functions(&self.callee) {
self.arguments.iter().any(|e| e.may_have_side_effects(ctx))
} else {
true
return self.arguments.iter().any(|e| e.may_have_side_effects(ctx));
}
true
}
}

Expand Down
4 changes: 2 additions & 2 deletions crates/oxc_minifier/src/peephole/mod.rs
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Expand Up @@ -255,7 +255,7 @@ impl<'a> Traverse<'a, MinifierState<'a>> for PeepholeOptimizations {
Self::try_compress_normal_assignment_to_combined_logical_assignment(e, ctx);
Self::try_compress_normal_assignment_to_combined_assignment(e, ctx);
Self::try_compress_assignment_to_update_expression(expr, ctx);
Self::remove_unused_assignment_expression(expr, ctx);
Self::remove_unused_assignment_expr(expr, ctx);
}
Expression::SequenceExpression(_) => Self::try_fold_sequence_expression(expr, ctx),
Expression::ArrowFunctionExpression(e) => Self::try_compress_arrow_expression(e, ctx),
Expand Down Expand Up @@ -497,7 +497,7 @@ impl<'a> Traverse<'a, MinifierState<'a>> for DeadCodeElimination {
PeepholeOptimizations::try_fold_sequence_expression(e, ctx);
}
Expression::AssignmentExpression(_) => {
PeepholeOptimizations::remove_unused_assignment_expression(e, ctx);
PeepholeOptimizations::remove_unused_assignment_expr(e, ctx);
}
_ => {}
}
Expand Down
55 changes: 24 additions & 31 deletions crates/oxc_minifier/src/peephole/remove_unused_expression.rs
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Expand Up @@ -17,25 +17,23 @@ impl<'a> PeepholeOptimizations {
/// `SimplifyUnusedExpr`: <https://github.com/evanw/esbuild/blob/v0.24.2/internal/js_ast/js_ast_helpers.go#L534>
pub fn remove_unused_expression(e: &mut Expression<'a>, ctx: &mut Ctx<'a, '_>) -> bool {
match e {
Expression::ArrayExpression(_) => Self::fold_array_expression(e, ctx),
Expression::UnaryExpression(_) => Self::fold_unary_expression(e, ctx),
Expression::NewExpression(_) => Self::fold_new_constructor(e, ctx),
Expression::LogicalExpression(_) => Self::fold_logical_expression(e, ctx),
Expression::SequenceExpression(_) => Self::fold_sequence_expression(e, ctx),
Expression::TemplateLiteral(_) => Self::fold_template_literal(e, ctx),
Expression::ObjectExpression(_) => Self::fold_object_expression(e, ctx),
Expression::ConditionalExpression(_) => Self::fold_conditional_expression(e, ctx),
Expression::BinaryExpression(_) => Self::fold_binary_expression(e, ctx),
Expression::CallExpression(_) => Self::remove_unused_call_expression(e, ctx),
Expression::AssignmentExpression(_) => {
Self::remove_unused_assignment_expression(e, ctx)
}
Expression::ClassExpression(_) => Self::remove_unused_class_expression(e, ctx),
Expression::ArrayExpression(_) => Self::remove_unused_array_expr(e, ctx),
Expression::AssignmentExpression(_) => Self::remove_unused_assignment_expr(e, ctx),
Expression::BinaryExpression(_) => Self::remove_unused_binary_expr(e, ctx),
Expression::CallExpression(_) => Self::remove_unused_call_expr(e, ctx),
Expression::ClassExpression(_) => Self::remove_unused_class_expr(e, ctx),
Expression::ConditionalExpression(_) => Self::remove_unused_conditional_expr(e, ctx),
Expression::LogicalExpression(_) => Self::remove_unused_logical_expr(e, ctx),
Expression::NewExpression(_) => Self::remove_unused_new_expr(e, ctx),
Expression::ObjectExpression(_) => Self::remove_unused_object_expr(e, ctx),
Expression::SequenceExpression(_) => Self::remove_unused_sequence_expr(e, ctx),
Expression::TemplateLiteral(_) => Self::remove_unused_template_literal(e, ctx),
Expression::UnaryExpression(_) => Self::remove_unused_unary_expr(e, ctx),
_ => !e.may_have_side_effects(ctx),
}
}

fn fold_unary_expression(e: &mut Expression<'a>, ctx: &mut Ctx<'a, '_>) -> bool {
fn remove_unused_unary_expr(e: &mut Expression<'a>, ctx: &mut Ctx<'a, '_>) -> bool {
let Expression::UnaryExpression(unary_expr) = e else { return false };
match unary_expr.operator {
UnaryOperator::Void | UnaryOperator::LogicalNot => {
Expand All @@ -56,19 +54,17 @@ impl<'a> PeepholeOptimizations {
}
}

fn fold_sequence_expression(e: &mut Expression<'a>, ctx: &mut Ctx<'a, '_>) -> bool {
fn remove_unused_sequence_expr(e: &mut Expression<'a>, ctx: &mut Ctx<'a, '_>) -> bool {
let Expression::SequenceExpression(sequence_expr) = e else { return false };

let old_len = sequence_expr.expressions.len();
sequence_expr.expressions.retain_mut(|e| !Self::remove_unused_expression(e, ctx));
if sequence_expr.expressions.len() != old_len {
ctx.state.changed = true;
}

sequence_expr.expressions.is_empty()
}

fn fold_logical_expression(e: &mut Expression<'a>, ctx: &mut Ctx<'a, '_>) -> bool {
fn remove_unused_logical_expr(e: &mut Expression<'a>, ctx: &mut Ctx<'a, '_>) -> bool {
let Expression::LogicalExpression(logical_expr) = e else { return false };
if !logical_expr.operator.is_coalesce() {
Self::try_fold_expr_in_boolean_context(&mut logical_expr.left, ctx);
Expand Down Expand Up @@ -166,7 +162,7 @@ impl<'a> PeepholeOptimizations {
}

// `([1,2,3, foo()])` -> `foo()`
fn fold_array_expression(e: &mut Expression<'a>, ctx: &mut Ctx<'a, '_>) -> bool {
fn remove_unused_array_expr(e: &mut Expression<'a>, ctx: &mut Ctx<'a, '_>) -> bool {
let Expression::ArrayExpression(array_expr) = e else {
return false;
};
Expand Down Expand Up @@ -216,7 +212,7 @@ impl<'a> PeepholeOptimizations {
false
}

fn fold_new_constructor(e: &mut Expression<'a>, ctx: &mut Ctx<'a, '_>) -> bool {
fn remove_unused_new_expr(e: &mut Expression<'a>, ctx: &mut Ctx<'a, '_>) -> bool {
let Expression::NewExpression(new_expr) = e else { return false };
if new_expr.pure && ctx.annotations() {
let mut exprs =
Expand All @@ -236,7 +232,7 @@ impl<'a> PeepholeOptimizations {
}

// "`${1}2${foo()}3`" -> "`${foo()}`"
fn fold_template_literal(e: &mut Expression<'a>, ctx: &mut Ctx<'a, '_>) -> bool {
fn remove_unused_template_literal(e: &mut Expression<'a>, ctx: &mut Ctx<'a, '_>) -> bool {
let Expression::TemplateLiteral(temp_lit) = e else { return false };
if temp_lit.expressions.is_empty() {
return true;
Expand Down Expand Up @@ -316,7 +312,7 @@ impl<'a> PeepholeOptimizations {
}

// `({ 1: 1, [foo()]: bar() })` -> `foo(), bar()`
fn fold_object_expression(e: &mut Expression<'a>, ctx: &mut Ctx<'a, '_>) -> bool {
fn remove_unused_object_expr(e: &mut Expression<'a>, ctx: &mut Ctx<'a, '_>) -> bool {
let Expression::ObjectExpression(object_expr) = e else {
return false;
};
Expand Down Expand Up @@ -381,7 +377,7 @@ impl<'a> PeepholeOptimizations {
false
}

fn fold_conditional_expression(e: &mut Expression<'a>, ctx: &mut Ctx<'a, '_>) -> bool {
fn remove_unused_conditional_expr(e: &mut Expression<'a>, ctx: &mut Ctx<'a, '_>) -> bool {
let Expression::ConditionalExpression(conditional_expr) = e else {
return false;
};
Expand Down Expand Up @@ -429,7 +425,7 @@ impl<'a> PeepholeOptimizations {
false
}

fn fold_binary_expression(e: &mut Expression<'a>, ctx: &mut Ctx<'a, '_>) -> bool {
fn remove_unused_binary_expr(e: &mut Expression<'a>, ctx: &mut Ctx<'a, '_>) -> bool {
let Expression::BinaryExpression(binary_expr) = e else {
return false;
};
Expand Down Expand Up @@ -522,7 +518,7 @@ impl<'a> PeepholeOptimizations {
false
}

fn remove_unused_call_expression(e: &mut Expression<'a>, ctx: &mut Ctx<'a, '_>) -> bool {
fn remove_unused_call_expr(e: &mut Expression<'a>, ctx: &mut Ctx<'a, '_>) -> bool {
let Expression::CallExpression(call_expr) = e else { return false };

if call_expr.pure && ctx.annotations() {
Expand Down Expand Up @@ -601,10 +597,7 @@ impl<'a> PeepholeOptimizations {
}))
}

pub fn remove_unused_assignment_expression(
e: &mut Expression<'a>,
ctx: &mut Ctx<'a, '_>,
) -> bool {
pub fn remove_unused_assignment_expr(e: &mut Expression<'a>, ctx: &mut Ctx<'a, '_>) -> bool {
let Expression::AssignmentExpression(assign_expr) = e else { return false };
if matches!(
ctx.state.options.unused,
Expand Down Expand Up @@ -646,7 +639,7 @@ impl<'a> PeepholeOptimizations {
false
}

fn remove_unused_class_expression(e: &mut Expression<'a>, ctx: &mut Ctx<'a, '_>) -> bool {
fn remove_unused_class_expr(e: &mut Expression<'a>, ctx: &mut Ctx<'a, '_>) -> bool {
let Expression::ClassExpression(c) = e else { return false };
if let Some(exprs) = Self::remove_unused_class(c, ctx) {
if exprs.is_empty() {
Expand Down
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