mirror of
https://github.com/danbulant/oxc
synced 2026-05-20 12:48:38 +00:00
feat(minifier): compress (a = b) === null || a === undefined to (a = b) == null (#8637)
This commit is contained in:
sapphi-red
parent
864b8efe1a
commit
2bcbed2d50
2 changed files with 114 additions and 60 deletions
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@ -1,4 +1,4 @@
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use oxc_allocator::Vec;
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use oxc_allocator::{CloneIn, Vec};
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use oxc_ast::{ast::*, NONE};
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use oxc_ecmascript::{
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constant_evaluation::{ConstantEvaluation, ValueType},
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@ -331,6 +331,9 @@ impl<'a, 'b> PeepholeOptimizations {
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/// `foo === null || foo === undefined` => `foo == null`
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/// `foo !== null && foo !== undefined` => `foo != null`
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///
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/// Also supports `(a = foo.bar) === null || a === undefined` which commonly happens when
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/// optional chaining is lowered. (`(a=foo.bar)==null`)
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///
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/// This compression assumes that `document.all` is a normal object.
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/// If that assumption does not hold, this compression is not allowed.
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/// - `document.all === null || document.all === undefined` is `false`
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@ -346,8 +349,8 @@ impl<'a, 'b> PeepholeOptimizations {
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LogicalOperator::Coalesce => return None,
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};
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if let Some(new_expr) = Self::try_compress_is_null_or_undefined_for_left_and_right(
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&expr.left,
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&expr.right,
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&mut expr.left,
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&mut expr.right,
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expr.span,
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target_ops,
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ctx,
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@ -360,10 +363,11 @@ impl<'a, 'b> PeepholeOptimizations {
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if left.operator != op {
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return None;
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}
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let new_span = Span::new(left.right.span().start, expr.span.end);
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Self::try_compress_is_null_or_undefined_for_left_and_right(
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&left.right,
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&expr.right,
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Span::new(left.right.span().start, expr.span.end),
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&mut left.right,
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&mut expr.right,
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new_span,
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target_ops,
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ctx,
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)
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@ -378,60 +382,93 @@ impl<'a, 'b> PeepholeOptimizations {
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}
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fn try_compress_is_null_or_undefined_for_left_and_right(
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left: &Expression<'a>,
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right: &Expression<'a>,
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left: &mut Expression<'a>,
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right: &mut Expression<'a>,
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span: Span,
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(find_op, replace_op): (BinaryOperator, BinaryOperator),
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ctx: Ctx<'a, 'b>,
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) -> Option<Expression<'a>> {
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let pair = Self::commutative_pair(
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(&left, &right),
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|a| {
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if let Expression::BinaryExpression(op) = a {
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if op.operator == find_op {
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return Self::commutative_pair(
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(&op.left, &op.right),
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|a_a| a_a.is_null().then_some(a_a.span()),
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|a_b| {
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if let Expression::Identifier(id) = a_b {
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Some((a_b.span(), (*id).clone()))
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} else {
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None
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}
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},
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);
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}
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}
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None
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},
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|b| {
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if let Expression::BinaryExpression(op) = b {
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if op.operator == find_op {
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return Self::commutative_pair(
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(&op.left, &op.right),
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|b_a| b_a.evaluate_to_undefined().then_some(()),
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|b_b| {
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if let Expression::Identifier(id) = b_b {
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Some((*id).clone())
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} else {
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None
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}
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},
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)
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.map(|v| v.1);
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}
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}
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None
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},
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);
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let ((null_expr_span, (left_id_expr_span, left_id_ref)), right_id_ref) = pair?;
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if left_id_ref.name != right_id_ref.name {
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enum LeftPairValueResult {
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Null(Span),
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Undefined,
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}
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let (
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Expression::BinaryExpression(left_binary_expr),
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Expression::BinaryExpression(right_binary_expr),
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) = (left, right)
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else {
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return None;
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};
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if left_binary_expr.operator != find_op || right_binary_expr.operator != find_op {
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return None;
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}
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let left_id_expr =
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ctx.ast.expression_identifier_reference(left_id_expr_span, left_id_ref.name);
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let null_expr = ctx.ast.expression_null_literal(null_expr_span);
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Some(ctx.ast.expression_binary(span, left_id_expr, replace_op, null_expr))
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let is_null_or_undefined = |a: &Expression| {
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if a.is_null() {
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Some(LeftPairValueResult::Null(a.span()))
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} else if a.evaluate_to_undefined() {
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Some(LeftPairValueResult::Undefined)
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} else {
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None
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}
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};
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let is_id_or_assign_to_id = |b: &Expression| match b {
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Expression::Identifier(id) => Some(id.name.clone_in(ctx.ast.allocator)),
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Expression::AssignmentExpression(assign_expr) => {
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if assign_expr.operator == AssignmentOperator::Assign {
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if let AssignmentTarget::AssignmentTargetIdentifier(id) = &assign_expr.left {
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return Some(id.name.clone_in(ctx.ast.allocator));
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}
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}
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None
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}
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_ => None,
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};
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let (left_value, (left_non_value_expr, left_id_name)) = {
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let left_value;
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let left_non_value;
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if let Some(v) = is_null_or_undefined(&left_binary_expr.left) {
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left_value = v;
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let left_non_value_id = is_id_or_assign_to_id(&left_binary_expr.right)?;
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left_non_value = (&mut left_binary_expr.right, left_non_value_id);
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} else {
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left_value = is_null_or_undefined(&left_binary_expr.right)?;
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let left_non_value_id = is_id_or_assign_to_id(&left_binary_expr.left)?;
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left_non_value = (&mut left_binary_expr.left, left_non_value_id);
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}
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(left_value, left_non_value)
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};
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let (right_value, right_id) = Self::commutative_pair(
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(&right_binary_expr.left, &right_binary_expr.right),
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|a| match left_value {
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LeftPairValueResult::Null(_) => a.evaluate_to_undefined().then_some(None),
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LeftPairValueResult::Undefined => a.is_null().then_some(Some(a.span())),
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},
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|b| {
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if let Expression::Identifier(id) = b {
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Some(id)
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} else {
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None
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}
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},
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)?;
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if left_id_name != right_id.name {
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return None;
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}
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let null_expr_span = match left_value {
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LeftPairValueResult::Null(span) => span,
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LeftPairValueResult::Undefined => right_value.unwrap(),
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};
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Some(ctx.ast.expression_binary(
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span,
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ctx.ast.move_expression(left_non_value_expr),
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replace_op,
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ctx.ast.expression_null_literal(null_expr_span),
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))
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}
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/// Compress `a || (a = b)` to `a ||= b`
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@ -539,14 +576,14 @@ impl<'a, 'b> PeepholeOptimizations {
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}
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}
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fn commutative_pair<A, F, G, RetF: 'a, RetG: 'a>(
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pair: (&A, &A),
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fn commutative_pair<'x, A, F, G, RetF: 'x, RetG: 'x>(
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pair: (&'x A, &'x A),
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check_a: F,
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check_b: G,
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) -> Option<(RetF, RetG)>
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where
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F: Fn(&A) -> Option<RetF>,
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G: Fn(&A) -> Option<RetG>,
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F: Fn(&'x A) -> Option<RetF>,
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G: Fn(&'x A) -> Option<RetG>,
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{
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if let Some(a) = check_a(pair.0) {
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if let Some(b) = check_b(pair.1) {
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@ -559,6 +596,7 @@ impl<'a, 'b> PeepholeOptimizations {
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}
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None
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}
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fn try_fold_loose_equals_undefined(
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e: &mut BinaryExpression<'a>,
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ctx: Ctx<'a, 'b>,
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@ -1782,6 +1820,22 @@ mod test {
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test("foo !== 1 && foo !== null && foo !== void 0", "foo !== 1 && foo != null");
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test("foo !== 1 || foo !== void 0 && foo !== null", "foo !== 1 || foo != null");
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test_same("foo !== void 0 && bar !== null");
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test("(_foo = foo) === null || _foo === undefined", "(_foo = foo) == null");
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test("(_foo = foo) === null || _foo === void 0", "(_foo = foo) == null");
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test("(_foo = foo.bar) === null || _foo === undefined", "(_foo = foo.bar) == null");
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test("(_foo = foo) !== null && _foo !== undefined", "(_foo = foo) != null");
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test("(_foo = foo) === undefined || _foo === null", "(_foo = foo) == null");
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test("(_foo = foo) === void 0 || _foo === null", "(_foo = foo) == null");
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test(
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"(_foo = foo) === null || _foo === void 0 || _foo === 1",
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"(_foo = foo) == null || _foo === 1",
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);
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test(
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"_foo === 1 || (_foo = foo) === null || _foo === void 0",
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"_foo === 1 || (_foo = foo) == null",
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);
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test_same("(_foo = foo) === void 0 || bar === null");
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}
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#[test]
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@ -21,7 +21,7 @@ Original | minified | minified | gzip | gzip | Fixture
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3.20 MB | 1.01 MB | 1.01 MB | 332.00 kB | 331.56 kB | echarts.js
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6.69 MB | 2.31 MB | 2.31 MB | 492.53 kB | 488.28 kB | antd.js
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6.69 MB | 2.31 MB | 2.31 MB | 491.99 kB | 488.28 kB | antd.js
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10.95 MB | 3.49 MB | 3.49 MB | 907.24 kB | 915.50 kB | typescript.js
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10.95 MB | 3.48 MB | 3.49 MB | 905.39 kB | 915.50 kB | typescript.js
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