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feat(minifier): compress (a = _a) != null ? a : b and (a = _a) != null ? a.b() : undefined #8823

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Feb 2, 2025
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feat(minifier): compress (a = _a) != null ? a : b and (a = _a) != null ? a.b() : undefined #8823

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214 changes: 139 additions & 75 deletions crates/oxc_minifier/src/peephole/minimize_conditions.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -577,32 +577,43 @@ impl<'a> PeepholeOptimizations {

// Try using the "??" or "?." operators
if self.target >= ESTarget::ES2020 {
if let Expression::BinaryExpression(test_binary) = &expr.test {
if let Expression::BinaryExpression(test_binary) = &mut expr.test {
if let Some(is_negate) = match test_binary.operator {
BinaryOperator::Inequality => Some(true),
BinaryOperator::Equality => Some(false),
_ => None,
} {
// a == null / a != null
if let Some((id_expr, ())) = Self::commutative_pair(
(&test_binary.left, &test_binary.right),
|a| {
if let Expression::Identifier(id) = a {
(!ctx.is_global_reference(id)).then_some(a)
} else {
None
}
},
|b| b.is_null().then_some(()),
) {
// a == null / a != null / (a = foo) == null / (a = foo) != null
let value_expr_with_id_name = if test_binary.left.is_null() {
if let Some(id) = Self::extract_id_or_assign_to_id(&test_binary.right)
.filter(|id| !ctx.is_global_reference(id))
{
Some((id.name, &mut test_binary.right))
} else {
None
}
} else if test_binary.right.is_null() {
if let Some(id) = Self::extract_id_or_assign_to_id(&test_binary.left)
.filter(|id| !ctx.is_global_reference(id))
{
Some((id.name, &mut test_binary.left))
} else {
None
}
} else {
None
};
if let Some((target_id_name, value_expr)) = value_expr_with_id_name {
// `a == null ? b : a` -> `a ?? b`
// `a != null ? a : b` -> `a ?? b`
let target_expr =
// `(a = foo) == null ? b : a` -> `(a = foo) ?? b`
// `(a = foo) != null ? a : b` -> `(a = foo) ?? b`
let maybe_same_id_expr =
if is_negate { &mut expr.consequent } else { &mut expr.alternate };
if id_expr.content_eq(target_expr) {
if maybe_same_id_expr.is_specific_id(&target_id_name) {
return Some(ctx.ast.expression_logical(
expr.span,
ctx.ast.move_expression(target_expr),
ctx.ast.move_expression(value_expr),
LogicalOperator::Coalesce,
ctx.ast.move_expression(if is_negate {
&mut expr.alternate
Expand All @@ -614,13 +625,16 @@ impl<'a> PeepholeOptimizations {

// "a == null ? undefined : a.b.c[d](e)" => "a?.b.c[d](e)"
// "a != null ? a.b.c[d](e) : undefined" => "a?.b.c[d](e)"
let target_expr =
// "(a = foo) == null ? undefined : a.b.c[d](e)" => "(a = foo)?.b.c[d](e)"
// "(a = foo) != null ? a.b.c[d](e) : undefined" => "(a = foo)?.b.c[d](e)"
let maybe_undefined_expr =
if is_negate { &expr.alternate } else { &expr.consequent };
if ctx.is_expression_undefined(target_expr) {
if ctx.is_expression_undefined(maybe_undefined_expr) {
let expr_to_inject_optional_chaining =
if is_negate { &mut expr.consequent } else { &mut expr.alternate };
if Self::inject_optional_chaining_if_matched(
id_expr,
&target_id_name,
value_expr,
expr_to_inject_optional_chaining,
ctx,
) {
Expand Down Expand Up @@ -698,85 +712,133 @@ impl<'a> PeepholeOptimizations {
///
/// For `target_expr` = `a`, `expr` = `a.b`, this function changes `expr` to `a?.b` and returns true.
fn inject_optional_chaining_if_matched(
target_expr: &Expression<'a>,
target_id_name: &str,
expr_to_inject: &mut Expression<'a>,
expr: &mut Expression<'a>,
ctx: Ctx<'a, '_>,
) -> bool {
fn inject(target_expr: &Expression<'_>, expr: &mut Expression<'_>) -> bool {
match expr {
Expression::StaticMemberExpression(e) => {
if e.object.content_eq(target_expr) {
if Self::inject_optional_chaining_if_matched_inner(
target_id_name,
expr_to_inject,
expr,
ctx,
) {
if !matches!(expr, Expression::ChainExpression(_)) {
*expr = ctx.ast.expression_chain(
expr.span(),
ctx.ast.move_expression(expr).into_chain_element().unwrap(),
);
}
true
} else {
false
}
}

/// See [`Self::inject_optional_chaining_if_matched`]
fn inject_optional_chaining_if_matched_inner(
target_id_name: &str,
expr_to_inject: &mut Expression<'a>,
expr: &mut Expression<'a>,
ctx: Ctx<'a, '_>,
) -> bool {
match expr {
Expression::StaticMemberExpression(e) => {
if e.object.is_specific_id(target_id_name) {
e.optional = true;
e.object = ctx.ast.move_expression(expr_to_inject);
return true;
}
if Self::inject_optional_chaining_if_matched_inner(
target_id_name,
expr_to_inject,
&mut e.object,
ctx,
) {
return true;
}
}
Expression::ComputedMemberExpression(e) => {
if e.object.is_specific_id(target_id_name) {
e.optional = true;
e.object = ctx.ast.move_expression(expr_to_inject);
return true;
}
if Self::inject_optional_chaining_if_matched_inner(
target_id_name,
expr_to_inject,
&mut e.object,
ctx,
) {
return true;
}
}
Expression::CallExpression(e) => {
if e.callee.is_specific_id(target_id_name) {
e.optional = true;
e.callee = ctx.ast.move_expression(expr_to_inject);
return true;
}
if Self::inject_optional_chaining_if_matched_inner(
target_id_name,
expr_to_inject,
&mut e.callee,
ctx,
) {
return true;
}
}
Expression::ChainExpression(e) => match &mut e.expression {
ChainElement::StaticMemberExpression(e) => {
if e.object.is_specific_id(target_id_name) {
e.optional = true;
e.object = ctx.ast.move_expression(expr_to_inject);
return true;
}
if inject(target_expr, &mut e.object) {
if Self::inject_optional_chaining_if_matched_inner(
target_id_name,
expr_to_inject,
&mut e.object,
ctx,
) {
return true;
}
}
Expression::ComputedMemberExpression(e) => {
if e.object.content_eq(target_expr) {
ChainElement::ComputedMemberExpression(e) => {
if e.object.is_specific_id(target_id_name) {
e.optional = true;
e.object = ctx.ast.move_expression(expr_to_inject);
return true;
}
if inject(target_expr, &mut e.object) {
if Self::inject_optional_chaining_if_matched_inner(
target_id_name,
expr_to_inject,
&mut e.object,
ctx,
) {
return true;
}
}
Expression::CallExpression(e) => {
if e.callee.content_eq(target_expr) {
ChainElement::CallExpression(e) => {
if e.callee.is_specific_id(target_id_name) {
e.optional = true;
e.callee = ctx.ast.move_expression(expr_to_inject);
return true;
}
if inject(target_expr, &mut e.callee) {
if Self::inject_optional_chaining_if_matched_inner(
target_id_name,
expr_to_inject,
&mut e.callee,
ctx,
) {
return true;
}
}
Expression::ChainExpression(e) => match &mut e.expression {
ChainElement::StaticMemberExpression(e) => {
if e.object.content_eq(target_expr) {
e.optional = true;
return true;
}
if inject(target_expr, &mut e.object) {
return true;
}
}
ChainElement::ComputedMemberExpression(e) => {
if e.object.content_eq(target_expr) {
e.optional = true;
return true;
}
if inject(target_expr, &mut e.object) {
return true;
}
}
ChainElement::CallExpression(e) => {
if e.callee.content_eq(target_expr) {
e.optional = true;
return true;
}
if inject(target_expr, &mut e.callee) {
return true;
}
}
_ => {}
},
_ => {}
}
false
}

if inject(target_expr, expr) {
if !matches!(expr, Expression::ChainExpression(_)) {
*expr = ctx.ast.expression_chain(
expr.span(),
ctx.ast.move_expression(expr).into_chain_element().unwrap(),
);
}
true
} else {
false
},
_ => {}
}
false
}

/// Merge `consequent` and `alternate` of `ConditionalExpression` inside.
Expand Down Expand Up @@ -2426,9 +2488,11 @@ mod test {
test("var a; a ? b(c) : b(e)", "var a; b(a ? c : e)");
test("a() != null ? a() : b", "a() == null ? b : a()");
test("var a; a != null ? a : b", "var a; a ?? b");
test("var a; (a = _a) != null ? a : b", "var a; (a = _a) ?? b");
test("a != null ? a : b", "a == null ? b : a"); // accessing global `a` may have a getter with side effects
test_es2019("var a; a != null ? a : b", "var a; a == null ? b : a");
test("var a; a != null ? a.b.c[d](e) : undefined", "var a; a?.b.c[d](e)");
test("var a; (a = _a) != null ? a.b.c[d](e) : undefined", "var a; (a = _a)?.b.c[d](e)");
test("a != null ? a.b.c[d](e) : undefined", "a != null && a.b.c[d](e)"); // accessing global `a` may have a getter with side effects
test(
"var a, undefined = 1; a != null ? a.b.c[d](e) : undefined",
Expand Down
4 changes: 2 additions & 2 deletions tasks/minsize/minsize.snap
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Original file line number Diff line number Diff line change
Expand Up @@ -21,7 +21,7 @@ Original | minified | minified | gzip | gzip | Fixture

3.20 MB | 1.01 MB | 1.01 MB | 324.31 kB | 331.56 kB | echarts.js

6.69 MB | 2.30 MB | 2.31 MB | 468.88 kB | 488.28 kB | antd.js
6.69 MB | 2.30 MB | 2.31 MB | 468.52 kB | 488.28 kB | antd.js

10.95 MB | 3.37 MB | 3.49 MB | 863.74 kB | 915.50 kB | typescript.js
10.95 MB | 3.36 MB | 3.49 MB | 862.11 kB | 915.50 kB | typescript.js

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