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feat(minifier): minimize a + 'b' + 'c' -> a + 'bc' (#8137)
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@Boshen
Boshen committed Dec 27, 2024
1 parent 213364a commit 2b2a373
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68 changes: 66 additions & 2 deletions crates/oxc_minifier/src/ast_passes/peephole_fold_constants.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -241,14 +241,14 @@ impl<'a, 'b> PeepholeFoldConstants {
BinaryOperator::ShiftLeft
| BinaryOperator::ShiftRight
| BinaryOperator::ShiftRightZeroFill
| BinaryOperator::Addition
| BinaryOperator::Subtraction
| BinaryOperator::Division
| BinaryOperator::Remainder
| BinaryOperator::Multiplication
| BinaryOperator::Exponential => {
ctx.eval_binary_expression(e).map(|v| ctx.value_to_expr(e.span, v))
}
BinaryOperator::Addition => Self::try_fold_add(e, ctx),
BinaryOperator::BitwiseAnd | BinaryOperator::BitwiseOR | BinaryOperator::BitwiseXOR => {
if let Some(v) = ctx.eval_binary_expression(e) {
return Some(ctx.value_to_expr(e.span, v));
Expand All @@ -260,6 +260,27 @@ impl<'a, 'b> PeepholeFoldConstants {
}
}

// Simplified version of `tryFoldAdd` from closure compiler.
fn try_fold_add(e: &mut BinaryExpression<'a>, ctx: Ctx<'a, 'b>) -> Option<Expression<'a>> {
if let Some(v) = ctx.eval_binary_expression(e) {
return Some(ctx.value_to_expr(e.span, v));
}
debug_assert_eq!(e.operator, BinaryOperator::Addition);
// a + 'b' + 'c' -> a + 'bc'
if let Expression::BinaryExpression(left_binary_expr) = &mut e.left {
if let Expression::StringLiteral(left_str) = &left_binary_expr.right {
if let Expression::StringLiteral(right_str) = &e.right {
let span = Span::new(left_str.span.start, right_str.span.end);
let value = left_str.value.to_string() + right_str.value.as_str();
let right = ctx.ast.expression_string_literal(span, value, None);
let left = ctx.ast.move_expression(&mut left_binary_expr.left);
return Some(ctx.ast.expression_binary(e.span, left, e.operator, right));
}
}
}
None
}

fn try_fold_left_child_op(
e: &mut BinaryExpression<'a>,
ctx: Ctx<'a, '_>,
Expand Down Expand Up @@ -1318,7 +1339,7 @@ mod test {
}

#[test]
fn test_fold_bit_shift() {
fn test_fold_bit_shifts() {
test("x = 1 << 0", "x=1");
test("x = -1 << 0", "x=-1");
test("x = 1 << 1", "x=2");
Expand Down Expand Up @@ -1366,6 +1387,49 @@ mod test {
test("8589934593 >>> 0", "1");
}

#[test]
fn test_string_add() {
test("x = 'a' + 'bc'", "x = 'abc'");
test("x = 'a' + 5", "x = 'a5'");
test("x = 5 + 'a'", "x = '5a'");
// test("x = 'a' + 5n", "x = 'a5n'");
// test("x = 5n + 'a'", "x = '5na'");
test("x = 'a' + ''", "x = 'a'");
test("x = 'a' + foo()", "x = 'a'+foo()");
test("x = foo() + 'a' + 'b'", "x = foo()+'ab'");
test("x = (foo() + 'a') + 'b'", "x = foo()+'ab'"); // believe it!
test("x = foo() + 'a' + 'b' + 'cd' + bar()", "x = foo()+'abcd'+bar()");
test("x = foo() + 2 + 'b'", "x = foo()+2+\"b\""); // don't fold!

// test("x = foo() + 'a' + 2", "x = foo()+\"a2\"");
test("x = '' + null", "x = 'null'");
test("x = true + '' + false", "x = 'truefalse'");
// test("x = '' + []", "x = ''");
// test("x = foo() + 'a' + 1 + 1", "x = foo() + 'a11'");
test("x = 1 + 1 + 'a'", "x = '2a'");
test("x = 1 + 1 + 'a'", "x = '2a'");
test("x = 'a' + (1 + 1)", "x = 'a2'");
// test("x = '_' + p1 + '_' + ('' + p2)", "x = '_' + p1 + '_' + p2");
// test("x = 'a' + ('_' + 1 + 1)", "x = 'a_11'");
// test("x = 'a' + ('_' + 1) + 1", "x = 'a_11'");
// test("x = 1 + (p1 + '_') + ('' + p2)", "x = 1 + (p1 + '_') + p2");
// test("x = 1 + p1 + '_' + ('' + p2)", "x = 1 + p1 + '_' + p2");
// test("x = 1 + 'a' + p1", "x = '1a' + p1");
// test("x = (p1 + (p2 + 'a')) + 'b'", "x = (p1 + (p2 + 'ab'))");
// test("'a' + ('b' + p1) + 1", "'ab' + p1 + 1");
// test("x = 'a' + ('b' + p1 + 'c')", "x = 'ab' + (p1 + 'c')");
test_same("x = 'a' + (4 + p1 + 'a')");
test_same("x = p1 / 3 + 4");
test_same("foo() + 3 + 'a' + foo()");
test_same("x = 'a' + ('b' + p1 + p2)");
test_same("x = 1 + ('a' + p1)");
test_same("x = p1 + '' + p2");
test_same("x = 'a' + (1 + p1)");
test_same("x = (p2 + 'a') + (1 + p1)");
test_same("x = (p2 + 'a') + (1 + p1 + p2)");
test_same("x = (p2 + 'a') + (1 + (p1 + p2))");
}

#[test]
fn test_fold_arithmetic() {
test("x = 10 + 20", "x = 30");
Expand Down
10 changes: 5 additions & 5 deletions tasks/minsize/minsize.snap
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Original file line number Diff line number Diff line change
@@ -1,13 +1,13 @@
| Oxc | ESBuild | Oxc | ESBuild |
Original | minified | minified | gzip | gzip | Fixture
-------------------------------------------------------------------------------------
72.14 kB | 23.74 kB | 23.70 kB | 8.62 kB | 8.54 kB | react.development.js
72.14 kB | 23.74 kB | 23.70 kB | 8.61 kB | 8.54 kB | react.development.js

173.90 kB | 60.22 kB | 59.82 kB | 19.49 kB | 19.33 kB | moment.js

287.63 kB | 90.76 kB | 90.07 kB | 32.22 kB | 31.95 kB | jquery.js
287.63 kB | 90.74 kB | 90.07 kB | 32.21 kB | 31.95 kB | jquery.js

342.15 kB | 119.00 kB | 118.14 kB | 44.66 kB | 44.37 kB | vue.js
342.15 kB | 118.77 kB | 118.14 kB | 44.54 kB | 44.37 kB | vue.js

544.10 kB | 72.53 kB | 72.48 kB | 26.23 kB | 26.20 kB | lodash.js

Expand All @@ -17,11 +17,11 @@ Original | minified | minified | gzip | gzip | Fixture

1.25 MB | 657.23 kB | 646.76 kB | 164.23 kB | 163.73 kB | three.js

2.14 MB | 735.70 kB | 724.14 kB | 181.11 kB | 181.07 kB | victory.js
2.14 MB | 735.67 kB | 724.14 kB | 181.09 kB | 181.07 kB | victory.js

3.20 MB | 1.01 MB | 1.01 MB | 332.35 kB | 331.56 kB | echarts.js

6.69 MB | 2.38 MB | 2.31 MB | 495.34 kB | 488.28 kB | antd.js
6.69 MB | 2.38 MB | 2.31 MB | 495.33 kB | 488.28 kB | antd.js

10.95 MB | 3.51 MB | 3.49 MB | 910.94 kB | 915.50 kB | typescript.js

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