From cd274eeb02f8ae0edf45f31db227f72deb488f39 Mon Sep 17 00:00:00 2001
From: Cameron <cameron.clark@hey.com>
Date: Thu, 2 Jan 2025 10:32:20 +0000
Subject: [PATCH] feat(minifier): minimize logical exprs (#8209)

---
 .../peephole_minimize_conditions.rs           | 61 +++++++++++++++++--
 tasks/minsize/minsize.snap                    | 10 +--
 2 files changed, 62 insertions(+), 9 deletions(-)

diff --git a/crates/oxc_minifier/src/ast_passes/peephole_minimize_conditions.rs b/crates/oxc_minifier/src/ast_passes/peephole_minimize_conditions.rs
index 1bcff47b4402e..981cbbad9b40f 100644
--- a/crates/oxc_minifier/src/ast_passes/peephole_minimize_conditions.rs
+++ b/crates/oxc_minifier/src/ast_passes/peephole_minimize_conditions.rs
@@ -57,6 +57,9 @@ impl<'a> Traverse<'a> for PeepholeMinimizeConditions {
     fn exit_expression(&mut self, expr: &mut Expression<'a>, ctx: &mut TraverseCtx<'a>) {
         if let Some(folded_expr) = match expr {
             Expression::UnaryExpression(e) => Self::try_minimize_not(e, ctx),
+            Expression::LogicalExpression(logical_expr) => {
+                Self::try_minimize_logical(logical_expr, ctx)
+            }
             Expression::ConditionalExpression(conditional_expr) => {
                 Self::try_minimize_conditional(conditional_expr, ctx)
             }
@@ -257,6 +260,51 @@ impl<'a> PeepholeMinimizeConditions {
         }
     }
 
+    fn try_minimize_logical(
+        expr: &mut LogicalExpression<'a>,
+        ctx: &mut TraverseCtx<'a>,
+    ) -> Option<Expression<'a>> {
+        // `a && true` -> `a`
+        // `a && false` -> `false`
+        if expr.operator == LogicalOperator::And {
+            if let (
+                Expression::Identifier(test_ident),
+                Expression::BooleanLiteral(consequent_lit),
+            ) = (&expr.left, &expr.right)
+            {
+                if consequent_lit.value {
+                    return Some(ctx.ast.move_expression(&mut expr.left));
+                }
+                if ctx.scopes().find_binding(ctx.current_scope_id(), &test_ident.name).is_some() {
+                    return Some(ctx.ast.expression_boolean_literal(expr.span, false));
+                }
+                return None;
+            }
+        }
+
+        // `a || true` -> `true`
+        // `a || false` -> `a`
+        if expr.operator == LogicalOperator::Or {
+            if let (
+                Expression::Identifier(test_ident),
+                Expression::BooleanLiteral(consequent_lit),
+            ) = (&expr.left, &expr.right)
+            {
+                if consequent_lit.value {
+                    if ctx.scopes().find_binding(ctx.current_scope_id(), &test_ident.name).is_some()
+                    {
+                        return Some(ctx.ast.expression_boolean_literal(expr.span, true));
+                    }
+                } else {
+                    return Some(ctx.ast.move_expression(&mut expr.left));
+                }
+                return None;
+            }
+        }
+
+        None
+    }
+
     fn try_minimize_conditional(
         expr: &mut ConditionalExpression<'a>,
         ctx: &mut TraverseCtx<'a>,
@@ -669,10 +717,15 @@ mod test {
         fold("(x ? false : true) && y()", "!x && y()");
         fold("(x ? true : y) && y()", "(x || y) && y()");
         fold("(x ? y : false) && y()", "(x && y) && y()");
-        // fold("(x && true) && y()", "x && y()");
-        // fold("(x && false) && y()", "0&&y()");
-        // fold("(x || true) && y()", "1&&y()");
-        // fold("(x || false) && y()", "x&&y()");
+        fold("var x; (x && true) && y()", "var x; x && y()");
+        fold("var x; (x && false) && y()", "var x; false && y()");
+        fold("(x && true) && y()", "x && y()");
+        fold("(x && false) && y()", "x && false && y()");
+        fold("var x; (x || true) && y()", "var x; true && y()");
+        fold("var x; (x || false) && y()", "var x; x && y()");
+
+        fold_same("(x || true) && y()");
+        fold("(x || false) && y()", "x && y()");
     }
 
     #[test]
diff --git a/tasks/minsize/minsize.snap b/tasks/minsize/minsize.snap
index 6d06107f38210..48400ccd99454 100644
--- a/tasks/minsize/minsize.snap
+++ b/tasks/minsize/minsize.snap
@@ -15,13 +15,13 @@ Original   | minified   | minified   | gzip       | gzip       | Fixture
 
 1.01 MB    | 460.75 kB  | 458.89 kB  | 126.88 kB  | 126.71 kB  | bundle.min.js
 
-1.25 MB    | 653.17 kB  | 646.76 kB  | 163.58 kB  | 163.73 kB  | three.js  
+1.25 MB    | 653.17 kB  | 646.76 kB  | 163.57 kB  | 163.73 kB  | three.js  
 
-2.14 MB    | 726.71 kB  | 724.14 kB  | 180.25 kB  | 181.07 kB  | victory.js
+2.14 MB    | 726.70 kB  | 724.14 kB  | 180.25 kB  | 181.07 kB  | victory.js
 
-3.20 MB    | 1.01 MB    | 1.01 MB    | 332.14 kB  | 331.56 kB  | echarts.js
+3.20 MB    | 1.01 MB    | 1.01 MB    | 332.13 kB  | 331.56 kB  | echarts.js
 
-6.69 MB    | 2.32 MB    | 2.31 MB    | 493.00 kB  | 488.28 kB  | antd.js   
+6.69 MB    | 2.32 MB    | 2.31 MB    | 492.99 kB  | 488.28 kB  | antd.js   
 
-10.95 MB   | 3.51 MB    | 3.49 MB    | 910.09 kB  | 915.50 kB  | typescript.js
+10.95 MB   | 3.51 MB    | 3.49 MB    | 910.06 kB  | 915.50 kB  | typescript.js