feat(minifier): support if with side effects in dead code elimination

crates/oxc_minifier/src/peephole/remove_dead_code.rs

@@ -177,13 +177,14 @@ impl<'a, 'b> PeepholeOptimizations {
             _ => {}
         }
 
-        if let Some(boolean) = if_stmt.test.get_side_free_boolean_value(&ctx) {
+        if let Some(boolean) = if_stmt.test.evaluate_value_to_boolean(&ctx) {
+            let test_has_side_effects = if_stmt.test.may_have_side_effects(&ctx);
             // Use "1" and "0" instead of "true" and "false" to be shorter.
-            // And also prevent swapping consequent and alternate when `!0` is encourtnered.
-            if let Expression::BooleanLiteral(b) = &if_stmt.test {
+            // And also prevent swapping consequent and alternate when `!0` is encountered.
+            if !test_has_side_effects {
                 if_stmt.test = ctx.ast.expression_numeric_literal(
-                    b.span,
-                    if b.value { 1.0 } else { 0.0 },
+                    if_stmt.test.span(),
+                    if boolean { 1.0 } else { 0.0 },
                     None,
                     NumberBase::Decimal,
                 );
@@ -196,14 +197,31 @@ impl<'a, 'b> PeepholeOptimizations {
             } else {
                 keep_var.visit_statement(&if_stmt.consequent);
             };
-            if let Some(var_stmt) = keep_var.get_variable_declaration_statement() {
+            let var_stmt = keep_var.get_variable_declaration_statement();
+            let has_var_stmt = var_stmt.is_some();
+            if let Some(var_stmt) = var_stmt {
                 if boolean {
                     if_stmt.alternate = Some(var_stmt);
                 } else {
                     if_stmt.consequent = var_stmt;
                 }
                 return None;
             }
+            if test_has_side_effects {
+                if !has_var_stmt {
+                    if boolean {
+                        if_stmt.alternate = None;
+                    } else {
+                        if_stmt.consequent = ctx.ast.statement_empty(if_stmt.consequent.span());
+                    }
+                }
+                return Some(ctx.ast.statement_if(
+                    if_stmt.span,
+                    ctx.ast.move_expression(&mut if_stmt.test),
+                    ctx.ast.move_statement(&mut if_stmt.consequent),
+                    if_stmt.alternate.as_mut().map(|alternate| ctx.ast.move_statement(alternate)),
+                ));
+            }
             return Some(if boolean {
                 ctx.ast.move_statement(&mut if_stmt.consequent)
             } else {

crates/oxc_minifier/tests/peephole/dead_code_elimination.rs

@@ -68,9 +68,11 @@ fn dce_if_statement() {
 
     test("if (!false && xxx) { foo }", "if (xxx) foo");
     test("if (!true && yyy) { foo } else { bar }", "bar");
+    test("if (xxx && false) { foo } else { bar }", "if (xxx && false); else bar");
 
     test("if (true || xxx) { foo }", "foo");
     test("if (false || xxx) { foo }", "if (xxx) foo");
+    test("if (xxx || true) { foo } else { bar }", "if (xxx || true) foo");
 
     test("if ('production' == 'production') { foo } else { bar }", "foo");
     test("if ('development' == 'production') { foo } else { bar }", "bar");

crates/oxc_minifier/tests/peephole/mod.rs

@@ -57,7 +57,7 @@ fn integration() {
          }
          console.log(c, d);
         ",
-        "if (console.log('effect'), !1) for (var c = 1, c; unknownGlobal; unknownGlobal) var d;
+        "if (console.log('effect'), !1) var c, c, d;
         console.log(c, d);
         ",
     );