From 0e7bab887f6d56abdfb6cbb8f88a512c94387f68 Mon Sep 17 00:00:00 2001
From: Boshen <1430279+Boshen@users.noreply.github.com>
Date: Fri, 10 Jan 2025 16:22:09 +0000
Subject: [PATCH] feat(minifier): remove `if(false){}` in a single pass (#8421)

---
 .../src/ast_passes/peephole_remove_dead_code.rs     | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/crates/oxc_minifier/src/ast_passes/peephole_remove_dead_code.rs b/crates/oxc_minifier/src/ast_passes/peephole_remove_dead_code.rs
index d5ca1697dd2da..908f019afe18d 100644
--- a/crates/oxc_minifier/src/ast_passes/peephole_remove_dead_code.rs
+++ b/crates/oxc_minifier/src/ast_passes/peephole_remove_dead_code.rs
@@ -33,9 +33,7 @@ impl<'a> Traverse<'a> for PeepholeRemoveDeadCode {
             Statement::BlockStatement(s) => Self::try_optimize_block(s, ctx),
             Statement::IfStatement(s) => self.try_fold_if(s, ctx),
             Statement::ForStatement(s) => self.try_fold_for(s, ctx),
-            Statement::ExpressionStatement(s) => {
-                Self::try_fold_iife(s, ctx).or_else(|| Self::try_fold_expression_stmt(s, ctx))
-            }
+            Statement::ExpressionStatement(s) => Self::try_fold_iife(s, ctx),
             Statement::TryStatement(s) => Self::try_fold_try(s, ctx),
             Statement::LabeledStatement(s) => Self::try_fold_labeled(s, ctx),
             _ => None,
@@ -43,6 +41,13 @@ impl<'a> Traverse<'a> for PeepholeRemoveDeadCode {
             *stmt = new_stmt;
             self.changed = true;
         }
+
+        if let Statement::ExpressionStatement(s) = stmt {
+            if let Some(new_stmt) = Self::try_fold_expression_stmt(s, ctx) {
+                *stmt = new_stmt;
+                self.changed = true;
+            }
+        }
     }
 
     fn exit_statements(&mut self, stmts: &mut Vec<'a, Statement<'a>>, ctx: &mut TraverseCtx<'a>) {
@@ -746,6 +751,8 @@ mod test {
     fn test_fold_if_statement() {
         test("if (foo) {}", "foo");
         test("if (foo) {} else {}", "foo");
+        test("if (false) {}", "");
+        test("if (true) {}", "");
     }
 
     #[test]