perf(minifier): merge Normalize and RemoveSyntax pass (#8467)

crates/oxc_minifier/src/ast_passes/mod.rs

@@ -13,7 +13,6 @@ mod peephole_minimize_conditions;
 mod peephole_remove_dead_code;
 mod peephole_replace_known_methods;
 mod peephole_substitute_alternate_syntax;
-mod remove_syntax;
 mod remove_unused_code;
 mod statement_fusion;
 
@@ -27,7 +26,6 @@ pub use peephole_minimize_conditions::PeepholeMinimizeConditions;
 pub use peephole_remove_dead_code::PeepholeRemoveDeadCode;
 pub use peephole_replace_known_methods::PeepholeReplaceKnownMethods;
 pub use peephole_substitute_alternate_syntax::PeepholeSubstituteAlternateSyntax;
-pub use remove_syntax::RemoveSyntax;
 #[expect(unused)]
 pub use remove_unused_code::RemoveUnusedCode;
 pub use statement_fusion::StatementFusion;

crates/oxc_minifier/src/ast_passes/normalize.rs

@@ -1,22 +1,31 @@
+use oxc_allocator::Vec;
 use oxc_ast::ast::*;
 use oxc_ecmascript::constant_evaluation::ConstantEvaluation;
 use oxc_span::GetSpan;
 use oxc_syntax::scope::ScopeFlags;
 use oxc_traverse::{traverse_mut_with_ctx, ReusableTraverseCtx, Traverse, TraverseCtx};
 
-use crate::{ctx::Ctx, CompressorPass};
+use crate::{ctx::Ctx, CompressOptions, CompressorPass};
 
 /// Normalize AST
 ///
 /// Make subsequent AST passes easier to analyze:
 ///
+/// * remove `Statement::EmptyStatement`
+/// * remove `ParenthesizedExpression`
 /// * convert whiles to fors
 /// * convert `Infinity` to `f64::INFINITY`
 /// * convert `NaN` to `f64::NaN`
 /// * convert `var x; void x` to `void 0`
 ///
+/// Also
+///
+/// * remove `debugger` and `console.log` (optional)
+///
 /// <https://github.com/google/closure-compiler/blob/v20240609/src/com/google/javascript/jscomp/Normalize.java>
-pub struct Normalize;
+pub struct Normalize {
+    options: CompressOptions,
+}
 
 impl<'a> CompressorPass<'a> for Normalize {
     fn build(&mut self, program: &mut Program<'a>, ctx: &mut ReusableTraverseCtx<'a>) {
@@ -25,6 +34,14 @@ impl<'a> CompressorPass<'a> for Normalize {
 }
 
 impl<'a> Traverse<'a> for Normalize {
+    fn exit_statements(&mut self, stmts: &mut Vec<'a, Statement<'a>>, _ctx: &mut TraverseCtx<'a>) {
+        stmts.retain(|stmt| {
+            !(matches!(stmt, Statement::EmptyStatement(_))
+                || self.drop_debugger(stmt)
+                || self.drop_console(stmt))
+        });
+    }
+
     fn exit_statement(&mut self, stmt: &mut Statement<'a>, ctx: &mut TraverseCtx<'a>) {
         match stmt {
             Statement::WhileStatement(_) => {
@@ -36,21 +53,63 @@ impl<'a> Traverse<'a> for Normalize {
     }
 
     fn exit_expression(&mut self, expr: &mut Expression<'a>, ctx: &mut TraverseCtx<'a>) {
+        if let Expression::ParenthesizedExpression(paren_expr) = expr {
+            *expr = ctx.ast.move_expression(&mut paren_expr.expression);
+        }
         match expr {
             Expression::Identifier(_) => {
                 Self::convert_infinity_or_nan_into_number(expr, ctx);
             }
             Expression::UnaryExpression(e) if e.operator.is_void() => {
                 Self::convert_void_ident(e, ctx);
             }
+            Expression::ArrowFunctionExpression(e) => {
+                self.recover_arrow_expression_after_drop_console(e);
+            }
+            Expression::CallExpression(_) if self.options.drop_console => {
+                self.compress_console(expr, ctx);
+            }
             _ => {}
         }
     }
 }
 
 impl<'a> Normalize {
-    pub fn new() -> Self {
-        Self
+    pub fn new(options: CompressOptions) -> Self {
+        Self { options }
+    }
+
+    /// Drop `drop_debugger` statement.
+    ///
+    /// Enabled by `compress.drop_debugger`
+    fn drop_debugger(&mut self, stmt: &Statement<'a>) -> bool {
+        matches!(stmt, Statement::DebuggerStatement(_)) && self.options.drop_debugger
+    }
+
+    fn compress_console(&mut self, expr: &mut Expression<'a>, ctx: &mut TraverseCtx<'a>) {
+        debug_assert!(self.options.drop_console);
+        if Self::is_console(expr) {
+            *expr = ctx.ast.void_0(expr.span());
+        }
+    }
+
+    fn drop_console(&mut self, stmt: &Statement<'a>) -> bool {
+        self.options.drop_console
+            && matches!(stmt, Statement::ExpressionStatement(expr) if Self::is_console(&expr.expression))
+    }
+
+    fn recover_arrow_expression_after_drop_console(&self, expr: &mut ArrowFunctionExpression<'a>) {
+        if self.options.drop_console && expr.expression && expr.body.is_empty() {
+            expr.expression = false;
+        }
+    }
+
+    fn is_console(expr: &Expression<'_>) -> bool {
+        let Expression::CallExpression(call_expr) = &expr else { return false };
+        let Some(member_expr) = call_expr.callee.as_member_expression() else { return false };
+        let obj = member_expr.object();
+        let Some(ident) = obj.get_identifier_reference() else { return false };
+        ident.name == "console"
     }
 
     fn convert_while_to_for(stmt: &mut Statement<'a>, ctx: &mut TraverseCtx<'a>) {
@@ -112,11 +171,16 @@ impl<'a> Normalize {
 mod test {
     use oxc_allocator::Allocator;
 
-    use crate::tester;
+    use crate::{tester, CompressOptions};
 
     fn test(source_text: &str, expected: &str) {
         let allocator = Allocator::default();
-        let mut pass = super::Normalize::new();
+        let options = CompressOptions {
+            drop_debugger: true,
+            drop_console: true,
+            ..CompressOptions::default()
+        };
+        let mut pass = super::Normalize::new(options);
         tester::test(&allocator, source_text, expected, &mut pass);
     }
 
@@ -131,4 +195,21 @@ mod test {
         test("var x; void x", "var x; void 0");
         test("void x", "void x"); // reference error
     }
+
+    #[test]
+    fn parens() {
+        test("(((x)))", "x");
+        test("(((a + b))) * c", "(a + b) * c");
+    }
+
+    #[test]
+    fn drop_console() {
+        test("console.log()", "void 0;\n");
+        test("() => console.log()", "() => void 0");
+    }
+
+    #[test]
+    fn drop_debugger() {
+        test("debugger", "");
+    }
 }

crates/oxc_minifier/src/compressor.rs

@@ -4,7 +4,7 @@ use oxc_semantic::{ScopeTree, SemanticBuilder, SymbolTable};
 use oxc_traverse::ReusableTraverseCtx;
 
 use crate::{
-    ast_passes::{DeadCodeElimination, Normalize, PeepholeOptimizations, RemoveSyntax},
+    ast_passes::{DeadCodeElimination, Normalize, PeepholeOptimizations},
     CompressOptions, CompressorPass,
 };
 
@@ -31,9 +31,8 @@ impl<'a> Compressor<'a> {
         program: &mut Program<'a>,
     ) {
         let mut ctx = ReusableTraverseCtx::new(scopes, symbols, self.allocator);
-        RemoveSyntax::new(self.options).build(program, &mut ctx);
         // RemoveUnusedCode::new(self.options).build(program, &mut ctx);
-        Normalize::new().build(program, &mut ctx);
+        Normalize::new(self.options).build(program, &mut ctx);
         PeepholeOptimizations::new(self.options.target, true, self.options)
             .run_in_loop(program, &mut ctx);
         PeepholeOptimizations::new(self.options.target, false, self.options)
@@ -53,7 +52,7 @@ impl<'a> Compressor<'a> {
         program: &mut Program<'a>,
     ) {
         let mut ctx = ReusableTraverseCtx::new(scopes, symbols, self.allocator);
-        RemoveSyntax::new(self.options).build(program, &mut ctx);
+        Normalize::new(self.options).build(program, &mut ctx);
         DeadCodeElimination::new().build(program, &mut ctx);
     }
 }

crates/oxc_minifier/src/tester.rs

@@ -6,7 +6,7 @@ use oxc_span::SourceType;
 use oxc_traverse::ReusableTraverseCtx;
 
 use crate::{
-    ast_passes::{CompressorPass, Normalize, RemoveSyntax},
+    ast_passes::{CompressorPass, Normalize},
     CompressOptions,
 };
 
@@ -44,8 +44,7 @@ fn run<'a, P: CompressorPass<'a>>(
         let (symbols, scopes) =
             SemanticBuilder::new().build(&program).semantic.into_symbol_table_and_scope_tree();
         let mut ctx = ReusableTraverseCtx::new(scopes, symbols, allocator);
-        RemoveSyntax::new(CompressOptions::all_false()).build(&mut program, &mut ctx);
-        Normalize::new().build(&mut program, &mut ctx);
+        Normalize::new(CompressOptions::all_false()).build(&mut program, &mut ctx);
         pass.build(&mut program, &mut ctx);
     }