perf(minifier): only run optimizations on local changes (#8644)

Previously all code are ran in a fixed point loop when ast changes.

This PR changes running code when a function changes its enclosing ast only.

Author: Boshen

Cargo.lock

@@ -33,6 +33,7 @@ oxc_syntax = { workspace = true }
 oxc_traverse = { workspace = true }
 
 cow-utils = { workspace = true }
+rustc-hash = { workspace = true }
 
 [dev-dependencies]
 oxc_parser = { workspace = true }

crates/oxc_minifier/Cargo.toml

@@ -93,7 +93,7 @@ impl<'a> PeepholeOptimizations {
         }
 
         *stmts = new_stmts;
-        self.changed = true;
+        self.mark_current_function_as_changed();
     }
 }
 
@@ -133,7 +133,7 @@ impl<'a> PeepholeOptimizations {
             }
         }
 
-        if self.changed {
+        if self.is_current_function_changed() {
             stmts.retain(|stmt| !matches!(stmt, Statement::EmptyStatement(_)));
         }
     }
@@ -147,7 +147,7 @@ impl<'a> PeepholeOptimizations {
         if let Statement::ExpressionStatement(expr_stmt) = ctx.ast.move_statement(&mut stmts[i]) {
             if let Statement::ForStatement(for_stmt) = &mut stmts[i + 1] {
                 for_stmt.init = Some(ForStatementInit::from(expr_stmt.unbox().expression));
-                self.changed = true;
+                self.mark_current_function_as_changed();
             };
         }
     }
@@ -163,11 +163,11 @@ impl<'a> PeepholeOptimizations {
                 match for_stmt.init.as_mut() {
                     Some(ForStatementInit::VariableDeclaration(for_var)) => {
                         for_var.declarations.splice(0..0, var.unbox().declarations);
-                        self.changed = true;
+                        self.mark_current_function_as_changed();
                     }
                     None => {
                         for_stmt.init = Some(ForStatementInit::VariableDeclaration(var));
-                        self.changed = true;
+                        self.mark_current_function_as_changed();
                     }
                     _ => {
                         unreachable!()
@@ -209,7 +209,7 @@ impl<'a> PeepholeOptimizations {
                                 _ => unreachable!(),
                             };
                             *left = ForStatementLeft::VariableDeclaration(var);
-                            self.changed = true;
+                            self.mark_current_function_as_changed();
                         }
                     }
                 }

crates/oxc_minifier/src/peephole/collapse_variable_declarations.rs

@@ -35,7 +35,7 @@ impl<'a> PeepholeOptimizations {
             *expr = MemberExpression::StaticMemberExpression(
                 ctx.ast.alloc_static_member_expression(e.span, object, property, e.optional),
             );
-            self.changed = true;
+            self.mark_current_function_as_changed();
             return;
         }
         let v = s.value.as_str();

crates/oxc_minifier/src/peephole/convert_to_dotted_properties.rs

@@ -36,7 +36,7 @@ impl<'a, 'b> PeepholeOptimizations {
             _ => None,
         } {
             *expr = folded_expr;
-            self.changed = true;
+            self.mark_current_function_as_changed();
         };
     }
 
@@ -706,7 +706,7 @@ impl<'a, 'b> PeepholeOptimizations {
             true
         });
         if e.properties.len() != len {
-            self.changed = true;
+            self.mark_current_function_as_changed();
         }
         None
     }

crates/oxc_minifier/src/peephole/fold_constants.rs

@@ -21,16 +21,20 @@ impl<'a> PeepholeOptimizations {
         stmts: &mut oxc_allocator::Vec<'a, Statement<'a>>,
         ctx: &mut TraverseCtx<'a>,
     ) {
-        self.try_replace_if(stmts, ctx);
-        let changed = self.changed;
-        while self.changed {
-            self.changed = false;
-            self.try_replace_if(stmts, ctx);
+        let mut changed = false;
+        let mut changed2 = false;
+        Self::try_replace_if(stmts, &mut changed2, ctx);
+        while changed2 {
+            changed2 = false;
+            Self::try_replace_if(stmts, &mut changed2, ctx);
             if stmts.iter().any(|stmt| matches!(stmt, Statement::EmptyStatement(_))) {
                 stmts.retain(|stmt| !matches!(stmt, Statement::EmptyStatement(_)));
             }
+            changed = changed2;
+        }
+        if changed {
+            self.mark_current_function_as_changed();
         }
-        self.changed = self.changed || changed;
     }
 
     pub fn minimize_conditions_exit_statement(
@@ -64,7 +68,7 @@ impl<'a> PeepholeOptimizations {
             _ => None,
         } {
             *stmt = folded_stmt;
-            self.changed = true;
+            self.mark_current_function_as_changed();
         };
     }
 
@@ -87,7 +91,7 @@ impl<'a> PeepholeOptimizations {
                 }
             }
             if changed {
-                self.changed = true;
+                self.mark_current_function_as_changed();
             } else {
                 break;
             }
@@ -99,7 +103,7 @@ impl<'a> PeepholeOptimizations {
             _ => None,
         } {
             *expr = folded_expr;
-            self.changed = true;
+            self.mark_current_function_as_changed();
         };
     }
 
@@ -236,7 +240,11 @@ impl<'a> PeepholeOptimizations {
         None
     }
 
-    fn try_replace_if(&mut self, stmts: &mut Vec<'a, Statement<'a>>, ctx: &mut TraverseCtx<'a>) {
+    fn try_replace_if(
+        stmts: &mut Vec<'a, Statement<'a>>,
+        changed: &mut bool,
+        ctx: &mut TraverseCtx<'a>,
+    ) {
         for i in 0..stmts.len() {
             let Statement::IfStatement(if_stmt) = &stmts[i] else {
                 continue;
@@ -268,15 +276,15 @@ impl<'a> PeepholeOptimizations {
                     alternate,
                 );
                 stmts[i] = ctx.ast.statement_return(if_stmt.span, Some(argument));
-                self.changed = true;
+                *changed = true;
                 break;
             } else if else_branch.is_some() && Self::statement_must_exit_parent(then_branch) {
                 let Statement::IfStatement(if_stmt) = &mut stmts[i] else {
                     unreachable!();
                 };
                 let else_branch = if_stmt.alternate.take().unwrap();
                 stmts.insert(i + 1, else_branch);
-                self.changed = true;
+                *changed = true;
             }
         }
     }

crates/oxc_minifier/src/peephole/minimize_conditions.rs

@@ -22,7 +22,7 @@ impl<'a> PeepholeOptimizations {
         if let Some(last) = stmts.last() {
             if matches!(last, Statement::ReturnStatement(ret) if ret.argument.is_none()) {
                 stmts.pop();
-                self.changed = true;
+                self.mark_current_function_as_changed();
             }
         }
     }