Prevent allocation of field names (#2901)

boa_engine/src/bytecompiler/mod.rs

@@ -14,6 +14,7 @@ mod utils;
 use crate::{
     builtins::function::ThisMode,
     environments::{BindingLocator, CompileTimeEnvironment},
+    js_string,
     vm::{BindingOpcode, CodeBlock, Opcode},
     Context, JsBigInt, JsString, JsValue,
 };
@@ -241,7 +242,7 @@ pub struct ByteCompiler<'ctx, 'host> {
     pub(crate) literals: Vec<JsValue>,
 
     /// Property field names.
-    pub(crate) names: Vec<Identifier>,
+    pub(crate) names: Vec<JsString>,
 
     /// Private names.
     pub(crate) private_names: Vec<PrivateName>,
@@ -363,8 +364,9 @@ impl<'ctx, 'host> ByteCompiler<'ctx, 'host> {
             return *index;
         }
 
+        let string = self.interner().resolve_expect(name.sym()).utf16();
         let index = self.names.len() as u32;
-        self.names.push(name);
+        self.names.push(js_string!(string));
         self.names_map.insert(name, index);
         index
     }

boa_engine/src/vm/code_block.rs

@@ -18,10 +18,7 @@ use crate::{
     vm::CallFrame,
     Context, JsError, JsResult, JsString, JsValue,
 };
-use boa_ast::{
+use boa_ast::function::{FormalParameterList, PrivateName};
-    expression::Identifier,
-    function::{FormalParameterList, PrivateName},
-};
 use boa_gc::{Finalize, Gc, GcRefCell, Trace};
 use boa_interner::Sym;
 use boa_profiler::Profiler;
@@ -89,8 +86,7 @@ pub struct CodeBlock {
     pub(crate) literals: Box<[JsValue]>,
 
     /// Property field names.
-    #[unsafe_ignore_trace]
+    pub(crate) names: Box<[JsString]>,
-    pub(crate) names: Box<[Identifier]>,
 
     /// Private names.
     #[unsafe_ignore_trace]
@@ -365,7 +361,7 @@ impl CodeBlock {
                 *pc += size_of::<u32>();
                 format!(
                     "{operand:04}: '{}'",
-                    interner.resolve_expect(self.names[operand as usize].sym()),
+                    self.names[operand as usize].to_std_string_escaped(),
                 )
             }
             Opcode::SetPrivateField

boa_engine/src/vm/flowgraph/mod.rs

@@ -444,7 +444,7 @@ impl CodeBlock {
                     pc += size_of::<u32>();
                     let label = format!(
                         "{opcode_str} '{}'",
-                        interner.resolve_expect(self.names[operand as usize].sym()),
+                        self.names[operand as usize].to_std_string_escaped(),
                     );
                     graph.add_node(previous_pc, NodeShape::None, label.into(), Color::None);
                     graph.add_edge(previous_pc, pc, None, Color::None, EdgeStyle::Line);

boa_engine/src/vm/opcode/define/class/getter.rs

@@ -22,10 +22,8 @@ impl Operation for DefineClassStaticGetterByName {
         let function = context.vm.pop();
         let class = context.vm.pop();
         let class = class.as_object().expect("class must be object");
-        let key = context
+        let key = context.vm.frame().code_block.names[index as usize]
-            .interner()
+            .clone()
-            .resolve_expect(context.vm.frame().code_block.names[index as usize].sym())
-            .into_common::<JsString>(false)
             .into();
         {
             let function_object = function
@@ -74,10 +72,8 @@ impl Operation for DefineClassGetterByName {
         let function = context.vm.pop();
         let class_proto = context.vm.pop();
         let class_proto = class_proto.as_object().expect("class must be object");
-        let key = context
+        let key = context.vm.frame().code_block.names[index as usize]
-            .interner()
+            .clone()
-            .resolve_expect(context.vm.frame().code_block.names[index as usize].sym())
-            .into_common::<JsString>(false)
             .into();
         {
             let function_object = function

boa_engine/src/vm/opcode/define/class/method.rs

@@ -3,7 +3,7 @@ use crate::{
     object::CONSTRUCTOR,
     property::PropertyDescriptor,
     vm::{opcode::Operation, CompletionType},
-    Context, JsResult, JsString,
+    Context, JsResult,
 };
 
 /// `DefineClassStaticMethodByName` implements the Opcode Operation for `Opcode::DefineClassStaticMethodByName`
@@ -22,10 +22,8 @@ impl Operation for DefineClassStaticMethodByName {
         let function = context.vm.pop();
         let class = context.vm.pop();
         let class = class.as_object().expect("class must be object");
-        let key = context
+        let key = context.vm.frame().code_block.names[index as usize]
-            .interner()
+            .clone()
-            .resolve_expect(context.vm.frame().code_block.names[index as usize].sym())
-            .into_common::<JsString>(false)
             .into();
         {
             let function_object = function
@@ -70,10 +68,8 @@ impl Operation for DefineClassMethodByName {
         let function = context.vm.pop();
         let class_proto = context.vm.pop();
         let class_proto = class_proto.as_object().expect("class must be object");
-        let key = context
+        let key = context.vm.frame().code_block.names[index as usize]
-            .interner()
+            .clone()
-            .resolve_expect(context.vm.frame().code_block.names[index as usize].sym())
-            .into_common::<JsString>(false)
             .into();
         {
             let function_object = function

boa_engine/src/vm/opcode/define/class/setter.rs

@@ -22,10 +22,8 @@ impl Operation for DefineClassStaticSetterByName {
         let function = context.vm.pop();
         let class = context.vm.pop();
         let class = class.as_object().expect("class must be object");
-        let key = context
+        let key = context.vm.frame().code_block.names[index as usize]
-            .interner()
+            .clone()
-            .resolve_expect(context.vm.frame().code_block.names[index as usize].sym())
-            .into_common::<JsString>(false)
             .into();
         {
             let function_object = function
@@ -75,10 +73,8 @@ impl Operation for DefineClassSetterByName {
         let function = context.vm.pop();
         let class_proto = context.vm.pop();
         let class_proto = class_proto.as_object().expect("class must be object");
-        let key = context
+        let key = context.vm.frame().code_block.names[index as usize]
-            .interner()
+            .clone()
-            .resolve_expect(context.vm.frame().code_block.names[index as usize].sym())
-            .into_common::<JsString>(false)
             .into();
         {
             let function_object = function

boa_engine/src/vm/opcode/define/own_property.rs

@@ -1,7 +1,7 @@
 use crate::{
     property::PropertyDescriptor,
     vm::{opcode::Operation, CompletionType},
-    Context, JsNativeError, JsResult, JsString,
+    Context, JsNativeError, JsResult,
 };
 
 /// `DefineOwnPropertyByName` implements the Opcode Operation for `Opcode::DefineOwnPropertyByName`
@@ -24,11 +24,7 @@ impl Operation for DefineOwnPropertyByName {
         } else {
             object.to_object(context)?
         };
-        let name = context.vm.frame().code_block.names[index as usize];
+        let name = context.vm.frame().code_block.names[index as usize].clone();
-        let name = context
-            .interner()
-            .resolve_expect(name.sym())
-            .into_common::<JsString>(false);
         object.__define_own_property__(
             &name.into(),
             PropertyDescriptor::builder()

boa_engine/src/vm/opcode/delete/mod.rs

@@ -1,7 +1,7 @@
 use crate::{
     error::JsNativeError,
     vm::{opcode::Operation, CompletionType},
-    Context, JsResult, JsString,
+    Context, JsResult,
 };
 
 /// `DeletePropertyByName` implements the Opcode Operation for `Opcode::DeletePropertyByName`
@@ -17,14 +17,11 @@ impl Operation for DeletePropertyByName {
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let index = context.vm.read::<u32>();
-        let key = context.vm.frame().code_block.names[index as usize];
-        let key = context
-            .interner()
-            .resolve_expect(key.sym())
-            .into_common::<JsString>(false)
-            .into();
         let value = context.vm.pop();
         let object = value.to_object(context)?;
+        let key = context.vm.frame().code_block.names[index as usize]
+            .clone()
+            .into();
         let result = object.__delete__(&key, context)?;
         if !result && context.vm.frame().code_block.strict {
             return Err(JsNativeError::typ()

boa_engine/src/vm/opcode/get/property.rs

@@ -1,5 +1,4 @@
 use crate::{
-    js_string,
     property::PropertyKey,
     vm::{opcode::Operation, CompletionType},
     Context, JsResult, JsValue,
@@ -26,8 +25,9 @@ impl Operation for GetPropertyByName {
             value.to_object(context)?
         };
 
-        let name = context.vm.frame().code_block.names[index as usize];
+        let key = context.vm.frame().code_block.names[index as usize]
-        let key: PropertyKey = context.interner().resolve_expect(name.sym()).utf16().into();
+            .clone()
+            .into();
         let result = object.__get__(&key, value, context)?;
 
         context.vm.push(result);
@@ -93,8 +93,7 @@ impl Operation for GetMethod {
 
     fn execute(context: &mut Context<'_>) -> JsResult<CompletionType> {
         let index = context.vm.read::<u32>();
-        let name = context.vm.frame().code_block.names[index as usize];
+        let key = context.vm.frame().code_block.names[index as usize].clone();
-        let key = js_string!(context.interner().resolve_expect(name.sym()).utf16());
         let value = context.vm.pop();
 
         let method = value.get_method(key, context)?;

boa_engine/src/vm/opcode/set/property.rs

@@ -30,8 +30,9 @@ impl Operation for SetPropertyByName {
             object.to_object(context)?
         };
 
-        let name = context.vm.frame().code_block.names[index as usize];
+        let name: PropertyKey = context.vm.frame().code_block.names[index as usize]
-        let name: PropertyKey = context.interner().resolve_expect(name.sym()).utf16().into();
+            .clone()
+            .into();
 
         let succeeded = object.__set__(name.clone(), value.clone(), receiver, context)?;
         if !succeeded && context.vm.frame().code_block.strict {
@@ -163,11 +164,8 @@ impl Operation for SetPropertyGetterByName {
         let value = context.vm.pop();
         let object = context.vm.pop();
         let object = object.to_object(context)?;
-        let name = context.vm.frame().code_block.names[index as usize];
+        let name = context.vm.frame().code_block.names[index as usize]
-        let name = context
+            .clone()
-            .interner()
-            .resolve_expect(name.sym())
-            .into_common::<JsString>(false)
             .into();
         let set = object
             .__get_own_property__(&name, context)?
@@ -240,11 +238,8 @@ impl Operation for SetPropertySetterByName {
         let value = context.vm.pop();
         let object = context.vm.pop();
         let object = object.to_object(context)?;
-        let name = context.vm.frame().code_block.names[index as usize];
+        let name = context.vm.frame().code_block.names[index as usize]
-        let name = context
+            .clone()
-            .interner()
-            .resolve_expect(name.sym())
-            .into_common::<JsString>(false)
             .into();
         let get = object
             .__get_own_property__(&name, context)?