lazy builtins

.vscode/tasks.json

@@ -37,7 +37,7 @@
       "type": "process",
       "label": "Run JS file",
       "command": "cargo",
-      "args": ["run", "--bin", "boa", "${file}"],
+      "args": ["run", "--bin", "boa", "${workspaceFolder}/debug/script.js"],
       "group": {
         "kind": "build",
         "isDefault": true

CHANGELOG.md

@@ -2,7 +2,7 @@
 
 ## What's Changed
 
-# [0.20.0 (2024-09-11)](https://github.com/boa-dev/boa/compare/v0.19.1...v0.20.0)
+# [0.20.0 (2024-12-5)](https://github.com/boa-dev/boa/compare/v0.19.1...v0.20.0)
 
 ### Feature Enhancements
 
@@ -61,6 +61,7 @@
 - Update night build's rename binary step by @nekevss in https://github.com/boa-dev/boa/pull/4032
 - Use upload-rust-binary-action for nightly release by @nekevss in https://github.com/boa-dev/boa/pull/4040
 - Fix `ref` value in nightly and add target to nightly release by @nekevss in https://github.com/boa-dev/boa/pull/4042
+- Reduce environment allocations by @raskad in https://github.com/boa-dev/boa/pull/4002
 
 ### Other Changes
 

Cargo.toml

@@ -23,7 +23,7 @@ exclude = [
 
 [workspace.package]
 edition = "2021"
-version = "0.19.0"
+version = "0.20.0"
 rust-version = "1.82.0"
 authors = ["boa-dev"]
 repository = "https://github.com/boa-dev/boa"
@@ -33,17 +33,17 @@ description = "Boa is a Javascript lexer, parser and compiler written in Rust. C
 [workspace.dependencies]
 
 # Repo Crates
-boa_ast = { version = "~0.19.0", path = "core/ast" }
-boa_engine = { version = "~0.19.0", path = "core/engine" }
-boa_gc = { version = "~0.19.0", path = "core/gc" }
-boa_icu_provider = { version = "~0.19.0", path = "core/icu_provider" }
-boa_interner = { version = "~0.19.0", path = "core/interner" }
-boa_interop = { version = "~0.19.0", path = "core/interop" }
-boa_macros = { version = "~0.19.0", path = "core/macros" }
-boa_parser = { version = "~0.19.0", path = "core/parser" }
-boa_profiler = { version = "~0.19.0", path = "core/profiler" }
-boa_runtime = { version = "~0.19.0", path = "core/runtime" }
-boa_string = { version = "~0.19.0", path = "core/string" }
+boa_ast = { version = "~0.20.0", path = "core/ast" }
+boa_engine = { version = "~0.20.0", path = "core/engine" }
+boa_gc = { version = "~0.20.0", path = "core/gc" }
+boa_icu_provider = { version = "~0.20.0", path = "core/icu_provider" }
+boa_interner = { version = "~0.20.0", path = "core/interner" }
+boa_interop = { version = "~0.20.0", path = "core/interop" }
+boa_macros = { version = "~0.20.0", path = "core/macros" }
+boa_parser = { version = "~0.20.0", path = "core/parser" }
+boa_profiler = { version = "~0.20.0", path = "core/profiler" }
+boa_runtime = { version = "~0.20.0", path = "core/runtime" }
+boa_string = { version = "~0.20.0", path = "core/string" }
 
 # Shared deps
 arbitrary = "1"

core/engine/src/builtins/builder.rs

@@ -3,7 +3,7 @@ use crate::{
     native_function::{NativeFunctionObject, NativeFunctionPointer},
     object::{
         shape::{property_table::PropertyTableInner, slot::SlotAttributes},
-        FunctionBinding, JsFunction, JsPrototype, CONSTRUCTOR, PROTOTYPE,
+        FunctionBinding, JsFunction, JsPrototype, LazyBuiltIn, CONSTRUCTOR, PROTOTYPE,
     },
     property::{Attribute, PropertyDescriptor, PropertyKey},
     realm::Realm,
@@ -392,12 +392,25 @@ impl BuiltInConstructorWithPrototype<'_> {
         }
 
         let mut object = self.object.borrow_mut();
-        let function = object
-            .downcast_mut::<NativeFunctionObject>()
-            .expect("Builtin must be a function object");
-        function.f = NativeFunction::from_fn_ptr(self.function);
-        function.constructor = Some(ConstructorKind::Base);
-        function.realm = Some(self.realm.clone());
+        if object.is::<NativeFunctionObject>() {
+            let function = object
+                .downcast_mut::<NativeFunctionObject>()
+                .expect("Builtin must be a function object");
+            function.f = NativeFunction::from_fn_ptr(self.function);
+            function.constructor = Some(ConstructorKind::Base);
+            function.realm = Some(self.realm.clone());
+        } else if object.is::<LazyBuiltIn>() {
+            let lazy = object
+                .downcast_mut::<LazyBuiltIn>()
+                .expect("Builtin must be a lazy object");
+            lazy.set_constructor(
+                NativeFunction::from_fn_ptr(self.function),
+                self.realm.clone(),
+            );
+        } else {
+            unreachable!("The object must be a function or a lazy object");
+        }
+
         object
             .properties_mut()
             .shape

core/engine/src/builtins/function/mod.rs

@@ -26,7 +26,7 @@ use crate::{
             get_prototype_from_constructor, CallValue, InternalObjectMethods,
             ORDINARY_INTERNAL_METHODS,
         },
-        JsData, JsFunction, JsObject, PrivateElement, PrivateName,
+        JsData, JsFunction, JsObject, LazyBuiltIn, PrivateElement, PrivateName,
     },
     property::{Attribute, PropertyDescriptor, PropertyKey},
     realm::Realm,
@@ -845,8 +845,7 @@ impl BuiltInFunctionObject {
             return Err(JsNativeError::typ().with_message("not a function").into());
         };
 
-        let object_borrow = object.borrow();
-        if object_borrow.is::<NativeFunctionObject>() {
+        if object.is::<NativeFunctionObject>() || object.is::<LazyBuiltIn>() {
             let name = {
                 // Is there a case here where if there is no name field on a value
                 // name should default to None? Do all functions have names set?
@@ -860,10 +859,11 @@ impl BuiltInFunctionObject {
             return Ok(
                 js_string!(js_str!("function "), &name, js_str!("() { [native code] }")).into(),
             );
-        } else if object_borrow.is::<Proxy>() || object_borrow.is::<BoundFunction>() {
+        } else if object.is::<Proxy>() || object.is::<BoundFunction>() {
             return Ok(js_string!("function () { [native code] }").into());
         }
 
+        let object_borrow = object.borrow();
         let function = object_borrow
             .downcast_ref::<OrdinaryFunction>()
             .ok_or_else(|| JsNativeError::typ().with_message("not a function"))?;

core/engine/src/builtins/mod.rs

@@ -208,7 +208,6 @@ impl Realm {
         ForInIterator::init(self);
         Math::init(self);
         Json::init(self);
-        Array::init(self);
         ArrayIterator::init(self);
         Proxy::init(self);
         ArrayBuffer::init(self);