3x faster `TextEncoder.prototype.encodeInto`

thanks to @Constellation for the tip

4 files changed, 32 insertions, 23 deletions

diff --git a/bench/snippets/encode-into.mjs b/bench/snippets/encode-into.mjs
new file mode 100644
index 000000000..5275b6f10
--- /dev/null
+++ b/bench/snippets/encode-into.mjs
@@ -0,0 +1,10 @@
+import { run, bench } from "../node_modules/mitata/src/cli.mjs";
+
+const encoder = new TextEncoder();
+
+const buffer = new Uint8Array(1024);
+bench("encodeInto", () => {
+  encoder.encodeInto("Hello World!", buffer);
+});
+
+await run();
diff --git a/src/bun.js/bindings/ZigGlobalObject.cpp b/src/bun.js/bindings/ZigGlobalObject.cpp
index 467498aae..bcb42dc29 100644
--- a/src/bun.js/bindings/ZigGlobalObject.cpp
+++ b/src/bun.js/bindings/ZigGlobalObject.cpp
@@ -2490,12 +2490,18 @@ void GlobalObject::finishCreation(VM& vm)
             init.set(map);
         });
 
-    m_encodeIntoObjectPrototype.initLater(
-        [](const JSC::LazyProperty<JSC::JSGlobalObject, JSC::JSObject>::Initializer& init) {
-            JSC::JSObject* object = JSC::constructEmptyObject(init.owner, init.owner->objectPrototype(), 2);
-            object->putDirect(init.vm, JSC::Identifier::fromString(init.vm, "read"_s), JSC::jsNumber(0), 0);
-            object->putDirect(init.vm, JSC::Identifier::fromString(init.vm, "written"_s), JSC::jsNumber(0), 0);
-            init.set(object);
+    m_encodeIntoObjectStructure.initLater(
+        [](const JSC::LazyProperty<JSC::JSGlobalObject, JSC::Structure>::Initializer& init) {
+            auto& vm = init.vm;
+            auto& globalObject = *init.owner;
+            Structure* structure = globalObject.structureCache().emptyObjectStructureForPrototype(&globalObject, globalObject.objectPrototype(), 2);
+            PropertyOffset offset;
+            auto clientData = WebCore::clientData(vm);
+            structure = Structure::addPropertyTransition(vm, structure, clientData->builtinNames().readPublicName(), 0, offset);
+            RELEASE_ASSERT(offset == 0);
+            structure = Structure::addPropertyTransition(vm, structure, clientData->builtinNames().writtenPublicName(), 0, offset);
+            RELEASE_ASSERT(offset == 1);
+            init.set(structure);
         });
 
     m_JSFileSinkClassStructure.initLater(
@@ -3337,7 +3343,7 @@ void GlobalObject::visitChildrenImpl(JSCell* cell, Visitor& visitor)
     thisObject->m_performMicrotaskVariadicFunction.visit(visitor);
     thisObject->m_lazyReadableStreamPrototypeMap.visit(visitor);
     thisObject->m_requireMap.visit(visitor);
-    thisObject->m_encodeIntoObjectPrototype.visit(visitor);
+    thisObject->m_encodeIntoObjectStructure.visit(visitor);
     thisObject->m_JSArrayBufferControllerPrototype.visit(visitor);
     thisObject->m_JSFileSinkControllerPrototype.visit(visitor);
     thisObject->m_JSHTTPSResponseControllerPrototype.visit(visitor);
@@ -3608,8 +3614,6 @@ JSC::JSValue GlobalObject::moduleLoaderEvaluate(JSGlobalObject* globalObject,
     return result;
 }
 
-
-
 #include "ZigGeneratedClasses+lazyStructureImpl.h"
 
 } // namespace Zig
diff --git a/src/bun.js/bindings/ZigGlobalObject.h b/src/bun.js/bindings/ZigGlobalObject.h
index b537bbb12..bcc6cb804 100644
--- a/src/bun.js/bindings/ZigGlobalObject.h
+++ b/src/bun.js/bindings/ZigGlobalObject.h
@@ -229,7 +229,7 @@ public:
 
     JSC::JSMap* readableStreamNativeMap() { return m_lazyReadableStreamPrototypeMap.getInitializedOnMainThread(this); }
     JSC::JSMap* requireMap() { return m_requireMap.getInitializedOnMainThread(this); }
-    JSC::JSObject* encodeIntoObjectPrototype() { return m_encodeIntoObjectPrototype.getInitializedOnMainThread(this); }
+    JSC::Structure* encodeIntoObjectStructure() { return m_encodeIntoObjectStructure.getInitializedOnMainThread(this); }
 
     JSC::Structure* callSiteStructure() const { return m_callSiteStructure.getInitializedOnMainThread(this); }
 
@@ -483,7 +483,7 @@ private:
     LazyProperty<JSGlobalObject, JSFunction> m_emitReadableNextTickFunction;
     LazyProperty<JSGlobalObject, JSMap> m_lazyReadableStreamPrototypeMap;
     LazyProperty<JSGlobalObject, JSMap> m_requireMap;
-    LazyProperty<JSGlobalObject, JSObject> m_encodeIntoObjectPrototype;
+    LazyProperty<JSGlobalObject, Structure> m_encodeIntoObjectStructure;
     LazyProperty<JSGlobalObject, JSObject> m_JSArrayBufferControllerPrototype;
     LazyProperty<JSGlobalObject, JSObject> m_JSFileSinkControllerPrototype;
     LazyProperty<JSGlobalObject, JSObject> m_JSHTTPSResponseControllerPrototype;
diff --git a/src/bun.js/bindings/webcore/JSTextEncoder.cpp b/src/bun.js/bindings/webcore/JSTextEncoder.cpp
index 90092163f..09352b98f 100644
--- a/src/bun.js/bindings/webcore/JSTextEncoder.cpp
+++ b/src/bun.js/bindings/webcore/JSTextEncoder.cpp
@@ -296,11 +296,9 @@ JSC_DEFINE_JIT_OPERATION(jsTextEncoderPrototypeFunction_encodeIntoWithoutTypeChe
     }
 
     Zig::GlobalObject* globalObject = reinterpret_cast<Zig::GlobalObject*>(lexicalGlobalObject);
-    auto clientData = WebCore::clientData(vm);
-
-    auto* result = JSC::constructEmptyObject(globalObject, globalObject->encodeIntoObjectPrototype(), 2);
-    result->putDirect(vm, clientData->builtinNames().readPublicName(), JSC::jsNumber(static_cast<uint32_t>(res)), 0);
-    result->putDirect(vm, clientData->builtinNames().writtenPublicName(), JSC::jsNumber(static_cast<uint32_t>(res >> 32)), 0);
+    auto* result = JSC::constructEmptyObject(vm, globalObject->encodeIntoObjectStructure());
+    result->putDirectOffset(vm, 0, JSC::jsNumber(static_cast<uint32_t>(res)));
+    result->putDirectOffset(vm, 1, JSC::jsNumber(static_cast<uint32_t>(res >> 32)));
 
     return JSValue::encode(result);
 }
@@ -416,15 +414,13 @@ static inline JSC::EncodedJSValue jsTextEncoderPrototypeFunction_encodeIntoBody(
 {
     auto& vm = JSC::getVM(lexicalGlobalObject);
     auto throwScope = DECLARE_THROW_SCOPE(vm);
-    UNUSED_PARAM(throwScope);
-    UNUSED_PARAM(callFrame);
     if (UNLIKELY(callFrame->argumentCount() < 2))
         return throwVMError(lexicalGlobalObject, throwScope, createNotEnoughArgumentsError(lexicalGlobalObject));
     EnsureStillAliveScope argument0 = callFrame->uncheckedArgument(0);
     auto source = argument0.value().toWTFString(lexicalGlobalObject);
     RETURN_IF_EXCEPTION(throwScope, encodedJSValue());
     EnsureStillAliveScope argument1 = callFrame->uncheckedArgument(1);
-    auto* destination = JSC::jsDynamicCast<JSC::JSUint8Array*>(argument1.value());
+    auto* destination = JSC::jsDynamicCast<JSC::JSArrayBufferView*>(argument1.value());
     if (!destination) {
         throwVMTypeError(lexicalGlobalObject, throwScope, "Expected Uint8Array"_s);
         return encodedJSValue();
@@ -438,11 +434,10 @@ static inline JSC::EncodedJSValue jsTextEncoderPrototypeFunction_encodeIntoBody(
     }
 
     Zig::GlobalObject* globalObject = reinterpret_cast<Zig::GlobalObject*>(lexicalGlobalObject);
-    auto clientData = WebCore::clientData(vm);
 
-    auto* result = JSC::constructEmptyObject(globalObject, globalObject->encodeIntoObjectPrototype(), 2);
-    result->putDirect(vm, clientData->builtinNames().readPublicName(), JSC::jsNumber(static_cast<uint32_t>(res)), 0);
-    result->putDirect(vm, clientData->builtinNames().writtenPublicName(), JSC::jsNumber(static_cast<uint32_t>(res >> 32)), 0);
+    auto* result = JSC::constructEmptyObject(vm, globalObject->encodeIntoObjectStructure());
+    result->putDirectOffset(vm, 0, JSC::jsNumber(static_cast<uint32_t>(res)));
+    result->putDirectOffset(vm, 1, JSC::jsNumber(static_cast<uint32_t>(res >> 32)));
 
     return JSValue::encode(result);
 }