[async-iteration] eliminate Suspend for AsyncGeneratorYield await

A spec change (https://github.com/tc39/proposal-async-iteration/commit/a0dfeba1a8029012b6e964099929b8a157818c9f) introduced a number of Await operations to the spec. In turn, this caused generated bytecode for async generators to grow drastically.

This commit moves the Await within AsyncGeneratorYield (https://tc39.github.io/proposal-async-iteration/#sec-asyncgeneratoryield step 5) into a new TFJ builtin, similar in structure to AsyncGeneratorAwait, but instead of resuming the generator on resolution of the Promise, the current generator request's Promise is fulfilled instead.

This results in a reduction in generated bytecode without losing any statically available information.

BUG=v8:5855

Change-Id: Ib5bcf06132d221beffdea30639a7b4437030143b
Reviewed-on: https://chromium-review.googlesource.com/582487
Commit-Queue: Caitlin Potter <caitp@igalia.com>
Reviewed-by: Georg Neis <neis@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47224}

src/bootstrapper.cc

@@ -1488,6 +1488,12 @@ void Genesis::InitializeGlobal(Handle<JSGlobalObject> global_object,
     info->set_length(1);
     native_context()->set_async_generator_await_reject_shared_fun(*info);
 
+    code = BUILTIN_CODE(isolate, AsyncGeneratorYieldResolveClosure);
+    info = factory->NewSharedFunctionInfo(factory->empty_string(), code, false);
+    info->set_internal_formal_parameter_count(1);
+    info->set_length(1);
+    native_context()->set_async_generator_yield_resolve_shared_fun(*info);
+
     code = BUILTIN_CODE(isolate, AsyncGeneratorReturnResolveClosure);
     info = factory->NewSharedFunctionInfo(factory->empty_string(), code, false);
     info->set_internal_formal_parameter_count(1);

src/builtins/builtins-async-gen.cc

@@ -23,7 +23,7 @@ Node* AsyncBuiltinsAssembler::Await(
     Node* context, Node* generator, Node* value, Node* outer_promise,
     int context_length, const ContextInitializer& init_closure_context,
     int on_resolve_context_index, int on_reject_context_index,
-    bool is_predicted_as_caught) {
+    Node* is_predicted_as_caught) {
   DCHECK_GE(context_length, Context::MIN_CONTEXT_SLOTS);
 
   Node* const native_context = LoadNativeContext(context);
@@ -146,7 +146,8 @@ Node* AsyncBuiltinsAssembler::Await(
       CallRuntime(Runtime::kSetProperty, context, on_reject, key,
                   TrueConstant(), SmiConstant(STRICT));
 
-      if (is_predicted_as_caught) PromiseSetHandledHint(value);
+      GotoIf(IsFalse(is_predicted_as_caught), &common);
+      PromiseSetHandledHint(value);
     }
 
     Goto(&common);

src/builtins/builtins-async-gen.h

@@ -27,7 +27,17 @@ class AsyncBuiltinsAssembler : public PromiseBuiltinsAssembler {
               int context_length,
               const ContextInitializer& init_closure_context,
               int on_resolve_context_index, int on_reject_context_index,
-              bool is_predicted_as_caught);
+              Node* is_predicted_as_caught);
+  Node* Await(Node* context, Node* generator, Node* value, Node* outer_promise,
+              int context_length,
+              const ContextInitializer& init_closure_context,
+              int on_resolve_context_index, int on_reject_context_index,
+              bool is_predicted_as_caught) {
+    return Await(context, generator, value, outer_promise, context_length,
+                 init_closure_context, on_resolve_context_index,
+                 on_reject_context_index,
+                 BooleanConstant(is_predicted_as_caught));
+  }
 
   // Return a new built-in function object as defined in
   // Async Iterator Value Unwrap Functions

src/builtins/builtins-async-generator-gen.cc

@@ -539,6 +539,48 @@ TF_BUILTIN(AsyncGeneratorReject, AsyncGeneratorBuiltinsAssembler) {
                      TrueConstant()));
 }
 
+TF_BUILTIN(AsyncGeneratorYield, AsyncGeneratorBuiltinsAssembler) {
+  Node* const generator = Parameter(Descriptor::kGenerator);
+  Node* const value = Parameter(Descriptor::kValue);
+  Node* const is_caught = Parameter(Descriptor::kIsCaught);
+  Node* const context = Parameter(Descriptor::kContext);
+
+  Node* const request = LoadFirstAsyncGeneratorRequestFromQueue(generator);
+  Node* const outer_promise = LoadPromiseFromAsyncGeneratorRequest(request);
+
+  ContextInitializer init_closure_context = [&](Node* context) {
+    StoreContextElementNoWriteBarrier(context, AwaitContext::kGeneratorSlot,
+                                      generator);
+  };
+
+  const int on_resolve = Context::ASYNC_GENERATOR_YIELD_RESOLVE_SHARED_FUN;
+  const int on_reject = Context::ASYNC_GENERATOR_AWAIT_REJECT_SHARED_FUN;
+
+  Node* const promise =
+      Await(context, generator, value, outer_promise, AwaitContext::kLength,
+            init_closure_context, on_resolve, on_reject, is_caught);
+  StoreObjectField(generator, JSAsyncGeneratorObject::kAwaitedPromiseOffset,
+                   promise);
+  Return(UndefinedConstant());
+}
+
+TF_BUILTIN(AsyncGeneratorYieldResolveClosure, AsyncGeneratorBuiltinsAssembler) {
+  Node* const context = Parameter(Descriptor::kContext);
+  Node* const value = Parameter(Descriptor::kValue);
+  Node* const generator =
+      LoadContextElement(context, AwaitContext::kGeneratorSlot);
+
+  CSA_SLOW_ASSERT(this, IsGeneratorSuspendedForAwait(generator));
+  ClearAwaitedPromise(generator);
+
+  // Per proposal-async-iteration/#sec-asyncgeneratoryield step 9
+  // Return ! AsyncGeneratorResolve(_F_.[[Generator]], _value_, *false*).
+  CallBuiltin(Builtins::kAsyncGeneratorResolve, context, generator, value,
+              FalseConstant());
+
+  TailCallBuiltin(Builtins::kAsyncGeneratorResumeNext, context, generator);
+}
+
 TF_BUILTIN(AsyncGeneratorReturnProcessor, AsyncGeneratorBuiltinsAssembler) {
   Node* const generator = Parameter(Descriptor::kGenerator);
   Node* const req = LoadFirstAsyncGeneratorRequestFromQueue(generator);

src/builtins/builtins-definitions.h

@@ -1053,6 +1053,7 @@ namespace internal {
                                                                                \
   TFS(AsyncGeneratorResolve, kGenerator, kValue, kDone)                        \
   TFS(AsyncGeneratorReject, kGenerator, kValue)                                \
+  TFS(AsyncGeneratorYield, kGenerator, kValue, kIsCaught)                      \
   TFS(AsyncGeneratorReturnProcessor, kGenerator)                               \
   TFS(AsyncGeneratorResumeNext, kGenerator)                                    \
                                                                                \
@@ -1078,6 +1079,7 @@ namespace internal {
   TFJ(AsyncGeneratorAwaitUncaught, 1, kAwaited)                                \
   TFJ(AsyncGeneratorAwaitResolveClosure, 1, kValue)                            \
   TFJ(AsyncGeneratorAwaitRejectClosure, 1, kValue)                             \
+  TFJ(AsyncGeneratorYieldResolveClosure, 1, kValue)                            \
   TFJ(AsyncGeneratorReturnResolveClosure, 1, kValue)                           \
   TFJ(AsyncGeneratorReturnRejectClosure, 1, kValue)                            \
                                                                                \

src/compiler/js-intrinsic-lowering.cc

@@ -46,6 +46,8 @@ Reduction JSIntrinsicLowering::Reduce(Node* node) {
       return ReduceAsyncGeneratorReject(node);
     case Runtime::kInlineAsyncGeneratorResolve:
       return ReduceAsyncGeneratorResolve(node);
+    case Runtime::kInlineAsyncGeneratorYield:
+      return ReduceAsyncGeneratorYield(node);
     case Runtime::kInlineGeneratorGetResumeMode:
       return ReduceGeneratorGetResumeMode(node);
     case Runtime::kInlineGeneratorGetContext:
@@ -198,6 +200,12 @@ Reduction JSIntrinsicLowering::ReduceAsyncGeneratorResolve(Node* node) {
       0);
 }
 
+Reduction JSIntrinsicLowering::ReduceAsyncGeneratorYield(Node* node) {
+  return Change(
+      node, Builtins::CallableFor(isolate(), Builtins::kAsyncGeneratorYield),
+      0);
+}
+
 Reduction JSIntrinsicLowering::ReduceGeneratorGetContext(Node* node) {
   Node* const generator = NodeProperties::GetValueInput(node, 0);
   Node* const effect = NodeProperties::GetEffectInput(node);

src/compiler/js-intrinsic-lowering.h

@@ -51,6 +51,7 @@ class V8_EXPORT_PRIVATE JSIntrinsicLowering final
   Reduction ReduceGeneratorGetInputOrDebugPos(Node* node);
   Reduction ReduceAsyncGeneratorReject(Node* node);
   Reduction ReduceAsyncGeneratorResolve(Node* node);
+  Reduction ReduceAsyncGeneratorYield(Node* node);
   Reduction ReduceGeneratorSaveInputForAwait(Node* node);
   Reduction ReduceGeneratorGetResumeMode(Node* node);
   Reduction ReduceIsInstanceType(Node* node, InstanceType instance_type);

src/contexts.h

@@ -217,6 +217,8 @@ enum ContextLookupFlags {
     async_generator_await_reject_shared_fun)                                   \
   V(ASYNC_GENERATOR_AWAIT_RESOLVE_SHARED_FUN, SharedFunctionInfo,              \
     async_generator_await_resolve_shared_fun)                                  \
+  V(ASYNC_GENERATOR_YIELD_RESOLVE_SHARED_FUN, SharedFunctionInfo,              \
+    async_generator_yield_resolve_shared_fun)                                  \
   V(ASYNC_GENERATOR_RETURN_RESOLVE_SHARED_FUN, SharedFunctionInfo,             \
     async_generator_return_resolve_shared_fun)                                 \
   V(ASYNC_GENERATOR_RETURN_REJECT_SHARED_FUN, SharedFunctionInfo,              \

src/interpreter/bytecode-array-builder.cc

@@ -631,6 +631,10 @@ BytecodeArrayBuilder& BytecodeArrayBuilder::LoadFalse() {
   return *this;
 }
 
+BytecodeArrayBuilder& BytecodeArrayBuilder::LoadBoolean(bool value) {
+  return value ? LoadTrue() : LoadFalse();
+}
+
 BytecodeArrayBuilder& BytecodeArrayBuilder::LoadAccumulatorWithRegister(
     Register reg) {
   if (register_optimizer_) {

src/interpreter/bytecode-array-builder.h

@@ -79,6 +79,7 @@ class V8_EXPORT_PRIVATE BytecodeArrayBuilder final
   BytecodeArrayBuilder& LoadTheHole();
   BytecodeArrayBuilder& LoadTrue();
   BytecodeArrayBuilder& LoadFalse();
+  BytecodeArrayBuilder& LoadBoolean(bool value);
 
   // Global loads to the accumulator and stores from the accumulator.
   BytecodeArrayBuilder& LoadGlobal(const AstRawString* name, int feedback_slot,

src/interpreter/bytecode-generator.cc

@@ -2602,25 +2602,25 @@ void BytecodeGenerator::VisitYield(Yield* expr) {
   if (!expr->IsInitialYield()) {
     if (IsAsyncGeneratorFunction(function_kind())) {
       // AsyncGenerator yields (with the exception of the initial yield)
-      // delegate to AsyncGeneratorResolve(), implemented via the runtime call
-      // below.
+      // delegate work to the AsyncGeneratorYield stub, which Awaits the operand
+      // and on success, wraps the value in an IteratorResult.
       RegisterAllocationScope register_scope(this);
       RegisterList args = register_allocator()->NewRegisterList(3);
       builder()
-          ->MoveRegister(generator_object_, args[0])
-          .StoreAccumulatorInRegister(args[1])
-          .LoadFalse()
-          .StoreAccumulatorInRegister(args[2])
-          .CallRuntime(Runtime::kInlineAsyncGeneratorResolve, args);
+          ->MoveRegister(generator_object_, args[0])  // generator
+          .StoreAccumulatorInRegister(args[1])        // value
+          .LoadBoolean(catch_prediction() != HandlerTable::ASYNC_AWAIT)
+          .StoreAccumulatorInRegister(args[2])        // is_caught
+          .CallRuntime(Runtime::kInlineAsyncGeneratorYield, args);
     } else {
       // Generator yields (with the exception of the initial yield) wrap the
       // value into IteratorResult.
       RegisterAllocationScope register_scope(this);
       RegisterList args = register_allocator()->NewRegisterList(2);
       builder()
-          ->StoreAccumulatorInRegister(args[0])
+          ->StoreAccumulatorInRegister(args[0])  // value
           .LoadFalse()
-          .StoreAccumulatorInRegister(args[1])
+          .StoreAccumulatorInRegister(args[1])   // done
           .CallRuntime(Runtime::kInlineCreateIterResultObject, args);
     }
   }

src/interpreter/interpreter-intrinsics-generator.cc

@@ -439,6 +439,11 @@ Node* IntrinsicsGenerator::AsyncGeneratorResolve(Node* input, Node* arg_count,
                                 Builtins::kAsyncGeneratorResolve);
 }
 
+Node* IntrinsicsGenerator::AsyncGeneratorYield(Node* input, Node* arg_count,
+                                               Node* context) {
+  return IntrinsicAsBuiltinCall(input, context, Builtins::kAsyncGeneratorYield);
+}
+
 void IntrinsicsGenerator::AbortIfArgCountMismatch(int expected, Node* actual) {
   InterpreterAssembler::Label match(assembler_);
   Node* comparison = __ Word32Equal(actual, __ Int32Constant(expected));

src/interpreter/interpreter-intrinsics.h

@@ -16,6 +16,7 @@ namespace interpreter {
 #define INTRINSICS_LIST(V)                                            \
   V(AsyncGeneratorReject, async_generator_reject, 2)                  \
   V(AsyncGeneratorResolve, async_generator_resolve, 3)                \
+  V(AsyncGeneratorYield, async_generator_yield, 3)                    \
   V(CreateJSGeneratorObject, create_js_generator_object, 2)           \
   V(GeneratorGetContext, generator_get_context, 1)                    \
   V(GeneratorGetResumeMode, generator_get_resume_mode, 1)             \

src/parsing/parser-base.h

@@ -2949,12 +2949,6 @@ typename ParserBase<Impl>::ExpressionT ParserBase<Impl>::ParseYieldExpression(
     return impl()->RewriteYieldStar(expression, pos);
   }
 
-  if (is_async_generator()) {
-    // Per https://github.com/tc39/proposal-async-iteration/pull/102, the yield
-    // operand must be Await-ed in async generators.
-    expression = factory()->NewAwait(expression, pos);
-  }
-
   // Hackily disambiguate o from o.next and o [Symbol.iterator]().
   // TODO(verwaest): Come up with a better solution.
   ExpressionT yield =

src/runtime/runtime-generator.cc

@@ -80,6 +80,12 @@ RUNTIME_FUNCTION(Runtime_AsyncGeneratorReject) {
   UNREACHABLE();
 }
 
+RUNTIME_FUNCTION(Runtime_AsyncGeneratorYield) {
+  // Runtime call is implemented in InterpreterIntrinsics and lowered in
+  // JSIntrinsicLowering
+  UNREACHABLE();
+}
+
 RUNTIME_FUNCTION(Runtime_GeneratorGetResumeMode) {
   // Runtime call is implemented in InterpreterIntrinsics and lowered in
   // JSIntrinsicLowering

src/runtime/runtime.h

@@ -230,17 +230,18 @@ namespace internal {
   F(IsFunction, 1, 1)                      \
   F(FunctionToString, 1, 1)
 
-#define FOR_EACH_INTRINSIC_GENERATOR(F)          \
-  F(CreateJSGeneratorObject, 2, 1)               \
-  F(GeneratorClose, 1, 1)                        \
-  F(GeneratorGetFunction, 1, 1)                  \
-  F(GeneratorGetReceiver, 1, 1)                  \
-  F(GeneratorGetContext, 1, 1)                   \
-  F(GeneratorGetInputOrDebugPos, 1, 1)           \
-  F(AsyncGeneratorResolve, 3, 1)                 \
-  F(AsyncGeneratorReject, 2, 1)                  \
-  F(GeneratorGetContinuation, 1, 1)              \
-  F(GeneratorGetSourcePosition, 1, 1)            \
+#define FOR_EACH_INTRINSIC_GENERATOR(F) \
+  F(CreateJSGeneratorObject, 2, 1)      \
+  F(GeneratorClose, 1, 1)               \
+  F(GeneratorGetFunction, 1, 1)         \
+  F(GeneratorGetReceiver, 1, 1)         \
+  F(GeneratorGetContext, 1, 1)          \
+  F(GeneratorGetInputOrDebugPos, 1, 1)  \
+  F(AsyncGeneratorResolve, 3, 1)        \
+  F(AsyncGeneratorReject, 2, 1)         \
+  F(AsyncGeneratorYield, 3, 1)          \
+  F(GeneratorGetContinuation, 1, 1)     \
+  F(GeneratorGetSourcePosition, 1, 1)   \
   F(GeneratorGetResumeMode, 1, 1)
 
 #ifdef V8_INTL_SUPPORT

test/cctest/interpreter/bytecode_expectations/AsyncGenerators.golden

@@ -169,7 +169,7 @@ snippet: "
 "
 frame size: 10
 parameter count: 1
-bytecode array length: 446
+bytecode array length: 401
 bytecodes: [
                 B(Mov), R(new_target), R(1),
                 B(Ldar), R(new_target),
@@ -178,7 +178,7 @@ bytecodes: [
                 B(PushContext), R(3),
                 B(RestoreGeneratorState), R(1),
                 B(Star), R(2),
-                B(SwitchOnSmiNoFeedback), U8(0), U8(6), I8(0),
+                B(SwitchOnSmiNoFeedback), U8(0), U8(5), I8(0),
                 B(LdaSmi), I8(46),
                 B(Star), R(3),
                 B(CallRuntime), U16(Runtime::kAbort), R(3), U8(1),
@@ -201,7 +201,7 @@ bytecodes: [
                 B(InvokeIntrinsic), U8(Runtime::k_GeneratorGetInputOrDebugPos), R(1), U8(1),
                 B(Star), R(7),
                 B(InvokeIntrinsic), U8(Runtime::k_GeneratorGetResumeMode), R(1), U8(1),
-                B(SwitchOnSmiNoFeedback), U8(6), U8(2), I8(0),
+                B(SwitchOnSmiNoFeedback), U8(5), U8(2), I8(0),
                 B(Ldar), R(7),
   /*   17 E> */ B(Throw),
                 B(Mov), R(1), R(8),
@@ -224,31 +224,13 @@ bytecodes: [
                 B(LdaZero),
                 B(Star), R(3),
                 B(Mov), R(8), R(4),
-                B(Jump), U8(247),
+                B(Jump), U8(202),
   /*   22 S> */ B(LdaSmi), I8(42),
-                B(Star), R(8),
-                B(Mov), R(1), R(7),
-                B(CallJSRuntime), U8(%async_generator_await_uncaught), R(7), U8(2),
-                B(SuspendGenerator), R(1), R(0), U8(7), U8(4),
-  /*   31 S> */ B(Return),
-                B(RestoreGeneratorRegisters), R(1), R(0), U8(7),
-                B(LdaSmi), I8(-2),
-                B(Star), R(2),
-                B(InvokeIntrinsic), U8(Runtime::k_GeneratorGetInputOrDebugPos), R(1), U8(1),
-                B(Star), R(7),
-                B(InvokeIntrinsic), U8(Runtime::k_GeneratorGetResumeMode), R(1), U8(1),
-                B(Star), R(8),
-                B(LdaZero),
-                B(TestEqualStrictNoFeedback), R(8),
-                B(JumpIfTrue), U8(5),
-                B(Ldar), R(7),
-                B(ReThrow),
-                B(Ldar), R(7),
                 B(Star), R(8),
                 B(LdaFalse),
                 B(Star), R(9),
                 B(Mov), R(1), R(7),
-                B(InvokeIntrinsic), U8(Runtime::k_AsyncGeneratorResolve), R(7), U8(3),
+                B(InvokeIntrinsic), U8(Runtime::k_AsyncGeneratorYield), R(7), U8(3),
                 B(SuspendGenerator), R(1), R(0), U8(7), U8(2),
   /*   31 S> */ B(Return),
                 B(RestoreGeneratorRegisters), R(1), R(0), U8(7),
@@ -257,7 +239,7 @@ bytecodes: [
                 B(InvokeIntrinsic), U8(Runtime::k_GeneratorGetInputOrDebugPos), R(1), U8(1),
                 B(Star), R(7),
                 B(InvokeIntrinsic), U8(Runtime::k_GeneratorGetResumeMode), R(1), U8(1),
-                B(SwitchOnSmiNoFeedback), U8(8), U8(2), I8(0),
+                B(SwitchOnSmiNoFeedback), U8(7), U8(2), I8(0),
                 B(Ldar), R(7),
   /*   22 E> */ B(Throw),
                 B(Mov), R(1), R(8),
@@ -285,7 +267,7 @@ bytecodes: [
                 B(Star), R(8),
                 B(Mov), R(1), R(7),
                 B(CallJSRuntime), U8(%async_generator_await_uncaught), R(7), U8(2),
-                B(SuspendGenerator), R(1), R(0), U8(7), U8(5),
+                B(SuspendGenerator), R(1), R(0), U8(7), U8(4),
   /*   31 S> */ B(Return),
                 B(RestoreGeneratorRegisters), R(1), R(0), U8(7),
                 B(LdaSmi), I8(-2),
@@ -306,7 +288,7 @@ bytecodes: [
                 B(Jump), U8(39),
                 B(Star), R(7),
                 B(Ldar), R(closure),
-                B(CreateCatchContext), R(7), U8(10), U8(11),
+                B(CreateCatchContext), R(7), U8(9), U8(10),
                 B(Star), R(6),
                 B(LdaTheHole),
                 B(SetPendingMessage),
@@ -334,7 +316,7 @@ bytecodes: [
                 B(Ldar), R(5),
                 B(SetPendingMessage),
                 B(Ldar), R(3),
-                B(SwitchOnSmiNoFeedback), U8(12), U8(3), I8(0),
+                B(SwitchOnSmiNoFeedback), U8(11), U8(3), I8(0),
                 B(Jump), U8(34),
                 B(LdaTrue),
                 B(Star), R(8),
@@ -359,10 +341,9 @@ bytecodes: [
 constant pool: [
   Smi [46],
   Smi [87],
-  Smi [188],
-  Smi [229],
-  Smi [140],
-  Smi [281],
+  Smi [143],
+  Smi [184],
+  Smi [236],
   Smi [59],
   Smi [7],
   Smi [59],
@@ -374,8 +355,8 @@ constant pool: [
   Smi [35],
 ]
 handlers: [
-  [52, 373, 379],
-  [55, 334, 336],
+  [52, 328, 334],
+  [55, 289, 291],
 ]
 
 ---
@@ -385,7 +366,7 @@ snippet: "
 "
 frame size: 23
 parameter count: 1
-bytecode array length: 742
+bytecode array length: 697
 bytecodes: [
                 B(Mov), R(new_target), R(10),
                 B(Ldar), R(new_target),
@@ -394,7 +375,7 @@ bytecodes: [
                 B(PushContext), R(12),
                 B(RestoreGeneratorState), R(10),
                 B(Star), R(11),
-                B(SwitchOnSmiNoFeedback), U8(0), U8(6), I8(0),
+                B(SwitchOnSmiNoFeedback), U8(0), U8(5), I8(0),
                 B(LdaSmi), I8(46),
                 B(Star), R(12),
                 B(CallRuntime), U16(Runtime::kAbort), R(12), U8(1),
@@ -417,7 +398,7 @@ bytecodes: [
                 B(InvokeIntrinsic), U8(Runtime::k_GeneratorGetInputOrDebugPos), R(10), U8(1),
                 B(Star), R(16),
                 B(InvokeIntrinsic), U8(Runtime::k_GeneratorGetResumeMode), R(10), U8(1),
-                B(SwitchOnSmiNoFeedback), U8(6), U8(2), I8(0),
+                B(SwitchOnSmiNoFeedback), U8(5), U8(2), I8(0),
                 B(Ldar), R(16),
   /*   17 E> */ B(Throw),
                 B(Mov), R(10), R(17),
@@ -440,30 +421,30 @@ bytecodes: [
                 B(LdaZero),
                 B(Star), R(12),
                 B(Mov), R(17), R(13),
-                B(JumpConstant), U8(26),
+                B(JumpConstant), U8(24),
                 B(LdaTheHole),
                 B(Star), R(1),
                 B(LdaZero),
                 B(Star), R(6),
                 B(Mov), R(context), R(18),
                 B(Mov), R(context), R(19),
-  /*   36 S> */ B(CreateArrayLiteral), U8(8), U8(0), U8(37),
+  /*   36 S> */ B(CreateArrayLiteral), U8(7), U8(0), U8(37),
                 B(Star), R(20),
-                B(LdaNamedProperty), R(20), U8(9), U8(1),
+                B(LdaNamedProperty), R(20), U8(8), U8(1),
                 B(Star), R(21),
                 B(CallProperty0), R(21), R(20), U8(3),
                 B(JumpIfJSReceiver), U8(7),
                 B(CallRuntime), U16(Runtime::kThrowSymbolIteratorInvalid), R(0), U8(0),
                 B(Star), R(4),
                 B(Ldar), R(11),
-                B(SwitchOnSmiNoFeedback), U8(10), U8(3), I8(2),
+                B(SwitchOnSmiNoFeedback), U8(9), U8(2), I8(2),
                 B(LdaSmi), I8(-2),
   /*   36 E> */ B(TestEqualStrictNoFeedback), R(11),
                 B(JumpIfTrue), U8(11),
                 B(LdaSmi), I8(46),
                 B(Star), R(20),
                 B(CallRuntime), U16(Runtime::kAbort), R(20), U8(1),
-  /*   31 S> */ B(LdaNamedProperty), R(4), U8(13), U8(7),
+  /*   31 S> */ B(LdaNamedProperty), R(4), U8(11), U8(7),
                 B(Star), R(20),
                 B(CallProperty0), R(20), R(4), U8(5),
                 B(Star), R(5),
@@ -471,38 +452,20 @@ bytecodes: [
                 B(ToBooleanLogicalNot),
                 B(JumpIfFalse), U8(7),
                 B(CallRuntime), U16(Runtime::kThrowIteratorResultNotAnObject), R(5), U8(1),
-                B(LdaNamedProperty), R(5), U8(14), U8(9),
-                B(JumpIfToBooleanTrue), U8(166),
-                B(LdaNamedProperty), R(5), U8(15), U8(11),
+                B(LdaNamedProperty), R(5), U8(12), U8(9),
+                B(JumpIfToBooleanTrue), U8(121),
+                B(LdaNamedProperty), R(5), U8(13), U8(11),
                 B(Star), R(7),
                 B(LdaSmi), I8(2),
                 B(Star), R(6),
                 B(Mov), R(7), R(3),
   /*   22 E> */ B(StackCheck),
                 B(Mov), R(3), R(0),
-  /*   42 S> */ B(Mov), R(10), R(20),
-                B(Mov), R(0), R(21),
-                B(CallJSRuntime), U8(%async_generator_await_uncaught), R(20), U8(2),
-                B(SuspendGenerator), R(10), R(0), U8(20), U8(4),
-  /*   50 S> */ B(Return),
-                B(RestoreGeneratorRegisters), R(10), R(0), U8(20),
-                B(LdaSmi), I8(-2),
-                B(Star), R(11),
-                B(InvokeIntrinsic), U8(Runtime::k_GeneratorGetInputOrDebugPos), R(10), U8(1),
-                B(Star), R(20),
-                B(InvokeIntrinsic), U8(Runtime::k_GeneratorGetResumeMode), R(10), U8(1),
-                B(Star), R(21),
-                B(LdaZero),
-                B(TestEqualStrictNoFeedback), R(21),
-                B(JumpIfTrue), U8(5),
-                B(Ldar), R(20),
-                B(ReThrow),
-                B(Ldar), R(20),
-                B(Star), R(21),
-                B(LdaFalse),
+  /*   42 S> */ B(LdaFalse),
                 B(Star), R(22),
                 B(Mov), R(10), R(20),
-                B(InvokeIntrinsic), U8(Runtime::k_AsyncGeneratorResolve), R(20), U8(3),
+                B(Mov), R(0), R(21),
+                B(InvokeIntrinsic), U8(Runtime::k_AsyncGeneratorYield), R(20), U8(3),
                 B(SuspendGenerator), R(10), R(0), U8(20), U8(2),
   /*   50 S> */ B(Return),
                 B(RestoreGeneratorRegisters), R(10), R(0), U8(20),
@@ -511,7 +474,7 @@ bytecodes: [
                 B(InvokeIntrinsic), U8(Runtime::k_GeneratorGetInputOrDebugPos), R(10), U8(1),
                 B(Star), R(20),
                 B(InvokeIntrinsic), U8(Runtime::k_GeneratorGetResumeMode), R(10), U8(1),
-                B(SwitchOnSmiNoFeedback), U8(16), U8(2), I8(0),
+                B(SwitchOnSmiNoFeedback), U8(14), U8(2), I8(0),
                 B(Ldar), R(20),
   /*   42 E> */ B(Throw),
                 B(Mov), R(10), R(21),
@@ -537,11 +500,11 @@ bytecodes: [
                 B(Jump), U8(60),
                 B(LdaZero),
                 B(Star), R(6),
-                B(JumpLoop), U8(212), I8(0),
+                B(JumpLoop), U8(167), I8(0),
                 B(Jump), U8(40),
                 B(Star), R(20),
                 B(Ldar), R(closure),
-                B(CreateCatchContext), R(20), U8(18), U8(19),
+                B(CreateCatchContext), R(20), U8(16), U8(17),
                 B(Star), R(19),
                 B(LdaTheHole),
                 B(SetPendingMessage),
@@ -568,7 +531,7 @@ bytecodes: [
                 B(LdaZero),
                 B(TestEqualStrict), R(6), U8(14),
                 B(JumpIfTrue), U8(104),
-                B(LdaNamedProperty), R(4), U8(20), U8(15),
+                B(LdaNamedProperty), R(4), U8(18), U8(15),
                 B(Star), R(8),
                 B(TestUndetectable),
                 B(JumpIfFalse), U8(4),
@@ -582,7 +545,7 @@ bytecodes: [
                 B(Jump), U8(18),
                 B(Wide), B(LdaSmi), I16(134),
                 B(Star), R(19),
-                B(LdaConstant), U8(21),
+                B(LdaConstant), U8(19),
                 B(Star), R(20),
                 B(CallRuntime), U16(Runtime::kNewTypeError), R(19), U8(2),
                 B(Throw),
@@ -593,7 +556,7 @@ bytecodes: [
                 B(Jump), U8(20),
                 B(Star), R(20),
                 B(Ldar), R(closure),
-                B(CreateCatchContext), R(20), U8(18), U8(22),
+                B(CreateCatchContext), R(20), U8(16), U8(20),
                 B(Star), R(19),
                 B(LdaTheHole),
                 B(SetPendingMessage),
@@ -612,7 +575,7 @@ bytecodes: [
                 B(Ldar), R(18),
                 B(SetPendingMessage),
                 B(Ldar), R(16),
-                B(SwitchOnSmiNoFeedback), U8(23), U8(2), I8(0),
+                B(SwitchOnSmiNoFeedback), U8(21), U8(2), I8(0),
                 B(Jump), U8(13),
                 B(LdaZero),
                 B(Star), R(12),
@@ -624,7 +587,7 @@ bytecodes: [
                 B(Star), R(17),
                 B(Mov), R(10), R(16),
                 B(CallJSRuntime), U8(%async_generator_await_uncaught), R(16), U8(2),
-                B(SuspendGenerator), R(10), R(0), U8(16), U8(5),
+                B(SuspendGenerator), R(10), R(0), U8(16), U8(4),
   /*   50 S> */ B(Return),
                 B(RestoreGeneratorRegisters), R(10), R(0), U8(16),
                 B(LdaSmi), I8(-2),
@@ -645,7 +608,7 @@ bytecodes: [
                 B(Jump), U8(39),
                 B(Star), R(16),
                 B(Ldar), R(closure),
-                B(CreateCatchContext), R(16), U8(18), U8(25),
+                B(CreateCatchContext), R(16), U8(16), U8(23),
                 B(Star), R(15),
                 B(LdaTheHole),
                 B(SetPendingMessage),
@@ -673,7 +636,7 @@ bytecodes: [
                 B(Ldar), R(14),
                 B(SetPendingMessage),
                 B(Ldar), R(12),
-                B(SwitchOnSmiNoFeedback), U8(27), U8(3), I8(0),
+                B(SwitchOnSmiNoFeedback), U8(25), U8(3), I8(0),
                 B(Jump), U8(34),
                 B(LdaTrue),
                 B(Star), R(17),
@@ -700,15 +663,13 @@ constant pool: [
   Smi [87],
   Smi [160],
   Smi [160],
-  Smi [160],
-  Smi [577],
+  Smi [532],
   Smi [59],
   Smi [7],
   TUPLE2_TYPE,
   SYMBOL_TYPE,
-  Smi [130],
-  Smi [171],
-  Smi [82],
+  Smi [85],
+  Smi [126],
   ONE_BYTE_INTERNALIZED_STRING_TYPE ["next"],
   ONE_BYTE_INTERNALIZED_STRING_TYPE ["done"],
   ONE_BYTE_INTERNALIZED_STRING_TYPE ["value"],
@@ -722,17 +683,17 @@ constant pool: [
   Smi [6],
   Smi [14],
   FIXED_ARRAY_TYPE,
-  Smi [543],
+  Smi [498],
   Smi [6],
   Smi [28],
   Smi [35],
 ]
 handlers: [
-  [52, 669, 675],
-  [55, 630, 632],
-  [149, 432, 438],
-  [152, 392, 394],
-  [499, 509, 511],
+  [52, 624, 630],
+  [55, 585, 587],
+  [149, 387, 393],
+  [152, 347, 349],
+  [454, 464, 466],
 ]
 
 ---
@@ -1061,7 +1022,7 @@ bytecodes: [
                 B(Star), R(17),
                 B(Mov), R(9), R(15),
                 B(Mov), R(3), R(16),
-                B(InvokeIntrinsic), U8(Runtime::k_AsyncGeneratorResolve), R(15), U8(3),
+                B(InvokeIntrinsic), U8(Runtime::k_AsyncGeneratorYield), R(15), U8(3),
                 B(SuspendGenerator), R(9), R(0), U8(15), U8(9),
   /*   60 S> */ B(Return),
                 B(RestoreGeneratorRegisters), R(9), R(0), U8(15),