[async-await] Remove await optimization flag

This CL removes the await-optimization-flag, that is no longer needed,
since the feature is considered web compatible.

Bug: v8:8267, chromium:893469
Change-Id: I046f003f9ed6853d713b825c436fe5f0a1e5a0a9
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1630677Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Commit-Queue: Maya Lekova <mslekova@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61834}

src/builtins/builtins-async-gen.cc

@@ -190,15 +190,7 @@ Node* AsyncBuiltinsAssembler::Await(Node* context, Node* generator, Node* value,
   Label if_old(this), if_new(this), done(this),
       if_slow_constructor(this, Label::kDeferred);
 
-  STATIC_ASSERT(sizeof(FLAG_harmony_await_optimization) == 1);
-  TNode<Word32T> flag_value = UncheckedCast<Word32T>(Load(
-      MachineType::Uint8(),
-      ExternalConstant(
-          ExternalReference::address_of_harmony_await_optimization_flag())));
-  GotoIf(Word32Equal(flag_value, Int32Constant(0)), &if_old);
-
-  // We're running with --harmony-await-optimization enabled, which means
-  // we do the `PromiseResolve(%Promise%,value)` avoiding to unnecessarily
+  // We do the `PromiseResolve(%Promise%,value)` avoiding to unnecessarily
   // create wrapper promises. Now if {value} is already a promise with the
   // intrinsics %Promise% constructor as its "constructor", we don't need
   // to allocate the wrapper promise and can just use the `AwaitOptimized`

src/codegen/external-reference.cc

@@ -412,11 +412,6 @@ ExternalReference ExternalReference::address_of_pending_message_obj(
 
 FUNCTION_REFERENCE(abort_with_reason, i::abort_with_reason)
 
-ExternalReference
-ExternalReference::address_of_harmony_await_optimization_flag() {
-  return ExternalReference(&FLAG_harmony_await_optimization);
-}
-
 ExternalReference ExternalReference::address_of_min_int() {
   return ExternalReference(reinterpret_cast<Address>(&double_min_int_constant));
 }

src/codegen/external-reference.h

@@ -89,8 +89,6 @@ class StatsCounter;
   V(address_of_double_neg_constant, "double_negate_constant")                 \
   V(address_of_float_abs_constant, "float_absolute_constant")                 \
   V(address_of_float_neg_constant, "float_negate_constant")                   \
-  V(address_of_harmony_await_optimization_flag,                               \
-    "FLAG_harmony_await_optimization")                                        \
   V(address_of_min_int, "LDoubleConstant::min_int")                           \
   V(address_of_mock_arraybuffer_allocator_flag,                               \
     "FLAG_mock_arraybuffer_allocator")                                        \

src/flags/flag-definitions.h

@@ -238,7 +238,6 @@ DEFINE_IMPLICATION(harmony_import_meta, harmony_dynamic_import)
   V(harmony_dynamic_import, "harmony dynamic import")                      \
   V(harmony_global, "harmony global")                                      \
   V(harmony_object_from_entries, "harmony Object.fromEntries()")           \
-  V(harmony_await_optimization, "harmony await taking 1 tick")             \
   V(harmony_hashbang, "harmony hashbang syntax")                           \
   V(harmony_numeric_separator, "harmony numeric separator between digits") \
   V(harmony_promise_all_settled, "harmony Promise.allSettled")
@@ -1127,7 +1126,6 @@ DEFINE_BOOL(trace_sim_messages, false,
 // isolate.cc
 DEFINE_BOOL(async_stack_traces, true,
             "include async stack traces in Error.stack")
-DEFINE_IMPLICATION(async_stack_traces, harmony_await_optimization)
 DEFINE_BOOL(stack_trace_on_illegal, false,
             "print stack trace when an illegal exception is thrown")
 DEFINE_BOOL(abort_on_uncaught_exception, false,

src/init/bootstrapper.cc

@@ -4232,7 +4232,6 @@ EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_dynamic_import)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_import_meta)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_numeric_separator)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_regexp_sequence)
-EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_await_optimization)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_hashbang)
 
 #ifdef V8_INTL_SUPPORT