Revert "[vm] Cleanup old async/async*/sync* implementation from the VM"

This reverts commit bc8afad.

Reason for revert: b/238653741

Original change's description:
> [vm] Cleanup old async/async*/sync* implementation from the VM
>
> TEST=ci
>
> Issue: #48378
> Change-Id: I089ba4ed5613f30eec29f0db4ac6d5d8fbffd185
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/249980
> Reviewed-by: Martin Kustermann <kustermann@google.com>
> Reviewed-by: Slava Egorov <vegorov@google.com>
> Commit-Queue: Alexander Markov <alexmarkov@google.com>

TBR=vegorov@google.com,kustermann@google.com,alexmarkov@google.com

Change-Id: I6437d2d7d3914eb7fb9fe397472e2a5f7ae0cd9e
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Issue: #48378
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/251147
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Alexander Markov <alexmarkov@google.com>
Reviewed-by: Alexander Markov <alexmarkov@google.com>

runtime/tests/vm/dart/regress_flutter51298_test.dart

@@ -2,7 +2,7 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// VMOptions=--optimization_counter_threshold=10 --deterministic
+// VMOptions=--async_igoto_threshold=0 --optimization_counter_threshold=10 --deterministic
 
 // Regression test for https://github.com/flutter/flutter/issues/51298.
 // This would cause a crash due to bad offsets causing entry to hit the pre-code

runtime/tests/vm/dart_2/regress_flutter51298_test.dart

@@ -4,7 +4,7 @@
 
 // @dart = 2.9
 
-// VMOptions=--optimization_counter_threshold=10 --deterministic
+// VMOptions=--async_igoto_threshold=0 --optimization_counter_threshold=10 --deterministic
 
 // Regression test for https://github.com/flutter/flutter/issues/51298.
 // This would cause a crash due to bad offsets causing entry to hit the pre-code

runtime/vm/code_descriptors.h

@@ -78,8 +78,8 @@ class ExceptionHandlerList : public ZoneAllocated {
 
   explicit ExceptionHandlerList(const Function& function)
       : list_(),
-        has_async_handler_(function.IsAsyncFunction() ||
-                           function.IsAsyncGenerator()) {}
+        has_async_handler_(function.IsCompactAsyncFunction() ||
+                           function.IsCompactAsyncStarFunction()) {}
 
   intptr_t Length() const { return list_.length(); }
 

runtime/vm/compiler/aot/precompiler.cc

@@ -629,6 +629,8 @@ void Precompiler::DoCompileAll() {
         IG->object_store()->set_simple_instance_of_true_function(null_function);
         IG->object_store()->set_simple_instance_of_false_function(
             null_function);
+        IG->object_store()->set_async_star_move_next_helper(null_function);
+        IG->object_store()->set_complete_on_async_return(null_function);
         IG->object_store()->set_async_star_stream_controller(null_class);
         DropMetadata();
         DropLibraryEntries();
@@ -1134,6 +1136,14 @@ void Precompiler::AddTypesOf(const Function& function) {
     return;
   }
 
+  // Preserve parents for generated bodies in async/async*/sync* functions,
+  // since predicates like Function::IsAsyncClosure(), etc. need that info.
+  if (function.is_generated_body()) {
+    AddRetainReason(parent_function, RetainReasons::kIsSyncAsyncFunction);
+    AddTypesOf(parent_function);
+    return;
+  }
+
   // We're not retaining the parent due to this function, so wrap it with
   // a weak serialization reference.
   const auto& data = ClosureData::CheckedHandle(Z, function.data());
@@ -2973,6 +2983,10 @@ void Precompiler::DiscardCodeObjects() {
           ++codes_with_native_function_;
           return;
         }
+        if (function_.IsAsyncClosure() || function_.IsAsyncGenClosure()) {
+          ++codes_with_async_closure_function_;
+          return;
+        }
 
         // Retain Code objects corresponding to dynamically
         // called functions.
@@ -3026,6 +3040,8 @@ void Precompiler::DiscardCodeObjects() {
                 codes_with_pc_descriptors_);
       THR_Print("    %8" Pd " Codes with native functions\n",
                 codes_with_native_function_);
+      THR_Print("    %8" Pd " Codes with async closure functions\n",
+                codes_with_async_closure_function_);
       THR_Print("    %8" Pd " Codes with dynamically called functions\n",
                 codes_with_dynamically_called_function_);
       THR_Print("    %8" Pd " Codes with deferred functions\n",
@@ -3057,6 +3073,7 @@ void Precompiler::DiscardCodeObjects() {
     intptr_t codes_with_exception_handlers_ = 0;
     intptr_t codes_with_pc_descriptors_ = 0;
     intptr_t codes_with_native_function_ = 0;
+    intptr_t codes_with_async_closure_function_ = 0;
     intptr_t codes_with_dynamically_called_function_ = 0;
     intptr_t codes_with_deferred_function_ = 0;
     intptr_t codes_with_ffi_trampoline_function_ = 0;

runtime/vm/compiler/backend/il.cc

@@ -6836,7 +6836,7 @@ void RawStoreFieldInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
 const Code& ReturnInstr::GetReturnStub(FlowGraphCompiler* compiler) const {
   const Function& function = compiler->parsed_function().function();
   ASSERT(function.IsSuspendableFunction());
-  if (function.IsAsyncFunction()) {
+  if (function.IsCompactAsyncFunction()) {
     if (!value()->Type()->CanBeFuture()) {
       return Code::ZoneHandle(compiler->zone(),
                               compiler->isolate_group()
@@ -6846,11 +6846,11 @@ const Code& ReturnInstr::GetReturnStub(FlowGraphCompiler* compiler) const {
     return Code::ZoneHandle(
         compiler->zone(),
         compiler->isolate_group()->object_store()->return_async_stub());
-  } else if (function.IsAsyncGenerator()) {
+  } else if (function.IsCompactAsyncStarFunction()) {
     return Code::ZoneHandle(
         compiler->zone(),
         compiler->isolate_group()->object_store()->return_async_star_stub());
-  } else if (function.IsSyncGenerator()) {
+  } else if (function.IsCompactSyncStarFunction()) {
     return Code::ZoneHandle(
         compiler->zone(),
         compiler->isolate_group()->object_store()->return_sync_star_stub());