[kernel] Remove obsolete AsyncMarker.SyncYielding and YieldStatement.…

…isNative

AsyncMarker.SyncYielding and YieldStatement.isNative became
obsolete after async/async*/sync* kernel transformation was removed in
https://dart-review.googlesource.com/c/sdk/+/249944.

TEST=ci

Issue: #48378
Change-Id: I69ac994af77f7e403686750bf8df437868bf33fa
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/249947
Commit-Queue: Alexander Markov <alexmarkov@google.com>
Reviewed-by: Sigmund Cherem <sigmund@google.com>
Reviewed-by: Slava Egorov <vegorov@google.com>

pkg/compiler/lib/src/inferrer/builder.dart

@@ -434,10 +434,6 @@ class KernelTypeGraphBuilder extends ir.Visitor<TypeInformation>
       case ir.AsyncMarker.AsyncStar:
         recordReturnType(_types.asyncStarStreamType);
         break;
-      case ir.AsyncMarker.SyncYielding:
-        failedAt(
-            _analyzedMember, "Unexpected async marker: ${node.asyncMarker}");
-        break;
     }
     assert(_breaksFor.isEmpty);
     assert(_continuesFor.isEmpty);

pkg/compiler/lib/src/ir/impact_data.dart

@@ -192,10 +192,6 @@ class ImpactBuilder extends StaticTypeVisitor implements ImpactRegistry {
         }
         registerAsyncStar(elementType);
         break;
-
-      case ir.AsyncMarker.SyncYielding:
-        failedAt(CURRENT_ELEMENT_SPANNABLE,
-            "Unexpected async marker: ${asyncMarker}");
     }
   }
 

pkg/compiler/lib/src/ir/util.dart

@@ -58,7 +58,6 @@ AsyncMarker getAsyncMarker(ir.FunctionNode node) {
       return AsyncMarker.SYNC;
     case ir.AsyncMarker.SyncStar:
       return AsyncMarker.SYNC_STAR;
-    case ir.AsyncMarker.SyncYielding:
     default:
       throw UnsupportedError(
           "Async marker ${node.asyncMarker} is not supported.");

pkg/front_end/lib/src/fasta/kernel/body_builder.dart

@@ -76,8 +76,7 @@ import '../messages.dart' as messages show getLocationFromUri;
 import '../modifier.dart'
     show Modifier, constMask, covariantMask, finalMask, lateMask, requiredMask;
 import '../names.dart' show emptyName, minusName, plusName;
-import '../problems.dart'
-    show internalProblem, unexpected, unhandled, unsupported;
+import '../problems.dart' show internalProblem, unhandled, unsupported;
 import '../scope.dart';
 import '../source/diet_parser.dart';
 import '../source/source_class_builder.dart';
@@ -1415,9 +1414,6 @@ class BodyBuilder extends StackListenerImpl
 
       case AsyncMarker.Sync:
         break; // skip
-      case AsyncMarker.SyncYielding:
-        unexpected("async, async*, sync, or sync*", "$asyncModifier",
-            member.charOffset, uri);
     }
 
     if (problem != null) {

pkg/kernel/binary.md

@@ -147,7 +147,7 @@ type CanonicalName {
 
 type ComponentFile {
   UInt32 magic = 0x90ABCDEF;
-  UInt32 formatVersion = 82;
+  UInt32 formatVersion = 83;
   Byte[10] shortSdkHash;
   List<String> problemsAsJson; // Described in problems.md.
   Library[] libraries;
@@ -510,8 +510,7 @@ enum AsyncMarker {
   Sync,
   SyncStar,
   Async,
-  AsyncStar,
-  SyncYielding
+  AsyncStar
 }
 */
 
@@ -1398,7 +1397,7 @@ type TryFinally extends Statement {
 type YieldStatement extends Statement {
   Byte tag = 77;
   FileOffset fileOffset;
-  Byte flags (isYieldStar, isNative);
+  Byte flags (isYieldStar);
   Expression expression;
 }
 

pkg/kernel/lib/ast.dart

@@ -3956,43 +3956,6 @@ enum AsyncMarker {
   SyncStar,
   Async,
   AsyncStar,
-
-  // `SyncYielding` is a marker that tells Dart VM that this function is an
-  // artificial closure introduced by an async transformer which desugared all
-  // async syntax into a combination of native yields and helper method calls.
-  //
-  // Native yields (formatted as `[yield]`) are semantically close to
-  // `yield x` statement: they denote a yield/resume point within a function
-  // but are completely decoupled from the notion of iterators. When
-  // execution of the closure reaches `[yield] x` it stops and return the
-  // value of `x` to the caller. If closure is called again it continues
-  // to the next statement after this yield as if it was suspended and resumed.
-  //
-  // Consider this example:
-  //
-  //   g() {
-  //     var :await_jump_var = 0;
-  //     var :await_ctx_var;
-  //
-  //     f(x) yielding {
-  //       [yield] '${x}:0';
-  //       [yield] '${x}:1';
-  //       [yield] '${x}:2';
-  //     }
-  //
-  //     return f;
-  //   }
-  //
-  //   print(f('a'));  /* prints 'a:0', :await_jump_var = 1  */
-  //   print(f('b'));  /* prints 'b:1', :await_jump_var = 2  */
-  //   print(f('c'));  /* prints 'c:2', :await_jump_var = 3  */
-  //
-  // Note: currently Dart VM implicitly relies on async transformer to
-  // inject certain artificial variables into g (like `:await_jump_var`).
-  // As such SyncYielding and native yield are not intended to be used on their
-  // own, but are rather an implementation artifact of the async transformer
-  // itself.
-  SyncYielding,
 }
 
 // ------------------------------------------------------------------------
@@ -10523,33 +10486,23 @@ class TryFinally extends Statement {
 }
 
 /// Statement of form `yield x` or `yield* x`.
-///
-/// For native yield semantics see `AsyncMarker.SyncYielding`.
 class YieldStatement extends Statement {
   Expression expression;
   int flags = 0;
 
-  YieldStatement(this.expression,
-      {bool isYieldStar: false, bool isNative: false}) {
+  YieldStatement(this.expression, {bool isYieldStar: false}) {
     expression.parent = this;
     this.isYieldStar = isYieldStar;
-    this.isNative = isNative;
   }
 
   static const int FlagYieldStar = 1 << 0;
-  static const int FlagNative = 1 << 1;
 
   bool get isYieldStar => flags & FlagYieldStar != 0;
-  bool get isNative => flags & FlagNative != 0;
 
   void set isYieldStar(bool value) {
     flags = value ? (flags | FlagYieldStar) : (flags & ~FlagYieldStar);
   }
 
-  void set isNative(bool value) {
-    flags = value ? (flags | FlagNative) : (flags & ~FlagNative);
-  }
-
   @override
   R accept<R>(StatementVisitor<R> v) => v.visitYieldStatement(this);
 

pkg/kernel/lib/binary/ast_from_binary.dart

@@ -2895,8 +2895,7 @@ class BinaryBuilder {
     int offset = readOffset();
     int flags = readByte();
     return new YieldStatement(readExpression(),
-        isYieldStar: flags & YieldStatement.FlagYieldStar != 0,
-        isNative: flags & YieldStatement.FlagNative != 0)
+        isYieldStar: flags & YieldStatement.FlagYieldStar != 0)
       ..fileOffset = offset;
   }
 

pkg/kernel/lib/binary/tag.dart

@@ -179,7 +179,7 @@ class Tag {
   /// Internal version of kernel binary format.
   /// Bump it when making incompatible changes in kernel binaries.
   /// Keep in sync with runtime/vm/kernel_binary.h, pkg/kernel/binary.md.
-  static const int BinaryFormatVersion = 82;
+  static const int BinaryFormatVersion = 83;
 }
 
 abstract class ConstantTag {

pkg/kernel/lib/text/ast_to_text.dart

@@ -818,8 +818,6 @@ class Printer extends Visitor<void> with VisitorVoidMixin {
         return 'async';
       case AsyncMarker.AsyncStar:
         return 'async*';
-      case AsyncMarker.SyncYielding:
-        return 'yielding';
       default:
         return '<Invalid async marker: $marker>';
     }
@@ -2414,8 +2412,6 @@ class Printer extends Visitor<void> with VisitorVoidMixin {
     writeIndentation();
     if (node.isYieldStar) {
       writeWord('yield*');
-    } else if (node.isNative) {
-      writeWord('[yield]');
     } else {
       writeWord('yield');
     }

pkg/kernel/lib/type_checker.dart

@@ -363,26 +363,6 @@ class TypeCheckingVisitor
       case AsyncMarker.AsyncStar:
         return null;
 
-      case AsyncMarker.SyncYielding:
-        // The SyncStar transform wraps the original function body twice,
-        // where the inner most function returns bool.
-        TreeNode? parent = function.parent;
-        while (parent is! FunctionNode) {
-          parent = parent!.parent;
-        }
-        FunctionNode enclosingFunction = parent;
-        if (enclosingFunction.dartAsyncMarker == AsyncMarker.Sync) {
-          parent = enclosingFunction.parent;
-          while (parent is! FunctionNode) {
-            parent = parent!.parent;
-          }
-          enclosingFunction = parent;
-          if (enclosingFunction.dartAsyncMarker == AsyncMarker.SyncStar) {
-            return coreTypes.boolLegacyRawType;
-          }
-        }
-        return null;
-
       default:
         throw 'Unexpected async marker: ${function.asyncMarker}';
     }
@@ -405,9 +385,6 @@ class TypeCheckingVisitor
         }
         return const DynamicType();
 
-      case AsyncMarker.SyncYielding:
-        return function.returnType;
-
       default:
         throw 'Unexpected async marker: ${function.asyncMarker}';
     }

pkg/kernel/lib/verifier.dart

@@ -528,7 +528,6 @@ class VerifyingVisitor extends RecursiveResultVisitor<void> {
     switch (currentAsyncMarker) {
       case AsyncMarker.Sync:
       case AsyncMarker.Async:
-      case AsyncMarker.SyncYielding:
         // ok
         break;
       case AsyncMarker.SyncStar:
@@ -556,7 +555,6 @@ class VerifyingVisitor extends RecursiveResultVisitor<void> {
         break;
       case AsyncMarker.SyncStar:
       case AsyncMarker.AsyncStar:
-      case AsyncMarker.SyncYielding:
         // ok
         break;
     }

pkg/vm/lib/transformations/type_flow/summary_collector.dart

@@ -363,17 +363,6 @@ class _VariablesInfoCollector extends RecursiveVisitor {
     final function = node.function;
     function.accept(this);
 
-    if (function.asyncMarker == AsyncMarker.SyncYielding) {
-      // Mark parameters of synthetic async_op closures as captured
-      // to make sure their updates at yield points are taken into account.
-      for (var v in function.positionalParameters) {
-        _captureVariable(v);
-      }
-      for (var v in function.namedParameters) {
-        _captureVariable(v);
-      }
-    }
-
     activeStatements = savedActiveStatements;
     numVariablesAtActiveStatements = savedNumVariablesAtActiveStatements;
     numVariablesAtFunctionEntry = savedNumVariablesAtFunctionEntry;