mcs/mcs/codegen.cs

   1 //
   2 // codegen.cs: The code generator
   3 //
   4 // Authors:
   5 //   Miguel de Icaza (miguel@ximian.com)
   6 //   Marek Safar (marek.safar@gmail.com)
   7 //
   8 // Copyright 2001, 2002, 2003 Ximian, Inc.
   9 // Copyright 2004 Novell, Inc.
  10 // Copyright 2011 Xamarin Inc
  11 //
  12
  13 using System;
  14 using System.Collections.Generic;
  15 using Mono.CompilerServices.SymbolWriter;
  16
  17 #if STATIC
  18 using MetaType = IKVM.Reflection.Type;
  19 using IKVM.Reflection;
  20 using IKVM.Reflection.Emit;
  21 #else
  22 using MetaType = System.Type;
  23 using System.Reflection;
  24 using System.Reflection.Emit;
  25 #endif
  26
  27 namespace Mono.CSharp
  28 {
  29         /// <summary>
  30         ///   An Emit Context is created for each body of code (from methods,
  31         ///   properties bodies, indexer bodies or constructor bodies)
  32         /// </summary>
  33         public class EmitContext : BuilderContext
  34         {
  35                 // TODO: Has to be private
  36                 public readonly ILGenerator ig;
  37
  38                 /// <summary>
  39                 ///   The value that is allowed to be returned or NULL if there is no
  40                 ///   return type.
  41                 /// </summary>
  42                 readonly TypeSpec return_type;
  43
  44                 /// <summary>
  45                 ///   Keeps track of the Type to LocalBuilder temporary storage created
  46                 ///   to store structures (used to compute the address of the structure
  47                 ///   value on structure method invocations)
  48                 /// </summary>
  49                 Dictionary<TypeSpec, object> temporary_storage;
  50
  51                 /// <summary>
  52                 ///   The location where we store the return value.
  53                 /// </summary>
  54                 public LocalBuilder return_value;
  55
  56
  57                 /// <summary>
  58                 ///   Current loop begin and end labels.
  59                 /// </summary>
  60                 public Label LoopBegin, LoopEnd;
  61
  62                 /// <summary>
  63                 ///   Default target in a switch statement.   Only valid if
  64                 ///   InSwitch is true
  65                 /// </summary>
  66                 public Label DefaultTarget;
  67
  68                 /// <summary>
  69                 ///   If this is non-null, points to the current switch statement
  70                 /// </summary>
  71                 public Switch Switch;
  72
  73                 /// <summary>
  74                 ///  Whether we are inside an anonymous method.
  75                 /// </summary>
  76                 public AnonymousExpression CurrentAnonymousMethod;
  77
  78                 readonly IMemberContext member_context;
  79
  80                 readonly SourceMethodBuilder methodSymbols;
  81
  82                 DynamicSiteClass dynamic_site_container;
  83
  84                 Label? return_label;
  85
  86                 List<IExpressionCleanup> epilogue_expressions;
  87
  88                 public EmitContext (IMemberContext rc, ILGenerator ig, TypeSpec return_type, SourceMethodBuilder methodSymbols)
  89                 {
  90                         this.member_context = rc;
  91                         this.ig = ig;
  92                         this.return_type = return_type;
  93
  94                         if (rc.Module.Compiler.Settings.Checked)
  95                                 flags |= Options.CheckedScope;
  96
  97                         if (methodSymbols != null) {
  98                                 this.methodSymbols = methodSymbols;
  99                                 if (!rc.Module.Compiler.Settings.Optimize)
 100                                         flags |= Options.AccurateDebugInfo;
 101                         } else {
 102                                 flags |= Options.OmitDebugInfo;
 103                         }
 104
 105 #if STATIC
 106                         ig.__CleverExceptionBlockAssistance ();
 107 #endif
 108                 }
 109
 110                 #region Properties
 111
 112                 internal AsyncTaskStorey AsyncTaskStorey {
 113                         get {
 114                                 return CurrentAnonymousMethod.Storey as AsyncTaskStorey;
 115                         }
 116                 }
 117
 118                 public BuiltinTypes BuiltinTypes {
 119                         get {
 120                                 return MemberContext.Module.Compiler.BuiltinTypes;
 121                         }
 122                 }
 123
 124                 public ConditionalAccessContext ConditionalAccess { get; set; }
 125
 126                 public TypeSpec CurrentType {
 127                         get { return member_context.CurrentType; }
 128                 }
 129
 130                 public TypeParameters CurrentTypeParameters {
 131                     get { return member_context.CurrentTypeParameters; }
 132                 }
 133
 134                 public MemberCore CurrentTypeDefinition {
 135                         get { return member_context.CurrentMemberDefinition; }
 136                 }
 137
 138                 public bool EmitAccurateDebugInfo {
 139                         get {
 140                                 return (flags & Options.AccurateDebugInfo) != 0;
 141                         }
 142                 }
 143
 144                 public bool HasMethodSymbolBuilder {
 145                         get {
 146                                 return methodSymbols != null;
 147                         }
 148                 }
 149
 150                 public bool HasReturnLabel {
 151                         get {
 152                                 return return_label.HasValue;
 153                         }
 154                 }
 155
 156                 public bool IsStatic {
 157                         get { return member_context.IsStatic; }
 158                 }
 159
 160                 public bool IsStaticConstructor {
 161                         get {
 162                                 return member_context.IsStatic && (flags & Options.ConstructorScope) != 0;
 163                         }
 164                 }
 165
 166                 public bool IsAnonymousStoreyMutateRequired {
 167                         get {
 168                                 return CurrentAnonymousMethod != null &&
 169                                         CurrentAnonymousMethod.Storey != null &&
 170                                         CurrentAnonymousMethod.Storey.Mutator != null;
 171                         }
 172                 }
 173
 174                 public IMemberContext MemberContext {
 175                         get {
 176                                 return member_context;
 177                         }
 178                 }
 179
 180                 public ModuleContainer Module {
 181                         get {
 182                                 return member_context.Module;
 183                         }
 184                 }
 185
 186                 public bool NotifyEvaluatorOnStore {
 187                         get {
 188                                 return Module.Evaluator != null && Module.Evaluator.ModificationListener != null;
 189                         }
 190                 }
 191
 192                 // Has to be used for specific emitter errors only any
 193                 // possible resolver errors have to be reported during Resolve
 194                 public Report Report {
 195                         get {
 196                                 return member_context.Module.Compiler.Report;
 197                         }
 198                 }
 199
 200                 public TypeSpec ReturnType {
 201                         get {
 202                                 return return_type;
 203                         }
 204                 }
 205
 206                 //
 207                 // The label where we have to jump before leaving the context
 208                 //
 209                 public Label ReturnLabel {
 210                         get {
 211                                 return return_label.Value;
 212                         }
 213                 }
 214
 215                 public List<IExpressionCleanup> StatementEpilogue {
 216                         get {
 217                                 return epilogue_expressions;
 218                         }
 219                 }
 220
 221                 public LocalVariable AsyncThrowVariable { get; set; }
 222
 223                 public List<TryFinally> TryFinallyUnwind { get; set; }
 224
 225                 public Label RecursivePatternLabel { get; set; }
 226
 227                 #endregion
 228
 229                 public void AddStatementEpilog (IExpressionCleanup cleanupExpression)
 230                 {
 231                         if (epilogue_expressions == null) {
 232                                 epilogue_expressions = new List<IExpressionCleanup> ();
 233                         } else if (epilogue_expressions.Contains (cleanupExpression)) {
 234                                 return;
 235                         }
 236
 237                         epilogue_expressions.Add (cleanupExpression);
 238                 }
 239
 240                 public void AssertEmptyStack ()
 241                 {
 242 #if STATIC
 243                         if (ig.__StackHeight != 0)
 244                                 throw new InternalErrorException ("Await yields with non-empty stack in `{0}",
 245                                         member_context.GetSignatureForError ());
 246 #endif
 247                 }
 248
 249                 /// <summary>
 250                 ///   This is called immediately before emitting an IL opcode to tell the symbol
 251                 ///   writer to which source line this opcode belongs.
 252                 /// </summary>
 253                 public bool Mark (Location loc)
 254                 {
 255                         if ((flags & Options.OmitDebugInfo) != 0)
 256                                 return false;
 257
 258                         if (loc.IsNull || methodSymbols == null)
 259                                 return false;
 260
 261                         var sf = loc.SourceFile;
 262                         if (sf.IsHiddenLocation (loc))
 263                                 return false;
 264
 265 #if NET_4_0
 266                         methodSymbols.MarkSequencePoint (ig.ILOffset, sf.SourceFileEntry, loc.Row, loc.Column, false);
 267 #endif
 268                         return true;
 269                 }
 270
 271                 public void MarkCallEntry (Location loc)
 272                 {
 273                         if (!EmitAccurateDebugInfo)
 274                                 return;
 275
 276                         //
 277                         // TODO: This should emit different kind of sequence point to make
 278                         // step-over work for statement over multiple lines
 279                         //
 280                         // Debugging experience for Foo (A () + B ()) where A and B are
 281                         // on separate lines is not great
 282                         //
 283                         Mark (loc);
 284                 }
 285
 286                 public void DefineLocalVariable (string name, LocalBuilder builder)
 287                 {
 288                         if ((flags & Options.OmitDebugInfo) != 0)
 289                                 return;
 290
 291                         methodSymbols.AddLocal (builder.LocalIndex, name);
 292                 }
 293
 294                 public void BeginCatchBlock (TypeSpec type)
 295                 {
 296                         if (IsAnonymousStoreyMutateRequired)
 297                                 type = CurrentAnonymousMethod.Storey.Mutator.Mutate (type);
 298
 299                         ig.BeginCatchBlock (type.GetMetaInfo ());
 300                 }
 301
 302                 public void BeginFilterHandler ()
 303                 {
 304                         ig.BeginCatchBlock (null);
 305                 }
 306
 307                 public void BeginExceptionBlock ()
 308                 {
 309                         ig.BeginExceptionBlock ();
 310                 }
 311
 312                 public void BeginExceptionFilterBlock ()
 313                 {
 314                         ig.BeginExceptFilterBlock ();
 315                 }
 316
 317                 public void BeginFinallyBlock ()
 318                 {
 319                         ig.BeginFinallyBlock ();
 320                 }
 321
 322                 public void BeginScope ()
 323                 {
 324                         if ((flags & Options.OmitDebugInfo) != 0)
 325                                 return;
 326
 327 #if NET_4_0
 328                         methodSymbols.StartBlock (CodeBlockEntry.Type.Lexical, ig.ILOffset);
 329 #endif
 330                 }
 331
 332                 public void BeginCompilerScope ()
 333                 {
 334                         if ((flags & Options.OmitDebugInfo) != 0)
 335                                 return;
 336
 337 #if NET_4_0
 338                         methodSymbols.StartBlock (CodeBlockEntry.Type.CompilerGenerated, ig.ILOffset);
 339 #endif
 340                 }
 341
 342                 public void EndExceptionBlock ()
 343                 {
 344                         ig.EndExceptionBlock ();
 345                 }
 346
 347                 public void EndScope ()
 348                 {
 349                         if ((flags & Options.OmitDebugInfo) != 0)
 350                                 return;
 351
 352 #if NET_4_0
 353                         methodSymbols.EndBlock (ig.ILOffset);
 354 #endif
 355                 }
 356
 357                 public void CloseConditionalAccess (TypeSpec type)
 358                 {
 359                         if (type != null)
 360                                 Emit (OpCodes.Newobj, Nullable.NullableInfo.GetConstructor (type));
 361
 362                         MarkLabel (ConditionalAccess.EndLabel);
 363                         ConditionalAccess = null;
 364                 }
 365
 366                 //
 367                 // Creates a nested container in this context for all dynamic compiler generated stuff
 368                 //
 369                 internal DynamicSiteClass CreateDynamicSite ()
 370                 {
 371                         if (dynamic_site_container == null) {
 372                                 var mc = member_context.CurrentMemberDefinition as MemberBase;
 373                                 dynamic_site_container = new DynamicSiteClass (CurrentTypeDefinition.Parent.PartialContainer, mc, member_context.CurrentTypeParameters);
 374
 375                                 CurrentTypeDefinition.Module.AddCompilerGeneratedClass (dynamic_site_container);
 376                                 dynamic_site_container.CreateContainer ();
 377                                 dynamic_site_container.DefineContainer ();
 378                                 dynamic_site_container.Define ();
 379
 380                                 var inflator = new TypeParameterInflator (Module, CurrentType, TypeParameterSpec.EmptyTypes, TypeSpec.EmptyTypes);
 381                                 var inflated = dynamic_site_container.CurrentType.InflateMember (inflator);
 382                                 CurrentType.MemberCache.AddMember (inflated);
 383                         }
 384
 385                         return dynamic_site_container;
 386                 }
 387
 388                 public Label CreateReturnLabel ()
 389                 {
 390                         if (!return_label.HasValue)
 391                                 return_label = DefineLabel ();
 392
 393                         return return_label.Value;
 394                 }
 395
 396                 public LocalBuilder DeclareLocal (TypeSpec type, bool pinned)
 397                 {
 398                         if (IsAnonymousStoreyMutateRequired)
 399                                 type = CurrentAnonymousMethod.Storey.Mutator.Mutate (type);
 400
 401                         return ig.DeclareLocal (type.GetMetaInfo (), pinned);
 402                 }
 403
 404                 public Label DefineLabel ()
 405                 {
 406                         return ig.DefineLabel ();
 407                 }
 408
 409                 //
 410                 // Creates temporary field in current async storey
 411                 //
 412                 public StackFieldExpr GetTemporaryField (TypeSpec type, bool initializedFieldRequired = false)
 413                 {
 414                         var f = AsyncTaskStorey.AddCapturedLocalVariable (type, initializedFieldRequired);
 415                         var fexpr = new StackFieldExpr (f);
 416                         fexpr.InstanceExpression = new CompilerGeneratedThis (CurrentType, Location.Null);
 417                         return fexpr;
 418                 }
 419
 420                 public void MarkLabel (Label label)
 421                 {
 422                         ig.MarkLabel (label);
 423                 }
 424
 425                 public void Emit (OpCode opcode)
 426                 {
 427                         ig.Emit (opcode);
 428                 }
 429
 430                 public void Emit (OpCode opcode, LocalBuilder local)
 431                 {
 432                         ig.Emit (opcode, local);
 433                 }
 434
 435                 public void Emit (OpCode opcode, string arg)
 436                 {
 437                         ig.Emit (opcode, arg);
 438                 }
 439
 440                 public void Emit (OpCode opcode, double arg)
 441                 {
 442                         ig.Emit (opcode, arg);
 443                 }
 444
 445                 public void Emit (OpCode opcode, float arg)
 446                 {
 447                         ig.Emit (opcode, arg);
 448                 }
 449
 450                 public void Emit (OpCode opcode, Label label)
 451                 {
 452                         ig.Emit (opcode, label);
 453                 }
 454
 455                 public void Emit (OpCode opcode, Label[] labels)
 456                 {
 457                         ig.Emit (opcode, labels);
 458                 }
 459
 460                 public void Emit (OpCode opcode, TypeSpec type)
 461                 {
 462                         if (IsAnonymousStoreyMutateRequired)
 463                                 type = CurrentAnonymousMethod.Storey.Mutator.Mutate (type);
 464
 465                         ig.Emit (opcode, type.GetMetaInfo ());
 466                 }
 467
 468                 public void Emit (OpCode opcode, FieldSpec field)
 469                 {
 470                         if (IsAnonymousStoreyMutateRequired)
 471                                 field = field.Mutate (CurrentAnonymousMethod.Storey.Mutator);
 472
 473                         ig.Emit (opcode, field.GetMetaInfo ());
 474                 }
 475
 476                 public void Emit (OpCode opcode, MethodSpec method)
 477                 {
 478                         if (IsAnonymousStoreyMutateRequired)
 479                                 method = method.Mutate (CurrentAnonymousMethod.Storey.Mutator);
 480
 481                         if (method.IsConstructor)
 482                                 ig.Emit (opcode, (ConstructorInfo) method.GetMetaInfo ());
 483                         else
 484                                 ig.Emit (opcode, (MethodInfo) method.GetMetaInfo ());
 485                 }
 486
 487                 // TODO: REMOVE breaks mutator
 488                 public void Emit (OpCode opcode, MethodInfo method)
 489                 {
 490                         ig.Emit (opcode, method);
 491                 }
 492
 493                 public void Emit (OpCode opcode, MethodSpec method, MetaType[] vargs)
 494                 {
 495                         // TODO MemberCache: This should mutate too
 496                         ig.EmitCall (opcode, (MethodInfo) method.GetMetaInfo (), vargs);
 497                 }
 498
 499                 public void EmitArrayNew (ArrayContainer ac)
 500                 {
 501                         if (ac.Rank == 1) {
 502                                 var type = IsAnonymousStoreyMutateRequired ?
 503                                         CurrentAnonymousMethod.Storey.Mutator.Mutate (ac.Element) :
 504                                         ac.Element;
 505
 506                                 ig.Emit (OpCodes.Newarr, type.GetMetaInfo ());
 507                         } else {
 508                                 if (IsAnonymousStoreyMutateRequired)
 509                                         ac = (ArrayContainer) ac.Mutate (CurrentAnonymousMethod.Storey.Mutator);
 510
 511                                 ig.Emit (OpCodes.Newobj, ac.GetConstructor ());
 512                         }
 513                 }
 514
 515                 public void EmitArrayAddress (ArrayContainer ac)
 516                 {
 517                         if (ac.Rank > 1) {
 518                                 if (IsAnonymousStoreyMutateRequired)
 519                                         ac = (ArrayContainer) ac.Mutate (CurrentAnonymousMethod.Storey.Mutator);
 520
 521                                 ig.Emit (OpCodes.Call, ac.GetAddressMethod ());
 522                         } else {
 523                                 var type = IsAnonymousStoreyMutateRequired ?
 524                                         CurrentAnonymousMethod.Storey.Mutator.Mutate (ac.Element) :
 525                                         ac.Element;
 526
 527                                 ig.Emit (OpCodes.Ldelema, type.GetMetaInfo ());
 528                         }
 529                 }
 530
 531                 //
 532                 // Emits the right opcode to load from an array
 533                 //
 534                 public void EmitArrayLoad (ArrayContainer ac)
 535                 {
 536                         if (ac.Rank > 1) {
 537                                 if (IsAnonymousStoreyMutateRequired)
 538                                         ac = (ArrayContainer) ac.Mutate (CurrentAnonymousMethod.Storey.Mutator);
 539
 540                                 ig.Emit (OpCodes.Call, ac.GetGetMethod ());
 541                                 return;
 542                         }
 543
 544
 545                         var type = ac.Element;
 546                         if (type.Kind == MemberKind.Enum)
 547                                 type = EnumSpec.GetUnderlyingType (type);
 548
 549                         switch (type.BuiltinType) {
 550                         case BuiltinTypeSpec.Type.Bool:
 551                                 //
 552                                 // bool array can actually store any byte value in underlying byte slot
 553                                 // and C# spec does not specify any normalization rule, except the result
 554                                 // is undefined
 555                                 //
 556                         case BuiltinTypeSpec.Type.Byte:
 557                                 ig.Emit (OpCodes.Ldelem_U1);
 558                                 break;
 559                         case BuiltinTypeSpec.Type.SByte:
 560                                 ig.Emit (OpCodes.Ldelem_I1);
 561                                 break;
 562                         case BuiltinTypeSpec.Type.Short:
 563                                 ig.Emit (OpCodes.Ldelem_I2);
 564                                 break;
 565                         case BuiltinTypeSpec.Type.UShort:
 566                         case BuiltinTypeSpec.Type.Char:
 567                                 ig.Emit (OpCodes.Ldelem_U2);
 568                                 break;
 569                         case BuiltinTypeSpec.Type.Int:
 570                                 ig.Emit (OpCodes.Ldelem_I4);
 571                                 break;
 572                         case BuiltinTypeSpec.Type.UInt:
 573                                 ig.Emit (OpCodes.Ldelem_U4);
 574                                 break;
 575                         case BuiltinTypeSpec.Type.ULong:
 576                         case BuiltinTypeSpec.Type.Long:
 577                                 ig.Emit (OpCodes.Ldelem_I8);
 578                                 break;
 579                         case BuiltinTypeSpec.Type.Float:
 580                                 ig.Emit (OpCodes.Ldelem_R4);
 581                                 break;
 582                         case BuiltinTypeSpec.Type.Double:
 583                                 ig.Emit (OpCodes.Ldelem_R8);
 584                                 break;
 585                         case BuiltinTypeSpec.Type.IntPtr:
 586                                 ig.Emit (OpCodes.Ldelem_I);
 587                                 break;
 588                         default:
 589                                 switch (type.Kind) {
 590                                 case MemberKind.Struct:
 591                                         if (IsAnonymousStoreyMutateRequired)
 592                                                 type = CurrentAnonymousMethod.Storey.Mutator.Mutate (type);
 593
 594                                         ig.Emit (OpCodes.Ldelema, type.GetMetaInfo ());
 595                                         ig.Emit (OpCodes.Ldobj, type.GetMetaInfo ());
 596                                         break;
 597                                 case MemberKind.TypeParameter:
 598                                         if (IsAnonymousStoreyMutateRequired)
 599                                                 type = CurrentAnonymousMethod.Storey.Mutator.Mutate (type);
 600
 601                                         ig.Emit (OpCodes.Ldelem, type.GetMetaInfo ());
 602                                         break;
 603                                 case MemberKind.PointerType:
 604                                         ig.Emit (OpCodes.Ldelem_I);
 605                                         break;
 606                                 default:
 607                                         ig.Emit (OpCodes.Ldelem_Ref);
 608                                         break;
 609                                 }
 610                                 break;
 611                         }
 612                 }
 613
 614                 //
 615                 // Emits the right opcode to store to an array
 616                 //
 617                 public void EmitArrayStore (ArrayContainer ac)
 618                 {
 619                         if (ac.Rank > 1) {
 620                                 if (IsAnonymousStoreyMutateRequired)
 621                                         ac = (ArrayContainer) ac.Mutate (CurrentAnonymousMethod.Storey.Mutator);
 622
 623                                 ig.Emit (OpCodes.Call, ac.GetSetMethod ());
 624                                 return;
 625                         }
 626
 627                         var type = ac.Element;
 628
 629                         if (type.Kind == MemberKind.Enum)
 630                                 type = EnumSpec.GetUnderlyingType (type);
 631
 632                         switch (type.BuiltinType) {
 633                         case BuiltinTypeSpec.Type.Byte:
 634                         case BuiltinTypeSpec.Type.SByte:
 635                         case BuiltinTypeSpec.Type.Bool:
 636                                 Emit (OpCodes.Stelem_I1);
 637                                 return;
 638                         case BuiltinTypeSpec.Type.Short:
 639                         case BuiltinTypeSpec.Type.UShort:
 640                         case BuiltinTypeSpec.Type.Char:
 641                                 Emit (OpCodes.Stelem_I2);
 642                                 return;
 643                         case BuiltinTypeSpec.Type.Int:
 644                         case BuiltinTypeSpec.Type.UInt:
 645                                 Emit (OpCodes.Stelem_I4);
 646                                 return;
 647                         case BuiltinTypeSpec.Type.Long:
 648                         case BuiltinTypeSpec.Type.ULong:
 649                                 Emit (OpCodes.Stelem_I8);
 650                                 return;
 651                         case BuiltinTypeSpec.Type.Float:
 652                                 Emit (OpCodes.Stelem_R4);
 653                                 return;
 654                         case BuiltinTypeSpec.Type.Double:
 655                                 Emit (OpCodes.Stelem_R8);
 656                                 return;
 657                         }
 658
 659                         switch (type.Kind) {
 660                         case MemberKind.Struct:
 661                                 Emit (OpCodes.Stobj, type);
 662                                 break;
 663                         case MemberKind.TypeParameter:
 664                                 Emit (OpCodes.Stelem, type);
 665                                 break;
 666                         case MemberKind.PointerType:
 667                                 Emit (OpCodes.Stelem_I);
 668                                 break;
 669                         default:
 670                                 Emit (OpCodes.Stelem_Ref);
 671                                 break;
 672                         }
 673                 }
 674
 675                 public void EmitInt (int i)
 676                 {
 677                         EmitIntConstant (i);
 678                 }
 679
 680                 void EmitIntConstant (int i)
 681                 {
 682                         switch (i) {
 683                         case -1:
 684                                 ig.Emit (OpCodes.Ldc_I4_M1);
 685                                 break;
 686
 687                         case 0:
 688                                 ig.Emit (OpCodes.Ldc_I4_0);
 689                                 break;
 690
 691                         case 1:
 692                                 ig.Emit (OpCodes.Ldc_I4_1);
 693                                 break;
 694
 695                         case 2:
 696                                 ig.Emit (OpCodes.Ldc_I4_2);
 697                                 break;
 698
 699                         case 3:
 700                                 ig.Emit (OpCodes.Ldc_I4_3);
 701                                 break;
 702
 703                         case 4:
 704                                 ig.Emit (OpCodes.Ldc_I4_4);
 705                                 break;
 706
 707                         case 5:
 708                                 ig.Emit (OpCodes.Ldc_I4_5);
 709                                 break;
 710
 711                         case 6:
 712                                 ig.Emit (OpCodes.Ldc_I4_6);
 713                                 break;
 714
 715                         case 7:
 716                                 ig.Emit (OpCodes.Ldc_I4_7);
 717                                 break;
 718
 719                         case 8:
 720                                 ig.Emit (OpCodes.Ldc_I4_8);
 721                                 break;
 722
 723                         default:
 724                                 if (i >= -128 && i <= 127) {
 725                                         ig.Emit (OpCodes.Ldc_I4_S, (sbyte) i);
 726                                 } else
 727                                         ig.Emit (OpCodes.Ldc_I4, i);
 728                                 break;
 729                         }
 730                 }
 731
 732                 public void EmitLong (long l)
 733                 {
 734                         if (l >= int.MinValue && l <= int.MaxValue) {
 735                                 EmitIntConstant (unchecked ((int) l));
 736                                 ig.Emit (OpCodes.Conv_I8);
 737                         } else if (l >= 0 && l <= uint.MaxValue) {
 738                                 EmitIntConstant (unchecked ((int) l));
 739                                 ig.Emit (OpCodes.Conv_U8);
 740                         } else {
 741                                 ig.Emit (OpCodes.Ldc_I8, l);
 742                         }
 743                 }
 744
 745                 //
 746                 // Load the object from the pointer.
 747                 //
 748                 public void EmitLoadFromPtr (TypeSpec type)
 749                 {
 750                         if (type.Kind == MemberKind.Enum)
 751                                 type = EnumSpec.GetUnderlyingType (type);
 752
 753                         switch (type.BuiltinType) {
 754                         case BuiltinTypeSpec.Type.Int:
 755                                 ig.Emit (OpCodes.Ldind_I4);
 756                                 break;
 757                         case BuiltinTypeSpec.Type.UInt:
 758                                 ig.Emit (OpCodes.Ldind_U4);
 759                                 break;
 760                         case BuiltinTypeSpec.Type.Short:
 761                                 ig.Emit (OpCodes.Ldind_I2);
 762                                 break;
 763                         case BuiltinTypeSpec.Type.UShort:
 764                         case BuiltinTypeSpec.Type.Char:
 765                                 ig.Emit (OpCodes.Ldind_U2);
 766                                 break;
 767                         case BuiltinTypeSpec.Type.Byte:
 768                                 ig.Emit (OpCodes.Ldind_U1);
 769                                 break;
 770                         case BuiltinTypeSpec.Type.SByte:
 771                         case BuiltinTypeSpec.Type.Bool:
 772                                 ig.Emit (OpCodes.Ldind_I1);
 773                                 break;
 774                         case BuiltinTypeSpec.Type.ULong:
 775                         case BuiltinTypeSpec.Type.Long:
 776                                 ig.Emit (OpCodes.Ldind_I8);
 777                                 break;
 778                         case BuiltinTypeSpec.Type.Float:
 779                                 ig.Emit (OpCodes.Ldind_R4);
 780                                 break;
 781                         case BuiltinTypeSpec.Type.Double:
 782                                 ig.Emit (OpCodes.Ldind_R8);
 783                                 break;
 784                         case BuiltinTypeSpec.Type.IntPtr:
 785                                 ig.Emit (OpCodes.Ldind_I);
 786                                 break;
 787                         default:
 788                                 switch (type.Kind) {
 789                                 case MemberKind.Struct:
 790                                 case MemberKind.TypeParameter:
 791                                         if (IsAnonymousStoreyMutateRequired)
 792                                                 type = CurrentAnonymousMethod.Storey.Mutator.Mutate (type);
 793
 794                                         ig.Emit (OpCodes.Ldobj, type.GetMetaInfo ());
 795                                         break;
 796                                 case MemberKind.PointerType:
 797                                         ig.Emit (OpCodes.Ldind_I);
 798                                         break;
 799                                 default:
 800                                         ig.Emit (OpCodes.Ldind_Ref);
 801                                         break;
 802                                 }
 803                                 break;
 804                         }
 805                 }
 806
 807                 public void EmitNull ()
 808                 {
 809                         ig.Emit (OpCodes.Ldnull);
 810                 }
 811
 812                 public void EmitArgumentAddress (int pos)
 813                 {
 814                         if (!IsStatic)
 815                                 ++pos;
 816
 817                         if (pos > byte.MaxValue)
 818                                 ig.Emit (OpCodes.Ldarga, pos);
 819                         else
 820                                 ig.Emit (OpCodes.Ldarga_S, (byte) pos);
 821                 }
 822
 823                 public void EmitArgumentLoad (int pos)
 824                 {
 825                         if (!IsStatic)
 826                                 ++pos;
 827
 828                         switch (pos) {
 829                         case 0: ig.Emit (OpCodes.Ldarg_0); break;
 830                         case 1: ig.Emit (OpCodes.Ldarg_1); break;
 831                         case 2: ig.Emit (OpCodes.Ldarg_2); break;
 832                         case 3: ig.Emit (OpCodes.Ldarg_3); break;
 833                         default:
 834                                 if (pos > byte.MaxValue)
 835                                         ig.Emit (OpCodes.Ldarg, pos);
 836                                 else
 837                                         ig.Emit (OpCodes.Ldarg_S, (byte) pos);
 838                                 break;
 839                         }
 840                 }
 841
 842                 public void EmitArgumentStore (int pos)
 843                 {
 844                         if (!IsStatic)
 845                                 ++pos;
 846
 847                         if (pos > byte.MaxValue)
 848                                 ig.Emit (OpCodes.Starg, pos);
 849                         else
 850                                 ig.Emit (OpCodes.Starg_S, (byte) pos);
 851                 }
 852
 853                 //
 854                 // The stack contains the pointer and the value of type `type'
 855                 //
 856                 public void EmitStoreFromPtr (TypeSpec type)
 857                 {
 858                         if (type.IsEnum)
 859                                 type = EnumSpec.GetUnderlyingType (type);
 860
 861                         switch (type.BuiltinType) {
 862                         case BuiltinTypeSpec.Type.Int:
 863                         case BuiltinTypeSpec.Type.UInt:
 864                                 ig.Emit (OpCodes.Stind_I4);
 865                                 return;
 866                         case BuiltinTypeSpec.Type.Long:
 867                         case BuiltinTypeSpec.Type.ULong:
 868                                 ig.Emit (OpCodes.Stind_I8);
 869                                 return;
 870                         case BuiltinTypeSpec.Type.Char:
 871                         case BuiltinTypeSpec.Type.Short:
 872                         case BuiltinTypeSpec.Type.UShort:
 873                                 ig.Emit (OpCodes.Stind_I2);
 874                                 return;
 875                         case BuiltinTypeSpec.Type.Float:
 876                                 ig.Emit (OpCodes.Stind_R4);
 877                                 return;
 878                         case BuiltinTypeSpec.Type.Double:
 879                                 ig.Emit (OpCodes.Stind_R8);
 880                                 return;
 881                         case BuiltinTypeSpec.Type.Byte:
 882                         case BuiltinTypeSpec.Type.SByte:
 883                         case BuiltinTypeSpec.Type.Bool:
 884                                 ig.Emit (OpCodes.Stind_I1);
 885                                 return;
 886                         case BuiltinTypeSpec.Type.IntPtr:
 887                                 ig.Emit (OpCodes.Stind_I);
 888                                 return;
 889                         }
 890
 891                         switch (type.Kind) {
 892                         case MemberKind.Struct:
 893                         case MemberKind.TypeParameter:
 894                                 if (IsAnonymousStoreyMutateRequired)
 895                                         type = CurrentAnonymousMethod.Storey.Mutator.Mutate (type);
 896
 897                                 ig.Emit (OpCodes.Stobj, type.GetMetaInfo ());
 898                                 break;
 899                         default:
 900                                 ig.Emit (OpCodes.Stind_Ref);
 901                                 break;
 902                         }
 903                 }
 904
 905                 public void EmitThis ()
 906                 {
 907                         ig.Emit (OpCodes.Ldarg_0);
 908                 }
 909
 910                 public void EmitEpilogue ()
 911                 {
 912                         if (epilogue_expressions == null)
 913                                 return;
 914
 915                         foreach (var e in epilogue_expressions)
 916                                 e.EmitCleanup (this);
 917
 918                         epilogue_expressions = null;
 919                 }
 920
 921                 /// <summary>
 922                 ///   Returns a temporary storage for a variable of type t as
 923                 ///   a local variable in the current body.
 924                 /// </summary>
 925                 public LocalBuilder GetTemporaryLocal (TypeSpec t)
 926                 {
 927                         if (temporary_storage != null) {
 928                                 object o;
 929                                 if (temporary_storage.TryGetValue (t, out o)) {
 930                                         if (o is Stack<LocalBuilder>) {
 931                                                 var s = (Stack<LocalBuilder>) o;
 932                                                 o = s.Count == 0 ? null : s.Pop ();
 933                                         } else {
 934                                                 temporary_storage.Remove (t);
 935                                         }
 936                                 }
 937                                 if (o != null)
 938                                         return (LocalBuilder) o;
 939                         }
 940                         return DeclareLocal (t, false);
 941                 }
 942
 943                 public void FreeTemporaryLocal (LocalBuilder b, TypeSpec t)
 944                 {
 945                         if (temporary_storage == null) {
 946                                 temporary_storage = new Dictionary<TypeSpec, object> (ReferenceEquality<TypeSpec>.Default);
 947                                 temporary_storage.Add (t, b);
 948                                 return;
 949                         }
 950                         object o;
 951
 952                         if (!temporary_storage.TryGetValue (t, out o)) {
 953                                 temporary_storage.Add (t, b);
 954                                 return;
 955                         }
 956                         var s = o as Stack<LocalBuilder>;
 957                         if (s == null) {
 958                                 s = new Stack<LocalBuilder> ();
 959                                 s.Push ((LocalBuilder)o);
 960                                 temporary_storage [t] = s;
 961                         }
 962                         s.Push (b);
 963                 }
 964
 965                 /// <summary>
 966                 ///   ReturnValue creates on demand the LocalBuilder for the
 967                 ///   return value from the function.  By default this is not
 968                 ///   used.  This is only required when returns are found inside
 969                 ///   Try or Catch statements.
 970                 ///
 971                 ///   This method is typically invoked from the Emit phase, so
 972                 ///   we allow the creation of a return label if it was not
 973                 ///   requested during the resolution phase.   Could be cleaned
 974                 ///   up, but it would replicate a lot of logic in the Emit phase
 975                 ///   of the code that uses it.
 976                 /// </summary>
 977                 public LocalBuilder TemporaryReturn ()
 978                 {
 979                         if (return_value == null){
 980                                 return_value = DeclareLocal (return_type, false);
 981                         }
 982
 983                         return return_value;
 984                 }
 985         }
 986
 987         public class ConditionalAccessContext
 988         {
 989                 public ConditionalAccessContext (TypeSpec type, Label endLabel)
 990                 {
 991                         Type = type;
 992                         EndLabel = endLabel;
 993                 }
 994
 995                 public bool Statement { get; set; }
 996                 public Label EndLabel { get; private set; }
 997                 public TypeSpec Type { get; private set; }
 998         }
 999
1000         struct CallEmitter
1001         {
1002                 public Expression InstanceExpression;
1003
1004                 //
1005                 // When call has to leave an extra copy of all arguments on the stack
1006                 //
1007                 public bool DuplicateArguments;
1008
1009                 //
1010                 // Does not emit InstanceExpression load when InstanceExpressionOnStack
1011                 // is set. Used by compound assignments.
1012                 //
1013                 public bool InstanceExpressionOnStack;
1014
1015                 //
1016                 // Any of arguments contains await expression
1017                 //
1018                 public bool HasAwaitArguments;
1019
1020                 public bool ConditionalAccess;
1021
1022                 //
1023                 // When dealing with await arguments the original arguments are converted
1024                 // into a new set with hoisted stack results
1025                 //
1026                 public Arguments EmittedArguments;
1027
1028                 public void Emit (EmitContext ec, MethodSpec method, Arguments Arguments, Location loc)
1029                 {
1030                         EmitPredefined (ec, method, Arguments, false, loc);
1031                 }
1032
1033                 public void EmitStatement (EmitContext ec, MethodSpec method, Arguments Arguments, Location loc)
1034                 {
1035                         EmitPredefined (ec, method, Arguments, true, loc);
1036                 }
1037
1038                 public void EmitPredefined (EmitContext ec, MethodSpec method, Arguments Arguments, bool statement = false, Location? loc = null)
1039                 {
1040                         Expression instance_copy = null;
1041
1042                         if (!HasAwaitArguments && ec.HasSet (BuilderContext.Options.AsyncBody)) {
1043                                 HasAwaitArguments = Arguments != null && Arguments.ContainsEmitWithAwait ();
1044                                 if (HasAwaitArguments && InstanceExpressionOnStack) {
1045                                         throw new NotSupportedException ();
1046                                 }
1047                         }
1048
1049                         OpCode call_op;
1050                         LocalTemporary lt = null;
1051
1052                         if (method.IsStatic) {
1053                                 call_op = OpCodes.Call;
1054                         } else {
1055                                 call_op = IsVirtualCallRequired (InstanceExpression, method) ? OpCodes.Callvirt : OpCodes.Call;
1056
1057                                 if (HasAwaitArguments) {
1058                                         instance_copy = InstanceExpression.EmitToField (ec);
1059                                         var ie = new InstanceEmitter (instance_copy, IsAddressCall (instance_copy, call_op, method.DeclaringType));
1060
1061                                         if (Arguments == null) {
1062                                                 ie.EmitLoad (ec, true);
1063                                         }
1064                                 } else if (!InstanceExpressionOnStack) {
1065                                         var ie = new InstanceEmitter (InstanceExpression, IsAddressCall (InstanceExpression, call_op, method.DeclaringType));
1066                                         ie.Emit (ec, ConditionalAccess);
1067
1068                                         if (DuplicateArguments) {
1069                                                 ec.Emit (OpCodes.Dup);
1070                                                 if (Arguments != null && Arguments.Count != 0) {
1071                                                         lt = new LocalTemporary (ie.GetStackType (ec));
1072                                                         lt.Store (ec);
1073                                                         instance_copy = lt;
1074                                                 }
1075                                         }
1076                                 }
1077                         }
1078
1079                         if (Arguments != null && !InstanceExpressionOnStack) {
1080                                 EmittedArguments = Arguments.Emit (ec, DuplicateArguments, HasAwaitArguments);
1081                                 if (EmittedArguments != null) {
1082                                         if (instance_copy != null) {
1083                                                 var ie = new InstanceEmitter (instance_copy, IsAddressCall (instance_copy, call_op, method.DeclaringType));
1084                                                 ie.Emit (ec, ConditionalAccess);
1085
1086                                                 if (lt != null)
1087                                                         lt.Release (ec);
1088                                         }
1089
1090                                         EmittedArguments.Emit (ec);
1091                                 }
1092                         }
1093
1094                         if (call_op == OpCodes.Callvirt && (InstanceExpression.Type.IsGenericParameter || InstanceExpression.Type.IsStructOrEnum)) {
1095                                 ec.Emit (OpCodes.Constrained, InstanceExpression.Type);
1096                         }
1097
1098                         if (loc != null) {
1099                                 //
1100                                 // Emit explicit sequence point for expressions like Foo.Bar () to help debugger to
1101                                 // break at right place when LHS expression can be stepped-into
1102                                 //
1103                                 ec.MarkCallEntry (loc.Value);
1104                         }
1105
1106                         //
1107                         // Set instance expression to actual result expression. When it contains await it can be
1108                         // picked up by caller
1109                         //
1110                         InstanceExpression = instance_copy;
1111
1112                         if (method.Parameters.HasArglist) {
1113                                 var varargs_types = GetVarargsTypes (method, Arguments);
1114                                 ec.Emit (call_op, method, varargs_types);
1115                         } else {
1116                                 //
1117                                 // If you have:
1118                                 // this.DoFoo ();
1119                                 // and DoFoo is not virtual, you can omit the callvirt,
1120                                 // because you don't need the null checking behavior.
1121                                 //
1122                                 ec.Emit (call_op, method);
1123                         }
1124
1125                         //
1126                         // Pop the return value if there is one and stack should be empty
1127                         //
1128                         if (statement && method.ReturnType.Kind != MemberKind.Void)
1129                                 ec.Emit (OpCodes.Pop);
1130                 }
1131
1132                 static MetaType[] GetVarargsTypes (MethodSpec method, Arguments arguments)
1133                 {
1134                         AParametersCollection pd = method.Parameters;
1135
1136                         Argument a = arguments[pd.Count - 1];
1137                         Arglist list = (Arglist) a.Expr;
1138
1139                         return list.ArgumentTypes;
1140                 }
1141
1142                 //
1143                 // Used to decide whether call or callvirt is needed
1144                 //
1145                 static bool IsVirtualCallRequired (Expression instance, MethodSpec method)
1146                 {
1147                         //
1148                         // There are 2 scenarious where we emit callvirt
1149                         //
1150                         // Case 1: A method is virtual and it's not used to call base
1151                         // Case 2: A method instance expression can be null. In this casen callvirt ensures
1152                         // correct NRE exception when the method is called
1153                         //
1154                         var decl_type = method.DeclaringType;
1155                         if (decl_type.IsStruct || decl_type.IsEnum)
1156                                 return false;
1157
1158                         if (instance is BaseThis)
1159                                 return false;
1160
1161                         //
1162                         // It's non-virtual and will never be null and it can be determined
1163                         // whether it's known value or reference type by verifier
1164                         //
1165                         if (!method.IsVirtual && Expression.IsNeverNull (instance) && !instance.Type.IsGenericParameter)
1166                                 return false;
1167
1168                         return true;
1169                 }
1170
1171                 static bool IsAddressCall (Expression instance, OpCode callOpcode, TypeSpec declaringType)
1172                 {
1173                         var instance_type = instance.Type;
1174                         return (instance_type.IsStructOrEnum && (callOpcode == OpCodes.Callvirt || (callOpcode == OpCodes.Call && declaringType.IsStruct))) ||
1175                                 instance_type.IsGenericParameter || declaringType.IsNullableType;
1176                 }
1177         }
1178
1179         public struct InstanceEmitter
1180         {
1181                 readonly Expression instance;
1182                 readonly bool addressRequired;
1183
1184                 public InstanceEmitter (Expression instance, bool addressLoad)
1185                 {
1186                         this.instance = instance;
1187                         this.addressRequired = addressLoad;
1188                 }
1189
1190                 public void Emit (EmitContext ec, bool conditionalAccess)
1191                 {
1192                         Label NullOperatorLabel;
1193                         Nullable.Unwrap unwrap;
1194
1195                         if (conditionalAccess && Expression.IsNeverNull (instance))
1196                                 conditionalAccess = false;
1197
1198                         if (conditionalAccess) {
1199                                 NullOperatorLabel = ec.DefineLabel ();
1200                                 unwrap = instance as Nullable.Unwrap;
1201                         } else {
1202                                 NullOperatorLabel = new Label ();
1203                                 unwrap = null;
1204                         }
1205
1206                         IMemoryLocation instance_address = null;
1207                         bool conditional_access_dup = false;
1208
1209                         if (unwrap != null) {
1210                                 unwrap.Store (ec);
1211                                 unwrap.EmitCheck (ec);
1212                                 ec.Emit (OpCodes.Brtrue_S, NullOperatorLabel);
1213                         } else {
1214                                 if (conditionalAccess && addressRequired) {
1215                                         //
1216                                         // Don't allocate temp variable when instance load is cheap and load and load-address
1217                                         // operate on same memory
1218                                         //
1219                                         instance_address = instance as VariableReference;
1220                                         if (instance_address == null)
1221                                                 instance_address = instance as LocalTemporary;
1222
1223                                         if (instance_address == null) {
1224                                                 EmitLoad (ec, false);
1225                                                 ec.Emit (OpCodes.Dup);
1226                                                 ec.EmitLoadFromPtr (instance.Type);
1227
1228                                                 conditional_access_dup = true;
1229                                         } else {
1230                                                 instance.Emit (ec);
1231                                         }
1232                                 } else {
1233                                         EmitLoad (ec, !conditionalAccess);
1234
1235                                         if (conditionalAccess) {
1236                                                 conditional_access_dup = !IsInexpensiveLoad ();
1237                                                 if (conditional_access_dup)
1238                                                         ec.Emit (OpCodes.Dup);
1239                                         }
1240                                 }
1241
1242                                 if (conditionalAccess) {
1243                                         if (instance.Type.Kind == MemberKind.TypeParameter)
1244                                                 ec.Emit (OpCodes.Box, instance.Type);
1245
1246                                         ec.Emit (OpCodes.Brtrue_S, NullOperatorLabel);
1247
1248                                         if (conditional_access_dup)
1249                                                 ec.Emit (OpCodes.Pop);
1250                                 }
1251                         }
1252
1253                         if (conditionalAccess) {
1254                                 if (!ec.ConditionalAccess.Statement) {
1255                                         if (ec.ConditionalAccess.Type.IsNullableType)
1256                                                 Nullable.LiftedNull.Create (ec.ConditionalAccess.Type, Location.Null).Emit (ec);
1257                                         else
1258                                                 ec.EmitNull ();
1259                                 }
1260
1261                                 ec.Emit (OpCodes.Br, ec.ConditionalAccess.EndLabel);
1262                                 ec.MarkLabel (NullOperatorLabel);
1263
1264                                 if (instance_address != null) {
1265                                         instance_address.AddressOf (ec, AddressOp.Load);
1266                                 } else if (unwrap != null) {
1267                                         unwrap.Emit (ec);
1268                                         var tmp = ec.GetTemporaryLocal (unwrap.Type);
1269                                         ec.Emit (OpCodes.Stloc, tmp);
1270                                         ec.Emit (OpCodes.Ldloca, tmp);
1271                                         ec.FreeTemporaryLocal (tmp, unwrap.Type);
1272                                 } else if (!conditional_access_dup) {
1273                                         instance.Emit (ec);
1274                                 }
1275                         }
1276                 }
1277
1278                 public void EmitLoad (EmitContext ec, bool boxInstance)
1279                 {
1280                         var instance_type = instance.Type;
1281
1282                         //
1283                         // Push the instance expression
1284                         //
1285                         if (addressRequired) {
1286                                 //
1287                                 // If the expression implements IMemoryLocation, then
1288                                 // we can optimize and use AddressOf on the
1289                                 // return.
1290                                 //
1291                                 // If not we have to use some temporary storage for
1292                                 // it.
1293                                 var iml = instance as IMemoryLocation;
1294                                 if (iml != null) {
1295                                         iml.AddressOf (ec, AddressOp.Load);
1296                                 } else {
1297                                         LocalTemporary temp = new LocalTemporary (instance_type);
1298                                         instance.Emit (ec);
1299                                         temp.Store (ec);
1300                                         temp.AddressOf (ec, AddressOp.Load);
1301                                 }
1302
1303                                 return;
1304                         }
1305
1306                         instance.Emit (ec);
1307
1308                         // Only to make verifier happy
1309                         if (boxInstance && RequiresBoxing ()) {
1310                                 ec.Emit (OpCodes.Box, instance_type);
1311                         }
1312                 }
1313
1314                 public TypeSpec GetStackType (EmitContext ec)
1315                 {
1316                         var instance_type = instance.Type;
1317
1318                         if (addressRequired)
1319                                 return ReferenceContainer.MakeType (ec.Module, instance_type);
1320
1321                         if (instance_type.IsStructOrEnum)
1322                                 return ec.Module.Compiler.BuiltinTypes.Object;
1323
1324                         return instance_type;
1325                 }
1326
1327                 bool RequiresBoxing ()
1328                 {
1329                         var instance_type = instance.Type;
1330                         if (instance_type.IsGenericParameter && !(instance is This) && TypeSpec.IsReferenceType (instance_type))
1331                                 return true;
1332
1333                         if (instance_type.IsStructOrEnum)
1334                                 return true;
1335
1336                         return false;
1337                 }
1338
1339                 //
1340                 // Returns true for cheap race-free load, where we can avoid using dup
1341                 //
1342                 bool IsInexpensiveLoad ()
1343                 {
1344                         if (instance is Constant)
1345                                 return instance.IsSideEffectFree;
1346
1347                         if (RequiresBoxing ())
1348                                 return false;
1349
1350                         var vr = instance as VariableReference;
1351                         if (vr != null) {
1352                                 // Load from captured local would be racy without dup
1353                                 return !vr.IsRef && !vr.IsHoisted;
1354                         }
1355
1356                         if (instance is LocalTemporary)
1357                                 return true;
1358
1359                         var fe = instance as FieldExpr;
1360                         if (fe != null)
1361                                 return fe.IsStatic || fe.InstanceExpression is This;
1362
1363                         return false;
1364                 }
1365         }
1366 }