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 TypeSpec CurrentType {
 125                         get { return member_context.CurrentType; }
 126                 }
 127
 128                 public TypeParameters CurrentTypeParameters {
 129                     get { return member_context.CurrentTypeParameters; }
 130                 }
 131
 132                 public MemberCore CurrentTypeDefinition {
 133                         get { return member_context.CurrentMemberDefinition; }
 134                 }
 135
 136                 public bool EmitAccurateDebugInfo {
 137                         get {
 138                                 return (flags & Options.AccurateDebugInfo) != 0;
 139                         }
 140                 }
 141
 142                 public bool HasMethodSymbolBuilder {
 143                         get {
 144                                 return methodSymbols != null;
 145                         }
 146                 }
 147
 148                 public bool HasReturnLabel {
 149                         get {
 150                                 return return_label.HasValue;
 151                         }
 152                 }
 153
 154                 public bool IsStatic {
 155                         get { return member_context.IsStatic; }
 156                 }
 157
 158                 public bool IsAnonymousStoreyMutateRequired {
 159                         get {
 160                                 return CurrentAnonymousMethod != null &&
 161                                         CurrentAnonymousMethod.Storey != null &&
 162                                         CurrentAnonymousMethod.Storey.Mutator != null;
 163                         }
 164                 }
 165
 166                 public IMemberContext MemberContext {
 167                         get {
 168                                 return member_context;
 169                         }
 170                 }
 171
 172                 public ModuleContainer Module {
 173                         get {
 174                                 return member_context.Module;
 175                         }
 176                 }
 177
 178                 // Has to be used for specific emitter errors only any
 179                 // possible resolver errors have to be reported during Resolve
 180                 public Report Report {
 181                         get {
 182                                 return member_context.Module.Compiler.Report;
 183                         }
 184                 }
 185
 186                 public TypeSpec ReturnType {
 187                         get {
 188                                 return return_type;
 189                         }
 190                 }
 191
 192                 //
 193                 // The label where we have to jump before leaving the context
 194                 //
 195                 public Label ReturnLabel {
 196                         get {
 197                                 return return_label.Value;
 198                         }
 199                 }
 200
 201                 public List<IExpressionCleanup> StatementEpilogue {
 202                         get {
 203                                 return epilogue_expressions;
 204                         }
 205                 }
 206
 207                 #endregion
 208
 209                 public void AddStatementEpilog (IExpressionCleanup cleanupExpression)
 210                 {
 211                         if (epilogue_expressions == null) {
 212                                 epilogue_expressions = new List<IExpressionCleanup> ();
 213                         } else if (epilogue_expressions.Contains (cleanupExpression)) {
 214                                 return;
 215                         }
 216
 217                         epilogue_expressions.Add (cleanupExpression);
 218                 }
 219
 220                 public void AssertEmptyStack ()
 221                 {
 222 #if STATIC
 223                         if (ig.__StackHeight != 0)
 224                                 throw new InternalErrorException ("Await yields with non-empty stack in `{0}",
 225                                         member_context.GetSignatureForError ());
 226 #endif
 227                 }
 228
 229                 /// <summary>
 230                 ///   This is called immediately before emitting an IL opcode to tell the symbol
 231                 ///   writer to which source line this opcode belongs.
 232                 /// </summary>
 233                 public bool Mark (Location loc)
 234                 {
 235                         if ((flags & Options.OmitDebugInfo) != 0)
 236                                 return false;
 237
 238                         if (loc.IsNull || methodSymbols == null)
 239                                 return false;
 240
 241                         var sf = loc.SourceFile;
 242                         if (sf.IsHiddenLocation (loc))
 243                                 return false;
 244
 245 #if NET_4_0
 246                         methodSymbols.MarkSequencePoint (ig.ILOffset, sf.SourceFileEntry, loc.Row, loc.Column, false);
 247 #endif
 248                         return true;
 249                 }
 250
 251                 public void DefineLocalVariable (string name, LocalBuilder builder)
 252                 {
 253                         if ((flags & Options.OmitDebugInfo) != 0)
 254                                 return;
 255
 256                         methodSymbols.AddLocal (builder.LocalIndex, name);
 257                 }
 258
 259                 public void BeginCatchBlock (TypeSpec type)
 260                 {
 261                         ig.BeginCatchBlock (type.GetMetaInfo ());
 262                 }
 263
 264                 public void BeginExceptionBlock ()
 265                 {
 266                         ig.BeginExceptionBlock ();
 267                 }
 268
 269                 public void BeginFinallyBlock ()
 270                 {
 271                         ig.BeginFinallyBlock ();
 272                 }
 273
 274                 public void BeginScope ()
 275                 {
 276                         if ((flags & Options.OmitDebugInfo) != 0)
 277                                 return;
 278
 279 #if NET_4_0
 280                         methodSymbols.StartBlock (CodeBlockEntry.Type.Lexical, ig.ILOffset);
 281 #endif
 282                 }
 283
 284                 public void EndExceptionBlock ()
 285                 {
 286                         ig.EndExceptionBlock ();
 287                 }
 288
 289                 public void EndScope ()
 290                 {
 291                         if ((flags & Options.OmitDebugInfo) != 0)
 292                                 return;
 293
 294 #if NET_4_0
 295                         methodSymbols.EndBlock (ig.ILOffset);
 296 #endif
 297                 }
 298
 299                 //
 300                 // Creates a nested container in this context for all dynamic compiler generated stuff
 301                 //
 302                 internal DynamicSiteClass CreateDynamicSite ()
 303                 {
 304                         if (dynamic_site_container == null) {
 305                                 var mc = member_context.CurrentMemberDefinition as MemberBase;
 306                                 dynamic_site_container = new DynamicSiteClass (CurrentTypeDefinition.Parent.PartialContainer, mc, member_context.CurrentTypeParameters);
 307
 308                                 CurrentTypeDefinition.Module.AddCompilerGeneratedClass (dynamic_site_container);
 309                                 dynamic_site_container.CreateContainer ();
 310                                 dynamic_site_container.DefineContainer ();
 311                                 dynamic_site_container.Define ();
 312
 313                                 var inflator = new TypeParameterInflator (Module, CurrentType, TypeParameterSpec.EmptyTypes, TypeSpec.EmptyTypes);
 314                                 var inflated = dynamic_site_container.CurrentType.InflateMember (inflator);
 315                                 CurrentType.MemberCache.AddMember (inflated);
 316                         }
 317
 318                         return dynamic_site_container;
 319                 }
 320
 321                 public Label CreateReturnLabel ()
 322                 {
 323                         if (!return_label.HasValue)
 324                                 return_label = DefineLabel ();
 325
 326                         return return_label.Value;
 327                 }
 328
 329                 public LocalBuilder DeclareLocal (TypeSpec type, bool pinned)
 330                 {
 331                         if (IsAnonymousStoreyMutateRequired)
 332                                 type = CurrentAnonymousMethod.Storey.Mutator.Mutate (type);
 333
 334                         return ig.DeclareLocal (type.GetMetaInfo (), pinned);
 335                 }
 336
 337                 public Label DefineLabel ()
 338                 {
 339                         return ig.DefineLabel ();
 340                 }
 341
 342                 //
 343                 // Creates temporary field in current async storey
 344                 //
 345                 public FieldExpr GetTemporaryField (TypeSpec type)
 346                 {
 347                         var f = AsyncTaskStorey.AddCapturedLocalVariable (type);
 348                         var fexpr = new StackFieldExpr (f);
 349                         fexpr.InstanceExpression = new CompilerGeneratedThis (CurrentType, Location.Null);
 350                         return fexpr;
 351                 }
 352
 353                 public void MarkLabel (Label label)
 354                 {
 355                         ig.MarkLabel (label);
 356                 }
 357
 358                 public void Emit (OpCode opcode)
 359                 {
 360                         ig.Emit (opcode);
 361                 }
 362
 363                 public void Emit (OpCode opcode, LocalBuilder local)
 364                 {
 365                         ig.Emit (opcode, local);
 366                 }
 367
 368                 public void Emit (OpCode opcode, string arg)
 369                 {
 370                         ig.Emit (opcode, arg);
 371                 }
 372
 373                 public void Emit (OpCode opcode, double arg)
 374                 {
 375                         ig.Emit (opcode, arg);
 376                 }
 377
 378                 public void Emit (OpCode opcode, float arg)
 379                 {
 380                         ig.Emit (opcode, arg);
 381                 }
 382
 383                 public void Emit (OpCode opcode, Label label)
 384                 {
 385                         ig.Emit (opcode, label);
 386                 }
 387
 388                 public void Emit (OpCode opcode, Label[] labels)
 389                 {
 390                         ig.Emit (opcode, labels);
 391                 }
 392
 393                 public void Emit (OpCode opcode, TypeSpec type)
 394                 {
 395                         if (IsAnonymousStoreyMutateRequired)
 396                                 type = CurrentAnonymousMethod.Storey.Mutator.Mutate (type);
 397
 398                         ig.Emit (opcode, type.GetMetaInfo ());
 399                 }
 400
 401                 public void Emit (OpCode opcode, FieldSpec field)
 402                 {
 403                         if (IsAnonymousStoreyMutateRequired)
 404                                 field = field.Mutate (CurrentAnonymousMethod.Storey.Mutator);
 405
 406                         ig.Emit (opcode, field.GetMetaInfo ());
 407                 }
 408
 409                 public void Emit (OpCode opcode, MethodSpec method)
 410                 {
 411                         if (IsAnonymousStoreyMutateRequired)
 412                                 method = method.Mutate (CurrentAnonymousMethod.Storey.Mutator);
 413
 414                         if (method.IsConstructor)
 415                                 ig.Emit (opcode, (ConstructorInfo) method.GetMetaInfo ());
 416                         else
 417                                 ig.Emit (opcode, (MethodInfo) method.GetMetaInfo ());
 418                 }
 419
 420                 // TODO: REMOVE breaks mutator
 421                 public void Emit (OpCode opcode, MethodInfo method)
 422                 {
 423                         ig.Emit (opcode, method);
 424                 }
 425
 426                 public void Emit (OpCode opcode, MethodSpec method, MetaType[] vargs)
 427                 {
 428                         // TODO MemberCache: This should mutate too
 429                         ig.EmitCall (opcode, (MethodInfo) method.GetMetaInfo (), vargs);
 430                 }
 431
 432                 public void EmitArrayNew (ArrayContainer ac)
 433                 {
 434                         if (ac.Rank == 1) {
 435                                 var type = IsAnonymousStoreyMutateRequired ?
 436                                         CurrentAnonymousMethod.Storey.Mutator.Mutate (ac.Element) :
 437                                         ac.Element;
 438
 439                                 ig.Emit (OpCodes.Newarr, type.GetMetaInfo ());
 440                         } else {
 441                                 if (IsAnonymousStoreyMutateRequired)
 442                                         ac = (ArrayContainer) ac.Mutate (CurrentAnonymousMethod.Storey.Mutator);
 443
 444                                 ig.Emit (OpCodes.Newobj, ac.GetConstructor ());
 445                         }
 446                 }
 447
 448                 public void EmitArrayAddress (ArrayContainer ac)
 449                 {
 450                         if (ac.Rank > 1) {
 451                                 if (IsAnonymousStoreyMutateRequired)
 452                                         ac = (ArrayContainer) ac.Mutate (CurrentAnonymousMethod.Storey.Mutator);
 453
 454                                 ig.Emit (OpCodes.Call, ac.GetAddressMethod ());
 455                         } else {
 456                                 var type = IsAnonymousStoreyMutateRequired ?
 457                                         CurrentAnonymousMethod.Storey.Mutator.Mutate (ac.Element) :
 458                                         ac.Element;
 459
 460                                 ig.Emit (OpCodes.Ldelema, type.GetMetaInfo ());
 461                         }
 462                 }
 463
 464                 //
 465                 // Emits the right opcode to load from an array
 466                 //
 467                 public void EmitArrayLoad (ArrayContainer ac)
 468                 {
 469                         if (ac.Rank > 1) {
 470                                 if (IsAnonymousStoreyMutateRequired)
 471                                         ac = (ArrayContainer) ac.Mutate (CurrentAnonymousMethod.Storey.Mutator);
 472
 473                                 ig.Emit (OpCodes.Call, ac.GetGetMethod ());
 474                                 return;
 475                         }
 476
 477
 478                         var type = ac.Element;
 479                         if (type.Kind == MemberKind.Enum)
 480                                 type = EnumSpec.GetUnderlyingType (type);
 481
 482                         switch (type.BuiltinType) {
 483                         case BuiltinTypeSpec.Type.Byte:
 484                         case BuiltinTypeSpec.Type.Bool:
 485                                 ig.Emit (OpCodes.Ldelem_U1);
 486                                 break;
 487                         case BuiltinTypeSpec.Type.SByte:
 488                                 ig.Emit (OpCodes.Ldelem_I1);
 489                                 break;
 490                         case BuiltinTypeSpec.Type.Short:
 491                                 ig.Emit (OpCodes.Ldelem_I2);
 492                                 break;
 493                         case BuiltinTypeSpec.Type.UShort:
 494                         case BuiltinTypeSpec.Type.Char:
 495                                 ig.Emit (OpCodes.Ldelem_U2);
 496                                 break;
 497                         case BuiltinTypeSpec.Type.Int:
 498                                 ig.Emit (OpCodes.Ldelem_I4);
 499                                 break;
 500                         case BuiltinTypeSpec.Type.UInt:
 501                                 ig.Emit (OpCodes.Ldelem_U4);
 502                                 break;
 503                         case BuiltinTypeSpec.Type.ULong:
 504                         case BuiltinTypeSpec.Type.Long:
 505                                 ig.Emit (OpCodes.Ldelem_I8);
 506                                 break;
 507                         case BuiltinTypeSpec.Type.Float:
 508                                 ig.Emit (OpCodes.Ldelem_R4);
 509                                 break;
 510                         case BuiltinTypeSpec.Type.Double:
 511                                 ig.Emit (OpCodes.Ldelem_R8);
 512                                 break;
 513                         case BuiltinTypeSpec.Type.IntPtr:
 514                                 ig.Emit (OpCodes.Ldelem_I);
 515                                 break;
 516                         default:
 517                                 switch (type.Kind) {
 518                                 case MemberKind.Struct:
 519                                         if (IsAnonymousStoreyMutateRequired)
 520                                                 type = CurrentAnonymousMethod.Storey.Mutator.Mutate (type);
 521
 522                                         ig.Emit (OpCodes.Ldelema, type.GetMetaInfo ());
 523                                         ig.Emit (OpCodes.Ldobj, type.GetMetaInfo ());
 524                                         break;
 525                                 case MemberKind.TypeParameter:
 526                                         if (IsAnonymousStoreyMutateRequired)
 527                                                 type = CurrentAnonymousMethod.Storey.Mutator.Mutate (type);
 528
 529                                         ig.Emit (OpCodes.Ldelem, type.GetMetaInfo ());
 530                                         break;
 531                                 case MemberKind.PointerType:
 532                                         ig.Emit (OpCodes.Ldelem_I);
 533                                         break;
 534                                 default:
 535                                         ig.Emit (OpCodes.Ldelem_Ref);
 536                                         break;
 537                                 }
 538                                 break;
 539                         }
 540                 }
 541
 542                 //
 543                 // Emits the right opcode to store to an array
 544                 //
 545                 public void EmitArrayStore (ArrayContainer ac)
 546                 {
 547                         if (ac.Rank > 1) {
 548                                 if (IsAnonymousStoreyMutateRequired)
 549                                         ac = (ArrayContainer) ac.Mutate (CurrentAnonymousMethod.Storey.Mutator);
 550
 551                                 ig.Emit (OpCodes.Call, ac.GetSetMethod ());
 552                                 return;
 553                         }
 554
 555                         var type = ac.Element;
 556
 557                         if (type.Kind == MemberKind.Enum)
 558                                 type = EnumSpec.GetUnderlyingType (type);
 559
 560                         switch (type.BuiltinType) {
 561                         case BuiltinTypeSpec.Type.Byte:
 562                         case BuiltinTypeSpec.Type.SByte:
 563                         case BuiltinTypeSpec.Type.Bool:
 564                                 Emit (OpCodes.Stelem_I1);
 565                                 return;
 566                         case BuiltinTypeSpec.Type.Short:
 567                         case BuiltinTypeSpec.Type.UShort:
 568                         case BuiltinTypeSpec.Type.Char:
 569                                 Emit (OpCodes.Stelem_I2);
 570                                 return;
 571                         case BuiltinTypeSpec.Type.Int:
 572                         case BuiltinTypeSpec.Type.UInt:
 573                                 Emit (OpCodes.Stelem_I4);
 574                                 return;
 575                         case BuiltinTypeSpec.Type.Long:
 576                         case BuiltinTypeSpec.Type.ULong:
 577                                 Emit (OpCodes.Stelem_I8);
 578                                 return;
 579                         case BuiltinTypeSpec.Type.Float:
 580                                 Emit (OpCodes.Stelem_R4);
 581                                 return;
 582                         case BuiltinTypeSpec.Type.Double:
 583                                 Emit (OpCodes.Stelem_R8);
 584                                 return;
 585                         }
 586
 587                         switch (type.Kind) {
 588                         case MemberKind.Struct:
 589                                 Emit (OpCodes.Stobj, type);
 590                                 break;
 591                         case MemberKind.TypeParameter:
 592                                 Emit (OpCodes.Stelem, type);
 593                                 break;
 594                         case MemberKind.PointerType:
 595                                 Emit (OpCodes.Stelem_I);
 596                                 break;
 597                         default:
 598                                 Emit (OpCodes.Stelem_Ref);
 599                                 break;
 600                         }
 601                 }
 602
 603                 public void EmitInt (int i)
 604                 {
 605                         EmitIntConstant (i);
 606                 }
 607
 608                 void EmitIntConstant (int i)
 609                 {
 610                         switch (i) {
 611                         case -1:
 612                                 ig.Emit (OpCodes.Ldc_I4_M1);
 613                                 break;
 614
 615                         case 0:
 616                                 ig.Emit (OpCodes.Ldc_I4_0);
 617                                 break;
 618
 619                         case 1:
 620                                 ig.Emit (OpCodes.Ldc_I4_1);
 621                                 break;
 622
 623                         case 2:
 624                                 ig.Emit (OpCodes.Ldc_I4_2);
 625                                 break;
 626
 627                         case 3:
 628                                 ig.Emit (OpCodes.Ldc_I4_3);
 629                                 break;
 630
 631                         case 4:
 632                                 ig.Emit (OpCodes.Ldc_I4_4);
 633                                 break;
 634
 635                         case 5:
 636                                 ig.Emit (OpCodes.Ldc_I4_5);
 637                                 break;
 638
 639                         case 6:
 640                                 ig.Emit (OpCodes.Ldc_I4_6);
 641                                 break;
 642
 643                         case 7:
 644                                 ig.Emit (OpCodes.Ldc_I4_7);
 645                                 break;
 646
 647                         case 8:
 648                                 ig.Emit (OpCodes.Ldc_I4_8);
 649                                 break;
 650
 651                         default:
 652                                 if (i >= -128 && i <= 127) {
 653                                         ig.Emit (OpCodes.Ldc_I4_S, (sbyte) i);
 654                                 } else
 655                                         ig.Emit (OpCodes.Ldc_I4, i);
 656                                 break;
 657                         }
 658                 }
 659
 660                 public void EmitLong (long l)
 661                 {
 662                         if (l >= int.MinValue && l <= int.MaxValue) {
 663                                 EmitIntConstant (unchecked ((int) l));
 664                                 ig.Emit (OpCodes.Conv_I8);
 665                         } else if (l >= 0 && l <= uint.MaxValue) {
 666                                 EmitIntConstant (unchecked ((int) l));
 667                                 ig.Emit (OpCodes.Conv_U8);
 668                         } else {
 669                                 ig.Emit (OpCodes.Ldc_I8, l);
 670                         }
 671                 }
 672
 673                 //
 674                 // Load the object from the pointer.
 675                 //
 676                 public void EmitLoadFromPtr (TypeSpec type)
 677                 {
 678                         if (type.Kind == MemberKind.Enum)
 679                                 type = EnumSpec.GetUnderlyingType (type);
 680
 681                         switch (type.BuiltinType) {
 682                         case BuiltinTypeSpec.Type.Int:
 683                                 ig.Emit (OpCodes.Ldind_I4);
 684                                 break;
 685                         case BuiltinTypeSpec.Type.UInt:
 686                                 ig.Emit (OpCodes.Ldind_U4);
 687                                 break;
 688                         case BuiltinTypeSpec.Type.Short:
 689                                 ig.Emit (OpCodes.Ldind_I2);
 690                                 break;
 691                         case BuiltinTypeSpec.Type.UShort:
 692                         case BuiltinTypeSpec.Type.Char:
 693                                 ig.Emit (OpCodes.Ldind_U2);
 694                                 break;
 695                         case BuiltinTypeSpec.Type.Byte:
 696                                 ig.Emit (OpCodes.Ldind_U1);
 697                                 break;
 698                         case BuiltinTypeSpec.Type.SByte:
 699                         case BuiltinTypeSpec.Type.Bool:
 700                                 ig.Emit (OpCodes.Ldind_I1);
 701                                 break;
 702                         case BuiltinTypeSpec.Type.ULong:
 703                         case BuiltinTypeSpec.Type.Long:
 704                                 ig.Emit (OpCodes.Ldind_I8);
 705                                 break;
 706                         case BuiltinTypeSpec.Type.Float:
 707                                 ig.Emit (OpCodes.Ldind_R4);
 708                                 break;
 709                         case BuiltinTypeSpec.Type.Double:
 710                                 ig.Emit (OpCodes.Ldind_R8);
 711                                 break;
 712                         case BuiltinTypeSpec.Type.IntPtr:
 713                                 ig.Emit (OpCodes.Ldind_I);
 714                                 break;
 715                         default:
 716                                 switch (type.Kind) {
 717                                 case MemberKind.Struct:
 718                                 case MemberKind.TypeParameter:
 719                                         if (IsAnonymousStoreyMutateRequired)
 720                                                 type = CurrentAnonymousMethod.Storey.Mutator.Mutate (type);
 721
 722                                         ig.Emit (OpCodes.Ldobj, type.GetMetaInfo ());
 723                                         break;
 724                                 case MemberKind.PointerType:
 725                                         ig.Emit (OpCodes.Ldind_I);
 726                                         break;
 727                                 default:
 728                                         ig.Emit (OpCodes.Ldind_Ref);
 729                                         break;
 730                                 }
 731                                 break;
 732                         }
 733                 }
 734
 735                 public void EmitNull ()
 736                 {
 737                         ig.Emit (OpCodes.Ldnull);
 738                 }
 739
 740                 public void EmitArgumentAddress (int pos)
 741                 {
 742                         if (!IsStatic)
 743                                 ++pos;
 744
 745                         if (pos > byte.MaxValue)
 746                                 ig.Emit (OpCodes.Ldarga, pos);
 747                         else
 748                                 ig.Emit (OpCodes.Ldarga_S, (byte) pos);
 749                 }
 750
 751                 public void EmitArgumentLoad (int pos)
 752                 {
 753                         if (!IsStatic)
 754                                 ++pos;
 755
 756                         switch (pos) {
 757                         case 0: ig.Emit (OpCodes.Ldarg_0); break;
 758                         case 1: ig.Emit (OpCodes.Ldarg_1); break;
 759                         case 2: ig.Emit (OpCodes.Ldarg_2); break;
 760                         case 3: ig.Emit (OpCodes.Ldarg_3); break;
 761                         default:
 762                                 if (pos > byte.MaxValue)
 763                                         ig.Emit (OpCodes.Ldarg, pos);
 764                                 else
 765                                         ig.Emit (OpCodes.Ldarg_S, (byte) pos);
 766                                 break;
 767                         }
 768                 }
 769
 770                 public void EmitArgumentStore (int pos)
 771                 {
 772                         if (!IsStatic)
 773                                 ++pos;
 774
 775                         if (pos > byte.MaxValue)
 776                                 ig.Emit (OpCodes.Starg, pos);
 777                         else
 778                                 ig.Emit (OpCodes.Starg_S, (byte) pos);
 779                 }
 780
 781                 //
 782                 // The stack contains the pointer and the value of type `type'
 783                 //
 784                 public void EmitStoreFromPtr (TypeSpec type)
 785                 {
 786                         if (type.IsEnum)
 787                                 type = EnumSpec.GetUnderlyingType (type);
 788
 789                         switch (type.BuiltinType) {
 790                         case BuiltinTypeSpec.Type.Int:
 791                         case BuiltinTypeSpec.Type.UInt:
 792                                 ig.Emit (OpCodes.Stind_I4);
 793                                 return;
 794                         case BuiltinTypeSpec.Type.Long:
 795                         case BuiltinTypeSpec.Type.ULong:
 796                                 ig.Emit (OpCodes.Stind_I8);
 797                                 return;
 798                         case BuiltinTypeSpec.Type.Char:
 799                         case BuiltinTypeSpec.Type.Short:
 800                         case BuiltinTypeSpec.Type.UShort:
 801                                 ig.Emit (OpCodes.Stind_I2);
 802                                 return;
 803                         case BuiltinTypeSpec.Type.Float:
 804                                 ig.Emit (OpCodes.Stind_R4);
 805                                 return;
 806                         case BuiltinTypeSpec.Type.Double:
 807                                 ig.Emit (OpCodes.Stind_R8);
 808                                 return;
 809                         case BuiltinTypeSpec.Type.Byte:
 810                         case BuiltinTypeSpec.Type.SByte:
 811                         case BuiltinTypeSpec.Type.Bool:
 812                                 ig.Emit (OpCodes.Stind_I1);
 813                                 return;
 814                         case BuiltinTypeSpec.Type.IntPtr:
 815                                 ig.Emit (OpCodes.Stind_I);
 816                                 return;
 817                         }
 818
 819                         switch (type.Kind) {
 820                         case MemberKind.Struct:
 821                         case MemberKind.TypeParameter:
 822                                 if (IsAnonymousStoreyMutateRequired)
 823                                         type = CurrentAnonymousMethod.Storey.Mutator.Mutate (type);
 824
 825                                 ig.Emit (OpCodes.Stobj, type.GetMetaInfo ());
 826                                 break;
 827                         default:
 828                                 ig.Emit (OpCodes.Stind_Ref);
 829                                 break;
 830                         }
 831                 }
 832
 833                 public void EmitThis ()
 834                 {
 835                         ig.Emit (OpCodes.Ldarg_0);
 836                 }
 837
 838                 public void EmitEpilogue ()
 839                 {
 840                         if (epilogue_expressions == null)
 841                                 return;
 842
 843                         foreach (var e in epilogue_expressions)
 844                                 e.EmitCleanup (this);
 845
 846                         epilogue_expressions = null;
 847                 }
 848
 849                 /// <summary>
 850                 ///   Returns a temporary storage for a variable of type t as
 851                 ///   a local variable in the current body.
 852                 /// </summary>
 853                 public LocalBuilder GetTemporaryLocal (TypeSpec t)
 854                 {
 855                         if (temporary_storage != null) {
 856                                 object o;
 857                                 if (temporary_storage.TryGetValue (t, out o)) {
 858                                         if (o is Stack<LocalBuilder>) {
 859                                                 var s = (Stack<LocalBuilder>) o;
 860                                                 o = s.Count == 0 ? null : s.Pop ();
 861                                         } else {
 862                                                 temporary_storage.Remove (t);
 863                                         }
 864                                 }
 865                                 if (o != null)
 866                                         return (LocalBuilder) o;
 867                         }
 868                         return DeclareLocal (t, false);
 869                 }
 870
 871                 public void FreeTemporaryLocal (LocalBuilder b, TypeSpec t)
 872                 {
 873                         if (temporary_storage == null) {
 874                                 temporary_storage = new Dictionary<TypeSpec, object> (ReferenceEquality<TypeSpec>.Default);
 875                                 temporary_storage.Add (t, b);
 876                                 return;
 877                         }
 878                         object o;
 879
 880                         if (!temporary_storage.TryGetValue (t, out o)) {
 881                                 temporary_storage.Add (t, b);
 882                                 return;
 883                         }
 884                         var s = o as Stack<LocalBuilder>;
 885                         if (s == null) {
 886                                 s = new Stack<LocalBuilder> ();
 887                                 s.Push ((LocalBuilder)o);
 888                                 temporary_storage [t] = s;
 889                         }
 890                         s.Push (b);
 891                 }
 892
 893                 /// <summary>
 894                 ///   ReturnValue creates on demand the LocalBuilder for the
 895                 ///   return value from the function.  By default this is not
 896                 ///   used.  This is only required when returns are found inside
 897                 ///   Try or Catch statements.
 898                 ///
 899                 ///   This method is typically invoked from the Emit phase, so
 900                 ///   we allow the creation of a return label if it was not
 901                 ///   requested during the resolution phase.   Could be cleaned
 902                 ///   up, but it would replicate a lot of logic in the Emit phase
 903                 ///   of the code that uses it.
 904                 /// </summary>
 905                 public LocalBuilder TemporaryReturn ()
 906                 {
 907                         if (return_value == null){
 908                                 return_value = DeclareLocal (return_type, false);
 909                         }
 910
 911                         return return_value;
 912                 }
 913         }
 914
 915         struct CallEmitter
 916         {
 917                 public Expression InstanceExpression;
 918
 919                 //
 920                 // When set leaves an extra copy of all arguments on the stack
 921                 //
 922                 public bool DuplicateArguments;
 923
 924                 //
 925                 // Does not emit InstanceExpression load when InstanceExpressionOnStack
 926                 // is set. Used by compound assignments.
 927                 //
 928                 public bool InstanceExpressionOnStack;
 929
 930                 //
 931                 // Any of arguments contains await expression
 932                 //
 933                 public bool HasAwaitArguments;
 934
 935                 //
 936                 // When dealing with await arguments the original arguments are converted
 937                 // into a new set with hoisted stack results
 938                 //
 939                 public Arguments EmittedArguments;
 940
 941                 public void Emit (EmitContext ec, MethodSpec method, Arguments Arguments, Location loc)
 942                 {
 943                         // Speed up the check by not doing it on not allowed targets
 944                         if (method.ReturnType.Kind == MemberKind.Void && method.IsConditionallyExcluded (ec.MemberContext, loc))
 945                                 return;
 946
 947                         EmitPredefined (ec, method, Arguments, loc);
 948                 }
 949
 950                 public void EmitPredefined (EmitContext ec, MethodSpec method, Arguments Arguments, Location? loc = null)
 951                 {
 952                         Expression instance_copy = null;
 953
 954                         if (!HasAwaitArguments && ec.HasSet (BuilderContext.Options.AsyncBody)) {
 955                                 HasAwaitArguments = Arguments != null && Arguments.ContainsEmitWithAwait ();
 956                                 if (HasAwaitArguments && InstanceExpressionOnStack) {
 957                                         throw new NotSupportedException ();
 958                                 }
 959                         }
 960
 961                         OpCode call_op;
 962                         LocalTemporary lt = null;
 963
 964                         if (method.IsStatic) {
 965                                 call_op = OpCodes.Call;
 966                         } else {
 967                                 if (IsVirtualCallRequired (InstanceExpression, method)) {
 968                                         call_op = OpCodes.Callvirt;
 969                                 } else {
 970                                         call_op = OpCodes.Call;
 971                                 }
 972
 973                                 if (HasAwaitArguments) {
 974                                         instance_copy = InstanceExpression.EmitToField (ec);
 975                                         if (Arguments == null)
 976                                                 EmitCallInstance (ec, instance_copy, method.DeclaringType, call_op);
 977                                 } else if (!InstanceExpressionOnStack) {
 978                                         var instance_on_stack_type = EmitCallInstance (ec, InstanceExpression, method.DeclaringType, call_op);
 979
 980                                         if (DuplicateArguments) {
 981                                                 ec.Emit (OpCodes.Dup);
 982                                                 if (Arguments != null && Arguments.Count != 0) {
 983                                                         lt = new LocalTemporary (instance_on_stack_type);
 984                                                         lt.Store (ec);
 985                                                         instance_copy = lt;
 986                                                 }
 987                                         }
 988                                 }
 989                         }
 990
 991                         if (Arguments != null && !InstanceExpressionOnStack) {
 992                                 EmittedArguments = Arguments.Emit (ec, DuplicateArguments, HasAwaitArguments);
 993                                 if (EmittedArguments != null) {
 994                                         if (instance_copy != null) {
 995                                                 EmitCallInstance (ec, instance_copy, method.DeclaringType, call_op);
 996
 997                                                 if (lt != null)
 998                                                         lt.Release (ec);
 999                                         }
1000
1001                                         EmittedArguments.Emit (ec);
1002                                 }
1003                         }
1004
1005                         if (call_op == OpCodes.Callvirt && (InstanceExpression.Type.IsGenericParameter || InstanceExpression.Type.IsStruct)) {
1006                                 ec.Emit (OpCodes.Constrained, InstanceExpression.Type);
1007                         }
1008
1009                         if (loc != null) {
1010                                 //
1011                                 // Emit explicit sequence point for expressions like Foo.Bar () to help debugger to
1012                                 // break at right place when LHS expression can be stepped-into
1013                                 //
1014                                 // TODO: The list is probably not comprehensive, need to do more testing
1015                                 //
1016                                 if (InstanceExpression is PropertyExpr || InstanceExpression is Invocation || InstanceExpression is IndexerExpr ||
1017                                         InstanceExpression is New || InstanceExpression is DelegateInvocation)
1018                                         ec.Mark (loc.Value);
1019                         }
1020
1021                         //
1022                         // Set instance expression to actual result expression. When it contains await it can be
1023                         // picked up by caller
1024                         //
1025                         InstanceExpression = instance_copy;
1026
1027                         if (method.Parameters.HasArglist) {
1028                                 var varargs_types = GetVarargsTypes (method, Arguments);
1029                                 ec.Emit (call_op, method, varargs_types);
1030                                 return;
1031                         }
1032
1033                         //
1034                         // If you have:
1035                         // this.DoFoo ();
1036                         // and DoFoo is not virtual, you can omit the callvirt,
1037                         // because you don't need the null checking behavior.
1038                         //
1039                         ec.Emit (call_op, method);
1040                 }
1041
1042                 static TypeSpec EmitCallInstance (EmitContext ec, Expression instance, TypeSpec declaringType, OpCode callOpcode)
1043                 {
1044                         var instance_type = instance.Type;
1045
1046                         //
1047                         // Push the instance expression
1048                         //
1049                         if ((instance_type.IsStruct && (callOpcode == OpCodes.Callvirt || (callOpcode == OpCodes.Call && declaringType.IsStruct))) ||
1050                                 instance_type.IsGenericParameter || declaringType.IsNullableType) {
1051                                 //
1052                                 // If the expression implements IMemoryLocation, then
1053                                 // we can optimize and use AddressOf on the
1054                                 // return.
1055                                 //
1056                                 // If not we have to use some temporary storage for
1057                                 // it.
1058                                 var iml = instance as IMemoryLocation;
1059                                 if (iml != null) {
1060                                         iml.AddressOf (ec, AddressOp.Load);
1061                                 } else {
1062                                         LocalTemporary temp = new LocalTemporary (instance_type);
1063                                         instance.Emit (ec);
1064                                         temp.Store (ec);
1065                                         temp.AddressOf (ec, AddressOp.Load);
1066                                 }
1067
1068                                 return ReferenceContainer.MakeType (ec.Module, instance_type);
1069                         }
1070
1071                         if (instance_type.IsEnum || instance_type.IsStruct) {
1072                                 instance.Emit (ec);
1073                                 ec.Emit (OpCodes.Box, instance_type);
1074                                 return ec.BuiltinTypes.Object;
1075                         }
1076
1077                         instance.Emit (ec);
1078                         return instance_type;
1079                 }
1080
1081                 static MetaType[] GetVarargsTypes (MethodSpec method, Arguments arguments)
1082                 {
1083                         AParametersCollection pd = method.Parameters;
1084
1085                         Argument a = arguments[pd.Count - 1];
1086                         Arglist list = (Arglist) a.Expr;
1087
1088                         return list.ArgumentTypes;
1089                 }
1090
1091                 //
1092                 // Used to decide whether call or callvirt is needed
1093                 //
1094                 static bool IsVirtualCallRequired (Expression instance, MethodSpec method)
1095                 {
1096                         //
1097                         // There are 2 scenarious where we emit callvirt
1098                         //
1099                         // Case 1: A method is virtual and it's not used to call base
1100                         // Case 2: A method instance expression can be null. In this casen callvirt ensures
1101                         // correct NRE exception when the method is called
1102                         //
1103                         var decl_type = method.DeclaringType;
1104                         if (decl_type.IsStruct || decl_type.IsEnum)
1105                                 return false;
1106
1107                         if (instance is BaseThis)
1108                                 return false;
1109
1110                         //
1111                         // It's non-virtual and will never be null and it can be determined
1112                         // whether it's known value or reference type by verifier
1113                         //
1114                         if (!method.IsVirtual && (instance is This || instance is New || instance is ArrayCreation || instance is DelegateCreation) &&
1115                                 !instance.Type.IsGenericParameter)
1116                                 return false;
1117
1118                         return true;
1119                 }
1120         }
1121 }