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 MarkCallEntry (Location loc)
 252                 {
 253                         if (!EmitAccurateDebugInfo)
 254                                 return;
 255
 256                         //
 257                         // TODO: This should emit different kind of sequence point to make
 258                         // step-over work for statement over multiple lines
 259                         //
 260                         // Debugging experience for Foo (A () + B ()) where A and B are
 261                         // on separate lines is not great
 262                         //
 263                         Mark (loc);
 264                 }
 265
 266                 public void DefineLocalVariable (string name, LocalBuilder builder)
 267                 {
 268                         if ((flags & Options.OmitDebugInfo) != 0)
 269                                 return;
 270
 271                         methodSymbols.AddLocal (builder.LocalIndex, name);
 272                 }
 273
 274                 public void BeginCatchBlock (TypeSpec type)
 275                 {
 276                         if (IsAnonymousStoreyMutateRequired)
 277                                 type = CurrentAnonymousMethod.Storey.Mutator.Mutate (type);
 278
 279                         ig.BeginCatchBlock (type.GetMetaInfo ());
 280                 }
 281
 282                 public void BeginExceptionBlock ()
 283                 {
 284                         ig.BeginExceptionBlock ();
 285                 }
 286
 287                 public void BeginFinallyBlock ()
 288                 {
 289                         ig.BeginFinallyBlock ();
 290                 }
 291
 292                 public void BeginScope ()
 293                 {
 294                         if ((flags & Options.OmitDebugInfo) != 0)
 295                                 return;
 296
 297 #if NET_4_0
 298                         methodSymbols.StartBlock (CodeBlockEntry.Type.Lexical, ig.ILOffset);
 299 #endif
 300                 }
 301
 302                 public void BeginCompilerScope ()
 303                 {
 304                         if ((flags & Options.OmitDebugInfo) != 0)
 305                                 return;
 306
 307 #if NET_4_0
 308                         methodSymbols.StartBlock (CodeBlockEntry.Type.CompilerGenerated, ig.ILOffset);
 309 #endif
 310                 }
 311
 312                 public void EndExceptionBlock ()
 313                 {
 314                         ig.EndExceptionBlock ();
 315                 }
 316
 317                 public void EndScope ()
 318                 {
 319                         if ((flags & Options.OmitDebugInfo) != 0)
 320                                 return;
 321
 322 #if NET_4_0
 323                         methodSymbols.EndBlock (ig.ILOffset);
 324 #endif
 325                 }
 326
 327                 //
 328                 // Creates a nested container in this context for all dynamic compiler generated stuff
 329                 //
 330                 internal DynamicSiteClass CreateDynamicSite ()
 331                 {
 332                         if (dynamic_site_container == null) {
 333                                 var mc = member_context.CurrentMemberDefinition as MemberBase;
 334                                 dynamic_site_container = new DynamicSiteClass (CurrentTypeDefinition.Parent.PartialContainer, mc, member_context.CurrentTypeParameters);
 335
 336                                 CurrentTypeDefinition.Module.AddCompilerGeneratedClass (dynamic_site_container);
 337                                 dynamic_site_container.CreateContainer ();
 338                                 dynamic_site_container.DefineContainer ();
 339                                 dynamic_site_container.Define ();
 340
 341                                 var inflator = new TypeParameterInflator (Module, CurrentType, TypeParameterSpec.EmptyTypes, TypeSpec.EmptyTypes);
 342                                 var inflated = dynamic_site_container.CurrentType.InflateMember (inflator);
 343                                 CurrentType.MemberCache.AddMember (inflated);
 344                         }
 345
 346                         return dynamic_site_container;
 347                 }
 348
 349                 public Label CreateReturnLabel ()
 350                 {
 351                         if (!return_label.HasValue)
 352                                 return_label = DefineLabel ();
 353
 354                         return return_label.Value;
 355                 }
 356
 357                 public LocalBuilder DeclareLocal (TypeSpec type, bool pinned)
 358                 {
 359                         if (IsAnonymousStoreyMutateRequired)
 360                                 type = CurrentAnonymousMethod.Storey.Mutator.Mutate (type);
 361
 362                         return ig.DeclareLocal (type.GetMetaInfo (), pinned);
 363                 }
 364
 365                 public Label DefineLabel ()
 366                 {
 367                         return ig.DefineLabel ();
 368                 }
 369
 370                 //
 371                 // Creates temporary field in current async storey
 372                 //
 373                 public StackFieldExpr GetTemporaryField (TypeSpec type)
 374                 {
 375                         var f = AsyncTaskStorey.AddCapturedLocalVariable (type);
 376                         var fexpr = new StackFieldExpr (f);
 377                         fexpr.InstanceExpression = new CompilerGeneratedThis (CurrentType, Location.Null);
 378                         return fexpr;
 379                 }
 380
 381                 public void MarkLabel (Label label)
 382                 {
 383                         ig.MarkLabel (label);
 384                 }
 385
 386                 public void Emit (OpCode opcode)
 387                 {
 388                         ig.Emit (opcode);
 389                 }
 390
 391                 public void Emit (OpCode opcode, LocalBuilder local)
 392                 {
 393                         ig.Emit (opcode, local);
 394                 }
 395
 396                 public void Emit (OpCode opcode, string arg)
 397                 {
 398                         ig.Emit (opcode, arg);
 399                 }
 400
 401                 public void Emit (OpCode opcode, double arg)
 402                 {
 403                         ig.Emit (opcode, arg);
 404                 }
 405
 406                 public void Emit (OpCode opcode, float arg)
 407                 {
 408                         ig.Emit (opcode, arg);
 409                 }
 410
 411                 public void Emit (OpCode opcode, Label label)
 412                 {
 413                         ig.Emit (opcode, label);
 414                 }
 415
 416                 public void Emit (OpCode opcode, Label[] labels)
 417                 {
 418                         ig.Emit (opcode, labels);
 419                 }
 420
 421                 public void Emit (OpCode opcode, TypeSpec type)
 422                 {
 423                         if (IsAnonymousStoreyMutateRequired)
 424                                 type = CurrentAnonymousMethod.Storey.Mutator.Mutate (type);
 425
 426                         ig.Emit (opcode, type.GetMetaInfo ());
 427                 }
 428
 429                 public void Emit (OpCode opcode, FieldSpec field)
 430                 {
 431                         if (IsAnonymousStoreyMutateRequired)
 432                                 field = field.Mutate (CurrentAnonymousMethod.Storey.Mutator);
 433
 434                         ig.Emit (opcode, field.GetMetaInfo ());
 435                 }
 436
 437                 public void Emit (OpCode opcode, MethodSpec method)
 438                 {
 439                         if (IsAnonymousStoreyMutateRequired)
 440                                 method = method.Mutate (CurrentAnonymousMethod.Storey.Mutator);
 441
 442                         if (method.IsConstructor)
 443                                 ig.Emit (opcode, (ConstructorInfo) method.GetMetaInfo ());
 444                         else
 445                                 ig.Emit (opcode, (MethodInfo) method.GetMetaInfo ());
 446                 }
 447
 448                 // TODO: REMOVE breaks mutator
 449                 public void Emit (OpCode opcode, MethodInfo method)
 450                 {
 451                         ig.Emit (opcode, method);
 452                 }
 453
 454                 public void Emit (OpCode opcode, MethodSpec method, MetaType[] vargs)
 455                 {
 456                         // TODO MemberCache: This should mutate too
 457                         ig.EmitCall (opcode, (MethodInfo) method.GetMetaInfo (), vargs);
 458                 }
 459
 460                 public void EmitArrayNew (ArrayContainer ac)
 461                 {
 462                         if (ac.Rank == 1) {
 463                                 var type = IsAnonymousStoreyMutateRequired ?
 464                                         CurrentAnonymousMethod.Storey.Mutator.Mutate (ac.Element) :
 465                                         ac.Element;
 466
 467                                 ig.Emit (OpCodes.Newarr, type.GetMetaInfo ());
 468                         } else {
 469                                 if (IsAnonymousStoreyMutateRequired)
 470                                         ac = (ArrayContainer) ac.Mutate (CurrentAnonymousMethod.Storey.Mutator);
 471
 472                                 ig.Emit (OpCodes.Newobj, ac.GetConstructor ());
 473                         }
 474                 }
 475
 476                 public void EmitArrayAddress (ArrayContainer ac)
 477                 {
 478                         if (ac.Rank > 1) {
 479                                 if (IsAnonymousStoreyMutateRequired)
 480                                         ac = (ArrayContainer) ac.Mutate (CurrentAnonymousMethod.Storey.Mutator);
 481
 482                                 ig.Emit (OpCodes.Call, ac.GetAddressMethod ());
 483                         } else {
 484                                 var type = IsAnonymousStoreyMutateRequired ?
 485                                         CurrentAnonymousMethod.Storey.Mutator.Mutate (ac.Element) :
 486                                         ac.Element;
 487
 488                                 ig.Emit (OpCodes.Ldelema, type.GetMetaInfo ());
 489                         }
 490                 }
 491
 492                 //
 493                 // Emits the right opcode to load from an array
 494                 //
 495                 public void EmitArrayLoad (ArrayContainer ac)
 496                 {
 497                         if (ac.Rank > 1) {
 498                                 if (IsAnonymousStoreyMutateRequired)
 499                                         ac = (ArrayContainer) ac.Mutate (CurrentAnonymousMethod.Storey.Mutator);
 500
 501                                 ig.Emit (OpCodes.Call, ac.GetGetMethod ());
 502                                 return;
 503                         }
 504
 505
 506                         var type = ac.Element;
 507                         if (type.Kind == MemberKind.Enum)
 508                                 type = EnumSpec.GetUnderlyingType (type);
 509
 510                         switch (type.BuiltinType) {
 511                         case BuiltinTypeSpec.Type.Byte:
 512                         case BuiltinTypeSpec.Type.Bool:
 513                                 ig.Emit (OpCodes.Ldelem_U1);
 514                                 break;
 515                         case BuiltinTypeSpec.Type.SByte:
 516                                 ig.Emit (OpCodes.Ldelem_I1);
 517                                 break;
 518                         case BuiltinTypeSpec.Type.Short:
 519                                 ig.Emit (OpCodes.Ldelem_I2);
 520                                 break;
 521                         case BuiltinTypeSpec.Type.UShort:
 522                         case BuiltinTypeSpec.Type.Char:
 523                                 ig.Emit (OpCodes.Ldelem_U2);
 524                                 break;
 525                         case BuiltinTypeSpec.Type.Int:
 526                                 ig.Emit (OpCodes.Ldelem_I4);
 527                                 break;
 528                         case BuiltinTypeSpec.Type.UInt:
 529                                 ig.Emit (OpCodes.Ldelem_U4);
 530                                 break;
 531                         case BuiltinTypeSpec.Type.ULong:
 532                         case BuiltinTypeSpec.Type.Long:
 533                                 ig.Emit (OpCodes.Ldelem_I8);
 534                                 break;
 535                         case BuiltinTypeSpec.Type.Float:
 536                                 ig.Emit (OpCodes.Ldelem_R4);
 537                                 break;
 538                         case BuiltinTypeSpec.Type.Double:
 539                                 ig.Emit (OpCodes.Ldelem_R8);
 540                                 break;
 541                         case BuiltinTypeSpec.Type.IntPtr:
 542                                 ig.Emit (OpCodes.Ldelem_I);
 543                                 break;
 544                         default:
 545                                 switch (type.Kind) {
 546                                 case MemberKind.Struct:
 547                                         if (IsAnonymousStoreyMutateRequired)
 548                                                 type = CurrentAnonymousMethod.Storey.Mutator.Mutate (type);
 549
 550                                         ig.Emit (OpCodes.Ldelema, type.GetMetaInfo ());
 551                                         ig.Emit (OpCodes.Ldobj, type.GetMetaInfo ());
 552                                         break;
 553                                 case MemberKind.TypeParameter:
 554                                         if (IsAnonymousStoreyMutateRequired)
 555                                                 type = CurrentAnonymousMethod.Storey.Mutator.Mutate (type);
 556
 557                                         ig.Emit (OpCodes.Ldelem, type.GetMetaInfo ());
 558                                         break;
 559                                 case MemberKind.PointerType:
 560                                         ig.Emit (OpCodes.Ldelem_I);
 561                                         break;
 562                                 default:
 563                                         ig.Emit (OpCodes.Ldelem_Ref);
 564                                         break;
 565                                 }
 566                                 break;
 567                         }
 568                 }
 569
 570                 //
 571                 // Emits the right opcode to store to an array
 572                 //
 573                 public void EmitArrayStore (ArrayContainer ac)
 574                 {
 575                         if (ac.Rank > 1) {
 576                                 if (IsAnonymousStoreyMutateRequired)
 577                                         ac = (ArrayContainer) ac.Mutate (CurrentAnonymousMethod.Storey.Mutator);
 578
 579                                 ig.Emit (OpCodes.Call, ac.GetSetMethod ());
 580                                 return;
 581                         }
 582
 583                         var type = ac.Element;
 584
 585                         if (type.Kind == MemberKind.Enum)
 586                                 type = EnumSpec.GetUnderlyingType (type);
 587
 588                         switch (type.BuiltinType) {
 589                         case BuiltinTypeSpec.Type.Byte:
 590                         case BuiltinTypeSpec.Type.SByte:
 591                         case BuiltinTypeSpec.Type.Bool:
 592                                 Emit (OpCodes.Stelem_I1);
 593                                 return;
 594                         case BuiltinTypeSpec.Type.Short:
 595                         case BuiltinTypeSpec.Type.UShort:
 596                         case BuiltinTypeSpec.Type.Char:
 597                                 Emit (OpCodes.Stelem_I2);
 598                                 return;
 599                         case BuiltinTypeSpec.Type.Int:
 600                         case BuiltinTypeSpec.Type.UInt:
 601                                 Emit (OpCodes.Stelem_I4);
 602                                 return;
 603                         case BuiltinTypeSpec.Type.Long:
 604                         case BuiltinTypeSpec.Type.ULong:
 605                                 Emit (OpCodes.Stelem_I8);
 606                                 return;
 607                         case BuiltinTypeSpec.Type.Float:
 608                                 Emit (OpCodes.Stelem_R4);
 609                                 return;
 610                         case BuiltinTypeSpec.Type.Double:
 611                                 Emit (OpCodes.Stelem_R8);
 612                                 return;
 613                         }
 614
 615                         switch (type.Kind) {
 616                         case MemberKind.Struct:
 617                                 Emit (OpCodes.Stobj, type);
 618                                 break;
 619                         case MemberKind.TypeParameter:
 620                                 Emit (OpCodes.Stelem, type);
 621                                 break;
 622                         case MemberKind.PointerType:
 623                                 Emit (OpCodes.Stelem_I);
 624                                 break;
 625                         default:
 626                                 Emit (OpCodes.Stelem_Ref);
 627                                 break;
 628                         }
 629                 }
 630
 631                 public void EmitInt (int i)
 632                 {
 633                         EmitIntConstant (i);
 634                 }
 635
 636                 void EmitIntConstant (int i)
 637                 {
 638                         switch (i) {
 639                         case -1:
 640                                 ig.Emit (OpCodes.Ldc_I4_M1);
 641                                 break;
 642
 643                         case 0:
 644                                 ig.Emit (OpCodes.Ldc_I4_0);
 645                                 break;
 646
 647                         case 1:
 648                                 ig.Emit (OpCodes.Ldc_I4_1);
 649                                 break;
 650
 651                         case 2:
 652                                 ig.Emit (OpCodes.Ldc_I4_2);
 653                                 break;
 654
 655                         case 3:
 656                                 ig.Emit (OpCodes.Ldc_I4_3);
 657                                 break;
 658
 659                         case 4:
 660                                 ig.Emit (OpCodes.Ldc_I4_4);
 661                                 break;
 662
 663                         case 5:
 664                                 ig.Emit (OpCodes.Ldc_I4_5);
 665                                 break;
 666
 667                         case 6:
 668                                 ig.Emit (OpCodes.Ldc_I4_6);
 669                                 break;
 670
 671                         case 7:
 672                                 ig.Emit (OpCodes.Ldc_I4_7);
 673                                 break;
 674
 675                         case 8:
 676                                 ig.Emit (OpCodes.Ldc_I4_8);
 677                                 break;
 678
 679                         default:
 680                                 if (i >= -128 && i <= 127) {
 681                                         ig.Emit (OpCodes.Ldc_I4_S, (sbyte) i);
 682                                 } else
 683                                         ig.Emit (OpCodes.Ldc_I4, i);
 684                                 break;
 685                         }
 686                 }
 687
 688                 public void EmitLong (long l)
 689                 {
 690                         if (l >= int.MinValue && l <= int.MaxValue) {
 691                                 EmitIntConstant (unchecked ((int) l));
 692                                 ig.Emit (OpCodes.Conv_I8);
 693                         } else if (l >= 0 && l <= uint.MaxValue) {
 694                                 EmitIntConstant (unchecked ((int) l));
 695                                 ig.Emit (OpCodes.Conv_U8);
 696                         } else {
 697                                 ig.Emit (OpCodes.Ldc_I8, l);
 698                         }
 699                 }
 700
 701                 //
 702                 // Load the object from the pointer.
 703                 //
 704                 public void EmitLoadFromPtr (TypeSpec type)
 705                 {
 706                         if (type.Kind == MemberKind.Enum)
 707                                 type = EnumSpec.GetUnderlyingType (type);
 708
 709                         switch (type.BuiltinType) {
 710                         case BuiltinTypeSpec.Type.Int:
 711                                 ig.Emit (OpCodes.Ldind_I4);
 712                                 break;
 713                         case BuiltinTypeSpec.Type.UInt:
 714                                 ig.Emit (OpCodes.Ldind_U4);
 715                                 break;
 716                         case BuiltinTypeSpec.Type.Short:
 717                                 ig.Emit (OpCodes.Ldind_I2);
 718                                 break;
 719                         case BuiltinTypeSpec.Type.UShort:
 720                         case BuiltinTypeSpec.Type.Char:
 721                                 ig.Emit (OpCodes.Ldind_U2);
 722                                 break;
 723                         case BuiltinTypeSpec.Type.Byte:
 724                                 ig.Emit (OpCodes.Ldind_U1);
 725                                 break;
 726                         case BuiltinTypeSpec.Type.SByte:
 727                         case BuiltinTypeSpec.Type.Bool:
 728                                 ig.Emit (OpCodes.Ldind_I1);
 729                                 break;
 730                         case BuiltinTypeSpec.Type.ULong:
 731                         case BuiltinTypeSpec.Type.Long:
 732                                 ig.Emit (OpCodes.Ldind_I8);
 733                                 break;
 734                         case BuiltinTypeSpec.Type.Float:
 735                                 ig.Emit (OpCodes.Ldind_R4);
 736                                 break;
 737                         case BuiltinTypeSpec.Type.Double:
 738                                 ig.Emit (OpCodes.Ldind_R8);
 739                                 break;
 740                         case BuiltinTypeSpec.Type.IntPtr:
 741                                 ig.Emit (OpCodes.Ldind_I);
 742                                 break;
 743                         default:
 744                                 switch (type.Kind) {
 745                                 case MemberKind.Struct:
 746                                 case MemberKind.TypeParameter:
 747                                         if (IsAnonymousStoreyMutateRequired)
 748                                                 type = CurrentAnonymousMethod.Storey.Mutator.Mutate (type);
 749
 750                                         ig.Emit (OpCodes.Ldobj, type.GetMetaInfo ());
 751                                         break;
 752                                 case MemberKind.PointerType:
 753                                         ig.Emit (OpCodes.Ldind_I);
 754                                         break;
 755                                 default:
 756                                         ig.Emit (OpCodes.Ldind_Ref);
 757                                         break;
 758                                 }
 759                                 break;
 760                         }
 761                 }
 762
 763                 public void EmitNull ()
 764                 {
 765                         ig.Emit (OpCodes.Ldnull);
 766                 }
 767
 768                 public void EmitArgumentAddress (int pos)
 769                 {
 770                         if (!IsStatic)
 771                                 ++pos;
 772
 773                         if (pos > byte.MaxValue)
 774                                 ig.Emit (OpCodes.Ldarga, pos);
 775                         else
 776                                 ig.Emit (OpCodes.Ldarga_S, (byte) pos);
 777                 }
 778
 779                 public void EmitArgumentLoad (int pos)
 780                 {
 781                         if (!IsStatic)
 782                                 ++pos;
 783
 784                         switch (pos) {
 785                         case 0: ig.Emit (OpCodes.Ldarg_0); break;
 786                         case 1: ig.Emit (OpCodes.Ldarg_1); break;
 787                         case 2: ig.Emit (OpCodes.Ldarg_2); break;
 788                         case 3: ig.Emit (OpCodes.Ldarg_3); break;
 789                         default:
 790                                 if (pos > byte.MaxValue)
 791                                         ig.Emit (OpCodes.Ldarg, pos);
 792                                 else
 793                                         ig.Emit (OpCodes.Ldarg_S, (byte) pos);
 794                                 break;
 795                         }
 796                 }
 797
 798                 public void EmitArgumentStore (int pos)
 799                 {
 800                         if (!IsStatic)
 801                                 ++pos;
 802
 803                         if (pos > byte.MaxValue)
 804                                 ig.Emit (OpCodes.Starg, pos);
 805                         else
 806                                 ig.Emit (OpCodes.Starg_S, (byte) pos);
 807                 }
 808
 809                 //
 810                 // The stack contains the pointer and the value of type `type'
 811                 //
 812                 public void EmitStoreFromPtr (TypeSpec type)
 813                 {
 814                         if (type.IsEnum)
 815                                 type = EnumSpec.GetUnderlyingType (type);
 816
 817                         switch (type.BuiltinType) {
 818                         case BuiltinTypeSpec.Type.Int:
 819                         case BuiltinTypeSpec.Type.UInt:
 820                                 ig.Emit (OpCodes.Stind_I4);
 821                                 return;
 822                         case BuiltinTypeSpec.Type.Long:
 823                         case BuiltinTypeSpec.Type.ULong:
 824                                 ig.Emit (OpCodes.Stind_I8);
 825                                 return;
 826                         case BuiltinTypeSpec.Type.Char:
 827                         case BuiltinTypeSpec.Type.Short:
 828                         case BuiltinTypeSpec.Type.UShort:
 829                                 ig.Emit (OpCodes.Stind_I2);
 830                                 return;
 831                         case BuiltinTypeSpec.Type.Float:
 832                                 ig.Emit (OpCodes.Stind_R4);
 833                                 return;
 834                         case BuiltinTypeSpec.Type.Double:
 835                                 ig.Emit (OpCodes.Stind_R8);
 836                                 return;
 837                         case BuiltinTypeSpec.Type.Byte:
 838                         case BuiltinTypeSpec.Type.SByte:
 839                         case BuiltinTypeSpec.Type.Bool:
 840                                 ig.Emit (OpCodes.Stind_I1);
 841                                 return;
 842                         case BuiltinTypeSpec.Type.IntPtr:
 843                                 ig.Emit (OpCodes.Stind_I);
 844                                 return;
 845                         }
 846
 847                         switch (type.Kind) {
 848                         case MemberKind.Struct:
 849                         case MemberKind.TypeParameter:
 850                                 if (IsAnonymousStoreyMutateRequired)
 851                                         type = CurrentAnonymousMethod.Storey.Mutator.Mutate (type);
 852
 853                                 ig.Emit (OpCodes.Stobj, type.GetMetaInfo ());
 854                                 break;
 855                         default:
 856                                 ig.Emit (OpCodes.Stind_Ref);
 857                                 break;
 858                         }
 859                 }
 860
 861                 public void EmitThis ()
 862                 {
 863                         ig.Emit (OpCodes.Ldarg_0);
 864                 }
 865
 866                 public void EmitEpilogue ()
 867                 {
 868                         if (epilogue_expressions == null)
 869                                 return;
 870
 871                         foreach (var e in epilogue_expressions)
 872                                 e.EmitCleanup (this);
 873
 874                         epilogue_expressions = null;
 875                 }
 876
 877                 /// <summary>
 878                 ///   Returns a temporary storage for a variable of type t as
 879                 ///   a local variable in the current body.
 880                 /// </summary>
 881                 public LocalBuilder GetTemporaryLocal (TypeSpec t)
 882                 {
 883                         if (temporary_storage != null) {
 884                                 object o;
 885                                 if (temporary_storage.TryGetValue (t, out o)) {
 886                                         if (o is Stack<LocalBuilder>) {
 887                                                 var s = (Stack<LocalBuilder>) o;
 888                                                 o = s.Count == 0 ? null : s.Pop ();
 889                                         } else {
 890                                                 temporary_storage.Remove (t);
 891                                         }
 892                                 }
 893                                 if (o != null)
 894                                         return (LocalBuilder) o;
 895                         }
 896                         return DeclareLocal (t, false);
 897                 }
 898
 899                 public void FreeTemporaryLocal (LocalBuilder b, TypeSpec t)
 900                 {
 901                         if (temporary_storage == null) {
 902                                 temporary_storage = new Dictionary<TypeSpec, object> (ReferenceEquality<TypeSpec>.Default);
 903                                 temporary_storage.Add (t, b);
 904                                 return;
 905                         }
 906                         object o;
 907
 908                         if (!temporary_storage.TryGetValue (t, out o)) {
 909                                 temporary_storage.Add (t, b);
 910                                 return;
 911                         }
 912                         var s = o as Stack<LocalBuilder>;
 913                         if (s == null) {
 914                                 s = new Stack<LocalBuilder> ();
 915                                 s.Push ((LocalBuilder)o);
 916                                 temporary_storage [t] = s;
 917                         }
 918                         s.Push (b);
 919                 }
 920
 921                 /// <summary>
 922                 ///   ReturnValue creates on demand the LocalBuilder for the
 923                 ///   return value from the function.  By default this is not
 924                 ///   used.  This is only required when returns are found inside
 925                 ///   Try or Catch statements.
 926                 ///
 927                 ///   This method is typically invoked from the Emit phase, so
 928                 ///   we allow the creation of a return label if it was not
 929                 ///   requested during the resolution phase.   Could be cleaned
 930                 ///   up, but it would replicate a lot of logic in the Emit phase
 931                 ///   of the code that uses it.
 932                 /// </summary>
 933                 public LocalBuilder TemporaryReturn ()
 934                 {
 935                         if (return_value == null){
 936                                 return_value = DeclareLocal (return_type, false);
 937                         }
 938
 939                         return return_value;
 940                 }
 941         }
 942
 943         struct CallEmitter
 944         {
 945                 public Expression InstanceExpression;
 946
 947                 //
 948                 // When set leaves an extra copy of all arguments on the stack
 949                 //
 950                 public bool DuplicateArguments;
 951
 952                 //
 953                 // Does not emit InstanceExpression load when InstanceExpressionOnStack
 954                 // is set. Used by compound assignments.
 955                 //
 956                 public bool InstanceExpressionOnStack;
 957
 958                 //
 959                 // Any of arguments contains await expression
 960                 //
 961                 public bool HasAwaitArguments;
 962
 963                 //
 964                 // When dealing with await arguments the original arguments are converted
 965                 // into a new set with hoisted stack results
 966                 //
 967                 public Arguments EmittedArguments;
 968
 969                 public void Emit (EmitContext ec, MethodSpec method, Arguments Arguments, Location loc)
 970                 {
 971                         EmitPredefined (ec, method, Arguments, loc);
 972                 }
 973
 974                 public void EmitPredefined (EmitContext ec, MethodSpec method, Arguments Arguments, Location? loc = null)
 975                 {
 976                         Expression instance_copy = null;
 977
 978                         if (!HasAwaitArguments && ec.HasSet (BuilderContext.Options.AsyncBody)) {
 979                                 HasAwaitArguments = Arguments != null && Arguments.ContainsEmitWithAwait ();
 980                                 if (HasAwaitArguments && InstanceExpressionOnStack) {
 981                                         throw new NotSupportedException ();
 982                                 }
 983                         }
 984
 985                         OpCode call_op;
 986                         LocalTemporary lt = null;
 987
 988                         if (method.IsStatic) {
 989                                 call_op = OpCodes.Call;
 990                         } else {
 991                                 if (IsVirtualCallRequired (InstanceExpression, method)) {
 992                                         call_op = OpCodes.Callvirt;
 993                                 } else {
 994                                         call_op = OpCodes.Call;
 995                                 }
 996
 997                                 if (HasAwaitArguments) {
 998                                         instance_copy = InstanceExpression.EmitToField (ec);
 999                                         if (Arguments == null)
1000                                                 EmitCallInstance (ec, instance_copy, method.DeclaringType, call_op);
1001                                 } else if (!InstanceExpressionOnStack) {
1002                                         var instance_on_stack_type = EmitCallInstance (ec, InstanceExpression, method.DeclaringType, call_op);
1003
1004                                         if (DuplicateArguments) {
1005                                                 ec.Emit (OpCodes.Dup);
1006                                                 if (Arguments != null && Arguments.Count != 0) {
1007                                                         lt = new LocalTemporary (instance_on_stack_type);
1008                                                         lt.Store (ec);
1009                                                         instance_copy = lt;
1010                                                 }
1011                                         }
1012                                 }
1013                         }
1014
1015                         if (Arguments != null && !InstanceExpressionOnStack) {
1016                                 EmittedArguments = Arguments.Emit (ec, DuplicateArguments, HasAwaitArguments);
1017                                 if (EmittedArguments != null) {
1018                                         if (instance_copy != null) {
1019                                                 EmitCallInstance (ec, instance_copy, method.DeclaringType, call_op);
1020
1021                                                 if (lt != null)
1022                                                         lt.Release (ec);
1023                                         }
1024
1025                                         EmittedArguments.Emit (ec);
1026                                 }
1027                         }
1028
1029                         if (call_op == OpCodes.Callvirt && (InstanceExpression.Type.IsGenericParameter || InstanceExpression.Type.IsStruct)) {
1030                                 ec.Emit (OpCodes.Constrained, InstanceExpression.Type);
1031                         }
1032
1033                         if (loc != null) {
1034                                 //
1035                                 // Emit explicit sequence point for expressions like Foo.Bar () to help debugger to
1036                                 // break at right place when LHS expression can be stepped-into
1037                                 //
1038                                 ec.MarkCallEntry (loc.Value);
1039                         }
1040
1041                         //
1042                         // Set instance expression to actual result expression. When it contains await it can be
1043                         // picked up by caller
1044                         //
1045                         InstanceExpression = instance_copy;
1046
1047                         if (method.Parameters.HasArglist) {
1048                                 var varargs_types = GetVarargsTypes (method, Arguments);
1049                                 ec.Emit (call_op, method, varargs_types);
1050                                 return;
1051                         }
1052
1053                         //
1054                         // If you have:
1055                         // this.DoFoo ();
1056                         // and DoFoo is not virtual, you can omit the callvirt,
1057                         // because you don't need the null checking behavior.
1058                         //
1059                         ec.Emit (call_op, method);
1060                 }
1061
1062                 static TypeSpec EmitCallInstance (EmitContext ec, Expression instance, TypeSpec declaringType, OpCode callOpcode)
1063                 {
1064                         var instance_type = instance.Type;
1065
1066                         //
1067                         // Push the instance expression
1068                         //
1069                         if ((instance_type.IsStruct && (callOpcode == OpCodes.Callvirt || (callOpcode == OpCodes.Call && declaringType.IsStruct))) ||
1070                                 instance_type.IsGenericParameter || declaringType.IsNullableType) {
1071                                 //
1072                                 // If the expression implements IMemoryLocation, then
1073                                 // we can optimize and use AddressOf on the
1074                                 // return.
1075                                 //
1076                                 // If not we have to use some temporary storage for
1077                                 // it.
1078                                 var iml = instance as IMemoryLocation;
1079                                 if (iml != null) {
1080                                         iml.AddressOf (ec, AddressOp.Load);
1081                                 } else {
1082                                         LocalTemporary temp = new LocalTemporary (instance_type);
1083                                         instance.Emit (ec);
1084                                         temp.Store (ec);
1085                                         temp.AddressOf (ec, AddressOp.Load);
1086                                 }
1087
1088                                 return ReferenceContainer.MakeType (ec.Module, instance_type);
1089                         }
1090
1091                         if (instance_type.IsEnum || instance_type.IsStruct) {
1092                                 instance.Emit (ec);
1093                                 ec.Emit (OpCodes.Box, instance_type);
1094                                 return ec.BuiltinTypes.Object;
1095                         }
1096
1097                         instance.Emit (ec);
1098                         return instance_type;
1099                 }
1100
1101                 static MetaType[] GetVarargsTypes (MethodSpec method, Arguments arguments)
1102                 {
1103                         AParametersCollection pd = method.Parameters;
1104
1105                         Argument a = arguments[pd.Count - 1];
1106                         Arglist list = (Arglist) a.Expr;
1107
1108                         return list.ArgumentTypes;
1109                 }
1110
1111                 //
1112                 // Used to decide whether call or callvirt is needed
1113                 //
1114                 static bool IsVirtualCallRequired (Expression instance, MethodSpec method)
1115                 {
1116                         //
1117                         // There are 2 scenarious where we emit callvirt
1118                         //
1119                         // Case 1: A method is virtual and it's not used to call base
1120                         // Case 2: A method instance expression can be null. In this casen callvirt ensures
1121                         // correct NRE exception when the method is called
1122                         //
1123                         var decl_type = method.DeclaringType;
1124                         if (decl_type.IsStruct || decl_type.IsEnum)
1125                                 return false;
1126
1127                         if (instance is BaseThis)
1128                                 return false;
1129
1130                         //
1131                         // It's non-virtual and will never be null and it can be determined
1132                         // whether it's known value or reference type by verifier
1133                         //
1134                         if (!method.IsVirtual && (instance is This || instance is New || instance is ArrayCreation || instance is DelegateCreation) &&
1135                                 !instance.Type.IsGenericParameter)
1136                                 return false;
1137
1138                         return true;
1139                 }
1140         }
1141 }