mcs/gmcs/codegen.cs

   1 //
   2 // codegen.cs: The code generator
   3 //
   4 // Author:
   5 //   Miguel de Icaza (miguel@ximian.com)
   6 //
   7 // (C) 2001 Ximian, Inc.
   8 //
   9
  10 using System;
  11 using System.IO;
  12 using System.Collections;
  13 using System.Reflection;
  14 using System.Reflection.Emit;
  15
  16 namespace Mono.CSharp {
  17
  18         /// <summary>
  19         ///    Code generator class.
  20         /// </summary>
  21         public class CodeGen {
  22                 static AppDomain current_domain;
  23                 public static AssemblyBuilder AssemblyBuilder;
  24                 public static ModuleBuilder   ModuleBuilder;
  25
  26                 static public SymbolWriter SymbolWriter;
  27
  28                 public static string Basename (string name)
  29                 {
  30                         int pos = name.LastIndexOf ('/');
  31
  32                         if (pos != -1)
  33                                 return name.Substring (pos + 1);
  34
  35                         pos = name.LastIndexOf ('\\');
  36                         if (pos != -1)
  37                                 return name.Substring (pos + 1);
  38
  39                         return name;
  40                 }
  41
  42                 public static string Dirname (string name)
  43                 {
  44                         int pos = name.LastIndexOf ('/');
  45
  46                         if (pos != -1)
  47                                 return name.Substring (0, pos);
  48
  49                         pos = name.LastIndexOf ('\\');
  50                         if (pos != -1)
  51                                 return name.Substring (0, pos);
  52
  53                         return ".";
  54                 }
  55
  56                 static string TrimExt (string name)
  57                 {
  58                         int pos = name.LastIndexOf ('.');
  59
  60                         return name.Substring (0, pos);
  61                 }
  62
  63                 static public string FileName;
  64
  65                 //
  66                 // Initializes the symbol writer
  67                 //
  68                 static void InitializeSymbolWriter ()
  69                 {
  70                         SymbolWriter = SymbolWriter.GetSymbolWriter (ModuleBuilder);
  71
  72                         //
  73                         // If we got an ISymbolWriter instance, initialize it.
  74                         //
  75                         if (SymbolWriter == null) {
  76                                 Report.Warning (
  77                                         -18, "Could not find the symbol writer assembly (Mono.CSharp.Debugger.dll). This is normally an installation problem. Please make sure to compile and install the mcs/class/Mono.CSharp.Debugger directory.");
  78                                 return;
  79                         }
  80                 }
  81
  82                 //
  83                 // Initializes the code generator variables
  84                 //
  85                 static public void Init (string name, string output, bool want_debugging_support)
  86                 {
  87                         AssemblyName an;
  88
  89                         FileName = output;
  90                         an = new AssemblyName ();
  91                         an.Name = Path.GetFileNameWithoutExtension (name);
  92
  93                         current_domain = AppDomain.CurrentDomain;
  94                         AssemblyBuilder = current_domain.DefineDynamicAssembly (
  95                                 an, AssemblyBuilderAccess.Save, Dirname (name));
  96
  97                         //
  98                         // Pass a path-less name to DefineDynamicModule.  Wonder how
  99                         // this copes with output in different directories then.
 100                         // FIXME: figure out how this copes with --output /tmp/blah
 101                         //
 102                         // If the third argument is true, the ModuleBuilder will dynamically
 103                         // load the default symbol writer.
 104                         //
 105                         ModuleBuilder = AssemblyBuilder.DefineDynamicModule (
 106                                 Basename (name), Basename (output), want_debugging_support);
 107
 108                         if (want_debugging_support)
 109                                 InitializeSymbolWriter ();
 110                 }
 111
 112                 static public void Save (string name)
 113                 {
 114                         try {
 115                                 AssemblyBuilder.Save (Basename (name));
 116                         } catch (System.IO.IOException io){
 117                                 Report.Error (16, "Could not write to file `"+name+"', cause: " + io.Message);
 118                         }
 119                 }
 120         }
 121
 122         //
 123         // Provides "local" store across code that can yield: locals
 124         // or fields, notice that this should not be used by anonymous
 125         // methods to create local storage, those only require
 126         // variable mapping.
 127         //
 128         public class VariableStorage {
 129                 ILGenerator ig;
 130                 FieldBuilder fb;
 131                 LocalBuilder local;
 132
 133                 static int count;
 134
 135                 public VariableStorage (EmitContext ec, Type t)
 136                 {
 137                         count++;
 138                         if (ec.InIterator)
 139                                 fb = IteratorHandler.Current.MapVariable ("s_", count.ToString (), t);
 140                         else
 141                                 local = ec.ig.DeclareLocal (t);
 142                         ig = ec.ig;
 143                 }
 144
 145                 public void EmitThis ()
 146                 {
 147                         if (fb != null)
 148                                 ig.Emit (OpCodes.Ldarg_0);
 149                 }
 150
 151                 public void EmitStore ()
 152                 {
 153                         if (fb == null)
 154                                 ig.Emit (OpCodes.Stloc, local);
 155                         else
 156                                 ig.Emit (OpCodes.Stfld, fb);
 157                 }
 158
 159                 public void EmitLoad ()
 160                 {
 161                         if (fb == null)
 162                                 ig.Emit (OpCodes.Ldloc, local);
 163                         else
 164                                 ig.Emit (OpCodes.Ldfld, fb);
 165                 }
 166         }
 167
 168         /// <summary>
 169         ///   An Emit Context is created for each body of code (from methods,
 170         ///   properties bodies, indexer bodies or constructor bodies)
 171         /// </summary>
 172         public class EmitContext {
 173                 public DeclSpace DeclSpace;
 174                 public DeclSpace TypeContainer;
 175                 public ILGenerator   ig;
 176
 177                 /// <summary>
 178                 ///   This variable tracks the `checked' state of the compilation,
 179                 ///   it controls whether we should generate code that does overflow
 180                 ///   checking, or if we generate code that ignores overflows.
 181                 ///
 182                 ///   The default setting comes from the command line option to generate
 183                 ///   checked or unchecked code plus any source code changes using the
 184                 ///   checked/unchecked statements or expressions.   Contrast this with
 185                 ///   the ConstantCheckState flag.
 186                 /// </summary>
 187
 188                 public bool CheckState;
 189
 190                 /// <summary>
 191                 ///   The constant check state is always set to `true' and cant be changed
 192                 ///   from the command line.  The source code can change this setting with
 193                 ///   the `checked' and `unchecked' statements and expressions.
 194                 /// </summary>
 195                 public bool ConstantCheckState;
 196
 197                 /// <summary>
 198                 ///   Whether we are emitting code inside a static or instance method
 199                 /// </summary>
 200                 public bool IsStatic;
 201
 202                 /// <summary>
 203                 ///   Whether we are emitting a field initializer
 204                 /// </summary>
 205                 public bool IsFieldInitializer;
 206
 207                 /// <summary>
 208                 ///   The value that is allowed to be returned or NULL if there is no
 209                 ///   return type.
 210                 /// </summary>
 211                 public Type ReturnType;
 212
 213                 /// <summary>
 214                 ///   Points to the Type (extracted from the TypeContainer) that
 215                 ///   declares this body of code
 216                 /// </summary>
 217                 public Type ContainerType;
 218
 219                 /// <summary>
 220                 ///   Whether this is generating code for a constructor
 221                 /// </summary>
 222                 public bool IsConstructor;
 223
 224                 /// <summary>
 225                 ///   Whether we're control flow analysis enabled
 226                 /// </summary>
 227                 public bool DoFlowAnalysis;
 228
 229                 /// <summary>
 230                 ///   Keeps track of the Type to LocalBuilder temporary storage created
 231                 ///   to store structures (used to compute the address of the structure
 232                 ///   value on structure method invocations)
 233                 /// </summary>
 234                 public Hashtable temporary_storage;
 235
 236                 public Block CurrentBlock;
 237
 238                 public int CurrentFile;
 239
 240                 /// <summary>
 241                 ///   The location where we store the return value.
 242                 /// </summary>
 243                 LocalBuilder return_value;
 244
 245                 /// <summary>
 246                 ///   The location where return has to jump to return the
 247                 ///   value
 248                 /// </summary>
 249                 public Label ReturnLabel;
 250
 251                 /// <summary>
 252                 ///   If we already defined the ReturnLabel
 253                 /// </summary>
 254                 public bool HasReturnLabel;
 255
 256                 /// <summary>
 257                 ///   Whether we are inside an iterator block.
 258                 /// </summary>
 259                 public bool InIterator;
 260
 261                 public bool IsLastStatement;
 262
 263                 /// <summary>
 264                 ///   Whether remapping of locals, parameters and fields is turned on.
 265                 ///   Used by iterators and anonymous methods.
 266                 /// </summary>
 267                 public bool RemapToProxy;
 268
 269                 /// <summary>
 270                 ///  Whether we are inside an unsafe block
 271                 /// </summary>
 272                 public bool InUnsafe;
 273
 274                 /// <summary>
 275                 ///  Whether we are in a `fixed' initialization
 276                 /// </summary>
 277                 public bool InFixedInitializer;
 278
 279                 /// <summary>
 280                 ///  Whether we are inside an anonymous method.
 281                 /// </summary>
 282                 public bool InAnonymousMethod;
 283
 284                 /// <summary>
 285                 ///   Location for this EmitContext
 286                 /// </summary>
 287                 public Location loc;
 288
 289                 /// <summary>
 290                 ///   Used to flag that it is ok to define types recursively, as the
 291                 ///   expressions are being evaluated as part of the type lookup
 292                 ///   during the type resolution process
 293                 /// </summary>
 294                 public bool ResolvingTypeTree;
 295
 296                 /// <summary>
 297                 ///   Inside an enum definition, we do not resolve enumeration values
 298                 ///   to their enumerations, but rather to the underlying type/value
 299                 ///   This is so EnumVal + EnumValB can be evaluated.
 300                 ///
 301                 ///   There is no "E operator + (E x, E y)", so during an enum evaluation
 302                 ///   we relax the rules
 303                 /// </summary>
 304                 public bool InEnumContext;
 305
 306                 FlowBranching current_flow_branching;
 307
 308                 public EmitContext (DeclSpace parent, DeclSpace ds, Location l, ILGenerator ig,
 309                                     Type return_type, int code_flags, bool is_constructor)
 310                 {
 311                         this.ig = ig;
 312
 313                         TypeContainer = parent;
 314                         DeclSpace = ds;
 315                         CheckState = RootContext.Checked;
 316                         ConstantCheckState = true;
 317
 318                         IsStatic = (code_flags & Modifiers.STATIC) != 0;
 319                         InIterator = (code_flags & Modifiers.METHOD_YIELDS) != 0;
 320                         RemapToProxy = InIterator;
 321                         ReturnType = return_type;
 322                         IsConstructor = is_constructor;
 323                         CurrentBlock = null;
 324                         CurrentFile = 0;
 325
 326                         if (parent != null){
 327                                 // Can only be null for the ResolveType contexts.
 328                                 ContainerType = parent.TypeBuilder;
 329                                 if (parent.UnsafeContext)
 330                                         InUnsafe = true;
 331                                 else
 332                                         InUnsafe = (code_flags & Modifiers.UNSAFE) != 0;
 333                         }
 334                         loc = l;
 335
 336                         if (ReturnType == TypeManager.void_type)
 337                                 ReturnType = null;
 338                 }
 339
 340                 public EmitContext (TypeContainer tc, Location l, ILGenerator ig,
 341                                     Type return_type, int code_flags, bool is_constructor)
 342                         : this (tc, tc, l, ig, return_type, code_flags, is_constructor)
 343                 {
 344                 }
 345
 346                 public EmitContext (TypeContainer tc, Location l, ILGenerator ig,
 347                                     Type return_type, int code_flags)
 348                         : this (tc, tc, l, ig, return_type, code_flags, false)
 349                 {
 350                 }
 351
 352                 public FlowBranching CurrentBranching {
 353                         get {
 354                                 return current_flow_branching;
 355                         }
 356                 }
 357
 358                 // <summary>
 359                 //   Starts a new code branching.  This inherits the state of all local
 360                 //   variables and parameters from the current branching.
 361                 // </summary>
 362                 public FlowBranching StartFlowBranching (FlowBranching.BranchingType type, Location loc)
 363                 {
 364                         current_flow_branching = FlowBranching.CreateBranching (CurrentBranching, type, null, loc);
 365                         return current_flow_branching;
 366                 }
 367
 368                 // <summary>
 369                 //   Starts a new code branching for block `block'.
 370                 // </summary>
 371                 public FlowBranching StartFlowBranching (Block block)
 372                 {
 373                         FlowBranching.BranchingType type;
 374
 375                         if (CurrentBranching.Type == FlowBranching.BranchingType.Switch)
 376                                 type = FlowBranching.BranchingType.SwitchSection;
 377                         else
 378                                 type = FlowBranching.BranchingType.Block;
 379
 380                         current_flow_branching = FlowBranching.CreateBranching (CurrentBranching, type, block, block.StartLocation);
 381                         return current_flow_branching;
 382                 }
 383
 384                 // <summary>
 385                 //   Ends a code branching.  Merges the state of locals and parameters
 386                 //   from all the children of the ending branching.
 387                 // </summary>
 388                 public FlowBranching.UsageVector DoEndFlowBranching ()
 389                 {
 390                         FlowBranching old = current_flow_branching;
 391                         current_flow_branching = current_flow_branching.Parent;
 392
 393                         return current_flow_branching.MergeChild (old);
 394                 }
 395
 396                 // <summary>
 397                 //   Ends a code branching.  Merges the state of locals and parameters
 398                 //   from all the children of the ending branching.
 399                 // </summary>
 400                 public FlowBranching.Reachability EndFlowBranching ()
 401                 {
 402                         FlowBranching.UsageVector vector = DoEndFlowBranching ();
 403
 404                         return vector.Reachability;
 405                 }
 406
 407                 // <summary>
 408                 //   Kills the current code branching.  This throws away any changed state
 409                 //   information and should only be used in case of an error.
 410                 // </summary>
 411                 public void KillFlowBranching ()
 412                 {
 413                         current_flow_branching = current_flow_branching.Parent;
 414                 }
 415
 416                 public void EmitTopBlock (Block block, InternalParameters ip, Location loc)
 417                 {
 418                         bool unreachable = false;
 419
 420                         if (!Location.IsNull (loc))
 421                                 CurrentFile = loc.File;
 422
 423                         if (block != null){
 424                             try {
 425                                 int errors = Report.Errors;
 426
 427                                 block.EmitMeta (this, ip);
 428
 429                                 if (Report.Errors == errors){
 430                                         bool old_do_flow_analysis = DoFlowAnalysis;
 431                                         DoFlowAnalysis = true;
 432
 433                                         current_flow_branching = FlowBranching.CreateBranching (
 434                                                 null, FlowBranching.BranchingType.Block, block, loc);
 435
 436                                         if (!block.Resolve (this)) {
 437                                                 current_flow_branching = null;
 438                                                 DoFlowAnalysis = old_do_flow_analysis;
 439                                                 return;
 440                                         }
 441
 442                                         FlowBranching.Reachability reachability = current_flow_branching.MergeTopBlock ();
 443                                         current_flow_branching = null;
 444
 445                                         DoFlowAnalysis = old_do_flow_analysis;
 446
 447                                         block.Emit (this);
 448
 449                                         if (reachability.AlwaysReturns ||
 450                                             reachability.AlwaysThrows ||
 451                                             reachability.IsUnreachable)
 452                                                 unreachable = true;
 453                                         }
 454                             } catch (Exception e) {
 455                                         Console.WriteLine ("Exception caught by the compiler while compiling:");
 456                                         Console.WriteLine ("   Block that caused the problem begin at: " + loc);
 457
 458                                         if (CurrentBlock != null){
 459                                                 Console.WriteLine ("                     Block being compiled: [{0},{1}]",
 460                                                                    CurrentBlock.StartLocation, CurrentBlock.EndLocation);
 461                                         }
 462                                         Console.WriteLine (e.GetType ().FullName + ": " + e.Message);
 463                                         Console.WriteLine (Report.FriendlyStackTrace (e));
 464
 465                                         Environment.Exit (1);
 466                             }
 467                         }
 468
 469                         if (ReturnType != null && !unreachable){
 470                                 if (!InIterator){
 471                                         Report.Error (161, loc, "Not all code paths return a value");
 472                                         return;
 473                                 }
 474                         }
 475
 476                         if (HasReturnLabel)
 477                                 ig.MarkLabel (ReturnLabel);
 478                         if (return_value != null){
 479                                 ig.Emit (OpCodes.Ldloc, return_value);
 480                                 ig.Emit (OpCodes.Ret);
 481                         } else {
 482                                 //
 483                                 // If `HasReturnLabel' is set, then we already emitted a
 484                                 // jump to the end of the method, so we must emit a `ret'
 485                                 // there.
 486                                 //
 487                                 // Unfortunately, System.Reflection.Emit automatically emits
 488                                 // a leave to the end of a finally block.  This is a problem
 489                                 // if no code is following the try/finally block since we may
 490                                 // jump to a point after the end of the method.
 491                                 // As a workaround, we're always creating a return label in
 492                                 // this case.
 493                                 //
 494
 495                                 if ((block != null) && block.IsDestructor) {
 496                                         // Nothing to do; S.R.E automatically emits a leave.
 497                                 } else if (HasReturnLabel || (!unreachable && !InIterator)) {
 498                                         if (ReturnType != null)
 499                                                 ig.Emit (OpCodes.Ldloc, TemporaryReturn ());
 500                                         ig.Emit (OpCodes.Ret);
 501                                 }
 502                         }
 503                 }
 504
 505                 /// <summary>
 506                 ///   This is called immediately before emitting an IL opcode to tell the symbol
 507                 ///   writer to which source line this opcode belongs.
 508                 /// </summary>
 509                 public void Mark (Location loc, bool check_file)
 510                 {
 511                         if ((CodeGen.SymbolWriter == null) || Location.IsNull (loc))
 512                                 return;
 513
 514                         if (check_file && (CurrentFile != loc.File))
 515                                 return;
 516
 517                         ig.MarkSequencePoint (null, loc.Row, 0, 0, 0);
 518                 }
 519
 520                 /// <summary>
 521                 ///   Returns a temporary storage for a variable of type t as
 522                 ///   a local variable in the current body.
 523                 /// </summary>
 524                 public LocalBuilder GetTemporaryLocal (Type t)
 525                 {
 526                         LocalBuilder location = null;
 527
 528                         if (temporary_storage != null){
 529                                 object o = temporary_storage [t];
 530                                 if (o != null){
 531                                         if (o is ArrayList){
 532                                                 ArrayList al = (ArrayList) o;
 533
 534                                                 for (int i = 0; i < al.Count; i++){
 535                                                         if (al [i] != null){
 536                                                                 location = (LocalBuilder) al [i];
 537                                                                 al [i] = null;
 538                                                                 break;
 539                                                         }
 540                                                 }
 541                                         } else
 542                                                 location = (LocalBuilder) o;
 543                                         if (location != null)
 544                                                 return location;
 545                                 }
 546                         }
 547
 548                         return ig.DeclareLocal (t);
 549                 }
 550
 551                 public void FreeTemporaryLocal (LocalBuilder b, Type t)
 552                 {
 553                         if (temporary_storage == null){
 554                                 temporary_storage = new Hashtable ();
 555                                 temporary_storage [t] = b;
 556                                 return;
 557                         }
 558                         object o = temporary_storage [t];
 559                         if (o == null){
 560                                 temporary_storage [t] = b;
 561                                 return;
 562                         }
 563                         if (o is ArrayList){
 564                                 ArrayList al = (ArrayList) o;
 565                                 for (int i = 0; i < al.Count; i++){
 566                                         if (al [i] == null){
 567                                                 al [i] = b;
 568                                                 return;
 569                                         }
 570                                 }
 571                                 al.Add (b);
 572                                 return;
 573                         }
 574                         ArrayList replacement = new ArrayList ();
 575                         replacement.Add (o);
 576                         temporary_storage.Remove (t);
 577                         temporary_storage [t] = replacement;
 578                 }
 579
 580                 /// <summary>
 581                 ///   Current loop begin and end labels.
 582                 /// </summary>
 583                 public Label LoopBegin, LoopEnd;
 584
 585                 /// <summary>
 586                 ///   Default target in a switch statement.   Only valid if
 587                 ///   InSwitch is true
 588                 /// </summary>
 589                 public Label DefaultTarget;
 590
 591                 /// <summary>
 592                 ///   If this is non-null, points to the current switch statement
 593                 /// </summary>
 594                 public Switch Switch;
 595
 596                 /// <summary>
 597                 ///   ReturnValue creates on demand the LocalBuilder for the
 598                 ///   return value from the function.  By default this is not
 599                 ///   used.  This is only required when returns are found inside
 600                 ///   Try or Catch statements.
 601                 /// </summary>
 602                 public LocalBuilder TemporaryReturn ()
 603                 {
 604                         if (return_value == null){
 605                                 return_value = ig.DeclareLocal (ReturnType);
 606                                 ReturnLabel = ig.DefineLabel ();
 607                                 HasReturnLabel = true;
 608                         }
 609
 610                         return return_value;
 611                 }
 612
 613                 public void NeedReturnLabel ()
 614                 {
 615                         if (!HasReturnLabel) {
 616                                 ReturnLabel = ig.DefineLabel ();
 617                                 HasReturnLabel = true;
 618                         }
 619                 }
 620
 621                 //
 622                 // Creates a field `name' with the type `t' on the proxy class
 623                 //
 624                 public FieldBuilder MapVariable (string name, Type t)
 625                 {
 626                         if (InIterator){
 627                                 return IteratorHandler.Current.MapVariable ("v_", name, t);
 628                         }
 629
 630                         throw new Exception ("MapVariable for an unknown state");
 631                 }
 632
 633                 //
 634                 // Invoke this routine to remap a VariableInfo into the
 635                 // proper MemberAccess expression
 636                 //
 637                 public Expression RemapLocal (LocalInfo local_info)
 638                 {
 639                         FieldExpr fe = new FieldExpr (local_info.FieldBuilder, loc);
 640                         fe.InstanceExpression = new ProxyInstance ();
 641                         return fe.DoResolve (this);
 642                 }
 643
 644                 public Expression RemapLocalLValue (LocalInfo local_info, Expression right_side)
 645                 {
 646                         FieldExpr fe = new FieldExpr (local_info.FieldBuilder, loc);
 647                         fe.InstanceExpression = new ProxyInstance ();
 648                         return fe.DoResolveLValue (this, right_side);
 649                 }
 650
 651                 public Expression RemapParameter (int idx)
 652                 {
 653                         FieldExpr fe = new FieldExprNoAddress (IteratorHandler.Current.parameter_fields [idx], loc);
 654                         fe.InstanceExpression = new ProxyInstance ();
 655                         return fe.DoResolve (this);
 656                 }
 657
 658                 public Expression RemapParameterLValue (int idx, Expression right_side)
 659                 {
 660                         FieldExpr fe = new FieldExprNoAddress (IteratorHandler.Current.parameter_fields [idx], loc);
 661                         fe.InstanceExpression = new ProxyInstance ();
 662                         return fe.DoResolveLValue (this, right_side);
 663                 }
 664
 665                 //
 666                 // Emits the proper object to address fields on a remapped
 667                 // variable/parameter to field in anonymous-method/iterator proxy classes.
 668                 //
 669                 public void EmitThis ()
 670                 {
 671                         ig.Emit (OpCodes.Ldarg_0);
 672
 673                         if (!IsStatic){
 674                                 if (InIterator)
 675                                         ig.Emit (OpCodes.Ldfld, IteratorHandler.Current.this_field);
 676                                 else
 677                                         throw new Exception ("EmitThis for an unknown state");
 678                         }
 679                 }
 680
 681                 public Expression GetThis (Location loc)
 682                 {
 683                         This my_this;
 684                         if (CurrentBlock != null)
 685                                 my_this = new This (CurrentBlock, loc);
 686                         else
 687                                 my_this = new This (loc);
 688
 689                         if (!my_this.ResolveBase (this))
 690                                 my_this = null;
 691
 692                         return my_this;
 693                 }
 694         }
 695 }