mcs/mcs/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 using System.Diagnostics.SymbolStore;
  16
  17 namespace Mono.CSharp {
  18
  19         /// <summary>
  20         ///    Code generator class.
  21         /// </summary>
  22         public class CodeGen {
  23                 static AppDomain current_domain;
  24                 public static AssemblyBuilder AssemblyBuilder;
  25                 public static ModuleBuilder   ModuleBuilder;
  26
  27                 static public ISymbolWriter SymbolWriter;
  28
  29                 public static string Basename (string name)
  30                 {
  31                         int pos = name.LastIndexOf ("/");
  32
  33                         if (pos != -1)
  34                                 return name.Substring (pos + 1);
  35
  36                         pos = name.LastIndexOf ("\\");
  37                         if (pos != -1)
  38                                 return name.Substring (pos + 1);
  39
  40                         return name;
  41                 }
  42
  43                 public static string Dirname (string name)
  44                 {
  45                         int pos = name.LastIndexOf ("/");
  46
  47                         if (pos != -1)
  48                                 return name.Substring (0, pos);
  49
  50                         pos = name.LastIndexOf ("\\");
  51                         if (pos != -1)
  52                                 return name.Substring (0, pos);
  53
  54                         return ".";
  55                 }
  56
  57                 static string TrimExt (string name)
  58                 {
  59                         int pos = name.LastIndexOf (".");
  60
  61                         return name.Substring (0, pos);
  62                 }
  63
  64                 static public string FileName;
  65
  66                 //
  67                 // This routine initializes the Mono runtime SymbolWriter.
  68                 //
  69                 static bool InitMonoSymbolWriter (string basename, string symbol_output,
  70                                                   string exe_output_file, string[] debug_args)
  71                 {
  72                         Type itype = SymbolWriter.GetType ();
  73                         if (itype == null)
  74                                 return false;
  75
  76                         Type[] arg_types = new Type [3];
  77                         arg_types [0] = typeof (string);
  78                         arg_types [1] = typeof (string);
  79                         arg_types [2] = typeof (string[]);
  80
  81                         MethodInfo initialize = itype.GetMethod ("Initialize", arg_types);
  82                         if (initialize == null)
  83                                 return false;
  84
  85                         object[] args = new object [3];
  86                         args [0] = exe_output_file;
  87                         args [1] = symbol_output;
  88                         args [2] = debug_args;
  89
  90                         initialize.Invoke (SymbolWriter, args);
  91                         return true;
  92                 }
  93
  94                 //
  95                 // Initializes the symbol writer
  96                 //
  97                 static void InitializeSymbolWriter (string basename, string symbol_output,
  98                                                     string exe_output_file, string[] args)
  99                 {
 100                         SymbolWriter = ModuleBuilder.GetSymWriter ();
 101
 102                         //
 103                         // If we got an ISymbolWriter instance, initialize it.
 104                         //
 105                         if (SymbolWriter == null) {
 106                                 Report.Error (
 107                                         -18, "Cannot find any symbol writer");
 108                                 return;
 109                         }
 110
 111                         //
 112                         // Due to lacking documentation about the first argument of the
 113                         // Initialize method, we cannot use Microsoft's default symbol
 114                         // writer yet.
 115                         //
 116                         // If we're using the mono symbol writer, the SymbolWriter object
 117                         // is of type MonoSymbolWriter - but that's defined in a dynamically
 118                         // loaded DLL - that's why we're doing a comparision based on the type
 119                         // name here instead of using `SymbolWriter is MonoSymbolWriter'.
 120                         //
 121                         Type sym_type = ((object) SymbolWriter).GetType ();
 122
 123                         switch (sym_type.Name){
 124                         case "MonoSymbolWriter":
 125                                 if (!InitMonoSymbolWriter (basename, symbol_output,
 126                                                            exe_output_file, args))
 127                                         Report.Error (
 128                                                 -18, "Cannot initialize the symbol writer");
 129                                 break;
 130
 131                         default:
 132                                 Report.Error (
 133                                         -18, "Cannot generate debugging information on this platform");
 134                                 break;
 135                         }
 136                 }
 137
 138                 //
 139                 // Initializes the code generator variables
 140                 //
 141                 static public void Init (string name, string output, bool want_debugging_support,
 142                                          string[] debug_args)
 143                 {
 144                         AssemblyName an;
 145
 146                         FileName = output;
 147                         an = new AssemblyName ();
 148                         an.Name = TrimExt (Basename (name));
 149                         current_domain = AppDomain.CurrentDomain;
 150                         AssemblyBuilder = current_domain.DefineDynamicAssembly (
 151                                 an, AssemblyBuilderAccess.RunAndSave, Dirname (name));
 152
 153                         //
 154                         // Pass a path-less name to DefineDynamicModule.  Wonder how
 155                         // this copes with output in different directories then.
 156                         // FIXME: figure out how this copes with --output /tmp/blah
 157                         //
 158                         // If the third argument is true, the ModuleBuilder will dynamically
 159                         // load the default symbol writer.
 160                         //
 161                         ModuleBuilder = AssemblyBuilder.DefineDynamicModule (
 162                                 Basename (name), Basename (output), want_debugging_support);
 163
 164                         int pos = output.LastIndexOf (".");
 165
 166                         string basename;
 167                         if (pos > 0)
 168                                 basename = output.Substring (0, pos);
 169                         else
 170                                 basename = output;
 171
 172                         string symbol_output = basename + ".dbg";
 173
 174                         if (want_debugging_support)
 175                                 InitializeSymbolWriter (basename, symbol_output, output, debug_args);
 176                         else {
 177                                 try {
 178                                         File.Delete (symbol_output);
 179                                 } catch {
 180                                         // Ignore errors.
 181                                 }
 182                         }
 183                 }
 184
 185                 static public void Save (string name)
 186                 {
 187                         try {
 188                                 AssemblyBuilder.Save (Basename (name));
 189                         } catch (System.IO.IOException io){
 190                                 Report.Error (16, "Coult not write to file `"+name+"', cause: " + io.Message);
 191                         }
 192                 }
 193
 194                 static public void SaveSymbols ()
 195                 {
 196                         if (SymbolWriter != null) {
 197                                 // If we have a symbol writer, call its Close() method to write
 198                                 // the symbol file to disk.
 199                                 //
 200                                 // When using Mono's default symbol writer, the Close() method must
 201                                 // be called after the assembly has already been written to disk since
 202                                 // it opens the assembly and reads its metadata.
 203                                 SymbolWriter.Close ();
 204                         }
 205                 }
 206         }
 207
 208         /// <summary>
 209         ///   An Emit Context is created for each body of code (from methods,
 210         ///   properties bodies, indexer bodies or constructor bodies)
 211         /// </summary>
 212         public class EmitContext {
 213                 public DeclSpace DeclSpace;
 214                 public TypeContainer TypeContainer;
 215                 public ILGenerator   ig;
 216
 217                 /// <summary>
 218                 ///   This variable tracks the `checked' state of the compilation,
 219                 ///   it controls whether we should generate code that does overflow
 220                 ///   checking, or if we generate code that ignores overflows.
 221                 ///
 222                 ///   The default setting comes from the command line option to generate
 223                 ///   checked or unchecked code plus any source code changes using the
 224                 ///   checked/unchecked statements or expressions.   Contrast this with
 225                 ///   the ConstantCheckState flag.
 226                 /// </summary>
 227
 228                 public bool CheckState;
 229
 230                 /// <summary>
 231                 ///   The constant check state is always set to `true' and cant be changed
 232                 ///   from the command line.  The source code can change this setting with
 233                 ///   the `checked' and `unchecked' statements and expressions.
 234                 /// </summary>
 235                 public bool ConstantCheckState;
 236
 237                 /// <summary>
 238                 ///   Whether we are emitting code inside a static or instance method
 239                 /// </summary>
 240                 public bool IsStatic;
 241
 242                 /// <summary>
 243                 ///   Whether we are emitting a field initializer
 244                 /// </summary>
 245                 public bool IsFieldInitializer;
 246
 247                 /// <summary>
 248                 ///   The value that is allowed to be returned or NULL if there is no
 249                 ///   return type.
 250                 /// </summary>
 251                 public Type ReturnType;
 252
 253                 /// <summary>
 254                 ///   Points to the Type (extracted from the TypeContainer) that
 255                 ///   declares this body of code
 256                 /// </summary>
 257                 public Type ContainerType;
 258
 259                 /// <summary>
 260                 ///   Whether this is generating code for a constructor
 261                 /// </summary>
 262                 public bool IsConstructor;
 263
 264                 /// <summary>
 265                 ///   Whether we're control flow analysis enabled
 266                 /// </summary>
 267                 public bool DoFlowAnalysis;
 268
 269                 /// <summary>
 270                 ///   Keeps track of the Type to LocalBuilder temporary storage created
 271                 ///   to store structures (used to compute the address of the structure
 272                 ///   value on structure method invocations)
 273                 /// </summary>
 274                 public Hashtable temporary_storage;
 275
 276                 public Block CurrentBlock;
 277
 278                 /// <summary>
 279                 ///   The location where we store the return value.
 280                 /// </summary>
 281                 LocalBuilder return_value;
 282
 283                 /// <summary>
 284                 ///   The location where return has to jump to return the
 285                 ///   value
 286                 /// </summary>
 287                 public Label ReturnLabel;
 288
 289                 /// <summary>
 290                 ///   If we already defined the ReturnLabel
 291                 /// </summary>
 292                 public bool HasReturnLabel;
 293
 294                 /// <summary>
 295                 ///   Whether we are in a Finally block
 296                 /// </summary>
 297                 public bool InFinally;
 298
 299                 /// <summary>
 300                 ///   Whether we are in a Try block
 301                 /// </summary>
 302                 public bool InTry;
 303
 304                 /// <summary>
 305                 ///   Whether we are in a Catch block
 306                 /// </summary>
 307                 public bool InCatch;
 308
 309                 /// <summary>
 310                 ///  Whether we are inside an unsafe block
 311                 /// </summary>
 312                 public bool InUnsafe;
 313
 314                 /// <summary>
 315                 ///   Whether we break from a loop or not
 316                 /// </summary>
 317                 public bool Breaks;
 318
 319                 /// <summary>
 320                 ///   Location for this EmitContext
 321                 /// </summary>
 322                 public Location loc;
 323
 324                 /// <summary>
 325                 ///   Used to flag that it is ok to define types recursively, as the
 326                 ///   expressions are being evaluated as part of the type lookup
 327                 ///   during the type resolution process
 328                 /// </summary>
 329                 public bool ResolvingTypeTree;
 330
 331                 /// <summary>
 332                 ///   Inside an enum definition, we do not resolve enumeration values
 333                 ///   to their enumerations, but rather to the underlying type/value
 334                 ///   This is so EnumVal + EnumValB can be evaluated.
 335                 ///
 336                 ///   There is no "E operator + (E x, E y)", so during an enum evaluation
 337                 ///   we relax the rules
 338                 /// </summary>
 339                 public bool InEnumContext;
 340
 341                 protected Stack FlowStack;
 342
 343                 public EmitContext (TypeContainer parent, DeclSpace ds, Location l, ILGenerator ig,
 344                                     Type return_type, int code_flags, bool is_constructor)
 345                 {
 346                         this.ig = ig;
 347
 348                         TypeContainer = parent;
 349                         DeclSpace = ds;
 350                         CheckState = RootContext.Checked;
 351                         ConstantCheckState = true;
 352
 353                         IsStatic = (code_flags & Modifiers.STATIC) != 0;
 354                         ReturnType = return_type;
 355                         IsConstructor = is_constructor;
 356                         CurrentBlock = null;
 357
 358                         if (parent != null){
 359                                 // Can only be null for the ResolveType contexts.
 360                                 ContainerType = parent.TypeBuilder;
 361                                 if (parent.UnsafeContext)
 362                                         InUnsafe = true;
 363                                 else
 364                                         InUnsafe = (code_flags & Modifiers.UNSAFE) != 0;
 365                         }
 366                         loc = l;
 367
 368                         FlowStack = new Stack ();
 369
 370                         if (ReturnType == TypeManager.void_type)
 371                                 ReturnType = null;
 372                 }
 373
 374                 public EmitContext (TypeContainer tc, Location l, ILGenerator ig,
 375                                     Type return_type, int code_flags, bool is_constructor)
 376                         : this (tc, tc, l, ig, return_type, code_flags, is_constructor)
 377                 {
 378                 }
 379
 380                 public EmitContext (TypeContainer tc, Location l, ILGenerator ig,
 381                                     Type return_type, int code_flags)
 382                         : this (tc, tc, l, ig, return_type, code_flags, false)
 383                 {
 384                 }
 385
 386                 public FlowBranching CurrentBranching {
 387                         get {
 388                                 return (FlowBranching) FlowStack.Peek ();
 389                         }
 390                 }
 391
 392                 // <summary>
 393                 //   Starts a new code branching.  This inherits the state of all local
 394                 //   variables and parameters from the current branching.
 395                 // </summary>
 396                 public FlowBranching StartFlowBranching (FlowBranchingType type, Location loc)
 397                 {
 398                         FlowBranching cfb = new FlowBranching (CurrentBranching, type, null, loc);
 399
 400                         FlowStack.Push (cfb);
 401
 402                         return cfb;
 403                 }
 404
 405                 // <summary>
 406                 //   Starts a new code branching for block `block'.
 407                 // </summary>
 408                 public FlowBranching StartFlowBranching (Block block)
 409                 {
 410                         FlowBranching cfb;
 411                         FlowBranchingType type;
 412
 413                         if (CurrentBranching.Type == FlowBranchingType.SWITCH)
 414                                 type = FlowBranchingType.SWITCH_SECTION;
 415                         else
 416                                 type = FlowBranchingType.BLOCK;
 417
 418                         cfb = new FlowBranching (CurrentBranching, type, block, block.StartLocation);
 419
 420                         FlowStack.Push (cfb);
 421
 422                         return cfb;
 423                 }
 424
 425                 // <summary>
 426                 //   Ends a code branching.  Merges the state of locals and parameters
 427                 //   from all the children of the ending branching.
 428                 // </summary>
 429                 public FlowReturns EndFlowBranching ()
 430                 {
 431                         FlowBranching cfb = (FlowBranching) FlowStack.Pop ();
 432
 433                         return CurrentBranching.MergeChild (cfb);
 434                 }
 435
 436                 // <summary>
 437                 //   Kills the current code branching.  This throws away any changed state
 438                 //   information and should only be used in case of an error.
 439                 // </summary>
 440                 public void KillFlowBranching ()
 441                 {
 442                         FlowBranching cfb = (FlowBranching) FlowStack.Pop ();
 443                 }
 444
 445                 // <summary>
 446                 //   Checks whether the local variable `vi' is already initialized
 447                 //   at the current point of the method's control flow.
 448                 //   If this method returns false, the caller must report an
 449                 //   error 165.
 450                 // </summary>
 451                 public bool IsVariableAssigned (VariableInfo vi)
 452                 {
 453                         if (DoFlowAnalysis)
 454                                 return CurrentBranching.IsVariableAssigned (vi);
 455                         else
 456                                 return true;
 457                 }
 458
 459                 // <summary>
 460                 //   Marks the local variable `vi' as being initialized at the current
 461                 //   current point of the method's control flow.
 462                 // </summary>
 463                 public void SetVariableAssigned (VariableInfo vi)
 464                 {
 465                         if (DoFlowAnalysis)
 466                                 CurrentBranching.SetVariableAssigned (vi);
 467                 }
 468
 469                 // <summary>
 470                 //   Checks whether the parameter `number' is already initialized
 471                 //   at the current point of the method's control flow.
 472                 //   If this method returns false, the caller must report an
 473                 //   error 165.  This is only necessary for `out' parameters and the
 474                 //   call will always succeed for non-`out' parameters.
 475                 // </summary>
 476                 public bool IsParameterAssigned (int number)
 477                 {
 478                         if (DoFlowAnalysis)
 479                                 return CurrentBranching.IsParameterAssigned (number);
 480                         else
 481                                 return true;
 482                 }
 483
 484                 // <summary>
 485                 //   Marks the parameter `number' as being initialized at the current
 486                 //   current point of the method's control flow.  This is only necessary
 487                 //   for `out' parameters.
 488                 // </summary>
 489                 public void SetParameterAssigned (int number)
 490                 {
 491                         if (DoFlowAnalysis)
 492                                 CurrentBranching.SetParameterAssigned (number);
 493                 }
 494
 495                 public void EmitTopBlock (Block block, InternalParameters ip, Location loc)
 496                 {
 497                         bool has_ret = false;
 498
 499 //                      Console.WriteLine ("Emitting: " + loc);
 500
 501                         if (CodeGen.SymbolWriter != null)
 502                                 Mark (loc);
 503
 504                         if (block != null){
 505                                 int errors = Report.Errors;
 506
 507                                 block.EmitMeta (this, block);
 508
 509                                 if (Report.Errors == errors){
 510                                         bool old_do_flow_analysis = DoFlowAnalysis;
 511                                         DoFlowAnalysis = true;
 512
 513                                         FlowBranching cfb = new FlowBranching (block, ip, loc);
 514                                         FlowStack.Push (cfb);
 515
 516                                         if (!block.Resolve (this)) {
 517                                                 FlowStack.Pop ();
 518                                                 DoFlowAnalysis = old_do_flow_analysis;
 519                                                 return;
 520                                         }
 521
 522                                         cfb = (FlowBranching) FlowStack.Pop ();
 523                                         FlowReturns returns = cfb.MergeTopBlock ();
 524
 525                                         DoFlowAnalysis = old_do_flow_analysis;
 526
 527                                         has_ret = block.Emit (this);
 528
 529                                         if ((returns == FlowReturns.ALWAYS) ||
 530                                             (returns == FlowReturns.EXCEPTION))
 531                                                 has_ret = true;
 532
 533                                         if (Report.Errors == errors){
 534                                                 if (RootContext.WarningLevel >= 3)
 535                                                         block.UsageWarning ();
 536                                         }
 537                                 }
 538                         }
 539
 540                         if (ReturnType != null && !has_ret){
 541                                 //
 542                                 // FIXME: we need full flow analysis to implement this
 543                                 // correctly and emit an error instead of a warning.
 544                                 //
 545                                 //
 546                                 Report.Error (161, loc, "Not all code paths return a value");
 547                                 return;
 548                         }
 549
 550                         if (HasReturnLabel)
 551                                 ig.MarkLabel (ReturnLabel);
 552                         if (return_value != null){
 553                                 ig.Emit (OpCodes.Ldloc, return_value);
 554                                 ig.Emit (OpCodes.Ret);
 555                         } else {
 556                                 if (!InTry){
 557                                         if (!has_ret || HasReturnLabel)
 558                                                 ig.Emit (OpCodes.Ret);
 559                                 }
 560                         }
 561                 }
 562
 563                 /// <summary>
 564                 ///   This is called immediately before emitting an IL opcode to tell the symbol
 565                 ///   writer to which source line this opcode belongs.
 566                 /// </summary>
 567                 public void Mark (Location loc)
 568                 {
 569                         if (!Location.IsNull (loc)) {
 570                                 ISymbolDocumentWriter doc = loc.SymbolDocument;
 571
 572                                 if (doc != null)
 573                                         ig.MarkSequencePoint (doc, loc.Row, 0,  loc.Row, 0);
 574                         }               }
 575
 576
 577                 /// <summary>
 578                 ///   Returns a temporary storage for a variable of type t as
 579                 ///   a local variable in the current body.
 580                 /// </summary>
 581                 public LocalBuilder GetTemporaryStorage (Type t)
 582                 {
 583                         LocalBuilder location;
 584
 585                         if (temporary_storage != null){
 586                                 location = (LocalBuilder) temporary_storage [t];
 587                                 if (location != null)
 588                                         return location;
 589                         }
 590
 591                         location = ig.DeclareLocal (t);
 592
 593                         return location;
 594                 }
 595
 596                 public void FreeTemporaryStorage (LocalBuilder b)
 597                 {
 598                         // Empty for now.
 599                 }
 600
 601                 /// <summary>
 602                 ///   Current loop begin and end labels.
 603                 /// </summary>
 604                 public Label LoopBegin, LoopEnd;
 605
 606                 /// <summary>
 607                 ///   Whether we are inside a loop and break/continue are possible.
 608                 /// </summary>
 609                 public bool  InLoop;
 610
 611                 /// <summary>
 612                 ///   This is incremented each time we enter a try/catch block and
 613                 ///   decremented if we leave it.
 614                 /// </summary>
 615                 public int   TryCatchLevel;
 616
 617                 /// <summary>
 618                 ///   The TryCatchLevel at the begin of the current loop.
 619                 /// </summary>
 620                 public int   LoopBeginTryCatchLevel;
 621
 622                 /// <summary>
 623                 ///   Default target in a switch statement.   Only valid if
 624                 ///   InSwitch is true
 625                 /// </summary>
 626                 public Label DefaultTarget;
 627
 628                 /// <summary>
 629                 ///   If this is non-null, points to the current switch statement
 630                 /// </summary>
 631                 public Switch Switch;
 632
 633                 /// <summary>
 634                 ///   ReturnValue creates on demand the LocalBuilder for the
 635                 ///   return value from the function.  By default this is not
 636                 ///   used.  This is only required when returns are found inside
 637                 ///   Try or Catch statements.
 638                 /// </summary>
 639                 public LocalBuilder TemporaryReturn ()
 640                 {
 641                         if (return_value == null){
 642                                 return_value = ig.DeclareLocal (ReturnType);
 643                                 ReturnLabel = ig.DefineLabel ();
 644                                 HasReturnLabel = true;
 645                         }
 646
 647                         return return_value;
 648                 }
 649
 650                 /// <summary>
 651                 ///   A dynamic This that is shared by all variables in a emitcontext.
 652                 ///   Created on demand.
 653                 /// </summary>
 654                 public Expression my_this;
 655                 public Expression This {
 656                         get {
 657                                 if (my_this == null) {
 658                                         if (CurrentBlock != null)
 659                                                 my_this = new This (CurrentBlock, loc);
 660                                         else
 661                                                 my_this = new This (loc);
 662
 663                                         my_this = my_this.Resolve (this);
 664                                 }
 665
 666                                 return my_this;
 667                         }
 668                 }
 669         }
 670 }