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.Warning (
 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.Warning (
 128                                                 -18, "Cannot initialize the symbol writer");
 129                                 break;
 130
 131                         default:
 132                                 Report.Warning (
 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 = Path.GetFileNameWithoutExtension (name);
 149
 150                         current_domain = AppDomain.CurrentDomain;
 151                         AssemblyBuilder = current_domain.DefineDynamicAssembly (
 152                                 an, AssemblyBuilderAccess.RunAndSave, Dirname (name));
 153
 154                         //
 155                         // Pass a path-less name to DefineDynamicModule.  Wonder how
 156                         // this copes with output in different directories then.
 157                         // FIXME: figure out how this copes with --output /tmp/blah
 158                         //
 159                         // If the third argument is true, the ModuleBuilder will dynamically
 160                         // load the default symbol writer.
 161                         //
 162                         ModuleBuilder = AssemblyBuilder.DefineDynamicModule (
 163                                 Basename (name), Basename (output), want_debugging_support);
 164
 165                         int pos = output.LastIndexOf (".");
 166
 167                         string basename;
 168                         if (pos > 0)
 169                                 basename = output.Substring (0, pos);
 170                         else
 171                                 basename = output;
 172
 173                         string symbol_output = basename + ".dbg";
 174
 175                         if (want_debugging_support)
 176                                 InitializeSymbolWriter (basename, symbol_output, output, debug_args);
 177                         else {
 178                                 try {
 179                                         File.Delete (symbol_output);
 180                                 } catch {
 181                                         // Ignore errors.
 182                                 }
 183                         }
 184                 }
 185
 186                 static public void Save (string name)
 187                 {
 188                         try {
 189                                 AssemblyBuilder.Save (Basename (name));
 190                         } catch (System.IO.IOException io){
 191                                 Report.Error (16, "Could not write to file `"+name+"', cause: " + io.Message);
 192                         }
 193                 }
 194
 195                 static public void SaveSymbols ()
 196                 {
 197                         if (SymbolWriter != null) {
 198                                 // If we have a symbol writer, call its Close() method to write
 199                                 // the symbol file to disk.
 200                                 //
 201                                 // When using Mono's default symbol writer, the Close() method must
 202                                 // be called after the assembly has already been written to disk since
 203                                 // it opens the assembly and reads its metadata.
 204                                 SymbolWriter.Close ();
 205                         }
 206                 }
 207         }
 208
 209         /// <summary>
 210         ///   An Emit Context is created for each body of code (from methods,
 211         ///   properties bodies, indexer bodies or constructor bodies)
 212         /// </summary>
 213         public class EmitContext {
 214                 public DeclSpace DeclSpace;
 215                 public DeclSpace TypeContainer;
 216                 public ILGenerator   ig;
 217
 218                 /// <summary>
 219                 ///   This variable tracks the `checked' state of the compilation,
 220                 ///   it controls whether we should generate code that does overflow
 221                 ///   checking, or if we generate code that ignores overflows.
 222                 ///
 223                 ///   The default setting comes from the command line option to generate
 224                 ///   checked or unchecked code plus any source code changes using the
 225                 ///   checked/unchecked statements or expressions.   Contrast this with
 226                 ///   the ConstantCheckState flag.
 227                 /// </summary>
 228
 229                 public bool CheckState;
 230
 231                 /// <summary>
 232                 ///   The constant check state is always set to `true' and cant be changed
 233                 ///   from the command line.  The source code can change this setting with
 234                 ///   the `checked' and `unchecked' statements and expressions.
 235                 /// </summary>
 236                 public bool ConstantCheckState;
 237
 238                 /// <summary>
 239                 ///   Whether we are emitting code inside a static or instance method
 240                 /// </summary>
 241                 public bool IsStatic;
 242
 243                 /// <summary>
 244                 ///   Whether we are emitting a field initializer
 245                 /// </summary>
 246                 public bool IsFieldInitializer;
 247
 248                 /// <summary>
 249                 ///   The value that is allowed to be returned or NULL if there is no
 250                 ///   return type.
 251                 /// </summary>
 252                 public Type ReturnType;
 253
 254                 /// <summary>
 255                 ///   Points to the Type (extracted from the TypeContainer) that
 256                 ///   declares this body of code
 257                 /// </summary>
 258                 public Type ContainerType;
 259
 260                 /// <summary>
 261                 ///   Whether this is generating code for a constructor
 262                 /// </summary>
 263                 public bool IsConstructor;
 264
 265                 /// <summary>
 266                 ///   Whether we're control flow analysis enabled
 267                 /// </summary>
 268                 public bool DoFlowAnalysis;
 269
 270                 /// <summary>
 271                 ///   Keeps track of the Type to LocalBuilder temporary storage created
 272                 ///   to store structures (used to compute the address of the structure
 273                 ///   value on structure method invocations)
 274                 /// </summary>
 275                 public Hashtable temporary_storage;
 276
 277                 public Block CurrentBlock;
 278
 279                 /// <summary>
 280                 ///   The location where we store the return value.
 281                 /// </summary>
 282                 LocalBuilder return_value;
 283
 284                 /// <summary>
 285                 ///   The location where return has to jump to return the
 286                 ///   value
 287                 /// </summary>
 288                 public Label ReturnLabel;
 289
 290                 /// <summary>
 291                 ///   If we already defined the ReturnLabel
 292                 /// </summary>
 293                 public bool HasReturnLabel;
 294
 295                 /// <summary>
 296                 ///   Whether we are in a Finally block
 297                 /// </summary>
 298                 public bool InFinally;
 299
 300                 /// <summary>
 301                 ///   Whether we are in a Try block
 302                 /// </summary>
 303                 public bool InTry;
 304
 305                 /// <summary>
 306                 ///   Whether we are in a Catch block
 307                 /// </summary>
 308                 public bool InCatch;
 309
 310                 /// <summary>
 311                 ///  Whether we are inside an unsafe block
 312                 /// </summary>
 313                 public bool InUnsafe;
 314
 315                 /// <summary>
 316                 ///   Location for this EmitContext
 317                 /// </summary>
 318                 public Location loc;
 319
 320                 /// <summary>
 321                 ///   Used to flag that it is ok to define types recursively, as the
 322                 ///   expressions are being evaluated as part of the type lookup
 323                 ///   during the type resolution process
 324                 /// </summary>
 325                 public bool ResolvingTypeTree;
 326
 327                 /// <summary>
 328                 ///   Inside an enum definition, we do not resolve enumeration values
 329                 ///   to their enumerations, but rather to the underlying type/value
 330                 ///   This is so EnumVal + EnumValB can be evaluated.
 331                 ///
 332                 ///   There is no "E operator + (E x, E y)", so during an enum evaluation
 333                 ///   we relax the rules
 334                 /// </summary>
 335                 public bool InEnumContext;
 336
 337                 protected Stack FlowStack;
 338
 339                 public EmitContext (DeclSpace parent, DeclSpace ds, Location l, ILGenerator ig,
 340                                     Type return_type, int code_flags, bool is_constructor)
 341                 {
 342                         this.ig = ig;
 343
 344                         TypeContainer = parent;
 345                         DeclSpace = ds;
 346                         CheckState = RootContext.Checked;
 347                         ConstantCheckState = true;
 348
 349                         IsStatic = (code_flags & Modifiers.STATIC) != 0;
 350                         ReturnType = return_type;
 351                         IsConstructor = is_constructor;
 352                         CurrentBlock = null;
 353
 354                         if (parent != null){
 355                                 // Can only be null for the ResolveType contexts.
 356                                 ContainerType = parent.TypeBuilder;
 357                                 if (parent.UnsafeContext)
 358                                         InUnsafe = true;
 359                                 else
 360                                         InUnsafe = (code_flags & Modifiers.UNSAFE) != 0;
 361                         }
 362                         loc = l;
 363
 364                         FlowStack = new Stack ();
 365
 366                         if (ReturnType == TypeManager.void_type)
 367                                 ReturnType = null;
 368                 }
 369
 370                 public EmitContext (TypeContainer tc, Location l, ILGenerator ig,
 371                                     Type return_type, int code_flags, bool is_constructor)
 372                         : this (tc, tc, l, ig, return_type, code_flags, is_constructor)
 373                 {
 374                 }
 375
 376                 public EmitContext (TypeContainer tc, Location l, ILGenerator ig,
 377                                     Type return_type, int code_flags)
 378                         : this (tc, tc, l, ig, return_type, code_flags, false)
 379                 {
 380                 }
 381
 382                 public FlowBranching CurrentBranching {
 383                         get {
 384                                 return (FlowBranching) FlowStack.Peek ();
 385                         }
 386                 }
 387
 388                 // <summary>
 389                 //   Starts a new code branching.  This inherits the state of all local
 390                 //   variables and parameters from the current branching.
 391                 // </summary>
 392                 public FlowBranching StartFlowBranching (FlowBranchingType type, Location loc)
 393                 {
 394                         FlowBranching cfb = new FlowBranching (CurrentBranching, type, null, loc);
 395
 396                         FlowStack.Push (cfb);
 397
 398                         return cfb;
 399                 }
 400
 401                 // <summary>
 402                 //   Starts a new code branching for block `block'.
 403                 // </summary>
 404                 public FlowBranching StartFlowBranching (Block block)
 405                 {
 406                         FlowBranching cfb;
 407                         FlowBranchingType type;
 408
 409                         if (CurrentBranching.Type == FlowBranchingType.SWITCH)
 410                                 type = FlowBranchingType.SWITCH_SECTION;
 411                         else
 412                                 type = FlowBranchingType.BLOCK;
 413
 414                         cfb = new FlowBranching (CurrentBranching, type, block, block.StartLocation);
 415
 416                         FlowStack.Push (cfb);
 417
 418                         return cfb;
 419                 }
 420
 421                 // <summary>
 422                 //   Ends a code branching.  Merges the state of locals and parameters
 423                 //   from all the children of the ending branching.
 424                 // </summary>
 425                 public FlowReturns EndFlowBranching ()
 426                 {
 427                         FlowBranching cfb = (FlowBranching) FlowStack.Pop ();
 428
 429                         return CurrentBranching.MergeChild (cfb);
 430                 }
 431
 432                 // <summary>
 433                 //   Kills the current code branching.  This throws away any changed state
 434                 //   information and should only be used in case of an error.
 435                 // </summary>
 436                 public void KillFlowBranching ()
 437                 {
 438                         FlowBranching cfb = (FlowBranching) FlowStack.Pop ();
 439                 }
 440
 441                 // <summary>
 442                 //   Checks whether the local variable `vi' is already initialized
 443                 //   at the current point of the method's control flow.
 444                 //   If this method returns false, the caller must report an
 445                 //   error 165.
 446                 // </summary>
 447                 public bool IsVariableAssigned (VariableInfo vi)
 448                 {
 449                         if (DoFlowAnalysis)
 450                                 return CurrentBranching.IsVariableAssigned (vi);
 451                         else
 452                                 return true;
 453                 }
 454
 455                 // <summary>
 456                 //   Marks the local variable `vi' as being initialized at the current
 457                 //   current point of the method's control flow.
 458                 // </summary>
 459                 public void SetVariableAssigned (VariableInfo vi)
 460                 {
 461                         if (DoFlowAnalysis)
 462                                 CurrentBranching.SetVariableAssigned (vi);
 463                 }
 464
 465                 // <summary>
 466                 //   Checks whether the parameter `number' is already initialized
 467                 //   at the current point of the method's control flow.
 468                 //   If this method returns false, the caller must report an
 469                 //   error 165.  This is only necessary for `out' parameters and the
 470                 //   call will always succeed for non-`out' parameters.
 471                 // </summary>
 472                 public bool IsParameterAssigned (int number)
 473                 {
 474                         if (DoFlowAnalysis)
 475                                 return CurrentBranching.IsParameterAssigned (number);
 476                         else
 477                                 return true;
 478                 }
 479
 480                 // <summary>
 481                 //   Marks the parameter `number' as being initialized at the current
 482                 //   current point of the method's control flow.  This is only necessary
 483                 //   for `out' parameters.
 484                 // </summary>
 485                 public void SetParameterAssigned (int number)
 486                 {
 487                         if (DoFlowAnalysis)
 488                                 CurrentBranching.SetParameterAssigned (number);
 489                 }
 490
 491                 public void EmitTopBlock (Block block, InternalParameters ip, Location loc)
 492                 {
 493                         bool has_ret = false;
 494
 495 //                      Console.WriteLine ("Emitting: " + loc);
 496
 497                         if (CodeGen.SymbolWriter != null)
 498                                 Mark (loc);
 499
 500                         if (block != null){
 501                                 try {
 502                                 int errors = Report.Errors;
 503
 504                                 block.EmitMeta (this, block);
 505
 506                                 if (Report.Errors == errors){
 507                                         bool old_do_flow_analysis = DoFlowAnalysis;
 508                                         DoFlowAnalysis = true;
 509
 510                                         FlowBranching cfb = new FlowBranching (block, ip, loc);
 511                                         FlowStack.Push (cfb);
 512
 513                                         if (!block.Resolve (this)) {
 514                                                 FlowStack.Pop ();
 515                                                 DoFlowAnalysis = old_do_flow_analysis;
 516                                                 return;
 517                                         }
 518
 519                                         cfb = (FlowBranching) FlowStack.Pop ();
 520                                         FlowReturns returns = cfb.MergeTopBlock ();
 521
 522                                         DoFlowAnalysis = old_do_flow_analysis;
 523
 524                                         has_ret = block.Emit (this);
 525
 526                                         if ((returns == FlowReturns.ALWAYS) ||
 527                                             (returns == FlowReturns.EXCEPTION) ||
 528                                             (returns == FlowReturns.UNREACHABLE))
 529                                                 has_ret = true;
 530
 531                                         if (Report.Errors == errors){
 532                                                 if (RootContext.WarningLevel >= 3)
 533                                                         block.UsageWarning ();
 534                                         }
 535                                 }
 536                                 } catch {
 537                                         Console.WriteLine ("Exception caught by the compiler while compiling:");
 538                                         Console.WriteLine ("   Block that caused the problem begin at: " + loc);
 539                                         Console.WriteLine ("                     Block being compiled: [{0},{1}]",
 540                                                            CurrentBlock.StartLocation, CurrentBlock.EndLocation);
 541                                         throw;
 542                                 }
 543                         }
 544
 545                         if (ReturnType != null && !has_ret){
 546                                 //
 547                                 // FIXME: we need full flow analysis to implement this
 548                                 // correctly and emit an error instead of a warning.
 549                                 //
 550                                 //
 551                                 Report.Error (161, loc, "Not all code paths return a value");
 552                                 return;
 553                         }
 554
 555                         if (HasReturnLabel)
 556                                 ig.MarkLabel (ReturnLabel);
 557                         if (return_value != null){
 558                                 ig.Emit (OpCodes.Ldloc, return_value);
 559                                 ig.Emit (OpCodes.Ret);
 560                         } else {
 561                                 if (!InTry){
 562                                         if (!has_ret || HasReturnLabel)
 563                                                 ig.Emit (OpCodes.Ret);
 564                                 }
 565                         }
 566                 }
 567
 568                 /// <summary>
 569                 ///   This is called immediately before emitting an IL opcode to tell the symbol
 570                 ///   writer to which source line this opcode belongs.
 571                 /// </summary>
 572                 public void Mark (Location loc)
 573                 {
 574                         if ((CodeGen.SymbolWriter != null) && !Location.IsNull (loc)) {
 575                                 ISymbolDocumentWriter doc = loc.SymbolDocument;
 576
 577                                 if (doc != null)
 578                                         ig.MarkSequencePoint (doc, loc.Row, 0,  loc.Row, 0);
 579                         }
 580                 }
 581
 582                 /// <summary>
 583                 ///   Returns a temporary storage for a variable of type t as
 584                 ///   a local variable in the current body.
 585                 /// </summary>
 586                 public LocalBuilder GetTemporaryStorage (Type t)
 587                 {
 588                         LocalBuilder location;
 589
 590                         if (temporary_storage != null){
 591                                 location = (LocalBuilder) temporary_storage [t];
 592                                 if (location != null)
 593                                         return location;
 594                         }
 595
 596                         location = ig.DeclareLocal (t);
 597
 598                         return location;
 599                 }
 600
 601                 public void FreeTemporaryStorage (LocalBuilder b)
 602                 {
 603                         // Empty for now.
 604                 }
 605
 606                 /// <summary>
 607                 ///   Current loop begin and end labels.
 608                 /// </summary>
 609                 public Label LoopBegin, LoopEnd;
 610
 611                 /// <summary>
 612                 ///   Whether we are inside a loop and break/continue are possible.
 613                 /// </summary>
 614                 public bool  InLoop;
 615
 616                 /// <summary>
 617                 ///   This is incremented each time we enter a try/catch block and
 618                 ///   decremented if we leave it.
 619                 /// </summary>
 620                 public int   TryCatchLevel;
 621
 622                 /// <summary>
 623                 ///   The TryCatchLevel at the begin of the current loop.
 624                 /// </summary>
 625                 public int   LoopBeginTryCatchLevel;
 626
 627                 /// <summary>
 628                 ///   Default target in a switch statement.   Only valid if
 629                 ///   InSwitch is true
 630                 /// </summary>
 631                 public Label DefaultTarget;
 632
 633                 /// <summary>
 634                 ///   If this is non-null, points to the current switch statement
 635                 /// </summary>
 636                 public Switch Switch;
 637
 638                 /// <summary>
 639                 ///   ReturnValue creates on demand the LocalBuilder for the
 640                 ///   return value from the function.  By default this is not
 641                 ///   used.  This is only required when returns are found inside
 642                 ///   Try or Catch statements.
 643                 /// </summary>
 644                 public LocalBuilder TemporaryReturn ()
 645                 {
 646                         if (return_value == null){
 647                                 return_value = ig.DeclareLocal (ReturnType);
 648                                 ReturnLabel = ig.DefineLabel ();
 649                                 HasReturnLabel = true;
 650                         }
 651
 652                         return return_value;
 653                 }
 654
 655                 /// <summary>
 656                 ///   A dynamic This that is shared by all variables in a emitcontext.
 657                 ///   Created on demand.
 658                 /// </summary>
 659                 public Expression my_this;
 660                 public Expression This {
 661                         get {
 662                                 if (my_this == null) {
 663                                         if (CurrentBlock != null)
 664                                                 my_this = new This (CurrentBlock, loc);
 665                                         else
 666                                                 my_this = new This (loc);
 667
 668                                         my_this = my_this.Resolve (this);
 669                                 }
 670
 671                                 return my_this;
 672                         }
 673                 }
 674         }
 675 }