mcs/mbas/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                 ///   Location for this EmitContext
 316                 /// </summary>
 317                 public Location loc;
 318
 319                 /// <summary>
 320                 ///   Used to flag that it is ok to define types recursively, as the
 321                 ///   expressions are being evaluated as part of the type lookup
 322                 ///   during the type resolution process
 323                 /// </summary>
 324                 public bool ResolvingTypeTree;
 325
 326                 /// <summary>
 327                 ///   Inside an enum definition, we do not resolve enumeration values
 328                 ///   to their enumerations, but rather to the underlying type/value
 329                 ///   This is so EnumVal + EnumValB can be evaluated.
 330                 ///
 331                 ///   There is no "E operator + (E x, E y)", so during an enum evaluation
 332                 ///   we relax the rules
 333                 /// </summary>
 334                 public bool InEnumContext;
 335
 336                 protected Stack FlowStack;
 337
 338                 public EmitContext (TypeContainer parent, DeclSpace ds, Location l, ILGenerator ig,
 339                                     Type return_type, int code_flags, bool is_constructor)
 340                 {
 341                         this.ig = ig;
 342
 343                         TypeContainer = parent;
 344                         DeclSpace = ds;
 345                         CheckState = RootContext.Checked;
 346                         ConstantCheckState = true;
 347
 348                         IsStatic = (code_flags & Modifiers.STATIC) != 0;
 349                         ReturnType = return_type;
 350                         IsConstructor = is_constructor;
 351                         CurrentBlock = null;
 352
 353                         if (parent != null){
 354                                 // Can only be null for the ResolveType contexts.
 355                                 ContainerType = parent.TypeBuilder;
 356                                 if (parent.UnsafeContext)
 357                                         InUnsafe = true;
 358                                 else
 359                                         InUnsafe = (code_flags & Modifiers.UNSAFE) != 0;
 360                         }
 361                         loc = l;
 362
 363                         FlowStack = new Stack ();
 364
 365                         if (ReturnType == TypeManager.void_type)
 366                                 ReturnType = null;
 367                 }
 368
 369                 public EmitContext (TypeContainer tc, Location l, ILGenerator ig,
 370                                     Type return_type, int code_flags, bool is_constructor)
 371                         : this (tc, tc, l, ig, return_type, code_flags, is_constructor)
 372                 {
 373                 }
 374
 375                 public EmitContext (TypeContainer tc, Location l, ILGenerator ig,
 376                                     Type return_type, int code_flags)
 377                         : this (tc, tc, l, ig, return_type, code_flags, false)
 378                 {
 379                 }
 380
 381                 public FlowBranching CurrentBranching {
 382                         get {
 383                                 return (FlowBranching) FlowStack.Peek ();
 384                         }
 385                 }
 386
 387                 // <summary>
 388                 //   Starts a new code branching.  This inherits the state of all local
 389                 //   variables and parameters from the current branching.
 390                 // </summary>
 391                 public FlowBranching StartFlowBranching (FlowBranchingType type, Location loc)
 392                 {
 393                         FlowBranching cfb = new FlowBranching (CurrentBranching, type, null, loc);
 394
 395                         FlowStack.Push (cfb);
 396
 397                         return cfb;
 398                 }
 399
 400                 // <summary>
 401                 //   Starts a new code branching for block `block'.
 402                 // </summary>
 403                 public FlowBranching StartFlowBranching (Block block)
 404                 {
 405                         FlowBranching cfb;
 406                         FlowBranchingType type;
 407
 408                         if (CurrentBranching.Type == FlowBranchingType.SWITCH)
 409                                 type = FlowBranchingType.SWITCH_SECTION;
 410                         else
 411                                 type = FlowBranchingType.BLOCK;
 412
 413                         cfb = new FlowBranching (CurrentBranching, type, block, block.StartLocation);
 414
 415                         FlowStack.Push (cfb);
 416
 417                         return cfb;
 418                 }
 419
 420                 // <summary>
 421                 //   Ends a code branching.  Merges the state of locals and parameters
 422                 //   from all the children of the ending branching.
 423                 // </summary>
 424                 public FlowReturns EndFlowBranching ()
 425                 {
 426                         FlowBranching cfb = (FlowBranching) FlowStack.Pop ();
 427
 428                         return CurrentBranching.MergeChild (cfb);
 429                 }
 430
 431                 // <summary>
 432                 //   Kills the current code branching.  This throws away any changed state
 433                 //   information and should only be used in case of an error.
 434                 // </summary>
 435                 public void KillFlowBranching ()
 436                 {
 437                         FlowBranching cfb = (FlowBranching) FlowStack.Pop ();
 438                 }
 439
 440                 // <summary>
 441                 //   Checks whether the local variable `vi' is already initialized
 442                 //   at the current point of the method's control flow.
 443                 //   If this method returns false, the caller must report an
 444                 //   error 165.
 445                 // </summary>
 446                 public bool IsVariableAssigned (VariableInfo vi)
 447                 {
 448                         if (DoFlowAnalysis)
 449                                 return CurrentBranching.IsVariableAssigned (vi);
 450                         else
 451                                 return true;
 452                 }
 453
 454                 // <summary>
 455                 //   Marks the local variable `vi' as being initialized at the current
 456                 //   current point of the method's control flow.
 457                 // </summary>
 458                 public void SetVariableAssigned (VariableInfo vi)
 459                 {
 460                         if (DoFlowAnalysis)
 461                                 CurrentBranching.SetVariableAssigned (vi);
 462                 }
 463
 464                 // <summary>
 465                 //   Checks whether the parameter `number' is already initialized
 466                 //   at the current point of the method's control flow.
 467                 //   If this method returns false, the caller must report an
 468                 //   error 165.  This is only necessary for `out' parameters and the
 469                 //   call will always succeed for non-`out' parameters.
 470                 // </summary>
 471                 public bool IsParameterAssigned (int number)
 472                 {
 473                         if (DoFlowAnalysis)
 474                                 return CurrentBranching.IsParameterAssigned (number);
 475                         else
 476                                 return true;
 477                 }
 478
 479                 // <summary>
 480                 //   Marks the parameter `number' as being initialized at the current
 481                 //   current point of the method's control flow.  This is only necessary
 482                 //   for `out' parameters.
 483                 // </summary>
 484                 public void SetParameterAssigned (int number)
 485                 {
 486                         if (DoFlowAnalysis)
 487                                 CurrentBranching.SetParameterAssigned (number);
 488                 }
 489
 490                 public void EmitTopBlock (Block block, InternalParameters ip, Location loc)
 491                 {
 492                         bool has_ret = false;
 493
 494 //                      Console.WriteLine ("Emitting: " + loc);
 495
 496                         if (CodeGen.SymbolWriter != null)
 497                                 Mark (loc);
 498
 499                         if (block != null){
 500                                 int errors = Report.Errors;
 501
 502                                 block.EmitMeta (this, block);
 503
 504                                 if (Report.Errors == errors){
 505                                         bool old_do_flow_analysis = DoFlowAnalysis;
 506                                         DoFlowAnalysis = true;
 507
 508                                         FlowBranching cfb = new FlowBranching (block, ip, loc);
 509                                         FlowStack.Push (cfb);
 510
 511                                         if (!block.Resolve (this)) {
 512                                                 FlowStack.Pop ();
 513                                                 DoFlowAnalysis = old_do_flow_analysis;
 514                                                 return;
 515                                         }
 516
 517                                         cfb = (FlowBranching) FlowStack.Pop ();
 518                                         FlowReturns returns = cfb.MergeTopBlock ();
 519
 520                                         DoFlowAnalysis = old_do_flow_analysis;
 521
 522                                         has_ret = block.Emit (this);
 523
 524                                         if ((returns == FlowReturns.ALWAYS) ||
 525                                             (returns == FlowReturns.EXCEPTION) ||
 526                                             (returns == FlowReturns.UNREACHABLE))
 527                                                 has_ret = true;
 528
 529                                         if (Report.Errors == errors){
 530                                                 if (RootContext.WarningLevel >= 3)
 531                                                         block.UsageWarning ();
 532                                         }
 533                                 }
 534                         }
 535
 536                         if (ReturnType != null && !has_ret){
 537                                 //
 538                                 // FIXME: we need full flow analysis to implement this
 539                                 // correctly and emit an error instead of a warning.
 540                                 //
 541                                 //
 542                                 Report.Error (161, loc, "Not all code paths return a value");
 543                                 return;
 544                         }
 545
 546                         if (HasReturnLabel)
 547                                 ig.MarkLabel (ReturnLabel);
 548                         if (return_value != null){
 549                                 ig.Emit (OpCodes.Ldloc, return_value);
 550                                 ig.Emit (OpCodes.Ret);
 551                         } else {
 552                                 if (!InTry){
 553                                         if (!has_ret || HasReturnLabel)
 554                                                 ig.Emit (OpCodes.Ret);
 555                                 }
 556                         }
 557                 }
 558
 559                 /// <summary>
 560                 ///   This is called immediately before emitting an IL opcode to tell the symbol
 561                 ///   writer to which source line this opcode belongs.
 562                 /// </summary>
 563                 public void Mark (Location loc)
 564                 {
 565                         if ((CodeGen.SymbolWriter != null) && !Location.IsNull (loc)) {
 566                                 ISymbolDocumentWriter doc = loc.SymbolDocument;
 567
 568                                 if (doc != null)
 569                                         ig.MarkSequencePoint (doc, loc.Row, 0,  loc.Row, 0);
 570                         }
 571                 }
 572
 573                 /// <summary>
 574                 ///   Returns a temporary storage for a variable of type t as
 575                 ///   a local variable in the current body.
 576                 /// </summary>
 577                 public LocalBuilder GetTemporaryStorage (Type t)
 578                 {
 579                         LocalBuilder location;
 580
 581                         if (temporary_storage != null){
 582                                 location = (LocalBuilder) temporary_storage [t];
 583                                 if (location != null)
 584                                         return location;
 585                         }
 586
 587                         location = ig.DeclareLocal (t);
 588
 589                         return location;
 590                 }
 591
 592                 public void FreeTemporaryStorage (LocalBuilder b)
 593                 {
 594                         // Empty for now.
 595                 }
 596
 597                 /// <summary>
 598                 ///   Current loop begin and end labels.
 599                 /// </summary>
 600                 public Label LoopBegin, LoopEnd;
 601
 602                 /// <summary>
 603                 ///   Whether we are inside a loop and break/continue are possible.
 604                 /// </summary>
 605                 public bool  InLoop;
 606
 607                 /// <summary>
 608                 ///   This is incremented each time we enter a try/catch block and
 609                 ///   decremented if we leave it.
 610                 /// </summary>
 611                 public int   TryCatchLevel;
 612
 613                 /// <summary>
 614                 ///   The TryCatchLevel at the begin of the current loop.
 615                 /// </summary>
 616                 public int   LoopBeginTryCatchLevel;
 617
 618                 /// <summary>
 619                 ///   Default target in a switch statement.   Only valid if
 620                 ///   InSwitch is true
 621                 /// </summary>
 622                 public Label DefaultTarget;
 623
 624                 /// <summary>
 625                 ///   If this is non-null, points to the current switch statement
 626                 /// </summary>
 627                 public Switch Switch;
 628
 629                 /// <summary>
 630                 ///   ReturnValue creates on demand the LocalBuilder for the
 631                 ///   return value from the function.  By default this is not
 632                 ///   used.  This is only required when returns are found inside
 633                 ///   Try or Catch statements.
 634                 /// </summary>
 635                 public LocalBuilder TemporaryReturn ()
 636                 {
 637                         if (return_value == null){
 638                                 return_value = ig.DeclareLocal (ReturnType);
 639                                 ReturnLabel = ig.DefineLabel ();
 640                                 HasReturnLabel = true;
 641                         }
 642
 643                         return return_value;
 644                 }
 645
 646                 /// <summary>
 647                 ///   A dynamic This that is shared by all variables in a emitcontext.
 648                 ///   Created on demand.
 649                 /// </summary>
 650                 public Expression my_this;
 651                 public Expression This {
 652                         get {
 653                                 if (my_this == null) {
 654                                         if (CurrentBlock != null)
 655                                                 my_this = new This (CurrentBlock, loc);
 656                                         else
 657                                                 my_this = new This (loc);
 658
 659                                         my_this = my_this.Resolve (this);
 660                                 }
 661
 662                                 return my_this;
 663                         }
 664                 }
 665         }
 666 }