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