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.Collections;
  12 using System.Reflection;
  13 using System.Reflection.Emit;
  14 using System.Diagnostics.SymbolStore;
  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 ISymbolWriter 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                 // This routine initializes the Mono runtime SymbolWriter.
  67                 //
  68                 static void InitMonoSymbolWriter (string basename, string[] debug_args)
  69                 {
  70                         string symbol_output = basename + "-debug.s";
  71
  72                         Type itype = SymbolWriter.GetType ();
  73                         if (itype == null)
  74                                 return;
  75
  76                         Type[] arg_types = new Type [2];
  77                         arg_types [0] = typeof (string);
  78                         arg_types [1] = typeof (string[]);
  79
  80                         MethodInfo initialize = itype.GetMethod ("Initialize", arg_types);
  81                         if (initialize == null)
  82                                 return;
  83
  84                         object[] args = new object [2];
  85                         args [0] = symbol_output;
  86                         args [1] = debug_args;
  87
  88                         initialize.Invoke (SymbolWriter, args);
  89                 }
  90
  91                 //
  92                 // Initializes the symbol writer
  93                 //
  94                 static void InitializeSymbolWriter (string basename, string[] args)
  95                 {
  96                         SymbolWriter = ModuleBuilder.GetSymWriter ();
  97
  98                         //
  99                         // If we got an ISymbolWriter instance, initialize it.
 100                         //
 101                         if (SymbolWriter == null)
 102                                 return;
 103
 104                         //
 105                         // Due to lacking documentation about the first argument of the
 106                         // Initialize method, we cannot use Microsoft's default symbol
 107                         // writer yet.
 108                         //
 109                         // If we're using the mono symbol writer, the SymbolWriter object
 110                         // is of type MonoSymbolWriter - but that's defined in a dynamically
 111                         // loaded DLL - that's why we're doing a comparision based on the type
 112                         // name here instead of using `SymbolWriter is MonoSymbolWriter'.
 113                         //
 114                         Type sym_type = ((object) SymbolWriter).GetType ();
 115
 116                         switch (sym_type.Name){
 117                         case "MonoSymbolWriter":
 118                                 InitMonoSymbolWriter (basename, args);
 119                                 break;
 120
 121                         default:
 122                                 Report.Error (
 123                                         -18, "Cannot generate debugging information on this platform");
 124                                 break;
 125                         }
 126                 }
 127
 128                 //
 129                 // Initializes the code generator variables
 130                 //
 131                 static public void Init (string name, string output, bool want_debugging_support,
 132                                          string[] debug_args)
 133                 {
 134                         AssemblyName an;
 135
 136                         FileName = output;
 137                         an = new AssemblyName ();
 138                         an.Name = TrimExt (Basename (name));
 139                         current_domain = AppDomain.CurrentDomain;
 140                         AssemblyBuilder = current_domain.DefineDynamicAssembly (
 141                                 an, AssemblyBuilderAccess.RunAndSave, Dirname (name));
 142
 143                         //
 144                         // Pass a path-less name to DefineDynamicModule.  Wonder how
 145                         // this copes with output in different directories then.
 146                         // FIXME: figure out how this copes with --output /tmp/blah
 147                         //
 148                         // If the third argument is true, the ModuleBuilder will dynamically
 149                         // load the default symbol writer.
 150                         //
 151                         ModuleBuilder = AssemblyBuilder.DefineDynamicModule (
 152                                 Basename (name), Basename (output), want_debugging_support);
 153
 154                         if (want_debugging_support)
 155                                 InitializeSymbolWriter (an.Name, debug_args);
 156                 }
 157
 158                 static public void Save (string name)
 159                 {
 160                         try {
 161                                 AssemblyBuilder.Save (Basename (name));
 162                         } catch (System.IO.IOException io){
 163                                 Report.Error (16, "Coult not write to file `"+name+"', cause: " + io.Message);
 164                         }
 165                 }
 166
 167                 static public void SaveSymbols ()
 168                 {
 169                         if (SymbolWriter != null) {
 170                                 // If we have a symbol writer, call its Close() method to write
 171                                 // the symbol file to disk.
 172                                 //
 173                                 // When using Mono's default symbol writer, the Close() method must
 174                                 // be called after the assembly has already been written to disk since
 175                                 // it opens the assembly and reads its metadata.
 176                                 SymbolWriter.Close ();
 177                         }
 178                 }
 179         }
 180
 181         /// <summary>
 182         ///   An Emit Context is created for each body of code (from methods,
 183         ///   properties bodies, indexer bodies or constructor bodies)
 184         /// </summary>
 185         public class EmitContext {
 186                 public DeclSpace DeclSpace;
 187                 public TypeContainer TypeContainer;
 188                 public ILGenerator   ig;
 189
 190                 /// <summary>
 191                 ///   This variable tracks the `checked' state of the compilation,
 192                 ///   it controls whether we should generate code that does overflow
 193                 ///   checking, or if we generate code that ignores overflows.
 194                 ///
 195                 ///   The default setting comes from the command line option to generate
 196                 ///   checked or unchecked code plus any source code changes using the
 197                 ///   checked/unchecked statements or expressions.   Contrast this with
 198                 ///   the ConstantCheckState flag.
 199                 /// </summary>
 200
 201                 public bool CheckState;
 202
 203                 /// <summary>
 204                 ///   The constant check state is always set to `true' and cant be changed
 205                 ///   from the command line.  The source code can change this setting with
 206                 ///   the `checked' and `unchecked' statements and expressions.
 207                 /// </summary>
 208                 public bool ConstantCheckState;
 209
 210                 /// <summary>
 211                 ///   Whether we are emitting code inside a static or instance method
 212                 /// </summary>
 213                 public bool IsStatic;
 214
 215                 /// <summary>
 216                 ///   The value that is allowed to be returned or NULL if there is no
 217                 ///   return type.
 218                 /// </summary>
 219                 public Type ReturnType;
 220
 221                 /// <summary>
 222                 ///   Points to the Type (extracted from the TypeContainer) that
 223                 ///   declares this body of code
 224                 /// </summary>
 225                 public Type ContainerType;
 226
 227                 /// <summary>
 228                 ///   Whether this is generating code for a constructor
 229                 /// </summary>
 230                 public bool IsConstructor;
 231
 232                 /// <summary>
 233                 ///   Keeps track of the Type to LocalBuilder temporary storage created
 234                 ///   to store structures (used to compute the address of the structure
 235                 ///   value on structure method invocations)
 236                 /// </summary>
 237                 public Hashtable temporary_storage;
 238
 239                 public Block CurrentBlock;
 240
 241                 /// <summary>
 242                 ///   The location where we store the return value.
 243                 /// </summary>
 244                 LocalBuilder return_value;
 245
 246                 /// <summary>
 247                 ///   The location where return has to jump to return the
 248                 ///   value
 249                 /// </summary>
 250                 public Label ReturnLabel;
 251
 252                 /// <summary>
 253                 ///   Whether we are in a Finally block
 254                 /// </summary>
 255                 public bool InFinally;
 256
 257                 /// <summary>
 258                 ///   Whether we are in a Try block
 259                 /// </summary>
 260                 public bool InTry;
 261
 262                 /// <summary>
 263                 ///   Whether we are in a Catch block
 264                 /// </summary>
 265                 public bool InCatch;
 266
 267                 /// <summary>
 268                 ///  Whether we are inside an unsafe block
 269                 /// </summary>
 270                 public bool InUnsafe;
 271
 272                 /// <summary>
 273                 ///   Whether we break from a loop or not
 274                 /// </summary>
 275                 public bool Breaks;
 276
 277                 /// <summary>
 278                 ///   Location for this EmitContext
 279                 /// </summary>
 280                 public Location loc;
 281
 282                 /// <summary>
 283                 ///   Used to "flag" the resolution process to only lookup types,
 284                 ///   and nothing else.  This is an out-of-band communication
 285                 ///   path to SimpleName from the cast operation.
 286                 /// </summary>
 287                 public bool OnlyLookupTypes;
 288
 289                 /// <summary>
 290                 ///   Used to flag that it is ok to define types recursively, as the
 291                 ///   expressions are being evaluated as part of the type lookup
 292                 ///   during the type resolution process
 293                 /// </summary>
 294                 public bool ResolvingTypeTree;
 295
 296                 /// <summary>
 297                 ///   Inside an enum definition, we do not resolve enumeration values
 298                 ///   to their enumerations, but rather to the underlying type/value
 299                 ///   This is so EnumVal + EnumValB can be evaluated.
 300                 ///
 301                 ///   There is no "E operator + (E x, E y)", so during an enum evaluation
 302                 ///   we relax the rules
 303                 /// </summary>
 304                 public bool InEnumContext;
 305
 306                 public EmitContext (TypeContainer parent, DeclSpace ds, Location l, ILGenerator ig,
 307                                     Type return_type, int code_flags, bool is_constructor)
 308                 {
 309                         this.ig = ig;
 310
 311                         TypeContainer = parent;
 312                         DeclSpace = ds;
 313                         CheckState = RootContext.Checked;
 314                         ConstantCheckState = true;
 315
 316                         IsStatic = (code_flags & Modifiers.STATIC) != 0;
 317                         ReturnType = return_type;
 318                         IsConstructor = is_constructor;
 319                         CurrentBlock = null;
 320
 321                         if (parent != null){
 322                                 // Can only be null for the ResolveType contexts.
 323                         ContainerType = parent.TypeBuilder;
 324                         InUnsafe = ((parent.ModFlags | code_flags) & Modifiers.UNSAFE) != 0;
 325                         }
 326                         OnlyLookupTypes = false;
 327                         loc = l;
 328
 329                         if (ReturnType == TypeManager.void_type)
 330                                 ReturnType = null;
 331                 }
 332
 333                 public EmitContext (TypeContainer tc, Location l, ILGenerator ig,
 334                                     Type return_type, int code_flags, bool is_constructor)
 335                         : this (tc, tc, l, ig, return_type, code_flags, is_constructor)
 336                 {
 337                 }
 338
 339                 public EmitContext (TypeContainer tc, Location l, ILGenerator ig,
 340                                     Type return_type, int code_flags)
 341                         : this (tc, tc, l, ig, return_type, code_flags, false)
 342                 {
 343                 }
 344
 345                 public void EmitTopBlock (Block block, Location loc)
 346                 {
 347                         bool has_ret = false;
 348
 349 //                      Console.WriteLine ("Emitting: " + loc);
 350
 351                         if (CodeGen.SymbolWriter != null)
 352                                 Mark (loc);
 353
 354                         if (block != null){
 355                                 int errors = Report.Errors;
 356
 357                                 block.EmitMeta (this, block);
 358
 359                                 if (Report.Errors == errors){
 360                                         if (!block.Resolve (this))
 361                                                 return;
 362
 363                                         has_ret = block.Emit (this);
 364
 365                                         if (Report.Errors == errors){
 366                                                 if (RootContext.WarningLevel >= 3)
 367                                                         block.UsageWarning ();
 368                                         }
 369                                 }
 370                         }
 371
 372                         if (ReturnType != null && !has_ret){
 373                                 //
 374                                 // FIXME: we need full flow analysis to implement this
 375                                 // correctly and emit an error instead of a warning.
 376                                 //
 377                                 //
 378                                 Report.Error (161, loc, "Not all code paths return a value");
 379                                 return;
 380                         }
 381
 382                         if (return_value != null){
 383                                 ig.MarkLabel (ReturnLabel);
 384                                 ig.Emit (OpCodes.Ldloc, return_value);
 385                                 ig.Emit (OpCodes.Ret);
 386                         } else {
 387                                 if (!has_ret){
 388                                         if (!InTry)
 389                                                 ig.Emit (OpCodes.Ret);
 390                                 }
 391                         }
 392                 }
 393
 394                 /// <summary>
 395                 ///   This is called immediately before emitting an IL opcode to tell the symbol
 396                 ///   writer to which source line this opcode belongs.
 397                 /// </summary>
 398                 public void Mark (Location loc)
 399                 {
 400                         if (!Location.IsNull (loc)) {
 401                                 ISymbolDocumentWriter doc = loc.SymbolDocument;
 402
 403                                 if (doc != null)
 404                                         ig.MarkSequencePoint (doc, loc.Row, 0,  loc.Row, 0);
 405                         }               }
 406
 407
 408                 /// <summary>
 409                 ///   Returns a temporary storage for a variable of type t as
 410                 ///   a local variable in the current body.
 411                 /// </summary>
 412                 public LocalBuilder GetTemporaryStorage (Type t)
 413                 {
 414                         LocalBuilder location;
 415
 416                         if (temporary_storage != null){
 417                                 location = (LocalBuilder) temporary_storage [t];
 418                                 if (location != null)
 419                                         return location;
 420                         }
 421
 422                         location = ig.DeclareLocal (t);
 423
 424                         return location;
 425                 }
 426
 427                 public void FreeTemporaryStorage (LocalBuilder b)
 428                 {
 429                         // Empty for now.
 430                 }
 431
 432                 /// <summary>
 433                 ///   Current loop begin and end labels.
 434                 /// </summary>
 435                 public Label LoopBegin, LoopEnd;
 436
 437                 /// <summary>
 438                 ///   Whether we are inside a loop and break/continue are possible.
 439                 /// </summary>
 440                 public bool  InLoop;
 441
 442                 /// <summary>
 443                 ///   Default target in a switch statement.   Only valid if
 444                 ///   InSwitch is true
 445                 /// </summary>
 446                 public Label DefaultTarget;
 447
 448                 /// <summary>
 449                 ///   If this is non-null, points to the current switch statement
 450                 /// </summary>
 451                 public Switch Switch;
 452
 453                 /// <summary>
 454                 ///   ReturnValue creates on demand the LocalBuilder for the
 455                 ///   return value from the function.  By default this is not
 456                 ///   used.  This is only required when returns are found inside
 457                 ///   Try or Catch statements.
 458                 /// </summary>
 459                 public LocalBuilder TemporaryReturn ()
 460                 {
 461                         if (return_value == null){
 462                                 return_value = ig.DeclareLocal (ReturnType);
 463                                 ReturnLabel = ig.DefineLabel ();
 464                         }
 465
 466                         return return_value;
 467                 }
 468
 469                 /// <summary>
 470                 ///   A dynamic This that is shared by all variables in a emitcontext.
 471                 ///   Created on demand.
 472                 /// </summary>
 473                 public Expression my_this;
 474                 public Expression This {
 475                         get {
 476                                 if (my_this == null)
 477                                         my_this = new This (loc).Resolve (this);
 478
 479                                 return my_this;
 480                         }
 481                 }
 482         }
 483 }