mcs/gmcs/cfold.cs

   1 //
   2 // cfold.cs: Constant Folding
   3 //
   4 // Author:
   5 //   Miguel de Icaza (miguel@ximian.com)
   6 //
   7 // (C) 2002, 2003 Ximian, Inc.
   8 //
   9
  10 using System;
  11
  12 namespace Mono.CSharp {
  13
  14         public class ConstantFold {
  15
  16                 //
  17                 // Performs the numeric promotions on the left and right expresions
  18                 // and desposits the results on `lc' and `rc'.
  19                 //
  20                 // On success, the types of `lc' and `rc' on output will always match,
  21                 // and the pair will be one of:
  22                 //
  23                 //   (double, double)
  24                 //   (float, float)
  25                 //   (ulong, ulong)
  26                 //   (long, long)
  27                 //   (uint, uint)
  28                 //   (int, int)
  29                 //   (short, short)   (Happens with enumerations with underlying short type)
  30                 //   (ushort, ushort) (Happens with enumerations with underlying short type)
  31                 //
  32                 static void DoConstantNumericPromotions (EmitContext ec, Binary.Operator oper,
  33                                                          ref Constant left, ref Constant right,
  34                                                          Location loc)
  35                 {
  36                         if (left is DoubleConstant || right is DoubleConstant){
  37                                 //
  38                                 // If either side is a double, convert the other to a double
  39                                 //
  40                                 if (!(left is DoubleConstant))
  41                                         left = left.ToDouble (loc);
  42
  43                                 if (!(right is DoubleConstant))
  44                                         right = right.ToDouble (loc);
  45                                 return;
  46                         } else if (left is FloatConstant || right is FloatConstant) {
  47                                 //
  48                                 // If either side is a float, convert the other to a float
  49                                 //
  50                                 if (!(left is FloatConstant))
  51                                         left = left.ToFloat (loc);
  52
  53                                 if (!(right is FloatConstant))
  54                                         right = right.ToFloat (loc);
  55 ;                               return;
  56                         } else if (left is ULongConstant || right is ULongConstant){
  57                                 //
  58                                 // If either operand is of type ulong, the other operand is
  59                                 // converted to type ulong.  or an error ocurrs if the other
  60                                 // operand is of type sbyte, short, int or long
  61                                 //
  62 #if WRONG
  63                                 Constant match, other;
  64 #endif
  65
  66                                 if (left is ULongConstant){
  67 #if WRONG
  68                                         other = right;
  69                                         match = left;
  70 #endif
  71                                         if (!(right is ULongConstant))
  72                                                 right = right.ToULong (loc);
  73                                 } else {
  74 #if WRONG
  75                                         other = left;
  76                                         match = right;
  77 #endif
  78                                         left = left.ToULong (loc);
  79                                 }
  80
  81 #if WRONG
  82                                 if (other is SByteConstant || other is ShortConstant ||
  83                                     other is IntConstant || other is LongConstant){
  84                                         Binary.Error_OperatorAmbiguous
  85                                                 (loc, oper, other.Type, match.Type);
  86                                         left = null;
  87                                         right = null;
  88                                 }
  89 #endif
  90                                 return;
  91                         } else if (left is LongConstant || right is LongConstant){
  92                                 //
  93                                 // If either operand is of type long, the other operand is converted
  94                                 // to type long.
  95                                 //
  96                                 if (!(left is LongConstant))
  97                                         left = left.ToLong (loc);
  98                                 else if (!(right is LongConstant))
  99                                         right = right.ToLong (loc);
 100                                 return;
 101                         } else if (left is UIntConstant || right is UIntConstant){
 102                                 //
 103                                 // If either operand is of type uint, and the other
 104                                 // operand is of type sbyte, short or int, the operands are
 105                                 // converted to type long.
 106                                 //
 107                                 Constant other;
 108                                 if (left is UIntConstant)
 109                                         other = right;
 110                                 else
 111                                         other = left;
 112
 113                                 // Nothing to do.
 114                                 if (other is UIntConstant)
 115                                         return;
 116
 117                                 IntConstant ic = other as IntConstant;
 118                                 if (ic != null){
 119                                         if (ic.Value >= 0){
 120                                                 if (left == other)
 121                                                         left = new UIntConstant ((uint) ic.Value);
 122                                                 else
 123                                                         right = new UIntConstant ((uint) ic.Value);
 124                                                 return;
 125                                         }
 126                                 }
 127
 128                                 if (other is SByteConstant || other is ShortConstant || ic != null){
 129                                         left = left.ToLong (loc);
 130                                         right = right.ToLong (loc);
 131                                 } else {
 132                                         left = left.ToUInt (loc);
 133                                         right = left.ToUInt (loc);
 134                                 }
 135
 136                                 return;
 137                         } else if (left is EnumConstant || right is EnumConstant){
 138                                 //
 139                                 // If either operand is an enum constant, the other one must
 140                                 // be implicitly convertable to that enum's underlying type.
 141                                 //
 142                                 EnumConstant match;
 143                                 Constant other;
 144                                 if (left is EnumConstant){
 145                                         other = right;
 146                                         match = (EnumConstant) left;
 147                                 } else {
 148                                         other = left;
 149                                         match = (EnumConstant) right;
 150                                 }
 151
 152                                 bool need_check = (other is EnumConstant) ||
 153                                         ((oper != Binary.Operator.Addition) &&
 154                                          (oper != Binary.Operator.Subtraction));
 155
 156                                 if (need_check &&
 157                                     !Convert.ImplicitConversionExists (ec, match, other.Type)) {
 158                                         Convert.Error_CannotImplicitConversion (loc, match.Type, other.Type);
 159                                         left = null;
 160                                         right = null;
 161                                         return;
 162                                 }
 163
 164                                 if (left is EnumConstant)
 165                                         left = ((EnumConstant) left).Child;
 166                                 if (right is EnumConstant)
 167                                         right = ((EnumConstant) right).Child;
 168                                 return;
 169
 170                         } else {
 171                                 //
 172                                 // Force conversions to int32
 173                                 //
 174                                 if (!(left is IntConstant))
 175                                         left = left.ToInt (loc);
 176                                 if (!(right is IntConstant))
 177                                         right = right.ToInt (loc);
 178                         }
 179                         return;
 180                 }
 181
 182                 static void Error_CompileTimeOverflow (Location loc)
 183                 {
 184                         Report.Error (220, loc, "The operation overflows at compile time in checked mode");
 185                 }
 186
 187                 /// <summary>
 188                 ///   Constant expression folder for binary operations.
 189                 ///
 190                 ///   Returns null if the expression can not be folded.
 191                 /// </summary>
 192                 static public Expression BinaryFold (EmitContext ec, Binary.Operator oper,
 193                                                      Constant left, Constant right, Location loc)
 194                 {
 195                         Type lt = left.Type;
 196                         Type rt = right.Type;
 197                         Type result_type = null;
 198                         bool bool_res;
 199
 200                         //
 201                         // Enumerator folding
 202                         //
 203                         if (rt == lt && left is EnumConstant)
 204                                 result_type = lt;
 205
 206                         //
 207                         // During an enum evaluation, we need to unwrap enumerations
 208                         //
 209                         if (ec.InEnumContext){
 210                                 if (left is EnumConstant)
 211                                         left = ((EnumConstant) left).Child;
 212
 213                                 if (right is EnumConstant)
 214                                         right = ((EnumConstant) right).Child;
 215                         }
 216
 217                         Type wrap_as;
 218                         Constant result = null;
 219                         switch (oper){
 220                         case Binary.Operator.BitwiseOr:
 221                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
 222                                 if (left == null || right == null)
 223                                         return null;
 224
 225                                 if (left is IntConstant){
 226                                         IntConstant v;
 227                                         int res = ((IntConstant) left).Value | ((IntConstant) right).Value;
 228
 229                                         v = new IntConstant (res);
 230                                         if (result_type == null)
 231                                                 return v;
 232                                         else
 233                                                 return new EnumConstant (v, result_type);
 234                                 } else if (left is UIntConstant){
 235                                         UIntConstant v;
 236                                         uint res = ((UIntConstant)left).Value | ((UIntConstant)right).Value;
 237
 238                                         v = new UIntConstant (res);
 239                                         if (result_type == null)
 240                                                 return v;
 241                                         else
 242                                                 return new EnumConstant (v, result_type);
 243                                 } else if (left is LongConstant){
 244                                         LongConstant v;
 245                                         long res = ((LongConstant)left).Value | ((LongConstant)right).Value;
 246
 247                                         v = new LongConstant (res);
 248                                         if (result_type == null)
 249                                                 return v;
 250                                         else
 251                                                 return new EnumConstant (v, result_type);
 252                                 } else if (left is ULongConstant){
 253                                         ULongConstant v;
 254                                         ulong res = ((ULongConstant)left).Value |
 255                                                 ((ULongConstant)right).Value;
 256
 257                                         v = new ULongConstant (res);
 258                                         if (result_type == null)
 259                                                 return v;
 260                                         else
 261                                                 return new EnumConstant (v, result_type);
 262                                 } else if (left is UShortConstant){
 263                                         UShortConstant v;
 264                                         ushort res = (ushort) (((UShortConstant)left).Value |
 265                                                                ((UShortConstant)right).Value);
 266
 267                                         v = new UShortConstant (res);
 268                                         if (result_type == null)
 269                                                 return v;
 270                                         else
 271                                                 return new EnumConstant (v, result_type);
 272                                 } else if (left is ShortConstant){
 273                                         ShortConstant v;
 274                                         short res = (short) (((ShortConstant)left).Value |
 275                                                              ((ShortConstant)right).Value);
 276
 277                                         v = new ShortConstant (res);
 278                                         if (result_type == null)
 279                                                 return v;
 280                                         else
 281                                                 return new EnumConstant (v, result_type);
 282                                 }
 283                                 break;
 284
 285                         case Binary.Operator.BitwiseAnd:
 286                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
 287                                 if (left == null || right == null)
 288                                         return null;
 289
 290                                 if (left is IntConstant){
 291                                         IntConstant v;
 292                                         int res = ((IntConstant) left).Value & ((IntConstant) right).Value;
 293
 294                                         v = new IntConstant (res);
 295                                         if (result_type == null)
 296                                                 return v;
 297                                         else
 298                                                 return new EnumConstant (v, result_type);
 299                                 } else if (left is UIntConstant){
 300                                         UIntConstant v;
 301                                         uint res = ((UIntConstant)left).Value & ((UIntConstant)right).Value;
 302
 303                                         v = new UIntConstant (res);
 304                                         if (result_type == null)
 305                                                 return v;
 306                                         else
 307                                                 return new EnumConstant (v, result_type);
 308                                 } else if (left is LongConstant){
 309                                         LongConstant v;
 310                                         long res = ((LongConstant)left).Value & ((LongConstant)right).Value;
 311
 312                                         v = new LongConstant (res);
 313                                         if (result_type == null)
 314                                                 return v;
 315                                         else
 316                                                 return new EnumConstant (v, result_type);
 317                                 } else if (left is ULongConstant){
 318                                         ULongConstant v;
 319                                         ulong res = ((ULongConstant)left).Value &
 320                                                 ((ULongConstant)right).Value;
 321
 322                                         v = new ULongConstant (res);
 323                                         if (result_type == null)
 324                                                 return v;
 325                                         else
 326                                                 return new EnumConstant (v, result_type);
 327                                 } else if (left is UShortConstant){
 328                                         UShortConstant v;
 329                                         ushort res = (ushort) (((UShortConstant)left).Value &
 330                                                                ((UShortConstant)right).Value);
 331
 332                                         v = new UShortConstant (res);
 333                                         if (result_type == null)
 334                                                 return v;
 335                                         else
 336                                                 return new EnumConstant (v, result_type);
 337                                 } else if (left is ShortConstant){
 338                                         ShortConstant v;
 339                                         short res = (short) (((ShortConstant)left).Value &
 340                                                              ((ShortConstant)right).Value);
 341
 342                                         v = new ShortConstant (res);
 343                                         if (result_type == null)
 344                                                 return v;
 345                                         else
 346                                                 return new EnumConstant (v, result_type);
 347                                 }
 348                                 break;
 349
 350                         case Binary.Operator.ExclusiveOr:
 351                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
 352                                 if (left == null || right == null)
 353                                         return null;
 354
 355                                 if (left is IntConstant){
 356                                         IntConstant v;
 357                                         int res = ((IntConstant) left).Value ^ ((IntConstant) right).Value;
 358
 359                                         v = new IntConstant (res);
 360                                         if (result_type == null)
 361                                                 return v;
 362                                         else
 363                                                 return new EnumConstant (v, result_type);
 364                                 } else if (left is UIntConstant){
 365                                         UIntConstant v;
 366                                         uint res = ((UIntConstant)left).Value ^ ((UIntConstant)right).Value;
 367
 368                                         v = new UIntConstant (res);
 369                                         if (result_type == null)
 370                                                 return v;
 371                                         else
 372                                                 return new EnumConstant (v, result_type);
 373                                 } else if (left is LongConstant){
 374                                         LongConstant v;
 375                                         long res = ((LongConstant)left).Value ^ ((LongConstant)right).Value;
 376
 377                                         v = new LongConstant (res);
 378                                         if (result_type == null)
 379                                                 return v;
 380                                         else
 381                                                 return new EnumConstant (v, result_type);
 382                                 } else if (left is ULongConstant){
 383                                         ULongConstant v;
 384                                         ulong res = ((ULongConstant)left).Value ^
 385                                                 ((ULongConstant)right).Value;
 386
 387                                         v = new ULongConstant (res);
 388                                         if (result_type == null)
 389                                                 return v;
 390                                         else
 391                                                 return new EnumConstant (v, result_type);
 392                                 } else if (left is UShortConstant){
 393                                         UShortConstant v;
 394                                         ushort res = (ushort) (((UShortConstant)left).Value ^
 395                                                                ((UShortConstant)right).Value);
 396
 397                                         v = new UShortConstant (res);
 398                                         if (result_type == null)
 399                                                 return v;
 400                                         else
 401                                                 return new EnumConstant (v, result_type);
 402                                 } else if (left is ShortConstant){
 403                                         ShortConstant v;
 404                                         short res = (short)(((ShortConstant)left).Value ^
 405                                                             ((ShortConstant)right).Value);
 406
 407                                         v = new ShortConstant (res);
 408                                         if (result_type == null)
 409                                                 return v;
 410                                         else
 411                                                 return new EnumConstant (v, result_type);
 412                                 }
 413                                 break;
 414
 415                         case Binary.Operator.Addition:
 416                                 bool left_is_string = left is StringConstant;
 417                                 bool right_is_string = right is StringConstant;
 418
 419                                 //
 420                                 // If both sides are strings, then concatenate, if
 421                                 // one is a string, and the other is not, then defer
 422                                 // to runtime concatenation
 423                                 //
 424                                 wrap_as = null;
 425                                 if (left_is_string || right_is_string){
 426                                         if (left_is_string && right_is_string)
 427                                                 return new StringConstant (
 428                                                         ((StringConstant) left).Value +
 429                                                         ((StringConstant) right).Value);
 430
 431                                         return null;
 432                                 }
 433
 434                                 //
 435                                 // handle "E operator + (E x, U y)"
 436                                 // handle "E operator + (Y y, E x)"
 437                                 //
 438                                 // note that E operator + (E x, E y) is invalid
 439                                 //
 440                                 if (left is EnumConstant){
 441                                         if (right is EnumConstant){
 442                                                 return null;
 443                                         }
 444                                         if (((EnumConstant) left).Child.Type != right.Type)
 445                                                 return null;
 446
 447                                         wrap_as = left.Type;
 448                                 } else if (right is EnumConstant){
 449                                         if (((EnumConstant) right).Child.Type != left.Type)
 450                                                 return null;
 451                                         wrap_as = right.Type;
 452                                 }
 453
 454                                 result = null;
 455                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
 456                                 if (left == null || right == null)
 457                                         return null;
 458
 459                                 try {
 460                                         if (left is DoubleConstant){
 461                                                 double res;
 462
 463                                                 if (ec.ConstantCheckState)
 464                                                         res = checked (((DoubleConstant) left).Value +
 465                                                                        ((DoubleConstant) right).Value);
 466                                                 else
 467                                                         res = unchecked (((DoubleConstant) left).Value +
 468                                                                          ((DoubleConstant) right).Value);
 469
 470                                                 result = new DoubleConstant (res);
 471                                         } else if (left is FloatConstant){
 472                                                 float res;
 473
 474                                                 if (ec.ConstantCheckState)
 475                                                         res = checked (((FloatConstant) left).Value +
 476                                                                        ((FloatConstant) right).Value);
 477                                                 else
 478                                                         res = unchecked (((FloatConstant) left).Value +
 479                                                                          ((FloatConstant) right).Value);
 480
 481                                                 result = new FloatConstant (res);
 482                                         } else if (left is ULongConstant){
 483                                                 ulong res;
 484
 485                                                 if (ec.ConstantCheckState)
 486                                                         res = checked (((ULongConstant) left).Value +
 487                                                                        ((ULongConstant) right).Value);
 488                                                 else
 489                                                         res = unchecked (((ULongConstant) left).Value +
 490                                                                          ((ULongConstant) right).Value);
 491
 492                                                 result = new ULongConstant (res);
 493                                         } else if (left is LongConstant){
 494                                                 long res;
 495
 496                                                 if (ec.ConstantCheckState)
 497                                                         res = checked (((LongConstant) left).Value +
 498                                                                        ((LongConstant) right).Value);
 499                                                 else
 500                                                         res = unchecked (((LongConstant) left).Value +
 501                                                                          ((LongConstant) right).Value);
 502
 503                                                 result = new LongConstant (res);
 504                                         } else if (left is UIntConstant){
 505                                                 uint res;
 506
 507                                                 if (ec.ConstantCheckState)
 508                                                         res = checked (((UIntConstant) left).Value +
 509                                                                        ((UIntConstant) right).Value);
 510                                                 else
 511                                                         res = unchecked (((UIntConstant) left).Value +
 512                                                                          ((UIntConstant) right).Value);
 513
 514                                                 result = new UIntConstant (res);
 515                                         } else if (left is IntConstant){
 516                                                 int res;
 517
 518                                                 if (ec.ConstantCheckState)
 519                                                         res = checked (((IntConstant) left).Value +
 520                                                                        ((IntConstant) right).Value);
 521                                                 else
 522                                                         res = unchecked (((IntConstant) left).Value +
 523                                                                          ((IntConstant) right).Value);
 524
 525                                                 result = new IntConstant (res);
 526                                         } else {
 527                                                 throw new Exception ( "Unexepected input: " + left);
 528                                         }
 529                                 } catch (OverflowException){
 530                                         Error_CompileTimeOverflow (loc);
 531                                 }
 532
 533                                 if (wrap_as != null)
 534                                         return new EnumConstant (result, wrap_as);
 535                                 else
 536                                         return result;
 537
 538                         case Binary.Operator.Subtraction:
 539                                 //
 540                                 // handle "E operator - (E x, U y)"
 541                                 // handle "E operator - (Y y, E x)"
 542                                 // handle "U operator - (E x, E y)"
 543                                 //
 544                                 wrap_as = null;
 545                                 if (left is EnumConstant){
 546                                         if (right is EnumConstant){
 547                                                 if (left.Type == right.Type)
 548                                                         wrap_as = TypeManager.EnumToUnderlying (left.Type);
 549                                                 else
 550                                                         return null;
 551                                         }
 552                                         if (((EnumConstant) left).Child.Type != right.Type)
 553                                                 return null;
 554
 555                                         wrap_as = left.Type;
 556                                 } else if (right is EnumConstant){
 557                                         if (((EnumConstant) right).Child.Type != left.Type)
 558                                                 return null;
 559                                         wrap_as = right.Type;
 560                                 }
 561
 562                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
 563                                 if (left == null || right == null)
 564                                         return null;
 565
 566                                 try {
 567                                         if (left is DoubleConstant){
 568                                                 double res;
 569
 570                                                 if (ec.ConstantCheckState)
 571                                                         res = checked (((DoubleConstant) left).Value -
 572                                                                        ((DoubleConstant) right).Value);
 573                                                 else
 574                                                         res = unchecked (((DoubleConstant) left).Value -
 575                                                                          ((DoubleConstant) right).Value);
 576
 577                                                 result = new DoubleConstant (res);
 578                                         } else if (left is FloatConstant){
 579                                                 float res;
 580
 581                                                 if (ec.ConstantCheckState)
 582                                                         res = checked (((FloatConstant) left).Value -
 583                                                                        ((FloatConstant) right).Value);
 584                                                 else
 585                                                         res = unchecked (((FloatConstant) left).Value -
 586                                                                          ((FloatConstant) right).Value);
 587
 588                                                 result = new FloatConstant (res);
 589                                         } else if (left is ULongConstant){
 590                                                 ulong res;
 591
 592                                                 if (ec.ConstantCheckState)
 593                                                         res = checked (((ULongConstant) left).Value -
 594                                                                        ((ULongConstant) right).Value);
 595                                                 else
 596                                                         res = unchecked (((ULongConstant) left).Value -
 597                                                                          ((ULongConstant) right).Value);
 598
 599                                                 result = new ULongConstant (res);
 600                                         } else if (left is LongConstant){
 601                                                 long res;
 602
 603                                                 if (ec.ConstantCheckState)
 604                                                         res = checked (((LongConstant) left).Value -
 605                                                                        ((LongConstant) right).Value);
 606                                                 else
 607                                                         res = unchecked (((LongConstant) left).Value -
 608                                                                          ((LongConstant) right).Value);
 609
 610                                                 result = new LongConstant (res);
 611                                         } else if (left is UIntConstant){
 612                                                 uint res;
 613
 614                                                 if (ec.ConstantCheckState)
 615                                                         res = checked (((UIntConstant) left).Value -
 616                                                                        ((UIntConstant) right).Value);
 617                                                 else
 618                                                         res = unchecked (((UIntConstant) left).Value -
 619                                                                          ((UIntConstant) right).Value);
 620
 621                                                 result = new UIntConstant (res);
 622                                         } else if (left is IntConstant){
 623                                                 int res;
 624
 625                                                 if (ec.ConstantCheckState)
 626                                                         res = checked (((IntConstant) left).Value -
 627                                                                        ((IntConstant) right).Value);
 628                                                 else
 629                                                         res = unchecked (((IntConstant) left).Value -
 630                                                                          ((IntConstant) right).Value);
 631
 632                                                 result = new IntConstant (res);
 633                                         } else {
 634                                                 throw new Exception ( "Unexepected input: " + left);
 635                                         }
 636                                 } catch (OverflowException){
 637                                         Error_CompileTimeOverflow (loc);
 638                                 }
 639                                 if (wrap_as != null)
 640                                         return new EnumConstant (result, wrap_as);
 641                                 else
 642                                         return result;
 643
 644                         case Binary.Operator.Multiply:
 645                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
 646                                 if (left == null || right == null)
 647                                         return null;
 648
 649                                 try {
 650                                         if (left is DoubleConstant){
 651                                                 double res;
 652
 653                                                 if (ec.ConstantCheckState)
 654                                                         res = checked (((DoubleConstant) left).Value *
 655                                                                        ((DoubleConstant) right).Value);
 656                                                 else
 657                                                         res = unchecked (((DoubleConstant) left).Value *
 658                                                                          ((DoubleConstant) right).Value);
 659
 660                                                 return new DoubleConstant (res);
 661                                         } else if (left is FloatConstant){
 662                                                 float res;
 663
 664                                                 if (ec.ConstantCheckState)
 665                                                         res = checked (((FloatConstant) left).Value *
 666                                                                        ((FloatConstant) right).Value);
 667                                                 else
 668                                                         res = unchecked (((FloatConstant) left).Value *
 669                                                                          ((FloatConstant) right).Value);
 670
 671                                                 return new FloatConstant (res);
 672                                         } else if (left is ULongConstant){
 673                                                 ulong res;
 674
 675                                                 if (ec.ConstantCheckState)
 676                                                         res = checked (((ULongConstant) left).Value *
 677                                                                        ((ULongConstant) right).Value);
 678                                                 else
 679                                                         res = unchecked (((ULongConstant) left).Value *
 680                                                                          ((ULongConstant) right).Value);
 681
 682                                                 return new ULongConstant (res);
 683                                         } else if (left is LongConstant){
 684                                                 long res;
 685
 686                                                 if (ec.ConstantCheckState)
 687                                                         res = checked (((LongConstant) left).Value *
 688                                                                        ((LongConstant) right).Value);
 689                                                 else
 690                                                         res = unchecked (((LongConstant) left).Value *
 691                                                                          ((LongConstant) right).Value);
 692
 693                                                 return new LongConstant (res);
 694                                         } else if (left is UIntConstant){
 695                                                 uint res;
 696
 697                                                 if (ec.ConstantCheckState)
 698                                                         res = checked (((UIntConstant) left).Value *
 699                                                                        ((UIntConstant) right).Value);
 700                                                 else
 701                                                         res = unchecked (((UIntConstant) left).Value *
 702                                                                          ((UIntConstant) right).Value);
 703
 704                                                 return new UIntConstant (res);
 705                                         } else if (left is IntConstant){
 706                                                 int res;
 707
 708                                                 if (ec.ConstantCheckState)
 709                                                         res = checked (((IntConstant) left).Value *
 710                                                                        ((IntConstant) right).Value);
 711                                                 else
 712                                                         res = unchecked (((IntConstant) left).Value *
 713                                                                          ((IntConstant) right).Value);
 714
 715                                                 return new IntConstant (res);
 716                                         } else {
 717                                                 throw new Exception ( "Unexepected input: " + left);
 718                                         }
 719                                 } catch (OverflowException){
 720                                         Error_CompileTimeOverflow (loc);
 721                                 }
 722                                 break;
 723
 724                         case Binary.Operator.Division:
 725                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
 726                                 if (left == null || right == null)
 727                                         return null;
 728
 729                                 try {
 730                                         if (left is DoubleConstant){
 731                                                 double res;
 732
 733                                                 if (ec.ConstantCheckState)
 734                                                         res = checked (((DoubleConstant) left).Value /
 735                                                                        ((DoubleConstant) right).Value);
 736                                                 else
 737                                                         res = unchecked (((DoubleConstant) left).Value /
 738                                                                          ((DoubleConstant) right).Value);
 739
 740                                                 return new DoubleConstant (res);
 741                                         } else if (left is FloatConstant){
 742                                                 float res;
 743
 744                                                 if (ec.ConstantCheckState)
 745                                                         res = checked (((FloatConstant) left).Value /
 746                                                                        ((FloatConstant) right).Value);
 747                                                 else
 748                                                         res = unchecked (((FloatConstant) left).Value /
 749                                                                          ((FloatConstant) right).Value);
 750
 751                                                 return new FloatConstant (res);
 752                                         } else if (left is ULongConstant){
 753                                                 ulong res;
 754
 755                                                 if (ec.ConstantCheckState)
 756                                                         res = checked (((ULongConstant) left).Value /
 757                                                                        ((ULongConstant) right).Value);
 758                                                 else
 759                                                         res = unchecked (((ULongConstant) left).Value /
 760                                                                          ((ULongConstant) right).Value);
 761
 762                                                 return new ULongConstant (res);
 763                                         } else if (left is LongConstant){
 764                                                 long res;
 765
 766                                                 if (ec.ConstantCheckState)
 767                                                         res = checked (((LongConstant) left).Value /
 768                                                                        ((LongConstant) right).Value);
 769                                                 else
 770                                                         res = unchecked (((LongConstant) left).Value /
 771                                                                          ((LongConstant) right).Value);
 772
 773                                                 return new LongConstant (res);
 774                                         } else if (left is UIntConstant){
 775                                                 uint res;
 776
 777                                                 if (ec.ConstantCheckState)
 778                                                         res = checked (((UIntConstant) left).Value /
 779                                                                        ((UIntConstant) right).Value);
 780                                                 else
 781                                                         res = unchecked (((UIntConstant) left).Value /
 782                                                                          ((UIntConstant) right).Value);
 783
 784                                                 return new UIntConstant (res);
 785                                         } else if (left is IntConstant){
 786                                                 int res;
 787
 788                                                 if (ec.ConstantCheckState)
 789                                                         res = checked (((IntConstant) left).Value /
 790                                                                        ((IntConstant) right).Value);
 791                                                 else
 792                                                         res = unchecked (((IntConstant) left).Value /
 793                                                                          ((IntConstant) right).Value);
 794
 795                                                 return new IntConstant (res);
 796                                         } else {
 797                                                 throw new Exception ( "Unexepected input: " + left);
 798                                         }
 799                                 } catch (OverflowException){
 800                                         Error_CompileTimeOverflow (loc);
 801
 802                                 } catch (DivideByZeroException) {
 803                                         Report.Error (020, loc, "Division by constant zero");
 804                                 }
 805
 806                                 break;
 807
 808                         case Binary.Operator.Modulus:
 809                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
 810                                 if (left == null || right == null)
 811                                         return null;
 812
 813                                 try {
 814                                         if (left is DoubleConstant){
 815                                                 double res;
 816
 817                                                 if (ec.ConstantCheckState)
 818                                                         res = checked (((DoubleConstant) left).Value %
 819                                                                        ((DoubleConstant) right).Value);
 820                                                 else
 821                                                         res = unchecked (((DoubleConstant) left).Value %
 822                                                                          ((DoubleConstant) right).Value);
 823
 824                                                 return new DoubleConstant (res);
 825                                         } else if (left is FloatConstant){
 826                                                 float res;
 827
 828                                                 if (ec.ConstantCheckState)
 829                                                         res = checked (((FloatConstant) left).Value %
 830                                                                        ((FloatConstant) right).Value);
 831                                                 else
 832                                                         res = unchecked (((FloatConstant) left).Value %
 833                                                                          ((FloatConstant) right).Value);
 834
 835                                                 return new FloatConstant (res);
 836                                         } else if (left is ULongConstant){
 837                                                 ulong res;
 838
 839                                                 if (ec.ConstantCheckState)
 840                                                         res = checked (((ULongConstant) left).Value %
 841                                                                        ((ULongConstant) right).Value);
 842                                                 else
 843                                                         res = unchecked (((ULongConstant) left).Value %
 844                                                                          ((ULongConstant) right).Value);
 845
 846                                                 return new ULongConstant (res);
 847                                         } else if (left is LongConstant){
 848                                                 long res;
 849
 850                                                 if (ec.ConstantCheckState)
 851                                                         res = checked (((LongConstant) left).Value %
 852                                                                        ((LongConstant) right).Value);
 853                                                 else
 854                                                         res = unchecked (((LongConstant) left).Value %
 855                                                                          ((LongConstant) right).Value);
 856
 857                                                 return new LongConstant (res);
 858                                         } else if (left is UIntConstant){
 859                                                 uint res;
 860
 861                                                 if (ec.ConstantCheckState)
 862                                                         res = checked (((UIntConstant) left).Value %
 863                                                                        ((UIntConstant) right).Value);
 864                                                 else
 865                                                         res = unchecked (((UIntConstant) left).Value %
 866                                                                          ((UIntConstant) right).Value);
 867
 868                                                 return new UIntConstant (res);
 869                                         } else if (left is IntConstant){
 870                                                 int res;
 871
 872                                                 if (ec.ConstantCheckState)
 873                                                         res = checked (((IntConstant) left).Value %
 874                                                                        ((IntConstant) right).Value);
 875                                                 else
 876                                                         res = unchecked (((IntConstant) left).Value %
 877                                                                          ((IntConstant) right).Value);
 878
 879                                                 return new IntConstant (res);
 880                                         } else {
 881                                                 throw new Exception ( "Unexepected input: " + left);
 882                                         }
 883                                 } catch (DivideByZeroException){
 884                                         Report.Error (020, loc, "Division by constant zero");
 885                                 } catch (OverflowException){
 886                                         Error_CompileTimeOverflow (loc);
 887                                 }
 888                                 break;
 889
 890                                 //
 891                                 // There is no overflow checking on left shift
 892                                 //
 893                         case Binary.Operator.LeftShift:
 894                                 IntConstant ic = right.ToInt (loc);
 895                                 if (ic == null){
 896                                         Binary.Error_OperatorCannotBeApplied (loc, "<<", lt, rt);
 897                                         return null;
 898                                 }
 899                                 int lshift_val = ic.Value;
 900
 901                                 IntConstant lic;
 902                                 if ((lic = left.ConvertToInt ()) != null)
 903                                         return new IntConstant (lic.Value << lshift_val);
 904
 905                                 UIntConstant luic;
 906                                 if ((luic = left.ConvertToUInt ()) != null)
 907                                         return new UIntConstant (luic.Value << lshift_val);
 908
 909                                 LongConstant llc;
 910                                 if ((llc = left.ConvertToLong ()) != null)
 911                                         return new LongConstant (llc.Value << lshift_val);
 912
 913                                 ULongConstant lulc;
 914                                 if ((lulc = left.ConvertToULong ()) != null)
 915                                         return new ULongConstant (lulc.Value << lshift_val);
 916
 917                                 Binary.Error_OperatorCannotBeApplied (loc, "<<", lt, rt);
 918                                 break;
 919
 920                                 //
 921                                 // There is no overflow checking on right shift
 922                                 //
 923                         case Binary.Operator.RightShift:
 924                                 IntConstant sic = right.ToInt (loc);
 925                                 if (sic == null){
 926                                         Binary.Error_OperatorCannotBeApplied (loc, ">>", lt, rt);
 927                                         return null;
 928                                 }
 929                                 int rshift_val = sic.Value;
 930
 931                                 IntConstant ric;
 932                                 if ((ric = left.ConvertToInt ()) != null)
 933                                         return new IntConstant (ric.Value >> rshift_val);
 934
 935                                 UIntConstant ruic;
 936                                 if ((ruic = left.ConvertToUInt ()) != null)
 937                                         return new UIntConstant (ruic.Value >> rshift_val);
 938
 939                                 LongConstant rlc;
 940                                 if ((rlc = left.ConvertToLong ()) != null)
 941                                         return new LongConstant (rlc.Value >> rshift_val);
 942
 943                                 ULongConstant rulc;
 944                                 if ((rulc = left.ConvertToULong ()) != null)
 945                                         return new ULongConstant (rulc.Value >> rshift_val);
 946
 947                                 Binary.Error_OperatorCannotBeApplied (loc, ">>", lt, rt);
 948                                 break;
 949
 950                         case Binary.Operator.LogicalAnd:
 951                                 if (left is BoolConstant && right is BoolConstant){
 952                                         return new BoolConstant (
 953                                                 ((BoolConstant) left).Value &&
 954                                                 ((BoolConstant) right).Value);
 955                                 }
 956                                 break;
 957
 958                         case Binary.Operator.LogicalOr:
 959                                 if (left is BoolConstant && right is BoolConstant){
 960                                         return new BoolConstant (
 961                                                 ((BoolConstant) left).Value ||
 962                                                 ((BoolConstant) right).Value);
 963                                 }
 964                                 break;
 965
 966                         case Binary.Operator.Equality:
 967                                 if (left is BoolConstant && right is BoolConstant){
 968                                         return new BoolConstant (
 969                                                 ((BoolConstant) left).Value ==
 970                                                 ((BoolConstant) right).Value);
 971
 972                                 }
 973                                 if (left is NullLiteral){
 974                                         if (right is NullLiteral)
 975                                                 return new BoolConstant (true);
 976                                         else if (right is StringConstant)
 977                                                 return new BoolConstant (
 978                                                         ((StringConstant) right).Value == null);
 979                                 } else if (right is NullLiteral){
 980                                         if (left is NullLiteral)
 981                                                 return new BoolConstant (true);
 982                                         else if (left is StringConstant)
 983                                                 return new BoolConstant (
 984                                                         ((StringConstant) left).Value == null);
 985                                 }
 986                                 if (left is StringConstant && right is StringConstant){
 987                                         return new BoolConstant (
 988                                                 ((StringConstant) left).Value ==
 989                                                 ((StringConstant) right).Value);
 990
 991                                 }
 992
 993                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
 994                                 if (left == null || right == null)
 995                                         return null;
 996
 997                                 bool_res = false;
 998                                 if (left is DoubleConstant)
 999                                         bool_res = ((DoubleConstant) left).Value ==
1000                                                 ((DoubleConstant) right).Value;
1001                                 else if (left is FloatConstant)
1002                                         bool_res = ((FloatConstant) left).Value ==
1003                                                 ((FloatConstant) right).Value;
1004                                 else if (left is ULongConstant)
1005                                         bool_res = ((ULongConstant) left).Value ==
1006                                                 ((ULongConstant) right).Value;
1007                                 else if (left is LongConstant)
1008                                         bool_res = ((LongConstant) left).Value ==
1009                                                 ((LongConstant) right).Value;
1010                                 else if (left is UIntConstant)
1011                                         bool_res = ((UIntConstant) left).Value ==
1012                                                 ((UIntConstant) right).Value;
1013                                 else if (left is IntConstant)
1014                                         bool_res = ((IntConstant) left).Value ==
1015                                                 ((IntConstant) right).Value;
1016                                 else
1017                                         return null;
1018
1019                                 return new BoolConstant (bool_res);
1020
1021                         case Binary.Operator.Inequality:
1022                                 if (left is BoolConstant && right is BoolConstant){
1023                                         return new BoolConstant (
1024                                                 ((BoolConstant) left).Value !=
1025                                                 ((BoolConstant) right).Value);
1026                                 }
1027                                 if (left is NullLiteral){
1028                                         if (right is NullLiteral)
1029                                                 return new BoolConstant (false);
1030                                         else if (right is StringConstant)
1031                                                 return new BoolConstant (
1032                                                         ((StringConstant) right).Value != null);
1033                                 } else if (right is NullLiteral){
1034                                         if (left is NullLiteral)
1035                                                 return new BoolConstant (false);
1036                                         else if (left is StringConstant)
1037                                                 return new BoolConstant (
1038                                                         ((StringConstant) left).Value != null);
1039                                 }
1040                                 if (left is StringConstant && right is StringConstant){
1041                                         return new BoolConstant (
1042                                                 ((StringConstant) left).Value !=
1043                                                 ((StringConstant) right).Value);
1044
1045                                 }
1046                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
1047                                 if (left == null || right == null)
1048                                         return null;
1049
1050                                 bool_res = false;
1051                                 if (left is DoubleConstant)
1052                                         bool_res = ((DoubleConstant) left).Value !=
1053                                                 ((DoubleConstant) right).Value;
1054                                 else if (left is FloatConstant)
1055                                         bool_res = ((FloatConstant) left).Value !=
1056                                                 ((FloatConstant) right).Value;
1057                                 else if (left is ULongConstant)
1058                                         bool_res = ((ULongConstant) left).Value !=
1059                                                 ((ULongConstant) right).Value;
1060                                 else if (left is LongConstant)
1061                                         bool_res = ((LongConstant) left).Value !=
1062                                                 ((LongConstant) right).Value;
1063                                 else if (left is UIntConstant)
1064                                         bool_res = ((UIntConstant) left).Value !=
1065                                                 ((UIntConstant) right).Value;
1066                                 else if (left is IntConstant)
1067                                         bool_res = ((IntConstant) left).Value !=
1068                                                 ((IntConstant) right).Value;
1069                                 else
1070                                         return null;
1071
1072                                 return new BoolConstant (bool_res);
1073
1074                         case Binary.Operator.LessThan:
1075                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
1076                                 if (left == null || right == null)
1077                                         return null;
1078
1079                                 bool_res = false;
1080                                 if (left is DoubleConstant)
1081                                         bool_res = ((DoubleConstant) left).Value <
1082                                                 ((DoubleConstant) right).Value;
1083                                 else if (left is FloatConstant)
1084                                         bool_res = ((FloatConstant) left).Value <
1085                                                 ((FloatConstant) right).Value;
1086                                 else if (left is ULongConstant)
1087                                         bool_res = ((ULongConstant) left).Value <
1088                                                 ((ULongConstant) right).Value;
1089                                 else if (left is LongConstant)
1090                                         bool_res = ((LongConstant) left).Value <
1091                                                 ((LongConstant) right).Value;
1092                                 else if (left is UIntConstant)
1093                                         bool_res = ((UIntConstant) left).Value <
1094                                                 ((UIntConstant) right).Value;
1095                                 else if (left is IntConstant)
1096                                         bool_res = ((IntConstant) left).Value <
1097                                                 ((IntConstant) right).Value;
1098                                 else
1099                                         return null;
1100
1101                                 return new BoolConstant (bool_res);
1102
1103                         case Binary.Operator.GreaterThan:
1104                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
1105                                 if (left == null || right == null)
1106                                         return null;
1107
1108                                 bool_res = false;
1109                                 if (left is DoubleConstant)
1110                                         bool_res = ((DoubleConstant) left).Value >
1111                                                 ((DoubleConstant) right).Value;
1112                                 else if (left is FloatConstant)
1113                                         bool_res = ((FloatConstant) left).Value >
1114                                                 ((FloatConstant) right).Value;
1115                                 else if (left is ULongConstant)
1116                                         bool_res = ((ULongConstant) left).Value >
1117                                                 ((ULongConstant) right).Value;
1118                                 else if (left is LongConstant)
1119                                         bool_res = ((LongConstant) left).Value >
1120                                                 ((LongConstant) right).Value;
1121                                 else if (left is UIntConstant)
1122                                         bool_res = ((UIntConstant) left).Value >
1123                                                 ((UIntConstant) right).Value;
1124                                 else if (left is IntConstant)
1125                                         bool_res = ((IntConstant) left).Value >
1126                                                 ((IntConstant) right).Value;
1127                                 else
1128                                         return null;
1129
1130                                 return new BoolConstant (bool_res);
1131
1132                         case Binary.Operator.GreaterThanOrEqual:
1133                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
1134                                 if (left == null || right == null)
1135                                         return null;
1136
1137                                 bool_res = false;
1138                                 if (left is DoubleConstant)
1139                                         bool_res = ((DoubleConstant) left).Value >=
1140                                                 ((DoubleConstant) right).Value;
1141                                 else if (left is FloatConstant)
1142                                         bool_res = ((FloatConstant) left).Value >=
1143                                                 ((FloatConstant) right).Value;
1144                                 else if (left is ULongConstant)
1145                                         bool_res = ((ULongConstant) left).Value >=
1146                                                 ((ULongConstant) right).Value;
1147                                 else if (left is LongConstant)
1148                                         bool_res = ((LongConstant) left).Value >=
1149                                                 ((LongConstant) right).Value;
1150                                 else if (left is UIntConstant)
1151                                         bool_res = ((UIntConstant) left).Value >=
1152                                                 ((UIntConstant) right).Value;
1153                                 else if (left is IntConstant)
1154                                         bool_res = ((IntConstant) left).Value >=
1155                                                 ((IntConstant) right).Value;
1156                                 else
1157                                         return null;
1158
1159                                 return new BoolConstant (bool_res);
1160
1161                         case Binary.Operator.LessThanOrEqual:
1162                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
1163                                 if (left == null || right == null)
1164                                         return null;
1165
1166                                 bool_res = false;
1167                                 if (left is DoubleConstant)
1168                                         bool_res = ((DoubleConstant) left).Value <=
1169                                                 ((DoubleConstant) right).Value;
1170                                 else if (left is FloatConstant)
1171                                         bool_res = ((FloatConstant) left).Value <=
1172                                                 ((FloatConstant) right).Value;
1173                                 else if (left is ULongConstant)
1174                                         bool_res = ((ULongConstant) left).Value <=
1175                                                 ((ULongConstant) right).Value;
1176                                 else if (left is LongConstant)
1177                                         bool_res = ((LongConstant) left).Value <=
1178                                                 ((LongConstant) right).Value;
1179                                 else if (left is UIntConstant)
1180                                         bool_res = ((UIntConstant) left).Value <=
1181                                                 ((UIntConstant) right).Value;
1182                                 else if (left is IntConstant)
1183                                         bool_res = ((IntConstant) left).Value <=
1184                                                 ((IntConstant) right).Value;
1185                                 else
1186                                         return null;
1187
1188                                 return new BoolConstant (bool_res);
1189                         }
1190
1191                         return null;
1192                 }
1193         }
1194 }