mcs/bmcs/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 DecimalConstant || right is DecimalConstant) {
 138                                 if (!(left is DecimalConstant))
 139                                         left = left.ToDecimal (loc);
 140                                 else if (!(right is DecimalConstant))
 141                                         right = right.ToDecimal (loc);
 142                                 return;
 143                         } else if (left is EnumConstant || right is EnumConstant){
 144                                 //
 145                                 // If either operand is an enum constant, the other one must
 146                                 // be implicitly convertable to that enum's underlying type.
 147                                 //
 148                                 EnumConstant match;
 149                                 Constant other;
 150                                 if (left is EnumConstant){
 151                                         other = right;
 152                                         match = (EnumConstant) left;
 153                                 } else {
 154                                         other = left;
 155                                         match = (EnumConstant) right;
 156                                 }
 157
 158                                 bool need_check = (other is EnumConstant) ||
 159                                         ((oper != Binary.Operator.Addition) &&
 160                                          (oper != Binary.Operator.Subtraction));
 161
 162                                 if (need_check &&
 163                                     !Convert.WideningConversionExists (ec, match, other.Type)) {
 164                                         Convert.Error_CannotWideningConversion (loc, match.Type, other.Type);
 165                                         left = null;
 166                                         right = null;
 167                                         return;
 168                                 }
 169
 170                                 if (left is EnumConstant)
 171                                         left = ((EnumConstant) left).Child;
 172                                 if (right is EnumConstant)
 173                                         right = ((EnumConstant) right).Child;
 174
 175                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
 176                                 return;
 177
 178                         } else {
 179                                 //
 180                                 // Force conversions to int32
 181                                 //
 182                                 if (!(left is IntConstant))
 183                                         left = left.ToInt (loc);
 184                                 if (!(right is IntConstant))
 185                                         right = right.ToInt (loc);
 186                         }
 187                         return;
 188                 }
 189
 190                 static void Error_CompileTimeOverflow (Location loc)
 191                 {
 192                         Report.Error (220, loc, "The operation overflows at compile time in checked mode");
 193                 }
 194
 195                 /// <summary>
 196                 ///   Constant expression folder for binary operations.
 197                 ///
 198                 ///   Returns null if the expression can not be folded.
 199                 /// </summary>
 200                 static public Expression BinaryFold (EmitContext ec, Binary.Operator oper,
 201                                                      Constant left, Constant right, Location loc)
 202                 {
 203                         Type lt = left.Type;
 204                         Type rt = right.Type;
 205                         Type result_type = null;
 206                         bool bool_res;
 207
 208                         //
 209                         // Enumerator folding
 210                         //
 211                         if (rt == lt && left is EnumConstant)
 212                                 result_type = lt;
 213
 214                         //
 215                         // During an enum evaluation, we need to unwrap enumerations
 216                         //
 217                         if (ec.InEnumContext){
 218                                 if (left is EnumConstant)
 219                                         left = ((EnumConstant) left).Child;
 220
 221                                 if (right is EnumConstant)
 222                                         right = ((EnumConstant) right).Child;
 223                         }
 224
 225                         Type wrap_as;
 226                         Constant result = null;
 227                         switch (oper){
 228                         case Binary.Operator.BitwiseOr:
 229                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
 230                                 if (left == null || right == null)
 231                                         return null;
 232
 233                                 if (left is IntConstant){
 234                                         IntConstant v;
 235                                         int res = ((IntConstant) left).Value | ((IntConstant) right).Value;
 236
 237                                         v = new IntConstant (res);
 238                                         if (result_type == null)
 239                                                 return v;
 240                                         else
 241                                                 return new EnumConstant (v, result_type);
 242                                 } else if (left is UIntConstant){
 243                                         UIntConstant v;
 244                                         uint res = ((UIntConstant)left).Value | ((UIntConstant)right).Value;
 245
 246                                         v = new UIntConstant (res);
 247                                         if (result_type == null)
 248                                                 return v;
 249                                         else
 250                                                 return new EnumConstant (v, result_type);
 251                                 } else if (left is LongConstant){
 252                                         LongConstant v;
 253                                         long res = ((LongConstant)left).Value | ((LongConstant)right).Value;
 254
 255                                         v = new LongConstant (res);
 256                                         if (result_type == null)
 257                                                 return v;
 258                                         else
 259                                                 return new EnumConstant (v, result_type);
 260                                 } else if (left is ULongConstant){
 261                                         ULongConstant v;
 262                                         ulong res = ((ULongConstant)left).Value |
 263                                                 ((ULongConstant)right).Value;
 264
 265                                         v = new ULongConstant (res);
 266                                         if (result_type == null)
 267                                                 return v;
 268                                         else
 269                                                 return new EnumConstant (v, result_type);
 270                                 } else if (left is UShortConstant){
 271                                         UShortConstant v;
 272                                         ushort res = (ushort) (((UShortConstant)left).Value |
 273                                                                ((UShortConstant)right).Value);
 274
 275                                         v = new UShortConstant (res);
 276                                         if (result_type == null)
 277                                                 return v;
 278                                         else
 279                                                 return new EnumConstant (v, result_type);
 280                                 } else if (left is ShortConstant){
 281                                         ShortConstant v;
 282                                         short res = (short) (((ShortConstant)left).Value |
 283                                                              ((ShortConstant)right).Value);
 284
 285                                         v = new ShortConstant (res);
 286                                         if (result_type == null)
 287                                                 return v;
 288                                         else
 289                                                 return new EnumConstant (v, result_type);
 290                                 }
 291                                 break;
 292
 293                         case Binary.Operator.BitwiseAnd:
 294                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
 295                                 if (left == null || right == null)
 296                                         return null;
 297
 298                                 if (left is IntConstant){
 299                                         IntConstant v;
 300                                         int res = ((IntConstant) left).Value & ((IntConstant) right).Value;
 301
 302                                         v = new IntConstant (res);
 303                                         if (result_type == null)
 304                                                 return v;
 305                                         else
 306                                                 return new EnumConstant (v, result_type);
 307                                 } else if (left is UIntConstant){
 308                                         UIntConstant v;
 309                                         uint res = ((UIntConstant)left).Value & ((UIntConstant)right).Value;
 310
 311                                         v = new UIntConstant (res);
 312                                         if (result_type == null)
 313                                                 return v;
 314                                         else
 315                                                 return new EnumConstant (v, result_type);
 316                                 } else if (left is LongConstant){
 317                                         LongConstant v;
 318                                         long res = ((LongConstant)left).Value & ((LongConstant)right).Value;
 319
 320                                         v = new LongConstant (res);
 321                                         if (result_type == null)
 322                                                 return v;
 323                                         else
 324                                                 return new EnumConstant (v, result_type);
 325                                 } else if (left is ULongConstant){
 326                                         ULongConstant v;
 327                                         ulong res = ((ULongConstant)left).Value &
 328                                                 ((ULongConstant)right).Value;
 329
 330                                         v = new ULongConstant (res);
 331                                         if (result_type == null)
 332                                                 return v;
 333                                         else
 334                                                 return new EnumConstant (v, result_type);
 335                                 } else if (left is UShortConstant){
 336                                         UShortConstant v;
 337                                         ushort res = (ushort) (((UShortConstant)left).Value &
 338                                                                ((UShortConstant)right).Value);
 339
 340                                         v = new UShortConstant (res);
 341                                         if (result_type == null)
 342                                                 return v;
 343                                         else
 344                                                 return new EnumConstant (v, result_type);
 345                                 } else if (left is ShortConstant){
 346                                         ShortConstant v;
 347                                         short res = (short) (((ShortConstant)left).Value &
 348                                                              ((ShortConstant)right).Value);
 349
 350                                         v = new ShortConstant (res);
 351                                         if (result_type == null)
 352                                                 return v;
 353                                         else
 354                                                 return new EnumConstant (v, result_type);
 355                                 }
 356                                 break;
 357
 358                         case Binary.Operator.ExclusiveOr:
 359                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
 360                                 if (left == null || right == null)
 361                                         return null;
 362
 363                                 if (left is IntConstant){
 364                                         IntConstant v;
 365                                         int res = ((IntConstant) left).Value ^ ((IntConstant) right).Value;
 366
 367                                         v = new IntConstant (res);
 368                                         if (result_type == null)
 369                                                 return v;
 370                                         else
 371                                                 return new EnumConstant (v, result_type);
 372                                 } else if (left is UIntConstant){
 373                                         UIntConstant v;
 374                                         uint res = ((UIntConstant)left).Value ^ ((UIntConstant)right).Value;
 375
 376                                         v = new UIntConstant (res);
 377                                         if (result_type == null)
 378                                                 return v;
 379                                         else
 380                                                 return new EnumConstant (v, result_type);
 381                                 } else if (left is LongConstant){
 382                                         LongConstant v;
 383                                         long res = ((LongConstant)left).Value ^ ((LongConstant)right).Value;
 384
 385                                         v = new LongConstant (res);
 386                                         if (result_type == null)
 387                                                 return v;
 388                                         else
 389                                                 return new EnumConstant (v, result_type);
 390                                 } else if (left is ULongConstant){
 391                                         ULongConstant v;
 392                                         ulong res = ((ULongConstant)left).Value ^
 393                                                 ((ULongConstant)right).Value;
 394
 395                                         v = new ULongConstant (res);
 396                                         if (result_type == null)
 397                                                 return v;
 398                                         else
 399                                                 return new EnumConstant (v, result_type);
 400                                 } else if (left is UShortConstant){
 401                                         UShortConstant v;
 402                                         ushort res = (ushort) (((UShortConstant)left).Value ^
 403                                                                ((UShortConstant)right).Value);
 404
 405                                         v = new UShortConstant (res);
 406                                         if (result_type == null)
 407                                                 return v;
 408                                         else
 409                                                 return new EnumConstant (v, result_type);
 410                                 } else if (left is ShortConstant){
 411                                         ShortConstant v;
 412                                         short res = (short)(((ShortConstant)left).Value ^
 413                                                             ((ShortConstant)right).Value);
 414
 415                                         v = new ShortConstant (res);
 416                                         if (result_type == null)
 417                                                 return v;
 418                                         else
 419                                                 return new EnumConstant (v, result_type);
 420                                 }
 421                                 break;
 422
 423                         case Binary.Operator.Addition:
 424                                 bool left_is_string = left is StringConstant;
 425                                 bool right_is_string = right is StringConstant;
 426
 427                                 //
 428                                 // If both sides are strings, then concatenate, if
 429                                 // one is a string, and the other is not, then defer
 430                                 // to runtime concatenation
 431                                 //
 432                                 wrap_as = null;
 433                                 if (left_is_string || right_is_string){
 434                                         if (left_is_string && right_is_string)
 435                                                 return new StringConstant (
 436                                                         ((StringConstant) left).Value +
 437                                                         ((StringConstant) right).Value);
 438
 439                                         return null;
 440                                 }
 441
 442                                 //
 443                                 // handle "E operator + (E x, U y)"
 444                                 // handle "E operator + (Y y, E x)"
 445                                 //
 446                                 // note that E operator + (E x, E y) is invalid
 447                                 //
 448                                 if (left is EnumConstant){
 449                                         if (right is EnumConstant){
 450                                                 return null;
 451                                         }
 452                                         if (((EnumConstant) left).Child.Type != right.Type)
 453                                                 return null;
 454
 455                                         wrap_as = left.Type;
 456                                 } else if (right is EnumConstant){
 457                                         if (((EnumConstant) right).Child.Type != left.Type)
 458                                                 return null;
 459                                         wrap_as = right.Type;
 460                                 }
 461
 462                                 result = null;
 463                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
 464                                 if (left == null || right == null)
 465                                         return null;
 466
 467                                 try {
 468                                         if (left is DoubleConstant){
 469                                                 double res;
 470
 471                                                 if (ec.ConstantCheckState)
 472                                                         res = checked (((DoubleConstant) left).Value +
 473                                                                        ((DoubleConstant) right).Value);
 474                                                 else
 475                                                         res = unchecked (((DoubleConstant) left).Value +
 476                                                                          ((DoubleConstant) right).Value);
 477
 478                                                 result = new DoubleConstant (res);
 479                                         } else if (left is FloatConstant){
 480                                                 float res;
 481
 482                                                 if (ec.ConstantCheckState)
 483                                                         res = checked (((FloatConstant) left).Value +
 484                                                                        ((FloatConstant) right).Value);
 485                                                 else
 486                                                         res = unchecked (((FloatConstant) left).Value +
 487                                                                          ((FloatConstant) right).Value);
 488
 489                                                 result = new FloatConstant (res);
 490                                         } else if (left is ULongConstant){
 491                                                 ulong res;
 492
 493                                                 if (ec.ConstantCheckState)
 494                                                         res = checked (((ULongConstant) left).Value +
 495                                                                        ((ULongConstant) right).Value);
 496                                                 else
 497                                                         res = unchecked (((ULongConstant) left).Value +
 498                                                                          ((ULongConstant) right).Value);
 499
 500                                                 result = new ULongConstant (res);
 501                                         } else if (left is LongConstant){
 502                                                 long res;
 503
 504                                                 if (ec.ConstantCheckState)
 505                                                         res = checked (((LongConstant) left).Value +
 506                                                                        ((LongConstant) right).Value);
 507                                                 else
 508                                                         res = unchecked (((LongConstant) left).Value +
 509                                                                          ((LongConstant) right).Value);
 510
 511                                                 result = new LongConstant (res);
 512                                         } else if (left is UIntConstant){
 513                                                 uint res;
 514
 515                                                 if (ec.ConstantCheckState)
 516                                                         res = checked (((UIntConstant) left).Value +
 517                                                                        ((UIntConstant) right).Value);
 518                                                 else
 519                                                         res = unchecked (((UIntConstant) left).Value +
 520                                                                          ((UIntConstant) right).Value);
 521
 522                                                 result = new UIntConstant (res);
 523                                         } else if (left is IntConstant){
 524                                                 int res;
 525
 526                                                 if (ec.ConstantCheckState)
 527                                                         res = checked (((IntConstant) left).Value +
 528                                                                        ((IntConstant) right).Value);
 529                                                 else
 530                                                         res = unchecked (((IntConstant) left).Value +
 531                                                                          ((IntConstant) right).Value);
 532
 533                                                 result = new IntConstant (res);
 534                                         } else if (left is DecimalConstant) {
 535                                                 decimal res;
 536
 537                                                 if (ec.ConstantCheckState)
 538                                                         res = checked (((DecimalConstant) left).Value +
 539                                                                 ((DecimalConstant) right).Value);
 540                                                 else
 541                                                         res = unchecked (((DecimalConstant) left).Value +
 542                                                                 ((DecimalConstant) right).Value);
 543
 544                                                 result = new DecimalConstant (res);
 545                                         } else {
 546                                                 throw new Exception ( "Unexepected addition input: " + left);
 547                                         }
 548                                 } catch (OverflowException){
 549                                         Error_CompileTimeOverflow (loc);
 550                                 }
 551
 552                                 if (wrap_as != null)
 553                                         return new EnumConstant (result, wrap_as);
 554                                 else
 555                                         return result;
 556
 557                         case Binary.Operator.Subtraction:
 558                                 //
 559                                 // handle "E operator - (E x, U y)"
 560                                 // handle "E operator - (Y y, E x)"
 561                                 // handle "U operator - (E x, E y)"
 562                                 //
 563                                 wrap_as = null;
 564                                 if (left is EnumConstant){
 565                                         if (right is EnumConstant){
 566                                                 if (left.Type == right.Type)
 567                                                         wrap_as = TypeManager.EnumToUnderlying (left.Type);
 568                                                 else
 569                                                         return null;
 570                                         }
 571                                         if (((EnumConstant) left).Child.Type != right.Type)
 572                                                 return null;
 573
 574                                         wrap_as = left.Type;
 575                                 } else if (right is EnumConstant){
 576                                         if (((EnumConstant) right).Child.Type != left.Type)
 577                                                 return null;
 578                                         wrap_as = right.Type;
 579                                 }
 580
 581                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
 582                                 if (left == null || right == null)
 583                                         return null;
 584
 585                                 try {
 586                                         if (left is DoubleConstant){
 587                                                 double res;
 588
 589                                                 if (ec.ConstantCheckState)
 590                                                         res = checked (((DoubleConstant) left).Value -
 591                                                                        ((DoubleConstant) right).Value);
 592                                                 else
 593                                                         res = unchecked (((DoubleConstant) left).Value -
 594                                                                          ((DoubleConstant) right).Value);
 595
 596                                                 result = new DoubleConstant (res);
 597                                         } else if (left is FloatConstant){
 598                                                 float res;
 599
 600                                                 if (ec.ConstantCheckState)
 601                                                         res = checked (((FloatConstant) left).Value -
 602                                                                        ((FloatConstant) right).Value);
 603                                                 else
 604                                                         res = unchecked (((FloatConstant) left).Value -
 605                                                                          ((FloatConstant) right).Value);
 606
 607                                                 result = new FloatConstant (res);
 608                                         } else if (left is ULongConstant){
 609                                                 ulong res;
 610
 611                                                 if (ec.ConstantCheckState)
 612                                                         res = checked (((ULongConstant) left).Value -
 613                                                                        ((ULongConstant) right).Value);
 614                                                 else
 615                                                         res = unchecked (((ULongConstant) left).Value -
 616                                                                          ((ULongConstant) right).Value);
 617
 618                                                 result = new ULongConstant (res);
 619                                         } else if (left is LongConstant){
 620                                                 long res;
 621
 622                                                 if (ec.ConstantCheckState)
 623                                                         res = checked (((LongConstant) left).Value -
 624                                                                        ((LongConstant) right).Value);
 625                                                 else
 626                                                         res = unchecked (((LongConstant) left).Value -
 627                                                                          ((LongConstant) right).Value);
 628
 629                                                 result = new LongConstant (res);
 630                                         } else if (left is UIntConstant){
 631                                                 uint res;
 632
 633                                                 if (ec.ConstantCheckState)
 634                                                         res = checked (((UIntConstant) left).Value -
 635                                                                        ((UIntConstant) right).Value);
 636                                                 else
 637                                                         res = unchecked (((UIntConstant) left).Value -
 638                                                                          ((UIntConstant) right).Value);
 639
 640                                                 result = new UIntConstant (res);
 641                                         } else if (left is IntConstant){
 642                                                 int res;
 643
 644                                                 if (ec.ConstantCheckState)
 645                                                         res = checked (((IntConstant) left).Value -
 646                                                                        ((IntConstant) right).Value);
 647                                                 else
 648                                                         res = unchecked (((IntConstant) left).Value -
 649                                                                          ((IntConstant) right).Value);
 650
 651                                                 result = new IntConstant (res);
 652                                         } else if (left is DecimalConstant) {
 653                                                 decimal res;
 654
 655                                                 if (ec.ConstantCheckState)
 656                                                         res = checked (((DecimalConstant) left).Value -
 657                                                                 ((DecimalConstant) right).Value);
 658                                                 else
 659                                                         res = unchecked (((DecimalConstant) left).Value -
 660                                                                 ((DecimalConstant) right).Value);
 661
 662                                                 return new DecimalConstant (res);
 663                                         } else {
 664                                                 throw new Exception ( "Unexepected subtraction input: " + left);
 665                                         }
 666                                 } catch (OverflowException){
 667                                         Error_CompileTimeOverflow (loc);
 668                                 }
 669                                 if (wrap_as != null)
 670                                         return new EnumConstant (result, wrap_as);
 671                                 else
 672                                         return result;
 673
 674                         case Binary.Operator.Multiply:
 675                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
 676                                 if (left == null || right == null)
 677                                         return null;
 678
 679                                 try {
 680                                         if (left is DoubleConstant){
 681                                                 double res;
 682
 683                                                 if (ec.ConstantCheckState)
 684                                                         res = checked (((DoubleConstant) left).Value *
 685                                                                 ((DoubleConstant) right).Value);
 686                                                 else
 687                                                         res = unchecked (((DoubleConstant) left).Value *
 688                                                                 ((DoubleConstant) right).Value);
 689
 690                                                 return new DoubleConstant (res);
 691                                         } else if (left is FloatConstant){
 692                                                 float res;
 693
 694                                                 if (ec.ConstantCheckState)
 695                                                         res = checked (((FloatConstant) left).Value *
 696                                                                 ((FloatConstant) right).Value);
 697                                                 else
 698                                                         res = unchecked (((FloatConstant) left).Value *
 699                                                                 ((FloatConstant) right).Value);
 700
 701                                                 return new FloatConstant (res);
 702                                         } else if (left is ULongConstant){
 703                                                 ulong res;
 704
 705                                                 if (ec.ConstantCheckState)
 706                                                         res = checked (((ULongConstant) left).Value *
 707                                                                 ((ULongConstant) right).Value);
 708                                                 else
 709                                                         res = unchecked (((ULongConstant) left).Value *
 710                                                                 ((ULongConstant) right).Value);
 711
 712                                                 return new ULongConstant (res);
 713                                         } else if (left is LongConstant){
 714                                                 long res;
 715
 716                                                 if (ec.ConstantCheckState)
 717                                                         res = checked (((LongConstant) left).Value *
 718                                                                 ((LongConstant) right).Value);
 719                                                 else
 720                                                         res = unchecked (((LongConstant) left).Value *
 721                                                                 ((LongConstant) right).Value);
 722
 723                                                 return new LongConstant (res);
 724                                         } else if (left is UIntConstant){
 725                                                 uint res;
 726
 727                                                 if (ec.ConstantCheckState)
 728                                                         res = checked (((UIntConstant) left).Value *
 729                                                                 ((UIntConstant) right).Value);
 730                                                 else
 731                                                         res = unchecked (((UIntConstant) left).Value *
 732                                                                 ((UIntConstant) right).Value);
 733
 734                                                 return new UIntConstant (res);
 735                                         } else if (left is IntConstant){
 736                                                 int res;
 737
 738                                                 if (ec.ConstantCheckState)
 739                                                         res = checked (((IntConstant) left).Value *
 740                                                                 ((IntConstant) right).Value);
 741                                                 else
 742                                                         res = unchecked (((IntConstant) left).Value *
 743                                                                 ((IntConstant) right).Value);
 744
 745                                                 return new IntConstant (res);
 746                                         } else if (left is DecimalConstant) {
 747                                                 decimal res;
 748
 749                                                 if (ec.ConstantCheckState)
 750                                                         res = checked (((DecimalConstant) left).Value *
 751                                                                 ((DecimalConstant) right).Value);
 752                                                 else
 753                                                         res = unchecked (((DecimalConstant) left).Value *
 754                                                                 ((DecimalConstant) right).Value);
 755
 756                                                 return new DecimalConstant (res);
 757                                         } else {
 758                                                 throw new Exception ( "Unexepected multiply input: " + left);
 759                                         }
 760                                 } catch (OverflowException){
 761                                         Error_CompileTimeOverflow (loc);
 762                                 }
 763                                 break;
 764
 765                         case Binary.Operator.Division:
 766                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
 767                                 if (left == null || right == null)
 768                                         return null;
 769
 770                                 try {
 771                                         if (left is DoubleConstant){
 772                                                 double res;
 773
 774                                                 if (ec.ConstantCheckState)
 775                                                         res = checked (((DoubleConstant) left).Value /
 776                                                                 ((DoubleConstant) right).Value);
 777                                                 else
 778                                                         res = unchecked (((DoubleConstant) left).Value /
 779                                                                 ((DoubleConstant) right).Value);
 780
 781                                                 return new DoubleConstant (res);
 782                                         } else if (left is FloatConstant){
 783                                                 float res;
 784
 785                                                 if (ec.ConstantCheckState)
 786                                                         res = checked (((FloatConstant) left).Value /
 787                                                                 ((FloatConstant) right).Value);
 788                                                 else
 789                                                         res = unchecked (((FloatConstant) left).Value /
 790                                                                 ((FloatConstant) right).Value);
 791
 792                                                 return new FloatConstant (res);
 793                                         } else if (left is ULongConstant){
 794                                                 ulong res;
 795
 796                                                 if (ec.ConstantCheckState)
 797                                                         res = checked (((ULongConstant) left).Value /
 798                                                                 ((ULongConstant) right).Value);
 799                                                 else
 800                                                         res = unchecked (((ULongConstant) left).Value /
 801                                                                 ((ULongConstant) right).Value);
 802
 803                                                 return new ULongConstant (res);
 804                                         } else if (left is LongConstant){
 805                                                 long res;
 806
 807                                                 if (ec.ConstantCheckState)
 808                                                         res = checked (((LongConstant) left).Value /
 809                                                                 ((LongConstant) right).Value);
 810                                                 else
 811                                                         res = unchecked (((LongConstant) left).Value /
 812                                                                 ((LongConstant) right).Value);
 813
 814                                                 return new LongConstant (res);
 815                                         } else if (left is UIntConstant){
 816                                                 uint res;
 817
 818                                                 if (ec.ConstantCheckState)
 819                                                         res = checked (((UIntConstant) left).Value /
 820                                                                 ((UIntConstant) right).Value);
 821                                                 else
 822                                                         res = unchecked (((UIntConstant) left).Value /
 823                                                                 ((UIntConstant) right).Value);
 824
 825                                                 return new UIntConstant (res);
 826                                         } else if (left is IntConstant){
 827                                                 int res;
 828
 829                                                 if (ec.ConstantCheckState)
 830                                                         res = checked (((IntConstant) left).Value /
 831                                                                 ((IntConstant) right).Value);
 832                                                 else
 833                                                         res = unchecked (((IntConstant) left).Value /
 834                                                                 ((IntConstant) right).Value);
 835
 836                                                 return new IntConstant (res);
 837                                         } else if (left is DecimalConstant) {
 838                                                 decimal res;
 839
 840                                                 if (ec.ConstantCheckState)
 841                                                         res = checked (((DecimalConstant) left).Value /
 842                                                                 ((DecimalConstant) right).Value);
 843                                                 else
 844                                                         res = unchecked (((DecimalConstant) left).Value /
 845                                                                 ((DecimalConstant) right).Value);
 846
 847                                                 return new DecimalConstant (res);
 848                                         } else {
 849                                                 throw new Exception ( "Unexepected division input: " + left);
 850                                         }
 851                                 } catch (OverflowException){
 852                                         Error_CompileTimeOverflow (loc);
 853
 854                                 } catch (DivideByZeroException) {
 855                                         Report.Error (020, loc, "Division by constant zero");
 856                                 }
 857
 858                                 break;
 859
 860                         case Binary.Operator.Modulus:
 861                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
 862                                 if (left == null || right == null)
 863                                         return null;
 864
 865                                 try {
 866                                         if (left is DoubleConstant){
 867                                                 double res;
 868
 869                                                 if (ec.ConstantCheckState)
 870                                                         res = checked (((DoubleConstant) left).Value %
 871                                                                        ((DoubleConstant) right).Value);
 872                                                 else
 873                                                         res = unchecked (((DoubleConstant) left).Value %
 874                                                                          ((DoubleConstant) right).Value);
 875
 876                                                 return new DoubleConstant (res);
 877                                         } else if (left is FloatConstant){
 878                                                 float res;
 879
 880                                                 if (ec.ConstantCheckState)
 881                                                         res = checked (((FloatConstant) left).Value %
 882                                                                        ((FloatConstant) right).Value);
 883                                                 else
 884                                                         res = unchecked (((FloatConstant) left).Value %
 885                                                                          ((FloatConstant) right).Value);
 886
 887                                                 return new FloatConstant (res);
 888                                         } else if (left is ULongConstant){
 889                                                 ulong res;
 890
 891                                                 if (ec.ConstantCheckState)
 892                                                         res = checked (((ULongConstant) left).Value %
 893                                                                        ((ULongConstant) right).Value);
 894                                                 else
 895                                                         res = unchecked (((ULongConstant) left).Value %
 896                                                                          ((ULongConstant) right).Value);
 897
 898                                                 return new ULongConstant (res);
 899                                         } else if (left is LongConstant){
 900                                                 long res;
 901
 902                                                 if (ec.ConstantCheckState)
 903                                                         res = checked (((LongConstant) left).Value %
 904                                                                        ((LongConstant) right).Value);
 905                                                 else
 906                                                         res = unchecked (((LongConstant) left).Value %
 907                                                                          ((LongConstant) right).Value);
 908
 909                                                 return new LongConstant (res);
 910                                         } else if (left is UIntConstant){
 911                                                 uint res;
 912
 913                                                 if (ec.ConstantCheckState)
 914                                                         res = checked (((UIntConstant) left).Value %
 915                                                                        ((UIntConstant) right).Value);
 916                                                 else
 917                                                         res = unchecked (((UIntConstant) left).Value %
 918                                                                          ((UIntConstant) right).Value);
 919
 920                                                 return new UIntConstant (res);
 921                                         } else if (left is IntConstant){
 922                                                 int res;
 923
 924                                                 if (ec.ConstantCheckState)
 925                                                         res = checked (((IntConstant) left).Value %
 926                                                                        ((IntConstant) right).Value);
 927                                                 else
 928                                                         res = unchecked (((IntConstant) left).Value %
 929                                                                          ((IntConstant) right).Value);
 930
 931                                                 return new IntConstant (res);
 932                                         } else {
 933                                                 throw new Exception ( "Unexepected modulus input: " + left);
 934                                         }
 935                                 } catch (DivideByZeroException){
 936                                         Report.Error (020, loc, "Division by constant zero");
 937                                 } catch (OverflowException){
 938                                         Error_CompileTimeOverflow (loc);
 939                                 }
 940                                 break;
 941
 942                                 //
 943                                 // There is no overflow checking on left shift
 944                                 //
 945                         case Binary.Operator.LeftShift:
 946                                 IntConstant ic = right.ToInt (loc);
 947                                 if (ic == null){
 948                                         Binary.Error_OperatorCannotBeApplied (loc, "<<", lt, rt);
 949                                         return null;
 950                                 }
 951                                 int lshift_val = ic.Value;
 952
 953                                 IntConstant lic;
 954                                 if ((lic = left.ConvertToInt ()) != null)
 955                                         return new IntConstant (lic.Value << lshift_val);
 956
 957                                 UIntConstant luic;
 958                                 if ((luic = left.ConvertToUInt ()) != null)
 959                                         return new UIntConstant (luic.Value << lshift_val);
 960
 961                                 LongConstant llc;
 962                                 if ((llc = left.ConvertToLong ()) != null)
 963                                         return new LongConstant (llc.Value << lshift_val);
 964
 965                                 ULongConstant lulc;
 966                                 if ((lulc = left.ConvertToULong ()) != null)
 967                                         return new ULongConstant (lulc.Value << lshift_val);
 968
 969                                 Binary.Error_OperatorCannotBeApplied (loc, "<<", lt, rt);
 970                                 break;
 971
 972                                 //
 973                                 // There is no overflow checking on right shift
 974                                 //
 975                         case Binary.Operator.RightShift:
 976                                 IntConstant sic = right.ToInt (loc);
 977                                 if (sic == null){
 978                                         Binary.Error_OperatorCannotBeApplied (loc, ">>", lt, rt);
 979                                         return null;
 980                                 }
 981                                 int rshift_val = sic.Value;
 982
 983                                 IntConstant ric;
 984                                 if ((ric = left.ConvertToInt ()) != null)
 985                                         return new IntConstant (ric.Value >> rshift_val);
 986
 987                                 UIntConstant ruic;
 988                                 if ((ruic = left.ConvertToUInt ()) != null)
 989                                         return new UIntConstant (ruic.Value >> rshift_val);
 990
 991                                 LongConstant rlc;
 992                                 if ((rlc = left.ConvertToLong ()) != null)
 993                                         return new LongConstant (rlc.Value >> rshift_val);
 994
 995                                 ULongConstant rulc;
 996                                 if ((rulc = left.ConvertToULong ()) != null)
 997                                         return new ULongConstant (rulc.Value >> rshift_val);
 998
 999                                 Binary.Error_OperatorCannotBeApplied (loc, ">>", lt, rt);
1000                                 break;
1001
1002                         case Binary.Operator.LogicalAndAlso:
1003                                 if (left is BoolConstant && right is BoolConstant){
1004                                         return new BoolConstant (
1005                                                 ((BoolConstant) left).Value &&
1006                                                 ((BoolConstant) right).Value);
1007                                 }
1008                                 break;
1009
1010                         case Binary.Operator.LogicalOrElse:
1011                                 if (left is BoolConstant && right is BoolConstant){
1012                                         return new BoolConstant (
1013                                                 ((BoolConstant) left).Value ||
1014                                                 ((BoolConstant) right).Value);
1015                                 }
1016                                 break;
1017
1018                         case Binary.Operator.Equality:
1019                                 if (left is BoolConstant && right is BoolConstant){
1020                                         return new BoolConstant (
1021                                                 ((BoolConstant) left).Value ==
1022                                                 ((BoolConstant) right).Value);
1023
1024                                 }
1025                                 if (left is NullLiteral){
1026                                         if (right is NullLiteral)
1027                                                 return new BoolConstant (true);
1028                                         else if (right is StringConstant)
1029                                                 return new BoolConstant (
1030                                                         ((StringConstant) right).Value == null);
1031                                 } else if (right is NullLiteral){
1032                                         if (left is NullLiteral)
1033                                                 return new BoolConstant (true);
1034                                         else if (left is StringConstant)
1035                                                 return new BoolConstant (
1036                                                         ((StringConstant) left).Value == null);
1037                                 }
1038                                 if (left is StringConstant && right is StringConstant){
1039                                         return new BoolConstant (
1040                                                 ((StringConstant) left).Value ==
1041                                                 ((StringConstant) right).Value);
1042
1043                                 }
1044
1045                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
1046                                 if (left == null || right == null)
1047                                         return null;
1048
1049                                 bool_res = false;
1050                                 if (left is DoubleConstant)
1051                                         bool_res = ((DoubleConstant) left).Value ==
1052                                                 ((DoubleConstant) right).Value;
1053                                 else if (left is FloatConstant)
1054                                         bool_res = ((FloatConstant) left).Value ==
1055                                                 ((FloatConstant) right).Value;
1056                                 else if (left is ULongConstant)
1057                                         bool_res = ((ULongConstant) left).Value ==
1058                                                 ((ULongConstant) right).Value;
1059                                 else if (left is LongConstant)
1060                                         bool_res = ((LongConstant) left).Value ==
1061                                                 ((LongConstant) right).Value;
1062                                 else if (left is UIntConstant)
1063                                         bool_res = ((UIntConstant) left).Value ==
1064                                                 ((UIntConstant) right).Value;
1065                                 else if (left is IntConstant)
1066                                         bool_res = ((IntConstant) left).Value ==
1067                                                 ((IntConstant) right).Value;
1068                                 else
1069                                         return null;
1070
1071                                 return new BoolConstant (bool_res);
1072
1073                         case Binary.Operator.Inequality:
1074                                 if (left is BoolConstant && right is BoolConstant){
1075                                         return new BoolConstant (
1076                                                 ((BoolConstant) left).Value !=
1077                                                 ((BoolConstant) right).Value);
1078                                 }
1079                                 if (left is NullLiteral){
1080                                         if (right is NullLiteral)
1081                                                 return new BoolConstant (false);
1082                                         else if (right is StringConstant)
1083                                                 return new BoolConstant (
1084                                                         ((StringConstant) right).Value != null);
1085                                 } else if (right is NullLiteral){
1086                                         if (left is NullLiteral)
1087                                                 return new BoolConstant (false);
1088                                         else if (left is StringConstant)
1089                                                 return new BoolConstant (
1090                                                         ((StringConstant) left).Value != null);
1091                                 }
1092                                 if (left is StringConstant && right is StringConstant){
1093                                         return new BoolConstant (
1094                                                 ((StringConstant) left).Value !=
1095                                                 ((StringConstant) right).Value);
1096
1097                                 }
1098                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
1099                                 if (left == null || right == null)
1100                                         return null;
1101
1102                                 bool_res = false;
1103                                 if (left is DoubleConstant)
1104                                         bool_res = ((DoubleConstant) left).Value !=
1105                                                 ((DoubleConstant) right).Value;
1106                                 else if (left is FloatConstant)
1107                                         bool_res = ((FloatConstant) left).Value !=
1108                                                 ((FloatConstant) right).Value;
1109                                 else if (left is ULongConstant)
1110                                         bool_res = ((ULongConstant) left).Value !=
1111                                                 ((ULongConstant) right).Value;
1112                                 else if (left is LongConstant)
1113                                         bool_res = ((LongConstant) left).Value !=
1114                                                 ((LongConstant) right).Value;
1115                                 else if (left is UIntConstant)
1116                                         bool_res = ((UIntConstant) left).Value !=
1117                                                 ((UIntConstant) right).Value;
1118                                 else if (left is IntConstant)
1119                                         bool_res = ((IntConstant) left).Value !=
1120                                                 ((IntConstant) right).Value;
1121                                 else
1122                                         return null;
1123
1124                                 return new BoolConstant (bool_res);
1125
1126                         case Binary.Operator.LessThan:
1127                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
1128                                 if (left == null || right == null)
1129                                         return null;
1130
1131                                 bool_res = false;
1132                                 if (left is DoubleConstant)
1133                                         bool_res = ((DoubleConstant) left).Value <
1134                                                 ((DoubleConstant) right).Value;
1135                                 else if (left is FloatConstant)
1136                                         bool_res = ((FloatConstant) left).Value <
1137                                                 ((FloatConstant) right).Value;
1138                                 else if (left is ULongConstant)
1139                                         bool_res = ((ULongConstant) left).Value <
1140                                                 ((ULongConstant) right).Value;
1141                                 else if (left is LongConstant)
1142                                         bool_res = ((LongConstant) left).Value <
1143                                                 ((LongConstant) right).Value;
1144                                 else if (left is UIntConstant)
1145                                         bool_res = ((UIntConstant) left).Value <
1146                                                 ((UIntConstant) right).Value;
1147                                 else if (left is IntConstant)
1148                                         bool_res = ((IntConstant) left).Value <
1149                                                 ((IntConstant) right).Value;
1150                                 else
1151                                         return null;
1152
1153                                 return new BoolConstant (bool_res);
1154
1155                         case Binary.Operator.GreaterThan:
1156                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
1157                                 if (left == null || right == null)
1158                                         return null;
1159
1160                                 bool_res = false;
1161                                 if (left is DoubleConstant)
1162                                         bool_res = ((DoubleConstant) left).Value >
1163                                                 ((DoubleConstant) right).Value;
1164                                 else if (left is FloatConstant)
1165                                         bool_res = ((FloatConstant) left).Value >
1166                                                 ((FloatConstant) right).Value;
1167                                 else if (left is ULongConstant)
1168                                         bool_res = ((ULongConstant) left).Value >
1169                                                 ((ULongConstant) right).Value;
1170                                 else if (left is LongConstant)
1171                                         bool_res = ((LongConstant) left).Value >
1172                                                 ((LongConstant) right).Value;
1173                                 else if (left is UIntConstant)
1174                                         bool_res = ((UIntConstant) left).Value >
1175                                                 ((UIntConstant) right).Value;
1176                                 else if (left is IntConstant)
1177                                         bool_res = ((IntConstant) left).Value >
1178                                                 ((IntConstant) right).Value;
1179                                 else
1180                                         return null;
1181
1182                                 return new BoolConstant (bool_res);
1183
1184                         case Binary.Operator.GreaterThanOrEqual:
1185                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
1186                                 if (left == null || right == null)
1187                                         return null;
1188
1189                                 bool_res = false;
1190                                 if (left is DoubleConstant)
1191                                         bool_res = ((DoubleConstant) left).Value >=
1192                                                 ((DoubleConstant) right).Value;
1193                                 else if (left is FloatConstant)
1194                                         bool_res = ((FloatConstant) left).Value >=
1195                                                 ((FloatConstant) right).Value;
1196                                 else if (left is ULongConstant)
1197                                         bool_res = ((ULongConstant) left).Value >=
1198                                                 ((ULongConstant) right).Value;
1199                                 else if (left is LongConstant)
1200                                         bool_res = ((LongConstant) left).Value >=
1201                                                 ((LongConstant) right).Value;
1202                                 else if (left is UIntConstant)
1203                                         bool_res = ((UIntConstant) left).Value >=
1204                                                 ((UIntConstant) right).Value;
1205                                 else if (left is IntConstant)
1206                                         bool_res = ((IntConstant) left).Value >=
1207                                                 ((IntConstant) right).Value;
1208                                 else
1209                                         return null;
1210
1211                                 return new BoolConstant (bool_res);
1212
1213                         case Binary.Operator.LessThanOrEqual:
1214                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
1215                                 if (left == null || right == null)
1216                                         return null;
1217
1218                                 bool_res = false;
1219                                 if (left is DoubleConstant)
1220                                         bool_res = ((DoubleConstant) left).Value <=
1221                                                 ((DoubleConstant) right).Value;
1222                                 else if (left is FloatConstant)
1223                                         bool_res = ((FloatConstant) left).Value <=
1224                                                 ((FloatConstant) right).Value;
1225                                 else if (left is ULongConstant)
1226                                         bool_res = ((ULongConstant) left).Value <=
1227                                                 ((ULongConstant) right).Value;
1228                                 else if (left is LongConstant)
1229                                         bool_res = ((LongConstant) left).Value <=
1230                                                 ((LongConstant) right).Value;
1231                                 else if (left is UIntConstant)
1232                                         bool_res = ((UIntConstant) left).Value <=
1233                                                 ((UIntConstant) right).Value;
1234                                 else if (left is IntConstant)
1235                                         bool_res = ((IntConstant) left).Value <=
1236                                                 ((IntConstant) right).Value;
1237                                 else
1238                                         return null;
1239
1240                                 return new BoolConstant (bool_res);
1241                         }
1242
1243                         return null;
1244                 }
1245         }
1246 }