mcs/mcs/cfold.cs

   1 //
   2 // cfold.cs: Constant Folding
   3 //
   4 // Author:
   5 //   Miguel de Icaza (miguel@ximian.com)
   6 //   Marek Safar (marek.safar@seznam.cz)
   7 //
   8 // (C) 2002, 2003 Ximian, Inc.
   9 //
  10
  11 using System;
  12
  13 namespace Mono.CSharp {
  14
  15         public class ConstantFold {
  16
  17                 //
  18                 // Performs the numeric promotions on the left and right expresions
  19                 // and desposits the results on `lc' and `rc'.
  20                 //
  21                 // On success, the types of `lc' and `rc' on output will always match,
  22                 // and the pair will be one of:
  23                 //
  24                 //   (double, double)
  25                 //   (float, float)
  26                 //   (ulong, ulong)
  27                 //   (long, long)
  28                 //   (uint, uint)
  29                 //   (int, int)
  30                 //   (short, short)   (Happens with enumerations with underlying short type)
  31                 //   (ushort, ushort) (Happens with enumerations with underlying short type)
  32                 //
  33                 static void DoConstantNumericPromotions (EmitContext ec, Binary.Operator oper,
  34                                                          ref Constant left, ref Constant right,
  35                                                          Location loc)
  36                 {
  37                         if (left is DoubleConstant || right is DoubleConstant){
  38                                 //
  39                                 // If either side is a double, convert the other to a double
  40                                 //
  41                                 if (!(left is DoubleConstant))
  42                                         left = left.ToDouble (loc);
  43
  44                                 if (!(right is DoubleConstant))
  45                                         right = right.ToDouble (loc);
  46                                 return;
  47                         } else if (left is FloatConstant || right is FloatConstant) {
  48                                 //
  49                                 // If either side is a float, convert the other to a float
  50                                 //
  51                                 if (!(left is FloatConstant))
  52                                         left = left.ToFloat (loc);
  53
  54                                 if (!(right is FloatConstant))
  55                                         right = right.ToFloat (loc);
  56 ;                               return;
  57                         } else if (left is ULongConstant || right is ULongConstant){
  58                                 //
  59                                 // If either operand is of type ulong, the other operand is
  60                                 // converted to type ulong.  or an error ocurrs if the other
  61                                 // operand is of type sbyte, short, int or long
  62                                 //
  63 #if WRONG
  64                                 Constant match, other;
  65 #endif
  66
  67                                 if (left is ULongConstant){
  68 #if WRONG
  69                                         other = right;
  70                                         match = left;
  71 #endif
  72                                         if (!(right is ULongConstant))
  73                                                 right = right.ToULong (loc);
  74                                 } else {
  75 #if WRONG
  76                                         other = left;
  77                                         match = right;
  78 #endif
  79                                         left = left.ToULong (loc);
  80                                 }
  81
  82 #if WRONG
  83                                 if (other is SByteConstant || other is ShortConstant ||
  84                                     other is IntConstant || other is LongConstant){
  85                                         Binary.Error_OperatorAmbiguous
  86                                                 (loc, oper, other.Type, match.Type);
  87                                         left = null;
  88                                         right = null;
  89                                 }
  90 #endif
  91                                 return;
  92                         } else if (left is LongConstant || right is LongConstant){
  93                                 //
  94                                 // If either operand is of type long, the other operand is converted
  95                                 // to type long.
  96                                 //
  97                                 if (!(left is LongConstant))
  98                                         left = left.ToLong (loc);
  99                                 else if (!(right is LongConstant))
 100                                         right = right.ToLong (loc);
 101                                 return;
 102                         } else if (left is UIntConstant || right is UIntConstant){
 103                                 //
 104                                 // If either operand is of type uint, and the other
 105                                 // operand is of type sbyte, short or int, the operands are
 106                                 // converted to type long.
 107                                 //
 108                                 Constant other;
 109                                 if (left is UIntConstant)
 110                                         other = right;
 111                                 else
 112                                         other = left;
 113
 114                                 // Nothing to do.
 115                                 if (other is UIntConstant)
 116                                         return;
 117
 118                                 IntConstant ic = other as IntConstant;
 119                                 if (ic != null){
 120                                         if (ic.Value >= 0){
 121                                                 if (left == other)
 122                                                         left = new UIntConstant ((uint) ic.Value, ic.Location);
 123                                                 else
 124                                                         right = new UIntConstant ((uint) ic.Value, ic.Location);
 125                                                 return;
 126                                         }
 127                                 }
 128
 129                                 if (other is SByteConstant || other is ShortConstant || ic != null){
 130                                         left = left.ToLong (loc);
 131                                         right = right.ToLong (loc);
 132                                 } else {
 133                                         left = left.ToUInt (loc);
 134                                         right = left.ToUInt (loc);
 135                                 }
 136
 137                                 return;
 138                         } else if (left is DecimalConstant || right is DecimalConstant) {
 139                                 if (!(left is DecimalConstant))
 140                                         left = left.ToDecimal (loc);
 141                                 else if (!(right is DecimalConstant))
 142                                         right = right.ToDecimal (loc);
 143                                 return;
 144                         } else if (left is EnumConstant || right is EnumConstant){
 145                                 if (left is EnumConstant)
 146                                         left = ((EnumConstant) left).Child;
 147                                 if (right is EnumConstant)
 148                                         right = ((EnumConstant) right).Child;
 149
 150                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
 151                                 return;
 152
 153                         } else {
 154                                 //
 155                                 // Force conversions to int32
 156                                 //
 157                                 if (!(left is IntConstant))
 158                                         left = left.ToInt (loc);
 159                                 if (!(right is IntConstant))
 160                                         right = right.ToInt (loc);
 161                         }
 162                         return;
 163                 }
 164
 165                 static void Error_CompileTimeOverflow (Location loc)
 166                 {
 167                         Report.Error (220, loc, "The operation overflows at compile time in checked mode");
 168                 }
 169
 170                 /// <summary>
 171                 ///   Constant expression folder for binary operations.
 172                 ///
 173                 ///   Returns null if the expression can not be folded.
 174                 /// </summary>
 175                 static public Expression BinaryFold (EmitContext ec, Binary.Operator oper,
 176                                                      Constant left, Constant right, Location loc)
 177                 {
 178                         if (left is EmptyConstantCast)
 179                                 return BinaryFold (ec, oper, ((EmptyConstantCast)left).child, right, loc);
 180
 181                         if (right is EmptyConstantCast)
 182                                 return BinaryFold (ec, oper, left, ((EmptyConstantCast)right).child, loc);
 183
 184                         Type lt = left.Type;
 185                         Type rt = right.Type;
 186                         Type result_type = null;
 187                         bool bool_res;
 188
 189                         //
 190                         // Enumerator folding
 191                         //
 192                         if (rt == lt && left is EnumConstant)
 193                                 result_type = lt;
 194
 195                         //
 196                         // During an enum evaluation, we need to unwrap enumerations
 197                         //
 198                         if (ec.InEnumContext){
 199                                 if (left is EnumConstant)
 200                                         left = ((EnumConstant) left).Child;
 201
 202                                 if (right is EnumConstant)
 203                                         right = ((EnumConstant) right).Child;
 204                         }
 205
 206                         if (left is BoolConstant && right is BoolConstant) {
 207                                 bool lv = ((BoolConstant) left ).Value;
 208                                 bool rv = ((BoolConstant) right).Value;
 209                                 switch (oper) {
 210                                 case Binary.Operator.BitwiseAnd:
 211                                 case Binary.Operator.LogicalAnd:
 212                                         return new BoolConstant (lv && rv, left.Location);
 213                                 case Binary.Operator.BitwiseOr:
 214                                 case Binary.Operator.LogicalOr:
 215                                         return new BoolConstant (lv || rv, left.Location);
 216                                 case Binary.Operator.ExclusiveOr:
 217                                         return new BoolConstant (lv ^ rv, left.Location);
 218                                 case Binary.Operator.Equality:
 219                                         return new BoolConstant (lv == rv, left.Location);
 220                                 case Binary.Operator.Inequality:
 221                                         return new BoolConstant (lv != rv, left.Location);
 222                                 default:
 223                                         throw new InternalErrorException ("Invalid operator on booleans: " + oper);
 224                                 }
 225                         }
 226
 227                         Type wrap_as;
 228                         Constant result = null;
 229                         switch (oper){
 230                         case Binary.Operator.BitwiseOr:
 231                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
 232                                 if (left == null || right == null)
 233                                         return null;
 234
 235                                 if (left is IntConstant){
 236                                         IntConstant v;
 237                                         int res = ((IntConstant) left).Value | ((IntConstant) right).Value;
 238
 239                                         v = new IntConstant (res, left.Location);
 240                                         if (result_type == null)
 241                                                 return v;
 242                                         else
 243                                                 return new EnumConstant (v, result_type);
 244                                 } else if (left is UIntConstant){
 245                                         UIntConstant v;
 246                                         uint res = ((UIntConstant)left).Value | ((UIntConstant)right).Value;
 247
 248                                         v = new UIntConstant (res, left.Location);
 249                                         if (result_type == null)
 250                                                 return v;
 251                                         else
 252                                                 return new EnumConstant (v, result_type);
 253                                 } else if (left is LongConstant){
 254                                         LongConstant v;
 255                                         long res = ((LongConstant)left).Value | ((LongConstant)right).Value;
 256
 257                                         v = new LongConstant (res, left.Location);
 258                                         if (result_type == null)
 259                                                 return v;
 260                                         else
 261                                                 return new EnumConstant (v, result_type);
 262                                 } else if (left is ULongConstant){
 263                                         ULongConstant v;
 264                                         ulong res = ((ULongConstant)left).Value |
 265                                                 ((ULongConstant)right).Value;
 266
 267                                         v = new ULongConstant (res, left.Location);
 268                                         if (result_type == null)
 269                                                 return v;
 270                                         else
 271                                                 return new EnumConstant (v, result_type);
 272                                 } else if (left is UShortConstant){
 273                                         UShortConstant v;
 274                                         ushort res = (ushort) (((UShortConstant)left).Value |
 275                                                                ((UShortConstant)right).Value);
 276
 277                                         v = new UShortConstant (res, left.Location);
 278                                         if (result_type == null)
 279                                                 return v;
 280                                         else
 281                                                 return new EnumConstant (v, result_type);
 282                                 } else if (left is ShortConstant){
 283                                         ShortConstant v;
 284                                         short res = (short) (((ShortConstant)left).Value |
 285                                                              ((ShortConstant)right).Value);
 286
 287                                         v = new ShortConstant (res, left.Location);
 288                                         if (result_type == null)
 289                                                 return v;
 290                                         else
 291                                                 return new EnumConstant (v, result_type);
 292                                 }
 293                                 break;
 294
 295                         case Binary.Operator.BitwiseAnd:
 296                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
 297                                 if (left == null || right == null)
 298                                         return null;
 299
 300                                 if (left is IntConstant){
 301                                         IntConstant v;
 302                                         int res = ((IntConstant) left).Value & ((IntConstant) right).Value;
 303
 304                                         v = new IntConstant (res, left.Location);
 305                                         if (result_type == null)
 306                                                 return v;
 307                                         else
 308                                                 return new EnumConstant (v, result_type);
 309                                 } else if (left is UIntConstant){
 310                                         UIntConstant v;
 311                                         uint res = ((UIntConstant)left).Value & ((UIntConstant)right).Value;
 312
 313                                         v = new UIntConstant (res, left.Location);
 314                                         if (result_type == null)
 315                                                 return v;
 316                                         else
 317                                                 return new EnumConstant (v, result_type);
 318                                 } else if (left is LongConstant){
 319                                         LongConstant v;
 320                                         long res = ((LongConstant)left).Value & ((LongConstant)right).Value;
 321
 322                                         v = new LongConstant (res, left.Location);
 323                                         if (result_type == null)
 324                                                 return v;
 325                                         else
 326                                                 return new EnumConstant (v, result_type);
 327                                 } else if (left is ULongConstant){
 328                                         ULongConstant v;
 329                                         ulong res = ((ULongConstant)left).Value &
 330                                                 ((ULongConstant)right).Value;
 331
 332                                         v = new ULongConstant (res, left.Location);
 333                                         if (result_type == null)
 334                                                 return v;
 335                                         else
 336                                                 return new EnumConstant (v, result_type);
 337                                 } else if (left is UShortConstant){
 338                                         UShortConstant v;
 339                                         ushort res = (ushort) (((UShortConstant)left).Value &
 340                                                                ((UShortConstant)right).Value);
 341
 342                                         v = new UShortConstant (res, left.Location);
 343                                         if (result_type == null)
 344                                                 return v;
 345                                         else
 346                                                 return new EnumConstant (v, result_type);
 347                                 } else if (left is ShortConstant){
 348                                         ShortConstant v;
 349                                         short res = (short) (((ShortConstant)left).Value &
 350                                                              ((ShortConstant)right).Value);
 351
 352                                         v = new ShortConstant (res, left.Location);
 353                                         if (result_type == null)
 354                                                 return v;
 355                                         else
 356                                                 return new EnumConstant (v, result_type);
 357                                 }
 358                                 break;
 359
 360                         case Binary.Operator.ExclusiveOr:
 361                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
 362                                 if (left == null || right == null)
 363                                         return null;
 364
 365                                 if (left is IntConstant){
 366                                         IntConstant v;
 367                                         int res = ((IntConstant) left).Value ^ ((IntConstant) right).Value;
 368
 369                                         v = new IntConstant (res, left.Location);
 370                                         if (result_type == null)
 371                                                 return v;
 372                                         else
 373                                                 return new EnumConstant (v, result_type);
 374                                 } else if (left is UIntConstant){
 375                                         UIntConstant v;
 376                                         uint res = ((UIntConstant)left).Value ^ ((UIntConstant)right).Value;
 377
 378                                         v = new UIntConstant (res, left.Location);
 379                                         if (result_type == null)
 380                                                 return v;
 381                                         else
 382                                                 return new EnumConstant (v, result_type);
 383                                 } else if (left is LongConstant){
 384                                         LongConstant v;
 385                                         long res = ((LongConstant)left).Value ^ ((LongConstant)right).Value;
 386
 387                                         v = new LongConstant (res, left.Location);
 388                                         if (result_type == null)
 389                                                 return v;
 390                                         else
 391                                                 return new EnumConstant (v, result_type);
 392                                 } else if (left is ULongConstant){
 393                                         ULongConstant v;
 394                                         ulong res = ((ULongConstant)left).Value ^
 395                                                 ((ULongConstant)right).Value;
 396
 397                                         v = new ULongConstant (res, left.Location);
 398                                         if (result_type == null)
 399                                                 return v;
 400                                         else
 401                                                 return new EnumConstant (v, result_type);
 402                                 } else if (left is UShortConstant){
 403                                         UShortConstant v;
 404                                         ushort res = (ushort) (((UShortConstant)left).Value ^
 405                                                                ((UShortConstant)right).Value);
 406
 407                                         v = new UShortConstant (res, left.Location);
 408                                         if (result_type == null)
 409                                                 return v;
 410                                         else
 411                                                 return new EnumConstant (v, result_type);
 412                                 } else if (left is ShortConstant){
 413                                         ShortConstant v;
 414                                         short res = (short)(((ShortConstant)left).Value ^
 415                                                             ((ShortConstant)right).Value);
 416
 417                                         v = new ShortConstant (res, left.Location);
 418                                         if (result_type == null)
 419                                                 return v;
 420                                         else
 421                                                 return new EnumConstant (v, result_type);
 422                                 }
 423                                 break;
 424
 425                         case Binary.Operator.Addition:
 426                                 bool left_is_string = left is StringConstant;
 427                                 bool right_is_string = right is StringConstant;
 428
 429                                 //
 430                                 // If both sides are strings, then concatenate, if
 431                                 // one is a string, and the other is not, then defer
 432                                 // to runtime concatenation
 433                                 //
 434                                 wrap_as = null;
 435                                 if (left_is_string || right_is_string){
 436                                         if (left_is_string && right_is_string)
 437                                                 return new StringConstant (
 438                                                         ((StringConstant) left).Value +
 439                                                         ((StringConstant) right).Value, left.Location);
 440
 441                                         return null;
 442                                 }
 443
 444                                 //
 445                                 // handle "E operator + (E x, U y)"
 446                                 // handle "E operator + (Y y, E x)"
 447                                 //
 448                                 // note that E operator + (E x, E y) is invalid
 449                                 //
 450                                 if (left is EnumConstant){
 451                                         if (right is EnumConstant){
 452                                                 return null;
 453                                         }
 454
 455                                         right = right.ToType (((EnumConstant) left).Child.Type);
 456                                         if (right == null)
 457                                                 return null;
 458
 459                                         wrap_as = left.Type;
 460                                 } else if (right is EnumConstant){
 461                                         left = left.ToType (((EnumConstant) right).Child.Type);
 462                                         if (left == null)
 463                                                 return null;
 464
 465                                         wrap_as = right.Type;
 466                                 }
 467
 468                                 result = null;
 469                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
 470                                 if (left == null || right == null)
 471                                         return null;
 472
 473                                 try {
 474                                         if (left is DoubleConstant){
 475                                                 double res;
 476
 477                                                 if (ec.ConstantCheckState)
 478                                                         res = checked (((DoubleConstant) left).Value +
 479                                                                        ((DoubleConstant) right).Value);
 480                                                 else
 481                                                         res = unchecked (((DoubleConstant) left).Value +
 482                                                                          ((DoubleConstant) right).Value);
 483
 484                                                 result = new DoubleConstant (res, left.Location);
 485                                         } else if (left is FloatConstant){
 486                                                 float res;
 487
 488                                                 if (ec.ConstantCheckState)
 489                                                         res = checked (((FloatConstant) left).Value +
 490                                                                        ((FloatConstant) right).Value);
 491                                                 else
 492                                                         res = unchecked (((FloatConstant) left).Value +
 493                                                                          ((FloatConstant) right).Value);
 494
 495                                                 result = new FloatConstant (res, left.Location);
 496                                         } else if (left is ULongConstant){
 497                                                 ulong res;
 498
 499                                                 if (ec.ConstantCheckState)
 500                                                         res = checked (((ULongConstant) left).Value +
 501                                                                        ((ULongConstant) right).Value);
 502                                                 else
 503                                                         res = unchecked (((ULongConstant) left).Value +
 504                                                                          ((ULongConstant) right).Value);
 505
 506                                                 result = new ULongConstant (res, left.Location);
 507                                         } else if (left is LongConstant){
 508                                                 long res;
 509
 510                                                 if (ec.ConstantCheckState)
 511                                                         res = checked (((LongConstant) left).Value +
 512                                                                        ((LongConstant) right).Value);
 513                                                 else
 514                                                         res = unchecked (((LongConstant) left).Value +
 515                                                                          ((LongConstant) right).Value);
 516
 517                                                 result = new LongConstant (res, left.Location);
 518                                         } else if (left is UIntConstant){
 519                                                 uint res;
 520
 521                                                 if (ec.ConstantCheckState)
 522                                                         res = checked (((UIntConstant) left).Value +
 523                                                                        ((UIntConstant) right).Value);
 524                                                 else
 525                                                         res = unchecked (((UIntConstant) left).Value +
 526                                                                          ((UIntConstant) right).Value);
 527
 528                                                 result = new UIntConstant (res, left.Location);
 529                                         } else if (left is IntConstant){
 530                                                 int res;
 531
 532                                                 if (ec.ConstantCheckState)
 533                                                         res = checked (((IntConstant) left).Value +
 534                                                                        ((IntConstant) right).Value);
 535                                                 else
 536                                                         res = unchecked (((IntConstant) left).Value +
 537                                                                          ((IntConstant) right).Value);
 538
 539                                                 result = new IntConstant (res, left.Location);
 540                                         } else if (left is DecimalConstant) {
 541                                                 decimal res;
 542
 543                                                 if (ec.ConstantCheckState)
 544                                                         res = checked (((DecimalConstant) left).Value +
 545                                                                 ((DecimalConstant) right).Value);
 546                                                 else
 547                                                         res = unchecked (((DecimalConstant) left).Value +
 548                                                                 ((DecimalConstant) right).Value);
 549
 550                                                 result = new DecimalConstant (res, left.Location);
 551                                         } else {
 552                                                 throw new Exception ( "Unexepected addition input: " + left);
 553                                         }
 554                                 } catch (OverflowException){
 555                                         Error_CompileTimeOverflow (loc);
 556                                 }
 557
 558                                 if (wrap_as != null) {
 559                                         try {
 560                                                 return result.TryReduce (ec, wrap_as, loc);
 561                                         }
 562                                         catch (OverflowException) {
 563                                                 return null;
 564                                         }
 565                                 }
 566                                 else
 567                                         return result;
 568
 569                         case Binary.Operator.Subtraction:
 570                                 //
 571                                 // handle "E operator - (E x, U y)"
 572                                 // handle "E operator - (Y y, E x)"
 573                                 // handle "U operator - (E x, E y)"
 574                                 //
 575                                 wrap_as = null;
 576                                 if (left is EnumConstant){
 577                                         if (right is EnumConstant){
 578                                                 if (left.Type != right.Type) {
 579                                                         Binary.Error_OperatorCannotBeApplied (loc, "-", left.Type, right.Type);
 580                                                         return null;
 581                                                 }
 582
 583                                                 wrap_as = TypeManager.EnumToUnderlying (left.Type);
 584                                                 right = ((EnumConstant) right).Child.ToType (wrap_as);
 585                                                 if (right == null)
 586                                                         return null;
 587
 588                                                 left = ((EnumConstant) left).Child.ToType (wrap_as);
 589                                                 if (left == null)
 590                                                         return null;
 591                                         }
 592                                         else {
 593                                                 right = right.ToType (((EnumConstant) left).Child.Type);
 594                                                 if (right == null)
 595                                                         return null;
 596
 597                                                 wrap_as = left.Type;
 598                                         }
 599                                 } else if (right is EnumConstant){
 600                                         left = left.ToType (((EnumConstant) right).Child.Type);
 601                                         if (left == null)
 602                                                 return null;
 603
 604                                         wrap_as = right.Type;
 605                                 }
 606
 607                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
 608                                 if (left == null || right == null)
 609                                         return null;
 610
 611                                 try {
 612                                         if (left is DoubleConstant){
 613                                                 double res;
 614
 615                                                 if (ec.ConstantCheckState)
 616                                                         res = checked (((DoubleConstant) left).Value -
 617                                                                        ((DoubleConstant) right).Value);
 618                                                 else
 619                                                         res = unchecked (((DoubleConstant) left).Value -
 620                                                                          ((DoubleConstant) right).Value);
 621
 622                                                 result = new DoubleConstant (res, left.Location);
 623                                         } else if (left is FloatConstant){
 624                                                 float res;
 625
 626                                                 if (ec.ConstantCheckState)
 627                                                         res = checked (((FloatConstant) left).Value -
 628                                                                        ((FloatConstant) right).Value);
 629                                                 else
 630                                                         res = unchecked (((FloatConstant) left).Value -
 631                                                                          ((FloatConstant) right).Value);
 632
 633                                                 result = new FloatConstant (res, left.Location);
 634                                         } else if (left is ULongConstant){
 635                                                 ulong res;
 636
 637                                                 if (ec.ConstantCheckState)
 638                                                         res = checked (((ULongConstant) left).Value -
 639                                                                        ((ULongConstant) right).Value);
 640                                                 else
 641                                                         res = unchecked (((ULongConstant) left).Value -
 642                                                                          ((ULongConstant) right).Value);
 643
 644                                                 result = new ULongConstant (res, left.Location);
 645                                         } else if (left is LongConstant){
 646                                                 long res;
 647
 648                                                 if (ec.ConstantCheckState)
 649                                                         res = checked (((LongConstant) left).Value -
 650                                                                        ((LongConstant) right).Value);
 651                                                 else
 652                                                         res = unchecked (((LongConstant) left).Value -
 653                                                                          ((LongConstant) right).Value);
 654
 655                                                 result = new LongConstant (res, left.Location);
 656                                         } else if (left is UIntConstant){
 657                                                 uint res;
 658
 659                                                 if (ec.ConstantCheckState)
 660                                                         res = checked (((UIntConstant) left).Value -
 661                                                                        ((UIntConstant) right).Value);
 662                                                 else
 663                                                         res = unchecked (((UIntConstant) left).Value -
 664                                                                          ((UIntConstant) right).Value);
 665
 666                                                 result = new UIntConstant (res, left.Location);
 667                                         } else if (left is IntConstant){
 668                                                 int res;
 669
 670                                                 if (ec.ConstantCheckState)
 671                                                         res = checked (((IntConstant) left).Value -
 672                                                                        ((IntConstant) right).Value);
 673                                                 else
 674                                                         res = unchecked (((IntConstant) left).Value -
 675                                                                          ((IntConstant) right).Value);
 676
 677                                                 result = new IntConstant (res, left.Location);
 678                                         } else if (left is DecimalConstant) {
 679                                                 decimal res;
 680
 681                                                 if (ec.ConstantCheckState)
 682                                                         res = checked (((DecimalConstant) left).Value -
 683                                                                 ((DecimalConstant) right).Value);
 684                                                 else
 685                                                         res = unchecked (((DecimalConstant) left).Value -
 686                                                                 ((DecimalConstant) right).Value);
 687
 688                                                 return new DecimalConstant (res, left.Location);
 689                                         } else {
 690                                                 throw new Exception ( "Unexepected subtraction input: " + left);
 691                                         }
 692                                 } catch (OverflowException){
 693                                         Error_CompileTimeOverflow (loc);
 694                                 }
 695
 696                                 if (wrap_as != null) {
 697                                         try {
 698                                                 return result.TryReduce (ec, wrap_as, loc);
 699                                         }
 700                                         catch (OverflowException) {
 701                                                 return null;
 702                                         }
 703                                 }
 704
 705                                 return result;
 706
 707                         case Binary.Operator.Multiply:
 708                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
 709                                 if (left == null || right == null)
 710                                         return null;
 711
 712                                 try {
 713                                         if (left is DoubleConstant){
 714                                                 double res;
 715
 716                                                 if (ec.ConstantCheckState)
 717                                                         res = checked (((DoubleConstant) left).Value *
 718                                                                 ((DoubleConstant) right).Value);
 719                                                 else
 720                                                         res = unchecked (((DoubleConstant) left).Value *
 721                                                                 ((DoubleConstant) right).Value);
 722
 723                                                 return new DoubleConstant (res, left.Location);
 724                                         } else if (left is FloatConstant){
 725                                                 float res;
 726
 727                                                 if (ec.ConstantCheckState)
 728                                                         res = checked (((FloatConstant) left).Value *
 729                                                                 ((FloatConstant) right).Value);
 730                                                 else
 731                                                         res = unchecked (((FloatConstant) left).Value *
 732                                                                 ((FloatConstant) right).Value);
 733
 734                                                 return new FloatConstant (res, left.Location);
 735                                         } else if (left is ULongConstant){
 736                                                 ulong res;
 737
 738                                                 if (ec.ConstantCheckState)
 739                                                         res = checked (((ULongConstant) left).Value *
 740                                                                 ((ULongConstant) right).Value);
 741                                                 else
 742                                                         res = unchecked (((ULongConstant) left).Value *
 743                                                                 ((ULongConstant) right).Value);
 744
 745                                                 return new ULongConstant (res, left.Location);
 746                                         } else if (left is LongConstant){
 747                                                 long res;
 748
 749                                                 if (ec.ConstantCheckState)
 750                                                         res = checked (((LongConstant) left).Value *
 751                                                                 ((LongConstant) right).Value);
 752                                                 else
 753                                                         res = unchecked (((LongConstant) left).Value *
 754                                                                 ((LongConstant) right).Value);
 755
 756                                                 return new LongConstant (res, left.Location);
 757                                         } else if (left is UIntConstant){
 758                                                 uint res;
 759
 760                                                 if (ec.ConstantCheckState)
 761                                                         res = checked (((UIntConstant) left).Value *
 762                                                                 ((UIntConstant) right).Value);
 763                                                 else
 764                                                         res = unchecked (((UIntConstant) left).Value *
 765                                                                 ((UIntConstant) right).Value);
 766
 767                                                 return new UIntConstant (res, left.Location);
 768                                         } else if (left is IntConstant){
 769                                                 int res;
 770
 771                                                 if (ec.ConstantCheckState)
 772                                                         res = checked (((IntConstant) left).Value *
 773                                                                 ((IntConstant) right).Value);
 774                                                 else
 775                                                         res = unchecked (((IntConstant) left).Value *
 776                                                                 ((IntConstant) right).Value);
 777
 778                                                 return new IntConstant (res, left.Location);
 779                                         } else if (left is DecimalConstant) {
 780                                                 decimal res;
 781
 782                                                 if (ec.ConstantCheckState)
 783                                                         res = checked (((DecimalConstant) left).Value *
 784                                                                 ((DecimalConstant) right).Value);
 785                                                 else
 786                                                         res = unchecked (((DecimalConstant) left).Value *
 787                                                                 ((DecimalConstant) right).Value);
 788
 789                                                 return new DecimalConstant (res, left.Location);
 790                                         } else {
 791                                                 throw new Exception ( "Unexepected multiply input: " + left);
 792                                         }
 793                                 } catch (OverflowException){
 794                                         Error_CompileTimeOverflow (loc);
 795                                 }
 796                                 break;
 797
 798                         case Binary.Operator.Division:
 799                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
 800                                 if (left == null || right == null)
 801                                         return null;
 802
 803                                 try {
 804                                         if (left is DoubleConstant){
 805                                                 double res;
 806
 807                                                 if (ec.ConstantCheckState)
 808                                                         res = checked (((DoubleConstant) left).Value /
 809                                                                 ((DoubleConstant) right).Value);
 810                                                 else
 811                                                         res = unchecked (((DoubleConstant) left).Value /
 812                                                                 ((DoubleConstant) right).Value);
 813
 814                                                 return new DoubleConstant (res, left.Location);
 815                                         } else if (left is FloatConstant){
 816                                                 float res;
 817
 818                                                 if (ec.ConstantCheckState)
 819                                                         res = checked (((FloatConstant) left).Value /
 820                                                                 ((FloatConstant) right).Value);
 821                                                 else
 822                                                         res = unchecked (((FloatConstant) left).Value /
 823                                                                 ((FloatConstant) right).Value);
 824
 825                                                 return new FloatConstant (res, left.Location);
 826                                         } else if (left is ULongConstant){
 827                                                 ulong res;
 828
 829                                                 if (ec.ConstantCheckState)
 830                                                         res = checked (((ULongConstant) left).Value /
 831                                                                 ((ULongConstant) right).Value);
 832                                                 else
 833                                                         res = unchecked (((ULongConstant) left).Value /
 834                                                                 ((ULongConstant) right).Value);
 835
 836                                                 return new ULongConstant (res, left.Location);
 837                                         } else if (left is LongConstant){
 838                                                 long res;
 839
 840                                                 if (ec.ConstantCheckState)
 841                                                         res = checked (((LongConstant) left).Value /
 842                                                                 ((LongConstant) right).Value);
 843                                                 else
 844                                                         res = unchecked (((LongConstant) left).Value /
 845                                                                 ((LongConstant) right).Value);
 846
 847                                                 return new LongConstant (res, left.Location);
 848                                         } else if (left is UIntConstant){
 849                                                 uint res;
 850
 851                                                 if (ec.ConstantCheckState)
 852                                                         res = checked (((UIntConstant) left).Value /
 853                                                                 ((UIntConstant) right).Value);
 854                                                 else
 855                                                         res = unchecked (((UIntConstant) left).Value /
 856                                                                 ((UIntConstant) right).Value);
 857
 858                                                 return new UIntConstant (res, left.Location);
 859                                         } else if (left is IntConstant){
 860                                                 int res;
 861
 862                                                 if (ec.ConstantCheckState)
 863                                                         res = checked (((IntConstant) left).Value /
 864                                                                 ((IntConstant) right).Value);
 865                                                 else
 866                                                         res = unchecked (((IntConstant) left).Value /
 867                                                                 ((IntConstant) right).Value);
 868
 869                                                 return new IntConstant (res, left.Location);
 870                                         } else if (left is DecimalConstant) {
 871                                                 decimal res;
 872
 873                                                 if (ec.ConstantCheckState)
 874                                                         res = checked (((DecimalConstant) left).Value /
 875                                                                 ((DecimalConstant) right).Value);
 876                                                 else
 877                                                         res = unchecked (((DecimalConstant) left).Value /
 878                                                                 ((DecimalConstant) right).Value);
 879
 880                                                 return new DecimalConstant (res, left.Location);
 881                                         } else {
 882                                                 throw new Exception ( "Unexepected division input: " + left);
 883                                         }
 884                                 } catch (OverflowException){
 885                                         Error_CompileTimeOverflow (loc);
 886
 887                                 } catch (DivideByZeroException) {
 888                                         Report.Error (020, loc, "Division by constant zero");
 889                                 }
 890
 891                                 break;
 892
 893                         case Binary.Operator.Modulus:
 894                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
 895                                 if (left == null || right == null)
 896                                         return null;
 897
 898                                 try {
 899                                         if (left is DoubleConstant){
 900                                                 double res;
 901
 902                                                 if (ec.ConstantCheckState)
 903                                                         res = checked (((DoubleConstant) left).Value %
 904                                                                        ((DoubleConstant) right).Value);
 905                                                 else
 906                                                         res = unchecked (((DoubleConstant) left).Value %
 907                                                                          ((DoubleConstant) right).Value);
 908
 909                                                 return new DoubleConstant (res, left.Location);
 910                                         } else if (left is FloatConstant){
 911                                                 float res;
 912
 913                                                 if (ec.ConstantCheckState)
 914                                                         res = checked (((FloatConstant) left).Value %
 915                                                                        ((FloatConstant) right).Value);
 916                                                 else
 917                                                         res = unchecked (((FloatConstant) left).Value %
 918                                                                          ((FloatConstant) right).Value);
 919
 920                                                 return new FloatConstant (res, left.Location);
 921                                         } else if (left is ULongConstant){
 922                                                 ulong res;
 923
 924                                                 if (ec.ConstantCheckState)
 925                                                         res = checked (((ULongConstant) left).Value %
 926                                                                        ((ULongConstant) right).Value);
 927                                                 else
 928                                                         res = unchecked (((ULongConstant) left).Value %
 929                                                                          ((ULongConstant) right).Value);
 930
 931                                                 return new ULongConstant (res, left.Location);
 932                                         } else if (left is LongConstant){
 933                                                 long res;
 934
 935                                                 if (ec.ConstantCheckState)
 936                                                         res = checked (((LongConstant) left).Value %
 937                                                                        ((LongConstant) right).Value);
 938                                                 else
 939                                                         res = unchecked (((LongConstant) left).Value %
 940                                                                          ((LongConstant) right).Value);
 941
 942                                                 return new LongConstant (res, left.Location);
 943                                         } else if (left is UIntConstant){
 944                                                 uint res;
 945
 946                                                 if (ec.ConstantCheckState)
 947                                                         res = checked (((UIntConstant) left).Value %
 948                                                                        ((UIntConstant) right).Value);
 949                                                 else
 950                                                         res = unchecked (((UIntConstant) left).Value %
 951                                                                          ((UIntConstant) right).Value);
 952
 953                                                 return new UIntConstant (res, left.Location);
 954                                         } else if (left is IntConstant){
 955                                                 int res;
 956
 957                                                 if (ec.ConstantCheckState)
 958                                                         res = checked (((IntConstant) left).Value %
 959                                                                        ((IntConstant) right).Value);
 960                                                 else
 961                                                         res = unchecked (((IntConstant) left).Value %
 962                                                                          ((IntConstant) right).Value);
 963
 964                                                 return new IntConstant (res, left.Location);
 965                                         } else {
 966                                                 throw new Exception ( "Unexepected modulus input: " + left);
 967                                         }
 968                                 } catch (DivideByZeroException){
 969                                         Report.Error (020, loc, "Division by constant zero");
 970                                 } catch (OverflowException){
 971                                         Error_CompileTimeOverflow (loc);
 972                                 }
 973                                 break;
 974
 975                                 //
 976                                 // There is no overflow checking on left shift
 977                                 //
 978                         case Binary.Operator.LeftShift:
 979                                 IntConstant ic = right.ToInt (loc);
 980                                 if (ic == null){
 981                                         Binary.Error_OperatorCannotBeApplied (loc, "<<", lt, rt);
 982                                         return null;
 983                                 }
 984                                 int lshift_val = ic.Value;
 985
 986                                 IntConstant lic;
 987                                 if ((lic = left.ConvertToInt ()) != null)
 988                                         return new IntConstant (lic.Value << lshift_val, left.Location);
 989
 990                                 UIntConstant luic;
 991                                 if ((luic = left.ConvertToUInt ()) != null)
 992                                         return new UIntConstant (luic.Value << lshift_val, left.Location);
 993
 994                                 LongConstant llc;
 995                                 if ((llc = left.ConvertToLong ()) != null)
 996                                         return new LongConstant (llc.Value << lshift_val, left.Location);
 997
 998                                 ULongConstant lulc;
 999                                 if ((lulc = left.ConvertToULong ()) != null)
1000                                         return new ULongConstant (lulc.Value << lshift_val, left.Location);
1001
1002                                 Binary.Error_OperatorCannotBeApplied (loc, "<<", lt, rt);
1003                                 break;
1004
1005                                 //
1006                                 // There is no overflow checking on right shift
1007                                 //
1008                         case Binary.Operator.RightShift:
1009                                 IntConstant sic = right.ToInt (loc);
1010                                 if (sic == null){
1011                                         Binary.Error_OperatorCannotBeApplied (loc, ">>", lt, rt);
1012                                         return null;
1013                                 }
1014                                 int rshift_val = sic.Value;
1015
1016                                 IntConstant ric;
1017                                 if ((ric = left.ConvertToInt ()) != null)
1018                                         return new IntConstant (ric.Value >> rshift_val, left.Location);
1019
1020                                 UIntConstant ruic;
1021                                 if ((ruic = left.ConvertToUInt ()) != null)
1022                                         return new UIntConstant (ruic.Value >> rshift_val, left.Location);
1023
1024                                 LongConstant rlc;
1025                                 if ((rlc = left.ConvertToLong ()) != null)
1026                                         return new LongConstant (rlc.Value >> rshift_val, left.Location);
1027
1028                                 ULongConstant rulc;
1029                                 if ((rulc = left.ConvertToULong ()) != null)
1030                                         return new ULongConstant (rulc.Value >> rshift_val, left.Location);
1031
1032                                 Binary.Error_OperatorCannotBeApplied (loc, ">>", lt, rt);
1033                                 break;
1034
1035                         case Binary.Operator.Equality:
1036                                 if (left is NullConstant){
1037                                         if (right is NullConstant)
1038                                                 return new BoolConstant (true, left.Location);
1039                                         else if (right is StringConstant)
1040                                                 return new BoolConstant (
1041                                                         ((StringConstant) right).Value == null, left.Location);
1042                                 } else if (right is NullConstant){
1043                                         if (left is NullConstant)
1044                                                 return new BoolConstant (true, left.Location);
1045                                         else if (left is StringConstant)
1046                                                 return new BoolConstant (
1047                                                         ((StringConstant) left).Value == null, left.Location);
1048                                 }
1049                                 if (left is StringConstant && right is StringConstant){
1050                                         return new BoolConstant (
1051                                                 ((StringConstant) left).Value ==
1052                                                 ((StringConstant) right).Value, left.Location);
1053
1054                                 }
1055
1056                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
1057                                 if (left == null || right == null)
1058                                         return null;
1059
1060                                 bool_res = false;
1061                                 if (left is DoubleConstant)
1062                                         bool_res = ((DoubleConstant) left).Value ==
1063                                                 ((DoubleConstant) right).Value;
1064                                 else if (left is FloatConstant)
1065                                         bool_res = ((FloatConstant) left).Value ==
1066                                                 ((FloatConstant) right).Value;
1067                                 else if (left is ULongConstant)
1068                                         bool_res = ((ULongConstant) left).Value ==
1069                                                 ((ULongConstant) right).Value;
1070                                 else if (left is LongConstant)
1071                                         bool_res = ((LongConstant) left).Value ==
1072                                                 ((LongConstant) right).Value;
1073                                 else if (left is UIntConstant)
1074                                         bool_res = ((UIntConstant) left).Value ==
1075                                                 ((UIntConstant) right).Value;
1076                                 else if (left is IntConstant)
1077                                         bool_res = ((IntConstant) left).Value ==
1078                                                 ((IntConstant) right).Value;
1079                                 else
1080                                         return null;
1081
1082                                 return new BoolConstant (bool_res, left.Location);
1083
1084                         case Binary.Operator.Inequality:
1085                                 if (left is NullConstant){
1086                                         if (right is NullConstant)
1087                                                 return new BoolConstant (false, left.Location);
1088                                         else if (right is StringConstant)
1089                                                 return new BoolConstant (
1090                                                         ((StringConstant) right).Value != null, left.Location);
1091                                 } else if (right is NullConstant){
1092                                         if (left is NullConstant)
1093                                                 return new BoolConstant (false, left.Location);
1094                                         else if (left is StringConstant)
1095                                                 return new BoolConstant (
1096                                                         ((StringConstant) left).Value != null, left.Location);
1097                                 }
1098                                 if (left is StringConstant && right is StringConstant){
1099                                         return new BoolConstant (
1100                                                 ((StringConstant) left).Value !=
1101                                                 ((StringConstant) right).Value, left.Location);
1102
1103                                 }
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, left.Location);
1131
1132                         case Binary.Operator.LessThan:
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, left.Location);
1160
1161                         case Binary.Operator.GreaterThan:
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, left.Location);
1189
1190                         case Binary.Operator.GreaterThanOrEqual:
1191                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
1192                                 if (left == null || right == null)
1193                                         return null;
1194
1195                                 bool_res = false;
1196                                 if (left is DoubleConstant)
1197                                         bool_res = ((DoubleConstant) left).Value >=
1198                                                 ((DoubleConstant) right).Value;
1199                                 else if (left is FloatConstant)
1200                                         bool_res = ((FloatConstant) left).Value >=
1201                                                 ((FloatConstant) right).Value;
1202                                 else if (left is ULongConstant)
1203                                         bool_res = ((ULongConstant) left).Value >=
1204                                                 ((ULongConstant) right).Value;
1205                                 else if (left is LongConstant)
1206                                         bool_res = ((LongConstant) left).Value >=
1207                                                 ((LongConstant) right).Value;
1208                                 else if (left is UIntConstant)
1209                                         bool_res = ((UIntConstant) left).Value >=
1210                                                 ((UIntConstant) right).Value;
1211                                 else if (left is IntConstant)
1212                                         bool_res = ((IntConstant) left).Value >=
1213                                                 ((IntConstant) right).Value;
1214                                 else
1215                                         return null;
1216
1217                                 return new BoolConstant (bool_res, left.Location);
1218
1219                         case Binary.Operator.LessThanOrEqual:
1220                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
1221                                 if (left == null || right == null)
1222                                         return null;
1223
1224                                 bool_res = false;
1225                                 if (left is DoubleConstant)
1226                                         bool_res = ((DoubleConstant) left).Value <=
1227                                                 ((DoubleConstant) right).Value;
1228                                 else if (left is FloatConstant)
1229                                         bool_res = ((FloatConstant) left).Value <=
1230                                                 ((FloatConstant) right).Value;
1231                                 else if (left is ULongConstant)
1232                                         bool_res = ((ULongConstant) left).Value <=
1233                                                 ((ULongConstant) right).Value;
1234                                 else if (left is LongConstant)
1235                                         bool_res = ((LongConstant) left).Value <=
1236                                                 ((LongConstant) right).Value;
1237                                 else if (left is UIntConstant)
1238                                         bool_res = ((UIntConstant) left).Value <=
1239                                                 ((UIntConstant) right).Value;
1240                                 else if (left is IntConstant)
1241                                         bool_res = ((IntConstant) left).Value <=
1242                                                 ((IntConstant) right).Value;
1243                                 else
1244                                         return null;
1245
1246                                 return new BoolConstant (bool_res, left.Location);
1247                         }
1248
1249                         return null;
1250                 }
1251         }
1252 }