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