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                                 //
 145                                 // If either operand is an enum constant, the other one must
 146                                 // be implicitly convertable to that enum's underlying type.
 147                                 //
 148                                 EnumConstant match;
 149                                 Constant other;
 150                                 if (left is EnumConstant){
 151                                         other = right;
 152                                         match = (EnumConstant) left;
 153                                 } else {
 154                                         other = left;
 155                                         match = (EnumConstant) right;
 156                                 }
 157
 158                                 bool need_check = (other is EnumConstant) ||
 159                                         !(oper == Binary.Operator.Addition ||
 160                                           oper == Binary.Operator.Subtraction ||
 161                                           (other.IsZeroInteger && other is IntConstant));
 162
 163                                 if (need_check &&
 164                                     !Convert.ImplicitConversionExists (ec, match, other.Type)) {
 165                                         Convert.Error_CannotImplicitConversion (loc, match.Type, other.Type);
 166                                         left = null;
 167                                         right = null;
 168                                         return;
 169                                 }
 170
 171                                 if (left is EnumConstant)
 172                                         left = ((EnumConstant) left).Child;
 173                                 if (right is EnumConstant)
 174                                         right = ((EnumConstant) right).Child;
 175
 176                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
 177                                 return;
 178
 179                         } else {
 180                                 //
 181                                 // Force conversions to int32
 182                                 //
 183                                 if (!(left is IntConstant))
 184                                         left = left.ToInt (loc);
 185                                 if (!(right is IntConstant))
 186                                         right = right.ToInt (loc);
 187                         }
 188                         return;
 189                 }
 190
 191                 static void Error_CompileTimeOverflow (Location loc)
 192                 {
 193                         Report.Error (220, loc, "The operation overflows at compile time in checked mode");
 194                 }
 195
 196                 /// <summary>
 197                 ///   Constant expression folder for binary operations.
 198                 ///
 199                 ///   Returns null if the expression can not be folded.
 200                 /// </summary>
 201                 static public Expression BinaryFold (EmitContext ec, Binary.Operator oper,
 202                                                      Constant left, Constant right, Location loc)
 203                 {
 204                         Type lt = left.Type;
 205                         Type rt = right.Type;
 206                         Type result_type = null;
 207                         bool bool_res;
 208
 209                         //
 210                         // Enumerator folding
 211                         //
 212                         if (rt == lt && left is EnumConstant)
 213                                 result_type = lt;
 214
 215                         //
 216                         // During an enum evaluation, we need to unwrap enumerations
 217                         //
 218                         if (ec.InEnumContext){
 219                                 if (left is EnumConstant)
 220                                         left = ((EnumConstant) left).Child;
 221
 222                                 if (right is EnumConstant)
 223                                         right = ((EnumConstant) right).Child;
 224                         }
 225
 226                         Type wrap_as;
 227                         Constant result = null;
 228                         switch (oper){
 229                         case Binary.Operator.BitwiseOr:
 230                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
 231                                 if (left == null || right == null)
 232                                         return null;
 233
 234                                 if (left is IntConstant){
 235                                         IntConstant v;
 236                                         int res = ((IntConstant) left).Value | ((IntConstant) right).Value;
 237
 238                                         v = new IntConstant (res, left.Location);
 239                                         if (result_type == null)
 240                                                 return v;
 241                                         else
 242                                                 return new EnumConstant (v, result_type);
 243                                 } else if (left is UIntConstant){
 244                                         UIntConstant v;
 245                                         uint res = ((UIntConstant)left).Value | ((UIntConstant)right).Value;
 246
 247                                         v = new UIntConstant (res, left.Location);
 248                                         if (result_type == null)
 249                                                 return v;
 250                                         else
 251                                                 return new EnumConstant (v, result_type);
 252                                 } else if (left is LongConstant){
 253                                         LongConstant v;
 254                                         long res = ((LongConstant)left).Value | ((LongConstant)right).Value;
 255
 256                                         v = new LongConstant (res, left.Location);
 257                                         if (result_type == null)
 258                                                 return v;
 259                                         else
 260                                                 return new EnumConstant (v, result_type);
 261                                 } else if (left is ULongConstant){
 262                                         ULongConstant v;
 263                                         ulong res = ((ULongConstant)left).Value |
 264                                                 ((ULongConstant)right).Value;
 265
 266                                         v = new ULongConstant (res, left.Location);
 267                                         if (result_type == null)
 268                                                 return v;
 269                                         else
 270                                                 return new EnumConstant (v, result_type);
 271                                 } else if (left is UShortConstant){
 272                                         UShortConstant v;
 273                                         ushort res = (ushort) (((UShortConstant)left).Value |
 274                                                                ((UShortConstant)right).Value);
 275
 276                                         v = new UShortConstant (res, left.Location);
 277                                         if (result_type == null)
 278                                                 return v;
 279                                         else
 280                                                 return new EnumConstant (v, result_type);
 281                                 } else if (left is ShortConstant){
 282                                         ShortConstant v;
 283                                         short res = (short) (((ShortConstant)left).Value |
 284                                                              ((ShortConstant)right).Value);
 285
 286                                         v = new ShortConstant (res, left.Location);
 287                                         if (result_type == null)
 288                                                 return v;
 289                                         else
 290                                                 return new EnumConstant (v, result_type);
 291                                 }
 292                                 break;
 293
 294                         case Binary.Operator.BitwiseAnd:
 295                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
 296                                 if (left == null || right == null)
 297                                         return null;
 298
 299                                 if (left is IntConstant){
 300                                         IntConstant v;
 301                                         int res = ((IntConstant) left).Value & ((IntConstant) right).Value;
 302
 303                                         v = new IntConstant (res, left.Location);
 304                                         if (result_type == null)
 305                                                 return v;
 306                                         else
 307                                                 return new EnumConstant (v, result_type);
 308                                 } else if (left is UIntConstant){
 309                                         UIntConstant v;
 310                                         uint res = ((UIntConstant)left).Value & ((UIntConstant)right).Value;
 311
 312                                         v = new UIntConstant (res, left.Location);
 313                                         if (result_type == null)
 314                                                 return v;
 315                                         else
 316                                                 return new EnumConstant (v, result_type);
 317                                 } else if (left is LongConstant){
 318                                         LongConstant v;
 319                                         long res = ((LongConstant)left).Value & ((LongConstant)right).Value;
 320
 321                                         v = new LongConstant (res, left.Location);
 322                                         if (result_type == null)
 323                                                 return v;
 324                                         else
 325                                                 return new EnumConstant (v, result_type);
 326                                 } else if (left is ULongConstant){
 327                                         ULongConstant v;
 328                                         ulong res = ((ULongConstant)left).Value &
 329                                                 ((ULongConstant)right).Value;
 330
 331                                         v = new ULongConstant (res, left.Location);
 332                                         if (result_type == null)
 333                                                 return v;
 334                                         else
 335                                                 return new EnumConstant (v, result_type);
 336                                 } else if (left is UShortConstant){
 337                                         UShortConstant v;
 338                                         ushort res = (ushort) (((UShortConstant)left).Value &
 339                                                                ((UShortConstant)right).Value);
 340
 341                                         v = new UShortConstant (res, left.Location);
 342                                         if (result_type == null)
 343                                                 return v;
 344                                         else
 345                                                 return new EnumConstant (v, result_type);
 346                                 } else if (left is ShortConstant){
 347                                         ShortConstant v;
 348                                         short res = (short) (((ShortConstant)left).Value &
 349                                                              ((ShortConstant)right).Value);
 350
 351                                         v = new ShortConstant (res, left.Location);
 352                                         if (result_type == null)
 353                                                 return v;
 354                                         else
 355                                                 return new EnumConstant (v, result_type);
 356                                 }
 357                                 break;
 358
 359                         case Binary.Operator.ExclusiveOr:
 360                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
 361                                 if (left == null || right == null)
 362                                         return null;
 363
 364                                 if (left is IntConstant){
 365                                         IntConstant v;
 366                                         int res = ((IntConstant) left).Value ^ ((IntConstant) right).Value;
 367
 368                                         v = new IntConstant (res, left.Location);
 369                                         if (result_type == null)
 370                                                 return v;
 371                                         else
 372                                                 return new EnumConstant (v, result_type);
 373                                 } else if (left is UIntConstant){
 374                                         UIntConstant v;
 375                                         uint res = ((UIntConstant)left).Value ^ ((UIntConstant)right).Value;
 376
 377                                         v = new UIntConstant (res, left.Location);
 378                                         if (result_type == null)
 379                                                 return v;
 380                                         else
 381                                                 return new EnumConstant (v, result_type);
 382                                 } else if (left is LongConstant){
 383                                         LongConstant v;
 384                                         long res = ((LongConstant)left).Value ^ ((LongConstant)right).Value;
 385
 386                                         v = new LongConstant (res, left.Location);
 387                                         if (result_type == null)
 388                                                 return v;
 389                                         else
 390                                                 return new EnumConstant (v, result_type);
 391                                 } else if (left is ULongConstant){
 392                                         ULongConstant v;
 393                                         ulong res = ((ULongConstant)left).Value ^
 394                                                 ((ULongConstant)right).Value;
 395
 396                                         v = new ULongConstant (res, left.Location);
 397                                         if (result_type == null)
 398                                                 return v;
 399                                         else
 400                                                 return new EnumConstant (v, result_type);
 401                                 } else if (left is UShortConstant){
 402                                         UShortConstant v;
 403                                         ushort res = (ushort) (((UShortConstant)left).Value ^
 404                                                                ((UShortConstant)right).Value);
 405
 406                                         v = new UShortConstant (res, left.Location);
 407                                         if (result_type == null)
 408                                                 return v;
 409                                         else
 410                                                 return new EnumConstant (v, result_type);
 411                                 } else if (left is ShortConstant){
 412                                         ShortConstant v;
 413                                         short res = (short)(((ShortConstant)left).Value ^
 414                                                             ((ShortConstant)right).Value);
 415
 416                                         v = new ShortConstant (res, left.Location);
 417                                         if (result_type == null)
 418                                                 return v;
 419                                         else
 420                                                 return new EnumConstant (v, result_type);
 421                                 }
 422                                 break;
 423
 424                         case Binary.Operator.Addition:
 425                                 bool left_is_string = left is StringConstant;
 426                                 bool right_is_string = right is StringConstant;
 427
 428                                 //
 429                                 // If both sides are strings, then concatenate, if
 430                                 // one is a string, and the other is not, then defer
 431                                 // to runtime concatenation
 432                                 //
 433                                 wrap_as = null;
 434                                 if (left_is_string || right_is_string){
 435                                         if (left_is_string && right_is_string)
 436                                                 return new StringConstant (
 437                                                         ((StringConstant) left).Value +
 438                                                         ((StringConstant) right).Value, left.Location);
 439
 440                                         return null;
 441                                 }
 442
 443                                 //
 444                                 // handle "E operator + (E x, U y)"
 445                                 // handle "E operator + (Y y, E x)"
 446                                 //
 447                                 // note that E operator + (E x, E y) is invalid
 448                                 //
 449                                 if (left is EnumConstant){
 450                                         if (right is EnumConstant){
 451                                                 return null;
 452                                         }
 453
 454                                         right = right.ToType (((EnumConstant) left).Child.Type, loc);
 455                                         if (right == null)
 456                                                 return null;
 457
 458                                         wrap_as = left.Type;
 459                                 } else if (right is EnumConstant){
 460                                         left = left.ToType (((EnumConstant) right).Child.Type, loc);
 461                                         if (left == null)
 462                                                 return null;
 463
 464                                         wrap_as = right.Type;
 465                                 }
 466
 467                                 result = null;
 468                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
 469                                 if (left == null || right == null)
 470                                         return null;
 471
 472                                 try {
 473                                         if (left is DoubleConstant){
 474                                                 double res;
 475
 476                                                 if (ec.ConstantCheckState)
 477                                                         res = checked (((DoubleConstant) left).Value +
 478                                                                        ((DoubleConstant) right).Value);
 479                                                 else
 480                                                         res = unchecked (((DoubleConstant) left).Value +
 481                                                                          ((DoubleConstant) right).Value);
 482
 483                                                 result = new DoubleConstant (res, left.Location);
 484                                         } else if (left is FloatConstant){
 485                                                 float res;
 486
 487                                                 if (ec.ConstantCheckState)
 488                                                         res = checked (((FloatConstant) left).Value +
 489                                                                        ((FloatConstant) right).Value);
 490                                                 else
 491                                                         res = unchecked (((FloatConstant) left).Value +
 492                                                                          ((FloatConstant) right).Value);
 493
 494                                                 result = new FloatConstant (res, left.Location);
 495                                         } else if (left is ULongConstant){
 496                                                 ulong res;
 497
 498                                                 if (ec.ConstantCheckState)
 499                                                         res = checked (((ULongConstant) left).Value +
 500                                                                        ((ULongConstant) right).Value);
 501                                                 else
 502                                                         res = unchecked (((ULongConstant) left).Value +
 503                                                                          ((ULongConstant) right).Value);
 504
 505                                                 result = new ULongConstant (res, left.Location);
 506                                         } else if (left is LongConstant){
 507                                                 long res;
 508
 509                                                 if (ec.ConstantCheckState)
 510                                                         res = checked (((LongConstant) left).Value +
 511                                                                        ((LongConstant) right).Value);
 512                                                 else
 513                                                         res = unchecked (((LongConstant) left).Value +
 514                                                                          ((LongConstant) right).Value);
 515
 516                                                 result = new LongConstant (res, left.Location);
 517                                         } else if (left is UIntConstant){
 518                                                 uint res;
 519
 520                                                 if (ec.ConstantCheckState)
 521                                                         res = checked (((UIntConstant) left).Value +
 522                                                                        ((UIntConstant) right).Value);
 523                                                 else
 524                                                         res = unchecked (((UIntConstant) left).Value +
 525                                                                          ((UIntConstant) right).Value);
 526
 527                                                 result = new UIntConstant (res, left.Location);
 528                                         } else if (left is IntConstant){
 529                                                 int res;
 530
 531                                                 if (ec.ConstantCheckState)
 532                                                         res = checked (((IntConstant) left).Value +
 533                                                                        ((IntConstant) right).Value);
 534                                                 else
 535                                                         res = unchecked (((IntConstant) left).Value +
 536                                                                          ((IntConstant) right).Value);
 537
 538                                                 result = new IntConstant (res, left.Location);
 539                                         } else if (left is DecimalConstant) {
 540                                                 decimal res;
 541
 542                                                 if (ec.ConstantCheckState)
 543                                                         res = checked (((DecimalConstant) left).Value +
 544                                                                 ((DecimalConstant) right).Value);
 545                                                 else
 546                                                         res = unchecked (((DecimalConstant) left).Value +
 547                                                                 ((DecimalConstant) right).Value);
 548
 549                                                 result = new DecimalConstant (res, left.Location);
 550                                         } else {
 551                                                 throw new Exception ( "Unexepected addition input: " + left);
 552                                         }
 553                                 } catch (OverflowException){
 554                                         Error_CompileTimeOverflow (loc);
 555                                 }
 556
 557                                 if (wrap_as != null)
 558                                         return new EnumConstant (result, wrap_as);
 559                                 else
 560                                         return result;
 561
 562                         case Binary.Operator.Subtraction:
 563                                 //
 564                                 // handle "E operator - (E x, U y)"
 565                                 // handle "E operator - (Y y, E x)"
 566                                 // handle "U operator - (E x, E y)"
 567                                 //
 568                                 wrap_as = null;
 569                                 if (left is EnumConstant){
 570                                         if (right is EnumConstant){
 571                                                 if (left.Type != right.Type) {
 572                                                         Binary.Error_OperatorCannotBeApplied (loc, "-", left.Type, right.Type);
 573                                                         return null;
 574                                                 }
 575
 576                                                 wrap_as = TypeManager.EnumToUnderlying (left.Type);
 577                                                 right = ((EnumConstant) right).Child.ToType (wrap_as, loc);
 578                                                 if (right == null)
 579                                                         return null;
 580
 581                                                 left = ((EnumConstant) left).Child.ToType (wrap_as, loc);
 582                                                 if (left == null)
 583                                                         return null;
 584                                         }
 585                                         else {
 586                                                 right = right.ToType (((EnumConstant) left).Child.Type, loc);
 587                                                 if (right == null)
 588                                                         return null;
 589
 590                                                 wrap_as = left.Type;
 591                                         }
 592                                 } else if (right is EnumConstant){
 593                                         left = left.ToType (((EnumConstant) right).Child.Type, loc);
 594                                         if (left == null)
 595                                                 return null;
 596
 597                                         wrap_as = right.Type;
 598                                 }
 599
 600                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
 601                                 if (left == null || right == null)
 602                                         return null;
 603
 604                                 try {
 605                                         if (left is DoubleConstant){
 606                                                 double res;
 607
 608                                                 if (ec.ConstantCheckState)
 609                                                         res = checked (((DoubleConstant) left).Value -
 610                                                                        ((DoubleConstant) right).Value);
 611                                                 else
 612                                                         res = unchecked (((DoubleConstant) left).Value -
 613                                                                          ((DoubleConstant) right).Value);
 614
 615                                                 result = new DoubleConstant (res, left.Location);
 616                                         } else if (left is FloatConstant){
 617                                                 float res;
 618
 619                                                 if (ec.ConstantCheckState)
 620                                                         res = checked (((FloatConstant) left).Value -
 621                                                                        ((FloatConstant) right).Value);
 622                                                 else
 623                                                         res = unchecked (((FloatConstant) left).Value -
 624                                                                          ((FloatConstant) right).Value);
 625
 626                                                 result = new FloatConstant (res, left.Location);
 627                                         } else if (left is ULongConstant){
 628                                                 ulong res;
 629
 630                                                 if (ec.ConstantCheckState)
 631                                                         res = checked (((ULongConstant) left).Value -
 632                                                                        ((ULongConstant) right).Value);
 633                                                 else
 634                                                         res = unchecked (((ULongConstant) left).Value -
 635                                                                          ((ULongConstant) right).Value);
 636
 637                                                 result = new ULongConstant (res, left.Location);
 638                                         } else if (left is LongConstant){
 639                                                 long res;
 640
 641                                                 if (ec.ConstantCheckState)
 642                                                         res = checked (((LongConstant) left).Value -
 643                                                                        ((LongConstant) right).Value);
 644                                                 else
 645                                                         res = unchecked (((LongConstant) left).Value -
 646                                                                          ((LongConstant) right).Value);
 647
 648                                                 result = new LongConstant (res, left.Location);
 649                                         } else if (left is UIntConstant){
 650                                                 uint res;
 651
 652                                                 if (ec.ConstantCheckState)
 653                                                         res = checked (((UIntConstant) left).Value -
 654                                                                        ((UIntConstant) right).Value);
 655                                                 else
 656                                                         res = unchecked (((UIntConstant) left).Value -
 657                                                                          ((UIntConstant) right).Value);
 658
 659                                                 result = new UIntConstant (res, left.Location);
 660                                         } else if (left is IntConstant){
 661                                                 int res;
 662
 663                                                 if (ec.ConstantCheckState)
 664                                                         res = checked (((IntConstant) left).Value -
 665                                                                        ((IntConstant) right).Value);
 666                                                 else
 667                                                         res = unchecked (((IntConstant) left).Value -
 668                                                                          ((IntConstant) right).Value);
 669
 670                                                 result = new IntConstant (res, left.Location);
 671                                         } else if (left is DecimalConstant) {
 672                                                 decimal res;
 673
 674                                                 if (ec.ConstantCheckState)
 675                                                         res = checked (((DecimalConstant) left).Value -
 676                                                                 ((DecimalConstant) right).Value);
 677                                                 else
 678                                                         res = unchecked (((DecimalConstant) left).Value -
 679                                                                 ((DecimalConstant) right).Value);
 680
 681                                                 return new DecimalConstant (res, left.Location);
 682                                         } else {
 683                                                 throw new Exception ( "Unexepected subtraction input: " + left);
 684                                         }
 685                                 } catch (OverflowException){
 686                                         Error_CompileTimeOverflow (loc);
 687                                 }
 688                                 if (wrap_as != null)
 689                                         return new EnumConstant (result, wrap_as);
 690                                 else
 691                                         return result;
 692
 693                         case Binary.Operator.Multiply:
 694                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
 695                                 if (left == null || right == null)
 696                                         return null;
 697
 698                                 try {
 699                                         if (left is DoubleConstant){
 700                                                 double res;
 701
 702                                                 if (ec.ConstantCheckState)
 703                                                         res = checked (((DoubleConstant) left).Value *
 704                                                                 ((DoubleConstant) right).Value);
 705                                                 else
 706                                                         res = unchecked (((DoubleConstant) left).Value *
 707                                                                 ((DoubleConstant) right).Value);
 708
 709                                                 return new DoubleConstant (res, left.Location);
 710                                         } else if (left is FloatConstant){
 711                                                 float res;
 712
 713                                                 if (ec.ConstantCheckState)
 714                                                         res = checked (((FloatConstant) left).Value *
 715                                                                 ((FloatConstant) right).Value);
 716                                                 else
 717                                                         res = unchecked (((FloatConstant) left).Value *
 718                                                                 ((FloatConstant) right).Value);
 719
 720                                                 return new FloatConstant (res, left.Location);
 721                                         } else if (left is ULongConstant){
 722                                                 ulong res;
 723
 724                                                 if (ec.ConstantCheckState)
 725                                                         res = checked (((ULongConstant) left).Value *
 726                                                                 ((ULongConstant) right).Value);
 727                                                 else
 728                                                         res = unchecked (((ULongConstant) left).Value *
 729                                                                 ((ULongConstant) right).Value);
 730
 731                                                 return new ULongConstant (res, left.Location);
 732                                         } else if (left is LongConstant){
 733                                                 long res;
 734
 735                                                 if (ec.ConstantCheckState)
 736                                                         res = checked (((LongConstant) left).Value *
 737                                                                 ((LongConstant) right).Value);
 738                                                 else
 739                                                         res = unchecked (((LongConstant) left).Value *
 740                                                                 ((LongConstant) right).Value);
 741
 742                                                 return new LongConstant (res, left.Location);
 743                                         } else if (left is UIntConstant){
 744                                                 uint res;
 745
 746                                                 if (ec.ConstantCheckState)
 747                                                         res = checked (((UIntConstant) left).Value *
 748                                                                 ((UIntConstant) right).Value);
 749                                                 else
 750                                                         res = unchecked (((UIntConstant) left).Value *
 751                                                                 ((UIntConstant) right).Value);
 752
 753                                                 return new UIntConstant (res, left.Location);
 754                                         } else if (left is IntConstant){
 755                                                 int res;
 756
 757                                                 if (ec.ConstantCheckState)
 758                                                         res = checked (((IntConstant) left).Value *
 759                                                                 ((IntConstant) right).Value);
 760                                                 else
 761                                                         res = unchecked (((IntConstant) left).Value *
 762                                                                 ((IntConstant) right).Value);
 763
 764                                                 return new IntConstant (res, left.Location);
 765                                         } else if (left is DecimalConstant) {
 766                                                 decimal res;
 767
 768                                                 if (ec.ConstantCheckState)
 769                                                         res = checked (((DecimalConstant) left).Value *
 770                                                                 ((DecimalConstant) right).Value);
 771                                                 else
 772                                                         res = unchecked (((DecimalConstant) left).Value *
 773                                                                 ((DecimalConstant) right).Value);
 774
 775                                                 return new DecimalConstant (res, left.Location);
 776                                         } else {
 777                                                 throw new Exception ( "Unexepected multiply input: " + left);
 778                                         }
 779                                 } catch (OverflowException){
 780                                         Error_CompileTimeOverflow (loc);
 781                                 }
 782                                 break;
 783
 784                         case Binary.Operator.Division:
 785                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
 786                                 if (left == null || right == null)
 787                                         return null;
 788
 789                                 try {
 790                                         if (left is DoubleConstant){
 791                                                 double res;
 792
 793                                                 if (ec.ConstantCheckState)
 794                                                         res = checked (((DoubleConstant) left).Value /
 795                                                                 ((DoubleConstant) right).Value);
 796                                                 else
 797                                                         res = unchecked (((DoubleConstant) left).Value /
 798                                                                 ((DoubleConstant) right).Value);
 799
 800                                                 return new DoubleConstant (res, left.Location);
 801                                         } else if (left is FloatConstant){
 802                                                 float res;
 803
 804                                                 if (ec.ConstantCheckState)
 805                                                         res = checked (((FloatConstant) left).Value /
 806                                                                 ((FloatConstant) right).Value);
 807                                                 else
 808                                                         res = unchecked (((FloatConstant) left).Value /
 809                                                                 ((FloatConstant) right).Value);
 810
 811                                                 return new FloatConstant (res, left.Location);
 812                                         } else if (left is ULongConstant){
 813                                                 ulong res;
 814
 815                                                 if (ec.ConstantCheckState)
 816                                                         res = checked (((ULongConstant) left).Value /
 817                                                                 ((ULongConstant) right).Value);
 818                                                 else
 819                                                         res = unchecked (((ULongConstant) left).Value /
 820                                                                 ((ULongConstant) right).Value);
 821
 822                                                 return new ULongConstant (res, left.Location);
 823                                         } else if (left is LongConstant){
 824                                                 long res;
 825
 826                                                 if (ec.ConstantCheckState)
 827                                                         res = checked (((LongConstant) left).Value /
 828                                                                 ((LongConstant) right).Value);
 829                                                 else
 830                                                         res = unchecked (((LongConstant) left).Value /
 831                                                                 ((LongConstant) right).Value);
 832
 833                                                 return new LongConstant (res, left.Location);
 834                                         } else if (left is UIntConstant){
 835                                                 uint res;
 836
 837                                                 if (ec.ConstantCheckState)
 838                                                         res = checked (((UIntConstant) left).Value /
 839                                                                 ((UIntConstant) right).Value);
 840                                                 else
 841                                                         res = unchecked (((UIntConstant) left).Value /
 842                                                                 ((UIntConstant) right).Value);
 843
 844                                                 return new UIntConstant (res, left.Location);
 845                                         } else if (left is IntConstant){
 846                                                 int res;
 847
 848                                                 if (ec.ConstantCheckState)
 849                                                         res = checked (((IntConstant) left).Value /
 850                                                                 ((IntConstant) right).Value);
 851                                                 else
 852                                                         res = unchecked (((IntConstant) left).Value /
 853                                                                 ((IntConstant) right).Value);
 854
 855                                                 return new IntConstant (res, left.Location);
 856                                         } else if (left is DecimalConstant) {
 857                                                 decimal res;
 858
 859                                                 if (ec.ConstantCheckState)
 860                                                         res = checked (((DecimalConstant) left).Value /
 861                                                                 ((DecimalConstant) right).Value);
 862                                                 else
 863                                                         res = unchecked (((DecimalConstant) left).Value /
 864                                                                 ((DecimalConstant) right).Value);
 865
 866                                                 return new DecimalConstant (res, left.Location);
 867                                         } else {
 868                                                 throw new Exception ( "Unexepected division input: " + left);
 869                                         }
 870                                 } catch (OverflowException){
 871                                         Error_CompileTimeOverflow (loc);
 872
 873                                 } catch (DivideByZeroException) {
 874                                         Report.Error (020, loc, "Division by constant zero");
 875                                 }
 876
 877                                 break;
 878
 879                         case Binary.Operator.Modulus:
 880                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
 881                                 if (left == null || right == null)
 882                                         return null;
 883
 884                                 try {
 885                                         if (left is DoubleConstant){
 886                                                 double res;
 887
 888                                                 if (ec.ConstantCheckState)
 889                                                         res = checked (((DoubleConstant) left).Value %
 890                                                                        ((DoubleConstant) right).Value);
 891                                                 else
 892                                                         res = unchecked (((DoubleConstant) left).Value %
 893                                                                          ((DoubleConstant) right).Value);
 894
 895                                                 return new DoubleConstant (res, left.Location);
 896                                         } else if (left is FloatConstant){
 897                                                 float res;
 898
 899                                                 if (ec.ConstantCheckState)
 900                                                         res = checked (((FloatConstant) left).Value %
 901                                                                        ((FloatConstant) right).Value);
 902                                                 else
 903                                                         res = unchecked (((FloatConstant) left).Value %
 904                                                                          ((FloatConstant) right).Value);
 905
 906                                                 return new FloatConstant (res, left.Location);
 907                                         } else if (left is ULongConstant){
 908                                                 ulong res;
 909
 910                                                 if (ec.ConstantCheckState)
 911                                                         res = checked (((ULongConstant) left).Value %
 912                                                                        ((ULongConstant) right).Value);
 913                                                 else
 914                                                         res = unchecked (((ULongConstant) left).Value %
 915                                                                          ((ULongConstant) right).Value);
 916
 917                                                 return new ULongConstant (res, left.Location);
 918                                         } else if (left is LongConstant){
 919                                                 long res;
 920
 921                                                 if (ec.ConstantCheckState)
 922                                                         res = checked (((LongConstant) left).Value %
 923                                                                        ((LongConstant) right).Value);
 924                                                 else
 925                                                         res = unchecked (((LongConstant) left).Value %
 926                                                                          ((LongConstant) right).Value);
 927
 928                                                 return new LongConstant (res, left.Location);
 929                                         } else if (left is UIntConstant){
 930                                                 uint res;
 931
 932                                                 if (ec.ConstantCheckState)
 933                                                         res = checked (((UIntConstant) left).Value %
 934                                                                        ((UIntConstant) right).Value);
 935                                                 else
 936                                                         res = unchecked (((UIntConstant) left).Value %
 937                                                                          ((UIntConstant) right).Value);
 938
 939                                                 return new UIntConstant (res, left.Location);
 940                                         } else if (left is IntConstant){
 941                                                 int res;
 942
 943                                                 if (ec.ConstantCheckState)
 944                                                         res = checked (((IntConstant) left).Value %
 945                                                                        ((IntConstant) right).Value);
 946                                                 else
 947                                                         res = unchecked (((IntConstant) left).Value %
 948                                                                          ((IntConstant) right).Value);
 949
 950                                                 return new IntConstant (res, left.Location);
 951                                         } else {
 952                                                 throw new Exception ( "Unexepected modulus input: " + left);
 953                                         }
 954                                 } catch (DivideByZeroException){
 955                                         Report.Error (020, loc, "Division by constant zero");
 956                                 } catch (OverflowException){
 957                                         Error_CompileTimeOverflow (loc);
 958                                 }
 959                                 break;
 960
 961                                 //
 962                                 // There is no overflow checking on left shift
 963                                 //
 964                         case Binary.Operator.LeftShift:
 965                                 IntConstant ic = right.ToInt (loc);
 966                                 if (ic == null){
 967                                         Binary.Error_OperatorCannotBeApplied (loc, "<<", lt, rt);
 968                                         return null;
 969                                 }
 970                                 int lshift_val = ic.Value;
 971
 972                                 IntConstant lic;
 973                                 if ((lic = left.ConvertToInt ()) != null)
 974                                         return new IntConstant (lic.Value << lshift_val, left.Location);
 975
 976                                 UIntConstant luic;
 977                                 if ((luic = left.ConvertToUInt ()) != null)
 978                                         return new UIntConstant (luic.Value << lshift_val, left.Location);
 979
 980                                 LongConstant llc;
 981                                 if ((llc = left.ConvertToLong ()) != null)
 982                                         return new LongConstant (llc.Value << lshift_val, left.Location);
 983
 984                                 ULongConstant lulc;
 985                                 if ((lulc = left.ConvertToULong ()) != null)
 986                                         return new ULongConstant (lulc.Value << lshift_val, left.Location);
 987
 988                                 Binary.Error_OperatorCannotBeApplied (loc, "<<", lt, rt);
 989                                 break;
 990
 991                                 //
 992                                 // There is no overflow checking on right shift
 993                                 //
 994                         case Binary.Operator.RightShift:
 995                                 IntConstant sic = right.ToInt (loc);
 996                                 if (sic == null){
 997                                         Binary.Error_OperatorCannotBeApplied (loc, ">>", lt, rt);
 998                                         return null;
 999                                 }
1000                                 int rshift_val = sic.Value;
1001
1002                                 IntConstant ric;
1003                                 if ((ric = left.ConvertToInt ()) != null)
1004                                         return new IntConstant (ric.Value >> rshift_val, left.Location);
1005
1006                                 UIntConstant ruic;
1007                                 if ((ruic = left.ConvertToUInt ()) != null)
1008                                         return new UIntConstant (ruic.Value >> rshift_val, left.Location);
1009
1010                                 LongConstant rlc;
1011                                 if ((rlc = left.ConvertToLong ()) != null)
1012                                         return new LongConstant (rlc.Value >> rshift_val, left.Location);
1013
1014                                 ULongConstant rulc;
1015                                 if ((rulc = left.ConvertToULong ()) != null)
1016                                         return new ULongConstant (rulc.Value >> rshift_val, left.Location);
1017
1018                                 Binary.Error_OperatorCannotBeApplied (loc, ">>", lt, rt);
1019                                 break;
1020
1021                         case Binary.Operator.LogicalAnd:
1022                                 if (left is BoolConstant && right is BoolConstant){
1023                                         return new BoolConstant (
1024                                                 ((BoolConstant) left).Value &&
1025                                                 ((BoolConstant) right).Value, left.Location);
1026                                 }
1027                                 break;
1028
1029                         case Binary.Operator.LogicalOr:
1030                                 if (left is BoolConstant && right is BoolConstant){
1031                                         return new BoolConstant (
1032                                                 ((BoolConstant) left).Value ||
1033                                                 ((BoolConstant) right).Value, left.Location);
1034                                 }
1035                                 break;
1036
1037                         case Binary.Operator.Equality:
1038                                 if (left is BoolConstant && right is BoolConstant){
1039                                         return new BoolConstant (
1040                                                 ((BoolConstant) left).Value ==
1041                                                 ((BoolConstant) right).Value, left.Location);
1042
1043                                 }
1044                                 if (left is NullLiteral){
1045                                         if (right is NullLiteral)
1046                                                 return new BoolConstant (true, left.Location);
1047                                         else if (right is StringConstant)
1048                                                 return new BoolConstant (
1049                                                         ((StringConstant) right).Value == null, left.Location);
1050                                 } else if (right is NullLiteral){
1051                                         if (left is NullLiteral)
1052                                                 return new BoolConstant (true, left.Location);
1053                                         else if (left is StringConstant)
1054                                                 return new BoolConstant (
1055                                                         ((StringConstant) left).Value == null, left.Location);
1056                                 }
1057                                 if (left is StringConstant && right is StringConstant){
1058                                         return new BoolConstant (
1059                                                 ((StringConstant) left).Value ==
1060                                                 ((StringConstant) right).Value, left.Location);
1061
1062                                 }
1063
1064                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
1065                                 if (left == null || right == null)
1066                                         return null;
1067
1068                                 bool_res = false;
1069                                 if (left is DoubleConstant)
1070                                         bool_res = ((DoubleConstant) left).Value ==
1071                                                 ((DoubleConstant) right).Value;
1072                                 else if (left is FloatConstant)
1073                                         bool_res = ((FloatConstant) left).Value ==
1074                                                 ((FloatConstant) right).Value;
1075                                 else if (left is ULongConstant)
1076                                         bool_res = ((ULongConstant) left).Value ==
1077                                                 ((ULongConstant) right).Value;
1078                                 else if (left is LongConstant)
1079                                         bool_res = ((LongConstant) left).Value ==
1080                                                 ((LongConstant) right).Value;
1081                                 else if (left is UIntConstant)
1082                                         bool_res = ((UIntConstant) left).Value ==
1083                                                 ((UIntConstant) right).Value;
1084                                 else if (left is IntConstant)
1085                                         bool_res = ((IntConstant) left).Value ==
1086                                                 ((IntConstant) right).Value;
1087                                 else
1088                                         return null;
1089
1090                                 return new BoolConstant (bool_res, left.Location);
1091
1092                         case Binary.Operator.Inequality:
1093                                 if (left is BoolConstant && right is BoolConstant){
1094                                         return new BoolConstant (
1095                                                 ((BoolConstant) left).Value !=
1096                                                 ((BoolConstant) right).Value, left.Location);
1097                                 }
1098                                 if (left is NullLiteral){
1099                                         if (right is NullLiteral)
1100                                                 return new BoolConstant (false, left.Location);
1101                                         else if (right is StringConstant)
1102                                                 return new BoolConstant (
1103                                                         ((StringConstant) right).Value != null, left.Location);
1104                                 } else if (right is NullLiteral){
1105                                         if (left is NullLiteral)
1106                                                 return new BoolConstant (false, left.Location);
1107                                         else if (left is StringConstant)
1108                                                 return new BoolConstant (
1109                                                         ((StringConstant) left).Value != null, left.Location);
1110                                 }
1111                                 if (left is StringConstant && right is StringConstant){
1112                                         return new BoolConstant (
1113                                                 ((StringConstant) left).Value !=
1114                                                 ((StringConstant) right).Value, left.Location);
1115
1116                                 }
1117                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
1118                                 if (left == null || right == null)
1119                                         return null;
1120
1121                                 bool_res = false;
1122                                 if (left is DoubleConstant)
1123                                         bool_res = ((DoubleConstant) left).Value !=
1124                                                 ((DoubleConstant) right).Value;
1125                                 else if (left is FloatConstant)
1126                                         bool_res = ((FloatConstant) left).Value !=
1127                                                 ((FloatConstant) right).Value;
1128                                 else if (left is ULongConstant)
1129                                         bool_res = ((ULongConstant) left).Value !=
1130                                                 ((ULongConstant) right).Value;
1131                                 else if (left is LongConstant)
1132                                         bool_res = ((LongConstant) left).Value !=
1133                                                 ((LongConstant) right).Value;
1134                                 else if (left is UIntConstant)
1135                                         bool_res = ((UIntConstant) left).Value !=
1136                                                 ((UIntConstant) right).Value;
1137                                 else if (left is IntConstant)
1138                                         bool_res = ((IntConstant) left).Value !=
1139                                                 ((IntConstant) right).Value;
1140                                 else
1141                                         return null;
1142
1143                                 return new BoolConstant (bool_res, left.Location);
1144
1145                         case Binary.Operator.LessThan:
1146                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
1147                                 if (left == null || right == null)
1148                                         return null;
1149
1150                                 bool_res = false;
1151                                 if (left is DoubleConstant)
1152                                         bool_res = ((DoubleConstant) left).Value <
1153                                                 ((DoubleConstant) right).Value;
1154                                 else if (left is FloatConstant)
1155                                         bool_res = ((FloatConstant) left).Value <
1156                                                 ((FloatConstant) right).Value;
1157                                 else if (left is ULongConstant)
1158                                         bool_res = ((ULongConstant) left).Value <
1159                                                 ((ULongConstant) right).Value;
1160                                 else if (left is LongConstant)
1161                                         bool_res = ((LongConstant) left).Value <
1162                                                 ((LongConstant) right).Value;
1163                                 else if (left is UIntConstant)
1164                                         bool_res = ((UIntConstant) left).Value <
1165                                                 ((UIntConstant) right).Value;
1166                                 else if (left is IntConstant)
1167                                         bool_res = ((IntConstant) left).Value <
1168                                                 ((IntConstant) right).Value;
1169                                 else
1170                                         return null;
1171
1172                                 return new BoolConstant (bool_res, left.Location);
1173
1174                         case Binary.Operator.GreaterThan:
1175                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
1176                                 if (left == null || right == null)
1177                                         return null;
1178
1179                                 bool_res = false;
1180                                 if (left is DoubleConstant)
1181                                         bool_res = ((DoubleConstant) left).Value >
1182                                                 ((DoubleConstant) right).Value;
1183                                 else if (left is FloatConstant)
1184                                         bool_res = ((FloatConstant) left).Value >
1185                                                 ((FloatConstant) right).Value;
1186                                 else if (left is ULongConstant)
1187                                         bool_res = ((ULongConstant) left).Value >
1188                                                 ((ULongConstant) right).Value;
1189                                 else if (left is LongConstant)
1190                                         bool_res = ((LongConstant) left).Value >
1191                                                 ((LongConstant) right).Value;
1192                                 else if (left is UIntConstant)
1193                                         bool_res = ((UIntConstant) left).Value >
1194                                                 ((UIntConstant) right).Value;
1195                                 else if (left is IntConstant)
1196                                         bool_res = ((IntConstant) left).Value >
1197                                                 ((IntConstant) right).Value;
1198                                 else
1199                                         return null;
1200
1201                                 return new BoolConstant (bool_res, left.Location);
1202
1203                         case Binary.Operator.GreaterThanOrEqual:
1204                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
1205                                 if (left == null || right == null)
1206                                         return null;
1207
1208                                 bool_res = false;
1209                                 if (left is DoubleConstant)
1210                                         bool_res = ((DoubleConstant) left).Value >=
1211                                                 ((DoubleConstant) right).Value;
1212                                 else if (left is FloatConstant)
1213                                         bool_res = ((FloatConstant) left).Value >=
1214                                                 ((FloatConstant) right).Value;
1215                                 else if (left is ULongConstant)
1216                                         bool_res = ((ULongConstant) left).Value >=
1217                                                 ((ULongConstant) right).Value;
1218                                 else if (left is LongConstant)
1219                                         bool_res = ((LongConstant) left).Value >=
1220                                                 ((LongConstant) right).Value;
1221                                 else if (left is UIntConstant)
1222                                         bool_res = ((UIntConstant) left).Value >=
1223                                                 ((UIntConstant) right).Value;
1224                                 else if (left is IntConstant)
1225                                         bool_res = ((IntConstant) left).Value >=
1226                                                 ((IntConstant) right).Value;
1227                                 else
1228                                         return null;
1229
1230                                 return new BoolConstant (bool_res, left.Location);
1231
1232                         case Binary.Operator.LessThanOrEqual:
1233                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
1234                                 if (left == null || right == null)
1235                                         return null;
1236
1237                                 bool_res = false;
1238                                 if (left is DoubleConstant)
1239                                         bool_res = ((DoubleConstant) left).Value <=
1240                                                 ((DoubleConstant) right).Value;
1241                                 else if (left is FloatConstant)
1242                                         bool_res = ((FloatConstant) left).Value <=
1243                                                 ((FloatConstant) right).Value;
1244                                 else if (left is ULongConstant)
1245                                         bool_res = ((ULongConstant) left).Value <=
1246                                                 ((ULongConstant) right).Value;
1247                                 else if (left is LongConstant)
1248                                         bool_res = ((LongConstant) left).Value <=
1249                                                 ((LongConstant) right).Value;
1250                                 else if (left is UIntConstant)
1251                                         bool_res = ((UIntConstant) left).Value <=
1252                                                 ((UIntConstant) right).Value;
1253                                 else if (left is IntConstant)
1254                                         bool_res = ((IntConstant) left).Value <=
1255                                                 ((IntConstant) right).Value;
1256                                 else
1257                                         return null;
1258
1259                                 return new BoolConstant (bool_res, left.Location);
1260                         }
1261
1262                         return null;
1263                 }
1264         }
1265 }