mcs/mcs/cfold.cs

   1 //
   2 // cfold.cs: Constant Folding
   3 //
   4 // Author:
   5 //   Miguel de Icaza (miguel@ximian.com)
   6 //   Marek Safar (marek.safar@seznam.cz)
   7 //
   8 // (C) 2002, 2003 Ximian, Inc.
   9 //
  10
  11 using System;
  12
  13 namespace Mono.CSharp {
  14
  15         public class ConstantFold {
  16
  17                 //
  18                 // Performs the numeric promotions on the left and right expresions
  19                 // and desposits the results on `lc' and `rc'.
  20                 //
  21                 // On success, the types of `lc' and `rc' on output will always match,
  22                 // and the pair will be one of:
  23                 //
  24                 //   (double, double)
  25                 //   (float, float)
  26                 //   (ulong, ulong)
  27                 //   (long, long)
  28                 //   (uint, uint)
  29                 //   (int, int)
  30                 //   (short, short)   (Happens with enumerations with underlying short type)
  31                 //   (ushort, ushort) (Happens with enumerations with underlying short type)
  32                 //
  33                 static void DoConstantNumericPromotions (EmitContext ec, Binary.Operator oper,
  34                                                          ref Constant left, ref Constant right,
  35                                                          Location loc)
  36                 {
  37                         if (left is DoubleConstant || right is DoubleConstant){
  38                                 //
  39                                 // If either side is a double, convert the other to a double
  40                                 //
  41                                 if (!(left is DoubleConstant))
  42                                         left = left.ToDouble (loc);
  43
  44                                 if (!(right is DoubleConstant))
  45                                         right = right.ToDouble (loc);
  46                                 return;
  47                         } else if (left is FloatConstant || right is FloatConstant) {
  48                                 //
  49                                 // If either side is a float, convert the other to a float
  50                                 //
  51                                 if (!(left is FloatConstant))
  52                                         left = left.ToFloat (loc);
  53
  54                                 if (!(right is FloatConstant))
  55                                         right = right.ToFloat (loc);
  56 ;                               return;
  57                         } else if (left is ULongConstant || right is ULongConstant){
  58                                 //
  59                                 // If either operand is of type ulong, the other operand is
  60                                 // converted to type ulong.  or an error ocurrs if the other
  61                                 // operand is of type sbyte, short, int or long
  62                                 //
  63 #if WRONG
  64                                 Constant match, other;
  65 #endif
  66
  67                                 if (left is ULongConstant){
  68 #if WRONG
  69                                         other = right;
  70                                         match = left;
  71 #endif
  72                                         if (!(right is ULongConstant))
  73                                                 right = right.ToULong (loc);
  74                                 } else {
  75 #if WRONG
  76                                         other = left;
  77                                         match = right;
  78 #endif
  79                                         left = left.ToULong (loc);
  80                                 }
  81
  82 #if WRONG
  83                                 if (other is SByteConstant || other is ShortConstant ||
  84                                     other is IntConstant || other is LongConstant){
  85                                         Binary.Error_OperatorAmbiguous
  86                                                 (loc, oper, other.Type, match.Type);
  87                                         left = null;
  88                                         right = null;
  89                                 }
  90 #endif
  91                                 return;
  92                         } else if (left is LongConstant || right is LongConstant){
  93                                 //
  94                                 // If either operand is of type long, the other operand is converted
  95                                 // to type long.
  96                                 //
  97                                 if (!(left is LongConstant))
  98                                         left = left.ToLong (loc);
  99                                 else if (!(right is LongConstant))
 100                                         right = right.ToLong (loc);
 101                                 return;
 102                         } else if (left is UIntConstant || right is UIntConstant){
 103                                 //
 104                                 // If either operand is of type uint, and the other
 105                                 // operand is of type sbyte, short or int, the operands are
 106                                 // converted to type long.
 107                                 //
 108                                 Constant other;
 109                                 if (left is UIntConstant)
 110                                         other = right;
 111                                 else
 112                                         other = left;
 113
 114                                 // Nothing to do.
 115                                 if (other is UIntConstant)
 116                                         return;
 117
 118                                 IntConstant ic = other as IntConstant;
 119                                 if (ic != null){
 120                                         if (ic.Value >= 0){
 121                                                 if (left == other)
 122                                                         left = new UIntConstant ((uint) ic.Value, ic.Location);
 123                                                 else
 124                                                         right = new UIntConstant ((uint) ic.Value, ic.Location);
 125                                                 return;
 126                                         }
 127                                 }
 128
 129                                 if (other is SByteConstant || other is ShortConstant || ic != null){
 130                                         left = left.ToLong (loc);
 131                                         right = right.ToLong (loc);
 132                                 } else {
 133                                         left = left.ToUInt (loc);
 134                                         right = left.ToUInt (loc);
 135                                 }
 136
 137                                 return;
 138                         } else if (left is DecimalConstant || right is DecimalConstant) {
 139                                 if (!(left is DecimalConstant))
 140                                         left = left.ToDecimal (loc);
 141                                 else if (!(right is DecimalConstant))
 142                                         right = right.ToDecimal (loc);
 143                                 return;
 144                         } else if (left is EnumConstant || right is EnumConstant){
 145                                 if (left is EnumConstant)
 146                                         left = ((EnumConstant) left).Child;
 147                                 if (right is EnumConstant)
 148                                         right = ((EnumConstant) right).Child;
 149
 150                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
 151                                 return;
 152
 153                         } else {
 154                                 //
 155                                 // Force conversions to int32
 156                                 //
 157                                 if (!(left is IntConstant))
 158                                         left = left.ToInt (loc);
 159                                 if (!(right is IntConstant))
 160                                         right = right.ToInt (loc);
 161                         }
 162                         return;
 163                 }
 164
 165                 internal static void Error_CompileTimeOverflow (Location loc)
 166                 {
 167                         Report.Error (220, loc, "The operation overflows at compile time in checked mode");
 168                 }
 169
 170                 /// <summary>
 171                 ///   Constant expression folder for binary operations.
 172                 ///
 173                 ///   Returns null if the expression can not be folded.
 174                 /// </summary>
 175                 static public Expression BinaryFold (EmitContext ec, Binary.Operator oper,
 176                                                      Constant left, Constant right, Location loc)
 177                 {
 178                         if (left is EmptyConstantCast)
 179                                 return BinaryFold (ec, oper, ((EmptyConstantCast)left).child, right, loc);
 180
 181                         if (right is EmptyConstantCast)
 182                                 return BinaryFold (ec, oper, left, ((EmptyConstantCast)right).child, loc);
 183
 184                         Type lt = left.Type;
 185                         Type rt = right.Type;
 186                         Type result_type = null;
 187                         bool bool_res;
 188
 189                         //
 190                         // Enumerator folding
 191                         //
 192                         if (rt == lt && left is EnumConstant)
 193                                 result_type = lt;
 194
 195                         //
 196                         // During an enum evaluation, we need to unwrap enumerations
 197                         //
 198                         if (ec.InEnumContext){
 199                                 if (left is EnumConstant)
 200                                         left = ((EnumConstant) left).Child;
 201
 202                                 if (right is EnumConstant)
 203                                         right = ((EnumConstant) right).Child;
 204                         }
 205
 206                         if (left is BoolConstant && right is BoolConstant) {
 207                                 bool lv = ((BoolConstant) left ).Value;
 208                                 bool rv = ((BoolConstant) right).Value;
 209                                 switch (oper) {
 210                                 case Binary.Operator.BitwiseAnd:
 211                                 case Binary.Operator.LogicalAnd:
 212                                         return new BoolConstant (lv && rv, left.Location);
 213                                 case Binary.Operator.BitwiseOr:
 214                                 case Binary.Operator.LogicalOr:
 215                                         return new BoolConstant (lv || rv, left.Location);
 216                                 case Binary.Operator.ExclusiveOr:
 217                                         return new BoolConstant (lv ^ rv, left.Location);
 218                                 case Binary.Operator.Equality:
 219                                         return new BoolConstant (lv == rv, left.Location);
 220                                 case Binary.Operator.Inequality:
 221                                         return new BoolConstant (lv != rv, left.Location);
 222                                 }
 223                                 return null;
 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);
 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);
 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                                         try {
 559                                                 return result.TryReduce (ec, wrap_as, loc);
 560                                         }
 561                                         catch (OverflowException) {
 562                                                 return null;
 563                                         }
 564                                 }
 565                                 else
 566                                         return result;
 567
 568                         case Binary.Operator.Subtraction:
 569                                 //
 570                                 // handle "E operator - (E x, U y)"
 571                                 // handle "E operator - (Y y, E x)"
 572                                 // handle "U operator - (E x, E y)"
 573                                 //
 574                                 wrap_as = null;
 575                                 if (left is EnumConstant){
 576                                         if (right is EnumConstant){
 577                                                 if (left.Type != right.Type) {
 578                                                         Binary.Error_OperatorCannotBeApplied (loc, "-", left.Type, right.Type);
 579                                                         return null;
 580                                                 }
 581
 582                                                 wrap_as = TypeManager.EnumToUnderlying (left.Type);
 583                                                 right = ((EnumConstant) right).Child.ToType (wrap_as);
 584                                                 if (right == null)
 585                                                         return null;
 586
 587                                                 left = ((EnumConstant) left).Child.ToType (wrap_as);
 588                                                 if (left == null)
 589                                                         return null;
 590                                         }
 591                                         else {
 592                                                 right = right.ToType (((EnumConstant) left).Child.Type);
 593                                                 if (right == null)
 594                                                         return null;
 595
 596                                                 wrap_as = left.Type;
 597                                         }
 598                                 } else if (right is EnumConstant){
 599                                         left = left.ToType (((EnumConstant) right).Child.Type);
 600                                         if (left == null)
 601                                                 return null;
 602
 603                                         wrap_as = right.Type;
 604                                 }
 605
 606                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
 607                                 if (left == null || right == null)
 608                                         return null;
 609
 610                                 try {
 611                                         if (left is DoubleConstant){
 612                                                 double res;
 613
 614                                                 if (ec.ConstantCheckState)
 615                                                         res = checked (((DoubleConstant) left).Value -
 616                                                                        ((DoubleConstant) right).Value);
 617                                                 else
 618                                                         res = unchecked (((DoubleConstant) left).Value -
 619                                                                          ((DoubleConstant) right).Value);
 620
 621                                                 result = new DoubleConstant (res, left.Location);
 622                                         } else if (left is FloatConstant){
 623                                                 float res;
 624
 625                                                 if (ec.ConstantCheckState)
 626                                                         res = checked (((FloatConstant) left).Value -
 627                                                                        ((FloatConstant) right).Value);
 628                                                 else
 629                                                         res = unchecked (((FloatConstant) left).Value -
 630                                                                          ((FloatConstant) right).Value);
 631
 632                                                 result = new FloatConstant (res, left.Location);
 633                                         } else if (left is ULongConstant){
 634                                                 ulong res;
 635
 636                                                 if (ec.ConstantCheckState)
 637                                                         res = checked (((ULongConstant) left).Value -
 638                                                                        ((ULongConstant) right).Value);
 639                                                 else
 640                                                         res = unchecked (((ULongConstant) left).Value -
 641                                                                          ((ULongConstant) right).Value);
 642
 643                                                 result = new ULongConstant (res, left.Location);
 644                                         } else if (left is LongConstant){
 645                                                 long res;
 646
 647                                                 if (ec.ConstantCheckState)
 648                                                         res = checked (((LongConstant) left).Value -
 649                                                                        ((LongConstant) right).Value);
 650                                                 else
 651                                                         res = unchecked (((LongConstant) left).Value -
 652                                                                          ((LongConstant) right).Value);
 653
 654                                                 result = new LongConstant (res, left.Location);
 655                                         } else if (left is UIntConstant){
 656                                                 uint res;
 657
 658                                                 if (ec.ConstantCheckState)
 659                                                         res = checked (((UIntConstant) left).Value -
 660                                                                        ((UIntConstant) right).Value);
 661                                                 else
 662                                                         res = unchecked (((UIntConstant) left).Value -
 663                                                                          ((UIntConstant) right).Value);
 664
 665                                                 result = new UIntConstant (res, left.Location);
 666                                         } else if (left is IntConstant){
 667                                                 int res;
 668
 669                                                 if (ec.ConstantCheckState)
 670                                                         res = checked (((IntConstant) left).Value -
 671                                                                        ((IntConstant) right).Value);
 672                                                 else
 673                                                         res = unchecked (((IntConstant) left).Value -
 674                                                                          ((IntConstant) right).Value);
 675
 676                                                 result = new IntConstant (res, left.Location);
 677                                         } else if (left is DecimalConstant) {
 678                                                 decimal res;
 679
 680                                                 if (ec.ConstantCheckState)
 681                                                         res = checked (((DecimalConstant) left).Value -
 682                                                                 ((DecimalConstant) right).Value);
 683                                                 else
 684                                                         res = unchecked (((DecimalConstant) left).Value -
 685                                                                 ((DecimalConstant) right).Value);
 686
 687                                                 return new DecimalConstant (res, left.Location);
 688                                         } else {
 689                                                 throw new Exception ( "Unexepected subtraction input: " + left);
 690                                         }
 691                                 } catch (OverflowException){
 692                                         Error_CompileTimeOverflow (loc);
 693                                 }
 694
 695                                 if (wrap_as != null) {
 696                                         try {
 697                                                 return result.TryReduce (ec, wrap_as, loc);
 698                                         }
 699                                         catch (OverflowException) {
 700                                                 return null;
 701                                         }
 702                                 }
 703
 704                                 return result;
 705
 706                         case Binary.Operator.Multiply:
 707                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
 708                                 if (left == null || right == null)
 709                                         return null;
 710
 711                                 try {
 712                                         if (left is DoubleConstant){
 713                                                 double res;
 714
 715                                                 if (ec.ConstantCheckState)
 716                                                         res = checked (((DoubleConstant) left).Value *
 717                                                                 ((DoubleConstant) right).Value);
 718                                                 else
 719                                                         res = unchecked (((DoubleConstant) left).Value *
 720                                                                 ((DoubleConstant) right).Value);
 721
 722                                                 return new DoubleConstant (res, left.Location);
 723                                         } else if (left is FloatConstant){
 724                                                 float res;
 725
 726                                                 if (ec.ConstantCheckState)
 727                                                         res = checked (((FloatConstant) left).Value *
 728                                                                 ((FloatConstant) right).Value);
 729                                                 else
 730                                                         res = unchecked (((FloatConstant) left).Value *
 731                                                                 ((FloatConstant) right).Value);
 732
 733                                                 return new FloatConstant (res, left.Location);
 734                                         } else if (left is ULongConstant){
 735                                                 ulong res;
 736
 737                                                 if (ec.ConstantCheckState)
 738                                                         res = checked (((ULongConstant) left).Value *
 739                                                                 ((ULongConstant) right).Value);
 740                                                 else
 741                                                         res = unchecked (((ULongConstant) left).Value *
 742                                                                 ((ULongConstant) right).Value);
 743
 744                                                 return new ULongConstant (res, left.Location);
 745                                         } else if (left is LongConstant){
 746                                                 long res;
 747
 748                                                 if (ec.ConstantCheckState)
 749                                                         res = checked (((LongConstant) left).Value *
 750                                                                 ((LongConstant) right).Value);
 751                                                 else
 752                                                         res = unchecked (((LongConstant) left).Value *
 753                                                                 ((LongConstant) right).Value);
 754
 755                                                 return new LongConstant (res, left.Location);
 756                                         } else if (left is UIntConstant){
 757                                                 uint res;
 758
 759                                                 if (ec.ConstantCheckState)
 760                                                         res = checked (((UIntConstant) left).Value *
 761                                                                 ((UIntConstant) right).Value);
 762                                                 else
 763                                                         res = unchecked (((UIntConstant) left).Value *
 764                                                                 ((UIntConstant) right).Value);
 765
 766                                                 return new UIntConstant (res, left.Location);
 767                                         } else if (left is IntConstant){
 768                                                 int res;
 769
 770                                                 if (ec.ConstantCheckState)
 771                                                         res = checked (((IntConstant) left).Value *
 772                                                                 ((IntConstant) right).Value);
 773                                                 else
 774                                                         res = unchecked (((IntConstant) left).Value *
 775                                                                 ((IntConstant) right).Value);
 776
 777                                                 return new IntConstant (res, left.Location);
 778                                         } else if (left is DecimalConstant) {
 779                                                 decimal res;
 780
 781                                                 if (ec.ConstantCheckState)
 782                                                         res = checked (((DecimalConstant) left).Value *
 783                                                                 ((DecimalConstant) right).Value);
 784                                                 else
 785                                                         res = unchecked (((DecimalConstant) left).Value *
 786                                                                 ((DecimalConstant) right).Value);
 787
 788                                                 return new DecimalConstant (res, left.Location);
 789                                         } else {
 790                                                 throw new Exception ( "Unexepected multiply input: " + left);
 791                                         }
 792                                 } catch (OverflowException){
 793                                         Error_CompileTimeOverflow (loc);
 794                                 }
 795                                 break;
 796
 797                         case Binary.Operator.Division:
 798                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
 799                                 if (left == null || right == null)
 800                                         return null;
 801
 802                                 try {
 803                                         if (left is DoubleConstant){
 804                                                 double res;
 805
 806                                                 if (ec.ConstantCheckState)
 807                                                         res = checked (((DoubleConstant) left).Value /
 808                                                                 ((DoubleConstant) right).Value);
 809                                                 else
 810                                                         res = unchecked (((DoubleConstant) left).Value /
 811                                                                 ((DoubleConstant) right).Value);
 812
 813                                                 return new DoubleConstant (res, left.Location);
 814                                         } else if (left is FloatConstant){
 815                                                 float res;
 816
 817                                                 if (ec.ConstantCheckState)
 818                                                         res = checked (((FloatConstant) left).Value /
 819                                                                 ((FloatConstant) right).Value);
 820                                                 else
 821                                                         res = unchecked (((FloatConstant) left).Value /
 822                                                                 ((FloatConstant) right).Value);
 823
 824                                                 return new FloatConstant (res, left.Location);
 825                                         } else if (left is ULongConstant){
 826                                                 ulong res;
 827
 828                                                 if (ec.ConstantCheckState)
 829                                                         res = checked (((ULongConstant) left).Value /
 830                                                                 ((ULongConstant) right).Value);
 831                                                 else
 832                                                         res = unchecked (((ULongConstant) left).Value /
 833                                                                 ((ULongConstant) right).Value);
 834
 835                                                 return new ULongConstant (res, left.Location);
 836                                         } else if (left is LongConstant){
 837                                                 long res;
 838
 839                                                 if (ec.ConstantCheckState)
 840                                                         res = checked (((LongConstant) left).Value /
 841                                                                 ((LongConstant) right).Value);
 842                                                 else
 843                                                         res = unchecked (((LongConstant) left).Value /
 844                                                                 ((LongConstant) right).Value);
 845
 846                                                 return new LongConstant (res, left.Location);
 847                                         } else if (left is UIntConstant){
 848                                                 uint res;
 849
 850                                                 if (ec.ConstantCheckState)
 851                                                         res = checked (((UIntConstant) left).Value /
 852                                                                 ((UIntConstant) right).Value);
 853                                                 else
 854                                                         res = unchecked (((UIntConstant) left).Value /
 855                                                                 ((UIntConstant) right).Value);
 856
 857                                                 return new UIntConstant (res, left.Location);
 858                                         } else if (left is IntConstant){
 859                                                 int res;
 860
 861                                                 if (ec.ConstantCheckState)
 862                                                         res = checked (((IntConstant) left).Value /
 863                                                                 ((IntConstant) right).Value);
 864                                                 else
 865                                                         res = unchecked (((IntConstant) left).Value /
 866                                                                 ((IntConstant) right).Value);
 867
 868                                                 return new IntConstant (res, left.Location);
 869                                         } else if (left is DecimalConstant) {
 870                                                 decimal res;
 871
 872                                                 if (ec.ConstantCheckState)
 873                                                         res = checked (((DecimalConstant) left).Value /
 874                                                                 ((DecimalConstant) right).Value);
 875                                                 else
 876                                                         res = unchecked (((DecimalConstant) left).Value /
 877                                                                 ((DecimalConstant) right).Value);
 878
 879                                                 return new DecimalConstant (res, left.Location);
 880                                         } else {
 881                                                 throw new Exception ( "Unexepected division input: " + left);
 882                                         }
 883                                 } catch (OverflowException){
 884                                         Error_CompileTimeOverflow (loc);
 885
 886                                 } catch (DivideByZeroException) {
 887                                         Report.Error (020, loc, "Division by constant zero");
 888                                 }
 889
 890                                 break;
 891
 892                         case Binary.Operator.Modulus:
 893                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
 894                                 if (left == null || right == null)
 895                                         return null;
 896
 897                                 try {
 898                                         if (left is DoubleConstant){
 899                                                 double res;
 900
 901                                                 if (ec.ConstantCheckState)
 902                                                         res = checked (((DoubleConstant) left).Value %
 903                                                                        ((DoubleConstant) right).Value);
 904                                                 else
 905                                                         res = unchecked (((DoubleConstant) left).Value %
 906                                                                          ((DoubleConstant) right).Value);
 907
 908                                                 return new DoubleConstant (res, left.Location);
 909                                         } else if (left is FloatConstant){
 910                                                 float res;
 911
 912                                                 if (ec.ConstantCheckState)
 913                                                         res = checked (((FloatConstant) left).Value %
 914                                                                        ((FloatConstant) right).Value);
 915                                                 else
 916                                                         res = unchecked (((FloatConstant) left).Value %
 917                                                                          ((FloatConstant) right).Value);
 918
 919                                                 return new FloatConstant (res, left.Location);
 920                                         } else if (left is ULongConstant){
 921                                                 ulong res;
 922
 923                                                 if (ec.ConstantCheckState)
 924                                                         res = checked (((ULongConstant) left).Value %
 925                                                                        ((ULongConstant) right).Value);
 926                                                 else
 927                                                         res = unchecked (((ULongConstant) left).Value %
 928                                                                          ((ULongConstant) right).Value);
 929
 930                                                 return new ULongConstant (res, left.Location);
 931                                         } else if (left is LongConstant){
 932                                                 long res;
 933
 934                                                 if (ec.ConstantCheckState)
 935                                                         res = checked (((LongConstant) left).Value %
 936                                                                        ((LongConstant) right).Value);
 937                                                 else
 938                                                         res = unchecked (((LongConstant) left).Value %
 939                                                                          ((LongConstant) right).Value);
 940
 941                                                 return new LongConstant (res, left.Location);
 942                                         } else if (left is UIntConstant){
 943                                                 uint res;
 944
 945                                                 if (ec.ConstantCheckState)
 946                                                         res = checked (((UIntConstant) left).Value %
 947                                                                        ((UIntConstant) right).Value);
 948                                                 else
 949                                                         res = unchecked (((UIntConstant) left).Value %
 950                                                                          ((UIntConstant) right).Value);
 951
 952                                                 return new UIntConstant (res, left.Location);
 953                                         } else if (left is IntConstant){
 954                                                 int res;
 955
 956                                                 if (ec.ConstantCheckState)
 957                                                         res = checked (((IntConstant) left).Value %
 958                                                                        ((IntConstant) right).Value);
 959                                                 else
 960                                                         res = unchecked (((IntConstant) left).Value %
 961                                                                          ((IntConstant) right).Value);
 962
 963                                                 return new IntConstant (res, left.Location);
 964                                         } else {
 965                                                 throw new Exception ( "Unexepected modulus input: " + left);
 966                                         }
 967                                 } catch (DivideByZeroException){
 968                                         Report.Error (020, loc, "Division by constant zero");
 969                                 } catch (OverflowException){
 970                                         Error_CompileTimeOverflow (loc);
 971                                 }
 972                                 break;
 973
 974                                 //
 975                                 // There is no overflow checking on left shift
 976                                 //
 977                         case Binary.Operator.LeftShift:
 978                                 IntConstant ic = right.ToInt (loc);
 979                                 if (ic == null){
 980                                         Binary.Error_OperatorCannotBeApplied (loc, "<<", lt, rt);
 981                                         return null;
 982                                 }
 983                                 int lshift_val = ic.Value;
 984
 985                                 IntConstant lic;
 986                                 if ((lic = left.ConvertToInt ()) != null)
 987                                         return new IntConstant (lic.Value << lshift_val, left.Location);
 988
 989                                 UIntConstant luic;
 990                                 if ((luic = left.ConvertToUInt ()) != null)
 991                                         return new UIntConstant (luic.Value << lshift_val, left.Location);
 992
 993                                 LongConstant llc;
 994                                 if ((llc = left.ConvertToLong ()) != null)
 995                                         return new LongConstant (llc.Value << lshift_val, left.Location);
 996
 997                                 ULongConstant lulc;
 998                                 if ((lulc = left.ConvertToULong ()) != null)
 999                                         return new ULongConstant (lulc.Value << lshift_val, left.Location);
1000
1001                                 Binary.Error_OperatorCannotBeApplied (loc, "<<", lt, rt);
1002                                 break;
1003
1004                                 //
1005                                 // There is no overflow checking on right shift
1006                                 //
1007                         case Binary.Operator.RightShift:
1008                                 IntConstant sic = right.ToInt (loc);
1009                                 if (sic == null){
1010                                         Binary.Error_OperatorCannotBeApplied (loc, ">>", lt, rt);
1011                                         return null;
1012                                 }
1013                                 int rshift_val = sic.Value;
1014
1015                                 IntConstant ric;
1016                                 if ((ric = left.ConvertToInt ()) != null)
1017                                         return new IntConstant (ric.Value >> rshift_val, left.Location);
1018
1019                                 UIntConstant ruic;
1020                                 if ((ruic = left.ConvertToUInt ()) != null)
1021                                         return new UIntConstant (ruic.Value >> rshift_val, left.Location);
1022
1023                                 LongConstant rlc;
1024                                 if ((rlc = left.ConvertToLong ()) != null)
1025                                         return new LongConstant (rlc.Value >> rshift_val, left.Location);
1026
1027                                 ULongConstant rulc;
1028                                 if ((rulc = left.ConvertToULong ()) != null)
1029                                         return new ULongConstant (rulc.Value >> rshift_val, left.Location);
1030
1031                                 Binary.Error_OperatorCannotBeApplied (loc, ">>", lt, rt);
1032                                 break;
1033
1034                         case Binary.Operator.Equality:
1035                                 if (left is NullConstant){
1036                                         if (right is NullConstant)
1037                                                 return new BoolConstant (true, left.Location);
1038                                         else if (right is StringConstant)
1039                                                 return new BoolConstant (
1040                                                         ((StringConstant) right).Value == null, left.Location);
1041                                 } else if (right is NullConstant){
1042                                         if (left is NullConstant)
1043                                                 return new BoolConstant (true, left.Location);
1044                                         else if (left is StringConstant)
1045                                                 return new BoolConstant (
1046                                                         ((StringConstant) left).Value == null, left.Location);
1047                                 }
1048                                 if (left is StringConstant && right is StringConstant){
1049                                         return new BoolConstant (
1050                                                 ((StringConstant) left).Value ==
1051                                                 ((StringConstant) right).Value, left.Location);
1052
1053                                 }
1054
1055                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
1056                                 if (left == null || right == null)
1057                                         return null;
1058
1059                                 bool_res = false;
1060                                 if (left is DoubleConstant)
1061                                         bool_res = ((DoubleConstant) left).Value ==
1062                                                 ((DoubleConstant) right).Value;
1063                                 else if (left is FloatConstant)
1064                                         bool_res = ((FloatConstant) left).Value ==
1065                                                 ((FloatConstant) right).Value;
1066                                 else if (left is ULongConstant)
1067                                         bool_res = ((ULongConstant) left).Value ==
1068                                                 ((ULongConstant) right).Value;
1069                                 else if (left is LongConstant)
1070                                         bool_res = ((LongConstant) left).Value ==
1071                                                 ((LongConstant) right).Value;
1072                                 else if (left is UIntConstant)
1073                                         bool_res = ((UIntConstant) left).Value ==
1074                                                 ((UIntConstant) right).Value;
1075                                 else if (left is IntConstant)
1076                                         bool_res = ((IntConstant) left).Value ==
1077                                                 ((IntConstant) right).Value;
1078                                 else
1079                                         return null;
1080
1081                                 return new BoolConstant (bool_res, left.Location);
1082
1083                         case Binary.Operator.Inequality:
1084                                 if (left is NullConstant){
1085                                         if (right is NullConstant)
1086                                                 return new BoolConstant (false, left.Location);
1087                                         else if (right is StringConstant)
1088                                                 return new BoolConstant (
1089                                                         ((StringConstant) right).Value != null, left.Location);
1090                                 } else if (right is NullConstant){
1091                                         if (left is NullConstant)
1092                                                 return new BoolConstant (false, left.Location);
1093                                         else if (left is StringConstant)
1094                                                 return new BoolConstant (
1095                                                         ((StringConstant) left).Value != null, left.Location);
1096                                 }
1097                                 if (left is StringConstant && right is StringConstant){
1098                                         return new BoolConstant (
1099                                                 ((StringConstant) left).Value !=
1100                                                 ((StringConstant) right).Value, left.Location);
1101
1102                                 }
1103                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
1104                                 if (left == null || right == null)
1105                                         return null;
1106
1107                                 bool_res = false;
1108                                 if (left is DoubleConstant)
1109                                         bool_res = ((DoubleConstant) left).Value !=
1110                                                 ((DoubleConstant) right).Value;
1111                                 else if (left is FloatConstant)
1112                                         bool_res = ((FloatConstant) left).Value !=
1113                                                 ((FloatConstant) right).Value;
1114                                 else if (left is ULongConstant)
1115                                         bool_res = ((ULongConstant) left).Value !=
1116                                                 ((ULongConstant) right).Value;
1117                                 else if (left is LongConstant)
1118                                         bool_res = ((LongConstant) left).Value !=
1119                                                 ((LongConstant) right).Value;
1120                                 else if (left is UIntConstant)
1121                                         bool_res = ((UIntConstant) left).Value !=
1122                                                 ((UIntConstant) right).Value;
1123                                 else if (left is IntConstant)
1124                                         bool_res = ((IntConstant) left).Value !=
1125                                                 ((IntConstant) right).Value;
1126                                 else
1127                                         return null;
1128
1129                                 return new BoolConstant (bool_res, left.Location);
1130
1131                         case Binary.Operator.LessThan:
1132                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
1133                                 if (left == null || right == null)
1134                                         return null;
1135
1136                                 bool_res = false;
1137                                 if (left is DoubleConstant)
1138                                         bool_res = ((DoubleConstant) left).Value <
1139                                                 ((DoubleConstant) right).Value;
1140                                 else if (left is FloatConstant)
1141                                         bool_res = ((FloatConstant) left).Value <
1142                                                 ((FloatConstant) right).Value;
1143                                 else if (left is ULongConstant)
1144                                         bool_res = ((ULongConstant) left).Value <
1145                                                 ((ULongConstant) right).Value;
1146                                 else if (left is LongConstant)
1147                                         bool_res = ((LongConstant) left).Value <
1148                                                 ((LongConstant) right).Value;
1149                                 else if (left is UIntConstant)
1150                                         bool_res = ((UIntConstant) left).Value <
1151                                                 ((UIntConstant) right).Value;
1152                                 else if (left is IntConstant)
1153                                         bool_res = ((IntConstant) left).Value <
1154                                                 ((IntConstant) right).Value;
1155                                 else
1156                                         return null;
1157
1158                                 return new BoolConstant (bool_res, left.Location);
1159
1160                         case Binary.Operator.GreaterThan:
1161                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
1162                                 if (left == null || right == null)
1163                                         return null;
1164
1165                                 bool_res = false;
1166                                 if (left is DoubleConstant)
1167                                         bool_res = ((DoubleConstant) left).Value >
1168                                                 ((DoubleConstant) right).Value;
1169                                 else if (left is FloatConstant)
1170                                         bool_res = ((FloatConstant) left).Value >
1171                                                 ((FloatConstant) right).Value;
1172                                 else if (left is ULongConstant)
1173                                         bool_res = ((ULongConstant) left).Value >
1174                                                 ((ULongConstant) right).Value;
1175                                 else if (left is LongConstant)
1176                                         bool_res = ((LongConstant) left).Value >
1177                                                 ((LongConstant) right).Value;
1178                                 else if (left is UIntConstant)
1179                                         bool_res = ((UIntConstant) left).Value >
1180                                                 ((UIntConstant) right).Value;
1181                                 else if (left is IntConstant)
1182                                         bool_res = ((IntConstant) left).Value >
1183                                                 ((IntConstant) right).Value;
1184                                 else
1185                                         return null;
1186
1187                                 return new BoolConstant (bool_res, left.Location);
1188
1189                         case Binary.Operator.GreaterThanOrEqual:
1190                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
1191                                 if (left == null || right == null)
1192                                         return null;
1193
1194                                 bool_res = false;
1195                                 if (left is DoubleConstant)
1196                                         bool_res = ((DoubleConstant) left).Value >=
1197                                                 ((DoubleConstant) right).Value;
1198                                 else if (left is FloatConstant)
1199                                         bool_res = ((FloatConstant) left).Value >=
1200                                                 ((FloatConstant) right).Value;
1201                                 else if (left is ULongConstant)
1202                                         bool_res = ((ULongConstant) left).Value >=
1203                                                 ((ULongConstant) right).Value;
1204                                 else if (left is LongConstant)
1205                                         bool_res = ((LongConstant) left).Value >=
1206                                                 ((LongConstant) right).Value;
1207                                 else if (left is UIntConstant)
1208                                         bool_res = ((UIntConstant) left).Value >=
1209                                                 ((UIntConstant) right).Value;
1210                                 else if (left is IntConstant)
1211                                         bool_res = ((IntConstant) left).Value >=
1212                                                 ((IntConstant) right).Value;
1213                                 else
1214                                         return null;
1215
1216                                 return new BoolConstant (bool_res, left.Location);
1217
1218                         case Binary.Operator.LessThanOrEqual:
1219                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
1220                                 if (left == null || right == null)
1221                                         return null;
1222
1223                                 bool_res = false;
1224                                 if (left is DoubleConstant)
1225                                         bool_res = ((DoubleConstant) left).Value <=
1226                                                 ((DoubleConstant) right).Value;
1227                                 else if (left is FloatConstant)
1228                                         bool_res = ((FloatConstant) left).Value <=
1229                                                 ((FloatConstant) right).Value;
1230                                 else if (left is ULongConstant)
1231                                         bool_res = ((ULongConstant) left).Value <=
1232                                                 ((ULongConstant) right).Value;
1233                                 else if (left is LongConstant)
1234                                         bool_res = ((LongConstant) left).Value <=
1235                                                 ((LongConstant) right).Value;
1236                                 else if (left is UIntConstant)
1237                                         bool_res = ((UIntConstant) left).Value <=
1238                                                 ((UIntConstant) right).Value;
1239                                 else if (left is IntConstant)
1240                                         bool_res = ((IntConstant) left).Value <=
1241                                                 ((IntConstant) right).Value;
1242                                 else
1243                                         return null;
1244
1245                                 return new BoolConstant (bool_res, left.Location);
1246                         }
1247
1248                         return null;
1249                 }
1250         }
1251 }