mcs/mcs/cfold.cs

   1 //
   2 // cfold.cs: Constant Folding
   3 //
   4 // Author:
   5 //   Miguel de Icaza (miguel@ximian.com)
   6 //
   7 // (C) 2002, 2003 Ximian, Inc.
   8 //
   9
  10 using System;
  11
  12 namespace Mono.CSharp {
  13
  14         public class ConstantFold {
  15
  16                 //
  17                 // Performs the numeric promotions on the left and right expresions
  18                 // and desposits the results on `lc' and `rc'.
  19                 //
  20                 // On success, the types of `lc' and `rc' on output will always match,
  21                 // and the pair will be one of:
  22                 //
  23                 //   (double, double)
  24                 //   (float, float)
  25                 //   (ulong, ulong)
  26                 //   (long, long)
  27                 //   (uint, uint)
  28                 //   (int, int)
  29                 //   (short, short)   (Happens with enumerations with underlying short type)
  30                 //   (ushort, ushort) (Happens with enumerations with underlying short type)
  31                 //
  32                 static void DoConstantNumericPromotions (EmitContext ec, Binary.Operator oper,
  33                                                          ref Constant left, ref Constant right,
  34                                                          Location loc)
  35                 {
  36                         if (left is DoubleConstant || right is DoubleConstant){
  37                                 //
  38                                 // If either side is a double, convert the other to a double
  39                                 //
  40                                 if (!(left is DoubleConstant))
  41                                         left = left.ToDouble (loc);
  42
  43                                 if (!(right is DoubleConstant))
  44                                         right = right.ToDouble (loc);
  45                                 return;
  46                         } else if (left is FloatConstant || right is FloatConstant) {
  47                                 //
  48                                 // If either side is a float, convert the other to a float
  49                                 //
  50                                 if (!(left is FloatConstant))
  51                                         left = left.ToFloat (loc);
  52
  53                                 if (!(right is FloatConstant))
  54                                         right = right.ToFloat (loc);
  55 ;                               return;
  56                         } else if (left is ULongConstant || right is ULongConstant){
  57                                 //
  58                                 // If either operand is of type ulong, the other operand is
  59                                 // converted to type ulong.  or an error ocurrs if the other
  60                                 // operand is of type sbyte, short, int or long
  61                                 //
  62 #if WRONG
  63                                 Constant match, other;
  64 #endif
  65
  66                                 if (left is ULongConstant){
  67 #if WRONG
  68                                         other = right;
  69                                         match = left;
  70 #endif
  71                                         if (!(right is ULongConstant))
  72                                                 right = right.ToULong (loc);
  73                                 } else {
  74 #if WRONG
  75                                         other = left;
  76                                         match = right;
  77 #endif
  78                                         left = left.ToULong (loc);
  79                                 }
  80
  81 #if WRONG
  82                                 if (other is SByteConstant || other is ShortConstant ||
  83                                     other is IntConstant || other is LongConstant){
  84                                         Binary.Error_OperatorAmbiguous
  85                                                 (loc, oper, other.Type, match.Type);
  86                                         left = null;
  87                                         right = null;
  88                                 }
  89 #endif
  90                                 return;
  91                         } else if (left is LongConstant || right is LongConstant){
  92                                 //
  93                                 // If either operand is of type long, the other operand is converted
  94                                 // to type long.
  95                                 //
  96                                 if (!(left is LongConstant))
  97                                         left = left.ToLong (loc);
  98                                 else if (!(right is LongConstant))
  99                                         right = right.ToLong (loc);
 100                                 return;
 101                         } else if (left is UIntConstant || right is UIntConstant){
 102                                 //
 103                                 // If either operand is of type uint, and the other
 104                                 // operand is of type sbyte, short or int, the operands are
 105                                 // converted to type long.
 106                                 //
 107                                 Constant other;
 108                                 if (left is UIntConstant)
 109                                         other = right;
 110                                 else
 111                                         other = left;
 112
 113                                 // Nothing to do.
 114                                 if (other is UIntConstant)
 115                                         return;
 116
 117                                 IntConstant ic = other as IntConstant;
 118                                 if (ic != null){
 119                                         if (ic.Value >= 0){
 120                                                 if (left == other)
 121                                                         left = new UIntConstant ((uint) ic.Value, ic.Location);
 122                                                 else
 123                                                         right = new UIntConstant ((uint) ic.Value, ic.Location);
 124                                                 return;
 125                                         }
 126                                 }
 127
 128                                 if (other is SByteConstant || other is ShortConstant || ic != null){
 129                                         left = left.ToLong (loc);
 130                                         right = right.ToLong (loc);
 131                                 } else {
 132                                         left = left.ToUInt (loc);
 133                                         right = left.ToUInt (loc);
 134                                 }
 135
 136                                 return;
 137                         } else if (left is DecimalConstant || right is DecimalConstant) {
 138                                 if (!(left is DecimalConstant))
 139                                         left = left.ToDecimal (loc);
 140                                 else if (!(right is DecimalConstant))
 141                                         right = right.ToDecimal (loc);
 142                                 return;
 143                         } else if (left is EnumConstant || right is EnumConstant){
 144                                 if (left is EnumConstant)
 145                                         left = ((EnumConstant) left).Child;
 146                                 if (right is EnumConstant)
 147                                         right = ((EnumConstant) right).Child;
 148
 149                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
 150                                 return;
 151
 152                         } else {
 153                                 //
 154                                 // Force conversions to int32
 155                                 //
 156                                 if (!(left is IntConstant))
 157                                         left = left.ToInt (loc);
 158                                 if (!(right is IntConstant))
 159                                         right = right.ToInt (loc);
 160                         }
 161                         return;
 162                 }
 163
 164                 static void Error_CompileTimeOverflow (Location loc)
 165                 {
 166                         Report.Error (220, loc, "The operation overflows at compile time in checked mode");
 167                 }
 168
 169                 /// <summary>
 170                 ///   Constant expression folder for binary operations.
 171                 ///
 172                 ///   Returns null if the expression can not be folded.
 173                 /// </summary>
 174                 static public Expression BinaryFold (EmitContext ec, Binary.Operator oper,
 175                                                      Constant left, Constant right, Location loc)
 176                 {
 177                         Type lt = left.Type;
 178                         Type rt = right.Type;
 179                         Type result_type = null;
 180                         bool bool_res;
 181
 182                         //
 183                         // Enumerator folding
 184                         //
 185                         if (rt == lt && left is EnumConstant)
 186                                 result_type = lt;
 187
 188                         //
 189                         // During an enum evaluation, we need to unwrap enumerations
 190                         //
 191                         if (ec.InEnumContext){
 192                                 if (left is EnumConstant)
 193                                         left = ((EnumConstant) left).Child;
 194
 195                                 if (right is EnumConstant)
 196                                         right = ((EnumConstant) right).Child;
 197                         }
 198
 199                         Type wrap_as;
 200                         Constant result = null;
 201                         switch (oper){
 202                         case Binary.Operator.BitwiseOr:
 203                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
 204                                 if (left == null || right == null)
 205                                         return null;
 206
 207                                 if (left is IntConstant){
 208                                         IntConstant v;
 209                                         int res = ((IntConstant) left).Value | ((IntConstant) right).Value;
 210
 211                                         v = new IntConstant (res, left.Location);
 212                                         if (result_type == null)
 213                                                 return v;
 214                                         else
 215                                                 return new EnumConstant (v, result_type);
 216                                 } else if (left is UIntConstant){
 217                                         UIntConstant v;
 218                                         uint res = ((UIntConstant)left).Value | ((UIntConstant)right).Value;
 219
 220                                         v = new UIntConstant (res, left.Location);
 221                                         if (result_type == null)
 222                                                 return v;
 223                                         else
 224                                                 return new EnumConstant (v, result_type);
 225                                 } else if (left is LongConstant){
 226                                         LongConstant v;
 227                                         long res = ((LongConstant)left).Value | ((LongConstant)right).Value;
 228
 229                                         v = new LongConstant (res, left.Location);
 230                                         if (result_type == null)
 231                                                 return v;
 232                                         else
 233                                                 return new EnumConstant (v, result_type);
 234                                 } else if (left is ULongConstant){
 235                                         ULongConstant v;
 236                                         ulong res = ((ULongConstant)left).Value |
 237                                                 ((ULongConstant)right).Value;
 238
 239                                         v = new ULongConstant (res, left.Location);
 240                                         if (result_type == null)
 241                                                 return v;
 242                                         else
 243                                                 return new EnumConstant (v, result_type);
 244                                 } else if (left is UShortConstant){
 245                                         UShortConstant v;
 246                                         ushort res = (ushort) (((UShortConstant)left).Value |
 247                                                                ((UShortConstant)right).Value);
 248
 249                                         v = new UShortConstant (res, left.Location);
 250                                         if (result_type == null)
 251                                                 return v;
 252                                         else
 253                                                 return new EnumConstant (v, result_type);
 254                                 } else if (left is ShortConstant){
 255                                         ShortConstant v;
 256                                         short res = (short) (((ShortConstant)left).Value |
 257                                                              ((ShortConstant)right).Value);
 258
 259                                         v = new ShortConstant (res, left.Location);
 260                                         if (result_type == null)
 261                                                 return v;
 262                                         else
 263                                                 return new EnumConstant (v, result_type);
 264                                 }
 265                                 break;
 266
 267                         case Binary.Operator.BitwiseAnd:
 268                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
 269                                 if (left == null || right == null)
 270                                         return null;
 271
 272                                 if (left is IntConstant){
 273                                         IntConstant v;
 274                                         int res = ((IntConstant) left).Value & ((IntConstant) right).Value;
 275
 276                                         v = new IntConstant (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 UIntConstant){
 282                                         UIntConstant v;
 283                                         uint res = ((UIntConstant)left).Value & ((UIntConstant)right).Value;
 284
 285                                         v = new UIntConstant (res, left.Location);
 286                                         if (result_type == null)
 287                                                 return v;
 288                                         else
 289                                                 return new EnumConstant (v, result_type);
 290                                 } else if (left is LongConstant){
 291                                         LongConstant v;
 292                                         long res = ((LongConstant)left).Value & ((LongConstant)right).Value;
 293
 294                                         v = new LongConstant (res, left.Location);
 295                                         if (result_type == null)
 296                                                 return v;
 297                                         else
 298                                                 return new EnumConstant (v, result_type);
 299                                 } else if (left is ULongConstant){
 300                                         ULongConstant v;
 301                                         ulong res = ((ULongConstant)left).Value &
 302                                                 ((ULongConstant)right).Value;
 303
 304                                         v = new ULongConstant (res, left.Location);
 305                                         if (result_type == null)
 306                                                 return v;
 307                                         else
 308                                                 return new EnumConstant (v, result_type);
 309                                 } else if (left is UShortConstant){
 310                                         UShortConstant v;
 311                                         ushort res = (ushort) (((UShortConstant)left).Value &
 312                                                                ((UShortConstant)right).Value);
 313
 314                                         v = new UShortConstant (res, left.Location);
 315                                         if (result_type == null)
 316                                                 return v;
 317                                         else
 318                                                 return new EnumConstant (v, result_type);
 319                                 } else if (left is ShortConstant){
 320                                         ShortConstant v;
 321                                         short res = (short) (((ShortConstant)left).Value &
 322                                                              ((ShortConstant)right).Value);
 323
 324                                         v = new ShortConstant (res, left.Location);
 325                                         if (result_type == null)
 326                                                 return v;
 327                                         else
 328                                                 return new EnumConstant (v, result_type);
 329                                 }
 330                                 break;
 331
 332                         case Binary.Operator.ExclusiveOr:
 333                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
 334                                 if (left == null || right == null)
 335                                         return null;
 336
 337                                 if (left is IntConstant){
 338                                         IntConstant v;
 339                                         int res = ((IntConstant) left).Value ^ ((IntConstant) right).Value;
 340
 341                                         v = new IntConstant (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 UIntConstant){
 347                                         UIntConstant v;
 348                                         uint res = ((UIntConstant)left).Value ^ ((UIntConstant)right).Value;
 349
 350                                         v = new UIntConstant (res, left.Location);
 351                                         if (result_type == null)
 352                                                 return v;
 353                                         else
 354                                                 return new EnumConstant (v, result_type);
 355                                 } else if (left is LongConstant){
 356                                         LongConstant v;
 357                                         long res = ((LongConstant)left).Value ^ ((LongConstant)right).Value;
 358
 359                                         v = new LongConstant (res, left.Location);
 360                                         if (result_type == null)
 361                                                 return v;
 362                                         else
 363                                                 return new EnumConstant (v, result_type);
 364                                 } else if (left is ULongConstant){
 365                                         ULongConstant v;
 366                                         ulong res = ((ULongConstant)left).Value ^
 367                                                 ((ULongConstant)right).Value;
 368
 369                                         v = new ULongConstant (res, left.Location);
 370                                         if (result_type == null)
 371                                                 return v;
 372                                         else
 373                                                 return new EnumConstant (v, result_type);
 374                                 } else if (left is UShortConstant){
 375                                         UShortConstant v;
 376                                         ushort res = (ushort) (((UShortConstant)left).Value ^
 377                                                                ((UShortConstant)right).Value);
 378
 379                                         v = new UShortConstant (res, left.Location);
 380                                         if (result_type == null)
 381                                                 return v;
 382                                         else
 383                                                 return new EnumConstant (v, result_type);
 384                                 } else if (left is ShortConstant){
 385                                         ShortConstant v;
 386                                         short res = (short)(((ShortConstant)left).Value ^
 387                                                             ((ShortConstant)right).Value);
 388
 389                                         v = new ShortConstant (res, left.Location);
 390                                         if (result_type == null)
 391                                                 return v;
 392                                         else
 393                                                 return new EnumConstant (v, result_type);
 394                                 }
 395                                 break;
 396
 397                         case Binary.Operator.Addition:
 398                                 bool left_is_string = left is StringConstant;
 399                                 bool right_is_string = right is StringConstant;
 400
 401                                 //
 402                                 // If both sides are strings, then concatenate, if
 403                                 // one is a string, and the other is not, then defer
 404                                 // to runtime concatenation
 405                                 //
 406                                 wrap_as = null;
 407                                 if (left_is_string || right_is_string){
 408                                         if (left_is_string && right_is_string)
 409                                                 return new StringConstant (
 410                                                         ((StringConstant) left).Value +
 411                                                         ((StringConstant) right).Value, left.Location);
 412
 413                                         return null;
 414                                 }
 415
 416                                 //
 417                                 // handle "E operator + (E x, U y)"
 418                                 // handle "E operator + (Y y, E x)"
 419                                 //
 420                                 // note that E operator + (E x, E y) is invalid
 421                                 //
 422                                 if (left is EnumConstant){
 423                                         if (right is EnumConstant){
 424                                                 return null;
 425                                         }
 426
 427                                         right = right.ToType (((EnumConstant) left).Child.Type, loc);
 428                                         if (right == null)
 429                                                 return null;
 430
 431                                         wrap_as = left.Type;
 432                                 } else if (right is EnumConstant){
 433                                         left = left.ToType (((EnumConstant) right).Child.Type, loc);
 434                                         if (left == null)
 435                                                 return null;
 436
 437                                         wrap_as = right.Type;
 438                                 }
 439
 440                                 result = null;
 441                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
 442                                 if (left == null || right == null)
 443                                         return null;
 444
 445                                 try {
 446                                         if (left is DoubleConstant){
 447                                                 double res;
 448
 449                                                 if (ec.ConstantCheckState)
 450                                                         res = checked (((DoubleConstant) left).Value +
 451                                                                        ((DoubleConstant) right).Value);
 452                                                 else
 453                                                         res = unchecked (((DoubleConstant) left).Value +
 454                                                                          ((DoubleConstant) right).Value);
 455
 456                                                 result = new DoubleConstant (res, left.Location);
 457                                         } else if (left is FloatConstant){
 458                                                 float res;
 459
 460                                                 if (ec.ConstantCheckState)
 461                                                         res = checked (((FloatConstant) left).Value +
 462                                                                        ((FloatConstant) right).Value);
 463                                                 else
 464                                                         res = unchecked (((FloatConstant) left).Value +
 465                                                                          ((FloatConstant) right).Value);
 466
 467                                                 result = new FloatConstant (res, left.Location);
 468                                         } else if (left is ULongConstant){
 469                                                 ulong res;
 470
 471                                                 if (ec.ConstantCheckState)
 472                                                         res = checked (((ULongConstant) left).Value +
 473                                                                        ((ULongConstant) right).Value);
 474                                                 else
 475                                                         res = unchecked (((ULongConstant) left).Value +
 476                                                                          ((ULongConstant) right).Value);
 477
 478                                                 result = new ULongConstant (res, left.Location);
 479                                         } else if (left is LongConstant){
 480                                                 long res;
 481
 482                                                 if (ec.ConstantCheckState)
 483                                                         res = checked (((LongConstant) left).Value +
 484                                                                        ((LongConstant) right).Value);
 485                                                 else
 486                                                         res = unchecked (((LongConstant) left).Value +
 487                                                                          ((LongConstant) right).Value);
 488
 489                                                 result = new LongConstant (res, left.Location);
 490                                         } else if (left is UIntConstant){
 491                                                 uint res;
 492
 493                                                 if (ec.ConstantCheckState)
 494                                                         res = checked (((UIntConstant) left).Value +
 495                                                                        ((UIntConstant) right).Value);
 496                                                 else
 497                                                         res = unchecked (((UIntConstant) left).Value +
 498                                                                          ((UIntConstant) right).Value);
 499
 500                                                 result = new UIntConstant (res, left.Location);
 501                                         } else if (left is IntConstant){
 502                                                 int res;
 503
 504                                                 if (ec.ConstantCheckState)
 505                                                         res = checked (((IntConstant) left).Value +
 506                                                                        ((IntConstant) right).Value);
 507                                                 else
 508                                                         res = unchecked (((IntConstant) left).Value +
 509                                                                          ((IntConstant) right).Value);
 510
 511                                                 result = new IntConstant (res, left.Location);
 512                                         } else if (left is DecimalConstant) {
 513                                                 decimal res;
 514
 515                                                 if (ec.ConstantCheckState)
 516                                                         res = checked (((DecimalConstant) left).Value +
 517                                                                 ((DecimalConstant) right).Value);
 518                                                 else
 519                                                         res = unchecked (((DecimalConstant) left).Value +
 520                                                                 ((DecimalConstant) right).Value);
 521
 522                                                 result = new DecimalConstant (res, left.Location);
 523                                         } else {
 524                                                 throw new Exception ( "Unexepected addition input: " + left);
 525                                         }
 526                                 } catch (OverflowException){
 527                                         Error_CompileTimeOverflow (loc);
 528                                 }
 529
 530                                 if (wrap_as != null)
 531                                         return result.TryReduce (ec, wrap_as, loc);
 532                                 else
 533                                         return result;
 534
 535                         case Binary.Operator.Subtraction:
 536                                 //
 537                                 // handle "E operator - (E x, U y)"
 538                                 // handle "E operator - (Y y, E x)"
 539                                 // handle "U operator - (E x, E y)"
 540                                 //
 541                                 wrap_as = null;
 542                                 if (left is EnumConstant){
 543                                         if (right is EnumConstant){
 544                                                 if (left.Type != right.Type) {
 545                                                         Binary.Error_OperatorCannotBeApplied (loc, "-", left.Type, right.Type);
 546                                                         return null;
 547                                                 }
 548
 549                                                 wrap_as = TypeManager.EnumToUnderlying (left.Type);
 550                                                 right = ((EnumConstant) right).Child.ToType (wrap_as, loc);
 551                                                 if (right == null)
 552                                                         return null;
 553
 554                                                 left = ((EnumConstant) left).Child.ToType (wrap_as, loc);
 555                                                 if (left == null)
 556                                                         return null;
 557                                         }
 558                                         else {
 559                                                 right = right.ToType (((EnumConstant) left).Child.Type, loc);
 560                                                 if (right == null)
 561                                                         return null;
 562
 563                                                 wrap_as = left.Type;
 564                                         }
 565                                 } else if (right is EnumConstant){
 566                                         left = left.ToType (((EnumConstant) right).Child.Type, loc);
 567                                         if (left == null)
 568                                                 return null;
 569
 570                                         wrap_as = right.Type;
 571                                 }
 572
 573                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
 574                                 if (left == null || right == null)
 575                                         return null;
 576
 577                                 try {
 578                                         if (left is DoubleConstant){
 579                                                 double res;
 580
 581                                                 if (ec.ConstantCheckState)
 582                                                         res = checked (((DoubleConstant) left).Value -
 583                                                                        ((DoubleConstant) right).Value);
 584                                                 else
 585                                                         res = unchecked (((DoubleConstant) left).Value -
 586                                                                          ((DoubleConstant) right).Value);
 587
 588                                                 result = new DoubleConstant (res, left.Location);
 589                                         } else if (left is FloatConstant){
 590                                                 float res;
 591
 592                                                 if (ec.ConstantCheckState)
 593                                                         res = checked (((FloatConstant) left).Value -
 594                                                                        ((FloatConstant) right).Value);
 595                                                 else
 596                                                         res = unchecked (((FloatConstant) left).Value -
 597                                                                          ((FloatConstant) right).Value);
 598
 599                                                 result = new FloatConstant (res, left.Location);
 600                                         } else if (left is ULongConstant){
 601                                                 ulong res;
 602
 603                                                 if (ec.ConstantCheckState)
 604                                                         res = checked (((ULongConstant) left).Value -
 605                                                                        ((ULongConstant) right).Value);
 606                                                 else
 607                                                         res = unchecked (((ULongConstant) left).Value -
 608                                                                          ((ULongConstant) right).Value);
 609
 610                                                 result = new ULongConstant (res, left.Location);
 611                                         } else if (left is LongConstant){
 612                                                 long res;
 613
 614                                                 if (ec.ConstantCheckState)
 615                                                         res = checked (((LongConstant) left).Value -
 616                                                                        ((LongConstant) right).Value);
 617                                                 else
 618                                                         res = unchecked (((LongConstant) left).Value -
 619                                                                          ((LongConstant) right).Value);
 620
 621                                                 result = new LongConstant (res, left.Location);
 622                                         } else if (left is UIntConstant){
 623                                                 uint res;
 624
 625                                                 if (ec.ConstantCheckState)
 626                                                         res = checked (((UIntConstant) left).Value -
 627                                                                        ((UIntConstant) right).Value);
 628                                                 else
 629                                                         res = unchecked (((UIntConstant) left).Value -
 630                                                                          ((UIntConstant) right).Value);
 631
 632                                                 result = new UIntConstant (res, left.Location);
 633                                         } else if (left is IntConstant){
 634                                                 int res;
 635
 636                                                 if (ec.ConstantCheckState)
 637                                                         res = checked (((IntConstant) left).Value -
 638                                                                        ((IntConstant) right).Value);
 639                                                 else
 640                                                         res = unchecked (((IntConstant) left).Value -
 641                                                                          ((IntConstant) right).Value);
 642
 643                                                 result = new IntConstant (res, left.Location);
 644                                         } else if (left is DecimalConstant) {
 645                                                 decimal res;
 646
 647                                                 if (ec.ConstantCheckState)
 648                                                         res = checked (((DecimalConstant) left).Value -
 649                                                                 ((DecimalConstant) right).Value);
 650                                                 else
 651                                                         res = unchecked (((DecimalConstant) left).Value -
 652                                                                 ((DecimalConstant) right).Value);
 653
 654                                                 return new DecimalConstant (res, left.Location);
 655                                         } else {
 656                                                 throw new Exception ( "Unexepected subtraction input: " + left);
 657                                         }
 658                                 } catch (OverflowException){
 659                                         Error_CompileTimeOverflow (loc);
 660                                 }
 661
 662                                 if (wrap_as != null)
 663                                         return result.TryReduce (ec, wrap_as, loc);
 664
 665                                 return result;
 666
 667                         case Binary.Operator.Multiply:
 668                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
 669                                 if (left == null || right == null)
 670                                         return null;
 671
 672                                 try {
 673                                         if (left is DoubleConstant){
 674                                                 double res;
 675
 676                                                 if (ec.ConstantCheckState)
 677                                                         res = checked (((DoubleConstant) left).Value *
 678                                                                 ((DoubleConstant) right).Value);
 679                                                 else
 680                                                         res = unchecked (((DoubleConstant) left).Value *
 681                                                                 ((DoubleConstant) right).Value);
 682
 683                                                 return new DoubleConstant (res, left.Location);
 684                                         } else if (left is FloatConstant){
 685                                                 float res;
 686
 687                                                 if (ec.ConstantCheckState)
 688                                                         res = checked (((FloatConstant) left).Value *
 689                                                                 ((FloatConstant) right).Value);
 690                                                 else
 691                                                         res = unchecked (((FloatConstant) left).Value *
 692                                                                 ((FloatConstant) right).Value);
 693
 694                                                 return new FloatConstant (res, left.Location);
 695                                         } else if (left is ULongConstant){
 696                                                 ulong res;
 697
 698                                                 if (ec.ConstantCheckState)
 699                                                         res = checked (((ULongConstant) left).Value *
 700                                                                 ((ULongConstant) right).Value);
 701                                                 else
 702                                                         res = unchecked (((ULongConstant) left).Value *
 703                                                                 ((ULongConstant) right).Value);
 704
 705                                                 return new ULongConstant (res, left.Location);
 706                                         } else if (left is LongConstant){
 707                                                 long res;
 708
 709                                                 if (ec.ConstantCheckState)
 710                                                         res = checked (((LongConstant) left).Value *
 711                                                                 ((LongConstant) right).Value);
 712                                                 else
 713                                                         res = unchecked (((LongConstant) left).Value *
 714                                                                 ((LongConstant) right).Value);
 715
 716                                                 return new LongConstant (res, left.Location);
 717                                         } else if (left is UIntConstant){
 718                                                 uint res;
 719
 720                                                 if (ec.ConstantCheckState)
 721                                                         res = checked (((UIntConstant) left).Value *
 722                                                                 ((UIntConstant) right).Value);
 723                                                 else
 724                                                         res = unchecked (((UIntConstant) left).Value *
 725                                                                 ((UIntConstant) right).Value);
 726
 727                                                 return new UIntConstant (res, left.Location);
 728                                         } else if (left is IntConstant){
 729                                                 int res;
 730
 731                                                 if (ec.ConstantCheckState)
 732                                                         res = checked (((IntConstant) left).Value *
 733                                                                 ((IntConstant) right).Value);
 734                                                 else
 735                                                         res = unchecked (((IntConstant) left).Value *
 736                                                                 ((IntConstant) right).Value);
 737
 738                                                 return new IntConstant (res, left.Location);
 739                                         } else if (left is DecimalConstant) {
 740                                                 decimal res;
 741
 742                                                 if (ec.ConstantCheckState)
 743                                                         res = checked (((DecimalConstant) left).Value *
 744                                                                 ((DecimalConstant) right).Value);
 745                                                 else
 746                                                         res = unchecked (((DecimalConstant) left).Value *
 747                                                                 ((DecimalConstant) right).Value);
 748
 749                                                 return new DecimalConstant (res, left.Location);
 750                                         } else {
 751                                                 throw new Exception ( "Unexepected multiply input: " + left);
 752                                         }
 753                                 } catch (OverflowException){
 754                                         Error_CompileTimeOverflow (loc);
 755                                 }
 756                                 break;
 757
 758                         case Binary.Operator.Division:
 759                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
 760                                 if (left == null || right == null)
 761                                         return null;
 762
 763                                 try {
 764                                         if (left is DoubleConstant){
 765                                                 double res;
 766
 767                                                 if (ec.ConstantCheckState)
 768                                                         res = checked (((DoubleConstant) left).Value /
 769                                                                 ((DoubleConstant) right).Value);
 770                                                 else
 771                                                         res = unchecked (((DoubleConstant) left).Value /
 772                                                                 ((DoubleConstant) right).Value);
 773
 774                                                 return new DoubleConstant (res, left.Location);
 775                                         } else if (left is FloatConstant){
 776                                                 float res;
 777
 778                                                 if (ec.ConstantCheckState)
 779                                                         res = checked (((FloatConstant) left).Value /
 780                                                                 ((FloatConstant) right).Value);
 781                                                 else
 782                                                         res = unchecked (((FloatConstant) left).Value /
 783                                                                 ((FloatConstant) right).Value);
 784
 785                                                 return new FloatConstant (res, left.Location);
 786                                         } else if (left is ULongConstant){
 787                                                 ulong res;
 788
 789                                                 if (ec.ConstantCheckState)
 790                                                         res = checked (((ULongConstant) left).Value /
 791                                                                 ((ULongConstant) right).Value);
 792                                                 else
 793                                                         res = unchecked (((ULongConstant) left).Value /
 794                                                                 ((ULongConstant) right).Value);
 795
 796                                                 return new ULongConstant (res, left.Location);
 797                                         } else if (left is LongConstant){
 798                                                 long res;
 799
 800                                                 if (ec.ConstantCheckState)
 801                                                         res = checked (((LongConstant) left).Value /
 802                                                                 ((LongConstant) right).Value);
 803                                                 else
 804                                                         res = unchecked (((LongConstant) left).Value /
 805                                                                 ((LongConstant) right).Value);
 806
 807                                                 return new LongConstant (res, left.Location);
 808                                         } else if (left is UIntConstant){
 809                                                 uint res;
 810
 811                                                 if (ec.ConstantCheckState)
 812                                                         res = checked (((UIntConstant) left).Value /
 813                                                                 ((UIntConstant) right).Value);
 814                                                 else
 815                                                         res = unchecked (((UIntConstant) left).Value /
 816                                                                 ((UIntConstant) right).Value);
 817
 818                                                 return new UIntConstant (res, left.Location);
 819                                         } else if (left is IntConstant){
 820                                                 int res;
 821
 822                                                 if (ec.ConstantCheckState)
 823                                                         res = checked (((IntConstant) left).Value /
 824                                                                 ((IntConstant) right).Value);
 825                                                 else
 826                                                         res = unchecked (((IntConstant) left).Value /
 827                                                                 ((IntConstant) right).Value);
 828
 829                                                 return new IntConstant (res, left.Location);
 830                                         } else if (left is DecimalConstant) {
 831                                                 decimal res;
 832
 833                                                 if (ec.ConstantCheckState)
 834                                                         res = checked (((DecimalConstant) left).Value /
 835                                                                 ((DecimalConstant) right).Value);
 836                                                 else
 837                                                         res = unchecked (((DecimalConstant) left).Value /
 838                                                                 ((DecimalConstant) right).Value);
 839
 840                                                 return new DecimalConstant (res, left.Location);
 841                                         } else {
 842                                                 throw new Exception ( "Unexepected division input: " + left);
 843                                         }
 844                                 } catch (OverflowException){
 845                                         Error_CompileTimeOverflow (loc);
 846
 847                                 } catch (DivideByZeroException) {
 848                                         Report.Error (020, loc, "Division by constant zero");
 849                                 }
 850
 851                                 break;
 852
 853                         case Binary.Operator.Modulus:
 854                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
 855                                 if (left == null || right == null)
 856                                         return null;
 857
 858                                 try {
 859                                         if (left is DoubleConstant){
 860                                                 double res;
 861
 862                                                 if (ec.ConstantCheckState)
 863                                                         res = checked (((DoubleConstant) left).Value %
 864                                                                        ((DoubleConstant) right).Value);
 865                                                 else
 866                                                         res = unchecked (((DoubleConstant) left).Value %
 867                                                                          ((DoubleConstant) right).Value);
 868
 869                                                 return new DoubleConstant (res, left.Location);
 870                                         } else if (left is FloatConstant){
 871                                                 float res;
 872
 873                                                 if (ec.ConstantCheckState)
 874                                                         res = checked (((FloatConstant) left).Value %
 875                                                                        ((FloatConstant) right).Value);
 876                                                 else
 877                                                         res = unchecked (((FloatConstant) left).Value %
 878                                                                          ((FloatConstant) right).Value);
 879
 880                                                 return new FloatConstant (res, left.Location);
 881                                         } else if (left is ULongConstant){
 882                                                 ulong res;
 883
 884                                                 if (ec.ConstantCheckState)
 885                                                         res = checked (((ULongConstant) left).Value %
 886                                                                        ((ULongConstant) right).Value);
 887                                                 else
 888                                                         res = unchecked (((ULongConstant) left).Value %
 889                                                                          ((ULongConstant) right).Value);
 890
 891                                                 return new ULongConstant (res, left.Location);
 892                                         } else if (left is LongConstant){
 893                                                 long res;
 894
 895                                                 if (ec.ConstantCheckState)
 896                                                         res = checked (((LongConstant) left).Value %
 897                                                                        ((LongConstant) right).Value);
 898                                                 else
 899                                                         res = unchecked (((LongConstant) left).Value %
 900                                                                          ((LongConstant) right).Value);
 901
 902                                                 return new LongConstant (res, left.Location);
 903                                         } else if (left is UIntConstant){
 904                                                 uint res;
 905
 906                                                 if (ec.ConstantCheckState)
 907                                                         res = checked (((UIntConstant) left).Value %
 908                                                                        ((UIntConstant) right).Value);
 909                                                 else
 910                                                         res = unchecked (((UIntConstant) left).Value %
 911                                                                          ((UIntConstant) right).Value);
 912
 913                                                 return new UIntConstant (res, left.Location);
 914                                         } else if (left is IntConstant){
 915                                                 int res;
 916
 917                                                 if (ec.ConstantCheckState)
 918                                                         res = checked (((IntConstant) left).Value %
 919                                                                        ((IntConstant) right).Value);
 920                                                 else
 921                                                         res = unchecked (((IntConstant) left).Value %
 922                                                                          ((IntConstant) right).Value);
 923
 924                                                 return new IntConstant (res, left.Location);
 925                                         } else {
 926                                                 throw new Exception ( "Unexepected modulus input: " + left);
 927                                         }
 928                                 } catch (DivideByZeroException){
 929                                         Report.Error (020, loc, "Division by constant zero");
 930                                 } catch (OverflowException){
 931                                         Error_CompileTimeOverflow (loc);
 932                                 }
 933                                 break;
 934
 935                                 //
 936                                 // There is no overflow checking on left shift
 937                                 //
 938                         case Binary.Operator.LeftShift:
 939                                 IntConstant ic = right.ToInt (loc);
 940                                 if (ic == null){
 941                                         Binary.Error_OperatorCannotBeApplied (loc, "<<", lt, rt);
 942                                         return null;
 943                                 }
 944                                 int lshift_val = ic.Value;
 945
 946                                 IntConstant lic;
 947                                 if ((lic = left.ConvertToInt ()) != null)
 948                                         return new IntConstant (lic.Value << lshift_val, left.Location);
 949
 950                                 UIntConstant luic;
 951                                 if ((luic = left.ConvertToUInt ()) != null)
 952                                         return new UIntConstant (luic.Value << lshift_val, left.Location);
 953
 954                                 LongConstant llc;
 955                                 if ((llc = left.ConvertToLong ()) != null)
 956                                         return new LongConstant (llc.Value << lshift_val, left.Location);
 957
 958                                 ULongConstant lulc;
 959                                 if ((lulc = left.ConvertToULong ()) != null)
 960                                         return new ULongConstant (lulc.Value << lshift_val, left.Location);
 961
 962                                 Binary.Error_OperatorCannotBeApplied (loc, "<<", lt, rt);
 963                                 break;
 964
 965                                 //
 966                                 // There is no overflow checking on right shift
 967                                 //
 968                         case Binary.Operator.RightShift:
 969                                 IntConstant sic = right.ToInt (loc);
 970                                 if (sic == null){
 971                                         Binary.Error_OperatorCannotBeApplied (loc, ">>", lt, rt);
 972                                         return null;
 973                                 }
 974                                 int rshift_val = sic.Value;
 975
 976                                 IntConstant ric;
 977                                 if ((ric = left.ConvertToInt ()) != null)
 978                                         return new IntConstant (ric.Value >> rshift_val, left.Location);
 979
 980                                 UIntConstant ruic;
 981                                 if ((ruic = left.ConvertToUInt ()) != null)
 982                                         return new UIntConstant (ruic.Value >> rshift_val, left.Location);
 983
 984                                 LongConstant rlc;
 985                                 if ((rlc = left.ConvertToLong ()) != null)
 986                                         return new LongConstant (rlc.Value >> rshift_val, left.Location);
 987
 988                                 ULongConstant rulc;
 989                                 if ((rulc = left.ConvertToULong ()) != null)
 990                                         return new ULongConstant (rulc.Value >> rshift_val, left.Location);
 991
 992                                 Binary.Error_OperatorCannotBeApplied (loc, ">>", lt, rt);
 993                                 break;
 994
 995                         case Binary.Operator.LogicalAnd:
 996                                 if (left is BoolConstant && right is BoolConstant){
 997                                         return new BoolConstant (
 998                                                 ((BoolConstant) left).Value &&
 999                                                 ((BoolConstant) right).Value, left.Location);
1000                                 }
1001                                 break;
1002
1003                         case Binary.Operator.LogicalOr:
1004                                 if (left is BoolConstant && right is BoolConstant){
1005                                         return new BoolConstant (
1006                                                 ((BoolConstant) left).Value ||
1007                                                 ((BoolConstant) right).Value, left.Location);
1008                                 }
1009                                 break;
1010
1011                         case Binary.Operator.Equality:
1012                                 if (left is BoolConstant && right is BoolConstant){
1013                                         return new BoolConstant (
1014                                                 ((BoolConstant) left).Value ==
1015                                                 ((BoolConstant) right).Value, left.Location);
1016
1017                                 }
1018                                 if (left is NullLiteral){
1019                                         if (right is NullLiteral)
1020                                                 return new BoolConstant (true, left.Location);
1021                                         else if (right is StringConstant)
1022                                                 return new BoolConstant (
1023                                                         ((StringConstant) right).Value == null, left.Location);
1024                                 } else if (right is NullLiteral){
1025                                         if (left is NullLiteral)
1026                                                 return new BoolConstant (true, left.Location);
1027                                         else if (left is StringConstant)
1028                                                 return new BoolConstant (
1029                                                         ((StringConstant) left).Value == null, left.Location);
1030                                 }
1031                                 if (left is StringConstant && right is StringConstant){
1032                                         return new BoolConstant (
1033                                                 ((StringConstant) left).Value ==
1034                                                 ((StringConstant) right).Value, left.Location);
1035
1036                                 }
1037
1038                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
1039                                 if (left == null || right == null)
1040                                         return null;
1041
1042                                 bool_res = false;
1043                                 if (left is DoubleConstant)
1044                                         bool_res = ((DoubleConstant) left).Value ==
1045                                                 ((DoubleConstant) right).Value;
1046                                 else if (left is FloatConstant)
1047                                         bool_res = ((FloatConstant) left).Value ==
1048                                                 ((FloatConstant) right).Value;
1049                                 else if (left is ULongConstant)
1050                                         bool_res = ((ULongConstant) left).Value ==
1051                                                 ((ULongConstant) right).Value;
1052                                 else if (left is LongConstant)
1053                                         bool_res = ((LongConstant) left).Value ==
1054                                                 ((LongConstant) right).Value;
1055                                 else if (left is UIntConstant)
1056                                         bool_res = ((UIntConstant) left).Value ==
1057                                                 ((UIntConstant) right).Value;
1058                                 else if (left is IntConstant)
1059                                         bool_res = ((IntConstant) left).Value ==
1060                                                 ((IntConstant) right).Value;
1061                                 else
1062                                         return null;
1063
1064                                 return new BoolConstant (bool_res, left.Location);
1065
1066                         case Binary.Operator.Inequality:
1067                                 if (left is BoolConstant && right is BoolConstant){
1068                                         return new BoolConstant (
1069                                                 ((BoolConstant) left).Value !=
1070                                                 ((BoolConstant) right).Value, left.Location);
1071                                 }
1072                                 if (left is NullLiteral){
1073                                         if (right is NullLiteral)
1074                                                 return new BoolConstant (false, left.Location);
1075                                         else if (right is StringConstant)
1076                                                 return new BoolConstant (
1077                                                         ((StringConstant) right).Value != null, left.Location);
1078                                 } else if (right is NullLiteral){
1079                                         if (left is NullLiteral)
1080                                                 return new BoolConstant (false, left.Location);
1081                                         else if (left is StringConstant)
1082                                                 return new BoolConstant (
1083                                                         ((StringConstant) left).Value != null, left.Location);
1084                                 }
1085                                 if (left is StringConstant && right is StringConstant){
1086                                         return new BoolConstant (
1087                                                 ((StringConstant) left).Value !=
1088                                                 ((StringConstant) right).Value, left.Location);
1089
1090                                 }
1091                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
1092                                 if (left == null || right == null)
1093                                         return null;
1094
1095                                 bool_res = false;
1096                                 if (left is DoubleConstant)
1097                                         bool_res = ((DoubleConstant) left).Value !=
1098                                                 ((DoubleConstant) right).Value;
1099                                 else if (left is FloatConstant)
1100                                         bool_res = ((FloatConstant) left).Value !=
1101                                                 ((FloatConstant) right).Value;
1102                                 else if (left is ULongConstant)
1103                                         bool_res = ((ULongConstant) left).Value !=
1104                                                 ((ULongConstant) right).Value;
1105                                 else if (left is LongConstant)
1106                                         bool_res = ((LongConstant) left).Value !=
1107                                                 ((LongConstant) right).Value;
1108                                 else if (left is UIntConstant)
1109                                         bool_res = ((UIntConstant) left).Value !=
1110                                                 ((UIntConstant) right).Value;
1111                                 else if (left is IntConstant)
1112                                         bool_res = ((IntConstant) left).Value !=
1113                                                 ((IntConstant) right).Value;
1114                                 else
1115                                         return null;
1116
1117                                 return new BoolConstant (bool_res, left.Location);
1118
1119                         case Binary.Operator.LessThan:
1120                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
1121                                 if (left == null || right == null)
1122                                         return null;
1123
1124                                 bool_res = false;
1125                                 if (left is DoubleConstant)
1126                                         bool_res = ((DoubleConstant) left).Value <
1127                                                 ((DoubleConstant) right).Value;
1128                                 else if (left is FloatConstant)
1129                                         bool_res = ((FloatConstant) left).Value <
1130                                                 ((FloatConstant) right).Value;
1131                                 else if (left is ULongConstant)
1132                                         bool_res = ((ULongConstant) left).Value <
1133                                                 ((ULongConstant) right).Value;
1134                                 else if (left is LongConstant)
1135                                         bool_res = ((LongConstant) left).Value <
1136                                                 ((LongConstant) right).Value;
1137                                 else if (left is UIntConstant)
1138                                         bool_res = ((UIntConstant) left).Value <
1139                                                 ((UIntConstant) right).Value;
1140                                 else if (left is IntConstant)
1141                                         bool_res = ((IntConstant) left).Value <
1142                                                 ((IntConstant) right).Value;
1143                                 else
1144                                         return null;
1145
1146                                 return new BoolConstant (bool_res, left.Location);
1147
1148                         case Binary.Operator.GreaterThan:
1149                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
1150                                 if (left == null || right == null)
1151                                         return null;
1152
1153                                 bool_res = false;
1154                                 if (left is DoubleConstant)
1155                                         bool_res = ((DoubleConstant) left).Value >
1156                                                 ((DoubleConstant) right).Value;
1157                                 else if (left is FloatConstant)
1158                                         bool_res = ((FloatConstant) left).Value >
1159                                                 ((FloatConstant) right).Value;
1160                                 else if (left is ULongConstant)
1161                                         bool_res = ((ULongConstant) left).Value >
1162                                                 ((ULongConstant) right).Value;
1163                                 else if (left is LongConstant)
1164                                         bool_res = ((LongConstant) left).Value >
1165                                                 ((LongConstant) right).Value;
1166                                 else if (left is UIntConstant)
1167                                         bool_res = ((UIntConstant) left).Value >
1168                                                 ((UIntConstant) right).Value;
1169                                 else if (left is IntConstant)
1170                                         bool_res = ((IntConstant) left).Value >
1171                                                 ((IntConstant) right).Value;
1172                                 else
1173                                         return null;
1174
1175                                 return new BoolConstant (bool_res, left.Location);
1176
1177                         case Binary.Operator.GreaterThanOrEqual:
1178                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
1179                                 if (left == null || right == null)
1180                                         return null;
1181
1182                                 bool_res = false;
1183                                 if (left is DoubleConstant)
1184                                         bool_res = ((DoubleConstant) left).Value >=
1185                                                 ((DoubleConstant) right).Value;
1186                                 else if (left is FloatConstant)
1187                                         bool_res = ((FloatConstant) left).Value >=
1188                                                 ((FloatConstant) right).Value;
1189                                 else if (left is ULongConstant)
1190                                         bool_res = ((ULongConstant) left).Value >=
1191                                                 ((ULongConstant) right).Value;
1192                                 else if (left is LongConstant)
1193                                         bool_res = ((LongConstant) left).Value >=
1194                                                 ((LongConstant) right).Value;
1195                                 else if (left is UIntConstant)
1196                                         bool_res = ((UIntConstant) left).Value >=
1197                                                 ((UIntConstant) right).Value;
1198                                 else if (left is IntConstant)
1199                                         bool_res = ((IntConstant) left).Value >=
1200                                                 ((IntConstant) right).Value;
1201                                 else
1202                                         return null;
1203
1204                                 return new BoolConstant (bool_res, left.Location);
1205
1206                         case Binary.Operator.LessThanOrEqual:
1207                                 DoConstantNumericPromotions (ec, oper, ref left, ref right, loc);
1208                                 if (left == null || right == null)
1209                                         return null;
1210
1211                                 bool_res = false;
1212                                 if (left is DoubleConstant)
1213                                         bool_res = ((DoubleConstant) left).Value <=
1214                                                 ((DoubleConstant) right).Value;
1215                                 else if (left is FloatConstant)
1216                                         bool_res = ((FloatConstant) left).Value <=
1217                                                 ((FloatConstant) right).Value;
1218                                 else if (left is ULongConstant)
1219                                         bool_res = ((ULongConstant) left).Value <=
1220                                                 ((ULongConstant) right).Value;
1221                                 else if (left is LongConstant)
1222                                         bool_res = ((LongConstant) left).Value <=
1223                                                 ((LongConstant) right).Value;
1224                                 else if (left is UIntConstant)
1225                                         bool_res = ((UIntConstant) left).Value <=
1226                                                 ((UIntConstant) right).Value;
1227                                 else if (left is IntConstant)
1228                                         bool_res = ((IntConstant) left).Value <=
1229                                                 ((IntConstant) right).Value;
1230                                 else
1231                                         return null;
1232
1233                                 return new BoolConstant (bool_res, left.Location);
1234                         }
1235
1236                         return null;
1237                 }
1238         }
1239 }