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 // Copyright 2002, 2003 Ximian, Inc.
   9 // Copyright 2003-2008, Novell, Inc.
  10 //
  11 using System;
  12
  13 namespace Mono.CSharp {
  14
  15         public class ConstantFold {
  16
  17                 static TypeSpec[] binary_promotions;
  18
  19                 public static TypeSpec[] BinaryPromotionsTypes {
  20                         get {
  21                                 if (binary_promotions == null) {
  22                                          binary_promotions = new TypeSpec[] {
  23                                                 TypeManager.decimal_type, TypeManager.double_type, TypeManager.float_type,
  24                                                 TypeManager.uint64_type, TypeManager.int64_type, TypeManager.uint32_type };
  25                                 }
  26
  27                                 return binary_promotions;
  28                         }
  29                 }
  30
  31                 public static void Reset ()
  32                 {
  33                         binary_promotions = null;
  34                 }
  35
  36                 //
  37                 // Performs the numeric promotions on the left and right expresions
  38                 // and deposits the results on `lc' and `rc'.
  39                 //
  40                 // On success, the types of `lc' and `rc' on output will always match,
  41                 // and the pair will be one of:
  42                 //
  43                 // TODO: BinaryFold should be called as an optimization step only,
  44                 // error checking here is weak
  45                 //
  46                 static bool DoBinaryNumericPromotions (ResolveContext rc, ref Constant left, ref Constant right)
  47                 {
  48                         TypeSpec ltype = left.Type;
  49                         TypeSpec rtype = right.Type;
  50
  51                         foreach (TypeSpec t in BinaryPromotionsTypes) {
  52                                 if (t == ltype)
  53                                         return t == rtype || ConvertPromotion (rc, ref right, ref left, t);
  54
  55                                 if (t == rtype)
  56                                         return t == ltype || ConvertPromotion (rc, ref left, ref right, t);
  57                         }
  58
  59                         left = left.ConvertImplicitly (rc, TypeManager.int32_type);
  60                         right = right.ConvertImplicitly (rc, TypeManager.int32_type);
  61                         return left != null && right != null;
  62                 }
  63
  64                 static bool ConvertPromotion (ResolveContext rc, ref Constant prim, ref Constant second, TypeSpec type)
  65                 {
  66                         Constant c = prim.ConvertImplicitly (rc, type);
  67                         if (c != null) {
  68                                 prim = c;
  69                                 return true;
  70                         }
  71
  72                         if (type == TypeManager.uint32_type) {
  73                                 type = TypeManager.int64_type;
  74                                 prim = prim.ConvertImplicitly (rc, type);
  75                                 second = second.ConvertImplicitly (rc, type);
  76                                 return prim != null && second != null;
  77                         }
  78
  79                         return false;
  80                 }
  81
  82                 internal static void Error_CompileTimeOverflow (ResolveContext rc, Location loc)
  83                 {
  84                         rc.Report.Error (220, loc, "The operation overflows at compile time in checked mode");
  85                 }
  86
  87                 /// <summary>
  88                 ///   Constant expression folder for binary operations.
  89                 ///
  90                 ///   Returns null if the expression can not be folded.
  91                 /// </summary>
  92                 static public Constant BinaryFold (ResolveContext ec, Binary.Operator oper,
  93                                                      Constant left, Constant right, Location loc)
  94                 {
  95                         Constant result = null;
  96
  97                         if (left is EmptyConstantCast)
  98                                 return BinaryFold (ec, oper, ((EmptyConstantCast)left).child, right, loc);
  99
 100                         if (left is SideEffectConstant) {
 101                                 result = BinaryFold (ec, oper, ((SideEffectConstant) left).value, right, loc);
 102                                 if (result == null)
 103                                         return null;
 104                                 return new SideEffectConstant (result, left, loc);
 105                         }
 106
 107                         if (right is EmptyConstantCast)
 108                                 return BinaryFold (ec, oper, left, ((EmptyConstantCast)right).child, loc);
 109
 110                         if (right is SideEffectConstant) {
 111                                 result = BinaryFold (ec, oper, left, ((SideEffectConstant) right).value, loc);
 112                                 if (result == null)
 113                                         return null;
 114                                 return new SideEffectConstant (result, right, loc);
 115                         }
 116
 117                         TypeSpec lt = left.Type;
 118                         TypeSpec rt = right.Type;
 119                         bool bool_res;
 120
 121                         if (lt == TypeManager.bool_type && lt == rt) {
 122                                 bool lv = (bool) left.GetValue ();
 123                                 bool rv = (bool) right.GetValue ();
 124                                 switch (oper) {
 125                                 case Binary.Operator.BitwiseAnd:
 126                                 case Binary.Operator.LogicalAnd:
 127                                         return new BoolConstant (lv && rv, left.Location);
 128                                 case Binary.Operator.BitwiseOr:
 129                                 case Binary.Operator.LogicalOr:
 130                                         return new BoolConstant (lv || rv, left.Location);
 131                                 case Binary.Operator.ExclusiveOr:
 132                                         return new BoolConstant (lv ^ rv, left.Location);
 133                                 case Binary.Operator.Equality:
 134                                         return new BoolConstant (lv == rv, left.Location);
 135                                 case Binary.Operator.Inequality:
 136                                         return new BoolConstant (lv != rv, left.Location);
 137                                 }
 138                                 return null;
 139                         }
 140
 141                         //
 142                         // During an enum evaluation, none of the rules are valid
 143                         // Not sure whether it is bug in csc or in documentation
 144                         //
 145                         if (ec.HasSet (ResolveContext.Options.EnumScope)){
 146                                 if (left is EnumConstant)
 147                                         left = ((EnumConstant) left).Child;
 148
 149                                 if (right is EnumConstant)
 150                                         right = ((EnumConstant) right).Child;
 151                         } else if (left is EnumConstant && rt == lt) {
 152                                 switch (oper){
 153                                         ///
 154                                         /// E operator |(E x, E y);
 155                                         /// E operator &(E x, E y);
 156                                         /// E operator ^(E x, E y);
 157                                         ///
 158                                         case Binary.Operator.BitwiseOr:
 159                                         case Binary.Operator.BitwiseAnd:
 160                                         case Binary.Operator.ExclusiveOr:
 161                                                 result = BinaryFold (ec, oper, ((EnumConstant)left).Child, ((EnumConstant)right).Child, loc);
 162                                                 if (result != null)
 163                                                         result = result.Resolve (ec).TryReduce (ec, lt, loc);
 164                                                 return result;
 165
 166                                         ///
 167                                         /// U operator -(E x, E y);
 168                                         ///
 169                                         case Binary.Operator.Subtraction:
 170                                                 result = BinaryFold (ec, oper, ((EnumConstant)left).Child, ((EnumConstant)right).Child, loc);
 171                                                 if (result != null)
 172                                                         result = result.Resolve (ec).TryReduce (ec, EnumSpec.GetUnderlyingType (lt), loc);
 173                                                 return result;
 174
 175                                         ///
 176                                         /// bool operator ==(E x, E y);
 177                                         /// bool operator !=(E x, E y);
 178                                         /// bool operator <(E x, E y);
 179                                         /// bool operator >(E x, E y);
 180                                         /// bool operator <=(E x, E y);
 181                                         /// bool operator >=(E x, E y);
 182                                         ///
 183                                         case Binary.Operator.Equality:
 184                                         case Binary.Operator.Inequality:
 185                                         case Binary.Operator.LessThan:
 186                                         case Binary.Operator.GreaterThan:
 187                                         case Binary.Operator.LessThanOrEqual:
 188                                         case Binary.Operator.GreaterThanOrEqual:
 189                                                 return BinaryFold(ec, oper, ((EnumConstant)left).Child, ((EnumConstant)right).Child, loc);
 190                                 }
 191                                 return null;
 192                         }
 193
 194                         switch (oper){
 195                         case Binary.Operator.BitwiseOr:
 196                                 //
 197                                 // bool? operator &(bool? x, bool? y);
 198                                 //
 199                                 if ((lt == TypeManager.bool_type && right is NullLiteral) ||
 200                                         (rt == TypeManager.bool_type && left is NullLiteral)) {
 201                                         var b = new Nullable.LiftedBinaryOperator (oper, left, right, loc).Resolve (ec);
 202
 203                                         // false | null => null
 204                                         // null | false => null
 205                                         if ((right is NullLiteral && left.IsDefaultValue) || (left is NullLiteral && right.IsDefaultValue))
 206                                                 return Nullable.LiftedNull.CreateFromExpression (ec, b);
 207
 208                                         // true | null => true
 209                                         // null | true => true
 210                                         return ReducedExpression.Create (new BoolConstant (true, loc).Resolve (ec), b);
 211                                 }
 212
 213                                 if (!DoBinaryNumericPromotions (ec, ref left, ref right))
 214                                         return null;
 215
 216                                 if (left is IntConstant){
 217                                         int res = ((IntConstant) left).Value | ((IntConstant) right).Value;
 218
 219                                         return new IntConstant (res, left.Location);
 220                                 }
 221                                 if (left is UIntConstant){
 222                                         uint res = ((UIntConstant)left).Value | ((UIntConstant)right).Value;
 223
 224                                         return new UIntConstant (res, left.Location);
 225                                 }
 226                                 if (left is LongConstant){
 227                                         long res = ((LongConstant)left).Value | ((LongConstant)right).Value;
 228
 229                                         return new LongConstant (res, left.Location);
 230                                 }
 231                                 if (left is ULongConstant){
 232                                         ulong res = ((ULongConstant)left).Value |
 233                                                 ((ULongConstant)right).Value;
 234
 235                                         return new ULongConstant (res, left.Location);
 236                                 }
 237                                 break;
 238
 239                         case Binary.Operator.BitwiseAnd:
 240                                 //
 241                                 // bool? operator &(bool? x, bool? y);
 242                                 //
 243                                 if ((lt == TypeManager.bool_type && right is NullLiteral) ||
 244                                         (rt == TypeManager.bool_type && left is NullLiteral)) {
 245                                         var b = new Nullable.LiftedBinaryOperator (oper, left, right, loc).Resolve (ec);
 246
 247                                         // false & null => false
 248                                         // null & false => false
 249                                         if ((right is NullLiteral && left.IsDefaultValue) || (left is NullLiteral && right.IsDefaultValue))
 250                                                 return ReducedExpression.Create (new BoolConstant (false, loc).Resolve (ec), b);
 251
 252                                         // true & null => null
 253                                         // null & true => null
 254                                         return Nullable.LiftedNull.CreateFromExpression (ec, b);
 255                                 }
 256
 257                                 if (!DoBinaryNumericPromotions (ec, ref left, ref right))
 258                                         return null;
 259
 260                                 ///
 261                                 /// int operator &(int x, int y);
 262                                 /// uint operator &(uint x, uint y);
 263                                 /// long operator &(long x, long y);
 264                                 /// ulong operator &(ulong x, ulong y);
 265                                 ///
 266                                 if (left is IntConstant){
 267                                         int res = ((IntConstant) left).Value & ((IntConstant) right).Value;
 268                                         return new IntConstant (res, left.Location);
 269                                 }
 270                                 if (left is UIntConstant){
 271                                         uint res = ((UIntConstant)left).Value & ((UIntConstant)right).Value;
 272                                         return new UIntConstant (res, left.Location);
 273                                 }
 274                                 if (left is LongConstant){
 275                                         long res = ((LongConstant)left).Value & ((LongConstant)right).Value;
 276                                         return new LongConstant (res, left.Location);
 277                                 }
 278                                 if (left is ULongConstant){
 279                                         ulong res = ((ULongConstant)left).Value &
 280                                                 ((ULongConstant)right).Value;
 281
 282                                         return new ULongConstant (res, left.Location);
 283                                 }
 284                                 break;
 285
 286                         case Binary.Operator.ExclusiveOr:
 287                                 if (!DoBinaryNumericPromotions (ec, ref left, ref right))
 288                                         return null;
 289
 290                                 if (left is IntConstant){
 291                                         int res = ((IntConstant) left).Value ^ ((IntConstant) right).Value;
 292                                         return new IntConstant (res, left.Location);
 293                                 }
 294                                 if (left is UIntConstant){
 295                                         uint res = ((UIntConstant)left).Value ^ ((UIntConstant)right).Value;
 296
 297                                         return  new UIntConstant (res, left.Location);
 298                                 }
 299                                 if (left is LongConstant){
 300                                         long res = ((LongConstant)left).Value ^ ((LongConstant)right).Value;
 301
 302                                         return new LongConstant (res, left.Location);
 303                                 }
 304                                 if (left is ULongConstant){
 305                                         ulong res = ((ULongConstant)left).Value ^
 306                                                 ((ULongConstant)right).Value;
 307
 308                                         return new ULongConstant (res, left.Location);
 309                                 }
 310                                 break;
 311
 312                         case Binary.Operator.Addition:
 313                                 if (lt == InternalType.Null)
 314                                         return right;
 315
 316                                 if (rt == InternalType.Null)
 317                                         return left;
 318
 319                                 //
 320                                 // If both sides are strings, then concatenate, if
 321                                 // one is a string, and the other is not, then defer
 322                                 // to runtime concatenation
 323                                 //
 324                                 if (lt == TypeManager.string_type || rt == TypeManager.string_type){
 325                                         if (lt == rt)
 326                                                 return new StringConstant ((string)left.GetValue () + (string)right.GetValue (),
 327                                                         left.Location);
 328
 329                                         return null;
 330                                 }
 331
 332                                 //
 333                                 // handle "E operator + (E x, U y)"
 334                                 // handle "E operator + (Y y, E x)"
 335                                 //
 336                                 EnumConstant lc = left as EnumConstant;
 337                                 EnumConstant rc = right as EnumConstant;
 338                                 if (lc != null || rc != null){
 339                                         if (lc == null) {
 340                                                 lc = rc;
 341                                                 lt = lc.Type;
 342                                                 right = left;
 343                                         }
 344
 345                                         // U has to be implicitly convetible to E.base
 346                                         right = right.ConvertImplicitly (ec, lc.Child.Type);
 347                                         if (right == null)
 348                                                 return null;
 349
 350                                         result = BinaryFold (ec, oper, lc.Child, right, loc);
 351                                         if (result == null)
 352                                                 return null;
 353
 354                                         result = result.Resolve (ec).TryReduce (ec, lt, loc);
 355                                         if (result == null)
 356                                                 return null;
 357
 358                                         return new EnumConstant (result, lt);
 359                                 }
 360
 361                                 if (!DoBinaryNumericPromotions (ec, ref left, ref right))
 362                                         return null;
 363
 364                                 try {
 365                                         if (left is DoubleConstant){
 366                                                 double res;
 367
 368                                                 if (ec.ConstantCheckState)
 369                                                         res = checked (((DoubleConstant) left).Value +
 370                                                                        ((DoubleConstant) right).Value);
 371                                                 else
 372                                                         res = unchecked (((DoubleConstant) left).Value +
 373                                                                          ((DoubleConstant) right).Value);
 374
 375                                                 return new DoubleConstant (res, left.Location);
 376                                         }
 377                                         if (left is FloatConstant){
 378                                                 float res;
 379
 380                                                 if (ec.ConstantCheckState)
 381                                                         res = checked (((FloatConstant) left).Value +
 382                                                                        ((FloatConstant) right).Value);
 383                                                 else
 384                                                         res = unchecked (((FloatConstant) left).Value +
 385                                                                          ((FloatConstant) right).Value);
 386
 387                                                 result = new FloatConstant (res, left.Location);
 388                                         } else if (left is ULongConstant){
 389                                                 ulong res;
 390
 391                                                 if (ec.ConstantCheckState)
 392                                                         res = checked (((ULongConstant) left).Value +
 393                                                                        ((ULongConstant) right).Value);
 394                                                 else
 395                                                         res = unchecked (((ULongConstant) left).Value +
 396                                                                          ((ULongConstant) right).Value);
 397
 398                                                 result = new ULongConstant (res, left.Location);
 399                                         } else if (left is LongConstant){
 400                                                 long res;
 401
 402                                                 if (ec.ConstantCheckState)
 403                                                         res = checked (((LongConstant) left).Value +
 404                                                                        ((LongConstant) right).Value);
 405                                                 else
 406                                                         res = unchecked (((LongConstant) left).Value +
 407                                                                          ((LongConstant) right).Value);
 408
 409                                                 result = new LongConstant (res, left.Location);
 410                                         } else if (left is UIntConstant){
 411                                                 uint res;
 412
 413                                                 if (ec.ConstantCheckState)
 414                                                         res = checked (((UIntConstant) left).Value +
 415                                                                        ((UIntConstant) right).Value);
 416                                                 else
 417                                                         res = unchecked (((UIntConstant) left).Value +
 418                                                                          ((UIntConstant) right).Value);
 419
 420                                                 result = new UIntConstant (res, left.Location);
 421                                         } else if (left is IntConstant){
 422                                                 int res;
 423
 424                                                 if (ec.ConstantCheckState)
 425                                                         res = checked (((IntConstant) left).Value +
 426                                                                        ((IntConstant) right).Value);
 427                                                 else
 428                                                         res = unchecked (((IntConstant) left).Value +
 429                                                                          ((IntConstant) right).Value);
 430
 431                                                 result = new IntConstant (res, left.Location);
 432                                         } else if (left is DecimalConstant) {
 433                                                 decimal res;
 434
 435                                                 if (ec.ConstantCheckState)
 436                                                         res = checked (((DecimalConstant) left).Value +
 437                                                                 ((DecimalConstant) right).Value);
 438                                                 else
 439                                                         res = unchecked (((DecimalConstant) left).Value +
 440                                                                 ((DecimalConstant) right).Value);
 441
 442                                                 result = new DecimalConstant (res, left.Location);
 443                                         }
 444                                 } catch (OverflowException){
 445                                         Error_CompileTimeOverflow (ec, loc);
 446                                 }
 447
 448                                 return result;
 449
 450                         case Binary.Operator.Subtraction:
 451                                 //
 452                                 // handle "E operator - (E x, U y)"
 453                                 // handle "E operator - (Y y, E x)"
 454                                 //
 455                                 lc = left as EnumConstant;
 456                                 rc = right as EnumConstant;
 457                                 if (lc != null || rc != null){
 458                                         if (lc == null) {
 459                                                 lc = rc;
 460                                                 lt = lc.Type;
 461                                                 right = left;
 462                                         }
 463
 464                                         // U has to be implicitly convetible to E.base
 465                                         right = right.ConvertImplicitly (ec, lc.Child.Type);
 466                                         if (right == null)
 467                                                 return null;
 468
 469                                         result = BinaryFold (ec, oper, lc.Child, right, loc);
 470                                         if (result == null)
 471                                                 return null;
 472
 473                                         result = result.Resolve (ec).TryReduce (ec, lt, loc);
 474                                         if (result == null)
 475                                                 return null;
 476
 477                                         return new EnumConstant (result, lt);
 478                                 }
 479
 480                                 if (left is NullLiteral && right is NullLiteral) {
 481                                         var lifted_int = new Nullable.NullableType (TypeManager.int32_type, loc).ResolveAsTypeTerminal (ec, false);
 482                                         return (Constant) new Nullable.LiftedBinaryOperator (oper, lifted_int, right, loc).Resolve (ec);
 483                                 }
 484
 485                                 if (!DoBinaryNumericPromotions (ec, ref left, ref right))
 486                                         return null;
 487
 488                                 try {
 489                                         if (left is DoubleConstant){
 490                                                 double res;
 491
 492                                                 if (ec.ConstantCheckState)
 493                                                         res = checked (((DoubleConstant) left).Value -
 494                                                                        ((DoubleConstant) right).Value);
 495                                                 else
 496                                                         res = unchecked (((DoubleConstant) left).Value -
 497                                                                          ((DoubleConstant) right).Value);
 498
 499                                                 result = new DoubleConstant (res, left.Location);
 500                                         } else if (left is FloatConstant){
 501                                                 float res;
 502
 503                                                 if (ec.ConstantCheckState)
 504                                                         res = checked (((FloatConstant) left).Value -
 505                                                                        ((FloatConstant) right).Value);
 506                                                 else
 507                                                         res = unchecked (((FloatConstant) left).Value -
 508                                                                          ((FloatConstant) right).Value);
 509
 510                                                 result = new FloatConstant (res, left.Location);
 511                                         } else if (left is ULongConstant){
 512                                                 ulong res;
 513
 514                                                 if (ec.ConstantCheckState)
 515                                                         res = checked (((ULongConstant) left).Value -
 516                                                                        ((ULongConstant) right).Value);
 517                                                 else
 518                                                         res = unchecked (((ULongConstant) left).Value -
 519                                                                          ((ULongConstant) right).Value);
 520
 521                                                 result = new ULongConstant (res, left.Location);
 522                                         } else if (left is LongConstant){
 523                                                 long res;
 524
 525                                                 if (ec.ConstantCheckState)
 526                                                         res = checked (((LongConstant) left).Value -
 527                                                                        ((LongConstant) right).Value);
 528                                                 else
 529                                                         res = unchecked (((LongConstant) left).Value -
 530                                                                          ((LongConstant) right).Value);
 531
 532                                                 result = new LongConstant (res, left.Location);
 533                                         } else if (left is UIntConstant){
 534                                                 uint res;
 535
 536                                                 if (ec.ConstantCheckState)
 537                                                         res = checked (((UIntConstant) left).Value -
 538                                                                        ((UIntConstant) right).Value);
 539                                                 else
 540                                                         res = unchecked (((UIntConstant) left).Value -
 541                                                                          ((UIntConstant) right).Value);
 542
 543                                                 result = new UIntConstant (res, left.Location);
 544                                         } else if (left is IntConstant){
 545                                                 int res;
 546
 547                                                 if (ec.ConstantCheckState)
 548                                                         res = checked (((IntConstant) left).Value -
 549                                                                        ((IntConstant) right).Value);
 550                                                 else
 551                                                         res = unchecked (((IntConstant) left).Value -
 552                                                                          ((IntConstant) right).Value);
 553
 554                                                 result = new IntConstant (res, left.Location);
 555                                         } else if (left is DecimalConstant) {
 556                                                 decimal res;
 557
 558                                                 if (ec.ConstantCheckState)
 559                                                         res = checked (((DecimalConstant) left).Value -
 560                                                                 ((DecimalConstant) right).Value);
 561                                                 else
 562                                                         res = unchecked (((DecimalConstant) left).Value -
 563                                                                 ((DecimalConstant) right).Value);
 564
 565                                                 return new DecimalConstant (res, left.Location);
 566                                         } else {
 567                                                 throw new Exception ( "Unexepected subtraction input: " + left);
 568                                         }
 569                                 } catch (OverflowException){
 570                                         Error_CompileTimeOverflow (ec, loc);
 571                                 }
 572
 573                                 return result;
 574
 575                         case Binary.Operator.Multiply:
 576                                 if (left is NullLiteral && right is NullLiteral) {
 577                                         var lifted_int = new Nullable.NullableType (TypeManager.int32_type, loc).ResolveAsTypeTerminal (ec, false);
 578                                         return (Constant) new Nullable.LiftedBinaryOperator (oper, lifted_int, right, loc).Resolve (ec);
 579                                 }
 580
 581                                 if (!DoBinaryNumericPromotions (ec, ref left, ref right))
 582                                         return null;
 583
 584                                 try {
 585                                         if (left is DoubleConstant){
 586                                                 double res;
 587
 588                                                 if (ec.ConstantCheckState)
 589                                                         res = checked (((DoubleConstant) left).Value *
 590                                                                 ((DoubleConstant) right).Value);
 591                                                 else
 592                                                         res = unchecked (((DoubleConstant) left).Value *
 593                                                                 ((DoubleConstant) right).Value);
 594
 595                                                 return new DoubleConstant (res, left.Location);
 596                                         } else if (left is FloatConstant){
 597                                                 float res;
 598
 599                                                 if (ec.ConstantCheckState)
 600                                                         res = checked (((FloatConstant) left).Value *
 601                                                                 ((FloatConstant) right).Value);
 602                                                 else
 603                                                         res = unchecked (((FloatConstant) left).Value *
 604                                                                 ((FloatConstant) right).Value);
 605
 606                                                 return new FloatConstant (res, left.Location);
 607                                         } else if (left is ULongConstant){
 608                                                 ulong res;
 609
 610                                                 if (ec.ConstantCheckState)
 611                                                         res = checked (((ULongConstant) left).Value *
 612                                                                 ((ULongConstant) right).Value);
 613                                                 else
 614                                                         res = unchecked (((ULongConstant) left).Value *
 615                                                                 ((ULongConstant) right).Value);
 616
 617                                                 return new ULongConstant (res, left.Location);
 618                                         } else if (left is LongConstant){
 619                                                 long res;
 620
 621                                                 if (ec.ConstantCheckState)
 622                                                         res = checked (((LongConstant) left).Value *
 623                                                                 ((LongConstant) right).Value);
 624                                                 else
 625                                                         res = unchecked (((LongConstant) left).Value *
 626                                                                 ((LongConstant) right).Value);
 627
 628                                                 return new LongConstant (res, left.Location);
 629                                         } else if (left is UIntConstant){
 630                                                 uint res;
 631
 632                                                 if (ec.ConstantCheckState)
 633                                                         res = checked (((UIntConstant) left).Value *
 634                                                                 ((UIntConstant) right).Value);
 635                                                 else
 636                                                         res = unchecked (((UIntConstant) left).Value *
 637                                                                 ((UIntConstant) right).Value);
 638
 639                                                 return new UIntConstant (res, left.Location);
 640                                         } else if (left is IntConstant){
 641                                                 int res;
 642
 643                                                 if (ec.ConstantCheckState)
 644                                                         res = checked (((IntConstant) left).Value *
 645                                                                 ((IntConstant) right).Value);
 646                                                 else
 647                                                         res = unchecked (((IntConstant) left).Value *
 648                                                                 ((IntConstant) right).Value);
 649
 650                                                 return new IntConstant (res, left.Location);
 651                                         } else if (left is DecimalConstant) {
 652                                                 decimal res;
 653
 654                                                 if (ec.ConstantCheckState)
 655                                                         res = checked (((DecimalConstant) left).Value *
 656                                                                 ((DecimalConstant) right).Value);
 657                                                 else
 658                                                         res = unchecked (((DecimalConstant) left).Value *
 659                                                                 ((DecimalConstant) right).Value);
 660
 661                                                 return new DecimalConstant (res, left.Location);
 662                                         } else {
 663                                                 throw new Exception ( "Unexepected multiply input: " + left);
 664                                         }
 665                                 } catch (OverflowException){
 666                                         Error_CompileTimeOverflow (ec, loc);
 667                                 }
 668                                 break;
 669
 670                         case Binary.Operator.Division:
 671                                 if (left is NullLiteral && right is NullLiteral) {
 672                                         var lifted_int = new Nullable.NullableType (TypeManager.int32_type, loc).ResolveAsTypeTerminal (ec, false);
 673                                         return (Constant) new Nullable.LiftedBinaryOperator (oper, lifted_int, right, loc).Resolve (ec);
 674                                 }
 675
 676                                 if (!DoBinaryNumericPromotions (ec, ref left, ref right))
 677                                         return null;
 678
 679                                 try {
 680                                         if (left is DoubleConstant){
 681                                                 double res;
 682
 683                                                 if (ec.ConstantCheckState)
 684                                                         res = checked (((DoubleConstant) left).Value /
 685                                                                 ((DoubleConstant) right).Value);
 686                                                 else
 687                                                         res = unchecked (((DoubleConstant) left).Value /
 688                                                                 ((DoubleConstant) right).Value);
 689
 690                                                 return new DoubleConstant (res, left.Location);
 691                                         } else if (left is FloatConstant){
 692                                                 float res;
 693
 694                                                 if (ec.ConstantCheckState)
 695                                                         res = checked (((FloatConstant) left).Value /
 696                                                                 ((FloatConstant) right).Value);
 697                                                 else
 698                                                         res = unchecked (((FloatConstant) left).Value /
 699                                                                 ((FloatConstant) right).Value);
 700
 701                                                 return new FloatConstant (res, left.Location);
 702                                         } else if (left is ULongConstant){
 703                                                 ulong res;
 704
 705                                                 if (ec.ConstantCheckState)
 706                                                         res = checked (((ULongConstant) left).Value /
 707                                                                 ((ULongConstant) right).Value);
 708                                                 else
 709                                                         res = unchecked (((ULongConstant) left).Value /
 710                                                                 ((ULongConstant) right).Value);
 711
 712                                                 return new ULongConstant (res, left.Location);
 713                                         } else if (left is LongConstant){
 714                                                 long res;
 715
 716                                                 if (ec.ConstantCheckState)
 717                                                         res = checked (((LongConstant) left).Value /
 718                                                                 ((LongConstant) right).Value);
 719                                                 else
 720                                                         res = unchecked (((LongConstant) left).Value /
 721                                                                 ((LongConstant) right).Value);
 722
 723                                                 return new LongConstant (res, left.Location);
 724                                         } else if (left is UIntConstant){
 725                                                 uint res;
 726
 727                                                 if (ec.ConstantCheckState)
 728                                                         res = checked (((UIntConstant) left).Value /
 729                                                                 ((UIntConstant) right).Value);
 730                                                 else
 731                                                         res = unchecked (((UIntConstant) left).Value /
 732                                                                 ((UIntConstant) right).Value);
 733
 734                                                 return new UIntConstant (res, left.Location);
 735                                         } else if (left is IntConstant){
 736                                                 int res;
 737
 738                                                 if (ec.ConstantCheckState)
 739                                                         res = checked (((IntConstant) left).Value /
 740                                                                 ((IntConstant) right).Value);
 741                                                 else
 742                                                         res = unchecked (((IntConstant) left).Value /
 743                                                                 ((IntConstant) right).Value);
 744
 745                                                 return new IntConstant (res, left.Location);
 746                                         } else if (left is DecimalConstant) {
 747                                                 decimal res;
 748
 749                                                 if (ec.ConstantCheckState)
 750                                                         res = checked (((DecimalConstant) left).Value /
 751                                                                 ((DecimalConstant) right).Value);
 752                                                 else
 753                                                         res = unchecked (((DecimalConstant) left).Value /
 754                                                                 ((DecimalConstant) right).Value);
 755
 756                                                 return new DecimalConstant (res, left.Location);
 757                                         } else {
 758                                                 throw new Exception ( "Unexepected division input: " + left);
 759                                         }
 760                                 } catch (OverflowException){
 761                                         Error_CompileTimeOverflow (ec, loc);
 762
 763                                 } catch (DivideByZeroException) {
 764                                         ec.Report.Error (20, loc, "Division by constant zero");
 765                                 }
 766
 767                                 break;
 768
 769                         case Binary.Operator.Modulus:
 770                                 if (left is NullLiteral && right is NullLiteral) {
 771                                         var lifted_int = new Nullable.NullableType (TypeManager.int32_type, loc).ResolveAsTypeTerminal (ec, false);
 772                                         return (Constant) new Nullable.LiftedBinaryOperator (oper, lifted_int, right, loc).Resolve (ec);
 773                                 }
 774
 775                                 if (!DoBinaryNumericPromotions (ec, ref left, ref right))
 776                                         return null;
 777
 778                                 try {
 779                                         if (left is DoubleConstant){
 780                                                 double res;
 781
 782                                                 if (ec.ConstantCheckState)
 783                                                         res = checked (((DoubleConstant) left).Value %
 784                                                                        ((DoubleConstant) right).Value);
 785                                                 else
 786                                                         res = unchecked (((DoubleConstant) left).Value %
 787                                                                          ((DoubleConstant) right).Value);
 788
 789                                                 return new DoubleConstant (res, left.Location);
 790                                         } else if (left is FloatConstant){
 791                                                 float res;
 792
 793                                                 if (ec.ConstantCheckState)
 794                                                         res = checked (((FloatConstant) left).Value %
 795                                                                        ((FloatConstant) right).Value);
 796                                                 else
 797                                                         res = unchecked (((FloatConstant) left).Value %
 798                                                                          ((FloatConstant) right).Value);
 799
 800                                                 return new FloatConstant (res, left.Location);
 801                                         } else if (left is ULongConstant){
 802                                                 ulong res;
 803
 804                                                 if (ec.ConstantCheckState)
 805                                                         res = checked (((ULongConstant) left).Value %
 806                                                                        ((ULongConstant) right).Value);
 807                                                 else
 808                                                         res = unchecked (((ULongConstant) left).Value %
 809                                                                          ((ULongConstant) right).Value);
 810
 811                                                 return new ULongConstant (res, left.Location);
 812                                         } else if (left is LongConstant){
 813                                                 long res;
 814
 815                                                 if (ec.ConstantCheckState)
 816                                                         res = checked (((LongConstant) left).Value %
 817                                                                        ((LongConstant) right).Value);
 818                                                 else
 819                                                         res = unchecked (((LongConstant) left).Value %
 820                                                                          ((LongConstant) right).Value);
 821
 822                                                 return new LongConstant (res, left.Location);
 823                                         } else if (left is UIntConstant){
 824                                                 uint res;
 825
 826                                                 if (ec.ConstantCheckState)
 827                                                         res = checked (((UIntConstant) left).Value %
 828                                                                        ((UIntConstant) right).Value);
 829                                                 else
 830                                                         res = unchecked (((UIntConstant) left).Value %
 831                                                                          ((UIntConstant) right).Value);
 832
 833                                                 return new UIntConstant (res, left.Location);
 834                                         } else if (left is IntConstant){
 835                                                 int res;
 836
 837                                                 if (ec.ConstantCheckState)
 838                                                         res = checked (((IntConstant) left).Value %
 839                                                                        ((IntConstant) right).Value);
 840                                                 else
 841                                                         res = unchecked (((IntConstant) left).Value %
 842                                                                          ((IntConstant) right).Value);
 843
 844                                                 return new IntConstant (res, left.Location);
 845                                         } else {
 846                                                 throw new Exception ( "Unexepected modulus input: " + left);
 847                                         }
 848                                 } catch (DivideByZeroException){
 849                                         ec.Report.Error (20, loc, "Division by constant zero");
 850                                 } catch (OverflowException){
 851                                         Error_CompileTimeOverflow (ec, loc);
 852                                 }
 853                                 break;
 854
 855                                 //
 856                                 // There is no overflow checking on left shift
 857                                 //
 858                         case Binary.Operator.LeftShift:
 859                                 if (left is NullLiteral && right is NullLiteral) {
 860                                         var lifted_int = new Nullable.NullableType (TypeManager.int32_type, loc).ResolveAsTypeTerminal (ec, false);
 861                                         return (Constant) new Nullable.LiftedBinaryOperator (oper, lifted_int, right, loc).Resolve (ec);
 862                                 }
 863
 864                                 IntConstant ic = right.ConvertImplicitly (ec, TypeManager.int32_type) as IntConstant;
 865                                 if (ic == null){
 866                                         Binary.Error_OperatorCannotBeApplied (ec, left, right, oper, loc);
 867                                         return null;
 868                                 }
 869
 870                                 int lshift_val = ic.Value;
 871                                 if (left.Type == TypeManager.uint64_type)
 872                                         return new ULongConstant (((ULongConstant)left).Value << lshift_val, left.Location);
 873                                 if (left.Type == TypeManager.int64_type)
 874                                         return new LongConstant (((LongConstant)left).Value << lshift_val, left.Location);
 875                                 if (left.Type == TypeManager.uint32_type)
 876                                         return new UIntConstant (((UIntConstant)left).Value << lshift_val, left.Location);
 877
 878                                 // null << value => null
 879                                 if (left is NullLiteral)
 880                                         return (Constant) new Nullable.LiftedBinaryOperator (oper, left, right, loc).Resolve (ec);
 881
 882                                 left = left.ConvertImplicitly (ec, TypeManager.int32_type);
 883                                 if (left.Type == TypeManager.int32_type)
 884                                         return new IntConstant (((IntConstant)left).Value << lshift_val, left.Location);
 885
 886                                 Binary.Error_OperatorCannotBeApplied (ec, left, right, oper, loc);
 887                                 break;
 888
 889                                 //
 890                                 // There is no overflow checking on right shift
 891                                 //
 892                         case Binary.Operator.RightShift:
 893                                 if (left is NullLiteral && right is NullLiteral) {
 894                                         var lifted_int = new Nullable.NullableType (TypeManager.int32_type, loc).ResolveAsTypeTerminal (ec, false);
 895                                         return (Constant) new Nullable.LiftedBinaryOperator (oper, lifted_int, right, loc).Resolve (ec);
 896                                 }
 897
 898                                 IntConstant sic = right.ConvertImplicitly (ec, TypeManager.int32_type) as IntConstant;
 899                                 if (sic == null){
 900                                         Binary.Error_OperatorCannotBeApplied (ec, left, right, oper, loc); ;
 901                                         return null;
 902                                 }
 903                                 int rshift_val = sic.Value;
 904                                 if (left.Type == TypeManager.uint64_type)
 905                                         return new ULongConstant (((ULongConstant)left).Value >> rshift_val, left.Location);
 906                                 if (left.Type == TypeManager.int64_type)
 907                                         return new LongConstant (((LongConstant)left).Value >> rshift_val, left.Location);
 908                                 if (left.Type == TypeManager.uint32_type)
 909                                         return new UIntConstant (((UIntConstant)left).Value >> rshift_val, left.Location);
 910
 911                                 // null >> value => null
 912                                 if (left is NullLiteral)
 913                                         return (Constant) new Nullable.LiftedBinaryOperator (oper, left, right, loc).Resolve (ec);
 914
 915                                 left = left.ConvertImplicitly (ec, TypeManager.int32_type);
 916                                 if (left.Type == TypeManager.int32_type)
 917                                         return new IntConstant (((IntConstant)left).Value >> rshift_val, left.Location);
 918
 919                                 Binary.Error_OperatorCannotBeApplied (ec, left, right, oper, loc);
 920                                 break;
 921
 922                         case Binary.Operator.Equality:
 923                                 if (TypeManager.IsReferenceType (lt) && TypeManager.IsReferenceType (rt) ||
 924                                         (left is Nullable.LiftedNull && right.IsNull) ||
 925                                         (right is Nullable.LiftedNull && left.IsNull)) {
 926                                         if (left.IsNull || right.IsNull) {
 927                                                 return ReducedExpression.Create (
 928                                                         new BoolConstant (left.IsNull == right.IsNull, left.Location).Resolve (ec),
 929                                                         new Binary (oper, left, right, loc));
 930                                         }
 931
 932                                         if (left is StringConstant && right is StringConstant)
 933                                                 return new BoolConstant (
 934                                                         ((StringConstant) left).Value == ((StringConstant) right).Value, left.Location);
 935
 936                                         return null;
 937                                 }
 938
 939                                 if (!DoBinaryNumericPromotions (ec, ref left, ref right))
 940                                         return null;
 941
 942                                 bool_res = false;
 943                                 if (left is DoubleConstant)
 944                                         bool_res = ((DoubleConstant) left).Value ==
 945                                                 ((DoubleConstant) right).Value;
 946                                 else if (left is FloatConstant)
 947                                         bool_res = ((FloatConstant) left).Value ==
 948                                                 ((FloatConstant) right).Value;
 949                                 else if (left is ULongConstant)
 950                                         bool_res = ((ULongConstant) left).Value ==
 951                                                 ((ULongConstant) right).Value;
 952                                 else if (left is LongConstant)
 953                                         bool_res = ((LongConstant) left).Value ==
 954                                                 ((LongConstant) right).Value;
 955                                 else if (left is UIntConstant)
 956                                         bool_res = ((UIntConstant) left).Value ==
 957                                                 ((UIntConstant) right).Value;
 958                                 else if (left is IntConstant)
 959                                         bool_res = ((IntConstant) left).Value ==
 960                                                 ((IntConstant) right).Value;
 961                                 else
 962                                         return null;
 963
 964                                 return new BoolConstant (bool_res, left.Location);
 965
 966                         case Binary.Operator.Inequality:
 967                                 if (TypeManager.IsReferenceType (lt) && TypeManager.IsReferenceType (rt) ||
 968                                         (left is Nullable.LiftedNull && right.IsNull) ||
 969                                         (right is Nullable.LiftedNull && left.IsNull)) {
 970                                         if (left.IsNull || right.IsNull) {
 971                                                 return ReducedExpression.Create (
 972                                                         new BoolConstant (left.IsNull != right.IsNull, left.Location).Resolve (ec),
 973                                                         new Binary (oper, left, right, loc));
 974                                         }
 975
 976                                         if (left is StringConstant && right is StringConstant)
 977                                                 return new BoolConstant (
 978                                                         ((StringConstant) left).Value != ((StringConstant) right).Value, left.Location);
 979
 980                                         return null;
 981                                 }
 982
 983                                 if (!DoBinaryNumericPromotions (ec, ref left, ref right))
 984                                         return null;
 985
 986                                 bool_res = false;
 987                                 if (left is DoubleConstant)
 988                                         bool_res = ((DoubleConstant) left).Value !=
 989                                                 ((DoubleConstant) right).Value;
 990                                 else if (left is FloatConstant)
 991                                         bool_res = ((FloatConstant) left).Value !=
 992                                                 ((FloatConstant) right).Value;
 993                                 else if (left is ULongConstant)
 994                                         bool_res = ((ULongConstant) left).Value !=
 995                                                 ((ULongConstant) right).Value;
 996                                 else if (left is LongConstant)
 997                                         bool_res = ((LongConstant) left).Value !=
 998                                                 ((LongConstant) right).Value;
 999                                 else if (left is UIntConstant)
1000                                         bool_res = ((UIntConstant) left).Value !=
1001                                                 ((UIntConstant) right).Value;
1002                                 else if (left is IntConstant)
1003                                         bool_res = ((IntConstant) left).Value !=
1004                                                 ((IntConstant) right).Value;
1005                                 else
1006                                         return null;
1007
1008                                 return new BoolConstant (bool_res, left.Location);
1009
1010                         case Binary.Operator.LessThan:
1011                                 if (right is NullLiteral) {
1012                                         if (left is NullLiteral) {
1013                                                 var lifted_int = new Nullable.NullableType (TypeManager.int32_type, loc).ResolveAsTypeTerminal (ec, false);
1014                                                 return (Constant) new Nullable.LiftedBinaryOperator (oper, lifted_int, right, loc).Resolve (ec);
1015                                         }
1016
1017                                         if (left is Nullable.LiftedNull) {
1018                                                 return (Constant) new Nullable.LiftedBinaryOperator (oper, left, right, loc).Resolve (ec);
1019                                         }
1020                                 }
1021
1022                                 if (!DoBinaryNumericPromotions (ec, ref left, ref right))
1023                                         return null;
1024
1025                                 bool_res = false;
1026                                 if (left is DoubleConstant)
1027                                         bool_res = ((DoubleConstant) left).Value <
1028                                                 ((DoubleConstant) right).Value;
1029                                 else if (left is FloatConstant)
1030                                         bool_res = ((FloatConstant) left).Value <
1031                                                 ((FloatConstant) right).Value;
1032                                 else if (left is ULongConstant)
1033                                         bool_res = ((ULongConstant) left).Value <
1034                                                 ((ULongConstant) right).Value;
1035                                 else if (left is LongConstant)
1036                                         bool_res = ((LongConstant) left).Value <
1037                                                 ((LongConstant) right).Value;
1038                                 else if (left is UIntConstant)
1039                                         bool_res = ((UIntConstant) left).Value <
1040                                                 ((UIntConstant) right).Value;
1041                                 else if (left is IntConstant)
1042                                         bool_res = ((IntConstant) left).Value <
1043                                                 ((IntConstant) right).Value;
1044                                 else
1045                                         return null;
1046
1047                                 return new BoolConstant (bool_res, left.Location);
1048
1049                         case Binary.Operator.GreaterThan:
1050                                 if (right is NullLiteral) {
1051                                         if (left is NullLiteral) {
1052                                                 var lifted_int = new Nullable.NullableType (TypeManager.int32_type, loc).ResolveAsTypeTerminal (ec, false);
1053                                                 return (Constant) new Nullable.LiftedBinaryOperator (oper, lifted_int, right, loc).Resolve (ec);
1054                                         }
1055
1056                                         if (left is Nullable.LiftedNull) {
1057                                                 return (Constant) new Nullable.LiftedBinaryOperator (oper, left, right, loc).Resolve (ec);
1058                                         }
1059                                 }
1060
1061                                 if (!DoBinaryNumericPromotions (ec, ref left, ref right))
1062                                         return null;
1063
1064                                 bool_res = false;
1065                                 if (left is DoubleConstant)
1066                                         bool_res = ((DoubleConstant) left).Value >
1067                                                 ((DoubleConstant) right).Value;
1068                                 else if (left is FloatConstant)
1069                                         bool_res = ((FloatConstant) left).Value >
1070                                                 ((FloatConstant) right).Value;
1071                                 else if (left is ULongConstant)
1072                                         bool_res = ((ULongConstant) left).Value >
1073                                                 ((ULongConstant) right).Value;
1074                                 else if (left is LongConstant)
1075                                         bool_res = ((LongConstant) left).Value >
1076                                                 ((LongConstant) right).Value;
1077                                 else if (left is UIntConstant)
1078                                         bool_res = ((UIntConstant) left).Value >
1079                                                 ((UIntConstant) right).Value;
1080                                 else if (left is IntConstant)
1081                                         bool_res = ((IntConstant) left).Value >
1082                                                 ((IntConstant) right).Value;
1083                                 else
1084                                         return null;
1085
1086                                 return new BoolConstant (bool_res, left.Location);
1087
1088                         case Binary.Operator.GreaterThanOrEqual:
1089                                 if (right is NullLiteral) {
1090                                         if (left is NullLiteral) {
1091                                                 var lifted_int = new Nullable.NullableType (TypeManager.int32_type, loc).ResolveAsTypeTerminal (ec, false);
1092                                                 return (Constant) new Nullable.LiftedBinaryOperator (oper, lifted_int, right, loc).Resolve (ec);
1093                                         }
1094
1095                                         if (left is Nullable.LiftedNull) {
1096                                                 return (Constant) new Nullable.LiftedBinaryOperator (oper, left, right, loc).Resolve (ec);
1097                                         }
1098                                 }
1099
1100                                 if (!DoBinaryNumericPromotions (ec, ref left, ref right))
1101                                         return null;
1102
1103                                 bool_res = false;
1104                                 if (left is DoubleConstant)
1105                                         bool_res = ((DoubleConstant) left).Value >=
1106                                                 ((DoubleConstant) right).Value;
1107                                 else if (left is FloatConstant)
1108                                         bool_res = ((FloatConstant) left).Value >=
1109                                                 ((FloatConstant) right).Value;
1110                                 else if (left is ULongConstant)
1111                                         bool_res = ((ULongConstant) left).Value >=
1112                                                 ((ULongConstant) right).Value;
1113                                 else if (left is LongConstant)
1114                                         bool_res = ((LongConstant) left).Value >=
1115                                                 ((LongConstant) right).Value;
1116                                 else if (left is UIntConstant)
1117                                         bool_res = ((UIntConstant) left).Value >=
1118                                                 ((UIntConstant) right).Value;
1119                                 else if (left is IntConstant)
1120                                         bool_res = ((IntConstant) left).Value >=
1121                                                 ((IntConstant) right).Value;
1122                                 else
1123                                         return null;
1124
1125                                 return new BoolConstant (bool_res, left.Location);
1126
1127                         case Binary.Operator.LessThanOrEqual:
1128                                 if (right is NullLiteral) {
1129                                         if (left is NullLiteral) {
1130                                                 var lifted_int = new Nullable.NullableType (TypeManager.int32_type, loc).ResolveAsTypeTerminal (ec, false);
1131                                                 return (Constant) new Nullable.LiftedBinaryOperator (oper, lifted_int, right, loc).Resolve (ec);
1132                                         }
1133
1134                                         if (left is Nullable.LiftedNull) {
1135                                                 return (Constant) new Nullable.LiftedBinaryOperator (oper, left, right, loc).Resolve (ec);
1136                                         }
1137                                 }
1138
1139                                 if (!DoBinaryNumericPromotions (ec, ref left, ref right))
1140                                         return null;
1141
1142                                 bool_res = false;
1143                                 if (left is DoubleConstant)
1144                                         bool_res = ((DoubleConstant) left).Value <=
1145                                                 ((DoubleConstant) right).Value;
1146                                 else if (left is FloatConstant)
1147                                         bool_res = ((FloatConstant) left).Value <=
1148                                                 ((FloatConstant) right).Value;
1149                                 else if (left is ULongConstant)
1150                                         bool_res = ((ULongConstant) left).Value <=
1151                                                 ((ULongConstant) right).Value;
1152                                 else if (left is LongConstant)
1153                                         bool_res = ((LongConstant) left).Value <=
1154                                                 ((LongConstant) right).Value;
1155                                 else if (left is UIntConstant)
1156                                         bool_res = ((UIntConstant) left).Value <=
1157                                                 ((UIntConstant) right).Value;
1158                                 else if (left is IntConstant)
1159                                         bool_res = ((IntConstant) left).Value <=
1160                                                 ((IntConstant) right).Value;
1161                                 else
1162                                         return null;
1163
1164                                 return new BoolConstant (bool_res, left.Location);
1165                         }
1166
1167                         return null;
1168                 }
1169         }
1170 }