mcs/class/System.Core/System.Linq.Expressions/BinaryExpression.cs

   1 //
   2 // BinaryExpression.cs
   3 //
   4 // Author:
   5 //   Jb Evain (jbevain@novell.com)
   6 //   Miguel de Icaza (miguel@novell.com)
   7 //
   8 // Contains code from the Mono C# compiler:
   9 //   Marek Safar (marek.safar@seznam.cz)
  10 //   Martin Baulig (martin@ximian.com)
  11 //   Raja Harinath (harinath@gmail.com)
  12 //
  13 // (C) 2001-2003 Ximian, Inc.
  14 // (C) 2004-2008 Novell, Inc. (http://www.novell.com)
  15 //
  16 // Permission is hereby granted, free of charge, to any person obtaining
  17 // a copy of this software and associated documentation files (the
  18 // "Software"), to deal in the Software without restriction, including
  19 // without limitation the rights to use, copy, modify, merge, publish,
  20 // distribute, sublicense, and/or sell copies of the Software, and to
  21 // permit persons to whom the Software is furnished to do so, subject to
  22 // the following conditions:
  23 //
  24 // The above copyright notice and this permission notice shall be
  25 // included in all copies or substantial portions of the Software.
  26 //
  27 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  28 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  29 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  30 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  31 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  32 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  33 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  34 //
  35
  36 using System;
  37 using System.Reflection;
  38 #if !FULL_AOT_RUNTIME
  39 using System.Reflection.Emit;
  40 #endif
  41
  42 namespace System.Linq.Expressions {
  43
  44         public sealed class BinaryExpression : Expression {
  45
  46                 Expression left;
  47                 Expression right;
  48                 LambdaExpression conversion;
  49                 MethodInfo method;
  50                 bool lift_to_null, is_lifted;
  51
  52                 public Expression Left {
  53                         get { return left; }
  54                 }
  55
  56                 public Expression Right {
  57                         get { return right; }
  58                 }
  59
  60                 public MethodInfo Method {
  61                         get { return method; }
  62                 }
  63
  64                 public bool IsLifted {
  65                         get { return is_lifted;  }
  66                 }
  67
  68                 public bool IsLiftedToNull {
  69                         get { return lift_to_null; }
  70                 }
  71
  72                 public LambdaExpression Conversion {
  73                         get { return conversion; }
  74                 }
  75
  76                 internal BinaryExpression (ExpressionType node_type, Type type, Expression left, Expression right)
  77                         : base (node_type, type)
  78                 {
  79                         this.left = left;
  80                         this.right = right;
  81                 }
  82
  83                 internal BinaryExpression (ExpressionType node_type, Type type, Expression left, Expression right, MethodInfo method)
  84                         : base (node_type, type)
  85                 {
  86                         this.left = left;
  87                         this.right = right;
  88                         this.method = method;
  89                 }
  90
  91                 internal BinaryExpression (ExpressionType node_type, Type type, Expression left, Expression right, bool lift_to_null,
  92                         bool is_lifted, MethodInfo method, LambdaExpression conversion) : base (node_type, type)
  93                 {
  94                         this.left = left;
  95                         this.right = right;
  96                         this.method = method;
  97                         this.conversion = conversion;
  98                         this.lift_to_null = lift_to_null;
  99                         this.is_lifted = is_lifted;
 100                 }
 101
 102 #if !FULL_AOT_RUNTIME
 103                 void EmitArrayAccess (EmitContext ec)
 104                 {
 105                         left.Emit (ec);
 106                         right.Emit (ec);
 107                         ec.ig.Emit (OpCodes.Ldelem, this.Type);
 108                 }
 109
 110                 void EmitLogicalBinary (EmitContext ec)
 111                 {
 112                         switch (NodeType) {
 113                         case ExpressionType.And:
 114                         case ExpressionType.Or:
 115                                 if (!IsLifted)
 116                                         EmitLogical (ec);
 117                                 else if (Type == typeof (bool?))
 118                                         EmitLiftedLogical (ec);
 119                                 else
 120                                         EmitLiftedArithmeticBinary (ec);
 121                                 break;
 122                         case ExpressionType.AndAlso:
 123                         case ExpressionType.OrElse:
 124                                 if (!IsLifted)
 125                                         EmitLogicalShortCircuit (ec);
 126                                 else
 127                                         EmitLiftedLogicalShortCircuit (ec);
 128                                 break;
 129                         }
 130                 }
 131
 132                 void EmitLogical (EmitContext ec)
 133                 {
 134                         EmitNonLiftedBinary (ec);
 135                 }
 136
 137                 void EmitLiftedLogical (EmitContext ec)
 138                 {
 139                         var ig = ec.ig;
 140                         var and = NodeType == ExpressionType.And;
 141                         var left = ec.EmitStored (this.left);
 142                         var right = ec.EmitStored (this.right);
 143
 144                         var ret_from_left = ig.DefineLabel ();
 145                         var ret_from_right = ig.DefineLabel ();
 146                         var done = ig.DefineLabel ();
 147
 148                         ec.EmitNullableGetValueOrDefault (left);
 149                         ig.Emit (OpCodes.Brtrue, ret_from_left);
 150                         ec.EmitNullableGetValueOrDefault (right);
 151                         ig.Emit (OpCodes.Brtrue, ret_from_right);
 152
 153                         ec.EmitNullableHasValue (left);
 154                         ig.Emit (OpCodes.Brfalse, ret_from_left);
 155
 156                         ig.MarkLabel (ret_from_right);
 157                         ec.EmitLoad (and ? left : right);
 158                         ig.Emit (OpCodes.Br, done);
 159
 160                         ig.MarkLabel (ret_from_left);
 161                         ec.EmitLoad (and ? right : left);
 162
 163                         ig.MarkLabel (done);
 164                 }
 165
 166                 void EmitLogicalShortCircuit (EmitContext ec)
 167                 {
 168                         var ig = ec.ig;
 169                         var and = NodeType == ExpressionType.AndAlso;
 170                         var ret = ig.DefineLabel ();
 171                         var done = ig.DefineLabel ();
 172
 173                         ec.Emit (left);
 174                         ig.Emit (and ? OpCodes.Brfalse : OpCodes.Brtrue, ret);
 175
 176                         ec.Emit (right);
 177
 178                         ig.Emit (OpCodes.Br, done);
 179
 180                         ig.MarkLabel (ret);
 181                         ig.Emit (and ? OpCodes.Ldc_I4_0 : OpCodes.Ldc_I4_1);
 182
 183                         ig.MarkLabel (done);
 184                 }
 185
 186                 MethodInfo GetFalseOperator ()
 187                 {
 188                         return GetFalseOperator (left.Type.GetNotNullableType ());
 189                 }
 190
 191                 MethodInfo GetTrueOperator ()
 192                 {
 193                         return GetTrueOperator (left.Type.GetNotNullableType ());
 194                 }
 195
 196                 void EmitUserDefinedLogicalShortCircuit (EmitContext ec)
 197                 {
 198                         var ig = ec.ig;
 199                         var and = NodeType == ExpressionType.AndAlso;
 200
 201                         var done = ig.DefineLabel ();
 202
 203                         var left = ec.EmitStored (this.left);
 204
 205                         ec.EmitLoad (left);
 206                         ig.Emit (OpCodes.Dup);
 207                         ec.EmitCall (and ? GetFalseOperator () : GetTrueOperator ());
 208                         ig.Emit (OpCodes.Brtrue, done);
 209
 210                         ec.Emit (this.right);
 211                         ec.EmitCall (method);
 212
 213                         ig.MarkLabel (done);
 214                 }
 215
 216                 void EmitLiftedLogicalShortCircuit (EmitContext ec)
 217                 {
 218                         var ig = ec.ig;
 219                         var and = NodeType == ExpressionType.AndAlso;
 220                         var left_is_null = ig.DefineLabel ();
 221                         var ret_from_left = ig.DefineLabel ();
 222                         var ret_null = ig.DefineLabel ();
 223                         var ret_new = ig.DefineLabel();
 224                         var done = ig.DefineLabel();
 225
 226                         var left = ec.EmitStored (this.left);
 227
 228                         ec.EmitNullableHasValue (left);
 229                         ig.Emit (OpCodes.Brfalse, left_is_null);
 230
 231                         ec.EmitNullableGetValueOrDefault (left);
 232
 233                         ig.Emit (OpCodes.Ldc_I4_0);
 234                         ig.Emit (OpCodes.Ceq);
 235                         ig.Emit (and ? OpCodes.Brtrue : OpCodes.Brfalse, ret_from_left);
 236
 237                         ig.MarkLabel (left_is_null);
 238                         var right = ec.EmitStored (this.right);
 239
 240                         ec.EmitNullableHasValue (right);
 241                         ig.Emit (OpCodes.Brfalse_S, ret_null);
 242
 243                         ec.EmitNullableGetValueOrDefault (right);
 244
 245                         ig.Emit (OpCodes.Ldc_I4_0);
 246                         ig.Emit (OpCodes.Ceq);
 247
 248                         ig.Emit (and ? OpCodes.Brtrue : OpCodes.Brfalse, ret_from_left);
 249
 250                         ec.EmitNullableHasValue (left);
 251                         ig.Emit (OpCodes.Brfalse, ret_null);
 252
 253                         ig.Emit (and ? OpCodes.Ldc_I4_1 : OpCodes.Ldc_I4_0);
 254                         ig.Emit (OpCodes.Br_S, ret_new);
 255
 256                         ig.MarkLabel (ret_from_left);
 257                         ig.Emit (and ? OpCodes.Ldc_I4_0 : OpCodes.Ldc_I4_1);
 258
 259                         ig.MarkLabel (ret_new);
 260                         ec.EmitNullableNew (Type);
 261                         ig.Emit (OpCodes.Br, done);
 262
 263                         ig.MarkLabel (ret_null);
 264                         var ret = ig.DeclareLocal (Type);
 265                         ec.EmitNullableInitialize (ret);
 266
 267                         ig.MarkLabel (done);
 268                 }
 269
 270                 void EmitCoalesce (EmitContext ec)
 271                 {
 272                         var ig = ec.ig;
 273                         var done = ig.DefineLabel ();
 274                         var load_right = ig.DefineLabel ();
 275
 276                         var left = ec.EmitStored (this.left);
 277                         var left_is_nullable = left.LocalType.IsNullable ();
 278
 279                         if (left_is_nullable)
 280                                 ec.EmitNullableHasValue (left);
 281                         else
 282                                 ec.EmitLoad (left);
 283
 284                         ig.Emit (OpCodes.Brfalse, load_right);
 285
 286                         if (left_is_nullable && !Type.IsNullable ())
 287                                 ec.EmitNullableGetValue (left);
 288                         else
 289                                 ec.EmitLoad (left);
 290
 291                         ig.Emit (OpCodes.Br, done);
 292
 293                         ig.MarkLabel (load_right);
 294                         ec.Emit (this.right);
 295
 296                         ig.MarkLabel (done);
 297                 }
 298
 299                 void EmitConvertedCoalesce (EmitContext ec)
 300                 {
 301                         var ig = ec.ig;
 302                         var done = ig.DefineLabel ();
 303                         var load_right = ig.DefineLabel ();
 304
 305                         var left = ec.EmitStored (this.left);
 306
 307                         if (left.LocalType.IsNullable ())
 308                                 ec.EmitNullableHasValue (left);
 309                         else
 310                                 ec.EmitLoad (left);
 311
 312                         ig.Emit (OpCodes.Brfalse, load_right);
 313
 314                         ec.Emit (conversion);
 315                         ec.EmitLoad (left);
 316                         ig.Emit (OpCodes.Callvirt, conversion.Type.GetInvokeMethod ());
 317
 318                         ig.Emit (OpCodes.Br, done);
 319
 320                         ig.MarkLabel (load_right);
 321                         ec.Emit (this.right);
 322
 323                         ig.MarkLabel (done);
 324                 }
 325
 326                 static bool IsInt32OrInt64 (Type type)
 327                 {
 328                         return type == typeof (int) || type == typeof (long);
 329                 }
 330
 331                 static bool IsSingleOrDouble (Type type)
 332                 {
 333                         return type == typeof (float) || type == typeof (double);
 334                 }
 335
 336                 void EmitBinaryOperator (EmitContext ec)
 337                 {
 338                         var ig = ec.ig;
 339                         bool is_unsigned = IsUnsigned (left.Type);
 340
 341                         switch (NodeType) {
 342                         case ExpressionType.Add:
 343                                 ig.Emit (OpCodes.Add);
 344                                 break;
 345                         case ExpressionType.AddChecked:
 346                                 if (IsInt32OrInt64 (left.Type))
 347                                         ig.Emit (OpCodes.Add_Ovf);
 348                                 else
 349                                         ig.Emit (is_unsigned ? OpCodes.Add_Ovf_Un : OpCodes.Add);
 350                                 break;
 351                         case ExpressionType.Subtract:
 352                                 ig.Emit (OpCodes.Sub);
 353                                 break;
 354                         case ExpressionType.SubtractChecked:
 355                                 if (IsInt32OrInt64 (left.Type))
 356                                         ig.Emit (OpCodes.Sub_Ovf);
 357                                 else
 358                                         ig.Emit (is_unsigned ? OpCodes.Sub_Ovf_Un : OpCodes.Sub);
 359                                 break;
 360                         case ExpressionType.Multiply:
 361                                 ig.Emit (OpCodes.Mul);
 362                                 break;
 363                         case ExpressionType.MultiplyChecked:
 364                                 if (IsInt32OrInt64 (left.Type))
 365                                         ig.Emit (OpCodes.Mul_Ovf);
 366                                 else
 367                                         ig.Emit (is_unsigned ? OpCodes.Mul_Ovf_Un : OpCodes.Mul);
 368                                 break;
 369                         case ExpressionType.Divide:
 370                                 ig.Emit (is_unsigned ? OpCodes.Div_Un : OpCodes.Div);
 371                                 break;
 372                         case ExpressionType.Modulo:
 373                                 ig.Emit (is_unsigned ? OpCodes.Rem_Un : OpCodes.Rem);
 374                                 break;
 375                         case ExpressionType.RightShift:
 376                         case ExpressionType.LeftShift:
 377                                 ig.Emit (OpCodes.Ldc_I4, left.Type == typeof (int) ? 0x1f : 0x3f);
 378                                 ig.Emit (OpCodes.And);
 379                                 if (NodeType == ExpressionType.RightShift)
 380                                         ig.Emit (is_unsigned ? OpCodes.Shr_Un : OpCodes.Shr);
 381                                 else
 382                                         ig.Emit (OpCodes.Shl);
 383                                 break;
 384                         case ExpressionType.And:
 385                                 ig.Emit (OpCodes.And);
 386                                 break;
 387                         case ExpressionType.Or:
 388                                 ig.Emit (OpCodes.Or);
 389                                 break;
 390                         case ExpressionType.ExclusiveOr:
 391                                 ig.Emit (OpCodes.Xor);
 392                                 break;
 393                         case ExpressionType.GreaterThan:
 394                                 ig.Emit (is_unsigned ? OpCodes.Cgt_Un : OpCodes.Cgt);
 395                                 break;
 396                         case ExpressionType.GreaterThanOrEqual:
 397                                 if (is_unsigned || IsSingleOrDouble (left.Type))
 398                                         ig.Emit (OpCodes.Clt_Un);
 399                                 else
 400                                         ig.Emit (OpCodes.Clt);
 401
 402                                 ig.Emit (OpCodes.Ldc_I4_0);
 403                                 ig.Emit (OpCodes.Ceq);
 404                                 break;
 405                         case ExpressionType.LessThan:
 406                                 ig.Emit (is_unsigned ? OpCodes.Clt_Un : OpCodes.Clt);
 407                                 break;
 408                         case ExpressionType.LessThanOrEqual:
 409                                 if (is_unsigned || IsSingleOrDouble (left.Type))
 410                                         ig.Emit (OpCodes.Cgt_Un);
 411                                 else
 412                                         ig.Emit (OpCodes.Cgt);
 413
 414                                 ig.Emit (OpCodes.Ldc_I4_0);
 415                                 ig.Emit (OpCodes.Ceq);
 416                                 break;
 417                         case ExpressionType.Equal:
 418                                 ig.Emit (OpCodes.Ceq);
 419                                 break;
 420                         case ExpressionType.NotEqual:
 421                                 ig.Emit (OpCodes.Ceq);
 422                                 ig.Emit (OpCodes.Ldc_I4_0);
 423                                 ig.Emit (OpCodes.Ceq);
 424                                 break;
 425                         case ExpressionType.Power:
 426                                 ig.Emit (OpCodes.Call, typeof (Math).GetMethod ("Pow"));
 427                                 break;
 428                         default:
 429                                 throw new InvalidOperationException (
 430                                         string.Format ("Internal error: BinaryExpression contains non-Binary nodetype {0}", NodeType));
 431                         }
 432                 }
 433
 434                 bool IsLeftLiftedBinary ()
 435                 {
 436                         return left.Type.IsNullable () && !right.Type.IsNullable ();
 437                 }
 438
 439                 void EmitLeftLiftedToNullBinary (EmitContext ec)
 440                 {
 441                         var ig = ec.ig;
 442
 443                         var ret = ig.DefineLabel ();
 444                         var done = ig.DefineLabel ();
 445
 446                         var left = ec.EmitStored (this.left);
 447
 448                         ec.EmitNullableHasValue (left);
 449                         ig.Emit (OpCodes.Brfalse, ret);
 450
 451                         ec.EmitNullableGetValueOrDefault (left);
 452                         ec.Emit (right);
 453
 454                         EmitBinaryOperator (ec);
 455
 456                         ec.EmitNullableNew (Type);
 457
 458                         ig.Emit (OpCodes.Br, done);
 459
 460                         ig.MarkLabel (ret);
 461
 462                         var temp = ig.DeclareLocal (Type);
 463                         ec.EmitNullableInitialize (temp);
 464
 465                         ig.MarkLabel (done);
 466                 }
 467
 468                 void EmitLiftedArithmeticBinary (EmitContext ec)
 469                 {
 470                         if (IsLeftLiftedBinary ())
 471                                 EmitLeftLiftedToNullBinary (ec);
 472                         else
 473                                 EmitLiftedToNullBinary (ec);
 474                 }
 475
 476                 void EmitLiftedToNullBinary (EmitContext ec)
 477                 {
 478                         var ig = ec.ig;
 479                         var left = ec.EmitStored (this.left);
 480                         var right = ec.EmitStored (this.right);
 481                         var result = ig.DeclareLocal (Type);
 482
 483                         var has_value = ig.DefineLabel ();
 484                         var done = ig.DefineLabel ();
 485
 486                         ec.EmitNullableHasValue (left);
 487                         ec.EmitNullableHasValue (right);
 488                         ig.Emit (OpCodes.And);
 489                         ig.Emit (OpCodes.Brtrue, has_value);
 490
 491                         ec.EmitNullableInitialize (result);
 492
 493                         ig.Emit (OpCodes.Br, done);
 494
 495                         ig.MarkLabel (has_value);
 496
 497                         ec.EmitNullableGetValueOrDefault (left);
 498                         ec.EmitNullableGetValueOrDefault (right);
 499
 500                         EmitBinaryOperator (ec);
 501
 502                         ec.EmitNullableNew (result.LocalType);
 503
 504                         ig.MarkLabel (done);
 505                 }
 506
 507                 void EmitLiftedRelationalBinary (EmitContext ec)
 508                 {
 509                         var ig = ec.ig;
 510                         var left = ec.EmitStored (this.left);
 511                         var right = ec.EmitStored (this.right);
 512
 513                         var ret = ig.DefineLabel ();
 514                         var done = ig.DefineLabel ();
 515
 516                         ec.EmitNullableGetValueOrDefault (left);
 517                         ec.EmitNullableGetValueOrDefault (right);
 518
 519                         switch (NodeType) {
 520                         case ExpressionType.Equal:
 521                         case ExpressionType.NotEqual:
 522                                 ig.Emit (OpCodes.Bne_Un, ret);
 523                                 break;
 524                         default:
 525                                 EmitBinaryOperator (ec);
 526                                 ig.Emit (OpCodes.Brfalse, ret);
 527                                 break;
 528                         }
 529
 530                         ec.EmitNullableHasValue (left);
 531                         ec.EmitNullableHasValue (right);
 532
 533                         switch (NodeType) {
 534                         case ExpressionType.Equal:
 535                                 ig.Emit (OpCodes.Ceq);
 536                                 break;
 537                         case ExpressionType.NotEqual:
 538                                 ig.Emit (OpCodes.Ceq);
 539                                 ig.Emit (OpCodes.Ldc_I4_0);
 540                                 ig.Emit (OpCodes.Ceq);
 541                                 break;
 542                         default:
 543                                 ig.Emit (OpCodes.And);
 544                                 break;
 545                         }
 546
 547                         ig.Emit (OpCodes.Br, done);
 548
 549                         ig.MarkLabel (ret);
 550
 551                         ig.Emit (NodeType == ExpressionType.NotEqual ? OpCodes.Ldc_I4_1 : OpCodes.Ldc_I4_0);
 552
 553                         ig.MarkLabel (done);
 554                 }
 555
 556                 void EmitArithmeticBinary (EmitContext ec)
 557                 {
 558                         if (!IsLifted)
 559                                 EmitNonLiftedBinary (ec);
 560                         else
 561                                 EmitLiftedArithmeticBinary (ec);
 562                 }
 563
 564                 void EmitNonLiftedBinary (EmitContext ec)
 565                 {
 566                         ec.Emit (left);
 567                         ec.Emit (right);
 568                         EmitBinaryOperator (ec);
 569                 }
 570
 571                 void EmitRelationalBinary (EmitContext ec)
 572                 {
 573                         if (!IsLifted) {
 574                                 EmitNonLiftedBinary (ec);
 575                                 return;
 576                         }
 577
 578                         if (IsLiftedToNull) {
 579                                 EmitLiftedToNullBinary (ec);
 580                                 return;
 581                         }
 582
 583                         if (ConstantExpression.IsNull (right) && !ConstantExpression.IsNull (left) && left.Type.IsNullable ()) {
 584                                 EmitNullEquality (ec, left);
 585                                 return;
 586                         }
 587
 588                         if (ConstantExpression.IsNull (left) && !ConstantExpression.IsNull (right) && right.Type.IsNullable ()) {
 589                                 EmitNullEquality (ec, right);
 590                                 return;
 591                         }
 592
 593                         EmitLiftedRelationalBinary (ec);
 594                 }
 595
 596                 void EmitNullEquality (EmitContext ec, Expression e)
 597                 {
 598                         var ig = ec.ig;
 599
 600                         if (IsLiftedToNull) {
 601                                 e.Emit (ec);
 602                                 if (e.Type != typeof (void))
 603                                         ig.Emit (OpCodes.Pop);
 604
 605                                 ec.EmitNullableNew (typeof (bool?));
 606                                 return;
 607                         }
 608
 609                         var se = ec.EmitStored (e);
 610                         ec.EmitNullableHasValue (se);
 611                         if (NodeType == ExpressionType.Equal) {
 612                                 ig.Emit (OpCodes.Ldc_I4_0);
 613                                 ig.Emit (OpCodes.Ceq);
 614                         }
 615                 }
 616
 617                 void EmitLiftedUserDefinedOperator (EmitContext ec)
 618                 {
 619                         var ig = ec.ig;
 620
 621                         var ret_true = ig.DefineLabel ();
 622                         var ret_false = ig.DefineLabel ();
 623                         var done = ig.DefineLabel ();
 624
 625                         var left = ec.EmitStored (this.left);
 626                         var right = ec.EmitStored (this.right);
 627
 628                         ec.EmitNullableHasValue (left);
 629                         ec.EmitNullableHasValue (right);
 630                         switch (NodeType) {
 631                         case ExpressionType.Equal:
 632                                 ig.Emit (OpCodes.Bne_Un, ret_false);
 633                                 ec.EmitNullableHasValue (left);
 634                                 ig.Emit (OpCodes.Brfalse, ret_true);
 635                                 break;
 636                         case ExpressionType.NotEqual:
 637                                 ig.Emit (OpCodes.Bne_Un, ret_true);
 638                                 ec.EmitNullableHasValue (left);
 639                                 ig.Emit (OpCodes.Brfalse, ret_false);
 640                                 break;
 641                         default:
 642                                 ig.Emit (OpCodes.And);
 643                                 ig.Emit (OpCodes.Brfalse, ret_false);
 644                                 break;
 645                         }
 646
 647                         ec.EmitNullableGetValueOrDefault (left);
 648                         ec.EmitNullableGetValueOrDefault (right);
 649                         ec.EmitCall (method);
 650                         ig.Emit (OpCodes.Br, done);
 651
 652                         ig.MarkLabel (ret_true);
 653                         ig.Emit (OpCodes.Ldc_I4_1);
 654                         ig.Emit (OpCodes.Br, done);
 655
 656                         ig.MarkLabel (ret_false);
 657                         ig.Emit (OpCodes.Ldc_I4_0);
 658                         ig.Emit (OpCodes.Br, done);
 659
 660                         ig.MarkLabel (done);
 661                 }
 662
 663                 void EmitLiftedToNullUserDefinedOperator (EmitContext ec)
 664                 {
 665                         var ig = ec.ig;
 666
 667                         var ret = ig.DefineLabel ();
 668                         var done = ig.DefineLabel ();
 669
 670                         var left = ec.EmitStored (this.left);
 671                         var right = ec.EmitStored (this.right);
 672
 673                         ec.EmitNullableHasValue (left);
 674                         ec.EmitNullableHasValue (right);
 675                         ig.Emit (OpCodes.And);
 676                         ig.Emit (OpCodes.Brfalse, ret);
 677
 678                         ec.EmitNullableGetValueOrDefault (left);
 679                         ec.EmitNullableGetValueOrDefault (right);
 680                         ec.EmitCall (method);
 681                         ec.EmitNullableNew (Type);
 682                         ig.Emit (OpCodes.Br, done);
 683
 684                         ig.MarkLabel (ret);
 685                         var temp = ig.DeclareLocal (Type);
 686                         ec.EmitNullableInitialize (temp);
 687
 688                         ig.MarkLabel (done);
 689                 }
 690
 691                 void EmitUserDefinedLiftedLogicalShortCircuit (EmitContext ec)
 692                 {
 693                         var ig = ec.ig;
 694                         var and = NodeType == ExpressionType.AndAlso;
 695
 696                         var left_is_null = ig.DefineLabel ();
 697                         var ret_left = ig.DefineLabel ();
 698                         var ret_null = ig.DefineLabel ();
 699                         var done = ig.DefineLabel ();
 700
 701                         var left = ec.EmitStored (this.left);
 702
 703                         ec.EmitNullableHasValue (left);
 704                         ig.Emit (OpCodes.Brfalse, and ? ret_null : left_is_null);
 705
 706                         ec.EmitNullableGetValueOrDefault (left);
 707                         ec.EmitCall (and ? GetFalseOperator () : GetTrueOperator ());
 708                         ig.Emit (OpCodes.Brtrue, ret_left);
 709
 710                         ig.MarkLabel (left_is_null);
 711                         var right = ec.EmitStored (this.right);
 712                         ec.EmitNullableHasValue (right);
 713                         ig.Emit (OpCodes.Brfalse, ret_null);
 714
 715                         ec.EmitNullableGetValueOrDefault (left);
 716                         ec.EmitNullableGetValueOrDefault (right);
 717                         ec.EmitCall (method);
 718
 719                         ec.EmitNullableNew (Type);
 720                         ig.Emit (OpCodes.Br, done);
 721
 722                         ig.MarkLabel (ret_left);
 723                         ec.EmitLoad (left);
 724                         ig.Emit (OpCodes.Br, done);
 725
 726                         ig.MarkLabel (ret_null);
 727                         var ret = ig.DeclareLocal (Type);
 728                         ec.EmitNullableInitialize (ret);
 729
 730                         ig.MarkLabel (done);
 731                 }
 732
 733                 void EmitUserDefinedOperator (EmitContext ec)
 734                 {
 735                         if (!IsLifted) {
 736                                 switch (NodeType) {
 737                                 case ExpressionType.AndAlso:
 738                                 case ExpressionType.OrElse:
 739                                         EmitUserDefinedLogicalShortCircuit (ec);
 740                                         break;
 741                                 default:
 742                                         left.Emit (ec);
 743                                         right.Emit (ec);
 744                                         ec.EmitCall (method);
 745                                         break;
 746                                 }
 747                         } else if (IsLiftedToNull) {
 748                                 switch (NodeType) {
 749                                 case ExpressionType.AndAlso:
 750                                 case ExpressionType.OrElse:
 751                                         EmitUserDefinedLiftedLogicalShortCircuit (ec);
 752                                         break;
 753                                 default:
 754                                         EmitLiftedToNullUserDefinedOperator (ec);
 755                                         break;
 756                                 }
 757                         }  else
 758                                 EmitLiftedUserDefinedOperator (ec);
 759                 }
 760
 761                 internal override void Emit (EmitContext ec)
 762                 {
 763                         if (method != null) {
 764                                 EmitUserDefinedOperator (ec);
 765                                 return;
 766                         }
 767
 768                         switch (NodeType){
 769                         case ExpressionType.ArrayIndex:
 770                                 EmitArrayAccess (ec);
 771                                 return;
 772                         case ExpressionType.Coalesce:
 773                                 if (conversion != null)
 774                                         EmitConvertedCoalesce (ec);
 775                                 else
 776                                         EmitCoalesce (ec);
 777                                 return;
 778                         case ExpressionType.Power:
 779                         case ExpressionType.Add:
 780                         case ExpressionType.AddChecked:
 781                         case ExpressionType.Divide:
 782                         case ExpressionType.ExclusiveOr:
 783                         case ExpressionType.LeftShift:
 784                         case ExpressionType.Modulo:
 785                         case ExpressionType.Multiply:
 786                         case ExpressionType.MultiplyChecked:
 787                         case ExpressionType.RightShift:
 788                         case ExpressionType.Subtract:
 789                         case ExpressionType.SubtractChecked:
 790                                 EmitArithmeticBinary (ec);
 791                                 return;
 792                         case ExpressionType.Equal:
 793                         case ExpressionType.GreaterThan:
 794                         case ExpressionType.GreaterThanOrEqual:
 795                         case ExpressionType.LessThan:
 796                         case ExpressionType.LessThanOrEqual:
 797                         case ExpressionType.NotEqual:
 798                                 EmitRelationalBinary (ec);
 799                                 return;
 800                         case ExpressionType.And:
 801                         case ExpressionType.Or:
 802                         case ExpressionType.AndAlso:
 803                         case ExpressionType.OrElse:
 804                                 EmitLogicalBinary (ec);
 805                                 return;
 806                         default:
 807                                 throw new NotSupportedException (this.NodeType.ToString ());
 808                         }
 809                 }
 810 #endif
 811         }
 812 }