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 using System.Reflection.Emit;
  39
  40 namespace System.Linq.Expressions {
  41
  42         public sealed class BinaryExpression : Expression {
  43
  44                 Expression left;
  45                 Expression right;
  46                 LambdaExpression conversion;
  47                 MethodInfo method;
  48                 bool lift_to_null, is_lifted;
  49
  50                 public Expression Left {
  51                         get { return left; }
  52                 }
  53
  54                 public Expression Right {
  55                         get { return right; }
  56                 }
  57
  58                 public MethodInfo Method {
  59                         get { return method; }
  60                 }
  61
  62                 public bool IsLifted {
  63                         get { return is_lifted;  }
  64                 }
  65
  66                 public bool IsLiftedToNull {
  67                         get { return lift_to_null; }
  68                 }
  69
  70                 public LambdaExpression Conversion {
  71                         get { return conversion; }
  72                 }
  73
  74                 internal BinaryExpression (ExpressionType node_type, Type type, Expression left, Expression right)
  75                         : base (node_type, type)
  76                 {
  77                         this.left = left;
  78                         this.right = right;
  79                 }
  80
  81                 internal BinaryExpression (ExpressionType node_type, Type type, Expression left, Expression right, MethodInfo method)
  82                         : base (node_type, type)
  83                 {
  84                         this.left = left;
  85                         this.right = right;
  86                         this.method = method;
  87                 }
  88
  89                 internal BinaryExpression (ExpressionType node_type, Type type, Expression left, Expression right, bool lift_to_null,
  90                         bool is_lifted, MethodInfo method, LambdaExpression conversion) : base (node_type, type)
  91                 {
  92                         this.left = left;
  93                         this.right = right;
  94                         this.method = method;
  95                         this.conversion = conversion;
  96                         this.lift_to_null = lift_to_null;
  97                         this.is_lifted = is_lifted;
  98                 }
  99
 100                 void EmitArrayAccess (EmitContext ec)
 101                 {
 102                         left.Emit (ec);
 103                         right.Emit (ec);
 104                         ec.ig.Emit (OpCodes.Ldelem, this.Type);
 105                 }
 106
 107                 void EmitLogicalBinary (EmitContext ec)
 108                 {
 109                         switch (NodeType) {
 110                         case ExpressionType.And:
 111                         case ExpressionType.Or:
 112                                 if (!IsLifted)
 113                                         EmitLogical (ec);
 114                                 else if (Type == typeof (bool?))
 115                                         EmitLiftedLogical (ec);
 116                                 else
 117                                         EmitLiftedArithmeticBinary (ec);
 118                                 break;
 119                         case ExpressionType.AndAlso:
 120                         case ExpressionType.OrElse:
 121                                 if (!IsLifted)
 122                                         EmitLogicalShortCircuit (ec);
 123                                 else
 124                                         EmitLiftedLogicalShortCircuit (ec);
 125                                 break;
 126                         }
 127                 }
 128
 129                 void EmitLogical (EmitContext ec)
 130                 {
 131                         EmitNonLiftedBinary (ec);
 132                 }
 133
 134                 void EmitLiftedLogical (EmitContext ec)
 135                 {
 136                         var ig = ec.ig;
 137                         var and = NodeType == ExpressionType.And;
 138                         var left = ec.EmitStored (this.left);
 139                         var right = ec.EmitStored (this.right);
 140
 141                         var ret_from_left = ig.DefineLabel ();
 142                         var ret_from_right = ig.DefineLabel ();
 143                         var done = ig.DefineLabel ();
 144
 145                         ec.EmitNullableGetValueOrDefault (left);
 146                         ig.Emit (OpCodes.Brtrue, ret_from_left);
 147                         ec.EmitNullableGetValueOrDefault (right);
 148                         ig.Emit (OpCodes.Brtrue, ret_from_right);
 149
 150                         ec.EmitNullableHasValue (left);
 151                         ig.Emit (OpCodes.Brfalse, ret_from_left);
 152
 153                         ig.MarkLabel (ret_from_right);
 154                         ec.EmitLoad (and ? left : right);
 155                         ig.Emit (OpCodes.Br, done);
 156
 157                         ig.MarkLabel (ret_from_left);
 158                         ec.EmitLoad (and ? right : left);
 159
 160                         ig.MarkLabel (done);
 161                 }
 162
 163                 void EmitLogicalShortCircuit (EmitContext ec)
 164                 {
 165                         var ig = ec.ig;
 166                         var and = NodeType == ExpressionType.AndAlso;
 167                         var ret = ig.DefineLabel ();
 168                         var done = ig.DefineLabel ();
 169
 170                         ec.Emit (left);
 171                         ig.Emit (and ? OpCodes.Brfalse : OpCodes.Brtrue, ret);
 172
 173                         ec.Emit (right);
 174
 175                         ig.Emit (OpCodes.Br, done);
 176
 177                         ig.MarkLabel (ret);
 178                         ig.Emit (and ? OpCodes.Ldc_I4_0 : OpCodes.Ldc_I4_1);
 179
 180                         ig.MarkLabel (done);
 181                 }
 182
 183                 MethodInfo GetFalseOperator ()
 184                 {
 185                         return GetFalseOperator (left.Type.GetNotNullableType ());
 186                 }
 187
 188                 MethodInfo GetTrueOperator ()
 189                 {
 190                         return GetTrueOperator (left.Type.GetNotNullableType ());
 191                 }
 192
 193                 void EmitUserDefinedLogicalShortCircuit (EmitContext ec)
 194                 {
 195                         var ig = ec.ig;
 196                         var and = NodeType == ExpressionType.AndAlso;
 197
 198                         var done = ig.DefineLabel ();
 199
 200                         var left = ec.EmitStored (this.left);
 201
 202                         ec.EmitLoad (left);
 203                         ig.Emit (OpCodes.Dup);
 204                         ec.EmitCall (and ? GetFalseOperator () : GetTrueOperator ());
 205                         ig.Emit (OpCodes.Brtrue, done);
 206
 207                         ec.Emit (this.right);
 208                         ec.EmitCall (method);
 209
 210                         ig.MarkLabel (done);
 211                 }
 212
 213                 void EmitLiftedLogicalShortCircuit (EmitContext ec)
 214                 {
 215                         var ig = ec.ig;
 216                         var and = NodeType == ExpressionType.AndAlso;
 217                         var left_is_null = ig.DefineLabel ();
 218                         var ret_from_left = ig.DefineLabel ();
 219                         var ret_null = ig.DefineLabel ();
 220                         var ret_new = ig.DefineLabel();
 221                         var done = ig.DefineLabel();
 222
 223                         var left = ec.EmitStored (this.left);
 224
 225                         ec.EmitNullableHasValue (left);
 226                         ig.Emit (OpCodes.Brfalse, left_is_null);
 227
 228                         ec.EmitNullableGetValueOrDefault (left);
 229
 230                         ig.Emit (OpCodes.Ldc_I4_0);
 231                         ig.Emit (OpCodes.Ceq);
 232                         ig.Emit (and ? OpCodes.Brtrue : OpCodes.Brfalse, ret_from_left);
 233
 234                         ig.MarkLabel (left_is_null);
 235                         var right = ec.EmitStored (this.right);
 236
 237                         ec.EmitNullableHasValue (right);
 238                         ig.Emit (OpCodes.Brfalse_S, ret_null);
 239
 240                         ec.EmitNullableGetValueOrDefault (right);
 241
 242                         ig.Emit (OpCodes.Ldc_I4_0);
 243                         ig.Emit (OpCodes.Ceq);
 244
 245                         ig.Emit (and ? OpCodes.Brtrue : OpCodes.Brfalse, ret_from_left);
 246
 247                         ec.EmitNullableHasValue (left);
 248                         ig.Emit (OpCodes.Brfalse, ret_null);
 249
 250                         ig.Emit (and ? OpCodes.Ldc_I4_1 : OpCodes.Ldc_I4_0);
 251                         ig.Emit (OpCodes.Br_S, ret_new);
 252
 253                         ig.MarkLabel (ret_from_left);
 254                         ig.Emit (and ? OpCodes.Ldc_I4_0 : OpCodes.Ldc_I4_1);
 255
 256                         ig.MarkLabel (ret_new);
 257                         ec.EmitNullableNew (Type);
 258                         ig.Emit (OpCodes.Br, done);
 259
 260                         ig.MarkLabel (ret_null);
 261                         var ret = ig.DeclareLocal (Type);
 262                         ec.EmitNullableInitialize (ret);
 263
 264                         ig.MarkLabel (done);
 265                 }
 266
 267                 void EmitCoalesce (EmitContext ec)
 268                 {
 269                         var ig = ec.ig;
 270                         var done = ig.DefineLabel ();
 271                         var load_right = ig.DefineLabel ();
 272
 273                         var left = ec.EmitStored (this.left);
 274                         var left_is_nullable = left.LocalType.IsNullable ();
 275
 276                         if (left_is_nullable)
 277                                 ec.EmitNullableHasValue (left);
 278                         else
 279                                 ec.EmitLoad (left);
 280
 281                         ig.Emit (OpCodes.Brfalse, load_right);
 282
 283                         if (left_is_nullable && !Type.IsNullable ())
 284                                 ec.EmitNullableGetValue (left);
 285                         else
 286                                 ec.EmitLoad (left);
 287
 288                         ig.Emit (OpCodes.Br, done);
 289
 290                         ig.MarkLabel (load_right);
 291                         ec.Emit (this.right);
 292
 293                         ig.MarkLabel (done);
 294                 }
 295
 296                 void EmitConvertedCoalesce (EmitContext ec)
 297                 {
 298                         var ig = ec.ig;
 299                         var done = ig.DefineLabel ();
 300                         var load_right = ig.DefineLabel ();
 301
 302                         var left = ec.EmitStored (this.left);
 303
 304                         if (left.LocalType.IsNullable ())
 305                                 ec.EmitNullableHasValue (left);
 306                         else
 307                                 ec.EmitLoad (left);
 308
 309                         ig.Emit (OpCodes.Brfalse, load_right);
 310
 311                         ec.Emit (conversion);
 312                         ec.EmitLoad (left);
 313                         ig.Emit (OpCodes.Callvirt, conversion.Type.GetInvokeMethod ());
 314
 315                         ig.Emit (OpCodes.Br, done);
 316
 317                         ig.MarkLabel (load_right);
 318                         ec.Emit (this.right);
 319
 320                         ig.MarkLabel (done);
 321                 }
 322
 323                 static bool IsInt32OrInt64 (Type type)
 324                 {
 325                         return type == typeof (int) || type == typeof (long);
 326                 }
 327
 328                 static bool IsSingleOrDouble (Type type)
 329                 {
 330                         return type == typeof (float) || type == typeof (double);
 331                 }
 332
 333                 void EmitBinaryOperator (EmitContext ec)
 334                 {
 335                         var ig = ec.ig;
 336                         bool is_unsigned = IsUnsigned (left.Type);
 337
 338                         switch (NodeType) {
 339                         case ExpressionType.Add:
 340                                 ig.Emit (OpCodes.Add);
 341                                 break;
 342                         case ExpressionType.AddChecked:
 343                                 if (IsInt32OrInt64 (left.Type))
 344                                         ig.Emit (OpCodes.Add_Ovf);
 345                                 else
 346                                         ig.Emit (is_unsigned ? OpCodes.Add_Ovf_Un : OpCodes.Add);
 347                                 break;
 348                         case ExpressionType.Subtract:
 349                                 ig.Emit (OpCodes.Sub);
 350                                 break;
 351                         case ExpressionType.SubtractChecked:
 352                                 if (IsInt32OrInt64 (left.Type))
 353                                         ig.Emit (OpCodes.Sub_Ovf);
 354                                 else
 355                                         ig.Emit (is_unsigned ? OpCodes.Sub_Ovf_Un : OpCodes.Sub);
 356                                 break;
 357                         case ExpressionType.Multiply:
 358                                 ig.Emit (OpCodes.Mul);
 359                                 break;
 360                         case ExpressionType.MultiplyChecked:
 361                                 if (IsInt32OrInt64 (left.Type))
 362                                         ig.Emit (OpCodes.Mul_Ovf);
 363                                 else
 364                                         ig.Emit (is_unsigned ? OpCodes.Mul_Ovf_Un : OpCodes.Mul);
 365                                 break;
 366                         case ExpressionType.Divide:
 367                                 ig.Emit (is_unsigned ? OpCodes.Div_Un : OpCodes.Div);
 368                                 break;
 369                         case ExpressionType.Modulo:
 370                                 ig.Emit (is_unsigned ? OpCodes.Rem_Un : OpCodes.Rem);
 371                                 break;
 372                         case ExpressionType.RightShift:
 373                         case ExpressionType.LeftShift:
 374                                 ig.Emit (OpCodes.Ldc_I4, left.Type == typeof (int) ? 0x1f : 0x3f);
 375                                 ig.Emit (OpCodes.And);
 376                                 if (NodeType == ExpressionType.RightShift)
 377                                         ig.Emit (is_unsigned ? OpCodes.Shr_Un : OpCodes.Shr);
 378                                 else
 379                                         ig.Emit (OpCodes.Shl);
 380                                 break;
 381                         case ExpressionType.And:
 382                                 ig.Emit (OpCodes.And);
 383                                 break;
 384                         case ExpressionType.Or:
 385                                 ig.Emit (OpCodes.Or);
 386                                 break;
 387                         case ExpressionType.ExclusiveOr:
 388                                 ig.Emit (OpCodes.Xor);
 389                                 break;
 390                         case ExpressionType.GreaterThan:
 391                                 ig.Emit (is_unsigned ? OpCodes.Cgt_Un : OpCodes.Cgt);
 392                                 break;
 393                         case ExpressionType.GreaterThanOrEqual:
 394                                 if (is_unsigned || IsSingleOrDouble (left.Type))
 395                                         ig.Emit (OpCodes.Clt_Un);
 396                                 else
 397                                         ig.Emit (OpCodes.Clt);
 398
 399                                 ig.Emit (OpCodes.Ldc_I4_0);
 400                                 ig.Emit (OpCodes.Ceq);
 401                                 break;
 402                         case ExpressionType.LessThan:
 403                                 ig.Emit (is_unsigned ? OpCodes.Clt_Un : OpCodes.Clt);
 404                                 break;
 405                         case ExpressionType.LessThanOrEqual:
 406                                 if (is_unsigned || IsSingleOrDouble (left.Type))
 407                                         ig.Emit (OpCodes.Cgt_Un);
 408                                 else
 409                                         ig.Emit (OpCodes.Cgt);
 410
 411                                 ig.Emit (OpCodes.Ldc_I4_0);
 412                                 ig.Emit (OpCodes.Ceq);
 413                                 break;
 414                         case ExpressionType.Equal:
 415                                 ig.Emit (OpCodes.Ceq);
 416                                 break;
 417                         case ExpressionType.NotEqual:
 418                                 ig.Emit (OpCodes.Ceq);
 419                                 ig.Emit (OpCodes.Ldc_I4_0);
 420                                 ig.Emit (OpCodes.Ceq);
 421                                 break;
 422                         case ExpressionType.Power:
 423                                 ig.Emit (OpCodes.Call, typeof (Math).GetMethod ("Pow"));
 424                                 break;
 425                         default:
 426                                 throw new InvalidOperationException (
 427                                         string.Format ("Internal error: BinaryExpression contains non-Binary nodetype {0}", NodeType));
 428                         }
 429                 }
 430
 431                 bool IsLeftLiftedBinary ()
 432                 {
 433                         return left.Type.IsNullable () && !right.Type.IsNullable ();
 434                 }
 435
 436                 void EmitLeftLiftedToNullBinary (EmitContext ec)
 437                 {
 438                         var ig = ec.ig;
 439
 440                         var ret = ig.DefineLabel ();
 441                         var done = ig.DefineLabel ();
 442
 443                         var left = ec.EmitStored (this.left);
 444
 445                         ec.EmitNullableHasValue (left);
 446                         ig.Emit (OpCodes.Brfalse, ret);
 447
 448                         ec.EmitNullableGetValueOrDefault (left);
 449                         ec.Emit (right);
 450
 451                         EmitBinaryOperator (ec);
 452
 453                         ec.EmitNullableNew (Type);
 454
 455                         ig.Emit (OpCodes.Br, done);
 456
 457                         ig.MarkLabel (ret);
 458
 459                         var temp = ig.DeclareLocal (Type);
 460                         ec.EmitNullableInitialize (temp);
 461
 462                         ig.MarkLabel (done);
 463                 }
 464
 465                 void EmitLiftedArithmeticBinary (EmitContext ec)
 466                 {
 467                         if (IsLeftLiftedBinary ())
 468                                 EmitLeftLiftedToNullBinary (ec);
 469                         else
 470                                 EmitLiftedToNullBinary (ec);
 471                 }
 472
 473                 void EmitLiftedToNullBinary (EmitContext ec)
 474                 {
 475                         var ig = ec.ig;
 476                         var left = ec.EmitStored (this.left);
 477                         var right = ec.EmitStored (this.right);
 478                         var result = ig.DeclareLocal (Type);
 479
 480                         var has_value = ig.DefineLabel ();
 481                         var done = ig.DefineLabel ();
 482
 483                         ec.EmitNullableHasValue (left);
 484                         ec.EmitNullableHasValue (right);
 485                         ig.Emit (OpCodes.And);
 486                         ig.Emit (OpCodes.Brtrue, has_value);
 487
 488                         ec.EmitNullableInitialize (result);
 489
 490                         ig.Emit (OpCodes.Br, done);
 491
 492                         ig.MarkLabel (has_value);
 493
 494                         ec.EmitNullableGetValueOrDefault (left);
 495                         ec.EmitNullableGetValueOrDefault (right);
 496
 497                         EmitBinaryOperator (ec);
 498
 499                         ec.EmitNullableNew (result.LocalType);
 500
 501                         ig.MarkLabel (done);
 502                 }
 503
 504                 void EmitLiftedRelationalBinary (EmitContext ec)
 505                 {
 506                         var ig = ec.ig;
 507                         var left = ec.EmitStored (this.left);
 508                         var right = ec.EmitStored (this.right);
 509
 510                         var ret = ig.DefineLabel ();
 511                         var done = ig.DefineLabel ();
 512
 513                         ec.EmitNullableGetValueOrDefault (left);
 514                         ec.EmitNullableGetValueOrDefault (right);
 515
 516                         switch (NodeType) {
 517                         case ExpressionType.Equal:
 518                         case ExpressionType.NotEqual:
 519                                 ig.Emit (OpCodes.Bne_Un, ret);
 520                                 break;
 521                         default:
 522                                 EmitBinaryOperator (ec);
 523                                 ig.Emit (OpCodes.Brfalse, ret);
 524                                 break;
 525                         }
 526
 527                         ec.EmitNullableHasValue (left);
 528                         ec.EmitNullableHasValue (right);
 529
 530                         switch (NodeType) {
 531                         case ExpressionType.Equal:
 532                                 ig.Emit (OpCodes.Ceq);
 533                                 break;
 534                         case ExpressionType.NotEqual:
 535                                 ig.Emit (OpCodes.Ceq);
 536                                 ig.Emit (OpCodes.Ldc_I4_0);
 537                                 ig.Emit (OpCodes.Ceq);
 538                                 break;
 539                         default:
 540                                 ig.Emit (OpCodes.And);
 541                                 break;
 542                         }
 543
 544                         ig.Emit (OpCodes.Br, done);
 545
 546                         ig.MarkLabel (ret);
 547
 548                         ig.Emit (NodeType == ExpressionType.NotEqual ? OpCodes.Ldc_I4_1 : OpCodes.Ldc_I4_0);
 549
 550                         ig.MarkLabel (done);
 551                 }
 552
 553                 void EmitArithmeticBinary (EmitContext ec)
 554                 {
 555                         if (!IsLifted)
 556                                 EmitNonLiftedBinary (ec);
 557                         else
 558                                 EmitLiftedArithmeticBinary (ec);
 559                 }
 560
 561                 void EmitNonLiftedBinary (EmitContext ec)
 562                 {
 563                         ec.Emit (left);
 564                         ec.Emit (right);
 565                         EmitBinaryOperator (ec);
 566                 }
 567
 568                 void EmitRelationalBinary (EmitContext ec)
 569                 {
 570                         if (!IsLifted)
 571                                 EmitNonLiftedBinary (ec);
 572                         else if (IsLiftedToNull)
 573                                 EmitLiftedToNullBinary (ec);
 574                         else
 575                                 EmitLiftedRelationalBinary (ec);
 576                 }
 577
 578                 void EmitLiftedUserDefinedOperator (EmitContext ec)
 579                 {
 580                         var ig = ec.ig;
 581
 582                         var ret_true = ig.DefineLabel ();
 583                         var ret_false = ig.DefineLabel ();
 584                         var done = ig.DefineLabel ();
 585
 586                         var left = ec.EmitStored (this.left);
 587                         var right = ec.EmitStored (this.right);
 588
 589                         ec.EmitNullableHasValue (left);
 590                         ec.EmitNullableHasValue (right);
 591                         switch (NodeType) {
 592                         case ExpressionType.Equal:
 593                                 ig.Emit (OpCodes.Bne_Un, ret_false);
 594                                 ec.EmitNullableHasValue (left);
 595                                 ig.Emit (OpCodes.Brfalse, ret_true);
 596                                 break;
 597                         case ExpressionType.NotEqual:
 598                                 ig.Emit (OpCodes.Bne_Un, ret_true);
 599                                 ec.EmitNullableHasValue (left);
 600                                 ig.Emit (OpCodes.Brfalse, ret_false);
 601                                 break;
 602                         default:
 603                                 ig.Emit (OpCodes.And);
 604                                 ig.Emit (OpCodes.Brfalse, ret_false);
 605                                 break;
 606                         }
 607
 608                         ec.EmitNullableGetValueOrDefault (left);
 609                         ec.EmitNullableGetValueOrDefault (right);
 610                         ec.EmitCall (method);
 611                         ig.Emit (OpCodes.Br, done);
 612
 613                         ig.MarkLabel (ret_true);
 614                         ig.Emit (OpCodes.Ldc_I4_1);
 615                         ig.Emit (OpCodes.Br, done);
 616
 617                         ig.MarkLabel (ret_false);
 618                         ig.Emit (OpCodes.Ldc_I4_0);
 619                         ig.Emit (OpCodes.Br, done);
 620
 621                         ig.MarkLabel (done);
 622                 }
 623
 624                 void EmitLiftedToNullUserDefinedOperator (EmitContext ec)
 625                 {
 626                         var ig = ec.ig;
 627
 628                         var ret = ig.DefineLabel ();
 629                         var done = ig.DefineLabel ();
 630
 631                         var left = ec.EmitStored (this.left);
 632                         var right = ec.EmitStored (this.right);
 633
 634                         ec.EmitNullableHasValue (left);
 635                         ec.EmitNullableHasValue (right);
 636                         ig.Emit (OpCodes.And);
 637                         ig.Emit (OpCodes.Brfalse, ret);
 638
 639                         ec.EmitNullableGetValueOrDefault (left);
 640                         ec.EmitNullableGetValueOrDefault (right);
 641                         ec.EmitCall (method);
 642                         ec.EmitNullableNew (Type);
 643                         ig.Emit (OpCodes.Br, done);
 644
 645                         ig.MarkLabel (ret);
 646                         var temp = ig.DeclareLocal (Type);
 647                         ec.EmitNullableInitialize (temp);
 648
 649                         ig.MarkLabel (done);
 650                 }
 651
 652                 void EmitUserDefinedLiftedLogicalShortCircuit (EmitContext ec)
 653                 {
 654                         var ig = ec.ig;
 655                         var and = NodeType == ExpressionType.AndAlso;
 656
 657                         var left_is_null = ig.DefineLabel ();
 658                         var ret_left = ig.DefineLabel ();
 659                         var ret_null = ig.DefineLabel ();
 660                         var done = ig.DefineLabel ();
 661
 662                         var left = ec.EmitStored (this.left);
 663
 664                         ec.EmitNullableHasValue (left);
 665                         ig.Emit (OpCodes.Brfalse, and ? ret_null : left_is_null);
 666
 667                         ec.EmitNullableGetValueOrDefault (left);
 668                         ec.EmitCall (and ? GetFalseOperator () : GetTrueOperator ());
 669                         ig.Emit (OpCodes.Brtrue, ret_left);
 670
 671                         ig.MarkLabel (left_is_null);
 672                         var right = ec.EmitStored (this.right);
 673                         ec.EmitNullableHasValue (right);
 674                         ig.Emit (OpCodes.Brfalse, ret_null);
 675
 676                         ec.EmitNullableGetValueOrDefault (left);
 677                         ec.EmitNullableGetValueOrDefault (right);
 678                         ec.EmitCall (method);
 679
 680                         ec.EmitNullableNew (Type);
 681                         ig.Emit (OpCodes.Br, done);
 682
 683                         ig.MarkLabel (ret_left);
 684                         ec.EmitLoad (left);
 685                         ig.Emit (OpCodes.Br, done);
 686
 687                         ig.MarkLabel (ret_null);
 688                         var ret = ig.DeclareLocal (Type);
 689                         ec.EmitNullableInitialize (ret);
 690
 691                         ig.MarkLabel (done);
 692                 }
 693
 694                 void EmitUserDefinedOperator (EmitContext ec)
 695                 {
 696                         if (!IsLifted) {
 697                                 switch (NodeType) {
 698                                 case ExpressionType.AndAlso:
 699                                 case ExpressionType.OrElse:
 700                                         EmitUserDefinedLogicalShortCircuit (ec);
 701                                         break;
 702                                 default:
 703                                         left.Emit (ec);
 704                                         right.Emit (ec);
 705                                         ec.EmitCall (method);
 706                                         break;
 707                                 }
 708                         } else if (IsLiftedToNull) {
 709                                 switch (NodeType) {
 710                                 case ExpressionType.AndAlso:
 711                                 case ExpressionType.OrElse:
 712                                         EmitUserDefinedLiftedLogicalShortCircuit (ec);
 713                                         break;
 714                                 default:
 715                                         EmitLiftedToNullUserDefinedOperator (ec);
 716                                         break;
 717                                 }
 718                         }  else
 719                                 EmitLiftedUserDefinedOperator (ec);
 720                 }
 721
 722                 internal override void Emit (EmitContext ec)
 723                 {
 724                         if (method != null) {
 725                                 EmitUserDefinedOperator (ec);
 726                                 return;
 727                         }
 728
 729                         switch (NodeType){
 730                         case ExpressionType.ArrayIndex:
 731                                 EmitArrayAccess (ec);
 732                                 return;
 733                         case ExpressionType.Coalesce:
 734                                 if (conversion != null)
 735                                         EmitConvertedCoalesce (ec);
 736                                 else
 737                                         EmitCoalesce (ec);
 738                                 return;
 739                         case ExpressionType.Power:
 740                         case ExpressionType.Add:
 741                         case ExpressionType.AddChecked:
 742                         case ExpressionType.Divide:
 743                         case ExpressionType.ExclusiveOr:
 744                         case ExpressionType.LeftShift:
 745                         case ExpressionType.Modulo:
 746                         case ExpressionType.Multiply:
 747                         case ExpressionType.MultiplyChecked:
 748                         case ExpressionType.RightShift:
 749                         case ExpressionType.Subtract:
 750                         case ExpressionType.SubtractChecked:
 751                                 EmitArithmeticBinary (ec);
 752                                 return;
 753                         case ExpressionType.Equal:
 754                         case ExpressionType.GreaterThan:
 755                         case ExpressionType.GreaterThanOrEqual:
 756                         case ExpressionType.LessThan:
 757                         case ExpressionType.LessThanOrEqual:
 758                         case ExpressionType.NotEqual:
 759                                 EmitRelationalBinary (ec);
 760                                 return;
 761                         case ExpressionType.And:
 762                         case ExpressionType.Or:
 763                         case ExpressionType.AndAlso:
 764                         case ExpressionType.OrElse:
 765                                 EmitLogicalBinary (ec);
 766                                 return;
 767                         default:
 768                                 throw new NotSupportedException (this.NodeType.ToString ());
 769                         }
 770                 }
 771         }
 772 }