**** Merged r40457-r40460 from MCS ****
[mono.git] / mcs / gmcs / codegen.cs
1 //
2 // codegen.cs: The code generator
3 //
4 // Author:
5 //   Miguel de Icaza (miguel@ximian.com)
6 //
7 // (C) 2001, 2002, 2003 Ximian, Inc.
8 // (C) 2004 Novell, Inc.
9 //
10 //#define PRODUCTION
11 using System;
12 using System.IO;
13 using System.Collections;
14 using System.Collections.Specialized;
15 using System.Reflection;
16 using System.Reflection.Emit;
17 using System.Runtime.InteropServices;
18 using System.Security;
19 using System.Security.Cryptography;
20 using System.Security.Permissions;
21
22 using Mono.Security.Cryptography;
23
24 namespace Mono.CSharp {
25
26         /// <summary>
27         ///    Code generator class.
28         /// </summary>
29         public class CodeGen {
30                 static AppDomain current_domain;
31                 static public SymbolWriter SymbolWriter;
32
33                 public static AssemblyClass Assembly;
34                 public static ModuleClass Module;
35
36                 static CodeGen ()
37                 {
38                         Assembly = new AssemblyClass ();
39                         Module = new ModuleClass (RootContext.Unsafe);
40                 }
41
42                 public static string Basename (string name)
43                 {
44                         int pos = name.LastIndexOf ('/');
45
46                         if (pos != -1)
47                                 return name.Substring (pos + 1);
48
49                         pos = name.LastIndexOf ('\\');
50                         if (pos != -1)
51                                 return name.Substring (pos + 1);
52
53                         return name;
54                 }
55
56                 public static string Dirname (string name)
57                 {
58                         int pos = name.LastIndexOf ('/');
59
60                         if (pos != -1)
61                                 return name.Substring (0, pos);
62
63                         pos = name.LastIndexOf ('\\');
64                         if (pos != -1)
65                                 return name.Substring (0, pos);
66
67                         return ".";
68                 }
69
70                 static string TrimExt (string name)
71                 {
72                         int pos = name.LastIndexOf ('.');
73
74                         return name.Substring (0, pos);
75                 }
76
77                 static public string FileName;
78
79                 //
80                 // Initializes the symbol writer
81                 //
82                 static void InitializeSymbolWriter (string filename)
83                 {
84                         SymbolWriter = SymbolWriter.GetSymbolWriter (Module.Builder, filename);
85
86                         //
87                         // If we got an ISymbolWriter instance, initialize it.
88                         //
89                         if (SymbolWriter == null) {
90                                 Report.Warning (
91                                         -18, "Could not find the symbol writer assembly (Mono.CompilerServices.SymbolWriter.dll). This is normally an installation problem. Please make sure to compile and install the mcs/class/Mono.CompilerServices.SymbolWriter directory.");
92                                 return;
93                         }
94                 }
95
96                 //
97                 // Initializes the code generator variables
98                 //
99                 static public void Init (string name, string output, bool want_debugging_support)
100                 {
101                         FileName = output;
102                         AssemblyName an = Assembly.GetAssemblyName (name, output);
103
104                         if (an.KeyPair != null) {
105                                 // If we are going to strong name our assembly make
106                                 // sure all its refs are strong named
107                                 foreach (Assembly a in TypeManager.GetAssemblies ()) {
108                                         AssemblyName ref_name = a.GetName ();
109                                         byte [] b = ref_name.GetPublicKeyToken ();
110                                         if (b == null || b.Length == 0) {
111                                                 Report.Warning (1577, "Assembly generation failed " +
112                                                                 "-- Referenced assembly '" +
113                                                                 ref_name.Name +
114                                                                 "' does not have a strong name.");
115                                                 //Environment.Exit (1);
116                                         }
117                                 }
118                         }
119                         
120                         current_domain = AppDomain.CurrentDomain;
121
122                         try {
123                                 Assembly.Builder = current_domain.DefineDynamicAssembly (an,
124                                         AssemblyBuilderAccess.Save, Dirname (name));
125                         }
126                         catch (ArgumentException) {
127                                 // specified key may not be exportable outside it's container
128                                 if (RootContext.StrongNameKeyContainer != null) {
129                                         Report.Error (1548, "Could not access the key inside the container `" +
130                                                 RootContext.StrongNameKeyContainer + "'.");
131                                         Environment.Exit (1);
132                                 }
133                                 throw;
134                         }
135                         catch (CryptographicException) {
136                                 if ((RootContext.StrongNameKeyContainer != null) || (RootContext.StrongNameKeyFile != null)) {
137                                         Report.Error (1548, "Could not use the specified key to strongname the assembly.");
138                                         Environment.Exit (1);
139                                 }
140                                 throw;
141                         }
142
143                         //
144                         // Pass a path-less name to DefineDynamicModule.  Wonder how
145                         // this copes with output in different directories then.
146                         // FIXME: figure out how this copes with --output /tmp/blah
147                         //
148                         // If the third argument is true, the ModuleBuilder will dynamically
149                         // load the default symbol writer.
150                         //
151                         Module.Builder = Assembly.Builder.DefineDynamicModule (
152                                 Basename (name), Basename (output), false);
153
154                         if (want_debugging_support)
155                                 InitializeSymbolWriter (output);
156                 }
157
158                 static public void Save (string name)
159                 {
160                         try {
161                                 Assembly.Builder.Save (Basename (name));
162                         }
163                         catch (COMException) {
164                                 if ((RootContext.StrongNameKeyFile == null) || (!RootContext.StrongNameDelaySign))
165                                         throw;
166
167                                 // FIXME: it seems Microsoft AssemblyBuilder doesn't like to delay sign assemblies 
168                                 Report.Error (1548, "Couldn't delay-sign the assembly with the '" +
169                                         RootContext.StrongNameKeyFile +
170                                         "', Use MCS with the Mono runtime or CSC to compile this assembly.");
171                         }
172                         catch (System.IO.IOException io) {
173                                 Report.Error (16, "Could not write to file `"+name+"', cause: " + io.Message);
174                         }
175
176                         if (SymbolWriter != null)
177                                 SymbolWriter.WriteSymbolFile ();
178                 }
179         }
180
181         //
182         // Provides "local" store across code that can yield: locals
183         // or fields, notice that this should not be used by anonymous
184         // methods to create local storage, those only require
185         // variable mapping.
186         //
187         public class VariableStorage {
188                 FieldBuilder fb;
189                 LocalBuilder local;
190                 
191                 static int count;
192                 
193                 public VariableStorage (EmitContext ec, Type t)
194                 {
195                         count++;
196                         if (ec.InIterator)
197                                 fb = ec.CurrentIterator.MapVariable ("s_", count.ToString (), t);
198                         else
199                                 local = ec.ig.DeclareLocal (t);
200                 }
201
202                 public void EmitThis (ILGenerator ig)
203                 {
204                         if (fb != null)
205                                 ig.Emit (OpCodes.Ldarg_0);
206                 }
207
208                 public void EmitStore (ILGenerator ig)
209                 {
210                         if (fb == null)
211                                 ig.Emit (OpCodes.Stloc, local);
212                         else
213                                 ig.Emit (OpCodes.Stfld, fb);
214                 }
215
216                 public void EmitLoad (ILGenerator ig)
217                 {
218                         if (fb == null)
219                                 ig.Emit (OpCodes.Ldloc, local);
220                         else 
221                                 ig.Emit (OpCodes.Ldfld, fb);
222                 }
223
224                 public void EmitLoadAddress (ILGenerator ig)
225                 {
226                         if (fb == null)
227                                 ig.Emit (OpCodes.Ldloca, local);
228                         else 
229                                 ig.Emit (OpCodes.Ldflda, fb);
230                 }
231                 
232                 public void EmitCall (ILGenerator ig, MethodInfo mi)
233                 {
234                         // FIXME : we should handle a call like tostring
235                         // here, where boxing is needed. However, we will
236                         // never encounter that with the current usage.
237                         
238                         bool value_type_call;
239                         EmitThis (ig);
240                         if (fb == null) {
241                                 value_type_call = local.LocalType.IsValueType;
242                                 
243                                 if (value_type_call)
244                                         ig.Emit (OpCodes.Ldloca, local);
245                                 else
246                                         ig.Emit (OpCodes.Ldloc, local);
247                         } else {
248                                 value_type_call = fb.FieldType.IsValueType;
249                                 
250                                 if (value_type_call)
251                                         ig.Emit (OpCodes.Ldflda, fb);
252                                 else
253                                         ig.Emit (OpCodes.Ldfld, fb);
254                         }
255                         
256                         ig.Emit (value_type_call ? OpCodes.Call : OpCodes.Callvirt, mi);
257                 }
258         }
259         
260         /// <summary>
261         ///   An Emit Context is created for each body of code (from methods,
262         ///   properties bodies, indexer bodies or constructor bodies)
263         /// </summary>
264         public class EmitContext {
265                 public DeclSpace DeclSpace;
266                 public DeclSpace TypeContainer;
267                 public ILGenerator   ig;
268
269                 /// <summary>
270                 ///   This variable tracks the `checked' state of the compilation,
271                 ///   it controls whether we should generate code that does overflow
272                 ///   checking, or if we generate code that ignores overflows.
273                 ///
274                 ///   The default setting comes from the command line option to generate
275                 ///   checked or unchecked code plus any source code changes using the
276                 ///   checked/unchecked statements or expressions.   Contrast this with
277                 ///   the ConstantCheckState flag.
278                 /// </summary>
279                 
280                 public bool CheckState;
281
282                 /// <summary>
283                 ///   The constant check state is always set to `true' and cant be changed
284                 ///   from the command line.  The source code can change this setting with
285                 ///   the `checked' and `unchecked' statements and expressions. 
286                 /// </summary>
287                 public bool ConstantCheckState;
288
289                 /// <summary>
290                 ///   Whether we are emitting code inside a static or instance method
291                 /// </summary>
292                 public bool IsStatic;
293
294                 /// <summary>
295                 ///   Whether we are emitting a field initializer
296                 /// </summary>
297                 public bool IsFieldInitializer;
298
299                 /// <summary>
300                 ///   The value that is allowed to be returned or NULL if there is no
301                 ///   return type.
302                 /// </summary>
303                 public Type ReturnType;
304
305                 /// <summary>
306                 ///   Points to the Type (extracted from the TypeContainer) that
307                 ///   declares this body of code
308                 /// </summary>
309                 public Type ContainerType;
310                 
311                 /// <summary>
312                 ///   Whether this is generating code for a constructor
313                 /// </summary>
314                 public bool IsConstructor;
315
316                 /// <summary>
317                 ///   Whether we're control flow analysis enabled
318                 /// </summary>
319                 public bool DoFlowAnalysis;
320                 
321                 /// <summary>
322                 ///   Keeps track of the Type to LocalBuilder temporary storage created
323                 ///   to store structures (used to compute the address of the structure
324                 ///   value on structure method invocations)
325                 /// </summary>
326                 public Hashtable temporary_storage;
327
328                 public Block CurrentBlock;
329
330                 public int CurrentFile;
331
332                 /// <summary>
333                 ///   The location where we store the return value.
334                 /// </summary>
335                 LocalBuilder return_value;
336
337                 /// <summary>
338                 ///   The location where return has to jump to return the
339                 ///   value
340                 /// </summary>
341                 public Label ReturnLabel;
342
343                 /// <summary>
344                 ///   If we already defined the ReturnLabel
345                 /// </summary>
346                 public bool HasReturnLabel;
347
348                 /// <summary>
349                 ///   Whether we are inside an iterator block.
350                 /// </summary>
351                 public bool InIterator;
352
353                 public bool IsLastStatement;
354                 
355                 /// <summary>
356                 ///   Whether remapping of locals, parameters and fields is turned on.
357                 ///   Used by iterators and anonymous methods.
358                 /// </summary>
359                 public bool RemapToProxy;
360
361                 /// <summary>
362                 ///  Whether we are inside an unsafe block
363                 /// </summary>
364                 public bool InUnsafe;
365
366                 /// <summary>
367                 ///  Whether we are in a `fixed' initialization
368                 /// </summary>
369                 public bool InFixedInitializer;
370
371                 /// <summary>
372                 ///  Whether we are inside an anonymous method.
373                 /// </summary>
374                 public AnonymousMethod CurrentAnonymousMethod;
375                 
376                 /// <summary>
377                 ///   Location for this EmitContext
378                 /// </summary>
379                 public Location loc;
380
381                 /// <summary>
382                 ///   Used to flag that it is ok to define types recursively, as the
383                 ///   expressions are being evaluated as part of the type lookup
384                 ///   during the type resolution process
385                 /// </summary>
386                 public bool ResolvingTypeTree;
387                 
388                 /// <summary>
389                 ///   Inside an enum definition, we do not resolve enumeration values
390                 ///   to their enumerations, but rather to the underlying type/value
391                 ///   This is so EnumVal + EnumValB can be evaluated.
392                 ///
393                 ///   There is no "E operator + (E x, E y)", so during an enum evaluation
394                 ///   we relax the rules
395                 /// </summary>
396                 public bool InEnumContext;
397
398                 /// <summary>
399                 ///   Anonymous methods can capture local variables and fields,
400                 ///   this object tracks it.  It is copied from the TopLevelBlock
401                 ///   field.
402                 /// </summary>
403                 public CaptureContext capture_context;
404
405                 /// <summary>
406                 /// Trace when method is called and is obsolete then this member suppress message
407                 /// when call is inside next [Obsolete] method or type.
408                 /// </summary>
409                 public bool TestObsoleteMethodUsage = true;
410
411                 /// <summary>
412                 ///    The current iterator
413                 /// </summary>
414                 public Iterator CurrentIterator;
415
416                 /// <summary>
417                 ///    Whether we are in the resolving stage or not
418                 /// </summary>
419                 enum Phase {
420                         Created,
421                         Resolving,
422                         Emitting
423                 }
424                 
425                 Phase current_phase;
426                 
427                 FlowBranching current_flow_branching;
428                 
429                 public EmitContext (DeclSpace parent, DeclSpace ds, Location l, ILGenerator ig,
430                                     Type return_type, int code_flags, bool is_constructor)
431                 {
432                         this.ig = ig;
433
434                         TypeContainer = parent;
435                         DeclSpace = ds;
436                         CheckState = RootContext.Checked;
437                         ConstantCheckState = true;
438
439                         if ((return_type is TypeBuilder) && return_type.IsGenericTypeDefinition)
440                                 throw new Exception ("FUCK");
441                         
442                         IsStatic = (code_flags & Modifiers.STATIC) != 0;
443                         InIterator = (code_flags & Modifiers.METHOD_YIELDS) != 0;
444                         RemapToProxy = InIterator;
445                         ReturnType = return_type;
446                         IsConstructor = is_constructor;
447                         CurrentBlock = null;
448                         CurrentFile = 0;
449                         current_phase = Phase.Created;
450                         
451                         if (parent != null){
452                                 // Can only be null for the ResolveType contexts.
453                                 ContainerType = parent.TypeBuilder;
454                                 if (parent.UnsafeContext)
455                                         InUnsafe = true;
456                                 else
457                                         InUnsafe = (code_flags & Modifiers.UNSAFE) != 0;
458                         }
459                         loc = l;
460
461                         if (ReturnType == TypeManager.void_type)
462                                 ReturnType = null;
463                 }
464
465                 public EmitContext (TypeContainer tc, Location l, ILGenerator ig,
466                                     Type return_type, int code_flags, bool is_constructor)
467                         : this (tc, tc, l, ig, return_type, code_flags, is_constructor)
468                 {
469                 }
470
471                 public EmitContext (TypeContainer tc, Location l, ILGenerator ig,
472                                     Type return_type, int code_flags)
473                         : this (tc, tc, l, ig, return_type, code_flags, false)
474                 {
475                 }
476
477                 public FlowBranching CurrentBranching {
478                         get {
479                                 return current_flow_branching;
480                         }
481                 }
482
483                 public bool HaveCaptureInfo {
484                         get {
485                                 return capture_context != null;
486                         }
487                 }
488
489                 // <summary>
490                 //   Starts a new code branching.  This inherits the state of all local
491                 //   variables and parameters from the current branching.
492                 // </summary>
493                 public FlowBranching StartFlowBranching (FlowBranching.BranchingType type, Location loc)
494                 {
495                         current_flow_branching = FlowBranching.CreateBranching (CurrentBranching, type, null, loc);
496                         return current_flow_branching;
497                 }
498
499                 // <summary>
500                 //   Starts a new code branching for block `block'.
501                 // </summary>
502                 public FlowBranching StartFlowBranching (Block block)
503                 {
504                         FlowBranching.BranchingType type;
505
506                         if (CurrentBranching.Type == FlowBranching.BranchingType.Switch)
507                                 type = FlowBranching.BranchingType.SwitchSection;
508                         else
509                                 type = FlowBranching.BranchingType.Block;
510
511                         current_flow_branching = FlowBranching.CreateBranching (CurrentBranching, type, block, block.StartLocation);
512                         return current_flow_branching;
513                 }
514
515                 public FlowBranchingException StartFlowBranching (ExceptionStatement stmt)
516                 {
517                         FlowBranchingException branching = new FlowBranchingException (
518                                 CurrentBranching, stmt);
519                         current_flow_branching = branching;
520                         return branching;
521                 }
522
523                 // <summary>
524                 //   Ends a code branching.  Merges the state of locals and parameters
525                 //   from all the children of the ending branching.
526                 // </summary>
527                 public FlowBranching.UsageVector DoEndFlowBranching ()
528                 {
529                         FlowBranching old = current_flow_branching;
530                         current_flow_branching = current_flow_branching.Parent;
531
532                         return current_flow_branching.MergeChild (old);
533                 }
534
535                 // <summary>
536                 //   Ends a code branching.  Merges the state of locals and parameters
537                 //   from all the children of the ending branching.
538                 // </summary>
539                 public FlowBranching.Reachability EndFlowBranching ()
540                 {
541                         FlowBranching.UsageVector vector = DoEndFlowBranching ();
542
543                         return vector.Reachability;
544                 }
545
546                 // <summary>
547                 //   Kills the current code branching.  This throws away any changed state
548                 //   information and should only be used in case of an error.
549                 // </summary>
550                 public void KillFlowBranching ()
551                 {
552                         current_flow_branching = current_flow_branching.Parent;
553                 }
554
555                 public void CaptureVariable (LocalInfo li)
556                 {
557                         capture_context.AddLocal (CurrentAnonymousMethod, li);
558                         li.IsCaptured = true;
559                 }
560
561                 public void CaptureParameter (string name, Type t, int idx)
562                 {
563                         capture_context.AddParameter (this, CurrentAnonymousMethod, name, t, idx);
564                 }
565
566                 public void CaptureThis ()
567                 {
568                         capture_context.CaptureThis ();
569                 }
570                 
571                 
572                 //
573                 // Use to register a field as captured
574                 //
575                 public void CaptureField (FieldExpr fe)
576                 {
577                         capture_context.AddField (fe);
578                 }
579
580                 //
581                 // Whether anonymous methods have captured variables
582                 //
583                 public bool HaveCapturedVariables ()
584                 {
585                         if (capture_context != null)
586                                 return capture_context.HaveCapturedVariables;
587                         return false;
588                 }
589
590                 //
591                 // Whether anonymous methods have captured fields or this.
592                 //
593                 public bool HaveCapturedFields ()
594                 {
595                         if (capture_context != null)
596                                 return capture_context.HaveCapturedFields;
597                         return false;
598                 }
599
600                 //
601                 // Emits the instance pointer for the host method
602                 //
603                 public void EmitMethodHostInstance (EmitContext target, AnonymousMethod am)
604                 {
605                         if (capture_context != null)
606                                 capture_context.EmitMethodHostInstance (target, am);
607                         else if (IsStatic)
608                                 target.ig.Emit (OpCodes.Ldnull);
609                         else
610                                 target.ig.Emit (OpCodes.Ldarg_0);
611                 }
612
613                 //
614                 // Returns whether the `local' variable has been captured by an anonymous
615                 // method
616                 //
617                 public bool IsCaptured (LocalInfo local)
618                 {
619                         return capture_context.IsCaptured (local);
620                 }
621
622                 public bool IsParameterCaptured (string name)
623                 {
624                         if (capture_context != null)
625                                 return capture_context.IsParameterCaptured (name);
626                         return false;
627                 }
628                 
629                 public void EmitMeta (ToplevelBlock b, InternalParameters ip)
630                 {
631                         if (capture_context != null)
632                                 capture_context.EmitAnonymousHelperClasses (this);
633                         b.EmitMeta (this);
634
635                         if (HasReturnLabel)
636                                 ReturnLabel = ig.DefineLabel ();
637                 }
638
639                 //
640                 // Here until we can fix the problem with Mono.CSharp.Switch, which
641                 // currently can not cope with ig == null during resolve (which must
642                 // be fixed for switch statements to work on anonymous methods).
643                 //
644                 public void EmitTopBlock (ToplevelBlock block, InternalParameters ip, Location loc)
645                 {
646                         if (block == null)
647                                 return;
648                         
649                         bool unreachable;
650                         
651                         if (ResolveTopBlock (null, block, ip, loc, out unreachable)){
652                                 EmitMeta (block, ip);
653
654                                 current_phase = Phase.Emitting;
655                                 EmitResolvedTopBlock (block, unreachable);
656                         }
657                 }
658
659                 public bool ResolveTopBlock (EmitContext anonymous_method_host, ToplevelBlock block,
660                                              InternalParameters ip, Location loc, out bool unreachable)
661                 {
662                         current_phase = Phase.Resolving;
663                         
664                         unreachable = false;
665
666                         capture_context = block.CaptureContext;
667
668                         if (!Location.IsNull (loc))
669                                 CurrentFile = loc.File;
670
671 #if PRODUCTION
672                             try {
673 #endif
674                                 int errors = Report.Errors;
675
676                                 block.ResolveMeta (block, this, ip);
677
678
679                                 if (Report.Errors == errors){
680                                         bool old_do_flow_analysis = DoFlowAnalysis;
681                                         DoFlowAnalysis = true;
682
683                                         if (anonymous_method_host != null)
684                                                 current_flow_branching = FlowBranching.CreateBranching (
685                                                 anonymous_method_host.CurrentBranching, FlowBranching.BranchingType.Block,
686                                                 block, loc);
687                                         else 
688                                         current_flow_branching = FlowBranching.CreateBranching (
689                                                 null, FlowBranching.BranchingType.Block, block, loc);
690
691                                         if (!block.Resolve (this)) {
692                                                 current_flow_branching = null;
693                                                 DoFlowAnalysis = old_do_flow_analysis;
694                                                 return false;
695                                         }
696
697                                         FlowBranching.Reachability reachability = current_flow_branching.MergeTopBlock ();
698                                         current_flow_branching = null;
699
700                                         DoFlowAnalysis = old_do_flow_analysis;
701
702                                         if (reachability.AlwaysReturns ||
703                                             reachability.AlwaysThrows ||
704                                             reachability.IsUnreachable)
705                                                 unreachable = true;
706                                         }
707 #if PRODUCTION
708                             } catch (Exception e) {
709                                         Console.WriteLine ("Exception caught by the compiler while compiling:");
710                                         Console.WriteLine ("   Block that caused the problem begin at: " + loc);
711                                         
712                                         if (CurrentBlock != null){
713                                                 Console.WriteLine ("                     Block being compiled: [{0},{1}]",
714                                                                    CurrentBlock.StartLocation, CurrentBlock.EndLocation);
715                                         }
716                                         Console.WriteLine (e.GetType ().FullName + ": " + e.Message);
717                                 throw;
718                         }
719 #endif
720
721                         if (ReturnType != null && !unreachable){
722                                 if (!InIterator){
723                                         if (CurrentAnonymousMethod != null){
724                                                 Report.Error (1643, loc, "Not all code paths return a value in anonymous method of type `{0}'",
725                                                               CurrentAnonymousMethod.Type);
726                                         } else {
727                                         Report.Error (161, loc, "Not all code paths return a value");
728                                         }
729
730                                         return false;
731                                 }
732                         }
733                         block.CompleteContexts ();
734
735                         return true;
736                 }
737
738                 public void EmitResolvedTopBlock (ToplevelBlock block, bool unreachable)
739                 {
740                         if (block != null)
741                                 block.Emit (this);
742
743                         if (HasReturnLabel)
744                                 ig.MarkLabel (ReturnLabel);
745
746                         if (return_value != null){
747                                 ig.Emit (OpCodes.Ldloc, return_value);
748                                 ig.Emit (OpCodes.Ret);
749                         } else {
750                                 //
751                                 // If `HasReturnLabel' is set, then we already emitted a
752                                 // jump to the end of the method, so we must emit a `ret'
753                                 // there.
754                                 //
755                                 // Unfortunately, System.Reflection.Emit automatically emits
756                                 // a leave to the end of a finally block.  This is a problem
757                                 // if no code is following the try/finally block since we may
758                                 // jump to a point after the end of the method.
759                                 // As a workaround, we're always creating a return label in
760                                 // this case.
761                                 //
762
763                                 if ((block != null) && block.IsDestructor) {
764                                         // Nothing to do; S.R.E automatically emits a leave.
765                                 } else if (HasReturnLabel || (!unreachable && !InIterator)) {
766                                         if (ReturnType != null)
767                                                 ig.Emit (OpCodes.Ldloc, TemporaryReturn ());
768                                         ig.Emit (OpCodes.Ret);
769                                 }
770                         }
771
772                         //
773                         // Close pending helper classes if we are the toplevel
774                         //
775                         if (capture_context != null && capture_context.ParentToplevel == null)
776                                 capture_context.CloseAnonymousHelperClasses ();
777                 }
778
779                 /// <summary>
780                 ///   This is called immediately before emitting an IL opcode to tell the symbol
781                 ///   writer to which source line this opcode belongs.
782                 /// </summary>
783                 public void Mark (Location loc, bool check_file)
784                 {
785                         if ((CodeGen.SymbolWriter == null) || Location.IsNull (loc))
786                                 return;
787
788                         if (check_file && (CurrentFile != loc.File))
789                                 return;
790
791                         CodeGen.SymbolWriter.MarkSequencePoint (ig, loc.Row, 0);
792                 }
793
794                 public void DefineLocalVariable (string name, LocalBuilder builder)
795                 {
796                         if (CodeGen.SymbolWriter == null)
797                                 return;
798
799                         CodeGen.SymbolWriter.DefineLocalVariable (name, builder);
800                 }
801
802                 /// <summary>
803                 ///   Returns a temporary storage for a variable of type t as 
804                 ///   a local variable in the current body.
805                 /// </summary>
806                 public LocalBuilder GetTemporaryLocal (Type t)
807                 {
808                         LocalBuilder location = null;
809                         
810                         if (temporary_storage != null){
811                                 object o = temporary_storage [t];
812                                 if (o != null){
813                                         if (o is ArrayList){
814                                                 ArrayList al = (ArrayList) o;
815                                                 
816                                                 for (int i = 0; i < al.Count; i++){
817                                                         if (al [i] != null){
818                                                                 location = (LocalBuilder) al [i];
819                                                                 al [i] = null;
820                                                                 break;
821                                                         }
822                                                 }
823                                         } else
824                                                 location = (LocalBuilder) o;
825                                         if (location != null)
826                                                 return location;
827                                 }
828                         }
829                         
830                         return ig.DeclareLocal (t);
831                 }
832
833                 public void FreeTemporaryLocal (LocalBuilder b, Type t)
834                 {
835                         if (temporary_storage == null){
836                                 temporary_storage = new Hashtable ();
837                                 temporary_storage [t] = b;
838                                 return;
839                         }
840                         object o = temporary_storage [t];
841                         if (o == null){
842                                 temporary_storage [t] = b;
843                                 return;
844                         }
845                         if (o is ArrayList){
846                                 ArrayList al = (ArrayList) o;
847                                 for (int i = 0; i < al.Count; i++){
848                                         if (al [i] == null){
849                                                 al [i] = b;
850                                                 return;
851                                         }
852                                 }
853                                 al.Add (b);
854                                 return;
855                         }
856                         ArrayList replacement = new ArrayList ();
857                         replacement.Add (o);
858                         temporary_storage.Remove (t);
859                         temporary_storage [t] = replacement;
860                 }
861
862                 /// <summary>
863                 ///   Current loop begin and end labels.
864                 /// </summary>
865                 public Label LoopBegin, LoopEnd;
866
867                 /// <summary>
868                 ///   Default target in a switch statement.   Only valid if
869                 ///   InSwitch is true
870                 /// </summary>
871                 public Label DefaultTarget;
872
873                 /// <summary>
874                 ///   If this is non-null, points to the current switch statement
875                 /// </summary>
876                 public Switch Switch;
877
878                 /// <summary>
879                 ///   ReturnValue creates on demand the LocalBuilder for the
880                 ///   return value from the function.  By default this is not
881                 ///   used.  This is only required when returns are found inside
882                 ///   Try or Catch statements.
883                 ///
884                 ///   This method is typically invoked from the Emit phase, so
885                 ///   we allow the creation of a return label if it was not
886                 ///   requested during the resolution phase.   Could be cleaned
887                 ///   up, but it would replicate a lot of logic in the Emit phase
888                 ///   of the code that uses it.
889                 /// </summary>
890                 public LocalBuilder TemporaryReturn ()
891                 {
892                         if (return_value == null){
893                                 return_value = ig.DeclareLocal (ReturnType);
894                                 if (!HasReturnLabel){
895                                 ReturnLabel = ig.DefineLabel ();
896                                 HasReturnLabel = true;
897                         }
898                         }
899
900                         return return_value;
901                 }
902
903                 /// <summary>
904                 ///   This method is used during the Resolution phase to flag the
905                 ///   need to define the ReturnLabel
906                 /// </summary>
907                 public void NeedReturnLabel ()
908                 {
909                         if (current_phase != Phase.Resolving){
910                                 //
911                                 // The reason is that the `ReturnLabel' is declared between
912                                 // resolution and emission
913                                 // 
914                                 throw new Exception ("NeedReturnLabel called from Emit phase, should only be called during Resolve");
915                         }
916                         
917                         if (!InIterator && !HasReturnLabel) 
918                                 HasReturnLabel = true;
919                         }
920
921                 //
922                 // Creates a field `name' with the type `t' on the proxy class
923                 //
924                 public FieldBuilder MapVariable (string name, Type t)
925                 {
926                         if (InIterator)
927                                 return CurrentIterator.MapVariable ("v_", name, t);
928
929                         throw new Exception ("MapVariable for an unknown state");
930                 }
931
932                 public Expression RemapParameter (int idx)
933                 {
934                         FieldExpr fe = new FieldExprNoAddress (CurrentIterator.parameter_fields [idx].FieldBuilder, loc);
935                         fe.InstanceExpression = new ProxyInstance ();
936                         return fe.DoResolve (this);
937                 }
938
939                 public Expression RemapParameterLValue (int idx, Expression right_side)
940                 {
941                         FieldExpr fe = new FieldExprNoAddress (CurrentIterator.parameter_fields [idx].FieldBuilder, loc);
942                         fe.InstanceExpression = new ProxyInstance ();
943                         return fe.DoResolveLValue (this, right_side);
944                 }
945                 
946                 //
947                 // Emits the proper object to address fields on a remapped
948                 // variable/parameter to field in anonymous-method/iterator proxy classes.
949                 //
950                 public void EmitThis ()
951                 {
952                         ig.Emit (OpCodes.Ldarg_0);
953                         if (InIterator){
954                                 if (!IsStatic){
955                                 FieldBuilder this_field = CurrentIterator.this_field.FieldBuilder;
956                                 if (TypeManager.IsValueType (this_field.FieldType))
957                                         ig.Emit (OpCodes.Ldflda, this_field);
958                                 else
959                                         ig.Emit (OpCodes.Ldfld, this_field);
960                         }
961                         } else if (capture_context != null && CurrentAnonymousMethod != null){
962                                 ScopeInfo si = CurrentAnonymousMethod.Scope;
963                                 while (si != null){
964                                         if (si.ParentLink != null)
965                                                 ig.Emit (OpCodes.Ldfld, si.ParentLink);
966                                         if (si.THIS != null){
967                                                 ig.Emit (OpCodes.Ldfld, si.THIS);
968                                                 break;
969                                         }
970                                         si = si.ParentScope;
971                                 }
972                         } 
973                 }
974
975                 //
976                 // Emits the code necessary to load the instance required
977                 // to access the captured LocalInfo
978                 //
979                 public void EmitCapturedVariableInstance (LocalInfo li)
980                 {
981                         if (RemapToProxy){
982                                 ig.Emit (OpCodes.Ldarg_0);
983                                 return;
984                         }
985                         
986                         if (capture_context == null)
987                                 throw new Exception ("Calling EmitCapturedContext when there is no capture_context");
988                         
989                         capture_context.EmitCapturedVariableInstance (this, li, CurrentAnonymousMethod);
990                 }
991
992                 public void EmitParameter (string name)
993                 {
994                         capture_context.EmitParameter (this, name);
995                 }
996
997                 public void EmitAssignParameter (string name, Expression source, bool leave_copy, bool prepare_for_load)
998                 {
999                         capture_context.EmitAssignParameter (this, name, source, leave_copy, prepare_for_load);
1000                 }
1001
1002                 public void EmitAddressOfParameter (string name)
1003                 {
1004                         capture_context.EmitAddressOfParameter (this, name);
1005                 }
1006
1007                 public Expression GetThis (Location loc)
1008                 {
1009                         This my_this;
1010                         if (CurrentBlock != null)
1011                                 my_this = new This (CurrentBlock, loc);
1012                         else
1013                                 my_this = new This (loc);
1014
1015                         if (!my_this.ResolveBase (this))
1016                                 my_this = null;
1017
1018                         return my_this;
1019                 }
1020         }
1021
1022
1023         public abstract class CommonAssemblyModulClass: Attributable {
1024                 protected CommonAssemblyModulClass ():
1025                         base (null)
1026                 {
1027                 }
1028
1029                 public void AddAttributes (ArrayList attrs)
1030                 {
1031                         if (OptAttributes == null) {
1032                                 OptAttributes = new Attributes (attrs);
1033                                 return;
1034                         }
1035                         OptAttributes.AddAttributes (attrs);
1036                 }
1037
1038                 public virtual void Emit (TypeContainer tc) 
1039                 {
1040                         if (OptAttributes == null)
1041                                 return;
1042
1043                         EmitContext ec = new EmitContext (tc, Mono.CSharp.Location.Null, null, null, 0, false);
1044                         OptAttributes.Emit (ec, this);
1045                 }
1046
1047                 protected Attribute GetClsCompliantAttribute ()
1048                 {
1049                         if (OptAttributes == null)
1050                                 return null;
1051
1052                         // Ensure that we only have GlobalAttributes, since the Search below isn't safe with other types.
1053                         if (!OptAttributes.CheckTargets (this))
1054                                 return null;
1055
1056                         EmitContext temp_ec = new EmitContext (RootContext.Tree.Types, Mono.CSharp.Location.Null, null, null, 0, false);
1057                         Attribute a = OptAttributes.Search (TypeManager.cls_compliant_attribute_type, temp_ec);
1058                         if (a != null) {
1059                                 a.Resolve (temp_ec);
1060                         }
1061                         return a;
1062                 }
1063         }
1064
1065         public class AssemblyClass: CommonAssemblyModulClass {
1066                 // TODO: make it private and move all builder based methods here
1067                 public AssemblyBuilder Builder;
1068                     
1069                 bool is_cls_compliant;
1070                 public Attribute ClsCompliantAttribute;
1071
1072                 ListDictionary declarative_security;
1073
1074                 static string[] attribute_targets = new string [] { "assembly" };
1075
1076                 public AssemblyClass (): base ()
1077                 {
1078                         is_cls_compliant = false;
1079                 }
1080
1081                 public bool IsClsCompliant {
1082                         get {
1083                                 return is_cls_compliant;
1084                         }
1085                         }
1086
1087                 public override AttributeTargets AttributeTargets {
1088                         get {
1089                                 return AttributeTargets.Assembly;
1090                         }
1091                 }
1092
1093                 public override bool IsClsCompliaceRequired(DeclSpace ds)
1094                 {
1095                         return is_cls_compliant;
1096                 }
1097
1098                 public void ResolveClsCompliance ()
1099                 {
1100                         ClsCompliantAttribute = GetClsCompliantAttribute ();
1101                         if (ClsCompliantAttribute == null)
1102                                 return;
1103
1104                         is_cls_compliant = ClsCompliantAttribute.GetClsCompliantAttributeValue (null);
1105                 }
1106
1107                 // fix bug #56621
1108                 private void SetPublicKey (AssemblyName an, byte[] strongNameBlob) 
1109                 {
1110                         try {
1111                                 // check for possible ECMA key
1112                                 if (strongNameBlob.Length == 16) {
1113                                         // will be rejected if not "the" ECMA key
1114                                         an.SetPublicKey (strongNameBlob);
1115                                 }
1116                                 else {
1117                                         // take it, with or without, a private key
1118                                         RSA rsa = CryptoConvert.FromCapiKeyBlob (strongNameBlob);
1119                                         // and make sure we only feed the public part to Sys.Ref
1120                                         byte[] publickey = CryptoConvert.ToCapiPublicKeyBlob (rsa);
1121                                         
1122                                         // AssemblyName.SetPublicKey requires an additional header
1123                                         byte[] publicKeyHeader = new byte [12] { 0x00, 0x24, 0x00, 0x00, 0x04, 0x80, 0x00, 0x00, 0x94, 0x00, 0x00, 0x00 };
1124
1125                                         byte[] encodedPublicKey = new byte [12 + publickey.Length];
1126                                         Buffer.BlockCopy (publicKeyHeader, 0, encodedPublicKey, 0, 12);
1127                                         Buffer.BlockCopy (publickey, 0, encodedPublicKey, 12, publickey.Length);
1128                                         an.SetPublicKey (encodedPublicKey);
1129                                 }
1130                         }
1131                         catch (Exception) {
1132                                 Report.Error (1548, "Could not strongname the assembly. File `" +
1133                                         RootContext.StrongNameKeyFile + "' incorrectly encoded.");
1134                                 Environment.Exit (1);
1135                         }
1136                 }
1137
1138                 // TODO: rewrite this code (to kill N bugs and make it faster) and use standard ApplyAttribute way.
1139                 public AssemblyName GetAssemblyName (string name, string output) 
1140                 {
1141                         if (OptAttributes != null) {
1142                                foreach (Attribute a in OptAttributes.Attrs) {
1143                                        // cannot rely on any resolve-based members before you call Resolve
1144                                        if (a.ExplicitTarget == null || a.ExplicitTarget != "assembly")
1145                                                continue;
1146
1147                                        // TODO: This code is buggy: comparing Attribute name without resolving it is wrong.
1148                                        //       However, this is invoked by CodeGen.Init, at which time none of the namespaces
1149                                        //       are loaded yet.
1150                                         switch (a.Name) {
1151                                                 case "AssemblyKeyFile":
1152                                                case "AssemblyKeyFileAttribute":
1153                                                case "System.Reflection.AssemblyKeyFileAttribute":
1154                                                         if (RootContext.StrongNameKeyFile != null) {
1155                                                                 Report.SymbolRelatedToPreviousError (a.Location, a.Name);
1156                                                                 Report.Warning (1616, "Compiler option '{0}' overrides '{1}' given in source", "keyfile", "System.Reflection.AssemblyKeyFileAttribute");
1157                                                         }
1158                                                         else {
1159                                                                 string value = a.GetString ();
1160                                                                 if (value != String.Empty)
1161                                                                         RootContext.StrongNameKeyFile = value;
1162                                                         }
1163                                                         break;
1164                                                 case "AssemblyKeyName":
1165                                                case "AssemblyKeyNameAttribute":
1166                                                case "System.Reflection.AssemblyKeyNameAttribute":
1167                                                         if (RootContext.StrongNameKeyContainer != null) {
1168                                                                 Report.SymbolRelatedToPreviousError (a.Location, a.Name);
1169                                                                 Report.Warning (1616, "keycontainer", "Compiler option '{0}' overrides '{1}' given in source", "System.Reflection.AssemblyKeyNameAttribute");
1170                                                         }
1171                                                         else {
1172                                                                 string value = a.GetString ();
1173                                                                 if (value != String.Empty)
1174                                                                         RootContext.StrongNameKeyContainer = value;
1175                                                         }
1176                                                         break;
1177                                                 case "AssemblyDelaySign":
1178                                                case "AssemblyDelaySignAttribute":
1179                                                case "System.Reflection.AssemblyDelaySignAttribute":
1180                                                         RootContext.StrongNameDelaySign = a.GetBoolean ();
1181                                                         break;
1182                                         }
1183                                 }
1184                         }
1185
1186                         AssemblyName an = new AssemblyName ();
1187                         an.Name = Path.GetFileNameWithoutExtension (name);
1188
1189                         // note: delay doesn't apply when using a key container
1190                         if (RootContext.StrongNameKeyContainer != null) {
1191                                 an.KeyPair = new StrongNameKeyPair (RootContext.StrongNameKeyContainer);
1192                                 return an;
1193                         }
1194
1195                         // strongname is optional
1196                         if (RootContext.StrongNameKeyFile == null)
1197                                 return an;
1198
1199                         string AssemblyDir = Path.GetDirectoryName (output);
1200
1201                         // the StrongName key file may be relative to (a) the compiled
1202                         // file or (b) to the output assembly. See bugzilla #55320
1203                         // http://bugzilla.ximian.com/show_bug.cgi?id=55320
1204
1205                         // (a) relative to the compiled file
1206                         string filename = Path.GetFullPath (RootContext.StrongNameKeyFile);
1207                         bool exist = File.Exists (filename);
1208                         if ((!exist) && (AssemblyDir != null) && (AssemblyDir != String.Empty)) {
1209                                 // (b) relative to the outputed assembly
1210                                 filename = Path.GetFullPath (Path.Combine (AssemblyDir, RootContext.StrongNameKeyFile));
1211                                 exist = File.Exists (filename);
1212                         }
1213
1214                         if (exist) {
1215                                 using (FileStream fs = new FileStream (filename, FileMode.Open, FileAccess.Read)) {
1216                                         byte[] snkeypair = new byte [fs.Length];
1217                                         fs.Read (snkeypair, 0, snkeypair.Length);
1218
1219                                         if (RootContext.StrongNameDelaySign) {
1220                                                 // delayed signing - DO NOT include private key
1221                                                 SetPublicKey (an, snkeypair);
1222                                         }
1223                                         else {
1224                                                 // no delay so we make sure we have the private key
1225                                                 try {
1226                                                         CryptoConvert.FromCapiPrivateKeyBlob (snkeypair);
1227                                                         an.KeyPair = new StrongNameKeyPair (snkeypair);
1228                                                 }
1229                                                 catch (CryptographicException) {
1230                                                         if (snkeypair.Length == 16) {
1231                                                                 // error # is different for ECMA key
1232                                                                 Report.Error (1606, "Could not strongname the assembly. " + 
1233                                                                         "ECMA key can only be used to delay-sign assemblies");
1234                                                         }
1235                                                         else {
1236                                                                 Report.Error (1548, "Could not strongname the assembly. File `" +
1237                                                                         RootContext.StrongNameKeyFile +
1238                                                                         "' doesn't have a private key.");
1239                                                         }
1240                                                         Environment.Exit (1);
1241                                                 }
1242                                         }
1243                                 }
1244                         }
1245                         else {
1246                                 Report.Error (1548, "Could not strongname the assembly. File `" +
1247                                         RootContext.StrongNameKeyFile + "' not found.");
1248                                 Environment.Exit (1);
1249                         }
1250                         return an;
1251                 }
1252
1253                 public override void ApplyAttributeBuilder (Attribute a, CustomAttributeBuilder customBuilder)
1254                 {
1255                         if (a.Type.IsSubclassOf (TypeManager.security_attr_type) && a.CheckSecurityActionValidity (true)) {
1256                                 if (declarative_security == null)
1257                                         declarative_security = new ListDictionary ();
1258
1259                                 a.ExtractSecurityPermissionSet (declarative_security);
1260                                 return;
1261                         }
1262
1263                         Builder.SetCustomAttribute (customBuilder);
1264                 }
1265
1266                 public override void Emit (TypeContainer tc)
1267                 {
1268                         base.Emit (tc);
1269
1270                         if (declarative_security != null) {
1271
1272                                 MethodInfo add_permission = typeof (AssemblyBuilder).GetMethod ("AddPermissionRequests", BindingFlags.Instance | BindingFlags.NonPublic);
1273                                 object builder_instance = Builder;
1274
1275                                 try {
1276                                         // Microsoft runtime hacking
1277                                         if (add_permission == null) {
1278                                                 Type assembly_builder = typeof (AssemblyBuilder).Assembly.GetType ("System.Reflection.Emit.AssemblyBuilderData");
1279                                                 add_permission = assembly_builder.GetMethod ("AddPermissionRequests", BindingFlags.Instance | BindingFlags.NonPublic);
1280
1281                                                 FieldInfo fi = typeof (AssemblyBuilder).GetField ("m_assemblyData", BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.GetField);
1282                                                 builder_instance = fi.GetValue (Builder);
1283                                         }
1284
1285                                         object[] args = new object [] { declarative_security [SecurityAction.RequestMinimum],
1286                                                                                                   declarative_security [SecurityAction.RequestOptional],
1287                                                                                                   declarative_security [SecurityAction.RequestRefuse] };
1288                                         add_permission.Invoke (builder_instance, args);
1289                                 }
1290                                 catch {
1291                                         Report.RuntimeMissingSupport (Location.Null, "assembly permission setting");
1292                                 }
1293                         }
1294                 }
1295
1296                 public override string[] ValidAttributeTargets {
1297                         get {
1298                                 return attribute_targets;
1299                         }
1300                 }
1301         }
1302
1303         public class ModuleClass: CommonAssemblyModulClass {
1304                 // TODO: make it private and move all builder based methods here
1305                 public ModuleBuilder Builder;
1306                 bool m_module_is_unsafe;
1307
1308                 static string[] attribute_targets = new string [] { "module" };
1309
1310                 public ModuleClass (bool is_unsafe)
1311                 {
1312                         m_module_is_unsafe = is_unsafe;
1313                 }
1314
1315                 public override AttributeTargets AttributeTargets {
1316                         get {
1317                                 return AttributeTargets.Module;
1318                         }
1319                 }
1320
1321                 public override bool IsClsCompliaceRequired(DeclSpace ds)
1322                 {
1323                         return CodeGen.Assembly.IsClsCompliant;
1324                         }
1325
1326                 public override void Emit (TypeContainer tc) 
1327                 {
1328                         base.Emit (tc);
1329
1330                         if (!m_module_is_unsafe)
1331                                 return;
1332
1333                         if (TypeManager.unverifiable_code_ctor == null) {
1334                                 Console.WriteLine ("Internal error ! Cannot set unverifiable code attribute.");
1335                                 return;
1336                         }
1337                                 
1338                         Builder.SetCustomAttribute (new CustomAttributeBuilder (TypeManager.unverifiable_code_ctor, new object [0]));
1339                 }
1340                 
1341                 public override void ApplyAttributeBuilder (Attribute a, CustomAttributeBuilder customBuilder)
1342                 {
1343                         if (a.Type == TypeManager.cls_compliant_attribute_type) {
1344                                 if (CodeGen.Assembly.ClsCompliantAttribute == null) {
1345                                         Report.Warning (3012, a.Location, "You must specify the CLSCompliant attribute on the assembly, not the module, to enable CLS compliance checking");
1346                                 }
1347                                 else if (CodeGen.Assembly.IsClsCompliant != a.GetBoolean ()) {
1348                                         Report.SymbolRelatedToPreviousError (CodeGen.Assembly.ClsCompliantAttribute.Location, CodeGen.Assembly.ClsCompliantAttribute.Name);
1349                                         Report.Error (3017, a.Location, "You cannot specify the CLSCompliant attribute on a module that differs from the CLSCompliant attribute on the assembly");
1350                                         return;
1351                                 }
1352                         }
1353
1354                         Builder.SetCustomAttribute (customBuilder);
1355                 }
1356
1357                 public override string[] ValidAttributeTargets {
1358                         get {
1359                                 return attribute_targets;
1360                         }
1361                 }
1362         }
1363 }