2 // flowanalyis.cs: The control flow analysis code
5 // Martin Baulig (martin@ximian.com)
6 // Raja R Harinath (rharinath@novell.com)
8 // Copyright 2001, 2002, 2003 Ximian, Inc.
9 // Copyright 2003-2008 Novell, Inc.
14 using System.Collections.Generic;
19 // A new instance of this class is created every time a new block is resolved
20 // and if there's branching in the block's control flow.
22 public abstract class FlowBranching
25 // The type of a FlowBranching.
27 public enum BranchingType : byte {
28 // Normal (conditional or toplevel) block.
37 // The statement embedded inside a loop
40 // part of a block headed by a jump target
46 // TryFinally, Using, Lock, CollectionForeach
52 // The toplevel block of a function
60 // The type of one sibling of a branching.
62 public enum SiblingType : byte {
71 public static FlowBranching CreateBranching (FlowBranching parent, BranchingType type, Block block, Location loc)
74 case BranchingType.Exception:
75 case BranchingType.Labeled:
76 case BranchingType.Toplevel:
77 case BranchingType.TryCatch:
78 throw new InvalidOperationException ();
80 case BranchingType.Switch:
81 return new FlowBranchingBreakable (parent, type, SiblingType.SwitchSection, block, loc);
83 case BranchingType.Block:
84 return new FlowBranchingBlock (parent, type, SiblingType.Block, block, loc);
86 case BranchingType.Loop:
87 return new FlowBranchingBreakable (parent, type, SiblingType.Conditional, block, loc);
89 case BranchingType.Embedded:
90 return new FlowBranchingContinuable (parent, type, SiblingType.Conditional, block, loc);
93 return new FlowBranchingBlock (parent, type, SiblingType.Conditional, block, loc);
98 // The type of this flow branching.
100 public readonly BranchingType Type;
103 // The block this branching is contained in. This may be null if it's not
104 // a top-level block and it doesn't declare any local variables.
106 public readonly Block Block;
109 // The parent of this branching or null if this is the top-block.
111 public readonly FlowBranching Parent;
114 // Start-Location of this flow branching.
116 public readonly Location Location;
118 static int next_id = 0;
122 // The vector contains a BitArray with information about which local variables
123 // and parameters are already initialized at the current code position.
125 public class UsageVector {
127 // The type of this branching.
129 public readonly SiblingType Type;
132 // Start location of this branching.
134 public Location Location;
137 // This is only valid for SwitchSection, Try, Catch and Finally.
139 public readonly Block Block;
142 // The number of locals in this block.
144 public readonly int CountLocals;
147 // If not null, then we inherit our state from this vector and do a
148 // copy-on-write. If null, then we're the first sibling in a top-level
149 // block and inherit from the empty vector.
151 public readonly UsageVector InheritsFrom;
154 // This is used to construct a list of UsageVector's.
156 public UsageVector Next;
164 static int next_id = 0;
168 // Normally, you should not use any of these constructors.
170 public UsageVector (SiblingType type, UsageVector parent, Block block, Location loc, int num_locals)
175 this.InheritsFrom = parent;
176 this.CountLocals = num_locals;
178 locals = num_locals == 0
180 : new MyBitVector (parent == null ? MyBitVector.Empty : parent.locals, num_locals);
183 is_unreachable = parent.is_unreachable;
189 public UsageVector (SiblingType type, UsageVector parent, Block block, Location loc)
190 : this (type, parent, block, loc, parent.CountLocals)
193 private UsageVector (MyBitVector locals, bool is_unreachable, Block block, Location loc)
195 this.Type = SiblingType.Block;
199 this.is_unreachable = is_unreachable;
201 this.locals = locals;
208 // This does a deep copy of the usage vector.
210 public UsageVector Clone ()
212 UsageVector retval = new UsageVector (Type, null, Block, Location, CountLocals);
214 retval.locals = locals.Clone ();
215 retval.is_unreachable = is_unreachable;
220 public bool IsAssigned (VariableInfo var, bool ignoreReachability)
222 if (!ignoreReachability && !var.IsParameter && IsUnreachable)
225 return var.IsAssigned (locals);
228 public void SetAssigned (VariableInfo var)
230 if (!var.IsParameter && IsUnreachable)
233 var.SetAssigned (locals);
236 public bool IsFieldAssigned (VariableInfo var, string name)
238 if (!var.IsParameter && IsUnreachable)
241 return var.IsFieldAssigned (locals, name);
244 public void SetFieldAssigned (VariableInfo var, string name)
246 if (!var.IsParameter && IsUnreachable)
249 var.SetFieldAssigned (locals, name);
252 public bool IsUnreachable {
253 get { return is_unreachable; }
256 public void ResetBarrier ()
258 is_unreachable = false;
263 is_unreachable = true;
266 public static UsageVector MergeSiblings (UsageVector sibling_list, Location loc)
268 if (sibling_list.Next == null)
271 MyBitVector locals = null;
272 bool is_unreachable = sibling_list.is_unreachable;
274 if (!sibling_list.IsUnreachable)
275 locals &= sibling_list.locals;
277 for (UsageVector child = sibling_list.Next; child != null; child = child.Next) {
278 is_unreachable &= child.is_unreachable;
280 if (!child.IsUnreachable)
281 locals &= child.locals;
284 return new UsageVector (locals, is_unreachable, null, loc);
288 // Merges a child branching.
290 public UsageVector MergeChild (UsageVector child, bool overwrite)
292 Report.Debug (2, " MERGING CHILD EFFECTS", this, child, Type);
294 bool new_isunr = child.is_unreachable;
297 // We've now either reached the point after the branching or we will
298 // never get there since we always return or always throw an exception.
300 // If we can reach the point after the branching, mark all locals and
301 // parameters as initialized which have been initialized in all branches
302 // we need to look at (see above).
305 if ((Type == SiblingType.SwitchSection) && !new_isunr) {
306 Report.Error (163, Location,
307 "Control cannot fall through from one " +
308 "case label to another");
312 locals |= child.locals;
314 // throw away un-necessary information about variables in child blocks
315 if (locals.Count != CountLocals)
316 locals = new MyBitVector (locals, CountLocals);
319 is_unreachable = new_isunr;
321 is_unreachable |= new_isunr;
326 public void MergeOrigins (UsageVector o_vectors)
328 Report.Debug (1, " MERGING BREAK ORIGINS", this);
330 if (o_vectors == null)
333 if (IsUnreachable && locals != null)
334 locals.SetAll (true);
336 for (UsageVector vector = o_vectors; vector != null; vector = vector.Next) {
337 Report.Debug (1, " MERGING BREAK ORIGIN", vector);
338 if (vector.IsUnreachable)
340 locals &= vector.locals;
341 is_unreachable &= vector.is_unreachable;
344 Report.Debug (1, " MERGING BREAK ORIGINS DONE", this);
351 public override string ToString ()
353 return String.Format ("Vector ({0},{1},{2}-{3})", Type, id, is_unreachable, locals);
358 // Creates a new flow branching which is contained in `parent'.
359 // You should only pass non-null for the `block' argument if this block
360 // introduces any new variables - in this case, we need to create a new
361 // usage vector with a different size than our parent's one.
363 protected FlowBranching (FlowBranching parent, BranchingType type, SiblingType stype,
364 Block block, Location loc)
374 UsageVector parent_vector = parent != null ? parent.CurrentUsageVector : null;
375 vector = new UsageVector (stype, parent_vector, Block, loc, Block.AssignableSlots);
377 vector = new UsageVector (stype, Parent.CurrentUsageVector, null, loc);
383 public abstract UsageVector CurrentUsageVector {
388 // Creates a sibling of the current usage vector.
390 public virtual void CreateSibling (Block block, SiblingType type)
392 UsageVector vector = new UsageVector (
393 type, Parent.CurrentUsageVector, block, Location);
396 Report.Debug (1, " CREATED SIBLING", CurrentUsageVector);
399 public void CreateSibling ()
401 CreateSibling (null, SiblingType.Conditional);
404 protected abstract void AddSibling (UsageVector uv);
406 protected abstract UsageVector Merge ();
408 public UsageVector MergeChild (FlowBranching child)
410 return CurrentUsageVector.MergeChild (child.Merge (), true);
413 public virtual bool CheckRethrow (Location loc)
415 return Parent.CheckRethrow (loc);
418 public virtual bool AddResumePoint (ResumableStatement stmt, Location loc, out int pc)
420 return Parent.AddResumePoint (stmt, loc, out pc);
423 // returns true if we crossed an unwind-protected region (try/catch/finally, lock, using, ...)
424 public virtual bool AddBreakOrigin (UsageVector vector, Location loc)
426 return Parent.AddBreakOrigin (vector, loc);
429 // returns true if we crossed an unwind-protected region (try/catch/finally, lock, using, ...)
430 public virtual bool AddContinueOrigin (UsageVector vector, Location loc)
432 return Parent.AddContinueOrigin (vector, loc);
435 // returns true if we crossed an unwind-protected region (try/catch/finally, lock, using, ...)
436 public virtual bool AddReturnOrigin (UsageVector vector, ExitStatement stmt)
438 return Parent.AddReturnOrigin (vector, stmt);
441 // returns true if we crossed an unwind-protected region (try/catch/finally, lock, using, ...)
442 public virtual bool AddGotoOrigin (UsageVector vector, Goto goto_stmt)
444 return Parent.AddGotoOrigin (vector, goto_stmt);
447 public bool IsAssigned (VariableInfo vi)
449 return CurrentUsageVector.IsAssigned (vi, false);
452 public bool IsFieldAssigned (VariableInfo vi, string field_name)
454 return CurrentUsageVector.IsAssigned (vi, false) || CurrentUsageVector.IsFieldAssigned (vi, field_name);
457 protected static Report Report {
458 get { return RootContext.ToplevelTypes.Compiler.Report; }
461 public void SetAssigned (VariableInfo vi)
463 CurrentUsageVector.SetAssigned (vi);
466 public void SetFieldAssigned (VariableInfo vi, string name)
468 CurrentUsageVector.SetFieldAssigned (vi, name);
472 public override string ToString ()
474 StringBuilder sb = new StringBuilder ();
475 sb.Append (GetType ());
483 sb.Append (Block.ID);
485 sb.Append (Block.StartLocation);
488 // sb.Append (Siblings.Length);
489 // sb.Append (" - ");
490 sb.Append (CurrentUsageVector);
492 return sb.ToString ();
497 get { return String.Format ("{0} ({1}:{2}:{3})", GetType (), id, Type, Location); }
501 public class FlowBranchingBlock : FlowBranching
503 UsageVector sibling_list = null;
505 public FlowBranchingBlock (FlowBranching parent, BranchingType type,
506 SiblingType stype, Block block, Location loc)
507 : base (parent, type, stype, block, loc)
510 public override UsageVector CurrentUsageVector {
511 get { return sibling_list; }
514 protected override void AddSibling (UsageVector sibling)
516 if (sibling_list != null && sibling_list.Type == SiblingType.Block)
517 throw new InternalErrorException ("Blocks don't have sibling flow paths");
518 sibling.Next = sibling_list;
519 sibling_list = sibling;
522 public override bool AddGotoOrigin (UsageVector vector, Goto goto_stmt)
524 LabeledStatement stmt = Block == null ? null : Block.LookupLabel (goto_stmt.Target);
526 return Parent.AddGotoOrigin (vector, goto_stmt);
529 goto_stmt.SetResolvedTarget (stmt);
530 stmt.AddUsageVector (vector);
534 public static void Error_UnknownLabel (Location loc, string label, Report Report)
536 Report.Error(159, loc, "The label `{0}:' could not be found within the scope of the goto statement",
540 protected override UsageVector Merge ()
542 Report.Debug (2, " MERGING SIBLINGS", Name);
543 UsageVector vector = UsageVector.MergeSiblings (sibling_list, Location);
544 Report.Debug (2, " MERGING SIBLINGS DONE", Name, vector);
549 public class FlowBranchingBreakable : FlowBranchingBlock
551 UsageVector break_origins;
553 public FlowBranchingBreakable (FlowBranching parent, BranchingType type, SiblingType stype, Block block, Location loc)
554 : base (parent, type, stype, block, loc)
557 public override bool AddBreakOrigin (UsageVector vector, Location loc)
559 vector = vector.Clone ();
560 vector.Next = break_origins;
561 break_origins = vector;
565 protected override UsageVector Merge ()
567 UsageVector vector = base.Merge ();
568 vector.MergeOrigins (break_origins);
573 public class FlowBranchingContinuable : FlowBranchingBlock
575 UsageVector continue_origins;
577 public FlowBranchingContinuable (FlowBranching parent, BranchingType type, SiblingType stype, Block block, Location loc)
578 : base (parent, type, stype, block, loc)
581 public override bool AddContinueOrigin (UsageVector vector, Location loc)
583 vector = vector.Clone ();
584 vector.Next = continue_origins;
585 continue_origins = vector;
589 protected override UsageVector Merge ()
591 UsageVector vector = base.Merge ();
592 vector.MergeOrigins (continue_origins);
597 public class FlowBranchingLabeled : FlowBranchingBlock
599 LabeledStatement stmt;
602 public FlowBranchingLabeled (FlowBranching parent, LabeledStatement stmt)
603 : base (parent, BranchingType.Labeled, SiblingType.Conditional, null, stmt.loc)
606 CurrentUsageVector.MergeOrigins (stmt.JumpOrigins);
607 actual = CurrentUsageVector.Clone ();
609 // stand-in for backward jumps
610 CurrentUsageVector.ResetBarrier ();
613 public override bool AddGotoOrigin (UsageVector vector, Goto goto_stmt)
615 if (goto_stmt.Target != stmt.Name)
616 return Parent.AddGotoOrigin (vector, goto_stmt);
619 goto_stmt.SetResolvedTarget (stmt);
620 actual.MergeOrigins (vector.Clone ());
625 protected override UsageVector Merge ()
627 UsageVector vector = base.Merge ();
629 if (actual.IsUnreachable)
630 Report.Warning (162, 2, stmt.loc, "Unreachable code detected");
632 actual.MergeChild (vector, false);
637 public class FlowBranchingIterator : FlowBranchingBlock
639 readonly StateMachineInitializer iterator;
641 public FlowBranchingIterator (FlowBranching parent, StateMachineInitializer iterator)
642 : base (parent, BranchingType.Iterator, SiblingType.Block, iterator.Block, iterator.Location)
644 this.iterator = iterator;
647 public override bool AddResumePoint (ResumableStatement stmt, Location loc, out int pc)
649 pc = iterator.AddResumePoint (stmt);
654 public class FlowBranchingToplevel : FlowBranchingBlock
656 UsageVector return_origins;
658 public FlowBranchingToplevel (FlowBranching parent, ParametersBlock stmt)
659 : base (parent, BranchingType.Toplevel, SiblingType.Conditional, stmt, stmt.loc)
663 public override bool CheckRethrow (Location loc)
665 Report.Error (156, loc, "A throw statement with no arguments is not allowed outside of a catch clause");
669 public override bool AddResumePoint (ResumableStatement stmt, Location loc, out int pc)
671 throw new InternalErrorException ("A yield in a non-iterator block");
674 public override bool AddBreakOrigin (UsageVector vector, Location loc)
676 Report.Error (139, loc, "No enclosing loop out of which to break or continue");
680 public override bool AddContinueOrigin (UsageVector vector, Location loc)
682 Report.Error (139, loc, "No enclosing loop out of which to break or continue");
686 public override bool AddReturnOrigin (UsageVector vector, ExitStatement stmt)
688 vector = vector.Clone ();
689 vector.Location = stmt.loc;
690 vector.Next = return_origins;
691 return_origins = vector;
695 public override bool AddGotoOrigin (UsageVector vector, Goto goto_stmt)
697 string name = goto_stmt.Target;
698 LabeledStatement s = Block.LookupLabel (name);
700 throw new InternalErrorException ("Shouldn't get here");
702 if (Parent == null) {
703 Error_UnknownLabel (goto_stmt.loc, name, Report);
707 int errors = Report.Errors;
708 Parent.AddGotoOrigin (vector, goto_stmt);
709 if (errors == Report.Errors)
710 Report.Error (1632, goto_stmt.loc, "Control cannot leave the body of an anonymous method");
714 protected override UsageVector Merge ()
716 for (UsageVector origin = return_origins; origin != null; origin = origin.Next)
717 Block.ParametersBlock.CheckOutParameters (origin, origin.Location);
719 UsageVector vector = base.Merge ();
720 Block.ParametersBlock.CheckOutParameters (vector, Block.loc);
721 // Note: we _do_not_ merge in the return origins
727 return Merge ().IsUnreachable;
731 public class FlowBranchingTryCatch : FlowBranchingBlock
734 public FlowBranchingTryCatch (FlowBranching parent, TryCatch stmt)
735 : base (parent, BranchingType.Block, SiblingType.Try, null, stmt.loc)
740 public override bool CheckRethrow (Location loc)
742 return CurrentUsageVector.Next != null || Parent.CheckRethrow (loc);
745 public override bool AddResumePoint (ResumableStatement stmt, Location loc, out int pc)
747 int errors = Report.Errors;
748 Parent.AddResumePoint (stmt, loc, out pc);
749 if (errors == Report.Errors) {
750 if (CurrentUsageVector.Next == null)
751 Report.Error (1626, loc, "Cannot yield a value in the body of a try block with a catch clause");
753 Report.Error (1631, loc, "Cannot yield a value in the body of a catch clause");
758 public override bool AddBreakOrigin (UsageVector vector, Location loc)
760 Parent.AddBreakOrigin (vector, loc);
761 stmt.SomeCodeFollows ();
765 public override bool AddContinueOrigin (UsageVector vector, Location loc)
767 Parent.AddContinueOrigin (vector, loc);
768 stmt.SomeCodeFollows ();
772 public override bool AddReturnOrigin (UsageVector vector, ExitStatement exit_stmt)
774 Parent.AddReturnOrigin (vector, exit_stmt);
775 stmt.SomeCodeFollows ();
779 public override bool AddGotoOrigin (UsageVector vector, Goto goto_stmt)
781 Parent.AddGotoOrigin (vector, goto_stmt);
786 public class FlowBranchingException : FlowBranching
788 ExceptionStatement stmt;
789 UsageVector current_vector;
790 UsageVector try_vector;
791 UsageVector finally_vector;
793 abstract class SavedOrigin {
794 public readonly SavedOrigin Next;
795 public readonly UsageVector Vector;
797 protected SavedOrigin (SavedOrigin next, UsageVector vector)
800 Vector = vector.Clone ();
803 protected abstract void DoPropagateFinally (FlowBranching parent);
804 public void PropagateFinally (UsageVector finally_vector, FlowBranching parent)
806 if (finally_vector != null)
807 Vector.MergeChild (finally_vector, false);
808 DoPropagateFinally (parent);
812 class BreakOrigin : SavedOrigin {
814 public BreakOrigin (SavedOrigin next, UsageVector vector, Location loc)
815 : base (next, vector)
820 protected override void DoPropagateFinally (FlowBranching parent)
822 parent.AddBreakOrigin (Vector, Loc);
826 class ContinueOrigin : SavedOrigin {
828 public ContinueOrigin (SavedOrigin next, UsageVector vector, Location loc)
829 : base (next, vector)
834 protected override void DoPropagateFinally (FlowBranching parent)
836 parent.AddContinueOrigin (Vector, Loc);
840 class ReturnOrigin : SavedOrigin {
841 public ExitStatement Stmt;
843 public ReturnOrigin (SavedOrigin next, UsageVector vector, ExitStatement stmt)
844 : base (next, vector)
849 protected override void DoPropagateFinally (FlowBranching parent)
851 parent.AddReturnOrigin (Vector, Stmt);
855 class GotoOrigin : SavedOrigin {
858 public GotoOrigin (SavedOrigin next, UsageVector vector, Goto stmt)
859 : base (next, vector)
864 protected override void DoPropagateFinally (FlowBranching parent)
866 parent.AddGotoOrigin (Vector, Stmt);
870 SavedOrigin saved_origins;
872 public FlowBranchingException (FlowBranching parent,
873 ExceptionStatement stmt)
874 : base (parent, BranchingType.Exception, SiblingType.Try,
880 protected override void AddSibling (UsageVector sibling)
882 switch (sibling.Type) {
883 case SiblingType.Try:
884 try_vector = sibling;
886 case SiblingType.Finally:
887 finally_vector = sibling;
890 throw new InvalidOperationException ();
892 current_vector = sibling;
895 public override UsageVector CurrentUsageVector {
896 get { return current_vector; }
899 public override bool CheckRethrow (Location loc)
901 if (!Parent.CheckRethrow (loc))
903 if (finally_vector == null)
905 Report.Error (724, loc, "A throw statement with no arguments is not allowed inside of a finally clause nested inside of the innermost catch clause");
909 public override bool AddResumePoint (ResumableStatement stmt, Location loc, out int pc)
911 int errors = Report.Errors;
912 Parent.AddResumePoint (this.stmt, loc, out pc);
913 if (errors == Report.Errors) {
914 if (finally_vector == null)
915 this.stmt.AddResumePoint (stmt, pc);
917 Report.Error (1625, loc, "Cannot yield in the body of a finally clause");
922 public override bool AddBreakOrigin (UsageVector vector, Location loc)
924 if (finally_vector != null) {
925 int errors = Report.Errors;
926 Parent.AddBreakOrigin (vector, loc);
927 if (errors == Report.Errors)
928 Report.Error (157, loc, "Control cannot leave the body of a finally clause");
930 saved_origins = new BreakOrigin (saved_origins, vector, loc);
933 // either the loop test or a back jump will follow code
934 stmt.SomeCodeFollows ();
938 public override bool AddContinueOrigin (UsageVector vector, Location loc)
940 if (finally_vector != null) {
941 int errors = Report.Errors;
942 Parent.AddContinueOrigin (vector, loc);
943 if (errors == Report.Errors)
944 Report.Error (157, loc, "Control cannot leave the body of a finally clause");
946 saved_origins = new ContinueOrigin (saved_origins, vector, loc);
949 // either the loop test or a back jump will follow code
950 stmt.SomeCodeFollows ();
954 public override bool AddReturnOrigin (UsageVector vector, ExitStatement exit_stmt)
956 if (finally_vector != null) {
957 int errors = Report.Errors;
958 Parent.AddReturnOrigin (vector, exit_stmt);
959 if (errors == Report.Errors)
960 exit_stmt.Error_FinallyClause (Report);
962 saved_origins = new ReturnOrigin (saved_origins, vector, exit_stmt);
965 // sets ec.NeedReturnLabel()
966 stmt.SomeCodeFollows ();
970 public override bool AddGotoOrigin (UsageVector vector, Goto goto_stmt)
972 LabeledStatement s = current_vector.Block == null ? null : current_vector.Block.LookupLabel (goto_stmt.Target);
974 throw new InternalErrorException ("Shouldn't get here");
976 if (finally_vector != null) {
977 int errors = Report.Errors;
978 Parent.AddGotoOrigin (vector, goto_stmt);
979 if (errors == Report.Errors)
980 Report.Error (157, goto_stmt.loc, "Control cannot leave the body of a finally clause");
982 saved_origins = new GotoOrigin (saved_origins, vector, goto_stmt);
987 protected override UsageVector Merge ()
989 UsageVector vector = try_vector.Clone ();
991 if (finally_vector != null)
992 vector.MergeChild (finally_vector, false);
994 for (SavedOrigin origin = saved_origins; origin != null; origin = origin.Next)
995 origin.PropagateFinally (finally_vector, Parent);
1002 // This is used by the flow analysis code to keep track of the type of local variables
1005 // The flow code uses a BitVector to keep track of whether a variable has been assigned
1006 // or not. This is easy for fundamental types (int, char etc.) or reference types since
1007 // you can only assign the whole variable as such.
1009 // For structs, we also need to keep track of all its fields. To do this, we allocate one
1010 // bit for the struct itself (it's used if you assign/access the whole struct) followed by
1011 // one bit for each of its fields.
1013 // This class computes this `layout' for each type.
1015 public class TypeInfo
1017 public readonly TypeSpec Type;
1020 // Total number of bits a variable of this type consumes in the flow vector.
1022 public readonly int TotalLength;
1025 // Number of bits the simple fields of a variable of this type consume
1026 // in the flow vector.
1028 public readonly int Length;
1031 // This is only used by sub-structs.
1033 public readonly int Offset;
1036 // If this is a struct.
1038 public readonly bool IsStruct;
1041 // If this is a struct, all fields which are structs theirselves.
1043 public TypeInfo[] SubStructInfo;
1045 readonly StructInfo struct_info;
1046 private static Dictionary<TypeSpec, TypeInfo> type_hash;
1053 public static void Reset ()
1055 type_hash = new Dictionary<TypeSpec, TypeInfo> ();
1056 StructInfo.field_type_hash = new Dictionary<TypeSpec, StructInfo> ();
1059 public static TypeInfo GetTypeInfo (TypeSpec type)
1062 if (type_hash.TryGetValue (type, out info))
1065 info = new TypeInfo (type);
1066 type_hash.Add (type, info);
1070 private TypeInfo (TypeSpec type)
1074 struct_info = StructInfo.GetStructInfo (type);
1075 if (struct_info != null) {
1076 Length = struct_info.Length;
1077 TotalLength = struct_info.TotalLength;
1078 SubStructInfo = struct_info.StructFields;
1087 TypeInfo (StructInfo struct_info, int offset)
1089 this.struct_info = struct_info;
1090 this.Offset = offset;
1091 this.Length = struct_info.Length;
1092 this.TotalLength = struct_info.TotalLength;
1093 this.SubStructInfo = struct_info.StructFields;
1094 this.Type = struct_info.Type;
1095 this.IsStruct = true;
1098 public int GetFieldIndex (string name)
1100 if (struct_info == null)
1103 return struct_info [name];
1106 public TypeInfo GetSubStruct (string name)
1108 if (struct_info == null)
1111 return struct_info.GetStructField (name);
1115 // A struct's constructor must always assign all fields.
1116 // This method checks whether it actually does so.
1118 public bool IsFullyInitialized (BlockContext ec, VariableInfo vi, Location loc)
1120 if (struct_info == null)
1124 FlowBranching branching = ec.CurrentBranching;
1125 for (int i = 0; i < struct_info.Count; i++) {
1126 var field = struct_info.Fields [i];
1128 // Fixed size buffers are not subject to definite assignment checking
1129 if (field is FixedFieldSpec)
1132 if (!branching.IsFieldAssigned (vi, field.Name)) {
1133 if (field.MemberDefinition is Property.BackingField) {
1134 ec.Report.Error (843, loc,
1135 "An automatically implemented property `{0}' must be fully assigned before control leaves the constructor. Consider calling the default struct contructor from a constructor initializer",
1136 field.GetSignatureForError ());
1138 ec.Report.Error (171, loc,
1139 "Field `{0}' must be fully assigned before control leaves the constructor",
1140 field.GetSignatureForError ());
1149 public override string ToString ()
1151 return String.Format ("TypeInfo ({0}:{1}:{2}:{3})",
1152 Type, Offset, Length, TotalLength);
1156 public readonly TypeSpec Type;
1157 public readonly FieldSpec[] Fields;
1158 public readonly TypeInfo[] StructFields;
1159 public readonly int Count;
1160 public readonly int CountPublic;
1161 public readonly int CountNonPublic;
1162 public readonly int Length;
1163 public readonly int TotalLength;
1164 public readonly bool HasStructFields;
1166 public static Dictionary<TypeSpec, StructInfo> field_type_hash;
1167 private Dictionary<string, TypeInfo> struct_field_hash;
1168 private Dictionary<string, int> field_hash;
1170 protected bool InTransit = false;
1172 // Private constructor. To save memory usage, we only need to create one instance
1173 // of this class per struct type.
1174 private StructInfo (TypeSpec type)
1178 field_type_hash.Add (type, this);
1180 TypeContainer tc = type.MemberDefinition as TypeContainer;
1182 var public_fields = new List<FieldSpec> ();
1183 var non_public_fields = new List<FieldSpec> ();
1186 var fields = tc.Fields;
1188 if (fields != null) {
1189 foreach (FieldBase field in fields) {
1190 if ((field.ModFlags & Modifiers.STATIC) != 0)
1192 if ((field.ModFlags & Modifiers.PUBLIC) != 0)
1193 public_fields.Add (field.Spec);
1195 non_public_fields.Add (field.Spec);
1200 CountPublic = public_fields.Count;
1201 CountNonPublic = non_public_fields.Count;
1202 Count = CountPublic + CountNonPublic;
1204 Fields = new FieldSpec[Count];
1205 public_fields.CopyTo (Fields, 0);
1206 non_public_fields.CopyTo (Fields, CountPublic);
1208 struct_field_hash = new Dictionary<string, TypeInfo> ();
1209 field_hash = new Dictionary<string, int> ();
1212 StructFields = new TypeInfo [Count];
1213 StructInfo[] sinfo = new StructInfo [Count];
1217 for (int i = 0; i < Count; i++) {
1218 var field = Fields [i];
1220 sinfo [i] = GetStructInfo (field.MemberType);
1221 if (sinfo [i] == null)
1222 field_hash.Add (field.Name, ++Length);
1223 else if (sinfo [i].InTransit) {
1231 TotalLength = Length + 1;
1232 for (int i = 0; i < Count; i++) {
1233 var field = Fields [i];
1235 if (sinfo [i] == null)
1238 field_hash.Add (field.Name, TotalLength);
1240 HasStructFields = true;
1241 StructFields [i] = new TypeInfo (sinfo [i], TotalLength);
1242 struct_field_hash.Add (field.Name, StructFields [i]);
1243 TotalLength += sinfo [i].TotalLength;
1247 public int this [string name] {
1250 if (!field_hash.TryGetValue (name, out val))
1257 public TypeInfo GetStructField (string name)
1260 if (struct_field_hash.TryGetValue (name, out ti))
1266 public static StructInfo GetStructInfo (TypeSpec type)
1268 if (!type.IsStruct || type.BuiltinType > 0)
1272 if (field_type_hash.TryGetValue (type, out info))
1275 return new StructInfo (type);
1281 // This is used by the flow analysis code to store information about a single local variable
1282 // or parameter. Depending on the variable's type, we need to allocate one or more elements
1283 // in the BitVector - if it's a fundamental or reference type, we just need to know whether
1284 // it has been assigned or not, but for structs, we need this information for each of its fields.
1286 public class VariableInfo {
1287 public readonly string Name;
1288 public readonly TypeInfo TypeInfo;
1291 // The bit offset of this variable in the flow vector.
1293 public readonly int Offset;
1296 // The number of bits this variable needs in the flow vector.
1297 // The first bit always specifies whether the variable as such has been assigned while
1298 // the remaining bits contain this information for each of a struct's fields.
1300 public readonly int Length;
1303 // If this is a parameter of local variable.
1305 public readonly bool IsParameter;
1307 public readonly LocalVariable LocalInfo;
1309 readonly VariableInfo Parent;
1310 VariableInfo[] sub_info;
1312 bool is_ever_assigned;
1313 public bool IsEverAssigned {
1314 get { return is_ever_assigned; }
1317 protected VariableInfo (string name, TypeSpec type, int offset)
1320 this.Offset = offset;
1321 this.TypeInfo = TypeInfo.GetTypeInfo (type);
1323 Length = TypeInfo.TotalLength;
1328 protected VariableInfo (VariableInfo parent, TypeInfo type)
1330 this.Name = parent.Name;
1331 this.TypeInfo = type;
1332 this.Offset = parent.Offset + type.Offset;
1333 this.Parent = parent;
1334 this.Length = type.TotalLength;
1336 this.IsParameter = parent.IsParameter;
1337 this.LocalInfo = parent.LocalInfo;
1342 protected void Initialize ()
1344 TypeInfo[] sub_fields = TypeInfo.SubStructInfo;
1345 if (sub_fields != null) {
1346 sub_info = new VariableInfo [sub_fields.Length];
1347 for (int i = 0; i < sub_fields.Length; i++) {
1348 if (sub_fields [i] != null)
1349 sub_info [i] = new VariableInfo (this, sub_fields [i]);
1352 sub_info = new VariableInfo [0];
1355 public VariableInfo (LocalVariable local_info, int offset)
1356 : this (local_info.Name, local_info.Type, offset)
1358 this.LocalInfo = local_info;
1359 this.IsParameter = false;
1362 public VariableInfo (ParametersCompiled ip, int i, int offset)
1363 : this (ip.FixedParameters [i].Name, ip.Types [i], offset)
1365 this.IsParameter = true;
1368 public bool IsAssigned (ResolveContext ec)
1370 return !ec.DoFlowAnalysis ||
1371 (ec.OmitStructFlowAnalysis && TypeInfo.Type.IsStruct) ||
1372 ec.CurrentBranching.IsAssigned (this);
1375 public bool IsAssigned (ResolveContext ec, Location loc)
1377 if (IsAssigned (ec))
1380 ec.Report.Error (165, loc,
1381 "Use of unassigned local variable `" + Name + "'");
1382 ec.CurrentBranching.SetAssigned (this);
1386 public bool IsAssigned (MyBitVector vector)
1391 if (vector [Offset])
1394 // FIXME: Fix SetFieldAssigned to set the whole range like SetAssigned below. Then, get rid of this stanza
1395 for (VariableInfo parent = Parent; parent != null; parent = parent.Parent) {
1396 if (vector [parent.Offset]) {
1397 // 'parent' is assigned, but someone forgot to note that all its components are assigned too
1398 parent.SetAssigned (vector);
1403 // Return unless this is a struct.
1404 if (!TypeInfo.IsStruct)
1407 // Ok, so each field must be assigned.
1408 for (int i = 0; i < TypeInfo.Length; i++) {
1409 if (!vector [Offset + i + 1])
1413 // Ok, now check all fields which are structs.
1414 for (int i = 0; i < sub_info.Length; i++) {
1415 VariableInfo sinfo = sub_info [i];
1419 if (!sinfo.IsAssigned (vector))
1423 vector [Offset] = true;
1424 is_ever_assigned = true;
1428 public void SetAssigned (ResolveContext ec)
1430 if (ec.DoFlowAnalysis)
1431 ec.CurrentBranching.SetAssigned (this);
1434 public void SetAssigned (MyBitVector vector)
1437 vector [Offset] = true;
1439 vector.SetRange (Offset, Length);
1440 is_ever_assigned = true;
1443 public bool IsFieldAssigned (ResolveContext ec, string name, Location loc)
1445 if (!ec.DoFlowAnalysis ||
1446 ec.OmitStructFlowAnalysis && TypeInfo.IsStruct ||
1447 ec.CurrentBranching.IsFieldAssigned (this, name))
1450 ec.Report.Error (170, loc,
1451 "Use of possibly unassigned field `" + name + "'");
1452 ec.CurrentBranching.SetFieldAssigned (this, name);
1456 public bool IsFieldAssigned (MyBitVector vector, string field_name)
1458 int field_idx = TypeInfo.GetFieldIndex (field_name);
1463 return vector [Offset + field_idx];
1466 public void SetFieldAssigned (ResolveContext ec, string name)
1468 if (ec.DoFlowAnalysis)
1469 ec.CurrentBranching.SetFieldAssigned (this, name);
1472 public void SetFieldAssigned (MyBitVector vector, string field_name)
1474 int field_idx = TypeInfo.GetFieldIndex (field_name);
1479 vector [Offset + field_idx] = true;
1480 is_ever_assigned = true;
1483 public VariableInfo GetSubStruct (string name)
1485 TypeInfo type = TypeInfo.GetSubStruct (name);
1490 return new VariableInfo (this, type);
1493 public override string ToString ()
1495 return String.Format ("VariableInfo ({0}:{1}:{2}:{3}:{4})",
1496 Name, TypeInfo, Offset, Length, IsParameter);
1501 // This is a special bit vector which can inherit from another bit vector doing a
1502 // copy-on-write strategy. The inherited vector may have a smaller size than the
1505 public class MyBitVector {
1506 public readonly int Count;
1507 public static readonly MyBitVector Empty = new MyBitVector ();
1509 // Invariant: vector != null => vector.Count == Count
1510 // Invariant: vector == null || shared == null
1511 // i.e., at most one of 'vector' and 'shared' can be non-null. They can both be null -- that means all-ones
1512 // The object in 'shared' cannot be modified, while 'vector' can be freely modified
1513 System.Collections.BitArray vector, shared;
1517 shared = new System.Collections.BitArray (0, false);
1520 public MyBitVector (MyBitVector InheritsFrom, int Count)
1522 if (InheritsFrom != null)
1523 shared = InheritsFrom.MakeShared (Count);
1528 System.Collections.BitArray MakeShared (int new_count)
1530 // Post-condition: vector == null
1532 // ensure we don't leak out dirty bits from the BitVector we inherited from
1533 if (new_count > Count &&
1534 ((shared != null && shared.Count > Count) ||
1535 (shared == null && vector == null)))
1536 initialize_vector ();
1538 if (vector != null) {
1547 // Get/set bit `index' in the bit vector.
1549 public bool this [int index] {
1552 // FIXME: Disabled due to missing anonymous method flow analysis
1553 // throw new ArgumentOutOfRangeException ();
1557 return vector [index];
1560 if (index < shared.Count)
1561 return shared [index];
1566 // Only copy the vector if we're actually modifying it.
1567 if (this [index] != value) {
1569 initialize_vector ();
1570 vector [index] = value;
1576 // Performs an `or' operation on the bit vector. The `new_vector' may have a
1577 // different size than the current one.
1579 private MyBitVector Or (MyBitVector new_vector)
1581 if (Count == 0 || new_vector.Count == 0)
1584 var o = new_vector.vector != null ? new_vector.vector : new_vector.shared;
1587 int n = new_vector.Count;
1589 for (int i = 0; i < n; ++i)
1597 if (Count == o.Count) {
1598 if (vector == null) {
1601 initialize_vector ();
1611 for (int i = 0; i < min; i++) {
1620 // Performs an `and' operation on the bit vector. The `new_vector' may have
1621 // a different size than the current one.
1623 private MyBitVector And (MyBitVector new_vector)
1628 var o = new_vector.vector != null ? new_vector.vector : new_vector.shared;
1631 for (int i = new_vector.Count; i < Count; ++i)
1641 if (Count == o.Count) {
1642 if (vector == null) {
1643 if (shared == null) {
1644 shared = new_vector.MakeShared (Count);
1647 initialize_vector ();
1657 for (int i = 0; i < min; i++) {
1662 for (int i = min; i < Count; i++)
1668 public static MyBitVector operator & (MyBitVector a, MyBitVector b)
1676 if (a.Count > b.Count)
1677 return a.Clone ().And (b);
1679 return b.Clone ().And (a);
1682 public static MyBitVector operator | (MyBitVector a, MyBitVector b)
1687 return new MyBitVector (null, b.Count);
1689 return new MyBitVector (null, a.Count);
1690 if (a.Count > b.Count)
1691 return a.Clone ().Or (b);
1693 return b.Clone ().Or (a);
1696 public MyBitVector Clone ()
1698 return Count == 0 ? Empty : new MyBitVector (this, Count);
1701 public void SetRange (int offset, int length)
1703 if (offset > Count || offset + length > Count)
1704 throw new ArgumentOutOfRangeException ("flow-analysis");
1706 if (shared == null && vector == null)
1710 if (shared != null) {
1711 if (offset + length <= shared.Count) {
1712 for (; i < length; ++i)
1713 if (!shared [i+offset])
1718 initialize_vector ();
1720 for (; i < length; ++i)
1721 vector [i+offset] = true;
1725 public void SetAll (bool value)
1727 // Don't clobber Empty
1730 shared = value ? null : Empty.MakeShared (Count);
1734 void initialize_vector ()
1736 // Post-condition: vector != null
1737 if (shared == null) {
1738 vector = new System.Collections.BitArray (Count, true);
1742 vector = new System.Collections.BitArray (shared);
1743 if (Count != vector.Count)
1744 vector.Length = Count;
1748 StringBuilder Dump (StringBuilder sb)
1750 var dump = vector == null ? shared : vector;
1752 return sb.Append ("/");
1755 for (int i = 0; i < dump.Count; i++)
1756 sb.Append (dump [i] ? "1" : "0");
1760 public override string ToString ()
1762 return Dump (new StringBuilder ("{")).Append ("}").ToString ();