2007-02-06 Marek Safar <marek.safar@gmail.com>
[mono.git] / mcs / mcs / flowanalysis.cs
index 05e8ce401efcb30dd25ebdcee4864d9063a22883..3eab67dfa3393d4917b93cdf5240f417f12eb4dc 100644 (file)
@@ -3,6 +3,7 @@
 //
 // Author:
 //   Martin Baulig (martin@ximian.com)
+//   Raja R Harinath (rharinath@novell.com)
 //
 // (C) 2001, 2002, 2003 Ximian, Inc.
 //
@@ -475,12 +476,12 @@ namespace Mono.CSharp
                                                      child.Type, child.Reachability.IsUnreachable, unreachable);
 
                                        if (!unreachable)
-                                               MyBitVector.And (ref locals, child.locals);
+                                               locals &= child.locals;
 
                                        // An `out' parameter must be assigned in all branches which do
                                        // not always throw an exception.
                                        if (!child.Reachability.AlwaysThrows)
-                                               MyBitVector.And (ref parameters, child.parameters);
+                                               parameters &= child.parameters;
 
                                        Report.Debug (2, "    MERGING SIBLING #2", parameters, locals);
                                }
@@ -516,8 +517,8 @@ namespace Mono.CSharp
                                        return child;
                                }
 
-                               MyBitVector.Or (ref locals, child.locals);
-                               MyBitVector.Or (ref parameters, child.parameters);
+                               locals |= child.locals;
+                               parameters |= child.parameters;
 
                                if (overwrite)
                                        reachability = new_r.Clone ();
@@ -545,8 +546,8 @@ namespace Mono.CSharp
                                        Report.Debug (1, "    MERGING BREAK ORIGIN", vector);
                                        if (vector.Reachability.IsUnreachable)
                                                continue;
-                                       MyBitVector.And (ref locals, vector.locals);
-                                       MyBitVector.And (ref parameters, vector.parameters);
+                                       locals &= vector.locals;
+                                       parameters &= vector.parameters;
                                        reachability.Meet (vector.Reachability);
                                }
 
@@ -1326,7 +1327,7 @@ namespace Mono.CSharp
                                        ArrayList non_public_fields = new ArrayList ();
 
                                        if (fields != null) {
-                                               foreach (FieldMember field in fields) {
+                                               foreach (FieldBase field in fields) {
                                                        if ((field.ModFlags & Modifiers.STATIC) != 0)
                                                                continue;
                                                        if ((field.ModFlags & Modifiers.PUBLIC) != 0)
@@ -1343,6 +1344,12 @@ namespace Mono.CSharp
                                        Fields = new FieldInfo [Count];
                                        public_fields.CopyTo (Fields, 0);
                                        non_public_fields.CopyTo (Fields, CountPublic);
+#if GMCS_SOURCE
+                               } else if (type is GenericTypeParameterBuilder) {
+                                       CountPublic = CountNonPublic = Count = 0;
+
+                                       Fields = new FieldInfo [0];
+#endif
                                } else {
                                        FieldInfo[] public_fields = type.GetFields (
                                                BindingFlags.Instance|BindingFlags.Public);
@@ -1752,49 +1759,53 @@ namespace Mono.CSharp
        // </summary>
        public class MyBitVector {
                public readonly int Count;
-               public MyBitVector InheritsFrom;
                public static readonly MyBitVector Empty = new MyBitVector ();
 
-               BitArray vector;
+               // Invariant: vector != null => vector.Count == Count
+               // Invariant: vector == null || shared == null
+               //            i.e., at most one of 'vector' and 'shared' can be non-null.  They can both be null -- that means all-ones
+               // The object in 'shared' cannot be modified, while 'vector' can be freely modified
+               BitArray vector, shared;
 
                MyBitVector ()
                {
-                       InheritsFrom = null;
-                       Count = 0;
+                       shared = new BitArray (0, false);
                }
 
                public MyBitVector (MyBitVector InheritsFrom, int Count)
                {
-                       if (InheritsFrom != null) {
-                               while (InheritsFrom.InheritsFrom != null)
-                                       InheritsFrom = InheritsFrom.InheritsFrom;                               
-                               if (InheritsFrom.Count >= Count && InheritsFrom.vector == null)
-                                       InheritsFrom = null;
-                       }
+                       if (InheritsFrom != null)
+                               shared = InheritsFrom.Shared;
 
-                       this.InheritsFrom = InheritsFrom;
                        this.Count = Count;
                }
 
+               // Use this accessor to get a shareable copy of the underlying BitArray representation
+               BitArray Shared {
+                       get {
+                               // Post-condition: vector == null
+                               if (shared == null) {
+                                       shared = vector;
+                                       vector = null;
+                               }
+                               return shared;
+                       }
+               }
+
                // <summary>
                //   Get/set bit `index' in the bit vector.
                // </summary>
-               public bool this [int index]
-               {
+               public bool this [int index] {
                        get {
                                if (index >= Count)
                                        throw new ArgumentOutOfRangeException ();
 
-                               // We're doing a "copy-on-write" strategy here; as long
-                               // as nobody writes to the array, we can use our parent's
-                               // copy instead of duplicating the vector.
-
                                if (vector != null)
                                        return vector [index];
-                               if (InheritsFrom == null)
+                               if (shared == null)
                                        return true;
-                               if (index < InheritsFrom.Count)
-                                       return InheritsFrom [index];
+                               if (index < shared.Count)
+                                       return shared [index];
                                return false;
                        }
 
@@ -1812,96 +1823,160 @@ namespace Mono.CSharp
                //   Performs an `or' operation on the bit vector.  The `new_vector' may have a
                //   different size than the current one.
                // </summary>
-               private void Or (MyBitVector new_vector)
+               private MyBitVector Or (MyBitVector new_vector)
                {
-                       int min = new_vector.Count;
+                       if (Count == 0 || new_vector.Count == 0)
+                               return this;
+
+                       BitArray o = new_vector.vector != null ? new_vector.vector : new_vector.shared;
+
+                       if (o == null) {
+                               int n = new_vector.Count;
+                               if (n < Count) {
+                                       for (int i = 0; i < n; ++i)
+                                               this [i] = true;
+                               } else {
+                                       SetAll (true);
+                               }
+                               return this;
+                       }
+
+                       if (Count == o.Count) {
+                               if (vector == null) {
+                                       if (shared == null)
+                                               return this;
+                                       initialize_vector ();
+                               }
+                               vector.Or (o);
+                               return this;
+                       }
+
+                       int min = o.Count;
                        if (Count < min)
                                min = Count;
 
-                       for (int i = 0; i < min; i++)
-                               this [i] |= new_vector [i];
+                       for (int i = 0; i < min; i++) {
+                               if (o [i])
+                                       this [i] = true;
+                       }
+
+                       return this;
                }
 
                // <summary>
-               //   Perfonrms an `and' operation on the bit vector.  The `new_vector' may have
+               //   Performs an `and' operation on the bit vector.  The `new_vector' may have
                //   a different size than the current one.
                // </summary>
-               private void And (MyBitVector new_vector)
+               private MyBitVector And (MyBitVector new_vector)
                {
-                       int min = new_vector.Count;
+                       if (Count == 0)
+                               return this;
+
+                       BitArray o = new_vector.vector != null ? new_vector.vector : new_vector.shared;
+
+                       if (o == null) {
+                               for (int i = new_vector.Count; i < Count; ++i)
+                                       this [i] = false;
+                               return this;
+                       }
+
+                       if (o.Count == 0) {
+                               SetAll (false);
+                               return this;
+                       }
+
+                       if (Count == o.Count) {
+                               if (vector == null) {
+                                       if (shared == null) {
+                                               shared = new_vector.Shared;
+                                               return this;
+                                       }
+                                       initialize_vector ();
+                               }
+                               vector.And (o);
+                               return this;
+                       }
+
+                       int min = o.Count;
                        if (Count < min)
                                min = Count;
 
-                       for (int i = 0; i < min; i++)
-                               this [i] &= new_vector [i];
+                       for (int i = 0; i < min; i++) {
+                               if (! o [i])
+                                       this [i] = false;
+                       }
 
                        for (int i = min; i < Count; i++)
                                this [i] = false;
+
+                       return this;
                }
 
-               public static void And (ref MyBitVector target, MyBitVector vector)
+               public static MyBitVector operator & (MyBitVector a, MyBitVector b)
                {
-                       if (vector == null)
-                               return;
-                       if (target == null)
-                               target = vector.Clone ();
+                       if (a == b)
+                               return a;
+                       if (a == null)
+                               return b.Clone ();
+                       if (b == null)
+                               return a.Clone ();
+                       if (a.Count > b.Count)
+                               return a.Clone ().And (b);
                        else
-                               target.And (vector);
+                               return b.Clone ().And (a);                                      
                }
 
-               public static void Or (ref MyBitVector target, MyBitVector vector)
+               public static MyBitVector operator | (MyBitVector a, MyBitVector b)
                {
-                       if (target == null)
-                               return;
-                       if (vector == null)
-                               target.SetAll (true);
+                       if (a == b)
+                               return a;
+                       if (a == null)
+                               return new MyBitVector (null, b.Count);
+                       if (b == null)
+                               return new MyBitVector (null, a.Count);
+                       if (a.Count > b.Count)
+                               return a.Clone ().Or (b);
                        else
-                               target.Or (vector);
+                               return b.Clone ().Or (a);
                }
 
-               // <summary>
-               //   This does a deep copy of the bit vector.
-               // </summary>
                public MyBitVector Clone ()
                {
-                       if (Count == 0)
-                               return Empty;
-                       MyBitVector retval = new MyBitVector (this, Count);
-                       retval.initialize_vector ();
-                       return retval;
+                       return Count == 0 ? Empty : new MyBitVector (this, Count);
                }
 
                public void SetAll (bool value)
                {
-                       InheritsFrom = value ? null : Empty;
+                       // Don't clobber Empty
+                       if (Count == 0)
+                               return;
+                       shared = value ? null : Empty.Shared;
                        vector = null;
                }
 
                void initialize_vector ()
                {
-                       if (InheritsFrom == null) {
+                       // Post-condition: vector != null
+                       if (shared == null) {
                                vector = new BitArray (Count, true);
                                return;
                        }
 
-                       vector = new BitArray (Count, false);
-
-                       int min = InheritsFrom.Count;
-                       if (min > Count)
-                               min = Count;
-
-                       for (int i = 0; i < min; i++)
-                               vector [i] = InheritsFrom [i];
-
-                       InheritsFrom = null;
+                       vector = new BitArray (shared);
+                       if (Count != vector.Count)
+                               vector.Length = Count;
+                       shared = null;
                }
 
                StringBuilder Dump (StringBuilder sb)
                {
-                       if (vector == null)
-                               return InheritsFrom == null ? sb.Append ("/") : InheritsFrom.Dump (sb.Append ("="));
-                       for (int i = 0; i < Count; i++)
-                               sb.Append (this [i] ? "1" : "0");
+                       BitArray dump = vector == null ? shared : vector;
+                       if (dump == null)
+                               return sb.Append ("/");
+                       if (dump == shared)
+                               sb.Append ("=");
+                       for (int i = 0; i < dump.Count; i++)
+                               sb.Append (dump [i] ? "1" : "0");
                        return sb;
                }