public sealed class Reachability
{
- TriState returns, throws, barrier;
+ TriState returns, barrier;
public TriState Returns {
get { return returns; }
}
- public TriState Throws {
- get { return throws; }
- }
public TriState Barrier {
get { return barrier; }
}
- Reachability (TriState returns, TriState throws, TriState barrier)
+ Reachability (TriState returns, TriState barrier)
{
this.returns = returns;
- this.throws = throws;
this.barrier = barrier;
}
public Reachability Clone ()
{
- return new Reachability (returns, throws, barrier);
+ return new Reachability (returns, barrier);
}
public static TriState TriState_Meet (TriState a, TriState b)
else
returns = TriState_Meet (returns, b.returns);
- throws = TriState_Meet (throws, b.throws);
barrier = TriState_Meet (barrier, b.barrier);
}
public void Or (Reachability b)
{
returns = TriState_Max (returns, b.returns);
- throws = TriState_Max (throws, b.throws);
barrier = TriState_Max (barrier, b.barrier);
}
public static Reachability Always ()
{
- return new Reachability (TriState.Never, TriState.Never, TriState.Never);
+ return new Reachability (TriState.Never, TriState.Never);
}
TriState Unreachable {
- get { return TriState_Max (returns, TriState_Max (throws, barrier)); }
+ get { return TriState_Max (returns, barrier); }
}
TriState Reachable {
get { return returns == TriState.Always; }
}
- public bool AlwaysThrows {
- get { return throws == TriState.Always; }
- }
-
public bool AlwaysHasBarrier {
get { return barrier == TriState.Always; }
}
returns = TriState.Always;
}
- public void SetThrows ()
- {
- throws = TriState.Always;
- }
-
public void SetBarrier ()
{
barrier = TriState.Always;
public override string ToString ()
{
- return String.Format ("[{0}:{1}:{2}:{3}]",
- ShortName (returns), ShortName (throws), ShortName (barrier),
- ShortName (Reachable));
+ return String.Format ("[{0}:{1}:{2}]",
+ ShortName (returns), ShortName (barrier), ShortName (Reachable));
}
}
reachability.SetReturns ();
}
- public void Throw ()
- {
- if (!reachability.IsUnreachable) {
- reachability.SetThrows ();
- reachability.SetBarrier ();
- }
- }
-
public void Goto ()
{
if (!reachability.IsUnreachable)
MyBitVector locals = null;
MyBitVector parameters = null;
- Reachability reachability = null;
+ Reachability reachability = sibling_list.Reachability.Clone ();
- for (UsageVector child = sibling_list; child != null; child = child.Next) {
- Report.Debug (2, " MERGING SIBLING ", reachability, child);
+ if (!sibling_list.Reachability.IsUnreachable) {
+ locals &= sibling_list.locals;
+ parameters &= sibling_list.parameters;
+ }
- if (reachability == null)
- reachability = child.Reachability.Clone ();
- else
- reachability.Meet (child.Reachability);
-
- // A local variable is initialized after a flow branching if it
- // has been initialized in all its branches which do neither
- // always return or always throw an exception.
- //
- // If a branch may return, but does not always return, then we
- // can treat it like a never-returning branch here: control will
- // only reach the code position after the branching if we did not
- // return here.
- //
- // It's important to distinguish between always and sometimes
- // returning branches here:
- //
- // 1 int a;
- // 2 if (something) {
- // 3 return;
- // 4 a = 5;
- // 5 }
- // 6 Console.WriteLine (a);
- //
- // The if block in lines 3-4 always returns, so we must not look
- // at the initialization of `a' in line 4 - thus it'll still be
- // uninitialized in line 6.
- //
- // On the other hand, the following is allowed:
- //
- // 1 int a;
- // 2 if (something)
- // 3 a = 5;
- // 4 else
- // 5 return;
- // 6 Console.WriteLine (a);
- //
- // Here, `a' is initialized in line 3 and we must not look at
- // line 5 since it always returns.
- //
- bool unreachable = child.Reachability.IsUnreachable;
-
- Report.Debug (2, " MERGING SIBLING #1", reachability,
- child.Type, child.Reachability.IsUnreachable, unreachable);
-
- if (!unreachable)
- locals &= child.locals;
+ for (UsageVector child = sibling_list.Next; child != null; child = child.Next) {
+ reachability.Meet (child.Reachability);
- // An `out' parameter must be assigned in all branches which do
- // not always throw an exception.
- if (!child.Reachability.AlwaysThrows)
+ if (!child.Reachability.IsUnreachable) {
+ locals &= child.locals;
parameters &= child.parameters;
-
- Report.Debug (2, " MERGING SIBLING #2", parameters, locals);
+ }
}
-
- if (reachability == null)
- throw new InternalErrorException ("Cannot happen: the loop above runs at least twice");
return new UsageVector (parameters, locals, reachability, null, loc);
}
projects / mono.git / blobdiff