// . Check for optimal number of barriers needed for a program
// by trying to put at every possible configurations starting
// from the configuration with 1, 2, 3, ... barriers.
// . We could not do this checking directly on the flow graph
// because it is not possible to check whether a configuration
// is disabled by a particular barrier (suppose there is a branch
// and the barrier comes before it, the transition is a reordering
// between an instruction after the branch and the one before the
// branch. The barriers may even change the branch condition
// . So for every configuration we need to run the reachablity
// analysis again.
public static void CheckOptimality(State st0)
{
int i;
stateSet.AddState(st0);
FindGoodState(st0);
Console.Write("Good end values:");
for(i = 0; i < goodReportedValues.Count; i++)
Console.Write(" {0}", goodReportedValues[i]);
Console.WriteLine();
stateSet = new StateSet();
stateSet.AddState(st0);
badState = -1;
possibleLocations = new Hashtable();
FindBadState(st0);
int nLocations = 0;
IDictionaryEnumerator iter = possibleLocations.GetEnumerator();
while(iter.MoveNext())
if(((CILInstruction)iter.Value).ParentMethod.Name.Equals(".ctor") == false)
nLocations++;
marker = new int[nLocations];
for(i = 0; i < marker.Length; i++)
marker[i] = 0;
ins = new CILInstruction[marker.Length];
iter = possibleLocations.GetEnumerator();
i = 0;
while(iter.MoveNext())
if(((CILInstruction)iter.Value).ParentMethod.Name.Equals(".ctor") == false)
ins[i++] = (CILInstruction)iter.Value;
found = false;
int nBarriers = 1;
initialState = st0;
while(found == false)
{
Console.WriteLine("progress: nBarriers = {0}", nBarriers);
last = -1;
GenerateCases(nBarriers);
nBarriers++;
}
for(i = 0; i < marker.Length; i++)
if(marker[i] == 1)
Console.WriteLine(ins[i].ParentMethod.Name + ":" + ins[i]);
}
static void GenerateCases(int depth)
{
for(int i = last + 1; i < marker.Length;i++)
{
if(marker[i] == 0)
{
marker[i] = 1;
int oldLast = last;
last = i;
if(depth >= 4)
Console.WriteLine("progress: {0}: {1} of {2}", depth, i, marker.Length);
CILInstruction barrier = new CIL_call("xxxx", program.GetClass("[mscorlib]System.Threading.Thread").GetMethod("MemoryBarrier", "()"));
if(ins[i].ParentMethod.InsertInstruction(ins[i].ID, barrier) == false)
throw new Exception("Exception at insert instruction");
if(depth == 1)
{
badState = -1;
stateSet = new StateSet();
stateSet.AddState(initialState);
FindFirstBadState(initialState);
if(badState == -1)
{
found = true;
return;
}
}
else
{
GenerateCases(depth - 1);
if(found)
return;
}
if(ins[i].ParentMethod.RemoveInstruction(barrier.ID) == false)
throw new Exception("Exception at remove instruction");
last = oldLast;
marker[i] = 0;
}
}
}
