public static List<List<string>> assign(Graph graph)
{
List<List<string>> assigned = new List<List<string>>();
List<string> available = new List<string>();
Regex literal = new Regex(@"^[0-9]+");
Regex str = new Regex(@"^"".+""");
Regex memory = new Regex(@"[MEM.+]");
//build list of available registers
for(int i = 1; i <= Allocate.registers; i++){
string reg = "R" + i;
if(!livein.Contains(reg)){
available.Add(reg);
}
}
//assign registers
for(int i = 0; i < graph.Count; i++){
Node n = graph.Get(i);
if(n.isRegister || str.IsMatch(n.id) || memory.IsMatch(n.id)){
assigned.Add(new List<string>(){n.id,n.id});
}
else if(literal.IsMatch(n.id)){
assigned.Add(new List<string>(){n.id,"="+n.id});
}
else{
assigned.Add(new List<string>(){n.id,available[0]});
available.Remove(available[0]);
}
}
return assigned;
}
public static void takeInput(List<List<string>> inputIn, List<string> live)
{
input = inputIn;
livein = live;
graph = new Graph();
Console.WriteLine("Registers = " + registers);
}
public static List<List<string>> simplify(Graph graph, List<string> spill)
{
//conditions to start colouring graph
if(graph.Count == 1 || graph.isRegisters()){
return assign(graph);
}
List<List<string>> result = new List<List<string>>();
List<int> degrees = new List<int>();
Node n;
for(int i = 0; i < graph.Count; i++){
if(graph.Get(i).isRegister){
degrees.Add(-1); //causes nodes that are already registers to be ignored when simplifying
}
else{
degrees.Add(graph.Get(i).getDegree());
}
}
//define degree that node must be at (or less than) to be simplified
int k = Allocate.registers - 1;
while(k >= 0){
if(degrees.Contains(k)){
int index = degrees.IndexOf(k);
n = graph.Get(index);
graph.Remove(n);
result = simplify(graph, spill);
if(result == null){
return null;
}
graph.Add(n);
return appendToAllocated(result, n);
}
k--;
}
n = graph.GetHighestDegreeNode();
graph.Remove(n);
spill.Add(n.id);
result = simplify(graph, spill);
if(result == null){
return null;
}
graph.Add(n);
result = appendToAllocated(result, n); //you know, let's just try to colour the node anyway
if(result != null){
spill.Remove(n.id);
}
return result;
}