Refactor phi-function insertion module

src/main/rascal/lang/jimple/toolkit/ssa/PhiFunctionInsertion.rsc

@@ -14,30 +14,30 @@ import List;
 public FlowGraph insertPhiFunctions(FlowGraph flowGraph, map[&T, set[&T]] dominanceFrontier) {
 	newFlowGraph = { <origin, destination> | <origin, destination> <- flowGraph };
 	variableList = { getStmtVariable(graphNode) | <graphNode, _> <- flowGraph, isVariable(graphNode) };
-	
+
 	for(Variable variable <- variableList) {
-		F = {}; // set of basic blocks where φ is added
-		W = {}; // set of basic blocks that contain definitions of v
-		
+		phiBasicBlocks = {}; // "F" set of basic blocks where φ is added
+		basicBlocksContainsVariable = {}; // "W" set of basic blocks that contain definitions of v
+
 		for(variableNode <- blocksWithVariable(flowGraph, variable)) { // d ∈ Defs(v)
-			B = variableNode;
-			W = W + {B};
+			tempVariableNode = variableNode;
+			basicBlocksContainsVariable = basicBlocksContainsVariable + {tempVariableNode};
 		};
-		
-		while(size(W) != 0) {
+
+		while(size(basicBlocksContainsVariable) != 0) {
 			// remove a basic block X from W
-			tuple[Node, set[Node]] elements = takeOneFrom(W);
+			tuple[Node, set[Node]] elements = takeOneFrom(basicBlocksContainsVariable);
 			X = elements[0];
-			W = elements[1];
-			
+			basicBlocksContainsVariable = elements[1];
+
 			if(X in dominanceFrontier) { // Avoids NoSuchKey error
 				frontierNodes = dominanceFrontier[X];
-				for(Y <- frontierNodes) { // Y : basic block ∈ DF(X )
-					if(size({Y} & F) == 0 && isJoinNode(flowGraph, Y)) { // Y \notin F && Y is a join node
-						newFlowGraph = insertPhiFunction(newFlowGraph, Y, variable); // add v←φ(...) at entry of Y
-						F = F + {Y}; // F ← F ∪ {Y}
-						if(size([Y] & blocksWithVariable(flowGraph, variable)) == 0) { // Y \notin Defs(v)
-							W = W + {Y}; // W ←W ∪{Y}
+				for(frontierNode <- frontierNodes) { // Y : basic block ∈ DF(X )
+					if(size({frontierNode} & phiBasicBlocks) == 0 && isJoinNode(flowGraph, frontierNode)) { // Y \notin F && Y is a join node
+						newFlowGraph = insertPhiFunction(newFlowGraph, frontierNode, variable); // add v←φ(...) at entry of Y
+						phiBasicBlocks = phiBasicBlocks + {frontierNode}; // F ← F ∪ {Y}
+						if(size([frontierNode] & blocksWithVariable(flowGraph, variable)) == 0) { // Y \notin Defs(v)
+							basicBlocksContainsVariable = basicBlocksContainsVariable + {frontierNode}; // W ←W ∪{Y}
 						};
 					};
 				};
@@ -67,40 +67,40 @@ public list[Node] blocksWithVariable(FlowGraph flowGraph, Variable variable) {
 
 public bool isVariable(Node graphNode) {
 	if (size(graphNode[..]) == 0) return false;
-	
+
 	stmtNode(assignStatement) = graphNode;
 	if (size(assignStatement[..]) == 0) return false;
-	
+
 	variableArg = assignStatement[0];
 	typeOfVariableArg = typeOf(variableArg);
-	
+
 	if (size(typeOfVariableArg[..]) == 0) return false;
-	
+
 	return typeOfVariableArg.name == "Variable";
 }
 
 public bool isSameVariable(Node graphNode, Variable variable) {
 	if (size(graphNode[..]) == 0) return false;
-	
+
 	stmtNode(assignStatement) = graphNode;
 	if (size(assignStatement[..]) == 0) return false;
-	
+
 	variableArg = assignStatement[0];
 	typeOfVariableArg = typeOf(variableArg);
-	
+
 	if (size(typeOfVariableArg[..]) == 0) return false;
-	
+
 	return variableArg == variable;
 }
 
 public FlowGraph insertPhiFunction(FlowGraph flowGraph, Node childNode, Variable variable) {
 	fatherNodes = predecessors(flowGraph, childNode);
 	phiFunctionStmt = stmtNode(assign(variable, phiFunction(variable, [])));
-	
+
 	phiFunctionRelations = { <fatherNode, phiFunctionStmt> | fatherNode <- fatherNodes };
 	filteredFlowGraph = { <origin, destination> | <origin, destination> <- flowGraph, !(origin in fatherNodes) || !(childNode == destination) };
-	
+
 	flowGraphWithPhiFunction = phiFunctionRelations + filteredFlowGraph + {<phiFunctionStmt, childNode>};
-	
+
 	return flowGraphWithPhiFunction;
-}
+}