//
//===----------------------------------------------------------------------===//
//
-// This module privides means for calculating a maximum spanning tree for a
+// This module provides means for calculating a maximum spanning tree for a
// given set of weighted edges. The type parameter T is the type of a node.
//
//===----------------------------------------------------------------------===//
/// The type parameter T determines the type of the nodes of the graph.
template <typename T>
class MaximumSpanningTree {
-
- // A comparing class for comparing weighted edges.
- template <typename CT>
- struct EdgeWeightCompare {
- bool operator()(typename MaximumSpanningTree<CT>::EdgeWeight X,
- typename MaximumSpanningTree<CT>::EdgeWeight Y) const {
- if (X.second > Y.second) return true;
- if (X.second < Y.second) return false;
- if (const BasicBlock *BBX = dyn_cast<BasicBlock>(X.first.first)) {
- if (const BasicBlock *BBY = dyn_cast<BasicBlock>(Y.first.first)) {
- if (BBX->size() > BBY->size()) return true;
- if (BBX->size() < BBY->size()) return false;
- }
- }
- if (const BasicBlock *BBX = dyn_cast<BasicBlock>(X.first.second)) {
- if (const BasicBlock *BBY = dyn_cast<BasicBlock>(Y.first.second)) {
- if (BBX->size() > BBY->size()) return true;
- if (BBX->size() < BBY->size()) return false;
- }
- }
- return false;
- }
- };
-
public:
typedef std::pair<const T*, const T*> Edge;
typedef std::pair<Edge, double> EdgeWeight;
MaxSpanTree MST;
+ private:
+ // A comparing class for comparing weighted edges.
+ struct EdgeWeightCompare {
+ static bool getBlockSize(const T *X) {
+ const BasicBlock *BB = dyn_cast_or_null<BasicBlock>(X);
+ return BB ? BB->size() : 0;
+ }
+
+ bool operator()(EdgeWeight X, EdgeWeight Y) const {
+ if (X.second > Y.second) return true;
+ if (X.second < Y.second) return false;
+
+ // Equal edge weights: break ties by comparing block sizes.
+ size_t XSizeA = getBlockSize(X.first.first);
+ size_t YSizeA = getBlockSize(Y.first.first);
+ if (XSizeA > YSizeA) return true;
+ if (XSizeA < YSizeA) return false;
+
+ size_t XSizeB = getBlockSize(X.first.second);
+ size_t YSizeB = getBlockSize(Y.first.second);
+ if (XSizeB > YSizeB) return true;
+ if (XSizeB < YSizeB) return false;
+
+ return false;
+ }
+ };
+
public:
static char ID; // Class identification, replacement for typeinfo
/// spanning tree.
MaximumSpanningTree(EdgeWeights &EdgeVector) {
- std::stable_sort(EdgeVector.begin(), EdgeVector.end(), EdgeWeightCompare<T>());
+ std::stable_sort(EdgeVector.begin(), EdgeVector.end(), EdgeWeightCompare());
// Create spanning tree, Forest contains a special data structure
// that makes checking if two nodes are already in a common (sub-)tree