Converted MaximumSpanningTree algorithm to a generic template, this could go

into llvm/ADT.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@81001 91177308-0d34-0410-b5e6-96231b3b80d8

4 files changed, 64 insertions, 138 deletions

diff --git a/lib/Transforms/Instrumentation/CMakeLists.txt b/lib/Transforms/Instrumentation/CMakeLists.txt
index be6a451f57..494928e438 100644
--- a/lib/Transforms/Instrumentation/CMakeLists.txt
+++ b/lib/Transforms/Instrumentation/CMakeLists.txt
@@ -1,7 +1,6 @@
 add_llvm_library(LLVMInstrumentation
   BlockProfiling.cpp
   EdgeProfiling.cpp
-  MaximumSpanningTree.cpp
   OptimalEdgeProfiling.cpp
   ProfilingUtils.cpp
   RSProfiling.cpp
diff --git a/lib/Transforms/Instrumentation/MaximumSpanningTree.cpp b/lib/Transforms/Instrumentation/MaximumSpanningTree.cpp
deleted file mode 100644
index 19c4a83f76..0000000000
--- a/lib/Transforms/Instrumentation/MaximumSpanningTree.cpp
+++ /dev/null
@@ -1,119 +0,0 @@
-//===- MaximumSpanningTree.cpp - LLVM Pass to estimate profile info -------===//
-//
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-//
-// This module privides means for calculating a maximum spanning tree for the
-// CFG of a function according to a given profile. The tree does not contain
-// leaf edges, since they are needed for optimal edge profiling.
-//
-//===----------------------------------------------------------------------===//
-#define DEBUG_TYPE "maximum-spanning-tree"
-#include "MaximumSpanningTree.h"
-#include "llvm/ADT/EquivalenceClasses.h"
-#include "llvm/Support/Compiler.h"
-#include "llvm/Support/CFG.h"
-#include "llvm/Support/Debug.h"
-#include "llvm/Support/Format.h"
-using namespace llvm;
-
-namespace {
-  // compare two weighted edges
-  struct VISIBILITY_HIDDEN EdgeWeightCompare {
-    bool operator()(const ProfileInfo::EdgeWeight X, 
-                    const ProfileInfo::EdgeWeight Y) const {
-      if (X.second > Y.second) return true;
-      if (X.second < Y.second) return false;
-
-      // It would be enough to just compare the weights of the edges and be
-      // done. With edges of the same weight this may lead to a different MST
-      // each time the MST is created. To have more stable sorting (and thus
-      // more stable MSTs) furhter sort the edges.
-      if (X.first.first != 0 && Y.first.first == 0) return true;
-      if (X.first.first == 0 && Y.first.first != 0) return false;
-      if (X.first.first == 0 && Y.first.first == 0) return false;
-
-      if (X.first.first->size() > Y.first.first->size()) return true;
-      if (X.first.first->size() < Y.first.first->size()) return false;
-
-      if (X.first.second != 0 && Y.first.second == 0) return true;
-      if (X.first.second == 0 && Y.first.second != 0) return false;
-      if (X.first.second == 0 && Y.first.second == 0) return false;
-
-      if (X.first.second->size() > Y.first.second->size()) return true;
-      if (X.first.second->size() < Y.first.second->size()) return false;
-
-      return false;
-    }
-  };
-}
-
-static void inline printMSTEdge(ProfileInfo::EdgeWeight E, 
-                                const char *M) {
-  DEBUG(errs() << "--Edge " << E.first
-               <<" (Weight "<< format("%g",E.second) << ") "
-               << (M) << "\n");
-}
-
-// MaximumSpanningTree() - Takes a function and returns a spanning tree
-// according to the currently active profiling information, the leaf edges are
-// NOT in the MST. MaximumSpanningTree uses the algorithm of Kruskal.
-MaximumSpanningTree::MaximumSpanningTree(std::vector<ProfileInfo::EdgeWeight>
-                                         &EdgeVector) {
-
-  std::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
-  // fast and cheap.
-  EquivalenceClasses<const BasicBlock*> Forest;
-  for (std::vector<ProfileInfo::EdgeWeight>::iterator bbi = EdgeVector.begin(),
-       bbe = EdgeVector.end(); bbi != bbe; ++bbi) {
-    Forest.insert(bbi->first.first);
-    Forest.insert(bbi->first.second);
-  }
-  Forest.insert(0);
-
-  // Iterate over the sorted edges, biggest first.
-  for (std::vector<ProfileInfo::EdgeWeight>::iterator bbi = EdgeVector.begin(),
-       bbe = EdgeVector.end(); bbi != bbe; ++bbi) {
-    ProfileInfo::Edge e = (*bbi).first;
-
-    if (Forest.findLeader(e.first) != Forest.findLeader(e.second)) {
-      Forest.unionSets(e.first, e.second);
-      // So we know now that the edge is not already in a subtree (and not
-      // (0,entry)), so we push the edge to the MST if it has some successors.
-      MST.push_back(e);
-      printMSTEdge(*bbi,"in MST");
-    } else {
-      // This edge is either (0,entry) or (BB,0) or would create a circle in a
-      // subtree.
-      printMSTEdge(*bbi,"*not* in MST");
-    }
-  }
-
-  // Sort the MST edges.
-  std::stable_sort(MST.begin(),MST.end());
-}
-
-MaximumSpanningTree::MaxSpanTree::iterator MaximumSpanningTree::begin() {
-  return MST.begin();
-}
-
-MaximumSpanningTree::MaxSpanTree::iterator MaximumSpanningTree::end() {
-  return MST.end();
-}
-
-void MaximumSpanningTree::dump() {
-  errs()<<"{";
-  for ( MaxSpanTree::iterator ei = MST.begin(), ee = MST.end();
-        ei!=ee; ++ei ) {
-    errs()<<"("<<((*ei).first?(*ei).first->getNameStr():"0")<<",";
-    errs()<<(*ei).second->getNameStr()<<")";
-  }
-  errs()<<"}\n";
-}
diff --git a/lib/Transforms/Instrumentation/MaximumSpanningTree.h b/lib/Transforms/Instrumentation/MaximumSpanningTree.h
index 2343985f23..2951dbcea9 100644
--- a/lib/Transforms/Instrumentation/MaximumSpanningTree.h
+++ b/lib/Transforms/Instrumentation/MaximumSpanningTree.h
@@ -7,43 +7,87 @@
 //
 //===----------------------------------------------------------------------===//
 //
-// This module privides means for calculating a maximum spanning tree for the
-// CFG of a function according to a given profile.
+// This module privides means for calculating a maximum spanning tree for a
+// given set of weighted edges. The type parameter T is the type of a node.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_ANALYSIS_MAXIMUMSPANNINGTREE_H
 #define LLVM_ANALYSIS_MAXIMUMSPANNINGTREE_H
 
-#include "llvm/Analysis/ProfileInfo.h"
-#include "llvm/Support/raw_ostream.h"
+#include "llvm/ADT/EquivalenceClasses.h"
 #include <vector>
+#include <algorithm>
 
 namespace llvm {
-  class Function;
 
+  /// MaximumSpanningTree - A MST implementation.
+  /// The type parameter T determines the type of the nodes of the graph.
+  template <typename T>
   class MaximumSpanningTree {
-  public:
-    typedef std::vector<ProfileInfo::Edge> MaxSpanTree;
 
+    // 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;
+        return false;
+      }
+    };
+
+  public:
+    typedef std::pair<const T*, const T*> Edge;
+    typedef std::pair<Edge, double> EdgeWeight;
+    typedef std::vector<EdgeWeight> EdgeWeights;
   protected:
+    typedef std::vector<Edge> MaxSpanTree;
+
     MaxSpanTree MST;
 
   public:
     static char ID; // Class identification, replacement for typeinfo
 
-    // MaxSpanTree() - Calculates a MST for a function according to a profile.
-    // If inverted is true, all the edges *not* in the MST are returned. As a
-    // special also all leaf edges of the MST are not included, this makes it
-    // easier for the OptimalEdgeProfileInstrumentation to use this MST to do
-    // an optimal profiling.
-    MaximumSpanningTree(std::vector<ProfileInfo::EdgeWeight>&);
-    virtual ~MaximumSpanningTree() {}
+    /// MaximumSpanningTree() - Takes a vector of weighted edges and returns a
+    /// spanning tree.
+    MaximumSpanningTree(EdgeWeights &EdgeVector) {
+
+      std::stable_sort(EdgeVector.begin(), EdgeVector.end(), EdgeWeightCompare<T>());
+
+      // Create spanning tree, Forest contains a special data structure
+      // that makes checking if two nodes are already in a common (sub-)tree
+      // fast and cheap.
+      EquivalenceClasses<const T*> Forest;
+      for (typename EdgeWeights::iterator EWi = EdgeVector.begin(),
+           EWe = EdgeVector.end(); EWi != EWe; ++EWi) {
+        Edge e = (*EWi).first;
+
+        Forest.insert(e.first);
+        Forest.insert(e.second);
+      }
+
+      // Iterate over the sorted edges, biggest first.
+      for (typename EdgeWeights::iterator EWi = EdgeVector.begin(),
+           EWe = EdgeVector.end(); EWi != EWe; ++EWi) {
+        Edge e = (*EWi).first;
+
+        if (Forest.findLeader(e.first) != Forest.findLeader(e.second)) {
+          Forest.unionSets(e.first, e.second);
+          // So we know now that the edge is not already in a subtree, so we push
+          // the edge to the MST.
+          MST.push_back(e);
+        }
+      }
+    }
 
-    virtual MaxSpanTree::iterator begin();
-    virtual MaxSpanTree::iterator end();
+    typename MaxSpanTree::iterator begin() {
+      return MST.begin();
+    }
 
-    virtual void dump();
+    typename MaxSpanTree::iterator end() {
+      return MST.end();
+    }
   };
 
 } // End llvm namespace
diff --git a/lib/Transforms/Instrumentation/OptimalEdgeProfiling.cpp b/lib/Transforms/Instrumentation/OptimalEdgeProfiling.cpp
index 2c06423872..cdaf5f1b0d 100644
--- a/lib/Transforms/Instrumentation/OptimalEdgeProfiling.cpp
+++ b/lib/Transforms/Instrumentation/OptimalEdgeProfiling.cpp
@@ -17,6 +17,7 @@
 #include "llvm/Module.h"
 #include "llvm/Pass.h"
 #include "llvm/Analysis/Passes.h"
+#include "llvm/Analysis/ProfileInfo.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Support/Debug.h"
@@ -131,7 +132,8 @@ bool OptimalEdgeProfiler::runOnModule(Module &M) {
     ProfileInfo::EdgeWeights ECs = 
       getAnalysisID<ProfileInfo>(ProfileEstimatorPassID, *F).getEdgeWeights(F);
     std::vector<ProfileInfo::EdgeWeight> EdgeVector(ECs.begin(), ECs.end());
-    MaximumSpanningTree MST = MaximumSpanningTree(EdgeVector);
+    MaximumSpanningTree<BasicBlock> MST (EdgeVector);
+    std::stable_sort(MST.begin(),MST.end());
 
     // Check if (0,entry) not in the MST. If not, instrument edge
     // (IncrementCounterInBlock()) and set the counter initially to zero, if