Pass to compute various statisics related to DSGraphs.

For now, this just computes the #indirect call sites and
the avg. #callees per indirect call site (actually it prints
both totals and the average is their ratio).


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@4705 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Analysis/DataStructure/DataStructureStats.cpp

@@ -0,0 +1,86 @@
+//===- DSGraphStats.cpp - Various statistics for DS Graphs -----*- C++ -*--===//
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Analysis/DataStructure.h"
+#include "llvm/Analysis/DSGraph.h"
+#include "llvm/Function.h"
+#include "llvm/iOther.h"
+#include "llvm/Pass.h"
+#include "Support/Statistic.h"
+#include <vector>
+
+namespace {
+  Statistic<double> TotalNumCallees("totalcallees",
+                "Total number of callee functions at all indirect call sites");
+  Statistic<> NumIndirectCalls("numindirect",
+                "Total number of indirect call sites in the program");
+  Statistic<> NumPoolNodes("numpools",
+                  "Number of allocation nodes that could be pool allocated");
+
+  class DSGraphStats: public FunctionPass {
+    void countCallees(const Function& F, const DSGraph& tdGraph);
+
+  public:
+    /// Driver functions to compute the Load/Store Dep. Graph per function.
+    bool runOnFunction(Function& F);
+
+    /// getAnalysisUsage - This modify nothing, and uses the Top-Down Graph.
+    void getAnalysisUsage(AnalysisUsage &AU) const {
+      AU.setPreservesAll();
+      AU.addRequired<TDDataStructures>();
+    }
+
+    /// Debugging support methods
+    void print(std::ostream &O) const { }
+    void dump() const;
+  };
+
+  static RegisterAnalysis<DSGraphStats> Z("dsstats", "DS Graph Statistics");
+}
+
+
+void DSGraphStats::countCallees(const Function& F,
+                                const DSGraph& tdGraph)
+{
+  unsigned numIndirectCalls = 0, totalNumCallees = 0;
+
+  const std::vector<DSCallSite>& callSites = tdGraph.getFunctionCalls();
+  for (unsigned i=0, N = callSites.size(); i < N; ++i)
+    if (callSites[i].getCallInst().getCalledFunction() == NULL)
+      { // This is an indirect function call
+        std::vector<GlobalValue*> Callees =
+          callSites[i].getCallee().getNode()->getGlobals();
+        if (Callees.size() > 0)
+          {
+            totalNumCallees  += Callees.size();
+            ++numIndirectCalls;
+          }
+#ifndef NDEBUG
+        else
+          std::cerr << "WARNING: No callee in Function " << F.getName()
+                      << "at call:\n" << callSites[i].getCallInst();
+#endif
+      }
+
+  TotalNumCallees  += totalNumCallees;
+  NumIndirectCalls += numIndirectCalls;
+
+  std::cout << "  In function " << F.getName() << " :  "
+            << (double) (numIndirectCalls == 0? 0.0
+                         : (totalNumCallees / (double) numIndirectCalls)) 
+            << " avg. callees per indirect call\n";
+}
+
+
+bool DSGraphStats::runOnFunction(Function& F)
+{
+  const DSGraph& tdGraph = getAnalysis<TDDataStructures>().getDSGraph(F);
+  countCallees(F, tdGraph);
+  return true;
+}
+
+void DSGraphStats::dump() const
+{
+  this->print(std::cerr);
+}