[merge-fdata] Add option to print function list.

Summary:
Print total number of functions/objects that have profile
and add new options:

  -print      - print the list of objects with count to stderr
    =none     -   do not print objects/functions
    =exec     -   print functions sorted by execution count
    =branches -   print functions sorted by total branch count
  -q          - do not print merged data to stdout

(cherry picked from FBD3442288)

bolt/merge-fdata/merge-fdata.cpp

@@ -27,12 +27,40 @@ using namespace bolt;
 
 namespace opts {
 
+enum SortType : char {
+  ST_NONE,
+  ST_EXEC_COUNT,      /// Sort based on function execution count.
+  ST_TOTAL_BRANCHES,  /// Sort based on all branches in the function.
+};
+
 static cl::list<std::string>
 InputDataFilenames(cl::Positional,
                    cl::CommaSeparated,
                    cl::desc("<fdata1> [<fdata2>]..."),
                    cl::OneOrMore);
 
+static cl::opt<bool>
+SuppressMergedDataOutput("q",
+                         cl::desc("do not print merged data to stdout"),
+                         cl::init(false),
+                         cl::Optional);
+
+static cl::opt<SortType>
+PrintFunctionList(
+    "print",
+    cl::desc("print the list of objects with count to stderr"),
+    cl::init(ST_NONE),
+    cl::values(clEnumValN(ST_NONE,
+                          "none",
+                          "do not print objects/functions"),
+               clEnumValN(ST_EXEC_COUNT,
+                          "exec",
+                          "print functions sorted by execution count"),
+               clEnumValN(ST_TOTAL_BRANCHES,
+                          "branches",
+                          "print functions sorted by total branch count"),
+               clEnumValEnd));
+
 } // namespace opts
 
 static StringRef ToolName;
@@ -98,6 +126,7 @@ int main(int argc, char **argv) {
     for (auto &FI : ReaderOrErr.get()->getAllFuncsData()) {
       auto MI = MergedFunctionsData.find(FI.second.Name);
       if (MI != MergedFunctionsData.end()) {
+        MI->second.ExecutionCount += FI.second.ExecutionCount;
         std::vector<BranchInfo> TmpBI;
         for (auto &BI : FI.second.Data) {
           // Find and merge a corresponding entry or copy data.
@@ -132,6 +161,7 @@ int main(int argc, char **argv) {
             std::make_pair(*NamePtr,
                            FuncBranchData(*NamePtr,
                                           FuncBranchData::ContainerTy())));
+        MI->second.ExecutionCount = FI.second.ExecutionCount;
         // Copy with string conversion while eliminating duplicates.
         std::sort(FI.second.Data.begin(), FI.second.Data.end());
         BranchInfo *PrevBI = nullptr;
@@ -148,18 +178,59 @@ int main(int argc, char **argv) {
     }
   }
 
-  // Print all the data in the original format
-  for (auto &FDI : MergedFunctionsData) {
-    for (auto &BD : FDI.second.Data) {
-      outs() << BD.From.IsSymbol << " " << FDI.first() << " "
-             << Twine::utohexstr(BD.From.Offset) << " "
-             << BD.To.IsSymbol << " " << BD.To.Name << " "
-             << Twine::utohexstr(BD.To.Offset) << " "
-             << BD.Mispreds << " " << BD.Branches << '\n';
+  if (!opts::SuppressMergedDataOutput) {
+    // Print all the data in the original format
+    for (auto &FDI : MergedFunctionsData) {
+      for (auto &BD : FDI.second.Data) {
+        outs() << BD.From.IsSymbol << " " << FDI.first() << " "
+               << Twine::utohexstr(BD.From.Offset) << " "
+               << BD.To.IsSymbol << " " << BD.To.Name << " "
+               << Twine::utohexstr(BD.To.Offset) << " "
+               << BD.Mispreds << " " << BD.Branches << '\n';
+      }
     }
   }
 
-  errs() << "All data merged successfully.\n";
+  errs() << "Data for " << MergedFunctionsData.size()
+         << " unique objects successfully merged.\n";
+
+  if (opts::PrintFunctionList != opts::ST_NONE) {
+    // List of function names with execution count.
+    std::vector<std::pair<uint64_t, StringRef>>
+      FunctionList(MergedFunctionsData.size());
+    using CountFuncType =
+      std::function<std::pair<uint64_t,StringRef>(
+          const StringMapEntry<FuncBranchData>&)>;
+    CountFuncType ExecCountFunc = [](const StringMapEntry<FuncBranchData> &v) {
+      return std::make_pair(v.second.ExecutionCount,
+                            v.second.Name);
+    };
+    CountFuncType BranchCountFunc = [](const StringMapEntry<FuncBranchData> &v){
+      // Return total branch count.
+      uint64_t BranchCount = 0;
+      for (const auto &BI : v.second.Data)
+        BranchCount += BI.Branches;
+      return std::make_pair(BranchCount,
+                            v.second.Name);
+    };
+
+    CountFuncType CountFunc = (opts::PrintFunctionList == opts::ST_EXEC_COUNT)
+       ? ExecCountFunc
+       : BranchCountFunc;
+    std::transform(MergedFunctionsData.begin(),
+                   MergedFunctionsData.end(),
+                   FunctionList.begin(),
+                   CountFunc);
+    std::stable_sort(FunctionList.rbegin(), FunctionList.rend());
+    errs() << "Functions sorted by "
+           << (opts::PrintFunctionList == opts::ST_EXEC_COUNT
+                ? "execution"
+                : "total branch")
+           << " count:\n";
+    for (auto &FI : FunctionList) {
+      errs() << FI.second << " : " << FI.first << '\n';
+    }
+  }
 
   AllStrings.clear();