Subzero: Improve the output with the --timing-focus=xxx option.

src/IceTimerTree.cpp

 //===- subzero/src/IceTimerTree.cpp - Pass timer defs ---------------------===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file defines the TimerTree class, which tracks flat and
@@ skipping 79 matching lines @@
   }
   TTindex Prefix = StackTop;
   while (Prefix) {
     Nodes[Prefix].Time += Delta;
     TTindex Next = Nodes[Prefix].Parent;
     assert(Next < Prefix);
     Prefix = Next;
   }
 }
 
+void TimerStack::reset() {
+  StateChangeCount = 0;
+  FirstTimestamp = LastTimestamp = timestamp();
+  LeafTimes.assign(LeafTimes.size(), 0);
+  for (TimerTreeNode &Node : Nodes) {
+    Node.Time = 0;
+  }
+}
+
 namespace {
 
 typedef std::multimap<double, IceString> DumpMapType;
 
 // Dump the Map items in reverse order of their time contribution.
 void dumpHelper(Ostream &Str, const DumpMapType &Map, double TotalTime) {
   // TODO(stichnot): Use llvm::make_range with LLVM 3.5.
   for (auto I = Map.rbegin(), E = Map.rend(); I != E; ++I) {
     char buf[80];
     snprintf(buf, llvm::array_lengthof(buf), "  %10.6f (%4.1f%%): ", I->first,
@@ skipping 34 matching lines @@
   dumpHelper(Str, FlatMap, TotalTime);
   Str << "Number of timer updates: " << StateChangeCount << "\n";
 }
 
 double TimerStack::timestamp() {
   // TODO: Implement in terms of std::chrono for C++11.
   return llvm::TimeRecord::getCurrentTime(false).getWallTime();
 }
 
 } // end of namespace Ice