[Timers] TimerGroup: add constructor from StringMap<TimeRecord>

[lebedev.ri]

Summary

This is needed for the continuation of D46504,
to be able to store the timings.

[alexfh]

LG

include/llvm/Support/Timer.h

 //===-- llvm/Support/Timer.h - Interval Timing Support ----------*- C++ -*-===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_SUPPORT_TIMER_H
 #define LLVM_SUPPORT_TIMER_H
 
+#include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/DataTypes.h"
 #include <cassert>
 #include <string>
 #include <utility>
 #include <vector>
 
 namespace llvm {
class TimerGroup {
 
   TimerGroup **Prev; ///< Pointer to Next field of previous timergroup in list.
   TimerGroup *Next;  ///< Pointer to next timergroup in list.
   TimerGroup(const TimerGroup &TG) = delete;
   void operator=(const TimerGroup &TG) = delete;
 
 public:
   explicit TimerGroup(StringRef Name, StringRef Description);
+
+  explicit TimerGroup(StringRef Name, StringRef Description,
+                      const StringMap<TimeRecord> &Records);
+
   ~TimerGroup();
 
   void setName(StringRef NewName, StringRef NewDescription) {
     Name.assign(NewName.begin(), NewName.end());
     Description.assign(NewDescription.begin(), NewDescription.end());
   }
 
   /// Print any started timers in this group and zero them.

lib/Support/Timer.cpp

TimerGroup::TimerGroup(StringRef Name, StringRef Description)
   sys::SmartScopedLock<true> L(*TimerLock);
   if (TimerGroupList)
     TimerGroupList->Prev = &Next;
   Next = TimerGroupList;
   Prev = &TimerGroupList;
   TimerGroupList = this;
 }
 
+TimerGroup::TimerGroup(StringRef Name, StringRef Description,
+                       const StringMap<TimeRecord> &Records)
+    : TimerGroup(Name, Description) {
+  TimersToPrint.reserve(Records.size());
+  for (const auto &P : Records)
+    TimersToPrint.emplace_back(P.getValue(), P.getKey(), P.getKey());
+  assert(TimersToPrint.size() == Records.size() && "Size mismatch");
+}
+
 TimerGroup::~TimerGroup() {
   // If the timer group is destroyed before the timers it owns, accumulate and
   // print the timing data.
   while (FirstTimer)
     removeTimer(*FirstTimer);
 
   // Remove the group from the TimerGroupList.
   sys::SmartScopedLock<true> L(*TimerLock);