[clang] [llvm] [llvm][NFC] Rework Timer.cpp globals to ensure valid lifetimes (PR #121663)

[Tarun Prabhu via llvm-commits]

================
@@ -38,63 +38,40 @@
 
 using namespace llvm;
 
-// This ugly hack is brought to you courtesy of constructor/destructor ordering
-// being unspecified by C++.  Basically the problem is that a Statistic object
-// gets destroyed, which ends up calling 'GetLibSupportInfoOutputFile()'
-// (below), which calls this function.  LibSupportInfoOutputFilename used to be
-// a global variable, but sometimes it would get destroyed before the Statistic,
-// causing havoc to ensue.  We "fix" this by creating the string the first time
-// it is needed and never destroying it.
-static ManagedStatic<std::string> LibSupportInfoOutputFilename;
-static std::string &getLibSupportInfoOutputFilename() {
-  return *LibSupportInfoOutputFilename;
+//===----------------------------------------------------------------------===//
+// Forward declarations for Managed Timer Globals (mtg) getters.
+//
+// Globals have been placed at the end of the file to restrict direct
+// access. Use of getters also has the benefit of making it a bit more explicit
+// that a global is being used.
+//===----------------------------------------------------------------------===//
+namespace {
+class Name2PairMap;
 }
 
-static ManagedStatic<sys::SmartMutex<true> > TimerLock;
-
-/// Allows llvm::Timer to emit signposts when supported.
-static ManagedStatic<SignpostEmitter> Signposts;
-
-namespace {
-struct CreateTrackSpace {
-  static void *call() {
-    return new cl::opt<bool>("track-memory",
-                             cl::desc("Enable -time-passes memory "
-                                      "tracking (this may be slow)"),
-                             cl::Hidden);
-  }
-};
-static ManagedStatic<cl::opt<bool>, CreateTrackSpace> TrackSpace;
-struct CreateInfoOutputFilename {
-  static void *call() {
-    return new cl::opt<std::string, true>(
-        "info-output-file", cl::value_desc("filename"),
-        cl::desc("File to append -stats and -timer output to"), cl::Hidden,
-        cl::location(getLibSupportInfoOutputFilename()));
-  }
-};
-static ManagedStatic<cl::opt<std::string, true>, CreateInfoOutputFilename>
-    InfoOutputFilename;
-struct CreateSortTimers {
-  static void *call() {
-    return new cl::opt<bool>(
-        "sort-timers",
-        cl::desc("In the report, sort the timers in each group "
-                 "in wall clock time order"),
-        cl::init(true), cl::Hidden);
-  }
-};
-ManagedStatic<cl::opt<bool>, CreateSortTimers> SortTimers;
-} // namespace
+namespace mtg {
+static std::string &LibSupportInfoOutputFilename();
+static const std::string &InfoOutputFilename();
+static bool TrackSpace();
+static bool SortTimers();
+static SignpostEmitter &Signposts();
+static sys::SmartMutex<true> &TimerLock();
+static TimerGroup &DefaultTimerGroup();
+static TimerGroup *claimDefaultTimerGroup();
----------------
tarunprabhu wrote:

Is there a reason that this has different casing than the other functions? 

Could all of them be made "getters" in camel case since they are functions anyway?

https://github.com/llvm/llvm-project/pull/121663