[llvm][Timer] Use global TimerGroups for both new pass manager and old pass manager timers (#130375)

alanzhao1 · web-flow · commit 09d8e442ac28 · 2025-03-13T10:13:28.000-07:00
Additionally, remove the behavior for both pass manager's timer manager classes (`PassTimingInfo` for the old pass manager and `TimePassesHandler` for the new pass manager) where these classes would print the values of their timers upon destruction. Currently, each pass manager manages their own `TimerGroup`s. This is problematic because of duplicate `TimerGroup`s (both pass managers have a `TimerGroup` for pass times with identical names and descriptions). The result is that in Clang, `-ftime-report` has two "Pass execution timing report" sections (one for the new pass manager which manages optimization passes, and one for the old pass manager which manages the backend). The result of this change is that Clang's `-ftime-report` now prints both optimization and backend pass timing info in a unified "Pass execution timing report" section. Moving the ownership of the `TimerGroups` to globals also makes it easier to implement JSON-formatted `-ftime-report`. This was not possible with the old structure because the two pass managers were created and destroyed in far parts of the codebase and outputting JSON requires the printing logic to be at the same place because of formatting. Previous discourse discussion: https://discourse.llvm.org/t/difficulties-with-implementing-json-formatted-ftime-report/84353
diff --git a/clang/test/Misc/time-passes.c b/clang/test/Misc/time-passes.c
@@ -19,6 +19,5 @@
 // NPM:       InstCombinePass{{$}}
 // NPM-NOT:   InstCombinePass #
 // TIME: Total{{$}}
-// NPM: Pass execution timing report
 
 int foo(int x, int y) { return x + y; }
diff --git a/llvm/include/llvm/IR/PassTimingInfo.h b/llvm/include/llvm/IR/PassTimingInfo.h
@@ -39,17 +39,18 @@ Timer *getPassTimer(Pass *);
 /// This class implements -time-passes functionality for new pass manager.
 /// It provides the pass-instrumentation callbacks that measure the pass
 /// execution time. They collect timing info into individual timers as
-/// passes are being run. At the end of its life-time it prints the resulting
-/// timing report.
+/// passes are being run.
 class TimePassesHandler {
   /// Value of this type is capable of uniquely identifying pass invocations.
   /// It is a pair of string Pass-Identifier (which for now is common
   /// to all the instance of a given pass) + sequential invocation counter.
   using PassInvocationID = std::pair<StringRef, unsigned>;
 
   /// Groups of timers for passes and analyses.
-  TimerGroup PassTG;
-  TimerGroup AnalysisTG;
+  TimerGroup &PassTG =
+      NamedRegionTimer::getNamedTimerGroup(PassGroupName, PassGroupDesc);
+  TimerGroup &AnalysisTG = NamedRegionTimer::getNamedTimerGroup(
+      AnalysisGroupName, AnalysisGroupDesc);
 
   using TimerVector = llvm::SmallVector<std::unique_ptr<Timer>, 4>;
   /// Map of timers for pass invocations
@@ -71,12 +72,15 @@ class TimePassesHandler {
   bool PerRun;
 
 public:
+  static constexpr StringRef PassGroupName = "pass";
+  static constexpr StringRef AnalysisGroupName = "analysis";
+  static constexpr StringRef PassGroupDesc = "Pass execution timing report";
+  static constexpr StringRef AnalysisGroupDesc =
+      "Analysis execution timing report";
+
   TimePassesHandler();
   TimePassesHandler(bool Enabled, bool PerRun = false);
 
-  /// Destructor handles the print action if it has not been handled before.
-  ~TimePassesHandler() { print(); }
-
   /// Prints out timing information and then resets the timers.
   void print();
 
diff --git a/llvm/include/llvm/Support/Timer.h b/llvm/include/llvm/Support/Timer.h
@@ -169,6 +169,11 @@ struct NamedRegionTimer : public TimeRegion {
   explicit NamedRegionTimer(StringRef Name, StringRef Description,
                             StringRef GroupName,
                             StringRef GroupDescription, bool Enabled = true);
+
+  // Create or get a TimerGroup stored in the same global map owned by
+  // NamedRegionTimer.
+  static TimerGroup &getNamedTimerGroup(StringRef GroupName,
+                                        StringRef GroupDescription);
 };
 
 /// The TimerGroup class is used to group together related timers into a single
diff --git a/llvm/lib/IR/PassTimingInfo.cpp b/llvm/lib/IR/PassTimingInfo.cpp
@@ -63,16 +63,9 @@ class PassTimingInfo {
 private:
   StringMap<unsigned> PassIDCountMap; ///< Map that counts instances of passes
   DenseMap<PassInstanceID, std::unique_ptr<Timer>> TimingData; ///< timers for pass instances
-  TimerGroup TG;
+  TimerGroup *PassTG = nullptr;
 
 public:
-  /// Default constructor for yet-inactive timeinfo.
-  /// Use \p init() to activate it.
-  PassTimingInfo();
-
-  /// Print out timing information and release timers.
-  ~PassTimingInfo();
-
   /// Initializes the static \p TheTimeInfo member to a non-null value when
   /// -time-passes is enabled. Leaves it null otherwise.
   ///
@@ -94,14 +87,6 @@ class PassTimingInfo {
 
 static ManagedStatic<sys::SmartMutex<true>> TimingInfoMutex;
 
-PassTimingInfo::PassTimingInfo() : TG("pass", "Pass execution timing report") {}
-
-PassTimingInfo::~PassTimingInfo() {
-  // Deleting the timers accumulates their info into the TG member.
-  // Then TG member is (implicitly) deleted, actually printing the report.
-  TimingData.clear();
-}
-
 void PassTimingInfo::init() {
   if (TheTimeInfo || !TimePassesIsEnabled)
     return;
@@ -110,12 +95,16 @@ void PassTimingInfo::init() {
   // This guarantees that the object will be constructed after static globals,
   // thus it will be destroyed before them.
   static ManagedStatic<PassTimingInfo> TTI;
+  if (!TTI->PassTG)
+    TTI->PassTG = &NamedRegionTimer::getNamedTimerGroup(
+        TimePassesHandler::PassGroupName, TimePassesHandler::PassGroupDesc);
   TheTimeInfo = &*TTI;
 }
 
 /// Prints out timing information and then resets the timers.
 void PassTimingInfo::print(raw_ostream *OutStream) {
-  TG.print(OutStream ? *OutStream : *CreateInfoOutputFile(), true);
+  assert(PassTG && "PassTG is null, did you call PassTimingInfo::Init()?");
+  PassTG->print(OutStream ? *OutStream : *CreateInfoOutputFile(), true);
 }
 
 Timer *PassTimingInfo::newPassTimer(StringRef PassID, StringRef PassDesc) {
@@ -124,7 +113,8 @@ Timer *PassTimingInfo::newPassTimer(StringRef PassID, StringRef PassDesc) {
   // Appending description with a pass-instance number for all but the first one
   std::string PassDescNumbered =
       num <= 1 ? PassDesc.str() : formatv("{0} #{1}", PassDesc, num).str();
-  return new Timer(PassID, PassDescNumbered, TG);
+  assert(PassTG && "PassTG is null, did you call PassTimingInfo::Init()?");
+  return new Timer(PassID, PassDescNumbered, *PassTG);
 }
 
 Timer *PassTimingInfo::getPassTimer(Pass *P, PassInstanceID Pass) {
@@ -193,9 +183,7 @@ Timer &TimePassesHandler::getPassTimer(StringRef PassID, bool IsPass) {
 }
 
 TimePassesHandler::TimePassesHandler(bool Enabled, bool PerRun)
-    : PassTG("pass", "Pass execution timing report"),
-      AnalysisTG("analysis", "Analysis execution timing report"),
-      Enabled(Enabled), PerRun(PerRun) {}
+    : Enabled(Enabled), PerRun(PerRun) {}
 
 TimePassesHandler::TimePassesHandler()
     : TimePassesHandler(TimePassesIsEnabled, TimePassesPerRun) {}
diff --git a/llvm/lib/Support/Timer.cpp b/llvm/lib/Support/Timer.cpp
@@ -222,16 +222,27 @@ class Name2PairMap {
              StringRef GroupDescription) {
     sys::SmartScopedLock<true> L(timerLock());
 
-    std::pair<TimerGroup*, Name2TimerMap> &GroupEntry = Map[GroupName];
-
-    if (!GroupEntry.first)
-      GroupEntry.first = new TimerGroup(GroupName, GroupDescription);
-
+    std::pair<TimerGroup *, Name2TimerMap> &GroupEntry =
+        getGroupEntry(GroupName, GroupDescription);
     Timer &T = GroupEntry.second[Name];
     if (!T.isInitialized())
       T.init(Name, Description, *GroupEntry.first);
     return T;
   }
+
+  TimerGroup &getTimerGroup(StringRef GroupName, StringRef GroupDescription) {
+    return *getGroupEntry(GroupName, GroupDescription).first;
+  }
+
+private:
+  std::pair<TimerGroup *, Name2TimerMap> &
+  getGroupEntry(StringRef GroupName, StringRef GroupDescription) {
+    std::pair<TimerGroup *, Name2TimerMap> &GroupEntry = Map[GroupName];
+    if (!GroupEntry.first)
+      GroupEntry.first = new TimerGroup(GroupName, GroupDescription);
+
+    return GroupEntry;
+  }
 };
 
 }
@@ -244,6 +255,11 @@ NamedRegionTimer::NamedRegionTimer(StringRef Name, StringRef Description,
                      : &namedGroupedTimers().get(Name, Description, GroupName,
                                                  GroupDescription)) {}
 
+TimerGroup &NamedRegionTimer::getNamedTimerGroup(StringRef GroupName,
+                                                 StringRef GroupDescription) {
+  return namedGroupedTimers().getTimerGroup(GroupName, GroupDescription);
+}
+
 //===----------------------------------------------------------------------===//
 //   TimerGroup Implementation
 //===----------------------------------------------------------------------===//
diff --git a/llvm/unittests/IR/TimePassesTest.cpp b/llvm/unittests/IR/TimePassesTest.cpp
@@ -161,8 +161,8 @@ TEST(TimePassesTest, CustomOut) {
   PI.runBeforePass(Pass2, M);
   PI.runAfterPass(Pass2, M, PreservedAnalyses::all());
 
-  // Generate report by deleting the handler.
-  TimePasses.reset();
+  // Clear and generate report again.
+  TimePasses->print();
 
   // There should be Pass2 in this report and no Pass1.
   EXPECT_FALSE(TimePassesStr.str().empty());
