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

This is intended to help with flang `-ftime-report` support:
- #107270.

With this change, I was able to cherry-pick #107270, uncomment
`llvm::TimePassesIsEnabled = true;` and compile with `-ftime-report`.

I also noticed that `clang/lib/Driver/OffloadBundler.cpp` was statically
constructing a `TimerGroup` and changed it to lazily construct via
ManagedStatic.

Author: macurtis-amd

clang/lib/Driver/OffloadBundler.cpp

@@ -37,6 +37,7 @@
 #include "llvm/Support/ErrorOr.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/MD5.h"
+#include "llvm/Support/ManagedStatic.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/Program.h"
@@ -63,9 +64,17 @@ using namespace llvm;
 using namespace llvm::object;
 using namespace clang;
 
-static llvm::TimerGroup
-    ClangOffloadBundlerTimerGroup("Clang Offload Bundler Timer Group",
-                                  "Timer group for clang offload bundler");
+namespace {
+struct CreateClangOffloadBundlerTimerGroup {
+  static void *call() {
+    return new TimerGroup("Clang Offload Bundler Timer Group",
+                          "Timer group for clang offload bundler");
+  }
+};
+} // namespace
+static llvm::ManagedStatic<llvm::TimerGroup,
+                           CreateClangOffloadBundlerTimerGroup>
+    ClangOffloadBundlerTimerGroup;
 
 /// Magic string that marks the existence of offloading data.
 #define OFFLOAD_BUNDLER_MAGIC_STR "__CLANG_OFFLOAD_BUNDLE__"
@@ -987,7 +996,7 @@ CompressedOffloadBundle::compress(llvm::compression::Params P,
                              "Compression not supported");
 
   llvm::Timer HashTimer("Hash Calculation Timer", "Hash calculation time",
-                        ClangOffloadBundlerTimerGroup);
+                        *ClangOffloadBundlerTimerGroup);
   if (Verbose)
     HashTimer.startTimer();
   llvm::MD5 Hash;
@@ -1004,7 +1013,7 @@ CompressedOffloadBundle::compress(llvm::compression::Params P,
       Input.getBuffer().size());
 
   llvm::Timer CompressTimer("Compression Timer", "Compression time",
-                            ClangOffloadBundlerTimerGroup);
+                            *ClangOffloadBundlerTimerGroup);
   if (Verbose)
     CompressTimer.startTimer();
   llvm::compression::compress(P, BufferUint8, CompressedBuffer);
@@ -1119,7 +1128,7 @@ CompressedOffloadBundle::decompress(const llvm::MemoryBuffer &Input,
                              "Unknown compressing method");
 
   llvm::Timer DecompressTimer("Decompression Timer", "Decompression time",
-                              ClangOffloadBundlerTimerGroup);
+                              *ClangOffloadBundlerTimerGroup);
   if (Verbose)
     DecompressTimer.startTimer();
 
@@ -1141,7 +1150,7 @@ CompressedOffloadBundle::decompress(const llvm::MemoryBuffer &Input,
     // Recalculate MD5 hash for integrity check
     llvm::Timer HashRecalcTimer("Hash Recalculation Timer",
                                 "Hash recalculation time",
-                                ClangOffloadBundlerTimerGroup);
+                                *ClangOffloadBundlerTimerGroup);
     HashRecalcTimer.startTimer();
     llvm::MD5 Hash;
     llvm::MD5::MD5Result Result;

llvm/include/llvm/Support/Timer.h

@@ -12,13 +12,15 @@
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/DataTypes.h"
+#include "llvm/Support/Mutex.h"
 #include <cassert>
 #include <memory>
 #include <string>
 #include <vector>
 
 namespace llvm {
 
+class TimerGlobals;
 class TimerGroup;
 class raw_ostream;
 
@@ -196,6 +198,10 @@ class TimerGroup {
   TimerGroup(const TimerGroup &TG) = delete;
   void operator=(const TimerGroup &TG) = delete;
 
+  friend class TimerGlobals;
+  explicit TimerGroup(StringRef Name, StringRef Description,
+                      sys::SmartMutex<true> &lock);
+
 public:
   explicit TimerGroup(StringRef Name, StringRef Description);