[Clang][Driver] In -fintegrated-cc1 mode, avoid crashing on exit after a compiler crash

After a crash catched by the CrashRecoveryContext, this patch prevents from accessing dangling pointers in TimerGroup structures before the clang tool exits. Previously, the default TimerGroup had internal linked lists which were still pointing to old Timer or TimerGroup instances, which lived in stack frames released by the CrashRecoveryContext.

Fixes PR45164.

Differential Revision: https://reviews.llvm.org/D76099

(cherry picked from commit 28ad9fc20823678881baa0d723834b88ea9e8e3a)

2 files changed, 11 insertions, 0 deletions

diff --git a/llvm/include/llvm/Support/ManagedStatic.h b/llvm/include/llvm/Support/ManagedStatic.h
index e65bb051f18..bbd0d04ed04 100644
--- a/llvm/include/llvm/Support/ManagedStatic.h
+++ b/llvm/include/llvm/Support/ManagedStatic.h
@@ -102,6 +102,12 @@ public:
   }
 
   const C *operator->() const { return &**this; }
+
+  // Extract the instance, leaving the ManagedStatic uninitialized. The
+  // user is then responsible for the lifetime of the returned instance.
+  C *claim() {
+    return static_cast<C *>(Ptr.exchange(nullptr));
+  }
 };
 
 /// llvm_shutdown - Deallocate and destroy all ManagedStatic variables.
diff --git a/llvm/include/llvm/Support/Timer.h b/llvm/include/llvm/Support/Timer.h
index a298ecd9040..045ac448bdb 100644
--- a/llvm/include/llvm/Support/Timer.h
+++ b/llvm/include/llvm/Support/Timer.h
@@ -230,6 +230,11 @@ public:
   /// used by the Statistic code to influence the construction and destruction
   /// order of the global timer lists.
   static void ConstructTimerLists();
+
+  /// This makes the default group unmanaged, and lets the user manage the
+  /// group's lifetime.
+  static std::unique_ptr<TimerGroup> aquireDefaultGroup();
+
 private:
   friend class Timer;
   friend void PrintStatisticsJSON(raw_ostream &OS);