From 5b7d8df30604cfffaeb688f208bee49463980301 Mon Sep 17 00:00:00 2001
From: Lee Killough <15950023+leekillough@users.noreply.github.com>
Date: Thu, 14 Nov 2024 13:34:06 -0600
Subject: [PATCH] Add [[noreturn]] attribute to Output::fatal, add SST_Exit()
 function (#1175)

* Add [[noreturn]] attribute to Output::fatal, add SST_Exit() function
---
 src/sst/core/output.cc         | 18 ++----------------
 src/sst/core/output.h          |  3 ++-
 src/sst/core/simulation.cc     | 26 ++++++++++++++++++++++++++
 src/sst/core/simulation_impl.h |  8 ++++++--
 4 files changed, 36 insertions(+), 19 deletions(-)

diff --git a/src/sst/core/output.cc b/src/sst/core/output.cc
index 7aaafe7ef..5e048a398 100644
--- a/src/sst/core/output.cc
+++ b/src/sst/core/output.cc
@@ -41,9 +41,6 @@ REENABLE_WARNING
 
 namespace SST {
 
-// Atomic to control access to calling MPI_Abort or exit() in fatal() call
-std::atomic<int> fatal_count = 0;
-
 // Initialize The Static Member Variables
 Output      Output::m_defaultObject;
 std::string Output::m_sstGlobalSimFileName        = "";
@@ -159,7 +156,7 @@ Output::getOutputLocation() const
     return m_targetLoc;
 }
 
-void
+[[noreturn]] void
 Output::fatal(uint32_t line, const char* file, const char* func, int exit_code, const char* format, ...) const
 {
     va_list     arg1;
@@ -217,18 +214,7 @@ Output::fatal(uint32_t line, const char* file, const char* func, int exit_code,
 
     Simulation_impl::emergencyShutdown();
 
-    int count = fatal_count.fetch_add(1);
-
-    // Make sure only one thread calls MPI_Abort() or exit() in the
-    // case where two threads call fatal() at the same time
-    if ( count == 0 ) {
-#ifdef SST_CONFIG_HAVE_MPI
-        // If MPI exists, abort
-        MPI_Abort(MPI_COMM_WORLD, exit_code);
-#else
-        exit(exit_code);
-#endif
-    }
+    SST_Exit(exit_code);
 }
 
 void
diff --git a/src/sst/core/output.h b/src/sst/core/output.h
index a12c5f19a..41b4856e5 100644
--- a/src/sst/core/output.h
+++ b/src/sst/core/output.h
@@ -394,7 +394,8 @@ class Output
         @param format Format string.  All valid formats for printf are available.
         @param ... Arguments for format.
      */
-    void fatal(uint32_t line, const char* file, const char* func, int exit_code, const char* format, ...) const
+    [[noreturn]] void
+    fatal(uint32_t line, const char* file, const char* func, int exit_code, const char* format, ...) const
         __attribute__((format(printf, 6, 7)));
 
     // GET / SET METHODS
diff --git a/src/sst/core/simulation.cc b/src/sst/core/simulation.cc
index 7dd30bd6b..8ad51c6aa 100644
--- a/src/sst/core/simulation.cc
+++ b/src/sst/core/simulation.cc
@@ -43,7 +43,14 @@
 #include "sst/core/unitAlgebra.h"
 #include "sst/core/warnmacros.h"
 
+#ifdef SST_CONFIG_HAVE_MPI
+DISABLE_WARN_MISSING_OVERRIDE
+#include <mpi.h>
+REENABLE_WARNING
+#endif
+
 #include <cinttypes>
+#include <exception>
 #include <fstream>
 #include <iostream>
 #include <string>
@@ -2064,6 +2071,25 @@ Simulation_impl::printPerformanceInfo()
 }
 #endif
 
+[[noreturn]] void
+SST_Exit(int exit_code)
+{
+    // Make sure only one thread calls MPI_Abort() or exit() in the
+    // case where two threads call fatal() at the same time
+    // Only one thread initializes the function-local static variable
+    // Other threads are blocked
+
+#ifdef SST_CONFIG_HAVE_MPI
+    // If MPI exists, abort
+    static int exit_once = (MPI_Abort(MPI_COMM_WORLD, exit_code), 0);
+#else
+    static int exit_once = (exit(exit_code), 0);
+#endif
+
+    // Should never get here
+    std::terminate();
+}
+
 /* Define statics */
 Factory*                   Simulation_impl::factory;
 TimeLord                   Simulation_impl::timeLord;
diff --git a/src/sst/core/simulation_impl.h b/src/sst/core/simulation_impl.h
index 4f4a029aa..a0a62f3c0 100644
--- a/src/sst/core/simulation_impl.h
+++ b/src/sst/core/simulation_impl.h
@@ -16,6 +16,7 @@
 
 #include "sst/core/clock.h"
 #include "sst/core/componentInfo.h"
+#include "sst/core/exit.h"
 #include "sst/core/oneshot.h"
 #include "sst/core/output.h"
 #include "sst/core/profile/profiletool.h"
@@ -36,6 +37,9 @@ extern int main(int argc, char** argv);
 
 namespace SST {
 
+// Function to exit, guarding against race conditions if multiple threads call it
+[[noreturn]] void SST_Exit(int exit_code);
+
 #define _SIM_DBG(fmt, args...) __DBG(DBG_SIM, Sim, fmt, ##args)
 #define STATALLFLAG            "--ALLSTATS--"
 
@@ -243,7 +247,7 @@ class Simulation_impl
         if ( nullptr != i ) { return i->getComponent(); }
         else {
             printf("Simulation::getComponent() couldn't find component with id = %" PRIu64 "\n", id);
-            exit(1);
+            SST_Exit(1);
         }
     }
 
@@ -255,7 +259,7 @@ class Simulation_impl
         if ( nullptr != i ) { return i; }
         else {
             printf("Simulation::getComponentInfo() couldn't find component with id = %" PRIu64 "\n", id);
-            exit(1);
+            SST_Exit(1);
         }
     }