vm: change where we set safepoints_fep to false to allow old Ctrl-C behavior.

vm/safepoints.cpp

@@ -35,7 +35,6 @@ void factor_vm::handle_safepoint(cell pc) {
   faulting_p = false;
 
   if (atomic::load(&safepoint_fep_p)) {
-    atomic::store(&safepoint_fep_p, false);
     if (atomic::load(&sampling_profiler_p))
       end_sampling_profiler();
     std::cout << "Interrupted\n";
@@ -43,10 +42,12 @@ void factor_vm::handle_safepoint(cell pc) {
       /* Ctrl-Break throws an exception, interrupting the main thread, same
          as the "t" command in the factorbug debugger. But for Ctrl-Break to
          work we don't require the debugger to be activated, or even enabled. */
+      atomic::store(&safepoint_fep_p, false);
       general_error(ERROR_INTERRUPT, false_object, false_object);
       FACTOR_ASSERT(false);
     }
     factorbug();
+    atomic::store(&safepoint_fep_p, false);
   } else if (atomic::load(&sampling_profiler_p)) {
     FACTOR_ASSERT(code->seg->in_segment_p(pc));
     code_block* block = code->code_block_for_address(pc);

vm/vm.cpp

@@ -10,7 +10,6 @@ factor_vm::factor_vm(THREADHANDLE thread)
 #if defined(WINDOWS)
       thread_id(GetCurrentThreadId()),
       ctrl_break_thread(NULL),
-      stop_on_ctrl_break(false),
 #endif
       callback_id(0),
       c_to_factor_func(NULL),
@@ -30,7 +29,8 @@ factor_vm::factor_vm(THREADHANDLE thread)
       full_output(false),
       last_nano_count(0),
       signal_callstack_seg(NULL),
-      safepoint_fep_p(false) {
+      safepoint_fep_p(false),
+      stop_on_ctrl_break(false) {
   primitive_reset_dispatch_stats();
 }
 

vm/vm.hpp

@@ -149,6 +149,9 @@ struct factor_vm {
   // Two fep_p variants, one might be redundant.
   volatile cell safepoint_fep_p;
 
+  // Allow Ctrl-Break a busy loop in the Listener, only used on Windows
+  volatile bool stop_on_ctrl_break;
+
   // contexts
   context* new_context();
   void init_context(context* ctx);
@@ -395,7 +398,6 @@ struct factor_vm {
   void primitive_die();
   void primitive_enable_ctrl_break();
   void primitive_disable_ctrl_break();
-  volatile bool stop_on_ctrl_break;
 
   // arrays
   inline void set_array_nth(array* array, cell slot, cell value);