Add gc_safepoint_signal_number() API

api/gc-api.h

@@ -307,6 +307,7 @@ static inline void gc_safepoint(struct gc_mutator *mut) {
     gc_safepoint_slow(mut);
 }
 
+GC_API_ int gc_safepoint_signal_number(void);
 GC_API_ void gc_safepoint_signal_inhibit(struct gc_mutator *mut);
 GC_API_ void gc_safepoint_signal_reallow(struct gc_mutator *mut);
 

src/bdw.c

@@ -203,6 +203,9 @@ void gc_write_barrier_slow(struct gc_mutator *mut, struct gc_ref obj,
 int* gc_safepoint_flag_loc(struct gc_mutator *mut) { GC_CRASH(); }
 void gc_safepoint_slow(struct gc_mutator *mut) { GC_CRASH(); }
 
+int gc_safepoint_signal_number(void) {
+  return GC_get_suspend_signal();
+}
 void gc_safepoint_signal_inhibit(struct gc_mutator *mut) {
   GC_alloc_lock();
 }

src/mmc.c

@@ -872,6 +872,7 @@ gc_safepoint_slow(struct gc_mutator *mut) {
   heap_unlock(heap);
 }
 
+int gc_safepoint_signal_number(void) { GC_CRASH(); }
 void gc_safepoint_signal_inhibit(struct gc_mutator *mut) { GC_CRASH(); }
 void gc_safepoint_signal_reallow(struct gc_mutator *mut) { GC_CRASH(); }
 

src/pcc.c

@@ -1084,6 +1084,7 @@ void gc_safepoint_slow(struct gc_mutator *mut) {
   heap_unlock(heap);
 }
   
+int gc_safepoint_signal_number(void) { GC_CRASH(); }
 void gc_safepoint_signal_inhibit(struct gc_mutator *mut) { GC_CRASH(); }
 void gc_safepoint_signal_reallow(struct gc_mutator *mut) { GC_CRASH(); }
 

src/semi.c

@@ -487,6 +487,7 @@ void gc_write_barrier_slow(struct gc_mutator *mut, struct gc_ref obj,
 
 int* gc_safepoint_flag_loc(struct gc_mutator *mut) { GC_CRASH(); }
 void gc_safepoint_slow(struct gc_mutator *mut) { GC_CRASH(); }
+int gc_safepoint_signal_number(void) { GC_CRASH(); }
 void gc_safepoint_signal_inhibit(struct gc_mutator *mut) { GC_CRASH(); }
 void gc_safepoint_signal_reallow(struct gc_mutator *mut) { GC_CRASH(); }