Generalize delref assertion

The refcount should never become negative, not just during GC.

Author: nikic

Zend/zend_gc.c

@@ -833,7 +833,6 @@ static void gc_mark_grey(zend_refcounted *ref, gc_stack *stack)
 				while (zv != end) {
 					if (Z_REFCOUNTED_P(zv)) {
 						ref = Z_COUNTED_P(zv);
-						ZEND_ASSERT(GC_REFCOUNT(ref) > 0);
 						GC_DELREF(ref);
 						if (!GC_REF_CHECK_COLOR(ref, GC_GREY)) {
 							GC_REF_SET_COLOR(ref, GC_GREY);
@@ -844,7 +843,6 @@ static void gc_mark_grey(zend_refcounted *ref, gc_stack *stack)
 				}
 				if (EXPECTED(!ht)) {
 					ref = Z_COUNTED_P(zv);
-					ZEND_ASSERT(GC_REFCOUNT(ref) > 0);
 					GC_DELREF(ref);
 					if (!GC_REF_CHECK_COLOR(ref, GC_GREY)) {
 						GC_REF_SET_COLOR(ref, GC_GREY);
@@ -865,7 +863,6 @@ static void gc_mark_grey(zend_refcounted *ref, gc_stack *stack)
 		} else if (GC_TYPE(ref) == IS_REFERENCE) {
 			if (Z_REFCOUNTED(((zend_reference*)ref)->val)) {
 				ref = Z_COUNTED(((zend_reference*)ref)->val);
-				ZEND_ASSERT(GC_REFCOUNT(ref) > 0);
 				GC_DELREF(ref);
 				if (!GC_REF_CHECK_COLOR(ref, GC_GREY)) {
 					GC_REF_SET_COLOR(ref, GC_GREY);
@@ -898,7 +895,6 @@ static void gc_mark_grey(zend_refcounted *ref, gc_stack *stack)
 			}
 			if (Z_REFCOUNTED_P(zv)) {
 				ref = Z_COUNTED_P(zv);
-				ZEND_ASSERT(GC_REFCOUNT(ref) > 0);
 				GC_DELREF(ref);
 				if (!GC_REF_CHECK_COLOR(ref, GC_GREY)) {
 					GC_REF_SET_COLOR(ref, GC_GREY);
@@ -912,7 +908,6 @@ static void gc_mark_grey(zend_refcounted *ref, gc_stack *stack)
 			zv = Z_INDIRECT_P(zv);
 		}
 		ref = Z_COUNTED_P(zv);
-		ZEND_ASSERT(GC_REFCOUNT(ref) > 0);
 		GC_DELREF(ref);
 		if (!GC_REF_CHECK_COLOR(ref, GC_GREY)) {
 			GC_REF_SET_COLOR(ref, GC_GREY);

Zend/zend_types.h

@@ -1032,6 +1032,7 @@ static zend_always_inline uint32_t zend_gc_addref(zend_refcounted_h *p) {
 }
 
 static zend_always_inline uint32_t zend_gc_delref(zend_refcounted_h *p) {
+	ZEND_ASSERT(p->refcount > 0);
 	ZEND_RC_MOD_CHECK(p);
 	return --(p->refcount);
 }