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diff --git a/ext/opcache/Optimizer/compact_literals.c b/ext/opcache/Optimizer/compact_literals.c
index c20ddbd18356d99c1b006c2647217cd749a30bfa..deae12cdbb2763684ea3c6258b63c316258f8b67 100644 (file)
--- a/ext/opcache/Optimizer/compact_literals.c
+++ b/ext/opcache/Optimizer/compact_literals.c
@@ -345,6 +345,8 @@ void zend_optimizer_compact_literals(zend_op_array *op_array, zend_optimizer_ctx
                        }
                        switch (Z_TYPE(op_array->literals[i])) {
                                case IS_NULL:
+                                       /* Only checking MAY_MERGE for IS_NULL here 
+                                        * is because only IS_NULL can be default value for class type hinting(RECV_INIT). */
                                        if ((info[i].flags & LITERAL_MAY_MERGE)) {
                                                if (l_null < 0) {
                                                        l_null = j;