Avoid unnecessary allocations

Author: st0012

object.c

@@ -2950,10 +2950,16 @@ rb_obj_ivar_set_m(VALUE obj, VALUE iv, VALUE val)
 {
     ID id = id_for_var(obj, iv, instance);
     if (!id) id = rb_intern_str(iv);
-    VALUE pair = rb_ary_new_capa(2);
-    rb_ary_push(pair, iv);
-    rb_ary_push(pair, val);
-    EXEC_EVENT_HOOK(GET_EC(), RUBY_EVENT_IVAR_SET, obj, id, 0, 0, pair);
+
+    bool ivar_set_event_enabled = (ruby_vm_event_enabled_global_flags & RUBY_EVENT_IVAR_SET) &&
+        (ruby_vm_event_flags & RUBY_EVENT_IVAR_SET);
+
+    if (ivar_set_event_enabled) {
+        VALUE pair = rb_ary_new_capa(2);
+        rb_ary_push(pair, iv);
+        rb_ary_push(pair, val);
+        EXEC_EVENT_HOOK(GET_EC(), RUBY_EVENT_IVAR_SET, obj, id, 0, 0, pair);
+    }
     return rb_ivar_set(obj, id, val);
 }
 

vm_insnhelper.c

@@ -1642,11 +1642,16 @@ vm_setinstancevariable(const rb_iseq_t *iseq, VALUE obj, ID id, VALUE val, IVC i
     attr_index_t index;
     vm_ic_atomic_shape_and_index(ic, &dest_shape_id, &index);
 
-    VALUE pair = rb_ary_new_capa(2);
-    rb_ary_push(pair, rb_id2sym(id));
-    rb_ary_push(pair, val);
+    bool ivar_set_event_enabled = (ruby_vm_event_enabled_global_flags & RUBY_EVENT_IVAR_SET) &&
+        (ruby_vm_event_flags & RUBY_EVENT_IVAR_SET);
 
-    EXEC_EVENT_HOOK(GET_EC(), RUBY_EVENT_IVAR_SET, obj, id, 0, 0, pair);
+    if (ivar_set_event_enabled) {
+        VALUE pair = rb_ary_new_capa(2);
+        rb_ary_push(pair, rb_id2sym(id));
+        rb_ary_push(pair, val);
+
+        EXEC_EVENT_HOOK(GET_EC(), RUBY_EVENT_IVAR_SET, obj, id, 0, 0, pair);
+    }
 
     if (UNLIKELY(UNDEF_P(vm_setivar(obj, id, val, dest_shape_id, index)))) {
         switch (BUILTIN_TYPE(obj)) {
@@ -4759,15 +4764,15 @@ vm_call_method_each_type(rb_execution_context_t *ec, rb_control_frame_t *cfp, st
         rb_check_arity(calling->argc, 1, 1);
 
         const unsigned int aset_mask = (VM_CALL_ARGS_SPLAT | VM_CALL_KW_SPLAT | VM_CALL_KWARG | VM_CALL_FORWARDING);
+        bool ivar_set_event_enabled = (ruby_vm_event_enabled_global_flags & RUBY_EVENT_IVAR_SET) && (ruby_vm_event_flags & RUBY_EVENT_IVAR_SET);
 
         if (vm_cc_markable(cc)) {
             vm_cc_attr_index_initialize(cc, INVALID_SHAPE_ID);
             VM_CALL_METHOD_ATTR(v,
                                 vm_call_attrset_direct(ec, cfp, cc, calling->recv),
                                 CC_SET_FASTPATH(cc, vm_call_attrset,
                                     !(vm_ci_flag(ci) & aset_mask) &&
-                                    !(ruby_vm_event_flags & RUBY_EVENT_IVAR_SET) &&
-                                    !(ruby_vm_event_enabled_global_flags & RUBY_EVENT_IVAR_SET)));
+                                    !ivar_set_event_enabled));
         }
         else {
             cc = &((struct rb_callcache) {
@@ -4789,15 +4794,16 @@ vm_call_method_each_type(rb_execution_context_t *ec, rb_control_frame_t *cfp, st
                                 vm_call_attrset_direct(ec, cfp, cc, calling->recv),
                                 CC_SET_FASTPATH(cc, vm_call_attrset,
                                     !(vm_ci_flag(ci) & aset_mask) &&
-                                    !(ruby_vm_event_flags & RUBY_EVENT_IVAR_SET) &&
-                                    !(ruby_vm_event_enabled_global_flags & RUBY_EVENT_IVAR_SET)));
+                                    !ivar_set_event_enabled));
         }
 
-        ID mid = vm_cc_cme(cc)->def->body.attr.id;
-        VALUE pair = rb_ary_new_capa(2);
-        rb_ary_push(pair, rb_id2sym(mid));
-        rb_ary_push(pair, v);
-        EXEC_EVENT_HOOK(ec, RUBY_EVENT_IVAR_SET, calling->recv, mid, mid, 0, pair);
+        if (ivar_set_event_enabled) {
+            ID mid = vm_cc_cme(cc)->def->body.attr.id;
+            VALUE pair = rb_ary_new_capa(2);
+            rb_ary_push(pair, rb_id2sym(mid));
+            rb_ary_push(pair, v);
+            EXEC_EVENT_HOOK(ec, RUBY_EVENT_IVAR_SET, calling->recv, mid, mid, 0, pair);
+        }
 
         return v;