diff -rauN jdk12u-jdk-12.0.2+10/src/hotspot/share/c1/c1_Instruction.hpp jdk12u-jdk-12.0.2+10-c1-patch/src/hotspot/share/c1/c1_Instruction.hpp
--- jdk12u-jdk-12.0.2+10/src/hotspot/share/c1/c1_Instruction.hpp	2019-07-16 18:38:28.000000000 +0200
+++ jdk12u-jdk-12.0.2+10-c1-patch/src/hotspot/share/c1/c1_Instruction.hpp	2021-05-19 16:54:56.288783039 +0200
@@ -303,7 +303,6 @@
   XHandlers*   _exception_handlers;              // Flat list of exception handlers covering this instruction
 
   friend class UseCountComputer;
-  friend class BlockBegin;
 
   void update_exception_state(ValueStack* state);
 
@@ -349,7 +348,6 @@
   void* operator new(size_t size) throw() {
     Compilation* c = Compilation::current();
     void* res = c->arena()->Amalloc(size);
-    ((Instruction*)res)->_id = c->get_next_id();
     return res;
   }
 
@@ -410,11 +408,11 @@
 
   // creation
   Instruction(ValueType* type, ValueStack* state_before = NULL, bool type_is_constant = false)
-  :
+  : _id(Compilation::current()->get_next_id())
+  , _use_count(0)
 #ifndef PRODUCT
-  _printable_bci(-99),
+  , _printable_bci(-99)
 #endif
-    _use_count(0)
   , _pin_state(0)
   , _type(type)
   , _next(NULL)
@@ -1649,8 +1647,6 @@
    void* operator new(size_t size) throw() {
     Compilation* c = Compilation::current();
     void* res = c->arena()->Amalloc(size);
-    ((BlockBegin*)res)->_id = c->get_next_id();
-    ((BlockBegin*)res)->_block_id = c->get_next_block_id();
     return res;
   }
 
@@ -1662,6 +1658,7 @@
   // creation
   BlockBegin(int bci)
   : StateSplit(illegalType)
+  , _block_id(Compilation::current()->get_next_block_id())
   , _bci(bci)
   , _depth_first_number(-1)
   , _linear_scan_number(-1)