diff -r 9a0fd1f82406 -r 48b50573dee4 src/hotspot/cpu/x86/c2_init_x86.cpp
--- a/src/hotspot/cpu/x86/c2_init_x86.cpp	Wed Feb 20 11:11:38 2019 +0100
+++ b/src/hotspot/cpu/x86/c2_init_x86.cpp	Wed Feb 20 13:01:57 2019 +0100
@@ -29,6 +29,8 @@
 
 // processor dependent initialization for i486
 
+extern void reg_mask_init();
+
 void Compile::pd_compiler2_init() {
   guarantee(CodeEntryAlignment >= InteriorEntryAlignment, "" );
   // QQQ presumably all 64bit cpu's support this. Seems like the ifdef could
@@ -58,4 +60,5 @@
       OptoReg::invalidate(i);
     }
   }
+  reg_mask_init();
 }