--- old/src/cpu/x86/vm/c1_FrameMap_x86.hpp	2010-11-18 19:20:40.503393000 -0800
+++ new/src/cpu/x86/vm/c1_FrameMap_x86.hpp	2010-11-18 19:20:40.294031000 -0800
@@ -126,3 +126,15 @@
     assert(i >= 0 && i < nof_caller_save_xmm_regs, "out of bounds");
     return _caller_save_xmm_regs[i];
   }
+
+  // The amount of allocatable registers can change depending
+  // on whether compressed oops are on.
+  static int cpu_reg_range_reduction() {
+#ifdef _LP64
+    if (UseCompressedOops) {
+      // Reducing the allocatable range by 1 effectively excluding r12.
+      return 1;
+    }
+#endif
+    return 0;
+  }