static void compilePutfieldBarrier (VM_Assembler asm, int fieldOffset) {
static void compilePutfieldBarrier (VM_Assembler asm, byte reg) {
  static void compilePutfieldBarrier (VM_Assembler asm, int fieldOffset) {    //  on entry java stack contains ...|target_ref|ref_to_store|    //  SP -> ref_to_store, SP+4 -> target_ref    asm.emitPUSH_RegDisp(SP, 4);    asm.emitPUSH_Imm(fieldOffset);    asm.emitPUSH_RegDisp(SP, 8);  // Push what was originally (SP, 0)    genParameterRegisterLoad(asm, 3);    asm.emitCALL_RegDisp (JTOC, VM_Entrypoints.resolvedPutfieldWriteBarrierMethod.getOffset());  }