--  #define getSizzeofMutableByteArrayzh(r,a) \
--      r = ((StgArrWords *)(a))->bytes
emitPrimOp dflags [res] GetSizeofMutableByteArrayOp [arg]
   = emitAssign (CmmLocal res) (cmmLoadIndexW dflags arg (fixedHdrSizeW dflags) (bWord dflags))
emitPrimOp dflags [res] GetSizeofMutableByteArrayOp [arg]
   = emitAssign (CmmLocal res) (cmmLoadIndexW dflags arg (fixedHdrSizeW dflags) (bWord dflags))
emitPrimOp dflags [res] GetSizeofMutableByteArrayOp [arg]
   = emitAssign (CmmLocal res) (cmmLoadIndexW dflags arg (fixedHdrSizeW dflags) (bWord dflags))