QUery regarding target macros ELIMINABLE_REGS and CAN_ELIMINATE.

[sumanth <sumanth.gundapneni@xxxxxxxxxxxxxxxxxx>]

Hi,
   I have a doubt regarding target macros ELIMINABLE_REGS and 
CAN_ELIMINATE.
   I defined eliminable regs as
   #define ELIMINABLE_REGS  { \
       {FRAME_POINTER_REGNUM, STACK_POINTER_REGNUM} , \
       {FRAME_POINTER_REGNUM, HARD_FRAME_POINTER_REGNUM} , \
       {HARD_FRAME_POINTER_REGNUM, STACK_POINTER_REGNUM} }
  and CAN_ELIMINATE(FROM, TO) as if it has to replace 
FRAME_POINTER_REGNUM  with HARD_FRAME_POINTER_REGNUM
  whenever !(frame_pointer_needed).

  But, my code generated is not according to CAN_ELIMINATE . It is not 
replacing FRAME_POINTER_REGNUM  with HARD_FRAME_POINTER_REGNUM.

Can any one point me to solution.

Thanks in advance,
Sumanth