DEFAULT_CALLER_SAVES doesn't work on the mac

["Muhammed Fawzy" <mfawzymkh@xxxxxxxxxxx>]

Hi
   I am trying to force GCC to save ALL registers before functions calls. I 
am running GCC 4.0.1 on MAC OS X leopard.
I am trying to achieve this by defining DEFAULT_CALLER_SAVES as well as 
compiling with -fcaller-saves.  however, disassemble of a simple helloworld 
program that calls functions a from main doesn't show any difference.
is there any special thing needed to force gcc to save all registers ?
Thanks