Change the arrch64 abi ...(Custom /Specific change)

[Umesh Kalappa]

Hi All,

We are in process of changing the gcc compiler for aarch64 abi ,w.r.t
varargs  function arguments handling.

default(LP64) ,where 1,2,4 bytes  args are promoted to word size i.e 4
bytes ,we need to change these behaviour to 8 bytes (double word).

we are looking both hooks like  PROMOTE_MODE and
TARGET_PROMOTE_FUNCTION_MODE to make the changes.

arm has the definition for these macros and we are trying tweak the
code ,any expert suggestions  ,will help us to implement .

The gcc compiler version is 4.7.0 .


Thank you
~Umesh