ABI voilation

[Tim Prince]

kanishk rastogi wrote:
> hi all,
> I wanted to know if when i specify -O[0-3] flag to gcc does gcc
> optimize the code even violating ABI for that specific arch.
> If yes can i specify gcc not to violate the ABI ....
> I am mostly concerned witht he ABI specification which tells how to
> call another function..
> 

Only the -Os changes the value of -mpreferred-stack-boundary, breaking
the ability to support vectorization or other alignment dependent code
in the callee. That change can be over-ridden e.g. by -Os
-mpreferred-stack-boundary=4.  Evidently, this is a target dependent
question.  For example, double alignment is maintained by -Os for some
targets but not others.