On Mon, Feb 18, 2008 at 08:16:39PM -0500, David Edelsohn wrote: > The Altivec ABI does change the stack alignment. This should not > create an incompatibility for old code, but new code may not receive the > stack properly aligned without additional dynamic alignment.
I thought so, too, but Geoff explained to me that this is wrong. It only affects powerpc-eabi. powerpc-linux already has a sufficiently aligned stack; it's just not reflected in STACK_BOUNDARY. On powerpc-linux, if you do not pass or return vector arguments, the only affect of -mabi=altivec is that AltiVec registers are saved and restored correctly. On powerpc-eabi, we would need to dynamically align the stack for -maltivec to behave. -- Daniel Jacobowitz CodeSourcery
