This is the mail archive of the
gcc@gcc.gnu.org
mailing list for the GCC project.
Re: GCC 4.3.0 Status Report (2008-02-14)
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