On Fri, Sep 28, 2007 at 05:22:41PM -0700, Geoffrey Keating wrote: > The case where this matters is a 32-bit ELF EABI target (the only case > on powerpc that allows 8-byte stack alignment) using -maltivec but not > -mabi=no-altivec. It's not clear to me that case works.
I was originally worried about powerpc-linux. I think I was fooled by the STACK_BOUNDARY definition, though. If the ABI actually mandates 16-byte alignment and GCC rounds up the size of stack frames it generates, then things will work out (barring broken startup code). So you must be right - it's just powerpc-eabi. > I don't think that in general you want to do this in an embedded > context, because of the extra code generated to align the stack; it'd > be much better to just declare that you're going to use the AltiVec > ABI, even if some parts of your embedded code won't be allowed to use > any AltiVec instructions. Well, it would be nice if it worked - since e.g. the GCC testsuite will try to use it! However, this doesn't affect me directly; I test the standard powerpc-linux ABI on AltiVec capable hardware, but I only test -mabi=altivec on our AltiVec capable EABI targets. Thanks. -- Daniel Jacobowitz CodeSourcery
