------- Comment #16 from hjl dot tools at gmail dot com 2009-02-12 17:01 ------- (In reply to comment #15) > The DFmode and DImodes are different. Aligning DFmode on stack is very > performance critical, while DImodes on 32bit machine can quite safely be > misaligned (if we ignore their possible use in MMX intrincisc). > I think we ought to be able to handle this case without any extra options: > when > function use DFmode variables trigger stack realign at > -mpreferred-stack-boundary=2 and -O2, while do not trigger it with DImode.
That may break Ada or others. See comment #11. I still think a new command line option to control DImode alignment is better. It won't be the first command line option which changes ABI. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39137
