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Re: ABI voilation
Andrew Haley <aph-gcc@littlepinkcloud.COM> writes:
> Ian Lance Taylor writes:
> > Andrew Haley <aph-gcc@littlepinkcloud.COM> writes:
> >
> > > Geer Bosch asked "Can't we just explicitly align the stack frame to
> > > 128-bits during the function prologue, when we know that there are
> > > locals that require such alignment?" This seems so obvious that I
> > > can't understand why it hasn't been done.
> >
> > If you don't trust your startup code, use -mstackrealign or the
> > force_align_arg_pointer function attribute.
> >
> > We don't do it by default because it is slower and most people don't
> > need it.
>
> This doesn't make any sense to me. From what people have been saying
> here, using -Os *dealigns* the stack pointer, causing programs using
> SSE etc to fail. Do we seriously want this to happen? Is -Os
> supposed silently to break programs?
If that is happening without the -mpreferred-stack-boundary option, it
would clearly be a bug.
Ian