[Bug target/111107] i686-w64-mingw32 does not realign stack when __attribute__((aligned)) or __attribute__((vector_size)) are used

[zfigura at codeweavers dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111107

--- Comment #15 from Zeb Figura <zfigura at codeweavers dot com> ---
(In reply to Eric Botcazou from comment #14)
> > I'd say that
> > 
> > config/i386/cygming.h:#define STACK_REALIGN_DEFAULT TARGET_SSE
> > 
> > is a non-working "fix".  The appropriate default would be
> > -mincoming-stack-boundary=2.  MIN_STACK_BOUNDARY should already be 4, so
> > that leaves PREFERRED_STACK_BOUNDARY_DEFAULT is the way to go here.
> 
> This was a minimal fix to support SSE, but Solaris was indeed more radical:
> 
> sol2.h:#undef STACK_REALIGN_DEFAULT
> sol2.h:#define STACK_REALIGN_DEFAULT (TARGET_64BIT ? 0 : 1)
> 
> so we could just mimic it for Windows.

Why use STACK_REALIGN_DEFAULT rather than PREFERRED_STACK_BOUNDARY_DEFAULT?