Re: pthreads-win32 2.8.0, stack alignment, and SSE code

[Sébastien Kunz-Jacques <kunzjacq at yahoo dot fr>]

regarding my initial problem of making ATLAS work with pthread-win32, a 
solution was found with solves all ATLAS alignment problems without 
having to patch pthreads: it  is to add the option 

-mpreferred-stack-boundary=2

to the gcc ATLAS flags ( see 
http://sourceforge.net/tracker/index.php?func=detail&aid=2170667&group_id=23725&atid=379483 
). This should work with any client lib of pthreads. More generally it 
makes gcc more compliant with a platform such as win32 whose ABI only 
guarantees 4-byte stack alignment.

I still think aligning the stack of newly created threads on a 16-byte 
boundary would be a useful option for pthread-win32.

Ross Johnson a écrit :
> I've just read this whole thread for the first time. I haven't come 
> across this issue of alignment on Intel processors before so I thought 
> I'd better at least Google around the subject before replying. 
> Unfortunately I've got to run now and won't be reading mail for 
> another 5 days or so.
>
> I would very likely include the patch as a build option, so I'm 
> wondering if you've tried building the library with the -mstackrealign 
> gcc flag that does the same thing as force_align_arg_pointer (I 
> haven't tried either of these but read about it).
>
> Ross
>
> Ramiro Polla wrote:
> > Sébastien Kunz-Jacques wrote:
> > > If for some reason it is not desirable to patch the lib, would it be 
> > > possible to have some easy to see disclaimer added about this 
> > > problem somewhere?
> >
> > Oh, that's not my call =). It's up to Ross Johnson to decide. I 
> > simply had lots of free time today and decided to share my ideas. You 
> > can disregard anything I said... (although I think they might help).
> >
> > The patch is not necessary because 4-byte alignment is enough for x86 
> > and Win32, but it certainly might help some people to avoid a 
> > headache like you mentioned.
> >
> > Ramiro Polla