[Bug rtl-optimization/40838] gcc shouldn't assume that the stack is aligned

["hjl dot tools at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #59 from hjl dot tools at gmail dot com  2009-10-15 20:54 -------
(In reply to comment #58)
> (In reply to comment #53)
> > Created an attachment (id=18656)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=18656&action=view) [edit]
> > An updated patch for gcc 4.4
> 
> Seamonkey is correct with that patch. But it fails with structures containing
> sse vector, i.e. this. My patch (in comment #46) handles this case correctly
> (it reallign the stack if any structure on it has alignment at least 16), so
> should we submit that patch instead?
> 
> I think it's wrong to add alignment test to the autovectorizer because vector
> data types can be created explicitly without autovectorizer.
> 
> Mikulas
> 
> 
> typedef int v4si __attribute__ ((vector_size (16)));
> 
> struct x {
>         v4si v;
>         v4si w;
> };
> 
> void y(void *);
> 
> v4si x(void)
> {
>         struct x x;
>         y(&x);
> }
> 

Why should gcc align the stack when SSE registers aren't used
at all?


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40838