On Tue, 19 Jun 2012, Dominique Dhumieres wrote:
> On Tue, 19 Jun 2012, Richard Guenther wrote:
> >
> > > Richard Guenther <rguent...@suse.de> writes:
> > > > We are too eager to bump alignment of some decls when vectorizing.
> > > > The fix is to not bump alignment of decls the user explicitely
> > > > aligned or that are used in an unknown way.
> > >
> > > I thought attribute((__aligned__)) only set a minimum alignment for
> > > variables? Most usees I've seen have been trying to get better
> > > performance from higher alignment, so it might not go down well if the
> > > attribute stopped the vectoriser from increasing the alignment still
> > > further.
> >
> > That's what the documentation says indeed. I'm not sure which part of
> > the patch fixes the ObjC failures where the alignment is part of the ABI
> > (and I suppose ObjC then mis-uses the aligned attribute?).
>
> A quick test shows that
>
> if (DECL_PRESERVE_P (decl))
>
> alone is enough to fix the objc failures, while they are still there if
> one uses only
>
> if (DECL_USER_ALIGN (decl))
Thus, the following.
Bootstrapped and tested on x86_64-unknown-linux-gnu, applied.
Richard.
2012-06-20 Richard Guenther <rguent...@suse.de>
* tree-vect-data-refs.c (vect_can_force_dr_alignment_p):
Allow adjusting alignment of user-aligned decls again.
Index: gcc/tree-vect-data-refs.c
===================================================================
--- gcc/tree-vect-data-refs.c (revision 188817)
+++ gcc/tree-vect-data-refs.c (working copy)
@@ -4731,10 +4720,9 @@ vect_can_force_dr_alignment_p (const_tre
if (TREE_ASM_WRITTEN (decl))
return false;
- /* Do not override explicit alignment set by the user or the alignment
- as specified by the ABI when the used attribute is set. */
- if (DECL_USER_ALIGN (decl)
- || DECL_PRESERVE_P (decl))
+ /* Do not override the alignment as specified by the ABI when the used
+ attribute is set. */
+ if (DECL_PRESERVE_P (decl))
return false;
if (TREE_STATIC (decl))
