[Bug tree-optimization/41464] vector loads are unnecessarily split into high and low loads

["irar at il dot ibm dot com" <gcc-bugzilla@gcc.gnu.org>]

------- Comment #6 from irar at il dot ibm dot com  2009-09-27 09:56 -------
(In reply to comment #5)
> > 
> > "aligned to" refers to the offset misalignment and not to the misalignment of
> > base.
> Hmm, I believe it refers to base + offset + constant offset.
tree-data-refs.h:
  /* Alignment information.  ALIGNED_TO is set to the largest power of two
     that divides OFFSET.  */
  tree aligned_to;

tree-dat-refs.c:
DR_ALIGNED_TO (dr) = size_int (highest_pow2_factor (offset_iv.base));


> > attribute aligned works only for arrays, i.e., declarations, and not for
> > pointer arguments.
> I have to check that - I believe that in principle it should work.
> > For pointers the vectorizer only checks TYPE_ALIGN_UNIT of
> > the base type.
> That should be ok.  

But we need TYPE_ALIGN_UNIT to be 16, and we are checking scalar type here, so
without user defined alignment it will be 4.

Ira

> I guess I have to see what's going on here.
> Richard.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41464