Jakub Jelinek <jakub@redhat.com> wrote on 21/11/2011 07:25:10 PM:

> From: Jakub Jelinek <jakub@redhat.com>
> To: Razya Ladelsky/Haifa/IBM@IBMIL
> Cc: GCC Patches <gcc-patches@gcc.gnu.org>, Richard Guenther 
> <richard.guenther@gmail.com>
> Date: 21/11/2011 07:25 PM
> Subject: Re: [PATCH, take 2] Fix PR tree-optimization/49960 ,Fix 
> self data dependence
> 
> On Mon, Nov 21, 2011 at 06:56:55PM +0200, Razya Ladelsky wrote:
> > I have some non-affine cases for which compute_affine_dependence is 
called 
> > (as it is called for 
> > ALL dependences from compte_all_depepndences()), and no harm is done.
> > I looked a little bit closer into the code, and this is what happens 
for 
> > non affine accesses:
> > 
> > initialize_data_dependence_relation() assigns 
> > DDR_ARE_DEPENDENT (res) = chrec_dont_know for the dr.
> 
> It can be chrec_known too (that's actually the only interesting case for 
us
> unless it is a read-read ddr), but you're right that likely
> object_address_invariant_in_loop_p should be false.
> 
> > Then, compute_affine_depepndence()
> > tests if (DDR_ARE_DEPENDENT (ddr) == NULL_TREE), and does nothing 
> > otherwise.
> > Since the dr was initialized with chrec_dont_know, no harm is done.
> > 
> > Anyway, since it is useless for your gather case, I'll just remove it, 

> > along with compute_self_dependence().
> > 
> > OK?
> 
> Yes, patch preapproved.
> 
>    Jakub
> 

Hi,

Going to commit this patch today.
I bootstrapped and regtested on  ppc64-suse-linux.

ChangeLog:
 
        * tree-data-ref.c (initialize_data_dependence_relation): Update 
comment for the 
        self dependence case.
        (compute_self_dependence): Remove.
        * tree-vect-data-refs.c (vect_analyze_data_refs): Remove call to 
        compute_self_dependenc. 


Thanks,
Razya