On Thu, 4 Aug 2011, Richard Guenther wrote:
> On Wed, 3 Aug 2011, Mikael Morin wrote:
>
> > Hello,
> >
> > On Wednesday 03 August 2011 15:47:37 Richard Guenther wrote:
> > > Comments? Any idea why reversing the loop would break?
> >
> > Yes, the list of scalarized expressions has to be created in the same order
> > it
> > is consumed. Here the scalarized expressions are array indexes to be
> > precomputed out of the loop.
> > The attached patch seems to work (the interesting part is in
> > gfc_walk_variable_expr).
>
> Ah, thanks. I'll work from there to revise the patch.
The following is almost identical to your proposal.
Bootstrapped and tested on x86_64-unknown-linux-gnu, ok for trunk?
Thanks,
Richard.
2011-08-03 Richard Guenther <rguent...@suse.de>
PR fortran/49957
* trans-array.c (add_to_offset): New function.
(gfc_conv_array_ref): Build the array index expression in optimally
associated order.
(gfc_walk_variable_expr): Adjust for the backward walk.
* gfortran.dg/vect/O3-pr49957.f: New testcase.
Index: gcc/fortran/trans-array.c
===================================================================
--- gcc/fortran/trans-array.c (revision 177357)
+++ gcc/fortran/trans-array.c (working copy)
@@ -2622,6 +2622,22 @@ gfc_conv_tmp_array_ref (gfc_se * se)
gfc_advance_se_ss_chain (se);
}
+/* Add T to the offset pair *OFFSET, *CST_OFFSET. */
+
+static void
+add_to_offset (tree *cst_offset, tree *offset, tree t)
+{
+ if (TREE_CODE (t) == INTEGER_CST)
+ *cst_offset = int_const_binop (PLUS_EXPR, *cst_offset, t);
+ else
+ {
+ if (!integer_zerop (*offset))
+ *offset = fold_build2_loc (input_location, PLUS_EXPR,
+ gfc_array_index_type, *offset, t);
+ else
+ *offset = t;
+ }
+}
/* Build an array reference. se->expr already holds the array descriptor.
This should be either a variable, indirect variable reference or component
@@ -2634,7 +2650,7 @@ gfc_conv_array_ref (gfc_se * se, gfc_arr
locus * where)
{
int n;
- tree index;
+ tree offset, cst_offset;
tree tmp;
tree stride;
gfc_se indexse;
@@ -2669,10 +2685,12 @@ gfc_conv_array_ref (gfc_se * se, gfc_arr
return;
}
- index = gfc_index_zero_node;
+ cst_offset = offset = gfc_index_zero_node;
+ add_to_offset (&cst_offset, &offset, gfc_conv_array_offset (se->expr));
- /* Calculate the offsets from all the dimensions. */
- for (n = 0; n < ar->dimen; n++)
+ /* Calculate the offsets from all the dimensions. Make sure to associate
+ the final offset so that we form a chain of loop invariant summands. */
+ for (n = ar->dimen - 1; n >= 0; n--)
{
/* Calculate the index for this dimension. */
gfc_init_se (&indexse, se);
@@ -2741,19 +2759,17 @@ gfc_conv_array_ref (gfc_se * se, gfc_arr
indexse.expr, stride);
/* And add it to the total. */
- index = fold_build2_loc (input_location, PLUS_EXPR,
- gfc_array_index_type, index, tmp);
+ add_to_offset (&cst_offset, &offset, tmp);
}
- tmp = gfc_conv_array_offset (se->expr);
- if (!integer_zerop (tmp))
- index = fold_build2_loc (input_location, PLUS_EXPR,
- gfc_array_index_type, index, tmp);
+ if (!integer_zerop (cst_offset))
+ offset = fold_build2_loc (input_location, PLUS_EXPR,
+ gfc_array_index_type, offset, cst_offset);
/* Access the calculated element. */
tmp = gfc_conv_array_data (se->expr);
tmp = build_fold_indirect_ref (tmp);
- se->expr = gfc_build_array_ref (tmp, index, sym->backend_decl);
+ se->expr = gfc_build_array_ref (tmp, offset, sym->backend_decl);
}
@@ -7575,7 +7591,7 @@ gfc_walk_variable_expr (gfc_ss * ss, gfc
switch (ar->type)
{
case AR_ELEMENT:
- for (n = 0; n < ar->dimen + ar->codimen; n++)
+ for (n = ar->dimen + ar->codimen - 1; n >= 0; n--)
{
newss = gfc_get_ss ();
newss->type = GFC_SS_SCALAR;
Index: gcc/testsuite/gfortran.dg/vect/O3-pr49957.f
===================================================================
--- gcc/testsuite/gfortran.dg/vect/O3-pr49957.f (revision 0)
+++ gcc/testsuite/gfortran.dg/vect/O3-pr49957.f (revision 0)
@@ -0,0 +1,16 @@
+! { dg-do compile }
+! { dg-require-effective-target vect_double }
+ subroutine shell(nx,ny,nz,q,dq)
+ implicit none
+ integer i,j,k,l,nx,ny,nz
+ real*8 q(5,nx,ny),dq(5,nx,ny)
+ do j=1,ny
+ do i=1,nx
+ do l=1,5
+ q(l,i,j)=q(l,i,j)+dq(l,i,j)
+ enddo
+ enddo
+ enddo
+ return
+ end
+! { dg-final { scan-tree-dump "vectorized 1 loops" "vect" { xfail
vect_no_align } } }
