On December 2, 2015 5:34:54 PM GMT+01:00, Sebastian Pop <s....@samsung.com>
wrote:
>While enabling graphite in -O3 we found a Fortran testcase that fails
>because the max of the type domain is -1. We used to add that as a
>constraint
>to the elements accessed by the array, leading to a unfeasible
>constraint:
>0 <= i <= -1. Having that constraint, drops the data reference as that
>says
>that there are no elements accessed in the array.
But either that is the case or the frontend has a bug and should be fixed. So
your patch doesn't make any sense.
Richard.
>---
> gcc/graphite-dependences.c | 49 ++++++++++++-
>gcc/graphite-sese-to-poly.c | 98
>++++++++++++++-----------
> gcc/testsuite/gfortran.dg/graphite/run-id-3.f90 | 12 +++
> 3 files changed, 114 insertions(+), 45 deletions(-)
> create mode 100644 gcc/testsuite/gfortran.dg/graphite/run-id-3.f90
>
>diff --git a/gcc/graphite-dependences.c b/gcc/graphite-dependences.c
>index fcc771b..bb81ae3 100644
>--- a/gcc/graphite-dependences.c
>+++ b/gcc/graphite-dependences.c
>@@ -87,7 +87,11 @@ scop_get_reads (scop_p scop, vec<poly_bb_p> pbbs)
> {
> FOR_EACH_VEC_ELT (PBB_DRS (pbb), j, pdr)
> if (pdr_read_p (pdr))
>- res = isl_union_map_add_map (res, add_pdr_constraints (pdr, pbb));
>+ {
>+ if (dump_file)
>+ print_pdr (dump_file, pdr);
>+ res = isl_union_map_add_map (res, add_pdr_constraints (pdr,
>pbb));
>+ }
> }
>
> return res;
>@@ -108,7 +112,11 @@ scop_get_must_writes (scop_p scop, vec<poly_bb_p>
>pbbs)
> {
> FOR_EACH_VEC_ELT (PBB_DRS (pbb), j, pdr)
> if (pdr_write_p (pdr))
>- res = isl_union_map_add_map (res, add_pdr_constraints (pdr, pbb));
>+ {
>+ if (dump_file)
>+ print_pdr (dump_file, pdr);
>+ res = isl_union_map_add_map (res, add_pdr_constraints (pdr,
>pbb));
>+ }
> }
>
> return res;
>@@ -129,7 +137,12 @@ scop_get_may_writes (scop_p scop, vec<poly_bb_p>
>pbbs)
> {
> FOR_EACH_VEC_ELT (PBB_DRS (pbb), j, pdr)
> if (pdr_may_write_p (pdr))
>- res = isl_union_map_add_map (res, add_pdr_constraints (pdr, pbb));
>+ {
>+ if (dump_file)
>+ print_pdr (dump_file, pdr);
>+
>+ res = isl_union_map_add_map (res, add_pdr_constraints (pdr,
>pbb));
>+ }
> }
>
> return res;
>@@ -313,6 +326,36 @@ compute_deps (scop_p scop, vec<poly_bb_p> pbbs,
> isl_union_map *empty = isl_union_map_empty (space);
> isl_union_map *original = scop_get_original_schedule (scop, pbbs);
>
>+ if (dump_file)
>+ {
>+ fprintf (dump_file, "\n--- Documentation for datarefs dump:
>---\n");
>+ fprintf (dump_file, "Statements on the iteration domain are
>mapped to"
>+ " array references.\n");
>+ fprintf (dump_file, " To read the following data
>references:\n\n");
>+ fprintf (dump_file, " S_5[i0] -> [106] : i0 >= 0 and i0 <=
>3\n");
>+ fprintf (dump_file, " S_8[i0] -> [1, i0] : i0 >= 0 and i0 <=
>3\n\n");
>+
>+ fprintf (dump_file, " S_5[i0] is the dynamic instance of
>statement"
>+ " bb_5 in a loop that accesses all iterations 0 <= i0 <=
>3.\n");
>+ fprintf (dump_file, " [1, i0] is a 'memref' with alias set 1"
>+ " and first subscript access i0.\n");
>+ fprintf (dump_file, " [106] is a 'scalar reference' which is
>the sum of"
>+ " SSA_NAME_VERSION 6"
>+ " and --param graphite-max-arrays-per-scop=100\n");
>+ fprintf (dump_file, "-----------------------\n\n");
>+
>+ fprintf (dump_file, "data references (\n");
>+ fprintf (dump_file, " reads: ");
>+ print_isl_union_map (dump_file, reads);
>+ fprintf (dump_file, " must_writes: ");
>+ print_isl_union_map (dump_file, must_writes);
>+ fprintf (dump_file, " may_writes: ");
>+ print_isl_union_map (dump_file, may_writes);
>+ fprintf (dump_file, " all_writes: ");
>+ print_isl_union_map (dump_file, all_writes);
>+ fprintf (dump_file, ")\n");
>+ }
>+
> isl_union_map_compute_flow (isl_union_map_copy (reads),
> isl_union_map_copy (must_writes),
> isl_union_map_copy (may_writes),
>diff --git a/gcc/graphite-sese-to-poly.c b/gcc/graphite-sese-to-poly.c
>index 7ef01fb..887c212 100644
>--- a/gcc/graphite-sese-to-poly.c
>+++ b/gcc/graphite-sese-to-poly.c
>@@ -922,6 +922,33 @@ pdr_add_memory_accesses (isl_map *acc, dr_info
>&dri)
> return acc;
> }
>
>+/* Return true when the LOW and HIGH bounds of an array reference REF
>are valid
>+ to extract constraints on accessed elements of the array.
>Returning false is
>+ the conservative answer. */
>+
>+static bool
>+bounds_are_valid (tree ref, tree low, tree high)
>+{
>+ if (!high)
>+ return false;
>+
>+ if (!tree_fits_shwi_p (low)
>+ || !tree_fits_shwi_p (high))
>+ return false;
>+
>+ /* 1-element arrays at end of structures may extend over
>+ their declared size. */
>+ if (array_at_struct_end_p (ref)
>+ && operand_equal_p (low, high, 0))
>+ return false;
>+
>+ /* Fortran has some arrays where high bound is -1 and low is 0. */
>+ if (integer_onep (fold_build2 (LT_EXPR, boolean_type_node, high,
>low)))
>+ return false;
>+
>+ return true;
>+}
>+
> /* Add constrains representing the size of the accessed data to the
> ACCESSES polyhedron. ACCESSP_NB_DIMS is the dimension of the
> ACCESSES polyhedron, DOM_NB_DIMS is the dimension of the iteration
>@@ -942,48 +969,35 @@ pdr_add_data_dimensions (isl_set
>*subscript_sizes, scop_p scop,
> tree low = array_ref_low_bound (ref);
> tree high = array_ref_up_bound (ref);
>
>- /* XXX The PPL code dealt separately with
>- subscript - low >= 0 and high - subscript >= 0 in case one of
>- the two bounds isn't known. Do the same here? */
>-
>- if (tree_fits_shwi_p (low)
>- && high
>- && tree_fits_shwi_p (high)
>- /* 1-element arrays at end of structures may extend over
>- their declared size. */
>- && !(array_at_struct_end_p (ref)
>- && operand_equal_p (low, high, 0)))
>- {
>- isl_id *id;
>- isl_aff *aff;
>- isl_set *univ, *lbs, *ubs;
>- isl_pw_aff *index;
>- isl_set *valid;
>- isl_space *space = isl_set_get_space (subscript_sizes);
>- isl_pw_aff *lb = extract_affine_int (low, isl_space_copy (space));
>- isl_pw_aff *ub = extract_affine_int (high, isl_space_copy (space));
>-
>- /* high >= 0 */
>- valid = isl_pw_aff_nonneg_set (isl_pw_aff_copy (ub));
>- valid = isl_set_project_out (valid, isl_dim_set, 0,
>- isl_set_dim (valid, isl_dim_set));
>- scop->param_context = isl_set_intersect (scop->param_context,
>valid);
>-
>- aff = isl_aff_zero_on_domain (isl_local_space_from_space (space));
>- aff = isl_aff_add_coefficient_si (aff, isl_dim_in, i + 1, 1);
>- univ = isl_set_universe (isl_space_domain (isl_aff_get_space
>(aff)));
>- index = isl_pw_aff_alloc (univ, aff);
>-
>- id = isl_set_get_tuple_id (subscript_sizes);
>- lb = isl_pw_aff_set_tuple_id (lb, isl_dim_in, isl_id_copy (id));
>- ub = isl_pw_aff_set_tuple_id (ub, isl_dim_in, id);
>-
>- /* low <= sub_i <= high */
>- lbs = isl_pw_aff_ge_set (isl_pw_aff_copy (index), lb);
>- ubs = isl_pw_aff_le_set (index, ub);
>- subscript_sizes = isl_set_intersect (subscript_sizes, lbs);
>- subscript_sizes = isl_set_intersect (subscript_sizes, ubs);
>- }
>+ if (!bounds_are_valid (ref, low, high))
>+ continue;
>+
>+ isl_space *space = isl_set_get_space (subscript_sizes);
>+ isl_pw_aff *lb = extract_affine_int (low, isl_space_copy
>(space));
>+ isl_pw_aff *ub = extract_affine_int (high, isl_space_copy
>(space));
>+
>+ /* high >= 0 */
>+ isl_set *valid = isl_pw_aff_nonneg_set (isl_pw_aff_copy (ub));
>+ valid = isl_set_project_out (valid, isl_dim_set, 0,
>+ isl_set_dim (valid, isl_dim_set));
>+ scop->param_context = isl_set_intersect (scop->param_context,
>valid);
>+
>+ isl_aff *aff
>+ = isl_aff_zero_on_domain (isl_local_space_from_space (space));
>+ aff = isl_aff_add_coefficient_si (aff, isl_dim_in, i + 1, 1);
>+ isl_set *univ
>+ = isl_set_universe (isl_space_domain (isl_aff_get_space (aff)));
>+ isl_pw_aff *index = isl_pw_aff_alloc (univ, aff);
>+
>+ isl_id *id = isl_set_get_tuple_id (subscript_sizes);
>+ lb = isl_pw_aff_set_tuple_id (lb, isl_dim_in, isl_id_copy (id));
>+ ub = isl_pw_aff_set_tuple_id (ub, isl_dim_in, id);
>+
>+ /* low <= sub_i <= high */
>+ isl_set *lbs = isl_pw_aff_ge_set (isl_pw_aff_copy (index), lb);
>+ isl_set *ubs = isl_pw_aff_le_set (index, ub);
>+ subscript_sizes = isl_set_intersect (subscript_sizes, lbs);
>+ subscript_sizes = isl_set_intersect (subscript_sizes, ubs);
> }
>
> return subscript_sizes;
>diff --git a/gcc/testsuite/gfortran.dg/graphite/run-id-3.f90
>b/gcc/testsuite/gfortran.dg/graphite/run-id-3.f90
>new file mode 100644
>index 0000000..54139ef
>--- /dev/null
>+++ b/gcc/testsuite/gfortran.dg/graphite/run-id-3.f90
>@@ -0,0 +1,12 @@
>+! { dg-do run }
>+! { dg-options "-ffrontend-optimize -floop-nest-optimize" }
>+! PR 56872 - wrong front-end optimization with a single constructor.
>+! Original bug report by Rich Townsend.
>+ integer :: k
>+ real :: s
>+ integer :: m
>+ s = 2.0
>+ m = 4
>+ res = SUM([(s**(REAL(k-1)/REAL(m-1)),k=1,m)])
>+ if (abs(res - 5.84732246) > 1e-6) call abort
>+ end
