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.
---
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
--
1.9.1
