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fix invalid bounds on array refs

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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.

	* graphite-dependences.c (scop_get_reads): Add extra dumps.
	(scop_get_must_writes): Same.
	(scop_get_may_writes): Same.
	(compute_deps): Same.
	* graphite-sese-to-poly.c (bounds_are_valid): New.
	(pdr_add_data_dimensions): Call bounds_are_valid.

	* gfortran.dg/graphite/run-id-3.f90: New.

Co-Authored-By: Sebastian Pop <s.pop@samsung.com>

From-SVN: r231191
This commit is contained in:
Aditya Kumar 2015-12-02 17:11:52 +00:00 • committed by Sebastian Pop
parent 84c36240fc
commit 2e733703c0
5 changed files with 124 additions and 40 deletions
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10
gcc/ChangeLog
View file

@ -1,3 +1,13 @@
2015-12-02 Aditya Kumar <aditya.k7@samsung.com>
Sebastian Pop <s.pop@samsung.com>
* graphite-dependences.c (scop_get_reads): Add extra dumps.
(scop_get_must_writes): Same.
(scop_get_may_writes): Same.
(compute_deps): Same.
* graphite-sese-to-poly.c (bounds_are_valid): New.
(pdr_add_data_dimensions): Call bounds_are_valid.
2015-12-02 Aditya Kumar <aditya.k7@samsung.com>
Sebastian Pop <s.pop@samsung.com>

49
gcc/graphite-dependences.c
View file

@ -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),

88
gcc/graphite-sese-to-poly.c
View file

@ -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 (!bounds_are_valid (ref, low, high))
continue;
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));
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);
/* 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);
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);
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);
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);
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 */
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);
}
/* 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;

5
gcc/testsuite/ChangeLog
View file

@ -1,3 +1,8 @@
2015-12-02 Aditya Kumar <aditya.k7@samsung.com>
Sebastian Pop <s.pop@samsung.com>
* gfortran.dg/graphite/run-id-3.f90: New.
2015-12-02 David Sherwood <david.sherwood@arm.com>
* gcc.target/aarch64/fmaxmin.c: New test.

12
gcc/testsuite/gfortran.dg/graphite/run-id-3.f90 Normal file
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@ -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