/* Linear Loop transforms
- Copyright (C) 2003, 2004, 2005 Free Software Foundation, Inc.
+ Copyright (C) 2003, 2004, 2005, 2007 Free Software Foundation, Inc.
Contributed by Daniel Berlin <dberlin@dberlin.org>.
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
-Software Foundation; either version 2, or (at your option) any later
+Software Foundation; either version 3, or (at your option) any later
version.
GCC is distributed in the hope that it will be useful, but WITHOUT ANY
for more details.
You should have received a copy of the GNU General Public License
-along with GCC; see the file COPYING. If not, write to the Free
-Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
-02110-1301, USA. */
+along with GCC; see the file COPYING3. If not see
+<http://www.gnu.org/licenses/>. */
#include "config.h"
#include "rtl.h"
#include "basic-block.h"
#include "diagnostic.h"
+#include "obstack.h"
#include "tree-flow.h"
#include "tree-dump.h"
#include "timevar.h"
struct loop *first_loop,
unsigned int *dependence_steps,
unsigned int *nb_deps_not_carried_by_loop,
- unsigned int *access_strides)
+ double_int *access_strides)
{
unsigned int i, j;
struct data_dependence_relation *ddr;
*dependence_steps = 0;
*nb_deps_not_carried_by_loop = 0;
- *access_strides = 0;
+ *access_strides = double_int_zero;
for (i = 0; VEC_iterate (ddr_p, dependence_relations, i, ddr); i++)
{
for (j = 0; j < DDR_NUM_DIST_VECTS (ddr); j++)
{
- int dist = DDR_DIST_VECT (ddr, j)[loop->depth - first_loop->depth];
+ int dist = DDR_DIST_VECT (ddr, j)[loop_depth (loop) - loop_depth (first_loop)];
if (dist == 0)
(*nb_deps_not_carried_by_loop) += 1;
for (i = 0; VEC_iterate (data_reference_p, datarefs, i, dr); i++)
{
unsigned int it;
+ tree ref = DR_REF (dr);
tree stmt = DR_STMT (dr);
struct loop *stmt_loop = loop_containing_stmt (stmt);
struct loop *inner_loop = first_loop->inner;
-
+
if (inner_loop != stmt_loop
&& !flow_loop_nested_p (inner_loop, stmt_loop))
continue;
- for (it = 0; it < DR_NUM_DIMENSIONS (dr); it++)
+
+ for (it = 0; it < DR_NUM_DIMENSIONS (dr);
+ it++, ref = TREE_OPERAND (ref, 0))
{
tree chrec = DR_ACCESS_FN (dr, it);
- tree tstride = evolution_part_in_loop_num
- (chrec, loop->num);
-
+ tree tstride = evolution_part_in_loop_num (chrec, loop->num);
+ tree array_size = TYPE_SIZE (TREE_TYPE (ref));
+ double_int dstride;
+
if (tstride == NULL_TREE
- || TREE_CODE (tstride) != INTEGER_CST)
+ || array_size == NULL_TREE
+ || TREE_CODE (tstride) != INTEGER_CST
+ || TREE_CODE (array_size) != INTEGER_CST)
continue;
-
- (*access_strides) += int_cst_value (tstride);
+
+ dstride = double_int_mul (tree_to_double_int (array_size),
+ tree_to_double_int (tstride));
+ (*access_strides) = double_int_add (*access_strides, dstride);
}
}
}
VEC (data_reference_p, heap) *datarefs,
struct loop *first_loop)
{
+ bool res;
struct loop *loop_i;
struct loop *loop_j;
unsigned int dependence_steps_i, dependence_steps_j;
- unsigned int access_strides_i, access_strides_j;
+ double_int access_strides_i, access_strides_j;
+ double_int small, large, nb_iter;
+ double_int l1_cache_size, l2_cache_size;
+ int cmp;
unsigned int nb_deps_not_carried_by_i, nb_deps_not_carried_by_j;
struct data_dependence_relation *ddr;
+ if (VEC_length (ddr_p, dependence_relations) == 0)
+ return trans;
+
/* When there is an unknown relation in the dependence_relations, we
know that it is no worth looking at this loop nest: give up. */
ddr = VEC_index (ddr_p, dependence_relations, 0);
if (ddr == NULL || DDR_ARE_DEPENDENT (ddr) == chrec_dont_know)
return trans;
-
+
+ l1_cache_size = uhwi_to_double_int (L1_CACHE_SIZE * 1024);
+ l2_cache_size = uhwi_to_double_int (L2_CACHE_SIZE * 1024);
+
/* LOOP_I is always the outer loop. */
for (loop_j = first_loop->inner;
loop_j;
loop_j = loop_j->inner)
for (loop_i = first_loop;
- loop_i->depth < loop_j->depth;
+ loop_depth (loop_i) < loop_depth (loop_j);
loop_i = loop_i->inner)
{
gather_interchange_stats (dependence_relations, datarefs,
/* Heuristics for loop interchange profitability:
+ 0. Don't transform if the smallest stride is larger than
+ the L2 cache, or if the largest stride multiplied by the
+ number of iterations is smaller than the L1 cache.
+
1. (spatial locality) Inner loops should have smallest
dependence steps.
2. (spatial locality) Inner loops should contain more
dependence relations not carried by the loop.
- 3. (temporal locality) Inner loops should have smallest
+ 3. (temporal locality) Inner loops should have smallest
array access strides.
*/
+
+ cmp = double_int_ucmp (access_strides_i, access_strides_j);
+ small = cmp < 0 ? access_strides_i : access_strides_j;
+ large = cmp < 0 ? access_strides_j : access_strides_i;
+
+ if (double_int_ucmp (small, l2_cache_size) > 0)
+ continue;
+
+ res = cmp < 0 ?
+ estimated_loop_iterations (loop_j, false, &nb_iter):
+ estimated_loop_iterations (loop_i, false, &nb_iter);
+ large = double_int_mul (large, nb_iter);
+
+ if (res && double_int_ucmp (large, l1_cache_size) < 0)
+ continue;
+
if (dependence_steps_i < dependence_steps_j
|| nb_deps_not_carried_by_i > nb_deps_not_carried_by_j
- || access_strides_i < access_strides_j)
+ || cmp < 0)
{
lambda_matrix_row_exchange (LTM_MATRIX (trans),
- loop_i->depth - first_loop->depth,
- loop_j->depth - first_loop->depth);
+ loop_depth (loop_i) - loop_depth (first_loop),
+ loop_depth (loop_j) - loop_depth (first_loop));
/* Validate the resulting matrix. When the transformation
is not valid, reverse to the previous transformation. */
if (!lambda_transform_legal_p (trans, depth, dependence_relations))
lambda_matrix_row_exchange (LTM_MATRIX (trans),
- loop_i->depth - first_loop->depth,
- loop_j->depth - first_loop->depth);
+ loop_depth (loop_i) - loop_depth (first_loop),
+ loop_depth (loop_j) - loop_depth (first_loop));
}
}
return trans;
}
-/* Perform a set of linear transforms on LOOPS. */
+/* Return the number of nested loops in LOOP_NEST, or 0 if the loops
+ are not perfectly nested. */
+
+static unsigned int
+perfect_loop_nest_depth (struct loop *loop_nest)
+{
+ struct loop *temp;
+ unsigned int depth = 1;
+
+ /* If it's not a loop nest, we don't want it. We also don't handle
+ sibling loops properly, which are loops of the following form:
+
+ | for (i = 0; i < 50; i++)
+ | {
+ | for (j = 0; j < 50; j++)
+ | {
+ | ...
+ | }
+ | for (j = 0; j < 50; j++)
+ | {
+ | ...
+ | }
+ | }
+ */
+
+ if (!loop_nest->inner || !single_exit (loop_nest))
+ return 0;
+
+ for (temp = loop_nest->inner; temp; temp = temp->inner)
+ {
+ /* If we have a sibling loop or multiple exit edges, jump ship. */
+ if (temp->next || !single_exit (temp))
+ return 0;
+
+ depth++;
+ }
+
+ return depth;
+}
+
+/* Perform a set of linear transforms on loops. */
void
-linear_transform_loops (struct loops *loops)
+linear_transform_loops (void)
{
- unsigned int i;
+ bool modified = false;
+ loop_iterator li;
VEC(tree,heap) *oldivs = NULL;
VEC(tree,heap) *invariants = NULL;
-
- for (i = 1; i < loops->num; i++)
+ VEC(tree,heap) *remove_ivs = VEC_alloc (tree, heap, 3);
+ struct loop *loop_nest;
+ tree oldiv_stmt;
+ unsigned i;
+
+ FOR_EACH_LOOP (li, loop_nest, 0)
{
unsigned int depth = 0;
VEC (ddr_p, heap) *dependence_relations;
VEC (data_reference_p, heap) *datarefs;
- struct loop *loop_nest = loops->parray[i];
- struct loop *temp;
lambda_loopnest before, after;
lambda_trans_matrix trans;
- bool problem = false;
- bool need_perfect_nest = false;
- /* If it's not a loop nest, we don't want it.
- We also don't handle sibling loops properly,
- which are loops of the following form:
- for (i = 0; i < 50; i++)
- {
- for (j = 0; j < 50; j++)
- {
- ...
- }
- for (j = 0; j < 50; j++)
- {
- ...
- }
- } */
- if (!loop_nest || !loop_nest->inner)
+ struct obstack lambda_obstack;
+ gcc_obstack_init (&lambda_obstack);
+
+ depth = perfect_loop_nest_depth (loop_nest);
+ if (depth == 0)
continue;
+
VEC_truncate (tree, oldivs, 0);
VEC_truncate (tree, invariants, 0);
- depth = 1;
- for (temp = loop_nest->inner; temp; temp = temp->inner)
- {
- /* If we have a sibling loop or multiple exit edges, jump ship. */
- if (temp->next || !temp->single_exit)
- {
- problem = true;
- break;
- }
- depth ++;
- }
- if (problem)
- continue;
- /* Analyze data references and dependence relations using scev. */
-
datarefs = VEC_alloc (data_reference_p, heap, 10);
dependence_relations = VEC_alloc (ddr_p, heap, 10 * 10);
compute_data_dependences_for_loop (loop_nest, true, &datarefs,
{
if (dump_file)
fprintf (dump_file, "Won't transform loop. Optimal transform is the identity transform\n");
- continue;
+ goto free_and_continue;
}
/* Check whether the transformation is legal. */
{
if (dump_file)
fprintf (dump_file, "Can't transform loop, transform is illegal:\n");
- continue;
+ goto free_and_continue;
}
- if (!perfect_nest_p (loop_nest))
- need_perfect_nest = true;
+ before = gcc_loopnest_to_lambda_loopnest (loop_nest, &oldivs,
+ &invariants, &lambda_obstack);
- before = gcc_loopnest_to_lambda_loopnest (loops,
- loop_nest, &oldivs,
- &invariants,
- need_perfect_nest);
if (!before)
- continue;
-
+ goto free_and_continue;
+
if (dump_file)
{
fprintf (dump_file, "Before:\n");
print_lambda_loopnest (dump_file, before, 'i');
}
- after = lambda_loopnest_transform (before, trans);
+ after = lambda_loopnest_transform (before, trans, &lambda_obstack);
if (dump_file)
{
}
lambda_loopnest_to_gcc_loopnest (loop_nest, oldivs, invariants,
- after, trans);
+ &remove_ivs,
+ after, trans, &lambda_obstack);
+ modified = true;
if (dump_file)
fprintf (dump_file, "Successfully transformed loop.\n");
+ free_and_continue:
+ obstack_free (&lambda_obstack, NULL);
free_dependence_relations (dependence_relations);
free_data_refs (datarefs);
}
+ for (i = 0; VEC_iterate (tree, remove_ivs, i, oldiv_stmt); i++)
+ remove_iv (oldiv_stmt);
+
VEC_free (tree, heap, oldivs);
VEC_free (tree, heap, invariants);
+ VEC_free (tree, heap, remove_ivs);
scev_reset ();
- rewrite_into_loop_closed_ssa (NULL, TODO_update_ssa_full_phi);
+
+ if (modified)
+ rewrite_into_loop_closed_ssa (NULL, TODO_update_ssa_full_phi);
}
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