path: root/gcc/graphite-dependences.c

/* Data dependence analysis for Graphite.
   Copyright (C) 2009-2015 Free Software Foundation, Inc.
   Contributed by Sebastian Pop <sebastian.pop@amd.com> and
   Konrad Trifunovic <konrad.trifunovic@inria.fr>.

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 3, or (at your option)
any later version.

GCC is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING3.  If not see
<http://www.gnu.org/licenses/>.  */

#include "config.h"

#ifdef HAVE_isl
/* Workaround for GMP 5.1.3 bug, see PR56019.  */
#include <stddef.h>

#include <isl/constraint.h>
#include <isl/set.h>
#include <isl/map.h>
#include <isl/union_map.h>
#include <isl/flow.h>
#include <isl/constraint.h>

#include "system.h"
#include "coretypes.h"
#include "backend.h"
#include "cfghooks.h"
#include "tree.h"
#include "gimple.h"
#include "fold-const.h"
#include "gimple-iterator.h"
#include "tree-ssa-loop.h"
#include "tree-pass.h"
#include "cfgloop.h"
#include "tree-data-ref.h"
#include "graphite-poly.h"


/* Add the constraints from the set S to the domain of MAP.  */

static isl_map *
constrain_domain (isl_map *map, isl_set *s)
{
  isl_space *d = isl_map_get_space (map);
  isl_id *id = isl_space_get_tuple_id (d, isl_dim_in);

  s = isl_set_set_tuple_id (s, id);
  isl_space_free (d);
  return isl_map_intersect_domain (map, s);
}

/* Constrain pdr->accesses with pdr->subscript_sizes and pbb->domain.  */

static isl_map *
add_pdr_constraints (poly_dr_p pdr, poly_bb_p pbb)
{
  isl_map *x = isl_map_intersect_range (isl_map_copy (pdr->accesses),
					isl_set_copy (pdr->subscript_sizes));
  x = constrain_domain (x, isl_set_copy (pbb->domain));
  return x;
}

/* Returns all the memory reads in SCOP.  */

static isl_union_map *
scop_get_reads (scop_p scop, vec<poly_bb_p> pbbs)
{
  int i, j;
  poly_bb_p pbb;
  poly_dr_p pdr;
  isl_space *space = isl_set_get_space (scop->param_context);
  isl_union_map *res = isl_union_map_empty (space);

  FOR_EACH_VEC_ELT (pbbs, i, pbb)
    {
      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));
    }

  return res;
}

/* Returns all the memory must writes in SCOP.  */

static isl_union_map *
scop_get_must_writes (scop_p scop, vec<poly_bb_p> pbbs)
{
  int i, j;
  poly_bb_p pbb;
  poly_dr_p pdr;
  isl_space *space = isl_set_get_space (scop->param_context);
  isl_union_map *res = isl_union_map_empty (space);

  FOR_EACH_VEC_ELT (pbbs, i, pbb)
    {
      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));
    }

  return res;
}

/* Returns all the memory may writes in SCOP.  */

static isl_union_map *
scop_get_may_writes (scop_p scop, vec<poly_bb_p> pbbs)
{
  int i, j;
  poly_bb_p pbb;
  poly_dr_p pdr;
  isl_space *space = isl_set_get_space (scop->param_context);
  isl_union_map *res = isl_union_map_empty (space);

  FOR_EACH_VEC_ELT (pbbs, i, pbb)
    {
      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));
    }

  return res;
}

/* Returns all the original schedules in SCOP.  */

static isl_union_map *
scop_get_original_schedule (scop_p scop, vec<poly_bb_p> pbbs)
{
  int i;
  poly_bb_p pbb;
  isl_space *space = isl_set_get_space (scop->param_context);
  isl_union_map *res = isl_union_map_empty (space);

  FOR_EACH_VEC_ELT (pbbs, i, pbb)
    {
      res = isl_union_map_add_map
	(res, constrain_domain (isl_map_copy (pbb->schedule),
				isl_set_copy (pbb->domain)));
    }

  return res;
}

/* Helper function used on each MAP of a isl_union_map.  Computes the
   maximal output dimension.  */

static isl_stat
max_number_of_out_dimensions (__isl_take isl_map *map, void *user)
{
  int global_max = *((int *) user);
  isl_space *space = isl_map_get_space (map);
  int nb_out = isl_space_dim (space, isl_dim_out);

  if (global_max < nb_out)
    *((int *) user) = nb_out;

  isl_map_free (map);
  isl_space_free (space);
  return isl_stat_ok;
}

/* Extends the output dimension of MAP to MAX dimensions.  */

static __isl_give isl_map *
extend_map (__isl_take isl_map *map, int max)
{
  isl_space *space = isl_map_get_space (map);
  int n = isl_space_dim (space, isl_dim_out);

  isl_space_free (space);
  return isl_map_add_dims (map, isl_dim_out, max - n);
}

/* Structure used to pass parameters to extend_schedule_1.  */

struct extend_schedule_str {
  int max;
  isl_union_map *umap;
};

/* Helper function for extend_schedule.  */

static isl_stat
extend_schedule_1 (__isl_take isl_map *map, void *user)
{
  struct extend_schedule_str *str = (struct extend_schedule_str *) user;
  str->umap = isl_union_map_add_map (str->umap, extend_map (map, str->max));
  return isl_stat_ok;
}

/* Return a relation that has uniform output dimensions.  */

static __isl_give isl_union_map *
extend_schedule (__isl_take isl_union_map *x)
{
  int max = 0;
  struct extend_schedule_str str;

  isl_union_map_foreach_map (x, max_number_of_out_dimensions, (void *) &max);
  str.max = max;
  str.umap = isl_union_map_empty (isl_union_map_get_space (x));
  isl_union_map_foreach_map (x, extend_schedule_1, (void *) &str);
  isl_union_map_free (x);
  return str.umap;
}

/* Applies SCHEDULE to the in and out dimensions of the dependences
   DEPS and return the resulting relation.  */

static isl_map *
apply_schedule_on_deps (__isl_keep isl_union_map *schedule,
			__isl_keep isl_union_map *deps)
{
  isl_map *x;
  isl_union_map *ux, *trans;

  trans = isl_union_map_copy (schedule);
  trans = extend_schedule (trans);
  ux = isl_union_map_copy (deps);
  ux = isl_union_map_apply_domain (ux, isl_union_map_copy (trans));
  ux = isl_union_map_apply_range (ux, trans);
  if (isl_union_map_is_empty (ux))
    {
      isl_union_map_free (ux);
      return NULL;
    }
  x = isl_map_from_union_map (ux);

  return x;
}

/* Return true when DEPS is non empty and the intersection of LEX with
   the DEPS transformed by SCHEDULE is non empty.  LEX is the relation
   in which all the inputs before DEPTH occur at the same time as the
   output, and the input at DEPTH occurs before output.  */

bool
carries_deps (__isl_keep isl_union_map *schedule,
	      __isl_keep isl_union_map *deps,
	      int depth)
{
  bool res;
  int i;
  isl_space *space;
  isl_map *lex, *x;
  isl_constraint *ineq;

  if (isl_union_map_is_empty (deps))
    return false;

  x = apply_schedule_on_deps (schedule, deps);
  if (x == NULL)
    return false;
  space = isl_map_get_space (x);
  space = isl_space_range (space);
  lex = isl_map_lex_le (space);
  space = isl_map_get_space (x);
  ineq = isl_inequality_alloc (isl_local_space_from_space (space));

  for (i = 0; i < depth - 1; i++)
    lex = isl_map_equate (lex, isl_dim_in, i, isl_dim_out, i);

  /* in + 1 <= out  */
  ineq = isl_constraint_set_coefficient_si (ineq, isl_dim_out, depth - 1, 1);
  ineq = isl_constraint_set_coefficient_si (ineq, isl_dim_in, depth - 1, -1);
  ineq = isl_constraint_set_constant_si (ineq, -1);
  lex = isl_map_add_constraint (lex, ineq);
  x = isl_map_intersect (x, lex);
  res = !isl_map_is_empty (x);

  isl_map_free (x);
  return res;
}

/* Compute the original data dependences in SCOP for all the reads and
   writes in PBBS.  */

static void
compute_deps (scop_p scop, vec<poly_bb_p> pbbs,
	      isl_union_map **must_raw,
	      isl_union_map **may_raw,
	      isl_union_map **must_raw_no_source,
	      isl_union_map **may_raw_no_source,
	      isl_union_map **must_war,
	      isl_union_map **may_war,
	      isl_union_map **must_war_no_source,
	      isl_union_map **may_war_no_source,
	      isl_union_map **must_waw,
	      isl_union_map **may_waw,
	      isl_union_map **must_waw_no_source,
	      isl_union_map **may_waw_no_source)
{
  isl_union_map *reads = scop_get_reads (scop, pbbs);
  isl_union_map *must_writes = scop_get_must_writes (scop, pbbs);
  isl_union_map *may_writes = scop_get_may_writes (scop, pbbs);
  isl_union_map *all_writes = isl_union_map_union
    (isl_union_map_copy (must_writes), isl_union_map_copy (may_writes));
  isl_space *space = isl_union_map_get_space (all_writes);
  isl_union_map *empty = isl_union_map_empty (space);
  isl_union_map *original = scop_get_original_schedule (scop, pbbs);

  isl_union_map_compute_flow (isl_union_map_copy (reads),
			      isl_union_map_copy (must_writes),
			      isl_union_map_copy (may_writes),
			      isl_union_map_copy (original),
			      must_raw, may_raw, must_raw_no_source,
			      may_raw_no_source);
  isl_union_map_compute_flow (isl_union_map_copy (all_writes),
			      reads, empty,
			      isl_union_map_copy (original),
			      must_war, may_war, must_war_no_source,
			      may_war_no_source);
  isl_union_map_compute_flow (all_writes, must_writes, may_writes,
			      original,
			      must_waw, may_waw, must_waw_no_source,
			      may_waw_no_source);
}

isl_union_map *
scop_get_dependences (scop_p scop)
{
  isl_union_map *dependences;

  if (!scop->must_raw)
    compute_deps (scop, scop->pbbs,
		  &scop->must_raw, &scop->may_raw,
		  &scop->must_raw_no_source, &scop->may_raw_no_source,
		  &scop->must_war, &scop->may_war,
		  &scop->must_war_no_source, &scop->may_war_no_source,
		  &scop->must_waw, &scop->may_waw,
		  &scop->must_waw_no_source, &scop->may_waw_no_source);

  dependences = isl_union_map_copy (scop->must_raw);
  dependences = isl_union_map_union (dependences,
				     isl_union_map_copy (scop->must_war));
  dependences = isl_union_map_union (dependences,
				     isl_union_map_copy (scop->must_waw));
  dependences = isl_union_map_union (dependences,
				     isl_union_map_copy (scop->may_raw));
  dependences = isl_union_map_union (dependences,
				     isl_union_map_copy (scop->may_war));
  dependences = isl_union_map_union (dependences,
				     isl_union_map_copy (scop->may_waw));

  if (dump_file)
    {
      fprintf (dump_file, "data dependences (\n");
      print_isl_union_map (dump_file, dependences);
      fprintf (dump_file, ")\n");
    }

  return dependences;
}

#endif /* HAVE_isl */