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/* DDG - Data Dependence Graph implementation.

   Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009

   Free Software Foundation, Inc.

   Contributed by Ayal Zaks and Mustafa Hagog <zaks,mustafa@il.ibm.com>

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"

#include "system.h"

#include "coretypes.h"

#include "tm.h"

#include "toplev.h"

#include "rtl.h"

#include "tm_p.h"

#include "hard-reg-set.h"

#include "regs.h"

#include "function.h"

#include "flags.h"

#include "insn-config.h"

#include "insn-attr.h"

#include "except.h"

#include "recog.h"

#include "sched-int.h"

#include "target.h"

#include "cfglayout.h"

#include "cfgloop.h"

#include "sbitmap.h"

#include "expr.h"

#include "bitmap.h"

#include "ddg.h"

#ifdef INSN_SCHEDULING

/* A flag indicating that a ddg edge belongs to an SCC or not.  */

enum edge_flag {NOT_IN_SCC = 0, IN_SCC};

/* Forward declarations.  */

static void add_backarc_to_ddg (ddg_ptr, ddg_edge_ptr);

static void add_backarc_to_scc (ddg_scc_ptr, ddg_edge_ptr);

static void add_scc_to_ddg (ddg_all_sccs_ptr, ddg_scc_ptr);

static void create_ddg_dep_from_intra_loop_link (ddg_ptr, ddg_node_ptr,

                                                 ddg_node_ptr, dep_t);

static void create_ddg_dep_no_link (ddg_ptr, ddg_node_ptr, ddg_node_ptr,

                                    dep_type, dep_data_type, int);

static ddg_edge_ptr create_ddg_edge (ddg_node_ptr, ddg_node_ptr, dep_type,

                                     dep_data_type, int, int);

static void add_edge_to_ddg (ddg_ptr g, ddg_edge_ptr);

/* Auxiliary variable for mem_read_insn_p/mem_write_insn_p.  */

static bool mem_ref_p;

/* Auxiliary function for mem_read_insn_p.  */

static int

mark_mem_use (rtx *x, void *data ATTRIBUTE_UNUSED)

{

  if (MEM_P (*x))

    mem_ref_p = true;

  return 0;

}

/* Auxiliary function for mem_read_insn_p.  */

static void

mark_mem_use_1 (rtx *x, void *data)

{

  for_each_rtx (x, mark_mem_use, data);

}

/* Returns nonzero if INSN reads from memory.  */

static bool

mem_read_insn_p (rtx insn)

{

  mem_ref_p = false;

  note_uses (&PATTERN (insn), mark_mem_use_1, NULL);

  return mem_ref_p;

}

static void

mark_mem_store (rtx loc, const_rtx setter ATTRIBUTE_UNUSED, void *data ATTRIBUTE_UNUSED)

{

  if (MEM_P (loc))

    mem_ref_p = true;

}

/* Returns nonzero if INSN writes to memory.  */

static bool

mem_write_insn_p (rtx insn)

{

  mem_ref_p = false;

  note_stores (PATTERN (insn), mark_mem_store, NULL);

  return mem_ref_p;

}

/* Returns nonzero if X has access to memory.  */

static bool

rtx_mem_access_p (rtx x)

{

  int i, j;

  const char *fmt;

  enum rtx_code code;

  if (x == 0)

    return false;

  if (MEM_P (x))

    return true;

  code = GET_CODE (x);

  fmt = GET_RTX_FORMAT (code);

  for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)

    {

      if (fmt[i] == 'e')

        {

          if (rtx_mem_access_p (XEXP (x, i)))

            return true;

        }

      else if (fmt[i] == 'E')

        for (j = 0; j < XVECLEN (x, i); j++)

          {

            if (rtx_mem_access_p (XVECEXP (x, i, j)))

              return true;

          }

    }

  return false;

}

/* Returns nonzero if INSN reads to or writes from memory.  */

static bool

mem_access_insn_p (rtx insn)

{

  return rtx_mem_access_p (PATTERN (insn));

}

/* Computes the dependence parameters (latency, distance etc.), creates

   a ddg_edge and adds it to the given DDG.  */

static void

create_ddg_dep_from_intra_loop_link (ddg_ptr g, ddg_node_ptr src_node,

                                     ddg_node_ptr dest_node, dep_t link)

{

  ddg_edge_ptr e;

  int latency, distance = 0;

  dep_type t = TRUE_DEP;

  dep_data_type dt = (mem_access_insn_p (src_node->insn)

                      && mem_access_insn_p (dest_node->insn) ? MEM_DEP

                                                             : REG_DEP);

  gcc_assert (src_node->cuid < dest_node->cuid);

  gcc_assert (link);

  /* Note: REG_DEP_ANTI applies to MEM ANTI_DEP as well!!  */

  if (DEP_TYPE (link) == REG_DEP_ANTI)

    t = ANTI_DEP;

  else if (DEP_TYPE (link) == REG_DEP_OUTPUT)

    t = OUTPUT_DEP;

  gcc_assert (!DEBUG_INSN_P (dest_node->insn) || t == ANTI_DEP);

  gcc_assert (!DEBUG_INSN_P (src_node->insn) || t == ANTI_DEP);

  /* We currently choose not to create certain anti-deps edges and

     compensate for that by generating reg-moves based on the life-range

     analysis.  The anti-deps that will be deleted are the ones which

     have true-deps edges in the opposite direction (in other words

     the kernel has only one def of the relevant register).  TODO:

     support the removal of all anti-deps edges, i.e. including those

     whose register has multiple defs in the loop.  */

  if (flag_modulo_sched_allow_regmoves && (t == ANTI_DEP && dt == REG_DEP))

    {

      rtx set;

      set = single_set (dest_node->insn);

      /* TODO: Handle registers that REG_P is not true for them, i.e.

         subregs and special registers.  */

      if (set && REG_P (SET_DEST (set)))

        {

          int regno = REGNO (SET_DEST (set));

          df_ref first_def;

          struct df_rd_bb_info *bb_info = DF_RD_BB_INFO (g->bb);

          first_def = df_bb_regno_first_def_find (g->bb, regno);

          gcc_assert (first_def);

          if (bitmap_bit_p (bb_info->gen, DF_REF_ID (first_def)))

            return;

        }

    }

   latency = dep_cost (link);

   e = create_ddg_edge (src_node, dest_node, t, dt, latency, distance);

   add_edge_to_ddg (g, e);

}

/* The same as the above function, but it doesn't require a link parameter.  */

static void

create_ddg_dep_no_link (ddg_ptr g, ddg_node_ptr from, ddg_node_ptr to,

                        dep_type d_t, dep_data_type d_dt, int distance)

{

  ddg_edge_ptr e;

  int l;

  enum reg_note dep_kind;

  struct _dep _dep, *dep = &_dep;

  gcc_assert (!DEBUG_INSN_P (to->insn) || d_t == ANTI_DEP);

  gcc_assert (!DEBUG_INSN_P (from->insn) || d_t == ANTI_DEP);

  if (d_t == ANTI_DEP)

    dep_kind = REG_DEP_ANTI;

  else if (d_t == OUTPUT_DEP)

    dep_kind = REG_DEP_OUTPUT;

  else

    {

      gcc_assert (d_t == TRUE_DEP);

      dep_kind = REG_DEP_TRUE;

    }

  init_dep (dep, from->insn, to->insn, dep_kind);

  l = dep_cost (dep);

  e = create_ddg_edge (from, to, d_t, d_dt, l, distance);

  if (distance > 0)

    add_backarc_to_ddg (g, e);

  else

    add_edge_to_ddg (g, e);

}

/* Given a downwards exposed register def LAST_DEF (which is the last

   definition of that register in the bb), add inter-loop true dependences

   to all its uses in the next iteration, an output dependence to the

   first def of the same register (possibly itself) in the next iteration

   and anti-dependences from its uses in the current iteration to the

   first definition in the next iteration.  */

static void

add_cross_iteration_register_deps (ddg_ptr g, df_ref last_def)

{

  int regno = DF_REF_REGNO (last_def);

  struct df_link *r_use;

  int has_use_in_bb_p = false;

  rtx def_insn = DF_REF_INSN (last_def);

  ddg_node_ptr last_def_node = get_node_of_insn (g, def_insn);

  ddg_node_ptr use_node;

#ifdef ENABLE_CHECKING

  struct df_rd_bb_info *bb_info = DF_RD_BB_INFO (g->bb);

#endif

  df_ref first_def = df_bb_regno_first_def_find (g->bb, regno);

  gcc_assert (last_def_node);

  gcc_assert (first_def);

#ifdef ENABLE_CHECKING

  if (DF_REF_ID (last_def) != DF_REF_ID (first_def))

    gcc_assert (!bitmap_bit_p (bb_info->gen, DF_REF_ID (first_def)));

#endif

  /* Create inter-loop true dependences and anti dependences.  */

  for (r_use = DF_REF_CHAIN (last_def); r_use != NULL; r_use = r_use->next)

    {

      rtx use_insn = DF_REF_INSN (r_use->ref);

      if (BLOCK_FOR_INSN (use_insn) != g->bb)

        continue;

      /* ??? Do not handle uses with DF_REF_IN_NOTE notes.  */

      use_node = get_node_of_insn (g, use_insn);

      gcc_assert (use_node);

      has_use_in_bb_p = true;

      if (use_node->cuid <= last_def_node->cuid)

        {

          /* Add true deps from last_def to it's uses in the next

             iteration.  Any such upwards exposed use appears before

             the last_def def.  */

          create_ddg_dep_no_link (g, last_def_node, use_node,

                                  DEBUG_INSN_P (use_insn) ? ANTI_DEP : TRUE_DEP,

                                  REG_DEP, 1);

        }

      else if (!DEBUG_INSN_P (use_insn))

        {

          /* Add anti deps from last_def's uses in the current iteration

             to the first def in the next iteration.  We do not add ANTI

             dep when there is an intra-loop TRUE dep in the opposite

             direction, but use regmoves to fix such disregarded ANTI

             deps when broken.  If the first_def reaches the USE then

             there is such a dep.  */

          ddg_node_ptr first_def_node = get_node_of_insn (g,

                                                          DF_REF_INSN (first_def));

          gcc_assert (first_def_node);

          if (DF_REF_ID (last_def) != DF_REF_ID (first_def)

              || !flag_modulo_sched_allow_regmoves)

            create_ddg_dep_no_link (g, use_node, first_def_node, ANTI_DEP,

                                    REG_DEP, 1);

        }

    }

  /* Create an inter-loop output dependence between LAST_DEF (which is the

     last def in its block, being downwards exposed) and the first def in

     its block.  Avoid creating a self output dependence.  Avoid creating

     an output dependence if there is a dependence path between the two

     defs starting with a true dependence to a use which can be in the

     next iteration; followed by an anti dependence of that use to the

     first def (i.e. if there is a use between the two defs.)  */

  if (!has_use_in_bb_p)

    {

      ddg_node_ptr dest_node;

      if (DF_REF_ID (last_def) == DF_REF_ID (first_def))

        return;

      dest_node = get_node_of_insn (g, DF_REF_INSN (first_def));

      gcc_assert (dest_node);

      create_ddg_dep_no_link (g, last_def_node, dest_node,

                              OUTPUT_DEP, REG_DEP, 1);

    }

}

/* Build inter-loop dependencies, by looking at DF analysis backwards.  */

static void

build_inter_loop_deps (ddg_ptr g)

{

  unsigned rd_num;

  struct df_rd_bb_info *rd_bb_info;

  bitmap_iterator bi;

  rd_bb_info = DF_RD_BB_INFO (g->bb);

  /* Find inter-loop register output, true and anti deps.  */

  EXECUTE_IF_SET_IN_BITMAP (rd_bb_info->gen, 0, rd_num, bi)

  {

    df_ref rd = DF_DEFS_GET (rd_num);

    add_cross_iteration_register_deps (g, rd);

  }

}

/* Given two nodes, analyze their RTL insns and add inter-loop mem deps

   to ddg G.  */

static void

add_inter_loop_mem_dep (ddg_ptr g, ddg_node_ptr from, ddg_node_ptr to)

{

  if (!insn_alias_sets_conflict_p (from->insn, to->insn))

    /* Do not create edge if memory references have disjoint alias sets.  */

    return;

  if (mem_write_insn_p (from->insn))

    {

      if (mem_read_insn_p (to->insn))

        create_ddg_dep_no_link (g, from, to,

                                DEBUG_INSN_P (to->insn)

                                ? ANTI_DEP : TRUE_DEP, MEM_DEP, 1);

      else if (from->cuid != to->cuid)

        create_ddg_dep_no_link (g, from, to,

                                DEBUG_INSN_P (to->insn)

                                ? ANTI_DEP : OUTPUT_DEP, MEM_DEP, 1);

    }

  else

    {

      if (mem_read_insn_p (to->insn))

        return;

      else if (from->cuid != to->cuid)

        {

          create_ddg_dep_no_link (g, from, to, ANTI_DEP, MEM_DEP, 1);

          if (DEBUG_INSN_P (from->insn) || DEBUG_INSN_P (to->insn))

            create_ddg_dep_no_link (g, to, from, ANTI_DEP, MEM_DEP, 1);

          else

            create_ddg_dep_no_link (g, to, from, TRUE_DEP, MEM_DEP, 1);

        }

    }

}

/* Perform intra-block Data Dependency analysis and connect the nodes in

   the DDG.  We assume the loop has a single basic block.  */

static void

build_intra_loop_deps (ddg_ptr g)

{

  int i;

  /* Hold the dependency analysis state during dependency calculations.  */

  struct deps_desc tmp_deps;

  rtx head, tail;

  /* Build the dependence information, using the sched_analyze function.  */

  init_deps_global ();

  init_deps (&tmp_deps, false);

  /* Do the intra-block data dependence analysis for the given block.  */

  get_ebb_head_tail (g->bb, g->bb, &head, &tail);

  sched_analyze (&tmp_deps, head, tail);

  /* Build intra-loop data dependencies using the scheduler dependency

     analysis.  */

  for (i = 0; i < g->num_nodes; i++)

    {

      ddg_node_ptr dest_node = &g->nodes[i];

      sd_iterator_def sd_it;

      dep_t dep;

      if (! INSN_P (dest_node->insn))

        continue;

      FOR_EACH_DEP (dest_node->insn, SD_LIST_BACK, sd_it, dep)

        {

          ddg_node_ptr src_node = get_node_of_insn (g, DEP_PRO (dep));

          if (!src_node)

            continue;

          create_ddg_dep_from_intra_loop_link (g, src_node, dest_node, dep);

        }

      /* If this insn modifies memory, add an edge to all insns that access

         memory.  */

      if (mem_access_insn_p (dest_node->insn))

        {

          int j;

          for (j = 0; j <= i; j++)

            {

              ddg_node_ptr j_node = &g->nodes[j];

              if (DEBUG_INSN_P (j_node->insn))

                continue;

              if (mem_access_insn_p (j_node->insn))

                /* Don't bother calculating inter-loop dep if an intra-loop dep

                   already exists.  */

                  if (! TEST_BIT (dest_node->successors, j))

                    add_inter_loop_mem_dep (g, dest_node, j_node);

            }

        }

    }

  /* Free the INSN_LISTs.  */

  finish_deps_global ();

  free_deps (&tmp_deps);

  /* Free dependencies.  */

  sched_free_deps (head, tail, false);

}

/* Given a basic block, create its DDG and return a pointer to a variable

   of ddg type that represents it.

   Initialize the ddg structure fields to the appropriate values.  */

ddg_ptr

create_ddg (basic_block bb, int closing_branch_deps)

{

  ddg_ptr g;

  rtx insn, first_note;

  int i;

  int num_nodes = 0;

  g = (ddg_ptr) xcalloc (1, sizeof (struct ddg));

  g->bb = bb;

  g->closing_branch_deps = closing_branch_deps;

  /* Count the number of insns in the BB.  */

  for (insn = BB_HEAD (bb); insn != NEXT_INSN (BB_END (bb));

       insn = NEXT_INSN (insn))

    {

      if (! INSN_P (insn) || GET_CODE (PATTERN (insn)) == USE)

        continue;

      if (DEBUG_INSN_P (insn))

        g->num_debug++;

      else

        {

          if (mem_read_insn_p (insn))

            g->num_loads++;

          if (mem_write_insn_p (insn))

            g->num_stores++;

        }

      num_nodes++;

    }

  /* There is nothing to do for this BB.  */

  if ((num_nodes - g->num_debug) <= 1)

    {

      free (g);

      return NULL;

    }

  /* Allocate the nodes array, and initialize the nodes.  */

  g->num_nodes = num_nodes;

  g->nodes = (ddg_node_ptr) xcalloc (num_nodes, sizeof (struct ddg_node));

  g->closing_branch = NULL;

  i = 0;

  first_note = NULL_RTX;

  for (insn = BB_HEAD (bb); insn != NEXT_INSN (BB_END (bb));

       insn = NEXT_INSN (insn))

    {

      if (! INSN_P (insn))

        {

          if (! first_note && NOTE_P (insn)

              && NOTE_KIND (insn) !=  NOTE_INSN_BASIC_BLOCK)

            first_note = insn;

          continue;

        }

      if (JUMP_P (insn))

        {

          gcc_assert (!g->closing_branch);

          g->closing_branch = &g->nodes[i];

        }

      else if (GET_CODE (PATTERN (insn)) == USE)

        {

          if (! first_note)

            first_note = insn;

          continue;

        }

      g->nodes[i].cuid = i;

      g->nodes[i].successors = sbitmap_alloc (num_nodes);

      sbitmap_zero (g->nodes[i].successors);

      g->nodes[i].predecessors = sbitmap_alloc (num_nodes);

      sbitmap_zero (g->nodes[i].predecessors);

      g->nodes[i].first_note = (first_note ? first_note : insn);

      g->nodes[i++].insn = insn;

      first_note = NULL_RTX;

    }

  /* We must have found a branch in DDG.  */

  gcc_assert (g->closing_branch);

  /* Build the data dependency graph.  */

  build_intra_loop_deps (g);

  build_inter_loop_deps (g);

  return g;

}

/* Free all the memory allocated for the DDG.  */

void

free_ddg (ddg_ptr g)

{

  int i;

  if (!g)

    return;

  for (i = 0; i < g->num_nodes; i++)

    {

      ddg_edge_ptr e = g->nodes[i].out;

      while (e)

        {

          ddg_edge_ptr next = e->next_out;

          free (e);

          e = next;

        }

      sbitmap_free (g->nodes[i].successors);

      sbitmap_free (g->nodes[i].predecessors);

    }

  if (g->num_backarcs > 0)

    free (g->backarcs);

  free (g->nodes);

  free (g);

}

void

print_ddg_edge (FILE *file, ddg_edge_ptr e)

{

  char dep_c;

  switch (e->type)

    {

    case OUTPUT_DEP :

      dep_c = 'O';

      break;

    case ANTI_DEP :

      dep_c = 'A';

      break;

    default:

      dep_c = 'T';

    }

  fprintf (file, " [%d -(%c,%d,%d)-> %d] ", INSN_UID (e->src->insn),

           dep_c, e->latency, e->distance, INSN_UID (e->dest->insn));

}

/* Print the DDG nodes with there in/out edges to the dump file.  */

void

print_ddg (FILE *file, ddg_ptr g)

{

  int i;

  for (i = 0; i < g->num_nodes; i++)

    {

      ddg_edge_ptr e;

      fprintf (file, "Node num: %d\n", g->nodes[i].cuid);

      print_rtl_single (file, g->nodes[i].insn);

      fprintf (file, "OUT ARCS: ");

      for (e = g->nodes[i].out; e; e = e->next_out)

        print_ddg_edge (file, e);

      fprintf (file, "\nIN ARCS: ");

      for (e = g->nodes[i].in; e; e = e->next_in)

        print_ddg_edge (file, e);

      fprintf (file, "\n");

    }

}

/* Print the given DDG in VCG format.  */

void

vcg_print_ddg (FILE *file, ddg_ptr g)

{

  int src_cuid;

  fprintf (file, "graph: {\n");

  for (src_cuid = 0; src_cuid < g->num_nodes; src_cuid++)

    {

      ddg_edge_ptr e;

      int src_uid = INSN_UID (g->nodes[src_cuid].insn);

      fprintf (file, "node: {title: \"%d_%d\" info1: \"", src_cuid, src_uid);

      print_rtl_single (file, g->nodes[src_cuid].insn);

      fprintf (file, "\"}\n");

      for (e = g->nodes[src_cuid].out; e; e = e->next_out)

        {

          int dst_uid = INSN_UID (e->dest->insn);

          int dst_cuid = e->dest->cuid;

          /* Give the backarcs a different color.  */

          if (e->distance > 0)

            fprintf (file, "backedge: {color: red ");

          else

            fprintf (file, "edge: { ");

          fprintf (file, "sourcename: \"%d_%d\" ", src_cuid, src_uid);

          fprintf (file, "targetname: \"%d_%d\" ", dst_cuid, dst_uid);

          fprintf (file, "label: \"%d_%d\"}\n", e->latency, e->distance);

        }

    }

  fprintf (file, "}\n");

}

/* Dump the sccs in SCCS.  */

void

print_sccs (FILE *file, ddg_all_sccs_ptr sccs, ddg_ptr g)

{

  unsigned int u = 0;

  sbitmap_iterator sbi;

  int i;

  if (!file)

    return;

  fprintf (file, "\n;; Number of SCC nodes - %d\n", sccs->num_sccs);

  for (i = 0; i < sccs->num_sccs; i++)

    {

      fprintf (file, "SCC number: %d\n", i);

      EXECUTE_IF_SET_IN_SBITMAP (sccs->sccs[i]->nodes, 0, u, sbi)

      {

        fprintf (file, "insn num %d\n", u);

        print_rtl_single (file, g->nodes[u].insn);

      }

    }

  fprintf (file, "\n");

}

/* Create an edge and initialize it with given values.  */