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/* Scanning of rtl for dataflow analysis.

   Copyright (C) 2007, 2008, 2009, 2010

   Free Software Foundation, Inc.

   Contributed by Kenneth Zadeck (zadeck@naturalbridge.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 "rtl.h"

#include "tm_p.h"

#include "flags.h"

#include "regs.h"

#include "output.h"

#include "except.h"

#include "hard-reg-set.h"

#include "basic-block.h"

#include "timevar.h"

#include "df.h"

struct regstat_n_sets_and_refs_t *regstat_n_sets_and_refs;

/*----------------------------------------------------------------------------

   REG_N_SETS and REG_N_REFS.

   ----------------------------------------------------------------------------*/

/* If a pass need to change these values in some magical way or the

   pass needs to have accurate values for these and is not using

   incremental df scanning, then it should use REG_N_SETS and

   REG_N_USES.  If the pass is doing incremental scanning then it

   should be getting the info from DF_REG_DEF_COUNT and

   DF_REG_USE_COUNT.  */

void

regstat_init_n_sets_and_refs (void)

{

  unsigned int i;

  unsigned int max_regno = max_reg_num ();

  timevar_push (TV_REG_STATS);

  df_grow_reg_info ();

  gcc_assert (!regstat_n_sets_and_refs);

  regstat_n_sets_and_refs = XNEWVEC (struct regstat_n_sets_and_refs_t, max_regno);

  if (MAY_HAVE_DEBUG_INSNS)

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

      {

        int use_count;

        df_ref use;

        use_count = DF_REG_USE_COUNT (i);

        for (use = DF_REG_USE_CHAIN (i); use; use = DF_REF_NEXT_REG (use))

          if (DF_REF_INSN_INFO (use) && DEBUG_INSN_P (DF_REF_INSN (use)))

            use_count--;

        SET_REG_N_SETS (i, DF_REG_DEF_COUNT (i));

        SET_REG_N_REFS (i, use_count + REG_N_SETS (i));

      }

  else

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

      {

        SET_REG_N_SETS (i, DF_REG_DEF_COUNT (i));

        SET_REG_N_REFS (i, DF_REG_USE_COUNT (i) + REG_N_SETS (i));

      }

  timevar_pop (TV_REG_STATS);

}

/* Free the array that holds the REG_N_SETS and REG_N_REFS.  */

void

regstat_free_n_sets_and_refs (void)

{

  gcc_assert (regstat_n_sets_and_refs);

  free (regstat_n_sets_and_refs);

  regstat_n_sets_and_refs = NULL;

}

/*----------------------------------------------------------------------------

   REGISTER INFORMATION

   Process REG_N_DEATHS, REG_LIVE_LENGTH, REG_N_CALLS_CROSSED,

   REG_N_THROWING_CALLS_CROSSED and REG_BASIC_BLOCK.

   ----------------------------------------------------------------------------*/

static bitmap setjmp_crosses;

struct reg_info_t *reg_info_p;

/* The number allocated elements of reg_info_p.  */

size_t reg_info_p_size;

/* Compute register info: lifetime, bb, and number of defs and uses

   for basic block BB.  The three bitvectors are scratch regs used

   here.  */

static void

regstat_bb_compute_ri (unsigned int bb_index,

                       bitmap live, bitmap do_not_gen, bitmap artificial_uses,

                       bitmap local_live, bitmap local_processed)

{

  basic_block bb = BASIC_BLOCK (bb_index);

  rtx insn;

  df_ref *def_rec;

  df_ref *use_rec;

  int luid = 0;

  bitmap_iterator bi;

  unsigned int regno;

  bitmap_copy (live, df_get_live_out (bb));

  bitmap_clear (artificial_uses);

  /* Process the regs live at the end of the block.  Mark them as

     not local to any one basic block.  */

  EXECUTE_IF_SET_IN_BITMAP (live, 0, regno, bi)

    REG_BASIC_BLOCK (regno) = REG_BLOCK_GLOBAL;

  /* Process the artificial defs and uses at the bottom of the block

     to begin processing.  */

  for (def_rec = df_get_artificial_defs (bb_index); *def_rec; def_rec++)

    {

      df_ref def = *def_rec;

      if ((DF_REF_FLAGS (def) & DF_REF_AT_TOP) == 0)

        bitmap_clear_bit (live, DF_REF_REGNO (def));

    }

  for (use_rec = df_get_artificial_uses (bb_index); *use_rec; use_rec++)

    {

      df_ref use = *use_rec;

      if ((DF_REF_FLAGS (use) & DF_REF_AT_TOP) == 0)

        {

          regno = DF_REF_REGNO (use);

          bitmap_set_bit (live, regno);

          bitmap_set_bit (artificial_uses, regno);

        }

    }

  FOR_BB_INSNS_REVERSE (bb, insn)

    {

      unsigned int uid = INSN_UID (insn);

      unsigned int regno;

      bitmap_iterator bi;

      struct df_mw_hardreg **mws_rec;

      rtx link;

      if (!NONDEBUG_INSN_P (insn))

        continue;

      /* Increment the live_length for all of the registers that

         are are referenced in this block and live at this

         particular point.  */

      EXECUTE_IF_SET_IN_BITMAP (local_live, 0, regno, bi)

        {

          REG_LIVE_LENGTH (regno)++;

        }

      luid++;

      bitmap_clear (do_not_gen);

      link = REG_NOTES (insn);

      while (link)

        {

          if (REG_NOTE_KIND (link) == REG_DEAD)

            REG_N_DEATHS(REGNO (XEXP (link, 0)))++;

          link = XEXP (link, 1);

        }

      /* Process the defs.  */

      if (CALL_P (insn))

        {

          bool can_throw = can_throw_internal (insn);

          bool set_jump = (find_reg_note (insn, REG_SETJMP, NULL) != NULL);

          EXECUTE_IF_SET_IN_BITMAP (live, 0, regno, bi)

            {

              REG_N_CALLS_CROSSED (regno)++;

              REG_FREQ_CALLS_CROSSED (regno) += REG_FREQ_FROM_BB (bb);

              if (can_throw)

                REG_N_THROWING_CALLS_CROSSED (regno)++;

              /* We have a problem with any pseudoreg that lives

                 across the setjmp.  ANSI says that if a user variable

                 does not change in value between the setjmp and the

                 longjmp, then the longjmp preserves it.  This

                 includes longjmp from a place where the pseudo

                 appears dead.  (In principle, the value still exists

                 if it is in scope.)  If the pseudo goes in a hard

                 reg, some other value may occupy that hard reg where

                 this pseudo is dead, thus clobbering the pseudo.

                 Conclusion: such a pseudo must not go in a hard

                 reg.  */

              if (set_jump)

                bitmap_set_bit (setjmp_crosses, regno);

            }

        }

      /* We only care about real sets for calls.  Clobbers only

         may clobbers cannot be depended on.  */

      for (mws_rec = DF_INSN_UID_MWS (uid); *mws_rec; mws_rec++)

        {

          struct df_mw_hardreg *mws = *mws_rec;

          if (DF_MWS_REG_DEF_P (mws))

            {

              bool all_dead = true;

              unsigned int r;

              for (r=mws->start_regno; r <= mws->end_regno; r++)

                if ((bitmap_bit_p (live, r))

                    || bitmap_bit_p (artificial_uses, r))

                  {

                    all_dead = false;

                    break;

                  }

              if (all_dead)

                {

                  unsigned int regno = mws->start_regno;

                  bitmap_set_bit (do_not_gen, regno);

                  /* Only do this if the value is totally dead.  */

                  REG_LIVE_LENGTH (regno)++;

                }

            }

        }

      /* All of the defs except the return value are some sort of

         clobber.  This code is for the return.  */

      for (def_rec = DF_INSN_UID_DEFS (uid); *def_rec; def_rec++)

        {

          df_ref def = *def_rec;

          if ((!CALL_P (insn))

              || (!(DF_REF_FLAGS (def) & (DF_REF_MUST_CLOBBER | DF_REF_MAY_CLOBBER))))

            {

              unsigned int dregno = DF_REF_REGNO (def);

              if (bitmap_bit_p (live, dregno))

                {

                  /* If we have seen this regno, then it has already been

                     processed correctly with the per insn increment.  If we

                     have not seen it we need to add the length from here to

                     the end of the block to the live length.  */

                  if (bitmap_bit_p (local_processed, dregno))

                    {

                      if (!(DF_REF_FLAGS (def) & (DF_REF_PARTIAL | DF_REF_CONDITIONAL)))

                        bitmap_clear_bit (local_live, dregno);

                    }

                  else

                    {

                      bitmap_set_bit (local_processed, dregno);

                      REG_LIVE_LENGTH (dregno) += luid;

                    }

                }

              else if ((!(DF_REF_FLAGS (def) & DF_REF_MW_HARDREG))

                       && (!bitmap_bit_p (artificial_uses, dregno)))

                {

                  REG_LIVE_LENGTH (dregno)++;

                }

              if (dregno >= FIRST_PSEUDO_REGISTER)

                {

                  REG_FREQ (dregno) += REG_FREQ_FROM_BB (bb);

                  if (REG_BASIC_BLOCK (dregno) == REG_BLOCK_UNKNOWN)

                    REG_BASIC_BLOCK (dregno) = bb->index;

                  else if (REG_BASIC_BLOCK (dregno) != bb->index)

                    REG_BASIC_BLOCK (dregno) = REG_BLOCK_GLOBAL;

                }

              if (!(DF_REF_FLAGS (def) & (DF_REF_MUST_CLOBBER + DF_REF_MAY_CLOBBER)))

                bitmap_set_bit (do_not_gen, dregno);

              /* Kill this register if it is not a subreg store or conditional store.  */

              if (!(DF_REF_FLAGS (def) & (DF_REF_PARTIAL | DF_REF_CONDITIONAL)))

                bitmap_clear_bit (live, dregno);

            }

        }

      for (use_rec = DF_INSN_UID_USES (uid); *use_rec; use_rec++)

        {

          df_ref use = *use_rec;

          unsigned int uregno = DF_REF_REGNO (use);

          if (uregno >= FIRST_PSEUDO_REGISTER)

            {

              REG_FREQ (uregno) += REG_FREQ_FROM_BB (bb);

              if (REG_BASIC_BLOCK (uregno) == REG_BLOCK_UNKNOWN)

                REG_BASIC_BLOCK (uregno) = bb->index;

              else if (REG_BASIC_BLOCK (uregno) != bb->index)

                REG_BASIC_BLOCK (uregno) = REG_BLOCK_GLOBAL;

            }

          if (bitmap_set_bit (live, uregno))

            {

              /* This register is now live.  */

              /* If we have seen this regno, then it has already been

                 processed correctly with the per insn increment.  If

                 we have not seen it we set the bit so that begins to

                 get processed locally.  Note that we don't even get

                 here if the variable was live at the end of the block

                 since just a ref inside the block does not effect the

                 calculations.  */

              REG_LIVE_LENGTH (uregno) ++;

              bitmap_set_bit (local_live, uregno);

              bitmap_set_bit (local_processed, uregno);

            }

        }

    }

  /* Add the length of the block to all of the registers that were not

     referenced, but still live in this block.  */

  bitmap_and_compl_into (live, local_processed);

  EXECUTE_IF_SET_IN_BITMAP (live, 0, regno, bi)

    REG_LIVE_LENGTH (regno) += luid;

  bitmap_clear (local_processed);

  bitmap_clear (local_live);

}

/* Compute register info: lifetime, bb, and number of defs and uses.  */

void

regstat_compute_ri (void)

{

  basic_block bb;

  bitmap live = BITMAP_ALLOC (&df_bitmap_obstack);

  bitmap do_not_gen = BITMAP_ALLOC (&df_bitmap_obstack);

  bitmap artificial_uses = BITMAP_ALLOC (&df_bitmap_obstack);

  bitmap local_live = BITMAP_ALLOC (&df_bitmap_obstack);

  bitmap local_processed = BITMAP_ALLOC (&df_bitmap_obstack);

  unsigned int regno;

  bitmap_iterator bi;

  /* Initialize everything.  */

  gcc_assert (!reg_info_p);

  timevar_push (TV_REG_STATS);

  setjmp_crosses = BITMAP_ALLOC (&df_bitmap_obstack);

  max_regno = max_reg_num ();

  reg_info_p_size = max_regno;

  reg_info_p = XCNEWVEC (struct reg_info_t, max_regno);

  FOR_EACH_BB (bb)

    {

      regstat_bb_compute_ri (bb->index, live, do_not_gen, artificial_uses,

                             local_live, local_processed);

    }

  BITMAP_FREE (live);

  BITMAP_FREE (do_not_gen);

  BITMAP_FREE (artificial_uses);

  /* See the setjmp comment in regstat_ri_bb_compute.  */

  EXECUTE_IF_SET_IN_BITMAP (setjmp_crosses, FIRST_PSEUDO_REGISTER, regno, bi)

    {

      REG_BASIC_BLOCK (regno) = REG_BLOCK_UNKNOWN;

      REG_LIVE_LENGTH (regno) = -1;

    }

  BITMAP_FREE (local_live);

  BITMAP_FREE (local_processed);

  timevar_pop (TV_REG_STATS);

}

/* Free all storage associated with the problem.  */

void

regstat_free_ri (void)

{

  gcc_assert (reg_info_p);

  reg_info_p_size = 0;

  free (reg_info_p);

  reg_info_p = NULL;

  BITMAP_FREE (setjmp_crosses);

}

/* Return a bitmap containing the set of registers that cross a setjmp.

   The client should not change or delete this bitmap.  */

bitmap

regstat_get_setjmp_crosses (void)

{

  return setjmp_crosses;

}

/*----------------------------------------------------------------------------

   Process REG_N_CALLS_CROSSED.

   This is used by sched_deps.  A good implementation of sched-deps

   would really process the blocks directly rather than going through

   lists of insns.  If it did this, it could use the exact regs that

   cross an individual call rather than using this info that merges

   the info for all calls.

   ----------------------------------------------------------------------------*/

/* Compute calls crossed for BB. Live is a scratch bitvector.  */

static void

regstat_bb_compute_calls_crossed (unsigned int bb_index, bitmap live)

{

  basic_block bb = BASIC_BLOCK (bb_index);

  rtx insn;

  df_ref *def_rec;

  df_ref *use_rec;

  bitmap_copy (live, df_get_live_out (bb));

  /* Process the artificial defs and uses at the bottom of the block

     to begin processing.  */

  for (def_rec = df_get_artificial_defs (bb_index); *def_rec; def_rec++)

    {

      df_ref def = *def_rec;

      if ((DF_REF_FLAGS (def) & DF_REF_AT_TOP) == 0)

        bitmap_clear_bit (live, DF_REF_REGNO (def));

    }

  for (use_rec = df_get_artificial_uses (bb_index); *use_rec; use_rec++)

    {

      df_ref use = *use_rec;

      if ((DF_REF_FLAGS (use) & DF_REF_AT_TOP) == 0)

        bitmap_set_bit (live, DF_REF_REGNO (use));

    }

  FOR_BB_INSNS_REVERSE (bb, insn)

    {

      unsigned int uid = INSN_UID (insn);

      unsigned int regno;

      if (!INSN_P (insn))

        continue;

      /* Process the defs.  */

      if (CALL_P (insn))

        {

          bitmap_iterator bi;

          EXECUTE_IF_SET_IN_BITMAP (live, 0, regno, bi)

            {

              REG_N_CALLS_CROSSED (regno)++;

              REG_FREQ_CALLS_CROSSED (regno) += REG_FREQ_FROM_BB (bb);

            }

        }

      /* All of the defs except the return value are some sort of

         clobber.  This code is for the return.  */

      for (def_rec = DF_INSN_UID_DEFS (uid); *def_rec; def_rec++)

        {

          df_ref def = *def_rec;

          if ((!CALL_P (insn))

              || (!(DF_REF_FLAGS (def) & (DF_REF_MUST_CLOBBER | DF_REF_MAY_CLOBBER))))

            {

              /* Kill this register if it is not a subreg store or conditional store.  */

              if (!(DF_REF_FLAGS (def) & (DF_REF_PARTIAL | DF_REF_CONDITIONAL)))

                bitmap_clear_bit (live, DF_REF_REGNO (def));

            }

        }

      for (use_rec = DF_INSN_UID_USES (uid); *use_rec; use_rec++)

        {

          df_ref use = *use_rec;

          bitmap_set_bit (live, DF_REF_REGNO (use));

        }

    }

}

/* Compute register info: lifetime, bb, and number of defs and uses.  */

void

regstat_compute_calls_crossed (void)

{

  basic_block bb;

  bitmap live = BITMAP_ALLOC (&df_bitmap_obstack);

  /* Initialize everything.  */

  gcc_assert (!reg_info_p);

  timevar_push (TV_REG_STATS);

  max_regno = max_reg_num ();

  reg_info_p_size = max_regno;

  reg_info_p = XCNEWVEC (struct reg_info_t, max_regno);

  FOR_EACH_BB (bb)

    {

      regstat_bb_compute_calls_crossed (bb->index, live);

    }

  BITMAP_FREE (live);

  timevar_pop (TV_REG_STATS);

}

/* Free all storage associated with the problem.  */

void

regstat_free_calls_crossed (void)

{

  gcc_assert (reg_info_p);

  reg_info_p_size = 0;

  free (reg_info_p);

  reg_info_p = NULL;

}