path: root/gcc/lra-lives.c

/* Build live ranges for pseudos.
   Copyright (C) 2010-2014 Free Software Foundation, Inc.
   Contributed by Vladimir Makarov <vmakarov@redhat.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/>.	 */


/* This file contains code to build pseudo live-ranges (analogous
   structures used in IRA, so read comments about the live-ranges
   there) and other info necessary for other passes to assign
   hard-registers to pseudos, coalesce the spilled pseudos, and assign
   stack memory slots to spilled pseudos.  */

#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "hard-reg-set.h"
#include "rtl.h"
#include "tm_p.h"
#include "insn-config.h"
#include "recog.h"
#include "output.h"
#include "regs.h"
#include "hashtab.h"
#include "hash-set.h"
#include "vec.h"
#include "machmode.h"
#include "input.h"
#include "function.h"
#include "expr.h"
#include "basic-block.h"
#include "except.h"
#include "df.h"
#include "ira.h"
#include "sparseset.h"
#include "lra-int.h"

/* Program points are enumerated by numbers from range
   0..LRA_LIVE_MAX_POINT-1.  There are approximately two times more
   program points than insns.  Program points are places in the
   program where liveness info can be changed.	In most general case
   (there are more complicated cases too) some program points
   correspond to places where input operand dies and other ones
   correspond to places where output operands are born.	 */
int lra_live_max_point;

/* Accumulated execution frequency of all references for each hard
   register.  */
int lra_hard_reg_usage[FIRST_PSEUDO_REGISTER];

/* A global flag whose true value says to build live ranges for all
   pseudos, otherwise the live ranges only for pseudos got memory is
   build.  True value means also building copies and setting up hard
   register preferences.  The complete info is necessary only for the
   assignment pass.  The complete info is not needed for the
   coalescing and spill passes.	 */
static bool complete_info_p;

/* Pseudos live at current point in the RTL scan.  */
static sparseset pseudos_live;

/* Pseudos probably living through calls and setjumps.	As setjump is
   a call too, if a bit in PSEUDOS_LIVE_THROUGH_SETJUMPS is set up
   then the corresponding bit in PSEUDOS_LIVE_THROUGH_CALLS is set up
   too.	 These data are necessary for cases when only one subreg of a
   multi-reg pseudo is set up after a call.  So we decide it is
   probably live when traversing bb backward.  We are sure about
   living when we see its usage or definition of the pseudo.  */
static sparseset pseudos_live_through_calls;
static sparseset pseudos_live_through_setjumps;

/* Set of hard regs (except eliminable ones) currently live.  */
static HARD_REG_SET hard_regs_live;

/* Set of pseudos and hard registers start living/dying in the current
   insn.  These sets are used to update REG_DEAD and REG_UNUSED notes
   in the insn.	 */
static sparseset start_living, start_dying;

/* Set of pseudos and hard regs dead and unused in the current
   insn.  */
static sparseset unused_set, dead_set;

/* Pool for pseudo live ranges.	 */
static alloc_pool live_range_pool;

/* Free live range LR.	*/
static void
free_live_range (lra_live_range_t lr)
{
  pool_free (live_range_pool, lr);
}

/* Free live range list LR.  */
static void
free_live_range_list (lra_live_range_t lr)
{
  lra_live_range_t next;

  while (lr != NULL)
    {
      next = lr->next;
      free_live_range (lr);
      lr = next;
    }
}

/* Create and return pseudo live range with given attributes.  */
static lra_live_range_t
create_live_range (int regno, int start, int finish, lra_live_range_t next)
{
  lra_live_range_t p;

  p = (lra_live_range_t) pool_alloc (live_range_pool);
  p->regno = regno;
  p->start = start;
  p->finish = finish;
  p->next = next;
  return p;
}

/* Copy live range R and return the result.  */
static lra_live_range_t
copy_live_range (lra_live_range_t r)
{
  lra_live_range_t p;

  p = (lra_live_range_t) pool_alloc (live_range_pool);
  *p = *r;
  return p;
}

/* Copy live range list given by its head R and return the result.  */
lra_live_range_t
lra_copy_live_range_list (lra_live_range_t r)
{
  lra_live_range_t p, first, *chain;

  first = NULL;
  for (chain = &first; r != NULL; r = r->next)
    {
      p = copy_live_range (r);
      *chain = p;
      chain = &p->next;
    }
  return first;
}

/* Merge *non-intersected* ranges R1 and R2 and returns the result.
   The function maintains the order of ranges and tries to minimize
   size of the result range list.  Ranges R1 and R2 may not be used
   after the call.  */
lra_live_range_t
lra_merge_live_ranges (lra_live_range_t r1, lra_live_range_t r2)
{
  lra_live_range_t first, last, temp;

  if (r1 == NULL)
    return r2;
  if (r2 == NULL)
    return r1;
  for (first = last = NULL; r1 != NULL && r2 != NULL;)
    {
      if (r1->start < r2->start)
	{
	  temp = r1;
	  r1 = r2;
	  r2 = temp;
	}
      if (r1->start == r2->finish + 1)
	{
	  /* Joint ranges: merge r1 and r2 into r1.  */
	  r1->start = r2->start;
	  temp = r2;
	  r2 = r2->next;
	  pool_free (live_range_pool, temp);
	}
      else
	{
	  gcc_assert (r2->finish + 1 < r1->start);
	  /* Add r1 to the result.  */
	  if (first == NULL)
	    first = last = r1;
	  else
	    {
	      last->next = r1;
	      last = r1;
	    }
	  r1 = r1->next;
	}
    }
  if (r1 != NULL)
    {
      if (first == NULL)
	first = r1;
      else
	last->next = r1;
    }
  else
    {
      lra_assert (r2 != NULL);
      if (first == NULL)
	first = r2;
      else
	last->next = r2;
    }
  return first;
}

/* Return TRUE if live ranges R1 and R2 intersect.  */
bool
lra_intersected_live_ranges_p (lra_live_range_t r1, lra_live_range_t r2)
{
  /* Remember the live ranges are always kept ordered.	*/
  while (r1 != NULL && r2 != NULL)
    {
      if (r1->start > r2->finish)
	r1 = r1->next;
      else if (r2->start > r1->finish)
	r2 = r2->next;
      else
	return true;
    }
  return false;
}

/* The function processing birth of hard register REGNO.  It updates
   living hard regs, conflict hard regs for living pseudos, and
   START_LIVING.  */
static void
make_hard_regno_born (int regno)
{
  unsigned int i;

  lra_assert (regno < FIRST_PSEUDO_REGISTER);
  if (TEST_HARD_REG_BIT (lra_no_alloc_regs, regno)
      || TEST_HARD_REG_BIT (hard_regs_live, regno))
    return;
  SET_HARD_REG_BIT (hard_regs_live, regno);
  sparseset_set_bit (start_living, regno);
  EXECUTE_IF_SET_IN_SPARSESET (pseudos_live, i)
    SET_HARD_REG_BIT (lra_reg_info[i].conflict_hard_regs, regno);
}

/* Process the death of hard register REGNO.  This updates
   hard_regs_live and START_DYING.  */
static void
make_hard_regno_dead (int regno)
{
  lra_assert (regno < FIRST_PSEUDO_REGISTER);
  if (TEST_HARD_REG_BIT (lra_no_alloc_regs, regno)
      || ! TEST_HARD_REG_BIT (hard_regs_live, regno))
    return;
  sparseset_set_bit (start_dying, regno);
  CLEAR_HARD_REG_BIT (hard_regs_live, regno);
}

/* Mark pseudo REGNO as living at program point POINT, update conflicting
   hard registers of the pseudo and START_LIVING, and start a new live
   range for the pseudo corresponding to REGNO if it is necessary.  */
static void
mark_pseudo_live (int regno, int point)
{
  lra_live_range_t p;

  lra_assert (regno >= FIRST_PSEUDO_REGISTER);
  lra_assert (! sparseset_bit_p (pseudos_live, regno));
  sparseset_set_bit (pseudos_live, regno);
  IOR_HARD_REG_SET (lra_reg_info[regno].conflict_hard_regs, hard_regs_live);

  if ((complete_info_p || lra_get_regno_hard_regno (regno) < 0)
      && ((p = lra_reg_info[regno].live_ranges) == NULL
	  || (p->finish != point && p->finish + 1 != point)))
     lra_reg_info[regno].live_ranges
       = create_live_range (regno, point, -1, p);
  sparseset_set_bit (start_living, regno);
}

/* Mark pseudo REGNO as not living at program point POINT and update
   START_DYING.
   This finishes the current live range for the pseudo corresponding
   to REGNO.  */
static void
mark_pseudo_dead (int regno, int point)
{
  lra_live_range_t p;

  lra_assert (regno >= FIRST_PSEUDO_REGISTER);
  lra_assert (sparseset_bit_p (pseudos_live, regno));
  sparseset_clear_bit (pseudos_live, regno);
  sparseset_set_bit (start_dying, regno);
  if (complete_info_p || lra_get_regno_hard_regno (regno) < 0)
    {
      p = lra_reg_info[regno].live_ranges;
      lra_assert (p != NULL);
      p->finish = point;
    }
}

/* Mark register REGNO (pseudo or hard register) in MODE as live
   at program point POINT.
   Return TRUE if the liveness tracking sets were modified,
   or FALSE if nothing changed.  */
static bool
mark_regno_live (int regno, enum machine_mode mode, int point)
{
  int last;
  bool changed = false;

  if (regno < FIRST_PSEUDO_REGISTER)
    {
      for (last = regno + hard_regno_nregs[regno][mode];
	   regno < last;
	   regno++)
	make_hard_regno_born (regno);
    }
  else if (! sparseset_bit_p (pseudos_live, regno))
    {
      mark_pseudo_live (regno, point);
      changed = true;
    }
  return changed;
}


/* Mark register REGNO in MODE as dead at program point POINT.
   Return TRUE if the liveness tracking sets were modified,
   or FALSE if nothing changed.  */
static bool
mark_regno_dead (int regno, enum machine_mode mode, int point)
{
  int last;
  bool changed = false;

  if (regno < FIRST_PSEUDO_REGISTER)
    {
      for (last = regno + hard_regno_nregs[regno][mode];
	   regno < last;
	   regno++)
	make_hard_regno_dead (regno);
    }
  else if (sparseset_bit_p (pseudos_live, regno))
    {
      mark_pseudo_dead (regno, point);
      changed = true;
    }
  return changed;
}

/* Insn currently scanned.  */
static rtx_insn *curr_insn;
/* The insn data.  */
static lra_insn_recog_data_t curr_id;
/* The insn static data.  */
static struct lra_static_insn_data *curr_static_id;

/* Return true when one of the predecessor edges of BB is marked with
   EDGE_ABNORMAL_CALL or EDGE_EH.  */
static bool
bb_has_abnormal_call_pred (basic_block bb)
{
  edge e;
  edge_iterator ei;

  FOR_EACH_EDGE (e, ei, bb->preds)
    {
      if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
	return true;
    }
  return false;
}

/* Vec containing execution frequencies of program points.  */
static vec<int> point_freq_vec;

/* The start of the above vector elements.  */
int *lra_point_freq;

/* Increment the current program point POINT to the next point which has
   execution frequency FREQ.  */
static void
next_program_point (int &point, int freq)
{
  point_freq_vec.safe_push (freq);
  lra_point_freq = point_freq_vec.address ();
  point++;
}

/* Update the preference of HARD_REGNO for pseudo REGNO by PROFIT.  */
void
lra_setup_reload_pseudo_preferenced_hard_reg (int regno,
					      int hard_regno, int profit)
{
  lra_assert (regno >= lra_constraint_new_regno_start);
  if (lra_reg_info[regno].preferred_hard_regno1 == hard_regno)
    lra_reg_info[regno].preferred_hard_regno_profit1 += profit;
  else if (lra_reg_info[regno].preferred_hard_regno2 == hard_regno)
    lra_reg_info[regno].preferred_hard_regno_profit2 += profit;
  else if (lra_reg_info[regno].preferred_hard_regno1 < 0)
    {
      lra_reg_info[regno].preferred_hard_regno1 = hard_regno;
      lra_reg_info[regno].preferred_hard_regno_profit1 = profit;
    }
  else if (lra_reg_info[regno].preferred_hard_regno2 < 0
	   || profit > lra_reg_info[regno].preferred_hard_regno_profit2)
    {
      lra_reg_info[regno].preferred_hard_regno2 = hard_regno;
      lra_reg_info[regno].preferred_hard_regno_profit2 = profit;
    }
  else
    return;
  /* Keep the 1st hard regno as more profitable.  */
  if (lra_reg_info[regno].preferred_hard_regno1 >= 0
      && lra_reg_info[regno].preferred_hard_regno2 >= 0
      && (lra_reg_info[regno].preferred_hard_regno_profit2
	  > lra_reg_info[regno].preferred_hard_regno_profit1))
    {
      int temp;

      temp = lra_reg_info[regno].preferred_hard_regno1;
      lra_reg_info[regno].preferred_hard_regno1
	= lra_reg_info[regno].preferred_hard_regno2;
      lra_reg_info[regno].preferred_hard_regno2 = temp;
      temp = lra_reg_info[regno].preferred_hard_regno_profit1;
      lra_reg_info[regno].preferred_hard_regno_profit1
	= lra_reg_info[regno].preferred_hard_regno_profit2;
      lra_reg_info[regno].preferred_hard_regno_profit2 = temp;
    }
  if (lra_dump_file != NULL)
    {
      if ((hard_regno = lra_reg_info[regno].preferred_hard_regno1) >= 0)
	fprintf (lra_dump_file,
		 "	Hard reg %d is preferable by r%d with profit %d\n",
		 hard_regno, regno,
		 lra_reg_info[regno].preferred_hard_regno_profit1);
      if ((hard_regno = lra_reg_info[regno].preferred_hard_regno2) >= 0)
	fprintf (lra_dump_file,
		 "	Hard reg %d is preferable by r%d with profit %d\n",
		 hard_regno, regno,
		 lra_reg_info[regno].preferred_hard_regno_profit2);
    }
}

/* Check that REGNO living through calls and setjumps, set up conflict
   regs, and clear corresponding bits in PSEUDOS_LIVE_THROUGH_CALLS and
   PSEUDOS_LIVE_THROUGH_SETJUMPS.  */
static inline void
check_pseudos_live_through_calls (int regno)
{
  int hr;

  if (! sparseset_bit_p (pseudos_live_through_calls, regno))
    return;
  sparseset_clear_bit (pseudos_live_through_calls, regno);
  IOR_HARD_REG_SET (lra_reg_info[regno].conflict_hard_regs,
		    call_used_reg_set);

  for (hr = 0; hr < FIRST_PSEUDO_REGISTER; hr++)
    if (HARD_REGNO_CALL_PART_CLOBBERED (hr, PSEUDO_REGNO_MODE (regno)))
      SET_HARD_REG_BIT (lra_reg_info[regno].conflict_hard_regs, hr);
#ifdef ENABLE_CHECKING
  lra_reg_info[regno].call_p = true;
#endif
  if (! sparseset_bit_p (pseudos_live_through_setjumps, regno))
    return;
  sparseset_clear_bit (pseudos_live_through_setjumps, regno);
  /* Don't allocate pseudos that cross setjmps or any call, if this
     function receives a nonlocal goto.	 */
  SET_HARD_REG_SET (lra_reg_info[regno].conflict_hard_regs);
}

/* Process insns of the basic block BB to update pseudo live ranges,
   pseudo hard register conflicts, and insn notes.  We do it on
   backward scan of BB insns.  CURR_POINT is the program point where
   BB ends.  The function updates this counter and returns in
   CURR_POINT the program point where BB starts.  */
static void
process_bb_lives (basic_block bb, int &curr_point)
{
  int i, regno, freq;
  unsigned int j;
  bitmap_iterator bi;
  bitmap reg_live_out;
  unsigned int px;
  rtx link, *link_loc;
  bool need_curr_point_incr;

  reg_live_out = df_get_live_out (bb);
  sparseset_clear (pseudos_live);
  sparseset_clear (pseudos_live_through_calls);
  sparseset_clear (pseudos_live_through_setjumps);
  REG_SET_TO_HARD_REG_SET (hard_regs_live, reg_live_out);
  AND_COMPL_HARD_REG_SET (hard_regs_live, eliminable_regset);
  AND_COMPL_HARD_REG_SET (hard_regs_live, lra_no_alloc_regs);
  EXECUTE_IF_SET_IN_BITMAP (reg_live_out, FIRST_PSEUDO_REGISTER, j, bi)
    mark_pseudo_live (j, curr_point);

  freq = REG_FREQ_FROM_BB (bb);

  if (lra_dump_file != NULL)
    fprintf (lra_dump_file, "  BB %d\n", bb->index);

  /* Scan the code of this basic block, noting which pseudos and hard
     regs are born or die.

     Note that this loop treats uninitialized values as live until the
     beginning of the block.  For example, if an instruction uses
     (reg:DI foo), and only (subreg:SI (reg:DI foo) 0) is ever set,
     FOO will remain live until the beginning of the block.  Likewise
     if FOO is not set at all.	This is unnecessarily pessimistic, but
     it probably doesn't matter much in practice.  */
  FOR_BB_INSNS_REVERSE (bb, curr_insn)
    {
      bool call_p;
      int dst_regno, src_regno;
      rtx set;
      struct lra_insn_reg *reg;

      if (!NONDEBUG_INSN_P (curr_insn))
	continue;

      curr_id = lra_get_insn_recog_data (curr_insn);
      curr_static_id = curr_id->insn_static_data;
      if (lra_dump_file != NULL)
	fprintf (lra_dump_file, "   Insn %u: point = %d\n",
		 INSN_UID (curr_insn), curr_point);

      /* Update max ref width and hard reg usage.  */
      for (reg = curr_id->regs; reg != NULL; reg = reg->next)
	if (reg->regno >= FIRST_PSEUDO_REGISTER
	    && (GET_MODE_SIZE (reg->biggest_mode)
		> GET_MODE_SIZE (lra_reg_info[reg->regno].biggest_mode)))
	  lra_reg_info[reg->regno].biggest_mode = reg->biggest_mode;
	else if (reg->regno < FIRST_PSEUDO_REGISTER)
	  lra_hard_reg_usage[reg->regno] += freq;

      call_p = CALL_P (curr_insn);
      if (complete_info_p
	  && (set = single_set (curr_insn)) != NULL_RTX
	  && REG_P (SET_DEST (set)) && REG_P (SET_SRC (set))
	  /* Check that source regno does not conflict with
	     destination regno to exclude most impossible
	     preferences.  */
	  && ((((src_regno = REGNO (SET_SRC (set))) >= FIRST_PSEUDO_REGISTER
		&& ! sparseset_bit_p (pseudos_live, src_regno))
	       || (src_regno < FIRST_PSEUDO_REGISTER
		   && ! TEST_HARD_REG_BIT (hard_regs_live, src_regno)))
	      /* It might be 'inheritance pseudo <- reload pseudo'.  */
	      || (src_regno >= lra_constraint_new_regno_start
		  && ((int) REGNO (SET_DEST (set))
		      >= lra_constraint_new_regno_start)
		  /* Remember to skip special cases where src/dest regnos are
		     the same, e.g. insn SET pattern has matching constraints
		     like =r,0.  */
		  && src_regno != (int) REGNO (SET_DEST (set)))))
	{
	  int hard_regno = -1, regno = -1;

	  dst_regno = REGNO (SET_DEST (set));
	  if (dst_regno >= lra_constraint_new_regno_start
	      && src_regno >= lra_constraint_new_regno_start)
	    lra_create_copy (dst_regno, src_regno, freq);
	  else if (dst_regno >= lra_constraint_new_regno_start)
	    {
	      if ((hard_regno = src_regno) >= FIRST_PSEUDO_REGISTER)
		hard_regno = reg_renumber[src_regno];
	      regno = dst_regno;
	    }
	  else if (src_regno >= lra_constraint_new_regno_start)
	    {
	      if ((hard_regno = dst_regno) >= FIRST_PSEUDO_REGISTER)
		hard_regno = reg_renumber[dst_regno];
	      regno = src_regno;
	    }
	  if (regno >= 0 && hard_regno >= 0)
	    lra_setup_reload_pseudo_preferenced_hard_reg
	      (regno, hard_regno, freq);
	}

      sparseset_clear (start_living);

      /* Try to avoid unnecessary program point increments, this saves
	 a lot of time in remove_some_program_points_and_update_live_ranges.
	 We only need an increment if something becomes live or dies at this
	 program point.  */
      need_curr_point_incr = false;

      /* Mark each defined value as live.  We need to do this for
	 unused values because they still conflict with quantities
	 that are live at the time of the definition.  */
      for (reg = curr_id->regs; reg != NULL; reg = reg->next)
	if (reg->type != OP_IN)
	  {
	    need_curr_point_incr |= mark_regno_live (reg->regno,
						     reg->biggest_mode,
						     curr_point);
	    check_pseudos_live_through_calls (reg->regno);
	  }

      for (reg = curr_static_id->hard_regs; reg != NULL; reg = reg->next)
	if (reg->type != OP_IN)
	  make_hard_regno_born (reg->regno);

      sparseset_copy (unused_set, start_living);

      sparseset_clear (start_dying);

      /* See which defined values die here.  */
      for (reg = curr_id->regs; reg != NULL; reg = reg->next)
	if (reg->type == OP_OUT && ! reg->early_clobber && ! reg->subreg_p)
	  need_curr_point_incr |= mark_regno_dead (reg->regno,
						   reg->biggest_mode,
						   curr_point);

      for (reg = curr_static_id->hard_regs; reg != NULL; reg = reg->next)
	if (reg->type == OP_OUT && ! reg->early_clobber && ! reg->subreg_p)
	  make_hard_regno_dead (reg->regno);

      if (call_p)
	{
	  if (flag_use_caller_save)
	    {
	      HARD_REG_SET this_call_used_reg_set;
	      get_call_reg_set_usage (curr_insn, &this_call_used_reg_set,
				      call_used_reg_set);

	      EXECUTE_IF_SET_IN_SPARSESET (pseudos_live, j)
		IOR_HARD_REG_SET (lra_reg_info[j].actual_call_used_reg_set,
				  this_call_used_reg_set);
	    }

	  sparseset_ior (pseudos_live_through_calls,
			 pseudos_live_through_calls, pseudos_live);
	  if (cfun->has_nonlocal_label
	      || find_reg_note (curr_insn, REG_SETJMP,
				NULL_RTX) != NULL_RTX)
	    sparseset_ior (pseudos_live_through_setjumps,
			   pseudos_live_through_setjumps, pseudos_live);
	}

      /* Increment the current program point if we must.  */
      if (need_curr_point_incr)
	next_program_point (curr_point, freq);

      sparseset_clear (start_living);

      need_curr_point_incr = false;

      /* Mark each used value as live.	*/
      for (reg = curr_id->regs; reg != NULL; reg = reg->next)
	if (reg->type == OP_IN)
	  {
	    need_curr_point_incr |= mark_regno_live (reg->regno,
						     reg->biggest_mode,
						     curr_point);
	    check_pseudos_live_through_calls (reg->regno);
	  }

      for (reg = curr_static_id->hard_regs; reg != NULL; reg = reg->next)
	if (reg->type == OP_IN)
	  make_hard_regno_born (reg->regno);

      if (curr_id->arg_hard_regs != NULL)
	/* Make argument hard registers live.  */
	for (i = 0; (regno = curr_id->arg_hard_regs[i]) >= 0; i++)
	  make_hard_regno_born (regno);

      sparseset_and_compl (dead_set, start_living, start_dying);

      /* Mark early clobber outputs dead.  */
      for (reg = curr_id->regs; reg != NULL; reg = reg->next)
	if (reg->type == OP_OUT && reg->early_clobber && ! reg->subreg_p)
	  need_curr_point_incr |= mark_regno_dead (reg->regno,
						   reg->biggest_mode,
						   curr_point);

      for (reg = curr_static_id->hard_regs; reg != NULL; reg = reg->next)
	if (reg->type == OP_OUT && reg->early_clobber && ! reg->subreg_p)
	  make_hard_regno_dead (reg->regno);

      if (need_curr_point_incr)
	next_program_point (curr_point, freq);

      /* Update notes.	*/
      for (link_loc = &REG_NOTES (curr_insn); (link = *link_loc) != NULL_RTX;)
	{
	  if (REG_NOTE_KIND (link) != REG_DEAD
	      && REG_NOTE_KIND (link) != REG_UNUSED)
	    ;
	  else if (REG_P (XEXP (link, 0)))
	    {
	      regno = REGNO (XEXP (link, 0));
	      if ((REG_NOTE_KIND (link) == REG_DEAD
		   && ! sparseset_bit_p (dead_set, regno))
		  || (REG_NOTE_KIND (link) == REG_UNUSED
		      && ! sparseset_bit_p (unused_set, regno)))
		{
		  *link_loc = XEXP (link, 1);
		  continue;
		}
	      if (REG_NOTE_KIND (link) == REG_DEAD)
		sparseset_clear_bit (dead_set, regno);
	      else if (REG_NOTE_KIND (link) == REG_UNUSED)
		sparseset_clear_bit (unused_set, regno);
	    }
	  link_loc = &XEXP (link, 1);
	}
      EXECUTE_IF_SET_IN_SPARSESET (dead_set, j)
	add_reg_note (curr_insn, REG_DEAD, regno_reg_rtx[j]);
      EXECUTE_IF_SET_IN_SPARSESET (unused_set, j)
	add_reg_note (curr_insn, REG_UNUSED, regno_reg_rtx[j]);
    }

#ifdef EH_RETURN_DATA_REGNO
  if (bb_has_eh_pred (bb))
    for (j = 0; ; ++j)
      {
	unsigned int regno = EH_RETURN_DATA_REGNO (j);

	if (regno == INVALID_REGNUM)
	  break;
	make_hard_regno_born (regno);
      }
#endif

  /* Pseudos can't go in stack regs at the start of a basic block that
     is reached by an abnormal edge. Likewise for call clobbered regs,
     because caller-save, fixup_abnormal_edges and possibly the table
     driven EH machinery are not quite ready to handle such pseudos
     live across such edges.  */
  if (bb_has_abnormal_pred (bb))
    {
#ifdef STACK_REGS
      EXECUTE_IF_SET_IN_SPARSESET (pseudos_live, px)
	lra_reg_info[px].no_stack_p = true;
      for (px = FIRST_STACK_REG; px <= LAST_STACK_REG; px++)
	make_hard_regno_born (px);
#endif
      /* No need to record conflicts for call clobbered regs if we
	 have nonlocal labels around, as we don't ever try to
	 allocate such regs in this case.  */
      if (!cfun->has_nonlocal_label && bb_has_abnormal_call_pred (bb))
	for (px = 0; px < FIRST_PSEUDO_REGISTER; px++)
	  if (call_used_regs[px])
	    make_hard_regno_born (px);
    }

  /* See if we'll need an increment at the end of this basic block.
     An increment is needed if the PSEUDOS_LIVE set is not empty,
     to make sure the finish points are set up correctly.  */
  need_curr_point_incr = (sparseset_cardinality (pseudos_live) > 0);

  EXECUTE_IF_SET_IN_SPARSESET (pseudos_live, i)
    mark_pseudo_dead (i, curr_point);

  EXECUTE_IF_SET_IN_BITMAP (df_get_live_in (bb), FIRST_PSEUDO_REGISTER, j, bi)
    {
      if (sparseset_cardinality (pseudos_live_through_calls) == 0)
	break;
      if (sparseset_bit_p (pseudos_live_through_calls, j))
	check_pseudos_live_through_calls (j);
    }

  if (need_curr_point_incr)
    next_program_point (curr_point, freq);
}

/* Compress pseudo live ranges by removing program points where
   nothing happens.  Complexity of many algorithms in LRA is linear
   function of program points number.  To speed up the code we try to
   minimize the number of the program points here.  */
static void
remove_some_program_points_and_update_live_ranges (void)
{
  unsigned i;
  int n, max_regno;
  int *map;
  lra_live_range_t r, prev_r, next_r;
  sbitmap born_or_dead, born, dead;
  sbitmap_iterator sbi;
  bool born_p, dead_p, prev_born_p, prev_dead_p;

  born = sbitmap_alloc (lra_live_max_point);
  dead = sbitmap_alloc (lra_live_max_point);
  bitmap_clear (born);
  bitmap_clear (dead);
  max_regno = max_reg_num ();
  for (i = FIRST_PSEUDO_REGISTER; i < (unsigned) max_regno; i++)
    {
      for (r = lra_reg_info[i].live_ranges; r != NULL; r = r->next)
	{
	  lra_assert (r->start <= r->finish);
	  bitmap_set_bit (born, r->start);
	  bitmap_set_bit (dead, r->finish);
	}
    }
  born_or_dead = sbitmap_alloc (lra_live_max_point);
  bitmap_ior (born_or_dead, born, dead);
  map = XCNEWVEC (int, lra_live_max_point);
  n = -1;
  prev_born_p = prev_dead_p = false;
  EXECUTE_IF_SET_IN_BITMAP (born_or_dead, 0, i, sbi)
    {
      born_p = bitmap_bit_p (born, i);
      dead_p = bitmap_bit_p (dead, i);
      if ((prev_born_p && ! prev_dead_p && born_p && ! dead_p)
	  || (prev_dead_p && ! prev_born_p && dead_p && ! born_p))
	{
	  map[i] = n;
	  lra_point_freq[n] = MAX (lra_point_freq[n], lra_point_freq[i]);
	}
      else
	{
	  map[i] = ++n;
	  lra_point_freq[n] = lra_point_freq[i];
	}
      prev_born_p = born_p;
      prev_dead_p = dead_p;
    }
  sbitmap_free (born_or_dead);
  sbitmap_free (born);
  sbitmap_free (dead);
  n++;
  if (lra_dump_file != NULL)
    fprintf (lra_dump_file, "Compressing live ranges: from %d to %d - %d%%\n",
	     lra_live_max_point, n, 100 * n / lra_live_max_point);
  if (n < lra_live_max_point)
    {
      lra_live_max_point = n;
      for (i = FIRST_PSEUDO_REGISTER; i < (unsigned) max_regno; i++)
	{
	  for (prev_r = NULL, r = lra_reg_info[i].live_ranges;
	       r != NULL;
	       r = next_r)
	    {
	      next_r = r->next;
	      r->start = map[r->start];
	      r->finish = map[r->finish];
	      if (prev_r == NULL || prev_r->start > r->finish + 1)
		{
		  prev_r = r;
		  continue;
		}
	      prev_r->start = r->start;
	      prev_r->next = next_r;
	      free_live_range (r);
	    }
	}
    }
  free (map);
}

/* Print live ranges R to file F.  */
void
lra_print_live_range_list (FILE *f, lra_live_range_t r)
{
  for (; r != NULL; r = r->next)
    fprintf (f, " [%d..%d]", r->start, r->finish);
  fprintf (f, "\n");
}

DEBUG_FUNCTION void
debug (lra_live_range &ref)
{
  lra_print_live_range_list (stderr, &ref);
}

DEBUG_FUNCTION void
debug (lra_live_range *ptr)
{
  if (ptr)
    debug (*ptr);
  else
    fprintf (stderr, "<nil>\n");
}

/* Print live ranges R to stderr.  */
void
lra_debug_live_range_list (lra_live_range_t r)
{
  lra_print_live_range_list (stderr, r);
}

/* Print live ranges of pseudo REGNO to file F.	 */
static void
print_pseudo_live_ranges (FILE *f, int regno)
{
  if (lra_reg_info[regno].live_ranges == NULL)
    return;
  fprintf (f, " r%d:", regno);
  lra_print_live_range_list (f, lra_reg_info[regno].live_ranges);
}

/* Print live ranges of pseudo REGNO to stderr.	 */
void
lra_debug_pseudo_live_ranges (int regno)
{
  print_pseudo_live_ranges (stderr, regno);
}

/* Print live ranges of all pseudos to file F.	*/
static void
print_live_ranges (FILE *f)
{
  int i, max_regno;

  max_regno = max_reg_num ();
  for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
    print_pseudo_live_ranges (f, i);
}

/* Print live ranges of all pseudos to stderr.	*/
void
lra_debug_live_ranges (void)
{
  print_live_ranges (stderr);
}

/* Compress pseudo live ranges.	 */
static void
compress_live_ranges (void)
{
  remove_some_program_points_and_update_live_ranges ();
  if (lra_dump_file != NULL)
    {
      fprintf (lra_dump_file, "Ranges after the compression:\n");
      print_live_ranges (lra_dump_file);
    }
}

/* The number of the current live range pass.  */
int lra_live_range_iter;

/* The main entry function creates live ranges only for memory pseudos
   (or for all ones if ALL_P), set up CONFLICT_HARD_REGS for
   the pseudos.	 */
void
lra_create_live_ranges (bool all_p)
{
  basic_block bb;
  int i, hard_regno, max_regno = max_reg_num ();
  int curr_point;
  bool have_referenced_pseudos = false;

  timevar_push (TV_LRA_CREATE_LIVE_RANGES);

  complete_info_p = all_p;
  if (lra_dump_file != NULL)
    fprintf (lra_dump_file,
	     "\n********** Pseudo live ranges #%d: **********\n\n",
	     ++lra_live_range_iter);
  memset (lra_hard_reg_usage, 0, sizeof (lra_hard_reg_usage));
  for (i = 0; i < max_regno; i++)
    {
      lra_reg_info[i].live_ranges = NULL;
      CLEAR_HARD_REG_SET (lra_reg_info[i].conflict_hard_regs);
      lra_reg_info[i].preferred_hard_regno1 = -1;
      lra_reg_info[i].preferred_hard_regno2 = -1;
      lra_reg_info[i].preferred_hard_regno_profit1 = 0;
      lra_reg_info[i].preferred_hard_regno_profit2 = 0;
#ifdef STACK_REGS
      lra_reg_info[i].no_stack_p = false;
#endif
      /* The biggest mode is already set but its value might be to
	 conservative because of recent transformation.  Here in this
	 file we recalculate it again as it costs practically
	 nothing.  */
      if (regno_reg_rtx[i] != NULL_RTX)
	lra_reg_info[i].biggest_mode = GET_MODE (regno_reg_rtx[i]);
      else
	lra_reg_info[i].biggest_mode = VOIDmode;
#ifdef ENABLE_CHECKING
      lra_reg_info[i].call_p = false;
#endif
      if (i >= FIRST_PSEUDO_REGISTER
	  && lra_reg_info[i].nrefs != 0)
	{
	  if ((hard_regno = reg_renumber[i]) >= 0)
	    lra_hard_reg_usage[hard_regno] += lra_reg_info[i].freq;
	  have_referenced_pseudos = true;
	}
    }
  lra_free_copies ();
 
  /* Under some circumstances, we can have functions without pseudo
     registers.  For such functions, lra_live_max_point will be 0,
     see e.g. PR55604, and there's nothing more to do for us here.  */
  if (! have_referenced_pseudos)
    {
      timevar_pop (TV_LRA_CREATE_LIVE_RANGES);
      return;
    }

  pseudos_live = sparseset_alloc (max_regno);
  pseudos_live_through_calls = sparseset_alloc (max_regno);
  pseudos_live_through_setjumps = sparseset_alloc (max_regno);
  start_living = sparseset_alloc (max_regno);
  start_dying = sparseset_alloc (max_regno);
  dead_set = sparseset_alloc (max_regno);
  unused_set = sparseset_alloc (max_regno);
  curr_point = 0;
  point_freq_vec.create (get_max_uid () * 2);
  lra_point_freq = point_freq_vec.address ();
  int *post_order_rev_cfg = XNEWVEC (int, last_basic_block_for_fn (cfun));
  int n_blocks_inverted = inverted_post_order_compute (post_order_rev_cfg);
  lra_assert (n_blocks_inverted == n_basic_blocks_for_fn (cfun));
  for (i = n_blocks_inverted - 1; i >= 0; --i)
    {
      bb = BASIC_BLOCK_FOR_FN (cfun, post_order_rev_cfg[i]);
      if (bb == EXIT_BLOCK_PTR_FOR_FN (cfun) || bb
	  == ENTRY_BLOCK_PTR_FOR_FN (cfun))
	continue;
      process_bb_lives (bb, curr_point);
    }
  free (post_order_rev_cfg);
  lra_live_max_point = curr_point;
  gcc_checking_assert (lra_live_max_point > 0);
  if (lra_dump_file != NULL)
    print_live_ranges (lra_dump_file);
  /* Clean up.	*/
  sparseset_free (unused_set);
  sparseset_free (dead_set);
  sparseset_free (start_dying);
  sparseset_free (start_living);
  sparseset_free (pseudos_live_through_calls);
  sparseset_free (pseudos_live_through_setjumps);
  sparseset_free (pseudos_live);
  compress_live_ranges ();
  timevar_pop (TV_LRA_CREATE_LIVE_RANGES);
}

/* Finish all live ranges.  */
void
lra_clear_live_ranges (void)
{
  int i;

  for (i = 0; i < max_reg_num (); i++)
    free_live_range_list (lra_reg_info[i].live_ranges);
  point_freq_vec.release ();
}

/* Initialize live ranges data once per function.  */
void
lra_live_ranges_init (void)
{
  live_range_pool = create_alloc_pool ("live ranges",
				       sizeof (struct lra_live_range), 100);
}

/* Finish live ranges data once per function.  */
void
lra_live_ranges_finish (void)
{
  free_alloc_pool (live_range_pool);
}