path: root/gcc/ira.c

/* Integrated Register Allocator (IRA) entry point.
   Copyright (C) 2006, 2007, 2008
   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/>.  */

/* The integrated register allocator (IRA) is a
   regional register allocator performing graph coloring on a top-down
   traversal of nested regions.  Graph coloring in a region is based
   on Chaitin-Briggs algorithm.  It is called integrated because
   register coalescing, register live range splitting, and choosing a
   better hard register are done on-the-fly during coloring.  Register
   coalescing and choosing a cheaper hard register is done by hard
   register preferencing during hard register assigning.  The live
   range splitting is a byproduct of the regional register allocation.

   Major IRA notions are:

     o *Region* is a part of CFG where graph coloring based on
       Chaitin-Briggs algorithm is done.  IRA can work on any set of
       nested CFG regions forming a tree.  Currently the regions are
       the entire function for the root region and natural loops for
       the other regions.  Therefore data structure representing a
       region is called loop_tree_node.

     o *Cover class* is a register class belonging to a set of
       non-intersecting register classes containing all of the
       hard-registers available for register allocation.  The set of
       all cover classes for a target is defined in the corresponding
       machine-description file according some criteria.  Such notion
       is needed because Chaitin-Briggs algorithm works on
       non-intersected register classes.

     o *Allocno* represents the live range of a pseudo-register in a
       region.  Besides the obvious attributes like the corresponding
       pseudo-register number, cover class, conflicting allocnos and
       conflicting hard-registers, there are a few allocno attributes
       which are important for understanding the allocation algorithm:

       - *Live ranges*.  This is a list of ranges of *program
         points* where the allocno lives.  Program points represent
         places where a pseudo can be born or become dead (there are
         approximately two times more program points than the insns)
         and they are represented by integers starting with 0.  The
         live ranges are used to find conflicts between allocnos of
         different cover classes.  They also play very important role
         for the transformation of the IRA internal representation of
         several regions into a one region representation.  The later is
         used during the reload pass work because each allocno
         represents all of the corresponding pseudo-registers.

       - *Hard-register costs*.  This is a vector of size equal to the
         number of available hard-registers of the allocno's cover
         class.  The cost of a callee-clobbered hard-register for an
         allocno is increased by the cost of save/restore code around
         the calls through the given allocno's life.  If the allocno
         is a move instruction operand and another operand is a
         hard-register of the allocno's cover class, the cost of the
         hard-register is decreased by the move cost.

         When an allocno is assigned, the hard-register with minimal
         full cost is used.  Initially, a hard-register's full cost is
         the corresponding value from the hard-register's cost vector.
         If the allocno is connected by a *copy* (see below) to
         another allocno which has just received a hard-register, the
         cost of the hard-register is decreased.  Before choosing a
         hard-register for an allocno, the allocno's current costs of
         the hard-registers are modified by the conflict hard-register
         costs of all of the conflicting allocnos which are not
         assigned yet.

       - *Conflict hard-register costs*.  This is a vector of the same
         size as the hard-register costs vector.  To permit an
         unassigned allocno to get a better hard-register, IRA uses
         this vector to calculate the final full cost of the
         available hard-registers.  Conflict hard-register costs of an
         unassigned allocno are also changed with a change of the
         hard-register cost of the allocno when a copy involving the
         allocno is processed as described above.  This is done to
         show other unassigned allocnos that a given allocno prefers
         some hard-registers in order to remove the move instruction
         corresponding to the copy.

     o *Cap*.  If a pseudo-register does not live in a region but
       lives in a nested region, IRA creates a special allocno called
       a cap in the outer region.  A region cap is also created for a
       subregion cap.

     o *Copy*.  Allocnos can be connected by copies.  Copies are used
       to modify hard-register costs for allocnos during coloring.
       Such modifications reflects a preference to use the same
       hard-register for the allocnos connected by copies.  Usually
       copies are created for move insns (in this case it results in
       register coalescing).  But IRA also creates copies for operands
       of an insn which should be assigned to the same hard-register
       due to constraints in the machine description (it usually
       results in removing a move generated in reload to satisfy
       the constraints) and copies referring to the allocno which is
       the output operand of an instruction and the allocno which is
       an input operand dying in the instruction (creation of such
       copies results in less register shuffling).  IRA *does not*
       create copies between the same register allocnos from different
       regions because we use another technique for propagating
       hard-register preference on the borders of regions.

   Allocnos (including caps) for the upper region in the region tree
   *accumulate* information important for coloring from allocnos with
   the same pseudo-register from nested regions.  This includes
   hard-register and memory costs, conflicts with hard-registers,
   allocno conflicts, allocno copies and more.  *Thus, attributes for
   allocnos in a region have the same values as if the region had no
   subregions*.  It means that attributes for allocnos in the
   outermost region corresponding to the function have the same values
   as though the allocation used only one region which is the entire
   function.  It also means that we can look at IRA work as if the
   first IRA did allocation for all function then it improved the
   allocation for loops then their subloops and so on.

   IRA major passes are:

     o Building IRA internal representation which consists of the
       following subpasses:

       * First, IRA builds regions and creates allocnos (file
         ira-build.c) and initializes most of their attributes.

       * Then IRA finds a cover class for each allocno and calculates
         its initial (non-accumulated) cost of memory and each
         hard-register of its cover class (file ira-cost.c).

       * IRA creates live ranges of each allocno, calulates register
         pressure for each cover class in each region, sets up
         conflict hard registers for each allocno and info about calls
         the allocno lives through (file ira-lives.c).

       * IRA removes low register pressure loops from the regions
         mostly to speed IRA up (file ira-build.c).

       * IRA propagates accumulated allocno info from lower region
         allocnos to corresponding upper region allocnos (file
         ira-build.c).

       * IRA creates all caps (file ira-build.c).

       * Having live-ranges of allocnos and their cover classes, IRA
         creates conflicting allocnos of the same cover class for each
         allocno.  Conflicting allocnos are stored as a bit vector or
         array of pointers to the conflicting allocnos whatever is
         more profitable (file ira-conflicts.c).  At this point IRA
         creates allocno copies.

     o Coloring.  Now IRA has all necessary info to start graph coloring
       process.  It is done in each region on top-down traverse of the
       region tree (file ira-color.c).  There are following subpasses:
        
       * Optional aggressive coalescing of allocnos in the region.

       * Putting allocnos onto the coloring stack.  IRA uses Briggs
         optimistic coloring which is a major improvement over
         Chaitin's coloring.  Therefore IRA does not spill allocnos at
         this point.  There is some freedom in the order of putting
         allocnos on the stack which can affect the final result of
         the allocation.  IRA uses some heuristics to improve the order.

       * Popping the allocnos from the stack and assigning them hard
         registers.  If IRA can not assign a hard register to an
         allocno and the allocno is coalesced, IRA undoes the
         coalescing and puts the uncoalesced allocnos onto the stack in
         the hope that some such allocnos will get a hard register
         separately.  If IRA fails to assign hard register or memory
         is more profitable for it, IRA spills the allocno.  IRA
         assigns the allocno the hard-register with minimal full
         allocation cost which reflects the cost of usage of the
         hard-register for the allocno and cost of usage of the
         hard-register for allocnos conflicting with given allocno.

       * After allono assigning in the region, IRA modifies the hard
         register and memory costs for the corresponding allocnos in
         the subregions to reflect the cost of possible loads, stores,
         or moves on the border of the region and its subregions.
         When default regional allocation algorithm is used
         (-fira-algorithm=mixed), IRA just propagates the assignment
         for allocnos if the register pressure in the region for the
         corresponding cover class is less than number of available
         hard registers for given cover class.

     o Spill/restore code moving.  When IRA performs an allocation
       by traversing regions in top-down order, it does not know what
       happens below in the region tree.  Therefore, sometimes IRA
       misses opportunities to perform a better allocation.  A simple
       optimization tries to improve allocation in a region having
       subregions and containing in another region.  If the
       corresponding allocnos in the subregion are spilled, it spills
       the region allocno if it is profitable.  The optimization
       implements a simple iterative algorithm performing profitable
       transformations while they are still possible.  It is fast in
       practice, so there is no real need for a better time complexity
       algorithm.

     o Code change.  After coloring, two allocnos representing the same
       pseudo-register outside and inside a region respectively may be
       assigned to different locations (hard-registers or memory).  In
       this case IRA creates and uses a new pseudo-register inside the
       region and adds code to move allocno values on the region's
       borders.  This is done during top-down traversal of the regions
       (file ira-emit.c).  In some complicated cases IRA can create a
       new allocno to move allocno values (e.g. when a swap of values
       stored in two hard-registers is needed).  At this stage, the
       new allocno is marked as spilled.  IRA still creates the
       pseudo-register and the moves on the region borders even when
       both allocnos were assigned to the same hard-register.  If the
       reload pass spills a pseudo-register for some reason, the
       effect will be smaller because another allocno will still be in
       the hard-register.  In most cases, this is better then spilling
       both allocnos.  If reload does not change the allocation
       for the two pseudo-registers, the trivial move will be removed
       by post-reload optimizations.  IRA does not generate moves for
       allocnos assigned to the same hard register when the default
       regional allocation algorithm is used and the register pressure
       in the region for the corresponding allocno cover class is less
       than number of available hard registers for given cover class.
       IRA also does some optimizations to remove redundant stores and
       to reduce code duplication on the region borders.

     o Flattening internal representation.  After changing code, IRA
       transforms its internal representation for several regions into
       one region representation (file ira-build.c).  This process is
       called IR flattening.  Such process is more complicated than IR
       rebuilding would be, but is much faster.

     o After IR flattening, IRA tries to assign hard registers to all
       spilled allocnos.  This is impelemented by a simple and fast
       priority coloring algorithm (see function
       ira_reassign_conflict_allocnos::ira-color.c).  Here new allocnos
       created during the code change pass can be assigned to hard
       registers.

     o At the end IRA calls the reload pass.  The reload pass
       communicates with IRA through several functions in file
       ira-color.c to improve its decisions in

       * sharing stack slots for the spilled pseudos based on IRA info
         about pseudo-register conflicts.

       * reassigning hard-registers to all spilled pseudos at the end
         of each reload iteration.

       * choosing a better hard-register to spill based on IRA info
         about pseudo-register live ranges and the register pressure
         in places where the pseudo-register lives.

   IRA uses a lot of data representing the target processors.  These
   data are initilized in file ira.c.

   If function has no loops (or the loops are ignored when
   -fira-algorithm=CB is used), we have classic Chaitin-Briggs
   coloring (only instead of separate pass of coalescing, we use hard
   register preferencing).  In such case, IRA works much faster
   because many things are not made (like IR flattening, the
   spill/restore optimization, and the code change).

   Literature is worth to read for better understanding the code:

   o Preston Briggs, Keith D. Cooper, Linda Torczon.  Improvements to
     Graph Coloring Register Allocation.

   o David Callahan, Brian Koblenz.  Register allocation via
     hierarchical graph coloring.

   o Keith Cooper, Anshuman Dasgupta, Jason Eckhardt. Revisiting Graph
     Coloring Register Allocation: A Study of the Chaitin-Briggs and
     Callahan-Koblenz Algorithms.

   o Guei-Yuan Lueh, Thomas Gross, and Ali-Reza Adl-Tabatabai. Global
     Register Allocation Based on Graph Fusion.

   o Vladimir Makarov. The Integrated Register Allocator for GCC.

   o Vladimir Makarov.  The top-down register allocator for irregular
     register file architectures.

*/


#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "regs.h"
#include "rtl.h"
#include "tm_p.h"
#include "target.h"
#include "flags.h"
#include "obstack.h"
#include "bitmap.h"
#include "hard-reg-set.h"
#include "basic-block.h"
#include "expr.h"
#include "recog.h"
#include "params.h"
#include "timevar.h"
#include "tree-pass.h"
#include "output.h"
#include "reload.h"
#include "errors.h"
#include "integrate.h"
#include "df.h"
#include "ggc.h"
#include "ira-int.h"


/* A modified value of flag `-fira-verbose' used internally.  */
int internal_flag_ira_verbose;

/* Dump file of the allocator if it is not NULL.  */
FILE *ira_dump_file;

/* Pools for allocnos, copies, allocno live ranges.  */
alloc_pool allocno_pool, copy_pool, allocno_live_range_pool;

/* The number of elements in the following array.  */
int ira_spilled_reg_stack_slots_num;

/* The following array contains info about spilled pseudo-registers
   stack slots used in current function so far.  */
struct ira_spilled_reg_stack_slot *ira_spilled_reg_stack_slots;

/* Correspondingly overall cost of the allocation, cost of the
   allocnos assigned to hard-registers, cost of the allocnos assigned
   to memory, cost of loads, stores and register move insns generated
   for pseudo-register live range splitting (see ira-emit.c).  */
int ira_overall_cost;
int ira_reg_cost, ira_mem_cost;
int ira_load_cost, ira_store_cost, ira_shuffle_cost;
int ira_move_loops_num, ira_additional_jumps_num;

/* Map: hard regs X modes -> set of hard registers for storing value
   of given mode starting with given hard register.  */
HARD_REG_SET ira_reg_mode_hard_regset[FIRST_PSEUDO_REGISTER][NUM_MACHINE_MODES];

/* The following two variables are array analogs of the macros
   MEMORY_MOVE_COST and REGISTER_MOVE_COST.  */
short int ira_memory_move_cost[MAX_MACHINE_MODE][N_REG_CLASSES][2];
move_table *ira_register_move_cost[MAX_MACHINE_MODE];

/* Similar to may_move_in_cost but it is calculated in IRA instead of
   regclass.  Another difference is that we take only available hard
   registers into account to figure out that one register class is a
   subset of the another one.  */
move_table *ira_may_move_in_cost[MAX_MACHINE_MODE];

/* Similar to may_move_out_cost but it is calculated in IRA instead of
   regclass.  Another difference is that we take only available hard
   registers into account to figure out that one register class is a
   subset of the another one.  */
move_table *ira_may_move_out_cost[MAX_MACHINE_MODE];

/* Register class subset relation: TRUE if the first class is a subset
   of the second one considering only hard registers available for the
   allocation.  */
int ira_class_subset_p[N_REG_CLASSES][N_REG_CLASSES];

/* Temporary hard reg set used for a different calculation.  */
static HARD_REG_SET temp_hard_regset;



/* The function sets up the map IRA_REG_MODE_HARD_REGSET.  */
static void
setup_reg_mode_hard_regset (void)
{
  int i, m, hard_regno;

  for (m = 0; m < NUM_MACHINE_MODES; m++)
    for (hard_regno = 0; hard_regno < FIRST_PSEUDO_REGISTER; hard_regno++)
      {
	CLEAR_HARD_REG_SET (ira_reg_mode_hard_regset[hard_regno][m]);
	for (i = hard_regno_nregs[hard_regno][m] - 1; i >= 0; i--)
	  if (hard_regno + i < FIRST_PSEUDO_REGISTER)
	    SET_HARD_REG_BIT (ira_reg_mode_hard_regset[hard_regno][m],
			      hard_regno + i);
      }
}



/* Hard registers that can not be used for the register allocator for
   all functions of the current compilation unit.  */
static HARD_REG_SET no_unit_alloc_regs;

/* Array of the number of hard registers of given class which are
   available for allocation.  The order is defined by the
   allocation order.  */
short ira_class_hard_regs[N_REG_CLASSES][FIRST_PSEUDO_REGISTER];

/* The number of elements of the above array for given register
   class.  */
int ira_class_hard_regs_num[N_REG_CLASSES];

/* Index (in ira_class_hard_regs) for given register class and hard
   register (in general case a hard register can belong to several
   register classes).  The index is negative for hard registers
   unavailable for the allocation. */
short ira_class_hard_reg_index[N_REG_CLASSES][FIRST_PSEUDO_REGISTER];

/* The function sets up the three arrays declared above.  */
static void
setup_class_hard_regs (void)
{
  int cl, i, hard_regno, n;
  HARD_REG_SET processed_hard_reg_set;

  ira_assert (SHRT_MAX >= FIRST_PSEUDO_REGISTER);
  /* We could call ORDER_REGS_FOR_LOCAL_ALLOC here (it is usually
     putting hard callee-used hard registers first).  But our
     heuristics work better.  */
  for (cl = (int) N_REG_CLASSES - 1; cl >= 0; cl--)
    {
      COPY_HARD_REG_SET (temp_hard_regset, reg_class_contents[cl]);
      AND_COMPL_HARD_REG_SET (temp_hard_regset, no_unit_alloc_regs);
      CLEAR_HARD_REG_SET (processed_hard_reg_set);
      for (n = 0, i = 0; i < FIRST_PSEUDO_REGISTER; i++)
	{
#ifdef REG_ALLOC_ORDER
	  hard_regno = reg_alloc_order[i];
#else
	  hard_regno = i;
#endif	  
	  if (TEST_HARD_REG_BIT (processed_hard_reg_set, hard_regno))
	    continue;
	  SET_HARD_REG_BIT (processed_hard_reg_set, hard_regno);
      	  if (! TEST_HARD_REG_BIT (temp_hard_regset, hard_regno))
	    ira_class_hard_reg_index[cl][hard_regno] = -1;
	  else
	    {
	      ira_class_hard_reg_index[cl][hard_regno] = n;
	      ira_class_hard_regs[cl][n++] = hard_regno;
	    }
	}
      ira_class_hard_regs_num[cl] = n;
    }
}

/* Number of given class hard registers available for the register
   allocation for given classes.  */
int ira_available_class_regs[N_REG_CLASSES];

/* Set up IRA_AVAILABLE_CLASS_REGS.  */
static void
setup_available_class_regs (void)
{
  int i, j;

  memset (ira_available_class_regs, 0, sizeof (ira_available_class_regs));
  for (i = 0; i < N_REG_CLASSES; i++)
    {
      COPY_HARD_REG_SET (temp_hard_regset, reg_class_contents[i]);
      AND_COMPL_HARD_REG_SET (temp_hard_regset, no_unit_alloc_regs);
      for (j = 0; j < FIRST_PSEUDO_REGISTER; j++)
	if (TEST_HARD_REG_BIT (temp_hard_regset, j))
	  ira_available_class_regs[i]++;
    }
}

/* Set up global variables defining info about hard registers for the
   allocation.  These depend on USE_HARD_FRAME_P whose TRUE value means
   that we can use the hard frame pointer for the allocation.  */
static void
setup_alloc_regs (bool use_hard_frame_p)
{
  COPY_HARD_REG_SET (no_unit_alloc_regs, fixed_reg_set);
  if (! use_hard_frame_p)
    SET_HARD_REG_BIT (no_unit_alloc_regs, HARD_FRAME_POINTER_REGNUM);
  setup_class_hard_regs ();
  setup_available_class_regs ();
}



/* Set up IRA_MEMORY_MOVE_COST, IRA_REGISTER_MOVE_COST.  */
static void
setup_class_subset_and_memory_move_costs (void)
{
  int cl, cl2;
  enum machine_mode mode;
  HARD_REG_SET temp_hard_regset2;

  for (mode = 0; mode < MAX_MACHINE_MODE; mode++)
    ira_memory_move_cost[mode][NO_REGS][0]
      = ira_memory_move_cost[mode][NO_REGS][1] = SHRT_MAX;
  for (cl = (int) N_REG_CLASSES - 1; cl >= 0; cl--)
    {
      if (cl != (int) NO_REGS)
	for (mode = 0; mode < MAX_MACHINE_MODE; mode++)
	  {
	    ira_memory_move_cost[mode][cl][0] = MEMORY_MOVE_COST (mode, cl, 0);
	    ira_memory_move_cost[mode][cl][1] = MEMORY_MOVE_COST (mode, cl, 1);
	    /* Costs for NO_REGS are used in cost calculation on the
	       1st pass when the preferred register classes are not
	       known yet.  In this case we take the best scenario.  */
	    if (ira_memory_move_cost[mode][NO_REGS][0]
		> ira_memory_move_cost[mode][cl][0])
	      ira_memory_move_cost[mode][NO_REGS][0]
		= ira_memory_move_cost[mode][cl][0];
	    if (ira_memory_move_cost[mode][NO_REGS][1]
		> ira_memory_move_cost[mode][cl][1])
	      ira_memory_move_cost[mode][NO_REGS][1]
		= ira_memory_move_cost[mode][cl][1];
	  }
      for (cl2 = (int) N_REG_CLASSES - 1; cl2 >= 0; cl2--)
	{
	  COPY_HARD_REG_SET (temp_hard_regset, reg_class_contents[cl]);
	  AND_COMPL_HARD_REG_SET (temp_hard_regset, no_unit_alloc_regs);
	  COPY_HARD_REG_SET (temp_hard_regset2, reg_class_contents[cl2]);
	  AND_COMPL_HARD_REG_SET (temp_hard_regset2, no_unit_alloc_regs);
	  ira_class_subset_p[cl][cl2]
	    = hard_reg_set_subset_p (temp_hard_regset, temp_hard_regset2);
	}
    }
}



/* Define the following macro if allocation through malloc if
   preferable.  */
#define IRA_NO_OBSTACK

#ifndef IRA_NO_OBSTACK
/* Obstack used for storing all dynamic data (except bitmaps) of the
   IRA.  */
static struct obstack ira_obstack;
#endif

/* Obstack used for storing all bitmaps of the IRA.  */
static struct bitmap_obstack ira_bitmap_obstack;

/* Allocate memory of size LEN for IRA data.  */
void *
ira_allocate (size_t len)
{
  void *res;

#ifndef IRA_NO_OBSTACK
  res = obstack_alloc (&ira_obstack, len);
#else
  res = xmalloc (len);
#endif
  return res;
}

/* Reallocate memory PTR of size LEN for IRA data.  */
void *
ira_reallocate (void *ptr, size_t len)
{
  void *res;

#ifndef IRA_NO_OBSTACK
  res = obstack_alloc (&ira_obstack, len);
#else
  res = xrealloc (ptr, len);
#endif
  return res;
}

/* Free memory ADDR allocated for IRA data.  */
void
ira_free (void *addr ATTRIBUTE_UNUSED)
{
#ifndef IRA_NO_OBSTACK
  /* do nothing */
#else
  free (addr);
#endif
}


/* Allocate and returns bitmap for IRA.  */
bitmap
ira_allocate_bitmap (void)
{
  return BITMAP_ALLOC (&ira_bitmap_obstack);
}

/* Free bitmap B allocated for IRA.  */
void
ira_free_bitmap (bitmap b ATTRIBUTE_UNUSED)
{
  /* do nothing */
}



/* Output information about allocation of all allocnos (except for
   caps) into file F.  */
void
ira_print_disposition (FILE *f)
{
  int i, n, max_regno;
  ira_allocno_t a;
  basic_block bb;

  fprintf (f, "Disposition:");
  max_regno = max_reg_num ();
  for (n = 0, i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
    for (a = ira_regno_allocno_map[i];
	 a != NULL;
	 a = ALLOCNO_NEXT_REGNO_ALLOCNO (a))
      {
	if (n % 4 == 0)
	  fprintf (f, "\n");
	n++;
	fprintf (f, " %4d:r%-4d", ALLOCNO_NUM (a), ALLOCNO_REGNO (a));
	if ((bb = ALLOCNO_LOOP_TREE_NODE (a)->bb) != NULL)
	  fprintf (f, "b%-3d", bb->index);
	else
	  fprintf (f, "l%-3d", ALLOCNO_LOOP_TREE_NODE (a)->loop->num);
	if (ALLOCNO_HARD_REGNO (a) >= 0)
	  fprintf (f, " %3d", ALLOCNO_HARD_REGNO (a));
	else
	  fprintf (f, " mem");
      }
  fprintf (f, "\n");
}

/* Outputs information about allocation of all allocnos into
   stderr.  */
void
ira_debug_disposition (void)
{
  ira_print_disposition (stderr);
}



/* For each reg class, table listing all the classes contained in it
   (excluding the class itself.  Non-allocatable registers are
   excluded from the consideration).  */
static enum reg_class alloc_reg_class_subclasses[N_REG_CLASSES][N_REG_CLASSES];

/* Initialize the table of subclasses of each reg class.  */
static void
setup_reg_subclasses (void)
{
  int i, j;
  HARD_REG_SET temp_hard_regset2;

  for (i = 0; i < N_REG_CLASSES; i++)
    for (j = 0; j < N_REG_CLASSES; j++)
      alloc_reg_class_subclasses[i][j] = LIM_REG_CLASSES;

  for (i = 0; i < N_REG_CLASSES; i++)
    {
      if (i == (int) NO_REGS)
	continue;

      COPY_HARD_REG_SET (temp_hard_regset, reg_class_contents[i]);
      AND_COMPL_HARD_REG_SET (temp_hard_regset, no_unit_alloc_regs);
      if (hard_reg_set_empty_p (temp_hard_regset))
	continue;
      for (j = 0; j < N_REG_CLASSES; j++)
	if (i != j)
	  {
	    enum reg_class *p;

	    COPY_HARD_REG_SET (temp_hard_regset2, reg_class_contents[j]);
	    AND_COMPL_HARD_REG_SET (temp_hard_regset2, no_unit_alloc_regs);
	    if (! hard_reg_set_subset_p (temp_hard_regset,
					 temp_hard_regset2))
	      continue;
	    p = &alloc_reg_class_subclasses[j][0];
	    while (*p != LIM_REG_CLASSES) p++;
	    *p = (enum reg_class) i;
	  }
    }
}



/* Number of cover classes.  Cover classes is non-intersected register
   classes containing all hard-registers available for the
   allocation.  */
int ira_reg_class_cover_size;

/* The array containing cover classes (see also comments for macro
   IRA_COVER_CLASSES).  Only first IRA_REG_CLASS_COVER_SIZE elements are
   used for this.  */
enum reg_class ira_reg_class_cover[N_REG_CLASSES];

/* The number of elements in the subsequent array.  */
int ira_important_classes_num;

/* The array containing non-empty classes (including non-empty cover
   classes) which are subclasses of cover classes.  Such classes is
   important for calculation of the hard register usage costs.  */
enum reg_class ira_important_classes[N_REG_CLASSES];

/* The array containing indexes of important classes in the previous
   array.  The array elements are defined only for important
   classes.  */
int ira_important_class_nums[N_REG_CLASSES];

/* Check IRA_COVER_CLASSES and sets the four global variables defined
   above.  */
static void
setup_cover_and_important_classes (void)
{
  int i, j;
  enum reg_class cl;
  const enum reg_class *classes;
  HARD_REG_SET temp_hard_regset2;

  classes = targetm.ira_cover_classes ();
  ira_reg_class_cover_size = 0;
  for (i = 0; (cl = classes[i]) != LIM_REG_CLASSES; i++)
    {
      for (j = 0; j < i; j++)
	if (reg_classes_intersect_p (cl, classes[j]))
	  gcc_unreachable ();
      COPY_HARD_REG_SET (temp_hard_regset, reg_class_contents[cl]);
      AND_COMPL_HARD_REG_SET (temp_hard_regset, no_unit_alloc_regs);
      if (! hard_reg_set_empty_p (temp_hard_regset))
	ira_reg_class_cover[ira_reg_class_cover_size++] = cl;
    }
  ira_important_classes_num = 0;
  for (cl = 0; cl < N_REG_CLASSES; cl++)
    {
      COPY_HARD_REG_SET (temp_hard_regset, reg_class_contents[cl]);
      AND_COMPL_HARD_REG_SET (temp_hard_regset, no_unit_alloc_regs);
      if (! hard_reg_set_empty_p (temp_hard_regset))
	for (j = 0; j < ira_reg_class_cover_size; j++)
	  {
	    COPY_HARD_REG_SET (temp_hard_regset, reg_class_contents[cl]);
	    AND_COMPL_HARD_REG_SET (temp_hard_regset, no_unit_alloc_regs);
	    COPY_HARD_REG_SET (temp_hard_regset2,
			       reg_class_contents[ira_reg_class_cover[j]]);
	    AND_COMPL_HARD_REG_SET (temp_hard_regset2, no_unit_alloc_regs);
	    if (cl == ira_reg_class_cover[j]
		|| (hard_reg_set_subset_p (temp_hard_regset, temp_hard_regset2)
		    && ! hard_reg_set_equal_p (temp_hard_regset,
					       temp_hard_regset2)))
	      {
		ira_important_class_nums[cl] = ira_important_classes_num;
		ira_important_classes[ira_important_classes_num++] = cl;
	      }
	  }
    }
}

/* Map of all register classes to corresponding cover class containing
   the given class.  If given class is not a subset of a cover class,
   we translate it into the cheapest cover class.  */
enum reg_class ira_class_translate[N_REG_CLASSES];

/* Set up array IRA_CLASS_TRANSLATE.  */
static void
setup_class_translate (void)
{
  enum reg_class cl, cover_class, best_class, *cl_ptr;
  enum machine_mode mode;
  int i, cost, min_cost, best_cost;

  for (cl = 0; cl < N_REG_CLASSES; cl++)
    ira_class_translate[cl] = NO_REGS;
  for (i = 0; i < ira_reg_class_cover_size; i++)
    {
      cover_class = ira_reg_class_cover[i];
      for (cl_ptr = &alloc_reg_class_subclasses[cover_class][0];
	   (cl = *cl_ptr) != LIM_REG_CLASSES;
	   cl_ptr++)
	{
	  if (ira_class_translate[cl] == NO_REGS)
	    ira_class_translate[cl] = cover_class;
#ifdef ENABLE_IRA_CHECKING
	  else
	    {
	      COPY_HARD_REG_SET (temp_hard_regset, reg_class_contents[cl]);
	      AND_COMPL_HARD_REG_SET (temp_hard_regset, no_unit_alloc_regs);
	      if (! hard_reg_set_empty_p (temp_hard_regset))
		gcc_unreachable ();
	    }
#endif
	}
      ira_class_translate[cover_class] = cover_class;
    }
  /* For classes which are not fully covered by a cover class (in
     other words covered by more one cover class), use the cheapest
     cover class.  */
  for (cl = 0; cl < N_REG_CLASSES; cl++)
    {
      if (cl == NO_REGS || ira_class_translate[cl] != NO_REGS)
	continue;
      best_class = NO_REGS;
      best_cost = INT_MAX;
      for (i = 0; i < ira_reg_class_cover_size; i++)
	{
	  cover_class = ira_reg_class_cover[i];
	  COPY_HARD_REG_SET (temp_hard_regset,
			     reg_class_contents[cover_class]);
	  AND_HARD_REG_SET (temp_hard_regset, reg_class_contents[cl]);
	  AND_COMPL_HARD_REG_SET (temp_hard_regset, no_unit_alloc_regs);
	  if (! hard_reg_set_empty_p (temp_hard_regset))
	    {
	      min_cost = INT_MAX;
	      for (mode = 0; mode < MAX_MACHINE_MODE; mode++)
		{
		  cost = (ira_memory_move_cost[mode][cl][0]
			  + ira_memory_move_cost[mode][cl][1]);
		  if (min_cost > cost)
		    min_cost = cost;
		}
	      if (best_class == NO_REGS || best_cost > min_cost)
		{
		  best_class = cover_class;
		  best_cost = min_cost;
		}
	    }
	}
      ira_class_translate[cl] = best_class;
    }
}

/* The biggest important reg_class inside of intersection of the two
   reg_classes (that is calculated taking only hard registers
   available for allocation into account).  If the both reg_classes
   contain no hard registers available for allocation, the value is
   calculated by taking all hard-registers including fixed ones into
   account.  */
enum reg_class ira_reg_class_intersect[N_REG_CLASSES][N_REG_CLASSES];

/* The biggest important reg_class inside of union of the two
   reg_classes (that is calculated taking only hard registers
   available for allocation into account).  If the both reg_classes
   contain no hard registers available for allocation, the value is
   calculated by taking all hard-registers including fixed ones into
   account.  In other words, the value is the corresponding
   reg_class_subunion value.  */
enum reg_class ira_reg_class_union[N_REG_CLASSES][N_REG_CLASSES];

/* Set up IRA_REG_CLASS_INTERSECT and IRA_REG_CLASS_UNION.  */
static void
setup_reg_class_intersect_union (void)
{
  int i, cl1, cl2, cl3;
  HARD_REG_SET intersection_set, union_set, temp_set2;

  for (cl1 = 0; cl1 < N_REG_CLASSES; cl1++)
    {
      for (cl2 = 0; cl2 < N_REG_CLASSES; cl2++)
	{
	  ira_reg_class_intersect[cl1][cl2] = NO_REGS;
	  COPY_HARD_REG_SET (temp_hard_regset, reg_class_contents[cl1]);
	  AND_COMPL_HARD_REG_SET (temp_hard_regset, no_unit_alloc_regs);
	  COPY_HARD_REG_SET (temp_set2, reg_class_contents[cl2]);
	  AND_COMPL_HARD_REG_SET (temp_set2, no_unit_alloc_regs);
	  if (hard_reg_set_empty_p (temp_hard_regset)
	      && hard_reg_set_empty_p (temp_set2))
	    {
	      for (i = 0;; i++)
		{
		  cl3 = reg_class_subclasses[cl1][i];
		  if (cl3 == LIM_REG_CLASSES)
		    break;
		  if (reg_class_subset_p (ira_reg_class_intersect[cl1][cl2],
					  cl3))
		    ira_reg_class_intersect[cl1][cl2] = cl3;
		}
	      ira_reg_class_union[cl1][cl2] = reg_class_subunion[cl1][cl2];
	      continue;
	    }
	  ira_reg_class_union[cl1][cl2] = NO_REGS;
	  COPY_HARD_REG_SET (intersection_set, reg_class_contents[cl1]);
	  AND_HARD_REG_SET (intersection_set, reg_class_contents[cl2]);
	  AND_COMPL_HARD_REG_SET (intersection_set, no_unit_alloc_regs);
	  COPY_HARD_REG_SET (union_set, reg_class_contents[cl1]);
	  IOR_HARD_REG_SET (union_set, reg_class_contents[cl2]);
	  AND_COMPL_HARD_REG_SET (union_set, no_unit_alloc_regs);
	  for (i = 0; i < ira_important_classes_num; i++)
	    {
	      cl3 = ira_important_classes[i];
	      COPY_HARD_REG_SET (temp_hard_regset, reg_class_contents[cl3]);
	      AND_COMPL_HARD_REG_SET (temp_hard_regset, no_unit_alloc_regs);
	      if (hard_reg_set_subset_p (temp_hard_regset, intersection_set))
		{
		  COPY_HARD_REG_SET
		    (temp_set2,
		     reg_class_contents[(int)
					ira_reg_class_intersect[cl1][cl2]]);
		  AND_COMPL_HARD_REG_SET (temp_set2, no_unit_alloc_regs);
	 	  if (! hard_reg_set_subset_p (temp_hard_regset, temp_set2)
		      /* Ignore unavailable hard registers and prefer
			 smallest class for debugging purposes.  */
		      || (hard_reg_set_equal_p (temp_hard_regset, temp_set2)
			  && hard_reg_set_subset_p
			     (reg_class_contents[cl3],
			      reg_class_contents
			      [(int) ira_reg_class_intersect[cl1][cl2]])))
		    ira_reg_class_intersect[cl1][cl2] = (enum reg_class) cl3;
		}
	      if (hard_reg_set_subset_p (temp_hard_regset, union_set))
		{
		  COPY_HARD_REG_SET
		    (temp_set2,
		     reg_class_contents[(int) ira_reg_class_union[cl1][cl2]]);
		  AND_COMPL_HARD_REG_SET (temp_set2, no_unit_alloc_regs);
	 	  if (ira_reg_class_union[cl1][cl2] == NO_REGS
		      || (hard_reg_set_subset_p (temp_set2, temp_hard_regset)
		      
			  && (! hard_reg_set_equal_p (temp_set2,
						      temp_hard_regset)
			      /* Ignore unavailable hard registers and
				 prefer smallest class for debugging
				 purposes.  */
			      || hard_reg_set_subset_p
			         (reg_class_contents[cl3],
				  reg_class_contents
				  [(int) ira_reg_class_union[cl1][cl2]]))))
		    ira_reg_class_union[cl1][cl2] = (enum reg_class) cl3;
		}
	    }
	}
    }
}

/* Output all cover classes and the translation map into file F.  */
static void
print_class_cover (FILE *f)
{
  static const char *const reg_class_names[] = REG_CLASS_NAMES;
  int i;

  fprintf (f, "Class cover:\n");
  for (i = 0; i < ira_reg_class_cover_size; i++)
    fprintf (f, " %s", reg_class_names[ira_reg_class_cover[i]]);
  fprintf (f, "\nClass translation:\n");
  for (i = 0; i < N_REG_CLASSES; i++)
    fprintf (f, " %s -> %s\n", reg_class_names[i],
	     reg_class_names[ira_class_translate[i]]);
}

/* Output all cover classes and the translation map into
   stderr.  */
void
ira_debug_class_cover (void)
{
  print_class_cover (stderr);
}

/* Set up different arrays concerning class subsets, cover and
   important classes.  */
static void
find_reg_class_closure (void)
{
  setup_reg_subclasses ();
  if (targetm.ira_cover_classes)
    {
      setup_cover_and_important_classes ();
      setup_class_translate ();
      setup_reg_class_intersect_union ();
    }
}



/* Map: hard register number -> cover class it belongs to.  If the
   corresponding class is NO_REGS, the hard register is not available
   for allocation.  */
enum reg_class ira_hard_regno_cover_class[FIRST_PSEUDO_REGISTER];

/* Set up the array above.  */
static void
setup_hard_regno_cover_class (void)
{
  int i, j;
  enum reg_class cl;

  for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
    {
      ira_hard_regno_cover_class[i] = NO_REGS;
      for (j = 0; j < ira_reg_class_cover_size; j++)
	{
	  cl = ira_reg_class_cover[j];
	  if (ira_class_hard_reg_index[cl][i] >= 0)
	    {
	      ira_hard_regno_cover_class[i] = cl;
	      break;
	    }
	}
	    
    }
}



/* Map: register class x machine mode -> number of hard registers of
   given class needed to store value of given mode.  If the number is
   different, the size will be negative.  */
int ira_reg_class_nregs[N_REG_CLASSES][MAX_MACHINE_MODE];

/* Maximal value of the previous array elements.  */
int ira_max_nregs;

/* Form IRA_REG_CLASS_NREGS map.  */
static void
setup_reg_class_nregs (void)
{
  int m;
  enum reg_class cl;

  ira_max_nregs = -1;
  for (cl = 0; cl < N_REG_CLASSES; cl++)
    for (m = 0; m < MAX_MACHINE_MODE; m++)
      {
	ira_reg_class_nregs[cl][m] = CLASS_MAX_NREGS (cl, m);
	if (ira_max_nregs < ira_reg_class_nregs[cl][m])
	  ira_max_nregs = ira_reg_class_nregs[cl][m];
      }
}



/* Array whose values are hard regset of hard registers available for
   the allocation of given register class whose HARD_REGNO_MODE_OK
   values for given mode are zero.  */
HARD_REG_SET prohibited_class_mode_regs[N_REG_CLASSES][NUM_MACHINE_MODES];

/* Set up PROHIBITED_CLASS_MODE_REGS.  */
static void
setup_prohibited_class_mode_regs (void)
{
  int i, j, k, hard_regno;
  enum reg_class cl;

  for (i = 0; i < ira_reg_class_cover_size; i++)
    {
      cl = ira_reg_class_cover[i];
      for (j = 0; j < NUM_MACHINE_MODES; j++)
	{
	  CLEAR_HARD_REG_SET (prohibited_class_mode_regs[cl][j]);
	  for (k = ira_class_hard_regs_num[cl] - 1; k >= 0; k--)
	    {
	      hard_regno = ira_class_hard_regs[cl][k];
	      if (! HARD_REGNO_MODE_OK (hard_regno, j))
		SET_HARD_REG_BIT (prohibited_class_mode_regs[cl][j],
				  hard_regno);
	    }
	}
    }
}



/* Allocate and initialize IRA_REGISTER_MOVE_COST,
   IRA_MAY_MOVE_IN_COST, and IRA_MAY_MOVE_OUT_COST for MODE if it is
   not done yet.  */
void
ira_init_register_move_cost (enum machine_mode mode)
{
  int cl1, cl2;

  ira_assert (ira_register_move_cost[mode] == NULL
	      && ira_may_move_in_cost[mode] == NULL
	      && ira_may_move_out_cost[mode] == NULL);
  if (move_cost[mode] == NULL)
    init_move_cost (mode);
  ira_register_move_cost[mode] = move_cost[mode];
  /* Don't use ira_allocate because the tables exist out of scope of a
     IRA call.  */
  ira_may_move_in_cost[mode]
    = (move_table *) xmalloc (sizeof (move_table) * N_REG_CLASSES);
  memcpy (ira_may_move_in_cost[mode], may_move_in_cost[mode],
	  sizeof (move_table) * N_REG_CLASSES);
  ira_may_move_out_cost[mode]
    = (move_table *) xmalloc (sizeof (move_table) * N_REG_CLASSES);
  memcpy (ira_may_move_out_cost[mode], may_move_out_cost[mode],
	  sizeof (move_table) * N_REG_CLASSES);
  for (cl1 = 0; cl1 < N_REG_CLASSES; cl1++)
    {
      for (cl2 = 0; cl2 < N_REG_CLASSES; cl2++)
	{
	  if (ira_class_subset_p[cl1][cl2])
	    ira_may_move_in_cost[mode][cl1][cl2] = 0;
	  if (ira_class_subset_p[cl2][cl1])
	    ira_may_move_out_cost[mode][cl1][cl2] = 0;
	}
    }
}



/* This is called once during compiler work.  It sets up
   different arrays whose values don't depend on the compiled
   function.  */
void
ira_init_once (void)
{
  enum machine_mode mode;

  for (mode = 0; mode < MAX_MACHINE_MODE; mode++)
    {
      ira_register_move_cost[mode] = NULL;
      ira_may_move_in_cost[mode] = NULL;
      ira_may_move_out_cost[mode] = NULL;
    }
  ira_init_costs_once ();
}

/* Free ira_register_move_cost, ira_may_move_in_cost, and
   ira_may_move_out_cost for each mode.  */
static void
free_register_move_costs (void)
{
  enum machine_mode mode;

  for (mode = 0; mode < MAX_MACHINE_MODE; mode++)
    {
      if (ira_may_move_in_cost[mode] != NULL)
	free (ira_may_move_in_cost[mode]);
      if (ira_may_move_out_cost[mode] != NULL)
	free (ira_may_move_out_cost[mode]);
      ira_register_move_cost[mode] = NULL;
      ira_may_move_in_cost[mode] = NULL;
      ira_may_move_out_cost[mode] = NULL;
    }
}

/* This is called every time when register related information is
   changed.  */
void
ira_init (void)
{
  free_register_move_costs ();
  setup_reg_mode_hard_regset ();
  setup_alloc_regs (flag_omit_frame_pointer != 0);
  setup_class_subset_and_memory_move_costs ();
  find_reg_class_closure ();
  setup_hard_regno_cover_class ();
  setup_reg_class_nregs ();
  setup_prohibited_class_mode_regs ();
  ira_init_costs ();
}

/* Function called once at the end of compiler work.  */
void
ira_finish_once (void)
{
  ira_finish_costs_once ();
  free_register_move_costs ();
}



/* Array whose values are hard regset of hard registers for which
   move of the hard register in given mode into itself is
   prohibited.  */
HARD_REG_SET ira_prohibited_mode_move_regs[NUM_MACHINE_MODES];

/* Flag of that the above array has been initialized.  */
static bool ira_prohibited_mode_move_regs_initialized_p = false;

/* Set up IRA_PROHIBITED_MODE_MOVE_REGS.  */
static void
setup_prohibited_mode_move_regs (void)
{
  int i, j;
  rtx test_reg1, test_reg2, move_pat, move_insn;

  if (ira_prohibited_mode_move_regs_initialized_p)
    return;
  ira_prohibited_mode_move_regs_initialized_p = true;
  test_reg1 = gen_rtx_REG (VOIDmode, 0);
  test_reg2 = gen_rtx_REG (VOIDmode, 0);
  move_pat = gen_rtx_SET (VOIDmode, test_reg1, test_reg2);
  move_insn = gen_rtx_INSN (VOIDmode, 0, 0, 0, 0, 0, move_pat, -1, 0);
  for (i = 0; i < NUM_MACHINE_MODES; i++)
    {
      SET_HARD_REG_SET (ira_prohibited_mode_move_regs[i]);
      for (j = 0; j < FIRST_PSEUDO_REGISTER; j++)
	{
	  if (! HARD_REGNO_MODE_OK (j, i))
	    continue;
	  SET_REGNO (test_reg1, j);
	  PUT_MODE (test_reg1, i);
	  SET_REGNO (test_reg2, j);
	  PUT_MODE (test_reg2, i);
	  INSN_CODE (move_insn) = -1;
	  recog_memoized (move_insn);
	  if (INSN_CODE (move_insn) < 0)
	    continue;
	  extract_insn (move_insn);
	  if (! constrain_operands (1))
	    continue;
	  CLEAR_HARD_REG_BIT (ira_prohibited_mode_move_regs[i], j);
	}
    }
}



/* Function specific hard registers that can not be used for the
   register allocation.  */
HARD_REG_SET ira_no_alloc_regs;

/* Return TRUE if *LOC contains an asm.  */
static int
insn_contains_asm_1 (rtx *loc, void *data ATTRIBUTE_UNUSED)
{
  if ( !*loc)
    return FALSE;
  if (GET_CODE (*loc) == ASM_OPERANDS)
    return TRUE;
  return FALSE;
}


/* Return TRUE if INSN contains an ASM.  */
static bool
insn_contains_asm (rtx insn)
{
  return for_each_rtx (&insn, insn_contains_asm_1, NULL);
}

/* Set up regs_asm_clobbered.  */
static void
compute_regs_asm_clobbered (char *regs_asm_clobbered)
{
  basic_block bb;

  memset (regs_asm_clobbered, 0, sizeof (char) * FIRST_PSEUDO_REGISTER);
  
  FOR_EACH_BB (bb)
    {
      rtx insn;
      FOR_BB_INSNS_REVERSE (bb, insn)
	{
	  df_ref *def_rec;

	  if (insn_contains_asm (insn))
	    for (def_rec = DF_INSN_DEFS (insn); *def_rec; def_rec++)
	      {
		df_ref def = *def_rec;
		unsigned int dregno = DF_REF_REGNO (def);
		if (dregno < FIRST_PSEUDO_REGISTER)
		  {
		    unsigned int i;
		    enum machine_mode mode = GET_MODE (DF_REF_REAL_REG (def));
		    unsigned int end = dregno 
		      + hard_regno_nregs[dregno][mode] - 1;

		    for (i = dregno; i <= end; ++i)
		      regs_asm_clobbered[i] = 1;
		  }
	      }
	}
    }
}


/* Set up ELIMINABLE_REGSET, IRA_NO_ALLOC_REGS, and REGS_EVER_LIVE.  */
static void
setup_eliminable_regset (void)
{
  /* Like regs_ever_live, but 1 if a reg is set or clobbered from an
     asm.  Unlike regs_ever_live, elements of this array corresponding
     to eliminable regs (like the frame pointer) are set if an asm
     sets them.  */
  char *regs_asm_clobbered
    = (char *) alloca (FIRST_PSEUDO_REGISTER * sizeof (char));
#ifdef ELIMINABLE_REGS
  int i;
  static const struct {const int from, to; } eliminables[] = ELIMINABLE_REGS;
#endif
  /* FIXME: If EXIT_IGNORE_STACK is set, we will not save and restore
     sp for alloca.  So we can't eliminate the frame pointer in that
     case.  At some point, we should improve this by emitting the
     sp-adjusting insns for this case.  */
  int need_fp
    = (! flag_omit_frame_pointer
       || (cfun->calls_alloca && EXIT_IGNORE_STACK)
       || crtl->accesses_prior_frames
       || crtl->stack_realign_needed
       || FRAME_POINTER_REQUIRED);

  frame_pointer_needed = need_fp;

  COPY_HARD_REG_SET (ira_no_alloc_regs, no_unit_alloc_regs);
  CLEAR_HARD_REG_SET (eliminable_regset);

  compute_regs_asm_clobbered (regs_asm_clobbered);
  /* Build the regset of all eliminable registers and show we can't
     use those that we already know won't be eliminated.  */
#ifdef ELIMINABLE_REGS
  for (i = 0; i < (int) ARRAY_SIZE (eliminables); i++)
    {
      bool cannot_elim
	= (! CAN_ELIMINATE (eliminables[i].from, eliminables[i].to)
	   || (eliminables[i].to == STACK_POINTER_REGNUM && need_fp));

      if (! regs_asm_clobbered[eliminables[i].from])
	{
	    SET_HARD_REG_BIT (eliminable_regset, eliminables[i].from);

	    if (cannot_elim)
	      SET_HARD_REG_BIT (ira_no_alloc_regs, eliminables[i].from);
	}
      else if (cannot_elim)
	error ("%s cannot be used in asm here",
	       reg_names[eliminables[i].from]);
      else
	df_set_regs_ever_live (eliminables[i].from, true);
    }
#if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
  if (! regs_asm_clobbered[HARD_FRAME_POINTER_REGNUM])
    {
      SET_HARD_REG_BIT (eliminable_regset, HARD_FRAME_POINTER_REGNUM);
      if (need_fp)
	SET_HARD_REG_BIT (ira_no_alloc_regs, HARD_FRAME_POINTER_REGNUM);
    }
  else if (need_fp)
    error ("%s cannot be used in asm here",
	   reg_names[HARD_FRAME_POINTER_REGNUM]);
  else
    df_set_regs_ever_live (HARD_FRAME_POINTER_REGNUM, true);
#endif

#else
  if (! regs_asm_clobbered[FRAME_POINTER_REGNUM])
    {
      SET_HARD_REG_BIT (eliminable_regset, FRAME_POINTER_REGNUM);
      if (need_fp)
	SET_HARD_REG_BIT (ira_no_alloc_regs, FRAME_POINTER_REGNUM);
    }
  else if (need_fp)
    error ("%s cannot be used in asm here", reg_names[FRAME_POINTER_REGNUM]);
  else
    df_set_regs_ever_live (FRAME_POINTER_REGNUM, true);
#endif
}



/* The length of the following two arrays.  */
int ira_reg_equiv_len;

/* The element value is TRUE if the corresponding regno value is
   invariant.  */
bool *ira_reg_equiv_invariant_p;

/* The element value is equiv constant of given pseudo-register or
   NULL_RTX.  */
rtx *ira_reg_equiv_const;

/* Set up the two arrays declared above.  */
static void
find_reg_equiv_invariant_const (void)
{
  int i;
  bool invariant_p;
  rtx list, insn, note, constant, x;

  for (i = FIRST_PSEUDO_REGISTER; i < reg_equiv_init_size; i++)
    {
      constant = NULL_RTX;
      invariant_p = false;
      for (list = reg_equiv_init[i]; list != NULL_RTX; list = XEXP (list, 1))
	{
	  insn = XEXP (list, 0);
	  note = find_reg_note (insn, REG_EQUIV, NULL_RTX);
	  
	  if (note == NULL_RTX)
	    continue;

	  x = XEXP (note, 0);
	  
	  if (! function_invariant_p (x)
	      || ! flag_pic
	      /* A function invariant is often CONSTANT_P but may
		 include a register.  We promise to only pass CONSTANT_P
		 objects to LEGITIMATE_PIC_OPERAND_P.  */
	      || (CONSTANT_P (x) && LEGITIMATE_PIC_OPERAND_P (x)))
	    {
	      /* It can happen that a REG_EQUIV note contains a MEM
		 that is not a legitimate memory operand.  As later
		 stages of the reload assume that all addresses found
		 in the reg_equiv_* arrays were originally legitimate,
		 we ignore such REG_EQUIV notes.  */
	      if (memory_operand (x, VOIDmode))
		invariant_p = MEM_READONLY_P (x);
	      else if (function_invariant_p (x))
		{
		  if (GET_CODE (x) == PLUS
		      || x == frame_pointer_rtx || x == arg_pointer_rtx)
		    invariant_p = true;
		  else
		    constant = x;
		}
	    }
	}
      ira_reg_equiv_invariant_p[i] = invariant_p;
      ira_reg_equiv_const[i] = constant;
    }
}



/* Set up REG_RENUMBER and CALLER_SAVE_NEEDED (used by reload) from
   the allocation found by IRA.  */
static void
setup_reg_renumber (void)
{
  int regno, hard_regno;
  ira_allocno_t a;
  ira_allocno_iterator ai;

  caller_save_needed = 0;
  FOR_EACH_ALLOCNO (a, ai)
    {
      /* There are no caps at this point.  */
      ira_assert (ALLOCNO_CAP_MEMBER (a) == NULL);
      if (! ALLOCNO_ASSIGNED_P (a))
	/* It can happen if A is not referenced but partially anticipated
	   somewhere in a region.  */
	ALLOCNO_ASSIGNED_P (a) = true;
      ira_free_allocno_updated_costs (a);
      hard_regno = ALLOCNO_HARD_REGNO (a);
      regno = (int) REGNO (ALLOCNO_REG (a));
      reg_renumber[regno] = (hard_regno < 0 ? -1 : hard_regno);
      if (hard_regno >= 0 && ALLOCNO_CALLS_CROSSED_NUM (a) != 0
	  && ! ira_hard_reg_not_in_set_p (hard_regno, ALLOCNO_MODE (a),
					  call_used_reg_set))
	{
	  ira_assert (!optimize || flag_caller_saves
		      || regno >= ira_reg_equiv_len
		      || ira_reg_equiv_const[regno]
		      || ira_reg_equiv_invariant_p[regno]);
	  caller_save_needed = 1;
	}
    }
}

/* Set up allocno assignment flags for further allocation
   improvements.  */
static void
setup_allocno_assignment_flags (void)
{
  int hard_regno;
  ira_allocno_t a;
  ira_allocno_iterator ai;

  FOR_EACH_ALLOCNO (a, ai)
    {
      if (! ALLOCNO_ASSIGNED_P (a))
	/* It can happen if A is not referenced but partially anticipated
	   somewhere in a region.  */
	ira_free_allocno_updated_costs (a);
      hard_regno = ALLOCNO_HARD_REGNO (a);
      /* Don't assign hard registers to allocnos which are destination
	 of removed store at the end of loop.  It has no sense to keep
	 the same value in different hard registers.  It is also
	 impossible to assign hard registers correctly to such
	 allocnos because the cost info and info about intersected
	 calls are incorrect for them.  */
      ALLOCNO_ASSIGNED_P (a) = (hard_regno >= 0
				|| ALLOCNO_MEM_OPTIMIZED_DEST_P (a)
				|| (ALLOCNO_MEMORY_COST (a)
				    - ALLOCNO_COVER_CLASS_COST (a)) < 0);
      ira_assert (hard_regno < 0
		  || ! ira_hard_reg_not_in_set_p (hard_regno, ALLOCNO_MODE (a),
						  reg_class_contents
						  [ALLOCNO_COVER_CLASS (a)]));
    }
}

/* Evaluate overall allocation cost and the costs for using hard
   registers and memory for allocnos.  */
static void
calculate_allocation_cost (void)
{
  int hard_regno, cost;
  ira_allocno_t a;
  ira_allocno_iterator ai;

  ira_overall_cost = ira_reg_cost = ira_mem_cost = 0;
  FOR_EACH_ALLOCNO (a, ai)
    {
      hard_regno = ALLOCNO_HARD_REGNO (a);
      ira_assert (hard_regno < 0
		  || ! ira_hard_reg_not_in_set_p
		       (hard_regno, ALLOCNO_MODE (a),
			reg_class_contents[ALLOCNO_COVER_CLASS (a)])); 
      if (hard_regno < 0)
	{
	  cost = ALLOCNO_MEMORY_COST (a);
	  ira_mem_cost += cost;
	}
      else if (ALLOCNO_HARD_REG_COSTS (a) != NULL)
	{
	  cost = (ALLOCNO_HARD_REG_COSTS (a)
		  [ira_class_hard_reg_index
		   [ALLOCNO_COVER_CLASS (a)][hard_regno]]);
	  ira_reg_cost += cost;
	}
      else
	{
	  cost = ALLOCNO_COVER_CLASS_COST (a);
	  ira_reg_cost += cost;
	}
      ira_overall_cost += cost;
    }

  if (internal_flag_ira_verbose > 0 && ira_dump_file != NULL)
    {
      fprintf (ira_dump_file,
	       "+++Costs: overall %d, reg %d, mem %d, ld %d, st %d, move %d\n",
	       ira_overall_cost, ira_reg_cost, ira_mem_cost,
	       ira_load_cost, ira_store_cost, ira_shuffle_cost);
      fprintf (ira_dump_file, "+++       move loops %d, new jumps %d\n",
	       ira_move_loops_num, ira_additional_jumps_num);
    }

}

#ifdef ENABLE_IRA_CHECKING
/* Check the correctness of the allocation.  We do need this because
   of complicated code to transform more one region internal
   representation into one region representation.  */
static void
check_allocation (void)
{
  ira_allocno_t a, conflict_a;
  int hard_regno, conflict_hard_regno, nregs, conflict_nregs;
  ira_allocno_conflict_iterator aci;
  ira_allocno_iterator ai;

  FOR_EACH_ALLOCNO (a, ai)
    {
      if (ALLOCNO_CAP_MEMBER (a) != NULL
	  || (hard_regno = ALLOCNO_HARD_REGNO (a)) < 0)
	continue;
      nregs = hard_regno_nregs[hard_regno][ALLOCNO_MODE (a)];
      FOR_EACH_ALLOCNO_CONFLICT (a, conflict_a, aci)
	if ((conflict_hard_regno = ALLOCNO_HARD_REGNO (conflict_a)) >= 0)
	  {
	    conflict_nregs
	      = (hard_regno_nregs
		 [conflict_hard_regno][ALLOCNO_MODE (conflict_a)]);
	    if ((conflict_hard_regno <= hard_regno
		 && hard_regno < conflict_hard_regno + conflict_nregs)
		|| (hard_regno <= conflict_hard_regno
		    && conflict_hard_regno < hard_regno + nregs))
	      {
		fprintf (stderr, "bad allocation for %d and %d\n",
			 ALLOCNO_REGNO (a), ALLOCNO_REGNO (conflict_a));
		gcc_unreachable ();
	      }
	  }
    }
}
#endif

/* Fix values of array REG_EQUIV_INIT after live range splitting done
   by IRA.  */
static void
fix_reg_equiv_init (void)
{
  int max_regno = max_reg_num ();
  int i, new_regno;
  rtx x, prev, next, insn, set;
  
  if (reg_equiv_init_size < max_regno)
    {
      reg_equiv_init
	= (rtx *) ggc_realloc (reg_equiv_init, max_regno * sizeof (rtx));
      while (reg_equiv_init_size < max_regno)
	reg_equiv_init[reg_equiv_init_size++] = NULL_RTX;
      for (i = FIRST_PSEUDO_REGISTER; i < reg_equiv_init_size; i++)
	for (prev = NULL_RTX, x = reg_equiv_init[i]; x != NULL_RTX; x = next)
	  {
	    next = XEXP (x, 1);
	    insn = XEXP (x, 0);
	    set = single_set (insn);
	    ira_assert (set != NULL_RTX
			&& (REG_P (SET_DEST (set)) || REG_P (SET_SRC (set))));
	    if (REG_P (SET_DEST (set))
		&& ((int) REGNO (SET_DEST (set)) == i
		    || (int) ORIGINAL_REGNO (SET_DEST (set)) == i))
	      new_regno = REGNO (SET_DEST (set));
	    else if (REG_P (SET_SRC (set))
		     && ((int) REGNO (SET_SRC (set)) == i
			 || (int) ORIGINAL_REGNO (SET_SRC (set)) == i))
	      new_regno = REGNO (SET_SRC (set));
	    else
 	      gcc_unreachable ();
	    if (new_regno == i)
	      prev = x;
	    else
	      {
		if (prev == NULL_RTX)
		  reg_equiv_init[i] = next;
		else
		  XEXP (prev, 1) = next;
		XEXP (x, 1) = reg_equiv_init[new_regno];
		reg_equiv_init[new_regno] = x;
	      }
	  }
    }
}

#ifdef ENABLE_IRA_CHECKING
/* Print redundant memory-memory copies.  */
static void
print_redundant_copies (void)
{
  int hard_regno;
  ira_allocno_t a;
  ira_copy_t cp, next_cp;
  ira_allocno_iterator ai;
  
  FOR_EACH_ALLOCNO (a, ai)
    {
      if (ALLOCNO_CAP_MEMBER (a) != NULL)
	/* It is a cap. */
	continue;
      hard_regno = ALLOCNO_HARD_REGNO (a);
      if (hard_regno >= 0)
	continue;
      for (cp = ALLOCNO_COPIES (a); cp != NULL; cp = next_cp)
	if (cp->first == a)
	  next_cp = cp->next_first_allocno_copy;
	else
	  {
	    next_cp = cp->next_second_allocno_copy;
	    if (internal_flag_ira_verbose > 4 && ira_dump_file != NULL
		&& cp->insn != NULL_RTX
		&& ALLOCNO_HARD_REGNO (cp->first) == hard_regno)
	      fprintf (ira_dump_file,
		       "        Redundant move from %d(freq %d):%d\n",
		       INSN_UID (cp->insn), cp->freq, hard_regno);
	  }
    }
}
#endif

/* Setup preferred and alternative classes for new pseudo-registers
   created by IRA starting with START.  */
static void
setup_preferred_alternate_classes_for_new_pseudos (int start)
{
  int i, old_regno;
  int max_regno = max_reg_num ();

  for (i = start; i < max_regno; i++)
    {
      old_regno = ORIGINAL_REGNO (regno_reg_rtx[i]);
      ira_assert (i != old_regno); 
      setup_reg_classes (i, reg_preferred_class (old_regno),
			 reg_alternate_class (old_regno));
      if (internal_flag_ira_verbose > 2 && ira_dump_file != NULL)
	fprintf (ira_dump_file,
		 "    New r%d: setting preferred %s, alternative %s\n",
		 i, reg_class_names[reg_preferred_class (old_regno)],
		 reg_class_names[reg_alternate_class (old_regno)]);
    }
}



/* Regional allocation can create new pseudo-registers.  This function
   expands some arrays for pseudo-registers.  */
static void
expand_reg_info (int old_size)
{
  int i;
  int size = max_reg_num ();

  resize_reg_info ();
  for (i = old_size; i < size; i++)
    {
      reg_renumber[i] = -1;
      setup_reg_classes (i, GENERAL_REGS, ALL_REGS);
    }
}

/* Return TRUE if there is too high register pressure in the function.
   It is used to decide when stack slot sharing is worth to do.  */
static bool
too_high_register_pressure_p (void)
{
  int i;
  enum reg_class cover_class;
  
  for (i = 0; i < ira_reg_class_cover_size; i++)
    {
      cover_class = ira_reg_class_cover[i];
      if (ira_loop_tree_root->reg_pressure[cover_class] > 10000)
	return true;
    }
  return false;
}



/* All natural loops.  */
struct loops ira_loops;

/* This is the main entry of IRA.  */
static void
ira (FILE *f)
{
  int overall_cost_before, allocated_reg_info_size;
  bool loops_p;
  int max_regno_before_ira, ira_max_point_before_emit;
  int rebuild_p;
  int saved_flag_ira_algorithm;
  int saved_flag_ira_share_spill_slots;
  basic_block bb;

  timevar_push (TV_IRA);

  if (flag_ira_verbose < 10)
    {
      internal_flag_ira_verbose = flag_ira_verbose;
      ira_dump_file = f;
    }
  else
    {
      internal_flag_ira_verbose = flag_ira_verbose - 10;
      ira_dump_file = stderr;
    }

  setup_prohibited_mode_move_regs ();

  df_note_add_problem ();

  if (optimize == 1)
    {
      df_live_add_problem ();
      df_live_set_all_dirty ();
    }
#ifdef ENABLE_CHECKING
  df->changeable_flags |= DF_VERIFY_SCHEDULED;
#endif
  df_analyze ();
  df_clear_flags (DF_NO_INSN_RESCAN);
  regstat_init_n_sets_and_refs ();
  regstat_compute_ri ();

  /* If we are not optimizing, then this is the only place before
     register allocation where dataflow is done.  And that is needed
     to generate these warnings.  */
  if (warn_clobbered)
    generate_setjmp_warnings ();

  rebuild_p = update_equiv_regs ();

#ifndef IRA_NO_OBSTACK
  gcc_obstack_init (&ira_obstack);
#endif
  bitmap_obstack_initialize (&ira_bitmap_obstack);
  if (optimize)
    {      
      max_regno = max_reg_num ();
      ira_reg_equiv_len = max_regno;
      ira_reg_equiv_invariant_p
	= (bool *) ira_allocate (max_regno * sizeof (bool));
      memset (ira_reg_equiv_invariant_p, 0, max_regno * sizeof (bool));
      ira_reg_equiv_const = (rtx *) ira_allocate (max_regno * sizeof (rtx));
      memset (ira_reg_equiv_const, 0, max_regno * sizeof (rtx));
      find_reg_equiv_invariant_const ();
      if (rebuild_p)
	{
	  timevar_push (TV_JUMP);
	  rebuild_jump_labels (get_insns ());
	  purge_all_dead_edges ();
	  timevar_pop (TV_JUMP);
	}
    }

  max_regno_before_ira = allocated_reg_info_size = max_reg_num ();
  allocate_reg_info ();
  setup_eliminable_regset ();
      
  ira_overall_cost = ira_reg_cost = ira_mem_cost = 0;
  ira_load_cost = ira_store_cost = ira_shuffle_cost = 0;
  ira_move_loops_num = ira_additional_jumps_num = 0;
  
  ira_assert (current_loops == NULL);
  flow_loops_find (&ira_loops);
  current_loops = &ira_loops;
  saved_flag_ira_algorithm = flag_ira_algorithm;
  if (optimize && number_of_loops () > (unsigned) IRA_MAX_LOOPS_NUM)
    flag_ira_algorithm = IRA_ALGORITHM_CB;
      
  if (internal_flag_ira_verbose > 0 && ira_dump_file != NULL)
    fprintf (ira_dump_file, "Building IRA IR\n");
  loops_p = ira_build (optimize
		       && (flag_ira_algorithm == IRA_ALGORITHM_REGIONAL
			   || flag_ira_algorithm == IRA_ALGORITHM_MIXED));

  saved_flag_ira_share_spill_slots = flag_ira_share_spill_slots;
  if (too_high_register_pressure_p ())
    /* It is just wasting compiler's time to pack spilled pseudos into
       stack slots in this case -- prohibit it.  */ 
    flag_ira_share_spill_slots = FALSE;

  ira_color ();
      
  ira_max_point_before_emit = ira_max_point;
      
  ira_emit (loops_p);
  
  if (optimize)
    {
      max_regno = max_reg_num ();
      
      if (! loops_p)
	ira_initiate_assign ();
      else
	{
	  expand_reg_info (allocated_reg_info_size);
	  setup_preferred_alternate_classes_for_new_pseudos
	    (allocated_reg_info_size);
	  allocated_reg_info_size = max_regno;
	  
	  if (internal_flag_ira_verbose > 0 && ira_dump_file != NULL)
	    fprintf (ira_dump_file, "Flattening IR\n");
	  ira_flattening (max_regno_before_ira, ira_max_point_before_emit);
	  /* New insns were generated: add notes and recalculate live
	     info.  */
	  df_analyze ();
	  
	  flow_loops_find (&ira_loops);
	  current_loops = &ira_loops;

	  setup_allocno_assignment_flags ();
	  ira_initiate_assign ();
	  ira_reassign_conflict_allocnos (max_regno);
	}
    }

  setup_reg_renumber ();
  
  calculate_allocation_cost ();
  
#ifdef ENABLE_IRA_CHECKING
  if (optimize)
    check_allocation ();
#endif
      
  delete_trivially_dead_insns (get_insns (), max_reg_num ());
  max_regno = max_reg_num ();
  
  /* Determine if the current function is a leaf before running IRA
     since this can impact optimizations done by the prologue and
     epilogue thus changing register elimination offsets.  */
  current_function_is_leaf = leaf_function_p ();
  
  /* And the reg_equiv_memory_loc array.  */
  VEC_safe_grow (rtx, gc, reg_equiv_memory_loc_vec, max_regno);
  memset (VEC_address (rtx, reg_equiv_memory_loc_vec), 0,
	  sizeof (rtx) * max_regno);
  reg_equiv_memory_loc = VEC_address (rtx, reg_equiv_memory_loc_vec);

  if (max_regno != max_regno_before_ira)
    {
      regstat_free_n_sets_and_refs ();
      regstat_free_ri ();
      regstat_init_n_sets_and_refs ();
      regstat_compute_ri ();
    }

  allocate_initial_values (reg_equiv_memory_loc);

  overall_cost_before = ira_overall_cost;
  if (optimize)
    {
      fix_reg_equiv_init ();
      
#ifdef ENABLE_IRA_CHECKING
      print_redundant_copies ();
#endif

      ira_spilled_reg_stack_slots_num = 0;
      ira_spilled_reg_stack_slots
	= ((struct ira_spilled_reg_stack_slot *)
	   ira_allocate (max_regno
			 * sizeof (struct ira_spilled_reg_stack_slot)));
      memset (ira_spilled_reg_stack_slots, 0,
	      max_regno * sizeof (struct ira_spilled_reg_stack_slot));
    }
  
  timevar_pop (TV_IRA);

  timevar_push (TV_RELOAD);
  df_set_flags (DF_NO_INSN_RESCAN);
  build_insn_chain ();

  reload_completed = !reload (get_insns (), optimize > 0);

  timevar_pop (TV_RELOAD);

  timevar_push (TV_IRA);

  if (optimize)
    {
      ira_free (ira_spilled_reg_stack_slots);
      
      ira_finish_assign ();
      
    }  
  if (internal_flag_ira_verbose > 0 && ira_dump_file != NULL
      && overall_cost_before != ira_overall_cost)
    fprintf (ira_dump_file, "+++Overall after reload %d\n", ira_overall_cost);
  ira_destroy ();
  
  flag_ira_share_spill_slots = saved_flag_ira_share_spill_slots;

  flow_loops_free (&ira_loops);
  free_dominance_info (CDI_DOMINATORS);
  FOR_ALL_BB (bb)
    bb->loop_father = NULL;
  current_loops = NULL;

  flag_ira_algorithm = saved_flag_ira_algorithm;

  regstat_free_ri ();
  regstat_free_n_sets_and_refs ();
      
  if (optimize)
    {
      cleanup_cfg (CLEANUP_EXPENSIVE);
      
      ira_free (ira_reg_equiv_invariant_p);
      ira_free (ira_reg_equiv_const);
    }

  bitmap_obstack_release (&ira_bitmap_obstack);
#ifndef IRA_NO_OBSTACK
  obstack_free (&ira_obstack, NULL);
#endif

  /* The code after the reload has changed so much that at this point
     we might as well just rescan everything.  Not that
     df_rescan_all_insns is not going to help here because it does not
     touch the artificial uses and defs.  */
  df_finish_pass (true);
  if (optimize > 1)
    df_live_add_problem ();
  df_scan_alloc (NULL);
  df_scan_blocks ();

  if (optimize)
    df_analyze ();

  timevar_pop (TV_IRA);
}



static bool
gate_ira (void)
{
  return flag_ira != 0;
}

/* Run the integrated register allocator.  */
static unsigned int
rest_of_handle_ira (void)
{
  ira (dump_file);
  return 0;
}

struct rtl_opt_pass pass_ira =
{
 {
  RTL_PASS,
  "ira",                                /* name */
  gate_ira,                             /* gate */
  rest_of_handle_ira,		        /* execute */
  NULL,                                 /* sub */
  NULL,                                 /* next */
  0,                                    /* static_pass_number */
  0,		                        /* tv_id */
  0,                                    /* properties_required */
  0,                                    /* properties_provided */
  0,                                    /* properties_destroyed */
  0,                                    /* todo_flags_start */
  TODO_dump_func |
  TODO_ggc_collect                      /* todo_flags_finish */
 }
};