gcc/

[pf3gnuchains/gcc-fork.git] / gcc / reload1.c

/* Reload pseudo regs into hard regs for insns that require hard regs.
   Copyright (C) 1987, 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
   1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
   Free Software Foundation, Inc.

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 3, or (at your option) any later
version.

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

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

#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"

#include "machmode.h"
#include "hard-reg-set.h"
#include "rtl-error.h"
#include "tm_p.h"
#include "obstack.h"
#include "insn-config.h"
#include "flags.h"
#include "function.h"
#include "expr.h"
#include "optabs.h"
#include "regs.h"
#include "addresses.h"
#include "basic-block.h"
#include "df.h"
#include "reload.h"
#include "recog.h"
#include "output.h"
#include "except.h"
#include "tree.h"
#include "ira.h"
#include "target.h"
#include "emit-rtl.h"

/* This file contains the reload pass of the compiler, which is
   run after register allocation has been done.  It checks that
   each insn is valid (operands required to be in registers really
   are in registers of the proper class) and fixes up invalid ones
   by copying values temporarily into registers for the insns
   that need them.

   The results of register allocation are described by the vector
   reg_renumber; the insns still contain pseudo regs, but reg_renumber
   can be used to find which hard reg, if any, a pseudo reg is in.

   The technique we always use is to free up a few hard regs that are
   called ``reload regs'', and for each place where a pseudo reg
   must be in a hard reg, copy it temporarily into one of the reload regs.

   Reload regs are allocated locally for every instruction that needs
   reloads.  When there are pseudos which are allocated to a register that
   has been chosen as a reload reg, such pseudos must be ``spilled''.
   This means that they go to other hard regs, or to stack slots if no other
   available hard regs can be found.  Spilling can invalidate more
   insns, requiring additional need for reloads, so we must keep checking
   until the process stabilizes.

   For machines with different classes of registers, we must keep track
   of the register class needed for each reload, and make sure that
   we allocate enough reload registers of each class.

   The file reload.c contains the code that checks one insn for
   validity and reports the reloads that it needs.  This file
   is in charge of scanning the entire rtl code, accumulating the
   reload needs, spilling, assigning reload registers to use for
   fixing up each insn, and generating the new insns to copy values
   into the reload registers.  */
\f
struct target_reload default_target_reload;
#if SWITCHABLE_TARGET
struct target_reload *this_target_reload = &default_target_reload;
#endif

#define spill_indirect_levels                   \
  (this_target_reload->x_spill_indirect_levels)

/* During reload_as_needed, element N contains a REG rtx for the hard reg
   into which reg N has been reloaded (perhaps for a previous insn).  */
static rtx *reg_last_reload_reg;

/* Elt N nonzero if reg_last_reload_reg[N] has been set in this insn
   for an output reload that stores into reg N.  */
static regset_head reg_has_output_reload;

/* Indicates which hard regs are reload-registers for an output reload
   in the current insn.  */
static HARD_REG_SET reg_is_output_reload;

/* Element N is the constant value to which pseudo reg N is equivalent,
   or zero if pseudo reg N is not equivalent to a constant.
   find_reloads looks at this in order to replace pseudo reg N
   with the constant it stands for.  */
rtx *reg_equiv_constant;

/* Element N is an invariant value to which pseudo reg N is equivalent.
   eliminate_regs_in_insn uses this to replace pseudos in particular
   contexts.  */
rtx *reg_equiv_invariant;

/* Element N is a memory location to which pseudo reg N is equivalent,
   prior to any register elimination (such as frame pointer to stack
   pointer).  Depending on whether or not it is a valid address, this value
   is transferred to either reg_equiv_address or reg_equiv_mem.  */
rtx *reg_equiv_memory_loc;

/* We allocate reg_equiv_memory_loc inside a varray so that the garbage
   collector can keep track of what is inside.  */
VEC(rtx,gc) *reg_equiv_memory_loc_vec;

/* Element N is the address of stack slot to which pseudo reg N is equivalent.
   This is used when the address is not valid as a memory address
   (because its displacement is too big for the machine.)  */
rtx *reg_equiv_address;

/* Element N is the memory slot to which pseudo reg N is equivalent,
   or zero if pseudo reg N is not equivalent to a memory slot.  */
rtx *reg_equiv_mem;

/* Element N is an EXPR_LIST of REG_EQUIVs containing MEMs with
   alternate representations of the location of pseudo reg N.  */
rtx *reg_equiv_alt_mem_list;

/* Widest width in which each pseudo reg is referred to (via subreg).  */
static unsigned int *reg_max_ref_width;

/* Element N is the list of insns that initialized reg N from its equivalent
   constant or memory slot.  */
rtx *reg_equiv_init;
int reg_equiv_init_size;

/* Vector to remember old contents of reg_renumber before spilling.  */
static short *reg_old_renumber;

/* During reload_as_needed, element N contains the last pseudo regno reloaded
   into hard register N.  If that pseudo reg occupied more than one register,
   reg_reloaded_contents points to that pseudo for each spill register in
   use; all of these must remain set for an inheritance to occur.  */
static int reg_reloaded_contents[FIRST_PSEUDO_REGISTER];

/* During reload_as_needed, element N contains the insn for which
   hard register N was last used.   Its contents are significant only
   when reg_reloaded_valid is set for this register.  */
static rtx reg_reloaded_insn[FIRST_PSEUDO_REGISTER];

/* Indicate if reg_reloaded_insn / reg_reloaded_contents is valid.  */
static HARD_REG_SET reg_reloaded_valid;
/* Indicate if the register was dead at the end of the reload.
   This is only valid if reg_reloaded_contents is set and valid.  */
static HARD_REG_SET reg_reloaded_dead;

/* Indicate whether the register's current value is one that is not
   safe to retain across a call, even for registers that are normally
   call-saved.  This is only meaningful for members of reg_reloaded_valid.  */
static HARD_REG_SET reg_reloaded_call_part_clobbered;

/* Number of spill-regs so far; number of valid elements of spill_regs.  */
static int n_spills;

/* In parallel with spill_regs, contains REG rtx's for those regs.
   Holds the last rtx used for any given reg, or 0 if it has never
   been used for spilling yet.  This rtx is reused, provided it has
   the proper mode.  */
static rtx spill_reg_rtx[FIRST_PSEUDO_REGISTER];

/* In parallel with spill_regs, contains nonzero for a spill reg
   that was stored after the last time it was used.
   The precise value is the insn generated to do the store.  */
static rtx spill_reg_store[FIRST_PSEUDO_REGISTER];

/* This is the register that was stored with spill_reg_store.  This is a
   copy of reload_out / reload_out_reg when the value was stored; if
   reload_out is a MEM, spill_reg_stored_to will be set to reload_out_reg.  */
static rtx spill_reg_stored_to[FIRST_PSEUDO_REGISTER];

/* This table is the inverse mapping of spill_regs:
   indexed by hard reg number,
   it contains the position of that reg in spill_regs,
   or -1 for something that is not in spill_regs.

   ?!?  This is no longer accurate.  */
static short spill_reg_order[FIRST_PSEUDO_REGISTER];

/* This reg set indicates registers that can't be used as spill registers for
   the currently processed insn.  These are the hard registers which are live
   during the insn, but not allocated to pseudos, as well as fixed
   registers.  */
static HARD_REG_SET bad_spill_regs;

/* These are the hard registers that can't be used as spill register for any
   insn.  This includes registers used for user variables and registers that
   we can't eliminate.  A register that appears in this set also can't be used
   to retry register allocation.  */
static HARD_REG_SET bad_spill_regs_global;

/* Describes order of use of registers for reloading
   of spilled pseudo-registers.  `n_spills' is the number of
   elements that are actually valid; new ones are added at the end.

   Both spill_regs and spill_reg_order are used on two occasions:
   once during find_reload_regs, where they keep track of the spill registers
   for a single insn, but also during reload_as_needed where they show all
   the registers ever used by reload.  For the latter case, the information
   is calculated during finish_spills.  */
static short spill_regs[FIRST_PSEUDO_REGISTER];

/* This vector of reg sets indicates, for each pseudo, which hard registers
   may not be used for retrying global allocation because the register was
   formerly spilled from one of them.  If we allowed reallocating a pseudo to
   a register that it was already allocated to, reload might not
   terminate.  */
static HARD_REG_SET *pseudo_previous_regs;

/* This vector of reg sets indicates, for each pseudo, which hard
   registers may not be used for retrying global allocation because they
   are used as spill registers during one of the insns in which the
   pseudo is live.  */
static HARD_REG_SET *pseudo_forbidden_regs;

/* All hard regs that have been used as spill registers for any insn are
   marked in this set.  */
static HARD_REG_SET used_spill_regs;

/* Index of last register assigned as a spill register.  We allocate in
   a round-robin fashion.  */
static int last_spill_reg;

/* Record the stack slot for each spilled hard register.  */
static rtx spill_stack_slot[FIRST_PSEUDO_REGISTER];

/* Width allocated so far for that stack slot.  */
static unsigned int spill_stack_slot_width[FIRST_PSEUDO_REGISTER];

/* Record which pseudos needed to be spilled.  */
static regset_head spilled_pseudos;

/* Record which pseudos changed their allocation in finish_spills.  */
static regset_head changed_allocation_pseudos;

/* Used for communication between order_regs_for_reload and count_pseudo.
   Used to avoid counting one pseudo twice.  */
static regset_head pseudos_counted;

/* First uid used by insns created by reload in this function.
   Used in find_equiv_reg.  */
int reload_first_uid;

/* Flag set by local-alloc or global-alloc if anything is live in
   a call-clobbered reg across calls.  */
int caller_save_needed;

/* Set to 1 while reload_as_needed is operating.
   Required by some machines to handle any generated moves differently.  */
int reload_in_progress = 0;

/* This obstack is used for allocation of rtl during register elimination.
   The allocated storage can be freed once find_reloads has processed the
   insn.  */
static struct obstack reload_obstack;

/* Points to the beginning of the reload_obstack.  All insn_chain structures
   are allocated first.  */
static char *reload_startobj;

/* The point after all insn_chain structures.  Used to quickly deallocate
   memory allocated in copy_reloads during calculate_needs_all_insns.  */
static char *reload_firstobj;

/* This points before all local rtl generated by register elimination.
   Used to quickly free all memory after processing one insn.  */
static char *reload_insn_firstobj;

/* List of insn_chain instructions, one for every insn that reload needs to
   examine.  */
struct insn_chain *reload_insn_chain;

/* List of all insns needing reloads.  */
static struct insn_chain *insns_need_reload;
\f
/* This structure is used to record information about register eliminations.
   Each array entry describes one possible way of eliminating a register
   in favor of another.   If there is more than one way of eliminating a
   particular register, the most preferred should be specified first.  */

struct elim_table
{
  int from;                     /* Register number to be eliminated.  */
  int to;                       /* Register number used as replacement.  */
  HOST_WIDE_INT initial_offset; /* Initial difference between values.  */
  int can_eliminate;            /* Nonzero if this elimination can be done.  */
  int can_eliminate_previous;   /* Value returned by TARGET_CAN_ELIMINATE
                                   target hook in previous scan over insns
                                   made by reload.  */
  HOST_WIDE_INT offset;         /* Current offset between the two regs.  */
  HOST_WIDE_INT previous_offset;/* Offset at end of previous insn.  */
  int ref_outside_mem;          /* "to" has been referenced outside a MEM.  */
  rtx from_rtx;                 /* REG rtx for the register to be eliminated.
                                   We cannot simply compare the number since
                                   we might then spuriously replace a hard
                                   register corresponding to a pseudo
                                   assigned to the reg to be eliminated.  */
  rtx to_rtx;                   /* REG rtx for the replacement.  */
};

static struct elim_table *reg_eliminate = 0;

/* This is an intermediate structure to initialize the table.  It has
   exactly the members provided by ELIMINABLE_REGS.  */
static const struct elim_table_1
{
  const int from;
  const int to;
} reg_eliminate_1[] =

/* If a set of eliminable registers was specified, define the table from it.
   Otherwise, default to the normal case of the frame pointer being
   replaced by the stack pointer.  */

#ifdef ELIMINABLE_REGS
  ELIMINABLE_REGS;
#else
  {{ FRAME_POINTER_REGNUM, STACK_POINTER_REGNUM}};
#endif

#define NUM_ELIMINABLE_REGS ARRAY_SIZE (reg_eliminate_1)

/* Record the number of pending eliminations that have an offset not equal
   to their initial offset.  If nonzero, we use a new copy of each
   replacement result in any insns encountered.  */
int num_not_at_initial_offset;

/* Count the number of registers that we may be able to eliminate.  */
static int num_eliminable;
/* And the number of registers that are equivalent to a constant that
   can be eliminated to frame_pointer / arg_pointer + constant.  */
static int num_eliminable_invariants;

/* For each label, we record the offset of each elimination.  If we reach
   a label by more than one path and an offset differs, we cannot do the
   elimination.  This information is indexed by the difference of the
   number of the label and the first label number.  We can't offset the
   pointer itself as this can cause problems on machines with segmented
   memory.  The first table is an array of flags that records whether we
   have yet encountered a label and the second table is an array of arrays,
   one entry in the latter array for each elimination.  */

static int first_label_num;
static char *offsets_known_at;
static HOST_WIDE_INT (*offsets_at)[NUM_ELIMINABLE_REGS];

/* Stack of addresses where an rtx has been changed.  We can undo the 
   changes by popping items off the stack and restoring the original
   value at each location. 

   We use this simplistic undo capability rather than copy_rtx as copy_rtx
   will not make a deep copy of a normally sharable rtx, such as
   (const (plus (symbol_ref) (const_int))).  If such an expression appears
   as R1 in gen_reload_chain_without_interm_reg_p, then a shared
   rtx expression would be changed.  See PR 42431.  */

typedef rtx *rtx_p;
DEF_VEC_P(rtx_p);
DEF_VEC_ALLOC_P(rtx_p,heap);
static VEC(rtx_p,heap) *substitute_stack;

/* Number of labels in the current function.  */

static int num_labels;
\f
static void replace_pseudos_in (rtx *, enum machine_mode, rtx);
static void maybe_fix_stack_asms (void);
static void copy_reloads (struct insn_chain *);
static void calculate_needs_all_insns (int);
static int find_reg (struct insn_chain *, int);
static void find_reload_regs (struct insn_chain *);
static void select_reload_regs (void);
static void delete_caller_save_insns (void);

static void spill_failure (rtx, enum reg_class);
static void count_spilled_pseudo (int, int, int);
static void delete_dead_insn (rtx);
static void alter_reg (int, int, bool);
static void set_label_offsets (rtx, rtx, int);
static void check_eliminable_occurrences (rtx);
static void elimination_effects (rtx, enum machine_mode);
static rtx eliminate_regs_1 (rtx, enum machine_mode, rtx, bool, bool);
static int eliminate_regs_in_insn (rtx, int);
static void update_eliminable_offsets (void);
static void mark_not_eliminable (rtx, const_rtx, void *);
static void set_initial_elim_offsets (void);
static bool verify_initial_elim_offsets (void);
static void set_initial_label_offsets (void);
static void set_offsets_for_label (rtx);
static void init_eliminable_invariants (rtx, bool);
static void init_elim_table (void);
static void free_reg_equiv (void);
static void update_eliminables (HARD_REG_SET *);
static void elimination_costs_in_insn (rtx);
static void spill_hard_reg (unsigned int, int);
static int finish_spills (int);
static void scan_paradoxical_subregs (rtx);
static void count_pseudo (int);
static void order_regs_for_reload (struct insn_chain *);
static void reload_as_needed (int);
static void forget_old_reloads_1 (rtx, const_rtx, void *);
static void forget_marked_reloads (regset);
static int reload_reg_class_lower (const void *, const void *);
static void mark_reload_reg_in_use (unsigned int, int, enum reload_type,
                                    enum machine_mode);
static void clear_reload_reg_in_use (unsigned int, int, enum reload_type,
                                     enum machine_mode);
static int reload_reg_free_p (unsigned int, int, enum reload_type);
static int reload_reg_free_for_value_p (int, int, int, enum reload_type,
                                        rtx, rtx, int, int);
static int free_for_value_p (int, enum machine_mode, int, enum reload_type,
                             rtx, rtx, int, int);
static int reload_reg_reaches_end_p (unsigned int, int, enum reload_type);
static int allocate_reload_reg (struct insn_chain *, int, int);
static int conflicts_with_override (rtx);
static void failed_reload (rtx, int);
static int set_reload_reg (int, int);
static void choose_reload_regs_init (struct insn_chain *, rtx *);
static void choose_reload_regs (struct insn_chain *);
static void emit_input_reload_insns (struct insn_chain *, struct reload *,
                                     rtx, int);
static void emit_output_reload_insns (struct insn_chain *, struct reload *,
                                      int);
static void do_input_reload (struct insn_chain *, struct reload *, int);
static void do_output_reload (struct insn_chain *, struct reload *, int);
static void emit_reload_insns (struct insn_chain *);
static void delete_output_reload (rtx, int, int, rtx);
static void delete_address_reloads (rtx, rtx);
static void delete_address_reloads_1 (rtx, rtx, rtx);
static rtx inc_for_reload (rtx, rtx, rtx, int);
#ifdef AUTO_INC_DEC
static void add_auto_inc_notes (rtx, rtx);
#endif
static void substitute (rtx *, const_rtx, rtx);
static bool gen_reload_chain_without_interm_reg_p (int, int);
static int reloads_conflict (int, int);
static rtx gen_reload (rtx, rtx, int, enum reload_type);
static rtx emit_insn_if_valid_for_reload (rtx);
\f
/* Initialize the reload pass.  This is called at the beginning of compilation
   and may be called again if the target is reinitialized.  */

void
init_reload (void)
{
  int i;

  /* Often (MEM (REG n)) is still valid even if (REG n) is put on the stack.
     Set spill_indirect_levels to the number of levels such addressing is
     permitted, zero if it is not permitted at all.  */

  rtx tem
    = gen_rtx_MEM (Pmode,
                   gen_rtx_PLUS (Pmode,
                                 gen_rtx_REG (Pmode,
                                              LAST_VIRTUAL_REGISTER + 1),
                                 GEN_INT (4)));
  spill_indirect_levels = 0;

  while (memory_address_p (QImode, tem))
    {
      spill_indirect_levels++;
      tem = gen_rtx_MEM (Pmode, tem);
    }

  /* See if indirect addressing is valid for (MEM (SYMBOL_REF ...)).  */

  tem = gen_rtx_MEM (Pmode, gen_rtx_SYMBOL_REF (Pmode, "foo"));
  indirect_symref_ok = memory_address_p (QImode, tem);

  /* See if reg+reg is a valid (and offsettable) address.  */

  for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
    {
      tem = gen_rtx_PLUS (Pmode,
                          gen_rtx_REG (Pmode, HARD_FRAME_POINTER_REGNUM),
                          gen_rtx_REG (Pmode, i));

      /* This way, we make sure that reg+reg is an offsettable address.  */
      tem = plus_constant (tem, 4);

      if (memory_address_p (QImode, tem))
        {
          double_reg_address_ok = 1;
          break;
        }
    }

  /* Initialize obstack for our rtl allocation.  */
  gcc_obstack_init (&reload_obstack);
  reload_startobj = XOBNEWVAR (&reload_obstack, char, 0);

  INIT_REG_SET (&spilled_pseudos);
  INIT_REG_SET (&changed_allocation_pseudos);
  INIT_REG_SET (&pseudos_counted);
}

/* List of insn chains that are currently unused.  */
static struct insn_chain *unused_insn_chains = 0;

/* Allocate an empty insn_chain structure.  */
struct insn_chain *
new_insn_chain (void)
{
  struct insn_chain *c;

  if (unused_insn_chains == 0)
    {
      c = XOBNEW (&reload_obstack, struct insn_chain);
      INIT_REG_SET (&c->live_throughout);
      INIT_REG_SET (&c->dead_or_set);
    }
  else
    {
      c = unused_insn_chains;
      unused_insn_chains = c->next;
    }
  c->is_caller_save_insn = 0;
  c->need_operand_change = 0;
  c->need_reload = 0;
  c->need_elim = 0;
  return c;
}

/* Small utility function to set all regs in hard reg set TO which are
   allocated to pseudos in regset FROM.  */

void
compute_use_by_pseudos (HARD_REG_SET *to, regset from)
{
  unsigned int regno;
  reg_set_iterator rsi;

  EXECUTE_IF_SET_IN_REG_SET (from, FIRST_PSEUDO_REGISTER, regno, rsi)
    {
      int r = reg_renumber[regno];

      if (r < 0)
        {
          /* reload_combine uses the information from DF_LIVE_IN,
             which might still contain registers that have not
             actually been allocated since they have an
             equivalence.  */
          gcc_assert (ira_conflicts_p || reload_completed);
        }
      else
        add_to_hard_reg_set (to, PSEUDO_REGNO_MODE (regno), r);
    }
}

/* Replace all pseudos found in LOC with their corresponding
   equivalences.  */

static void
replace_pseudos_in (rtx *loc, enum machine_mode mem_mode, rtx usage)
{
  rtx x = *loc;
  enum rtx_code code;
  const char *fmt;
  int i, j;

  if (! x)
    return;

  code = GET_CODE (x);
  if (code == REG)
    {
      unsigned int regno = REGNO (x);

      if (regno < FIRST_PSEUDO_REGISTER)
        return;

      x = eliminate_regs_1 (x, mem_mode, usage, true, false);
      if (x != *loc)
        {
          *loc = x;
          replace_pseudos_in (loc, mem_mode, usage);
          return;
        }

      if (reg_equiv_constant[regno])
        *loc = reg_equiv_constant[regno];
      else if (reg_equiv_invariant[regno])
        *loc = reg_equiv_invariant[regno];
      else if (reg_equiv_mem[regno])
        *loc = reg_equiv_mem[regno];
      else if (reg_equiv_address[regno])
        *loc = gen_rtx_MEM (GET_MODE (x), reg_equiv_address[regno]);
      else
        {
          gcc_assert (!REG_P (regno_reg_rtx[regno])
                      || REGNO (regno_reg_rtx[regno]) != regno);
          *loc = regno_reg_rtx[regno];
        }

      return;
    }
  else if (code == MEM)
    {
      replace_pseudos_in (& XEXP (x, 0), GET_MODE (x), usage);
      return;
    }

  /* Process each of our operands recursively.  */
  fmt = GET_RTX_FORMAT (code);
  for (i = 0; i < GET_RTX_LENGTH (code); i++, fmt++)
    if (*fmt == 'e')
      replace_pseudos_in (&XEXP (x, i), mem_mode, usage);
    else if (*fmt == 'E')
      for (j = 0; j < XVECLEN (x, i); j++)
        replace_pseudos_in (& XVECEXP (x, i, j), mem_mode, usage);
}

/* Determine if the current function has an exception receiver block
   that reaches the exit block via non-exceptional edges  */

static bool
has_nonexceptional_receiver (void)
{
  edge e;
  edge_iterator ei;
  basic_block *tos, *worklist, bb;

  /* If we're not optimizing, then just err on the safe side.  */
  if (!optimize)
    return true;

  /* First determine which blocks can reach exit via normal paths.  */
  tos = worklist = XNEWVEC (basic_block, n_basic_blocks + 1);

  FOR_EACH_BB (bb)
    bb->flags &= ~BB_REACHABLE;

  /* Place the exit block on our worklist.  */
  EXIT_BLOCK_PTR->flags |= BB_REACHABLE;
  *tos++ = EXIT_BLOCK_PTR;

  /* Iterate: find everything reachable from what we've already seen.  */
  while (tos != worklist)
    {
      bb = *--tos;

      FOR_EACH_EDGE (e, ei, bb->preds)
        if (!(e->flags & EDGE_ABNORMAL))
          {
            basic_block src = e->src;

            if (!(src->flags & BB_REACHABLE))
              {
                src->flags |= BB_REACHABLE;
                *tos++ = src;
              }
          }
    }
  free (worklist);

  /* Now see if there's a reachable block with an exceptional incoming
     edge.  */
  FOR_EACH_BB (bb)
    if (bb->flags & BB_REACHABLE && bb_has_abnormal_pred (bb))
      return true;

  /* No exceptional block reached exit unexceptionally.  */
  return false;
}

\f
/* Global variables used by reload and its subroutines.  */

/* The current basic block while in calculate_elim_costs_all_insns.  */
static basic_block elim_bb;

/* Set during calculate_needs if an insn needs register elimination.  */
static int something_needs_elimination;
/* Set during calculate_needs if an insn needs an operand changed.  */
static int something_needs_operands_changed;
/* Set by alter_regs if we spilled a register to the stack.  */
static bool something_was_spilled;

/* Nonzero means we couldn't get enough spill regs.  */
static int failure;

/* Temporary array of pseudo-register number.  */
static int *temp_pseudo_reg_arr;

/* Main entry point for the reload pass.

   FIRST is the first insn of the function being compiled.

   GLOBAL nonzero means we were called from global_alloc
   and should attempt to reallocate any pseudoregs that we
   displace from hard regs we will use for reloads.
   If GLOBAL is zero, we do not have enough information to do that,
   so any pseudo reg that is spilled must go to the stack.

   Return value is nonzero if reload failed
   and we must not do any more for this function.  */

int
reload (rtx first, int global)
{
  int i, n;
  rtx insn;
  struct elim_table *ep;
  basic_block bb;

  /* Make sure even insns with volatile mem refs are recognizable.  */
  init_recog ();

  failure = 0;

  reload_firstobj = XOBNEWVAR (&reload_obstack, char, 0);

  /* Make sure that the last insn in the chain
     is not something that needs reloading.  */
  emit_note (NOTE_INSN_DELETED);

  /* Enable find_equiv_reg to distinguish insns made by reload.  */
  reload_first_uid = get_max_uid ();

#ifdef SECONDARY_MEMORY_NEEDED
  /* Initialize the secondary memory table.  */
  clear_secondary_mem ();
#endif

  /* We don't have a stack slot for any spill reg yet.  */
  memset (spill_stack_slot, 0, sizeof spill_stack_slot);
  memset (spill_stack_slot_width, 0, sizeof spill_stack_slot_width);

  /* Initialize the save area information for caller-save, in case some
     are needed.  */
  init_save_areas ();

  /* Compute which hard registers are now in use
     as homes for pseudo registers.
     This is done here rather than (eg) in global_alloc
     because this point is reached even if not optimizing.  */
  for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
    mark_home_live (i);

  /* A function that has a nonlocal label that can reach the exit
     block via non-exceptional paths must save all call-saved
     registers.  */
  if (cfun->has_nonlocal_label
      && has_nonexceptional_receiver ())
    crtl->saves_all_registers = 1;

  if (crtl->saves_all_registers)
    for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
      if (! call_used_regs[i] && ! fixed_regs[i] && ! LOCAL_REGNO (i))
        df_set_regs_ever_live (i, true);

  reg_old_renumber = XCNEWVEC (short, max_regno);
  memcpy (reg_old_renumber, reg_renumber, max_regno * sizeof (short));
  pseudo_forbidden_regs = XNEWVEC (HARD_REG_SET, max_regno);
  pseudo_previous_regs = XCNEWVEC (HARD_REG_SET, max_regno);

  CLEAR_HARD_REG_SET (bad_spill_regs_global);

  init_eliminable_invariants (first, true);
  init_elim_table ();

  /* Alter each pseudo-reg rtx to contain its hard reg number.  Assign
     stack slots to the pseudos that lack hard regs or equivalents.
     Do not touch virtual registers.  */

  temp_pseudo_reg_arr = XNEWVEC (int, max_regno - LAST_VIRTUAL_REGISTER - 1);
  for (n = 0, i = LAST_VIRTUAL_REGISTER + 1; i < max_regno; i++)
    temp_pseudo_reg_arr[n++] = i;

  if (ira_conflicts_p)
    /* Ask IRA to order pseudo-registers for better stack slot
       sharing.  */
    ira_sort_regnos_for_alter_reg (temp_pseudo_reg_arr, n, reg_max_ref_width);

  for (i = 0; i < n; i++)
    alter_reg (temp_pseudo_reg_arr[i], -1, false);

  /* If we have some registers we think can be eliminated, scan all insns to
     see if there is an insn that sets one of these registers to something
     other than itself plus a constant.  If so, the register cannot be
     eliminated.  Doing this scan here eliminates an extra pass through the
     main reload loop in the most common case where register elimination
     cannot be done.  */
  for (insn = first; insn && num_eliminable; insn = NEXT_INSN (insn))
    if (INSN_P (insn))
      note_stores (PATTERN (insn), mark_not_eliminable, NULL);

  maybe_fix_stack_asms ();

  insns_need_reload = 0;
  something_needs_elimination = 0;

  /* Initialize to -1, which means take the first spill register.  */
  last_spill_reg = -1;

  /* Spill any hard regs that we know we can't eliminate.  */
  CLEAR_HARD_REG_SET (used_spill_regs);
  /* There can be multiple ways to eliminate a register;
     they should be listed adjacently.
     Elimination for any register fails only if all possible ways fail.  */
  for (ep = reg_eliminate; ep < &reg_eliminate[NUM_ELIMINABLE_REGS]; )
    {
      int from = ep->from;
      int can_eliminate = 0;
      do
        {
          can_eliminate |= ep->can_eliminate;
          ep++;
        }
      while (ep < &reg_eliminate[NUM_ELIMINABLE_REGS] && ep->from == from);
      if (! can_eliminate)
        spill_hard_reg (from, 1);
    }

#if !HARD_FRAME_POINTER_IS_FRAME_POINTER
  if (frame_pointer_needed)
    spill_hard_reg (HARD_FRAME_POINTER_REGNUM, 1);
#endif
  finish_spills (global);

  /* From now on, we may need to generate moves differently.  We may also
     allow modifications of insns which cause them to not be recognized.
     Any such modifications will be cleaned up during reload itself.  */
  reload_in_progress = 1;

  /* This loop scans the entire function each go-round
     and repeats until one repetition spills no additional hard regs.  */
  for (;;)
    {
      int something_changed;
      int did_spill;
      HOST_WIDE_INT starting_frame_size;

      starting_frame_size = get_frame_size ();
      something_was_spilled = false;

      set_initial_elim_offsets ();
      set_initial_label_offsets ();

      /* For each pseudo register that has an equivalent location defined,
         try to eliminate any eliminable registers (such as the frame pointer)
         assuming initial offsets for the replacement register, which
         is the normal case.

         If the resulting location is directly addressable, substitute
         the MEM we just got directly for the old REG.

         If it is not addressable but is a constant or the sum of a hard reg
         and constant, it is probably not addressable because the constant is
         out of range, in that case record the address; we will generate
         hairy code to compute the address in a register each time it is
         needed.  Similarly if it is a hard register, but one that is not
         valid as an address register.

         If the location is not addressable, but does not have one of the
         above forms, assign a stack slot.  We have to do this to avoid the
         potential of producing lots of reloads if, e.g., a location involves
         a pseudo that didn't get a hard register and has an equivalent memory
         location that also involves a pseudo that didn't get a hard register.

         Perhaps at some point we will improve reload_when_needed handling
         so this problem goes away.  But that's very hairy.  */

      for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
        if (reg_renumber[i] < 0 && reg_equiv_memory_loc[i])
          {
            rtx x = eliminate_regs (reg_equiv_memory_loc[i], VOIDmode,
                                    NULL_RTX);

            if (strict_memory_address_addr_space_p
                  (GET_MODE (regno_reg_rtx[i]), XEXP (x, 0),
                   MEM_ADDR_SPACE (x)))
              reg_equiv_mem[i] = x, reg_equiv_address[i] = 0;
            else if (CONSTANT_P (XEXP (x, 0))
                     || (REG_P (XEXP (x, 0))
                         && REGNO (XEXP (x, 0)) < FIRST_PSEUDO_REGISTER)
                     || (GET_CODE (XEXP (x, 0)) == PLUS
                         && REG_P (XEXP (XEXP (x, 0), 0))
                         && (REGNO (XEXP (XEXP (x, 0), 0))
                             < FIRST_PSEUDO_REGISTER)
                         && CONSTANT_P (XEXP (XEXP (x, 0), 1))))
              reg_equiv_address[i] = XEXP (x, 0), reg_equiv_mem[i] = 0;
            else
              {
                /* Make a new stack slot.  Then indicate that something
                   changed so we go back and recompute offsets for
                   eliminable registers because the allocation of memory
                   below might change some offset.  reg_equiv_{mem,address}
                   will be set up for this pseudo on the next pass around
                   the loop.  */
                reg_equiv_memory_loc[i] = 0;
                reg_equiv_init[i] = 0;
                alter_reg (i, -1, true);
              }
          }

      if (caller_save_needed)
        setup_save_areas ();

      /* If we allocated another stack slot, redo elimination bookkeeping.  */
      if (something_was_spilled || starting_frame_size != get_frame_size ())
        continue;
      if (starting_frame_size && crtl->stack_alignment_needed)
        {
          /* If we have a stack frame, we must align it now.  The
             stack size may be a part of the offset computation for
             register elimination.  So if this changes the stack size,
             then repeat the elimination bookkeeping.  We don't
             realign when there is no stack, as that will cause a
             stack frame when none is needed should
             STARTING_FRAME_OFFSET not be already aligned to
             STACK_BOUNDARY.  */
          assign_stack_local (BLKmode, 0, crtl->stack_alignment_needed);
          if (starting_frame_size != get_frame_size ())
            continue;
        }

      if (caller_save_needed)
        {
          save_call_clobbered_regs ();
          /* That might have allocated new insn_chain structures.  */
          reload_firstobj = XOBNEWVAR (&reload_obstack, char, 0);
        }

      calculate_needs_all_insns (global);

      if (! ira_conflicts_p)
        /* Don't do it for IRA.  We need this info because we don't
           change live_throughout and dead_or_set for chains when IRA
           is used.  */
        CLEAR_REG_SET (&spilled_pseudos);

      did_spill = 0;

      something_changed = 0;

      /* If we allocated any new memory locations, make another pass
         since it might have changed elimination offsets.  */
      if (something_was_spilled || starting_frame_size != get_frame_size ())
        something_changed = 1;

      /* Even if the frame size remained the same, we might still have
         changed elimination offsets, e.g. if find_reloads called
         force_const_mem requiring the back end to allocate a constant
         pool base register that needs to be saved on the stack.  */
      else if (!verify_initial_elim_offsets ())
        something_changed = 1;

      {
        HARD_REG_SET to_spill;
        CLEAR_HARD_REG_SET (to_spill);
        update_eliminables (&to_spill);
        AND_COMPL_HARD_REG_SET (used_spill_regs, to_spill);

        for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
          if (TEST_HARD_REG_BIT (to_spill, i))
            {
              spill_hard_reg (i, 1);
              did_spill = 1;

              /* Regardless of the state of spills, if we previously had
                 a register that we thought we could eliminate, but now can
                 not eliminate, we must run another pass.

                 Consider pseudos which have an entry in reg_equiv_* which
                 reference an eliminable register.  We must make another pass
                 to update reg_equiv_* so that we do not substitute in the
                 old value from when we thought the elimination could be
                 performed.  */
              something_changed = 1;
            }
      }

      select_reload_regs ();
      if (failure)
        goto failed;

      if (insns_need_reload != 0 || did_spill)
        something_changed |= finish_spills (global);

      if (! something_changed)
        break;

      if (caller_save_needed)
        delete_caller_save_insns ();

      obstack_free (&reload_obstack, reload_firstobj);
    }

  /* If global-alloc was run, notify it of any register eliminations we have
     done.  */
  if (global)
    for (ep = reg_eliminate; ep < &reg_eliminate[NUM_ELIMINABLE_REGS]; ep++)
      if (ep->can_eliminate)
        mark_elimination (ep->from, ep->to);

  /* If a pseudo has no hard reg, delete the insns that made the equivalence.
     If that insn didn't set the register (i.e., it copied the register to
     memory), just delete that insn instead of the equivalencing insn plus
     anything now dead.  If we call delete_dead_insn on that insn, we may
     delete the insn that actually sets the register if the register dies
     there and that is incorrect.  */

  for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
    {
      if (reg_renumber[i] < 0 && reg_equiv_init[i] != 0)
        {
          rtx list;
          for (list = reg_equiv_init[i]; list; list = XEXP (list, 1))
            {
              rtx equiv_insn = XEXP (list, 0);

              /* If we already deleted the insn or if it may trap, we can't
                 delete it.  The latter case shouldn't happen, but can
                 if an insn has a variable address, gets a REG_EH_REGION
                 note added to it, and then gets converted into a load
                 from a constant address.  */
              if (NOTE_P (equiv_insn)
                  || can_throw_internal (equiv_insn))
                ;
              else if (reg_set_p (regno_reg_rtx[i], PATTERN (equiv_insn)))
                delete_dead_insn (equiv_insn);
              else
                SET_INSN_DELETED (equiv_insn);
            }
        }
    }

  /* Use the reload registers where necessary
     by generating move instructions to move the must-be-register
     values into or out of the reload registers.  */

  if (insns_need_reload != 0 || something_needs_elimination
      || something_needs_operands_changed)
    {
      HOST_WIDE_INT old_frame_size = get_frame_size ();

      reload_as_needed (global);

      gcc_assert (old_frame_size == get_frame_size ());

      gcc_assert (verify_initial_elim_offsets ());
    }

  /* If we were able to eliminate the frame pointer, show that it is no
     longer live at the start of any basic block.  If it ls live by
     virtue of being in a pseudo, that pseudo will be marked live
     and hence the frame pointer will be known to be live via that
     pseudo.  */

  if (! frame_pointer_needed)
    FOR_EACH_BB (bb)
      bitmap_clear_bit (df_get_live_in (bb), HARD_FRAME_POINTER_REGNUM);

  /* Come here (with failure set nonzero) if we can't get enough spill
     regs.  */
 failed:

  CLEAR_REG_SET (&changed_allocation_pseudos);
  CLEAR_REG_SET (&spilled_pseudos);
  reload_in_progress = 0;

  /* Now eliminate all pseudo regs by modifying them into
     their equivalent memory references.
     The REG-rtx's for the pseudos are modified in place,
     so all insns that used to refer to them now refer to memory.

     For a reg that has a reg_equiv_address, all those insns
     were changed by reloading so that no insns refer to it any longer;
     but the DECL_RTL of a variable decl may refer to it,
     and if so this causes the debugging info to mention the variable.  */

  for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
    {
      rtx addr = 0;

      if (reg_equiv_mem[i])
        addr = XEXP (reg_equiv_mem[i], 0);

      if (reg_equiv_address[i])
        addr = reg_equiv_address[i];

      if (addr)
        {
          if (reg_renumber[i] < 0)
            {
              rtx reg = regno_reg_rtx[i];

              REG_USERVAR_P (reg) = 0;
              PUT_CODE (reg, MEM);
              XEXP (reg, 0) = addr;
              if (reg_equiv_memory_loc[i])
                MEM_COPY_ATTRIBUTES (reg, reg_equiv_memory_loc[i]);
              else
                {
                  MEM_IN_STRUCT_P (reg) = MEM_SCALAR_P (reg) = 0;
                  MEM_ATTRS (reg) = 0;
                }
              MEM_NOTRAP_P (reg) = 1;
            }
          else if (reg_equiv_mem[i])
            XEXP (reg_equiv_mem[i], 0) = addr;
        }

      /* We don't want complex addressing modes in debug insns
         if simpler ones will do, so delegitimize equivalences
         in debug insns.  */
      if (MAY_HAVE_DEBUG_INSNS && reg_renumber[i] < 0)
        {
          rtx reg = regno_reg_rtx[i];
          rtx equiv = 0;
          df_ref use, next;

          if (reg_equiv_constant[i])
            equiv = reg_equiv_constant[i];
          else if (reg_equiv_invariant[i])
            equiv = reg_equiv_invariant[i];
          else if (reg && MEM_P (reg))
            equiv = targetm.delegitimize_address (reg);
          else if (reg && REG_P (reg) && (int)REGNO (reg) != i)
            equiv = reg;

          if (equiv == reg)
            continue;

          for (use = DF_REG_USE_CHAIN (i); use; use = next)
            {
              insn = DF_REF_INSN (use);

              /* Make sure the next ref is for a different instruction,
                 so that we're not affected by the rescan.  */
              next = DF_REF_NEXT_REG (use);
              while (next && DF_REF_INSN (next) == insn)
                next = DF_REF_NEXT_REG (next);

              if (DEBUG_INSN_P (insn))
                {
                  if (!equiv)
                    {
                      INSN_VAR_LOCATION_LOC (insn) = gen_rtx_UNKNOWN_VAR_LOC ();
                      df_insn_rescan_debug_internal (insn);
                    }
                  else
                    INSN_VAR_LOCATION_LOC (insn)
                      = simplify_replace_rtx (INSN_VAR_LOCATION_LOC (insn),
                                              reg, equiv);
                }
            }
        }
    }

  /* We must set reload_completed now since the cleanup_subreg_operands call
     below will re-recognize each insn and reload may have generated insns
     which are only valid during and after reload.  */
  reload_completed = 1;

  /* Make a pass over all the insns and delete all USEs which we inserted
     only to tag a REG_EQUAL note on them.  Remove all REG_DEAD and REG_UNUSED
     notes.  Delete all CLOBBER insns, except those that refer to the return
     value and the special mem:BLK CLOBBERs added to prevent the scheduler
     from misarranging variable-array code, and simplify (subreg (reg))
     operands.  Strip and regenerate REG_INC notes that may have been moved
     around.  */

  for (insn = first; insn; insn = NEXT_INSN (insn))
    if (INSN_P (insn))
      {
        rtx *pnote;

        if (CALL_P (insn))
          replace_pseudos_in (& CALL_INSN_FUNCTION_USAGE (insn),
                              VOIDmode, CALL_INSN_FUNCTION_USAGE (insn));

        if ((GET_CODE (PATTERN (insn)) == USE
             /* We mark with QImode USEs introduced by reload itself.  */
             && (GET_MODE (insn) == QImode
                 || find_reg_note (insn, REG_EQUAL, NULL_RTX)))
            || (GET_CODE (PATTERN (insn)) == CLOBBER
                && (!MEM_P (XEXP (PATTERN (insn), 0))
                    || GET_MODE (XEXP (PATTERN (insn), 0)) != BLKmode
                    || (GET_CODE (XEXP (XEXP (PATTERN (insn), 0), 0)) != SCRATCH
                        && XEXP (XEXP (PATTERN (insn), 0), 0)
                                != stack_pointer_rtx))
                && (!REG_P (XEXP (PATTERN (insn), 0))
                    || ! REG_FUNCTION_VALUE_P (XEXP (PATTERN (insn), 0)))))
          {
            delete_insn (insn);
            continue;
          }

        /* Some CLOBBERs may survive until here and still reference unassigned
           pseudos with const equivalent, which may in turn cause ICE in later
           passes if the reference remains in place.  */
        if (GET_CODE (PATTERN (insn)) == CLOBBER)
          replace_pseudos_in (& XEXP (PATTERN (insn), 0),
                              VOIDmode, PATTERN (insn));

        /* Discard obvious no-ops, even without -O.  This optimization
           is fast and doesn't interfere with debugging.  */
        if (NONJUMP_INSN_P (insn)
            && GET_CODE (PATTERN (insn)) == SET
            && REG_P (SET_SRC (PATTERN (insn)))
            && REG_P (SET_DEST (PATTERN (insn)))
            && (REGNO (SET_SRC (PATTERN (insn)))
                == REGNO (SET_DEST (PATTERN (insn)))))
          {
            delete_insn (insn);
            continue;
          }

        pnote = &REG_NOTES (insn);
        while (*pnote != 0)
          {
            if (REG_NOTE_KIND (*pnote) == REG_DEAD
                || REG_NOTE_KIND (*pnote) == REG_UNUSED
                || REG_NOTE_KIND (*pnote) == REG_INC)
              *pnote = XEXP (*pnote, 1);
            else
              pnote = &XEXP (*pnote, 1);
          }

#ifdef AUTO_INC_DEC
        add_auto_inc_notes (insn, PATTERN (insn));
#endif

        /* Simplify (subreg (reg)) if it appears as an operand.  */
        cleanup_subreg_operands (insn);

        /* Clean up invalid ASMs so that they don't confuse later passes.
           See PR 21299.  */
        if (asm_noperands (PATTERN (insn)) >= 0)
          {
            extract_insn (insn);
            if (!constrain_operands (1))
              {
                error_for_asm (insn,
                               "%<asm%> operand has impossible constraints");
                delete_insn (insn);
                continue;
              }
          }
      }

  /* If we are doing generic stack checking, give a warning if this
     function's frame size is larger than we expect.  */
  if (flag_stack_check == GENERIC_STACK_CHECK)
    {
      HOST_WIDE_INT size = get_frame_size () + STACK_CHECK_FIXED_FRAME_SIZE;
      static int verbose_warned = 0;

      for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
        if (df_regs_ever_live_p (i) && ! fixed_regs[i] && call_used_regs[i])
          size += UNITS_PER_WORD;

      if (size > STACK_CHECK_MAX_FRAME_SIZE)
        {
          warning (0, "frame size too large for reliable stack checking");
          if (! verbose_warned)
            {
              warning (0, "try reducing the number of local variables");
              verbose_warned = 1;
            }
        }
    }

  free (temp_pseudo_reg_arr);

  /* Indicate that we no longer have known memory locations or constants.  */
  free_reg_equiv ();
  reg_equiv_init = 0;
  free (reg_max_ref_width);
  free (reg_old_renumber);
  free (pseudo_previous_regs);
  free (pseudo_forbidden_regs);

  CLEAR_HARD_REG_SET (used_spill_regs);
  for (i = 0; i < n_spills; i++)
    SET_HARD_REG_BIT (used_spill_regs, spill_regs[i]);

  /* Free all the insn_chain structures at once.  */
  obstack_free (&reload_obstack, reload_startobj);
  unused_insn_chains = 0;
  fixup_abnormal_edges ();

  /* Replacing pseudos with their memory equivalents might have
     created shared rtx.  Subsequent passes would get confused
     by this, so unshare everything here.  */
  unshare_all_rtl_again (first);

#ifdef STACK_BOUNDARY
  /* init_emit has set the alignment of the hard frame pointer
     to STACK_BOUNDARY.  It is very likely no longer valid if
     the hard frame pointer was used for register allocation.  */
  if (!frame_pointer_needed)
    REGNO_POINTER_ALIGN (HARD_FRAME_POINTER_REGNUM) = BITS_PER_UNIT;
#endif

  VEC_free (rtx_p, heap, substitute_stack);

  gcc_assert (bitmap_empty_p (&spilled_pseudos));

  return failure;
}

/* Yet another special case.  Unfortunately, reg-stack forces people to
   write incorrect clobbers in asm statements.  These clobbers must not
   cause the register to appear in bad_spill_regs, otherwise we'll call
   fatal_insn later.  We clear the corresponding regnos in the live
   register sets to avoid this.
   The whole thing is rather sick, I'm afraid.  */

static void
maybe_fix_stack_asms (void)
{
#ifdef STACK_REGS
  const char *constraints[MAX_RECOG_OPERANDS];
  enum machine_mode operand_mode[MAX_RECOG_OPERANDS];
  struct insn_chain *chain;

  for (chain = reload_insn_chain; chain != 0; chain = chain->next)
    {
      int i, noperands;
      HARD_REG_SET clobbered, allowed;
      rtx pat;

      if (! INSN_P (chain->insn)
          || (noperands = asm_noperands (PATTERN (chain->insn))) < 0)
        continue;
      pat = PATTERN (chain->insn);
      if (GET_CODE (pat) != PARALLEL)
        continue;

      CLEAR_HARD_REG_SET (clobbered);
      CLEAR_HARD_REG_SET (allowed);

      /* First, make a mask of all stack regs that are clobbered.  */
      for (i = 0; i < XVECLEN (pat, 0); i++)
        {
          rtx t = XVECEXP (pat, 0, i);
          if (GET_CODE (t) == CLOBBER && STACK_REG_P (XEXP (t, 0)))
            SET_HARD_REG_BIT (clobbered, REGNO (XEXP (t, 0)));
        }

      /* Get the operand values and constraints out of the insn.  */
      decode_asm_operands (pat, recog_data.operand, recog_data.operand_loc,
                           constraints, operand_mode, NULL);

      /* For every operand, see what registers are allowed.  */
      for (i = 0; i < noperands; i++)
        {
          const char *p = constraints[i];
          /* For every alternative, we compute the class of registers allowed
             for reloading in CLS, and merge its contents into the reg set
             ALLOWED.  */
          int cls = (int) NO_REGS;

          for (;;)
            {
              char c = *p;

              if (c == '\0' || c == ',' || c == '#')
                {
                  /* End of one alternative - mark the regs in the current
                     class, and reset the class.  */
                  IOR_HARD_REG_SET (allowed, reg_class_contents[cls]);
                  cls = NO_REGS;
                  p++;
                  if (c == '#')
                    do {
                      c = *p++;
                    } while (c != '\0' && c != ',');
                  if (c == '\0')
                    break;
                  continue;
                }

              switch (c)
                {
                case '=': case '+': case '*': case '%': case '?': case '!':
                case '0': case '1': case '2': case '3': case '4': case '<':
                case '>': case 'V': case 'o': case '&': case 'E': case 'F':
                case 's': case 'i': case 'n': case 'X': case 'I': case 'J':
                case 'K': case 'L': case 'M': case 'N': case 'O': case 'P':
                case TARGET_MEM_CONSTRAINT:
                  break;

                case 'p':
                  cls = (int) reg_class_subunion[cls]
                      [(int) base_reg_class (VOIDmode, ADDRESS, SCRATCH)];
                  break;

                case 'g':
                case 'r':
                  cls = (int) reg_class_subunion[cls][(int) GENERAL_REGS];
                  break;

                default:
                  if (EXTRA_ADDRESS_CONSTRAINT (c, p))
                    cls = (int) reg_class_subunion[cls]
                      [(int) base_reg_class (VOIDmode, ADDRESS, SCRATCH)];
                  else
                    cls = (int) reg_class_subunion[cls]
                      [(int) REG_CLASS_FROM_CONSTRAINT (c, p)];
                }
              p += CONSTRAINT_LEN (c, p);
            }
        }
      /* Those of the registers which are clobbered, but allowed by the
         constraints, must be usable as reload registers.  So clear them
         out of the life information.  */
      AND_HARD_REG_SET (allowed, clobbered);
      for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
        if (TEST_HARD_REG_BIT (allowed, i))
          {
            CLEAR_REGNO_REG_SET (&chain->live_throughout, i);
            CLEAR_REGNO_REG_SET (&chain->dead_or_set, i);
          }
    }

#endif
}
\f
/* Copy the global variables n_reloads and rld into the corresponding elts
   of CHAIN.  */
static void
copy_reloads (struct insn_chain *chain)
{
  chain->n_reloads = n_reloads;
  chain->rld = XOBNEWVEC (&reload_obstack, struct reload, n_reloads);
  memcpy (chain->rld, rld, n_reloads * sizeof (struct reload));
  reload_insn_firstobj = XOBNEWVAR (&reload_obstack, char, 0);
}

/* Walk the chain of insns, and determine for each whether it needs reloads
   and/or eliminations.  Build the corresponding insns_need_reload list, and
   set something_needs_elimination as appropriate.  */
static void
calculate_needs_all_insns (int global)
{
  struct insn_chain **pprev_reload = &insns_need_reload;
  struct insn_chain *chain, *next = 0;

  something_needs_elimination = 0;

  reload_insn_firstobj = XOBNEWVAR (&reload_obstack, char, 0);
  for (chain = reload_insn_chain; chain != 0; chain = next)
    {
      rtx insn = chain->insn;

      next = chain->next;

      /* Clear out the shortcuts.  */
      chain->n_reloads = 0;
      chain->need_elim = 0;
      chain->need_reload = 0;
      chain->need_operand_change = 0;

      /* If this is a label, a JUMP_INSN, or has REG_NOTES (which might
         include REG_LABEL_OPERAND and REG_LABEL_TARGET), we need to see
         what effects this has on the known offsets at labels.  */

      if (LABEL_P (insn) || JUMP_P (insn)
          || (INSN_P (insn) && REG_NOTES (insn) != 0))
        set_label_offsets (insn, insn, 0);

      if (INSN_P (insn))
        {
          rtx old_body = PATTERN (insn);
          int old_code = INSN_CODE (insn);
          rtx old_notes = REG_NOTES (insn);
          int did_elimination = 0;
          int operands_changed = 0;
          rtx set = single_set (insn);

          /* Skip insns that only set an equivalence.  */
          if (set && REG_P (SET_DEST (set))
              && reg_renumber[REGNO (SET_DEST (set))] < 0
              && (reg_equiv_constant[REGNO (SET_DEST (set))]
                  || (reg_equiv_invariant[REGNO (SET_DEST (set))]))
                      && reg_equiv_init[REGNO (SET_DEST (set))])
            continue;

          /* If needed, eliminate any eliminable registers.  */
          if (num_eliminable || num_eliminable_invariants)
            did_elimination = eliminate_regs_in_insn (insn, 0);

          /* Analyze the instruction.  */
          operands_changed = find_reloads (insn, 0, spill_indirect_levels,
                                           global, spill_reg_order);

          /* If a no-op set needs more than one reload, this is likely
             to be something that needs input address reloads.  We
             can't get rid of this cleanly later, and it is of no use
             anyway, so discard it now.
             We only do this when expensive_optimizations is enabled,
             since this complements reload inheritance / output
             reload deletion, and it can make debugging harder.  */
          if (flag_expensive_optimizations && n_reloads > 1)
            {
              rtx set = single_set (insn);
              if (set
                  &&
                  ((SET_SRC (set) == SET_DEST (set)
                    && REG_P (SET_SRC (set))
                    && REGNO (SET_SRC (set)) >= FIRST_PSEUDO_REGISTER)
                   || (REG_P (SET_SRC (set)) && REG_P (SET_DEST (set))
                       && reg_renumber[REGNO (SET_SRC (set))] < 0
                       && reg_renumber[REGNO (SET_DEST (set))] < 0
                       && reg_equiv_memory_loc[REGNO (SET_SRC (set))] != NULL
                       && reg_equiv_memory_loc[REGNO (SET_DEST (set))] != NULL
                       && rtx_equal_p (reg_equiv_memory_loc
                                       [REGNO (SET_SRC (set))],
                                       reg_equiv_memory_loc
                                       [REGNO (SET_DEST (set))]))))
                {
                  if (ira_conflicts_p)
                    /* Inform IRA about the insn deletion.  */
                    ira_mark_memory_move_deletion (REGNO (SET_DEST (set)),
                                                   REGNO (SET_SRC (set)));
                  delete_insn (insn);
                  /* Delete it from the reload chain.  */
                  if (chain->prev)
                    chain->prev->next = next;
                  else
                    reload_insn_chain = next;
                  if (next)
                    next->prev = chain->prev;
                  chain->next = unused_insn_chains;
                  unused_insn_chains = chain;
                  continue;
                }
            }
          if (num_eliminable)
            update_eliminable_offsets ();

          /* Remember for later shortcuts which insns had any reloads or
             register eliminations.  */
          chain->need_elim = did_elimination;
          chain->need_reload = n_reloads > 0;
          chain->need_operand_change = operands_changed;

          /* Discard any register replacements done.  */
          if (did_elimination)
            {
              obstack_free (&reload_obstack, reload_insn_firstobj);
              PATTERN (insn) = old_body;
              INSN_CODE (insn) = old_code;
              REG_NOTES (insn) = old_notes;
              something_needs_elimination = 1;
            }

          something_needs_operands_changed |= operands_changed;

          if (n_reloads != 0)
            {
              copy_reloads (chain);
              *pprev_reload = chain;
              pprev_reload = &chain->next_need_reload;
            }
        }
    }
  *pprev_reload = 0;
}
\f
/* This function is called from the register allocator to set up estimates
   for the cost of eliminating pseudos which have REG_EQUIV equivalences to
   an invariant.  The structure is similar to calculate_needs_all_insns.  */

void
calculate_elim_costs_all_insns (void)
{
  int *reg_equiv_init_cost;
  basic_block bb;
  int i;

  reg_equiv_init_cost = XCNEWVEC (int, max_regno);
  init_elim_table ();
  init_eliminable_invariants (get_insns (), false);

  set_initial_elim_offsets ();
  set_initial_label_offsets ();

  FOR_EACH_BB (bb)
    {
      rtx insn;
      elim_bb = bb;

      FOR_BB_INSNS (bb, insn)
        {
          /* If this is a label, a JUMP_INSN, or has REG_NOTES (which might
             include REG_LABEL_OPERAND and REG_LABEL_TARGET), we need to see
             what effects this has on the known offsets at labels.  */

          if (LABEL_P (insn) || JUMP_P (insn)
              || (INSN_P (insn) && REG_NOTES (insn) != 0))
            set_label_offsets (insn, insn, 0);

          if (INSN_P (insn))
            {
              rtx set = single_set (insn);

              /* Skip insns that only set an equivalence.  */
              if (set && REG_P (SET_DEST (set))
                  && reg_renumber[REGNO (SET_DEST (set))] < 0
                  && (reg_equiv_constant[REGNO (SET_DEST (set))]
                      || (reg_equiv_invariant[REGNO (SET_DEST (set))])))
                {
                  unsigned regno = REGNO (SET_DEST (set));
                  rtx init = reg_equiv_init[regno];
                  if (init)
                    {
                      rtx t = eliminate_regs_1 (SET_SRC (set), VOIDmode, insn,
                                                false, true);
                      int cost = rtx_cost (t, SET,
                                           optimize_bb_for_speed_p (bb));
                      int freq = REG_FREQ_FROM_BB (bb);

                      reg_equiv_init_cost[regno] = cost * freq;
                      continue;
                    }
                }
              /* If needed, eliminate any eliminable registers.  */
              if (num_eliminable || num_eliminable_invariants)
                elimination_costs_in_insn (insn);

              if (num_eliminable)
                update_eliminable_offsets ();
            }
        }
    }
  for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++)
    {
      if (reg_equiv_invariant[i])
        {
          if (reg_equiv_init[i])
            {
              int cost = reg_equiv_init_cost[i];
              if (dump_file)
                fprintf (dump_file,
                         "Reg %d has equivalence, initial gains %d\n", i, cost);
              if (cost != 0)
                ira_adjust_equiv_reg_cost (i, cost);
            }
          else
            {
              if (dump_file)
                fprintf (dump_file,
                         "Reg %d had equivalence, but can't be eliminated\n",
                         i);
              ira_adjust_equiv_reg_cost (i, 0);
            }
        }
    }

  free_reg_equiv ();
  free (reg_equiv_init_cost);
}
\f
/* Comparison function for qsort to decide which of two reloads
   should be handled first.  *P1 and *P2 are the reload numbers.  */

static int
reload_reg_class_lower (const void *r1p, const void *r2p)
{
  int r1 = *(const short *) r1p, r2 = *(const short *) r2p;
  int t;

  /* Consider required reloads before optional ones.  */
  t = rld[r1].optional - rld[r2].optional;
  if (t != 0)
    return t;

  /* Count all solitary classes before non-solitary ones.  */
  t = ((reg_class_size[(int) rld[r2].rclass] == 1)
       - (reg_class_size[(int) rld[r1].rclass] == 1));
  if (t != 0)
    return t;

  /* Aside from solitaires, consider all multi-reg groups first.  */
  t = rld[r2].nregs - rld[r1].nregs;
  if (t != 0)
    return t;

  /* Consider reloads in order of increasing reg-class number.  */
  t = (int) rld[r1].rclass - (int) rld[r2].rclass;
  if (t != 0)
    return t;

  /* If reloads are equally urgent, sort by reload number,
     so that the results of qsort leave nothing to chance.  */
  return r1 - r2;
}
\f
/* The cost of spilling each hard reg.  */
static int spill_cost[FIRST_PSEUDO_REGISTER];

/* When spilling multiple hard registers, we use SPILL_COST for the first
   spilled hard reg and SPILL_ADD_COST for subsequent regs.  SPILL_ADD_COST
   only the first hard reg for a multi-reg pseudo.  */
static int spill_add_cost[FIRST_PSEUDO_REGISTER];

/* Map of hard regno to pseudo regno currently occupying the hard
   reg.  */
static int hard_regno_to_pseudo_regno[FIRST_PSEUDO_REGISTER];

/* Update the spill cost arrays, considering that pseudo REG is live.  */

static void
count_pseudo (int reg)
{
  int freq = REG_FREQ (reg);
  int r = reg_renumber[reg];
  int nregs;

  if (REGNO_REG_SET_P (&pseudos_counted, reg)
      || REGNO_REG_SET_P (&spilled_pseudos, reg)
      /* Ignore spilled pseudo-registers which can be here only if IRA
         is used.  */
      || (ira_conflicts_p && r < 0))
    return;

  SET_REGNO_REG_SET (&pseudos_counted, reg);

  gcc_assert (r >= 0);

  spill_add_cost[r] += freq;
  nregs = hard_regno_nregs[r][PSEUDO_REGNO_MODE (reg)];
  while (nregs-- > 0)
    {
      hard_regno_to_pseudo_regno[r + nregs] = reg;
      spill_cost[r + nregs] += freq;
    }
}

/* Calculate the SPILL_COST and SPILL_ADD_COST arrays and determine the
   contents of BAD_SPILL_REGS for the insn described by CHAIN.  */

static void
order_regs_for_reload (struct insn_chain *chain)
{
  unsigned i;
  HARD_REG_SET used_by_pseudos;
  HARD_REG_SET used_by_pseudos2;
  reg_set_iterator rsi;

  COPY_HARD_REG_SET (bad_spill_regs, fixed_reg_set);

  memset (spill_cost, 0, sizeof spill_cost);
  memset (spill_add_cost, 0, sizeof spill_add_cost);
  for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
    hard_regno_to_pseudo_regno[i] = -1;

  /* Count number of uses of each hard reg by pseudo regs allocated to it
     and then order them by decreasing use.  First exclude hard registers
     that are live in or across this insn.  */

  REG_SET_TO_HARD_REG_SET (used_by_pseudos, &chain->live_throughout);
  REG_SET_TO_HARD_REG_SET (used_by_pseudos2, &chain->dead_or_set);
  IOR_HARD_REG_SET (bad_spill_regs, used_by_pseudos);
  IOR_HARD_REG_SET (bad_spill_regs, used_by_pseudos2);

  /* Now find out which pseudos are allocated to it, and update
     hard_reg_n_uses.  */
  CLEAR_REG_SET (&pseudos_counted);

  EXECUTE_IF_SET_IN_REG_SET
    (&chain->live_throughout, FIRST_PSEUDO_REGISTER, i, rsi)
    {
      count_pseudo (i);
    }
  EXECUTE_IF_SET_IN_REG_SET
    (&chain->dead_or_set, FIRST_PSEUDO_REGISTER, i, rsi)
    {
      count_pseudo (i);
    }
  CLEAR_REG_SET (&pseudos_counted);
}
\f
/* Vector of reload-numbers showing the order in which the reloads should
   be processed.  */
static short reload_order[MAX_RELOADS];

/* This is used to keep track of the spill regs used in one insn.  */
static HARD_REG_SET used_spill_regs_local;

/* We decided to spill hard register SPILLED, which has a size of
   SPILLED_NREGS.  Determine how pseudo REG, which is live during the insn,
   is affected.  We will add it to SPILLED_PSEUDOS if necessary, and we will
   update SPILL_COST/SPILL_ADD_COST.  */

static void
count_spilled_pseudo (int spilled, int spilled_nregs, int reg)
{
  int freq = REG_FREQ (reg);
  int r = reg_renumber[reg];
  int nregs = hard_regno_nregs[r][PSEUDO_REGNO_MODE (reg)];

  /* Ignore spilled pseudo-registers which can be here only if IRA is
     used.  */
  if ((ira_conflicts_p && r < 0)
      || REGNO_REG_SET_P (&spilled_pseudos, reg)
      || spilled + spilled_nregs <= r || r + nregs <= spilled)
    return;

  SET_REGNO_REG_SET (&spilled_pseudos, reg);

  spill_add_cost[r] -= freq;
  while (nregs-- > 0)
    {
      hard_regno_to_pseudo_regno[r + nregs] = -1;
      spill_cost[r + nregs] -= freq;
    }
}

/* Find reload register to use for reload number ORDER.  */

static int
find_reg (struct insn_chain *chain, int order)
{
  int rnum = reload_order[order];
  struct reload *rl = rld + rnum;
  int best_cost = INT_MAX;
  int best_reg = -1;
  unsigned int i, j, n;
  int k;
  HARD_REG_SET not_usable;
  HARD_REG_SET used_by_other_reload;
  reg_set_iterator rsi;
  static int regno_pseudo_regs[FIRST_PSEUDO_REGISTER];
  static int best_regno_pseudo_regs[FIRST_PSEUDO_REGISTER];

  COPY_HARD_REG_SET (not_usable, bad_spill_regs);
  IOR_HARD_REG_SET (not_usable, bad_spill_regs_global);
  IOR_COMPL_HARD_REG_SET (not_usable, reg_class_contents[rl->rclass]);

  CLEAR_HARD_REG_SET (used_by_other_reload);
  for (k = 0; k < order; k++)
    {
      int other = reload_order[k];

      if (rld[other].regno >= 0 && reloads_conflict (other, rnum))
        for (j = 0; j < rld[other].nregs; j++)
          SET_HARD_REG_BIT (used_by_other_reload, rld[other].regno + j);
    }

  for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
    {
#ifdef REG_ALLOC_ORDER
      unsigned int regno = reg_alloc_order[i];
#else
      unsigned int regno = i;
#endif

      if (! TEST_HARD_REG_BIT (not_usable, regno)
          && ! TEST_HARD_REG_BIT (used_by_other_reload, regno)
          && HARD_REGNO_MODE_OK (regno, rl->mode))
        {
          int this_cost = spill_cost[regno];
          int ok = 1;
          unsigned int this_nregs = hard_regno_nregs[regno][rl->mode];

          for (j = 1; j < this_nregs; j++)
            {
              this_cost += spill_add_cost[regno + j];
              if ((TEST_HARD_REG_BIT (not_usable, regno + j))
                  || TEST_HARD_REG_BIT (used_by_other_reload, regno + j))
                ok = 0;
            }
          if (! ok)
            continue;

          if (ira_conflicts_p)
            {
              /* Ask IRA to find a better pseudo-register for
                 spilling.  */
              for (n = j = 0; j < this_nregs; j++)
                {
                  int r = hard_regno_to_pseudo_regno[regno + j];

                  if (r < 0)
                    continue;
                  if (n == 0 || regno_pseudo_regs[n - 1] != r)
                    regno_pseudo_regs[n++] = r;
                }
              regno_pseudo_regs[n++] = -1;
              if (best_reg < 0
                  || ira_better_spill_reload_regno_p (regno_pseudo_regs,
                                                      best_regno_pseudo_regs,
                                                      rl->in, rl->out,
                                                      chain->insn))
                {
                  best_reg = regno;
                  for (j = 0;; j++)
                    {
                      best_regno_pseudo_regs[j] = regno_pseudo_regs[j];
                      if (regno_pseudo_regs[j] < 0)
                        break;
                    }
                }
              continue;
            }

          if (rl->in && REG_P (rl->in) && REGNO (rl->in) == regno)
            this_cost--;
          if (rl->out && REG_P (rl->out) && REGNO (rl->out) == regno)
            this_cost--;
          if (this_cost < best_cost
              /* Among registers with equal cost, prefer caller-saved ones, or
                 use REG_ALLOC_ORDER if it is defined.  */
              || (this_cost == best_cost
#ifdef REG_ALLOC_ORDER
                  && (inv_reg_alloc_order[regno]
                      < inv_reg_alloc_order[best_reg])
#else
                  && call_used_regs[regno]
                  && ! call_used_regs[best_reg]
#endif
                  ))
            {
              best_reg = regno;
              best_cost = this_cost;
            }
        }
    }
  if (best_reg == -1)
    return 0;

  if (dump_file)
    fprintf (dump_file, "Using reg %d for reload %d\n", best_reg, rnum);

  rl->nregs = hard_regno_nregs[best_reg][rl->mode];
  rl->regno = best_reg;

  EXECUTE_IF_SET_IN_REG_SET
    (&chain->live_throughout, FIRST_PSEUDO_REGISTER, j, rsi)
    {
      count_spilled_pseudo (best_reg, rl->nregs, j);
    }

  EXECUTE_IF_SET_IN_REG_SET
    (&chain->dead_or_set, FIRST_PSEUDO_REGISTER, j, rsi)
    {
      count_spilled_pseudo (best_reg, rl->nregs, j);
    }

  for (i = 0; i < rl->nregs; i++)
    {
      gcc_assert (spill_cost[best_reg + i] == 0);
      gcc_assert (spill_add_cost[best_reg + i] == 0);
      gcc_assert (hard_regno_to_pseudo_regno[best_reg + i] == -1);
      SET_HARD_REG_BIT (used_spill_regs_local, best_reg + i);
    }
  return 1;
}

/* Find more reload regs to satisfy the remaining need of an insn, which
   is given by CHAIN.
   Do it by ascending class number, since otherwise a reg
   might be spilled for a big class and might fail to count
   for a smaller class even though it belongs to that class.  */

static void
find_reload_regs (struct insn_chain *chain)
{
  int i;

  /* In order to be certain of getting the registers we need,
     we must sort the reloads into order of increasing register class.
     Then our grabbing of reload registers will parallel the process
     that provided the reload registers.  */
  for (i = 0; i < chain->n_reloads; i++)
    {
      /* Show whether this reload already has a hard reg.  */
      if (chain->rld[i].reg_rtx)
        {
          int regno = REGNO (chain->rld[i].reg_rtx);
          chain->rld[i].regno = regno;
          chain->rld[i].nregs
            = hard_regno_nregs[regno][GET_MODE (chain->rld[i].reg_rtx)];
        }
      else
        chain->rld[i].regno = -1;
      reload_order[i] = i;
    }

  n_reloads = chain->n_reloads;
  memcpy (rld, chain->rld, n_reloads * sizeof (struct reload));

  CLEAR_HARD_REG_SET (used_spill_regs_local);

  if (dump_file)
    fprintf (dump_file, "Spilling for insn %d.\n", INSN_UID (chain->insn));

  qsort (reload_order, n_reloads, sizeof (short), reload_reg_class_lower);

  /* Compute the order of preference for hard registers to spill.  */

  order_regs_for_reload (chain);

  for (i = 0; i < n_reloads; i++)
    {
      int r = reload_order[i];

      /* Ignore reloads that got marked inoperative.  */
      if ((rld[r].out != 0 || rld[r].in != 0 || rld[r].secondary_p)
          && ! rld[r].optional
          && rld[r].regno == -1)
        if (! find_reg (chain, i))
          {
            if (dump_file)
              fprintf (dump_file, "reload failure for reload %d\n", r);
            spill_failure (chain->insn, rld[r].rclass);
            failure = 1;
            return;
          }
    }

  COPY_HARD_REG_SET (chain->used_spill_regs, used_spill_regs_local);
  IOR_HARD_REG_SET (used_spill_regs, used_spill_regs_local);

  memcpy (chain->rld, rld, n_reloads * sizeof (struct reload));
}

static void
select_reload_regs (void)
{
  struct insn_chain *chain;

  /* Try to satisfy the needs for each insn.  */
  for (chain = insns_need_reload; chain != 0;
       chain = chain->next_need_reload)
    find_reload_regs (chain);
}
\f
/* Delete all insns that were inserted by emit_caller_save_insns during
   this iteration.  */
static void
delete_caller_save_insns (void)
{
  struct insn_chain *c = reload_insn_chain;

  while (c != 0)
    {
      while (c != 0 && c->is_caller_save_insn)
        {
          struct insn_chain *next = c->next;
          rtx insn = c->insn;

          if (c == reload_insn_chain)
            reload_insn_chain = next;
          delete_insn (insn);

          if (next)
            next->prev = c->prev;
          if (c->prev)
            c->prev->next = next;
          c->next = unused_insn_chains;
          unused_insn_chains = c;
          c = next;
        }
      if (c != 0)
        c = c->next;
    }
}
\f
/* Handle the failure to find a register to spill.
   INSN should be one of the insns which needed this particular spill reg.  */

static void
spill_failure (rtx insn, enum reg_class rclass)
{
  if (asm_noperands (PATTERN (insn)) >= 0)
    error_for_asm (insn, "can%'t find a register in class %qs while "
                   "reloading %<asm%>",
                   reg_class_names[rclass]);
  else
    {
      error ("unable to find a register to spill in class %qs",
             reg_class_names[rclass]);

      if (dump_file)
        {
          fprintf (dump_file, "\nReloads for insn # %d\n", INSN_UID (insn));
          debug_reload_to_stream (dump_file);
        }
      fatal_insn ("this is the insn:", insn);
    }
}
\f
/* Delete an unneeded INSN and any previous insns who sole purpose is loading
   data that is dead in INSN.  */

static void
delete_dead_insn (rtx insn)
{
  rtx prev = prev_active_insn (insn);
  rtx prev_dest;

  /* If the previous insn sets a register that dies in our insn, delete it
     too.  */
  if (prev && GET_CODE (PATTERN (prev)) == SET
      && (prev_dest = SET_DEST (PATTERN (prev)), REG_P (prev_dest))
      && reg_mentioned_p (prev_dest, PATTERN (insn))
      && find_regno_note (insn, REG_DEAD, REGNO (prev_dest))
      && ! side_effects_p (SET_SRC (PATTERN (prev))))
    delete_dead_insn (prev);

  SET_INSN_DELETED (insn);
}

/* Modify the home of pseudo-reg I.
   The new home is present in reg_renumber[I].

   FROM_REG may be the hard reg that the pseudo-reg is being spilled from;
   or it may be -1, meaning there is none or it is not relevant.
   This is used so that all pseudos spilled from a given hard reg
   can share one stack slot.  */

static void
alter_reg (int i, int from_reg, bool dont_share_p)
{
  /* When outputting an inline function, this can happen
     for a reg that isn't actually used.  */
  if (regno_reg_rtx[i] == 0)
    return;

  /* If the reg got changed to a MEM at rtl-generation time,
     ignore it.  */
  if (!REG_P (regno_reg_rtx[i]))
    return;

  /* Modify the reg-rtx to contain the new hard reg
     number or else to contain its pseudo reg number.  */
  SET_REGNO (regno_reg_rtx[i],
             reg_renumber[i] >= 0 ? reg_renumber[i] : i);

  /* If we have a pseudo that is needed but has no hard reg or equivalent,
     allocate a stack slot for it.  */

  if (reg_renumber[i] < 0
      && REG_N_REFS (i) > 0
      && reg_equiv_constant[i] == 0
      && (reg_equiv_invariant[i] == 0 || reg_equiv_init[i] == 0)
      && reg_equiv_memory_loc[i] == 0)
    {
      rtx x = NULL_RTX;
      enum machine_mode mode = GET_MODE (regno_reg_rtx[i]);
      unsigned int inherent_size = PSEUDO_REGNO_BYTES (i);
      unsigned int inherent_align = GET_MODE_ALIGNMENT (mode);
      unsigned int total_size = MAX (inherent_size, reg_max_ref_width[i]);
      unsigned int min_align = reg_max_ref_width[i] * BITS_PER_UNIT;
      int adjust = 0;

      something_was_spilled = true;

      if (ira_conflicts_p)
        {
          /* Mark the spill for IRA.  */
          SET_REGNO_REG_SET (&spilled_pseudos, i);
          if (!dont_share_p)
            x = ira_reuse_stack_slot (i, inherent_size, total_size);
        }

      if (x)
        ;

      /* Each pseudo reg has an inherent size which comes from its own mode,
         and a total size which provides room for paradoxical subregs
         which refer to the pseudo reg in wider modes.

         We can use a slot already allocated if it provides both
         enough inherent space and enough total space.
         Otherwise, we allocate a new slot, making sure that it has no less
         inherent space, and no less total space, then the previous slot.  */
      else if (from_reg == -1 || (!dont_share_p && ira_conflicts_p))
        {
          rtx stack_slot;

          /* No known place to spill from => no slot to reuse.  */
          x = assign_stack_local (mode, total_size,
                                  min_align > inherent_align
                                  || total_size > inherent_size ? -1 : 0);

          stack_slot = x;

          /* Cancel the big-endian correction done in assign_stack_local.
             Get the address of the beginning of the slot.  This is so we
             can do a big-endian correction unconditionally below.  */
          if (BYTES_BIG_ENDIAN)
            {
              adjust = inherent_size - total_size;
              if (adjust)
                stack_slot
                  = adjust_address_nv (x, mode_for_size (total_size
                                                         * BITS_PER_UNIT,
                                                         MODE_INT, 1),
                                       adjust);
            }

          if (! dont_share_p && ira_conflicts_p)
            /* Inform IRA about allocation a new stack slot.  */
            ira_mark_new_stack_slot (stack_slot, i, total_size);
        }

      /* Reuse a stack slot if possible.  */
      else if (spill_stack_slot[from_reg] != 0
               && spill_stack_slot_width[from_reg] >= total_size
               && (GET_MODE_SIZE (GET_MODE (spill_stack_slot[from_reg]))
                   >= inherent_size)
               && MEM_ALIGN (spill_stack_slot[from_reg]) >= min_align)
        x = spill_stack_slot[from_reg];

      /* Allocate a bigger slot.  */
      else
        {
          /* Compute maximum size needed, both for inherent size
             and for total size.  */
          rtx stack_slot;

          if (spill_stack_slot[from_reg])
            {
              if (GET_MODE_SIZE (GET_MODE (spill_stack_slot[from_reg]))
                  > inherent_size)
                mode = GET_MODE (spill_stack_slot[from_reg]);
              if (spill_stack_slot_width[from_reg] > total_size)
                total_size = spill_stack_slot_width[from_reg];
              if (MEM_ALIGN (spill_stack_slot[from_reg]) > min_align)
                min_align = MEM_ALIGN (spill_stack_slot[from_reg]);
            }

          /* Make a slot with that size.  */
          x = assign_stack_local (mode, total_size,
                                  min_align > inherent_align
                                  || total_size > inherent_size ? -1 : 0);
          stack_slot = x;

          /* Cancel the  big-endian correction done in assign_stack_local.
             Get the address of the beginning of the slot.  This is so we
             can do a big-endian correction unconditionally below.  */
          if (BYTES_BIG_ENDIAN)
            {
              adjust = GET_MODE_SIZE (mode) - total_size;
              if (adjust)
                stack_slot
                  = adjust_address_nv (x, mode_for_size (total_size
                                                         * BITS_PER_UNIT,
                                                         MODE_INT, 1),
                                       adjust);
            }

          spill_stack_slot[from_reg] = stack_slot;
          spill_stack_slot_width[from_reg] = total_size;
        }

      /* On a big endian machine, the "address" of the slot
         is the address of the low part that fits its inherent mode.  */
      if (BYTES_BIG_ENDIAN && inherent_size < total_size)
        adjust += (total_size - inherent_size);

      /* If we have any adjustment to make, or if the stack slot is the
         wrong mode, make a new stack slot.  */
      x = adjust_address_nv (x, GET_MODE (regno_reg_rtx[i]), adjust);

      /* Set all of the memory attributes as appropriate for a spill.  */
      set_mem_attrs_for_spill (x);

      /* Save the stack slot for later.  */
      reg_equiv_memory_loc[i] = x;
    }
}

/* Mark the slots in regs_ever_live for the hard regs used by
   pseudo-reg number REGNO, accessed in MODE.  */

static void
mark_home_live_1 (int regno, enum machine_mode mode)
{
  int i, lim;

  i = reg_renumber[regno];
  if (i < 0)
    return;
  lim = end_hard_regno (mode, i);
  while (i < lim)
    df_set_regs_ever_live(i++, true);
}

/* Mark the slots in regs_ever_live for the hard regs
   used by pseudo-reg number REGNO.  */

void
mark_home_live (int regno)
{
  if (reg_renumber[regno] >= 0)
    mark_home_live_1 (regno, PSEUDO_REGNO_MODE (regno));
}
\f
/* This function handles the tracking of elimination offsets around branches.

   X is a piece of RTL being scanned.

   INSN is the insn that it came from, if any.

   INITIAL_P is nonzero if we are to set the offset to be the initial
   offset and zero if we are setting the offset of the label to be the
   current offset.  */

static void
set_label_offsets (rtx x, rtx insn, int initial_p)
{
  enum rtx_code code = GET_CODE (x);
  rtx tem;
  unsigned int i;
  struct elim_table *p;

  switch (code)
    {
    case LABEL_REF:
      if (LABEL_REF_NONLOCAL_P (x))
        return;

      x = XEXP (x, 0);

      /* ... fall through ...  */

    case CODE_LABEL:
      /* If we know nothing about this label, set the desired offsets.  Note
         that this sets the offset at a label to be the offset before a label
         if we don't know anything about the label.  This is not correct for
         the label after a BARRIER, but is the best guess we can make.  If
         we guessed wrong, we will suppress an elimination that might have
         been possible had we been able to guess correctly.  */

      if (! offsets_known_at[CODE_LABEL_NUMBER (x) - first_label_num])
        {
          for (i = 0; i < NUM_ELIMINABLE_REGS; i++)
            offsets_at[CODE_LABEL_NUMBER (x) - first_label_num][i]
              = (initial_p ? reg_eliminate[i].initial_offset
                 : reg_eliminate[i].offset);
          offsets_known_at[CODE_LABEL_NUMBER (x) - first_label_num] = 1;
        }

      /* Otherwise, if this is the definition of a label and it is
         preceded by a BARRIER, set our offsets to the known offset of
         that label.  */

      else if (x == insn
               && (tem = prev_nonnote_insn (insn)) != 0
               && BARRIER_P (tem))
        set_offsets_for_label (insn);
      else
        /* If neither of the above cases is true, compare each offset
           with those previously recorded and suppress any eliminations
           where the offsets disagree.  */

        for (i = 0; i < NUM_ELIMINABLE_REGS; i++)
          if (offsets_at[CODE_LABEL_NUMBER (x) - first_label_num][i]
              != (initial_p ? reg_eliminate[i].initial_offset
                  : reg_eliminate[i].offset))
            reg_eliminate[i].can_eliminate = 0;

      return;

    case JUMP_INSN:
      set_label_offsets (PATTERN (insn), insn, initial_p);

      /* ... fall through ...  */

    case INSN:
    case CALL_INSN:
      /* Any labels mentioned in REG_LABEL_OPERAND notes can be branched
         to indirectly and hence must have all eliminations at their
         initial offsets.  */
      for (tem = REG_NOTES (x); tem; tem = XEXP (tem, 1))
        if (REG_NOTE_KIND (tem) == REG_LABEL_OPERAND)
          set_label_offsets (XEXP (tem, 0), insn, 1);
      return;

    case PARALLEL:
    case ADDR_VEC:
    case ADDR_DIFF_VEC:
      /* Each of the labels in the parallel or address vector must be
         at their initial offsets.  We want the first field for PARALLEL
         and ADDR_VEC and the second field for ADDR_DIFF_VEC.  */

      for (i = 0; i < (unsigned) XVECLEN (x, code == ADDR_DIFF_VEC); i++)
        set_label_offsets (XVECEXP (x, code == ADDR_DIFF_VEC, i),
                           insn, initial_p);
      return;

    case SET:
      /* We only care about setting PC.  If the source is not RETURN,
         IF_THEN_ELSE, or a label, disable any eliminations not at
         their initial offsets.  Similarly if any arm of the IF_THEN_ELSE
         isn't one of those possibilities.  For branches to a label,
         call ourselves recursively.

         Note that this can disable elimination unnecessarily when we have
         a non-local goto since it will look like a non-constant jump to
         someplace in the current function.  This isn't a significant
         problem since such jumps will normally be when all elimination
         pairs are back to their initial offsets.  */

      if (SET_DEST (x) != pc_rtx)
        return;

      switch (GET_CODE (SET_SRC (x)))
        {
        case PC:
        case RETURN:
          return;

        case LABEL_REF:
          set_label_offsets (SET_SRC (x), insn, initial_p);
          return;

        case IF_THEN_ELSE:
          tem = XEXP (SET_SRC (x), 1);
          if (GET_CODE (tem) == LABEL_REF)
            set_label_offsets (XEXP (tem, 0), insn, initial_p);
          else if (GET_CODE (tem) != PC && GET_CODE (tem) != RETURN)
            break;

          tem = XEXP (SET_SRC (x), 2);
          if (GET_CODE (tem) == LABEL_REF)
            set_label_offsets (XEXP (tem, 0), insn, initial_p);
          else if (GET_CODE (tem) != PC && GET_CODE (tem) != RETURN)
            break;
          return;

        default:
          break;
        }

      /* If we reach here, all eliminations must be at their initial
         offset because we are doing a jump to a variable address.  */
      for (p = reg_eliminate; p < &reg_eliminate[NUM_ELIMINABLE_REGS]; p++)
        if (p->offset != p->initial_offset)
          p->can_eliminate = 0;
      break;

    default:
      break;
    }
}
\f
/* Called through for_each_rtx, this function examines every reg that occurs
   in PX and adjusts the costs for its elimination which are gathered by IRA.
   DATA is the insn in which PX occurs.  We do not recurse into MEM
   expressions.  */

static int
note_reg_elim_costly (rtx *px, void *data)
{
  rtx insn = (rtx)data;
  rtx x = *px;

  if (MEM_P (x))
    return -1;

  if (REG_P (x)
      && REGNO (x) >= FIRST_PSEUDO_REGISTER
      && reg_equiv_init[REGNO (x)]
      && reg_equiv_invariant[REGNO (x)])
    {
      rtx t = reg_equiv_invariant[REGNO (x)];
      rtx new_rtx = eliminate_regs_1 (t, Pmode, insn, true, true);
      int cost = rtx_cost (new_rtx, SET, optimize_bb_for_speed_p (elim_bb));
      int freq = REG_FREQ_FROM_BB (elim_bb);

      if (cost != 0)
        ira_adjust_equiv_reg_cost (REGNO (x), -cost * freq);
    }
  return 0;
}

/* Scan X and replace any eliminable registers (such as fp) with a
   replacement (such as sp), plus an offset.

   MEM_MODE is the mode of an enclosing MEM.  We need this to know how
   much to adjust a register for, e.g., PRE_DEC.  Also, if we are inside a
   MEM, we are allowed to replace a sum of a register and the constant zero
   with the register, which we cannot do outside a MEM.  In addition, we need
   to record the fact that a register is referenced outside a MEM.

   If INSN is an insn, it is the insn containing X.  If we replace a REG
   in a SET_DEST with an equivalent MEM and INSN is nonzero, write a
   CLOBBER of the pseudo after INSN so find_equiv_regs will know that
   the REG is being modified.

   Alternatively, INSN may be a note (an EXPR_LIST or INSN_LIST).
   That's used when we eliminate in expressions stored in notes.
   This means, do not set ref_outside_mem even if the reference
   is outside of MEMs.

   If FOR_COSTS is true, we are being called before reload in order to
   estimate the costs of keeping registers with an equivalence unallocated.

   REG_EQUIV_MEM and REG_EQUIV_ADDRESS contain address that have had
   replacements done assuming all offsets are at their initial values.  If
   they are not, or if REG_EQUIV_ADDRESS is nonzero for a pseudo we
   encounter, return the actual location so that find_reloads will do
   the proper thing.  */

static rtx
eliminate_regs_1 (rtx x, enum machine_mode mem_mode, rtx insn,
                  bool may_use_invariant, bool for_costs)
{
  enum rtx_code code = GET_CODE (x);
  struct elim_table *ep;
  int regno;
  rtx new_rtx;
  int i, j;
  const char *fmt;
  int copied = 0;

  if (! current_function_decl)
    return x;

  switch (code)
    {
    case CONST_INT:
    case CONST_DOUBLE:
    case CONST_FIXED:
    case CONST_VECTOR:
    case CONST:
    case SYMBOL_REF:
    case CODE_LABEL:
    case PC:
    case CC0:
    case ASM_INPUT:
    case ADDR_VEC:
    case ADDR_DIFF_VEC:
    case RETURN:
      return x;

    case REG:
      regno = REGNO (x);

      /* First handle the case where we encounter a bare register that
         is eliminable.  Replace it with a PLUS.  */
      if (regno < FIRST_PSEUDO_REGISTER)
        {
          for (ep = reg_eliminate; ep < &reg_eliminate[NUM_ELIMINABLE_REGS];
               ep++)
            if (ep->from_rtx == x && ep->can_eliminate)
              return plus_constant (ep->to_rtx, ep->previous_offset);

        }
      else if (reg_renumber && reg_renumber[regno] < 0
               && reg_equiv_invariant && reg_equiv_invariant[regno])
        {
          if (may_use_invariant || (insn && DEBUG_INSN_P (insn)))
            return eliminate_regs_1 (copy_rtx (reg_equiv_invariant[regno]),
                                     mem_mode, insn, true, for_costs);
          /* There exists at least one use of REGNO that cannot be
             eliminated.  Prevent the defining insn from being deleted.  */
          reg_equiv_init[regno] = NULL_RTX;
          if (!for_costs)
            alter_reg (regno, -1, true);
        }
      return x;

    /* You might think handling MINUS in a manner similar to PLUS is a
       good idea.  It is not.  It has been tried multiple times and every
       time the change has had to have been reverted.

       Other parts of reload know a PLUS is special (gen_reload for example)
       and require special code to handle code a reloaded PLUS operand.

       Also consider backends where the flags register is clobbered by a
       MINUS, but we can emit a PLUS that does not clobber flags (IA-32,
       lea instruction comes to mind).  If we try to reload a MINUS, we
       may kill the flags register that was holding a useful value.

       So, please before trying to handle MINUS, consider reload as a
       whole instead of this little section as well as the backend issues.  */
    case PLUS:
      /* If this is the sum of an eliminable register and a constant, rework
         the sum.  */
      if (REG_P (XEXP (x, 0))
          && REGNO (XEXP (x, 0)) < FIRST_PSEUDO_REGISTER
          && CONSTANT_P (XEXP (x, 1)))
        {
          for (ep = reg_eliminate; ep < &reg_eliminate[NUM_ELIMINABLE_REGS];
               ep++)
            if (ep->from_rtx == XEXP (x, 0) && ep->can_eliminate)
              {
                /* The only time we want to replace a PLUS with a REG (this
                   occurs when the constant operand of the PLUS is the negative
                   of the offset) is when we are inside a MEM.  We won't want
                   to do so at other times because that would change the
                   structure of the insn in a way that reload can't handle.
                   We special-case the commonest situation in
                   eliminate_regs_in_insn, so just replace a PLUS with a
                   PLUS here, unless inside a MEM.  */
                if (mem_mode != 0 && CONST_INT_P (XEXP (x, 1))
                    && INTVAL (XEXP (x, 1)) == - ep->previous_offset)
                  return ep->to_rtx;
                else
                  return gen_rtx_PLUS (Pmode, ep->to_rtx,
                                       plus_constant (XEXP (x, 1),
                                                      ep->previous_offset));
              }

          /* If the register is not eliminable, we are done since the other
             operand is a constant.  */
          return x;
        }

      /* If this is part of an address, we want to bring any constant to the
         outermost PLUS.  We will do this by doing register replacement in
         our operands and seeing if a constant shows up in one of them.

         Note that there is no risk of modifying the structure of the insn,
         since we only get called for its operands, thus we are either
         modifying the address inside a MEM, or something like an address
         operand of a load-address insn.  */

      {
        rtx new0 = eliminate_regs_1 (XEXP (x, 0), mem_mode, insn, true,
                                     for_costs);
        rtx new1 = eliminate_regs_1 (XEXP (x, 1), mem_mode, insn, true,
                                     for_costs);

        if (reg_renumber && (new0 != XEXP (x, 0) || new1 != XEXP (x, 1)))
          {
            /* If one side is a PLUS and the other side is a pseudo that
               didn't get a hard register but has a reg_equiv_constant,
               we must replace the constant here since it may no longer
               be in the position of any operand.  */
            if (GET_CODE (new0) == PLUS && REG_P (new1)
                && REGNO (new1) >= FIRST_PSEUDO_REGISTER
                && reg_renumber[REGNO (new1)] < 0
                && reg_equiv_constant != 0
                && reg_equiv_constant[REGNO (new1)] != 0)
              new1 = reg_equiv_constant[REGNO (new1)];
            else if (GET_CODE (new1) == PLUS && REG_P (new0)
                     && REGNO (new0) >= FIRST_PSEUDO_REGISTER
                     && reg_renumber[REGNO (new0)] < 0
                     && reg_equiv_constant[REGNO (new0)] != 0)
              new0 = reg_equiv_constant[REGNO (new0)];

            new_rtx = form_sum (GET_MODE (x), new0, new1);

            /* As above, if we are not inside a MEM we do not want to
               turn a PLUS into something else.  We might try to do so here
               for an addition of 0 if we aren't optimizing.  */
            if (! mem_mode && GET_CODE (new_rtx) != PLUS)
              return gen_rtx_PLUS (GET_MODE (x), new_rtx, const0_rtx);
            else
              return new_rtx;
          }
      }
      return x;

    case MULT:
      /* If this is the product of an eliminable register and a
         constant, apply the distribute law and move the constant out
         so that we have (plus (mult ..) ..).  This is needed in order
         to keep load-address insns valid.   This case is pathological.
         We ignore the possibility of overflow here.  */
      if (REG_P (XEXP (x, 0))
          && REGNO (XEXP (x, 0)) < FIRST_PSEUDO_REGISTER
          && CONST_INT_P (XEXP (x, 1)))
        for (ep = reg_eliminate; ep < &reg_eliminate[NUM_ELIMINABLE_REGS];
             ep++)
          if (ep->from_rtx == XEXP (x, 0) && ep->can_eliminate)
            {
              if (! mem_mode
                  /* Refs inside notes or in DEBUG_INSNs don't count for
                     this purpose.  */
                  && ! (insn != 0 && (GET_CODE (insn) == EXPR_LIST
                                      || GET_CODE (insn) == INSN_LIST
                                      || DEBUG_INSN_P (insn))))
                ep->ref_outside_mem = 1;

              return
                plus_constant (gen_rtx_MULT (Pmode, ep->to_rtx, XEXP (x, 1)),
                               ep->previous_offset * INTVAL (XEXP (x, 1)));
            }

      /* ... fall through ...  */

    case CALL:
    case COMPARE:
    /* See comments before PLUS about handling MINUS.  */
    case MINUS:
    case DIV:      case UDIV:
    case MOD:      case UMOD:
    case AND:      case IOR:      case XOR:
    case ROTATERT: case ROTATE:
    case ASHIFTRT: case LSHIFTRT: case ASHIFT:
    case NE:       case EQ:
    case GE:       case GT:       case GEU:    case GTU:
    case LE:       case LT:       case LEU:    case LTU:
      {
        rtx new0 = eliminate_regs_1 (XEXP (x, 0), mem_mode, insn, false,
                                     for_costs);
        rtx new1 = XEXP (x, 1)
          ? eliminate_regs_1 (XEXP (x, 1), mem_mode, insn, false,
                              for_costs) : 0;

        if (new0 != XEXP (x, 0) || new1 != XEXP (x, 1))
          return gen_rtx_fmt_ee (code, GET_MODE (x), new0, new1);
      }
      return x;

    case EXPR_LIST:
      /* If we have something in XEXP (x, 0), the usual case, eliminate it.  */
      if (XEXP (x, 0))
        {
          new_rtx = eliminate_regs_1 (XEXP (x, 0), mem_mode, insn, true,
                                      for_costs);
          if (new_rtx != XEXP (x, 0))
            {
              /* If this is a REG_DEAD note, it is not valid anymore.
                 Using the eliminated version could result in creating a
                 REG_DEAD note for the stack or frame pointer.  */
              if (REG_NOTE_KIND (x) == REG_DEAD)
                return (XEXP (x, 1)
                        ? eliminate_regs_1 (XEXP (x, 1), mem_mode, insn, true,
                                            for_costs)
                        : NULL_RTX);

              x = alloc_reg_note (REG_NOTE_KIND (x), new_rtx, XEXP (x, 1));
            }
        }

      /* ... fall through ...  */

    case INSN_LIST:
      /* Now do eliminations in the rest of the chain.  If this was
         an EXPR_LIST, this might result in allocating more memory than is
         strictly needed, but it simplifies the code.  */
      if (XEXP (x, 1))
        {
          new_rtx = eliminate_regs_1 (XEXP (x, 1), mem_mode, insn, true,
                                      for_costs);
          if (new_rtx != XEXP (x, 1))
            return
              gen_rtx_fmt_ee (GET_CODE (x), GET_MODE (x), XEXP (x, 0), new_rtx);
        }
      return x;

    case PRE_INC:
    case POST_INC:
    case PRE_DEC:
    case POST_DEC:
      /* We do not support elimination of a register that is modified.
         elimination_effects has already make sure that this does not
         happen.  */
      return x;

    case PRE_MODIFY:
    case POST_MODIFY:
      /* We do not support elimination of a register that is modified.
         elimination_effects has already make sure that this does not
         happen.  The only remaining case we need to consider here is
         that the increment value may be an eliminable register.  */
      if (GET_CODE (XEXP (x, 1)) == PLUS
          && XEXP (XEXP (x, 1), 0) == XEXP (x, 0))
        {
          rtx new_rtx = eliminate_regs_1 (XEXP (XEXP (x, 1), 1), mem_mode,
                                          insn, true, for_costs);

          if (new_rtx != XEXP (XEXP (x, 1), 1))
            return gen_rtx_fmt_ee (code, GET_MODE (x), XEXP (x, 0),
                                   gen_rtx_PLUS (GET_MODE (x),
                                                 XEXP (x, 0), new_rtx));
        }
      return x;

    case STRICT_LOW_PART:
    case NEG:          case NOT:
    case SIGN_EXTEND:  case ZERO_EXTEND:
    case TRUNCATE:     case FLOAT_EXTEND: case FLOAT_TRUNCATE:
    case FLOAT:        case FIX:
    case UNSIGNED_FIX: case UNSIGNED_FLOAT:
    case ABS:
    case SQRT:
    case FFS:
    case CLZ:
    case CTZ:
    case POPCOUNT:
    case PARITY:
    case BSWAP:
      new_rtx = eliminate_regs_1 (XEXP (x, 0), mem_mode, insn, false,
                                  for_costs);
      if (new_rtx != XEXP (x, 0))
        return gen_rtx_fmt_e (code, GET_MODE (x), new_rtx);
      return x;

    case SUBREG:
      /* Similar to above processing, but preserve SUBREG_BYTE.
         Convert (subreg (mem)) to (mem) if not paradoxical.
         Also, if we have a non-paradoxical (subreg (pseudo)) and the
         pseudo didn't get a hard reg, we must replace this with the
         eliminated version of the memory location because push_reload
         may do the replacement in certain circumstances.  */
      if (REG_P (SUBREG_REG (x))
          && (GET_MODE_SIZE (GET_MODE (x))
              <= GET_MODE_SIZE (GET_MODE (SUBREG_REG (x))))
          && reg_equiv_memory_loc != 0
          && reg_equiv_memory_loc[REGNO (SUBREG_REG (x))] != 0)
        {
          new_rtx = SUBREG_REG (x);
        }
      else
        new_rtx = eliminate_regs_1 (SUBREG_REG (x), mem_mode, insn, false,
                                    for_costs);

      if (new_rtx != SUBREG_REG (x))
        {
          int x_size = GET_MODE_SIZE (GET_MODE (x));
          int new_size = GET_MODE_SIZE (GET_MODE (new_rtx));

          if (MEM_P (new_rtx)
              && ((x_size < new_size
#ifdef WORD_REGISTER_OPERATIONS
                   /* On these machines, combine can create rtl of the form
                      (set (subreg:m1 (reg:m2 R) 0) ...)
                      where m1 < m2, and expects something interesting to
                      happen to the entire word.  Moreover, it will use the
                      (reg:m2 R) later, expecting all bits to be preserved.
                      So if the number of words is the same, preserve the
                      subreg so that push_reload can see it.  */
                   && ! ((x_size - 1) / UNITS_PER_WORD
                         == (new_size -1 ) / UNITS_PER_WORD)
#endif
                   )
                  || x_size == new_size)
              )
            return adjust_address_nv (new_rtx, GET_MODE (x), SUBREG_BYTE (x));
          else
            return gen_rtx_SUBREG (GET_MODE (x), new_rtx, SUBREG_BYTE (x));
        }

      return x;

    case MEM:
      /* Our only special processing is to pass the mode of the MEM to our
         recursive call and copy the flags.  While we are here, handle this
         case more efficiently.  */

      new_rtx = eliminate_regs_1 (XEXP (x, 0), GET_MODE (x), insn, true,
                                  for_costs);
      if (for_costs
          && memory_address_p (GET_MODE (x), XEXP (x, 0))
          && !memory_address_p (GET_MODE (x), new_rtx))
        for_each_rtx (&XEXP (x, 0), note_reg_elim_costly, insn);

      return replace_equiv_address_nv (x, new_rtx);

    case USE:
      /* Handle insn_list USE that a call to a pure function may generate.  */
      new_rtx = eliminate_regs_1 (XEXP (x, 0), VOIDmode, insn, false,
                                  for_costs);
      if (new_rtx != XEXP (x, 0))
        return gen_rtx_USE (GET_MODE (x), new_rtx);
      return x;

    case CLOBBER:
    case ASM_OPERANDS:
      gcc_assert (insn && DEBUG_INSN_P (insn));
      break;

    case SET:
      gcc_unreachable ();

    default:
      break;
    }

  /* Process each of our operands recursively.  If any have changed, make a
     copy of the rtx.  */
  fmt = GET_RTX_FORMAT (code);
  for (i = 0; i < GET_RTX_LENGTH (code); i++, fmt++)
    {
      if (*fmt == 'e')
        {
          new_rtx = eliminate_regs_1 (XEXP (x, i), mem_mode, insn, false,
                                      for_costs);
          if (new_rtx != XEXP (x, i) && ! copied)
            {
              x = shallow_copy_rtx (x);
              copied = 1;
            }
          XEXP (x, i) = new_rtx;
        }
      else if (*fmt == 'E')
        {
          int copied_vec = 0;
          for (j = 0; j < XVECLEN (x, i); j++)
            {
              new_rtx = eliminate_regs_1 (XVECEXP (x, i, j), mem_mode, insn, false,
                                          for_costs);
              if (new_rtx != XVECEXP (x, i, j) && ! copied_vec)
                {
                  rtvec new_v = gen_rtvec_v (XVECLEN (x, i),
                                             XVEC (x, i)->elem);
                  if (! copied)
                    {
                      x = shallow_copy_rtx (x);
                      copied = 1;
                    }
                  XVEC (x, i) = new_v;
                  copied_vec = 1;
                }
              XVECEXP (x, i, j) = new_rtx;
            }
        }
    }

  return x;
}

rtx
eliminate_regs (rtx x, enum machine_mode mem_mode, rtx insn)
{
  return eliminate_regs_1 (x, mem_mode, insn, false, false);
}

/* Scan rtx X for modifications of elimination target registers.  Update
   the table of eliminables to reflect the changed state.  MEM_MODE is
   the mode of an enclosing MEM rtx, or VOIDmode if not within a MEM.  */

static void
elimination_effects (rtx x, enum machine_mode mem_mode)
{
  enum rtx_code code = GET_CODE (x);
  struct elim_table *ep;
  int regno;
  int i, j;
  const char *fmt;

  switch (code)
    {
    case CONST_INT:
    case CONST_DOUBLE:
    case CONST_FIXED:
    case CONST_VECTOR:
    case CONST:
    case SYMBOL_REF:
    case CODE_LABEL:
    case PC:
    case CC0:
    case ASM_INPUT:
    case ADDR_VEC:
    case ADDR_DIFF_VEC:
    case RETURN:
      return;

    case REG:
      regno = REGNO (x);

      /* First handle the case where we encounter a bare register that
         is eliminable.  Replace it with a PLUS.  */
      if (regno < FIRST_PSEUDO_REGISTER)
        {
          for (ep = reg_eliminate; ep < &reg_eliminate[NUM_ELIMINABLE_REGS];
               ep++)
            if (ep->from_rtx == x && ep->can_eliminate)
              {
                if (! mem_mode)
                  ep->ref_outside_mem = 1;
                return;
              }

        }
      else if (reg_renumber[regno] < 0 && reg_equiv_constant
               && reg_equiv_constant[regno]
               && ! function_invariant_p (reg_equiv_constant[regno]))
        elimination_effects (reg_equiv_constant[regno], mem_mode);
      return;

    case PRE_INC:
    case POST_INC:
    case PRE_DEC:
    case POST_DEC:
    case POST_MODIFY:
    case PRE_MODIFY:
      /* If we modify the source of an elimination rule, disable it.  */
      for (ep = reg_eliminate; ep < &reg_eliminate[NUM_ELIMINABLE_REGS]; ep++)
        if (ep->from_rtx == XEXP (x, 0))
          ep->can_eliminate = 0;

      /* If we modify the target of an elimination rule by adding a constant,
         update its offset.  If we modify the target in any other way, we'll
         have to disable the rule as well.  */
      for (ep = reg_eliminate; ep < &reg_eliminate[NUM_ELIMINABLE_REGS]; ep++)
        if (ep->to_rtx == XEXP (x, 0))
          {
            int size = GET_MODE_SIZE (mem_mode);

            /* If more bytes than MEM_MODE are pushed, account for them.  */
#ifdef PUSH_ROUNDING
            if (ep->to_rtx == stack_pointer_rtx)
              size = PUSH_ROUNDING (size);
#endif
            if (code == PRE_DEC || code == POST_DEC)
              ep->offset += size;
            else if (code == PRE_INC || code == POST_INC)
              ep->offset -= size;
            else if (code == PRE_MODIFY || code == POST_MODIFY)
              {
                if (GET_CODE (XEXP (x, 1)) == PLUS
                    && XEXP (x, 0) == XEXP (XEXP (x, 1), 0)
                    && CONST_INT_P (XEXP (XEXP (x, 1), 1)))
                  ep->offset -= INTVAL (XEXP (XEXP (x, 1), 1));
                else
                  ep->can_eliminate = 0;
              }
          }

      /* These two aren't unary operators.  */
      if (code == POST_MODIFY || code == PRE_MODIFY)
        break;

      /* Fall through to generic unary operation case.  */
    case STRICT_LOW_PART:
    case NEG:          case NOT:
    case SIGN_EXTEND:  case ZERO_EXTEND:
    case TRUNCATE:     case FLOAT_EXTEND: case FLOAT_TRUNCATE:
    case FLOAT:        case FIX:
    case UNSIGNED_FIX: case UNSIGNED_FLOAT:
    case ABS:
    case SQRT:
    case FFS:
    case CLZ:
    case CTZ:
    case POPCOUNT:
    case PARITY:
    case BSWAP:
      elimination_effects (XEXP (x, 0), mem_mode);
      return;

    case SUBREG:
      if (REG_P (SUBREG_REG (x))
          && (GET_MODE_SIZE (GET_MODE (x))
              <= GET_MODE_SIZE (GET_MODE (SUBREG_REG (x))))
          && reg_equiv_memory_loc != 0
          && reg_equiv_memory_loc[REGNO (SUBREG_REG (x))] != 0)
        return;

      elimination_effects (SUBREG_REG (x), mem_mode);
      return;

    case USE:
      /* If using a register that is the source of an eliminate we still
         think can be performed, note it cannot be performed since we don't
         know how this register is used.  */
      for (ep = reg_eliminate; ep < &reg_eliminate[NUM_ELIMINABLE_REGS]; ep++)
        if (ep->from_rtx == XEXP (x, 0))
          ep->can_eliminate = 0;

      elimination_effects (XEXP (x, 0), mem_mode);
      return;

    case CLOBBER:
      /* If clobbering a register that is the replacement register for an
         elimination we still think can be performed, note that it cannot
         be performed.  Otherwise, we need not be concerned about it.  */
      for (ep = reg_eliminate; ep < &reg_eliminate[NUM_ELIMINABLE_REGS]; ep++)
        if (ep->to_rtx == XEXP (x, 0))
          ep->can_eliminate = 0;

      elimination_effects (XEXP (x, 0), mem_mode);
      return;

    case SET:
      /* Check for setting a register that we know about.  */
      if (REG_P (SET_DEST (x)))
        {
          /* See if this is setting the replacement register for an
             elimination.

             If DEST is the hard frame pointer, we do nothing because we
             assume that all assignments to the frame pointer are for
             non-local gotos and are being done at a time when they are valid
             and do not disturb anything else.  Some machines want to
             eliminate a fake argument pointer (or even a fake frame pointer)
             with either the real frame or the stack pointer.  Assignments to
             the hard frame pointer must not prevent this elimination.  */

          for (ep = reg_eliminate; ep < &reg_eliminate[NUM_ELIMINABLE_REGS];
               ep++)
            if (ep->to_rtx == SET_DEST (x)
                && SET_DEST (x) != hard_frame_pointer_rtx)
              {
                /* If it is being incremented, adjust the offset.  Otherwise,
                   this elimination can't be done.  */
                rtx src = SET_SRC (x);

                if (GET_CODE (src) == PLUS
                    && XEXP (src, 0) == SET_DEST (x)
                    && CONST_INT_P (XEXP (src, 1)))
                  ep->offset -= INTVAL (XEXP (src, 1));
                else
                  ep->can_eliminate = 0;
              }
        }

      elimination_effects (SET_DEST (x), VOIDmode);
      elimination_effects (SET_SRC (x), VOIDmode);
      return;

    case MEM:
      /* Our only special processing is to pass the mode of the MEM to our
         recursive call.  */
      elimination_effects (XEXP (x, 0), GET_MODE (x));
      return;

    default:
      break;
    }

  fmt = GET_RTX_FORMAT (code);
  for (i = 0; i < GET_RTX_LENGTH (code); i++, fmt++)
    {
      if (*fmt == 'e')
        elimination_effects (XEXP (x, i), mem_mode);
      else if (*fmt == 'E')
        for (j = 0; j < XVECLEN (x, i); j++)
          elimination_effects (XVECEXP (x, i, j), mem_mode);
    }
}

/* Descend through rtx X and verify that no references to eliminable registers
   remain.  If any do remain, mark the involved register as not
   eliminable.  */

static void
check_eliminable_occurrences (rtx x)
{
  const char *fmt;
  int i;
  enum rtx_code code;

  if (x == 0)
    return;

  code = GET_CODE (x);

  if (code == REG && REGNO (x) < FIRST_PSEUDO_REGISTER)
    {
      struct elim_table *ep;

      for (ep = reg_eliminate; ep < &reg_eliminate[NUM_ELIMINABLE_REGS]; ep++)
        if (ep->from_rtx == x)
          ep->can_eliminate = 0;
      return;
    }

  fmt = GET_RTX_FORMAT (code);
  for (i = 0; i < GET_RTX_LENGTH (code); i++, fmt++)
    {
      if (*fmt == 'e')
        check_eliminable_occurrences (XEXP (x, i));
      else if (*fmt == 'E')
        {
          int j;
          for (j = 0; j < XVECLEN (x, i); j++)
            check_eliminable_occurrences (XVECEXP (x, i, j));
        }
    }
}
\f
/* Scan INSN and eliminate all eliminable registers in it.

   If REPLACE is nonzero, do the replacement destructively.  Also
   delete the insn as dead it if it is setting an eliminable register.

   If REPLACE is zero, do all our allocations in reload_obstack.

   If no eliminations were done and this insn doesn't require any elimination
   processing (these are not identical conditions: it might be updating sp,
   but not referencing fp; this needs to be seen during reload_as_needed so
   that the offset between fp and sp can be taken into consideration), zero
   is returned.  Otherwise, 1 is returned.  */

static int
eliminate_regs_in_insn (rtx insn, int replace)
{
  int icode = recog_memoized (insn);
  rtx old_body = PATTERN (insn);
  int insn_is_asm = asm_noperands (old_body) >= 0;
  rtx old_set = single_set (insn);
  rtx new_body;
  int val = 0;
  int i;
  rtx substed_operand[MAX_RECOG_OPERANDS];
  rtx orig_operand[MAX_RECOG_OPERANDS];
  struct elim_table *ep;
  rtx plus_src, plus_cst_src;

  if (! insn_is_asm && icode < 0)
    {
      gcc_assert (GET_CODE (PATTERN (insn)) == USE
                  || GET_CODE (PATTERN (insn)) == CLOBBER
                  || GET_CODE (PATTERN (insn)) == ADDR_VEC
                  || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC
                  || GET_CODE (PATTERN (insn)) == ASM_INPUT
                  || DEBUG_INSN_P (insn));
      if (DEBUG_INSN_P (insn))
        INSN_VAR_LOCATION_LOC (insn)
          = eliminate_regs (INSN_VAR_LOCATION_LOC (insn), VOIDmode, insn);
      return 0;
    }

  if (old_set != 0 && REG_P (SET_DEST (old_set))
      && REGNO (SET_DEST (old_set)) < FIRST_PSEUDO_REGISTER)
    {
      /* Check for setting an eliminable register.  */
      for (ep = reg_eliminate; ep < &reg_eliminate[NUM_ELIMINABLE_REGS]; ep++)
        if (ep->from_rtx == SET_DEST (old_set) && ep->can_eliminate)
          {
#if !HARD_FRAME_POINTER_IS_FRAME_POINTER
            /* If this is setting the frame pointer register to the
               hardware frame pointer register and this is an elimination
               that will be done (tested above), this insn is really
               adjusting the frame pointer downward to compensate for
               the adjustment done before a nonlocal goto.  */
            if (ep->from == FRAME_POINTER_REGNUM
                && ep->to == HARD_FRAME_POINTER_REGNUM)
              {
                rtx base = SET_SRC (old_set);
                rtx base_insn = insn;
                HOST_WIDE_INT offset = 0;

                while (base != ep->to_rtx)
                  {
                    rtx prev_insn, prev_set;

                    if (GET_CODE (base) == PLUS
                        && CONST_INT_P (XEXP (base, 1)))
                      {
                        offset += INTVAL (XEXP (base, 1));
                        base = XEXP (base, 0);
                      }
                    else if ((prev_insn = prev_nonnote_insn (base_insn)) != 0
                             && (prev_set = single_set (prev_insn)) != 0
                             && rtx_equal_p (SET_DEST (prev_set), base))
                      {
                        base = SET_SRC (prev_set);
                        base_insn = prev_insn;
                      }
                    else
                      break;
                  }

                if (base == ep->to_rtx)
                  {
                    rtx src
                      = plus_constant (ep->to_rtx, offset - ep->offset);

                    new_body = old_body;
                    if (! replace)
                      {
                        new_body = copy_insn (old_body);
                        if (REG_NOTES (insn))
                          REG_NOTES (insn) = copy_insn_1 (REG_NOTES (insn));
                      }
                    PATTERN (insn) = new_body;
                    old_set = single_set (insn);

                    /* First see if this insn remains valid when we
                       make the change.  If not, keep the INSN_CODE
                       the same and let reload fit it up.  */
                    validate_change (insn, &SET_SRC (old_set), src, 1);
                    validate_change (insn, &SET_DEST (old_set),
                                     ep->to_rtx, 1);
                    if (! apply_change_group ())
                      {
                        SET_SRC (old_set) = src;
                        SET_DEST (old_set) = ep->to_rtx;
                      }

                    val = 1;
                    goto done;
                  }
              }
#endif

            /* In this case this insn isn't serving a useful purpose.  We
               will delete it in reload_as_needed once we know that this
               elimination is, in fact, being done.

               If REPLACE isn't set, we can't delete this insn, but needn't
               process it since it won't be used unless something changes.  */
            if (replace)
              {
                delete_dead_insn (insn);
                return 1;
              }
            val = 1;
            goto done;
          }
    }

  /* We allow one special case which happens to work on all machines we
     currently support: a single set with the source or a REG_EQUAL
     note being a PLUS of an eliminable register and a constant.  */
  plus_src = plus_cst_src = 0;
  if (old_set && REG_P (SET_DEST (old_set)))
    {
      if (GET_CODE (SET_SRC (old_set)) == PLUS)
        plus_src = SET_SRC (old_set);
      /* First see if the source is of the form (plus (...) CST).  */
      if (plus_src
          && CONST_INT_P (XEXP (plus_src, 1)))
        plus_cst_src = plus_src;
      else if (REG_P (SET_SRC (old_set))
               || plus_src)
        {
          /* Otherwise, see if we have a REG_EQUAL note of the form
             (plus (...) CST).  */
          rtx links;
          for (links = REG_NOTES (insn); links; links = XEXP (links, 1))
            {
              if ((REG_NOTE_KIND (links) == REG_EQUAL
                   || REG_NOTE_KIND (links) == REG_EQUIV)
                  && GET_CODE (XEXP (links, 0)) == PLUS
                  && CONST_INT_P (XEXP (XEXP (links, 0), 1)))
                {
                  plus_cst_src = XEXP (links, 0);
                  break;
                }
            }
        }

      /* Check that the first operand of the PLUS is a hard reg or
         the lowpart subreg of one.  */
      if (plus_cst_src)
        {
          rtx reg = XEXP (plus_cst_src, 0);
          if (GET_CODE (reg) == SUBREG && subreg_lowpart_p (reg))
            reg = SUBREG_REG (reg);

          if (!REG_P (reg) || REGNO (reg) >= FIRST_PSEUDO_REGISTER)
            plus_cst_src = 0;
        }
    }
  if (plus_cst_src)
    {
      rtx reg = XEXP (plus_cst_src, 0);
      HOST_WIDE_INT offset = INTVAL (XEXP (plus_cst_src, 1));

      if (GET_CODE (reg) == SUBREG)
        reg = SUBREG_REG (reg);

      for (ep = reg_eliminate; ep < &reg_eliminate[NUM_ELIMINABLE_REGS]; ep++)
        if (ep->from_rtx == reg && ep->can_eliminate)
          {
            rtx to_rtx = ep->to_rtx;
            offset += ep->offset;
            offset = trunc_int_for_mode (offset, GET_MODE (plus_cst_src));

            if (GET_CODE (XEXP (plus_cst_src, 0)) == SUBREG)
              to_rtx = gen_lowpart (GET_MODE (XEXP (plus_cst_src, 0)),
                                    to_rtx);
            /* If we have a nonzero offset, and the source is already
               a simple REG, the following transformation would
               increase the cost of the insn by replacing a simple REG
               with (plus (reg sp) CST).  So try only when we already
               had a PLUS before.  */
            if (offset == 0 || plus_src)
              {
                rtx new_src = plus_constant (to_rtx, offset);

                new_body = old_body;
                if (! replace)
                  {
                    new_body = copy_insn (old_body);
                    if (REG_NOTES (insn))
                      REG_NOTES (insn) = copy_insn_1 (REG_NOTES (insn));
                  }
                PATTERN (insn) = new_body;
                old_set = single_set (insn);

                /* First see if this insn remains valid when we make the
                   change.  If not, try to replace the whole pattern with
                   a simple set (this may help if the original insn was a
                   PARALLEL that was only recognized as single_set due to
                   REG_UNUSED notes).  If this isn't valid either, keep
                   the INSN_CODE the same and let reload fix it up. &