gcc/emit-rtl.c

/* Emit RTL for the GCC expander.
   Copyright (C) 1987-2015 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/>.  */


/* Middle-to-low level generation of rtx code and insns.

   This file contains support functions for creating rtl expressions
   and manipulating them in the doubly-linked chain of insns.

   The patterns of the insns are created by machine-dependent
   routines in insn-emit.c, which is generated automatically from
   the machine description.  These routines make the individual rtx's
   of the pattern with `gen_rtx_fmt_ee' and others in genrtl.[ch],
   which are automatically generated from rtl.def; what is machine
   dependent is the kind of rtx's they make and what arguments they
   use.  */

#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "diagnostic-core.h"
#include "rtl.h"
#include "hash-set.h"
#include "machmode.h"
#include "vec.h"
#include "double-int.h"
#include "input.h"
#include "alias.h"
#include "symtab.h"
#include "wide-int.h"
#include "inchash.h"
#include "real.h"
#include "tree.h"
#include "fold-const.h"
#include "varasm.h"
#include "predict.h"
#include "hard-reg-set.h"
#include "function.h"
#include "cfgrtl.h"
#include "basic-block.h"
#include "tree-eh.h"
#include "tm_p.h"
#include "flags.h"
#include "stringpool.h"
#include "hashtab.h"
#include "statistics.h"
#include "fixed-value.h"
#include "insn-config.h"
#include "expmed.h"
#include "dojump.h"
#include "explow.h"
#include "calls.h"
#include "emit-rtl.h"
#include "stmt.h"
#include "expr.h"
#include "regs.h"
#include "recog.h"
#include "bitmap.h"
#include "debug.h"
#include "langhooks.h"
#include "df.h"
#include "params.h"
#include "target.h"
#include "builtins.h"
#include "rtl-iter.h"

struct target_rtl default_target_rtl;
#if SWITCHABLE_TARGET
struct target_rtl *this_target_rtl = &default_target_rtl;
#endif

#define initial_regno_reg_rtx (this_target_rtl->x_initial_regno_reg_rtx)

/* Commonly used modes.  */

machine_mode byte_mode;	/* Mode whose width is BITS_PER_UNIT.  */
machine_mode word_mode;	/* Mode whose width is BITS_PER_WORD.  */
machine_mode double_mode;	/* Mode whose width is DOUBLE_TYPE_SIZE.  */
machine_mode ptr_mode;	/* Mode whose width is POINTER_SIZE.  */

/* Datastructures maintained for currently processed function in RTL form.  */

struct rtl_data x_rtl;

/* Indexed by pseudo register number, gives the rtx for that pseudo.
   Allocated in parallel with regno_pointer_align.
   FIXME: We could put it into emit_status struct, but gengtype is not able to deal
   with length attribute nested in top level structures.  */

rtx * regno_reg_rtx;

/* This is *not* reset after each function.  It gives each CODE_LABEL
   in the entire compilation a unique label number.  */

static GTY(()) int label_num = 1;

/* We record floating-point CONST_DOUBLEs in each floating-point mode for
   the values of 0, 1, and 2.  For the integer entries and VOIDmode, we
   record a copy of const[012]_rtx and constm1_rtx.  CONSTM1_RTX
   is set only for MODE_INT and MODE_VECTOR_INT modes.  */

rtx const_tiny_rtx[4][(int) MAX_MACHINE_MODE];

rtx const_true_rtx;

REAL_VALUE_TYPE dconst0;
REAL_VALUE_TYPE dconst1;
REAL_VALUE_TYPE dconst2;
REAL_VALUE_TYPE dconstm1;
REAL_VALUE_TYPE dconsthalf;

/* Record fixed-point constant 0 and 1.  */
FIXED_VALUE_TYPE fconst0[MAX_FCONST0];
FIXED_VALUE_TYPE fconst1[MAX_FCONST1];

/* We make one copy of (const_int C) where C is in
   [- MAX_SAVED_CONST_INT, MAX_SAVED_CONST_INT]
   to save space during the compilation and simplify comparisons of
   integers.  */

rtx const_int_rtx[MAX_SAVED_CONST_INT * 2 + 1];

/* Standard pieces of rtx, to be substituted directly into things.  */
rtx pc_rtx;
rtx ret_rtx;
rtx simple_return_rtx;
rtx cc0_rtx;

/* A hash table storing CONST_INTs whose absolute value is greater
   than MAX_SAVED_CONST_INT.  */

struct const_int_hasher : ggc_cache_hasher<rtx>
{
  typedef HOST_WIDE_INT compare_type;

  static hashval_t hash (rtx i);
  static bool equal (rtx i, HOST_WIDE_INT h);
};

static GTY ((cache)) hash_table<const_int_hasher> *const_int_htab;

struct const_wide_int_hasher : ggc_cache_hasher<rtx>
{
  static hashval_t hash (rtx x);
  static bool equal (rtx x, rtx y);
};

static GTY ((cache)) hash_table<const_wide_int_hasher> *const_wide_int_htab;

/* A hash table storing register attribute structures.  */
struct reg_attr_hasher : ggc_cache_hasher<reg_attrs *>
{
  static hashval_t hash (reg_attrs *x);
  static bool equal (reg_attrs *a, reg_attrs *b);
};

static GTY ((cache)) hash_table<reg_attr_hasher> *reg_attrs_htab;

/* A hash table storing all CONST_DOUBLEs.  */
struct const_double_hasher : ggc_cache_hasher<rtx>
{
  static hashval_t hash (rtx x);
  static bool equal (rtx x, rtx y);
};

static GTY ((cache)) hash_table<const_double_hasher> *const_double_htab;

/* A hash table storing all CONST_FIXEDs.  */
struct const_fixed_hasher : ggc_cache_hasher<rtx>
{
  static hashval_t hash (rtx x);
  static bool equal (rtx x, rtx y);
};

static GTY ((cache)) hash_table<const_fixed_hasher> *const_fixed_htab;

#define cur_insn_uid (crtl->emit.x_cur_insn_uid)
#define cur_debug_insn_uid (crtl->emit.x_cur_debug_insn_uid)
#define first_label_num (crtl->emit.x_first_label_num)

static void set_used_decls (tree);
static void mark_label_nuses (rtx);
#if TARGET_SUPPORTS_WIDE_INT
static rtx lookup_const_wide_int (rtx);
#endif
static rtx lookup_const_double (rtx);
static rtx lookup_const_fixed (rtx);
static reg_attrs *get_reg_attrs (tree, int);
static rtx gen_const_vector (machine_mode, int);
static void copy_rtx_if_shared_1 (rtx *orig);

/* Probability of the conditional branch currently proceeded by try_split.
   Set to -1 otherwise.  */
int split_branch_probability = -1;

/* Returns a hash code for X (which is a really a CONST_INT).  */

hashval_t
const_int_hasher::hash (rtx x)
{
  return (hashval_t) INTVAL (x);
}

/* Returns nonzero if the value represented by X (which is really a
   CONST_INT) is the same as that given by Y (which is really a
   HOST_WIDE_INT *).  */

bool
const_int_hasher::equal (rtx x, HOST_WIDE_INT y)
{
  return (INTVAL (x) == y);
}

#if TARGET_SUPPORTS_WIDE_INT
/* Returns a hash code for X (which is a really a CONST_WIDE_INT).  */

hashval_t
const_wide_int_hasher::hash (rtx x)
{
  int i;
  unsigned HOST_WIDE_INT hash = 0;
  const_rtx xr = x;

  for (i = 0; i < CONST_WIDE_INT_NUNITS (xr); i++)
    hash += CONST_WIDE_INT_ELT (xr, i);

  return (hashval_t) hash;
}

/* Returns nonzero if the value represented by X (which is really a
   CONST_WIDE_INT) is the same as that given by Y (which is really a
   CONST_WIDE_INT).  */

bool
const_wide_int_hasher::equal (rtx x, rtx y)
{
  int i;
  const_rtx xr = x;
  const_rtx yr = y;
  if (CONST_WIDE_INT_NUNITS (xr) != CONST_WIDE_INT_NUNITS (yr))
    return false;

  for (i = 0; i < CONST_WIDE_INT_NUNITS (xr); i++)
    if (CONST_WIDE_INT_ELT (xr, i) != CONST_WIDE_INT_ELT (yr, i))
      return false;

  return true;
}
#endif

/* Returns a hash code for X (which is really a CONST_DOUBLE).  */
hashval_t
const_double_hasher::hash (rtx x)
{
  const_rtx const value = x;
  hashval_t h;

  if (TARGET_SUPPORTS_WIDE_INT == 0 && GET_MODE (value) == VOIDmode)
    h = CONST_DOUBLE_LOW (value) ^ CONST_DOUBLE_HIGH (value);
  else
    {
      h = real_hash (CONST_DOUBLE_REAL_VALUE (value));
      /* MODE is used in the comparison, so it should be in the hash.  */
      h ^= GET_MODE (value);
    }
  return h;
}

/* Returns nonzero if the value represented by X (really a ...)
   is the same as that represented by Y (really a ...) */
bool
const_double_hasher::equal (rtx x, rtx y)
{
  const_rtx const a = x, b = y;

  if (GET_MODE (a) != GET_MODE (b))
    return 0;
  if (TARGET_SUPPORTS_WIDE_INT == 0 && GET_MODE (a) == VOIDmode)
    return (CONST_DOUBLE_LOW (a) == CONST_DOUBLE_LOW (b)
	    && CONST_DOUBLE_HIGH (a) == CONST_DOUBLE_HIGH (b));
  else
    return real_identical (CONST_DOUBLE_REAL_VALUE (a),
			   CONST_DOUBLE_REAL_VALUE (b));
}

/* Returns a hash code for X (which is really a CONST_FIXED).  */

hashval_t
const_fixed_hasher::hash (rtx x)
{
  const_rtx const value = x;
  hashval_t h;

  h = fixed_hash (CONST_FIXED_VALUE (value));
  /* MODE is used in the comparison, so it should be in the hash.  */
  h ^= GET_MODE (value);
  return h;
}

/* Returns nonzero if the value represented by X is the same as that
   represented by Y.  */

bool
const_fixed_hasher::equal (rtx x, rtx y)
{
  const_rtx const a = x, b = y;

  if (GET_MODE (a) != GET_MODE (b))
    return 0;
  return fixed_identical (CONST_FIXED_VALUE (a), CONST_FIXED_VALUE (b));
}

/* Return true if the given memory attributes are equal.  */

bool
mem_attrs_eq_p (const struct mem_attrs *p, const struct mem_attrs *q)
{
  if (p == q)
    return true;
  if (!p || !q)
    return false;
  return (p->alias == q->alias
	  && p->offset_known_p == q->offset_known_p
	  && (!p->offset_known_p || p->offset == q->offset)
	  && p->size_known_p == q->size_known_p
	  && (!p->size_known_p || p->size == q->size)
	  && p->align == q->align
	  && p->addrspace == q->addrspace
	  && (p->expr == q->expr
	      || (p->expr != NULL_TREE && q->expr != NULL_TREE
		  && operand_equal_p (p->expr, q->expr, 0))));
}

/* Set MEM's memory attributes so that they are the same as ATTRS.  */

static void
set_mem_attrs (rtx mem, mem_attrs *attrs)
{
  /* If everything is the default, we can just clear the attributes.  */
  if (mem_attrs_eq_p (attrs, mode_mem_attrs[(int) GET_MODE (mem)]))
    {
      MEM_ATTRS (mem) = 0;
      return;
    }

  if (!MEM_ATTRS (mem)
      || !mem_attrs_eq_p (attrs, MEM_ATTRS (mem)))
    {
      MEM_ATTRS (mem) = ggc_alloc<mem_attrs> ();
      memcpy (MEM_ATTRS (mem), attrs, sizeof (mem_attrs));
    }
}

/* Returns a hash code for X (which is a really a reg_attrs *).  */

hashval_t
reg_attr_hasher::hash (reg_attrs *x)
{
  const reg_attrs *const p = x;

  return ((p->offset * 1000) ^ (intptr_t) p->decl);
}

/* Returns nonzero if the value represented by X  is the same as that given by
   Y.  */

bool
reg_attr_hasher::equal (reg_attrs *x, reg_attrs *y)
{
  const reg_attrs *const p = x;
  const reg_attrs *const q = y;

  return (p->decl == q->decl && p->offset == q->offset);
}
/* Allocate a new reg_attrs structure and insert it into the hash table if
   one identical to it is not already in the table.  We are doing this for
   MEM of mode MODE.  */

static reg_attrs *
get_reg_attrs (tree decl, int offset)
{
  reg_attrs attrs;

  /* If everything is the default, we can just return zero.  */
  if (decl == 0 && offset == 0)
    return 0;

  attrs.decl = decl;
  attrs.offset = offset;

  reg_attrs **slot = reg_attrs_htab->find_slot (&attrs, INSERT);
  if (*slot == 0)
    {
      *slot = ggc_alloc<reg_attrs> ();
      memcpy (*slot, &attrs, sizeof (reg_attrs));
    }

  return *slot;
}


#if !HAVE_blockage
/* Generate an empty ASM_INPUT, which is used to block attempts to schedule,
   and to block register equivalences to be seen across this insn.  */

rtx
gen_blockage (void)
{
  rtx x = gen_rtx_ASM_INPUT (VOIDmode, "");
  MEM_VOLATILE_P (x) = true;
  return x;
}
#endif


/* Generate a new REG rtx.  Make sure ORIGINAL_REGNO is set properly, and
   don't attempt to share with the various global pieces of rtl (such as
   frame_pointer_rtx).  */

rtx
gen_raw_REG (machine_mode mode, int regno)
{
  rtx x = gen_rtx_raw_REG (mode, regno);
  ORIGINAL_REGNO (x) = regno;
  return x;
}

/* There are some RTL codes that require special attention; the generation
   functions do the raw handling.  If you add to this list, modify
   special_rtx in gengenrtl.c as well.  */

rtx_expr_list *
gen_rtx_EXPR_LIST (machine_mode mode, rtx expr, rtx expr_list)
{
  return as_a <rtx_expr_list *> (gen_rtx_fmt_ee (EXPR_LIST, mode, expr,
						 expr_list));
}

rtx_insn_list *
gen_rtx_INSN_LIST (machine_mode mode, rtx insn, rtx insn_list)
{
  return as_a <rtx_insn_list *> (gen_rtx_fmt_ue (INSN_LIST, mode, insn,
						 insn_list));
}

rtx_insn *
gen_rtx_INSN (machine_mode mode, rtx_insn *prev_insn, rtx_insn *next_insn,
	      basic_block bb, rtx pattern, int location, int code,
	      rtx reg_notes)
{
  return as_a <rtx_insn *> (gen_rtx_fmt_uuBeiie (INSN, mode,
						 prev_insn, next_insn,
						 bb, pattern, location, code,
						 reg_notes));
}

rtx
gen_rtx_CONST_INT (machine_mode mode ATTRIBUTE_UNUSED, HOST_WIDE_INT arg)
{
  if (arg >= - MAX_SAVED_CONST_INT && arg <= MAX_SAVED_CONST_INT)
    return const_int_rtx[arg + MAX_SAVED_CONST_INT];

#if STORE_FLAG_VALUE != 1 && STORE_FLAG_VALUE != -1
  if (const_true_rtx && arg == STORE_FLAG_VALUE)
    return const_true_rtx;
#endif

  /* Look up the CONST_INT in the hash table.  */
  rtx *slot = const_int_htab->find_slot_with_hash (arg, (hashval_t) arg,
						   INSERT);
  if (*slot == 0)
    *slot = gen_rtx_raw_CONST_INT (VOIDmode, arg);

  return *slot;
}

rtx
gen_int_mode (HOST_WIDE_INT c, machine_mode mode)
{
  return GEN_INT (trunc_int_for_mode (c, mode));
}

/* CONST_DOUBLEs might be created from pairs of integers, or from
   REAL_VALUE_TYPEs.  Also, their length is known only at run time,
   so we cannot use gen_rtx_raw_CONST_DOUBLE.  */

/* Determine whether REAL, a CONST_DOUBLE, already exists in the
   hash table.  If so, return its counterpart; otherwise add it
   to the hash table and return it.  */
static rtx
lookup_const_double (rtx real)
{
  rtx *slot = const_double_htab->find_slot (real, INSERT);
  if (*slot == 0)
    *slot = real;

  return *slot;
}

/* Return a CONST_DOUBLE rtx for a floating-point value specified by
   VALUE in mode MODE.  */
rtx
const_double_from_real_value (REAL_VALUE_TYPE value, machine_mode mode)
{
  rtx real = rtx_alloc (CONST_DOUBLE);
  PUT_MODE (real, mode);

  real->u.rv = value;

  return lookup_const_double (real);
}

/* Determine whether FIXED, a CONST_FIXED, already exists in the
   hash table.  If so, return its counterpart; otherwise add it
   to the hash table and return it.  */

static rtx
lookup_const_fixed (rtx fixed)
{
  rtx *slot = const_fixed_htab->find_slot (fixed, INSERT);
  if (*slot == 0)
    *slot = fixed;

  return *slot;
}

/* Return a CONST_FIXED rtx for a fixed-point value specified by
   VALUE in mode MODE.  */

rtx
const_fixed_from_fixed_value (FIXED_VALUE_TYPE value, machine_mode mode)
{
  rtx fixed = rtx_alloc (CONST_FIXED);
  PUT_MODE (fixed, mode);

  fixed->u.fv = value;

  return lookup_const_fixed (fixed);
}

#if TARGET_SUPPORTS_WIDE_INT == 0
/* Constructs double_int from rtx CST.  */

double_int
rtx_to_double_int (const_rtx cst)
{
  double_int r;

  if (CONST_INT_P (cst))
      r = double_int::from_shwi (INTVAL (cst));
  else if (CONST_DOUBLE_AS_INT_P (cst))
    {
      r.low = CONST_DOUBLE_LOW (cst);
      r.high = CONST_DOUBLE_HIGH (cst);
    }
  else
    gcc_unreachable ();
  
  return r;
}
#endif

#if TARGET_SUPPORTS_WIDE_INT
/* Determine whether CONST_WIDE_INT WINT already exists in the hash table.
   If so, return its counterpart; otherwise add it to the hash table and
   return it.  */

static rtx
lookup_const_wide_int (rtx wint)
{
  rtx *slot = const_wide_int_htab->find_slot (wint, INSERT);
  if (*slot == 0)
    *slot = wint;

  return *slot;
}
#endif

/* Return an rtx constant for V, given that the constant has mode MODE.
   The returned rtx will be a CONST_INT if V fits, otherwise it will be
   a CONST_DOUBLE (if !TARGET_SUPPORTS_WIDE_INT) or a CONST_WIDE_INT
   (if TARGET_SUPPORTS_WIDE_INT).  */

rtx
immed_wide_int_const (const wide_int_ref &v, machine_mode mode)
{
  unsigned int len = v.get_len ();
  unsigned int prec = GET_MODE_PRECISION (mode);

  /* Allow truncation but not extension since we do not know if the
     number is signed or unsigned.  */
  gcc_assert (prec <= v.get_precision ());

  if (len < 2 || prec <= HOST_BITS_PER_WIDE_INT)
    return gen_int_mode (v.elt (0), mode);

#if TARGET_SUPPORTS_WIDE_INT
  {
    unsigned int i;
    rtx value;
    unsigned int blocks_needed
      = (prec + HOST_BITS_PER_WIDE_INT - 1) / HOST_BITS_PER_WIDE_INT;

    if (len > blocks_needed)
      len = blocks_needed;

    value = const_wide_int_alloc (len);

    /* It is so tempting to just put the mode in here.  Must control
       myself ... */
    PUT_MODE (value, VOIDmode);
    CWI_PUT_NUM_ELEM (value, len);

    for (i = 0; i < len; i++)
      CONST_WIDE_INT_ELT (value, i) = v.elt (i);

    return lookup_const_wide_int (value);
  }
#else
  return immed_double_const (v.elt (0), v.elt (1), mode);
#endif
}

#if TARGET_SUPPORTS_WIDE_INT == 0
/* Return a CONST_DOUBLE or CONST_INT for a value specified as a pair
   of ints: I0 is the low-order word and I1 is the high-order word.
   For values that are larger than HOST_BITS_PER_DOUBLE_INT, the
   implied upper bits are copies of the high bit of i1.  The value
   itself is neither signed nor unsigned.  Do not use this routine for
   non-integer modes; convert to REAL_VALUE_TYPE and use
   CONST_DOUBLE_FROM_REAL_VALUE.  */

rtx
immed_double_const (HOST_WIDE_INT i0, HOST_WIDE_INT i1, machine_mode mode)
{
  rtx value;
  unsigned int i;

  /* There are the following cases (note that there are no modes with
     HOST_BITS_PER_WIDE_INT < GET_MODE_BITSIZE (mode) < HOST_BITS_PER_DOUBLE_INT):

     1) If GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT, then we use
	gen_int_mode.
     2) If the value of the integer fits into HOST_WIDE_INT anyway
        (i.e., i1 consists only from copies of the sign bit, and sign
	of i0 and i1 are the same), then we return a CONST_INT for i0.
     3) Otherwise, we create a CONST_DOUBLE for i0 and i1.  */
  if (mode != VOIDmode)
    {
      gcc_assert (GET_MODE_CLASS (mode) == MODE_INT
		  || GET_MODE_CLASS (mode) == MODE_PARTIAL_INT
		  /* We can get a 0 for an error mark.  */
		  || GET_MODE_CLASS (mode) == MODE_VECTOR_INT
		  || GET_MODE_CLASS (mode) == MODE_VECTOR_FLOAT
		  || GET_MODE_CLASS (mode) == MODE_POINTER_BOUNDS);

      if (GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT)
	return gen_int_mode (i0, mode);
    }

  /* If this integer fits in one word, return a CONST_INT.  */
  if ((i1 == 0 && i0 >= 0) || (i1 == ~0 && i0 < 0))
    return GEN_INT (i0);

  /* We use VOIDmode for integers.  */
  value = rtx_alloc (CONST_DOUBLE);
  PUT_MODE (value, VOIDmode);

  CONST_DOUBLE_LOW (value) = i0;
  CONST_DOUBLE_HIGH (value) = i1;

  for (i = 2; i < (sizeof CONST_DOUBLE_FORMAT - 1); i++)
    XWINT (value, i) = 0;

  return lookup_const_double (value);
}
#endif

rtx
gen_rtx_REG (machine_mode mode, unsigned int regno)
{
  /* In case the MD file explicitly references the frame pointer, have
     all such references point to the same frame pointer.  This is
     used during frame pointer elimination to distinguish the explicit
     references to these registers from pseudos that happened to be
     assigned to them.

     If we have eliminated the frame pointer or arg pointer, we will
     be using it as a normal register, for example as a spill
     register.  In such cases, we might be accessing it in a mode that
     is not Pmode and therefore cannot use the pre-allocated rtx.

     Also don't do this when we are making new REGs in reload, since
     we don't want to get confused with the real pointers.  */

  if (mode == Pmode && !reload_in_progress && !lra_in_progress)
    {
      if (regno == FRAME_POINTER_REGNUM
	  && (!reload_completed || frame_pointer_needed))
	return frame_pointer_rtx;
#if !HARD_FRAME_POINTER_IS_FRAME_POINTER
      if (regno == HARD_FRAME_POINTER_REGNUM
	  && (!reload_completed || frame_pointer_needed))
	return hard_frame_pointer_rtx;
#endif
#if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM && !HARD_FRAME_POINTER_IS_ARG_POINTER
      if (regno == ARG_POINTER_REGNUM)
	return arg_pointer_rtx;
#endif
#ifdef RETURN_ADDRESS_POINTER_REGNUM
      if (regno == RETURN_ADDRESS_POINTER_REGNUM)
	return return_address_pointer_rtx;
#endif
      if (regno == (unsigned) PIC_OFFSET_TABLE_REGNUM
	  && PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM
	  && fixed_regs[PIC_OFFSET_TABLE_REGNUM])
	return pic_offset_table_rtx;
      if (regno == STACK_POINTER_REGNUM)
	return stack_pointer_rtx;
    }

#if 0
  /* If the per-function register table has been set up, try to re-use
     an existing entry in that table to avoid useless generation of RTL.

     This code is disabled for now until we can fix the various backends
     which depend on having non-shared hard registers in some cases.   Long
     term we want to re-enable this code as it can significantly cut down
     on the amount of useless RTL that gets generated.

     We'll also need to fix some code that runs after reload that wants to
     set ORIGINAL_REGNO.  */

  if (cfun
      && cfun->emit
      && regno_reg_rtx
      && regno < FIRST_PSEUDO_REGISTER
      && reg_raw_mode[regno] == mode)
    return regno_reg_rtx[regno];
#endif

  return gen_raw_REG (mode, regno);
}

rtx
gen_rtx_MEM (machine_mode mode, rtx addr)
{
  rtx rt = gen_rtx_raw_MEM (mode, addr);

  /* This field is not cleared by the mere allocation of the rtx, so
     we clear it here.  */
  MEM_ATTRS (rt) = 0;

  return rt;
}

/* Generate a memory referring to non-trapping constant memory.  */

rtx
gen_const_mem (machine_mode mode, rtx addr)
{
  rtx mem = gen_rtx_MEM (mode, addr);
  MEM_READONLY_P (mem) = 1;
  MEM_NOTRAP_P (mem) = 1;
  return mem;
}

/* Generate a MEM referring to fixed portions of the frame, e.g., register
   save areas.  */

rtx
gen_frame_mem (machine_mode mode, rtx addr)
{
  rtx mem = gen_rtx_MEM (mode, addr);
  MEM_NOTRAP_P (mem) = 1;
  set_mem_alias_set (mem, get_frame_alias_set ());
  return mem;
}

/* Generate a MEM referring to a temporary use of the stack, not part
    of the fixed stack frame.  For example, something which is pushed
    by a target splitter.  */
rtx
gen_tmp_stack_mem (machine_mode mode, rtx addr)
{
  rtx mem = gen_rtx_MEM (mode, addr);
  MEM_NOTRAP_P (mem) = 1;
  if (!cfun->calls_alloca)
    set_mem_alias_set (mem, get_frame_alias_set ());
  return mem;
}

/* We want to create (subreg:OMODE (obj:IMODE) OFFSET).  Return true if
   this construct would be valid, and false otherwise.  */

bool
validate_subreg (machine_mode omode, machine_mode imode,
		 const_rtx reg, unsigned int offset)
{
  unsigned int isize = GET_MODE_SIZE (imode);
  unsigned int osize = GET_MODE_SIZE (omode);

  /* All subregs must be aligned.  */
  if (offset % osize != 0)
    return false;

  /* The subreg offset cannot be outside the inner object.  */
  if (offset >= isize)
    return false;

  /* ??? This should not be here.  Temporarily continue to allow word_mode
     subregs of anything.  The most common offender is (subreg:SI (reg:DF)).
     Generally, backends are doing something sketchy but it'll take time to
     fix them all.  */
  if (omode == word_mode)
    ;
  /* ??? Similarly, e.g. with (subreg:DF (reg:TI)).  Though store_bit_field
     is the culprit here, and not the backends.  */
  else if (osize >= UNITS_PER_WORD && isize >= osize)
    ;
  /* Allow component subregs of complex and vector.  Though given the below
     extraction rules, it's not always clear what that means.  */
  else if ((COMPLEX_MODE_P (imode) || VECTOR_MODE_P (imode))
	   && GET_MODE_INNER (imode) == omode)
    ;
  /* ??? x86 sse code makes heavy use of *paradoxical* vector subregs,
     i.e. (subreg:V4SF (reg:SF) 0).  This surely isn't the cleanest way to
     represent this.  It's questionable if this ought to be represented at
     all -- why can't this all be hidden in post-reload splitters that make
     arbitrarily mode changes to the registers themselves.  */
  else if (VECTOR_MODE_P (omode) && GET_MODE_INNER (omode) == imode)
    ;
  /* Subregs involving floating point modes are not allowed to
     change size.  Therefore (subreg:DI (reg:DF) 0) is fine, but
     (subreg:SI (reg:DF) 0) isn't.  */
  else if (FLOAT_MODE_P (imode) || FLOAT_MODE_P (omode))
    {
      if (! (isize == osize
	     /* LRA can use subreg to store a floating point value in
		an integer mode.  Although the floating point and the
		integer modes need the same number of hard registers,
		the size of floating point mode can be less than the
		integer mode.  LRA also uses subregs for a register
		should be used in different mode in on insn.  */
	     || lra_in_progress))
	return false;
    }

  /* Paradoxical subregs must have offset zero.  */
  if (osize > isize)
    return offset == 0;

  /* This is a normal subreg.  Verify that the offset is representable.  */

  /* For hard registers, we already have most of these rules collected in
     subreg_offset_representable_p.  */
  if (reg && REG_P (reg) && HARD_REGISTER_P (reg))
    {
      unsigned int regno = REGNO (reg);

#ifdef CANNOT_CHANGE_MODE_CLASS
      if ((COMPLEX_MODE_P (imode) || VECTOR_MODE_P (imode))
	  && GET_MODE_INNER (imode) == omode)
	;
      else if (REG_CANNOT_CHANGE_MODE_P (regno, imode, omode))
	return false;
#endif

      return subreg_offset_representable_p (regno, imode, offset, omode);
    }

  /* For pseudo registers, we want most of the same checks.  Namely:
     If the register no larger than a word, the subreg must be lowpart.
     If the register is larger than a word, the subreg must be the lowpart
     of a subword.  A subreg does *not* perform arbitrary bit extraction.
     Given that we've already checked mode/offset alignment, we only have
     to check subword subregs here.  */
  if (osize < UNITS_PER_WORD
      && ! (lra_in_progress && (FLOAT_MODE_P (imode) || FLOAT_MODE_P (omode))))
    {
      machine_mode wmode = isize > UNITS_PER_WORD ? word_mode : imode;
      unsigned int low_off = subreg_lowpart_offset (omode, wmode);
      if (offset % UNITS_PER_WORD != low_off)
	return false;
    }
  return true;
}

rtx
gen_rtx_SUBREG (machine_mode mode, rtx reg, int offset)
{
  gcc_assert (validate_subreg (mode, GET_MODE (reg), reg, offset));
  return gen_rtx_raw_SUBREG (mode, reg, offset);
}

/* Generate a SUBREG representing the least-significant part of REG if MODE
   is smaller than mode of REG, otherwise paradoxical SUBREG.  */

rtx
gen_lowpart_SUBREG (machine_mode mode, rtx reg)
{
  machine_mode inmode;

  inmode = GET_MODE (reg);
  if (inmode == VOIDmode)
    inmode = mode;
  return gen_rtx_SUBREG (mode, reg,
			 subreg_lowpart_offset (mode, inmode));
}

rtx
gen_rtx_VAR_LOCATION (machine_mode mode, tree decl, rtx loc,
		      enum var_init_status status)
{
  rtx x = gen_rtx_fmt_te (VAR_LOCATION, mode, decl, loc);
  PAT_VAR_LOCATION_STATUS (x) = status;
  return x;
}


/* Create an rtvec and stores within it the RTXen passed in the arguments.  */

rtvec
gen_rtvec (int n, ...)
{
  int i;
  rtvec rt_val;
  va_list p;

  va_start (p, n);

  /* Don't allocate an empty rtvec...  */
  if (n == 0)
    {
      va_end (p);
      return NULL_RTVEC;
    }

  rt_val = rtvec_alloc (n);

  for (i = 0; i < n; i++)
    rt_val->elem[i] = va_arg (p, rtx);

  va_end (p);
  return rt_val;
}

rtvec
gen_rtvec_v (int n, rtx *argp)
{
  int i;
  rtvec rt_val;

  /* Don't allocate an empty rtvec...  */
  if (n == 0)
    return NULL_RTVEC;

  rt_val = rtvec_alloc (n);

  for (i = 0; i < n; i++)
    rt_val->elem[i] = *argp++;

  return rt_val;
}

rtvec
gen_rtvec_v (int n, rtx_insn **argp)
{
  int i;
  rtvec rt_val;

  /* Don't allocate an empty rtvec...  */
  if (n == 0)
    return NULL_RTVEC;

  rt_val = rtvec_alloc (n);

  for (i = 0; i < n; i++)
    rt_val->elem[i] = *argp++;

  return rt_val;
}


/* Return the number of bytes between the start of an OUTER_MODE
   in-memory value and the start of an INNER_MODE in-memory value,
   given that the former is a lowpart of the latter.  It may be a
   paradoxical lowpart, in which case the offset will be negative
   on big-endian targets.  */

int
byte_lowpart_offset (machine_mode outer_mode,
		     machine_mode inner_mode)
{
  if (GET_MODE_SIZE (outer_mode) < GET_MODE_SIZE (inner_mode))
    return subreg_lowpart_offset (outer_mode, inner_mode);
  else
    return -subreg_lowpart_offset (inner_mode, outer_mode);
}

/* Generate a REG rtx for a new pseudo register of mode MODE.
   This pseudo is assigned the next sequential register number.  */

rtx
gen_reg_rtx (machine_mode mode)
{
  rtx val;
  unsigned int align = GET_MODE_ALIGNMENT (mode);

  gcc_assert (can_create_pseudo_p ());

  /* If a virtual register with bigger mode alignment is generated,
     increase stack alignment estimation because it might be spilled
     to stack later.  */
  if (SUPPORTS_STACK_ALIGNMENT
      && crtl->stack_alignment_estimated < align
      && !crtl->stack_realign_processed)
    {
      unsigned int min_align = MINIMUM_ALIGNMENT (NULL, mode, align);
      if (crtl->stack_alignment_estimated < min_align)
	crtl->stack_alignment_estimated = min_align;
    }

  if (generating_concat_p
      && (GET_MODE_CLASS (mode) == MODE_COMPLEX_FLOAT
	  || GET_MODE_CLASS (mode) == MODE_COMPLEX_INT))
    {
      /* For complex modes, don't make a single pseudo.
	 Instead, make a CONCAT of two pseudos.
	 This allows noncontiguous allocation of the real and imaginary parts,
	 which makes much better code.  Besides, allocating DCmode
	 pseudos overstrains reload on some machines like the 386.  */
      rtx realpart, imagpart;
      machine_mode partmode = GET_MODE_INNER (mode);

      realpart = gen_reg_rtx (partmode);
      imagpart = gen_reg_rtx (partmode);
      return gen_rtx_CONCAT (mode, realpart, imagpart);
    }

  /* Do not call gen_reg_rtx with uninitialized crtl.  */
  gcc_assert (crtl->emit.regno_pointer_align_length);

  /* Make sure regno_pointer_align, and regno_reg_rtx are large
     enough to have an element for this pseudo reg number.  */

  if (reg_rtx_no == crtl->emit.regno_pointer_align_length)
    {
      int old_size = crtl->emit.regno_pointer_align_length;
      char *tmp;
      rtx *new1;

      tmp = XRESIZEVEC (char, crtl->emit.regno_pointer_align, old_size * 2);
      memset (tmp + old_size, 0, old_size);
      crtl->emit.regno_pointer_align = (unsigned char *) tmp;

      new1 = GGC_RESIZEVEC (rtx, regno_reg_rtx, old_size * 2);
      memset (new1 + old_size, 0, old_size * sizeof (rtx));
      regno_reg_rtx = new1;

      crtl->emit.regno_pointer_align_length = old_size * 2;
    }

  val = gen_raw_REG (mode, reg_rtx_no);
  regno_reg_rtx[reg_rtx_no++] = val;
  return val;
}

/* Return TRUE if REG is a PARM_DECL, FALSE otherwise.  */

bool
reg_is_parm_p (rtx reg)
{
  tree decl;

  gcc_assert (REG_P (reg));
  decl = REG_EXPR (reg);
  return (decl && TREE_CODE (decl) == PARM_DECL);
}

/* Update NEW with the same attributes as REG, but with OFFSET added
   to the REG_OFFSET.  */

static void
update_reg_offset (rtx new_rtx, rtx reg, int offset)
{
  REG_ATTRS (new_rtx) = get_reg_attrs (REG_EXPR (reg),
				   REG_OFFSET (reg) + offset);
}

/* Generate a register with same attributes as REG, but with OFFSET
   added to the REG_OFFSET.  */

rtx
gen_rtx_REG_offset (rtx reg, machine_mode mode, unsigned int regno,
		    int offset)
{
  rtx new_rtx = gen_rtx_REG (mode, regno);

  update_reg_offset (new_rtx, reg, offset);
  return new_rtx;
}

/* Generate a new pseudo-register with the same attributes as REG, but
   with OFFSET added to the REG_OFFSET.  */

rtx
gen_reg_rtx_offset (rtx reg, machine_mode mode, int offset)
{
  rtx new_rtx = gen_reg_rtx (mode);

  update_reg_offset (new_rtx, reg, offset);
  return new_rtx;
}

/* Adjust REG in-place so that it has mode MODE.  It is assumed that the
   new register is a (possibly paradoxical) lowpart of the old one.  */

void
adjust_reg_mode (rtx reg, machine_mode mode)
{
  update_reg_offset (reg, reg, byte_lowpart_offset (mode, GET_MODE (reg)));
  PUT_MODE (reg, mode);
}

/* Copy REG's attributes from X, if X has any attributes.  If REG and X
   have different modes, REG is a (possibly paradoxical) lowpart of X.  */

void
set_reg_attrs_from_value (rtx reg, rtx x)
{
  int offset;
  bool can_be_reg_pointer = true;

  /* Don't call mark_reg_pointer for incompatible pointer sign
     extension.  */
  while (GET_CODE (x) == SIGN_EXTEND
	 || GET_CODE (x) == ZERO_EXTEND
	 || GET_CODE (x) == TRUNCATE
	 || (GET_CODE (x) == SUBREG && subreg_lowpart_p (x)))
    {
#if defined(POINTERS_EXTEND_UNSIGNED) && !defined(HAVE_ptr_extend)
      if ((GET_CODE (x) == SIGN_EXTEND && POINTERS_EXTEND_UNSIGNED)
	  || (GET_CODE (x) != SIGN_EXTEND && ! POINTERS_EXTEND_UNSIGNED))
	can_be_reg_pointer = false;
#endif
      x = XEXP (x, 0);
    }

  /* Hard registers can be reused for multiple purposes within the same
     function, so setting REG_ATTRS, REG_POINTER and REG_POINTER_ALIGN
     on them is wrong.  */
  if (HARD_REGISTER_P (reg))
    return;

  offset = byte_lowpart_offset (GET_MODE (reg), GET_MODE (x));
  if (MEM_P (x))
    {
      if (MEM_OFFSET_KNOWN_P (x))
	REG_ATTRS (reg) = get_reg_attrs (MEM_EXPR (x),
					 MEM_OFFSET (x) + offset);
      if (can_be_reg_pointer && MEM_POINTER (x))
	mark_reg_pointer (reg, 0);
    }
  else if (REG_P (x))
    {
      if (REG_ATTRS (x))
	update_reg_offset (reg, x, offset);
      if (can_be_reg_pointer && REG_POINTER (x))
	mark_reg_pointer (reg, REGNO_POINTER_ALIGN (REGNO (x)));
    }
}

/* Generate a REG rtx for a new pseudo register, copying the mode
   and attributes from X.  */

rtx
gen_reg_rtx_and_attrs (rtx x)
{
  rtx reg = gen_reg_rtx (GET_MODE (x));
  set_reg_attrs_from_value (reg, x);
  return reg;
}

/* Set the register attributes for registers contained in PARM_RTX.
   Use needed values from memory attributes of MEM.  */

void
set_reg_attrs_for_parm (rtx parm_rtx, rtx mem)
{
  if (REG_P (parm_rtx))
    set_reg_attrs_from_value (parm_rtx, mem);
  else if (GET_CODE (parm_rtx) == PARALLEL)
    {
      /* Check for a NULL entry in the first slot, used to indicate that the
	 parameter goes both on the stack and in registers.  */
      int i = XEXP (XVECEXP (parm_rtx, 0, 0), 0) ? 0 : 1;
      for (; i < XVECLEN (parm_rtx, 0); i++)
	{
	  rtx x = XVECEXP (parm_rtx, 0, i);
	  if (REG_P (XEXP (x, 0)))
	    REG_ATTRS (XEXP (x, 0))
	      = get_reg_attrs (MEM_EXPR (mem),
			       INTVAL (XEXP (x, 1)));
	}
    }
}

/* Set the REG_ATTRS for registers in value X, given that X represents
   decl T.  */

void
set_reg_attrs_for_decl_rtl (tree t, rtx x)
{
  if (GET_CODE (x) == SUBREG)
    {
      gcc_assert (subreg_lowpart_p (x));
      x = SUBREG_REG (x);
    }
  if (REG_P (x))
    REG_ATTRS (x)
      = get_reg_attrs (t, byte_lowpart_offset (GET_MODE (x),
					       DECL_MODE (t)));
  if (GET_CODE (x) == CONCAT)
    {
      if (REG_P (XEXP (x, 0)))
        REG_ATTRS (XEXP (x, 0)) = get_reg_attrs (t, 0);
      if (REG_P (XEXP (x, 1)))
	REG_ATTRS (XEXP (x, 1))
	  = get_reg_attrs (t, GET_MODE_UNIT_SIZE (GET_MODE (XEXP (x, 0))));
    }
  if (GET_CODE (x) == PARALLEL)
    {
      int i, start;

      /* Check for a NULL entry, used to indicate that the parameter goes
	 both on the stack and in registers.  */
      if (XEXP (XVECEXP (x, 0, 0), 0))
	start = 0;
      else
	start = 1;

      for (i = start; i < XVECLEN (x, 0); i++)
	{
	  rtx y = XVECEXP (x, 0, i);
	  if (REG_P (XEXP (y, 0)))
	    REG_ATTRS (XEXP (y, 0)) = get_reg_attrs (t, INTVAL (XEXP (y, 1)));
	}
    }
}

/* Assign the RTX X to declaration T.  */

void
set_decl_rtl (tree t, rtx x)
{
  DECL_WRTL_CHECK (t)->decl_with_rtl.rtl = x;
  if (x)
    set_reg_attrs_for_decl_rtl (t, x);
}

/* Assign the RTX X to parameter declaration T.  BY_REFERENCE_P is true
   if the ABI requires the parameter to be passed by reference.  */

void
set_decl_incoming_rtl (tree t, rtx x, bool by_reference_p)
{
  DECL_INCOMING_RTL (t) = x;
  if (x && !by_reference_p)
    set_reg_attrs_for_decl_rtl (t, x);
}

/* Identify REG (which may be a CONCAT) as a user register.  */

void
mark_user_reg (rtx reg)
{
  if (GET_CODE (reg) == CONCAT)
    {
      REG_USERVAR_P (XEXP (reg, 0)) = 1;
      REG_USERVAR_P (XEXP (reg, 1)) = 1;
    }
  else
    {
      gcc_assert (REG_P (reg));
      REG_USERVAR_P (reg) = 1;
    }
}

/* Identify REG as a probable pointer register and show its alignment
   as ALIGN, if nonzero.  */

void
mark_reg_pointer (rtx reg, int align)
{
  if (! REG_POINTER (reg))
    {
      REG_POINTER (reg) = 1;

      if (align)
	REGNO_POINTER_ALIGN (REGNO (reg)) = align;
    }
  else if (align && align < REGNO_POINTER_ALIGN (REGNO (reg)))
    /* We can no-longer be sure just how aligned this pointer is.  */
    REGNO_POINTER_ALIGN (REGNO (reg)) = align;
}

/* Return 1 plus largest pseudo reg number used in the current function.  */

int
max_reg_num (void)
{
  return reg_rtx_no;
}

/* Return 1 + the largest label number used so far in the current function.  */

int
max_label_num (void)
{
  return label_num;
}

/* Return first label number used in this function (if any were used).  */

int
get_first_label_num (void)
{
  return first_label_num;
}

/* If the rtx for label was created during the expansion of a nested
   function, then first_label_num won't include this label number.
   Fix this now so that array indices work later.  */

void
maybe_set_first_label_num (rtx x)
{
  if (CODE_LABEL_NUMBER (x) < first_label_num)
    first_label_num = CODE_LABEL_NUMBER (x);
}

/* Return a value representing some low-order bits of X, where the number
   of low-order bits is given by MODE.  Note that no conversion is done
   between floating-point and fixed-point values, rather, the bit
   representation is returned.

   This function handles the cases in common between gen_lowpart, below,
   and two variants in cse.c and combine.c.  These are the cases that can
   be safely handled at all points in the compilation.

   If this is not a case we can handle, return 0.  */

rtx
gen_lowpart_common (machine_mode mode, rtx x)
{
  int msize = GET_MODE_SIZE (mode);
  int xsize;
  int offset = 0;
  machine_mode innermode;

  /* Unfortunately, this routine doesn't take a parameter for the mode of X,
     so we have to make one up.  Yuk.  */
  innermode = GET_MODE (x);
  if (CONST_INT_P (x)
      && msize * BITS_PER_UNIT <= HOST_BITS_PER_WIDE_INT)
    innermode = mode_for_size (HOST_BITS_PER_WIDE_INT, MODE_INT, 0);
  else if (innermode == VOIDmode)
    innermode = mode_for_size (HOST_BITS_PER_DOUBLE_INT, MODE_INT, 0);

  xsize = GET_MODE_SIZE (innermode);

  gcc_assert (innermode != VOIDmode && innermode != BLKmode);

  if (innermode == mode)
    return x;

  /* MODE must occupy no more words than the mode of X.  */
  if ((msize + (UNITS_PER_WORD - 1)) / UNITS_PER_WORD
      > ((xsize + (UNITS_PER_WORD - 1)) / UNITS_PER_WORD))
    return 0;

  /* Don't allow generating paradoxical FLOAT_MODE subregs.  */
  if (SCALAR_FLOAT_MODE_P (mode) && msize > xsize)
    return 0;

  offset = subreg_lowpart_offset (mode, innermode);

  if ((GET_CODE (x) == ZERO_EXTEND || GET_CODE (x) == SIGN_EXTEND)
      && (GET_MODE_CLASS (mode) == MODE_INT
	  || GET_MODE_CLASS (mode) == MODE_PARTIAL_INT))
    {
      /* If we are getting the low-order part of something that has been
	 sign- or zero-extended, we can either just use the object being
	 extended or make a narrower extension.  If we want an even smaller
	 piece than the size of the object being extended, call ourselves
	 recursively.

	 This case is used mostly by combine and cse.  */

      if (GET_MODE (XEXP (x, 0)) == mode)
	return XEXP (x, 0);
      else if (msize < GET_MODE_SIZE (GET_MODE (XEXP (x, 0))))
	return gen_lowpart_common (mode, XEXP (x, 0));
      else if (msize < xsize)
	return gen_rtx_fmt_e (GET_CODE (x), mode, XEXP (x, 0));
    }
  else if (GET_CODE (x) == SUBREG || REG_P (x)
	   || GET_CODE (x) == CONCAT || GET_CODE (x) == CONST_VECTOR
	   || CONST_DOUBLE_AS_FLOAT_P (x) || CONST_SCALAR_INT_P (x))
    return simplify_gen_subreg (mode, x, innermode, offset);

  /* Otherwise, we can't do this.  */
  return 0;
}

rtx
gen_highpart (machine_mode mode, rtx x)
{
  unsigned int msize = GET_MODE_SIZE (mode);
  rtx result;

  /* This case loses if X is a subreg.  To catch bugs early,
     complain if an invalid MODE is used even in other cases.  */
  gcc_assert (msize <= UNITS_PER_WORD
	      || msize == (unsigned int) GET_MODE_UNIT_SIZE (GET_MODE (x)));

  result = simplify_gen_subreg (mode, x, GET_MODE (x),
				subreg_highpart_offset (mode, GET_MODE (x)));
  gcc_assert (result);

  /* simplify_gen_subreg is not guaranteed to return a valid operand for
     the target if we have a MEM.  gen_highpart must return a valid operand,
     emitting code if necessary to do so.  */
  if (MEM_P (result))
    {
      result = validize_mem (result);
      gcc_assert (result);
    }

  return result;
}

/* Like gen_highpart, but accept mode of EXP operand in case EXP can
   be VOIDmode constant.  */
rtx
gen_highpart_mode (machine_mode outermode, machine_mode innermode, rtx exp)
{
  if (GET_MODE (exp) != VOIDmode)
    {
      gcc_assert (GET_MODE (exp) == innermode);
      return gen_highpart (outermode, exp);
    }
  return simplify_gen_subreg (outermode, exp, innermode,
			      subreg_highpart_offset (outermode, innermode));
}

/* Return the SUBREG_BYTE for an OUTERMODE lowpart of an INNERMODE value.  */

unsigned int
subreg_lowpart_offset (machine_mode outermode, machine_mode innermode)
{
  unsigned int offset = 0;
  int difference = (GET_MODE_SIZE (innermode) - GET_MODE_SIZE (outermode));

  if (difference > 0)
    {
      if (WORDS_BIG_ENDIAN)
	offset += (difference / UNITS_PER_WORD) * UNITS_PER_WORD;
      if (BYTES_BIG_ENDIAN)
	offset += difference % UNITS_PER_WORD;
    }

  return offset;
}

/* Return offset in bytes to get OUTERMODE high part
   of the value in mode INNERMODE stored in memory in target format.  */
unsigned int
subreg_highpart_offset (machine_mode outermode, machine_mode innermode)
{
  unsigned int offset = 0;
  int difference = (GET_MODE_SIZE (innermode) - GET_MODE_SIZE (outermode));

  gcc_assert (GET_MODE_SIZE (innermode) >= GET_MODE_SIZE (outermode));

  if (difference > 0)
    {
      if (! WORDS_BIG_ENDIAN)
	offset += (difference / UNITS_PER_WORD) * UNITS_PER_WORD;
      if (! BYTES_BIG_ENDIAN)
	offset += difference % UNITS_PER_WORD;
    }

  return offset;
}

/* Return 1 iff X, assumed to be a SUBREG,
   refers to the least significant part of its containing reg.
   If X is not a SUBREG, always return 1 (it is its own low part!).  */

int
subreg_lowpart_p (const_rtx x)
{
  if (GET_CODE (x) != SUBREG)
    return 1;
  else if (GET_MODE (SUBREG_REG (x)) == VOIDmode)
    return 0;

  return (subreg_lowpart_offset (GET_MODE (x), GET_MODE (SUBREG_REG (x)))
	  == SUBREG_BYTE (x));
}

/* Return true if X is a paradoxical subreg, false otherwise.  */
bool
paradoxical_subreg_p (const_rtx x)
{
  if (GET_CODE (x) != SUBREG)
    return false;
  return (GET_MODE_PRECISION (GET_MODE (x))
	  > GET_MODE_PRECISION (GET_MODE (SUBREG_REG (x))));
}

/* Return subword OFFSET of operand OP.
   The word number, OFFSET, is interpreted as the word number starting
   at the low-order address.  OFFSET 0 is the low-order word if not
   WORDS_BIG_ENDIAN, otherwise it is the high-order word.

   If we cannot extract the required word, we return zero.  Otherwise,
   an rtx corresponding to the requested word will be returned.

   VALIDATE_ADDRESS is nonzero if the address should be validated.  Before
   reload has completed, a valid address will always be returned.  After
   reload, if a valid address cannot be returned, we return zero.

   If VALIDATE_ADDRESS is zero, we simply form the required address; validating
   it is the responsibility of the caller.

   MODE is the mode of OP in case it is a CONST_INT.

   ??? This is still rather broken for some cases.  The problem for the
   moment is that all callers of this thing provide no 'goal mode' to
   tell us to work with.  This exists because all callers were written
   in a word based SUBREG world.
   Now use of this function can be deprecated by simplify_subreg in most
   cases.
 */

rtx
operand_subword (rtx op, unsigned int offset, int validate_address, machine_mode mode)
{
  if (mode == VOIDmode)
    mode = GET_MODE (op);

  gcc_assert (mode != VOIDmode);

  /* If OP is narrower than a word, fail.  */
  if (mode != BLKmode
      && (GET_MODE_SIZE (mode) < UNITS_PER_WORD))
    return 0;

  /* If we want a word outside OP, return zero.  */
  if (mode != BLKmode
      && (offset + 1) * UNITS_PER_WORD > GET_MODE_SIZE (mode))
    return const0_rtx;

  /* Form a new MEM at the requested address.  */
  if (MEM_P (op))
    {
      rtx new_rtx = adjust_address_nv (op, word_mode, offset * UNITS_PER_WORD);

      if (! validate_address)
	return new_rtx;

      else if (reload_completed)
	{
	  if (! strict_memory_address_addr_space_p (word_mode,
						    XEXP (new_rtx, 0),
						    MEM_ADDR_SPACE (op)))
	    return 0;
	}
      else
	return replace_equiv_address (new_rtx, XEXP (new_rtx, 0));
    }

  /* Rest can be handled by simplify_subreg.  */
  return simplify_gen_subreg (word_mode, op, mode, (offset * UNITS_PER_WORD));
}

/* Similar to `operand_subword', but never return 0.  If we can't
   extract the required subword, put OP into a register and try again.
   The second attempt must succeed.  We always validate the address in
   this case.

   MODE is the mode of OP, in case it is CONST_INT.  */

rtx
operand_subword_force (rtx op, unsigned int offset, machine_mode mode)
{
  rtx result = operand_subword (op, offset, 1, mode);

  if (result)
    return result;

  if (mode != BLKmode && mode != VOIDmode)
    {
      /* If this is a register which can not be accessed by words, copy it
	 to a pseudo register.  */
      if (REG_P (op))
	op = copy_to_reg (op);
      else
	op = force_reg (mode, op);
    }

  result = operand_subword (op, offset, 1, mode);
  gcc_assert (result);

  return result;
}

/* Returns 1 if both MEM_EXPR can be considered equal
   and 0 otherwise.  */

int
mem_expr_equal_p (const_tree expr1, const_tree expr2)
{
  if (expr1 == expr2)
    return 1;

  if (! expr1 || ! expr2)
    return 0;

  if (TREE_CODE (expr1) != TREE_CODE (expr2))
    return 0;

  return operand_equal_p (expr1, expr2, 0);
}

/* Return OFFSET if XEXP (MEM, 0) - OFFSET is known to be ALIGN
   bits aligned for 0 <= OFFSET < ALIGN / BITS_PER_UNIT, or
   -1 if not known.  */

int
get_mem_align_offset (rtx mem, unsigned int align)
{
  tree expr;
  unsigned HOST_WIDE_INT offset;

  /* This function can't use
     if (!MEM_EXPR (mem) || !MEM_OFFSET_KNOWN_P (mem)
	 || (MAX (MEM_ALIGN (mem),
	          MAX (align, get_object_alignment (MEM_EXPR (mem))))
	     < align))
       return -1;
     else
       return (- MEM_OFFSET (mem)) & (align / BITS_PER_UNIT - 1);
     for two reasons:
     - COMPONENT_REFs in MEM_EXPR can have NULL first operand,
       for <variable>.  get_inner_reference doesn't handle it and
       even if it did, the alignment in that case needs to be determined
       from DECL_FIELD_CONTEXT's TYPE_ALIGN.
     - it would do suboptimal job for COMPONENT_REFs, even if MEM_EXPR
       isn't sufficiently aligned, the object it is in might be.  */
  gcc_assert (MEM_P (mem));
  expr = MEM_EXPR (mem);
  if (expr == NULL_TREE || !MEM_OFFSET_KNOWN_P (mem))
    return -1;

  offset = MEM_OFFSET (mem);
  if (DECL_P (expr))
    {
      if (DECL_ALIGN (expr) < align)
	return -1;
    }
  else if (INDIRECT_REF_P (expr))
    {
      if (TYPE_ALIGN (TREE_TYPE (expr)) < (unsigned int) align)
	return -1;
    }
  else if (TREE_CODE (expr) == COMPONENT_REF)
    {
      while (1)
	{
	  tree inner = TREE_OPERAND (expr, 0);
	  tree field = TREE_OPERAND (expr, 1);
	  tree byte_offset = component_ref_field_offset (expr);
	  tree bit_offset = DECL_FIELD_BIT_OFFSET (field);

	  if (!byte_offset
	      || !tree_fits_uhwi_p (byte_offset)
	      || !tree_fits_uhwi_p (bit_offset))
	    return -1;

	  offset += tree_to_uhwi (byte_offset);
	  offset += tree_to_uhwi (bit_offset) / BITS_PER_UNIT;

	  if (inner == NULL_TREE)
	    {
	      if (TYPE_ALIGN (DECL_FIELD_CONTEXT (field))
		  < (unsigned int) align)
		return -1;
	      break;
	    }
	  else if (DECL_P (inner))
	    {
	      if (DECL_ALIGN (inner) < align)
		return -1;
	      break;
	    }
	  else if (TREE_CODE (inner) != COMPONENT_REF)
	    return -1;
	  expr = inner;
	}
    }
  else
    return -1;

  return offset & ((align / BITS_PER_UNIT) - 1);
}

/* Given REF (a MEM) and T, either the type of X or the expression
   corresponding to REF, set the memory attributes.  OBJECTP is nonzero
   if we are making a new object of this type.  BITPOS is nonzero if
   there is an offset outstanding on T that will be applied later.  */

void
set_mem_attributes_minus_bitpos (rtx ref, tree t, int objectp,
				 HOST_WIDE_INT bitpos)
{
  HOST_WIDE_INT apply_bitpos = 0;
  tree type;
  struct mem_attrs attrs, *defattrs, *refattrs;
  addr_space_t as;

  /* It can happen that type_for_mode was given a mode for which there
     is no language-level type.  In which case it returns NULL, which
     we can see here.  */
  if (t == NULL_TREE)
    return;

  type = TYPE_P (t) ? t : TREE_TYPE (t);
  if (type == error_mark_node)
    return;

  /* If we have already set DECL_RTL = ref, get_alias_set will get the
     wrong answer, as it assumes that DECL_RTL already has the right alias
     info.  Callers should not set DECL_RTL until after the call to
     set_mem_attributes.  */
  gcc_assert (!DECL_P (t) || ref != DECL_RTL_IF_SET (t));

  memset (&attrs, 0, sizeof (attrs));

  /* Get the alias set from the expression or type (perhaps using a
     front-end routine) and use it.  */
  attrs.alias = get_alias_set (t);

  MEM_VOLATILE_P (ref) |= TYPE_VOLATILE (type);
  MEM_POINTER (ref) = POINTER_TYPE_P (type);

  /* Default values from pre-existing memory attributes if present.  */
  refattrs = MEM_ATTRS (ref);
  if (refattrs)
    {
      /* ??? Can this ever happen?  Calling this routine on a MEM that
	 already carries memory attributes should probably be invalid.  */
      attrs.expr = refattrs->expr;
      attrs.offset_known_p = refattrs->offset_known_p;
      attrs.offset = refattrs->offset;
      attrs.size_known_p = refattrs->size_known_p;
      attrs.size = refattrs->size;
      attrs.align = refattrs->align;
    }

  /* Otherwise, default values from the mode of the MEM reference.  */
  else
    {
      defattrs = mode_mem_attrs[(int) GET_MODE (ref)];
      gcc_assert (!defattrs->expr);
      gcc_assert (!defattrs->offset_known_p);

      /* Respect mode size.  */
      attrs.size_known_p = defattrs->size_known_p;
      attrs.size = defattrs->size;
      /* ??? Is this really necessary?  We probably should always get
	 the size from the type below.  */

      /* Respect mode alignment for STRICT_ALIGNMENT targets if T is a type;
         if T is an object, always compute the object alignment below.  */
      if (TYPE_P (t))
	attrs.align = defattrs->align;
      else
	attrs.align = BITS_PER_UNIT;
      /* ??? If T is a type, respecting mode alignment may *also* be wrong
	 e.g. if the type carries an alignment attribute.  Should we be
	 able to simply always use TYPE_ALIGN?  */
    }

  /* We can set the alignment from the type if we are making an object,
     this is an INDIRECT_REF, or if TYPE_ALIGN_OK.  */
  if (objectp || TREE_CODE (t) == INDIRECT_REF || TYPE_ALIGN_OK (type))
    attrs.align = MAX (attrs.align, TYPE_ALIGN (type));

  /* If the size is known, we can set that.  */
  tree new_size = TYPE_SIZE_UNIT (type);

  /* The address-space is that of the type.  */
  as = TYPE_ADDR_SPACE (type);

  /* If T is not a type, we may be able to deduce some more information about
     the expression.  */
  if (! TYPE_P (t))
    {
      tree base;

      if (TREE_THIS_VOLATILE (t))
	MEM_VOLATILE_P (ref) = 1;

      /* Now remove any conversions: they don't change what the underlying
	 object is.  Likewise for SAVE_EXPR.  */
      while (CONVERT_EXPR_P (t)
	     || TREE_CODE (t) == VIEW_CONVERT_EXPR
	     || TREE_CODE (t) == SAVE_EXPR)
	t = TREE_OPERAND (t, 0);

      /* Note whether this expression can trap.  */
      MEM_NOTRAP_P (ref) = !tree_could_trap_p (t);

      base = get_base_address (t);
      if (base)
	{
	  if (DECL_P (base)
	      && TREE_READONLY (base)
	      && (TREE_STATIC (base) || DECL_EXTERNAL (base))
	      && !TREE_THIS_VOLATILE (base))
	    MEM_READONLY_P (ref) = 1;

	  /* Mark static const strings readonly as well.  */
	  if (TREE_CODE (base) == STRING_CST
	      && TREE_READONLY (base)
	      && TREE_STATIC (base))
	    MEM_READONLY_P (ref) = 1;

	  /* Address-space information is on the base object.  */
	  if (TREE_CODE (base) == MEM_REF
	      || TREE_CODE (base) == TARGET_MEM_REF)
	    as = TYPE_ADDR_SPACE (TREE_TYPE (TREE_TYPE (TREE_OPERAND (base,
								      0))));
	  else
	    as = TYPE_ADDR_SPACE (TREE_TYPE (base));
	}

      /* If this expression uses it's parent's alias set, mark it such
	 that we won't change it.  */
      if (component_uses_parent_alias_set_from (t) != NULL_TREE)
	MEM_KEEP_ALIAS_SET_P (ref) = 1;

      /* If this is a decl, set the attributes of the MEM from it.  */
      if (DECL_P (t))
	{
	  attrs.expr = t;
	  attrs.offset_known_p = true;
	  attrs.offset = 0;
	  apply_bitpos = bitpos;
	  new_size = DECL_SIZE_UNIT (t);
	}

      /* ???  If we end up with a constant here do record a MEM_EXPR.  */
      else if (CONSTANT_CLASS_P (t))
	;

      /* If this is a field reference, record it.  */
      else if (TREE_CODE (t) == COMPONENT_REF)
	{
	  attrs.expr = t;
	  attrs.offset_known_p = true;
	  attrs.offset = 0;
	  apply_bitpos = bitpos;
	  if (DECL_BIT_FIELD (TREE_OPERAND (t, 1)))
	    new_size = DECL_SIZE_UNIT (TREE_OPERAND (t, 1));
	}

      /* If this is an array reference, look for an outer field reference.  */
      else if (TREE_CODE (t) == ARRAY_REF)
	{
	  tree off_tree = size_zero_node;
	  /* We can't modify t, because we use it at the end of the
	     function.  */
	  tree t2 = t;

	  do
	    {
	      tree index = TREE_OPERAND (t2, 1);
	      tree low_bound = array_ref_low_bound (t2);
	      tree unit_size = array_ref_element_size (t2);

	      /* We assume all arrays have sizes that are a multiple of a byte.
		 First subtract the lower bound, if any, in the type of the
		 index, then convert to sizetype and multiply by the size of
		 the array element.  */
	      if (! integer_zerop (low_bound))
		index = fold_build2 (MINUS_EXPR, TREE_TYPE (index),
				     index, low_bound);

	      off_tree = size_binop (PLUS_EXPR,
				     size_binop (MULT_EXPR,
						 fold_convert (sizetype,
							       index),
						 unit_size),
				     off_tree);
	      t2 = TREE_OPERAND (t2, 0);
	    }
	  while (TREE_CODE (t2) == ARRAY_REF);

	  if (DECL_P (t2)
	      || TREE_CODE (t2) == COMPONENT_REF)
	    {
	      attrs.expr = t2;
	      attrs.offset_known_p = false;
	      if (tree_fits_uhwi_p (off_tree))
		{
		  attrs.offset_known_p = true;
		  attrs.offset = tree_to_uhwi (off_tree);
		  apply_bitpos = bitpos;
		}
	    }
	  /* Else do not record a MEM_EXPR.  */
	}

      /* If this is an indirect reference, record it.  */
      else if (TREE_CODE (t) == MEM_REF 
	       || TREE_CODE (t) == TARGET_MEM_REF)
	{
	  attrs.expr = t;
	  attrs.offset_known_p = true;
	  attrs.offset = 0;
	  apply_bitpos = bitpos;
	}

      /* Compute the alignment.  */
      unsigned int obj_align;
      unsigned HOST_WIDE_INT obj_bitpos;
      get_object_alignment_1 (t, &obj_align, &obj_bitpos);
      obj_bitpos = (obj_bitpos - bitpos) & (obj_align - 1);
      if (obj_bitpos != 0)
	obj_align = (obj_bitpos & -obj_bitpos);
      attrs.align = MAX (attrs.align, obj_align);
    }

  if (tree_fits_uhwi_p (new_size))
    {
      attrs.size_known_p = true;
      attrs.size = tree_to_uhwi (new_size);
    }

  /* If we modified OFFSET based on T, then subtract the outstanding
     bit position offset.  Similarly, increase the size of the accessed
     object to contain the negative offset.  */
  if (apply_bitpos)
    {
      gcc_assert (attrs.offset_known_p);
      attrs.offset -= apply_bitpos / BITS_PER_UNIT;
      if (attrs.size_known_p)
	attrs.size += apply_bitpos / BITS_PER_UNIT;
    }

  /* Now set the attributes we computed above.  */
  attrs.addrspace = as;
  set_mem_attrs (ref, &attrs);
}

void
set_mem_attributes (rtx ref, tree t, int objectp)
{
  set_mem_attributes_minus_bitpos (ref, t, objectp, 0);
}

/* Set the alias set of MEM to SET.  */

void
set_mem_alias_set (rtx mem, alias_set_type set)
{
  struct mem_attrs attrs;

  /* If the new and old alias sets don't conflict, something is wrong.  */
  gcc_checking_assert (alias_sets_conflict_p (set, MEM_ALIAS_SET (mem)));
  attrs = *get_mem_attrs (mem);
  attrs.alias = set;
  set_mem_attrs (mem, &attrs);
}

/* Set the address space of MEM to ADDRSPACE (target-defined).  */

void
set_mem_addr_space (rtx mem, addr_space_t addrspace)
{
  struct mem_attrs attrs;

  attrs = *get_mem_attrs (mem);
  attrs.addrspace = addrspace;
  set_mem_attrs (mem, &attrs);
}

/* Set the alignment of MEM to ALIGN bits.  */

void
set_mem_align (rtx mem, unsigned int align)
{
  struct mem_attrs attrs;

  attrs = *get_mem_attrs (mem);
  attrs.align = align;
  set_mem_attrs (mem, &attrs);
}

/* Set the expr for MEM to EXPR.  */

void
set_mem_expr (rtx mem, tree expr)
{
  struct mem_attrs attrs;

  attrs = *get_mem_attrs (mem);
  attrs.expr = expr;
  set_mem_attrs (mem, &attrs);
}

/* Set the offset of MEM to OFFSET.  */

void
set_mem_offset (rtx mem, HOST_WIDE_INT offset)
{
  struct mem_attrs attrs;

  attrs = *get_mem_attrs (mem);
  attrs.offset_known_p = true;
  attrs.offset = offset;
  set_mem_attrs (mem, &attrs);
}

/* Clear the offset of MEM.  */

void
clear_mem_offset (rtx mem)
{
  struct mem_attrs attrs;

  attrs = *get_mem_attrs (mem);
  attrs.offset_known_p = false;
  set_mem_attrs (mem, &attrs);
}

/* Set the size of MEM to SIZE.  */

void
set_mem_size (rtx mem, HOST_WIDE_INT size)
{
  struct mem_attrs attrs;

  attrs = *get_mem_attrs (mem);
  attrs.size_known_p = true;
  attrs.size = size;
  set_mem_attrs (mem, &attrs);
}

/* Clear the size of MEM.  */

void
clear_mem_size (rtx mem)
{
  struct mem_attrs attrs;

  attrs = *get_mem_attrs (mem);
  attrs.size_known_p = false;
  set_mem_attrs (mem, &attrs);
}

/* Return a memory reference like MEMREF, but with its mode changed to MODE
   and its address changed to ADDR.  (VOIDmode means don't change the mode.
   NULL for ADDR means don't change the address.)  VALIDATE is nonzero if the
   returned memory location is required to be valid.  INPLACE is true if any
   changes can be made directly to MEMREF or false if MEMREF must be treated
   as immutable.

   The memory attributes are not changed.  */

static rtx
change_address_1 (rtx memref, machine_mode mode, rtx addr, int validate,
		  bool inplace)
{
  addr_space_t as;
  rtx new_rtx;

  gcc_assert (MEM_P (memref));
  as = MEM_ADDR_SPACE (memref);
  if (mode == VOIDmode)
    mode = GET_MODE (memref);
  if (addr == 0)
    addr = XEXP (memref, 0);
  if (mode == GET_MODE (memref) && addr == XEXP (memref, 0)
      && (!validate || memory_address_addr_space_p (mode, addr, as)))
    return memref;

  /* Don't validate address for LRA.  LRA can make the address valid
     by itself in most efficient way.  */
  if (validate && !lra_in_progress)
    {
      if (reload_in_progress || reload_completed)
	gcc_assert (memory_address_addr_space_p (mode, addr, as));
      else
	addr = memory_address_addr_space (mode, addr, as);
    }

  if (rtx_equal_p (addr, XEXP (memref, 0)) && mode == GET_MODE (memref))
    return memref;

  if (inplace)
    {
      XEXP (memref, 0) = addr;
      return memref;
    }

  new_rtx = gen_rtx_MEM (mode, addr);
  MEM_COPY_ATTRIBUTES (new_rtx, memref);
  return new_rtx;
}

/* Like change_address_1 with VALIDATE nonzero, but we are not saying in what
   way we are changing MEMREF, so we only preserve the alias set.  */

rtx
change_address (rtx memref, machine_mode mode, rtx addr)
{
  rtx new_rtx = change_address_1 (memref, mode, addr, 1, false);
  machine_mode mmode = GET_MODE (new_rtx);
  struct mem_attrs attrs, *defattrs;

  attrs = *get_mem_attrs (memref);
  defattrs = mode_mem_attrs[(int) mmode];
  attrs.expr = NULL_TREE;
  attrs.offset_known_p = false;
  attrs.size_known_p = defattrs->size_known_p;
  attrs.size = defattrs->size;
  attrs.align = defattrs->align;

  /* If there are no changes, just return the original memory reference.  */
  if (new_rtx == memref)
    {
      if (mem_attrs_eq_p (get_mem_attrs (memref), &attrs))
	return new_rtx;

      new_rtx = gen_rtx_MEM (mmode, XEXP (memref, 0));
      MEM_COPY_ATTRIBUTES (new_rtx, memref);
    }

  set_mem_attrs (new_rtx, &attrs);
  return new_rtx;
}

/* Return a memory reference like MEMREF, but with its mode changed
   to MODE and its address offset by OFFSET bytes.  If VALIDATE is
   nonzero, the memory address is forced to be valid.
   If ADJUST_ADDRESS is zero, OFFSET is only used to update MEM_ATTRS
   and the caller is responsible for adjusting MEMREF base register.
   If ADJUST_OBJECT is zero, the underlying object associated with the
   memory reference is left unchanged and the caller is responsible for
   dealing with it.  Otherwise, if the new memory reference is outside
   the underlying object, even partially, then the object is dropped.
   SIZE, if nonzero, is the size of an access in cases where MODE
   has no inherent size.  */

rtx
adjust_address_1 (rtx memref, machine_mode mode, HOST_WIDE_INT offset,
		  int validate, int adjust_address, int adjust_object,
		  HOST_WIDE_INT size)
{
  rtx addr = XEXP (memref, 0);
  rtx new_rtx;
  machine_mode address_mode;
  int pbits;
  struct mem_attrs attrs = *get_mem_attrs (memref), *defattrs;
  unsigned HOST_WIDE_INT max_align;
#ifdef POINTERS_EXTEND_UNSIGNED
  machine_mode pointer_mode
    = targetm.addr_space.pointer_mode (attrs.addrspace);
#endif

  /* VOIDmode means no mode change for change_address_1.  */
  if (mode == VOIDmode)
    mode = GET_MODE (memref);

  /* Take the size of non-BLKmode accesses from the mode.  */
  defattrs = mode_mem_attrs[(int) mode];
  if (defattrs->size_known_p)
    size = defattrs->size;

  /* If there are no changes, just return the original memory reference.  */
  if (mode == GET_MODE (memref) && !offset
      && (size == 0 || (attrs.size_known_p && attrs.size == size))
      && (!validate || memory_address_addr_space_p (mode, addr,
						    attrs.addrspace)))
    return memref;

  /* ??? Prefer to create garbage instead of creating shared rtl.
     This may happen even if offset is nonzero -- consider
     (plus (plus reg reg) const_int) -- so do this always.  */
  addr = copy_rtx (addr);

  /* Convert a possibly large offset to a signed value within the
     range of the target address space.  */
  address_mode = get_address_mode (memref);
  pbits = GET_MODE_BITSIZE (address_mode);
  if (HOST_BITS_PER_WIDE_INT > pbits)
    {
      int shift = HOST_BITS_PER_WIDE_INT - pbits;
      offset = (((HOST_WIDE_INT) ((unsigned HOST_WIDE_INT) offset << shift))
		>> shift);
    }

  if (adjust_address)
    {
      /* If MEMREF is a LO_SUM and the offset is within the alignment of the
	 object, we can merge it into the LO_SUM.  */
      if (GET_MODE (memref) != BLKmode && GET_CODE (addr) == LO_SUM
	  && offset >= 0
	  && (unsigned HOST_WIDE_INT) offset
	      < GET_MODE_ALIGNMENT (GET_MODE (memref)) / BITS_PER_UNIT)
	addr = gen_rtx_LO_SUM (address_mode, XEXP (addr, 0),
			       plus_constant (address_mode,
					      XEXP (addr, 1), offset));
#ifdef POINTERS_EXTEND_UNSIGNED
      /* If MEMREF is a ZERO_EXTEND from pointer_mode and the offset is valid
	 in that mode, we merge it into the ZERO_EXTEND.  We take advantage of
	 the fact that pointers are not allowed to overflow.  */
      else if (POINTERS_EXTEND_UNSIGNED > 0
	       && GET_CODE (addr) == ZERO_EXTEND
	       && GET_MODE (XEXP (addr, 0)) == pointer_mode
	       && trunc_int_for_mode (offset, pointer_mode) == offset)
	addr = gen_rtx_ZERO_EXTEND (address_mode,
				    plus_constant (pointer_mode,
						   XEXP (addr, 0), offset));
#endif
      else
	addr = plus_constant (address_mode, addr, offset);
    }

  new_rtx = change_address_1 (memref, mode, addr, validate, false);

  /* If the address is a REG, change_address_1 rightfully returns memref,
     but this would destroy memref's MEM_ATTRS.  */
  if (new_rtx == memref && offset != 0)
    new_rtx = copy_rtx (new_rtx);

  /* Conservatively drop the object if we don't know where we start from.  */
  if (adjust_object && (!attrs.offset_known_p || !attrs.size_known_p))
    {
      attrs.expr = NULL_TREE;
      attrs.alias = 0;
    }

  /* Compute the new values of the memory attributes due to this adjustment.
     We add the offsets and update the alignment.  */
  if (attrs.offset_known_p)
    {
      attrs.offset += offset;

      /* Drop the object if the new left end is not within its bounds.  */
      if (adjust_object && attrs.offset < 0)
	{
	  attrs.expr = NULL_TREE;
	  attrs.alias = 0;
	}
    }

  /* Compute the new alignment by taking the MIN of the alignment and the
     lowest-order set bit in OFFSET, but don't change the alignment if OFFSET
     if zero.  */
  if (offset != 0)
    {
      max_align = (offset & -offset) * BITS_PER_UNIT;
      attrs.align = MIN (attrs.align, max_align);
    }

  if (size)
    {
      /* Drop the object if the new right end is not within its bounds.  */
      if (adjust_object && (offset + size) > attrs.size)
	{
	  attrs.expr = NULL_TREE;
	  attrs.alias = 0;
	}
      attrs.size_known_p = true;
      attrs.size = size;
    }
  else if (attrs.size_known_p)
    {
      gcc_assert (!adjust_object);
      attrs.size -= offset;
      /* ??? The store_by_pieces machinery generates negative sizes,
	 so don't assert for that here.  */
    }

  set_mem_attrs (new_rtx, &attrs);

  return new_rtx;
}

/* Return a memory reference like MEMREF, but with its mode changed
   to MODE and its address changed to ADDR, which is assumed to be
   MEMREF offset by OFFSET bytes.  If VALIDATE is
   nonzero, the memory address is forced to be valid.  */

rtx
adjust_automodify_address_1 (rtx memref, machine_mode mode, rtx addr,
			     HOST_WIDE_INT offset, int validate)
{
  memref = change_address_1 (memref, VOIDmode, addr, validate, false);
  return adjust_address_1 (memref, mode, offset, validate, 0, 0, 0);
}

/* Return a memory reference like MEMREF, but whose address is changed by
   adding OFFSET, an RTX, to it.  POW2 is the highest power of two factor
   known to be in OFFSET (possibly 1).  */

rtx
offset_address (rtx memref, rtx offset, unsigned HOST_WIDE_INT pow2)
{
  rtx new_rtx, addr = XEXP (memref, 0);
  machine_mode address_mode;
  struct mem_attrs attrs, *defattrs;

  attrs = *get_mem_attrs (memref);
  address_mode = get_address_mode (memref);
  new_rtx = simplify_gen_binary (PLUS, address_mode, addr, offset);

  /* At this point we don't know _why_ the address is invalid.  It
     could have secondary memory references, multiplies or anything.

     However, if we did go and rearrange things, we can wind up not
     being able to recognize the magic around pic_offset_table_rtx.
     This stuff is fragile, and is yet another example of why it is
     bad to expose PIC machinery too early.  */
  if (! memory_address_addr_space_p (GET_MODE (memref), new_rtx,
				     attrs.addrspace)
      && GET_CODE (addr) == PLUS
      && XEXP (addr, 0) == pic_offset_table_rtx)
    {
      addr = force_reg (GET_MODE (addr), addr);
      new_rtx = simplify_gen_binary (PLUS, address_mode, addr, offset);
    }

  update_temp_slot_address (XEXP (memref, 0), new_rtx);
  new_rtx = change_address_1 (memref, VOIDmode, new_rtx, 1, false);

  /* If there are no changes, just return the original memory reference.  */
  if (new_rtx == memref)
    return new_rtx;

  /* Update the alignment to reflect the offset.  Reset the offset, which
     we don't know.  */
  defattrs = mode_mem_attrs[(int) GET_MODE (new_rtx)];
  attrs.offset_known_p = false;
  attrs.size_known_p = defattrs->size_known_p;
  attrs.size = defattrs->size;
  attrs.align = MIN (attrs.align, pow2 * BITS_PER_UNIT);
  set_mem_attrs (new_rtx, &attrs);
  return new_rtx;
}

/* Return a memory reference like MEMREF, but with its address changed to
   ADDR.  The caller is asserting that the actual piece of memory pointed
   to is the same, just the form of the address is being changed, such as
   by putting something into a register.  INPLACE is true if any changes
   can be made directly to MEMREF or false if MEMREF must be treated as
   immutable.  */

rtx
replace_equiv_address (rtx memref, rtx addr, bool inplace)
{
  /* change_address_1 copies the memory attribute structure without change
     and that's exactly what we want here.  */
  update_temp_slot_address (XEXP (memref, 0), addr);
  return change_address_1 (memref, VOIDmode, addr, 1, inplace);
}

/* Likewise, but the reference is not required to be valid.  */

rtx
replace_equiv_address_nv (rtx memref, rtx addr, bool inplace)
{
  return change_address_1 (memref, VOIDmode, addr, 0, inplace);
}

/* Return a memory reference like MEMREF, but with its mode widened to
   MODE and offset by OFFSET.  This would be used by targets that e.g.
   cannot issue QImode memory operations and have to use SImode memory
   operations plus masking logic.  */

rtx
widen_memory_access (rtx memref, machine_mode mode, HOST_WIDE_INT offset)
{
  rtx new_rtx = adjust_address_1 (memref, mode, offset, 1, 1, 0, 0);
  struct mem_attrs attrs;
  unsigned int size = GET_MODE_SIZE (mode);

  /* If there are no changes, just return the original memory reference.  */
  if (new_rtx == memref)
    return new_rtx;

  attrs = *get_mem_attrs (new_rtx);

  /* If we don't know what offset we were at within the expression, then
     we can't know if we've overstepped the bounds.  */
  if (! attrs.offset_known_p)
    attrs.expr = NULL_TREE;

  while (attrs.expr)
    {
      if (TREE_CODE (attrs.expr) == COMPONENT_REF)
	{
	  tree field = TREE_OPERAND (attrs.expr, 1);
	  tree offset = component_ref_field_offset (attrs.expr);

	  if (! DECL_SIZE_UNIT (field))
	    {
	      attrs.expr = NULL_TREE;
	      break;
	    }

	  /* Is the field at least as large as the access?  If so, ok,
	     otherwise strip back to the containing structure.  */
	  if (TREE_CODE (DECL_SIZE_UNIT (field)) == INTEGER_CST
	      && compare_tree_int (DECL_SIZE_UNIT (field), size) >= 0
	      && attrs.offset >= 0)
	    break;

	  if (! tree_fits_uhwi_p (offset))
	    {
	      attrs.expr = NULL_TREE;
	      break;
	    }

	  attrs.expr = TREE_OPERAND (attrs.expr, 0);
	  attrs.offset += tree_to_uhwi (offset);
	  attrs.offset += (tree_to_uhwi (DECL_FIELD_BIT_OFFSET (field))
			   / BITS_PER_UNIT);
	}
      /* Similarly for the decl.  */
      else if (DECL_P (attrs.expr)
	       && DECL_SIZE_UNIT (attrs.expr)
	       && TREE_CODE (DECL_SIZE_UNIT (attrs.expr)) == INTEGER_CST
	       && compare_tree_int (DECL_SIZE_UNIT (attrs.expr), size) >= 0
	       && (! attrs.offset_known_p || attrs.offset >= 0))
	break;
      else
	{
	  /* The widened memory access overflows the expression, which means
	     that it could alias another expression.  Zap it.  */
	  attrs.expr = NULL_TREE;
	  break;
	}
    }

  if (! attrs.expr)
    attrs.offset_known_p = false;

  /* The widened memory may alias other stuff, so zap the alias set.  */
  /* ??? Maybe use get_alias_set on any remaining expression.  */
  attrs.alias = 0;
  attrs.size_known_p = true;
  attrs.size = size;
  set_mem_attrs (new_rtx, &attrs);
  return new_rtx;
}

/* A fake decl that is used as the MEM_EXPR of spill slots.  */
static GTY(()) tree spill_slot_decl;

tree
get_spill_slot_decl (bool force_build_p)
{
  tree d = spill_slot_decl;
  rtx rd;
  struct mem_attrs attrs;

  if (d || !force_build_p)
    return d;

  d = build_decl (DECL_SOURCE_LOCATION (current_function_decl),
		  VAR_DECL, get_identifier ("%sfp"), void_type_node);
  DECL_ARTIFICIAL (d) = 1;
  DECL_IGNORED_P (d) = 1;
  TREE_USED (d) = 1;
  spill_slot_decl = d;

  rd = gen_rtx_MEM (BLKmode, frame_pointer_rtx);
  MEM_NOTRAP_P (rd) = 1;
  attrs = *mode_mem_attrs[(int) BLKmode];
  attrs.alias = new_alias_set ();
  attrs.expr = d;
  set_mem_attrs (rd, &attrs);
  SET_DECL_RTL (d, rd);

  return d;
}

/* Given MEM, a result from assign_stack_local, fill in the memory
   attributes as appropriate for a register allocator spill slot.
   These slots are not aliasable by other memory.  We arrange for
   them all to use a single MEM_EXPR, so that the aliasing code can
   work properly in the case of shared spill slots.  */

void
set_mem_attrs_for_spill (rtx mem)
{
  struct mem_attrs attrs;
  rtx addr;

  attrs = *get_mem_attrs (mem);
  attrs.expr = get_spill_slot_decl (true);
  attrs.alias = MEM_ALIAS_SET (DECL_RTL (attrs.expr));
  attrs.addrspace = ADDR_SPACE_GENERIC;

  /* We expect the incoming memory to be of the form:
	(mem:MODE (plus (reg sfp) (const_int offset)))
     with perhaps the plus missing for offset = 0.  */
  addr = XEXP (mem, 0);
  attrs.offset_known_p = true;
  attrs.offset = 0;
  if (GET_CODE (addr) == PLUS
      && CONST_INT_P (XEXP (addr, 1)))
    attrs.offset = INTVAL (XEXP (addr, 1));

  set_mem_attrs (mem, &attrs);
  MEM_NOTRAP_P (mem) = 1;
}

/* Return a newly created CODE_LABEL rtx with a unique label number.  */

rtx_code_label *
gen_label_rtx (void)
{
  return as_a <rtx_code_label *> (
	    gen_rtx_CODE_LABEL (VOIDmode, NULL_RTX, NULL_RTX,
				NULL, label_num++, NULL));
}

/* For procedure integration.  */

/* Install new pointers to the first and last insns in the chain.
   Also, set cur_insn_uid to one higher than the last in use.
   Used for an inline-procedure after copying the insn chain.  */

void
set_new_first_and_last_insn (rtx_insn *first, rtx_insn *last)
{
  rtx_insn *insn;

  set_first_insn (first);
  set_last_insn (last);
  cur_insn_uid = 0;

  if (MIN_NONDEBUG_INSN_UID || MAY_HAVE_DEBUG_INSNS)
    {
      int debug_count = 0;

      cur_insn_uid = MIN_NONDEBUG_INSN_UID - 1;
      cur_debug_insn_uid = 0;

      for (insn = first; insn; insn = NEXT_INSN (insn))
	if (INSN_UID (insn) < MIN_NONDEBUG_INSN_UID)
	  cur_debug_insn_uid = MAX (cur_debug_insn_uid, INSN_UID (insn));
	else
	  {
	    cur_insn_uid = MAX (cur_insn_uid, INSN_UID (insn));
	    if (DEBUG_INSN_P (insn))
	      debug_count++;
	  }

      if (debug_count)
	cur_debug_insn_uid = MIN_NONDEBUG_INSN_UID + debug_count;
      else
	cur_debug_insn_uid++;
    }
  else
    for (insn = first; insn; insn = NEXT_INSN (insn))
      cur_insn_uid = MAX (cur_insn_uid, INSN_UID (insn));

  cur_insn_uid++;
}

/* Go through all the RTL insn bodies and copy any invalid shared
   structure.  This routine should only be called once.  */

static void
unshare_all_rtl_1 (rtx_insn *insn)
{
  /* Unshare just about everything else.  */
  unshare_all_rtl_in_chain (insn);

  /* Make sure the addresses of stack slots found outside the insn chain
     (such as, in DECL_RTL of a variable) are not shared
     with the insn chain.

     This special care is necessary when the stack slot MEM does not
     actually appear in the insn chain.  If it does appear, its address
     is unshared from all else at that point.  */
  stack_slot_list = safe_as_a <rtx_expr_list *> (
		      copy_rtx_if_shared (stack_slot_list));
}

/* Go through all the RTL insn bodies and copy any invalid shared
   structure, again.  This is a fairly expensive thing to do so it
   should be done sparingly.  */

void
unshare_all_rtl_again (rtx_insn *insn)
{
  rtx_insn *p;
  tree decl;

  for (p = insn; p; p = NEXT_INSN (p))
    if (INSN_P (p))
      {
	reset_used_flags (PATTERN (p));
	reset_used_flags (REG_NOTES (p));
	if (CALL_P (p))
	  reset_used_flags (CALL_INSN_FUNCTION_USAGE (p));
      }

  /* Make sure that virtual stack slots are not shared.  */
  set_used_decls (DECL_INITIAL (cfun->decl));

  /* Make sure that virtual parameters are not shared.  */
  for (decl = DECL_ARGUMENTS (cfun->decl); decl; decl = DECL_CHAIN (decl))
    set_used_flags (DECL_RTL (decl));

  reset_used_flags (stack_slot_list);

  unshare_all_rtl_1 (insn);
}

unsigned int
unshare_all_rtl (void)
{
  unshare_all_rtl_1 (get_insns ());
  return 0;
}


/* Check that ORIG is not marked when it should not be and mark ORIG as in use,
   Recursively does the same for subexpressions.  */

static void
verify_rtx_sharing (rtx orig, rtx insn)
{
  rtx x = orig;
  int i;
  enum rtx_code code;
  const char *format_ptr;

  if (x == 0)
    return;

  code = GET_CODE (x);

  /* These types may be freely shared.  */

  switch (code)
    {
    case REG:
    case DEBUG_EXPR:
    case VALUE:
    CASE_CONST_ANY:
    case SYMBOL_REF:
    case LABEL_REF:
    case CODE_LABEL:
    case PC:
    case CC0:
    case RETURN:
    case SIMPLE_RETURN:
    case SCRATCH:
      /* SCRATCH must be shared because they represent distinct values.  */
      return;
    case CLOBBER:
      /* Share clobbers of hard registers (like cc0), but do not share pseudo reg
         clobbers or clobbers of hard registers that originated as pseudos.
         This is needed to allow safe register renaming.  */
      if (REG_P (XEXP (x, 0)) && REGNO (XEXP (x, 0)) < FIRST_PSEUDO_REGISTER
	  && ORIGINAL_REGNO (XEXP (x, 0)) == REGNO (XEXP (x, 0)))
	return;
      break;

    case CONST:
      if (shared_const_p (orig))
	return;
      break;

    case MEM:
      /* A MEM is allowed to be shared if its address is constant.  */
      if (CONSTANT_ADDRESS_P (XEXP (x, 0))
	  || reload_completed || reload_in_progress)
	return;

      break;

    default:
      break;
    }

  /* This rtx may not be shared.  If it has already been seen,
     replace it with a copy of itself.  */
#ifdef ENABLE_CHECKING
  if (RTX_FLAG (x, used))
    {
      error ("invalid rtl sharing found in the insn");
      debug_rtx (insn);
      error ("shared rtx");
      debug_rtx (x);
      internal_error ("internal consistency failure");
    }
#endif
  gcc_assert (!RTX_FLAG (x, used));

  RTX_FLAG (x, used) = 1;

  /* Now scan the subexpressions recursively.  */

  format_ptr = GET_RTX_FORMAT (code);

  for (i = 0; i < GET_RTX_LENGTH (code); i++)
    {
      switch (*format_ptr++)
	{
	case 'e':
	  verify_rtx_sharing (XEXP (x, i), insn);
	  break;

	case 'E':
	  if (XVEC (x, i) != NULL)
	    {
	      int j;
	      int len = XVECLEN (x, i);

	      for (j = 0; j < len; j++)
		{
		  /* We allow sharing of ASM_OPERANDS inside single
		     instruction.  */
		  if (j && GET_CODE (XVECEXP (x, i, j)) == SET
		      && (GET_CODE (SET_SRC (XVECEXP (x, i, j)))
			  == ASM_OPERANDS))
		    verify_rtx_sharing (SET_DEST (XVECEXP (x, i, j)), insn);
		  else
		    verify_rtx_sharing (XVECEXP (x, i, j), insn);
		}
	    }
	  break;
	}
    }
  return;
}

/* Reset used-flags for INSN.  */

static void
reset_insn_used_flags (rtx insn)
{
  gcc_assert (INSN_P (insn));
  reset_used_flags (PATTERN (insn));
  reset_used_flags (REG_NOTES (insn));
  if (CALL_P (insn))
    reset_used_flags (CALL_INSN_FUNCTION_USAGE (insn));
}

/* Go through all the RTL insn bodies and clear all the USED bits.  */

static void
reset_all_used_flags (void)
{
  rtx_insn *p;

  for (p = get_insns (); p; p = NEXT_INSN (p))
    if (INSN_P (p))
      {
	rtx pat = PATTERN (p);
	if (GET_CODE (pat) != SEQUENCE)
	  reset_insn_used_flags (p);
	else
	  {
	    gcc_assert (REG_NOTES (p) == NULL);
	    for (int i = 0; i < XVECLEN (pat, 0); i++)
	      {
		rtx insn = XVECEXP (pat, 0, i);
		if (INSN_P (insn))
		  reset_insn_used_flags (insn);
	      }
	  }
      }
}

/* Verify sharing in INSN.  */

static void
verify_insn_sharing (rtx insn)
{
  gcc_assert (INSN_P (insn));
  reset_used_flags (PATTERN (insn));
  reset_used_flags (REG_NOTES (insn));
  if (CALL_P (insn))
    reset_used_flags (CALL_INSN_FUNCTION_USAGE (insn));
}

/* Go through all the RTL insn bodies and check that there is no unexpected
   sharing in between the subexpressions.  */

DEBUG_FUNCTION void
verify_rtl_sharing (void)
{
  rtx_insn *p;

  timevar_push (TV_VERIFY_RTL_SHARING);

  reset_all_used_flags ();

  for (p = get_insns (); p; p = NEXT_INSN (p))
    if (INSN_P (p))
      {
	rtx pat = PATTERN (p);
	if (GET_CODE (pat) != SEQUENCE)
	  verify_insn_sharing (p);
	else
	  for (int i = 0; i < XVECLEN (pat, 0); i++)
	      {
		rtx insn = XVECEXP (pat, 0, i);
		if (INSN_P (insn))
		  verify_insn_sharing (insn);
	      }
      }

  reset_all_used_flags ();

  timevar_pop (TV_VERIFY_RTL_SHARING);
}

/* Go through all the RTL insn bodies and copy any invalid shared structure.
   Assumes the mark bits are cleared at entry.  */

void
unshare_all_rtl_in_chain (rtx_insn *insn)
{
  for (; insn; insn = NEXT_INSN (insn))
    if (INSN_P (insn))
      {
	PATTERN (insn) = copy_rtx_if_shared (PATTERN (insn));
	REG_NOTES (insn) = copy_rtx_if_shared (REG_NOTES (insn));
	if (CALL_P (insn))
	  CALL_INSN_FUNCTION_USAGE (insn)
	    = copy_rtx_if_shared (CALL_INSN_FUNCTION_USAGE (insn));
      }
}

/* Go through all virtual stack slots of a function and mark them as
   shared.  We never replace the DECL_RTLs themselves with a copy,
   but expressions mentioned into a DECL_RTL cannot be shared with
   expressions in the instruction stream.

   Note that reload may convert pseudo registers into memories in-place.
   Pseudo registers are always shared, but MEMs never are.  Thus if we
   reset the used flags on MEMs in the instruction stream, we must set
   them again on MEMs that appear in DECL_RTLs.  */

static void
set_used_decls (tree blk)
{
  tree t;

  /* Mark decls.  */
  for (t = BLOCK_VARS (blk); t; t = DECL_CHAIN (t))
    if (DECL_RTL_SET_P (t))
      set_used_flags (DECL_RTL (t));

  /* Now process sub-blocks.  */
  for (t = BLOCK_SUBBLOCKS (blk); t; t = BLOCK_CHAIN (t))
    set_used_decls (t);
}

/* Mark ORIG as in use, and return a copy of it if it was already in use.
   Recursively does the same for subexpressions.  Uses
   copy_rtx_if_shared_1 to reduce stack space.  */

rtx
copy_rtx_if_shared (rtx orig)
{
  copy_rtx_if_shared_1 (&orig);
  return orig;
}

/* Mark *ORIG1 as in use, and set it to a copy of it if it was already in
   use.  Recursively does the same for subexpressions.  */

static void
copy_rtx_if_shared_1 (rtx *orig1)
{
  rtx x;
  int i;
  enum rtx_code code;
  rtx *last_ptr;
  const char *format_ptr;
  int copied = 0;
  int length;

  /* Repeat is used to turn tail-recursion into iteration.  */
repeat:
  x = *orig1;

  if (x == 0)
    return;

  code = GET_CODE (x);

  /* These types may be freely shared.  */

  switch (code)
    {
    case REG:
    case DEBUG_EXPR:
    case VALUE:
    CASE_CONST_ANY:
    case SYMBOL_REF:
    case LABEL_REF:
    case CODE_LABEL:
    case PC:
    case CC0:
    case RETURN:
    case SIMPLE_RETURN:
    case SCRATCH:
      /* SCRATCH must be shared because they represent distinct values.  */
      return;
    case CLOBBER:
      /* Share clobbers of hard registers (like cc0), but do not share pseudo reg
         clobbers or clobbers of hard registers that originated as pseudos.
         This is needed to allow safe register renaming.  */
      if (REG_P (XEXP (x, 0)) && REGNO (XEXP (x, 0)) < FIRST_PSEUDO_REGISTER
	  && ORIGINAL_REGNO (XEXP (x, 0)) == REGNO (XEXP (x, 0)))
	return;
      break;

    case CONST:
      if (shared_const_p (x))
	return;
      break;

    case DEBUG_INSN:
    case INSN:
    case JUMP_INSN:
    case CALL_INSN:
    case NOTE:
    case BARRIER:
      /* The chain of insns is not being copied.  */
      return;

    default:
      break;
    }

  /* This rtx may not be shared.  If it has already been seen,
     replace it with a copy of itself.  */

  if (RTX_FLAG (x, used))
    {
      x = shallow_copy_rtx (x);
      copied = 1;
    }
  RTX_FLAG (x, used) = 1;

  /* Now scan the subexpressions recursively.
     We can store any replaced subexpressions directly into X
     since we know X is not shared!  Any vectors in X
     must be copied if X was copied.  */

  format_ptr = GET_RTX_FORMAT (code);
  length = GET_RTX_LENGTH (code);
  last_ptr = NULL;

  for (i = 0; i < length; i++)
    {
      switch (*format_ptr++)
	{
	case 'e':
          if (last_ptr)
            copy_rtx_if_shared_1 (last_ptr);
	  last_ptr = &XEXP (x, i);
	  break;

	case 'E':
	  if (XVEC (x, i) != NULL)
	    {
	      int j;
	      int len = XVECLEN (x, i);

              /* Copy the vector iff I copied the rtx and the length
		 is nonzero.  */
	      if (copied && len > 0)
		XVEC (x, i) = gen_rtvec_v (len, XVEC (x, i)->elem);

              /* Call recursively on all inside the vector.  */
	      for (j = 0; j < len; j++)
                {
		  if (last_ptr)
		    copy_rtx_if_shared_1 (last_ptr);
                  last_ptr = &XVECEXP (x, i, j);
                }
	    }
	  break;
	}
    }
  *orig1 = x;
  if (last_ptr)
    {
      orig1 = last_ptr;
      goto repeat;
    }
  return;
}

/* Set the USED bit in X and its non-shareable subparts to FLAG.  */

static void
mark_used_flags (rtx x, int flag)
{
  int i, j;
  enum rtx_code code;
  const char *format_ptr;
  int length;

  /* Repeat is used to turn tail-recursion into iteration.  */
repeat:
  if (x == 0)
    return;

  code = GET_CODE (x);

  /* These types may be freely shared so we needn't do any resetting
     for them.  */

  switch (code)
    {
    case REG:
    case DEBUG_EXPR:
    case VALUE:
    CASE_CONST_ANY:
    case SYMBOL_REF:
    case CODE_LABEL:
    case PC:
    case CC0:
    case RETURN:
    case SIMPLE_RETURN:
      return;

    case DEBUG_INSN:
    case INSN:
    case JUMP_INSN:
    case CALL_INSN:
    case NOTE:
    case LABEL_REF:
    case BARRIER:
      /* The chain of insns is not being copied.  */
      return;

    default:
      break;
    }

  RTX_FLAG (x, used) = flag;

  format_ptr = GET_RTX_FORMAT (code);
  length = GET_RTX_LENGTH (code);

  for (i = 0; i < length; i++)
    {
      switch (*format_ptr++)
	{
	case 'e':
          if (i == length-1)
            {
              x = XEXP (x, i);
	      goto repeat;
            }
	  mark_used_flags (XEXP (x, i), flag);
	  break;

	case 'E':
	  for (j = 0; j < XVECLEN (x, i); j++)
	    mark_used_flags (XVECEXP (x, i, j), flag);
	  break;
	}
    }
}

/* Clear all the USED bits in X to allow copy_rtx_if_shared to be used
   to look for shared sub-parts.  */

void
reset_used_flags (rtx x)
{
  mark_used_flags (x, 0);
}

/* Set all the USED bits in X to allow copy_rtx_if_shared to be used
   to look for shared sub-parts.  */

void
set_used_flags (rtx x)
{
  mark_used_flags (x, 1);
}

/* Copy X if necessary so that it won't be altered by changes in OTHER.
   Return X or the rtx for the pseudo reg the value of X was copied into.
   OTHER must be valid as a SET_DEST.  */

rtx
make_safe_from (rtx x, rtx other)
{
  while (1)
    switch (GET_CODE (other))
      {
      case SUBREG:
	other = SUBREG_REG (other);
	break;
      case STRICT_LOW_PART:
      case SIGN_EXTEND:
      case ZERO_EXTEND:
	other = XEXP (other, 0);
	break;
      default:
	goto done;
      }
 done:
  if ((MEM_P (other)
       && ! CONSTANT_P (x)
       && !REG_P (x)
       && GET_CODE (x) != SUBREG)
      || (REG_P (other)
	  && (REGNO (other) < FIRST_PSEUDO_REGISTER
	      || reg_mentioned_p (other, x))))
    {
      rtx temp = gen_reg_rtx (GET_MODE (x));
      emit_move_insn (temp, x);
      return temp;
    }
  return x;
}

/* Emission of insns (adding them to the doubly-linked list).  */

/* Return the last insn emitted, even if it is in a sequence now pushed.  */

rtx_insn *
get_last_insn_anywhere (void)
{
  struct sequence_stack *stack;
  if (get_last_insn ())
    return get_last_insn ();
  for (stack = seq_stack; stack; stack = stack->next)
    if (stack->last != 0)
      return stack->last;
  return 0;
}

/* Return the first nonnote insn emitted in current sequence or current
   function.  This routine looks inside SEQUENCEs.  */

rtx_insn *
get_first_nonnote_insn (void)
{
  rtx_insn *insn = get_insns ();

  if (insn)
    {
      if (NOTE_P (insn))
	for (insn = next_insn (insn);
	     insn && NOTE_P (insn);
	     insn = next_insn (insn))
	  continue;
      else
	{
	  if (NONJUMP_INSN_P (insn)
	      && GET_CODE (PATTERN (insn)) == SEQUENCE)
	    insn = as_a <rtx_sequence *> (PATTERN (insn))->insn (0);
	}
    }

  return insn;
}

/* Return the last nonnote insn emitted in current sequence or current
   function.  This routine looks inside SEQUENCEs.  */

rtx_insn *
get_last_nonnote_insn (void)
{
  rtx_insn *insn = get_last_insn ();

  if (insn)
    {
      if (NOTE_P (insn))
	for (insn = previous_insn (insn);
	     insn && NOTE_P (insn);
	     insn = previous_insn (insn))
	  continue;
      else
	{
	  if (NONJUMP_INSN_P (insn))
	    if (rtx_sequence *seq = dyn_cast <rtx_sequence *> (PATTERN (insn)))
	      insn = seq->insn (seq->len () - 1);
	}
    }

  return insn;
}

/* Return the number of actual (non-debug) insns emitted in this
   function.  */

int
get_max_insn_count (void)
{
  int n = cur_insn_uid;

  /* The table size must be stable across -g, to avoid codegen
     differences due to debug insns, and not be affected by
     -fmin-insn-uid, to avoid excessive table size and to simplify
     debugging of -fcompare-debug failures.  */
  if (cur_debug_insn_uid > MIN_NONDEBUG_INSN_UID)
    n -= cur_debug_insn_uid;
  else
    n -= MIN_NONDEBUG_INSN_UID;

  return n;
}


/* Return the next insn.  If it is a SEQUENCE, return the first insn
   of the sequence.  */

rtx_insn *
next_insn (rtx_insn *insn)
{
  if (insn)
    {
      insn = NEXT_INSN (insn);
      if (insn && NONJUMP_INSN_P (insn)
	  && GET_CODE (PATTERN (insn)) == SEQUENCE)
	insn = as_a <rtx_sequence *> (PATTERN (insn))->insn (0);
    }

  return insn;
}

/* Return the previous insn.  If it is a SEQUENCE, return the last insn
   of the sequence.  */

rtx_insn *
previous_insn (rtx_insn *insn)
{
  if (insn)
    {
      insn = PREV_INSN (insn);
      if (insn && NONJUMP_INSN_P (insn))
	if (rtx_sequence *seq = dyn_cast <rtx_sequence *> (PATTERN (insn)))
	  insn = seq->insn (seq->len () - 1);
    }

  return insn;
}

/* Return the next insn after INSN that is not a NOTE.  This routine does not
   look inside SEQUENCEs.  */

rtx_insn *
next_nonnote_insn (rtx uncast_insn)
{
  rtx_insn *insn = safe_as_a <rtx_insn *> (uncast_insn);
  while (insn)
    {
      insn = NEXT_INSN (insn);
      if (insn == 0 || !NOTE_P (insn))
	break;
    }

  return insn;
}

/* Return the next insn after INSN that is not a NOTE, but stop the
   search before we enter another basic block.  This routine does not