* tree.h: Fix typo in comment.

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

/* Expands front end tree to back end RTL for GCC.
   Copyright (C) 1987, 1988, 1989, 1991, 1992, 1993, 1994, 1995, 1996, 1997,
   1998, 1999, 2000, 2001, 2002, 2003, 2004 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 2, 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 COPYING.  If not, write to the Free
Software Foundation, 59 Temple Place - Suite 330, Boston, MA
02111-1307, USA.  */

/* This file handles the generation of rtl code from tree structure
   at the level of the function as a whole.
   It creates the rtl expressions for parameters and auto variables
   and has full responsibility for allocating stack slots.

   `expand_function_start' is called at the beginning of a function,
   before the function body is parsed, and `expand_function_end' is
   called after parsing the body.

   Call `assign_stack_local' to allocate a stack slot for a local variable.
   This is usually done during the RTL generation for the function body,
   but it can also be done in the reload pass when a pseudo-register does
   not get a hard register.  */

#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "rtl.h"
#include "tree.h"
#include "flags.h"
#include "except.h"
#include "function.h"
#include "expr.h"
#include "optabs.h"
#include "libfuncs.h"
#include "regs.h"
#include "hard-reg-set.h"
#include "insn-config.h"
#include "recog.h"
#include "output.h"
#include "basic-block.h"
#include "toplev.h"
#include "hashtab.h"
#include "ggc.h"
#include "tm_p.h"
#include "integrate.h"
#include "langhooks.h"
#include "target.h"
#include "cfglayout.h"

#ifndef LOCAL_ALIGNMENT
#define LOCAL_ALIGNMENT(TYPE, ALIGNMENT) ALIGNMENT
#endif

#ifndef STACK_ALIGNMENT_NEEDED
#define STACK_ALIGNMENT_NEEDED 1
#endif

#define STACK_BYTES (STACK_BOUNDARY / BITS_PER_UNIT)

/* Some systems use __main in a way incompatible with its use in gcc, in these
   cases use the macros NAME__MAIN to give a quoted symbol and SYMBOL__MAIN to
   give the same symbol without quotes for an alternative entry point.  You
   must define both, or neither.  */
#ifndef NAME__MAIN
#define NAME__MAIN "__main"
#endif

/* Round a value to the lowest integer less than it that is a multiple of
   the required alignment.  Avoid using division in case the value is
   negative.  Assume the alignment is a power of two.  */
#define FLOOR_ROUND(VALUE,ALIGN) ((VALUE) & ~((ALIGN) - 1))

/* Similar, but round to the next highest integer that meets the
   alignment.  */
#define CEIL_ROUND(VALUE,ALIGN) (((VALUE) + (ALIGN) - 1) & ~((ALIGN)- 1))

/* Nonzero if function being compiled doesn't contain any calls
   (ignoring the prologue and epilogue).  This is set prior to
   local register allocation and is valid for the remaining
   compiler passes.  */
int current_function_is_leaf;

/* Nonzero if function being compiled doesn't modify the stack pointer
   (ignoring the prologue and epilogue).  This is only valid after
   life_analysis has run.  */
int current_function_sp_is_unchanging;

/* Nonzero if the function being compiled is a leaf function which only
   uses leaf registers.  This is valid after reload (specifically after
   sched2) and is useful only if the port defines LEAF_REGISTERS.  */
int current_function_uses_only_leaf_regs;

/* Nonzero once virtual register instantiation has been done.
   assign_stack_local uses frame_pointer_rtx when this is nonzero.
   calls.c:emit_library_call_value_1 uses it to set up
   post-instantiation libcalls.  */
int virtuals_instantiated;

/* Assign unique numbers to labels generated for profiling, debugging, etc.  */
static GTY(()) int funcdef_no;

/* These variables hold pointers to functions to create and destroy
   target specific, per-function data structures.  */
struct machine_function * (*init_machine_status) (void);

/* The currently compiled function.  */
struct function *cfun = 0;

/* These arrays record the INSN_UIDs of the prologue and epilogue insns.  */
static GTY(()) varray_type prologue;
static GTY(()) varray_type epilogue;

/* Array of INSN_UIDs to hold the INSN_UIDs for each sibcall epilogue
   in this function.  */
static GTY(()) varray_type sibcall_epilogue;
\f
/* In order to evaluate some expressions, such as function calls returning
   structures in memory, we need to temporarily allocate stack locations.
   We record each allocated temporary in the following structure.

   Associated with each temporary slot is a nesting level.  When we pop up
   one level, all temporaries associated with the previous level are freed.
   Normally, all temporaries are freed after the execution of the statement
   in which they were created.  However, if we are inside a ({...}) grouping,
   the result may be in a temporary and hence must be preserved.  If the
   result could be in a temporary, we preserve it if we can determine which
   one it is in.  If we cannot determine which temporary may contain the
   result, all temporaries are preserved.  A temporary is preserved by
   pretending it was allocated at the previous nesting level.

   Automatic variables are also assigned temporary slots, at the nesting
   level where they are defined.  They are marked a "kept" so that
   free_temp_slots will not free them.  */

struct temp_slot GTY(())
{
  /* Points to next temporary slot.  */
  struct temp_slot *next;
  /* Points to previous temporary slot.  */
  struct temp_slot *prev;

  /* The rtx to used to reference the slot.  */
  rtx slot;
  /* The rtx used to represent the address if not the address of the
     slot above.  May be an EXPR_LIST if multiple addresses exist.  */
  rtx address;
  /* The alignment (in bits) of the slot.  */
  unsigned int align;
  /* The size, in units, of the slot.  */
  HOST_WIDE_INT size;
  /* The type of the object in the slot, or zero if it doesn't correspond
     to a type.  We use this to determine whether a slot can be reused.
     It can be reused if objects of the type of the new slot will always
     conflict with objects of the type of the old slot.  */
  tree type;
  /* Nonzero if this temporary is currently in use.  */
  char in_use;
  /* Nonzero if this temporary has its address taken.  */
  char addr_taken;
  /* Nesting level at which this slot is being used.  */
  int level;
  /* Nonzero if this should survive a call to free_temp_slots.  */
  int keep;
  /* The offset of the slot from the frame_pointer, including extra space
     for alignment.  This info is for combine_temp_slots.  */
  HOST_WIDE_INT base_offset;
  /* The size of the slot, including extra space for alignment.  This
     info is for combine_temp_slots.  */
  HOST_WIDE_INT full_size;
};
\f
/* Forward declarations.  */

static rtx assign_stack_local_1 (enum machine_mode, HOST_WIDE_INT, int,
                                 struct function *);
static struct temp_slot *find_temp_slot_from_address (rtx);
static void instantiate_decls (tree, int);
static void instantiate_decls_1 (tree, int);
static void instantiate_decl (rtx, HOST_WIDE_INT, int);
static rtx instantiate_new_reg (rtx, HOST_WIDE_INT *);
static int instantiate_virtual_regs_1 (rtx *, rtx, int);
static void pad_to_arg_alignment (struct args_size *, int, struct args_size *);
static void pad_below (struct args_size *, enum machine_mode, tree);
static void reorder_blocks_1 (rtx, tree, varray_type *);
static void reorder_fix_fragments (tree);
static int all_blocks (tree, tree *);
static tree *get_block_vector (tree, int *);
extern tree debug_find_var_in_block_tree (tree, tree);
/* We always define `record_insns' even if it's not used so that we
   can always export `prologue_epilogue_contains'.  */
static void record_insns (rtx, varray_type *) ATTRIBUTE_UNUSED;
static int contains (rtx, varray_type);
#ifdef HAVE_return
static void emit_return_into_block (basic_block, rtx);
#endif
static void purge_single_hard_subreg_set (rtx);
#if defined(HAVE_epilogue) && defined(INCOMING_RETURN_ADDR_RTX)
static rtx keep_stack_depressed (rtx);
#endif
static void prepare_function_start (tree);
static void do_clobber_return_reg (rtx, void *);
static void do_use_return_reg (rtx, void *);
static void instantiate_virtual_regs_lossage (rtx);
static void set_insn_locators (rtx, int) ATTRIBUTE_UNUSED;
\f
/* Pointer to chain of `struct function' for containing functions.  */
struct function *outer_function_chain;

/* Given a function decl for a containing function,
   return the `struct function' for it.  */

struct function *
find_function_data (tree decl)
{
  struct function *p;

  for (p = outer_function_chain; p; p = p->outer)
    if (p->decl == decl)
      return p;

  abort ();
}

/* Save the current context for compilation of a nested function.
   This is called from language-specific code.  The caller should use
   the enter_nested langhook to save any language-specific state,
   since this function knows only about language-independent
   variables.  */

void
push_function_context_to (tree context)
{
  struct function *p;

  if (context)
    {
      if (context == current_function_decl)
        cfun->contains_functions = 1;
      else
        {
          struct function *containing = find_function_data (context);
          containing->contains_functions = 1;
        }
    }

  if (cfun == 0)
    init_dummy_function_start ();
  p = cfun;

  p->outer = outer_function_chain;
  outer_function_chain = p;

  lang_hooks.function.enter_nested (p);

  cfun = 0;
}

void
push_function_context (void)
{
  push_function_context_to (current_function_decl);
}

/* Restore the last saved context, at the end of a nested function.
   This function is called from language-specific code.  */

void
pop_function_context_from (tree context ATTRIBUTE_UNUSED)
{
  struct function *p = outer_function_chain;

  cfun = p;
  outer_function_chain = p->outer;

  current_function_decl = p->decl;
  reg_renumber = 0;

  restore_emit_status (p);

  lang_hooks.function.leave_nested (p);

  /* Reset variables that have known state during rtx generation.  */
  rtx_equal_function_value_matters = 1;
  virtuals_instantiated = 0;
  generating_concat_p = 1;
}

void
pop_function_context (void)
{
  pop_function_context_from (current_function_decl);
}

/* Clear out all parts of the state in F that can safely be discarded
   after the function has been parsed, but not compiled, to let
   garbage collection reclaim the memory.  */

void
free_after_parsing (struct function *f)
{
  /* f->expr->forced_labels is used by code generation.  */
  /* f->emit->regno_reg_rtx is used by code generation.  */
  /* f->varasm is used by code generation.  */
  /* f->eh->eh_return_stub_label is used by code generation.  */

  lang_hooks.function.final (f);
  f->stmt = NULL;
}

/* Clear out all parts of the state in F that can safely be discarded
   after the function has been compiled, to let garbage collection
   reclaim the memory.  */

void
free_after_compilation (struct function *f)
{
  f->eh = NULL;
  f->expr = NULL;
  f->emit = NULL;
  f->varasm = NULL;
  f->machine = NULL;

  f->x_avail_temp_slots = NULL;
  f->x_used_temp_slots = NULL;
  f->arg_offset_rtx = NULL;
  f->return_rtx = NULL;
  f->internal_arg_pointer = NULL;
  f->x_nonlocal_goto_handler_labels = NULL;
  f->x_return_label = NULL;
  f->x_naked_return_label = NULL;
  f->x_stack_slot_list = NULL;
  f->x_tail_recursion_reentry = NULL;
  f->x_arg_pointer_save_area = NULL;
  f->x_parm_birth_insn = NULL;
  f->original_arg_vector = NULL;
  f->original_decl_initial = NULL;
  f->epilogue_delay_list = NULL;
}
\f
/* Allocate fixed slots in the stack frame of the current function.  */

/* Return size needed for stack frame based on slots so far allocated in
   function F.
   This size counts from zero.  It is not rounded to PREFERRED_STACK_BOUNDARY;
   the caller may have to do that.  */

HOST_WIDE_INT
get_func_frame_size (struct function *f)
{
#ifdef FRAME_GROWS_DOWNWARD
  return -f->x_frame_offset;
#else
  return f->x_frame_offset;
#endif
}

/* Return size needed for stack frame based on slots so far allocated.
   This size counts from zero.  It is not rounded to PREFERRED_STACK_BOUNDARY;
   the caller may have to do that.  */
HOST_WIDE_INT
get_frame_size (void)
{
  return get_func_frame_size (cfun);
}

/* Allocate a stack slot of SIZE bytes and return a MEM rtx for it
   with machine mode MODE.

   ALIGN controls the amount of alignment for the address of the slot:
   0 means according to MODE,
   -1 means use BIGGEST_ALIGNMENT and round size to multiple of that,
   -2 means use BITS_PER_UNIT,
   positive specifies alignment boundary in bits.

   We do not round to stack_boundary here.

   FUNCTION specifies the function to allocate in.  */

static rtx
assign_stack_local_1 (enum machine_mode mode, HOST_WIDE_INT size, int align,
                      struct function *function)
{
  rtx x, addr;
  int bigend_correction = 0;
  int alignment;
  int frame_off, frame_alignment, frame_phase;

  if (align == 0)
    {
      tree type;

      if (mode == BLKmode)
        alignment = BIGGEST_ALIGNMENT;
      else
        alignment = GET_MODE_ALIGNMENT (mode);

      /* Allow the target to (possibly) increase the alignment of this
         stack slot.  */
      type = lang_hooks.types.type_for_mode (mode, 0);
      if (type)
        alignment = LOCAL_ALIGNMENT (type, alignment);

      alignment /= BITS_PER_UNIT;
    }
  else if (align == -1)
    {
      alignment = BIGGEST_ALIGNMENT / BITS_PER_UNIT;
      size = CEIL_ROUND (size, alignment);
    }
  else if (align == -2)
    alignment = 1; /* BITS_PER_UNIT / BITS_PER_UNIT */
  else
    alignment = align / BITS_PER_UNIT;

#ifdef FRAME_GROWS_DOWNWARD
  function->x_frame_offset -= size;
#endif

  /* Ignore alignment we can't do with expected alignment of the boundary.  */
  if (alignment * BITS_PER_UNIT > PREFERRED_STACK_BOUNDARY)
    alignment = PREFERRED_STACK_BOUNDARY / BITS_PER_UNIT;

  if (function->stack_alignment_needed < alignment * BITS_PER_UNIT)
    function->stack_alignment_needed = alignment * BITS_PER_UNIT;

  /* Calculate how many bytes the start of local variables is off from
     stack alignment.  */
  frame_alignment = PREFERRED_STACK_BOUNDARY / BITS_PER_UNIT;
  frame_off = STARTING_FRAME_OFFSET % frame_alignment;
  frame_phase = frame_off ? frame_alignment - frame_off : 0;

  /* Round the frame offset to the specified alignment.  The default is
     to always honor requests to align the stack but a port may choose to
     do its own stack alignment by defining STACK_ALIGNMENT_NEEDED.  */
  if (STACK_ALIGNMENT_NEEDED
      || mode != BLKmode
      || size != 0)
    {
      /*  We must be careful here, since FRAME_OFFSET might be negative and
          division with a negative dividend isn't as well defined as we might
          like.  So we instead assume that ALIGNMENT is a power of two and
          use logical operations which are unambiguous.  */
#ifdef FRAME_GROWS_DOWNWARD
      function->x_frame_offset
        = (FLOOR_ROUND (function->x_frame_offset - frame_phase, alignment)
           + frame_phase);
#else
      function->x_frame_offset
        = (CEIL_ROUND (function->x_frame_offset - frame_phase, alignment)
           + frame_phase);
#endif
    }

  /* On a big-endian machine, if we are allocating more space than we will use,
     use the least significant bytes of those that are allocated.  */
  if (BYTES_BIG_ENDIAN && mode != BLKmode)
    bigend_correction = size - GET_MODE_SIZE (mode);

  /* If we have already instantiated virtual registers, return the actual
     address relative to the frame pointer.  */
  if (function == cfun && virtuals_instantiated)
    addr = plus_constant (frame_pointer_rtx,
                          trunc_int_for_mode
                          (frame_offset + bigend_correction
                           + STARTING_FRAME_OFFSET, Pmode));
  else
    addr = plus_constant (virtual_stack_vars_rtx,
                          trunc_int_for_mode
                          (function->x_frame_offset + bigend_correction,
                           Pmode));

#ifndef FRAME_GROWS_DOWNWARD
  function->x_frame_offset += size;
#endif

  x = gen_rtx_MEM (mode, addr);

  function->x_stack_slot_list
    = gen_rtx_EXPR_LIST (VOIDmode, x, function->x_stack_slot_list);

  return x;
}

/* Wrapper around assign_stack_local_1;  assign a local stack slot for the
   current function.  */

rtx
assign_stack_local (enum machine_mode mode, HOST_WIDE_INT size, int align)
{
  return assign_stack_local_1 (mode, size, align, cfun);
}

\f
/* Removes temporary slot TEMP from LIST.  */

static void
cut_slot_from_list (struct temp_slot *temp, struct temp_slot **list)
{
  if (temp->next)
    temp->next->prev = temp->prev;
  if (temp->prev)
    temp->prev->next = temp->next;
  else
    *list = temp->next;

  temp->prev = temp->next = NULL;
}

/* Inserts temporary slot TEMP to LIST.  */

static void
insert_slot_to_list (struct temp_slot *temp, struct temp_slot **list)
{
  temp->next = *list;
  if (*list)
    (*list)->prev = temp;
  temp->prev = NULL;
  *list = temp;
}

/* Returns the list of used temp slots at LEVEL.  */

static struct temp_slot **
temp_slots_at_level (int level)
{
  level++;

  if (!used_temp_slots)
    VARRAY_GENERIC_PTR_INIT (used_temp_slots, 3, "used_temp_slots");

  while (level >= (int) VARRAY_ACTIVE_SIZE (used_temp_slots))
    VARRAY_PUSH_GENERIC_PTR (used_temp_slots, NULL);

  return (struct temp_slot **) &VARRAY_GENERIC_PTR (used_temp_slots, level);
}

/* Returns the maximal temporary slot level.  */

static int
max_slot_level (void)
{
  if (!used_temp_slots)
    return -1;

  return VARRAY_ACTIVE_SIZE (used_temp_slots) - 1;
}

/* Moves temporary slot TEMP to LEVEL.  */

static void
move_slot_to_level (struct temp_slot *temp, int level)
{
  cut_slot_from_list (temp, temp_slots_at_level (temp->level));
  insert_slot_to_list (temp, temp_slots_at_level (level));
  temp->level = level;
}

/* Make temporary slot TEMP available.  */

static void
make_slot_available (struct temp_slot *temp)
{
  cut_slot_from_list (temp, temp_slots_at_level (temp->level));
  insert_slot_to_list (temp, &avail_temp_slots);
  temp->in_use = 0;
  temp->level = -1;
}
\f
/* Allocate a temporary stack slot and record it for possible later
   reuse.

   MODE is the machine mode to be given to the returned rtx.

   SIZE is the size in units of the space required.  We do no rounding here
   since assign_stack_local will do any required rounding.

   KEEP is 1 if this slot is to be retained after a call to
   free_temp_slots.  Automatic variables for a block are allocated
   with this flag.  KEEP is 2 if we allocate a longer term temporary,
   whose lifetime is controlled by CLEANUP_POINT_EXPRs.  KEEP is 3
   if we are to allocate something at an inner level to be treated as
   a variable in the block (e.g., a SAVE_EXPR).

   TYPE is the type that will be used for the stack slot.  */

rtx
assign_stack_temp_for_type (enum machine_mode mode, HOST_WIDE_INT size, int keep,
                            tree type)
{
  unsigned int align;
  struct temp_slot *p, *best_p = 0, *selected = NULL, **pp;
  rtx slot;

  /* If SIZE is -1 it means that somebody tried to allocate a temporary
     of a variable size.  */
  if (size == -1)
    abort ();

  if (mode == BLKmode)
    align = BIGGEST_ALIGNMENT;
  else
    align = GET_MODE_ALIGNMENT (mode);

  if (! type)
    type = lang_hooks.types.type_for_mode (mode, 0);

  if (type)
    align = LOCAL_ALIGNMENT (type, align);

  /* Try to find an available, already-allocated temporary of the proper
     mode which meets the size and alignment requirements.  Choose the
     smallest one with the closest alignment.  */
  for (p = avail_temp_slots; p; p = p->next)
    {
      if (p->align >= align && p->size >= size && GET_MODE (p->slot) == mode
          && objects_must_conflict_p (p->type, type)
          && (best_p == 0 || best_p->size > p->size
              || (best_p->size == p->size && best_p->align > p->align)))
        {
          if (p->align == align && p->size == size)
            {
              selected = p;
              cut_slot_from_list (selected, &avail_temp_slots);
              best_p = 0;
              break;
            }
          best_p = p;
        }
    }

  /* Make our best, if any, the one to use.  */
  if (best_p)
    {
      selected = best_p;
      cut_slot_from_list (selected, &avail_temp_slots);

      /* If there are enough aligned bytes left over, make them into a new
         temp_slot so that the extra bytes don't get wasted.  Do this only
         for BLKmode slots, so that we can be sure of the alignment.  */
      if (GET_MODE (best_p->slot) == BLKmode)
        {
          int alignment = best_p->align / BITS_PER_UNIT;
          HOST_WIDE_INT rounded_size = CEIL_ROUND (size, alignment);

          if (best_p->size - rounded_size >= alignment)
            {
              p = ggc_alloc (sizeof (struct temp_slot));
              p->in_use = p->addr_taken = 0;
              p->size = best_p->size - rounded_size;
              p->base_offset = best_p->base_offset + rounded_size;
              p->full_size = best_p->full_size - rounded_size;
              p->slot = gen_rtx_MEM (BLKmode,
                                     plus_constant (XEXP (best_p->slot, 0),
                                                    rounded_size));
              p->align = best_p->align;
              p->address = 0;
              p->type = best_p->type;
              insert_slot_to_list (p, &avail_temp_slots);

              stack_slot_list = gen_rtx_EXPR_LIST (VOIDmode, p->slot,
                                                   stack_slot_list);

              best_p->size = rounded_size;
              best_p->full_size = rounded_size;
            }
        }
    }

  /* If we still didn't find one, make a new temporary.  */
  if (selected == 0)
    {
      HOST_WIDE_INT frame_offset_old = frame_offset;

      p = ggc_alloc (sizeof (struct temp_slot));

      /* We are passing an explicit alignment request to assign_stack_local.
         One side effect of that is assign_stack_local will not round SIZE
         to ensure the frame offset remains suitably aligned.

         So for requests which depended on the rounding of SIZE, we go ahead
         and round it now.  We also make sure ALIGNMENT is at least
         BIGGEST_ALIGNMENT.  */
      if (mode == BLKmode && align < BIGGEST_ALIGNMENT)
        abort ();
      p->slot = assign_stack_local (mode,
                                    (mode == BLKmode
                                     ? CEIL_ROUND (size, (int) align / BITS_PER_UNIT)
                                     : size),
                                    align);

      p->align = align;

      /* The following slot size computation is necessary because we don't
         know the actual size of the temporary slot until assign_stack_local
         has performed all the frame alignment and size rounding for the
         requested temporary.  Note that extra space added for alignment
         can be either above or below this stack slot depending on which
         way the frame grows.  We include the extra space if and only if it
         is above this slot.  */
#ifdef FRAME_GROWS_DOWNWARD
      p->size = frame_offset_old - frame_offset;
#else
      p->size = size;
#endif

      /* Now define the fields used by combine_temp_slots.  */
#ifdef FRAME_GROWS_DOWNWARD
      p->base_offset = frame_offset;
      p->full_size = frame_offset_old - frame_offset;
#else
      p->base_offset = frame_offset_old;
      p->full_size = frame_offset - frame_offset_old;
#endif
      p->address = 0;

      selected = p;
    }

  p = selected;
  p->in_use = 1;
  p->addr_taken = 0;
  p->type = type;

  if (keep == 2)
    {
      p->level = target_temp_slot_level;
      p->keep = 1;
    }
  else if (keep == 3)
    {
      p->level = var_temp_slot_level;
      p->keep = 0;
    }
  else
    {
      p->level = temp_slot_level;
      p->keep = keep;
    }

  pp = temp_slots_at_level (p->level);
  insert_slot_to_list (p, pp);

  /* Create a new MEM rtx to avoid clobbering MEM flags of old slots.  */
  slot = gen_rtx_MEM (mode, XEXP (p->slot, 0));
  stack_slot_list = gen_rtx_EXPR_LIST (VOIDmode, slot, stack_slot_list);

  /* If we know the alias set for the memory that will be used, use
     it.  If there's no TYPE, then we don't know anything about the
     alias set for the memory.  */
  set_mem_alias_set (slot, type ? get_alias_set (type) : 0);
  set_mem_align (slot, align);

  /* If a type is specified, set the relevant flags.  */
  if (type != 0)
    {
      RTX_UNCHANGING_P (slot) = (lang_hooks.honor_readonly
                                 && TYPE_READONLY (type));
      MEM_VOLATILE_P (slot) = TYPE_VOLATILE (type);
      MEM_SET_IN_STRUCT_P (slot, AGGREGATE_TYPE_P (type));
    }

  return slot;
}

/* Allocate a temporary stack slot and record it for possible later
   reuse.  First three arguments are same as in preceding function.  */

rtx
assign_stack_temp (enum machine_mode mode, HOST_WIDE_INT size, int keep)
{
  return assign_stack_temp_for_type (mode, size, keep, NULL_TREE);
}
\f
/* Assign a temporary.
   If TYPE_OR_DECL is a decl, then we are doing it on behalf of the decl
   and so that should be used in error messages.  In either case, we
   allocate of the given type.
   KEEP is as for assign_stack_temp.
   MEMORY_REQUIRED is 1 if the result must be addressable stack memory;
   it is 0 if a register is OK.
   DONT_PROMOTE is 1 if we should not promote values in register
   to wider modes.  */

rtx
assign_temp (tree type_or_decl, int keep, int memory_required,
             int dont_promote ATTRIBUTE_UNUSED)
{
  tree type, decl;
  enum machine_mode mode;
#ifdef PROMOTE_MODE
  int unsignedp;
#endif

  if (DECL_P (type_or_decl))
    decl = type_or_decl, type = TREE_TYPE (decl);
  else
    decl = NULL, type = type_or_decl;

  mode = TYPE_MODE (type);
#ifdef PROMOTE_MODE
  unsignedp = TYPE_UNSIGNED (type);
#endif

  if (mode == BLKmode || memory_required)
    {
      HOST_WIDE_INT size = int_size_in_bytes (type);
      tree size_tree;
      rtx tmp;

      /* Zero sized arrays are GNU C extension.  Set size to 1 to avoid
         problems with allocating the stack space.  */
      if (size == 0)
        size = 1;

      /* Unfortunately, we don't yet know how to allocate variable-sized
         temporaries.  However, sometimes we have a fixed upper limit on
         the size (which is stored in TYPE_ARRAY_MAX_SIZE) and can use that
         instead.  This is the case for Chill variable-sized strings.  */
      if (size == -1 && TREE_CODE (type) == ARRAY_TYPE
          && TYPE_ARRAY_MAX_SIZE (type) != NULL_TREE
          && host_integerp (TYPE_ARRAY_MAX_SIZE (type), 1))
        size = tree_low_cst (TYPE_ARRAY_MAX_SIZE (type), 1);

      /* If we still haven't been able to get a size, see if the language
         can compute a maximum size.  */
      if (size == -1
          && (size_tree = lang_hooks.types.max_size (type)) != 0
          && host_integerp (size_tree, 1))
        size = tree_low_cst (size_tree, 1);

      /* The size of the temporary may be too large to fit into an integer.  */
      /* ??? Not sure this should happen except for user silliness, so limit
         this to things that aren't compiler-generated temporaries.  The
         rest of the time we'll abort in assign_stack_temp_for_type.  */
      if (decl && size == -1
          && TREE_CODE (TYPE_SIZE_UNIT (type)) == INTEGER_CST)
        {
          error ("%Jsize of variable '%D' is too large", decl, decl);
          size = 1;
        }

      tmp = assign_stack_temp_for_type (mode, size, keep, type);
      return tmp;
    }

#ifdef PROMOTE_MODE
  if (! dont_promote)
    mode = promote_mode (type, mode, &unsignedp, 0);
#endif

  return gen_reg_rtx (mode);
}
\f
/* Combine temporary stack slots which are adjacent on the stack.

   This allows for better use of already allocated stack space.  This is only
   done for BLKmode slots because we can be sure that we won't have alignment
   problems in this case.  */

void
combine_temp_slots (void)
{
  struct temp_slot *p, *q, *next, *next_q;
  int num_slots;

  /* We can't combine slots, because the information about which slot
     is in which alias set will be lost.  */
  if (flag_strict_aliasing)
    return;

  /* If there are a lot of temp slots, don't do anything unless
     high levels of optimization.  */
  if (! flag_expensive_optimizations)
    for (p = avail_temp_slots, num_slots = 0; p; p = p->next, num_slots++)
      if (num_slots > 100 || (num_slots > 10 && optimize == 0))
        return;

  for (p = avail_temp_slots; p; p = next)
    {
      int delete_p = 0;

      next = p->next;

      if (GET_MODE (p->slot) != BLKmode)
        continue;

      for (q = p->next; q; q = next_q)
        {
          int delete_q = 0;

          next_q = q->next;

          if (GET_MODE (q->slot) != BLKmode)
            continue;

          if (p->base_offset + p->full_size == q->base_offset)
            {
              /* Q comes after P; combine Q into P.  */
              p->size += q->size;
              p->full_size += q->full_size;
              delete_q = 1;
            }
          else if (q->base_offset + q->full_size == p->base_offset)
            {
              /* P comes after Q; combine P into Q.  */
              q->size += p->size;
              q->full_size += p->full_size;
              delete_p = 1;
              break;
            }
          if (delete_q)
            cut_slot_from_list (q, &avail_temp_slots);
        }

      /* Either delete P or advance past it.  */
      if (delete_p)
        cut_slot_from_list (p, &avail_temp_slots);
    }
}
\f
/* Find the temp slot corresponding to the object at address X.  */

static struct temp_slot *
find_temp_slot_from_address (rtx x)
{
  struct temp_slot *p;
  rtx next;
  int i;

  for (i = max_slot_level (); i >= 0; i--)
    for (p = *temp_slots_at_level (i); p; p = p->next)
      {
        if (XEXP (p->slot, 0) == x
            || p->address == x
            || (GET_CODE (x) == PLUS
                && XEXP (x, 0) == virtual_stack_vars_rtx
                && GET_CODE (XEXP (x, 1)) == CONST_INT
                && INTVAL (XEXP (x, 1)) >= p->base_offset
                && INTVAL (XEXP (x, 1)) < p->base_offset + p->full_size))
          return p;

        else if (p->address != 0 && GET_CODE (p->address) == EXPR_LIST)
          for (next = p->address; next; next = XEXP (next, 1))
            if (XEXP (next, 0) == x)
              return p;
      }

  /* If we have a sum involving a register, see if it points to a temp
     slot.  */
  if (GET_CODE (x) == PLUS && REG_P (XEXP (x, 0))
      && (p = find_temp_slot_from_address (XEXP (x, 0))) != 0)
    return p;
  else if (GET_CODE (x) == PLUS && REG_P (XEXP (x, 1))
           && (p = find_temp_slot_from_address (XEXP (x, 1))) != 0)
    return p;

  return 0;
}

/* Indicate that NEW is an alternate way of referring to the temp slot
   that previously was known by OLD.  */

void
update_temp_slot_address (rtx old, rtx new)
{
  struct temp_slot *p;

  if (rtx_equal_p (old, new))
    return;

  p = find_temp_slot_from_address (old);

  /* If we didn't find one, see if both OLD is a PLUS.  If so, and NEW
     is a register, see if one operand of the PLUS is a temporary
     location.  If so, NEW points into it.  Otherwise, if both OLD and
     NEW are a PLUS and if there is a register in common between them.
     If so, try a recursive call on those values.  */
  if (p == 0)
    {
      if (GET_CODE (old) != PLUS)
        return;

      if (REG_P (new))
        {
          update_temp_slot_address (XEXP (old, 0), new);
          update_temp_slot_address (XEXP (old, 1), new);
          return;
        }
      else if (GET_CODE (new) != PLUS)
        return;

      if (rtx_equal_p (XEXP (old, 0), XEXP (new, 0)))
        update_temp_slot_address (XEXP (old, 1), XEXP (new, 1));
      else if (rtx_equal_p (XEXP (old, 1), XEXP (new, 0)))
        update_temp_slot_address (XEXP (old, 0), XEXP (new, 1));
      else if (rtx_equal_p (XEXP (old, 0), XEXP (new, 1)))
        update_temp_slot_address (XEXP (old, 1), XEXP (new, 0));
      else if (rtx_equal_p (XEXP (old, 1), XEXP (new, 1)))
        update_temp_slot_address (XEXP (old, 0), XEXP (new, 0));

      return;
    }

  /* Otherwise add an alias for the temp's address.  */
  else if (p->address == 0)
    p->address = new;
  else
    {
      if (GET_CODE (p->address) != EXPR_LIST)
        p->address = gen_rtx_EXPR_LIST (VOIDmode, p->address, NULL_RTX);

      p->address = gen_rtx_EXPR_LIST (VOIDmode, new, p->address);
    }
}

/* If X could be a reference to a temporary slot, mark the fact that its
   address was taken.  */

void
mark_temp_addr_taken (rtx x)
{
  struct temp_slot *p;

  if (x == 0)
    return;

  /* If X is not in memory or is at a constant address, it cannot be in
     a temporary slot.  */
  if (!MEM_P (x) || CONSTANT_P (XEXP (x, 0)))
    return;

  p = find_temp_slot_from_address (XEXP (x, 0));
  if (p != 0)
    p->addr_taken = 1;
}

/* If X could be a reference to a temporary slot, mark that slot as
   belonging to the to one level higher than the current level.  If X
   matched one of our slots, just mark that one.  Otherwise, we can't
   easily predict which it is, so upgrade all of them.  Kept slots
   need not be touched.

   This is called when an ({...}) construct occurs and a statement
   returns a value in memory.  */

void
preserve_temp_slots (rtx x)
{
  struct temp_slot *p = 0, *next;

  /* If there is no result, we still might have some objects whose address
     were taken, so we need to make sure they stay around.  */
  if (x == 0)
    {
      for (p = *temp_slots_at_level (temp_slot_level); p; p = next)
        {
          next = p->next;

          if (p->addr_taken)
            move_slot_to_level (p, temp_slot_level - 1);
        }

      return;
    }

  /* If X is a register that is being used as a pointer, see if we have
     a temporary slot we know it points to.  To be consistent with
     the code below, we really should preserve all non-kept slots
     if we can't find a match, but that seems to be much too costly.  */
  if (REG_P (x) && REG_POINTER (x))
    p = find_temp_slot_from_address (x);

  /* If X is not in memory or is at a constant address, it cannot be in
     a temporary slot, but it can contain something whose address was
     taken.  */
  if (p == 0 && (!MEM_P (x) || CONSTANT_P (XEXP (x, 0))))
    {
      for (p = *temp_slots_at_level (temp_slot_level); p; p = next)
        {
          next = p->next;

          if (p->addr_taken)
            move_slot_to_level (p, temp_slot_level - 1);
        }

      return;
    }

  /* First see if we can find a match.  */
  if (p == 0)
    p = find_temp_slot_from_address (XEXP (x, 0));

  if (p != 0)
    {
      /* Move everything at our level whose address was taken to our new
         level in case we used its address.  */
      struct temp_slot *q;

      if (p->level == temp_slot_level)
        {
          for (q = *temp_slots_at_level (temp_slot_level); q; q = next)
            {
              next = q->next;

              if (p != q && q->addr_taken)
                move_slot_to_level (q, temp_slot_level - 1);
            }

          move_slot_to_level (p, temp_slot_level - 1);
          p->addr_taken = 0;
        }
      return;
    }

  /* Otherwise, preserve all non-kept slots at this level.  */
  for (p = *temp_slots_at_level (temp_slot_level); p; p = next)
    {
      next = p->next;

      if (!p->keep)
        move_slot_to_level (p, temp_slot_level - 1);
    }
}

/* Free all temporaries used so far.  This is normally called at the
   end of generating code for a statement.  */

void
free_temp_slots (void)
{
  struct temp_slot *p, *next;

  for (p = *temp_slots_at_level (temp_slot_level); p; p = next)
    {
      next = p->next;

      if (!p->keep)
        make_slot_available (p);
    }

  combine_temp_slots ();
}

/* Push deeper into the nesting level for stack temporaries.  */

void
push_temp_slots (void)
{
  temp_slot_level++;
}

/* Pop a temporary nesting level.  All slots in use in the current level
   are freed.  */

void
pop_temp_slots (void)
{
  struct temp_slot *p, *next;

  for (p = *temp_slots_at_level (temp_slot_level); p; p = next)
    {
      next = p->next;
      make_slot_available (p);
    }

  combine_temp_slots ();

  temp_slot_level--;
}

/* Initialize temporary slots.  */

void
init_temp_slots (void)
{
  /* We have not allocated any temporaries yet.  */
  avail_temp_slots = 0;
  used_temp_slots = 0;
  temp_slot_level = 0;
  var_temp_slot_level = 0;
  target_temp_slot_level = 0;
}
\f
/* These routines are responsible for converting virtual register references
   to the actual hard register references once RTL generation is complete.

   The following four variables are used for communication between the
   routines.  They contain the offsets of the virtual registers from their
   respective hard registers.  */

static int in_arg_offset;
static int var_offset;
static int dynamic_offset;
static int out_arg_offset;
static int cfa_offset;

/* In most machines, the stack pointer register is equivalent to the bottom
   of the stack.  */

#ifndef STACK_POINTER_OFFSET
#define STACK_POINTER_OFFSET    0
#endif

/* If not defined, pick an appropriate default for the offset of dynamically
   allocated memory depending on the value of ACCUMULATE_OUTGOING_ARGS,
   REG_PARM_STACK_SPACE, and OUTGOING_REG_PARM_STACK_SPACE.  */

#ifndef STACK_DYNAMIC_OFFSET

/* The bottom of the stack points to the actual arguments.  If
   REG_PARM_STACK_SPACE is defined, this includes the space for the register
   parameters.  However, if OUTGOING_REG_PARM_STACK space is not defined,
   stack space for register parameters is not pushed by the caller, but
   rather part of the fixed stack areas and hence not included in
   `current_function_outgoing_args_size'.  Nevertheless, we must allow
   for it when allocating stack dynamic objects.  */

#if defined(REG_PARM_STACK_SPACE) && ! defined(OUTGOING_REG_PARM_STACK_SPACE)
#define STACK_DYNAMIC_OFFSET(FNDECL)    \
((ACCUMULATE_OUTGOING_ARGS                                                    \
  ? (current_function_outgoing_args_size + REG_PARM_STACK_SPACE (FNDECL)) : 0)\
 + (STACK_POINTER_OFFSET))                                                    \

#else
#define STACK_DYNAMIC_OFFSET(FNDECL)    \
((ACCUMULATE_OUTGOING_ARGS ? current_function_outgoing_args_size : 0)         \
 + (STACK_POINTER_OFFSET))
#endif
#endif

/* On most machines, the CFA coincides with the first incoming parm.  */

#ifndef ARG_POINTER_CFA_OFFSET
#define ARG_POINTER_CFA_OFFSET(FNDECL) FIRST_PARM_OFFSET (FNDECL)
#endif

\f
/* Convert a SET of a hard subreg to a set of the appropriate hard
   register.  A subroutine of purge_hard_subreg_sets.  */

static void
purge_single_hard_subreg_set (rtx pattern)
{
  rtx reg = SET_DEST (pattern);
  enum machine_mode mode = GET_MODE (SET_DEST (pattern));
  int offset = 0;

  if (GET_CODE (reg) == SUBREG && REG_P (SUBREG_REG (reg))
      && REGNO (SUBREG_REG (reg)) < FIRST_PSEUDO_REGISTER)
    {
      offset = subreg_regno_offset (REGNO (SUBREG_REG (reg)),
                                    GET_MODE (SUBREG_REG (reg)),
                                    SUBREG_BYTE (reg),
                                    GET_MODE (reg));
      reg = SUBREG_REG (reg);
    }


  if (REG_P (reg) && REGNO (reg) < FIRST_PSEUDO_REGISTER)
    {
      reg = gen_rtx_REG (mode, REGNO (reg) + offset);
      SET_DEST (pattern) = reg;
    }
}

/* Eliminate all occurrences of SETs of hard subregs from INSNS.  The
   only such SETs that we expect to see are those left in because
   integrate can't handle sets of parts of a return value register.

   We don't use alter_subreg because we only want to eliminate subregs
   of hard registers.  */

void
purge_hard_subreg_sets (rtx insn)
{
  for (; insn; insn = NEXT_INSN (insn))
    {
      if (INSN_P (insn))
        {
          rtx pattern = PATTERN (insn);
          switch (GET_CODE (pattern))
            {
            case SET:
              if (GET_CODE (SET_DEST (pattern)) == SUBREG)
                purge_single_hard_subreg_set (pattern);
              break;
            case PARALLEL:
              {
                int j;
                for (j = XVECLEN (pattern, 0) - 1; j >= 0; j--)
                  {
                    rtx inner_pattern = XVECEXP (pattern, 0, j);
                    if (GET_CODE (inner_pattern) == SET
                        && GET_CODE (SET_DEST (inner_pattern)) == SUBREG)
                      purge_single_hard_subreg_set (inner_pattern);
                  }
              }
              break;
            default:
              break;
            }
        }
    }
}
\f
/* Pass through the INSNS of function FNDECL and convert virtual register
   references to hard register references.  */

void
instantiate_virtual_regs (void)
{
  rtx insn;

  /* Compute the offsets to use for this function.  */
  in_arg_offset = FIRST_PARM_OFFSET (current_function_decl);
  var_offset = STARTING_FRAME_OFFSET;
  dynamic_offset = STACK_DYNAMIC_OFFSET (current_function_decl);
  out_arg_offset = STACK_POINTER_OFFSET;
  cfa_offset = ARG_POINTER_CFA_OFFSET (current_function_decl);

  /* Scan all variables and parameters of this function.  For each that is
     in memory, instantiate all virtual registers if the result is a valid
     address.  If not, we do it later.  That will handle most uses of virtual
     regs on many machines.  */
  instantiate_decls (current_function_decl, 1);

  /* Initialize recognition, indicating that volatile is OK.  */
  init_recog ();

  /* Scan through all the insns, instantiating every virtual register still
     present.  */
  for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
    if (GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN
        || GET_CODE (insn) == CALL_INSN)
      {
        instantiate_virtual_regs_1 (&PATTERN (insn), insn, 1);
        if (INSN_DELETED_P (insn))
          continue;
        instantiate_virtual_regs_1 (&REG_NOTES (insn), NULL_RTX, 0);
        /* Instantiate any virtual registers in CALL_INSN_FUNCTION_USAGE.  */
        if (GET_CODE (insn) == CALL_INSN)
          instantiate_virtual_regs_1 (&CALL_INSN_FUNCTION_USAGE (insn),
                                      NULL_RTX, 0);

        /* Past this point all ASM statements should match.  Verify that
           to avoid failures later in the compilation process.  */
        if (asm_noperands (PATTERN (insn)) >= 0
            && ! check_asm_operands (PATTERN (insn)))
          instantiate_virtual_regs_lossage (insn);
      }

  /* Now instantiate the remaining register equivalences for debugging info.
     These will not be valid addresses.  */
  instantiate_decls (current_function_decl, 0);

  /* Indicate that, from now on, assign_stack_local should use
     frame_pointer_rtx.  */
  virtuals_instantiated = 1;
}

/* Scan all decls in FNDECL (both variables and parameters) and instantiate
   all virtual registers in their DECL_RTL's.

   If VALID_ONLY, do this only if the resulting address is still valid.
   Otherwise, always do it.  */

static void
instantiate_decls (tree fndecl, int valid_only)
{
  tree decl;

  /* Process all parameters of the function.  */
  for (decl = DECL_ARGUMENTS (fndecl); decl; decl = TREE_CHAIN (decl))
    {
      HOST_WIDE_INT size = int_size_in_bytes (TREE_TYPE (decl));
      HOST_WIDE_INT size_rtl;

      instantiate_decl (DECL_RTL (decl), size, valid_only);

      /* If the parameter was promoted, then the incoming RTL mode may be
         larger than the declared type size.  We must use the larger of
         the two sizes.  */
      size_rtl = GET_MODE_SIZE (GET_MODE (DECL_INCOMING_RTL (decl)));
      size = MAX (size_rtl, size);
      instantiate_decl (DECL_INCOMING_RTL (decl), size, valid_only);
    }

  /* Now process all variables defined in the function or its subblocks.  */
  instantiate_decls_1 (DECL_INITIAL (fndecl), valid_only);
}

/* Subroutine of instantiate_decls: Process all decls in the given
   BLOCK node and all its subblocks.  */

static void
instantiate_decls_1 (tree let, int valid_only)
{
  tree t;

  for (t = BLOCK_VARS (let); t; t = TREE_CHAIN (t))
    if (DECL_RTL_SET_P (t))
      instantiate_decl (DECL_RTL (t),
                        int_size_in_bytes (TREE_TYPE (t)),
                        valid_only);

  /* Process all subblocks.  */
  for (t = BLOCK_SUBBLOCKS (let); t; t = TREE_CHAIN (t))
    instantiate_decls_1 (t, valid_only);
}

/* Subroutine of the preceding procedures: Given RTL representing a
   decl and the size of the object, do any instantiation required.

   If VALID_ONLY is nonzero, it means that the RTL should only be
   changed if the new address is valid.  */

static void
instantiate_decl (rtx x, HOST_WIDE_INT size, int valid_only)
{
  enum machine_mode mode;
  rtx addr;

  /* If this is not a MEM, no need to do anything.  Similarly if the
     address is a constant or a register that is not a virtual register.  */

  if (x == 0 || !MEM_P (x))
    return;

  addr = XEXP (x, 0);
  if (CONSTANT_P (addr)
      || (REG_P (addr)
          && (REGNO (addr) < FIRST_VIRTUAL_REGISTER
              || REGNO (addr) > LAST_VIRTUAL_REGISTER)))
    return;

  /* If we should only do this if the address is valid, copy the address.
     We need to do this so we can undo any changes that might make the
     address invalid.  This copy is unfortunate, but probably can't be
     avoided.  */

  if (valid_only)
    addr = copy_rtx (addr);

  instantiate_virtual_regs_1 (&addr, NULL_RTX, 0);

  if (valid_only && size >= 0)
    {
      unsigned HOST_WIDE_INT decl_size = size;

      /* Now verify that the resulting address is valid for every integer or
         floating-point mode up to and including SIZE bytes long.  We do this
         since the object might be accessed in any mode and frame addresses
         are shared.  */

      for (mode = GET_CLASS_NARROWEST_MODE (MODE_INT);
           mode != VOIDmode && GET_MODE_SIZE (mode) <= decl_size;
           mode = GET_MODE_WIDER_MODE (mode))
        if (! memory_address_p (mode, addr))
          return;

      for (mode = GET_CLASS_NARROWEST_MODE (MODE_FLOAT);
           mode != VOIDmode && GET_MODE_SIZE (mode) <= decl_size;
           mode = GET_MODE_WIDER_MODE (mode))
        if (! memory_address_p (mode, addr))
          return;
    }

  /* Put back the address now that we have updated it and we either know
     it is valid or we don't care whether it is valid.  */

  XEXP (x, 0) = addr;
}
\f
/* Given a piece of RTX and a pointer to a HOST_WIDE_INT, if the RTX
   is a virtual register, return the equivalent hard register and set the
   offset indirectly through the pointer.  Otherwise, return 0.  */

static rtx
instantiate_new_reg (rtx x, HOST_WIDE_INT *poffset)
{
  rtx new;
  HOST_WIDE_INT offset;

  if (x == virtual_incoming_args_rtx)
    new = arg_pointer_rtx, offset = in_arg_offset;
  else if (x == virtual_stack_vars_rtx)
    new = frame_pointer_rtx, offset = var_offset;
  else if (x == virtual_stack_dynamic_rtx)
    new = stack_pointer_rtx, offset = dynamic_offset;
  else if (x == virtual_outgoing_args_rtx)
    new = stack_pointer_rtx, offset = out_arg_offset;
  else if (x == virtual_cfa_rtx)
    new = arg_pointer_rtx, offset = cfa_offset;
  else
    return 0;

  *poffset = offset;
  return new;
}
\f

/* Called when instantiate_virtual_regs has failed to update the instruction.
   Usually this means that non-matching instruction has been emit, however for
   asm statements it may be the problem in the constraints.  */
static void
instantiate_virtual_regs_lossage (rtx insn)
{
  if (asm_noperands (PATTERN (insn)) >= 0)
    {
      error_for_asm (insn, "impossible constraint in `asm'");
      delete_insn (insn);
    }
  else
    abort ();
}
/* Given a pointer to a piece of rtx and an optional pointer to the
   containing object, instantiate any virtual registers present in it.

   If EXTRA_INSNS, we always do the replacement and generate
   any extra insns before OBJECT.  If it zero, we do nothing if replacement
   is not valid.

   Return 1 if we either had nothing to do or if we were able to do the
   needed replacement.  Return 0 otherwise; we only return zero if
   EXTRA_INSNS is zero.

   We first try some simple transformations to avoid the creation of extra
   pseudos.  */

static int
instantiate_virtual_regs_1 (rtx *loc, rtx object, int extra_insns)
{
  rtx x;
  RTX_CODE code;
  rtx new = 0;
  HOST_WIDE_INT offset = 0;
  rtx temp;
  rtx seq;
  int i, j;
  const char *fmt;

  /* Re-start here to avoid recursion in common cases.  */
 restart:

  x = *loc;
  if (x == 0)
    return 1;

  /* We may have detected and deleted invalid asm statements.  */
  if (object && INSN_P (object) && INSN_DELETED_P (object))
    return 1;

  code = GET_CODE (x);

  /* Check for some special cases.  */
  switch (code)
    {
    case CONST_INT:
    case CONST_DOUBLE:
    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 1;

    case SET:
      /* We are allowed to set the virtual registers.  This means that
         the actual register should receive the source minus the
         appropriate offset.  This is used, for example, in the handling
         of non-local gotos.  */
      if ((new = instantiate_new_reg (SET_DEST (x), &offset)) != 0)
        {
          rtx src = SET_SRC (x);

          /* We are setting the register, not using it, so the relevant
             offset is the negative of the offset to use were we using
             the register.  */
          offset = - offset;
          instantiate_virtual_regs_1 (&src, NULL_RTX, 0);

          /* The only valid sources here are PLUS or REG.  Just do
             the simplest possible thing to handle them.  */
          if (!REG_P (src) && GET_CODE (src) != PLUS)
            {
              instantiate_virtual_regs_lossage (object);
              return 1;
            }

          start_sequence ();
          if (!REG_P (src))
            temp = force_operand (src, NULL_RTX);
          else
            temp = src;
          temp = force_operand (plus_constant (temp, offset), NULL_RTX);
          seq = get_insns ();
          end_sequence ();

          emit_insn_before (seq, object);
          SET_DEST (x) = new;

          if (! validate_change (object, &SET_SRC (x), temp, 0)
              || ! extra_insns)
            instantiate_virtual_regs_lossage (object);

          return 1;
        }

      instantiate_virtual_regs_1 (&SET_DEST (x), object, extra_insns);
      loc = &SET_SRC (x);
      goto restart;

    case PLUS:
      /* Handle special case of virtual register plus constant.  */
      if (CONSTANT_P (XEXP (x, 1)))
        {
          rtx old, new_offset;

          /* Check for (plus (plus VIRT foo) (const_int)) first.  */
          if (GET_CODE (XEXP (x, 0)) == PLUS)
            {
              if ((new = instantiate_new_reg (XEXP (XEXP (x, 0), 0), &offset)))
                {
                  instantiate_virtual_regs_1 (&XEXP (XEXP (x, 0), 1), object,
                                              extra_insns);
                  new = gen_rtx_PLUS (Pmode, new, XEXP (XEXP (x, 0), 1));
                }
              else
                {
                  loc = &XEXP (x, 0);
                  goto restart;
                }
            }

#ifdef POINTERS_EXTEND_UNSIGNED
          /* If we have (plus (subreg (virtual-reg)) (const_int)), we know
             we can commute the PLUS and SUBREG because pointers into the
             frame are well-behaved.  */
          else if (GET_CODE (XEXP (x, 0)) == SUBREG && GET_MODE (x) == ptr_mode
                   && GET_CODE (XEXP (x, 1)) == CONST_INT
                   && 0 != (new
                            = instantiate_new_reg (SUBREG_REG (XEXP (x, 0)),
                                                   &offset))
                   && validate_change (object, loc,
                                       plus_constant (gen_lowpart (ptr_mode,
                                                                   new),
                                                      offset
                                                      + INTVAL (XEXP (x, 1))),
                                       0))
                return 1;
#endif
          else if ((new = instantiate_new_reg (XEXP (x, 0), &offset)) == 0)
            {
              /* We know the second operand is a constant.  Unless the
                 first operand is a REG (which has been already checked),
                 it needs to be checked.  */
              if (!REG_P (XEXP (x, 0)))
                {
                  loc = &XEXP (x, 0);
                  goto restart;
                }
              return 1;
            }

          new_offset = plus_constant (XEXP (x, 1), offset);

          /* If the new constant is zero, try to replace the sum with just
             the register.  */
          if (new_offset == const0_rtx
              && validate_change (object, loc, new, 0))
            return 1;

          /* Next try to replace the register and new offset.
             There are two changes to validate here and we can't assume that
             in the case of old offset equals new just changing the register
             will yield a valid insn.  In the interests of a little efficiency,
             however, we only call validate change once (we don't queue up the
             changes and then call apply_change_group).  */

          old = XEXP (x, 0);
          if (offset == 0
              ? ! validate_change (object, &XEXP (x, 0), new, 0)
              : (XEXP (x, 0) = new,
                 ! validate_change (object, &XEXP (x, 1), new_offset, 0)))
            {
              if (! extra_insns)
                {
                  XEXP (x, 0) = old;
                  return 0;
                }

              /* Otherwise copy the new constant into a register and replace
                 constant with that register.  */
              temp = gen_reg_rtx (Pmode);
              XEXP (x, 0) = new;
              if (validate_change (object, &XEXP (x, 1), temp, 0))
                emit_insn_before (gen_move_insn (temp, new_offset), object);
              else
                {
                  /* If that didn't work, replace this expression with a
                     register containing the sum.  */

                  XEXP (x, 0) = old;
                  new = gen_rtx_PLUS (Pmode, new, new_offset);

                  start_sequence ();
                  temp = force_operand (new, NULL_RTX);
                  seq = get_insns ();
                  end_sequence ();

                  emit_insn_before (seq, object);
                  if (! validate_change (object, loc, temp, 0)
                      && ! validate_replace_rtx (x, temp, object))
                    {
                      instantiate_virtual_regs_lossage (object);
                      return 1;
                    }
                }
            }

          return 1;
        }

      /* Fall through to generic two-operand expression case.  */
    case EXPR_LIST:
    case CALL:
    case COMPARE:
    case MINUS:
    case MULT:
    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:
      if (XEXP (x, 1) && ! CONSTANT_P (XEXP (x, 1)))
        instantiate_virtual_regs_1 (&XEXP (x, 1), object, extra_insns);
      loc = &XEXP (x, 0);
      goto restart;

    case MEM:
      /* Most cases of MEM that convert to valid addresses have already been
         handled by our scan of decls.  The only special handling we
         need here is to make a copy of the rtx to ensure it isn't being
         shared if we have to change it to a pseudo.

         If the rtx is a simple reference to an address via a virtual register,
         it can potentially be shared.  In such cases, first try to make it
         a valid address, which can also be shared.  Otherwise, copy it and
         proceed normally.

         First check for common cases that need no processing.  These are
         usually due to instantiation already being done on a previous instance
         of a shared rtx.  */

      temp = XEXP (x, 0);
      if (CONSTANT_ADDRESS_P (temp)
#if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
          || temp == arg_pointer_rtx
#endif
#if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM
          || temp == hard_frame_pointer_rtx
#endif
          || temp == frame_pointer_rtx)
        return 1;

      if (GET_CODE (temp) == PLUS
          && CONSTANT_ADDRESS_P (XEXP (temp, 1))
          && (XEXP (temp, 0) == frame_pointer_rtx
#if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM
              || XEXP (temp, 0) == hard_frame_pointer_rtx
#endif
#if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
              || XEXP (temp, 0) == arg_pointer_rtx
#endif
              ))
        return 1;

      if (temp == virtual_stack_vars_rtx
          || temp == virtual_incoming_args_rtx
          || (GET_CODE (temp) == PLUS
              && CONSTANT_ADDRESS_P (XEXP (temp, 1))
              && (XEXP (temp, 0) == virtual_stack_vars_rtx
                  || XEXP (temp, 0) == virtual_incoming_args_rtx)))
        {
          /* This MEM may be shared.  If the substitution can be done without
             the need to generate new pseudos, we want to do it in place
             so all copies of the shared rtx benefit.  The call below will
             only make substitutions if the resulting address is still
             valid.

             Note that we cannot pass X as the object in the recursive call
             since the insn being processed may not allow all valid
             addresses.  However, if we were not passed on object, we can
             only modify X without copying it if X will have a valid
             address.

             ??? Also note that this can still lose if OBJECT is an insn that
             has less restrictions on an address that some other insn.
             In that case, we will modify the shared address.  This case
             doesn't seem very likely, though.  One case where this could
             happen is in the case of a USE or CLOBBER reference, but we
             take care of that below.  */

          if (instantiate_virtual_regs_1 (&XEXP (x, 0),
                                          object ? object : x, 0))
            return 1;

          /* Otherwise make a copy and process that copy.  We copy the entire
             RTL expression since it might be a PLUS which could also be
             shared.  */
          *loc = x = copy_rtx (x);
        }

      /* Fall through to generic unary operation case.  */
    case PREFETCH:
    case SUBREG:
    case STRICT_LOW_PART:
    case NEG:          case NOT:
    case PRE_DEC:      case PRE_INC:      case POST_DEC:    case POST_INC:
    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:
      /* These case either have just one operand or we know that we need not
         check the rest of the operands.  */
      loc = &XEXP (x, 0);
      goto restart;

    case USE:
    case CLOBBER:
      /* If the operand is a MEM, see if the change is a valid MEM.  If not,
         go ahead and make the invalid one, but do it to a copy.  For a REG,
         just make the recursive call, since there's no chance of a problem.  */

      if ((MEM_P (XEXP (x, 0))
           && instantiate_virtual_regs_1 (&XEXP (XEXP (x, 0), 0), XEXP (x, 0),
                                          0))
          || (REG_P (XEXP (x, 0))
              && instantiate_virtual_regs_1 (&XEXP (x, 0), object, 0)))
        return 1;

      XEXP (x, 0) = copy_rtx (XEXP (x, 0));
      loc = &XEXP (x, 0);
      goto restart;

    case REG:
      /* Try to replace with a PLUS.  If that doesn't work, compute the sum
         in front of this insn and substitute the temporary.  */
      if ((new = instantiate_new_reg (x, &offset)) != 0)
        {
          temp = plus_constant (new, offset);
          if (!validate_change (object, loc, temp, 0))
            {
              if (! extra_insns)
                return 0;

              start_sequence ();
              temp = force_operand (temp, NULL_RTX);
              seq = get_insns ();
              end_sequence ();

              emit_insn_before (seq, object);
              if (! validate_change (object, loc, temp, 0)
                  && ! validate_replace_rtx (x, temp, object))
                instantiate_virtual_regs_lossage (object);
            }
        }

      return 1;

    default:
      break;
    }

  /* Scan all subexpressions.  */
  fmt = GET_RTX_FORMAT (code);
  for (i = 0; i < GET_RTX_LENGTH (code); i++, fmt++)
    if (*fmt == 'e')
      {
        if (!instantiate_virtual_regs_1 (&XEXP (x, i), object, extra_insns))
          return 0;
      }
    else if (*fmt == 'E')
      for (j = 0; j < XVECLEN (x, i); j++)
        if (! instantiate_virtual_regs_1 (&XVECEXP (x, i, j), object,
                                          extra_insns))
          return 0;

  return 1;
}
\f
/* Return 1 if EXP is an aggregate type (or a value with aggregate type).
   This means a type for which function calls must pass an address to the
   function or get an address back from the function.
   EXP may be a type node or an expression (whose type is tested).  */

int
aggregate_value_p (tree exp, tree fntype)
{
  int i, regno, nregs;
  rtx reg;

  tree type = (TYPE_P (exp)) ? exp : TREE_TYPE (exp);

  if (fntype)
    switch (TREE_CODE (fntype))
      {
      case CALL_EXPR:
        fntype = get_callee_fndecl (fntype);
        fntype = fntype ? TREE_TYPE (fntype) : 0;
        break;
      case FUNCTION_DECL:
        fntype = TREE_TYPE (fntype);
        break;
      case FUNCTION_TYPE:
      case METHOD_TYPE:
        break;
      case IDENTIFIER_NODE:
        fntype = 0;
        break;
      default:
        /* We don't expect other rtl types here.  */
        abort();
      }

  if (TREE_CODE (type) == VOID_TYPE)
    return 0;
  if (targetm.calls.return_in_memory (type, fntype))
    return 1;
  /* Types that are TREE_ADDRESSABLE must be constructed in memory,
     and thus can't be returned in registers.  */
  if (TREE_ADDRESSABLE (type))
    return 1;
  if (flag_pcc_struct_return && AGGREGATE_TYPE_P (type))
    return 1;
  /* Make sure we have suitable call-clobbered regs to return
     the value in; if not, we must return it in memory.  */
  reg = hard_function_value (type, 0, 0);

  /* If we have something other than a REG (e.g. a PARALLEL), then assume
     it is OK.  */
  if (!REG_P (reg))
    return 0;

  regno = REGNO (reg);
  nregs = hard_regno_nregs[regno][TYPE_MODE (type)];
  for (i = 0; i < nregs; i++)
    if (! call_used_regs[regno + i])
      return 1;
  return 0;
}
\f
/* Return true if we should assign DECL a pseudo register; false if it
   should live on the local stack.  */

bool
use_register_for_decl (tree decl)
{
  /* Honor volatile.  */
  if (TREE_SIDE_EFFECTS (decl))
    return false;

  /* Honor addressability.  */
  if (TREE_ADDRESSABLE (decl))
    return false;

  /* Only register-like things go in registers.  */
  if (DECL_MODE (decl) == BLKmode)
    return false;

  /* If -ffloat-store specified, don't put explicit float variables
     into registers.  */
  /* ??? This should be checked after DECL_ARTIFICIAL, but tree-ssa
     propagates values across these stores, and it probably shouldn't.  */
  if (flag_float_store && FLOAT_TYPE_P (TREE_TYPE (decl)))
    return false;

  /* Compiler-generated temporaries can always go in registers.  */
  if (DECL_ARTIFICIAL (decl))
    return true;

#ifdef NON_SAVING_SETJMP
  /* Protect variables not declared "register" from setjmp.  */
  if (NON_SAVING_SETJMP
      && current_function_calls_setjmp
      && !DECL_REGISTER (decl))
    return false;
#endif

  return (optimize || DECL_REGISTER (decl));
}

/* Return true if TYPE should be passed by invisible reference.  */

bool
pass_by_reference (CUMULATIVE_ARGS *ca, enum machine_mode mode,
                   tree type, bool named_arg)
{
  if (type)
    {
      /* If this type contains non-trivial constructors, then it is
         forbidden for the middle-end to create any new copies.  */
      if (TREE_ADDRESSABLE (type))
        return true;

      /* GCC post 3.4 passes *all* variable sized types by reference.  */
      if (!TYPE_SIZE (type) || TREE_CODE (TYPE_SIZE (type)) != INTEGER_CST)
        return true;
    }

  return targetm.calls.pass_by_reference (ca, mode, type, named_arg);
}

/* Structures to communicate between the subroutines of assign_parms.
   The first holds data persistent across all parameters, the second
   is cleared out for each parameter.  */

struct assign_parm_data_all
{
  CUMULATIVE_ARGS args_so_far;
  struct args_size stack_args_size;
  tree function_result_decl;
  tree orig_fnargs;
  rtx conversion_insns;
  HOST_WIDE_INT pretend_args_size;
  HOST_WIDE_INT extra_pretend_bytes;
  int reg_parm_stack_space;
};

struct assign_parm_data_one
{
  tree nominal_type;
  tree passed_type;
  rtx entry_parm;
  rtx stack_parm;
  enum machine_mode nominal_mode;
  enum machine_mode passed_mode;
  enum machine_mode promoted_mode;
  struct locate_and_pad_arg_data locate;
  int partial;
  BOOL_BITFIELD named_arg : 1;
  BOOL_BITFIELD last_named : 1;
  BOOL_BITFIELD passed_pointer : 1;
  BOOL_BITFIELD on_stack : 1;
  BOOL_BITFIELD loaded_in_reg : 1;
};

/* A subroutine of assign_parms.  Initialize ALL.  */

static void
assign_parms_initialize_all (struct assign_parm_data_all *all)
{
  tree fntype;

  memset (all, 0, sizeof (*all));

  fntype = TREE_TYPE (current_function_decl);

#ifdef INIT_CUMULATIVE_INCOMING_ARGS
  INIT_CUMULATIVE_INCOMING_ARGS (all->args_so_far, fntype, NULL_RTX);
#else
  INIT_CUMULATIVE_ARGS (all->args_so_far, fntype, NULL_RTX,
                        current_function_decl, -1);
#endif

#ifdef REG_PARM_STACK_SPACE
  all->reg_parm_stack_space = REG_PARM_STACK_SPACE (current_function_decl);
#endif
}

/* If ARGS contains entries with complex types, split the entry into two
   entries of the component type.  Return a new list of substitutions are
   needed, else the old list.  */

static tree
split_complex_args (tree args)
{
  tree p;

  /* Before allocating memory, check for the common case of no complex.  */
  for (p = args; p; p = TREE_CHAIN (p))
    {
      tree type = TREE_TYPE (p);
      if (TREE_CODE (type) == COMPLEX_TYPE
          && targetm.calls.split_complex_arg (type))
        goto found;
    }
  return args;

 found:
  args = copy_list (args);

  for (p = args; p; p = TREE_CHAIN (p))
    {
      tree type = TREE_TYPE (p);
      if (TREE_CODE (type) == COMPLEX_TYPE
          && targetm.calls.split_complex_arg (type))
        {
          tree decl;
          tree subtype = TREE_TYPE (type);

          /* Rewrite the PARM_DECL's type with its component.  */
          TREE_TYPE (p) = subtype;
          DECL_ARG_TYPE (p) = TREE_TYPE (DECL_ARG_TYPE (p));
          DECL_MODE (p) = VOIDmode;
          DECL_SIZE (p) = NULL;
          DECL_SIZE_UNIT (p) = NULL;
          layout_decl (p, 0);

          /* Build a second synthetic decl.  */
          decl = build_decl (PARM_DECL, NULL_TREE, subtype);
          DECL_ARG_TYPE (decl) = DECL_ARG_TYPE (p);
          layout_decl (decl, 0);

          /* Splice it in; skip the new decl.  */
          TREE_CHAIN (decl) = TREE_CHAIN (p);
          TREE_CHAIN (p) = decl;
          p = decl;
        }
    }

  return args;
}

/* A subroutine of assign_parms.  Adjust the parameter list to incorporate
   the hidden struct return argument, and (abi willing) complex args.
   Return the new parameter list.  */

static tree
assign_parms_augmented_arg_list (struct assign_parm_data_all *all)
{
  tree fndecl = current_function_decl;
  tree fntype = TREE_TYPE (fndecl);
  tree fnargs = DECL_ARGUMENTS (fndecl);

  /* If struct value address is treated as the first argument, make it so.  */
  if (aggregate_value_p (DECL_RESULT (fndecl), fndecl)
      && ! current_function_returns_pcc_struct
      && targetm.calls.struct_value_rtx (TREE_TYPE (fndecl), 1) == 0)
    {
      tree type = build_pointer_type (TREE_TYPE (fntype));
      tree decl;

      decl = build_decl (PARM_DECL, NULL_TREE, type);
      DECL_ARG_TYPE (decl) = type;
      DECL_ARTIFICIAL (decl) = 1;

      TREE_CHAIN (decl) = fnargs;
      fnargs = decl;
      all->function_result_decl = decl;
    }

  all->orig_fnargs = fnargs;

  /* If the target wants to split complex arguments into scalars, do so.  */
  if (targetm.calls.split_complex_arg)
    fnargs = split_complex_args (fnargs);

  return fnargs;
}

/* A subroutine of assign_parms.  Examine PARM and pull out type and mode
   data for the parameter.  Incorporate ABI specifics such as pass-by-
   reference and type promotion.  */

static void
assign_parm_find_data_types (struct assign_parm_data_all *all, tree parm,
                             struct assign_parm_data_one *data)
{
  tree nominal_type, passed_type;
  enum machine_mode nominal_mode, passed_mode, promoted_mode;

  memset (data, 0, sizeof (*data));

  /* Set LAST_NAMED if this is last named arg before last anonymous args.  */
  if (current_function_stdarg)
    {
      tree tem;
      for (tem = TREE_CHAIN (parm); tem; tem = TREE_CHAIN (tem))
        if (DECL_NAME (tem))
          break;
      if (tem == 0)
        data->last_named = true;
    }

  /* Set NAMED_ARG if this arg should be treated as a named arg.  For
     most machines, if this is a varargs/stdarg function, then we treat
     the last named arg as if it were anonymous too.  */
  if (targetm.calls.strict_argument_naming (&all->args_so_far))
    data->named_arg = 1;
  else
    data->named_arg = !data->last_named;

  nominal_type = TREE_TYPE (parm);
  passed_type = DECL_ARG_TYPE (parm);

  /* Look out for errors propagating this far.  Also, if the parameter's
     type is void then its value doesn't matter.  */
  if (TREE_TYPE (parm) == error_mark_node
      /* This can happen after weird syntax errors
         or if an enum type is defined among the parms.  */
      || TREE_CODE (parm) != PARM_DECL
      || passed_type == NULL
      || VOID_TYPE_P (nominal_type))
    {
      nominal_type = passed_type = void_type_node;
      nominal_mode = passed_mode = promoted_mode = VOIDmode;
      goto egress;
    }

  /* Find mode of arg as it is passed, and mode of arg as it should be
     during execution of this function.  */
  passed_mode = TYPE_MODE (passed_type);
  nominal_mode = TYPE_MODE (nominal_type);

  /* If the parm is to be passed as a transparent union, use the type of
     the first field for the tests below.  We have already verified that
     the modes are the same.  */
  if (DECL_TRANSPARENT_UNION (parm)
      || (TREE_CODE (passed_type) == UNION_TYPE
          && TYPE_TRANSPARENT_UNION (passed_type)))
    passed_type = TREE_TYPE (TYPE_FIELDS (passed_type));

  /* See if this arg was passed by invisible reference.  */
  if (pass_by_reference (&all->args_so_far, passed_mode,
                         passed_type, data->named_arg))
    {
      passed_type = nominal_type = build_pointer_type (passed_type);
      data->passed_pointer = true;
      passed_mode = nominal_mode = Pmode;
    }
  /* See if the frontend wants to pass this by invisible reference.  */
  else if (passed_type != nominal_type
           && POINTER_TYPE_P (passed_type)
           && TREE_TYPE (passed_type) == nominal_type)
    {
      nominal_type = passed_type;
      data->passed_pointer = 1;
      passed_mode = nominal_mode = Pmode;
    }

  /* Find mode as it is passed by the ABI.  */
  promoted_mode = passed_mode;
  if (targetm.calls.promote_function_args (TREE_TYPE (current_function_decl)))
    {
      int unsignedp = TYPE_UNSIGNED (passed_type);
      promoted_mode = promote_mode (passed_type, promoted_mode,
                                    &unsignedp, 1);
    }

 egress:
  data->nominal_type = nominal_type;
  data->passed_type = passed_type;
  data->nominal_mode = nominal_mode;
  data->passed_mode = passed_mode;
  data->promoted_mode = promoted_mode;
}

/* A subroutine of assign_parms.  Invoke setup_incoming_varargs.  */

static void
assign_parms_setup_varargs (struct assign_parm_data_all *all,
                            struct assign_parm_data_one *data, bool no_rtl)
{
  int varargs_pretend_bytes = 0;

  targetm.calls.setup_incoming_varargs (&all->args_so_far,
                                        data->promoted_mode,
                                        data->passed_type,
                                        &varargs_pretend_bytes, no_rtl);

  /* If the back-end has requested extra stack space, record how much is
     needed.  Do not change pretend_args_size otherwise since it may be
     nonzero from an earlier partial argument.  */
  if (varargs_pretend_bytes > 0)
    all->pretend_args_size = varargs_pretend_bytes;
}

/* A subroutine of assign_parms.  Set DATA->ENTRY_PARM corresponding to
   the incoming location of the current parameter.  */

static void
assign_parm_find_entry_rtl (struct assign_parm_data_all *all,
                            struct assign_parm_data_one *data)
{
  HOST_WIDE_INT pretend_bytes = 0;
  rtx entry_parm;
  bool in_regs;

  if (data->promoted_mode == VOIDmode)
    {
      data->entry_parm = data->stack_parm = const0_rtx;
      return;
    }

#ifdef FUNCTION_INCOMING_ARG
  entry_parm = FUNCTION_INCOMING_ARG (all->args_so_far, data->promoted_mode,
                                      data->passed_type, data->named_arg);
#else
  entry_parm = FUNCTION_ARG (all->args_so_far, data->promoted_mode,
                             data->passed_type, data->named_arg);
#endif

  if (entry_parm == 0)
    data->promoted_mode = data->passed_mode;

  /* Determine parm's home in the stack, in case it arrives in the stack
     or we should pretend it did.  Compute the stack position and rtx where
     the argument arrives and its size.

     There is one complexity here:  If this was a parameter that would
     have been passed in registers, but wasn't only because it is
     __builtin_va_alist, we want locate_and_pad_parm to treat it as if
     it came in a register so that REG_PARM_STACK_SPACE isn't skipped.
     In this case, we call FUNCTION_ARG with NAMED set to 1 instead of 0
     as it was the previous time.  */
  in_regs = entry_parm != 0;
#ifdef STACK_PARMS_IN_REG_PARM_AREA
  in_regs = true;
#endif
  if (!in_regs && !data->named_arg)
    {
      if (targetm.calls.pretend_outgoing_varargs_named (&all->args_so_far))
        {
          rtx tem;
#ifdef FUNCTION_INCOMING_ARG
          tem = FUNCTION_INCOMING_ARG (all->args_so_far, data->promoted_mode,
                                       data->passed_type, true);
#else
          tem = FUNCTION_ARG (all->args_so_far, data->promoted_mode,
                              data->passed_type, true);
#endif
          in_regs = tem != NULL;
        }
    }

  /* If this parameter was passed both in registers and in the stack, use
     the copy on the stack.  */
  if (targetm.calls.must_pass_in_stack (data->promoted_mode,
                                        data->passed_type))
    entry_parm = 0;

  if (entry_parm)
    {
      int partial;

      partial = FUNCTION_ARG_PARTIAL_NREGS (all->args_so_far,
                                            data->promoted_mode,
                                            data->passed_type,
                                            data->named_arg);
      data->partial = partial;

      /* The caller might already have allocated stack space for the
         register parameters.  */
      if (partial != 0 && all->reg_parm_stack_space == 0)
        {
          /* Part of this argument is passed in registers and part
             is passed on the stack.  Ask the prologue code to extend
             the stack part so that we can recreate the full value.

             PRETEND_BYTES is the size of the registers we need to store.
             CURRENT_FUNCTION_PRETEND_ARGS_SIZE is the amount of extra
             stack space that the prologue should allocate.

             Internally, gcc assumes that the argument pointer is aligned
             to STACK_BOUNDARY bits.  This is used both for alignment
             optimizations (see init_emit) and to locate arguments that are
             aligned to more than PARM_BOUNDARY bits.  We must preserve this
             invariant by rounding CURRENT_FUNCTION_PRETEND_ARGS_SIZE up to
             a stack boundary.  */

          /* We assume at most one partial arg, and it must be the first
             argument on the stack.  */
          if (all->extra_pretend_bytes || all->pretend_args_size)
            abort ();

          pretend_bytes = partial * UNITS_PER_WORD;
          all->pretend_args_size = CEIL_ROUND (pretend_bytes, STACK_BYTES);

          /* We want to align relative to the actual stack pointer, so
             don't include this in the stack size until later.  */
          all->extra_pretend_bytes = all->pretend_args_size;
        }
    }

  locate_and_pad_parm (data->promoted_mode, data->passed_type, in_regs,
                       entry_parm ? data->partial : 0, current_function_decl,
                       &all->stack_args_size, &data->locate);

  /* Adjust offsets to include the pretend args.  */
  pretend_bytes = all->extra_pretend_bytes - pretend_bytes;
  data->locate.slot_offset.constant += pretend_bytes;
  data->locate.offset.constant += pretend_bytes;

  data->entry_parm = entry_parm;
}

/* A subroutine of assign_parms.  If there is actually space on the stack
   for this parm, count it in stack_args_size and return true.  */

static bool
assign_parm_is_stack_parm (struct assign_parm_data_all *all,
                           struct assign_parm_data_one *data)
{
  /* Trivially true if we've no incomming register.  */
  if (data->entry_parm == NULL)
    ;
  /* Also true if we're partially in registers and partially not,
     since we've arranged to drop the entire argument on the stack.  */
  else if (data->partial != 0)
    ;
  /* Also true if the target says that it's passed in both registers
     and on the stack.  */
  else if (GET_CODE (data->entry_parm) == PARALLEL
           && XEXP (XVECEXP (data->entry_parm, 0, 0), 0) == NULL_RTX)
    ;
  /* Also true if the target says that there's stack allocated for
     all register parameters.  */
  else if (all->reg_parm_stack_space > 0)
    ;
  /* Otherwise, no, this parameter has no ABI defined stack slot.  */
  else
    return false;

  all->stack_args_size.constant += data->locate.size.constant;
  if (data->locate.size.var)
    ADD_PARM_SIZE (all->stack_args_size, data->locate.size.var);

  return true;
}

/* A subroutine of assign_parms.  Given that this parameter is allocated
   stack space by the ABI, find it.  */

static void
assign_parm_find_stack_rtl (tree parm, struct assign_parm_data_one *data)
{
  rtx offset_rtx, stack_parm;
  unsigned int align, boundary;

  /* If we're passing this arg using a reg, make its stack home the
     aligned stack slot.  */
  if (data->entry_parm)
    offset_rtx = ARGS_SIZE_RTX (data->locate.slot_offset);
  else
    offset_rtx = ARGS_SIZE_RTX (data->locate.offset);

  stack_parm = current_function_internal_arg_pointer;
  if (offset_rtx != const0_rtx)
    stack_parm = gen_rtx_PLUS (Pmode, stack_parm, offset_rtx);
  stack_parm = gen_rtx_MEM (data->promoted_mode, stack_parm);

  set_mem_attributes (stack_parm, parm, 1);

  boundary = FUNCTION_ARG_BOUNDARY (data->promoted_mode, data->passed_type);
  align = 0;

  /* If we're padding upward, we know that the alignment of the slot
     is FUNCTION_ARG_BOUNDARY.  If we're using slot_offset, we're
     intentionally forcing upward padding.  Otherwise we have to come
     up with a guess at the alignment based on OFFSET_RTX.  */
  if (data->locate.where_pad == upward || data->entry_parm)
    align = boundary;
  else if (GET_CODE (offset_rtx) == CONST_INT)
    {
      align = INTVAL (offset_rtx) * BITS_PER_UNIT | boundary;
      align = align & -align;
    }
  if (align > 0)
    set_mem_align (stack_parm, align);

  if (data->entry_parm)
    set_reg_attrs_for_parm (data->entry_parm, stack_parm);

  data->stack_parm = stack_parm;
}

/* A subroutine of assign_parms.  Adjust DATA->ENTRY_RTL such that it's
   always valid and contiguous.  */

static void
assign_parm_adjust_entry_rtl (struct assign_parm_data_one *data)
{
  rtx entry_parm = data->entry_parm;
  rtx stack_parm = data->stack_parm;

  /* If this parm was passed part in regs and part in memory, pretend it
     arrived entirely in memory by pushing the register-part onto the stack.
     In the special case of a DImode or DFmode that is split, we could put
     it together in a pseudoreg directly, but for now that's not worth
     bothering with.  */
  if (data->partial != 0)
    {
      /* Handle calls that pass values in multiple non-contiguous
         locations.  The Irix 6 ABI has examples of this.  */
      if (GET_CODE (entry_parm) == PARALLEL)
        emit_group_store (validize_mem (stack_parm), entry_parm,
                          data->passed_type, 
                          int_size_in_bytes (data->passed_type));
      else
        move_block_from_reg (REGNO (entry_parm), validize_mem (stack_parm),
                             data->partial);

      entry_parm = stack_parm;
    }

  /* If we didn't decide this parm came in a register, by default it came
     on the stack.  */
  else if (entry_parm == NULL)
    entry_parm = stack_parm;

  /* When an argument is passed in multiple locations, we can't make use
     of this information, but we can save some copying if the whole argument
     is passed in a single register.  */
  else if (GET_CODE (entry_parm) == PARALLEL
           && data->nominal_mode != BLKmode
           && data->passed_mode != BLKmode)
    {
      size_t i, len = XVECLEN (entry_parm, 0);

      for (i = 0; i < len; i++)
        if (XEXP (XVECEXP (entry_parm, 0, i), 0) != NULL_RTX
            && REG_P (XEXP (XVECEXP (entry_parm, 0, i), 0))
            && (GET_MODE (XEXP (XVECEXP (entry_parm, 0, i), 0))
                == data->passed_mode)
            && INTVAL (XEXP (XVECEXP (entry_parm, 0, i), 1)) == 0)
          {
            entry_parm = XEXP (XVECEXP (entry_parm, 0, i), 0);
            break;
          }
    }

  data->entry_parm = entry_parm;
}

/* A subroutine of assign_parms.  Adjust DATA->STACK_RTL such that it's
   always valid and properly aligned.  */


static void
assign_parm_adjust_stack_rtl (struct assign_parm_data_one *data)
{
  rtx stack_parm = data->stack_parm;

  /* If we can't trust the parm stack slot to be aligned enough for its
     ultimate type, don't use that slot after entry.  We'll make another
     stack slot, if we need one.  */
  if (STRICT_ALIGNMENT && stack_parm
      && GET_MODE_ALIGNMENT (data->nominal_mode) > MEM_ALIGN (stack_parm))
    stack_parm = NULL;

  /* If parm was passed in memory, and we need to convert it on entry,
     don't store it back in that same slot.  */
  else if (data->entry_parm == stack_parm
           && data->nominal_mode != BLKmode
           && data->nominal_mode != data->passed_mode)
    stack_parm = NULL;

  data->stack_parm = stack_parm;
}

/* A subroutine of assign_parms.  Return true if the current parameter
   should be stored as a BLKmode in the current frame.  */

static bool
assign_parm_setup_block_p (struct assign_parm_data_one *data)
{
  if (data->nominal_mode == BLKmode)
    return true;
  if (GET_CODE (data->entry_parm) == PARALLEL)
    return true;

#ifdef BLOCK_REG_PADDING
  if (data->locate.where_pad == (BYTES_BIG_ENDIAN ? upward : downward)
      && GET_MODE_SIZE (data->promoted_mode) < UNITS_PER_WORD)
    return true;
#endif

  return false;
}

/* A subroutine of assign_parms.  Arrange for the parameter to be 
   present and valid in DATA->STACK_RTL.  */

static void
assign_parm_setup_block (tree parm, struct assign_parm_data_one *data)
{
  rtx entry_parm = data->entry_parm;
  rtx stack_parm = data->stack_parm;

  /* If we've a non-block object that's nevertheless passed in parts,
     reconstitute it in register operations rather than on the stack.  */
  if (GET_CODE (entry_parm) == PARALLEL
      && data->nominal_mode != BLKmode
      && XVECLEN (entry_parm, 0) > 1
      && optimize)
    {
      rtx parmreg = gen_reg_rtx (data->nominal_mode);

      emit_group_store (parmreg, entry_parm, data->nominal_type,
                        int_size_in_bytes (data->nominal_type));
      SET_DECL_RTL (parm, parmreg);
      return;
    }

  /* If a BLKmode arrives in registers, copy it to a stack slot.  Handle
     calls that pass values in multiple non-contiguous locations.  */
  if (REG_P (entry_parm) || GET_CODE (entry_parm) == PARALLEL)
    {
      HOST_WIDE_INT size = int_size_in_bytes (data->passed_type);
      HOST_WIDE_INT size_stored = CEIL_ROUND (size, UNITS_PER_WORD);
      rtx mem;

      /* Note that we will be storing an integral number of words.
         So we have to be careful to ensure that we allocate an
         integral number of words.  We do this below in the
         assign_stack_local if space was not allocated in the argument
         list.  If it was, this will not work if PARM_BOUNDARY is not
         a multiple of BITS_PER_WORD.  It isn't clear how to fix this
         if it becomes a problem.  Exception is when BLKmode arrives
         with arguments not conforming to word_mode.  */

      if (stack_parm == 0)
        {
          stack_parm = assign_stack_local (BLKmode, size_stored, 0);
          data->stack_parm = stack_parm;
          PUT_MODE (stack_parm, GET_MODE (entry_parm));
          set_mem_attributes (stack_parm, parm, 1);
        }
      else if (GET_CODE (entry_parm) == PARALLEL)
        ;
      else if (size != 0 && PARM_BOUNDARY % BITS_PER_WORD != 0)
        abort ();

      mem = validize_mem (stack_parm);

      /* Handle values in multiple non-contiguous locations.  */
      if (GET_CODE (entry_parm) == PARALLEL)
        emit_group_store (mem, entry_parm, data->passed_type, size);

      else if (size == 0)
        ;

      /* If SIZE is that of a mode no bigger than a word, just use
         that mode's store operation.  */
      else if (size <= UNITS_PER_WORD)
        {
          enum machine_mode mode
            = mode_for_size (size * BITS_PER_UNIT, MODE_INT, 0);

          if (mode != BLKmode
#ifdef BLOCK_REG_PADDING
              && (size == UNITS_PER_WORD
                  || (BLOCK_REG_PADDING (mode, data->passed_type, 1)
                      != (BYTES_BIG_ENDIAN ? upward : downward)))
#endif
              )
            {
              rtx reg = gen_rtx_REG (mode, REGNO (entry_parm));
              emit_move_insn (change_address (mem, mode, 0), reg);
            }

          /* Blocks smaller than a word on a BYTES_BIG_ENDIAN
             machine must be aligned to the left before storing
             to memory.  Note that the previous test doesn't
             handle all cases (e.g. SIZE == 3).  */
          else if (size != UNITS_PER_WORD
#ifdef BLOCK_REG_PADDING
                   && (BLOCK_REG_PADDING (mode, data->passed_type, 1)
                       == downward)
#else
                   && BYTES_BIG_ENDIAN
#endif
                   )
            {
              rtx tem, x;
              int by = (UNITS_PER_WORD - size) * BITS_PER_UNIT;
              rtx reg = gen_rtx_REG (word_mode, REGNO (data->entry_parm));

              x = expand_shift (LSHIFT_EXPR, word_mode, reg,
                                build_int_2 (by, 0), NULL_RTX, 1);
              tem = change_address (mem, word_mode, 0);
              emit_move_insn (tem, x);
            }
          else
            move_block_from_reg (REGNO (data->entry_parm), mem,
                                 size_stored / UNITS_PER_WORD);
        }
      else
        move_block_from_reg (REGNO (data->entry_parm), mem,
                             size_stored / UNITS_PER_WORD);
    }

  SET_DECL_RTL (parm, stack_parm);
}

/* A subroutine of assign_parms.  Allocate a pseudo to hold the current
   parameter.  Get it there.  Perform all ABI specified conversions.  */

static void
assign_parm_setup_reg (struct assign_parm_data_all *all, tree parm,
                       struct assign_parm_data_one *data)
{
  rtx parmreg;
  enum machine_mode promoted_nominal_mode;
  int unsignedp = TYPE_UNSIGNED (TREE_TYPE (parm));
  bool did_conversion = false;

  /* Store the parm in a pseudoregister during the function, but we may
     need to do it in a wider mode.  */

  promoted_nominal_mode
    = promote_mode (data->nominal_type, data->nominal_mode, &unsignedp, 0);

  parmreg = gen_reg_rtx (promoted_nominal_mode);

  if (!DECL_ARTIFICIAL (parm))
    mark_user_reg (parmreg);

  /* If this was an item that we received a pointer to,
     set DECL_RTL appropriately.  */
  if (data->passed_pointer)
    {
      rtx x = gen_rtx_MEM (TYPE_MODE (TREE_TYPE (data->passed_type)), parmreg);
      set_mem_attributes (x, parm, 1);
      SET_DECL_RTL (parm, x);
    }
  else
    {
      SET_DECL_RTL (parm, parmreg);
      maybe_set_unchanging (DECL_RTL (parm), parm);
    }

  /* Copy the value into the register.  */
  if (data->nominal_mode != data->passed_mode
      || promoted_nominal_mode != data->promoted_mode)
    {
      int save_tree_used;

      /* ENTRY_PARM has been converted to PROMOTED_MODE, its
         mode, by the caller.  We now have to convert it to
         NOMINAL_MODE, if different.  However, PARMREG may be in
         a different mode than NOMINAL_MODE if it is being stored
         promoted.

         If ENTRY_PARM is a hard register, it might be in a register
         not valid for operating in its mode (e.g., an odd-numbered
         register for a DFmode).  In that case, moves are the only
         thing valid, so we can't do a convert from there.  This
         occurs when the calling sequence allow such misaligned
         usages.

         In addition, the conversion may involve a call, which could
         clobber parameters which haven't been copied to pseudo
         registers yet.  Therefore, we must first copy the parm to
         a pseudo reg here, and save the conversion until after all
         parameters have been moved.  */

      rtx tempreg = gen_reg_rtx (GET_MODE (data->entry_parm));

      emit_move_insn (tempreg, validize_mem (data->entry_parm));

      push_to_sequence (all->conversion_insns);
      tempreg = convert_to_mode (data->nominal_mode, tempreg, unsignedp);

      if (GET_CODE (tempreg) == SUBREG
          && GET_MODE (tempreg) == data->nominal_mode
          && REG_P (SUBREG_REG (tempreg))
          && data->nominal_mode == data->passed_mode
          && GET_MODE (SUBREG_REG (tempreg)) == GET_MODE (data->entry_parm)
          && GET_MODE_SIZE (GET_MODE (tempreg))
             < GET_MODE_SIZE (GET_MODE (data->entry_parm)))
        {
          /* The argument is already sign/zero extended, so note it
             into the subreg.  */
          SUBREG_PROMOTED_VAR_P (tempreg) = 1;
          SUBREG_PROMOTED_UNSIGNED_SET (tempreg, unsignedp);
        }

      /* TREE_USED gets set erroneously during expand_assignment.  */
      save_tree_used = TREE_USED (parm);
      expand_assignment (parm, make_tree (data->nominal_type, tempreg), 0);
      TREE_USED (parm) = save_tree_used;
      all->conversion_insns = get_insns ();
      end_sequence ();

      did_conversion = true;
    }
  else
    emit_move_insn (parmreg, validize_mem (data->entry_parm));

  /* If we were passed a pointer but the actual value can safely live
     in a register, put it in one.  */
  if (data->passed_pointer
      && TYPE_MODE (TREE_TYPE (parm)) != BLKmode
      /* If by-reference argument was promoted, demote it.  */
      && (TYPE_MODE (TREE_TYPE (parm)) != GET_MODE (DECL_RTL (parm))
          || use_register_for_decl (parm)))
    {
      /* We can't use nominal_mode, because it will have been set to
         Pmode above.  We must use the actual mode of the parm.  */
      parmreg = gen_reg_rtx (TYPE_MODE (TREE_TYPE (parm)));
      mark_user_reg (parmreg);

      if (GET_MODE (parmreg) != GET_MODE (DECL_RTL (parm)))
        {
          rtx tempreg = gen_reg_rtx (GET_MODE (DECL_RTL (parm)));
          int unsigned_p = TYPE_UNSIGNED (TREE_TYPE (parm));

          push_to_sequence (all->conversion_insns);
          emit_move_insn (tempreg, DECL_RTL (parm));
          tempreg = convert_to_mode (GET_MODE (parmreg), tempreg, unsigned_p);
          emit_move_insn (parmreg, tempreg);
          all->conversion_insns = get_insns();
          end_sequence ();

          did_conversion = true;
        }
      else
        emit_move_insn (parmreg, DECL_RTL (parm));

      SET_DECL_RTL (parm, parmreg);

      /* STACK_PARM is the pointer, not the parm, and PARMREG is
         now the parm.  */
      data->stack_parm = NULL;
    }

  /* If we are passed an arg by reference and it is our responsibility
     to make a copy, do it now.
     PASSED_TYPE and PASSED mode now refer to the pointer, not the
     original argument, so we must recreate them in the call to
     FUNCTION_ARG_CALLEE_COPIES.  */
  /* ??? Later add code to handle the case that if the argument isn't
     modified, don't do the copy.  */

  else if (data->passed_pointer)
    {
      tree type = TREE_TYPE (data->passed_type);
    
      if (FUNCTION_ARG_CALLEE_COPIES (all->args_so_far, TYPE_MODE (type),
                                      type, data->named_arg)
           && !TREE_ADDRESSABLE (type))
        {
          rtx copy;

          /* This sequence may involve a library call perhaps clobbering
             registers that haven't been copied to pseudos yet.  */

          push_to_sequence (all->conversion_insns);

          if (!COMPLETE_TYPE_P (type)
              || TREE_CODE (TYPE_SIZE (type)) != INTEGER_CST)
            {
              /* This is a variable sized object.  */
              copy = allocate_dynamic_stack_space (expr_size (parm), NULL_RTX,
                                                   TYPE_ALIGN (type));
              copy = gen_rtx_MEM (BLKmode, copy);
            }
          else
            copy = assign_stack_temp (TYPE_MODE (type),
                                      int_size_in_bytes (type), 1);
          set_mem_attributes (copy, parm, 1);

          store_expr (parm, copy, 0);
          emit_move_insn (parmreg, XEXP (copy, 0));
          all->conversion_insns = get_insns ();
          end_sequence ();

          did_conversion = true;
        }
    }

  /* Mark the register as eliminable if we did no conversion and it was
     copied from memory at a fixed offset, and the arg pointer was not
     copied to a pseudo-reg.  If the arg pointer is a pseudo reg or the
     offset formed an invalid address, such memory-equivalences as we
     make here would screw up life analysis for it.  */
  if (data->nominal_mode == data->passed_mode
      && !did_conversion
      && data->stack_parm != 0
      && MEM_P (data->stack_parm)
      && data->locate.offset.var == 0
      && reg_mentioned_p (virtual_incoming_args_rtx,
                          XEXP (data->stack_parm, 0)))
    {
      rtx linsn = get_last_insn ();
      rtx sinsn, set;

      /* Mark complex types separately.  */
      if (GET_CODE (parmreg) == CONCAT)
        {
          enum machine_mode submode
            = GET_MODE_INNER (GET_MODE (parmreg));
          int regnor = REGNO (gen_realpart (submode, parmreg));
          int regnoi = REGNO (gen_imagpart (submode, parmreg));
          rtx stackr = gen_realpart (submode, data->stack_parm);
          rtx stacki = gen_imagpart (submode, data->stack_parm);

          /* Scan backwards for the set of the real and
             imaginary parts.  */
          for (sinsn = linsn; sinsn != 0;
               sinsn = prev_nonnote_insn (sinsn))
            {
              set = single_set (sinsn);
              if (set == 0)
                continue;

              if (SET_DEST (set) == regno_reg_rtx [regnoi])
                REG_NOTES (sinsn)
                  = gen_rtx_EXPR_LIST (REG_EQUIV, stacki,
                                       REG_NOTES (sinsn));
              else if (SET_DEST (set) == regno_reg_rtx [regnor])
                REG_NOTES (sinsn)
                  = gen_rtx_EXPR_LIST (REG_EQUIV, stackr,
                                       REG_NOTES (sinsn));
            }
        }
      else if ((set = single_set (linsn)) != 0
               && SET_DEST (set) == parmreg)
        REG_NOTES (linsn)
          = gen_rtx_EXPR_LIST (REG_EQUIV,
                               data->stack_parm, REG_NOTES (linsn));
    }

  /* For pointer data type, suggest pointer register.  */
  if (POINTER_TYPE_P (TREE_TYPE (parm)))
    mark_reg_pointer (parmreg,
                      TYPE_ALIGN (TREE_TYPE (TREE_TYPE (parm))));
}

/* A subroutine of assign_parms.  Allocate stack space to hold the current
   parameter.  Get it there.  Perform all ABI specified conversions.  */

static void
assign_parm_setup_stack (struct assign_parm_data_all *all, tree parm,
                         struct assign_parm_data_one *data)
{
  /* Value must be stored in the stack slot STACK_PARM during function
     execution.  */

  if (data->promoted_mode != data->nominal_mode)
    {
      /* Conversion is required.  */
      rtx tempreg = gen_reg_rtx (GET_MODE (data->entry_parm));

      emit_move_insn (tempreg, validize_mem (data->entry_parm));

      push_to_sequence (all->conversion_insns);
      data->entry_parm = convert_to_mode (data->nominal_mode, tempreg,
                                          TYPE_UNSIGNED (TREE_TYPE (parm)));

      if (data->stack_parm)
        /* ??? This may need a big-endian conversion on sparc64.  */
        data->stack_parm
          = adjust_address (data->stack_parm, data->nominal_mode, 0);

      all->conversion_insns = get_insns ();
      end_sequence ();
    }

  if (data->entry_parm != data->stack_parm)
    {
      if (data->stack_parm == 0)
        {
          data->stack_parm
            = assign_stack_local (GET_MODE (data->entry_parm),
                                  GET_MODE_SIZE (GET_MODE (data->entry_parm)),
                                  0);
          set_mem_attributes (data->stack_parm, parm, 1);
        }

      if (data->promoted_mode != data->nominal_mode)
        {
          push_to_sequence (all->conversion_insns);
          emit_move_insn (validize_mem (data->stack_parm),
                          validize_mem (data->entry_parm));
          all->conversion_insns = get_insns ();
          end_sequence ();
        }
      else
        emit_move_insn (validize_mem (data->stack_parm),
                        validize_mem (data->entry_parm));
    }

  SET_DECL_RTL (parm, data->stack_parm);
}

/* A subroutine of assign_parms.  If the ABI splits complex arguments, then
   undo the frobbing that we did in assign_parms_augmented_arg_list.  */

static void
assign_parms_unsplit_complex (tree orig_fnargs, tree fnargs)
{
  tree parm;

  for (parm = orig_fnargs; parm; parm = TREE_CHAIN (parm))
    {
      if (TREE_CODE (TREE_TYPE (parm)) == COMPLEX_TYPE
          && targetm.calls.split_complex_arg (TREE_TYPE (parm)))
        {
          rtx tmp, real, imag;
          enum machine_mode inner = GET_MODE_INNER (DECL_MODE (parm));

          real = DECL_RTL (fnargs);
          imag = DECL_RTL (TREE_CHAIN (fnargs));
          if (inner != GET_MODE (real))
            {
              real = gen_lowpart_SUBREG (inner, real);
              imag = gen_lowpart_SUBREG (inner, imag);
            }
          tmp = gen_rtx_CONCAT (DECL_MODE (parm), real, imag);
          SET_DECL_RTL (parm, tmp);

          real = DECL_INCOMING_RTL (fnargs);
          imag = DECL_INCOMING_RTL (TREE_CHAIN (fnargs));
          if (inner != GET_MODE (real))
            {
              real = gen_lowpart_SUBREG (inner, real);
              imag = gen_lowpart_SUBREG (inner, imag);
            }
          tmp = gen_rtx_CONCAT (DECL_MODE (parm), real, imag);
          set_decl_incoming_rtl (parm, tmp);
          fnargs = TREE_CHAIN (fnargs);
        }
      else
        {
          SET_DECL_RTL (parm, DECL_RTL (fnargs));
          set_decl_incoming_rtl (parm, DECL_INCOMING_RTL (fnargs));

          /* Set MEM_EXPR to the original decl, i.e. to PARM,
             instead of the copy of decl, i.e. FNARGS.  */
          if (DECL_INCOMING_RTL (parm) && MEM_P (DECL_INCOMING_RTL (parm)))
            set_mem_expr (DECL_INCOMING_RTL (parm), parm);
        }

      fnargs = TREE_CHAIN (fnargs);
    }
}

/* Assign RTL expressions to the function's parameters.  This may involve
   copying them into registers and using those registers as the DECL_RTL.  */

void
assign_parms (tree fndecl)
{
  struct assign_parm_data_all all;
  tree fnargs, parm;
  rtx internal_arg_pointer;
  int varargs_setup = 0;

  /* If the reg that the virtual arg pointer will be translated into is
     not a fixed reg or is the stack pointer, make a copy of the virtual
     arg pointer, and address parms via the copy.  The frame pointer is
     considered fixed even though it is not marked as such.

     The second time through, simply use ap to avoid generating rtx.  */

  if ((ARG_POINTER_REGNUM == STACK_POINTER_REGNUM
       || ! (fixed_regs[ARG_POINTER_REGNUM]
             || ARG_POINTER_REGNUM == FRAME_POINTER_REGNUM)))
    internal_arg_pointer = copy_to_reg (virtual_incoming_args_rtx);
  else
    internal_arg_pointer = virtual_incoming_args_rtx;
  current_function_internal_arg_pointer = internal_arg_pointer;

  assign_parms_initialize_all (&all);
  fnargs = assign_parms_augmented_arg_list (&all);

  for (parm = fnargs; parm; parm = TREE_CHAIN (parm))
    {
      struct assign_parm_data_one data;

      /* Extract the type of PARM; adjust it according to ABI.  */
      assign_parm_find_data_types (&all, parm, &data);

      /* Early out for errors and void parameters.  */
      if (data.passed_mode == VOIDmode)
        {
          SET_DECL_RTL (parm, const0_rtx);
          DECL_INCOMING_RTL (parm) = DECL_RTL (parm);
          continue;
        }

      /* Handle stdargs.  LAST_NAMED is a slight mis-nomer; it's also true
         for the unnamed dummy argument following the last named argument.
         See ABI silliness wrt strict_argument_naming and NAMED_ARG.  So
         we only want to do this when we get to the actual last named
         argument, which will be the first time LAST_NAMED gets set.  */
      if (data.last_named && !varargs_setup)
        {
          varargs_setup = true;
          assign_parms_setup_varargs (&all, &data, false);
        }

      /* Find out where the parameter arrives in this function.  */
      assign_parm_find_entry_rtl (&all, &data);

      /* Find out where stack space for this parameter might be.  */
      if (assign_parm_is_stack_parm (&all, &data))
        {
          assign_parm_find_stack_rtl (parm, &data);
          assign_parm_adjust_entry_rtl (&data);
        }

      /* Record permanently how this parm was passed.  */
      set_decl_incoming_rtl (parm, data.entry_parm);

      /* Update info on where next arg arrives in registers.  */
      FUNCTION_ARG_ADVANCE (all.args_so_far, data.promoted_mode,
                            data.passed_type, data.named_arg);

      assign_parm_adjust_stack_rtl (&data);

      if (assign_parm_setup_block_p (&data))
        assign_parm_setup_block (parm, &data);
      else if (data.passed_pointer || use_register_for_decl (parm))
        assign_parm_setup_reg (&all, parm, &data);
      else
        assign_parm_setup_stack (&all, parm, &data);
    }

  if (targetm.calls.split_complex_arg && fnargs != all.orig_fnargs)
    assign_parms_unsplit_complex (all.orig_fnargs, fnargs);

  /* Output all parameter conversion instructions (possibly including calls)
     now that all parameters have been copied out of hard registers.  */
  emit_insn (all.conversion_insns);

  /* If we are receiving a struct value address as the first argument, set up
     the RTL for the function result. As this might require code to convert
     the transmitted address to Pmode, we do this here to ensure that possible
     preliminary conversions of the address have been emitted already.  */
  if (all.function_result_decl)
    {
      tree result = DECL_RESULT (current_function_decl);
      rtx addr = DECL_RTL (all.function_result_decl);
      rtx x;

      addr = convert_memory_address (Pmode, addr);
      x = gen_rtx_MEM (DECL_MODE (result), addr);
      set_mem_attributes (x, result, 1);
      SET_DECL_RTL (result, x);
    }

  /* We have aligned all the args, so add space for the pretend args.  */
  current_function_pretend_args_size = all.pretend_args_size;
  all.stack_args_size.constant += all.extra_pretend_bytes;
  current_function_args_size = all.stack_args_size.constant;

  /* Adjust function incoming argument size for alignment and
     minimum length.  */

#ifdef REG_PARM_STACK_SPACE
  current_function_args_size = MAX (current_function_args_size,
                                    REG_PARM_STACK_SPACE (fndecl));
#endif

  current_function_args_size
    = ((current_function_args_size + STACK_BYTES - 1)
       / STACK_BYTES) * STACK_BYTES;

#ifdef ARGS_GROW_DOWNWARD
  current_function_arg_offset_rtx
    = (all.stack_args_size.var == 0 ? GEN_INT (-all.stack_args_size.constant)
       : expand_expr (size_diffop (all.stack_args_size.var,
                                   size_int (-all.stack_args_size.constant)),
                      NULL_RTX, VOIDmode, 0));
#else
  current_function_arg_offset_rtx = ARGS_SIZE_RTX (all.stack_args_size);
#endif

  /* See how many bytes, if any, of its args a function should try to pop
     on return.  */

  current_function_pops_args = RETURN_POPS_ARGS (fndecl, TREE_TYPE (fndecl),
                                                 current_function_args_size);

  /* For stdarg.h function, save info about
     regs and stack space used by the named args.  */

  current_function_args_info = all.args_so_far;

  /* Set the rtx used for the function return value.  Put this in its
     own variable so any optimizers that need this information don't have
     to include tree.h.  Do this here so it gets done when an inlined
     function gets output.  */

  current_function_return_rtx
    = (DECL_RTL_SET_P (DECL_RESULT (fndecl))
       ? DECL_RTL (DECL_RESULT (fndecl)) : NULL_RTX);

  /* If scalar return value was computed in a pseudo-reg, or was a named
     return value that got dumped to the stack, copy that to the hard
     return register.  */
  if (DECL_RTL_SET_P (DECL_RESULT (fndecl)))
    {
      tree decl_result = DECL_RESULT (fndecl);
      rtx decl_rtl = DECL_RTL (decl_result);

      if (REG_P (decl_rtl)
          ? REGNO (decl_rtl) >= FIRST_PSEUDO_REGISTER
          : DECL_REGISTER (decl_result))
        {
          rtx real_decl_rtl;

#ifdef FUNCTION_OUTGOING_VALUE
          real_decl_rtl = FUNCTION_OUTGOING_VALUE (TREE_TYPE (decl_result),
                                                   fndecl);
#else
          real_decl_rtl = FUNCTION_VALUE (TREE_TYPE (decl_result),
                                          fndecl);
#endif
          REG_FUNCTION_VALUE_P (real_decl_rtl) = 1;
          /* The delay slot scheduler assumes that current_function_return_rtx
             holds the hard register containing the return value, not a
             temporary pseudo.  */
          current_function_return_rtx = real_decl_rtl;
        }
    }
}
\f
/* Indicate whether REGNO is an incoming argument to the current function
   that was promoted to a wider mode.  If so, return the RTX for the
   register (to get its mode).  PMODE and PUNSIGNEDP are set to the mode
   that REGNO is promoted from and whether the promotion was signed or
   unsigned.  */

rtx
promoted_input_arg (unsigned int regno, enum machine_mode *pmode, int *punsignedp)
{
  tree arg;

  for (arg = DECL_ARGUMENTS (current_function_decl); arg;
       arg = TREE_CHAIN (arg))
    if (REG_P (DECL_INCOMING_RTL (arg))
        && REGNO (DECL_INCOMING_RTL (arg)) == regno
        && TYPE_MODE (DECL_ARG_TYPE (arg)) == TYPE_MODE (TREE_TYPE (arg)))
      {
        enum machine_mode mode = TYPE_MODE (TREE_TYPE (arg));
        int unsignedp = TYPE_UNSIGNED (TREE_TYPE (arg));

        mode = promote_mode (TREE_TYPE (arg), mode, &unsignedp, 1);
        if (mode == GET_MODE (DECL_INCOMING_RTL (arg))
            && mode != DECL_MODE (arg))
          {
            *pmode = DECL_MODE (arg);
            *punsignedp = unsignedp;
            return DECL_INCOMING_RTL (arg);
          }
      }

  return 0;
}

\f
/* Compute the size and offset from the start of the stacked arguments for a
   parm passed in mode PASSED_MODE and with type TYPE.

   INITIAL_OFFSET_PTR points to the current offset into the stacked
   arguments.

   The starting offset and size for this parm are returned in
   LOCATE->OFFSET and LOCATE->SIZE, respectively.  When IN_REGS is
   nonzero, the offset is that of stack slot, which is returned in
   LOCATE->SLOT_OFFSET.  LOCATE->ALIGNMENT_PAD is the amount of
   padding required from the initial offset ptr to the stack slot.

   IN_REGS is nonzero if the argument will be passed in registers.  It will
   never be set if REG_PARM_STACK_SPACE is not defined.

   FNDECL is the function in which the argument was defined.

   There are two types of rounding that are done.  The first, controlled by
   FUNCTION_ARG_BOUNDARY, forces the offset from the start of the argument
   list to be aligned to the specific boundary (in bits).  This rounding
   affects the initial and starting offsets, but not the argument size.

   The second, controlled by FUNCTION_ARG_PADDING and PARM_BOUNDARY,
   optionally rounds the size of the parm to PARM_BOUNDARY.  The
   initial offset is not affected by this rounding, while the size always
   is and the starting offset may be.  */

/*  LOCATE->OFFSET will be negative for ARGS_GROW_DOWNWARD case;
    INITIAL_OFFSET_PTR is positive because locate_and_pad_parm's
    callers pass in the total size of args so far as
    INITIAL_OFFSET_PTR.  LOCATE->SIZE is always positive.  */

void
locate_and_pad_parm (enum machine_mode passed_mode, tree type, int in_regs,
                     int partial, tree fndecl ATTRIBUTE_UNUSED,
                     struct args_size *initial_offset_ptr,
                     struct locate_and_pad_arg_data *locate)
{
  tree sizetree;
  enum direction where_pad;
  int boundary;
  int reg_parm_stack_space = 0;
  int part_size_in_regs;

#ifdef REG_PARM_STACK_SPACE
  reg_parm_stack_space = REG_PARM_STACK_SPACE (fndecl);

  /* If we have found a stack parm before we reach the end of the
     area reserved for registers, skip that area.  */
  if (! in_regs)
    {
      if (reg_parm_stack_space > 0)
        {
          if (initial_offset_ptr->var)
            {
              initial_offset_ptr->var
                = size_binop (MAX_EXPR, ARGS_SIZE_TREE (*initial_offset_ptr),
                              ssize_int (reg_parm_stack_space));
              initial_offset_ptr->constant = 0;
            }
          else if (initial_offset_ptr->constant < reg_parm_stack_space)
            initial_offset_ptr->constant = reg_parm_stack_space;
        }
    }
#endif /* REG_PARM_STACK_SPACE */

  part_size_in_regs = 0;
  if (reg_parm_stack_space == 0)
    part_size_in_regs = ((partial * UNITS_PER_WORD)
                         / (PARM_BOUNDARY / BITS_PER_UNIT)
                         * (PARM_BOUNDARY / BITS_PER_UNIT));

  sizetree
    = type ? size_in_bytes (type) : size_int (GET_MODE_SIZE (passed_mode));
  where_pad = FUNCTION_ARG_PADDING (passed_mode, type);
  boundary = FUNCTION_ARG_BOUNDARY (passed_mode, type);
  locate->where_pad = where_pad;

#ifdef ARGS_GROW_DOWNWARD
  locate->slot_offset.constant = -initial_offset_ptr->constant;
  if (initial_offset_ptr->var)
    locate->slot_offset.var = size_binop (MINUS_EXPR, ssize_int (0),
                                          initial_offset_ptr->var);

  {
    tree s2 = sizetree;
    if (where_pad != none
        && (!host_integerp (sizetree, 1)
            || (tree_low_cst (sizetree, 1) * BITS_PER_UNIT) % PARM_BOUNDARY))
      s2 = round_up (s2, PARM_BOUNDARY / BITS_PER_UNIT);
    SUB_PARM_SIZE (locate->slot_offset, s2);
  }

  locate->slot_offset.constant += part_size_in_regs;

  if (!in_regs
#ifdef REG_PARM_STACK_SPACE
      || REG_PARM_STACK_SPACE (fndecl) > 0
#endif
     )
    pad_to_arg_alignment (&locate->slot_offset, boundary,
                          &locate->alignment_pad);

  locate->size.constant = (-initial_offset_ptr->constant
                           - locate->slot_offset.constant);
  if (initial_offset_ptr->var)
    locate->size.var = size_binop (MINUS_EXPR,
                                   size_binop (MINUS_EXPR,
                                               ssize_int (0),
                                               initial_offset_ptr->var),
                                   locate->slot_offset.var);

  /* Pad_below needs the pre-rounded size to know how much to pad
     below.  */
  locate->offset = locate->slot_offset;
  if (where_pad == downward)
    pad_below (&locate->offset, passed_mode, sizetree);

#else /* !ARGS_GROW_DOWNWARD */
  if (!in_regs
#ifdef REG_PARM_STACK_SPACE
      || REG_PARM_STACK_SPACE (fndecl) > 0
#endif
      )
    pad_to_arg_alignment (initial_offset_ptr, boundary,
                          &locate->alignment_pad);
  locate->slot_offset = *initial_offset_ptr;

#ifdef PUSH_ROUNDING
  if (passed_mode != BLKmode)
    sizetree = size_int (PUSH_ROUNDING (TREE_INT_CST_LOW (sizetree)));
#endif

  /* Pad_below needs the pre-rounded size to know how much to pad below
     so this must be done before rounding up.  */
  locate->offset = locate->slot_offset;
  if (where_pad == downward)
    pad_below (&locate->offset, passed_mode, sizetree);

  if (where_pad != none
      && (!host_integerp (sizetree, 1)
          || (tree_low_cst (sizetree, 1) * BITS_PER_UNIT) % PARM_BOUNDARY))
    sizetree = round_up (sizetree, PARM_BOUNDARY / BITS_PER_UNIT);

  ADD_PARM_SIZE (locate->size, sizetree);

  locate->size.constant -= part_size_in_regs;
#endif /* ARGS_GROW_DOWNWARD */
}

/* Round the stack offset in *OFFSET_PTR up to a multiple of BOUNDARY.
   BOUNDARY is measured in bits, but must be a multiple of a storage unit.  */

static void
pad_to_arg_alignment (struct args_size *offset_ptr, int boundary,
                      struct args_size *alignment_pad)
{
  tree save_var = NULL_TREE;
  HOST_WIDE_INT save_constant = 0;
  int boundary_in_bytes = boundary / BITS_PER_UNIT;
  HOST_WIDE_INT sp_offset = STACK_POINTER_OFFSET;

#ifdef SPARC_STACK_BOUNDARY_HACK
  /* The sparc port has a bug.  It sometimes claims a STACK_BOUNDARY
     higher than the real alignment of %sp.  However, when it does this,
     the alignment of %sp+STACK_POINTER_OFFSET will be STACK_BOUNDARY.
     This is a temporary hack while the sparc port is fixed.  */
  if (SPARC_STACK_BOUNDARY_HACK)
    sp_offset = 0;
#endif

  if (boundary > PARM_BOUNDARY && boundary > STACK_BOUNDARY)
    {
      save_var = offset_ptr->var;
      save_constant = offset_ptr->constant;
    }

  alignment_pad->var = NULL_TREE;
  alignment_pad->constant = 0;

  if (boundary > BITS_PER_UNIT)
    {
      if (offset_ptr->var)
        {
          tree sp_offset_tree = ssize_int (sp_offset);
          tree offset = size_binop (PLUS_EXPR,
                                    ARGS_SIZE_TREE (*offset_ptr),
                                    sp_offset_tree);
#ifdef ARGS_GROW_DOWNWARD
          tree rounded = round_down (offset, boundary / BITS_PER_UNIT);
#else
          tree rounded = round_up   (offset, boundary / BITS_PER_UNIT);
#endif

          offset_ptr->var = size_binop (MINUS_EXPR, rounded, sp_offset_tree);
          /* ARGS_SIZE_TREE includes constant term.  */
          offset_ptr->constant = 0;
          if (boundary > PARM_BOUNDARY && boundary > STACK_BOUNDARY)
            alignment_pad->var = size_binop (MINUS_EXPR, offset_ptr->var,
                                             save_var);
        }
      else
        {
          offset_ptr->constant = -sp_offset +
#ifdef ARGS_GROW_DOWNWARD
            FLOOR_ROUND (offset_ptr->constant + sp_offset, boundary_in_bytes);
#else
            CEIL_ROUND (offset_ptr->constant + sp_offset, boundary_in_bytes);
#endif
            if (boundary > PARM_BOUNDARY && boundary > STACK_BOUNDARY)
              alignment_pad->constant = offset_ptr->constant - save_constant;
        }
    }
}

static void
pad_below (struct args_size *offset_ptr, enum machine_mode passed_mode, tree sizetree)
{
  if (passed_mode != BLKmode)
    {
      if (GET_MODE_BITSIZE (passed_mode) % PARM_BOUNDARY)
        offset_ptr->constant
          += (((GET_MODE_BITSIZE (passed_mode) + PARM_BOUNDARY - 1)
               / PARM_BOUNDARY * PARM_BOUNDARY / BITS_PER_UNIT)
              - GET_MODE_SIZE (passed_mode));
    }
  else
    {
      if (TREE_CODE (sizetree) != INTEGER_CST
          || (TREE_INT_CST_LOW (sizetree) * BITS_PER_UNIT) % PARM_BOUNDARY)
        {
          /* Round the size up to multiple of PARM_BOUNDARY bits.  */
          tree s2 = round_up (sizetree, PARM_BOUNDARY / BITS_PER_UNIT);
          /* Add it in.  */
          ADD_PARM_SIZE (*offset_ptr, s2);
          SUB_PARM_SIZE (*offset_ptr, sizetree);
        }
    }
}
\f
/* Walk the tree of blocks describing the binding levels within a function
   and warn about variables the might be killed by setjmp or vfork.
   This is done after calling flow_analysis and before global_alloc
   clobbers the pseudo-regs to hard regs.  */

void
setjmp_vars_warning (tree block)
{
  tree decl, sub;

  for (decl = BLOCK_VARS (block); decl; decl = TREE_CHAIN (decl))
    {
      if (TREE_CODE (decl) == VAR_DECL
          && DECL_RTL_SET_P (decl)
          && REG_P (DECL_RTL (decl))
          && regno_clobbered_at_setjmp (REGNO (DECL_RTL (decl))))
        warning ("%Jvariable '%D' might be clobbered by `longjmp' or `vfork'",
                 decl, decl);
    }

  for (sub = BLOCK_SUBBLOCKS (block); sub; sub = TREE_CHAIN (sub))
    setjmp_vars_warning (sub);
}

/* Do the appropriate part of setjmp_vars_warning
   but for arguments instead of local variables.  */

void
setjmp_args_warning (void)
{
  tree decl;
  for (decl = DECL_ARGUMENTS (current_function_decl);
       decl; decl = TREE_CHAIN (decl))
    if (DECL_RTL (decl) != 0
        && REG_P (DECL_RTL (decl))
        && regno_clobbered_at_setjmp (REGNO (DECL_RTL (decl))))
      warning ("%Jargument '%D' might be clobbered by `longjmp' or `vfork'",
               decl, decl);
}

\f
/* Identify BLOCKs referenced by more than one NOTE_INSN_BLOCK_{BEG,END},
   and create duplicate blocks.  */
/* ??? Need an option to either create block fragments or to create
   abstract origin duplicates of a source block.  It really depends
   on what optimization has been performed.  */

void
reorder_blocks (void)
{
  tree block = DECL_INITIAL (current_function_decl);
  varray_type block_stack;

  if (block == NULL_TREE)
    return;

  VARRAY_TREE_INIT (block_stack, 10, "block_stack");

  /* Reset the TREE_ASM_WRITTEN bit for all blocks.  */
  clear_block_marks (block);

  /* Prune the old trees away, so that they don't get in the way.  */
  BLOCK_SUBBLOCKS (block) = NULL_TREE;
  BLOCK_CHAIN (block) = NULL_TREE;

  /* Recreate the block tree from the note nesting.  */
  reorder_blocks_1 (get_insns (), block, &block_stack);
  BLOCK_SUBBLOCKS (block) = blocks_nreverse (BLOCK_SUBBLOCKS (block));

  /* Remove deleted blocks from the block fragment chains.  */
  reorder_fix_fragments (block);
}

/* Helper function for reorder_blocks.  Reset TREE_ASM_WRITTEN.  */

void
clear_block_marks (tree block)
{
  while (block)
    {
      TREE_ASM_WRITTEN (block) = 0;
      clear_block_marks (BLOCK_SUBBLOCKS (block));
      block = BLOCK_CHAIN (block);
    }
}

static void
reorder_blocks_1 (rtx insns, tree current_block, varray_type *p_block_stack)
{
  rtx insn;

  for (insn = insns; insn; insn = NEXT_INSN (insn))
    {
      if (NOTE_P (insn))
        {
          if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG)
            {
              tree block = NOTE_BLOCK (insn);

              /* If we have seen this block before, that means it now
                 spans multiple address regions.  Create a new fragment.  */
              if (TREE_ASM_WRITTEN (block))
                {
                  tree new_block = copy_node (block);
                  tree origin;

                  origin = (BLOCK_FRAGMENT_ORIGIN (block)
                            ? BLOCK_FRAGMENT_ORIGIN (block)
                            : block);
                  BLOCK_FRAGMENT_ORIGIN (new_block) = origin;
                  BLOCK_FRAGMENT_CHAIN (new_block)
                    = BLOCK_FRAGMENT_CHAIN (origin);
                  BLOCK_FRAGMENT_CHAIN (origin) = new_block;

                  NOTE_BLOCK (insn) = new_block;
                  block = new_block;
                }

              BLOCK_SUBBLOCKS (block) = 0;
              TREE_ASM_WRITTEN (block) = 1;
              /* When there's only one block for the entire function,
                 current_block == block and we mustn't do this, it
                 will cause infinite recursion.  */
              if (block != current_block)
                {
                  BLOCK_SUPERCONTEXT (block) = current_block;
                  BLOCK_CHAIN (block) = BLOCK_SUBBLOCKS (current_block);
                  BLOCK_SUBBLOCKS (current_block) = block;
                  current_block = block;
                }
              VARRAY_PUSH_TREE (*p_block_stack, block);
            }
          else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END)
            {
              NOTE_BLOCK (insn) = VARRAY_TOP_TREE (*p_block_stack);
              VARRAY_POP (*p_block_stack);
              BLOCK_SUBBLOCKS (current_block)
                = blocks_nreverse (BLOCK_SUBBLOCKS (current_block));
              current_block = BLOCK_SUPERCONTEXT (current_block);
            }
        }
    }
}

/* Rationalize BLOCK_FRAGMENT_ORIGIN.  If an origin block no longer
   appears in the block tree, select one of the fragments to become
   the new origin block.  */

static void
reorder_fix_fragments (tree block)
{
  while (block)
    {
      tree dup_origin = BLOCK_FRAGMENT_ORIGIN (block);
      tree new_origin = NULL_TREE;

      if (dup_origin)
        {
          if (! TREE_ASM_WRITTEN (dup_origin))
            {
              new_origin = BLOCK_FRAGMENT_CHAIN (dup_origin);

              /* Find the first of the remaining fragments.  There must
                 be at least one -- the current block.  */
              while (! TREE_ASM_WRITTEN (new_origin))
                new_origin = BLOCK_FRAGMENT_CHAIN (new_origin);
              BLOCK_FRAGMENT_ORIGIN (new_origin) = NULL_TREE;
            }
        }
      else if (! dup_origin)
        new_origin = block;

      /* Re-root the rest of the fragments to the new origin.  In the
         case that DUP_ORIGIN was null, that means BLOCK was the origin
         of a chain of fragments and we want to remove those fragments
         that didn't make it to the output.  */
      if (new_origin)
        {
          tree *pp = &BLOCK_FRAGMENT_CHAIN (new_origin);
          tree chain = *pp;

          while (chain)
            {
              if (TREE_ASM_WRITTEN (chain))
                {
                  BLOCK_FRAGMENT_ORIGIN (chain) = new_origin;
                  *pp = chain;
                  pp = &BLOCK_FRAGMENT_CHAIN (chain);
                }
              chain = BLOCK_FRAGMENT_CHAIN (chain);
            }
          *pp = NULL_TREE;
        }

      reorder_fix_fragments (BLOCK_SUBBLOCKS (block));
      block = BLOCK_CHAIN (block);
    }
}

/* Reverse the order of elements in the chain T of blocks,
   and return the new head of the chain (old last element).  */

tree
blocks_nreverse (tree t)
{
  tree prev = 0, decl, next;
  for (decl = t; decl; decl = next)
    {
      next = BLOCK_CHAIN (decl);
      BLOCK_CHAIN (decl) = prev;
      prev = decl;
    }
  return prev;
}

/* Count the subblocks of the list starting with BLOCK.  If VECTOR is
   non-NULL, list them all into VECTOR, in a depth-first preorder
   traversal of the block tree.  Also clear TREE_ASM_WRITTEN in all
   blocks.  */

static int
all_blocks (tree block, tree *vector)
{
  int n_blocks = 0;

  while (block)
    {
      TREE_ASM_WRITTEN (block) = 0;

      /* Record this block.  */
      if (vector)
        vector[n_blocks] = block;

      ++n_blocks;

      /* Record the subblocks, and their subblocks...  */
      n_blocks += all_blocks (BLOCK_SUBBLOCKS (block),
                              vector ? vector + n_blocks : 0);
      block = BLOCK_CHAIN (block);
    }

  return n_blocks;
}

/* Return a vector containing all the blocks rooted at BLOCK.  The
   number of elements in the vector is stored in N_BLOCKS_P.  The
   vector is dynamically allocated; it is the caller's responsibility
   to call `free' on the pointer returned.  */

static tree *
get_block_vector (tree block, int *n_blocks_p)
{
  tree *block_vector;

  *n_blocks_p = all_blocks (block, NULL);
  block_vector = xmalloc (*n_blocks_p * sizeof (tree));
  all_blocks (block, block_vector);

  return block_vector;
}

static GTY(()) int next_block_index = 2;

/* Set BLOCK_NUMBER for all the blocks in FN.  */

void
number_blocks (tree fn)
{
  int i;
  int n_blocks;
  tree *block_vector;

  /* For SDB and XCOFF debugging output, we start numbering the blocks
     from 1 within each function, rather than keeping a running
     count.  */
#if defined (SDB_DEBUGGING_INFO) || defined (XCOFF_DEBUGGING_INFO)
  if (write_symbols == SDB_DEBUG || write_symbols == XCOFF_DEBUG)
    next_block_index = 1;
#endif

  block_vector = get_block_vector (DECL_INITIAL (fn), &n_blocks);

  /* The top-level BLOCK isn't numbered at all.  */
  for (i = 1; i < n_blocks; ++i)
    /* We number the blocks from two.  */
    BLOCK_NUMBER (block_vector[i]) = next_block_index++;

  free (block_vector);

  return;
}

/* If VAR is present in a subblock of BLOCK, return the subblock.  */

tree
debug_find_var_in_block_tree (tree var, tree block)
{
  tree t;

  for (t = BLOCK_VARS (block); t; t = TREE_CHAIN (t))
    if (t == var)
      return block;

  for (t = BLOCK_SUBBLOCKS (block); t; t = TREE_CHAIN (t))
    {
      tree ret = debug_find_var_in_block_tree (var, t);
      if (ret)
        return ret;
    }

  return NULL_TREE;
}
\f
/* Allocate a function structure for FNDECL and set its contents
   to the defaults.  */

void
allocate_struct_function (tree fndecl)
{
  tree result;
  tree fntype = fndecl ? TREE_TYPE (fndecl) : NULL_TREE;

  cfun = ggc_alloc_cleared (sizeof (struct function));

  cfun->stack_alignment_needed = STACK_BOUNDARY;
  cfun->preferred_stack_boundary = STACK_BOUNDARY;

  current_function_funcdef_no = funcdef_no++;

  cfun->function_frequency = FUNCTION_FREQUENCY_NORMAL;

  init_stmt_for_function ();
  init_eh_for_function ();

  lang_hooks.function.init (cfun);
  if (init_machine_status)
    cfun->machine = (*init_machine_status) ();

  if (fndecl == NULL)
    return;

  DECL_STRUCT_FUNCTION (fndecl) = cfun;
  cfun->decl = fndecl;

  result = DECL_RESULT (fndecl);
  if (aggregate_value_p (result, fndecl))
    {
#ifdef PCC_STATIC_STRUCT_RETURN
      current_function_returns_pcc_struct = 1;
#endif
      current_function_returns_struct = 1;
    }

  current_function_returns_pointer = POINTER_TYPE_P (TREE_TYPE (result));

  current_function_stdarg
    = (fntype
       && TYPE_ARG_TYPES (fntype) != 0
       && (TREE_VALUE (tree_last (TYPE_ARG_TYPES (fntype)))
           != void_type_node));
}

/* Reset cfun, and other non-struct-function variables to defaults as
   appropriate for emitting rtl at the start of a function.  */

static void
prepare_function_start (tree fndecl)
{
  if (fndecl && DECL_STRUCT_FUNCTION (fndecl))
    cfun = DECL_STRUCT_FUNCTION (fndecl);
  else
    allocate_struct_function (fndecl);
  init_emit ();
  init_varasm_status (cfun);
  init_expr ();

  cse_not_expected = ! optimize;

  /* Caller save not needed yet.  */
  caller_save_needed = 0;

  /* We haven't done register allocation yet.  */
  reg_renumber = 0;

  /* Indicate that we need to distinguish between the return value of the
     present function and the return value of a function being called.  */
  rtx_equal_function_value_matters = 1;

  /* Indicate that we have not instantiated virtual registers yet.  */
  virtuals_instantiated = 0;

  /* Indicate that we want CONCATs now.  */
  generating_concat_p = 1;

  /* Indicate we have no need of a frame pointer yet.  */
  frame_pointer_needed = 0;
}

/* Initialize the rtl expansion mechanism so that we can do simple things
   like generate sequences.  This is used to provide a context during global
   initialization of some passes.  */
void
init_dummy_function_start (void)
{
  prepare_function_start (NULL);
}

/* Generate RTL for the start of the function SUBR (a FUNCTION_DECL tree node)
   and initialize static variables for generating RTL for the statements
   of the function.  */

void
init_function_start (tree subr)
{
  prepare_function_start (subr);

  /* Prevent ever trying to delete the first instruction of a
     function.  Also tell final how to output a linenum before the
     function prologue.  Note linenums could be missing, e.g. when
     compiling a Java .class file.  */
  if (! DECL_IS_BUILTIN (subr))
    emit_line_note (DECL_SOURCE_LOCATION (subr));

  /* Make sure first insn is a note even if we don't want linenums.
     This makes sure the first insn will never be deleted.
     Also, final expects a note to appear there.  */
  emit_note (NOTE_INSN_DELETED);

  /* Warn if this value is an aggregate type,
     regardless of which calling convention we are using for it.  */
  if (warn_aggregate_return
      && AGGREGATE_TYPE_P (TREE_TYPE (DECL_RESULT (subr))))
    warning ("function returns an aggregate");
}

/* Make sure all values used by the optimization passes have sane
   defaults.  */
void
init_function_for_compilation (void)
{
  reg_renumber = 0;

  /* No prologue/epilogue insns yet.  */
  VARRAY_GROW (prologue, 0);
  VARRAY_GROW (epilogue, 0);
  VARRAY_GROW (sibcall_epilogue, 0);
}

/* Expand a call to __main at the beginning of a possible main function.  */

#if defined(INIT_SECTION_ASM_OP) && !defined(INVOKE__main)
#undef HAS_INIT_SECTION
#define HAS_INIT_SECTION
#endif

void
expand_main_function (void)
{
#ifdef FORCE_PREFERRED_STACK_BOUNDARY_IN_MAIN
  if (FORCE_PREFERRED_STACK_BOUNDARY_IN_MAIN)
    {
      int align = PREFERRED_STACK_BOUNDARY / BITS_PER_UNIT;
      rtx tmp, seq;

      start_sequence ();
      /* Forcibly align the stack.  */
#ifdef STACK_GROWS_DOWNWARD
      tmp = expand_simple_binop (Pmode, AND, stack_pointer_rtx, GEN_INT(-align),
                                 stack_pointer_rtx, 1, OPTAB_WIDEN);
#else
      tmp = expand_simple_binop (Pmode, PLUS, stack_pointer_rtx,
                                 GEN_INT (align - 1), NULL_RTX, 1, OPTAB_WIDEN);
      tmp = expand_simple_binop (Pmode, AND, tmp, GEN_INT (-align),
                                 stack_pointer_rtx, 1, OPTAB_WIDEN);
#endif
      if (tmp != stack_pointer_rtx)
        emit_move_insn (stack_pointer_rtx, tmp);

      /* Enlist allocate_dynamic_stack_space to pick up the pieces.  */
      tmp = force_reg (Pmode, const0_rtx);
      allocate_dynamic_stack_space (tmp, NULL_RTX, BIGGEST_ALIGNMENT);
      seq = get_insns ();
      end_sequence ();

      for (tmp = get_last_insn (); tmp; tmp = PREV_INSN (tmp))
        if (NOTE_P (tmp) && NOTE_LINE_NUMBER (tmp) == NOTE_INSN_FUNCTION_BEG)
          break;
      if (tmp)
        emit_insn_before (seq, tmp);
      else
        emit_insn (seq);
    }
#endif

#ifndef HAS_INIT_SECTION
  emit_library_call (init_one_libfunc (NAME__MAIN), LCT_NORMAL, VOIDmode, 0);
#endif
}
\f
/* The PENDING_SIZES represent the sizes of variable-sized types.
   Create RTL for the various sizes now (using temporary variables),
   so that we can refer to the sizes from the RTL we are generating
   for the current function.  The PENDING_SIZES are a TREE_LIST.  The
   TREE_VALUE of each node is a SAVE_EXPR.  */

void
expand_pending_sizes (tree pending_sizes)
{
  tree tem;

  /* Evaluate now the sizes of any types declared among the arguments.  */
  for (tem = pending_sizes; tem; tem = TREE_CHAIN (tem))
    expand_expr (TREE_VALUE (tem), const0_rtx, VOIDmode, 0);
}

/* Start the RTL for a new function, and set variables used for
   emitting RTL.
   SUBR is the FUNCTION_DECL node.
   PARMS_HAVE_CLEANUPS is nonzero if there are cleanups associated with
   the function's parameters, which must be run at any return statement.  */

void
expand_function_start (tree subr)
{
  /* Make sure volatile mem refs aren't considered
     valid operands of arithmetic insns.  */
  init_recog_no_volatile ();

  current_function_profile
    = (profile_flag
       && ! DECL_NO_INSTRUMENT_FUNCTION_ENTRY_EXIT (subr));

  current_function_limit_stack
    = (stack_limit_rtx != NULL_RTX && ! DECL_NO_LIMIT_STACK (subr));

  /* Make the label for return statements to jump to.  Do not special
     case machines with special return instructions -- they will be
     handled later during jump, ifcvt, or epilogue creation.  */
  return_label = gen_label_rtx ();

  /* Initialize rtx used to return the value.  */
  /* Do this before assign_parms so that we copy the struct value address
     before any library calls that assign parms might generate.  */

  /* Decide whether to return the value in memory or in a register.  */
  if (aggregate_value_p (DECL_RESULT (subr), subr))
    {
      /* Returning something that won't go in a register.  */
      rtx value_address = 0;

#ifdef PCC_STATIC_STRUCT_RETURN
      if (current_function_returns_pcc_struct)
        {
          int size = int_size_in_bytes (TREE_TYPE (DECL_RESULT (subr)));
          value_address = assemble_static_space (size);
        }
      else
#endif
        {
          rtx sv = targetm.calls.struct_value_rtx (TREE_TYPE (subr), 1);
          /* Expect to be passed the address of a place to store the value.
             If it is passed as an argument, assign_parms will take care of
             it.  */
          if (sv)
            {
              value_address = gen_reg_rtx (Pmode);
              emit_move_insn (value_address, sv);
            }
        }
      if (value_address)
        {
          rtx x = gen_rtx_MEM (DECL_MODE (DECL_RESULT (subr)), value_address);
          set_mem_attributes (x, DECL_RESULT (subr), 1);
          SET_DECL_RTL (DECL_RESULT (subr), x);
        }
    }
  else if (DECL_MODE (DECL_RESULT (subr)) == VOIDmode)
    /* If return mode is void, this decl rtl should not be used.  */
    SET_DECL_RTL (DECL_RESULT (subr), NULL_RTX);
  else
    {
      /* Compute the return values into a pseudo reg, which we will copy
         into the true return register after the cleanups are done.  */

      /* In order to figure out what mode to use for the pseudo, we
         figure out what the mode of the eventual return register will
         actually be, and use that.  */
      rtx hard_reg
        = hard_function_value (TREE_TYPE (DECL_RESULT (subr)),
                               subr, 1);

      /* Structures that are returned in registers are not aggregate_value_p,
         so we may see a PARALLEL or a REG.  */
      if (REG_P (hard_reg))
        SET_DECL_RTL (DECL_RESULT (subr), gen_reg_rtx (GET_MODE (hard_reg)));
      else if (GET_CODE (hard_reg) == PARALLEL)
        SET_DECL_RTL (DECL_RESULT (subr), gen_group_rtx (hard_reg));
      else
        abort ();

      /* Set DECL_REGISTER flag so that expand_function_end will copy the
         result to the real return register(s).  */
      DECL_REGISTER (DECL_RESULT (subr)) = 1;
    }

  /* Initialize rtx for parameters and local variables.
     In some cases this requires emitting insns.  */
  assign_parms (subr);

  /* If function gets a static chain arg, store it.  */
  if (cfun->static_chain_decl)
    {
      tree parm = cfun->static_chain_decl;
      rtx local = gen_reg_rtx (Pmode);

      set_decl_incoming_rtl (parm, static_chain_incoming_rtx);
      SET_DECL_RTL (parm, local);
      maybe_set_unchanging (local, parm);
      mark_reg_pointer (local, TYPE_ALIGN (TREE_TYPE (TREE_TYPE (parm))));

      emit_move_insn (local, static_chain_incoming_rtx);
    }

  /* If the function receives a non-local goto, then store the
     bits we need to restore the frame pointer.  */
  if (cfun->nonlocal_goto_save_area)
    {
      tree t_save;
      rtx r_save;

      /* ??? We need to do this save early.  Unfortunately here is
         before the frame variable gets declared.  Help out...  */
      expand_var (TREE_OPERAND (cfun->nonlocal_goto_save_area, 0));

      t_save = build4 (ARRAY_REF, ptr_type_node,
                       cfun->nonlocal_goto_save_area,
                       integer_zero_node, NULL_TREE, NULL_TREE);
      r_save = expand_expr (t_save, NULL_RTX, VOIDmode, EXPAND_WRITE);
      r_save = convert_memory_address (Pmode, r_save);

      emit_move_insn (r_save, virtual_stack_vars_rtx);
      update_nonlocal_goto_save_area ();
    }

  /* The following was moved from init_function_start.
     The move is supposed to make sdb output more accurate.  */
  /* Indicate the beginning of the function body,
     as opposed to parm setup.  */
  emit_note (NOTE_INSN_FUNCTION_BEG);

  if (!NOTE_P (get_last_insn ()))
    emit_note (NOTE_INSN_DELETED);
  parm_birth_insn = get_last_insn ();

  if (current_function_profile)
    {
#ifdef PROFILE_HOOK
      PROFILE_HOOK (current_function_funcdef_no);
#endif
    }

  /* After the display initializations is where the tail-recursion label
     should go, if we end up needing one.   Ensure we have a NOTE here
     since some things (like trampolines) get placed before this.  */
  tail_recursion_reentry = emit_note (NOTE_INSN_DELETED);

  /* Evaluate now the sizes of any types declared among the arguments.  */
  expand_pending_sizes (nreverse (get_pending_sizes ()));

  /* Make sure there is a line number after the function entry setup code.  */
  force_next_line_note ();
}
\f
/* Undo the effects of init_dummy_function_start.  */
void
expand_dummy_function_end (void)
{
  /* End any sequences that failed to be closed due to syntax errors.  */
  while (in_sequence_p ())
    end_sequence ();

  /* Outside function body, can't compute type's actual size
     until next function's body starts.  */

  free_after_parsing (cfun);
  free_after_compilation (cfun);
  cfun = 0;
}

/* Call DOIT for each hard register used as a return value from
   the current function.  */

void
diddle_return_value (void (*doit) (rtx, void *), void *arg)
{
  rtx outgoing = current_function_return_rtx;

  if (! outgoing)
    return;

  if (REG_P (outgoing))
    (*doit) (outgoing, arg);
  else if (GET_CODE (outgoing) == PARALLEL)
    {
      int i;

      for (i = 0; i < XVECLEN (outgoing, 0); i++)
        {
          rtx x = XEXP (XVECEXP (outgoing, 0, i), 0);

          if (REG_P (x) && REGNO (x) < FIRST_PSEUDO_REGISTER)
            (*doit) (x, arg);
        }
    }
}

static void
do_clobber_return_reg (rtx reg, void *arg ATTRIBUTE_UNUSED)
{
  emit_insn (gen_rtx_CLOBBER (VOIDmode, reg));
}

void
clobber_return_register (void)
{
  diddle_return_value (do_clobber_return_reg, NULL);

  /* In case we do use pseudo to return value, clobber it too.  */
  if (DECL_RTL_SET_P (DECL_RESULT (current_function_decl)))
    {
      tree decl_result = DECL_RESULT (current_function_decl);
      rtx decl_rtl = DECL_RTL (decl_result);
      if (REG_P (decl_rtl) && REGNO (decl_rtl) >= FIRST_PSEUDO_REGISTER)
        {
          do_clobber_return_reg (decl_rtl, NULL);
        }
    }
}

static void
do_use_return_reg (rtx reg, void *arg ATTRIBUTE_UNUSED)
{
  emit_insn (gen_rtx_USE (VOIDmode, reg));
}

void
use_return_register (void)
{
  diddle_return_value (do_use_return_reg, NULL);
}

/* Possibly warn about unused parameters.  */
void
do_warn_unused_parameter (tree fn)
{
  tree decl;

  for (decl = DECL_ARGUMENTS (fn);
       decl; decl = TREE_CHAIN (decl))
    if (!TREE_USED (decl) && TREE_CODE (decl) == PARM_DECL
        && DECL_NAME (decl) && !DECL_ARTIFICIAL (decl))
      warning ("%Junused parameter '%D'", decl, decl);
}

static GTY(()) rtx initial_trampoline;

/* Generate RTL for the end of the current function.  */

void
expand_function_end (void)
{
  rtx clobber_after;

  /* If arg_pointer_save_area was referenced only from a nested
     function, we will not have initialized it yet.  Do that now.  */
  if (arg_pointer_save_area && ! cfun->arg_pointer_save_area_init)
    get_arg_pointer_save_area (cfun);

  /* If we are doing stack checking and this function makes calls,
     do a stack probe at the start of the function to ensure we have enough
     space for another stack frame.  */
  if (flag_stack_check && ! STACK_CHECK_BUILTIN)
    {
      rtx insn, seq;

      for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
        if (CALL_P (insn))
          {
            start_sequence ();
            probe_stack_range (STACK_CHECK_PROTECT,
                               GEN_INT (STACK_CHECK_MAX_FRAME_SIZE));
            seq = get_insns ();
            end_sequence ();
            emit_insn_before (seq, tail_recursion_reentry);
            break;
          }
    }

  /* Possibly warn about unused parameters.
     When frontend does unit-at-a-time, the warning is already
     issued at finalization time.  */
  if (warn_unused_parameter
      && !lang_hooks.callgraph.expand_function)
    do_warn_unused_parameter (current_function_decl);

  /* End any sequences that failed to be closed due to syntax errors.  */
  while (in_sequence_p ())
    end_sequence ();

  clear_pending_stack_adjust ();
  do_pending_stack_adjust ();

  /* @@@ This is a kludge.  We want to ensure that instructions that
     may trap are not moved into the epilogue by scheduling, because
     we don't always emit unwind information for the epilogue.
     However, not all machine descriptions define a blockage insn, so
     emit an ASM_INPUT to act as one.  */
  if (flag_non_call_exceptions)
    emit_insn (gen_rtx_ASM_INPUT (VOIDmode, ""));

  /* Mark the end of the function body.
     If control reaches this insn, the function can drop through
     without returning a value.  */
  emit_note (NOTE_INSN_FUNCTION_END);

  /* Must mark the last line number note in the function, so that the test
     coverage code can avoid counting the last line twice.  This just tells
     the code to ignore the immediately following line note, since there
     already exists a copy of this note somewhere above.  This line number
     note is still needed for debugging though, so we can't delete it.  */
  if (flag_test_coverage)
    emit_note (NOTE_INSN_REPEATED_LINE_NUMBER);

  /* Output a linenumber for the end of the function.
     SDB depends on this.  */
  force_next_line_note ();
  emit_line_note (input_location);

  /* Before the return label (if any), clobber the return
     registers so that they are not propagated live to the rest of
     the function.  This can only happen with functions that drop
     through; if there had been a return statement, there would
     have either been a return rtx, or a jump to the return label.

     We delay actual code generation after the current_function_value_rtx
     is computed.  */
  clobber_after = get_last_insn ();

  /* Output the label for the actual return from the function,
     if one is expected.  This happens either because a function epilogue
     is used instead of a return instruction, or because a return was done
     with a goto in order to run local cleanups, or because of pcc-style
     structure returning.  */
  if (return_label)
    emit_label (return_label);

  /* Let except.c know where it should emit the call to unregister
     the function context for sjlj exceptions.  */
  if (flag_exceptions && USING_SJLJ_EXCEPTIONS)
    sjlj_emit_function_exit_after (get_last_insn ());

  /* If we had calls to alloca, and this machine needs
     an accurate stack pointer to exit the function,
     insert some code to save and restore the stack pointer.  */
  if (! EXIT_IGNORE_STACK
      && current_function_calls_alloca)
    {
      rtx tem = 0;

      emit_stack_save (SAVE_FUNCTION, &tem, parm_birth_insn);
      emit_stack_restore (SAVE_FUNCTION, tem, NULL_RTX);
    }

  /* If scalar return value was computed in a pseudo-reg, or was a named
     return value that got dumped to the stack, copy that to the hard
     return register.  */
  if (DECL_RTL_SET_P (DECL_RESULT (current_function_decl)))
    {
      tree decl_result = DECL_RESULT (current_function_decl);
      rtx decl_rtl = DECL_RTL (decl_result);

      if (REG_P (decl_rtl)
          ? REGNO (decl_rtl) >= FIRST_PSEUDO_REGISTER
          : DECL_REGISTER (decl_result))
        {
          rtx real_decl_rtl = current_function_return_rtx;

          /* This should be set in assign_parms.  */
          if (! REG_FUNCTION_VALUE_P (real_decl_rtl))
            abort ();

          /* If this is a BLKmode structure being returned in registers,
             then use the mode computed in expand_return.  Note that if
             decl_rtl is memory, then its mode may have been changed,
             but that current_function_return_rtx has not.  */
          if (GET_MODE (real_decl_rtl) == BLKmode)
            PUT_MODE (real_decl_rtl, GET_MODE (decl_rtl));

          /* If a named return value dumped decl_return to memory, then
             we may need to re-do the PROMOTE_MODE signed/unsigned
             extension.  */
          if (GET_MODE (real_decl_rtl) != GET_MODE (decl_rtl))
            {
              int unsignedp = TYPE_UNSIGNED (TREE_TYPE (decl_result));

              if (targetm.calls.promote_function_return (TREE_TYPE (current_function_decl)))
                promote_mode (TREE_TYPE (decl_result), GET_MODE (decl_rtl),
                              &unsignedp, 1);

              convert_move (real_decl_rtl, decl_rtl, unsignedp);
            }
          else if (GET_CODE (real_decl_rtl) == PARALLEL)
            {
              /* If expand_function_start has created a PARALLEL for decl_rtl,
                 move the result to the real return registers.  Otherwise, do
                 a group load from decl_rtl for a named return.  */
              if (GET_CODE (decl_rtl) == PARALLEL)
                emit_group_move (real_decl_rtl, decl_rtl);
              else
                emit_group_load (real_decl_rtl, decl_rtl,
                                 TREE_TYPE (decl_result),
                                 int_size_in_bytes (TREE_TYPE (decl_result)));
            }
          else
            emit_move_insn (real_decl_rtl, decl_rtl);
        }
    }

  /* If returning a structure, arrange to return the address of the value
     in a place where debuggers expect to find it.

     If returning a structure PCC style,
     the caller also depends on this value.
     And current_function_returns_pcc_struct is not necessarily set.  */
  if (current_function_returns_struct
      || current_function_returns_pcc_struct)
    {
      rtx value_address
        = XEXP (DECL_RTL (DECL_RESULT (current_function_decl)), 0);
      tree type = TREE_TYPE (DECL_RESULT (current_function_decl));
#ifdef FUNCTION_OUTGOING_VALUE
      rtx outgoing
        = FUNCTION_OUTGOING_VALUE (build_pointer_type (type),
                                   current_function_decl);
#else
      rtx outgoing
        = FUNCTION_VALUE (build_pointer_type (type), current_function_decl);
#endif

      /* Mark this as a function return value so integrate will delete the
         assignment and USE below when inlining this function.  */
      REG_FUNCTION_VALUE_P (outgoing) = 1;

      /* The address may be ptr_mode and OUTGOING may be Pmode.  */
      value_address = convert_memory_address (GET_MODE (outgoing),
                                              value_address);

      emit_move_insn (outgoing, value_address);

      /* Show return register used to hold result (in this case the address
         of the result.  */
      current_function_return_rtx = outgoing;
    }

  /* If this is an implementation of throw, do what's necessary to
     communicate between __builtin_eh_return and the epilogue.  */
  expand_eh_return ();

  /* Emit the actual code to clobber return register.  */
  {
    rtx seq, after;

    start_sequence ();
    clobber_return_register ();
    seq = get_insns ();
    end_sequence ();

    after = emit_insn_after (seq, clobber_after);
  }

  /* Output the label for the naked return from the function, if one is
     expected.  This is currently used only by __builtin_return.  */
  if (naked_return_label)
    emit_label (naked_return_label);

  /* ??? This should no longer be necessary since stupid is no longer with
     us, but there are some parts of the compiler (eg reload_combine, and
     sh mach_dep_reorg) that still try and compute their own lifetime info
     instead of using the general framework.  */
  use_return_register ();
}

rtx
get_arg_pointer_save_area (struct function *f)
{
  rtx ret = f->x_arg_pointer_save_area;

  if (! ret)
    {
      ret = assign_stack_local_1 (Pmode, GET_MODE_SIZE (Pmode), 0, f);
      f->x_arg_pointer_save_area = ret;
    }

  if (f == cfun && ! f->arg_pointer_save_area_init)
    {
      rtx seq;

      /* Save the arg pointer at the beginning of the function.  The
         generated stack slot may not be a valid memory address, so we
         have to check it and fix it if necessary.  */
      start_sequence ();
      emit_move_insn (validize_mem (ret), virtual_incoming_args_rtx);
      seq = get_insns ();
      end_sequence ();

      push_topmost_sequence ();
      emit_insn_after (seq, get_insns ());
      pop_topmost_sequence ();
    }

  return ret;
}
\f
/* Extend a vector that records the INSN_UIDs of INSNS
   (a list of one or more insns).  */

static void
record_insns (rtx insns, varray_type *vecp)
{
  int i, len;
  rtx tmp;

  tmp = insns;
  len = 0;
  while (tmp != NULL_RTX)
    {
      len++;
      tmp = NEXT_INSN (tmp);
    }

  i = VARRAY_SIZE (*vecp);
  VARRAY_GROW (*vecp, i + len);
  tmp = insns;
  while (tmp != NULL_RTX)
    {
      VARRAY_INT (*vecp, i) = INSN_UID (tmp);
      i++;
      tmp = NEXT_INSN (tmp);
    }
}

/* Set the locator of the insn chain starting at INSN to LOC.  */
static void
set_insn_locators (rtx insn, int loc)
{
  while (insn != NULL_RTX)
    {
      if (INSN_P (insn))
        INSN_LOCATOR (insn) = loc;
      insn = NEXT_INSN (insn);
    }
}

/* Determine how many INSN_UIDs in VEC are part of INSN.  Because we can
   be running after reorg, SEQUENCE rtl is possible.  */

static int
contains (rtx insn, varray_type vec)
{
  int i, j;

  if (NONJUMP_INSN_P (insn)
      && GET_CODE (PATTERN (insn)) == SEQUENCE)
    {
      int count = 0;
      for (i = XVECLEN (PATTERN (insn), 0) - 1; i >= 0; i--)
        for (j = VARRAY_SIZE (vec) - 1; j >= 0; --j)
          if (INSN_UID (XVECEXP (PATTERN (insn), 0, i)) == VARRAY_INT (vec, j))
            count++;
      return count;
    }
  else
    {
      for (j = VARRAY_SIZE (vec) - 1; j >= 0; --j)
        if (INSN_UID (insn) == VARRAY_INT (vec, j))
          return 1;
    }
  return 0;
}

int
prologue_epilogue_contains (rtx insn)
{
  if (contains (insn, prologue))
    return 1;
  if (contains (insn, epilogue))
    return 1;
  return 0;
}

int
sibcall_epilogue_contains (rtx insn)
{
  if (sibcall_epilogue)
    return contains (insn, sibcall_epilogue);
  return 0;
}

#ifdef HAVE_return
/* Insert gen_return at the end of block BB.  This also means updating
   block_for_insn appropriately.  */

static void
emit_return_into_block (basic_block bb, rtx line_note)
{
  emit_jump_insn_after (gen_return (), BB_END (bb));
  if (line_note)
    emit_note_copy_after (line_note, PREV_INSN (BB_END (bb)));
}
#endif /* HAVE_return */

#if defined(HAVE_epilogue) && defined(INCOMING_RETURN_ADDR_RTX)

/* These functions convert the epilogue into a variant that does not modify the
   stack pointer.  This is used in cases where a function returns an object
   whose size is not known until it is computed.  The called function leaves the
   object on the stack, leaves the stack depressed, and returns a pointer to
   the object.

   What we need to do is track all modifications and references to the stack
   pointer, deleting the modifications and changing the references to point to
   the location the stack pointer would have pointed to had the modifications
   taken place.

   These functions need to be portable so we need to make as few assumptions
   about the epilogue as we can.  However, the epilogue basically contains
   three things: instructions to reset the stack pointer, instructions to
   reload registers, possibly including the frame pointer, and an
   instruction to return to the caller.

   If we can't be sure of what a relevant epilogue insn is doing, we abort.
   We also make no attempt to validate the insns we make since if they are
   invalid, we probably can't do anything valid.  The intent is that these
   routines get "smarter" as more and more machines start to use them and
   they try operating on different epilogues.

   We use the following structure to track what the part of the epilogue that
   we've already processed has done.  We keep two copies of the SP equivalence,
   one for use during the insn we are processing and one for use in the next
   insn.  The difference is because one part of a PARALLEL may adjust SP
   and the other may use it.  */

struct epi_info
{
  rtx sp_equiv_reg;             /* REG that SP is set from, perhaps SP.  */
  HOST_WIDE_INT sp_offset;      /* Offset from SP_EQUIV_REG of present SP.  */
  rtx new_sp_equiv_reg;         /* REG to be used at end of insn.  */
  HOST_WIDE_INT new_sp_offset;  /* Offset to be used at end of insn.  */
  rtx equiv_reg_src;            /* If nonzero, the value that SP_EQUIV_REG
                                   should be set to once we no longer need
                                   its value.  */
  rtx const_equiv[FIRST_PSEUDO_REGISTER]; /* Any known constant equivalences
                                             for registers.  */
};

static void handle_epilogue_set (rtx, struct epi_info *);
static void update_epilogue_consts (rtx, rtx, void *);
static void emit_equiv_load (struct epi_info *);

/* Modify INSN, a list of one or more insns that is part of the epilogue, to
   no modifications to the stack pointer.  Return the new list of insns.  */

static rtx
keep_stack_depressed (rtx insns)
{
  int j;
  struct epi_info info;
  rtx insn, next;

  /* If the epilogue is just a single instruction, it must be OK as is.  */
  if (NEXT_INSN (insns) == NULL_RTX)
    return insns;

  /* Otherwise, start a sequence, initialize the information we have, and
     process all the insns we were given.  */
  start_sequence ();

  info.sp_equiv_reg = stack_pointer_rtx;
  info.sp_offset = 0;
  info.equiv_reg_src = 0;

  for (j = 0; j < FIRST_PSEUDO_REGISTER; j++)
    info.const_equiv[j] = 0;

  insn = insns;
  next = NULL_RTX;
  while (insn != NULL_RTX)
    {
      next = NEXT_INSN (insn);

      if (!INSN_P (insn))
        {
          add_insn (insn);
          insn = next;
          continue;
        }

      /* If this insn references the register that SP is equivalent to and
         we have a pending load to that register, we must force out the load
         first and then indicate we no longer know what SP's equivalent is.  */
      if (info.equiv_reg_src != 0
          && reg_referenced_p (info.sp_equiv_reg, PATTERN (insn)))
        {
          emit_equiv_load (&info);
          info.sp_equiv_reg = 0;
        }

      info.new_sp_equiv_reg = info.sp_equiv_reg;
      info.new_sp_offset = info.sp_offset;

      /* If this is a (RETURN) and the return address is on the stack,
         update the address and change to an indirect jump.  */
      if (GET_CODE (PATTERN (insn)) == RETURN
          || (GET_CODE (PATTERN (insn)) == PARALLEL
              && GET_CODE (XVECEXP (PATTERN (insn), 0, 0)) == RETURN))
        {
          rtx retaddr = INCOMING_RETURN_ADDR_RTX;
          rtx base = 0;
          HOST_WIDE_INT offset = 0;
          rtx jump_insn, jump_set;

          /* If the return address is in a register, we can emit the insn
             unchanged.  Otherwise, it must be a MEM and we see what the
             base register and offset are.  In any case, we have to emit any
             pending load to the equivalent reg of SP, if any.  */
          if (REG_P (retaddr))
            {
              emit_equiv_load (&info);
              add_insn (insn);
              insn = next;
              continue;
            }
          else if (MEM_P (retaddr)
                   && REG_P (XEXP (retaddr, 0)))
            base = gen_rtx_REG (Pmode, REGNO (XEXP (retaddr, 0))), offset = 0;
          else if (MEM_P (retaddr)
                   && GET_CODE (XEXP (retaddr, 0)) == PLUS
                   && REG_P (XEXP (XEXP (retaddr, 0), 0))
                   && GET_CODE (XEXP (XEXP (retaddr, 0), 1)) == CONST_INT)
            {
              base = gen_rtx_REG (Pmode, REGNO (XEXP (XEXP (retaddr, 0), 0)));
              offset = INTVAL (XEXP (XEXP (retaddr, 0), 1));
            }
          else
            abort ();

          /* If the base of the location containing the return pointer
             is SP, we must update it with the replacement address.  Otherwise,
             just build the necessary MEM.  */
          retaddr = plus_constant (base, offset);
          if (base == stack_pointer_rtx)
            retaddr = simplify_replace_rtx (retaddr, stack_pointer_rtx,
                                            plus_constant (info.sp_equiv_reg,
                                                           info.sp_offset));

          retaddr = gen_rtx_MEM (Pmode, retaddr);

          /* If there is a pending load to the equivalent register for SP
             and we reference that register, we must load our address into
             a scratch register and then do that load.  */
          if (info.equiv_reg_src
              && reg_overlap_mentioned_p (info.equiv_reg_src, retaddr))
            {
              unsigned int regno;
              rtx reg;

              for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
                if (HARD_REGNO_MODE_OK (regno, Pmode)
                    && !fixed_regs[regno]
                    && TEST_HARD_REG_BIT (regs_invalidated_by_call, regno)
                    && !REGNO_REG_SET_P (EXIT_BLOCK_PTR->global_live_at_start,
                                         regno)
                    && !refers_to_regno_p (regno,
                                           regno + hard_regno_nregs[regno]
                                                                   [Pmode],
                                           info.equiv_reg_src, NULL)
                    && info.const_equiv[regno] == 0)
                  break;

              if (regno == FIRST_PSEUDO_REGISTER)
                abort ();

              reg = gen_rtx_REG (Pmode, regno);
              emit_move_insn (reg, retaddr);
              retaddr = reg;
            }

          emit_equiv_load (&info);
          jump_insn = emit_jump_insn (gen_indirect_jump (retaddr));

          /* Show the SET in the above insn is a RETURN.  */
          jump_set = single_set (jump_insn);
          if (jump_set == 0)
            abort ();
          else
            SET_IS_RETURN_P (jump_set) = 1;
        }

      /* If SP is not mentioned in the pattern and its equivalent register, if
         any, is not modified, just emit it.  Otherwise, if neither is set,
         replace the reference to SP and emit the insn.  If none of those are
         true, handle each SET individually.  */
      else if (!reg_mentioned_p (stack_pointer_rtx, PATTERN (insn))
               && (info.sp_equiv_reg == stack_pointer_rtx
                   || !reg_set_p (info.sp_equiv_reg, insn)))
        add_insn (insn);
      else if (! reg_set_p (stack_pointer_rtx, insn)
               && (info.sp_equiv_reg == stack_pointer_rtx
                   || !reg_set_p (info.sp_equiv_reg, insn)))
        {
          if (! validate_replace_rtx (stack_pointer_rtx,
                                      plus_constant (info.sp_equiv_reg,
                                                     info.sp_offset),
                                      insn))
            abort ();

          add_insn (insn);
        }
      else if (GET_CODE (PATTERN (insn)) == SET)
        handle_epilogue_set (PATTERN (insn), &info);
      else if (GET_CODE (PATTERN (insn)) == PARALLEL)
        {
          for (j = 0; j < XVECLEN (PATTERN (insn), 0); j++)
            if (GET_CODE (XVECEXP (PATTERN (insn), 0, j)) == SET)
              handle_epilogue_set (XVECEXP (PATTERN (insn), 0, j), &info);
        }
      else
        add_insn (insn);

      info.sp_equiv_reg = info.new_sp_equiv_reg;
      info.sp_offset = info.new_sp_offset;

      /* Now update any constants this insn sets.  */
      note_stores (PATTERN (insn), update_epilogue_consts, &info);
      insn = next;
    }

  insns = get_insns ();
  end_sequence ();
  return insns;
}

/* SET is a SET from an insn in the epilogue.  P is a pointer to the epi_info
   structure that contains information about what we've seen so far.  We
   process this SET by either updating that data or by emitting one or
   more insns.  */

static void
handle_epilogue_set (rtx set, struct epi_info *p)
{
  /* First handle the case where we are setting SP.  Record what it is being
     set from.  If unknown, abort.  */
  if (reg_set_p (stack_pointer_rtx, set))
    {
      if (SET_DEST (set) != stack_pointer_rtx)
        abort ();

      if (GET_CODE (SET_SRC (set)) == PLUS)
        {
          p->new_sp_equiv_reg = XEXP (SET_SRC (set), 0);
          if (GET_CODE (XEXP (SET_SRC (set), 1)) == CONST_INT)
            p->new_sp_offset = INTVAL (XEXP (SET_SRC (set), 1));
          else if (REG_P (XEXP (SET_SRC (set), 1))
                   && REGNO (XEXP (SET_SRC (set), 1)) < FIRST_PSEUDO_REGISTER
                   && p->const_equiv[REGNO (XEXP (SET_SRC (set), 1))] != 0)
            p->new_sp_offset
              = INTVAL (p->const_equiv[REGNO (XEXP (SET_SRC (set), 1))]);
          else
            abort ();
        }
      else
        p->new_sp_equiv_reg = SET_SRC (set), p->new_sp_offset = 0;

      /* If we are adjusting SP, we adjust from the old data.  */
      if (p->new_sp_equiv_reg == stack_pointer_rtx)
        {
          p->new_sp_equiv_reg = p->sp_equiv_reg;
          p->new_sp_offset += p->sp_offset;
        }

      if (p->new_sp_equiv_reg == 0 || !REG_P (p->new_sp_equiv_reg))
        abort ();

      return;
    }

  /* Next handle the case where we are setting SP's equivalent register.
     If we already have a value to set it to, abort.  We could update, but
     there seems little point in handling that case.  Note that we have
     to allow for the case where we are setting the register set in
     the previous part of a PARALLEL inside a single insn.  But use the
     old offset for any updates within this insn.  We must allow for the case
     where the register is being set in a different (usually wider) mode than
     Pmode).  */
  else if (p->new_sp_equiv_reg != 0 && reg_set_p (p->new_sp_equiv_reg, set))
    {
      if (p->equiv_reg_src != 0
          || !REG_P (p->new_sp_equiv_reg)
          || !REG_P (SET_DEST (set))
          || GET_MODE_BITSIZE (GET_MODE (SET_DEST (set))) > BITS_PER_WORD
          || REGNO (p->new_sp_equiv_reg) != REGNO (SET_DEST (set)))
        abort ();
      else
        p->equiv_reg_src
          = simplify_replace_rtx (SET_SRC (set), stack_pointer_rtx,
                                  plus_constant (p->sp_equiv_reg,
                                                 p->sp_offset));
    }

  /* Otherwise, replace any references to SP in the insn to its new value
     and emit the insn.  */
  else
    {
      SET_SRC (set) = simplify_replace_rtx (SET_SRC (set), stack_pointer_rtx,
                                            plus_constant (p->sp_equiv_reg,
                                                           p->sp_offset));
      SET_DEST (set) = simplify_replace_rtx (SET_DEST (set), stack_pointer_rtx,
                                             plus_constant (p->sp_equiv_reg,
                                                            p->sp_offset));
      emit_insn (set);
    }
}

/* Update the tracking information for registers set to constants.  */

static void
update_epilogue_consts (rtx dest, rtx x, void *data)
{
  struct epi_info *p = (struct epi_info *) data;
  rtx new;

  if (!REG_P (dest) || REGNO (dest) >= FIRST_PSEUDO_REGISTER)
    return;

  /* If we are either clobbering a register or doing a partial set,
     show we don't know the value.  */
  else if (GET_CODE (x) == CLOBBER || ! rtx_equal_p (dest, SET_DEST (x)))
    p->const_equiv[REGNO (dest)] = 0;

  /* If we are setting it to a constant, record that constant.  */
  else if (GET_CODE (SET_SRC (x)) == CONST_INT)
    p->const_equiv[REGNO (dest)] = SET_SRC (x);

  /* If this is a binary operation between a register we have been tracking
     and a constant, see if we can compute a new constant value.  */
  else if (ARITHMETIC_P (SET_SRC (x))
           && REG_P (XEXP (SET_SRC (x), 0))
           && REGNO (XEXP (SET_SRC (x), 0)) < FIRST_PSEUDO_REGISTER
           && p->const_equiv[REGNO (XEXP (SET_SRC (x), 0))] != 0
           && GET_CODE (XEXP (SET_SRC (x), 1)) == CONST_INT
           && 0 != (new = simplify_binary_operation
                    (GET_CODE (SET_SRC (x)), GET_MODE (dest),
                     p->const_equiv[REGNO (XEXP (SET_SRC (x), 0))],
                     XEXP (SET_SRC (x), 1)))
           && GET_CODE (new) == CONST_INT)
    p->const_equiv[REGNO (dest)] = new;

  /* Otherwise, we can't do anything with this value.  */
  else
    p->const_equiv[REGNO (dest)] = 0;
}

/* Emit an insn to do the load shown in p->equiv_reg_src, if needed.  */

static void
emit_equiv_load (struct epi_info *p)
{
  if (p->equiv_reg_src != 0)
    {
      rtx dest = p->sp_equiv_reg;

      if (GET_MODE (p->equiv_reg_src) != GET_MODE (dest))
        dest = gen_rtx_REG (GET_MODE (p->equiv_reg_src),
                            REGNO (p->sp_equiv_reg));

      emit_move_insn (dest, p->equiv_reg_src);
      p->equiv_reg_src = 0;
    }
}
#endif

/* Generate the prologue and epilogue RTL if the machine supports it.  Thread
   this into place with notes indicating where the prologue ends and where
   the epilogue begins.  Update the basic block information when possible.  */

void
thread_prologue_and_epilogue_insns (rtx f ATTRIBUTE_UNUSED)
{
  int inserted = 0;
  edge e;
#if defined (HAVE_sibcall_epilogue) || defined (HAVE_epilogue) || defined (HAVE_return) || defined (HAVE_prologue)
  rtx seq;
#endif
#ifdef HAVE_prologue
  rtx prologue_end = NULL_RTX;
#endif
#if defined (HAVE_epilogue) || defined(HAVE_return)
  rtx epilogue_end = NULL_RTX;
#endif

#ifdef HAVE_prologue
  if (HAVE_prologue)
    {
      start_sequence ();
      seq = gen_prologue ();
      emit_insn (seq);

      /* Retain a map of the prologue insns.  */
      record_insns (seq, &prologue);
      prologue_end = emit_note (NOTE_INSN_PROLOGUE_END);

      seq = get_insns ();
      end_sequence ();
      set_insn_locators (seq, prologue_locator);

      /* Can't deal with multiple successors of the entry block
         at the moment.  Function should always have at least one
         entry point.  */
      if (!ENTRY_BLOCK_PTR->succ || ENTRY_BLOCK_PTR->succ->succ_next)
        abort ();

      insert_insn_on_edge (seq, ENTRY_BLOCK_PTR->succ);
      inserted = 1;
    }
#endif

  /* If the exit block has no non-fake predecessors, we don't need
     an epilogue.  */
  for (e = EXIT_BLOCK_PTR->pred; e; e = e->pred_next)
    if ((e->flags & EDGE_FAKE) == 0)
      break;
  if (e == NULL)
    goto epilogue_done;

#ifdef HAVE_return
  if (optimize && HAVE_return)
    {
      /* If we're allowed to generate a simple return instruction,
         then by definition we don't need a full epilogue.  Examine
         the block that falls through to EXIT.   If it does not
         contain any code, examine its predecessors and try to
         emit (conditional) return instructions.  */

      basic_block last;
      edge e_next;
      rtx label;

      for (e = EXIT_BLOCK_PTR->pred; e; e = e->pred_next)
        if (e->flags & EDGE_FALLTHRU)
          break;
      if (e == NULL)
        goto epilogue_done;
      last = e->src;

      /* Verify that there are no active instructions in the last block.  */
      label = BB_END (last);
      while (label && !LABEL_P (label))
        {
          if (active_insn_p (label))
            break;
          label = PREV_INSN (label);
        }

      if (BB_HEAD (last) == label && LABEL_P (label))
        {
          rtx epilogue_line_note = NULL_RTX;

          /* Locate the line number associated with the closing brace,
             if we can find one.  */
          for (seq = get_last_insn ();
               seq && ! active_insn_p (seq);
               seq = PREV_INSN (seq))
            if (NOTE_P (seq) && NOTE_LINE_NUMBER (seq) > 0)
              {
                epilogue_line_note = seq;
                break;
              }

          for (e = last->pred; e; e = e_next)
            {
              basic_block bb = e->src;
              rtx jump;

              e_next = e->pred_next;
              if (bb == ENTRY_BLOCK_PTR)
                continue;

              jump = BB_END (bb);
              if (!JUMP_P (jump) || JUMP_LABEL (jump) != label)
                continue;

              /* If we have an unconditional jump, we can replace that
                 with a simple return instruction.  */
              if (simplejump_p (jump))
                {
                  emit_return_into_block (bb, epilogue_line_note);
                  delete_insn (jump);
                }

              /* If we have a conditional jump, we can try to replace
                 that with a conditional return instruction.  */
              else if (condjump_p (jump))
                {
                  if (! redirect_jump (jump, 0, 0))
                    continue;

                  /* If this block has only one successor, it both jumps
                     and falls through to the fallthru block, so we can't
                     delete the edge.  */
                  if (bb->succ->succ_next == NULL)
                    continue;
                }
              else
                continue;

              /* Fix up the CFG for the successful change we just made.  */
              redirect_edge_succ (e, EXIT_BLOCK_PTR);
            }

          /* Emit a return insn for the exit fallthru block.  Whether
             this is still reachable will be determined later.  */

          emit_barrier_after (BB_END (last));
          emit_return_into_block (last, epilogue_line_note);
          epilogue_end = BB_END (last);
          last->succ->flags &= ~EDGE_FALLTHRU;
          goto epilogue_done;
        }
    }
#endif
  /* Find the edge that falls through to EXIT.  Other edges may exist
     due to RETURN instructions, but those don't need epilogues.
     There really shouldn't be a mixture -- either all should have
     been converted or none, however...  */

  for (e = EXIT_BLOCK_PTR->pred; e; e = e->pred_next)
    if (e->flags & EDGE_FALLTHRU)
      break;
  if (e == NULL)
    goto epilogue_done;

#ifdef HAVE_epilogue
  if (HAVE_epilogue)
    {
      start_sequence ();
      epilogue_end = emit_note (NOTE_INSN_EPILOGUE_BEG);

      seq = gen_epilogue ();

#ifdef INCOMING_RETURN_ADDR_RTX
      /* If this function returns with the stack depressed and we can support
         it, massage the epilogue to actually do that.  */
      if (TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE
          && TYPE_RETURNS_STACK_DEPRESSED (TREE_TYPE (current_function_decl)))
        seq = keep_stack_depressed (seq);
#endif

      emit_jump_insn (seq);

      /* Retain a map of the epilogue insns.  */
      record_insns (seq, &epilogue);
      set_insn_locators (seq, epilogue_locator);

      seq = get_insns ();
      end_sequence ();

      insert_insn_on_edge (seq, e);
      inserted = 1;
    }
  else
#endif
    {
      basic_block cur_bb;

      if (! next_active_insn (BB_END (e->src)))
        goto epilogue_done;
      /* We have a fall-through edge to the exit block, the source is not
         at the end of the function, and there will be an assembler epilogue
         at the end of the function.
         We can't use force_nonfallthru here, because that would try to
         use return.  Inserting a jump 'by hand' is extremely messy, so
         we take advantage of cfg_layout_finalize using
        fixup_fallthru_exit_predecessor.  */
      cfg_layout_initialize (0);
      FOR_EACH_BB (cur_bb)
        if (cur_bb->index >= 0 && cur_bb->next_bb->index >= 0)
          cur_bb->rbi->next = cur_bb->next_bb;
      cfg_layout_finalize ();
    }
epilogue_done:

  if (inserted)
    commit_edge_insertions ();

#ifdef HAVE_sibcall_epilogue
  /* Emit sibling epilogues before any sibling call sites.  */
  for (e = EXIT_BLOCK_PTR->pred; e; e = e->pred_next)
    {
      basic_block bb = e->src;
      rtx insn = BB_END (bb);
      rtx i;
      rtx newinsn;

      if (!CALL_P (insn)
          || ! SIBLING_CALL_P (insn))
        continue;

      start_sequence ();
      emit_insn (gen_sibcall_epilogue ());
      seq = get_insns ();
      end_sequence ();

      /* Retain a map of the epilogue insns.  Used in life analysis to
         avoid getting rid of sibcall epilogue insns.  Do this before we
         actually emit the sequence.  */
      record_insns (seq, &sibcall_epilogue);
      set_insn_locators (seq, epilogue_locator);

      i = PREV_INSN (insn);
      newinsn = emit_insn_before (seq, insn);
    }
#endif

#ifdef HAVE_prologue
  /* This is probably all useless now that we use locators.  */
  if (prologue_end)
    {
      rtx insn, prev;

      /* GDB handles `break f' by setting a breakpoint on the first
         line note after the prologue.  Which means (1) that if
         there are line number notes before where we inserted the
         prologue we should move them, and (2) we should generate a
         note before the end of the first basic block, if there isn't
         one already there.

         ??? This behavior is completely broken when dealing with
         multiple entry functions.  We simply place the note always
         into first basic block and let alternate entry points
         to be missed.
       */

      for (insn = prologue_end; insn; insn = prev)
        {
          prev = PREV_INSN (insn);
          if (NOTE_P (insn) && NOTE_LINE_NUMBER (insn) > 0)
            {
              /* Note that we cannot reorder the first insn in the
                 chain, since rest_of_compilation relies on that
                 remaining constant.  */
              if (prev == NULL)
                break;
              reorder_insns (insn, insn, prologue_end);
            }
        }

      /* Find the last line number note in the first block.  */
      for (insn = BB_END (ENTRY_BLOCK_PTR->next_bb);
           insn != prologue_end && insn;
           insn = PREV_INSN (insn))
        if (NOTE_P (insn) && NOTE_LINE_NUMBER (insn) > 0)
          break;

      /* If we didn't find one, make a copy of the first line number
         we run across.  */
      if (! insn)
        {
          for (insn = next_active_insn (prologue_end);
               insn;
               insn = PREV_INSN (insn))
            if (NOTE_P (insn) && NOTE_LINE_NUMBER (insn) > 0)
              {
                emit_note_copy_after (insn, prologue_end);
                break;
              }
        }
    }
#endif
#ifdef HAVE_epilogue
  if (epilogue_end)
    {
      rtx insn, next;

      /* Similarly, move any line notes that appear after the epilogue.
         There is no need, however, to be quite so anal about the existence
         of such a note.  Also move the NOTE_INSN_FUNCTION_END and (possibly)
         NOTE_INSN_FUNCTION_BEG notes, as those can be relevant for debug
         info generation.  */
      for (insn = epilogue_end; insn; insn = next)
        {
          next = NEXT_INSN (insn);
          if (NOTE_P (insn) 
              && (NOTE_LINE_NUMBER (insn) > 0
                  || NOTE_LINE_NUMBER (insn) == NOTE_INSN_FUNCTION_BEG
                  || NOTE_LINE_NUMBER (insn) == NOTE_INSN_FUNCTION_END))
            reorder_insns (insn, insn, PREV_INSN (epilogue_end));
        }
    }
#endif
}

/* Reposition the prologue-end and epilogue-begin notes after instruction
   scheduling and delayed branch scheduling.  */

void
reposition_prologue_and_epilogue_notes (rtx f ATTRIBUTE_UNUSED)
{
#if defined (HAVE_prologue) || defined (HAVE_epilogue)
  rtx insn, last, note;
  int len;

  if ((len = VARRAY_SIZE (prologue)) > 0)
    {
      last = 0, note = 0;

      /* Scan from the beginning until we reach the last prologue insn.
         We apparently can't depend on basic_block_{head,end} after
         reorg has run.  */
      for (insn = f; insn; insn = NEXT_INSN (insn))
        {
          if (NOTE_P (insn))
            {
              if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_PROLOGUE_END)
                note = insn;
            }
          else if (contains (insn, prologue))
            {
              last = insn;
              if (--len == 0)
                break;
            }
        }

      if (last)
        {
          /* Find the prologue-end note if we haven't already, and
             move it to just after the last prologue insn.  */
          if (note == 0)
            {
              for (note = last; (note = NEXT_INSN (note));)
                if (NOTE_P (note)
                    && NOTE_LINE_NUMBER (note) == NOTE_INSN_PROLOGUE_END)
                  break;
            }

          /* Avoid placing note between CODE_LABEL and BASIC_BLOCK note.  */
          if (LABEL_P (last))
            last = NEXT_INSN (last);
          reorder_insns (note, note, last);
        }
    }

  if ((len = VARRAY_SIZE (epilogue)) > 0)
    {
      last = 0, note = 0;

      /* Scan from the end until we reach the first epilogue insn.
         We apparently can't depend on basic_block_{head,end} after
         reorg has run.  */
      for (insn = get_last_insn (); insn; insn = PREV_INSN (insn))
        {
          if (NOTE_P (insn))
            {
              if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EPILOGUE_BEG)
                note = insn;
            }
          else if (contains (insn, epilogue))
            {
              last = insn;
              if (--len == 0)
                break;
            }
        }

      if (last)
        {
          /* Find the epilogue-begin note if we haven't already, and
             move it to just before the first epilogue insn.  */
          if (note == 0)
            {
              for (note = insn; (note = PREV_INSN (note));)
                if (NOTE_P (note)
                    && NOTE_LINE_NUMBER (note) == NOTE_INSN_EPILOGUE_BEG)
                  break;
            }

          if (PREV_INSN (last) != note)
            reorder_insns (note, note, PREV_INSN (last));
        }
    }
#endif /* HAVE_prologue or HAVE_epilogue */
}

/* Called once, at initialization, to initialize function.c.  */

void
init_function_once (void)
{
  VARRAY_INT_INIT (prologue, 0, "prologue");
  VARRAY_INT_INIT (epilogue, 0, "epilogue");
  VARRAY_INT_INIT (sibcall_epilogue, 0, "sibcall_epilogue");
}

/* Resets insn_block_boundaries array.  */

void
reset_block_changes (void)
{
  VARRAY_TREE_INIT (cfun->ib_boundaries_block, 100, "ib_boundaries_block");
  VARRAY_PUSH_TREE (cfun->ib_boundaries_block, NULL_TREE);
}

/* Record the boundary for BLOCK.  */
void
record_block_change (tree block)
{
  int i, n;
  tree last_block;

  if (!block)
    return;

  last_block = VARRAY_TOP_TREE (cfun->ib_boundaries_block);
  VARRAY_POP (cfun->ib_boundaries_block);
  n = get_max_uid ();
  for (i = VARRAY_ACTIVE_SIZE (cfun->ib_boundaries_block); i < n; i++)
    VARRAY_PUSH_TREE (cfun->ib_boundaries_block, last_block);

  VARRAY_PUSH_TREE (cfun->ib_boundaries_block, block);
}

/* Finishes record of boundaries.  */
void finalize_block_changes (void)
{
  record_block_change (DECL_INITIAL (current_function_decl));
}

/* For INSN return the BLOCK it belongs to.  */ 
void
check_block_change (rtx insn, tree *block)
{
  unsigned uid = INSN_UID (insn);

  if (uid >= VARRAY_ACTIVE_SIZE (cfun->ib_boundaries_block))
    return;

  *block = VARRAY_TREE (cfun->ib_boundaries_block, uid);
}

/* Releases the ib_boundaries_block records.  */
void
free_block_changes (void)
{
  cfun->ib_boundaries_block = NULL;
}

/* Returns the name of the current function.  */
const char *
current_function_name (void)
{
  return lang_hooks.decl_printable_name (cfun->decl, 2);
}

#include "gt-function.h"