Merge branch 'master' of ssh://crater.dragonflybsd.org/repository/git/dragonfly

[dragonfly.git] / contrib / gcc-3.4 / gcc / stmt.c

/* Expands front end tree to back end RTL for GCC
   Copyright (C) 1987, 1988, 1989, 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
   above the level of expressions, using subroutines in exp*.c and emit-rtl.c.
   It also creates the rtl expressions for parameters and auto variables
   and has full responsibility for allocating stack slots.

   The functions whose names start with `expand_' are called by the
   parser to generate RTL instructions for various kinds of constructs.

   Some control and binding constructs require calling several such
   functions at different times.  For example, a simple if-then
   is expanded by calling `expand_start_cond' (with the condition-expression
   as argument) before parsing the then-clause and calling `expand_end_cond'
   after parsing the then-clause.  */

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

#include "rtl.h"
#include "tree.h"
#include "tm_p.h"
#include "flags.h"
#include "except.h"
#include "function.h"
#include "insn-config.h"
#include "expr.h"
#include "libfuncs.h"
#include "hard-reg-set.h"
#include "loop.h"
#include "recog.h"
#include "machmode.h"
#include "toplev.h"
#include "output.h"
#include "ggc.h"
#include "langhooks.h"
#include "predict.h"
#include "optabs.h"
#include "target.h"

/* Assume that case vectors are not pc-relative.  */
#ifndef CASE_VECTOR_PC_RELATIVE
#define CASE_VECTOR_PC_RELATIVE 0
#endif
\f
/* Functions and data structures for expanding case statements.  */

/* Case label structure, used to hold info on labels within case
   statements.  We handle "range" labels; for a single-value label
   as in C, the high and low limits are the same.

   An AVL tree of case nodes is initially created, and later transformed
   to a list linked via the RIGHT fields in the nodes.  Nodes with
   higher case values are later in the list.

   Switch statements can be output in one of two forms.  A branch table
   is used if there are more than a few labels and the labels are dense
   within the range between the smallest and largest case value.  If a
   branch table is used, no further manipulations are done with the case
   node chain.

   The alternative to the use of a branch table is to generate a series
   of compare and jump insns.  When that is done, we use the LEFT, RIGHT,
   and PARENT fields to hold a binary tree.  Initially the tree is
   totally unbalanced, with everything on the right.  We balance the tree
   with nodes on the left having lower case values than the parent
   and nodes on the right having higher values.  We then output the tree
   in order.  */

struct case_node GTY(())
{
  struct case_node      *left;  /* Left son in binary tree */
  struct case_node      *right; /* Right son in binary tree; also node chain */
  struct case_node      *parent; /* Parent of node in binary tree */
  tree                  low;    /* Lowest index value for this label */
  tree                  high;   /* Highest index value for this label */
  tree                  code_label; /* Label to jump to when node matches */
  int                   balance;
};

typedef struct case_node case_node;
typedef struct case_node *case_node_ptr;

/* These are used by estimate_case_costs and balance_case_nodes.  */

/* This must be a signed type, and non-ANSI compilers lack signed char.  */
static short cost_table_[129];
static int use_cost_table;
static int cost_table_initialized;

/* Special care is needed because we allow -1, but TREE_INT_CST_LOW
   is unsigned.  */
#define COST_TABLE(I)  cost_table_[(unsigned HOST_WIDE_INT) ((I) + 1)]
\f
/* Stack of control and binding constructs we are currently inside.

   These constructs begin when you call `expand_start_WHATEVER'
   and end when you call `expand_end_WHATEVER'.  This stack records
   info about how the construct began that tells the end-function
   what to do.  It also may provide information about the construct
   to alter the behavior of other constructs within the body.
   For example, they may affect the behavior of C `break' and `continue'.

   Each construct gets one `struct nesting' object.
   All of these objects are chained through the `all' field.
   `nesting_stack' points to the first object (innermost construct).
   The position of an entry on `nesting_stack' is in its `depth' field.

   Each type of construct has its own individual stack.
   For example, loops have `loop_stack'.  Each object points to the
   next object of the same type through the `next' field.

   Some constructs are visible to `break' exit-statements and others
   are not.  Which constructs are visible depends on the language.
   Therefore, the data structure allows each construct to be visible
   or not, according to the args given when the construct is started.
   The construct is visible if the `exit_label' field is non-null.
   In that case, the value should be a CODE_LABEL rtx.  */

struct nesting GTY(())
{
  struct nesting *all;
  struct nesting *next;
  int depth;
  rtx exit_label;
  enum nesting_desc {
    COND_NESTING,
    LOOP_NESTING,
    BLOCK_NESTING,
    CASE_NESTING
  } desc;
  union nesting_u
    {
      /* For conds (if-then and if-then-else statements).  */
      struct nesting_cond
        {
          /* Label for the end of the if construct.
             There is none if EXITFLAG was not set
             and no `else' has been seen yet.  */
          rtx endif_label;
          /* Label for the end of this alternative.
             This may be the end of the if or the next else/elseif.  */
          rtx next_label;
        } GTY ((tag ("COND_NESTING"))) cond;
      /* For loops.  */
      struct nesting_loop
        {
          /* Label at the top of the loop; place to loop back to.  */
          rtx start_label;
          /* Label at the end of the whole construct.  */
          rtx end_label;
          /* Label for `continue' statement to jump to;
             this is in front of the stepper of the loop.  */
          rtx continue_label;
        } GTY ((tag ("LOOP_NESTING"))) loop;
      /* For variable binding contours.  */
      struct nesting_block
        {
          /* Sequence number of this binding contour within the function,
             in order of entry.  */
          int block_start_count;
          /* Nonzero => value to restore stack to on exit.  */
          rtx stack_level;
          /* The NOTE that starts this contour.
             Used by expand_goto to check whether the destination
             is within each contour or not.  */
          rtx first_insn;
          /* Innermost containing binding contour that has a stack level.  */
          struct nesting *innermost_stack_block;
          /* List of cleanups to be run on exit from this contour.
             This is a list of expressions to be evaluated.
             The TREE_PURPOSE of each link is the ..._DECL node
             which the cleanup pertains to.  */
          tree cleanups;
          /* List of cleanup-lists of blocks containing this block,
             as they were at the locus where this block appears.
             There is an element for each containing block,
             ordered innermost containing block first.
             The tail of this list can be 0,
             if all remaining elements would be empty lists.
             The element's TREE_VALUE is the cleanup-list of that block,
             which may be null.  */
          tree outer_cleanups;
          /* Chain of labels defined inside this binding contour.
             For contours that have stack levels or cleanups.  */
          struct label_chain *label_chain;
          /* Nonzero if this is associated with an EH region.  */
          int exception_region;
          /* The saved target_temp_slot_level from our outer block.
             We may reset target_temp_slot_level to be the level of
             this block, if that is done, target_temp_slot_level
             reverts to the saved target_temp_slot_level at the very
             end of the block.  */
          int block_target_temp_slot_level;
          /* True if we are currently emitting insns in an area of
             output code that is controlled by a conditional
             expression.  This is used by the cleanup handling code to
             generate conditional cleanup actions.  */
          int conditional_code;
          /* A place to move the start of the exception region for any
             of the conditional cleanups, must be at the end or after
             the start of the last unconditional cleanup, and before any
             conditional branch points.  */
          rtx last_unconditional_cleanup;
        } GTY ((tag ("BLOCK_NESTING"))) block;
      /* For switch (C) or case (Pascal) statements,
         and also for dummies (see `expand_start_case_dummy').  */
      struct nesting_case
        {
          /* The insn after which the case dispatch should finally
             be emitted.  Zero for a dummy.  */
          rtx start;
          /* A list of case labels; it is first built as an AVL tree.
             During expand_end_case, this is converted to a list, and may be
             rearranged into a nearly balanced binary tree.  */
          struct case_node *case_list;
          /* Label to jump to if no case matches.  */
          tree default_label;
          /* The expression to be dispatched on.  */
          tree index_expr;
          /* Type that INDEX_EXPR should be converted to.  */
          tree nominal_type;
          /* Name of this kind of statement, for warnings.  */
          const char *printname;
          /* Used to save no_line_numbers till we see the first case label.
             We set this to -1 when we see the first case label in this
             case statement.  */
          int line_number_status;
        } GTY ((tag ("CASE_NESTING"))) case_stmt;
    } GTY ((desc ("%1.desc"))) data;
};

/* Allocate and return a new `struct nesting'.  */

#define ALLOC_NESTING() ggc_alloc (sizeof (struct nesting))

/* Pop the nesting stack element by element until we pop off
   the element which is at the top of STACK.
   Update all the other stacks, popping off elements from them
   as we pop them from nesting_stack.  */

#define POPSTACK(STACK)                                 \
do { struct nesting *target = STACK;                    \
     struct nesting *this;                              \
     do { this = nesting_stack;                         \
          if (loop_stack == this)                       \
            loop_stack = loop_stack->next;              \
          if (cond_stack == this)                       \
            cond_stack = cond_stack->next;              \
          if (block_stack == this)                      \
            block_stack = block_stack->next;            \
          if (stack_block_stack == this)                \
            stack_block_stack = stack_block_stack->next; \
          if (case_stack == this)                       \
            case_stack = case_stack->next;              \
          nesting_depth = nesting_stack->depth - 1;     \
          nesting_stack = this->all; }                  \
     while (this != target); } while (0)
\f
/* In some cases it is impossible to generate code for a forward goto
   until the label definition is seen.  This happens when it may be necessary
   for the goto to reset the stack pointer: we don't yet know how to do that.
   So expand_goto puts an entry on this fixup list.
   Each time a binding contour that resets the stack is exited,
   we check each fixup.
   If the target label has now been defined, we can insert the proper code.  */

struct goto_fixup GTY(())
{
  /* Points to following fixup.  */
  struct goto_fixup *next;
  /* Points to the insn before the jump insn.
     If more code must be inserted, it goes after this insn.  */
  rtx before_jump;
  /* The LABEL_DECL that this jump is jumping to, or 0
     for break, continue or return.  */
  tree target;
  /* The BLOCK for the place where this goto was found.  */
  tree context;
  /* The CODE_LABEL rtx that this is jumping to.  */
  rtx target_rtl;
  /* Number of binding contours started in current function
     before the label reference.  */
  int block_start_count;
  /* The outermost stack level that should be restored for this jump.
     Each time a binding contour that resets the stack is exited,
     if the target label is *not* yet defined, this slot is updated.  */
  rtx stack_level;
  /* List of lists of cleanup expressions to be run by this goto.
     There is one element for each block that this goto is within.
     The tail of this list can be 0,
     if all remaining elements would be empty.
     The TREE_VALUE contains the cleanup list of that block as of the
     time this goto was seen.
     The TREE_ADDRESSABLE flag is 1 for a block that has been exited.  */
  tree cleanup_list_list;
};

/* Within any binding contour that must restore a stack level,
   all labels are recorded with a chain of these structures.  */

struct label_chain GTY(())
{
  /* Points to following fixup.  */
  struct label_chain *next;
  tree label;
};

struct stmt_status GTY(())
{
  /* Chain of all pending binding contours.  */
  struct nesting * x_block_stack;

  /* If any new stacks are added here, add them to POPSTACKS too.  */

  /* Chain of all pending binding contours that restore stack levels
     or have cleanups.  */
  struct nesting * x_stack_block_stack;

  /* Chain of all pending conditional statements.  */
  struct nesting * x_cond_stack;

  /* Chain of all pending loops.  */
  struct nesting * x_loop_stack;

  /* Chain of all pending case or switch statements.  */
  struct nesting * x_case_stack;

  /* Separate chain including all of the above,
     chained through the `all' field.  */
  struct nesting * x_nesting_stack;

  /* Number of entries on nesting_stack now.  */
  int x_nesting_depth;

  /* Number of binding contours started so far in this function.  */
  int x_block_start_count;

  /* Each time we expand an expression-statement,
     record the expr's type and its RTL value here.  */
  tree x_last_expr_type;
  rtx x_last_expr_value;
  rtx x_last_expr_alt_rtl;

  /* Nonzero if within a ({...}) grouping, in which case we must
     always compute a value for each expr-stmt in case it is the last one.  */
  int x_expr_stmts_for_value;

  /* Location of last line-number note, whether we actually
     emitted it or not.  */
  location_t x_emit_locus;

  struct goto_fixup *x_goto_fixup_chain;
};

#define block_stack (cfun->stmt->x_block_stack)
#define stack_block_stack (cfun->stmt->x_stack_block_stack)
#define cond_stack (cfun->stmt->x_cond_stack)
#define loop_stack (cfun->stmt->x_loop_stack)
#define case_stack (cfun->stmt->x_case_stack)
#define nesting_stack (cfun->stmt->x_nesting_stack)
#define nesting_depth (cfun->stmt->x_nesting_depth)
#define current_block_start_count (cfun->stmt->x_block_start_count)
#define last_expr_type (cfun->stmt->x_last_expr_type)
#define last_expr_value (cfun->stmt->x_last_expr_value)
#define last_expr_alt_rtl (cfun->stmt->x_last_expr_alt_rtl)
#define expr_stmts_for_value (cfun->stmt->x_expr_stmts_for_value)
#define emit_locus (cfun->stmt->x_emit_locus)
#define goto_fixup_chain (cfun->stmt->x_goto_fixup_chain)

/* Nonzero if we are using EH to handle cleanups.  */
static int using_eh_for_cleanups_p = 0;

static int n_occurrences (int, const char *);
static bool decl_conflicts_with_clobbers_p (tree, const HARD_REG_SET);
static void expand_goto_internal (tree, rtx, rtx);
static int expand_fixup (tree, rtx, rtx);
static rtx expand_nl_handler_label (rtx, rtx);
static void expand_nl_goto_receiver (void);
static void expand_nl_goto_receivers (struct nesting *);
static void fixup_gotos (struct nesting *, rtx, tree, rtx, int);
static bool check_operand_nalternatives (tree, tree);
static bool check_unique_operand_names (tree, tree);
static char *resolve_operand_name_1 (char *, tree, tree);
static void expand_null_return_1 (rtx);
static enum br_predictor return_prediction (rtx);
static rtx shift_return_value (rtx);
static void expand_value_return (rtx);
static int tail_recursion_args (tree, tree);
static void expand_cleanups (tree, int, int);
static void check_seenlabel (void);
static void do_jump_if_equal (rtx, rtx, rtx, int);
static int estimate_case_costs (case_node_ptr);
static bool same_case_target_p (rtx, rtx);
static void strip_default_case_nodes (case_node_ptr *, rtx);
static bool lshift_cheap_p (void);
static int case_bit_test_cmp (const void *, const void *);
static void emit_case_bit_tests (tree, tree, tree, tree, case_node_ptr, rtx);
static void group_case_nodes (case_node_ptr);
static void balance_case_nodes (case_node_ptr *, case_node_ptr);
static int node_has_low_bound (case_node_ptr, tree);
static int node_has_high_bound (case_node_ptr, tree);
static int node_is_bounded (case_node_ptr, tree);
static void emit_jump_if_reachable (rtx);
static void emit_case_nodes (rtx, case_node_ptr, rtx, tree);
static struct case_node *case_tree2list (case_node *, case_node *);
\f
void
using_eh_for_cleanups (void)
{
  using_eh_for_cleanups_p = 1;
}

void
init_stmt_for_function (void)
{
  cfun->stmt = ggc_alloc_cleared (sizeof (struct stmt_status));
}
\f
/* Record the current file and line.  Called from emit_line_note.  */

void
set_file_and_line_for_stmt (location_t location)
{
  /* If we're outputting an inline function, and we add a line note,
     there may be no CFUN->STMT information.  So, there's no need to
     update it.  */
  if (cfun->stmt)
    emit_locus = location;
}

/* Emit a no-op instruction.  */

void
emit_nop (void)
{
  rtx last_insn;

  last_insn = get_last_insn ();
  if (!optimize
      && (GET_CODE (last_insn) == CODE_LABEL
          || (GET_CODE (last_insn) == NOTE
              && prev_real_insn (last_insn) == 0)))
    emit_insn (gen_nop ());
}
\f
/* Return the rtx-label that corresponds to a LABEL_DECL,
   creating it if necessary.  */

rtx
label_rtx (tree label)
{
  if (TREE_CODE (label) != LABEL_DECL)
    abort ();

  if (!DECL_RTL_SET_P (label))
    SET_DECL_RTL (label, gen_label_rtx ());

  return DECL_RTL (label);
}

/* As above, but also put it on the forced-reference list of the
   function that contains it.  */
rtx
force_label_rtx (tree label)
{
  rtx ref = label_rtx (label);
  tree function = decl_function_context (label);
  struct function *p;

  if (!function)
    abort ();

  if (function != current_function_decl
      && function != inline_function_decl)
    p = find_function_data (function);
  else
    p = cfun;

  p->expr->x_forced_labels = gen_rtx_EXPR_LIST (VOIDmode, ref,
                                                p->expr->x_forced_labels);
  return ref;
}

/* Add an unconditional jump to LABEL as the next sequential instruction.  */

void
emit_jump (rtx label)
{
  do_pending_stack_adjust ();
  emit_jump_insn (gen_jump (label));
  emit_barrier ();
}

/* Emit code to jump to the address
   specified by the pointer expression EXP.  */

void
expand_computed_goto (tree exp)
{
  rtx x = expand_expr (exp, NULL_RTX, VOIDmode, 0);

  x = convert_memory_address (Pmode, x);

  emit_queue ();

  if (! cfun->computed_goto_common_label)
    {
      cfun->computed_goto_common_reg = copy_to_mode_reg (Pmode, x);
      cfun->computed_goto_common_label = gen_label_rtx ();

      do_pending_stack_adjust ();
      emit_label (cfun->computed_goto_common_label);
      emit_indirect_jump (cfun->computed_goto_common_reg);

      current_function_has_computed_jump = 1;
    }
  else
    {
      emit_move_insn (cfun->computed_goto_common_reg, x);
      emit_jump (cfun->computed_goto_common_label);
    }
}
\f
/* Handle goto statements and the labels that they can go to.  */

/* Specify the location in the RTL code of a label LABEL,
   which is a LABEL_DECL tree node.

   This is used for the kind of label that the user can jump to with a
   goto statement, and for alternatives of a switch or case statement.
   RTL labels generated for loops and conditionals don't go through here;
   they are generated directly at the RTL level, by other functions below.

   Note that this has nothing to do with defining label *names*.
   Languages vary in how they do that and what that even means.  */

void
expand_label (tree label)
{
  struct label_chain *p;

  do_pending_stack_adjust ();
  emit_label (label_rtx (label));
  if (DECL_NAME (label))
    LABEL_NAME (DECL_RTL (label)) = IDENTIFIER_POINTER (DECL_NAME (label));

  if (stack_block_stack != 0)
    {
      p = ggc_alloc (sizeof (struct label_chain));
      p->next = stack_block_stack->data.block.label_chain;
      stack_block_stack->data.block.label_chain = p;
      p->label = label;
    }
}

/* Declare that LABEL (a LABEL_DECL) may be used for nonlocal gotos
   from nested functions.  */

void
declare_nonlocal_label (tree label)
{
  rtx slot = assign_stack_local (Pmode, GET_MODE_SIZE (Pmode), 0);

  nonlocal_labels = tree_cons (NULL_TREE, label, nonlocal_labels);
  LABEL_PRESERVE_P (label_rtx (label)) = 1;
  if (nonlocal_goto_handler_slots == 0)
    {
      emit_stack_save (SAVE_NONLOCAL,
                       &nonlocal_goto_stack_level,
                       PREV_INSN (tail_recursion_reentry));
    }
  nonlocal_goto_handler_slots
    = gen_rtx_EXPR_LIST (VOIDmode, slot, nonlocal_goto_handler_slots);
}

/* Generate RTL code for a `goto' statement with target label LABEL.
   LABEL should be a LABEL_DECL tree node that was or will later be
   defined with `expand_label'.  */

void
expand_goto (tree label)
{
  tree context;

  /* Check for a nonlocal goto to a containing function.  */
  context = decl_function_context (label);
  if (context != 0 && context != current_function_decl)
    {
      struct function *p = find_function_data (context);
      rtx label_ref = gen_rtx_LABEL_REF (Pmode, label_rtx (label));
      rtx handler_slot, static_chain, save_area, insn;
      tree link;

      /* Find the corresponding handler slot for this label.  */
      handler_slot = p->x_nonlocal_goto_handler_slots;
      for (link = p->x_nonlocal_labels; TREE_VALUE (link) != label;
           link = TREE_CHAIN (link))
        handler_slot = XEXP (handler_slot, 1);
      handler_slot = XEXP (handler_slot, 0);

      p->has_nonlocal_label = 1;
      current_function_has_nonlocal_goto = 1;
      LABEL_REF_NONLOCAL_P (label_ref) = 1;

      /* Copy the rtl for the slots so that they won't be shared in
         case the virtual stack vars register gets instantiated differently
         in the parent than in the child.  */

      static_chain = copy_to_reg (lookup_static_chain (label));

      /* Get addr of containing function's current nonlocal goto handler,
         which will do any cleanups and then jump to the label.  */
      handler_slot = copy_to_reg (replace_rtx (copy_rtx (handler_slot),
                                               virtual_stack_vars_rtx,
                                               static_chain));

      /* Get addr of containing function's nonlocal save area.  */
      save_area = p->x_nonlocal_goto_stack_level;
      if (save_area)
        save_area = replace_rtx (copy_rtx (save_area),
                                 virtual_stack_vars_rtx, static_chain);

#if HAVE_nonlocal_goto
      if (HAVE_nonlocal_goto)
        emit_insn (gen_nonlocal_goto (static_chain, handler_slot,
                                      save_area, label_ref));
      else
#endif
        {
          emit_insn (gen_rtx_CLOBBER (VOIDmode,
                                      gen_rtx_MEM (BLKmode,
                                                   gen_rtx_SCRATCH (VOIDmode))));
          emit_insn (gen_rtx_CLOBBER (VOIDmode,
                                      gen_rtx_MEM (BLKmode,
                                                   hard_frame_pointer_rtx)));

          /* Restore frame pointer for containing function.
             This sets the actual hard register used for the frame pointer
             to the location of the function's incoming static chain info.
             The non-local goto handler will then adjust it to contain the
             proper value and reload the argument pointer, if needed.  */
          emit_move_insn (hard_frame_pointer_rtx, static_chain);
          emit_stack_restore (SAVE_NONLOCAL, save_area, NULL_RTX);

          /* USE of hard_frame_pointer_rtx added for consistency;
             not clear if really needed.  */
          emit_insn (gen_rtx_USE (VOIDmode, hard_frame_pointer_rtx));
          emit_insn (gen_rtx_USE (VOIDmode, stack_pointer_rtx));
          emit_indirect_jump (handler_slot);
        }

      /* Search backwards to the jump insn and mark it as a
         non-local goto.  */
      for (insn = get_last_insn (); insn; insn = PREV_INSN (insn))
        {
          if (GET_CODE (insn) == JUMP_INSN)
            {
              REG_NOTES (insn) = alloc_EXPR_LIST (REG_NON_LOCAL_GOTO,
                                                  const0_rtx, REG_NOTES (insn));
              break;
            }
          else if (GET_CODE (insn) == CALL_INSN)
              break;
        }
    }
  else
    expand_goto_internal (label, label_rtx (label), NULL_RTX);
}

/* Generate RTL code for a `goto' statement with target label BODY.
   LABEL should be a LABEL_REF.
   LAST_INSN, if non-0, is the rtx we should consider as the last
   insn emitted (for the purposes of cleaning up a return).  */

static void
expand_goto_internal (tree body, rtx label, rtx last_insn)
{
  struct nesting *block;
  rtx stack_level = 0;

  if (GET_CODE (label) != CODE_LABEL)
    abort ();

  /* If label has already been defined, we can tell now
     whether and how we must alter the stack level.  */

  if (PREV_INSN (label) != 0)
    {
      /* Find the innermost pending block that contains the label.
         (Check containment by comparing insn-uids.)
         Then restore the outermost stack level within that block,
         and do cleanups of all blocks contained in it.  */
      for (block = block_stack; block; block = block->next)
        {
          if (INSN_UID (block->data.block.first_insn) < INSN_UID (label))
            break;
          if (block->data.block.stack_level != 0)
            stack_level = block->data.block.stack_level;
          /* Execute the cleanups for blocks we are exiting.  */
          if (block->data.block.cleanups != 0)
            {
              expand_cleanups (block->data.block.cleanups, 1, 1);
              do_pending_stack_adjust ();
            }
        }

      if (stack_level)
        {
          /* Ensure stack adjust isn't done by emit_jump, as this
             would clobber the stack pointer.  This one should be
             deleted as dead by flow.  */
          clear_pending_stack_adjust ();
          do_pending_stack_adjust ();

          /* Don't do this adjust if it's to the end label and this function
             is to return with a depressed stack pointer.  */
          if (label == return_label
              && (((TREE_CODE (TREE_TYPE (current_function_decl))
                   == FUNCTION_TYPE)
                   && (TYPE_RETURNS_STACK_DEPRESSED
                       (TREE_TYPE (current_function_decl))))))
            ;
          else
            emit_stack_restore (SAVE_BLOCK, stack_level, NULL_RTX);
        }

      if (body != 0 && DECL_TOO_LATE (body))
        error ("jump to `%s' invalidly jumps into binding contour",
               IDENTIFIER_POINTER (DECL_NAME (body)));
    }
  /* Label not yet defined: may need to put this goto
     on the fixup list.  */
  else if (! expand_fixup (body, label, last_insn))
    {
      /* No fixup needed.  Record that the label is the target
         of at least one goto that has no fixup.  */
      if (body != 0)
        TREE_ADDRESSABLE (body) = 1;
    }

  emit_jump (label);
}
\f
/* Generate if necessary a fixup for a goto
   whose target label in tree structure (if any) is TREE_LABEL
   and whose target in rtl is RTL_LABEL.

   If LAST_INSN is nonzero, we pretend that the jump appears
   after insn LAST_INSN instead of at the current point in the insn stream.

   The fixup will be used later to insert insns just before the goto.
   Those insns will restore the stack level as appropriate for the
   target label, and will (in the case of C++) also invoke any object
   destructors which have to be invoked when we exit the scopes which
   are exited by the goto.

   Value is nonzero if a fixup is made.  */

static int
expand_fixup (tree tree_label, rtx rtl_label, rtx last_insn)
{
  struct nesting *block, *end_block;

  /* See if we can recognize which block the label will be output in.
     This is possible in some very common cases.
     If we succeed, set END_BLOCK to that block.
     Otherwise, set it to 0.  */

  if (cond_stack
      && (rtl_label == cond_stack->data.cond.endif_label
          || rtl_label == cond_stack->data.cond.next_label))
    end_block = cond_stack;
  /* If we are in a loop, recognize certain labels which
     are likely targets.  This reduces the number of fixups
     we need to create.  */
  else if (loop_stack
      && (rtl_label == loop_stack->data.loop.start_label
          || rtl_label == loop_stack->data.loop.end_label
          || rtl_label == loop_stack->data.loop.continue_label))
    end_block = loop_stack;
  else
    end_block = 0;

  /* Now set END_BLOCK to the binding level to which we will return.  */

  if (end_block)
    {
      struct nesting *next_block = end_block->all;
      block = block_stack;

      /* First see if the END_BLOCK is inside the innermost binding level.
         If so, then no cleanups or stack levels are relevant.  */
      while (next_block && next_block != block)
        next_block = next_block->all;

      if (next_block)
        return 0;

      /* Otherwise, set END_BLOCK to the innermost binding level
         which is outside the relevant control-structure nesting.  */
      next_block = block_stack->next;
      for (block = block_stack; block != end_block; block = block->all)
        if (block == next_block)
          next_block = next_block->next;
      end_block = next_block;
    }

  /* Does any containing block have a stack level or cleanups?
     If not, no fixup is needed, and that is the normal case
     (the only case, for standard C).  */
  for (block = block_stack; block != end_block; block = block->next)
    if (block->data.block.stack_level != 0
        || block->data.block.cleanups != 0)
      break;

  if (block != end_block)
    {
      /* Ok, a fixup is needed.  Add a fixup to the list of such.  */
      struct goto_fixup *fixup = ggc_alloc (sizeof (struct goto_fixup));
      /* In case an old stack level is restored, make sure that comes
         after any pending stack adjust.  */
      /* ?? If the fixup isn't to come at the present position,
         doing the stack adjust here isn't useful.  Doing it with our
         settings at that location isn't useful either.  Let's hope
         someone does it!  */
      if (last_insn == 0)
        do_pending_stack_adjust ();
      fixup->target = tree_label;
      fixup->target_rtl = rtl_label;

      /* Create a BLOCK node and a corresponding matched set of
         NOTE_INSN_BLOCK_BEG and NOTE_INSN_BLOCK_END notes at
         this point.  The notes will encapsulate any and all fixup
         code which we might later insert at this point in the insn
         stream.  Also, the BLOCK node will be the parent (i.e. the
         `SUPERBLOCK') of any other BLOCK nodes which we might create
         later on when we are expanding the fixup code.

         Note that optimization passes (including expand_end_loop)
         might move the *_BLOCK notes away, so we use a NOTE_INSN_DELETED
         as a placeholder.  */

      {
        rtx original_before_jump
          = last_insn ? last_insn : get_last_insn ();
        rtx start;
        rtx end;
        tree block;

        block = make_node (BLOCK);
        TREE_USED (block) = 1;

        if (!cfun->x_whole_function_mode_p)
          (*lang_hooks.decls.insert_block) (block);
        else
          {
            BLOCK_CHAIN (block)
              = BLOCK_CHAIN (DECL_INITIAL (current_function_decl));
            BLOCK_CHAIN (DECL_INITIAL (current_function_decl))
              = block;
          }

        start_sequence ();
        start = emit_note (NOTE_INSN_BLOCK_BEG);
        if (cfun->x_whole_function_mode_p)
          NOTE_BLOCK (start) = block;
        fixup->before_jump = emit_note (NOTE_INSN_DELETED);
        end = emit_note (NOTE_INSN_BLOCK_END);
        if (cfun->x_whole_function_mode_p)
          NOTE_BLOCK (end) = block;
        fixup->context = block;
        end_sequence ();
        emit_insn_after (start, original_before_jump);
      }

      fixup->block_start_count = current_block_start_count;
      fixup->stack_level = 0;
      fixup->cleanup_list_list
        = ((block->data.block.outer_cleanups
            || block->data.block.cleanups)
           ? tree_cons (NULL_TREE, block->data.block.cleanups,
                        block->data.block.outer_cleanups)
           : 0);
      fixup->next = goto_fixup_chain;
      goto_fixup_chain = fixup;
    }

  return block != 0;
}
\f
/* Expand any needed fixups in the outputmost binding level of the
   function.  FIRST_INSN is the first insn in the function.  */

void
expand_fixups (rtx first_insn)
{
  fixup_gotos (NULL, NULL_RTX, NULL_TREE, first_insn, 0);
}

/* When exiting a binding contour, process all pending gotos requiring fixups.
   THISBLOCK is the structure that describes the block being exited.
   STACK_LEVEL is the rtx for the stack level to restore exiting this contour.
   CLEANUP_LIST is a list of expressions to evaluate on exiting this contour.
   FIRST_INSN is the insn that began this contour.

   Gotos that jump out of this contour must restore the
   stack level and do the cleanups before actually jumping.

   DONT_JUMP_IN positive means report error if there is a jump into this
   contour from before the beginning of the contour.  This is also done if
   STACK_LEVEL is nonzero unless DONT_JUMP_IN is negative.  */

static void
fixup_gotos (struct nesting *thisblock, rtx stack_level,
             tree cleanup_list, rtx first_insn, int dont_jump_in)
{
  struct goto_fixup *f, *prev;

  /* F is the fixup we are considering; PREV is the previous one.  */
  /* We run this loop in two passes so that cleanups of exited blocks
     are run first, and blocks that are exited are marked so
     afterwards.  */

  for (prev = 0, f = goto_fixup_chain; f; prev = f, f = f->next)
    {
      /* Test for a fixup that is inactive because it is already handled.  */
      if (f->before_jump == 0)
        {
          /* Delete inactive fixup from the chain, if that is easy to do.  */
          if (prev != 0)
            prev->next = f->next;
        }
      /* Has this fixup's target label been defined?
         If so, we can finalize it.  */
      else if (PREV_INSN (f->target_rtl) != 0)
        {
          rtx cleanup_insns;

          /* If this fixup jumped into this contour from before the beginning
             of this contour, report an error.   This code used to use
             the first non-label insn after f->target_rtl, but that's
             wrong since such can be added, by things like put_var_into_stack
             and have INSN_UIDs that are out of the range of the block.  */
          /* ??? Bug: this does not detect jumping in through intermediate
             blocks that have stack levels or cleanups.
             It detects only a problem with the innermost block
             around the label.  */
          if (f->target != 0
              && (dont_jump_in > 0 || (dont_jump_in == 0 && stack_level)
                  || cleanup_list)
              && INSN_UID (first_insn) < INSN_UID (f->target_rtl)
              && INSN_UID (first_insn) > INSN_UID (f->before_jump)
              && ! DECL_ERROR_ISSUED (f->target))
            {
              error ("%Jlabel '%D' used before containing binding contour",
                     f->target, f->target);
              /* Prevent multiple errors for one label.  */
              DECL_ERROR_ISSUED (f->target) = 1;
            }

          /* We will expand the cleanups into a sequence of their own and
             then later on we will attach this new sequence to the insn
             stream just ahead of the actual jump insn.  */

          start_sequence ();

          /* Temporarily restore the lexical context where we will
             logically be inserting the fixup code.  We do this for the
             sake of getting the debugging information right.  */

          (*lang_hooks.decls.pushlevel) (0);
          (*lang_hooks.decls.set_block) (f->context);

          /* Expand the cleanups for blocks this jump exits.  */
          if (f->cleanup_list_list)
            {
              tree lists;
              for (lists = f->cleanup_list_list; lists; lists = TREE_CHAIN (lists))
                /* Marked elements correspond to blocks that have been closed.
                   Do their cleanups.  */
                if (TREE_ADDRESSABLE (lists)
                    && TREE_VALUE (lists) != 0)
                  {
                    expand_cleanups (TREE_VALUE (lists), 1, 1);
                    /* Pop any pushes done in the cleanups,
                       in case function is about to return.  */
                    do_pending_stack_adjust ();
                  }
            }

          /* Restore stack level for the biggest contour that this
             jump jumps out of.  */
          if (f->stack_level
              && ! (f->target_rtl == return_label
                    && ((TREE_CODE (TREE_TYPE (current_function_decl))
                         == FUNCTION_TYPE)
                        && (TYPE_RETURNS_STACK_DEPRESSED
                            (TREE_TYPE (current_function_decl))))))
            emit_stack_restore (SAVE_BLOCK, f->stack_level, f->before_jump);

          /* Finish up the sequence containing the insns which implement the
             necessary cleanups, and then attach that whole sequence to the
             insn stream just ahead of the actual jump insn.  Attaching it
             at that point insures that any cleanups which are in fact
             implicit C++ object destructions (which must be executed upon
             leaving the block) appear (to the debugger) to be taking place
             in an area of the generated code where the object(s) being
             destructed are still "in scope".  */

          cleanup_insns = get_insns ();
          (*lang_hooks.decls.poplevel) (1, 0, 0);

          end_sequence ();
          emit_insn_after (cleanup_insns, f->before_jump);

          f->before_jump = 0;
        }
    }

  /* For any still-undefined labels, do the cleanups for this block now.
     We must do this now since items in the cleanup list may go out
     of scope when the block ends.  */
  for (prev = 0, f = goto_fixup_chain; f; prev = f, f = f->next)
    if (f->before_jump != 0
        && PREV_INSN (f->target_rtl) == 0
        /* Label has still not appeared.  If we are exiting a block with
           a stack level to restore, that started before the fixup,
           mark this stack level as needing restoration
           when the fixup is later finalized.  */
        && thisblock != 0
        /* Note: if THISBLOCK == 0 and we have a label that hasn't appeared, it
           means the label is undefined.  That's erroneous, but possible.  */
        && (thisblock->data.block.block_start_count
            <= f->block_start_count))
      {
        tree lists = f->cleanup_list_list;
        rtx cleanup_insns;

        for (; lists; lists = TREE_CHAIN (lists))
          /* If the following elt. corresponds to our containing block
             then the elt. must be for this block.  */
          if (TREE_CHAIN (lists) == thisblock->data.block.outer_cleanups)
            {
              start_sequence ();
              (*lang_hooks.decls.pushlevel) (0);
              (*lang_hooks.decls.set_block) (f->context);
              expand_cleanups (TREE_VALUE (lists), 1, 1);
              do_pending_stack_adjust ();
              cleanup_insns = get_insns ();
              (*lang_hooks.decls.poplevel) (1, 0, 0);
              end_sequence ();
              if (cleanup_insns != 0)
                f->before_jump
                  = emit_insn_after (cleanup_insns, f->before_jump);

              f->cleanup_list_list = TREE_CHAIN (lists);
            }

        if (stack_level)
          f->stack_level = stack_level;
      }
}
\f
/* Return the number of times character C occurs in string S.  */
static int
n_occurrences (int c, const char *s)
{
  int n = 0;
  while (*s)
    n += (*s++ == c);
  return n;
}
\f
/* Generate RTL for an asm statement (explicit assembler code).
   STRING is a STRING_CST node containing the assembler code text,
   or an ADDR_EXPR containing a STRING_CST.  VOL nonzero means the
   insn is volatile; don't optimize it.  */

void
expand_asm (tree string, int vol)
{
  rtx body;

  if (TREE_CODE (string) == ADDR_EXPR)
    string = TREE_OPERAND (string, 0);

  body = gen_rtx_ASM_INPUT (VOIDmode, TREE_STRING_POINTER (string));

  MEM_VOLATILE_P (body) = vol;

  emit_insn (body);

  clear_last_expr ();
}

/* Parse the output constraint pointed to by *CONSTRAINT_P.  It is the
   OPERAND_NUMth output operand, indexed from zero.  There are NINPUTS
   inputs and NOUTPUTS outputs to this extended-asm.  Upon return,
   *ALLOWS_MEM will be TRUE iff the constraint allows the use of a
   memory operand.  Similarly, *ALLOWS_REG will be TRUE iff the
   constraint allows the use of a register operand.  And, *IS_INOUT
   will be true if the operand is read-write, i.e., if it is used as
   an input as well as an output.  If *CONSTRAINT_P is not in
   canonical form, it will be made canonical.  (Note that `+' will be
   replaced with `=' as part of this process.)

   Returns TRUE if all went well; FALSE if an error occurred.  */

bool
parse_output_constraint (const char **constraint_p, int operand_num,
                         int ninputs, int noutputs, bool *allows_mem,
                         bool *allows_reg, bool *is_inout)
{
  const char *constraint = *constraint_p;
  const char *p;

  /* Assume the constraint doesn't allow the use of either a register
     or memory.  */
  *allows_mem = false;
  *allows_reg = false;

  /* Allow the `=' or `+' to not be at the beginning of the string,
     since it wasn't explicitly documented that way, and there is a
     large body of code that puts it last.  Swap the character to
     the front, so as not to uglify any place else.  */
  p = strchr (constraint, '=');
  if (!p)
    p = strchr (constraint, '+');

  /* If the string doesn't contain an `=', issue an error
     message.  */
  if (!p)
    {
      error ("output operand constraint lacks `='");
      return false;
    }

  /* If the constraint begins with `+', then the operand is both read
     from and written to.  */
  *is_inout = (*p == '+');

  /* Canonicalize the output constraint so that it begins with `='.  */
  if (p != constraint || is_inout)
    {
      char *buf;
      size_t c_len = strlen (constraint);

      if (p != constraint)
        warning ("output constraint `%c' for operand %d is not at the beginning",
                 *p, operand_num);

      /* Make a copy of the constraint.  */
      buf = alloca (c_len + 1);
      strcpy (buf, constraint);
      /* Swap the first character and the `=' or `+'.  */
      buf[p - constraint] = buf[0];
      /* Make sure the first character is an `='.  (Until we do this,
         it might be a `+'.)  */
      buf[0] = '=';
      /* Replace the constraint with the canonicalized string.  */
      *constraint_p = ggc_alloc_string (buf, c_len);
      constraint = *constraint_p;
    }

  /* Loop through the constraint string.  */
  for (p = constraint + 1; *p; p += CONSTRAINT_LEN (*p, p))
    switch (*p)
      {
      case '+':
      case '=':
        error ("operand constraint contains incorrectly positioned '+' or '='");
        return false;

      case '%':
        if (operand_num + 1 == ninputs + noutputs)
          {
            error ("`%%' constraint used with last operand");
            return false;
          }
        break;

      case 'V':  case 'm':  case 'o':
        *allows_mem = true;
        break;

      case '?':  case '!':  case '*':  case '&':  case '#':
      case 'E':  case 'F':  case 'G':  case 'H':
      case 's':  case 'i':  case 'n':
      case 'I':  case 'J':  case 'K':  case 'L':  case 'M':
      case 'N':  case 'O':  case 'P':  case ',':
        break;

      case '0':  case '1':  case '2':  case '3':  case '4':
      case '5':  case '6':  case '7':  case '8':  case '9':
      case '[':
        error ("matching constraint not valid in output operand");
        return false;

      case '<':  case '>':
        /* ??? Before flow, auto inc/dec insns are not supposed to exist,
           excepting those that expand_call created.  So match memory
           and hope.  */
        *allows_mem = true;
        break;

      case 'g':  case 'X':
        *allows_reg = true;
        *allows_mem = true;
        break;

      case 'p': case 'r':
        *allows_reg = true;
        break;

      default:
        if (!ISALPHA (*p))
          break;
        if (REG_CLASS_FROM_CONSTRAINT (*p, p) != NO_REGS)
          *allows_reg = true;
#ifdef EXTRA_CONSTRAINT_STR
        else if (EXTRA_ADDRESS_CONSTRAINT (*p, p))
          *allows_reg = true;
        else if (EXTRA_MEMORY_CONSTRAINT (*p, p))
          *allows_mem = true;
        else
          {
            /* Otherwise we can't assume anything about the nature of
               the constraint except that it isn't purely registers.
               Treat it like "g" and hope for the best.  */
            *allows_reg = true;
            *allows_mem = true;
          }
#endif
        break;
      }

  return true;
}

/* Similar, but for input constraints.  */

bool
parse_input_constraint (const char **constraint_p, int input_num,
                        int ninputs, int noutputs, int ninout,
                        const char * const * constraints,
                        bool *allows_mem, bool *allows_reg)
{
  const char *constraint = *constraint_p;
  const char *orig_constraint = constraint;
  size_t c_len = strlen (constraint);
  size_t j;
  bool saw_match = false;

  /* Assume the constraint doesn't allow the use of either
     a register or memory.  */
  *allows_mem = false;
  *allows_reg = false;

  /* Make sure constraint has neither `=', `+', nor '&'.  */

  for (j = 0; j < c_len; j += CONSTRAINT_LEN (constraint[j], constraint+j))
    switch (constraint[j])
      {
      case '+':  case '=':  case '&':
        if (constraint == orig_constraint)
          {
            error ("input operand constraint contains `%c'", constraint[j]);
            return false;
          }
        break;

      case '%':
        if (constraint == orig_constraint
            && input_num + 1 == ninputs - ninout)
          {
            error ("`%%' constraint used with last operand");
            return false;
          }
        break;

      case 'V':  case 'm':  case 'o':
        *allows_mem = true;
        break;

      case '<':  case '>':
      case '?':  case '!':  case '*':  case '#':
      case 'E':  case 'F':  case 'G':  case 'H':
      case 's':  case 'i':  case 'n':
      case 'I':  case 'J':  case 'K':  case 'L':  case 'M':
      case 'N':  case 'O':  case 'P':  case ',':
        break;

        /* Whether or not a numeric constraint allows a register is
           decided by the matching constraint, and so there is no need
           to do anything special with them.  We must handle them in
           the default case, so that we don't unnecessarily force
           operands to memory.  */
      case '0':  case '1':  case '2':  case '3':  case '4':
      case '5':  case '6':  case '7':  case '8':  case '9':
        {
          char *end;
          unsigned long match;

          saw_match = true;

          match = strtoul (constraint + j, &end, 10);
          if (match >= (unsigned long) noutputs)
            {
              error ("matching constraint references invalid operand number");
              return false;
            }

          /* Try and find the real constraint for this dup.  Only do this
             if the matching constraint is the only alternative.  */
          if (*end == '\0'
              && (j == 0 || (j == 1 && constraint[0] == '%')))
            {
              constraint = constraints[match];
              *constraint_p = constraint;
              c_len = strlen (constraint);
              j = 0;
              /* ??? At the end of the loop, we will skip the first part of
                 the matched constraint.  This assumes not only that the
                 other constraint is an output constraint, but also that
                 the '=' or '+' come first.  */
              break;
            }
          else
            j = end - constraint;
          /* Anticipate increment at end of loop.  */
          j--;
        }
        /* Fall through.  */

      case 'p':  case 'r':
        *allows_reg = true;
        break;

      case 'g':  case 'X':
        *allows_reg = true;
        *allows_mem = true;
        break;

      default:
        if (! ISALPHA (constraint[j]))
          {
            error ("invalid punctuation `%c' in constraint", constraint[j]);
            return false;
          }
        if (REG_CLASS_FROM_CONSTRAINT (constraint[j], constraint + j)
            != NO_REGS)
          *allows_reg = true;
#ifdef EXTRA_CONSTRAINT_STR
        else if (EXTRA_ADDRESS_CONSTRAINT (constraint[j], constraint + j))
          *allows_reg = true;
        else if (EXTRA_MEMORY_CONSTRAINT (constraint[j], constraint + j))
          *allows_mem = true;
        else
          {
            /* Otherwise we can't assume anything about the nature of
               the constraint except that it isn't purely registers.
               Treat it like "g" and hope for the best.  */
            *allows_reg = true;
            *allows_mem = true;
          }
#endif
        break;
      }

  if (saw_match && !*allows_reg)
    warning ("matching constraint does not allow a register");

  return true;
}

/* Check for overlap between registers marked in CLOBBERED_REGS and
   anything inappropriate in DECL.  Emit error and return TRUE for error,
   FALSE for ok.  */

static bool
decl_conflicts_with_clobbers_p (tree decl, const HARD_REG_SET clobbered_regs)
{
  /* Conflicts between asm-declared register variables and the clobber
     list are not allowed.  */
  if ((TREE_CODE (decl) == VAR_DECL || TREE_CODE (decl) == PARM_DECL)
      && DECL_REGISTER (decl)
      && REG_P (DECL_RTL (decl))
      && REGNO (DECL_RTL (decl)) < FIRST_PSEUDO_REGISTER)
    {
      rtx reg = DECL_RTL (decl);
      unsigned int regno;

      for (regno = REGNO (reg);
           regno < (REGNO (reg)
                    + HARD_REGNO_NREGS (REGNO (reg), GET_MODE (reg)));
           regno++)
        if (TEST_HARD_REG_BIT (clobbered_regs, regno))
          {
            error ("asm-specifier for variable `%s' conflicts with asm clobber list",
                   IDENTIFIER_POINTER (DECL_NAME (decl)));

            /* Reset registerness to stop multiple errors emitted for a
               single variable.  */
            DECL_REGISTER (decl) = 0;
            return true;
          }
    }
  return false;
}

/* Generate RTL for an asm statement with arguments.
   STRING is the instruction template.
   OUTPUTS is a list of output arguments (lvalues); INPUTS a list of inputs.
   Each output or input has an expression in the TREE_VALUE and
   and a tree list in TREE_PURPOSE which in turn contains a constraint
   name in TREE_VALUE (or NULL_TREE) and a constraint string
   in TREE_PURPOSE.
   CLOBBERS is a list of STRING_CST nodes each naming a hard register
   that is clobbered by this insn.

   Not all kinds of lvalue that may appear in OUTPUTS can be stored directly.
   Some elements of OUTPUTS may be replaced with trees representing temporary
   values.  The caller should copy those temporary values to the originally
   specified lvalues.

   VOL nonzero means the insn is volatile; don't optimize it.  */

void
expand_asm_operands (tree string, tree outputs, tree inputs,
                     tree clobbers, int vol, location_t locus)
{
  rtvec argvec, constraintvec;
  rtx body;
  int ninputs = list_length (inputs);
  int noutputs = list_length (outputs);
  int ninout;
  int nclobbers;
  HARD_REG_SET clobbered_regs;
  int clobber_conflict_found = 0;
  tree tail;
  tree t;
  int i;
  /* Vector of RTX's of evaluated output operands.  */
  rtx *output_rtx = alloca (noutputs * sizeof (rtx));
  int *inout_opnum = alloca (noutputs * sizeof (int));
  rtx *real_output_rtx = alloca (noutputs * sizeof (rtx));
  enum machine_mode *inout_mode
    = alloca (noutputs * sizeof (enum machine_mode));
  const char **constraints
    = alloca ((noutputs + ninputs) * sizeof (const char *));
  int old_generating_concat_p = generating_concat_p;

  /* An ASM with no outputs needs to be treated as volatile, for now.  */
  if (noutputs == 0)
    vol = 1;

  if (! check_operand_nalternatives (outputs, inputs))
    return;

  string = resolve_asm_operand_names (string, outputs, inputs);

  /* Collect constraints.  */
  i = 0;
  for (t = outputs; t ; t = TREE_CHAIN (t), i++)
    constraints[i] = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (t)));
  for (t = inputs; t ; t = TREE_CHAIN (t), i++)
    constraints[i] = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (t)));

#ifdef MD_ASM_CLOBBERS
  /* Sometimes we wish to automatically clobber registers across an asm.
     Case in point is when the i386 backend moved from cc0 to a hard reg --
     maintaining source-level compatibility means automatically clobbering
     the flags register.  */
  MD_ASM_CLOBBERS (clobbers);
#endif

  /* Count the number of meaningful clobbered registers, ignoring what
     we would ignore later.  */
  nclobbers = 0;
  CLEAR_HARD_REG_SET (clobbered_regs);
  for (tail = clobbers; tail; tail = TREE_CHAIN (tail))
    {
      const char *regname = TREE_STRING_POINTER (TREE_VALUE (tail));

      i = decode_reg_name (regname);
      if (i >= 0 || i == -4)
        ++nclobbers;
      else if (i == -2)
        error ("unknown register name `%s' in `asm'", regname);

      /* Mark clobbered registers.  */
      if (i >= 0)
        {
          /* Clobbering the PIC register is an error */
          if (i == (int) PIC_OFFSET_TABLE_REGNUM)
            {
              error ("PIC register `%s' clobbered in `asm'", regname);
              return;
            }

          SET_HARD_REG_BIT (clobbered_regs, i);
        }
    }

  clear_last_expr ();

  /* First pass over inputs and outputs checks validity and sets
     mark_addressable if needed.  */

  ninout = 0;
  for (i = 0, tail = outputs; tail; tail = TREE_CHAIN (tail), i++)
    {
      tree val = TREE_VALUE (tail);
      tree type = TREE_TYPE (val);
      const char *constraint;
      bool is_inout;
      bool allows_reg;
      bool allows_mem;

      /* If there's an erroneous arg, emit no insn.  */
      if (type == error_mark_node)
        return;

      /* Try to parse the output constraint.  If that fails, there's
         no point in going further.  */
      constraint = constraints[i];
      if (!parse_output_constraint (&constraint, i, ninputs, noutputs,
                                    &allows_mem, &allows_reg, &is_inout))
        return;

      if (! allows_reg
          && (allows_mem
              || is_inout
              || (DECL_P (val)
                  && GET_CODE (DECL_RTL (val)) == REG
                  && GET_MODE (DECL_RTL (val)) != TYPE_MODE (type))))
        (*lang_hooks.mark_addressable) (val);

      if (is_inout)
        ninout++;
    }

  ninputs += ninout;
  if (ninputs + noutputs > MAX_RECOG_OPERANDS)
    {
      error ("more than %d operands in `asm'", MAX_RECOG_OPERANDS);
      return;
    }

  for (i = 0, tail = inputs; tail; i++, tail = TREE_CHAIN (tail))
    {
      bool allows_reg, allows_mem;
      const char *constraint;

      /* If there's an erroneous arg, emit no insn, because the ASM_INPUT
         would get VOIDmode and that could cause a crash in reload.  */
      if (TREE_TYPE (TREE_VALUE (tail)) == error_mark_node)
        return;

      constraint = constraints[i + noutputs];
      if (! parse_input_constraint (&constraint, i, ninputs, noutputs, ninout,
                                    constraints, &allows_mem, &allows_reg))
        return;

      if (! allows_reg && allows_mem)
        (*lang_hooks.mark_addressable) (TREE_VALUE (tail));
    }

  /* Second pass evaluates arguments.  */

  ninout = 0;
  for (i = 0, tail = outputs; tail; tail = TREE_CHAIN (tail), i++)
    {
      tree val = TREE_VALUE (tail);
      tree type = TREE_TYPE (val);
      bool is_inout;
      bool allows_reg;
      bool allows_mem;
      rtx op;

      if (!parse_output_constraint (&constraints[i], i, ninputs,
                                    noutputs, &allows_mem, &allows_reg,
                                    &is_inout))
        abort ();

      /* If an output operand is not a decl or indirect ref and our constraint
         allows a register, make a temporary to act as an intermediate.
         Make the asm insn write into that, then our caller will copy it to
         the real output operand.  Likewise for promoted variables.  */

      generating_concat_p = 0;

      real_output_rtx[i] = NULL_RTX;
      if ((TREE_CODE (val) == INDIRECT_REF
           && allows_mem)
          || (DECL_P (val)
              && (allows_mem || GET_CODE (DECL_RTL (val)) == REG)
              && ! (GET_CODE (DECL_RTL (val)) == REG
                    && GET_MODE (DECL_RTL (val)) != TYPE_MODE (type)))
          || ! allows_reg
          || is_inout)
        {
          op = expand_expr (val, NULL_RTX, VOIDmode, EXPAND_WRITE);
          if (GET_CODE (op) == MEM)
            op = validize_mem (op);

          if (! allows_reg && GET_CODE (op) != MEM)
            error ("output number %d not directly addressable", i);
          if ((! allows_mem && GET_CODE (op) == MEM)
              || GET_CODE (op) == CONCAT)
            {
              real_output_rtx[i] = protect_from_queue (op, 1);
              op = gen_reg_rtx (GET_MODE (op));
              if (is_inout)
                emit_move_insn (op, real_output_rtx[i]);
            }
        }
      else
        {
          op = assign_temp (type, 0, 0, 1);
          op = validize_mem (op);
          TREE_VALUE (tail) = make_tree (type, op);
        }
      output_rtx[i] = op;

      generating_concat_p = old_generating_concat_p;

      if (is_inout)
        {
          inout_mode[ninout] = TYPE_MODE (type);
          inout_opnum[ninout++] = i;
        }

      if (decl_conflicts_with_clobbers_p (val, clobbered_regs))
        clobber_conflict_found = 1;
    }

  /* Make vectors for the expression-rtx, constraint strings,
     and named operands.  */

  argvec = rtvec_alloc (ninputs);
  constraintvec = rtvec_alloc (ninputs);

  body = gen_rtx_ASM_OPERANDS ((noutputs == 0 ? VOIDmode
                                : GET_MODE (output_rtx[0])),
                               TREE_STRING_POINTER (string),
                               empty_string, 0, argvec, constraintvec,
                               locus.file, locus.line);

  MEM_VOLATILE_P (body) = vol;

  /* Eval the inputs and put them into ARGVEC.
     Put their constraints into ASM_INPUTs and store in CONSTRAINTS.  */

  for (i = 0, tail = inputs; tail; tail = TREE_CHAIN (tail), ++i)
    {
      bool allows_reg, allows_mem;
      const char *constraint;
      tree val, type;
      rtx op;

      constraint = constraints[i + noutputs];
      if (! parse_input_constraint (&constraint, i, ninputs, noutputs, ninout,
                                    constraints, &allows_mem, &allows_reg))
        abort ();

      generating_concat_p = 0;

      val = TREE_VALUE (tail);
      type = TREE_TYPE (val);
      op = expand_expr (val, NULL_RTX, VOIDmode,
                        (allows_mem && !allows_reg
                         ? EXPAND_MEMORY : EXPAND_NORMAL));

      /* Never pass a CONCAT to an ASM.  */
      if (GET_CODE (op) == CONCAT)
        op = force_reg (GET_MODE (op), op);
      else if (GET_CODE (op) == MEM)
        op = validize_mem (op);

      if (asm_operand_ok (op, constraint) <= 0)
        {
          if (allows_reg)
            op = force_reg (TYPE_MODE (type), op);
          else if (!allows_mem)
            warning ("asm operand %d probably doesn't match constraints",
                     i + noutputs);
          else if (GET_CODE (op) == MEM)
            {
              /* We won't recognize either volatile memory or memory
                 with a queued address as available a memory_operand
                 at this point.  Ignore it: clearly this *is* a memory.  */
            }
          else
            {
              warning ("use of memory input without lvalue in "
                       "asm operand %d is deprecated", i + noutputs);

              if (CONSTANT_P (op))
                {
                  rtx mem = force_const_mem (TYPE_MODE (type), op);
                  if (mem)
                    op = validize_mem (mem);
                  else
                    op = force_reg (TYPE_MODE (type), op);
                }
              if (GET_CODE (op) == REG
                  || GET_CODE (op) == SUBREG
                  || GET_CODE (op) == ADDRESSOF
                  || GET_CODE (op) == CONCAT)
                {
                  tree qual_type = build_qualified_type (type,
                                                         (TYPE_QUALS (type)
                                                          | TYPE_QUAL_CONST));
                  rtx memloc = assign_temp (qual_type, 1, 1, 1);
                  memloc = validize_mem (memloc);
                  emit_move_insn (memloc, op);
                  op = memloc;
                }
            }
        }

      generating_concat_p = old_generating_concat_p;
      ASM_OPERANDS_INPUT (body, i) = op;

      ASM_OPERANDS_INPUT_CONSTRAINT_EXP (body, i)
        = gen_rtx_ASM_INPUT (TYPE_MODE (type), constraints[i + noutputs]);

      if (decl_conflicts_with_clobbers_p (val, clobbered_regs))
        clobber_conflict_found = 1;
    }

  /* Protect all the operands from the queue now that they have all been
     evaluated.  */

  generating_concat_p = 0;

  for (i = 0; i < ninputs - ninout; i++)
    ASM_OPERANDS_INPUT (body, i)
      = protect_from_queue (ASM_OPERANDS_INPUT (body, i), 0);

  for (i = 0; i < noutputs; i++)
    output_rtx[i] = protect_from_queue (output_rtx[i], 1);

  /* For in-out operands, copy output rtx to input rtx.  */
  for (i = 0; i < ninout; i++)
    {
      int j = inout_opnum[i];
      char buffer[16];

      ASM_OPERANDS_INPUT (body, ninputs - ninout + i)
        = output_rtx[j];

      sprintf (buffer, "%d", j);
      ASM_OPERANDS_INPUT_CONSTRAINT_EXP (body, ninputs - ninout + i)
        = gen_rtx_ASM_INPUT (inout_mode[i], ggc_strdup (buffer));
    }

  generating_concat_p = old_generating_concat_p;

  /* Now, for each output, construct an rtx
     (set OUTPUT (asm_operands INSN OUTPUTCONSTRAINT OUTPUTNUMBER
                               ARGVEC CONSTRAINTS OPNAMES))
     If there is more than one, put them inside a PARALLEL.  */

  if (noutputs == 1 && nclobbers == 0)
    {
      ASM_OPERANDS_OUTPUT_CONSTRAINT (body) = constraints[0];
      emit_insn (gen_rtx_SET (VOIDmode, output_rtx[0], body));
    }

  else if (noutputs == 0 && nclobbers == 0)
    {
      /* No output operands: put in a raw ASM_OPERANDS rtx.  */
      emit_insn (body);
    }

  else
    {
      rtx obody = body;
      int num = noutputs;

      if (num == 0)
        num = 1;

      body = gen_rtx_PARALLEL (VOIDmode, rtvec_alloc (num + nclobbers));

      /* For each output operand, store a SET.  */
      for (i = 0, tail = outputs; tail; tail = TREE_CHAIN (tail), i++)
        {
          XVECEXP (body, 0, i)
            = gen_rtx_SET (VOIDmode,
                           output_rtx[i],
                           gen_rtx_ASM_OPERANDS
                           (GET_MODE (output_rtx[i]),
                            TREE_STRING_POINTER (string),
                            constraints[i], i, argvec, constraintvec,
                            locus.file, locus.line));

          MEM_VOLATILE_P (SET_SRC (XVECEXP (body, 0, i))) = vol;
        }

      /* If there are no outputs (but there are some clobbers)
         store the bare ASM_OPERANDS into the PARALLEL.  */

      if (i == 0)
        XVECEXP (body, 0, i++) = obody;

      /* Store (clobber REG) for each clobbered register specified.  */

      for (tail = clobbers; tail; tail = TREE_CHAIN (tail))
        {
          const char *regname = TREE_STRING_POINTER (TREE_VALUE (tail));
          int j = decode_reg_name (regname);
          rtx clobbered_reg;

          if (j < 0)
            {
              if (j == -3)      /* `cc', which is not a register */
                continue;

              if (j == -4)      /* `memory', don't cache memory across asm */
                {
                  XVECEXP (body, 0, i++)
                    = gen_rtx_CLOBBER (VOIDmode,
                                       gen_rtx_MEM
                                       (BLKmode,
                                        gen_rtx_SCRATCH (VOIDmode)));
                  continue;
                }

              /* Ignore unknown register, error already signaled.  */
              continue;
            }

          /* Use QImode since that's guaranteed to clobber just one reg.  */
          clobbered_reg = gen_rtx_REG (QImode, j);

          /* Do sanity check for overlap between clobbers and respectively
             input and outputs that hasn't been handled.  Such overlap
             should have been detected and reported above.  */
          if (!clobber_conflict_found)
            {
              int opno;

              /* We test the old body (obody) contents to avoid tripping
                 over the under-construction body.  */
              for (opno = 0; opno < noutputs; opno++)
                if (reg_overlap_mentioned_p (clobbered_reg, output_rtx[opno]))
                  internal_error ("asm clobber conflict with output operand");

              for (opno = 0; opno < ninputs - ninout; opno++)
                if (reg_overlap_mentioned_p (clobbered_reg,
                                             ASM_OPERANDS_INPUT (obody, opno)))
                  internal_error ("asm clobber conflict with input operand");
            }

          XVECEXP (body, 0, i++)
            = gen_rtx_CLOBBER (VOIDmode, clobbered_reg);
        }

      emit_insn (body);
    }

  /* For any outputs that needed reloading into registers, spill them
     back to where they belong.  */
  for (i = 0; i < noutputs; ++i)
    if (real_output_rtx[i])
      emit_move_insn (real_output_rtx[i], output_rtx[i]);

  free_temp_slots ();
}

/* A subroutine of expand_asm_operands.  Check that all operands have
   the same number of alternatives.  Return true if so.  */

static bool
check_operand_nalternatives (tree outputs, tree inputs)
{
  if (outputs || inputs)
    {
      tree tmp = TREE_PURPOSE (outputs ? outputs : inputs);
      int nalternatives
        = n_occurrences (',', TREE_STRING_POINTER (TREE_VALUE (tmp)));
      tree next = inputs;

      if (nalternatives + 1 > MAX_RECOG_ALTERNATIVES)
        {
          error ("too many alternatives in `asm'");
          return false;
        }

      tmp = outputs;
      while (tmp)
        {
          const char *constraint
            = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (tmp)));

          if (n_occurrences (',', constraint) != nalternatives)
            {
              error ("operand constraints for `asm' differ in number of alternatives");
              return false;
            }

          if (TREE_CHAIN (tmp))
            tmp = TREE_CHAIN (tmp);
          else
            tmp = next, next = 0;
        }
    }

  return true;
}

/* A subroutine of expand_asm_operands.  Check that all operand names
   are unique.  Return true if so.  We rely on the fact that these names
   are identifiers, and so have been canonicalized by get_identifier,
   so all we need are pointer comparisons.  */

static bool
check_unique_operand_names (tree outputs, tree inputs)
{
  tree i, j;

  for (i = outputs; i ; i = TREE_CHAIN (i))
    {
      tree i_name = TREE_PURPOSE (TREE_PURPOSE (i));
      if (! i_name)
        continue;

      for (j = TREE_CHAIN (i); j ; j = TREE_CHAIN (j))
        if (simple_cst_equal (i_name, TREE_PURPOSE (TREE_PURPOSE (j))))
          goto failure;
    }

  for (i = inputs; i ; i = TREE_CHAIN (i))
    {
      tree i_name = TREE_PURPOSE (TREE_PURPOSE (i));
      if (! i_name)
        continue;

      for (j = TREE_CHAIN (i); j ; j = TREE_CHAIN (j))
        if (simple_cst_equal (i_name, TREE_PURPOSE (TREE_PURPOSE (j))))
          goto failure;
      for (j = outputs; j ; j = TREE_CHAIN (j))
        if (simple_cst_equal (i_name, TREE_PURPOSE (TREE_PURPOSE (j))))
          goto failure;
    }

  return true;

 failure:
  error ("duplicate asm operand name '%s'",
         TREE_STRING_POINTER (TREE_PURPOSE (TREE_PURPOSE (i))));
  return false;
}

/* A subroutine of expand_asm_operands.  Resolve the names of the operands
   in *POUTPUTS and *PINPUTS to numbers, and replace the name expansions in
   STRING and in the constraints to those numbers.  */

tree
resolve_asm_operand_names (tree string, tree outputs, tree inputs)
{
  char *buffer;
  char *p;
  const char *c;
  tree t;

  check_unique_operand_names (outputs, inputs);

  /* Substitute [<name>] in input constraint strings.  There should be no
     named operands in output constraints.  */
  for (t = inputs; t ; t = TREE_CHAIN (t))
    {
      c = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (t)));
      if (strchr (c, '[') != NULL)
        {
          p = buffer = xstrdup (c);
          while ((p = strchr (p, '[')) != NULL)
            p = resolve_operand_name_1 (p, outputs, inputs);
          TREE_VALUE (TREE_PURPOSE (t))
            = build_string (strlen (buffer), buffer);
          free (buffer);
        }
    }

  /* Now check for any needed substitutions in the template.  */
  c = TREE_STRING_POINTER (string);
  while ((c = strchr (c, '%')) != NULL)
    {
      if (c[1] == '[')
        break;
      else if (ISALPHA (c[1]) && c[2] == '[')
        break;
      else
        {
          c += 1;
          continue;
        }
    }

  if (c)
    {
      /* OK, we need to make a copy so we can perform the substitutions.
         Assume that we will not need extra space--we get to remove '['
         and ']', which means we cannot have a problem until we have more
         than 999 operands.  */
      buffer = xstrdup (TREE_STRING_POINTER (string));
      p = buffer + (c - TREE_STRING_POINTER (string));
      
      while ((p = strchr (p, '%')) != NULL)
        {
          if (p[1] == '[')
            p += 1;
          else if (ISALPHA (p[1]) && p[2] == '[')
            p += 2;
          else
            {
              p += 1;
              continue;
            }

          p = resolve_operand_name_1 (p, outputs, inputs);
        }

      string = build_string (strlen (buffer), buffer);
      free (buffer);
    }

  return string;
}

/* A subroutine of resolve_operand_names.  P points to the '[' for a
   potential named operand of the form [<name>].  In place, replace
   the name and brackets with a number.  Return a pointer to the
   balance of the string after substitution.  */

static char *
resolve_operand_name_1 (char *p, tree outputs, tree inputs)
{
  char *q;
  int op;
  tree t;
  size_t len;

  /* Collect the operand name.  */
  q = strchr (p, ']');
  if (!q)
    {
      error ("missing close brace for named operand");
      return strchr (p, '\0');
    }
  len = q - p - 1;

  /* Resolve the name to a number.  */
  for (op = 0, t = outputs; t ; t = TREE_CHAIN (t), op++)
    {
      tree name = TREE_PURPOSE (TREE_PURPOSE (t));
      if (name)
        {
          const char *c = TREE_STRING_POINTER (name);
          if (strncmp (c, p + 1, len) == 0 && c[len] == '\0')
            goto found;
        }
    }
  for (t = inputs; t ; t = TREE_CHAIN (t), op++)
    {
      tree name = TREE_PURPOSE (TREE_PURPOSE (t));
      if (name)
        {
          const char *c = TREE_STRING_POINTER (name);
          if (strncmp (c, p + 1, len) == 0 && c[len] == '\0')
            goto found;
        }
    }

  *q = '\0';
  error ("undefined named operand '%s'", p + 1);
  op = 0;
 found:

  /* Replace the name with the number.  Unfortunately, not all libraries
     get the return value of sprintf correct, so search for the end of the
     generated string by hand.  */
  sprintf (p, "%d", op);
  p = strchr (p, '\0');

  /* Verify the no extra buffer space assumption.  */
  if (p > q)
    abort ();

  /* Shift the rest of the buffer down to fill the gap.  */
  memmove (p, q + 1, strlen (q + 1) + 1);

  return p;
}
\f
/* Generate RTL to evaluate the expression EXP
   and remember it in case this is the VALUE in a ({... VALUE; }) constr.
   Provided just for backward-compatibility.  expand_expr_stmt_value()
   should be used for new code.  */

void
expand_expr_stmt (tree exp)
{
  expand_expr_stmt_value (exp, -1, 1);
}

/* Generate RTL to evaluate the expression EXP.  WANT_VALUE tells
   whether to (1) save the value of the expression, (0) discard it or
   (-1) use expr_stmts_for_value to tell.  The use of -1 is
   deprecated, and retained only for backward compatibility.  */

void
expand_expr_stmt_value (tree exp, int want_value, int maybe_last)
{
  rtx value;
  tree type;
  rtx alt_rtl = NULL;

  if (want_value == -1)
    want_value = expr_stmts_for_value != 0;

  /* If -Wextra, warn about statements with no side effects,
     except for an explicit cast to void (e.g. for assert()), and
     except for last statement in ({...}) where they may be useful.  */
  if (! want_value
      && (expr_stmts_for_value == 0 || ! maybe_last)
      && exp != error_mark_node
      && warn_unused_value)
    {
      if (TREE_SIDE_EFFECTS (exp))
        warn_if_unused_value (exp);
      else if (!VOID_TYPE_P (TREE_TYPE (exp)))
        warning ("%Hstatement with no effect", &emit_locus);
    }

  /* If EXP is of function type and we are expanding statements for
     value, convert it to pointer-to-function.  */
  if (want_value && TREE_CODE (TREE_TYPE (exp)) == FUNCTION_TYPE)
    exp = build1 (ADDR_EXPR, build_pointer_type (TREE_TYPE (exp)), exp);

  /* The call to `expand_expr' could cause last_expr_type and
     last_expr_value to get reset.  Therefore, we set last_expr_value
     and last_expr_type *after* calling expand_expr.  */
  value = expand_expr_real (exp, want_value ? NULL_RTX : const0_rtx,
                            VOIDmode, 0, &alt_rtl);
  type = TREE_TYPE (exp);

  /* If all we do is reference a volatile value in memory,
     copy it to a register to be sure it is actually touched.  */
  if (value && GET_CODE (value) == MEM && TREE_THIS_VOLATILE (exp))
    {
      if (TYPE_MODE (type) == VOIDmode)
        ;
      else if (TYPE_MODE (type) != BLKmode)
        value = copy_to_reg (value);
      else
        {
          rtx lab = gen_label_rtx ();

          /* Compare the value with itself to reference it.  */
          emit_cmp_and_jump_insns (value, value, EQ,
                                   expand_expr (TYPE_SIZE (type),
                                                NULL_RTX, VOIDmode, 0),
                                   BLKmode, 0, lab);
          emit_label (lab);
        }
    }

  /* If this expression is part of a ({...}) and is in memory, we may have
     to preserve temporaries.  */
  preserve_temp_slots (value);

  /* Free any temporaries used to evaluate this expression.  Any temporary
     used as a result of this expression will already have been preserved
     above.  */
  free_temp_slots ();

  if (want_value)
    {
      last_expr_value = value;
      last_expr_alt_rtl = alt_rtl;
      last_expr_type = type;
    }

  emit_queue ();
}

/* Warn if EXP contains any computations whose results are not used.
   Return 1 if a warning is printed; 0 otherwise.  */

int
warn_if_unused_value (tree exp)
{
  if (TREE_USED (exp))
    return 0;

  /* Don't warn about void constructs.  This includes casting to void,
     void function calls, and statement expressions with a final cast
     to void.  */
  if (VOID_TYPE_P (TREE_TYPE (exp)))
    return 0;

  switch (TREE_CODE (exp))
    {
    case PREINCREMENT_EXPR:
    case POSTINCREMENT_EXPR:
    case PREDECREMENT_EXPR:
    case POSTDECREMENT_EXPR:
    case MODIFY_EXPR:
    case INIT_EXPR:
    case TARGET_EXPR:
    case CALL_EXPR:
    case RTL_EXPR:
    case TRY_CATCH_EXPR:
    case WITH_CLEANUP_EXPR:
    case EXIT_EXPR:
      return 0;

    case BIND_EXPR:
      /* For a binding, warn if no side effect within it.  */
      return warn_if_unused_value (TREE_OPERAND (exp, 1));

    case SAVE_EXPR:
      return warn_if_unused_value (TREE_OPERAND (exp, 1));

    case TRUTH_ORIF_EXPR:
    case TRUTH_ANDIF_EXPR:
      /* In && or ||, warn if 2nd operand has no side effect.  */
      return warn_if_unused_value (TREE_OPERAND (exp, 1));

    case COMPOUND_EXPR:
      if (TREE_NO_UNUSED_WARNING (exp))
        return 0;
      if (warn_if_unused_value (TREE_OPERAND (exp, 0)))
        return 1;
      /* Let people do `(foo (), 0)' without a warning.  */
      if (TREE_CONSTANT (TREE_OPERAND (exp, 1)))
        return 0;
      return warn_if_unused_value (TREE_OPERAND (exp, 1));

    case NOP_EXPR:
    case CONVERT_EXPR:
    case NON_LVALUE_EXPR:
      /* Don't warn about conversions not explicit in the user's program.  */
      if (TREE_NO_UNUSED_WARNING (exp))
        return 0;
      /* Assignment to a cast usually results in a cast of a modify.
         Don't complain about that.  There can be an arbitrary number of
         casts before the modify, so we must loop until we find the first
         non-cast expression and then test to see if that is a modify.  */
      {
        tree tem = TREE_OPERAND (exp, 0);

        while (TREE_CODE (tem) == CONVERT_EXPR || TREE_CODE (tem) == NOP_EXPR)
          tem = TREE_OPERAND (tem, 0);

        if (TREE_CODE (tem) == MODIFY_EXPR || TREE_CODE (tem) == INIT_EXPR
            || TREE_CODE (tem) == CALL_EXPR)
          return 0;
      }
      goto maybe_warn;

    case INDIRECT_REF:
      /* Don't warn about automatic dereferencing of references, since
         the user cannot control it.  */
      if (TREE_CODE (TREE_TYPE (TREE_OPERAND (exp, 0))) == REFERENCE_TYPE)
        return warn_if_unused_value (TREE_OPERAND (exp, 0));
      /* Fall through.  */

    default:
      /* Referencing a volatile value is a side effect, so don't warn.  */
      if ((DECL_P (exp)
           || TREE_CODE_CLASS (TREE_CODE (exp)) == 'r')
          && TREE_THIS_VOLATILE (exp))
        return 0;

      /* If this is an expression which has no operands, there is no value
         to be unused.  There are no such language-independent codes,
         but front ends may define such.  */
      if (TREE_CODE_CLASS (TREE_CODE (exp)) == 'e'
          && TREE_CODE_LENGTH (TREE_CODE (exp)) == 0)
        return 0;

    maybe_warn:
      /* If this is an expression with side effects, don't warn.  */
      if (TREE_SIDE_EFFECTS (exp))
        return 0;

      warning ("%Hvalue computed is not used", &emit_locus);
      return 1;
    }
}

/* Clear out the memory of the last expression evaluated.  */

void
clear_last_expr (void)
{
  last_expr_type = NULL_TREE;
  last_expr_value = NULL_RTX;
  last_expr_alt_rtl = NULL_RTX;
}

/* Begin a statement-expression, i.e., a series of statements which
   may return a value.  Return the RTL_EXPR for this statement expr.
   The caller must save that value and pass it to
   expand_end_stmt_expr.  If HAS_SCOPE is nonzero, temporaries created
   in the statement-expression are deallocated at the end of the
   expression.  */

tree
expand_start_stmt_expr (int has_scope)
{
  tree t;

  /* Make the RTL_EXPR node temporary, not momentary,
     so that rtl_expr_chain doesn't become garbage.  */
  t = make_node (RTL_EXPR);
  do_pending_stack_adjust ();
  if (has_scope)
    start_sequence_for_rtl_expr (t);
  else
    start_sequence ();
  NO_DEFER_POP;
  expr_stmts_for_value++;
  return t;
}

/* Restore the previous state at the end of a statement that returns a value.
   Returns a tree node representing the statement's value and the
   insns to compute the value.

   The nodes of that expression have been freed by now, so we cannot use them.
   But we don't want to do that anyway; the expression has already been
   evaluated and now we just want to use the value.  So generate a RTL_EXPR
   with the proper type and RTL value.

   If the last substatement was not an expression,
   return something with type `void'.  */

tree
expand_end_stmt_expr (tree t)
{
  OK_DEFER_POP;

  if (! last_expr_value || ! last_expr_type)
    {
      last_expr_value = const0_rtx;
      last_expr_alt_rtl = NULL_RTX;
      last_expr_type = void_type_node;
    }
  else if (GET_CODE (last_expr_value) != REG && ! CONSTANT_P (last_expr_value))
    /* Remove any possible QUEUED.  */
    last_expr_value = protect_from_queue (last_expr_value, 0);

  emit_queue ();

  TREE_TYPE (t) = last_expr_type;
  RTL_EXPR_RTL (t) = last_expr_value;
  RTL_EXPR_ALT_RTL (t) = last_expr_alt_rtl;
  RTL_EXPR_SEQUENCE (t) = get_insns ();

  rtl_expr_chain = tree_cons (NULL_TREE, t, rtl_expr_chain);

  end_sequence ();

  /* Don't consider deleting this expr or containing exprs at tree level.  */
  TREE_SIDE_EFFECTS (t) = 1;
  /* Propagate volatility of the actual RTL expr.  */
  TREE_THIS_VOLATILE (t) = volatile_refs_p (last_expr_value);

  clear_last_expr ();
  expr_stmts_for_value--;

  return t;
}
\f
/* Generate RTL for the start of an if-then.  COND is the expression
   whose truth should be tested.

   If EXITFLAG is nonzero, this conditional is visible to
   `exit_something'.  */

void
expand_start_cond (tree cond, int exitflag)
{
  struct nesting *thiscond = ALLOC_NESTING ();

  /* Make an entry on cond_stack for the cond we are entering.  */

  thiscond->desc = COND_NESTING;
  thiscond->next = cond_stack;
  thiscond->all = nesting_stack;
  thiscond->depth = ++nesting_depth;
  thiscond->data.cond.next_label = gen_label_rtx ();
  /* Before we encounter an `else', we don't need a separate exit label
     unless there are supposed to be exit statements
     to exit this conditional.  */
  thiscond->exit_label = exitflag ? gen_label_rtx () : 0;
  thiscond->data.cond.endif_label = thiscond->exit_label;
  cond_stack = thiscond;
  nesting_stack = thiscond;

  do_jump (cond, thiscond->data.cond.next_label, NULL_RTX);
}

/* Generate RTL between then-clause and the elseif-clause
   of an if-then-elseif-....  */

void
expand_start_elseif (tree cond)
{
  if (cond_stack->data.cond.endif_label == 0)
    cond_stack->data.cond.endif_label = gen_label_rtx ();
  emit_jump (cond_stack->data.cond.endif_label);
  emit_label (cond_stack->data.cond.next_label);
  cond_stack->data.cond.next_label = gen_label_rtx ();
  do_jump (cond, cond_stack->data.cond.next_label, NULL_RTX);
}

/* Generate RTL between the then-clause and the else-clause
   of an if-then-else.  */

void
expand_start_else (void)
{
  if (cond_stack->data.cond.endif_label == 0)
    cond_stack->data.cond.endif_label = gen_label_rtx ();

  emit_jump (cond_stack->data.cond.endif_label);
  emit_label (cond_stack->data.cond.next_label);
  cond_stack->data.cond.next_label = 0;  /* No more _else or _elseif calls.  */
}

/* After calling expand_start_else, turn this "else" into an "else if"
   by providing another condition.  */

void
expand_elseif (tree cond)
{
  cond_stack->data.cond.next_label = gen_label_rtx ();
  do_jump (cond, cond_stack->data.cond.next_label, NULL_RTX);
}

/* Generate RTL for the end of an if-then.
   Pop the record for it off of cond_stack.  */

void
expand_end_cond (void)
{
  struct nesting *thiscond = cond_stack;

  do_pending_stack_adjust ();
  if (thiscond->data.cond.next_label)
    emit_label (thiscond->data.cond.next_label);
  if (thiscond->data.cond.endif_label)
    emit_label (thiscond->data.cond.endif_label);

  POPSTACK (cond_stack);
  clear_last_expr ();
}
\f
/* Generate RTL for the start of a loop.  EXIT_FLAG is nonzero if this
   loop should be exited by `exit_something'.  This is a loop for which
   `expand_continue' will jump to the top of the loop.

   Make an entry on loop_stack to record the labels associated with
   this loop.  */

struct nesting *
expand_start_loop (int exit_flag)
{
  struct nesting *thisloop = ALLOC_NESTING ();

  /* Make an entry on loop_stack for the loop we are entering.  */

  thisloop->desc = LOOP_NESTING;
  thisloop->next = loop_stack;
  thisloop->all = nesting_stack;
  thisloop->depth = ++nesting_depth;
  thisloop->data.loop.start_label = gen_label_rtx ();
  thisloop->data.loop.end_label = gen_label_rtx ();
  thisloop->data.loop.continue_label = thisloop->data.loop.start_label;
  thisloop->exit_label = exit_flag ? thisloop->data.loop.end_label : 0;
  loop_stack = thisloop;
  nesting_stack = thisloop;

  do_pending_stack_adjust ();
  emit_queue ();
  emit_note (NOTE_INSN_LOOP_BEG);
  emit_label (thisloop->data.loop.start_label);

  return thisloop;
}

/* Like expand_start_loop but for a loop where the continuation point
   (for expand_continue_loop) will be specified explicitly.  */

struct nesting *
expand_start_loop_continue_elsewhere (int exit_flag)
{
  struct nesting *thisloop = expand_start_loop (exit_flag);
  loop_stack->data.loop.continue_label = gen_label_rtx ();
  return thisloop;
}

/* Begin a null, aka do { } while (0) "loop".  But since the contents
   of said loop can still contain a break, we must frob the loop nest.  */

struct nesting *
expand_start_null_loop (void)
{
  struct nesting *thisloop = ALLOC_NESTING ();

  /* Make an entry on loop_stack for the loop we are entering.  */

  thisloop->desc = LOOP_NESTING;
  thisloop->next = loop_stack;
  thisloop->all = nesting_stack;
  thisloop->depth = ++nesting_depth;
  thisloop->data.loop.start_label = emit_note (NOTE_INSN_DELETED);
  thisloop->data.loop.end_label = gen_label_rtx ();
  thisloop->data.loop.continue_label = thisloop->data.loop.end_label;
  thisloop->exit_label = thisloop->data.loop.end_label;
  loop_stack = thisloop;
  nesting_stack = thisloop;

  return thisloop;
}

/* Specify the continuation point for a loop started with
   expand_start_loop_continue_elsewhere.
   Use this at the point in the code to which a continue statement
   should jump.  */

void
expand_loop_continue_here (void)
{
  do_pending_stack_adjust ();
  emit_note (NOTE_INSN_LOOP_CONT);
  emit_label (loop_stack->data.loop.continue_label);
}

/* Finish a loop.  Generate a jump back to the top and the loop-exit label.
   Pop the block off of loop_stack.  */

void
expand_end_loop (void)
{
  rtx start_label = loop_stack->data.loop.start_label;
  rtx etc_note;
  int eh_regions, debug_blocks;
  bool empty_test;

  /* Mark the continue-point at the top of the loop if none elsewhere.  */
  if (start_label == loop_stack->data.loop.continue_label)
    emit_note_before (NOTE_INSN_LOOP_CONT, start_label);

  do_pending_stack_adjust ();

  /* If the loop starts with a loop exit, roll that to the end where
     it will optimize together with the jump back.

     If the loop presently looks like this (in pseudo-C):

        LOOP_BEG
        start_label:
          if (test) goto end_label;
        LOOP_END_TOP_COND
          body;
          goto start_label;
        end_label:

     transform it to look like:

        LOOP_BEG
          goto start_label;
        top_label:
          body;
        start_label:
          if (test) goto end_label;
          goto top_label;
        end_label:

     We rely on the presence of NOTE_INSN_LOOP_END_TOP_COND to mark
     the end of the entry conditional.  Without this, our lexical scan
     can't tell the difference between an entry conditional and a
     body conditional that exits the loop.  Mistaking the two means
     that we can misplace the NOTE_INSN_LOOP_CONT note, which can
     screw up loop unrolling.

     Things will be oh so much better when loop optimization is done
     off of a proper control flow graph...  */

  /* Scan insns from the top of the loop looking for the END_TOP_COND note.  */

  empty_test = true;
  eh_regions = debug_blocks = 0;
  for (etc_note = start_label; etc_note ; etc_note = NEXT_INSN (etc_note))
    if (GET_CODE (etc_note) == NOTE)
      {
        if (NOTE_LINE_NUMBER (etc_note) == NOTE_INSN_LOOP_END_TOP_COND)
          break;

        /* We must not walk into a nested loop.  */
        else if (NOTE_LINE_NUMBER (etc_note) == NOTE_INSN_LOOP_BEG)
          {
            etc_note = NULL_RTX;
            break;
          }

        /* At the same time, scan for EH region notes, as we don't want
           to scrog region nesting.  This shouldn't happen, but...  */
        else if (NOTE_LINE_NUMBER (etc_note) == NOTE_INSN_EH_REGION_BEG)
          eh_regions++;
        else if (NOTE_LINE_NUMBER (etc_note) == NOTE_INSN_EH_REGION_END)
          {
            if (--eh_regions < 0)
              /* We've come to the end of an EH region, but never saw the
                 beginning of that region.  That means that an EH region
                 begins before the top of the loop, and ends in the middle
                 of it.  The existence of such a situation violates a basic
                 assumption in this code, since that would imply that even
                 when EH_REGIONS is zero, we might move code out of an
                 exception region.  */
              abort ();
          }

        /* Likewise for debug scopes.  In this case we'll either (1) move
           all of the notes if they are properly nested or (2) leave the
           notes alone and only rotate the loop at high optimization
           levels when we expect to scrog debug info.  */
        else if (NOTE_LINE_NUMBER (etc_note) == NOTE_INSN_BLOCK_BEG)
          debug_blocks++;
        else if (NOTE_LINE_NUMBER (etc_note) == NOTE_INSN_BLOCK_END)
          debug_blocks--;
      }
    else if (INSN_P (etc_note))
      empty_test = false;

  if (etc_note
      && optimize
      && ! empty_test
      && eh_regions == 0
      && (debug_blocks == 0 || optimize >= 2)
      && NEXT_INSN (etc_note) != NULL_RTX
      && ! any_condjump_p (get_last_insn ()))
    {
      /* We found one.  Move everything from START to ETC to the end
         of the loop, and add a jump from the top of the loop.  */
      rtx top_label = gen_label_rtx ();
      rtx start_move = start_label;

      /* If the start label is preceded by a NOTE_INSN_LOOP_CONT note,
         then we want to move this note also.  */
      if (GET_CODE (PREV_INSN (start_move)) == NOTE
          && NOTE_LINE_NUMBER (PREV_INSN (start_move)) == NOTE_INSN_LOOP_CONT)
        start_move = PREV_INSN (start_move);

      emit_label_before (top_label, start_move);

      /* Actually move the insns.  If the debug scopes are nested, we
         can move everything at once.  Otherwise we have to move them
         one by one and squeeze out the block notes.  */
      if (debug_blocks == 0)
        reorder_insns (start_move, etc_note, get_last_insn ());
      else
        {
          rtx insn, next_insn;
          for (insn = start_move; insn; insn = next_insn)
            {
              /* Figure out which insn comes after this one.  We have
                 to do this before we move INSN.  */
              next_insn = (insn == etc_note ? NULL : NEXT_INSN (insn));

              if (GET_CODE (insn) == NOTE
                  && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_BEG
                      || NOTE_LINE_NUMBER (insn) == NOTE_INSN_BLOCK_END))
                continue;

              reorder_insns (insn, insn, get_last_insn ());
            }
        }

      /* Add the jump from the top of the loop.  */
      emit_jump_insn_before (gen_jump (start_label), top_label);
      emit_barrier_before (top_label);
      start_label = top_label;
    }

  emit_jump (start_label);
  emit_note (NOTE_INSN_LOOP_END);
  emit_label (loop_stack->data.loop.end_label);

  POPSTACK (loop_stack);

  clear_last_expr ();
}

/* Finish a null loop, aka do { } while (0).  */

void
expand_end_null_loop (void)
{
  do_pending_stack_adjust ();
  emit_label (loop_stack->data.loop.end_label);

  POPSTACK (loop_stack);

  clear_last_expr ();
}

/* Generate a jump to the current loop's continue-point.
   This is usually the top of the loop, but may be specified
   explicitly elsewhere.  If not currently inside a loop,
   return 0 and do nothing; caller will print an error message.  */

int
expand_continue_loop (struct nesting *whichloop)
{
  /* Emit information for branch prediction.  */
  rtx note;

  if (flag_guess_branch_prob)
    {
      note = emit_note (NOTE_INSN_PREDICTION);
      NOTE_PREDICTION (note) = NOTE_PREDICT (PRED_CONTINUE, IS_TAKEN);
    }
  clear_last_expr ();
  if (whichloop == 0)
    whichloop = loop_stack;
  if (whichloop == 0)
    return 0;
  expand_goto_internal (NULL_TREE, whichloop->data.loop.continue_label,
                        NULL_RTX);
  return 1;
}

/* Generate a jump to exit the current loop.  If not currently inside a loop,
   return 0 and do nothing; caller will print an error message.  */

int
expand_exit_loop (struct nesting *whichloop)
{
  clear_last_expr ();
  if (whichloop == 0)
    whichloop = loop_stack;
  if (whichloop == 0)
    return 0;
  expand_goto_internal (NULL_TREE, whichloop->data.loop.end_label, NULL_RTX);
  return 1;
}

/* Generate a conditional jump to exit the current loop if COND
   evaluates to zero.  If not currently inside a loop,
   return 0 and do nothing; caller will print an error message.  */

int
expand_exit_loop_if_false (struct nesting *whichloop, tree cond)
{
  rtx label;
  clear_last_expr ();

  if (whichloop == 0)
    whichloop = loop_stack;
  if (whichloop == 0)
    return 0;

  if (integer_nonzerop (cond))
    return 1;
  if (integer_zerop (cond))
    return expand_exit_loop (whichloop);

  /* Check if we definitely won't need a fixup.  */
  if (whichloop == nesting_stack)
    {
      jumpifnot (cond, whichloop->data.loop.end_label);
      return 1;
    }

  /* In order to handle fixups, we actually create a conditional jump
     around an unconditional branch to exit the loop.  If fixups are
     necessary, they go before the unconditional branch.  */

  label = gen_label_rtx ();
  jumpif (cond, label);
  expand_goto_internal (NULL_TREE, whichloop->data.loop.end_label,
                        NULL_RTX);
  emit_label (label);

  return 1;
}

/* Like expand_exit_loop_if_false except also emit a note marking
   the end of the conditional.  Should only be used immediately
   after expand_loop_start.  */

int
expand_exit_loop_top_cond (struct nesting *whichloop, tree cond)
{
  if (! expand_exit_loop_if_false (whichloop, cond))
    return 0;

  emit_note (NOTE_INSN_LOOP_END_TOP_COND);
  return 1;
}

/* Return nonzero if we should preserve sub-expressions as separate
   pseudos.  We never do so if we aren't optimizing.  We always do so
   if -fexpensive-optimizations.

   Otherwise, we only do so if we are in the "early" part of a loop.  I.e.,
   the loop may still be a small one.  */

int
preserve_subexpressions_p (void)
{
  rtx insn;

  if (flag_expensive_optimizations)
    return 1;

  if (optimize == 0 || cfun == 0 || cfun->stmt == 0 || loop_stack == 0)
    return 0;

  insn = get_last_insn_anywhere ();

  return (insn
          && (INSN_UID (insn) - INSN_UID (loop_stack->data.loop.start_label)
              < n_non_fixed_regs * 3));

}

/* Generate a jump to exit the current loop, conditional, binding contour
   or case statement.  Not all such constructs are visible to this function,
   only those started with EXIT_FLAG nonzero.  Individual languages use
   the EXIT_FLAG parameter to control which kinds of constructs you can
   exit this way.

   If not currently inside anything that can be exited,
   return 0 and do nothing; caller will print an error message.  */

int
expand_exit_something (void)
{
  struct nesting *n;
  clear_last_expr ();
  for (n = nesting_stack; n; n = n->all)
    if (n->exit_label != 0)
      {
        expand_goto_internal (NULL_TREE, n->exit_label, NULL_RTX);
        return 1;
      }

  return 0;
}
\f
/* Generate RTL to return from the current function, with no value.
   (That is, we do not do anything about returning any value.)  */

void
expand_null_return (void)
{
  rtx last_insn;

  last_insn = get_last_insn ();

  /* If this function was declared to return a value, but we
     didn't, clobber the return registers so that they are not
     propagated live to the rest of the function.  */
  clobber_return_register ();

  expand_null_return_1 (last_insn);
}

/* Generate RTL to return directly from the current function.
   (That is, we bypass any return value.)  */

void
expand_naked_return (void)
{
  rtx last_insn, end_label;

  last_insn = get_last_insn ();
  end_label = naked_return_label;

  clear_pending_stack_adjust ();
  do_pending_stack_adjust ();
  clear_last_expr ();

  if (end_label == 0)
    end_label = naked_return_label = gen_label_rtx ();
  expand_goto_internal (NULL_TREE, end_label, last_insn);
}

/* Try to guess whether the value of return means error code.  */
static enum br_predictor
return_prediction (rtx val)
{
  /* Different heuristics for pointers and scalars.  */
  if (POINTER_TYPE_P (TREE_TYPE (DECL_RESULT (current_function_decl))))
    {
      /* NULL is usually not returned.  */
      if (val == const0_rtx)
        return PRED_NULL_RETURN;
    }
  else
    {
      /* Negative return values are often used to indicate
         errors.  */
      if (GET_CODE (val) == CONST_INT
          && INTVAL (val) < 0)
        return PRED_NEGATIVE_RETURN;
      /* Constant return values are also usually erors,
         zero/one often mean booleans so exclude them from the
         heuristics.  */
      if (CONSTANT_P (val)
          && (val != const0_rtx && val != const1_rtx))
        return PRED_CONST_RETURN;
    }
  return PRED_NO_PREDICTION;
}


/* If the current function returns values in the most significant part
   of a register, shift return value VAL appropriately.  The mode of
   the function's return type is known not to be BLKmode.  */

static rtx
shift_return_value (rtx val)
{
  tree type;

  type = TREE_TYPE (DECL_RESULT (current_function_decl));
  if (targetm.calls.return_in_msb (type))
    {
      rtx target;
      HOST_WIDE_INT shift;

      target = DECL_RTL (DECL_RESULT (current_function_decl));
      shift = (GET_MODE_BITSIZE (GET_MODE (target))
               - BITS_PER_UNIT * int_size_in_bytes (type));
      if (shift > 0)
        val = expand_binop (GET_MODE (target), ashl_optab,
                            gen_lowpart (GET_MODE (target), val),
                            GEN_INT (shift), target, 1, OPTAB_WIDEN);
    }
  return val;
}


/* Generate RTL to return from the current function, with value VAL.  */

static void
expand_value_return (rtx val)
{
  rtx last_insn;
  rtx return_reg;
  enum br_predictor pred;

  if (flag_guess_branch_prob
      && (pred = return_prediction (val)) != PRED_NO_PREDICTION)
    {
      /* Emit information for branch prediction.  */
      rtx note;

      note = emit_note (NOTE_INSN_PREDICTION);

      NOTE_PREDICTION (note) = NOTE_PREDICT (pred, NOT_TAKEN);

    }

  last_insn = get_last_insn ();
  return_reg = DECL_RTL (DECL_RESULT (current_function_decl));

  /* Copy the value to the return location
     unless it's already there.  */

  if (return_reg != val)
    {
      tree type = TREE_TYPE (DECL_RESULT (current_function_decl));
      if (targetm.calls.promote_function_return (TREE_TYPE (current_function_decl)))
      {
        int unsignedp = TREE_UNSIGNED (type);
        enum machine_mode old_mode
          = DECL_MODE (DECL_RESULT (current_function_decl));
        enum machine_mode mode
          = promote_mode (type, old_mode, &unsignedp, 1);

        if (mode != old_mode)
          val = convert_modes (mode, old_mode, val, unsignedp);
      }
      if (GET_CODE (return_reg) == PARALLEL)
        emit_group_load (return_reg, val, type, int_size_in_bytes (type));
      else
        emit_move_insn (return_reg, val);
    }

  expand_null_return_1 (last_insn);
}

/* Output a return with no value.  If LAST_INSN is nonzero,
   pretend that the return takes place after LAST_INSN.  */

static void
expand_null_return_1 (rtx last_insn)
{
  rtx end_label = cleanup_label ? cleanup_label : return_label;

  clear_pending_stack_adjust ();
  do_pending_stack_adjust ();
  clear_last_expr ();

  if (end_label == 0)
     end_label = return_label = gen_label_rtx ();
  expand_goto_internal (NULL_TREE, end_label, last_insn);
}
\f
/* Generate RTL to evaluate the expression RETVAL and return it
   from the current function.  */

void
expand_return (tree retval)
{
  /* If there are any cleanups to be performed, then they will
     be inserted following LAST_INSN.  It is desirable
     that the last_insn, for such purposes, should be the
     last insn before computing the return value.  Otherwise, cleanups
     which call functions can clobber the return value.  */
  /* ??? rms: I think that is erroneous, because in C++ it would
     run destructors on variables that might be used in the subsequent
     computation of the return value.  */
  rtx last_insn = 0;
  rtx result_rtl;
  rtx val = 0;
  tree retval_rhs;

  /* If function wants no value, give it none.  */
  if (TREE_CODE (TREE_TYPE (TREE_TYPE (current_function_decl))) == VOID_TYPE)
    {
      expand_expr (retval, NULL_RTX, VOIDmode, 0);
      emit_queue ();
      expand_null_return ();
      return;
    }

  if (retval == error_mark_node)
    {
      /* Treat this like a return of no value from a function that
         returns a value.  */
      expand_null_return ();
      return;
    }
  else if (TREE_CODE (retval) == RESULT_DECL)
    retval_rhs = retval;
  else if ((TREE_CODE (retval) == MODIFY_EXPR || TREE_CODE (retval) == INIT_EXPR)
           && TREE_CODE (TREE_OPERAND (retval, 0)) == RESULT_DECL)
    retval_rhs = TREE_OPERAND (retval, 1);
  else if (VOID_TYPE_P (TREE_TYPE (retval)))
    /* Recognize tail-recursive call to void function.  */
    retval_rhs = retval;
  else
    retval_rhs = NULL_TREE;

  last_insn = get_last_insn ();

  /* Distribute return down conditional expr if either of the sides
     may involve tail recursion (see test below).  This enhances the number
     of tail recursions we see.  Don't do this always since it can produce
     sub-optimal code in some cases and we distribute assignments into
     conditional expressions when it would help.  */

  if (optimize && retval_rhs != 0
      && frame_offset == 0
      && TREE_CODE (retval_rhs) == COND_EXPR
      && (TREE_CODE (TREE_OPERAND (retval_rhs, 1)) == CALL_EXPR
          || TREE_CODE (TREE_OPERAND (retval_rhs, 2)) == CALL_EXPR))
    {
      rtx label = gen_label_rtx ();
      tree expr;

      do_jump (TREE_OPERAND (retval_rhs, 0), label, NULL_RTX);
      start_cleanup_deferral ();
      expr = build (MODIFY_EXPR, TREE_TYPE (TREE_TYPE (current_function_decl)),
                    DECL_RESULT (current_function_decl),
                    TREE_OPERAND (retval_rhs, 1));
      TREE_SIDE_EFFECTS (expr) = 1;
      expand_return (expr);
      emit_label (label);

      expr = build (MODIFY_EXPR, TREE_TYPE (TREE_TYPE (current_function_decl)),
                    DECL_RESULT (current_function_decl),
                    TREE_OPERAND (retval_rhs, 2));
      TREE_SIDE_EFFECTS (expr) = 1;
      expand_return (expr);
      end_cleanup_deferral ();
      return;
    }

  result_rtl = DECL_RTL (DECL_RESULT (current_function_decl));

  /* If the result is an aggregate that is being returned in one (or more)
     registers, load the registers here.  The compiler currently can't handle
     copying a BLKmode value into registers.  We could put this code in a
     more general area (for use by everyone instead of just function
     call/return), but until this feature is generally usable it is kept here
     (and in expand_call).  The value must go into a pseudo in case there
     are cleanups that will clobber the real return register.  */

  if (retval_rhs != 0
      && TYPE_MODE (TREE_TYPE (retval_rhs)) == BLKmode
      && GET_CODE (result_rtl) == REG)
    {
      int i;
      unsigned HOST_WIDE_INT bitpos, xbitpos;
      unsigned HOST_WIDE_INT padding_correction = 0;
      unsigned HOST_WIDE_INT bytes
        = int_size_in_bytes (TREE_TYPE (retval_rhs));
      int n_regs = (bytes + UNITS_PER_WORD - 1) / UNITS_PER_WORD;
      unsigned int bitsize
        = MIN (TYPE_ALIGN (TREE_TYPE (retval_rhs)), BITS_PER_WORD);
      rtx *result_pseudos = alloca (sizeof (rtx) * n_regs);
      rtx result_reg, src = NULL_RTX, dst = NULL_RTX;
      rtx result_val = expand_expr (retval_rhs, NULL_RTX, VOIDmode, 0);
      enum machine_mode tmpmode, result_reg_mode;

      if (bytes == 0)
        {
          expand_null_return ();
          return;
        }

      /* If the structure doesn't take up a whole number of words, see
         whether the register value should be padded on the left or on
         the right.  Set PADDING_CORRECTION to the number of padding
         bits needed on the left side.

         In most ABIs, the structure will be returned at the least end of
         the register, which translates to right padding on little-endian
         targets and left padding on big-endian targets.  The opposite
         holds if the structure is returned at the most significant
         end of the register.  */
      if (bytes % UNITS_PER_WORD != 0
          && (targetm.calls.return_in_msb (TREE_TYPE (retval_rhs))
              ? !BYTES_BIG_ENDIAN
              : BYTES_BIG_ENDIAN))
        padding_correction = (BITS_PER_WORD - ((bytes % UNITS_PER_WORD)
                                               * BITS_PER_UNIT));

      /* Copy the structure BITSIZE bits at a time.  */
      for (bitpos = 0, xbitpos = padding_correction;
           bitpos < bytes * BITS_PER_UNIT;
           bitpos += bitsize, xbitpos += bitsize)
        {
          /* We need a new destination pseudo each time xbitpos is
             on a word boundary and when xbitpos == padding_correction
             (the first time through).  */
          if (xbitpos % BITS_PER_WORD == 0
              || xbitpos == padding_correction)
            {
              /* Generate an appropriate register.  */
              dst = gen_reg_rtx (word_mode);
              result_pseudos[xbitpos / BITS_PER_WORD] = dst;

              /* Clear the destination before we move anything into it.  */
              emit_move_insn (dst, CONST0_RTX (GET_MODE (dst)));
            }

          /* We need a new source operand each time bitpos is on a word
             boundary.  */
          if (bitpos % BITS_PER_WORD == 0)
            src = operand_subword_force (result_val,
                                         bitpos / BITS_PER_WORD,
                                         BLKmode);

          /* Use bitpos for the source extraction (left justified) and
             xbitpos for the destination store (right justified).  */
          store_bit_field (dst, bitsize, xbitpos % BITS_PER_WORD, word_mode,
                           extract_bit_field (src, bitsize,
                                              bitpos % BITS_PER_WORD, 1,
                                              NULL_RTX, word_mode, word_mode,
                                              BITS_PER_WORD),
                           BITS_PER_WORD);
        }

      tmpmode = GET_MODE (result_rtl);
      if (tmpmode == BLKmode)
        {
          /* Find the smallest integer mode large enough to hold the
             entire structure and use that mode instead of BLKmode
             on the USE insn for the return register.  */
          for (tmpmode = GET_CLASS_NARROWEST_MODE (MODE_INT);
               tmpmode != VOIDmode;
               tmpmode = GET_MODE_WIDER_MODE (tmpmode))
            /* Have we found a large enough mode?  */
            if (GET_MODE_SIZE (tmpmode) >= bytes)
              break;

          /* No suitable mode found.  */
          if (tmpmode == VOIDmode)
            abort ();

          PUT_MODE (result_rtl, tmpmode);
        }

      if (GET_MODE_SIZE (tmpmode) < GET_MODE_SIZE (word_mode))
        result_reg_mode = word_mode;
      else
        result_reg_mode = tmpmode;
      result_reg = gen_reg_rtx (result_reg_mode);

      emit_queue ();
      for (i = 0; i < n_regs; i++)
        emit_move_insn (operand_subword (result_reg, i, 0, result_reg_mode),
                        result_pseudos[i]);

      if (tmpmode != result_reg_mode)
        result_reg = gen_lowpart (tmpmode, result_reg);

      expand_value_return (result_reg);
    }
  else if (retval_rhs != 0
           && !VOID_TYPE_P (TREE_TYPE (retval_rhs))
           && (GET_CODE (result_rtl) == REG
               || (GET_CODE (result_rtl) == PARALLEL)))
    {
      /* Calculate the return value into a temporary (usually a pseudo
         reg).  */
      tree ot = TREE_TYPE (DECL_RESULT (current_function_decl));
      tree nt = build_qualified_type (ot, TYPE_QUALS (ot) | TYPE_QUAL_CONST);

      val = assign_temp (nt, 0, 0, 1);
      val = expand_expr (retval_rhs, val, GET_MODE (val), 0);
      val = force_not_mem (val);
      emit_queue ();
      /* Return the calculated value, doing cleanups first.  */
      expand_value_return (shift_return_value (val));
    }
  else
    {
      /* No cleanups or no hard reg used;
         calculate value into hard return reg.  */
      expand_expr (retval, const0_rtx, VOIDmode, 0);
      emit_queue ();
      expand_value_return (result_rtl);
    }
}
\f
/* Attempt to optimize a potential tail recursion call into a goto.
   ARGUMENTS are the arguments to a CALL_EXPR; LAST_INSN indicates
   where to place the jump to the tail recursion label.

   Return TRUE if the call was optimized into a goto.  */

int
optimize_tail_recursion (tree arguments, rtx last_insn)
{
  /* Finish checking validity, and if valid emit code to set the
     argument variables for the new call.  */
  if (tail_recursion_args (arguments, DECL_ARGUMENTS (current_function_decl)))
    {
      if (tail_recursion_label == 0)
        {
          tail_recursion_label = gen_label_rtx ();
          emit_label_after (tail_recursion_label,
                            tail_recursion_reentry);
        }
      emit_queue ();
      expand_goto_internal (NULL_TREE, tail_recursion_label, last_insn);
      emit_barrier ();
      return 1;
    }
  return 0;
}

/* Emit code to alter this function's formal parms for a tail-recursive call.
   ACTUALS is a list of actual parameter expressions (chain of TREE_LISTs).
   FORMALS is the chain of decls of formals.
   Return 1 if this can be done;
   otherwise return 0 and do not emit any code.  */

static int
tail_recursion_args (tree actuals, tree formals)
{
  tree a = actuals, f = formals;
  int i;
  rtx *argvec;

  /* Check that number and types of actuals are compatible
     with the formals.  This is not always true in valid C code.
     Also check that no formal needs to be addressable
     and that all formals are scalars.  */

  /* Also count the args.  */

  for (a = actuals, f = formals, i = 0; a && f; a = TREE_CHAIN (a), f = TREE_CHAIN (f), i++)
    {
      if (TYPE_MAIN_VARIANT (TREE_TYPE (TREE_VALUE (a)))
          != TYPE_MAIN_VARIANT (TREE_TYPE (f)))
        return 0;
      if (GET_CODE (DECL_RTL (f)) != REG || DECL_MODE (f) == BLKmode)
        return 0;
    }
  if (a != 0 || f != 0)
    return 0;

  /* Compute all the actuals.  */

  argvec = alloca (i * sizeof (rtx));

  for (a = actuals, i = 0; a; a = TREE_CHAIN (a), i++)
    argvec[i] = expand_expr (TREE_VALUE (a), NULL_RTX, VOIDmode, 0);

  /* Find which actual values refer to current values of previous formals.
     Copy each of them now, before any formal is changed.  */

  for (a = actuals, i = 0; a; a = TREE_CHAIN (a), i++)
    {
      int copy = 0;
      int j;
      for (f = formals, j = 0; j < i; f = TREE_CHAIN (f), j++)
        if (reg_mentioned_p (DECL_RTL (f), argvec[i]))
          {
            copy = 1;
            break;
          }
      if (copy)
        argvec[i] = copy_to_reg (argvec[i]);
    }

  /* Insert the pre-call sequence point.  This is important in cases
     where the actual values post-modify the formals: we want the final
     values of the formals to be the ones that we assign below, not the
     result of the post-modification.  */
  emit_queue ();

  /* Store the values of the actuals into the formals.  */

  for (f = formals, a = actuals, i = 0; f;
       f = TREE_CHAIN (f), a = TREE_CHAIN (a), i++)
    {
      if (GET_MODE (DECL_RTL (f)) == GET_MODE (argvec[i]))
        emit_move_insn (DECL_RTL (f), argvec[i]);
      else
        {
          rtx tmp = argvec[i];
          int unsignedp = TREE_UNSIGNED (TREE_TYPE (TREE_VALUE (a)));
          promote_mode(TREE_TYPE (TREE_VALUE (a)), GET_MODE (tmp),
                       &unsignedp, 0);
          if (DECL_MODE (f) != GET_MODE (DECL_RTL (f)))
            {
              tmp = gen_reg_rtx (DECL_MODE (f));
              convert_move (tmp, argvec[i], unsignedp);
            }
          convert_move (DECL_RTL (f), tmp, unsignedp);
        }
    }

  free_temp_slots ();
  return 1;
}
\f
/* Generate the RTL code for entering a binding contour.
   The variables are declared one by one, by calls to `expand_decl'.

   FLAGS is a bitwise or of the following flags:

     1 - Nonzero if this construct should be visible to
         `exit_something'.

     2 - Nonzero if this contour does not require a
         NOTE_INSN_BLOCK_BEG note.  Virtually all calls from
         language-independent code should set this flag because they
         will not create corresponding BLOCK nodes.  (There should be
         a one-to-one correspondence between NOTE_INSN_BLOCK_BEG notes
         and BLOCKs.)  If this flag is set, MARK_ENDS should be zero
         when expand_end_bindings is called.

    If we are creating a NOTE_INSN_BLOCK_BEG note, a BLOCK may
    optionally be supplied.  If so, it becomes the NOTE_BLOCK for the
    note.  */

void
expand_start_bindings_and_block (int flags, tree block)
{
  struct nesting *thisblock = ALLOC_NESTING ();
  rtx note;
  int exit_flag = ((flags & 1) != 0);
  int block_flag = ((flags & 2) == 0);

  /* If a BLOCK is supplied, then the caller should be requesting a
     NOTE_INSN_BLOCK_BEG note.  */
  if (!block_flag && block)
    abort ();

  /* Create a note to mark the beginning of the block.  */
  if (block_flag)
    {
      note = emit_note (NOTE_INSN_BLOCK_BEG);
      NOTE_BLOCK (note) = block;
    }
  else
    note = emit_note (NOTE_INSN_DELETED);

  /* Make an entry on block_stack for the block we are entering.  */

  thisblock->desc = BLOCK_NESTING;
  thisblock->next = block_stack;
  thisblock->all = nesting_stack;
  thisblock->depth = ++nesting_depth;
  thisblock->data.block.stack_level = 0;
  thisblock->data.block.cleanups = 0;
  thisblock->data.block.exception_region = 0;
  thisblock->data.block.block_target_temp_slot_level = target_temp_slot_level;

  thisblock->data.block.conditional_code = 0;
  thisblock->data.block.last_unconditional_cleanup = note;
  /* When we insert instructions after the last unconditional cleanup,
     we don't adjust last_insn.  That means that a later add_insn will
     clobber the instructions we've just added.  The easiest way to
     fix this is to just insert another instruction here, so that the
     instructions inserted after the last unconditional cleanup are
     never the last instruction.  */
  emit_note (NOTE_INSN_DELETED);

  if (block_stack
      && !(block_stack->data.block.cleanups == NULL_TREE
           && block_stack->data.block.outer_cleanups == NULL_TREE))
    thisblock->data.block.outer_cleanups
      = tree_cons (NULL_TREE, block_stack->data.block.cleanups,
                   block_stack->data.block.outer_cleanups);
  else
    thisblock->data.block.outer_cleanups = 0;
  thisblock->data.block.label_chain = 0;
  thisblock->data.block.innermost_stack_block = stack_block_stack;
  thisblock->data.block.first_insn = note;
  thisblock->data.block.block_start_count = ++current_block_start_count;
  thisblock->exit_label = exit_flag ? gen_label_rtx () : 0;
  block_stack = thisblock;
  nesting_stack = thisblock;

  /* Make a new level for allocating stack slots.  */
  push_temp_slots ();
}

/* Specify the scope of temporaries created by TARGET_EXPRs.  Similar
   to CLEANUP_POINT_EXPR, but handles cases when a series of calls to
   expand_expr are made.  After we end the region, we know that all
   space for all temporaries that were created by TARGET_EXPRs will be
   destroyed and their space freed for reuse.  */

void
expand_start_target_temps (void)
{
  /* This is so that even if the result is preserved, the space
     allocated will be freed, as we know that it is no longer in use.  */
  push_temp_slots ();

  /* Start a new binding layer that will keep track of all cleanup
     actions to be performed.  */
  expand_start_bindings (2);

  target_temp_slot_level = temp_slot_level;
}

void
expand_end_target_temps (void)
{
  expand_end_bindings (NULL_TREE, 0, 0);

  /* This is so that even if the result is preserved, the space
     allocated will be freed, as we know that it is no longer in use.  */
  pop_temp_slots ();
}

/* Given a pointer to a BLOCK node return nonzero if (and only if) the node
   in question represents the outermost pair of curly braces (i.e. the "body
   block") of a function or method.

   For any BLOCK node representing a "body block" of a function or method, the
   BLOCK_SUPERCONTEXT of the node will point to another BLOCK node which
   represents the outermost (function) scope for the function or method (i.e.
   the one which includes the formal parameters).  The BLOCK_SUPERCONTEXT of
   *that* node in turn will point to the relevant FUNCTION_DECL node.  */

int
is_body_block (tree stmt)
{
  if (lang_hooks.no_body_blocks)
    return 0;

  if (TREE_CODE (stmt) == BLOCK)
    {
      tree parent = BLOCK_SUPERCONTEXT (stmt);

      if (parent && TREE_CODE (parent) == BLOCK)
        {
          tree grandparent = BLOCK_SUPERCONTEXT (parent);

          if (grandparent && TREE_CODE (grandparent) == FUNCTION_DECL)
            return 1;
        }
    }

  return 0;
}

/* True if we are currently emitting insns in an area of output code
   that is controlled by a conditional expression.  This is used by
   the cleanup handling code to generate conditional cleanup actions.  */

int
conditional_context (void)
{
  return block_stack && block_stack->data.block.conditional_code;
}

/* Return an opaque pointer to the current nesting level, so frontend code
   can check its own sanity.  */

struct nesting *
current_nesting_level (void)
{
  return cfun ? block_stack : 0;
}

/* Emit a handler label for a nonlocal goto handler.
   Also emit code to store the handler label in SLOT before BEFORE_INSN.  */

static rtx
expand_nl_handler_label (rtx slot, rtx before_insn)
{
  rtx insns;
  rtx handler_label = gen_label_rtx ();

  /* Don't let cleanup_cfg delete the handler.  */
  LABEL_PRESERVE_P (handler_label) = 1;

  start_sequence ();
  emit_move_insn (slot, gen_rtx_LABEL_REF (Pmode, handler_label));
  insns = get_insns ();
  end_sequence ();
  emit_insn_before (insns, before_insn);

  emit_label (handler_label);

  return handler_label;
}

/* Emit code to restore vital registers at the beginning of a nonlocal goto
   handler.  */
static void
expand_nl_goto_receiver (void)
{
    /* Clobber the FP when we get here, so we have to make sure it's
     marked as used by this function.  */
  emit_insn (gen_rtx_USE (VOIDmode, hard_frame_pointer_rtx));

  /* Mark the static chain as clobbered here so life information
     doesn't get messed up for it.  */
  emit_insn (gen_rtx_CLOBBER (VOIDmode, static_chain_rtx));

#ifdef HAVE_nonlocal_goto
  if (! HAVE_nonlocal_goto)
#endif
    /* First adjust our frame pointer to its actual value.  It was
       previously set to the start of the virtual area corresponding to
       the stacked variables when we branched here and now needs to be
       adjusted to the actual hardware fp value.

       Assignments are to virtual registers are converted by
       instantiate_virtual_regs into the corresponding assignment
       to the underlying register (fp in this case) that makes
       the original assignment true.
       So the following insn will actually be
       decrementing fp by STARTING_FRAME_OFFSET.  */
    emit_move_insn (virtual_stack_vars_rtx, hard_frame_pointer_rtx);

#if ARG_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
  if (fixed_regs[ARG_POINTER_REGNUM])
    {
#ifdef ELIMINABLE_REGS
      /* If the argument pointer can be eliminated in favor of the
         frame pointer, we don't need to restore it.  We assume here
         that if such an elimination is present, it can always be used.
         This is the case on all known machines; if we don't make this
         assumption, we do unnecessary saving on many machines.  */
      static const struct elims {const int from, to;} elim_regs[] = ELIMINABLE_REGS;
      size_t i;

      for (i = 0; i < ARRAY_SIZE (elim_regs); i++)
        if (elim_regs[i].from == ARG_POINTER_REGNUM
            && elim_regs[i].to == HARD_FRAME_POINTER_REGNUM)
          break;

      if (i == ARRAY_SIZE (elim_regs))
#endif
        {
          /* Now restore our arg pointer from the address at which it
             was saved in our stack frame.  */
          emit_move_insn (virtual_incoming_args_rtx,
                          copy_to_reg (get_arg_pointer_save_area (cfun)));
        }
    }
#endif

#ifdef HAVE_nonlocal_goto_receiver
  if (HAVE_nonlocal_goto_receiver)
    emit_insn (gen_nonlocal_goto_receiver ());
#endif

  /* @@@ This is a kludge.  Not all machine descriptions define a blockage
     insn, but we must not allow the code we just generated to be reordered
     by scheduling.  Specifically, the update of the frame pointer must
     happen immediately, not later.  So emit an ASM_INPUT to act as blockage
     insn.  */
  emit_insn (gen_rtx_ASM_INPUT (VOIDmode, ""));
}

/* Make handlers for nonlocal gotos taking place in the function calls in
   block THISBLOCK.  */

static void
expand_nl_goto_receivers (struct nesting *thisblock)
{
  tree link;
  rtx afterward = gen_label_rtx ();
  rtx insns, slot;
  rtx label_list;
  int any_invalid;

  /* Record the handler address in the stack slot for that purpose,
     during this block, saving and restoring the outer value.  */
  if (thisblock->next != 0)
    for (slot = nonlocal_goto_handler_slots; slot; slot = XEXP (slot, 1))
      {
        rtx save_receiver = gen_reg_rtx (Pmode);
        emit_move_insn (XEXP (slot, 0), save_receiver);

        start_sequence ();
        emit_move_insn (save_receiver, XEXP (slot, 0));
        insns = get_insns ();
        end_sequence ();
        emit_insn_before (insns, thisblock->data.block.first_insn);
      }

  /* Jump around the handlers; they run only when specially invoked.  */
  emit_jump (afterward);

  /* Make a separate handler for each label.  */
  link = nonlocal_labels;
  slot = nonlocal_goto_handler_slots;
  label_list = NULL_RTX;
  for (; link; link = TREE_CHAIN (link), slot = XEXP (slot, 1))
    /* Skip any labels we shouldn't be able to jump to from here,
       we generate one special handler for all of them below which just calls
       abort.  */
    if (! DECL_TOO_LATE (TREE_VALUE (link)))
      {
        rtx lab;
        lab = expand_nl_handler_label (XEXP (slot, 0),
                                       thisblock->data.block.first_insn);
        label_list = gen_rtx_EXPR_LIST (VOIDmode, lab, label_list);

        expand_nl_goto_receiver ();

        /* Jump to the "real" nonlocal label.  */
        expand_goto (TREE_VALUE (link));
      }

  /* A second pass over all nonlocal labels; this time we handle those
     we should not be able to jump to at this point.  */
  link = nonlocal_labels;
  slot = nonlocal_goto_handler_slots;
  any_invalid = 0;
  for (; link; link = TREE_CHAIN (link), slot = XEXP (slot, 1))
    if (DECL_TOO_LATE (TREE_VALUE (link)))
      {
        rtx lab;
        lab = expand_nl_handler_label (XEXP (slot, 0),
                                       thisblock->data.block.first_insn);
        label_list = gen_rtx_EXPR_LIST (VOIDmode, lab, label_list);
        any_invalid = 1;
      }

  if (any_invalid)
    {
      expand_nl_goto_receiver ();
      expand_builtin_trap ();
    }

  nonlocal_goto_handler_labels = label_list;
  emit_label (afterward);
}

/* Warn about any unused VARS (which may contain nodes other than
   VAR_DECLs, but such nodes are ignored).  The nodes are connected
   via the TREE_CHAIN field.  */

void
warn_about_unused_variables (tree vars)
{
  tree decl;

  if (warn_unused_variable)
    for (decl = vars; decl; decl = TREE_CHAIN (decl))
      if (TREE_CODE (decl) == VAR_DECL
          && ! TREE_USED (decl)
          && ! DECL_IN_SYSTEM_HEADER (decl)
          && DECL_NAME (decl) && ! DECL_ARTIFICIAL (decl))
        warning ("%Junused variable '%D'", decl, decl);
}

/* Generate RTL code to terminate a binding contour.

   VARS is the chain of VAR_DECL nodes for the variables bound in this
   contour.  There may actually be other nodes in this chain, but any
   nodes other than VAR_DECLS are ignored.

   MARK_ENDS is nonzero if we should put a note at the beginning
   and end of this binding contour.

   DONT_JUMP_IN is positive if it is not valid to jump into this contour,
   zero if we can jump into this contour only if it does not have a saved
   stack level, and negative if we are not to check for invalid use of
   labels (because the front end does that).  */

void
expand_end_bindings (tree vars, int mark_ends, int dont_jump_in)
{
  struct nesting *thisblock = block_stack;

  /* If any of the variables in this scope were not used, warn the
     user.  */
  warn_about_unused_variables (vars);

  if (thisblock->exit_label)
    {
      do_pending_stack_adjust ();
      emit_label (thisblock->exit_label);
    }

  /* If necessary, make handlers for nonlocal gotos taking
     place in the function calls in this block.  */
  if (function_call_count != 0 && nonlocal_labels
      /* Make handler for outermost block
         if there were any nonlocal gotos to this function.  */
      && (thisblock->next == 0 ? current_function_has_nonlocal_label
          /* Make handler for inner block if it has something
             special to do when you jump out of it.  */
          : (thisblock->data.block.cleanups != 0
             || thisblock->data.block.stack_level != 0)))
    expand_nl_goto_receivers (thisblock);

  /* Don't allow jumping into a block that has a stack level.
     Cleanups are allowed, though.  */
  if (dont_jump_in > 0
      || (dont_jump_in == 0 && thisblock->data.block.stack_level != 0))
    {
      struct label_chain *chain;

      /* Any labels in this block are no longer valid to go to.
         Mark them to cause an error message.  */
      for (chain = thisblock->data.block.label_chain; chain; chain = chain->next)
        {
          DECL_TOO_LATE (chain->label) = 1;
          /* If any goto without a fixup came to this label,
             that must be an error, because gotos without fixups
             come from outside all saved stack-levels.  */
          if (TREE_ADDRESSABLE (chain->label))
            error ("%Jlabel '%D' used before containing binding contour",
                   chain->label, chain->label);
        }
    }

  /* Restore stack level in effect before the block
     (only if variable-size objects allocated).  */
  /* Perform any cleanups associated with the block.  */

  if (thisblock->data.block.stack_level != 0
      || thisblock->data.block.cleanups != 0)
    {
      int reachable;
      rtx insn;

      /* Don't let cleanups affect ({...}) constructs.  */
      int old_expr_stmts_for_value = expr_stmts_for_value;
      rtx old_last_expr_value = last_expr_value;
      rtx old_last_expr_alt_rtl = last_expr_alt_rtl;
      tree old_last_expr_type = last_expr_type;
      expr_stmts_for_value = 0;

      /* Only clean up here if this point can actually be reached.  */
      insn = get_last_insn ();
      if (GET_CODE (insn) == NOTE)
        insn = prev_nonnote_insn (insn);
      reachable = (! insn || GET_CODE (insn) != BARRIER);

      /* Do the cleanups.  */
      expand_cleanups (thisblock->data.block.cleanups, 0, reachable);
      if (reachable)
        do_pending_stack_adjust ();

      expr_stmts_for_value = old_expr_stmts_for_value;
      last_expr_value = old_last_expr_value;
      last_expr_alt_rtl = old_last_expr_alt_rtl;
      last_expr_type = old_last_expr_type;

      /* Restore the stack level.  */

      if (reachable && thisblock->data.block.stack_level != 0)
        {
          emit_stack_restore (thisblock->next ? SAVE_BLOCK : SAVE_FUNCTION,
                              thisblock->data.block.stack_level, NULL_RTX);
          if (nonlocal_goto_handler_slots != 0)
            emit_stack_save (SAVE_NONLOCAL, &nonlocal_goto_stack_level,
                             NULL_RTX);
        }

      /* Any gotos out of this block must also do these things.
         Also report any gotos with fixups that came to labels in this
         level.  */
      fixup_gotos (thisblock,
                   thisblock->data.block.stack_level,
                   thisblock->data.block.cleanups,
                   thisblock->data.block.first_insn,
                   dont_jump_in);
    }

  /* Mark the beginning and end of the scope if requested.
     We do this now, after running cleanups on the variables
     just going out of scope, so they are in scope for their cleanups.  */

  if (mark_ends)
    {
      rtx note = emit_note (NOTE_INSN_BLOCK_END);
      NOTE_BLOCK (note) = NOTE_BLOCK (thisblock->data.block.first_insn);
    }
  else
    /* Get rid of the beginning-mark if we don't make an end-mark.  */
    NOTE_LINE_NUMBER (thisblock->data.block.first_insn) = NOTE_INSN_DELETED;

  /* Restore the temporary level of TARGET_EXPRs.  */
  target_temp_slot_level = thisblock->data.block.block_target_temp_slot_level;

  /* Restore block_stack level for containing block.  */

  stack_block_stack = thisblock->data.block.innermost_stack_block;
  POPSTACK (block_stack);

  /* Pop the stack slot nesting and free any slots at this level.  */
  pop_temp_slots ();
}
\f
/* Generate code to save the stack pointer at the start of the current block
   and set up to restore it on exit.  */

void
save_stack_pointer (void)
{
  struct nesting *thisblock = block_stack;

  if (thisblock->data.block.stack_level == 0)
    {
      emit_stack_save (thisblock->next ? SAVE_BLOCK : SAVE_FUNCTION,
                       &thisblock->data.block.stack_level,
                       thisblock->data.block.first_insn);
      stack_block_stack = thisblock;
    }
}
\f
/* Generate RTL for the automatic variable declaration DECL.
   (Other kinds of declarations are simply ignored if seen here.)  */

void
expand_decl (tree decl)
{
  tree type;

  type = TREE_TYPE (decl);

  /* For a CONST_DECL, set mode, alignment, and sizes from those of the
     type in case this node is used in a reference.  */
  if (TREE_CODE (decl) == CONST_DECL)
    {
      DECL_MODE (decl) = TYPE_MODE (type);
      DECL_ALIGN (decl) = TYPE_ALIGN (type);
      DECL_SIZE (decl) = TYPE_SIZE (type);
      DECL_SIZE_UNIT (decl) = TYPE_SIZE_UNIT (type);
      return;
    }

  /* Otherwise, only automatic variables need any expansion done.  Static and
     external variables, and external functions, will be handled by
     `assemble_variable' (called from finish_decl).  TYPE_DECL requires
     nothing.  PARM_DECLs are handled in `assign_parms'.  */
  if (TREE_CODE (decl) != VAR_DECL)
    return;

  if (TREE_STATIC (decl) || DECL_EXTERNAL (decl))
    return;

  /* Create the RTL representation for the variable.  */

  if (type == error_mark_node)
    SET_DECL_RTL (decl, gen_rtx_MEM (BLKmode, const0_rtx));

  else if (DECL_SIZE (decl) == 0)
    /* Variable with incomplete type.  */
    {
      rtx x;
      if (DECL_INITIAL (decl) == 0)
        /* Error message was already done; now avoid a crash.  */
        x = gen_rtx_MEM (BLKmode, const0_rtx);
      else
        /* An initializer is going to decide the size of this array.
           Until we know the size, represent its address with a reg.  */
        x = gen_rtx_MEM (BLKmode, gen_reg_rtx (Pmode));

      set_mem_attributes (x, decl, 1);
      SET_DECL_RTL (decl, x);
    }
  else if (DECL_MODE (decl) != BLKmode
           /* If -ffloat-store, don't put explicit float vars
              into regs.  */
           && !(flag_float_store
                && TREE_CODE (type) == REAL_TYPE)
           && ! TREE_THIS_VOLATILE (decl)
           && ! DECL_NONLOCAL (decl)
           && (DECL_REGISTER (decl) || DECL_ARTIFICIAL (decl) || optimize))
    {
      /* Automatic variable that can go in a register.  */
      int unsignedp = TREE_UNSIGNED (type);
      enum machine_mode reg_mode
        = promote_mode (type, DECL_MODE (decl), &unsignedp, 0);

      SET_DECL_RTL (decl, gen_reg_rtx (reg_mode));

      if (!DECL_ARTIFICIAL (decl))
        mark_user_reg (DECL_RTL (decl));

      if (POINTER_TYPE_P (type))
        mark_reg_pointer (DECL_RTL (decl),
                          TYPE_ALIGN (TREE_TYPE (TREE_TYPE (decl))));

      maybe_set_unchanging (DECL_RTL (decl), decl);

      /* If something wants our address, try to use ADDRESSOF.  */
      if (TREE_ADDRESSABLE (decl))
        put_var_into_stack (decl, /*rescan=*/false);
    }

  else if (TREE_CODE (DECL_SIZE_UNIT (decl)) == INTEGER_CST
           && ! (flag_stack_check && ! STACK_CHECK_BUILTIN
                 && 0 < compare_tree_int (DECL_SIZE_UNIT (decl),
                                          STACK_CHECK_MAX_VAR_SIZE)))
    {
      /* Variable of fixed size that goes on the stack.  */
      rtx oldaddr = 0;
      rtx addr;
      rtx x;

      /* If we previously made RTL for this decl, it must be an array
         whose size was determined by the initializer.
         The old address was a register; set that register now
         to the proper address.  */
      if (DECL_RTL_SET_P (decl))
        {
          if (GET_CODE (DECL_RTL (decl)) != MEM
              || GET_CODE (XEXP (DECL_RTL (decl), 0)) != REG)
            abort ();
          oldaddr = XEXP (DECL_RTL (decl), 0);
        }

      /* Set alignment we actually gave this decl.  */
      DECL_ALIGN (decl) = (DECL_MODE (decl) == BLKmode ? BIGGEST_ALIGNMENT
                           : GET_MODE_BITSIZE (DECL_MODE (decl)));
      DECL_USER_ALIGN (decl) = 0;

      x = assign_temp (decl, 1, 1, 1);
      set_mem_attributes (x, decl, 1);
      SET_DECL_RTL (decl, x);

      if (oldaddr)
        {
          addr = force_operand (XEXP (DECL_RTL (decl), 0), oldaddr);
          if (addr != oldaddr)
            emit_move_insn (oldaddr, addr);
        }
    }
  else
    /* Dynamic-size object: must push space on the stack.  */
    {
      rtx address, size, x;

      /* Record the stack pointer on entry to block, if have
         not already done so.  */
      do_pending_stack_adjust ();
      save_stack_pointer ();

      /* In function-at-a-time mode, variable_size doesn't expand this,
         so do it now.  */
      if (TREE_CODE (type) == ARRAY_TYPE && TYPE_DOMAIN (type))
        expand_expr (TYPE_MAX_VALUE (TYPE_DOMAIN (type)),
                     const0_rtx, VOIDmode, 0);

      /* Compute the variable's size, in bytes.  */
      size = expand_expr (DECL_SIZE_UNIT (decl), NULL_RTX, VOIDmode, 0);
      free_temp_slots ();

      /* Allocate space on the stack for the variable.  Note that
         DECL_ALIGN says how the variable is to be aligned and we
         cannot use it to conclude anything about the alignment of
         the size.  */
      address = allocate_dynamic_stack_space (size, NULL_RTX,
                                              TYPE_ALIGN (TREE_TYPE (decl)));

      /* Reference the variable indirect through that rtx.  */
      x = gen_rtx_MEM (DECL_MODE (decl), address);
      set_mem_attributes (x, decl, 1);
      SET_DECL_RTL (decl, x);


      /* Indicate the alignment we actually gave this variable.  */
#ifdef STACK_BOUNDARY
      DECL_ALIGN (decl) = STACK_BOUNDARY;
#else
      DECL_ALIGN (decl) = BIGGEST_ALIGNMENT;
#endif
      DECL_USER_ALIGN (decl) = 0;
    }
}
\f
/* Emit code to perform the initialization of a declaration DECL.  */

void
expand_decl_init (tree decl)
{
  int was_used = TREE_USED (decl);

  /* If this is a CONST_DECL, we don't have to generate any code.  Likewise
     for static decls.  */
  if (TREE_CODE (decl) == CONST_DECL
      || TREE_STATIC (decl))
    return;

  /* Compute and store the initial value now.  */

  push_temp_slots ();

  if (DECL_INITIAL (decl) == error_mark_node)
    {
      enum tree_code code = TREE_CODE (TREE_TYPE (decl));

      if (code == INTEGER_TYPE || code == REAL_TYPE || code == ENUMERAL_TYPE
          || code == POINTER_TYPE || code == REFERENCE_TYPE)
        expand_assignment (decl, convert (TREE_TYPE (decl), integer_zero_node),
                           0);
      emit_queue ();
    }
  else if (DECL_INITIAL (decl) && TREE_CODE (DECL_INITIAL (decl)) != TREE_LIST)
    {
      emit_line_note (DECL_SOURCE_LOCATION (decl));
      expand_assignment (decl, DECL_INITIAL (decl), 0);
      emit_queue ();
    }

  /* Don't let the initialization count as "using" the variable.  */
  TREE_USED (decl) = was_used;

  /* Free any temporaries we made while initializing the decl.  */
  preserve_temp_slots (NULL_RTX);
  free_temp_slots ();
  pop_temp_slots ();
}

/* CLEANUP is an expression to be executed at exit from this binding contour;
   for example, in C++, it might call the destructor for this variable.

   We wrap CLEANUP in an UNSAVE_EXPR node, so that we can expand the
   CLEANUP multiple times, and have the correct semantics.  This
   happens in exception handling, for gotos, returns, breaks that
   leave the current scope.

   If CLEANUP is nonzero and DECL is zero, we record a cleanup
   that is not associated with any particular variable.  */

int
expand_decl_cleanup (tree decl, tree cleanup)
{
  struct nesting *thisblock;

  /* Error if we are not in any block.  */
  if (cfun == 0 || block_stack == 0)
    return 0;

  thisblock = block_stack;

  /* Record the cleanup if there is one.  */

  if (cleanup != 0)
    {
      tree t;
      rtx seq;
      tree *cleanups = &thisblock->data.block.cleanups;
      int cond_context = conditional_context ();

      if (cond_context)
        {
          rtx flag = gen_reg_rtx (word_mode);
          rtx set_flag_0;
          tree cond;

          start_sequence ();
          emit_move_insn (flag, const0_rtx);
          set_flag_0 = get_insns ();
          end_sequence ();

          thisblock->data.block.last_unconditional_cleanup
            = emit_insn_after (set_flag_0,
                                thisblock->data.block.last_unconditional_cleanup);

          emit_move_insn (flag, const1_rtx);

          cond = build_decl (VAR_DECL, NULL_TREE,
                             (*lang_hooks.types.type_for_mode) (word_mode, 1));
          SET_DECL_RTL (cond, flag);

          /* Conditionalize the cleanup.  */
          cleanup = build (COND_EXPR, void_type_node,
                           (*lang_hooks.truthvalue_conversion) (cond),
                           cleanup, integer_zero_node);
          cleanup = fold (cleanup);

          cleanups = &thisblock->data.block.cleanups;
        }

      cleanup = unsave_expr (cleanup);

      t = *cleanups = tree_cons (decl, cleanup, *cleanups);

      if (! cond_context)
        /* If this block has a cleanup, it belongs in stack_block_stack.  */
        stack_block_stack = thisblock;

      if (cond_context)
        {
          start_sequence ();
        }

      if (! using_eh_for_cleanups_p)
        TREE_ADDRESSABLE (t) = 1;
      else
        expand_eh_region_start ();

      if (cond_context)
        {
          seq = get_insns ();
          end_sequence ();
          if (seq)
            thisblock->data.block.last_unconditional_cleanup
              = emit_insn_after (seq,
                                 thisblock->data.block.last_unconditional_cleanup);
        }
      else
        {
          thisblock->data.block.last_unconditional_cleanup
            = get_last_insn ();
          /* When we insert instructions after the last unconditional cleanup,
             we don't adjust last_insn.  That means that a later add_insn will
             clobber the instructions we've just added.  The easiest way to
             fix this is to just insert another instruction here, so that the
             instructions inserted after the last unconditional cleanup are
             never the last instruction.  */
          emit_note (NOTE_INSN_DELETED);
        }
    }
  return 1;
}

/* Like expand_decl_cleanup, but maybe only run the cleanup if an exception
   is thrown.  */

int
expand_decl_cleanup_eh (tree decl, tree cleanup, int eh_only)
{
  int ret = expand_decl_cleanup (decl, cleanup);
  if (cleanup && ret)
    {
      tree node = block_stack->data.block.cleanups;
      CLEANUP_EH_ONLY (node) = eh_only;
    }
  return ret;
}
\f
/* DECL is an anonymous union.  CLEANUP is a cleanup for DECL.
   DECL_ELTS is the list of elements that belong to DECL's type.
   In each, the TREE_VALUE is a VAR_DECL, and the TREE_PURPOSE a cleanup.  */

void
expand_anon_union_decl (tree decl, tree cleanup, tree decl_elts)
{
  struct nesting *thisblock = cfun == 0 ? 0 : block_stack;