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

/* Tree lowering pass.  This pass converts the GENERIC functions-as-trees
   tree representation into the GIMPLE form.
   Copyright (C) 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
   Free Software Foundation, Inc.
   Major work done by Sebastian Pop <s.pop@laposte.net>,
   Diego Novillo <dnovillo@redhat.com> and Jason Merrill <jason@redhat.com>.

This file is part of GCC.

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

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

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

#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "tree.h"
#include "rtl.h"
#include "gimple.h"
#include "tree-iterator.h"
#include "tree-inline.h"
#include "diagnostic.h"
#include "langhooks.h"
#include "langhooks-def.h"
#include "tree-flow.h"
#include "cgraph.h"
#include "timevar.h"
#include "except.h"
#include "hashtab.h"
#include "flags.h"
#include "real.h"
#include "function.h"
#include "output.h"
#include "expr.h"
#include "ggc.h"
#include "toplev.h"
#include "target.h"
#include "optabs.h"
#include "pointer-set.h"
#include "splay-tree.h"
#include "vec.h"
#include "gimple.h"
#include "tree-pass.h"


enum gimplify_omp_var_data
{
  GOVD_SEEN = 1,
  GOVD_EXPLICIT = 2,
  GOVD_SHARED = 4,
  GOVD_PRIVATE = 8,
  GOVD_FIRSTPRIVATE = 16,
  GOVD_LASTPRIVATE = 32,
  GOVD_REDUCTION = 64,
  GOVD_LOCAL = 128,
  GOVD_DEBUG_PRIVATE = 256,
  GOVD_PRIVATE_OUTER_REF = 512,
  GOVD_DATA_SHARE_CLASS = (GOVD_SHARED | GOVD_PRIVATE | GOVD_FIRSTPRIVATE
                           | GOVD_LASTPRIVATE | GOVD_REDUCTION | GOVD_LOCAL)
};


enum omp_region_type
{
  ORT_WORKSHARE = 0,
  ORT_TASK = 1,
  ORT_PARALLEL = 2,
  ORT_COMBINED_PARALLEL = 3
};

struct gimplify_omp_ctx
{
  struct gimplify_omp_ctx *outer_context;
  splay_tree variables;
  struct pointer_set_t *privatized_types;
  location_t location;
  enum omp_clause_default_kind default_kind;
  enum omp_region_type region_type;
};

static struct gimplify_ctx *gimplify_ctxp;
static struct gimplify_omp_ctx *gimplify_omp_ctxp;


/* Formal (expression) temporary table handling: Multiple occurrences of
   the same scalar expression are evaluated into the same temporary.  */

typedef struct gimple_temp_hash_elt
{
  tree val;   /* Key */
  tree temp;  /* Value */
} elt_t;

/* Forward declarations.  */
static enum gimplify_status gimplify_compound_expr (tree *, gimple_seq *, bool);

/* Mark X addressable.  Unlike the langhook we expect X to be in gimple
   form and we don't do any syntax checking.  */
void
mark_addressable (tree x)
{
  while (handled_component_p (x))
    x = TREE_OPERAND (x, 0);
  if (TREE_CODE (x) != VAR_DECL
      && TREE_CODE (x) != PARM_DECL
      && TREE_CODE (x) != RESULT_DECL)
    return ;
  TREE_ADDRESSABLE (x) = 1;
}

/* Return a hash value for a formal temporary table entry.  */

static hashval_t
gimple_tree_hash (const void *p)
{
  tree t = ((const elt_t *) p)->val;
  return iterative_hash_expr (t, 0);
}

/* Compare two formal temporary table entries.  */

static int
gimple_tree_eq (const void *p1, const void *p2)
{
  tree t1 = ((const elt_t *) p1)->val;
  tree t2 = ((const elt_t *) p2)->val;
  enum tree_code code = TREE_CODE (t1);

  if (TREE_CODE (t2) != code
      || TREE_TYPE (t1) != TREE_TYPE (t2))
    return 0;

  if (!operand_equal_p (t1, t2, 0))
    return 0;

  /* Only allow them to compare equal if they also hash equal; otherwise
     results are nondeterminate, and we fail bootstrap comparison.  */
  gcc_assert (gimple_tree_hash (p1) == gimple_tree_hash (p2));

  return 1;
}

/* Link gimple statement GS to the end of the sequence *SEQ_P.  If
   *SEQ_P is NULL, a new sequence is allocated.  This function is
   similar to gimple_seq_add_stmt, but does not scan the operands.
   During gimplification, we need to manipulate statement sequences
   before the def/use vectors have been constructed.  */

static void
gimplify_seq_add_stmt (gimple_seq *seq_p, gimple gs)
{
  gimple_stmt_iterator si;

  if (gs == NULL)
    return;

  if (*seq_p == NULL)
    *seq_p = gimple_seq_alloc ();

  si = gsi_last (*seq_p);

  gsi_insert_after_without_update (&si, gs, GSI_NEW_STMT);
}

/* Append sequence SRC to the end of sequence *DST_P.  If *DST_P is
   NULL, a new sequence is allocated.   This function is
   similar to gimple_seq_add_seq, but does not scan the operands.
   During gimplification, we need to manipulate statement sequences
   before the def/use vectors have been constructed.  */

static void
gimplify_seq_add_seq (gimple_seq *dst_p, gimple_seq src)
{
  gimple_stmt_iterator si;

  if (src == NULL)
    return;

  if (*dst_p == NULL)
    *dst_p = gimple_seq_alloc ();

  si = gsi_last (*dst_p);
  gsi_insert_seq_after_without_update (&si, src, GSI_NEW_STMT);
}

/* Set up a context for the gimplifier.  */

void
push_gimplify_context (struct gimplify_ctx *c)
{
  memset (c, '\0', sizeof (*c));
  c->prev_context = gimplify_ctxp;
  gimplify_ctxp = c;
}

/* Tear down a context for the gimplifier.  If BODY is non-null, then
   put the temporaries into the outer BIND_EXPR.  Otherwise, put them
   in the local_decls.

   BODY is not a sequence, but the first tuple in a sequence.  */

void
pop_gimplify_context (gimple body)
{
  struct gimplify_ctx *c = gimplify_ctxp;

  gcc_assert (c && (c->bind_expr_stack == NULL
                    || VEC_empty (gimple, c->bind_expr_stack)));
  VEC_free (gimple, heap, c->bind_expr_stack);
  gimplify_ctxp = c->prev_context;

  if (body)
    declare_vars (c->temps, body, false);
  else
    record_vars (c->temps);

  if (c->temp_htab)
    htab_delete (c->temp_htab);
}

static void
gimple_push_bind_expr (gimple gimple_bind)
{
  if (gimplify_ctxp->bind_expr_stack == NULL)
    gimplify_ctxp->bind_expr_stack = VEC_alloc (gimple, heap, 8);
  VEC_safe_push (gimple, heap, gimplify_ctxp->bind_expr_stack, gimple_bind);
}

static void
gimple_pop_bind_expr (void)
{
  VEC_pop (gimple, gimplify_ctxp->bind_expr_stack);
}

gimple
gimple_current_bind_expr (void)
{
  return VEC_last (gimple, gimplify_ctxp->bind_expr_stack);
}

/* Return the stack GIMPLE_BINDs created during gimplification.  */

VEC(gimple, heap) *
gimple_bind_expr_stack (void)
{
  return gimplify_ctxp->bind_expr_stack;
}

/* Returns true iff there is a COND_EXPR between us and the innermost
   CLEANUP_POINT_EXPR.  This info is used by gimple_push_cleanup.  */

static bool
gimple_conditional_context (void)
{
  return gimplify_ctxp->conditions > 0;
}

/* Note that we've entered a COND_EXPR.  */

static void
gimple_push_condition (void)
{
#ifdef ENABLE_GIMPLE_CHECKING
  if (gimplify_ctxp->conditions == 0)
    gcc_assert (gimple_seq_empty_p (gimplify_ctxp->conditional_cleanups));
#endif
  ++(gimplify_ctxp->conditions);
}

/* Note that we've left a COND_EXPR.  If we're back at unconditional scope
   now, add any conditional cleanups we've seen to the prequeue.  */

static void
gimple_pop_condition (gimple_seq *pre_p)
{
  int conds = --(gimplify_ctxp->conditions);

  gcc_assert (conds >= 0);
  if (conds == 0)
    {
      gimplify_seq_add_seq (pre_p, gimplify_ctxp->conditional_cleanups);
      gimplify_ctxp->conditional_cleanups = NULL;
    }
}

/* A stable comparison routine for use with splay trees and DECLs.  */

static int
splay_tree_compare_decl_uid (splay_tree_key xa, splay_tree_key xb)
{
  tree a = (tree) xa;
  tree b = (tree) xb;

  return DECL_UID (a) - DECL_UID (b);
}

/* Create a new omp construct that deals with variable remapping.  */

static struct gimplify_omp_ctx *
new_omp_context (enum omp_region_type region_type)
{
  struct gimplify_omp_ctx *c;

  c = XCNEW (struct gimplify_omp_ctx);
  c->outer_context = gimplify_omp_ctxp;
  c->variables = splay_tree_new (splay_tree_compare_decl_uid, 0, 0);
  c->privatized_types = pointer_set_create ();
  c->location = input_location;
  c->region_type = region_type;
  if (region_type != ORT_TASK)
    c->default_kind = OMP_CLAUSE_DEFAULT_SHARED;
  else
    c->default_kind = OMP_CLAUSE_DEFAULT_UNSPECIFIED;

  return c;
}

/* Destroy an omp construct that deals with variable remapping.  */

static void
delete_omp_context (struct gimplify_omp_ctx *c)
{
  splay_tree_delete (c->variables);
  pointer_set_destroy (c->privatized_types);
  XDELETE (c);
}

static void omp_add_variable (struct gimplify_omp_ctx *, tree, unsigned int);
static bool omp_notice_variable (struct gimplify_omp_ctx *, tree, bool);

/* A subroutine of append_to_statement_list{,_force}.  T is not NULL.  */

static void
append_to_statement_list_1 (tree t, tree *list_p)
{
  tree list = *list_p;
  tree_stmt_iterator i;

  if (!list)
    {
      if (t && TREE_CODE (t) == STATEMENT_LIST)
        {
          *list_p = t;
          return;
        }
      *list_p = list = alloc_stmt_list ();
    }

  i = tsi_last (list);
  tsi_link_after (&i, t, TSI_CONTINUE_LINKING);
}

/* Add T to the end of the list container pointed to by LIST_P.
   If T is an expression with no effects, it is ignored.  */

void
append_to_statement_list (tree t, tree *list_p)
{
  if (t && TREE_SIDE_EFFECTS (t))
    append_to_statement_list_1 (t, list_p);
}

/* Similar, but the statement is always added, regardless of side effects.  */

void
append_to_statement_list_force (tree t, tree *list_p)
{
  if (t != NULL_TREE)
    append_to_statement_list_1 (t, list_p);
}

/* Both gimplify the statement T and append it to *SEQ_P.  This function
   behaves exactly as gimplify_stmt, but you don't have to pass T as a
   reference.  */

void
gimplify_and_add (tree t, gimple_seq *seq_p)
{
  gimplify_stmt (&t, seq_p);
}

/* Gimplify statement T into sequence *SEQ_P, and return the first
   tuple in the sequence of generated tuples for this statement.
   Return NULL if gimplifying T produced no tuples.  */

static gimple
gimplify_and_return_first (tree t, gimple_seq *seq_p)
{
  gimple_stmt_iterator last = gsi_last (*seq_p);

  gimplify_and_add (t, seq_p);

  if (!gsi_end_p (last))
    {
      gsi_next (&last);
      return gsi_stmt (last);
    }
  else
    return gimple_seq_first_stmt (*seq_p);
}

/* Strip off a legitimate source ending from the input string NAME of
   length LEN.  Rather than having to know the names used by all of
   our front ends, we strip off an ending of a period followed by
   up to five characters.  (Java uses ".class".)  */

static inline void
remove_suffix (char *name, int len)
{
  int i;

  for (i = 2;  i < 8 && len > i;  i++)
    {
      if (name[len - i] == '.')
        {
          name[len - i] = '\0';
          break;
        }
    }
}

/* Create a new temporary name with PREFIX.  Returns an identifier.  */

static GTY(()) unsigned int tmp_var_id_num;

tree
create_tmp_var_name (const char *prefix)
{
  char *tmp_name;

  if (prefix)
    {
      char *preftmp = ASTRDUP (prefix);

      remove_suffix (preftmp, strlen (preftmp));
      prefix = preftmp;
    }

  ASM_FORMAT_PRIVATE_NAME (tmp_name, prefix ? prefix : "T", tmp_var_id_num++);
  return get_identifier (tmp_name);
}


/* Create a new temporary variable declaration of type TYPE.
   Does NOT push it into the current binding.  */

tree
create_tmp_var_raw (tree type, const char *prefix)
{
  tree tmp_var;
  tree new_type;

  /* Make the type of the variable writable.  */
  new_type = build_type_variant (type, 0, 0);
  TYPE_ATTRIBUTES (new_type) = TYPE_ATTRIBUTES (type);

  tmp_var = build_decl (input_location,
                        VAR_DECL, prefix ? create_tmp_var_name (prefix) : NULL,
                        type);

  /* The variable was declared by the compiler.  */
  DECL_ARTIFICIAL (tmp_var) = 1;
  /* And we don't want debug info for it.  */
  DECL_IGNORED_P (tmp_var) = 1;

  /* Make the variable writable.  */
  TREE_READONLY (tmp_var) = 0;

  DECL_EXTERNAL (tmp_var) = 0;
  TREE_STATIC (tmp_var) = 0;
  TREE_USED (tmp_var) = 1;

  return tmp_var;
}

/* Create a new temporary variable declaration of type TYPE.  DOES push the
   variable into the current binding.  Further, assume that this is called
   only from gimplification or optimization, at which point the creation of
   certain types are bugs.  */

tree
create_tmp_var (tree type, const char *prefix)
{
  tree tmp_var;

  /* We don't allow types that are addressable (meaning we can't make copies),
     or incomplete.  We also used to reject every variable size objects here,
     but now support those for which a constant upper bound can be obtained.
     The processing for variable sizes is performed in gimple_add_tmp_var,
     point at which it really matters and possibly reached via paths not going
     through this function, e.g. after direct calls to create_tmp_var_raw.  */
  gcc_assert (!TREE_ADDRESSABLE (type) && COMPLETE_TYPE_P (type));

  tmp_var = create_tmp_var_raw (type, prefix);
  gimple_add_tmp_var (tmp_var);
  return tmp_var;
}

/* Create a new temporary variable declaration of type TYPE by calling
   create_tmp_var and if TYPE is a vector or a complex number, mark the new
   temporary as gimple register.  */

tree
create_tmp_reg (tree type, const char *prefix)
{
  tree tmp;

  tmp = create_tmp_var (type, prefix);
  if (TREE_CODE (type) == COMPLEX_TYPE
      || TREE_CODE (type) == VECTOR_TYPE)
    DECL_GIMPLE_REG_P (tmp) = 1;

  return tmp;
}

/* Create a temporary with a name derived from VAL.  Subroutine of
   lookup_tmp_var; nobody else should call this function.  */

static inline tree
create_tmp_from_val (tree val)
{
  return create_tmp_var (TREE_TYPE (val), get_name (val));
}

/* Create a temporary to hold the value of VAL.  If IS_FORMAL, try to reuse
   an existing expression temporary.  */

static tree
lookup_tmp_var (tree val, bool is_formal)
{
  tree ret;

  /* If not optimizing, never really reuse a temporary.  local-alloc
     won't allocate any variable that is used in more than one basic
     block, which means it will go into memory, causing much extra
     work in reload and final and poorer code generation, outweighing
     the extra memory allocation here.  */
  if (!optimize || !is_formal || TREE_SIDE_EFFECTS (val))
    ret = create_tmp_from_val (val);
  else
    {
      elt_t elt, *elt_p;
      void **slot;

      elt.val = val;
      if (gimplify_ctxp->temp_htab == NULL)
        gimplify_ctxp->temp_htab
          = htab_create (1000, gimple_tree_hash, gimple_tree_eq, free);
      slot = htab_find_slot (gimplify_ctxp->temp_htab, (void *)&elt, INSERT);
      if (*slot == NULL)
        {
          elt_p = XNEW (elt_t);
          elt_p->val = val;
          elt_p->temp = ret = create_tmp_from_val (val);
          *slot = (void *) elt_p;
        }
      else
        {
          elt_p = (elt_t *) *slot;
          ret = elt_p->temp;
        }
    }

  return ret;
}


/* Return true if T is a CALL_EXPR or an expression that can be
   assignmed to a temporary.  Note that this predicate should only be
   used during gimplification.  See the rationale for this in
   gimplify_modify_expr.  */

static bool
is_gimple_reg_rhs_or_call (tree t)
{
  return (get_gimple_rhs_class (TREE_CODE (t)) != GIMPLE_INVALID_RHS
          || TREE_CODE (t) == CALL_EXPR);
}

/* Return true if T is a valid memory RHS or a CALL_EXPR.  Note that
   this predicate should only be used during gimplification.  See the
   rationale for this in gimplify_modify_expr.  */

static bool
is_gimple_mem_rhs_or_call (tree t)
{
  /* If we're dealing with a renamable type, either source or dest must be
     a renamed variable.  */
  if (is_gimple_reg_type (TREE_TYPE (t)))
    return is_gimple_val (t);
  else
    return (is_gimple_val (t) || is_gimple_lvalue (t)
            || TREE_CODE (t) == CALL_EXPR);
}

/* Helper for get_formal_tmp_var and get_initialized_tmp_var.  */

static tree
internal_get_tmp_var (tree val, gimple_seq *pre_p, gimple_seq *post_p,
                      bool is_formal)
{
  tree t, mod;

  /* Notice that we explicitly allow VAL to be a CALL_EXPR so that we
     can create an INIT_EXPR and convert it into a GIMPLE_CALL below.  */
  gimplify_expr (&val, pre_p, post_p, is_gimple_reg_rhs_or_call,
                 fb_rvalue);

  t = lookup_tmp_var (val, is_formal);

  if (is_formal
      && (TREE_CODE (TREE_TYPE (t)) == COMPLEX_TYPE
          || TREE_CODE (TREE_TYPE (t)) == VECTOR_TYPE))
    DECL_GIMPLE_REG_P (t) = 1;

  mod = build2 (INIT_EXPR, TREE_TYPE (t), t, unshare_expr (val));

  if (EXPR_HAS_LOCATION (val))
    SET_EXPR_LOCATION (mod, EXPR_LOCATION (val));
  else
    SET_EXPR_LOCATION (mod, input_location);

  /* gimplify_modify_expr might want to reduce this further.  */
  gimplify_and_add (mod, pre_p);
  ggc_free (mod);

  /* If we're gimplifying into ssa, gimplify_modify_expr will have
     given our temporary an SSA name.  Find and return it.  */
  if (gimplify_ctxp->into_ssa)
    {
      gimple last = gimple_seq_last_stmt (*pre_p);
      t = gimple_get_lhs (last);
    }

  return t;
}

/* Returns a formal temporary variable initialized with VAL.  PRE_P is as
   in gimplify_expr.  Only use this function if:

   1) The value of the unfactored expression represented by VAL will not
      change between the initialization and use of the temporary, and
   2) The temporary will not be otherwise modified.

   For instance, #1 means that this is inappropriate for SAVE_EXPR temps,
   and #2 means it is inappropriate for && temps.

   For other cases, use get_initialized_tmp_var instead.  */

tree
get_formal_tmp_var (tree val, gimple_seq *pre_p)
{
  return internal_get_tmp_var (val, pre_p, NULL, true);
}

/* Returns a temporary variable initialized with VAL.  PRE_P and POST_P
   are as in gimplify_expr.  */

tree
get_initialized_tmp_var (tree val, gimple_seq *pre_p, gimple_seq *post_p)
{
  return internal_get_tmp_var (val, pre_p, post_p, false);
}

/* Declares all the variables in VARS in SCOPE.  If DEBUG_INFO is
   true, generate debug info for them; otherwise don't.  */

void
declare_vars (tree vars, gimple scope, bool debug_info)
{
  tree last = vars;
  if (last)
    {
      tree temps, block;

      gcc_assert (gimple_code (scope) == GIMPLE_BIND);

      temps = nreverse (last);

      block = gimple_bind_block (scope);
      gcc_assert (!block || TREE_CODE (block) == BLOCK);
      if (!block || !debug_info)
        {
          TREE_CHAIN (last) = gimple_bind_vars (scope);
          gimple_bind_set_vars (scope, temps);
        }
      else
        {
          /* We need to attach the nodes both to the BIND_EXPR and to its
             associated BLOCK for debugging purposes.  The key point here
             is that the BLOCK_VARS of the BIND_EXPR_BLOCK of a BIND_EXPR
             is a subchain of the BIND_EXPR_VARS of the BIND_EXPR.  */
          if (BLOCK_VARS (block))
            BLOCK_VARS (block) = chainon (BLOCK_VARS (block), temps);
          else
            {
              gimple_bind_set_vars (scope,
                                    chainon (gimple_bind_vars (scope), temps));
              BLOCK_VARS (block) = temps;
            }
        }
    }
}

/* For VAR a VAR_DECL of variable size, try to find a constant upper bound
   for the size and adjust DECL_SIZE/DECL_SIZE_UNIT accordingly.  Abort if
   no such upper bound can be obtained.  */

static void
force_constant_size (tree var)
{
  /* The only attempt we make is by querying the maximum size of objects
     of the variable's type.  */

  HOST_WIDE_INT max_size;

  gcc_assert (TREE_CODE (var) == VAR_DECL);

  max_size = max_int_size_in_bytes (TREE_TYPE (var));

  gcc_assert (max_size >= 0);

  DECL_SIZE_UNIT (var)
    = build_int_cst (TREE_TYPE (DECL_SIZE_UNIT (var)), max_size);
  DECL_SIZE (var)
    = build_int_cst (TREE_TYPE (DECL_SIZE (var)), max_size * BITS_PER_UNIT);
}

void
gimple_add_tmp_var (tree tmp)
{
  gcc_assert (!TREE_CHAIN (tmp) && !DECL_SEEN_IN_BIND_EXPR_P (tmp));

  /* Later processing assumes that the object size is constant, which might
     not be true at this point.  Force the use of a constant upper bound in
     this case.  */
  if (!host_integerp (DECL_SIZE_UNIT (tmp), 1))
    force_constant_size (tmp);

  DECL_CONTEXT (tmp) = current_function_decl;
  DECL_SEEN_IN_BIND_EXPR_P (tmp) = 1;

  if (gimplify_ctxp)
    {
      TREE_CHAIN (tmp) = gimplify_ctxp->temps;
      gimplify_ctxp->temps = tmp;

      /* Mark temporaries local within the nearest enclosing parallel.  */
      if (gimplify_omp_ctxp)
        {
          struct gimplify_omp_ctx *ctx = gimplify_omp_ctxp;
          while (ctx && ctx->region_type == ORT_WORKSHARE)
            ctx = ctx->outer_context;
          if (ctx)
            omp_add_variable (ctx, tmp, GOVD_LOCAL | GOVD_SEEN);
        }
    }
  else if (cfun)
    record_vars (tmp);
  else
    {
      gimple_seq body_seq;

      /* This case is for nested functions.  We need to expose the locals
         they create.  */
      body_seq = gimple_body (current_function_decl);
      declare_vars (tmp, gimple_seq_first_stmt (body_seq), false);
    }
}

/* Determines whether to assign a location to the statement GS.  */

static bool
should_carry_location_p (gimple gs)
{
  /* Don't emit a line note for a label.  We particularly don't want to
     emit one for the break label, since it doesn't actually correspond
     to the beginning of the loop/switch.  */
  if (gimple_code (gs) == GIMPLE_LABEL)
    return false;

  return true;
}


/* Return true if a location should not be emitted for this statement
   by annotate_one_with_location.  */

static inline bool
gimple_do_not_emit_location_p (gimple g)
{
  return gimple_plf (g, GF_PLF_1);
}

/* Mark statement G so a location will not be emitted by
   annotate_one_with_location.  */

static inline void
gimple_set_do_not_emit_location (gimple g)
{
  /* The PLF flags are initialized to 0 when a new tuple is created,
     so no need to initialize it anywhere.  */
  gimple_set_plf (g, GF_PLF_1, true);
}

/* Set the location for gimple statement GS to LOCATION.  */

static void
annotate_one_with_location (gimple gs, location_t location)
{
  if (!gimple_has_location (gs)
      && !gimple_do_not_emit_location_p (gs)
      && should_carry_location_p (gs))
    gimple_set_location (gs, location);
}


/* Set LOCATION for all the statements after iterator GSI in sequence
   SEQ.  If GSI is pointing to the end of the sequence, start with the
   first statement in SEQ.  */

static void
annotate_all_with_location_after (gimple_seq seq, gimple_stmt_iterator gsi,
                                  location_t location)
{
  if (gsi_end_p (gsi))
    gsi = gsi_start (seq);
  else
    gsi_next (&gsi);

  for (; !gsi_end_p (gsi); gsi_next (&gsi))
    annotate_one_with_location (gsi_stmt (gsi), location);
}


/* Set the location for all the statements in a sequence STMT_P to LOCATION.  */

void
annotate_all_with_location (gimple_seq stmt_p, location_t location)
{
  gimple_stmt_iterator i;

  if (gimple_seq_empty_p (stmt_p))
    return;

  for (i = gsi_start (stmt_p); !gsi_end_p (i); gsi_next (&i))
    {
      gimple gs = gsi_stmt (i);
      annotate_one_with_location (gs, location);
    }
}


/* Similar to copy_tree_r() but do not copy SAVE_EXPR or TARGET_EXPR nodes.
   These nodes model computations that should only be done once.  If we
   were to unshare something like SAVE_EXPR(i++), the gimplification
   process would create wrong code.  */

static tree
mostly_copy_tree_r (tree *tp, int *walk_subtrees, void *data)
{
  enum tree_code code = TREE_CODE (*tp);
  /* Don't unshare types, decls, constants and SAVE_EXPR nodes.  */
  if (TREE_CODE_CLASS (code) == tcc_type
      || TREE_CODE_CLASS (code) == tcc_declaration
      || TREE_CODE_CLASS (code) == tcc_constant
      || code == SAVE_EXPR || code == TARGET_EXPR
      /* We can't do anything sensible with a BLOCK used as an expression,
         but we also can't just die when we see it because of non-expression
         uses.  So just avert our eyes and cross our fingers.  Silly Java.  */
      || code == BLOCK)
    *walk_subtrees = 0;
  else
    {
      gcc_assert (code != BIND_EXPR);
      copy_tree_r (tp, walk_subtrees, data);
    }

  return NULL_TREE;
}

/* Callback for walk_tree to unshare most of the shared trees rooted at
   *TP.  If *TP has been visited already (i.e., TREE_VISITED (*TP) == 1),
   then *TP is deep copied by calling copy_tree_r.

   This unshares the same trees as copy_tree_r with the exception of
   SAVE_EXPR nodes.  These nodes model computations that should only be
   done once.  If we were to unshare something like SAVE_EXPR(i++), the
   gimplification process would create wrong code.  */

static tree
copy_if_shared_r (tree *tp, int *walk_subtrees ATTRIBUTE_UNUSED,
                  void *data ATTRIBUTE_UNUSED)
{
  tree t = *tp;
  enum tree_code code = TREE_CODE (t);

  /* Skip types, decls, and constants.  But we do want to look at their
     types and the bounds of types.  Mark them as visited so we properly
     unmark their subtrees on the unmark pass.  If we've already seen them,
     don't look down further.  */
  if (TREE_CODE_CLASS (code) == tcc_type
      || TREE_CODE_CLASS (code) == tcc_declaration
      || TREE_CODE_CLASS (code) == tcc_constant)
    {
      if (TREE_VISITED (t))
        *walk_subtrees = 0;
      else
        TREE_VISITED (t) = 1;
    }

  /* If this node has been visited already, unshare it and don't look
     any deeper.  */
  else if (TREE_VISITED (t))
    {
      walk_tree (tp, mostly_copy_tree_r, NULL, NULL);
      *walk_subtrees = 0;
    }

  /* Otherwise, mark the tree as visited and keep looking.  */
  else
    TREE_VISITED (t) = 1;

  return NULL_TREE;
}

static tree
unmark_visited_r (tree *tp, int *walk_subtrees ATTRIBUTE_UNUSED,
                  void *data ATTRIBUTE_UNUSED)
{
  if (TREE_VISITED (*tp))
    TREE_VISITED (*tp) = 0;
  else
    *walk_subtrees = 0;

  return NULL_TREE;
}

/* Unshare all the trees in BODY_P, a pointer into the body of FNDECL, and the
   bodies of any nested functions if we are unsharing the entire body of
   FNDECL.  */

static void
unshare_body (tree *body_p, tree fndecl)
{
  struct cgraph_node *cgn = cgraph_node (fndecl);

  walk_tree (body_p, copy_if_shared_r, NULL, NULL);
  if (body_p == &DECL_SAVED_TREE (fndecl))
    for (cgn = cgn->nested; cgn; cgn = cgn->next_nested)
      unshare_body (&DECL_SAVED_TREE (cgn->decl), cgn->decl);
}

/* Likewise, but mark all trees as not visited.  */

static void
unvisit_body (tree *body_p, tree fndecl)
{
  struct cgraph_node *cgn = cgraph_node (fndecl);

  walk_tree (body_p, unmark_visited_r, NULL, NULL);
  if (body_p == &DECL_SAVED_TREE (fndecl))
    for (cgn = cgn->nested; cgn; cgn = cgn->next_nested)
      unvisit_body (&DECL_SAVED_TREE (cgn->decl), cgn->decl);
}

/* Unconditionally make an unshared copy of EXPR.  This is used when using
   stored expressions which span multiple functions, such as BINFO_VTABLE,
   as the normal unsharing process can't tell that they're shared.  */

tree
unshare_expr (tree expr)
{
  walk_tree (&expr, mostly_copy_tree_r, NULL, NULL);
  return expr;
}
\f
/* WRAPPER is a code such as BIND_EXPR or CLEANUP_POINT_EXPR which can both
   contain statements and have a value.  Assign its value to a temporary
   and give it void_type_node.  Returns the temporary, or NULL_TREE if
   WRAPPER was already void.  */

tree
voidify_wrapper_expr (tree wrapper, tree temp)
{
  tree type = TREE_TYPE (wrapper);
  if (type && !VOID_TYPE_P (type))
    {
      tree *p;

      /* Set p to point to the body of the wrapper.  Loop until we find
         something that isn't a wrapper.  */
      for (p = &wrapper; p && *p; )
        {
          switch (TREE_CODE (*p))
            {
            case BIND_EXPR:
              TREE_SIDE_EFFECTS (*p) = 1;
              TREE_TYPE (*p) = void_type_node;
              /* For a BIND_EXPR, the body is operand 1.  */
              p = &BIND_EXPR_BODY (*p);
              break;

            case CLEANUP_POINT_EXPR:
            case TRY_FINALLY_EXPR:
            case TRY_CATCH_EXPR:
              TREE_SIDE_EFFECTS (*p) = 1;
              TREE_TYPE (*p) = void_type_node;
              p = &TREE_OPERAND (*p, 0);
              break;

            case STATEMENT_LIST:
              {
                tree_stmt_iterator i = tsi_last (*p);
                TREE_SIDE_EFFECTS (*p) = 1;
                TREE_TYPE (*p) = void_type_node;
                p = tsi_end_p (i) ? NULL : tsi_stmt_ptr (i);
              }
              break;

            case COMPOUND_EXPR:
              /* Advance to the last statement.  Set all container types to void.  */
              for (; TREE_CODE (*p) == COMPOUND_EXPR; p = &TREE_OPERAND (*p, 1))
                {
                  TREE_SIDE_EFFECTS (*p) = 1;
                  TREE_TYPE (*p) = void_type_node;
                }
              break;

            default:
              goto out;
            }
        }

    out:
      if (p == NULL || IS_EMPTY_STMT (*p))
        temp = NULL_TREE;
      else if (temp)
        {
          /* The wrapper is on the RHS of an assignment that we're pushing
             down.  */
          gcc_assert (TREE_CODE (temp) == INIT_EXPR
                      || TREE_CODE (temp) == MODIFY_EXPR);
          TREE_OPERAND (temp, 1) = *p;
          *p = temp;
        }
      else
        {
          temp = create_tmp_var (type, "retval");
          *p = build2 (INIT_EXPR, type, temp, *p);
        }

      return temp;
    }

  return NULL_TREE;
}

/* Prepare calls to builtins to SAVE and RESTORE the stack as well as
   a temporary through which they communicate.  */

static void
build_stack_save_restore (gimple *save, gimple *restore)
{
  tree tmp_var;

  *save = gimple_build_call (implicit_built_in_decls[BUILT_IN_STACK_SAVE], 0);
  tmp_var = create_tmp_var (ptr_type_node, "saved_stack");
  gimple_call_set_lhs (*save, tmp_var);

  *restore = gimple_build_call (implicit_built_in_decls[BUILT_IN_STACK_RESTORE],
                            1, tmp_var);
}

/* Gimplify a BIND_EXPR.  Just voidify and recurse.  */

static enum gimplify_status
gimplify_bind_expr (tree *expr_p, gimple_seq *pre_p)
{
  tree bind_expr = *expr_p;
  bool old_save_stack = gimplify_ctxp->save_stack;
  tree t;
  gimple gimple_bind;
  gimple_seq body;

  tree temp = voidify_wrapper_expr (bind_expr, NULL);

  /* Mark variables seen in this bind expr.  */
  for (t = BIND_EXPR_VARS (bind_expr); t ; t = TREE_CHAIN (t))
    {
      if (TREE_CODE (t) == VAR_DECL)
        {
          struct gimplify_omp_ctx *ctx = gimplify_omp_ctxp;

          /* Mark variable as local.  */
          if (ctx && !is_global_var (t)
              && (! DECL_SEEN_IN_BIND_EXPR_P (t)
                  || splay_tree_lookup (ctx->variables,
                                        (splay_tree_key) t) == NULL))
            omp_add_variable (gimplify_omp_ctxp, t, GOVD_LOCAL | GOVD_SEEN);

          DECL_SEEN_IN_BIND_EXPR_P (t) = 1;

          if (DECL_HARD_REGISTER (t) && !is_global_var (t) && cfun)
            cfun->has_local_explicit_reg_vars = true;
        }

      /* Preliminarily mark non-addressed complex variables as eligible
         for promotion to gimple registers.  We'll transform their uses
         as we find them.
         We exclude complex types if not optimizing because they can be
         subject to partial stores in GNU C by means of the __real__ and
         __imag__ operators and we cannot promote them to total stores
         (see gimplify_modify_expr_complex_part).  */
      if (optimize
          && (TREE_CODE (TREE_TYPE (t)) == COMPLEX_TYPE
              || TREE_CODE (TREE_TYPE (t)) == VECTOR_TYPE)
          && !TREE_THIS_VOLATILE (t)
          && (TREE_CODE (t) == VAR_DECL && !DECL_HARD_REGISTER (t))
          && !needs_to_live_in_memory (t))
        DECL_GIMPLE_REG_P (t) = 1;
    }

  gimple_bind = gimple_build_bind (BIND_EXPR_VARS (bind_expr), NULL,
                                   BIND_EXPR_BLOCK (bind_expr));
  gimple_push_bind_expr (gimple_bind);

  gimplify_ctxp->save_stack = false;

  /* Gimplify the body into the GIMPLE_BIND tuple's body.  */
  body = NULL;
  gimplify_stmt (&BIND_EXPR_BODY (bind_expr), &body);
  gimple_bind_set_body (gimple_bind, body);

  if (gimplify_ctxp->save_stack)
    {
      gimple stack_save, stack_restore, gs;
      gimple_seq cleanup, new_body;

      /* Save stack on entry and restore it on exit.  Add a try_finally
         block to achieve this.  Note that mudflap depends on the
         format of the emitted code: see mx_register_decls().  */
      build_stack_save_restore (&stack_save, &stack_restore);

      cleanup = new_body = NULL;
      gimplify_seq_add_stmt (&cleanup, stack_restore);
      gs = gimple_build_try (gimple_bind_body (gimple_bind), cleanup,
                             GIMPLE_TRY_FINALLY);

      gimplify_seq_add_stmt (&new_body, stack_save);
      gimplify_seq_add_stmt (&new_body, gs);
      gimple_bind_set_body (gimple_bind, new_body);
    }

  gimplify_ctxp->save_stack = old_save_stack;
  gimple_pop_bind_expr ();

  gimplify_seq_add_stmt (pre_p, gimple_bind);

  if (temp)
    {
      *expr_p = temp;
      return GS_OK;
    }

  *expr_p = NULL_TREE;
  return GS_ALL_DONE;
}

/* Gimplify a RETURN_EXPR.  If the expression to be returned is not a
   GIMPLE value, it is assigned to a new temporary and the statement is
   re-written to return the temporary.

   PRE_P points to the sequence where side effects that must happen before
   STMT should be stored.  */

static enum gimplify_status
gimplify_return_expr (tree stmt, gimple_seq *pre_p)
{
  gimple ret;
  tree ret_expr = TREE_OPERAND (stmt, 0);
  tree result_decl, result;

  if (ret_expr == error_mark_node)
    return GS_ERROR;

  if (!ret_expr
      || TREE_CODE (ret_expr) == RESULT_DECL
      || ret_expr == error_mark_node)
    {
      gimple ret = gimple_build_return (ret_expr);
      gimple_set_no_warning (ret, TREE_NO_WARNING (stmt));
      gimplify_seq_add_stmt (pre_p, ret);
      return GS_ALL_DONE;
    }

  if (VOID_TYPE_P (TREE_TYPE (TREE_TYPE (current_function_decl))))
    result_decl = NULL_TREE;
  else
    {
      result_decl = TREE_OPERAND (ret_expr, 0);

      /* See through a return by reference.  */
      if (TREE_CODE (result_decl) == INDIRECT_REF)
        result_decl = TREE_OPERAND (result_decl, 0);

      gcc_assert ((TREE_CODE (ret_expr) == MODIFY_EXPR
                   || TREE_CODE (ret_expr) == INIT_EXPR)
                  && TREE_CODE (result_decl) == RESULT_DECL);
    }

  /* If aggregate_value_p is true, then we can return the bare RESULT_DECL.
     Recall that aggregate_value_p is FALSE for any aggregate type that is
     returned in registers.  If we're returning values in registers, then
     we don't want to extend the lifetime of the RESULT_DECL, particularly
     across another call.  In addition, for those aggregates for which
     hard_function_value generates a PARALLEL, we'll die during normal
     expansion of structure assignments; there's special code in expand_return
     to handle this case that does not exist in expand_expr.  */
  if (!result_decl)
    result = NULL_TREE;
  else if (aggregate_value_p (result_decl, TREE_TYPE (current_function_decl)))
    {
      if (TREE_CODE (DECL_SIZE (result_decl)) != INTEGER_CST)
        {
          if (!TYPE_SIZES_GIMPLIFIED (TREE_TYPE (result_decl)))
            gimplify_type_sizes (TREE_TYPE (result_decl), pre_p);
          /* Note that we don't use gimplify_vla_decl because the RESULT_DECL
             should be effectively allocated by the caller, i.e. all calls to
             this function must be subject to the Return Slot Optimization.  */
          gimplify_one_sizepos (&DECL_SIZE (result_decl), pre_p);
          gimplify_one_sizepos (&DECL_SIZE_UNIT (result_decl), pre_p);
        }
      result = result_decl;
    }
  else if (gimplify_ctxp->return_temp)
    result = gimplify_ctxp->return_temp;
  else
    {
      result = create_tmp_reg (TREE_TYPE (result_decl), NULL);

      /* ??? With complex control flow (usually involving abnormal edges),
         we can wind up warning about an uninitialized value for this.  Due
         to how this variable is constructed and initialized, this is never
         true.  Give up and never warn.  */
      TREE_NO_WARNING (result) = 1;

      gimplify_ctxp->return_temp = result;
    }

  /* Smash the lhs of the MODIFY_EXPR to the temporary we plan to use.
     Then gimplify the whole thing.  */
  if (result != result_decl)
    TREE_OPERAND (ret_expr, 0) = result;

  gimplify_and_add (TREE_OPERAND (stmt, 0), pre_p);

  ret = gimple_build_return (result);
  gimple_set_no_warning (ret, TREE_NO_WARNING (stmt));
  gimplify_seq_add_stmt (pre_p, ret);

  return GS_ALL_DONE;
}

static void
gimplify_vla_decl (tree decl, gimple_seq *seq_p)
{
  /* This is a variable-sized decl.  Simplify its size and mark it
     for deferred expansion.  Note that mudflap depends on the format
     of the emitted code: see mx_register_decls().  */
  tree t, addr, ptr_type;

  gimplify_one_sizepos (&DECL_SIZE (decl), seq_p);
  gimplify_one_sizepos (&DECL_SIZE_UNIT (decl), seq_p);

  /* All occurrences of this decl in final gimplified code will be
     replaced by indirection.  Setting DECL_VALUE_EXPR does two
     things: First, it lets the rest of the gimplifier know what
     replacement to use.  Second, it lets the debug info know
     where to find the value.  */
  ptr_type = build_pointer_type (TREE_TYPE (decl));
  addr = create_tmp_var (ptr_type, get_name (decl));
  DECL_IGNORED_P (addr) = 0;
  t = build_fold_indirect_ref (addr);
  SET_DECL_VALUE_EXPR (decl, t);
  DECL_HAS_VALUE_EXPR_P (decl) = 1;

  t = built_in_decls[BUILT_IN_ALLOCA];
  t = build_call_expr (t, 1, DECL_SIZE_UNIT (decl));
  t = fold_convert (ptr_type, t);
  t = build2 (MODIFY_EXPR, TREE_TYPE (addr), addr, t);

  gimplify_and_add (t, seq_p);

  /* Indicate that we need to restore the stack level when the
     enclosing BIND_EXPR is exited.  */
  gimplify_ctxp->save_stack = true;
}


/* Gimplifies a DECL_EXPR node *STMT_P by making any necessary allocation
   and initialization explicit.  */

static enum gimplify_status
gimplify_decl_expr (tree *stmt_p, gimple_seq *seq_p)
{
  tree stmt = *stmt_p;
  tree decl = DECL_EXPR_DECL (stmt);

  *stmt_p = NULL_TREE;

  if (TREE_TYPE (decl) == error_mark_node)
    return GS_ERROR;

  if ((TREE_CODE (decl) == TYPE_DECL
       || TREE_CODE (decl) == VAR_DECL)
      && !TYPE_SIZES_GIMPLIFIED (TREE_TYPE (decl)))
    gimplify_type_sizes (TREE_TYPE (decl), seq_p);

  if (TREE_CODE (decl) == VAR_DECL && !DECL_EXTERNAL (decl))
    {
      tree init = DECL_INITIAL (decl);

      if (TREE_CODE (DECL_SIZE_UNIT (decl)) != INTEGER_CST
          || (!TREE_STATIC (decl)
              && flag_stack_check == GENERIC_STACK_CHECK
              && compare_tree_int (DECL_SIZE_UNIT (decl),
                                   STACK_CHECK_MAX_VAR_SIZE) > 0))
        gimplify_vla_decl (decl, seq_p);

      if (init && init != error_mark_node)
        {
          if (!TREE_STATIC (decl))
            {
              DECL_INITIAL (decl) = NULL_TREE;
              init = build2 (INIT_EXPR, void_type_node, decl, init);
              gimplify_and_add (init, seq_p);
              ggc_free (init);
            }
          else
            /* We must still examine initializers for static variables
               as they may contain a label address.  */
            walk_tree (&init, force_labels_r, NULL, NULL);
        }

      /* Some front ends do not explicitly declare all anonymous
         artificial variables.  We compensate here by declaring the
         variables, though it would be better if the front ends would
         explicitly declare them.  */
      if (!DECL_SEEN_IN_BIND_EXPR_P (decl)
          && DECL_ARTIFICIAL (decl) && DECL_NAME (decl) == NULL_TREE)
        gimple_add_tmp_var (decl);
    }

  return GS_ALL_DONE;
}

/* Gimplify a LOOP_EXPR.  Normally this just involves gimplifying the body
   and replacing the LOOP_EXPR with goto, but if the loop contains an
   EXIT_EXPR, we need to append a label for it to jump to.  */

static enum gimplify_status
gimplify_loop_expr (tree *expr_p, gimple_seq *pre_p)
{
  tree saved_label = gimplify_ctxp->exit_label;
  tree start_label = create_artificial_label (UNKNOWN_LOCATION);

  gimplify_seq_add_stmt (pre_p, gimple_build_label (start_label));

  gimplify_ctxp->exit_label = NULL_TREE;

  gimplify_and_add (LOOP_EXPR_BODY (*expr_p), pre_p);

  gimplify_seq_add_stmt (pre_p, gimple_build_goto (start_label));

  if (gimplify_ctxp->exit_label)
    gimplify_seq_add_stmt (pre_p, gimple_build_label (gimplify_ctxp->exit_label));

  gimplify_ctxp->exit_label = saved_label;

  *expr_p = NULL;
  return GS_ALL_DONE;
}

/* Gimplifies a statement list onto a sequence.  These may be created either
   by an enlightened front-end, or by shortcut_cond_expr.  */

static enum gimplify_status
gimplify_statement_list (tree *expr_p, gimple_seq *pre_p)
{
  tree temp = voidify_wrapper_expr (*expr_p, NULL);

  tree_stmt_iterator i = tsi_start (*expr_p);

  while (!tsi_end_p (i))
    {
      gimplify_stmt (tsi_stmt_ptr (i), pre_p);
      tsi_delink (&i);
    }

  if (temp)
    {
      *expr_p = temp;
      return GS_OK;
    }

  return GS_ALL_DONE;
}

/* Compare two case labels.  Because the front end should already have
   made sure that case ranges do not overlap, it is enough to only compare
   the CASE_LOW values of each case label.  */

static int
compare_case_labels (const void *p1, const void *p2)
{
  const_tree const case1 = *(const_tree const*)p1;
  const_tree const case2 = *(const_tree const*)p2;

  /* The 'default' case label always goes first.  */
  if (!CASE_LOW (case1))
    return -1;
  else if (!CASE_LOW (case2))
    return 1;
  else
    return tree_int_cst_compare (CASE_LOW (case1), CASE_LOW (case2));
}


/* Sort the case labels in LABEL_VEC in place in ascending order.  */

void
sort_case_labels (VEC(tree,heap)* label_vec)
{
  size_t len = VEC_length (tree, label_vec);
  qsort (VEC_address (tree, label_vec), len, sizeof (tree),
         compare_case_labels);
}


/* Gimplify a SWITCH_EXPR, and collect a TREE_VEC of the labels it can
   branch to.  */

static enum gimplify_status
gimplify_switch_expr (tree *expr_p, gimple_seq *pre_p)
{
  tree switch_expr = *expr_p;
  gimple_seq switch_body_seq = NULL;
  enum gimplify_status ret;

  ret = gimplify_expr (&SWITCH_COND (switch_expr), pre_p, NULL, is_gimple_val,
                       fb_rvalue);
  if (ret == GS_ERROR || ret == GS_UNHANDLED)
    return ret;

  if (SWITCH_BODY (switch_expr))
    {
      VEC (tree,heap) *labels;
      VEC (tree,heap) *saved_labels;
      tree default_case = NULL_TREE;
      size_t i, len;
      gimple gimple_switch;

      /* If someone can be bothered to fill in the labels, they can
         be bothered to null out the body too.  */
      gcc_assert (!SWITCH_LABELS (switch_expr));

      /* save old labels, get new ones from body, then restore the old
         labels.  Save all the things from the switch body to append after.  */
      saved_labels = gimplify_ctxp->case_labels;
      gimplify_ctxp->case_labels = VEC_alloc (tree, heap, 8);

      gimplify_stmt (&SWITCH_BODY (switch_expr), &switch_body_seq);
      labels = gimplify_ctxp->case_labels;
      gimplify_ctxp->case_labels = saved_labels;

      i = 0;
      while (i < VEC_length (tree, labels))
        {
          tree elt = VEC_index (tree, labels, i);
          tree low = CASE_LOW (elt);
          bool remove_element = FALSE;

          if (low)
            {
              /* Discard empty ranges.  */
              tree high = CASE_HIGH (elt);
              if (high && tree_int_cst_lt (high, low))
                remove_element = TRUE;
            }
          else
            {
              /* The default case must be the last label in the list.  */
              gcc_assert (!default_case);
              default_case = elt;
              remove_element = TRUE;
            }

          if (remove_element)
            VEC_ordered_remove (tree, labels, i);
          else
            i++;
        }
      len = i;

      if (!VEC_empty (tree, labels))
        sort_case_labels (labels);

      if (!default_case)
        {
          tree type = TREE_TYPE (switch_expr);

          /* If the switch has no default label, add one, so that we jump
             around the switch body.  If the labels already cover the whole
             range of type, add the default label pointing to one of the
             existing labels.  */
          if (type == void_type_node)
            type = TREE_TYPE (SWITCH_COND (switch_expr));
          if (len
              && INTEGRAL_TYPE_P (type)
              && TYPE_MIN_VALUE (type)
              && TYPE_MAX_VALUE (type)
              && tree_int_cst_equal (CASE_LOW (VEC_index (tree, labels, 0)),
                                     TYPE_MIN_VALUE (type)))
            {
              tree low, high = CASE_HIGH (VEC_index (tree, labels, len - 1));
              if (!high)
                high = CASE_LOW (VEC_index (tree, labels, len - 1));
              if (tree_int_cst_equal (high, TYPE_MAX_VALUE (type)))
                {
                  for (i = 1; i < len; i++)
                    {
                      high = CASE_LOW (VEC_index (tree, labels, i));
                      low = CASE_HIGH (VEC_index (tree, labels, i - 1));
                      if (!low)
                        low = CASE_LOW (VEC_index (tree, labels, i - 1));
                      if ((TREE_INT_CST_LOW (low) + 1
                           != TREE_INT_CST_LOW (high))
                          || (TREE_INT_CST_HIGH (low)
                              + (TREE_INT_CST_LOW (high) == 0)
                              != TREE_INT_CST_HIGH (high)))
                        break;
                    }
                  if (i == len)
                    default_case = build3 (CASE_LABEL_EXPR, void_type_node,
                                           NULL_TREE, NULL_TREE,
                                           CASE_LABEL (VEC_index (tree,
                                                                  labels, 0)));
                }
            }

          if (!default_case)
            {
              gimple new_default;

              default_case
                = build3 (CASE_LABEL_EXPR, void_type_node,
                          NULL_TREE, NULL_TREE,
                          create_artificial_label (UNKNOWN_LOCATION));
              new_default = gimple_build_label (CASE_LABEL (default_case));
              gimplify_seq_add_stmt (&switch_body_seq, new_default);
            }
        }

      gimple_switch = gimple_build_switch_vec (SWITCH_COND (switch_expr),
                                               default_case, labels);
      gimplify_seq_add_stmt (pre_p, gimple_switch);
      gimplify_seq_add_seq (pre_p, switch_body_seq);
      VEC_free(tree, heap, labels);
    }
  else
    gcc_assert (SWITCH_LABELS (switch_expr));

  return GS_ALL_DONE;
}


static enum gimplify_status
gimplify_case_label_expr (tree *expr_p, gimple_seq *pre_p)
{
  struct gimplify_ctx *ctxp;
  gimple gimple_label;

  /* Invalid OpenMP programs can play Duff's Device type games with
     #pragma omp parallel.  At least in the C front end, we don't
     detect such invalid branches until after gimplification.  */
  for (ctxp = gimplify_ctxp; ; ctxp = ctxp->prev_context)
    if (ctxp->case_labels)
      break;

  gimple_label = gimple_build_label (CASE_LABEL (*expr_p));
  VEC_safe_push (tree, heap, ctxp->case_labels, *expr_p);
  gimplify_seq_add_stmt (pre_p, gimple_label);

  return GS_ALL_DONE;
}

/* Build a GOTO to the LABEL_DECL pointed to by LABEL_P, building it first
   if necessary.  */

tree
build_and_jump (tree *label_p)
{
  if (label_p == NULL)
    /* If there's nowhere to jump, just fall through.  */
    return NULL_TREE;

  if (*label_p == NULL_TREE)
    {
      tree label = create_artificial_label (UNKNOWN_LOCATION);
      *label_p = label;
    }

  return build1 (GOTO_EXPR, void_type_node, *label_p);
}

/* Gimplify an EXIT_EXPR by converting to a GOTO_EXPR inside a COND_EXPR.
   This also involves building a label to jump to and communicating it to
   gimplify_loop_expr through gimplify_ctxp->exit_label.  */

static enum gimplify_status
gimplify_exit_expr (tree *expr_p)
{
  tree cond = TREE_OPERAND (*expr_p, 0);
  tree expr;

  expr = build_and_jump (&gimplify_ctxp->exit_label);
  expr = build3 (COND_EXPR, void_type_node, cond, expr, NULL_TREE);
  *expr_p = expr;

  return GS_OK;
}

/* A helper function to be called via walk_tree.  Mark all labels under *TP
   as being forced.  To be called for DECL_INITIAL of static variables.  */

tree
force_labels_r (tree *tp, int *walk_subtrees, void *data ATTRIBUTE_UNUSED)
{
  if (TYPE_P (*tp))
    *walk_subtrees = 0;
  if (TREE_CODE (*tp) == LABEL_DECL)
    FORCED_LABEL (*tp) = 1;

  return NULL_TREE;
}

/* *EXPR_P is a COMPONENT_REF being used as an rvalue.  If its type is
   different from its canonical type, wrap the whole thing inside a
   NOP_EXPR and force the type of the COMPONENT_REF to be the canonical
   type.

   The canonical type of a COMPONENT_REF is the type of the field being
   referenced--unless the field is a bit-field which can be read directly
   in a smaller mode, in which case the canonical type is the
   sign-appropriate type corresponding to that mode.  */

static void
canonicalize_component_ref (tree *expr_p)
{
  tree expr = *expr_p;
  tree type;

  gcc_assert (TREE_CODE (expr) == COMPONENT_REF);

  if (INTEGRAL_TYPE_P (TREE_TYPE (expr)))
    type = TREE_TYPE (get_unwidened (expr, NULL_TREE));
  else
    type = TREE_TYPE (TREE_OPERAND (expr, 1));

  /* One could argue that all the stuff below is not necessary for
     the non-bitfield case and declare it a FE error if type
     adjustment would be needed.  */
  if (TREE_TYPE (expr) != type)
    {
#ifdef ENABLE_TYPES_CHECKING
      tree old_type = TREE_TYPE (expr);
#endif
      int type_quals;

      /* We need to preserve qualifiers and propagate them from
         operand 0.  */
      type_quals = TYPE_QUALS (type)
        | TYPE_QUALS (TREE_TYPE (TREE_OPERAND (expr, 0)));
      if (TYPE_QUALS (type) != type_quals)
        type = build_qualified_type (TYPE_MAIN_VARIANT (type), type_quals);

      /* Set the type of the COMPONENT_REF to the underlying type.  */
      TREE_TYPE (expr) = type;

#ifdef ENABLE_TYPES_CHECKING
      /* It is now a FE error, if the conversion from the canonical
         type to the original expression type is not useless.  */
      gcc_assert (useless_type_conversion_p (old_type, type));
#endif
    }
}

/* If a NOP conversion is changing a pointer to array of foo to a pointer
   to foo, embed that change in the ADDR_EXPR by converting
      T array[U];
      (T *)&array
   ==>
      &array[L]
   where L is the lower bound.  For simplicity, only do this for constant
   lower bound.
   The constraint is that the type of &array[L] is trivially convertible
   to T *.  */

static void
canonicalize_addr_expr (tree *expr_p)
{
  tree expr = *expr_p;
  tree addr_expr = TREE_OPERAND (expr, 0);
  tree datype, ddatype, pddatype;

  /* We simplify only conversions from an ADDR_EXPR to a pointer type.  */
  if (!POINTER_TYPE_P (TREE_TYPE (expr))
      || TREE_CODE (addr_expr) != ADDR_EXPR)
    return;

  /* The addr_expr type should be a pointer to an array.  */
  datype = TREE_TYPE (TREE_TYPE (addr_expr));
  if (TREE_CODE (datype) != ARRAY_TYPE)
    return;

  /* The pointer to element type shall be trivially convertible to
     the expression pointer type.  */
  ddatype = TREE_TYPE (datype);
  pddatype = build_pointer_type (ddatype);
  if (!useless_type_conversion_p (TYPE_MAIN_VARIANT (TREE_TYPE (expr)),
                                  pddatype))
    return;

  /* The lower bound and element sizes must be constant.  */
  if (!TYPE_SIZE_UNIT (ddatype)
      || TREE_CODE (TYPE_SIZE_UNIT (ddatype)) != INTEGER_CST
      || !TYPE_DOMAIN (datype) || !TYPE_MIN_VALUE (TYPE_DOMAIN (datype))
      || TREE_CODE (TYPE_MIN_VALUE (TYPE_DOMAIN (datype))) != INTEGER_CST)
    return;

  /* All checks succeeded.  Build a new node to merge the cast.  */
  *expr_p = build4 (ARRAY_REF, ddatype, TREE_OPERAND (addr_expr, 0),
                    TYPE_MIN_VALUE (TYPE_DOMAIN (datype)),
                    NULL_TREE, NULL_TREE);
  *expr_p = build1 (ADDR_EXPR, pddatype, *expr_p);

  /* We can have stripped a required restrict qualifier above.  */
  if (!useless_type_conversion_p (TREE_TYPE (expr), TREE_TYPE (*expr_p)))
    *expr_p = fold_convert (TREE_TYPE (expr), *expr_p);
}

/* *EXPR_P is a NOP_EXPR or CONVERT_EXPR.  Remove it and/or other conversions
   underneath as appropriate.  */

static enum gimplify_status
gimplify_conversion (tree *expr_p)
{
  tree tem;
  location_t loc = EXPR_LOCATION (*expr_p);
  gcc_assert (CONVERT_EXPR_P (*expr_p));

  /* Then strip away all but the outermost conversion.  */
  STRIP_SIGN_NOPS (TREE_OPERAND (*expr_p, 0));

  /* And remove the outermost conversion if it's useless.  */
  if (tree_ssa_useless_type_conversion (*expr_p))
    *expr_p = TREE_OPERAND (*expr_p, 0);

  /* Attempt to avoid NOP_EXPR by producing reference to a subtype.
     For example this fold (subclass *)&A into &A->subclass avoiding
     a need for statement.  */
  if (CONVERT_EXPR_P (*expr_p)
      && POINTER_TYPE_P (TREE_TYPE (*expr_p))
      && POINTER_TYPE_P (TREE_TYPE (TREE_OPERAND (*expr_p, 0)))
      && (tem = maybe_fold_offset_to_address
          (EXPR_LOCATION (*expr_p), TREE_OPERAND (*expr_p, 0),
           integer_zero_node, TREE_TYPE (*expr_p))) != NULL_TREE)
    *expr_p = tem;

  /* If we still have a conversion at the toplevel,
     then canonicalize some constructs.  */
  if (CONVERT_EXPR_P (*expr_p))
    {
      tree sub = TREE_OPERAND (*expr_p, 0);

      /* If a NOP conversion is changing the type of a COMPONENT_REF
         expression, then canonicalize its type now in order to expose more
         redundant conversions.  */
      if (TREE_CODE (sub) == COMPONENT_REF)
        canonicalize_component_ref (&TREE_OPERAND (*expr_p, 0));

      /* If a NOP conversion is changing a pointer to array of foo
         to a pointer to foo, embed that change in the ADDR_EXPR.  */
      else if (TREE_CODE (sub) == ADDR_EXPR)
        canonicalize_addr_expr (expr_p);
    }

  /* If we have a conversion to a non-register type force the
     use of a VIEW_CONVERT_EXPR instead.  */
  if (CONVERT_EXPR_P (*expr_p) && !is_gimple_reg_type (TREE_TYPE (*expr_p)))
    *expr_p = fold_build1_loc (loc, VIEW_CONVERT_EXPR, TREE_TYPE (*expr_p),
                               TREE_OPERAND (*expr_p, 0));

  return GS_OK;
}

/* Nonlocal VLAs seen in the current function.  */
static struct pointer_set_t *nonlocal_vlas;

/* Gimplify a VAR_DECL or PARM_DECL.  Returns GS_OK if we expanded a
   DECL_VALUE_EXPR, and it's worth re-examining things.  */

static enum gimplify_status
gimplify_var_or_parm_decl (tree *expr_p)
{
  tree decl = *expr_p;

  /* ??? If this is a local variable, and it has not been seen in any
     outer BIND_EXPR, then it's probably the result of a duplicate
     declaration, for which we've already issued an error.  It would
     be really nice if the front end wouldn't leak these at all.
     Currently the only known culprit is C++ destructors, as seen
     in g++.old-deja/g++.jason/binding.C.  */
  if (TREE_CODE (decl) == VAR_DECL
      && !DECL_SEEN_IN_BIND_EXPR_P (decl)
      && !TREE_STATIC (decl) && !DECL_EXTERNAL (decl)
      && decl_function_context (decl) == current_function_decl)
    {
      gcc_assert (errorcount || sorrycount);
      return GS_ERROR;
    }

  /* When within an OpenMP context, notice uses of variables.  */
  if (gimplify_omp_ctxp && omp_notice_variable (gimplify_omp_ctxp, decl, true))
    return GS_ALL_DONE;

  /* If the decl is an alias for another expression, substitute it now.  */
  if (DECL_HAS_VALUE_EXPR_P (decl))
    {
      tree value_expr = DECL_VALUE_EXPR (decl);

      /* For referenced nonlocal VLAs add a decl for debugging purposes
         to the current function.  */
      if (TREE_CODE (decl) == VAR_DECL
          && TREE_CODE (DECL_SIZE_UNIT (decl)) != INTEGER_CST
          && nonlocal_vlas != NULL
          && TREE_CODE (value_expr) == INDIRECT_REF
          && TREE_CODE (TREE_OPERAND (value_expr, 0)) == VAR_DECL
          && decl_function_context (decl) != current_function_decl)
        {
          struct gimplify_omp_ctx *ctx = gimplify_omp_ctxp;
          while (ctx && ctx->region_type == ORT_WORKSHARE)
            ctx = ctx->outer_context;
          if (!ctx && !pointer_set_insert (nonlocal_vlas, decl))
            {
              tree copy = copy_node (decl), block;

              lang_hooks.dup_lang_specific_decl (copy);
              SET_DECL_RTL (copy, NULL_RTX);
              TREE_USED (copy) = 1;
              block = DECL_INITIAL (current_function_decl);
              TREE_CHAIN (copy) = BLOCK_VARS (block);
              BLOCK_VARS (block) = copy;
              SET_DECL_VALUE_EXPR (copy, unshare_expr (value_expr));
              DECL_HAS_VALUE_EXPR_P (copy) = 1;
            }
        }

      *expr_p = unshare_expr (value_expr);
      return GS_OK;
    }

  return GS_ALL_DONE;
}


/* Gimplify the COMPONENT_REF, ARRAY_REF, REALPART_EXPR or IMAGPART_EXPR
   node *EXPR_P.

      compound_lval
              : min_lval '[' val ']'
              | min_lval '.' ID
              | compound_lval '[' val ']'
              | compound_lval '.' ID

   This is not part of the original SIMPLE definition, which separates
   array and member references, but it seems reasonable to handle them
   together.  Also, this way we don't run into problems with union
   aliasing; gcc requires that for accesses through a union to alias, the
   union reference must be explicit, which was not always the case when we
   were splitting up array and member refs.

   PRE_P points to the sequence where side effects that must happen before
     *EXPR_P should be stored.

   POST_P points to the sequence where side effects that must happen after
     *EXPR_P should be stored.  */

static enum gimplify_status
gimplify_compound_lval (tree *expr_p, gimple_seq *pre_p, gimple_seq *post_p,
                        fallback_t fallback)
{
  tree *p;
  VEC(tree,heap) *stack;
  enum gimplify_status ret = GS_OK, tret;
  int i;
  location_t loc = EXPR_LOCATION (*expr_p);

  /* Create a stack of the subexpressions so later we can walk them in
     order from inner to outer.  */
  stack = VEC_alloc (tree, heap, 10);

  /* We can handle anything that get_inner_reference can deal with.  */
  for (p = expr_p; ; p = &TREE_OPERAND (*p, 0))
    {
    restart:
      /* Fold INDIRECT_REFs now to turn them into ARRAY_REFs.  */
      if (TREE_CODE (*p) == INDIRECT_REF)
        *p = fold_indirect_ref_loc (loc, *p);

      if (handled_component_p (*p))
        ;
      /* Expand DECL_VALUE_EXPR now.  In some cases that may expose
         additional COMPONENT_REFs.  */
      else if ((TREE_CODE (*p) == VAR_DECL || TREE_CODE (*p) == PARM_DECL)
               && gimplify_var_or_parm_decl (p) == GS_OK)
        goto restart;
      else
        break;

      VEC_safe_push (tree, heap, stack, *p);
    }

  gcc_assert (VEC_length (tree, stack));

  /* Now STACK is a stack of pointers to all the refs we've walked through
     and P points to the innermost expression.

     Java requires that we elaborated nodes in source order.  That
     means we must gimplify the inner expression followed by each of
     the indices, in order.  But we can't gimplify the inner
     expression until we deal with any variable bounds, sizes, or
     positions in order to deal with PLACEHOLDER_EXPRs.

     So we do this in three steps.  First we deal with the annotations
     for any variables in the components, then we gimplify the base,
     then we gimplify any indices, from left to right.  */
  for (i = VEC_length (tree, stack) - 1; i >= 0; i--)
    {
      tree t = VEC_index (tree, stack, i);

      if (TREE_CODE (t) == ARRAY_REF || TREE_CODE (t) == ARRAY_RANGE_REF)
        {
          /* Gimplify the low bound and element type size and put them into
             the ARRAY_REF.  If these values are set, they have already been
             gimplified.  */
          if (TREE_OPERAND (t, 2) == NULL_TREE)
            {
              tree low = unshare_expr (array_ref_low_bound (t));
              if (!is_gimple_min_invariant (low))
                {
                  TREE_OPERAND (t, 2) = low;
                  tret = gimplify_expr (&TREE_OPERAND (t, 2), pre_p,
                                        post_p, is_gimple_reg,
                                        fb_rvalue);
                  ret = MIN (ret, tret);
                }
            }

          if (!TREE_OPERAND (t, 3))
            {
              tree elmt_type = TREE_TYPE (TREE_TYPE (TREE_OPERAND (t, 0)));
              tree elmt_size = unshare_expr (array_ref_element_size (t));
              tree factor = size_int (TYPE_ALIGN_UNIT (elmt_type));

              /* Divide the element size by the alignment of the element
                 type (above).  */
              elmt_size = size_binop_loc (loc, EXACT_DIV_EXPR, elmt_size, factor);

              if (!is_gimple_min_invariant (elmt_size))
                {
                  TREE_OPERAND (t, 3) = elmt_size;
                  tret = gimplify_expr (&TREE_OPERAND (t, 3), pre_p,
                                        post_p, is_gimple_reg,
                                        fb_rvalue);
                  ret = MIN (ret, tret);
                }
            }
        }
      else if (TREE_CODE (t) == COMPONENT_REF)
        {
          /* Set the field offset into T and gimplify it.  */
          if (!TREE_OPERAND (t, 2))
            {
              tree offset = unshare_expr (component_ref_field_offset (t));
              tree field = TREE_OPERAND (t, 1);
              tree factor
                = size_int (DECL_OFFSET_ALIGN (field) / BITS_PER_UNIT);

              /* Divide the offset by its alignment.  */
              offset = size_binop_loc (loc, EXACT_DIV_EXPR, offset, factor);

              if (!is_gimple_min_invariant (offset))
                {
                  TREE_OPERAND (t, 2) = offset;
                  tret = gimplify_expr (&TREE_OPERAND (t, 2), pre_p,
                                        post_p, is_gimple_reg,
                                        fb_rvalue);
                  ret = MIN (ret, tret);
                }
            }
        }
    }

  /* Step 2 is to gimplify the base expression.  Make sure lvalue is set
     so as to match the min_lval predicate.  Failure to do so may result
     in the creation of large aggregate temporaries.  */
  tret = gimplify_expr (p, pre_p, post_p, is_gimple_min_lval,
                        fallback | fb_lvalue);
  ret = MIN (ret, tret);

  /* And finally, the indices and operands to BIT_FIELD_REF.  During this
     loop we also remove any useless conversions.  */
  for (; VEC_length (tree, stack) > 0; )
    {
      tree t = VEC_pop (tree, stack);

      if (TREE_CODE (t) == ARRAY_REF || TREE_CODE (t) == ARRAY_RANGE_REF)
        {
          /* Gimplify the dimension.  */
          if (!is_gimple_min_invariant (TREE_OPERAND (t, 1)))
            {
              tret = gimplify_expr (&TREE_OPERAND (t, 1), pre_p, post_p,
                                    is_gimple_val, fb_rvalue);
              ret = MIN (ret, tret);
            }
        }
      else if (TREE_CODE (t) == BIT_FIELD_REF)
        {
          tret = gimplify_expr (&TREE_OPERAND (t, 1), pre_p, post_p,
                                is_gimple_val, fb_rvalue);
          ret = MIN (ret, tret);
          tret = gimplify_expr (&TREE_OPERAND (t, 2), pre_p, post_p,
                                is_gimple_val, fb_rvalue);
          ret = MIN (ret, tret);
        }

      STRIP_USELESS_TYPE_CONVERSION (TREE_OPERAND (t, 0));

      /* The innermost expression P may have originally had
         TREE_SIDE_EFFECTS set which would have caused all the outer
         expressions in *EXPR_P leading to P to also have had
         TREE_SIDE_EFFECTS set.  */
      recalculate_side_effects (t);
    }

  /* If the outermost expression is a COMPONENT_REF, canonicalize its type.  */
  if ((fallback & fb_rvalue) && TREE_CODE (*expr_p) == COMPONENT_REF)
    {
      canonicalize_component_ref (expr_p);
      ret = MIN (ret, GS_OK);
    }

  VEC_free (tree, heap, stack);

  return ret;
}

/*  Gimplify the self modifying expression pointed to by EXPR_P
    (++, --, +=, -=).

    PRE_P points to the list where side effects that must happen before
        *EXPR_P should be stored.

    POST_P points to the list where side effects that must happen after
        *EXPR_P should be stored.

    WANT_VALUE is nonzero iff we want to use the value of this expression
        in another expression.  */

static enum gimplify_status
gimplify_self_mod_expr (tree *expr_p, gimple_seq *pre_p, gimple_seq *post_p,
                        bool want_value)
{
  enum tree_code code;
  tree lhs, lvalue, rhs, t1;
  gimple_seq post = NULL, *orig_post_p = post_p;
  bool postfix;
  enum tree_code arith_code;
  enum gimplify_status ret;
  location_t loc = EXPR_LOCATION (*expr_p);

  code = TREE_CODE (*expr_p);

  gcc_assert (code == POSTINCREMENT_EXPR || code == POSTDECREMENT_EXPR
              || code == PREINCREMENT_EXPR || code == PREDECREMENT_EXPR);

  /* Prefix or postfix?  */
  if (code == POSTINCREMENT_EXPR || code == POSTDECREMENT_EXPR)
    /* Faster to treat as prefix if result is not used.  */
    postfix = want_value;
  else
    postfix = false;

  /* For postfix, make sure the inner expression's post side effects
     are executed after side effects from this expression.  */
  if (postfix)
    post_p = &post;

  /* Add or subtract?  */
  if (code == PREINCREMENT_EXPR || code == POSTINCREMENT_EXPR)
    arith_code = PLUS_EXPR;
  else
    arith_code = MINUS_EXPR;

  /* Gimplify the LHS into a GIMPLE lvalue.  */
  lvalue = TREE_OPERAND (*expr_p, 0);
  ret = gimplify_expr (&lvalue, pre_p, post_p, is_gimple_lvalue, fb_lvalue);
  if (ret == GS_ERROR)
    return ret;

  /* Extract the operands to the arithmetic operation.  */
  lhs = lvalue;
  rhs = TREE_OPERAND (*expr_p, 1);

  /* For postfix operator, we evaluate the LHS to an rvalue and then use
     that as the result value and in the postqueue operation.  We also
     make sure to make lvalue a minimal lval, see
     gcc.c-torture/execute/20040313-1.c for an example where this matters.  */
  if (postfix)
    {
      if (!is_gimple_min_lval (lvalue))
        {
          mark_addressable (lvalue);
          lvalue = build_fold_addr_expr_loc (input_location, lvalue);
          gimplify_expr (&lvalue, pre_p, post_p, is_gimple_val, fb_rvalue);
          lvalue = build_fold_indirect_ref_loc (input_location, lvalue);
        }
      ret = gimplify_expr (&lhs, pre_p, post_p, is_gimple_val, fb_rvalue);
      if (ret == GS_ERROR)
        return ret;
    }

  /* For POINTERs increment, use POINTER_PLUS_EXPR.  */
  if (POINTER_TYPE_P (TREE_TYPE (lhs)))
    {
      rhs = fold_convert_loc (loc, sizetype, rhs);
      if (arith_code == MINUS_EXPR)
        rhs = fold_build1_loc (loc, NEGATE_EXPR, TREE_TYPE (rhs), rhs);
      arith_code = POINTER_PLUS_EXPR;
    }

  t1 = build2 (arith_code, TREE_TYPE (*expr_p), lhs, rhs);

  if (postfix)
    {
      gimplify_assign (lvalue, t1, orig_post_p);
      gimplify_seq_add_seq (orig_post_p, post);
      *expr_p = lhs;
      return GS_ALL_DONE;
    }
  else
    {
      *expr_p = build2 (MODIFY_EXPR, TREE_TYPE (lvalue), lvalue, t1);
      return GS_OK;
    }
}


/* If *EXPR_P has a variable sized type, wrap it in a WITH_SIZE_EXPR.  */

static void
maybe_with_size_expr (tree *expr_p)
{
  tree expr = *expr_p;
  tree type = TREE_TYPE (expr);
  tree size;

  /* If we've already wrapped this or the type is error_mark_node, we can't do
     anything.  */
  if (TREE_CODE (expr) == WITH_SIZE_EXPR
      || type == error_mark_node)
    return;

  /* If the size isn't known or is a constant, we have nothing to do.  */
  size = TYPE_SIZE_UNIT (type);
  if (!size || TREE_CODE (size) == INTEGER_CST)
    return;

  /* Otherwise, make a WITH_SIZE_EXPR.  */
  size = unshare_expr (size);
  size = SUBSTITUTE_PLACEHOLDER_IN_EXPR (size, expr);
  *expr_p = build2 (WITH_SIZE_EXPR, type, expr, size);
}


/* Helper for gimplify_call_expr.  Gimplify a single argument *ARG_P
   Store any side-effects in PRE_P.  CALL_LOCATION is the location of
   the CALL_EXPR.  */

static enum gimplify_status
gimplify_arg (tree *arg_p, gimple_seq *pre_p, location_t call_location)
{
  bool (*test) (tree);
  fallback_t fb;

  /* In general, we allow lvalues for function arguments to avoid
     extra overhead of copying large aggregates out of even larger
     aggregates into temporaries only to copy the temporaries to
     the argument list.  Make optimizers happy by pulling out to
     temporaries those types that fit in registers.  */
  if (is_gimple_reg_type (TREE_TYPE (*arg_p)))
    test = is_gimple_val, fb = fb_rvalue;
  else
    test = is_gimple_lvalue, fb = fb_either;

  /* If this is a variable sized type, we must remember the size.  */
  maybe_with_size_expr (arg_p);

  /* FIXME diagnostics: This will mess up gcc.dg/Warray-bounds.c.  */
  /* Make sure arguments have the same location as the function call
     itself.  */
  protected_set_expr_location (*arg_p, call_location);

  /* There is a sequence point before a function call.  Side effects in
     the argument list must occur before the actual call. So, when
     gimplifying arguments, force gimplify_expr to use an internal
     post queue which is then appended to the end of PRE_P.  */
  return gimplify_expr (arg_p, pre_p, NULL, test, fb);
}


/* Gimplify the CALL_EXPR node *EXPR_P into the GIMPLE sequence PRE_P.
   WANT_VALUE is true if the result of the call is desired.  */

static enum gimplify_status
gimplify_call_expr (tree *expr_p, gimple_seq *pre_p, bool want_value)
{
  tree fndecl, parms, p;
  enum gimplify_status ret;
  int i, nargs;
  gimple call;
  bool builtin_va_start_p = FALSE;
  location_t loc = EXPR_LOCATION (*expr_p);

  gcc_assert (TREE_CODE (*expr_p) == CALL_EXPR);

  /* For reliable diagnostics during inlining, it is necessary that
     every call_expr be annotated with file and line.  */
  if (! EXPR_HAS_LOCATION (*expr_p))
    SET_EXPR_LOCATION (*expr_p, input_location);

  /* This may be a call to a builtin function.

     Builtin function calls may be transformed into different
     (and more efficient) builtin function calls under certain
     circumstances.  Unfortunately, gimplification can muck things
     up enough that the builtin expanders are not aware that certain
     transformations are still valid.

     So we attempt transformation/gimplification of the call before
     we gimplify the CALL_EXPR.  At this time we do not manage to
     transform all calls in the same manner as the expanders do, but
     we do transform most of them.  */
  fndecl = get_callee_fndecl (*expr_p);
  if (fndecl && DECL_BUILT_IN (fndecl))
    {
      tree new_tree = fold_call_expr (input_location, *expr_p, !want_value);

      if (new_tree && new_tree != *expr_p)
        {
          /* There was a transformation of this call which computes the
             same value, but in a more efficient way.  Return and try
             again.  */
          *expr_p = new_tree;
          return GS_OK;
        }

      if (DECL_BUILT_IN_CLASS (fndecl) == BUILT_IN_NORMAL
          && DECL_FUNCTION_CODE (fndecl) == BUILT_IN_VA_START)
        {
          builtin_va_start_p = TRUE;
          if (call_expr_nargs (*expr_p) < 2)
            {
              error ("too few arguments to function %<va_start%>");
              *expr_p = build_empty_stmt (EXPR_LOCATION (*expr_p));
              return GS_OK;
            }

          if (fold_builtin_next_arg (*expr_p, true))
            {
              *expr_p = build_empty_stmt (EXPR_LOCATION (*expr_p));
              return GS_OK;
            }
        }
    }

  /* There is a sequence point before the call, so any side effects in
     the calling expression must occur before the actual call.  Force
     gimplify_expr to use an internal post queue.  */
  ret = gimplify_expr (&CALL_EXPR_FN (*expr_p), pre_p, NULL,
                       is_gimple_call_addr, fb_rvalue);

  nargs = call_expr_nargs (*expr_p);

  /* Get argument types for verification.  */
  fndecl = get_callee_fndecl (*expr_p);
  parms = NULL_TREE;
  if (fndecl)
    parms = TYPE_ARG_TYPES (TREE_TYPE (fndecl));
  else if (POINTER_TYPE_P (TREE_TYPE (CALL_EXPR_FN (*expr_p))))
    parms = TYPE_ARG_TYPES (TREE_TYPE (TREE_TYPE (CALL_EXPR_FN (*expr_p))));

  if (fndecl && DECL_ARGUMENTS (fndecl))
    p = DECL_ARGUMENTS (fndecl);
  else if (parms)
    p = parms;
  else
    p = NULL_TREE;
  for (i = 0; i < nargs && p; i++, p = TREE_CHAIN (p))
    ;

  /* If the last argument is __builtin_va_arg_pack () and it is not
     passed as a named argument, decrease the number of CALL_EXPR
     arguments and set instead the CALL_EXPR_VA_ARG_PACK flag.  */
  if (!p
      && i < nargs
      && TREE_CODE (CALL_EXPR_ARG (*expr_p, nargs - 1)) == CALL_EXPR)
    {
      tree last_arg = CALL_EXPR_ARG (*expr_p, nargs - 1);
      tree last_arg_fndecl = get_callee_fndecl (last_arg);

      if (last_arg_fndecl
          && TREE_CODE (last_arg_fndecl) == FUNCTION_DECL
          && DECL_BUILT_IN_CLASS (last_arg_fndecl) == BUILT_IN_NORMAL
          && DECL_FUNCTION_CODE (last_arg_fndecl) == BUILT_IN_VA_ARG_PACK)
        {
          tree call = *expr_p;

          --nargs;
          *expr_p = build_call_array_loc (loc, TREE_TYPE (call),
                                          CALL_EXPR_FN (call),
                                          nargs, CALL_EXPR_ARGP (call));

          /* Copy all CALL_EXPR flags, location and block, except
             CALL_EXPR_VA_ARG_PACK flag.  */
          CALL_EXPR_STATIC_CHAIN (*expr_p) = CALL_EXPR_STATIC_CHAIN (call);
          CALL_EXPR_TAILCALL (*expr_p) = CALL_EXPR_TAILCALL (call);
          CALL_EXPR_RETURN_SLOT_OPT (*expr_p)
            = CALL_EXPR_RETURN_SLOT_OPT (call);
          CALL_FROM_THUNK_P (*expr_p) = CALL_FROM_THUNK_P (call);
          CALL_CANNOT_INLINE_P (*expr_p) = CALL_CANNOT_INLINE_P (call);
          SET_EXPR_LOCATION (*expr_p, EXPR_LOCATION (call));
          TREE_BLOCK (*expr_p) = TREE_BLOCK (call);

          /* Set CALL_EXPR_VA_ARG_PACK.  */
          CALL_EXPR_VA_ARG_PACK (*expr_p) = 1;
        }
    }

  /* Finally, gimplify the function arguments.  */
  if (nargs > 0)
    {
      for (i = (PUSH_ARGS_REVERSED ? nargs - 1 : 0);
           PUSH_ARGS_REVERSED ? i >= 0 : i < nargs;
           PUSH_ARGS_REVERSED ? i-- : i++)
        {
          enum gimplify_status t;

          /* Avoid gimplifying the second argument to va_start, which needs to
             be the plain PARM_DECL.  */
          if ((i != 1) || !builtin_va_start_p)
            {
              t = gimplify_arg (&CALL_EXPR_ARG (*expr_p, i), pre_p,
                                EXPR_LOCATION (*expr_p));

              if (t == GS_ERROR)
                ret = GS_ERROR;
            }
        }
    }

  /* Verify the function result.  */
  if (want_value && fndecl
      && VOID_TYPE_P (TREE_TYPE (TREE_TYPE (fndecl))))
    {
      error_at (loc, "using result of function returning %<void%>");
      ret = GS_ERROR;
    }

  /* Try this again in case gimplification exposed something.  */
  if (ret != GS_ERROR)
    {
      tree new_tree = fold_call_expr (input_location, *expr_p, !want_value);

      if (new_tree && new_tree != *expr_p)
        {
          /* There was a transformation of this call which computes the
             same value, but in a more efficient way.  Return and try
             again.  */
          *expr_p = new_tree;
          return GS_OK;
        }
    }
  else
    {
      *expr_p = error_mark_node;
      return GS_ERROR;
    }

  /* If the function is "const" or "pure", then clear TREE_SIDE_EFFECTS on its
     decl.  This allows us to eliminate redundant or useless
     calls to "const" functions.  */
  if (TREE_CODE (*expr_p) == CALL_EXPR)
    {
      int flags = call_expr_flags (*expr_p);
      if (flags & (ECF_CONST | ECF_PURE)
          /* An infinite loop is considered a side effect.  */
          && !(flags & (ECF_LOOPING_CONST_OR_PURE)))
        TREE_SIDE_EFFECTS (*expr_p) = 0;
    }

  /* If the value is not needed by the caller, emit a new GIMPLE_CALL
     and clear *EXPR_P.  Otherwise, leave *EXPR_P in its gimplified
     form and delegate the creation of a GIMPLE_CALL to
     gimplify_modify_expr.  This is always possible because when
     WANT_VALUE is true, the caller wants the result of this call into
     a temporary, which means that we will emit an INIT_EXPR in
     internal_get_tmp_var which will then be handled by
     gimplify_modify_expr.  */
  if (!want_value)
    {
      /* The CALL_EXPR in *EXPR_P is already in GIMPLE form, so all we
         have to do is replicate it as a GIMPLE_CALL tuple.  */
      call = gimple_build_call_from_tree (*expr_p);
      gimplify_seq_add_stmt (pre_p, call);
      *expr_p = NULL_TREE;
    }

  return ret;
}

/* Handle shortcut semantics in the predicate operand of a COND_EXPR by
   rewriting it into multiple COND_EXPRs, and possibly GOTO_EXPRs.

   TRUE_LABEL_P and FALSE_LABEL_P point to the labels to jump to if the
   condition is true or false, respectively.  If null, we should generate
   our own to skip over the evaluation of this specific expression.

   LOCUS is the source location of the COND_EXPR.

   This function is the tree equivalent of do_jump.

   shortcut_cond_r should only be called by shortcut_cond_expr.  */

static tree
shortcut_cond_r (tree pred, tree *true_label_p, tree *false_label_p,
                 location_t locus)
{
  tree local_label = NULL_TREE;
  tree t, expr = NULL;

  /* OK, it's not a simple case; we need to pull apart the COND_EXPR to
     retain the shortcut semantics.  Just insert the gotos here;
     shortcut_cond_expr will append the real blocks later.  */
  if (TREE_CODE (pred) == TRUTH_ANDIF_EXPR)
    {
      location_t new_locus;

      /* Turn if (a && b) into

         if (a); else goto no;
         if (b) goto yes; else goto no;
         (no:) */

      if (false_label_p == NULL)
        false_label_p = &local_label;

      /* Keep the original source location on the first 'if'.  */
      t = shortcut_cond_r (TREE_OPERAND (pred, 0), NULL, false_label_p, locus);
      append_to_statement_list (t, &expr);

      /* Set the source location of the && on the second 'if'.  */
      new_locus = EXPR_HAS_LOCATION (pred) ? EXPR_LOCATION (pred) : locus;
      t = shortcut_cond_r (TREE_OPERAND (pred, 1), true_label_p, false_label_p,
                           new_locus);
      append_to_statement_list (t, &expr);
    }
  else if (TREE_CODE (pred) == TRUTH_ORIF_EXPR)
    {
      location_t new_locus;

      /* Turn if (a || b) into

         if (a) goto yes;
         if (b) goto yes; else goto no;
         (yes:) */

      if (true_label_p == NULL)
        true_label_p = &local_label;

      /* Keep the original source location on the first 'if'.  */
      t = shortcut_cond_r (TREE_OPERAND (pred, 0), true_label_p, NULL, locus);
      append_to_statement_list (t, &expr);

      /* Set the source location of the || on the second 'if'.  */
      new_locus = EXPR_HAS_LOCATION (pred) ? EXPR_LOCATION (pred) : locus;
      t = shortcut_cond_r (TREE_OPERAND (pred, 1), true_label_p, false_label_p,
                           new_locus);
      append_to_statement_list (t, &expr);
    }
  else if (TREE_CODE (pred) == COND_EXPR)
    {
      location_t new_locus;

      /* As long as we're messing with gotos, turn if (a ? b : c) into
         if (a)
           if (b) goto yes; else goto no;
         else
           if (c) goto yes; else goto no;  */

      /* Keep the original source location on the first 'if'.  Set the source
         location of the ? on the second 'if'.  */
      new_locus = EXPR_HAS_LOCATION (pred) ? EXPR_LOCATION (pred) : locus;
      expr = build3 (COND_EXPR, void_type_node, TREE_OPERAND (pred, 0),
                     shortcut_cond_r (TREE_OPERAND (pred, 1), true_label_p,
                                      false_label_p, locus),
                     shortcut_cond_r (TREE_OPERAND (pred, 2), true_label_p,
                                      false_label_p, new_locus));
    }
  else
    {
      expr = build3 (COND_EXPR, void_type_node, pred,
                     build_and_jump (true_label_p),
                     build_and_jump (false_label_p));
      SET_EXPR_LOCATION (expr, locus);
    }

  if (local_label)
    {
      t = build1 (LABEL_EXPR, void_type_node, local_label);
      append_to_statement_list (t, &expr);
    }

  return expr;
}

/* Given a conditional expression EXPR with short-circuit boolean
   predicates using TRUTH_ANDIF_EXPR or TRUTH_ORIF_EXPR, break the
   predicate appart into the equivalent sequence of conditionals.  */

static tree
shortcut_cond_expr (tree expr)
{
  tree pred = TREE_OPERAND (expr, 0);
  tree then_ = TREE_OPERAND (expr, 1);
  tree else_ = TREE_OPERAND (expr, 2);
  tree true_label, false_label, end_label, t;
  tree *true_label_p;
  tree *false_label_p;
  bool emit_end, emit_false, jump_over_else;
  bool then_se = then_ && TREE_SIDE_EFFECTS (then_);
  bool else_se = else_ && TREE_SIDE_EFFECTS (else_);

  /* First do simple transformations.  */
  if (!else_se)
    {
      /* If there is no 'else', turn
           if (a && b) then c
         into
           if (a) if (b) then c.  */
      while (TREE_CODE (pred) == TRUTH_ANDIF_EXPR)
        {
          /* Keep the original source location on the first 'if'.  */
          location_t locus = EXPR_HAS_LOCATION (expr)
                             ? EXPR_LOCATION (expr) : input_location;
          TREE_OPERAND (expr, 0) = TREE_OPERAND (pred, 1);
          /* Set the source location of the && on the second 'if'.  */
          if (EXPR_HAS_LOCATION (pred))
            SET_EXPR_LOCATION (expr, EXPR_LOCATION (pred));
          then_ = shortcut_cond_expr (expr);
          then_se = then_ && TREE_SIDE_EFFECTS (then_);
          pred = TREE_OPERAND (pred, 0);
          expr = build3 (COND_EXPR, void_type_node, pred, then_, NULL_TREE);
          SET_EXPR_LOCATION (expr, locus);
        }
    }

  if (!then_se)
    {
      /* If there is no 'then', turn
           if (a || b); else d
         into
           if (a); else if (b); else d.  */
      while (TREE_CODE (pred) == TRUTH_ORIF_EXPR)
        {
          /* Keep the original source location on the first 'if'.  */
          location_t locus = EXPR_HAS_LOCATION (expr)
                             ? EXPR_LOCATION (expr) : input_location;
          TREE_OPERAND (expr, 0) = TREE_OPERAND (pred, 1);
          /* Set the source location of the || on the second 'if'.  */
          if (EXPR_HAS_LOCATION (pred))
            SET_EXPR_LOCATION (expr, EXPR_LOCATION (pred));
          else_ = shortcut_cond_expr (expr);
          else_se = else_ && TREE_SIDE_EFFECTS (else_);
          pred = TREE_OPERAND (pred, 0);
          expr = build3 (COND_EXPR, void_type_node, pred, NULL_TREE, else_);
          SET_EXPR_LOCATION (expr, locus);
        }
    }

  /* If we're done, great.  */
  if (TREE_CODE (pred) != TRUTH_ANDIF_EXPR
      && TREE_CODE (pred) != TRUTH_ORIF_EXPR)
    return expr;

  /* Otherwise we need to mess with gotos.  Change
       if (a) c; else d;
     to
       if (a); else goto no;
       c; goto end;
       no: d; end:
     and recursively gimplify the condition.  */

  true_label = false_label = end_label = NULL_TREE;

  /* If our arms just jump somewhere, hijack those labels so we don't
     generate jumps to jumps.  */

  if (then_
      && TREE_CODE (then_) == GOTO_EXPR
      && TREE_CODE (GOTO_DESTINATION (then_)) == LABEL_DECL)
    {
      true_label = GOTO_DESTINATION (then_);
      then_ = NULL;
      then_se = false;
    }

  if (else_
      && TREE_CODE (else_) == GOTO_EXPR
      && TREE_CODE (GOTO_DESTINATION (else_)) == LABEL_DECL)
    {
      false_label = GOTO_DESTINATION (else_);
      else_ = NULL;
      else_se = false;
    }

  /* If we aren't hijacking a label for the 'then' branch, it falls through.  */
  if (true_label)
    true_label_p = &true_label;
  else
    true_label_p = NULL;

  /* The 'else' branch also needs a label if it contains interesting code.  */
  if (false_label || else_se)
    false_label_p = &false_label;
  else
    false_label_p = NULL;

  /* If there was nothing else in our arms, just forward the label(s).  */
  if (!then_se && !else_se)
    return shortcut_cond_r (pred, true_label_p, false_label_p,
                            EXPR_HAS_LOCATION (expr)
                            ? EXPR_LOCATION (expr) : input_location);

  /* If our last subexpression already has a terminal label, reuse it.  */
  if (else_se)
    t = expr_last (else_);
  else if (then_se)
    t = expr_last (then_);
  else
    t = NULL;
  if (t && TREE_CODE (t) == LABEL_EXPR)
    end_label = LABEL_EXPR_LABEL (t);

  /* If we don't care about jumping to the 'else' branch, jump to the end
     if the condition is false.  */
  if (!false_label_p)
    false_label_p = &end_label;

  /* We only want to emit these labels if we aren't hijacking them.  */
  emit_end = (end_label == NULL_TREE);
  emit_false = (false_label == NULL_TREE);

  /* We only emit the jump over the else clause if we have to--if the
     then clause may fall through.  Otherwise we can wind up with a
     useless jump and a useless label at the end of gimplified code,
     which will cause us to think that this conditional as a whole
     falls through even if it doesn't.  If we then inline a function
     which ends with such a condition, that can cause us to issue an
     inappropriate warning about control reaching the end of a
     non-void function.  */
  jump_over_else = block_may_fallthru (then_);

  pred = shortcut_cond_r (pred, true_label_p, false_label_p,
                          EXPR_HAS_LOCATION (expr)
                          ? EXPR_LOCATION (expr) : input_location);

  expr = NULL;
  append_to_statement_list (pred, &expr);

  append_to_statement_list (then_, &expr);
  if (else_se)
    {
      if (jump_over_else)
        {
          tree last = expr_last (expr);
          t = build_and_jump (&end_label);
          if (EXPR_HAS_LOCATION (last))
            SET_EXPR_LOCATION (t, EXPR_LOCATION (last));
          append_to_statement_list (t, &expr);
        }
      if (emit_false)
        {
          t = build1 (LABEL_EXPR, void_type_node, false_label);
          append_to_statement_list (t, &expr);
        }
      append_to_statement_list (else_, &expr);
    }
  if (emit_end && end_label)
    {
      t = build1 (LABEL_EXPR, void_type_node, end_label);
      append_to_statement_list (t, &expr);
    }

  return expr;
}

/* EXPR is used in a boolean context; make sure it has BOOLEAN_TYPE.  */

tree
gimple_boolify (tree expr)
{
  tree type = TREE_TYPE (expr);
  location_t loc = EXPR_LOCATION (expr);

  if (TREE_CODE (expr) == NE_EXPR
      && TREE_CODE (TREE_OPERAND (expr, 0)) == CALL_EXPR
      && integer_zerop (TREE_OPERAND (expr, 1)))
    {
      tree call = TREE_OPERAND (expr, 0);
      tree fn = get_callee_fndecl (call);

      /* For __builtin_expect ((long) (x), y) recurse into x as well
         if x is truth_value_p.  */
      if (fn
          && DECL_BUILT_IN_CLASS (fn) == BUILT_IN_NORMAL
          && DECL_FUNCTION_CODE (fn) == BUILT_IN_EXPECT
          && call_expr_nargs (call) == 2)
        {
          tree arg = CALL_EXPR_ARG (call, 0);
          if (arg)
            {
              if (TREE_CODE (arg) == NOP_EXPR
                  && TREE_TYPE (arg) == TREE_TYPE (call))
                arg = TREE_OPERAND (arg, 0);
              if (truth_value_p (TREE_CODE (arg)))
                {
                  arg = gimple_boolify (arg);
                  CALL_EXPR_ARG (call, 0)
                    = fold_convert_loc (loc, TREE_TYPE (call), arg);
                }
            }
        }
    }

  if (TREE_CODE (type) == BOOLEAN_TYPE)
    return expr;

  switch (TREE_CODE (expr))
    {
    case TRUTH_AND_EXPR:
    case TRUTH_OR_EXPR:
    case TRUTH_XOR_EXPR:
    case TRUTH_ANDIF_EXPR:
    case TRUTH_ORIF_EXPR:
      /* Also boolify the arguments of truth exprs.  */
      TREE_OPERAND (expr, 1) = gimple_boolify (TREE_OPERAND (expr, 1));
      /* FALLTHRU */

    case TRUTH_NOT_EXPR:
      TREE_OPERAND (expr, 0) = gimple_boolify (TREE_OPERAND (expr, 0));
      /* FALLTHRU */

    case EQ_EXPR: case NE_EXPR:
    case LE_EXPR: case GE_EXPR: case LT_EXPR: case GT_EXPR:
      /* These expressions always produce boolean results.  */
      TREE_TYPE (expr) = boolean_type_node;
      return expr;

    default:
      /* Other expressions that get here must have boolean values, but
         might need to be converted to the appropriate mode.  */
      return fold_convert_loc (loc, boolean_type_node, expr);
    }
}

/* Given a conditional expression *EXPR_P without side effects, gimplify
   its operands.  New statements are inserted to PRE_P.  */

static enum gimplify_status
gimplify_pure_cond_expr (tree *expr_p, gimple_seq *pre_p)
{
  tree expr = *expr_p, cond;
  enum gimplify_status ret, tret;
  enum tree_code code;

  cond = gimple_boolify (COND_EXPR_COND (expr));

  /* We need to handle && and || specially, as their gimplification
     creates pure cond_expr, thus leading to an infinite cycle otherwise.  */
  code = TREE_CODE (cond);
  if (code == TRUTH_ANDIF_EXPR)
    TREE_SET_CODE (cond, TRUTH_AND_EXPR);
  else if (code == TRUTH_ORIF_EXPR)
    TREE_SET_CODE (cond, TRUTH_OR_EXPR);
  ret = gimplify_expr (&cond, pre_p, NULL, is_gimple_condexpr, fb_rvalue);
  COND_EXPR_COND (*expr_p) = cond;

  tret = gimplify_expr (&COND_EXPR_THEN (expr), pre_p, NULL,
                                   is_gimple_val, fb_rvalue);
  ret = MIN (ret, tret);
  tret = gimplify_expr (&COND_EXPR_ELSE (expr), pre_p, NULL,
                                   is_gimple_val, fb_rvalue);

  return MIN (ret, tret);
}

/* Returns true if evaluating EXPR could trap.
   EXPR is GENERIC, while tree_could_trap_p can be called
   only on GIMPLE.  */

static bool
generic_expr_could_trap_p (tree expr)
{
  unsigned i, n;

  if (!expr || is_gimple_val (expr))
    return false;

  if (!EXPR_P (expr) || tree_could_trap_p (expr))
    return true;

  n = TREE_OPERAND_LENGTH (expr);
  for (i = 0; i < n; i++)
    if (generic_expr_could_trap_p (TREE_OPERAND (expr, i)))
      return true;

  return false;
}

/*  Convert the conditional expression pointed to by EXPR_P '(p) ? a : b;'
    into

    if (p)                      if (p)
      t1 = a;                     a;
    else                or      else
      t1 = b;                     b;
    t1;

    The second form is used when *EXPR_P is of type void.

    PRE_P points to the list where side effects that must happen before
      *EXPR_P should be stored.  */

static enum gimplify_status
gimplify_cond_expr (tree *expr_p, gimple_seq *pre_p, fallback_t fallback)
{
  tree expr = *expr_p;
  tree type = TREE_TYPE (expr);
  location_t loc = EXPR_LOCATION (expr);
  tree tmp, arm1, arm2;
  enum gimplify_status ret;
  tree label_true, label_false, label_cont;
  bool have_then_clause_p, have_else_clause_p;
  gimple gimple_cond;
  enum tree_code pred_code;
  gimple_seq seq = NULL;

  /* If this COND_EXPR has a value, copy the values into a temporary within
     the arms.  */
  if (!VOID_TYPE_P (type))
    {
      tree then_ = TREE_OPERAND (expr, 1), else_ = TREE_OPERAND (expr, 2);
      tree result;

      /* If either an rvalue is ok or we do not require an lvalue, create the
         temporary.  But we cannot do that if the type is addressable.  */
      if (((fallback & fb_rvalue) || !(fallback & fb_lvalue))
          && !TREE_ADDRESSABLE (type))
        {
          if (gimplify_ctxp->allow_rhs_cond_expr
              /* If either branch has side effects or could trap, it can't be
                 evaluated unconditionally.  */
              && !TREE_SIDE_EFFECTS (then_)
              && !generic_expr_could_trap_p (then_)
              && !TREE_SIDE_EFFECTS (else_)
              && !generic_expr_could_trap_p (else_))
            return gimplify_pure_cond_expr (expr_p, pre_p);

          tmp = create_tmp_var (type, "iftmp");
          result = tmp;
        }

      /* Otherwise, only create and copy references to the values.  */
      else
        {
          type = build_pointer_type (type);

          if (!VOID_TYPE_P (TREE_TYPE (then_)))
            then_ = build_fold_addr_expr_loc (loc, then_);

          if (!VOID_TYPE_P (TREE_TYPE (else_)))
            else_ = build_fold_addr_expr_loc (loc, else_);
 
          expr
            = build3 (COND_EXPR, type, TREE_OPERAND (expr, 0), then_, else_);

          tmp = create_tmp_var (type, "iftmp");
          result = build_fold_indirect_ref_loc (loc, tmp);
        }

      /* Build the new then clause, `tmp = then_;'.  But don't build the
         assignment if the value is void; in C++ it can be if it's a throw.  */
      if (!VOID_TYPE_P (TREE_TYPE (then_)))
        TREE_OPERAND (expr, 1) = build2 (MODIFY_EXPR, type, tmp, then_);

      /* Similarly, build the new else clause, `tmp = else_;'.  */
      if (!VOID_TYPE_P (TREE_TYPE (else_)))
        TREE_OPERAND (expr, 2) = build2 (MODIFY_EXPR, type, tmp, else_);

      TREE_TYPE (expr) = void_type_node;
      recalculate_side_effects (expr);

      /* Move the COND_EXPR to the prequeue.  */
      gimplify_stmt (&expr, pre_p);

      *expr_p = result;
      return GS_ALL_DONE;
    }

  /* Make sure the condition has BOOLEAN_TYPE.  */
  TREE_OPERAND (expr, 0) = gimple_boolify (TREE_OPERAND (expr, 0));

  /* Break apart && and || conditions.  */
  if (TREE_CODE (TREE_OPERAND (expr, 0)) == TRUTH_ANDIF_EXPR
      || TREE_CODE (TREE_OPERAND (expr, 0)) == TRUTH_ORIF_EXPR)
    {
      expr = shortcut_cond_expr (expr);

      if (expr != *expr_p)
        {
          *expr_p = expr;

          /* We can't rely on gimplify_expr to re-gimplify the expanded
             form properly, as cleanups might cause the target labels to be
             wrapped in a TRY_FINALLY_EXPR.  To prevent that, we need to
             set up a conditional context.  */
          gimple_push_condition ();
          gimplify_stmt (expr_p, &seq);
          gimple_pop_condition (pre_p);
          gimple_seq_add_seq (pre_p, seq);

          return GS_ALL_DONE;
        }
    }

  /* Now do the normal gimplification.  */

  /* Gimplify condition.  */
  ret = gimplify_expr (&TREE_OPERAND (expr, 0), pre_p, NULL, is_gimple_condexpr,
                       fb_rvalue);
  if (ret == GS_ERROR)
    return GS_ERROR;
  gcc_assert (TREE_OPERAND (expr, 0) != NULL_TREE);

  gimple_push_condition ();

  have_then_clause_p = have_else_clause_p = false;
  if (TREE_OPERAND (expr, 1) != NULL
      && TREE_CODE (TREE_OPERAND (expr, 1)) == GOTO_EXPR
      && TREE_CODE (GOTO_DESTINATION (TREE_OPERAND (expr, 1))) == LABEL_DECL
      && (DECL_CONTEXT (GOTO_DESTINATION (TREE_OPERAND (expr, 1)))
          == current_function_decl)
      /* For -O0 avoid this optimization if the COND_EXPR and GOTO_EXPR
         have different locations, otherwise we end up with incorrect
         location information on the branches.  */
      && (optimize
          || !EXPR_HAS_LOCATION (expr)
          || !EXPR_HAS_LOCATION (TREE_OPERAND (expr, 1))
          || EXPR_LOCATION (expr) == EXPR_LOCATION (TREE_OPERAND (expr, 1))))
    {
      label_true = GOTO_DESTINATION (TREE_OPERAND (expr, 1));
      have_then_clause_p = true;
    }
  else
    label_true = create_artificial_label (UNKNOWN_LOCATION);
  if (TREE_OPERAND (expr, 2) != NULL
      && TREE_CODE (TREE_OPERAND (expr, 2)) == GOTO_EXPR
      && TREE_CODE (GOTO_DESTINATION (TREE_OPERAND (expr, 2))) == LABEL_DECL
      && (DECL_CONTEXT (GOTO_DESTINATION (TREE_OPERAND (expr, 2)))
          == current_function_decl)
      /* For -O0 avoid this optimization if the COND_EXPR and GOTO_EXPR
         have different locations, otherwise we end up with incorrect
         location information on the branches.  */
      && (optimize
          || !EXPR_HAS_LOCATION (expr)
          || !EXPR_HAS_LOCATION (TREE_OPERAND (expr, 2))
          || EXPR_LOCATION (expr) == EXPR_LOCATION (TREE_OPERAND (expr, 2))))
    {
      label_false = GOTO_DESTINATION (TREE_OPERAND (expr, 2));
      have_else_clause_p = true;
    }
  else
    label_false = create_artificial_label (UNKNOWN_LOCATION);

  gimple_cond_get_ops_from_tree (COND_EXPR_COND (expr), &pred_code, &arm1,
                                 &arm2);

  gimple_cond = gimple_build_cond (pred_code, arm1, arm2, label_true,
                                   label_false);

  gimplify_seq_add_stmt (&seq, gimple_cond);
  label_cont = NULL_TREE;
  if (!have_then_clause_p)
    {
      /* For if (...) {} else { code; } put label_true after
         the else block.  */
      if (TREE_OPERAND (expr, 1) == NULL_TREE
          && !have_else_clause_p
          && TREE_OPERAND (expr, 2) != NULL_TREE)
        label_cont = label_true;
      else
        {
          gimplify_seq_add_stmt (&seq, gimple_build_label (label_true));
          have_then_clause_p = gimplify_stmt (&TREE_OPERAND (expr, 1), &seq);
          /* For if (...) { code; } else {} or
             if (...) { code; } else goto label; or
             if (...) { code; return; } else { ... }
             label_cont isn't needed.  */
          if (!have_else_clause_p
              && TREE_OPERAND (expr, 2) != NULL_TREE
              && gimple_seq_may_fallthru (seq))
            {
              gimple g;
              label_cont = create_artificial_label (UNKNOWN_LOCATION);

              g = gimple_build_goto (label_cont);

              /* GIMPLE_COND's are very low level; they have embedded
                 gotos.  This particular embedded goto should not be marked
                 with the location of the original COND_EXPR, as it would
                 correspond to the COND_EXPR's condition, not the ELSE or the
                 THEN arms.  To avoid marking it with the wrong location, flag
                 it as "no location".  */
              gimple_set_do_not_emit_location (g);

              gimplify_seq_add_stmt (&seq, g);
            }
        }
    }
  if (!have_else_clause_p)
    {
      gimplify_seq_add_stmt (&seq, gimple_build_label (label_false));
      have_else_clause_p = gimplify_stmt (&TREE_OPERAND (expr, 2), &seq);
    }
  if (label_cont)
    gimplify_seq_add_stmt (&seq, gimple_build_label (label_cont));

  gimple_pop_condition (pre_p);
  gimple_seq_add_seq (pre_p, seq);

  if (ret == GS_ERROR)
    ; /* Do nothing.  */
  else if (have_then_clause_p || have_else_clause_p)
    ret = GS_ALL_DONE;
  else
    {
      /* Both arms are empty; replace the COND_EXPR with its predicate.  */
      expr = TREE_OPERAND (expr, 0);
      gimplify_stmt (&expr, pre_p);
    }

  *expr_p = NULL;
  return ret;
}

/* Prepare the node pointed to by EXPR_P, an is_gimple_addressable expression,
   to be marked addressable.

   We cannot rely on such an expression being directly markable if a temporary
   has been created by the gimplification.  In this case, we create another
   temporary and initialize it with a copy, which will become a store after we
   mark it addressable.  This can happen if the front-end passed us something
   that it could not mark addressable yet, like a Fortran pass-by-reference
   parameter (int) floatvar.  */

static void
prepare_gimple_addressable (tree *expr_p, gimple_seq *seq_p)
{
  while (handled_component_p (*expr_p))
    expr_p = &TREE_OPERAND (*expr_p, 0);
  if (is_gimple_reg (*expr_p))
    *expr_p = get_initialized_tmp_var (*expr_p, seq_p, NULL);
}

/* A subroutine of gimplify_modify_expr.  Replace a MODIFY_EXPR with
   a call to __builtin_memcpy.  */

static enum gimplify_status
gimplify_modify_expr_to_memcpy (tree *expr_p, tree size, bool want_value,
                                gimple_seq *seq_p)
{
  tree t, to, to_ptr, from, from_ptr;
  gimple gs;
  location_t loc = EXPR_LOCATION (*expr_p);

  to = TREE_OPERAND (*expr_p, 0);
  from = TREE_OPERAND (*expr_p, 1);

  /* Mark the RHS addressable.  Beware that it may not be possible to do so
     directly if a temporary has been created by the gimplification.  */
  prepare_gimple_addressable (&from, seq_p);

  mark_addressable (from);
  from_ptr = build_fold_addr_expr_loc (loc, from);
  gimplify_arg (&from_ptr, seq_p, loc);

  mark_addressable (to);
  to_ptr = build_fold_addr_expr_loc (loc, to);
  gimplify_arg (&to_ptr, seq_p, loc);

  t = implicit_built_in_decls[BUILT_IN_MEMCPY];

  gs = gimple_build_call (t, 3, to_ptr, from_ptr, size);

  if (want_value)
    {
      /* tmp = memcpy() */
      t = create_tmp_var (TREE_TYPE (to_ptr), NULL);
      gimple_call_set_lhs (gs, t);
      gimplify_seq_add_stmt (seq_p, gs);

      *expr_p = build1 (INDIRECT_REF, TREE_TYPE (to), t);
      return GS_ALL_DONE;
    }

  gimplify_seq_add_stmt (seq_p, gs);
  *expr_p = NULL;
  return GS_ALL_DONE;
}

/* A subroutine of gimplify_modify_expr.  Replace a MODIFY_EXPR with
   a call to __builtin_memset.  In this case we know that the RHS is
   a CONSTRUCTOR with an empty element list.  */

static enum gimplify_status
gimplify_modify_expr_to_memset (tree *expr_p, tree size, bool want_value,
                                gimple_seq *seq_p)
{
  tree t, from, to, to_ptr;
  gimple gs;
  location_t loc = EXPR_LOCATION (*expr_p);

  /* Assert our assumptions, to abort instead of producing wrong code
     silently if they are not met.  Beware that the RHS CONSTRUCTOR might
     not be immediately exposed.  */
  from = TREE_OPERAND (*expr_p, 1);
  if (TREE_CODE (from) == WITH_SIZE_EXPR)
    from = TREE_OPERAND (from, 0);

  gcc_assert (TREE_CODE (from) == CONSTRUCTOR
              && VEC_empty (constructor_elt, CONSTRUCTOR_ELTS (from)));

  /* Now proceed.  */
  to = TREE_OPERAND (*expr_p, 0);

  to_ptr = build_fold_addr_expr_loc (loc, to);
  gimplify_arg (&to_ptr, seq_p, loc);
  t = implicit_built_in_decls[BUILT_IN_MEMSET];

  gs = gimple_build_call (t, 3, to_ptr, integer_zero_node, size);

  if (want_value)
    {
      /* tmp = memset() */
      t = create_tmp_var (TREE_TYPE (to_ptr), NULL);
      gimple_call_set_lhs (gs, t);
      gimplify_seq_add_stmt (seq_p, gs);

      *expr_p = build1 (INDIRECT_REF, TREE_TYPE (to), t);
      return GS_ALL_DONE;
    }

  gimplify_seq_add_stmt (seq_p, gs);
  *expr_p = NULL;
  return GS_ALL_DONE;
}

/* A subroutine of gimplify_init_ctor_preeval.  Called via walk_tree,
   determine, cautiously, if a CONSTRUCTOR overlaps the lhs of an
   assignment.  Returns non-null if we detect a potential overlap.  */

struct gimplify_init_ctor_preeval_data
{
  /* The base decl of the lhs object.  May be NULL, in which case we
     have to assume the lhs is indirect.  */
  tree lhs_base_decl;

  /* The alias set of the lhs object.  */
  alias_set_type lhs_alias_set;
};

static tree
gimplify_init_ctor_preeval_1 (tree *tp, int *walk_subtrees, void *xdata)
{
  struct gimplify_init_ctor_preeval_data *data
    = (struct gimplify_init_ctor_preeval_data *) xdata;
  tree t = *tp;

  /* If we find the base object, obviously we have overlap.  */
  if (data->lhs_base_decl == t)
    return t;

  /* If the constructor component is indirect, determine if we have a
     potential overlap with the lhs.  The only bits of information we
     have to go on at this point are addressability and alias sets.  */
  if (TREE_CODE (t) == INDIRECT_REF
      && (!data->lhs_base_decl || TREE_ADDRESSABLE (data->lhs_base_decl))
      && alias_sets_conflict_p (data->lhs_alias_set, get_alias_set (t)))
    return t;

  /* If the constructor component is a call, determine if it can hide a
     potential overlap with the lhs through an INDIRECT_REF like above.  */
  if (TREE_CODE (t) == CALL_EXPR)
    {
      tree type, fntype = TREE_TYPE (TREE_TYPE (CALL_EXPR_FN (t)));

      for (type = TYPE_ARG_TYPES (fntype); type; type = TREE_CHAIN (type))
        if (POINTER_TYPE_P (TREE_VALUE (type))
            && (!data->lhs_base_decl || TREE_ADDRESSABLE (data->lhs_base_decl))
            && alias_sets_conflict_p (data->lhs_alias_set,
                                      get_alias_set
                                        (TREE_TYPE (TREE_VALUE (type)))))
          return t;
    }

  if (IS_TYPE_OR_DECL_P (t))
    *walk_subtrees = 0;
  return NULL;
}

/* A subroutine of gimplify_init_constructor.  Pre-evaluate EXPR,
   force values that overlap with the lhs (as described by *DATA)
   into temporaries.  */

static void
gimplify_init_ctor_preeval (tree *expr_p, gimple_seq *pre_p, gimple_seq *post_p,
                            struct gimplify_init_ctor_preeval_data *data)
{
  enum gimplify_status one;

  /* If the value is constant, then there's nothing to pre-evaluate.  */
  if (TREE_CONSTANT (*expr_p))
    {
      /* Ensure it does not have side effects, it might contain a reference to
         the object we're initializing.  */
      gcc_assert (!TREE_SIDE_EFFECTS (*expr_p));
      return;
    }

  /* If the type has non-trivial constructors, we can't pre-evaluate.  */
  if (TREE_ADDRESSABLE (TREE_TYPE (*expr_p)))
    return;

  /* Recurse for nested constructors.  */
  if (TREE_CODE (*expr_p) == CONSTRUCTOR)
    {
      unsigned HOST_WIDE_INT ix;
      constructor_elt *ce;
      VEC(constructor_elt,gc) *v = CONSTRUCTOR_ELTS (*expr_p);

      for (ix = 0; VEC_iterate (constructor_elt, v, ix, ce); ix++)
        gimplify_init_ctor_preeval (&ce->value, pre_p, post_p, data);

      return;
    }

  /* If this is a variable sized type, we must remember the size.  */
  maybe_with_size_expr (expr_p);

  /* Gimplify the constructor element to something appropriate for the rhs
     of a MODIFY_EXPR.  Given that we know the LHS is an aggregate, we know
     the gimplifier will consider this a store to memory.  Doing this
     gimplification now means that we won't have to deal with complicated
     language-specific trees, nor trees like SAVE_EXPR that can induce
     exponential search behavior.  */
  one = gimplify_expr (expr_p, pre_p, post_p, is_gimple_mem_rhs, fb_rvalue);
  if (one == GS_ERROR)
    {
      *expr_p = NULL;
      return;
    }

  /* If we gimplified to a bare decl, we can be sure that it doesn't overlap
     with the lhs, since "a = { .x=a }" doesn't make sense.  This will
     always be true for all scalars, since is_gimple_mem_rhs insists on a
     temporary variable for them.  */
  if (DECL_P (*expr_p))
    return;

  /* If this is of variable size, we have no choice but to assume it doesn't
     overlap since we can't make a temporary for it.  */
  if (TREE_CODE (TYPE_SIZE (TREE_TYPE (*expr_p))) != INTEGER_CST)
    return;

  /* Otherwise, we must search for overlap ...  */
  if (!walk_tree (expr_p, gimplify_init_ctor_preeval_1, data, NULL))
    return;

  /* ... and if found, force the value into a temporary.  */
  *expr_p = get_formal_tmp_var (*expr_p, pre_p);
}

/* A subroutine of gimplify_init_ctor_eval.  Create a loop for
   a RANGE_EXPR in a CONSTRUCTOR for an array.

      var = lower;
    loop_entry:
      object[var] = value;
      if (var == upper)
        goto loop_exit;
      var = var + 1;
      goto loop_entry;
    loop_exit:

   We increment var _after_ the loop exit check because we might otherwise
   fail if upper == TYPE_MAX_VALUE (type for upper).

   Note that we never have to deal with SAVE_EXPRs here, because this has
   already been taken care of for us, in gimplify_init_ctor_preeval().  */

static void gimplify_init_ctor_eval (tree, VEC(constructor_elt,gc) *,
                                     gimple_seq *, bool);

static void
gimplify_init_ctor_eval_range (tree object, tree lower, tree upper,
                               tree value, tree array_elt_type,
                               gimple_seq *pre_p, bool cleared)
{
  tree loop_entry_label, loop_exit_label, fall_thru_label;
  tree var, var_type, cref, tmp;

  loop_entry_label = create_artificial_label (UNKNOWN_LOCATION);
  loop_exit_label = create_artificial_label (UNKNOWN_LOCATION);
  fall_thru_label = create_artificial_label (UNKNOWN_LOCATION);

  /* Create and initialize the index variable.  */
  var_type = TREE_TYPE (upper);
  var = create_tmp_var (var_type, NULL);
  gimplify_seq_add_stmt (pre_p, gimple_build_assign (var, lower));

  /* Add the loop entry label.  */
  gimplify_seq_add_stmt (pre_p, gimple_build_label (loop_entry_label));

  /* Build the reference.  */
  cref = build4 (ARRAY_REF, array_elt_type, unshare_expr (object),
                 var, NULL_TREE, NULL_TREE);

  /* If we are a constructor, just call gimplify_init_ctor_eval to do
     the store.  Otherwise just assign value to the reference.  */

  if (TREE_CODE (value) == CONSTRUCTOR)
    /* NB we might have to call ourself recursively through
       gimplify_init_ctor_eval if the value is a constructor.  */
    gimplify_init_ctor_eval (cref, CONSTRUCTOR_ELTS (value),
                             pre_p, cleared);
  else
    gimplify_seq_add_stmt (pre_p, gimple_build_assign (cref, value));

  /* We exit the loop when the index var is equal to the upper bound.  */
  gimplify_seq_add_stmt (pre_p,
                         gimple_build_cond (EQ_EXPR, var, upper,
                                            loop_exit_label, fall_thru_label));

  gimplify_seq_add_stmt (pre_p, gimple_build_label (fall_thru_label));

  /* Otherwise, increment the index var...  */
  tmp = build2 (PLUS_EXPR, var_type, var,
                fold_convert (var_type, integer_one_node));
  gimplify_seq_add_stmt (pre_p, gimple_build_assign (var, tmp));

  /* ...and jump back to the loop entry.  */
  gimplify_seq_add_stmt (pre_p, gimple_build_goto (loop_entry_label));

  /* Add the loop exit label.  */
  gimplify_seq_add_stmt (pre_p, gimple_build_label (loop_exit_label));
}

/* Return true if FDECL is accessing a field that is zero sized.  */

static bool
zero_sized_field_decl (const_tree fdecl)
{
  if (TREE_CODE (fdecl) == FIELD_DECL && DECL_SIZE (fdecl)
      && integer_zerop (DECL_SIZE (fdecl)))
    return true;
  return false;
}

/* Return true if TYPE is zero sized.  */

static bool
zero_sized_type (const_tree type)
{
  if (AGGREGATE_TYPE_P (type) && TYPE_SIZE (type)
      && integer_zerop (TYPE_SIZE (type)))
    return true;
  return false;
}

/* A subroutine of gimplify_init_constructor.  Generate individual
   MODIFY_EXPRs for a CONSTRUCTOR.  OBJECT is the LHS against which the
   assignments should happen.  ELTS is the CONSTRUCTOR_ELTS of the
   CONSTRUCTOR.  CLEARED is true if the entire LHS object has been
   zeroed first.  */

static void
gimplify_init_ctor_eval (tree object, VEC(constructor_elt,gc) *elts,
                         gimple_seq *pre_p, bool cleared)
{
  tree array_elt_type = NULL;
  unsigned HOST_WIDE_INT ix;
  tree purpose, value;

  if (TREE_CODE (TREE_TYPE (object)) == ARRAY_TYPE)
    array_elt_type = TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (object)));

  FOR_EACH_CONSTRUCTOR_ELT (elts, ix, purpose, value)
    {
      tree cref;

      /* NULL values are created above for gimplification errors.  */
      if (value == NULL)
        continue;

      if (cleared && initializer_zerop (value))
        continue;

      /* ??? Here's to hoping the front end fills in all of the indices,
         so we don't have to figure out what's missing ourselves.  */
      gcc_assert (purpose);

      /* Skip zero-sized fields, unless value has side-effects.  This can
         happen with calls to functions returning a zero-sized type, which
         we shouldn't discard.  As a number of downstream passes don't
         expect sets of zero-sized fields, we rely on the gimplification of
         the MODIFY_EXPR we make below to drop the assignment statement.  */
      if (! TREE_SIDE_EFFECTS (value) && zero_sized_field_decl (purpose))
        continue;

      /* If we have a RANGE_EXPR, we have to build a loop to assign the
         whole range.  */
      if (TREE_CODE (purpose) == RANGE_EXPR)
        {
          tree lower = TREE_OPERAND (purpose, 0);
          tree upper = TREE_OPERAND (purpose, 1);

          /* If the lower bound is equal to upper, just treat it as if
             upper was the index.  */
          if (simple_cst_equal (lower, upper))
            purpose = upper;
          else
            {
              gimplify_init_ctor_eval_range (object, lower, upper, value,
                                             array_elt_type, pre_p, cleared);
              continue;
            }
        }

      if (array_elt_type)
        {
          /* Do not use bitsizetype for ARRAY_REF indices.  */
          if (TYPE_DOMAIN (TREE_TYPE (object)))
            purpose = fold_convert (TREE_TYPE (TYPE_DOMAIN (TREE_TYPE (object))),
                                    purpose);
          cref = build4 (ARRAY_REF, array_elt_type, unshare_expr (object),
                         purpose, NULL_TREE, NULL_TREE);
        }
      else
        {
          gcc_assert (TREE_CODE (purpose) == FIELD_DECL);
          cref = build3 (COMPONENT_REF, TREE_TYPE (purpose),
                         unshare_expr (object), purpose, NULL_TREE);
        }

      if (TREE_CODE (value) == CONSTRUCTOR
          && TREE_CODE (TREE_TYPE (value)) != VECTOR_TYPE)
        gimplify_init_ctor_eval (cref, CONSTRUCTOR_ELTS (value),
                                 pre_p, cleared);
      else
        {
          tree init = build2 (INIT_EXPR, TREE_TYPE (cref), cref, value);
          gimplify_and_add (init, pre_p);
          ggc_free (init);
        }
    }
}


/* Returns the appropriate RHS predicate for this LHS.  */

gimple_predicate
rhs_predicate_for (tree lhs)
{
  if (is_gimple_reg (lhs))
    return is_gimple_reg_rhs_or_call;
  else
    return is_gimple_mem_rhs_or_call;
}

/* Gimplify a C99 compound literal expression.  This just means adding
   the DECL_EXPR before the current statement and using its anonymous
   decl instead.  */

static enum gimplify_status
gimplify_compound_literal_expr (tree *expr_p, gimple_seq *pre_p)
{
  tree decl_s = COMPOUND_LITERAL_EXPR_DECL_EXPR (*expr_p);
  tree decl = DECL_EXPR_DECL (decl_s);
  /* Mark the decl as addressable if the compound literal
     expression is addressable now, otherwise it is marked too late
     after we gimplify the initialization expression.  */
  if (TREE_ADDRESSABLE (*expr_p))
    TREE_ADDRESSABLE (decl) = 1;

  /* Preliminarily mark non-addressed complex variables as eligible
     for promotion to gimple registers.  We'll transform their uses
     as we find them.  */
  if ((TREE_CODE (TREE_TYPE (decl)) == COMPLEX_TYPE
       || TREE_CODE (TREE_TYPE (decl)) == VECTOR_TYPE)
      && !TREE_THIS_VOLATILE (decl)
      && !needs_to_live_in_memory (decl))
    DECL_GIMPLE_REG_P (decl) = 1;

  /* This decl isn't mentioned in the enclosing block, so add it to the
     list of temps.  FIXME it seems a bit of a kludge to say that
     anonymous artificial vars aren't pushed, but everything else is.  */
  if (DECL_NAME (decl) == NULL_TREE && !DECL_SEEN_IN_BIND_EXPR_P (decl))
    gimple_add_tmp_var (decl);

  gimplify_and_add (decl_s, pre_p);
  *expr_p = decl;
  return GS_OK;
}

/* Optimize embedded COMPOUND_LITERAL_EXPRs within a CONSTRUCTOR,
   return a new CONSTRUCTOR if something changed.  */

static tree
optimize_compound_literals_in_ctor (tree orig_ctor)
{
  tree ctor = orig_ctor;
  VEC(constructor_elt,gc) *elts = CONSTRUCTOR_ELTS (ctor);
  unsigned int idx, num = VEC_length (constructor_elt, elts);

  for (idx = 0; idx < num; idx++)
    {
      tree value = VEC_index (constructor_elt, elts, idx)->value;
      tree newval = value;
      if (TREE_CODE (value) == CONSTRUCTOR)
        newval = optimize_compound_literals_in_ctor (value);
      else if (TREE_CODE (value) == COMPOUND_LITERAL_EXPR)
        {
          tree decl_s = COMPOUND_LITERAL_EXPR_DECL_EXPR (value);
          tree decl = DECL_EXPR_DECL (decl_s);
          tree init = DECL_INITIAL (decl);

          if (!TREE_ADDRESSABLE (value)
              && !TREE_ADDRESSABLE (decl)
              && init)
            newval = optimize_compound_literals_in_ctor (init);
        }
      if (newval == value)
        continue;

      if (ctor == orig_ctor)
        {
          ctor = copy_node (orig_ctor);
          CONSTRUCTOR_ELTS (ctor) = VEC_copy (constructor_elt, gc, elts);
          elts = CONSTRUCTOR_ELTS (ctor);
        }
      VEC_index (constructor_elt, elts, idx)->value = newval;
    }
  return ctor;
}



/* A subroutine of gimplify_modify_expr.  Break out elements of a
   CONSTRUCTOR used as an initializer into separate MODIFY_EXPRs.

   Note that we still need to clear any elements that don't have explicit
   initializers, so if not all elements are initialized we keep the
   original MODIFY_EXPR, we just remove all of the constructor elements.

   If NOTIFY_TEMP_CREATION is true, do not gimplify, just return
   GS_ERROR if we would have to create a temporary when gimplifying
   this constructor.  Otherwise, return GS_OK.

   If NOTIFY_TEMP_CREATION is false, just do the gimplification.  */

static enum gimplify_status
gimplify_init_constructor (tree *expr_p, gimple_seq *pre_p, gimple_seq *post_p,
                           bool want_value, bool notify_temp_creation)
{
  tree object, ctor, type;
  enum gimplify_status ret;
  VEC(constructor_elt,gc) *elts;

  gcc_assert (TREE_CODE (TREE_OPERAND (*expr_p, 1)) == CONSTRUCTOR);

  if (!notify_temp_creation)
    {
      ret = gimplify_expr (&TREE_OPERAND (*expr_p, 0), pre_p, post_p,
                           is_gimple_lvalue, fb_lvalue);
      if (ret == GS_ERROR)
        return ret;
    }

  object = TREE_OPERAND (*expr_p, 0);
  ctor = TREE_OPERAND (*expr_p, 1) =
    optimize_compound_literals_in_ctor (TREE_OPERAND (*expr_p, 1));
  type = TREE_TYPE (ctor);
  elts = CONSTRUCTOR_ELTS (ctor);
  ret = GS_ALL_DONE;

  switch (TREE_CODE (type))
    {
    case RECORD_TYPE:
    case UNION_TYPE:
    case QUAL_UNION_TYPE:
    case ARRAY_TYPE:
      {
        struct gimplify_init_ctor_preeval_data preeval_data;
        HOST_WIDE_INT num_type_elements, num_ctor_elements;
        HOST_WIDE_INT num_nonzero_elements;
        bool cleared, valid_const_initializer;

        /* Aggregate types must lower constructors to initialization of
           individual elements.  The exception is that a CONSTRUCTOR node
           with no elements indicates zero-initialization of the whole.  */
        if (VEC_empty (constructor_elt, elts))
          {
            if (notify_temp_creation)
              return GS_OK;
            break;
          }

        /* Fetch information about the constructor to direct later processing.
           We might want to make static versions of it in various cases, and
           can only do so if it known to be a valid constant initializer.  */
        valid_const_initializer
          = categorize_ctor_elements (ctor, &num_nonzero_elements,
                                      &num_ctor_elements, &cleared);

        /* If a const aggregate variable is being initialized, then it
           should never be a lose to promote the variable to be static.  */
        if (valid_const_initializer
            && num_nonzero_elements > 1
            && TREE_READONLY (object)
            && TREE_CODE (object) == VAR_DECL
            && (flag_merge_constants >= 2 || !TREE_ADDRESSABLE (object)))
          {
            if (notify_temp_creation)
              return GS_ERROR;
            DECL_INITIAL (object) = ctor;
            TREE_STATIC (object) = 1;
            if (!DECL_NAME (object))
              DECL_NAME (object) = create_tmp_var_name ("C");
            walk_tree (&DECL_INITIAL (object), force_labels_r, NULL, NULL);

            /* ??? C++ doesn't automatically append a .<number> to the
               assembler name, and even when it does, it looks a FE private
               data structures to figure out what that number should be,
               which are not set for this variable.  I suppose this is
               important for local statics for inline functions, which aren't
               "local" in the object file sense.  So in order to get a unique
               TU-local symbol, we must invoke the lhd version now.  */
            lhd_set_decl_assembler_name (object);

            *expr_p = NULL_TREE;
            break;
          }

        /* If there are "lots" of initialized elements, even discounting
           those that are not address constants (and thus *must* be
           computed at runtime), then partition the constructor into
           constant and non-constant parts.  Block copy the constant
           parts in, then generate code for the non-constant parts.  */
        /* TODO.  There's code in cp/typeck.c to do this.  */

        num_type_elements = count_type_elements (type, true);

        /* If count_type_elements could not determine number of type elements
           for a constant-sized object, assume clearing is needed.
           Don't do this for variable-sized objects, as store_constructor
           will ignore the clearing of variable-sized objects.  */
        if (num_type_elements < 0 && int_size_in_bytes (type) >= 0)
          cleared = true;
        /* If there are "lots" of zeros, then block clear the object first.  */
        else if (num_type_elements - num_nonzero_elements
                 > CLEAR_RATIO (optimize_function_for_speed_p (cfun))
                 && num_nonzero_elements < num_type_elements/4)
          cleared = true;
        /* ??? This bit ought not be needed.  For any element not present
           in the initializer, we should simply set them to zero.  Except
           we'd need to *find* the elements that are not present, and that
           requires trickery to avoid quadratic compile-time behavior in
           large cases or excessive memory use in small cases.  */
        else if (num_ctor_elements < num_type_elements)
          cleared = true;

        /* If there are "lots" of initialized elements, and all of them
           are valid address constants, then the entire initializer can
           be dropped to memory, and then memcpy'd out.  Don't do this
           for sparse arrays, though, as it's more efficient to follow
           the standard CONSTRUCTOR behavior of memset followed by
           individual element initialization.  Also don't do this for small
           all-zero initializers (which aren't big enough to merit
           clearing), and don't try to make bitwise copies of
           TREE_ADDRESSABLE types.  */
        if (valid_const_initializer
            && !(cleared || num_nonzero_elements == 0)
            && !TREE_ADDRESSABLE (type))
          {
            HOST_WIDE_INT size = int_size_in_bytes (type);
            unsigned int align;

            /* ??? We can still get unbounded array types, at least
               from the C++ front end.  This seems wrong, but attempt
               to work around it for now.  */
            if (size < 0)
              {
                size = int_size_in_bytes (TREE_TYPE (object));
                if (size >= 0)
                  TREE_TYPE (ctor) = type = TREE_TYPE (object);
              }

            /* Find the maximum alignment we can assume for the object.  */
            /* ??? Make use of DECL_OFFSET_ALIGN.  */
            if (DECL_P (object))
              align = DECL_ALIGN (object);
            else
              align = TYPE_ALIGN (type);

            if (size > 0
                && num_nonzero_elements > 1
                && !can_move_by_pieces (size, align))
              {
                if (notify_temp_creation)
                  return GS_ERROR;

                walk_tree (&ctor, force_labels_r, NULL, NULL);
                TREE_OPERAND (*expr_p, 1) = tree_output_constant_def (ctor);

                /* This is no longer an assignment of a CONSTRUCTOR, but
                   we still may have processing to do on the LHS.  So
                   pretend we didn't do anything here to let that happen.  */
                return GS_UNHANDLED;
              }
          }

        /* If the target is volatile and we have non-zero elements
           initialize the target from a temporary.  */
        if (TREE_THIS_VOLATILE (object)
            && !TREE_ADDRESSABLE (type)
            && num_nonzero_elements > 0)
          {
            tree temp = create_tmp_var (TYPE_MAIN_VARIANT (type), NULL);
            TREE_OPERAND (*expr_p, 0) = temp;
            *expr_p = build2 (COMPOUND_EXPR, TREE_TYPE (*expr_p),
                              *expr_p,
                              build2 (MODIFY_EXPR, void_type_node,
                                      object, temp));
            return GS_OK;
          }

        if (notify_temp_creation)
          return GS_OK;

        /* If there are nonzero elements and if needed, pre-evaluate to capture
           elements overlapping with the lhs into temporaries.  We must do this
           before clearing to fetch the values before they are zeroed-out.  */
        if (num_nonzero_elements > 0 && TREE_CODE (*expr_p) != INIT_EXPR)
          {
            preeval_data.lhs_base_decl = get_base_address (object);
            if (!DECL_P (preeval_data.lhs_base_decl))
              preeval_data.lhs_base_decl = NULL;
            preeval_data.lhs_alias_set = get_alias_set (object);

            gimplify_init_ctor_preeval (&TREE_OPERAND (*expr_p, 1),
                                        pre_p, post_p, &preeval_data);
          }

        if (cleared)
          {
            /* Zap the CONSTRUCTOR element list, which simplifies this case.
               Note that we still have to gimplify, in order to handle the
               case of variable sized types.  Avoid shared tree structures.  */
            CONSTRUCTOR_ELTS (ctor) = NULL;
            TREE_SIDE_EFFECTS (ctor) = 0;
            object = unshare_expr (object);
            gimplify_stmt (expr_p, pre_p);
          }

        /* If we have not block cleared the object, or if there are nonzero
           elements in the constructor, add assignments to the individual
           scalar fields of the object.  */
        if (!cleared || num_nonzero_elements > 0)
          gimplify_init_ctor_eval (object, elts, pre_p, cleared);

        *expr_p = NULL_TREE;
      }
      break;

    case COMPLEX_TYPE:
      {
        tree r, i;

        if (notify_temp_creation)
          return GS_OK;

        /* Extract the real and imaginary parts out of the ctor.  */
        gcc_assert (VEC_length (constructor_elt, elts) == 2);
        r = VEC_index (constructor_elt, elts, 0)->value;
        i = VEC_index (constructor_elt, elts, 1)->value;
        if (r == NULL || i == NULL)
          {
            tree zero = fold_convert (TREE_TYPE (type), integer_zero_node);
            if (r == NULL)
              r = zero;
            if (i == NULL)
              i = zero;
          }

        /* Complex types have either COMPLEX_CST or COMPLEX_EXPR to
           represent creation of a complex value.  */
        if (TREE_CONSTANT (r) && TREE_CONSTANT (i))
          {
            ctor = build_complex (type, r, i);
            TREE_OPERAND (*expr_p, 1) = ctor;
          }
        else
          {
            ctor = build2 (COMPLEX_EXPR, type, r, i);
            TREE_OPERAND (*expr_p, 1) = ctor;
            ret = gimplify_expr (&TREE_OPERAND (*expr_p, 1),
                                 pre_p,
                                 post_p,
                                 rhs_predicate_for (TREE_OPERAND (*expr_p, 0)),
                                 fb_rvalue);
          }
      }
      break;

    case VECTOR_TYPE:
      {
        unsigned HOST_WIDE_INT ix;
        constructor_elt *ce;

        if (notify_temp_creation)
          return GS_OK;

        /* Go ahead and simplify constant constructors to VECTOR_CST.  */
        if (TREE_CONSTANT (ctor))
          {
            bool constant_p = true;
            tree value;

            /* Even when ctor is constant, it might contain non-*_CST
               elements, such as addresses or trapping values like
               1.0/0.0 - 1.0/0.0.  Such expressions don't belong
               in VECTOR_CST nodes.  */
            FOR_EACH_CONSTRUCTOR_VALUE (elts, ix, value)
              if (!CONSTANT_CLASS_P (value))
                {
                  constant_p = false;
                  break;
                }

            if (constant_p)
              {
                TREE_OPERAND (*expr_p, 1) = build_vector_from_ctor (type, elts);
                break;
              }

            /* Don't reduce an initializer constant even if we can't
               make a VECTOR_CST.  It won't do anything for us, and it'll
               prevent us from representing it as a single constant.  */
            if (initializer_constant_valid_p (ctor, type))
              break;

            TREE_CONSTANT (ctor) = 0;
          }

        /* Vector types use CONSTRUCTOR all the way through gimple
          compilation as a general initializer.  */
        for (ix = 0; VEC_iterate (constructor_elt, elts, ix, ce); ix++)
          {
            enum gimplify_status tret;
            tret = gimplify_expr (&ce->value, pre_p, post_p, is_gimple_val,
                                  fb_rvalue);
            if (tret == GS_ERROR)
              ret = GS_ERROR;
          }
        if (!is_gimple_reg (TREE_OPERAND (*expr_p, 0)))
          TREE_OPERAND (*expr_p, 1) = get_formal_tmp_var (ctor, pre_p);
      }
      break;

    default:
      /* So how did we get a CONSTRUCTOR for a scalar type?  */
      gcc_unreachable ();
    }

  if (ret == GS_ERROR)
    return GS_ERROR;
  else if (want_value)
    {
      *expr_p = object;
      return GS_OK;
    }
  else
    {
      /* If we have gimplified both sides of the initializer but have
         not emitted an assignment, do so now.  */
      if (*expr_p)
        {
          tree lhs = TREE_OPERAND (*expr_p, 0);
          tree rhs = TREE_OPERAND (*expr_p, 1);
          gimple init = gimple_build_assign (lhs, rhs);
          gimplify_seq_add_stmt (pre_p, init);
          *expr_p = NULL;
        }

      return GS_ALL_DONE;
    }
}

/* Given a pointer value OP0, return a simplified version of an
   indirection through OP0, or NULL_TREE if no simplification is
   possible.  Note that the resulting type may be different from
   the type pointed to in the sense that it is still compatible
   from the langhooks point of view. */

tree
gimple_fold_indirect_ref (tree t)
{
  tree type = TREE_TYPE (TREE_TYPE (t));
  tree sub = t;
  tree subtype;

  STRIP_NOPS (sub);
  subtype = TREE_TYPE (sub);
  if (!POINTER_TYPE_P (subtype))
    return NULL_TREE;

  if (TREE_CODE (sub) == ADDR_EXPR)
    {
      tree op = TREE_OPERAND (sub, 0);
      tree optype = TREE_TYPE (op);
      /* *&p => p */
      if (useless_type_conversion_p (type, optype))
        return op;

      /* *(foo *)&fooarray => fooarray[0] */
      if (TREE_CODE (optype) == ARRAY_TYPE
          && TREE_CODE (TYPE_SIZE (TREE_TYPE (optype))) == INTEGER_CST
          && useless_type_conversion_p (type, TREE_TYPE (optype)))
       {
         tree type_domain = TYPE_DOMAIN (optype);
         tree min_val = size_zero_node;
         if (type_domain && TYPE_MIN_VALUE (type_domain))
           min_val = TYPE_MIN_VALUE (type_domain);
         if (TREE_CODE (min_val) == INTEGER_CST)
           return build4 (ARRAY_REF, type, op, min_val, NULL_TREE, NULL_TREE);
       }
      /* *(foo *)&complexfoo => __real__ complexfoo */
      else if (TREE_CODE (optype) == COMPLEX_TYPE
               && useless_type_conversion_p (type, TREE_TYPE (optype)))
        return fold_build1 (REALPART_EXPR, type, op);
      /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
      else if (TREE_CODE (optype) == VECTOR_TYPE
               && useless_type_conversion_p (type, TREE_TYPE (optype)))
        {
          tree part_width = TYPE_SIZE (type);
          tree index = bitsize_int (0);
          return fold_build3 (BIT_FIELD_REF, type, op, part_width, index);
        }
    }

  /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
  if (TREE_CODE (sub) == POINTER_PLUS_EXPR
      && TREE_CODE (TREE_OPERAND (sub, 1)) == INTEGER_CST)
    {
      tree op00 = TREE_OPERAND (sub, 0);
      tree op01 = TREE_OPERAND (sub, 1);
      tree op00type;

      STRIP_NOPS (op00);
      op00type = TREE_TYPE (op00);
      if (TREE_CODE (op00) == ADDR_EXPR
          && TREE_CODE (TREE_TYPE (op00type)) == VECTOR_TYPE
          && useless_type_conversion_p (type, TREE_TYPE (TREE_TYPE (op00type))))
        {
          HOST_WIDE_INT offset = tree_low_cst (op01, 0);
          tree part_width = TYPE_SIZE (type);
          unsigned HOST_WIDE_INT part_widthi
            = tree_low_cst (part_width, 0) / BITS_PER_UNIT;
          unsigned HOST_WIDE_INT indexi = offset * BITS_PER_UNIT;
          tree index = bitsize_int (indexi);
          if (offset / part_widthi
              <= TYPE_VECTOR_SUBPARTS (TREE_TYPE (op00type)))
            return fold_build3 (BIT_FIELD_REF, type, TREE_OPERAND (op00, 0),
                                part_width, index);
        }
    }

  /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
  if (TREE_CODE (sub) == POINTER_PLUS_EXPR
      && TREE_CODE (TREE_OPERAND (sub, 1)) == INTEGER_CST)
    {
      tree op00 = TREE_OPERAND (sub, 0);
      tree op01 = TREE_OPERAND (sub, 1);
      tree op00type;

      STRIP_NOPS (op00);
      op00type = TREE_TYPE (op00);
      if (TREE_CODE (op00) == ADDR_EXPR
          && TREE_CODE (TREE_TYPE (op00type)) == COMPLEX_TYPE
          && useless_type_conversion_p (type, TREE_TYPE (TREE_TYPE (op00type))))
        {
          tree size = TYPE_SIZE_UNIT (type);
          if (tree_int_cst_equal (size, op01))
            return fold_build1 (IMAGPART_EXPR, type, TREE_OPERAND (op00, 0));
        }
    }

  /* *(foo *)fooarrptr => (*fooarrptr)[0] */
  if (TREE_CODE (TREE_TYPE (subtype)) == ARRAY_TYPE
      && TREE_CODE (TYPE_SIZE (TREE_TYPE (TREE_TYPE (subtype)))) == INTEGER_CST
      && useless_type_conversion_p (type, TREE_TYPE (TREE_TYPE (subtype))))
    {
      tree type_domain;
      tree min_val = size_zero_node;
      tree osub = sub;
      sub = gimple_fold_indirect_ref (sub);
      if (! sub)
        sub = build1 (INDIRECT_REF, TREE_TYPE (subtype), osub);
      type_domain = TYPE_DOMAIN (TREE_TYPE (sub));
      if (type_domain && TYPE_MIN_VALUE (type_domain))
        min_val = TYPE_MIN_VALUE (type_domain);
      if (TREE_CODE (min_val) == INTEGER_CST)
        return build4 (ARRAY_REF, type, sub, min_val, NULL_TREE, NULL_TREE);
    }

  return NULL_TREE;
}

/* Given a pointer value OP0, return a simplified version of an
   indirection through OP0, or NULL_TREE if no simplification is
   possible.  This may only be applied to a rhs of an expression.
   Note that the resulting type may be different from the type pointed
   to in the sense that it is still compatible from the langhooks
   point of view. */

static tree
gimple_fold_indirect_ref_rhs (tree t)
{
  return gimple_fold_indirect_ref (t);
}

/* Subroutine of gimplify_modify_expr to do simplifications of
   MODIFY_EXPRs based on the code of the RHS.  We loop for as long as
   something changes.  */

static enum gimplify_status
gimplify_modify_expr_rhs (tree *expr_p, tree *from_p, tree *to_p,
                          gimple_seq *pre_p, gimple_seq *post_p,
                          bool want_value)
{
  enum gimplify_status ret = GS_UNHANDLED;
  bool changed;

  do
    {
      changed = false;
      switch (TREE_CODE (*from_p))
        {
        case VAR_DECL:
          /* If we're assigning from a read-only variable initialized with
             a constructor, do the direct assignment from the constructor,
             but only if neither source nor target are volatile since this
             latter assignment might end up being done on a per-field basis.  */
          if (DECL_INITIAL (*from_p)
              && TREE_READONLY (*from_p)
              && !TREE_THIS_VOLATILE (*from_p)
              && !TREE_THIS_VOLATILE (*to_p)
              && TREE_CODE (DECL_INITIAL (*from_p)) == CONSTRUCTOR)
            {
              tree old_from = *from_p;
              enum gimplify_status subret;

              /* Move the constructor into the RHS.  */
              *from_p = unshare_expr (DECL_INITIAL (*from_p));

              /* Let's see if gimplify_init_constructor will need to put
                 it in memory.  */
              subret = gimplify_init_constructor (expr_p, NULL, NULL,
                                                  false, true);
              if (subret == GS_ERROR)
                {
                  /* If so, revert the change.  */
                  *from_p = old_from;
                }
              else
                {
                  ret = GS_OK;
                  changed = true;
                }
            }
          break;
        case INDIRECT_REF:
          {
            /* If we have code like

             *(const A*)(A*)&x

             where the type of "x" is a (possibly cv-qualified variant
             of "A"), treat the entire expression as identical to "x".
             This kind of code arises in C++ when an object is bound
             to a const reference, and if "x" is a TARGET_EXPR we want
             to take advantage of the optimization below.  */
            tree t = gimple_fold_indirect_ref_rhs (TREE_OPERAND (*from_p, 0));
            if (t)
              {
                *from_p = t;
                ret = GS_OK;
                changed = true;
              }
            break;
          }

        case TARGET_EXPR:
          {
            /* If we are initializing something from a TARGET_EXPR, strip the
               TARGET_EXPR and initialize it directly, if possible.  This can't
               be done if the initializer is void, since that implies that the
               temporary is set in some non-trivial way.

               ??? What about code that pulls out the temp and uses it
               elsewhere? I think that such code never uses the TARGET_EXPR as
               an initializer.  If I'm wrong, we'll die because the temp won't
               have any RTL.  In that case, I guess we'll need to replace
               references somehow.  */