gimplify.c

  if (cgn)
    for (cgn = cgn->nested; cgn; cgn = cgn->next_nested)
      unvisit_body (cgn->symbol.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;
}

/* Worker for unshare_expr_without_location.  */

static tree
prune_expr_location (tree *tp, int *walk_subtrees, void *)
{
  if (EXPR_P (*tp))
    SET_EXPR_LOCATION (*tp, UNKNOWN_LOCATION);
  else
    *walk_subtrees = 0;
  return NULL_TREE;
}

/* Similar to unshare_expr but also prune all expression locations
   from EXPR.  */

tree
unshare_expr_without_location (tree expr)
{
  walk_tree (&expr, mostly_copy_tree_r, NULL, NULL);
  if (EXPR_P (expr))
    walk_tree (&expr, prune_expr_location, NULL, NULL);
  return expr;
}

/* 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.  Return 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;

	    case TRANSACTION_EXPR:
	      TREE_SIDE_EFFECTS (*p) = 1;
	      TREE_TYPE (*p) = void_type_node;
	      p = &TRANSACTION_EXPR_BODY (*p);
	      break;

	    default:
	      /* Assume that any tree upon which voidify_wrapper_expr is
		 directly called is a wrapper, and that its body is op0.  */
	      if (p == &wrapper)
		{
		  TREE_SIDE_EFFECTS (*p) = 1;
		  TREE_TYPE (*p) = void_type_node;
		  p = &TREE_OPERAND (*p, 0);
		  break;
		}
	      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 (builtin_decl_implicit (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 (builtin_decl_implicit (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, cleanup;
  gimple stack_save;

  tree temp = voidify_wrapper_expr (bind_expr, NULL);

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

	  /* Mark variable as local.  */
	  if (ctx && !DECL_EXTERNAL (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.  */
      if ((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);

  cleanup = NULL;
  stack_save = NULL;
  if (gimplify_ctxp->save_stack)
    {
      gimple stack_restore;

      /* 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);

      gimplify_seq_add_stmt (&cleanup, stack_restore);
    }

  /* Add clobbers for all variables that go out of scope.  */
  for (t = BIND_EXPR_VARS (bind_expr); t ; t = DECL_CHAIN (t))
    {
      if (TREE_CODE (t) == VAR_DECL
	  && !is_global_var (t)
	  && DECL_CONTEXT (t) == current_function_decl
	  && !DECL_HARD_REGISTER (t)
	  && !TREE_THIS_VOLATILE (t)
	  && !DECL_HAS_VALUE_EXPR_P (t)
	  /* Only care for variables that have to be in memory.  Others
	     will be rewritten into SSA names, hence moved to the top-level.  */
	  && !is_gimple_reg (t)
	  && flag_stack_reuse != SR_NONE)
	{
	  tree clobber = build_constructor (TREE_TYPE (t),
					    NULL);
	  TREE_THIS_VOLATILE (clobber) = 1;
	  gimplify_seq_add_stmt (&cleanup, gimple_build_assign (t, clobber));
	}
    }

  if (cleanup)
    {
      gimple gs;
      gimple_seq new_body;

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

      if (stack_save)
	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;
}

/* Gimplify a variable-length array DECL.  */

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);

  /* Don't mess with a DECL_VALUE_EXPR set by the front-end.  */
  if (DECL_HAS_VALUE_EXPR_P (decl))
    return;

  /* 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);
  TREE_THIS_NOTRAP (t) = 1;
  SET_DECL_VALUE_EXPR (decl, t);
  DECL_HAS_VALUE_EXPR_P (decl) = 1;

  t = builtin_decl_explicit (BUILT_IN_ALLOCA_WITH_ALIGN);
  t = build_call_expr (t, 2, DECL_SIZE_UNIT (decl),
		       size_int (DECL_ALIGN (decl)));
  /* The call has been built for a variable-sized object.  */
  CALL_ALLOCA_FOR_VAR_P (t) = 1;
  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;
}

/* Gimplify 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);

  /* ??? DECL_ORIGINAL_TYPE is streamed for LTO so it needs to be gimplified
     in case its size expressions contain problematic nodes like CALL_EXPR.  */
  if (TREE_CODE (decl) == TYPE_DECL
      && DECL_ORIGINAL_TYPE (decl)
      && !TYPE_SIZES_GIMPLIFIED (DECL_ORIGINAL_TYPE (decl)))
    gimplify_type_sizes (DECL_ORIGINAL_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);

      /* 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);

      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);
	}
    }

  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;
}

/* Gimplify 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> label_vec)
{
  label_vec.qsort (compare_case_labels);
}

/* Prepare a vector of case labels to be used in a GIMPLE_SWITCH statement.

   LABELS is a vector that contains all case labels to look at.

   INDEX_TYPE is the type of the switch index expression.  Case labels
   in LABELS are discarded if their values are not in the value range
   covered by INDEX_TYPE.  The remaining case label values are folded
   to INDEX_TYPE.

   If a default case exists in LABELS, it is removed from LABELS and
   returned in DEFAULT_CASEP.  If no default case exists, but the
   case labels already cover the whole range of INDEX_TYPE, a default
   case is returned pointing to one of the existing case labels.
   Otherwise DEFAULT_CASEP is set to NULL_TREE.

   DEFAULT_CASEP may be NULL, in which case the above comment doesn't
   apply and no action is taken regardless of whether a default case is
   found or not.  */

void
preprocess_case_label_vec_for_gimple (vec<tree> labels,
				      tree index_type,
				      tree *default_casep)
{
  tree min_value, max_value;
  tree default_case = NULL_TREE;
  size_t i, len;

  i = 0;
  min_value = TYPE_MIN_VALUE (index_type);
  max_value = TYPE_MAX_VALUE (index_type);
  while (i < labels.length ())
    {
      tree elt = labels[i];
      tree low = CASE_LOW (elt);
      tree high = CASE_HIGH (elt);
      bool remove_element = FALSE;

      if (low)
	{
	  gcc_checking_assert (TREE_CODE (low) == INTEGER_CST);
	  gcc_checking_assert (!high || TREE_CODE (high) == INTEGER_CST);

	  /* This is a non-default case label, i.e. it has a value.

	     See if the case label is reachable within the range of
	     the index type.  Remove out-of-range case values.  Turn
	     case ranges into a canonical form (high > low strictly)
	     and convert the case label values to the index type.

	     NB: The type of gimple_switch_index() may be the promoted
	     type, but the case labels retain the original type.  */

	  if (high)
	    {
	      /* This is a case range.  Discard empty ranges.
		 If the bounds or the range are equal, turn this
		 into a simple (one-value) case.  */
	      int cmp = tree_int_cst_compare (high, low);
	      if (cmp < 0)
		remove_element = TRUE;
	      else if (cmp == 0)
		high = NULL_TREE;
	    }

	  if (! high)
	    {
	      /* If the simple case value is unreachable, ignore it.  */
	      if ((TREE_CODE (min_value) == INTEGER_CST
		   && tree_int_cst_compare (low, min_value) < 0)
		  || (TREE_CODE (max_value) == INTEGER_CST
		      && tree_int_cst_compare (low, max_value) > 0))
		remove_element = TRUE;
	      else
		low = fold_convert (index_type, low);
	    }
	  else
	    {
	      /* If the entire case range is unreachable, ignore it.  */
	      if ((TREE_CODE (min_value) == INTEGER_CST
		   && tree_int_cst_compare (high, min_value) < 0)
		  || (TREE_CODE (max_value) == INTEGER_CST
		      && tree_int_cst_compare (low, max_value) > 0))
		remove_element = TRUE;
	      else
		{
		  /* If the lower bound is less than the index type's
		     minimum value, truncate the range bounds.  */
		  if (TREE_CODE (min_value) == INTEGER_CST
		      && tree_int_cst_compare (low, min_value) < 0)
		    low = min_value;
		  low = fold_convert (index_type, low);

		  /* If the upper bound is greater than the index type's
		     maximum value, truncate the range bounds.  */
		  if (TREE_CODE (max_value) == INTEGER_CST
		      && tree_int_cst_compare (high, max_value) > 0)
		    high = max_value;
		  high = fold_convert (index_type, high);

		  /* We may have folded a case range to a one-value case.  */
		  if (tree_int_cst_equal (low, high))
		    high = NULL_TREE;
		}
	    }

	  CASE_LOW (elt) = low;
	  CASE_HIGH (elt) = high;
	}
      else
	{
	  gcc_assert (!default_case);
	  default_case = elt;
	  /* The default case must be passed separately to the
	     gimple_build_switch routine.  But if DEFAULT_CASEP
	     is NULL, we do not remove the default case (it would
	     be completely lost).  */
	  if (default_casep)
	    remove_element = TRUE;
	}

      if (remove_element)
	labels.ordered_remove (i);
      else
	i++;
    }
  len = i;

  if (!labels.is_empty ())
    sort_case_labels (labels);

  if (default_casep && !default_case)
    {
      /* 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 the switch index_type, add the default label pointing
	 to one of the existing labels.  */
      if (len
	  && TYPE_MIN_VALUE (index_type)
	  && TYPE_MAX_VALUE (index_type)
	  && tree_int_cst_equal (CASE_LOW (labels[0]),
				 TYPE_MIN_VALUE (index_type)))
	{
	  tree low, high = CASE_HIGH (labels[len - 1]);
	  if (!high)
	    high = CASE_LOW (labels[len - 1]);
	  if (tree_int_cst_equal (high, TYPE_MAX_VALUE (index_type)))
	    {
	      for (i = 1; i < len; i++)
		{
		  high = CASE_LOW (labels[i]);
		  low = CASE_HIGH (labels[i - 1]);
		  if (!low)
		    low = CASE_LOW (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)
		{
		  tree label = CASE_LABEL (labels[0]);
		  default_case = build_case_label (NULL_TREE, NULL_TREE,
						   label);
		}
	    }
	}
    }

  if (default_casep)
    *default_casep = default_case;
}

/* Gimplify a SWITCH_EXPR, and collect the vector of 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;
  tree index_type = TREE_TYPE (switch_expr);
  if (index_type == NULL_TREE)
    index_type = TREE_TYPE (SWITCH_COND (switch_expr));

  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> labels;
      vec<tree> saved_labels;
      tree default_case = NULL_TREE;
      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.create (8);

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

      preprocess_case_label_vec_for_gimple (labels, index_type,
					    &default_case);

      if (!default_case)
	{
	  gimple new_default;

	  default_case
	    = build_case_label (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 (SWITCH_COND (switch_expr),
					   default_case, labels);
      gimplify_seq_add_stmt (pre_p, gimple_switch);
      gimplify_seq_add_seq (pre_p, switch_body_seq);
      labels.release ();
    }
  else
    gcc_assert (SWITCH_LABELS (switch_expr));

  return GS_ALL_DONE;
}

/* Gimplify the CASE_LABEL_EXPR pointed to by EXPR_P.  */

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.exists ())
      break;

  gimple_label = gimple_build_label (CASE_LABEL (*expr_p));
  ctxp->case_labels.safe_push (*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)
{
  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);

  /* 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.  */