gimplify.c

  pred = shortcut_cond_r (pred, true_label_p, false_label_p,
			  EXPR_LOC_OR_HERE (expr));

  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);
		}
	    }
	}
    }

  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));

      /* These expressions always produce boolean results.  */
      if (TREE_CODE (type) != BOOLEAN_TYPE)
	TREE_TYPE (expr) = boolean_type_node;
      return expr;

    case ANNOTATE_EXPR:
      if ((enum annot_expr_kind) TREE_INT_CST_LOW (TREE_OPERAND (expr, 1))
	  == annot_expr_ivdep_kind)
	{
	  TREE_OPERAND (expr, 0) = gimple_boolify (TREE_OPERAND (expr, 0));
	  if (TREE_CODE (type) != BOOLEAN_TYPE)
	    TREE_TYPE (expr) = boolean_type_node;
	  return expr;
	}
      /* FALLTHRU */

    default:
      if (COMPARISON_CLASS_P (expr))
	{
	  /* There expressions always prduce boolean results.  */
	  if (TREE_CODE (type) != BOOLEAN_TYPE)
	    TREE_TYPE (expr) = boolean_type_node;
	  return expr;
	}
      /* Other expressions that get here must have boolean values, but
	 might need to be converted to the appropriate mode.  */
      if (TREE_CODE (type) == BOOLEAN_TYPE)
	return expr;
      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);
}

/* Return 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_simple_mem_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;
    }

  /* Remove any COMPOUND_EXPR so the following cases will be caught.  */
  STRIP_TYPE_NOPS (TREE_OPERAND (expr, 0));
  if (TREE_CODE (TREE_OPERAND (expr, 0)) == COMPOUND_EXPR)
    gimplify_compound_expr (&TREE_OPERAND (expr, 0), pre_p, true);

  /* 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 = builtin_decl_implicit (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 = build_simple_mem_ref (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_safe_is_empty (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 = builtin_decl_implicit (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.  Return 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 ((INDIRECT_REF_P (t)
       || TREE_CODE (t) == MEM_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.
     ??? Ugh - this is completely broken.  In fact this whole analysis
     doesn't look conservative.  */
  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, va_gc> *v = CONSTRUCTOR_ELTS (*expr_p);

      FOR_EACH_VEC_SAFE_ELT (v, ix, ce)
	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, va_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, va_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);
	}
    }
}

/* Return 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,
				bool (*gimple_test_f) (tree),
				fallback_t fallback)
{
  tree decl_s = COMPOUND_LITERAL_EXPR_DECL_EXPR (*expr_p);
  tree decl = DECL_EXPR_DECL (decl_s);
  tree init = DECL_INITIAL (decl);
  /* 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;
  /* Otherwise, if we don't need an lvalue and have a literal directly
     substitute it.  Check if it matches the gimple predicate, as
     otherwise we'd generate a new temporary, and we can as well just
     use the decl we already have.  */
  else if (!TREE_ADDRESSABLE (decl)
	   && init
	   && (fallback & fb_lvalue) == 0
	   && gimple_test_f (init))
    {
      *expr_p = init;
      return GS_OK;
    }

  /* 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;

  /* If the decl is not addressable, then it is being used in some
     expression or on the right hand side of a statement, and it can
     be put into a readonly data section.  */
  if (!TREE_ADDRESSABLE (decl) && (fallback & fb_lvalue) == 0)
    TREE_READONLY (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, va_gc> *elts = CONSTRUCTOR_ELTS (ctor);
  unsigned int idx, num = vec_safe_length (elts);

  for (idx = 0; idx < num; idx++)
    {
      tree value = (*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
	      && TREE_CODE (init) == CONSTRUCTOR)
	    newval = optimize_compound_literals_in_ctor (init);
	}
      if (newval == value)
	continue;

      if (ctor == orig_ctor)
	{
	  ctor = copy_node (orig_ctor);
	  CONSTRUCTOR_ELTS (ctor) = vec_safe_copy (elts);
	  elts = CONSTRUCTOR_ELTS (ctor);
	}
      (*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, va_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_ctor_elements, num_nonzero_elements;
	bool cleared, complete_p, 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_safe_is_empty (elts))