gimplify.c

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

  save_call =
      build_function_call_expr (implicit_built_in_decls[BUILT_IN_STACK_SAVE],
				NULL_TREE);
  tmp_var = create_tmp_var (ptr_type_node, "saved_stack");

  *save = build2 (MODIFY_EXPR, ptr_type_node, tmp_var, save_call);
  *restore =
    build_function_call_expr (implicit_built_in_decls[BUILT_IN_STACK_RESTORE],
			      tree_cons (NULL_TREE, tmp_var, NULL_TREE));
}

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

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

  temp = voidify_wrapper_expr (bind_expr, temp);

  /* 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;
	}

      /* 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_THIS_VOLATILE (t)
	  && (TREE_CODE (t) == VAR_DECL && !DECL_HARD_REGISTER (t))
	  && !needs_to_live_in_memory (t))
	DECL_COMPLEX_GIMPLE_REG_P (t) = 1;
    }

  gimple_push_bind_expr (bind_expr);
  gimplify_ctxp->save_stack = false;

  gimplify_to_stmt_list (&BIND_EXPR_BODY (bind_expr));

  if (gimplify_ctxp->save_stack)
    {
      tree stack_save, 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);

      t = build2 (TRY_FINALLY_EXPR, void_type_node,
		  BIND_EXPR_BODY (bind_expr), NULL_TREE);
      append_to_statement_list (stack_restore, &TREE_OPERAND (t, 1));

      BIND_EXPR_BODY (bind_expr) = NULL_TREE;
      append_to_statement_list (stack_save, &BIND_EXPR_BODY (bind_expr));
      append_to_statement_list (t, &BIND_EXPR_BODY (bind_expr));
    }

  gimplify_ctxp->save_stack = old_save_stack;
  gimple_pop_bind_expr ();

  if (temp)
    {
      *expr_p = temp;
      append_to_statement_list (bind_expr, pre_p);
      return GS_OK;
    }
  else
    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 list where side effects that must happen before
   STMT should be stored.  */

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

  if (!ret_expr || TREE_CODE (ret_expr) == RESULT_DECL
      || ret_expr == error_mark_node)
    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);
      if (TREE_CODE (result_decl) == INDIRECT_REF)
	/* See through a return by reference.  */
	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
      || aggregate_value_p (result_decl, TREE_TYPE (current_function_decl)))
    result = result_decl;
  else if (gimplify_ctxp->return_temp)
    result = gimplify_ctxp->return_temp;
  else
    {
      result = create_tmp_var (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);

  /* If we didn't use a temporary, then the result is just the result_decl.
     Otherwise we need a simple copy.  This should already be gimple.  */
  if (result == result_decl)
    ret_expr = result;
  else
    ret_expr = build2 (MODIFY_EXPR, TREE_TYPE (result), result_decl, result);
  TREE_OPERAND (stmt, 0) = ret_expr;

  return GS_ALL_DONE;
}

/* 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)
{
  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), stmt_p);

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

      if (!TREE_CONSTANT (DECL_SIZE (decl)))
	{
	  /* 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, args, addr, ptr_type;

	  gimplify_one_sizepos (&DECL_SIZE (decl), stmt_p);
	  gimplify_one_sizepos (&DECL_SIZE_UNIT (decl), stmt_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;

	  args = tree_cons (NULL, DECL_SIZE_UNIT (decl), NULL);
	  t = built_in_decls[BUILT_IN_ALLOCA];
	  t = build_function_call_expr (t, args);
	  t = fold_convert (ptr_type, t);
	  t = build2 (MODIFY_EXPR, void_type_node, addr, t);

	  gimplify_and_add (t, stmt_p);

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

      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, stmt_p);
	    }
	  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, tree *pre_p)
{
  tree saved_label = gimplify_ctxp->exit_label;
  tree start_label = build1 (LABEL_EXPR, void_type_node, NULL_TREE);
  tree jump_stmt = build_and_jump (&LABEL_EXPR_LABEL (start_label));

  append_to_statement_list (start_label, pre_p);

  gimplify_ctxp->exit_label = NULL_TREE;

  gimplify_and_add (LOOP_EXPR_BODY (*expr_p), pre_p);

  if (gimplify_ctxp->exit_label)
    {
      append_to_statement_list (jump_stmt, pre_p);
      *expr_p = build1 (LABEL_EXPR, void_type_node, gimplify_ctxp->exit_label);
    }
  else
    *expr_p = jump_stmt;

  gimplify_ctxp->exit_label = saved_label;

  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)
{
  tree case1 = *(tree *)p1;
  tree case2 = *(tree *)p2;

  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 (tree label_vec)
{
  size_t len = TREE_VEC_LENGTH (label_vec);
  tree default_case = TREE_VEC_ELT (label_vec, len - 1);

  if (CASE_LOW (default_case))
    {
      size_t i;

      /* The last label in the vector should be the default case
         but it is not.  */
      for (i = 0; i < len; ++i)
	{
	  tree t = TREE_VEC_ELT (label_vec, i);
	  if (!CASE_LOW (t))
	    {
	      default_case = t;
	      TREE_VEC_ELT (label_vec, i) = TREE_VEC_ELT (label_vec, len - 1);
	      TREE_VEC_ELT (label_vec, len - 1) = default_case;
	      break;
	    }
	}
    }

  qsort (&TREE_VEC_ELT (label_vec, 0), len - 1, 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, tree *pre_p)
{
  tree switch_expr = *expr_p;
  enum gimplify_status ret;

  ret = gimplify_expr (&SWITCH_COND (switch_expr), pre_p, NULL,
		       is_gimple_val, fb_rvalue);

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

      /* 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));

      saved_labels = gimplify_ctxp->case_labels;
      gimplify_ctxp->case_labels = VEC_alloc (tree, heap, 8);

      gimplify_to_stmt_list (&SWITCH_BODY (switch_expr));

      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 && 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;

      label_vec = make_tree_vec (len + 1);
      SWITCH_LABELS (*expr_p) = label_vec;
      append_to_statement_list (switch_expr, pre_p);

      if (! default_case)
	{
	  /* If the switch has no default label, add one, so that we jump
	     around the switch body.  */
	  default_case = build3 (CASE_LABEL_EXPR, void_type_node, NULL_TREE,
				 NULL_TREE, create_artificial_label ());
	  append_to_statement_list (SWITCH_BODY (switch_expr), pre_p);
	  *expr_p = build1 (LABEL_EXPR, void_type_node,
			    CASE_LABEL (default_case));
	}
      else
	*expr_p = SWITCH_BODY (switch_expr);

      for (i = 0; i < len; ++i)
	TREE_VEC_ELT (label_vec, i) = VEC_index (tree, labels, i);
      TREE_VEC_ELT (label_vec, len) = default_case;

      VEC_free (tree, heap, labels);

      sort_case_labels (label_vec);

      SWITCH_BODY (switch_expr) = NULL;
    }
  else
    gcc_assert (SWITCH_LABELS (switch_expr));

  return ret;
}

static enum gimplify_status
gimplify_case_label_expr (tree *expr_p)
{
  tree expr = *expr_p;
  struct gimplify_ctx *ctxp;

  /* 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;

  VEC_safe_push (tree, heap, ctxp->case_labels, expr);
  *expr_p = build1 (LABEL_EXPR, void_type_node, CASE_LABEL (expr));
  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 ();
      *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));

  if (TREE_TYPE (expr) != type)
    {
      tree old_type = TREE_TYPE (expr);

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

      /* And wrap the whole thing inside a NOP_EXPR.  */
      expr = build1 (NOP_EXPR, old_type, expr);

      *expr_p = expr;
    }
}

/* 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.  */

static void
canonicalize_addr_expr (tree *expr_p)
{
  tree expr = *expr_p;
  tree ctype = TREE_TYPE (expr);
  tree addr_expr = TREE_OPERAND (expr, 0);
  tree atype = TREE_TYPE (addr_expr);
  tree dctype, datype, ddatype, otype, obj_expr;

  /* Both cast and addr_expr types should be pointers.  */
  if (!POINTER_TYPE_P (ctype) || !POINTER_TYPE_P (atype))
    return;

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

  /* Both cast and addr_expr types should address the same object type.  */
  dctype = TREE_TYPE (ctype);
  ddatype = TREE_TYPE (datype);
  if (!lang_hooks.types_compatible_p (ddatype, dctype))
    return;

  /* The addr_expr and the object type should match.  */
  obj_expr = TREE_OPERAND (addr_expr, 0);
  otype = TREE_TYPE (obj_expr);
  if (!lang_hooks.types_compatible_p (otype, datype))
    return;

  /* The lower bound and element sizes must be constant.  */
  if (!TYPE_SIZE_UNIT (dctype)
      || TREE_CODE (TYPE_SIZE_UNIT (dctype)) != 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, dctype, obj_expr,
		    TYPE_MIN_VALUE (TYPE_DOMAIN (datype)),
		    TYPE_MIN_VALUE (TYPE_DOMAIN (datype)),
		    size_binop (EXACT_DIV_EXPR, TYPE_SIZE_UNIT (dctype),
				size_int (TYPE_ALIGN_UNIT (dctype))));
  *expr_p = build1 (ADDR_EXPR, ctype, *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)
{
  gcc_assert (TREE_CODE (*expr_p) == NOP_EXPR
	      || TREE_CODE (*expr_p) == CONVERT_EXPR);
  
  /* 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 (TREE_CODE (*expr_p) == NOP_EXPR || TREE_CODE (*expr_p) == CONVERT_EXPR)
    {
      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);
    }

  return GS_OK;
}

/* 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))
    {
      *expr_p = unshare_expr (DECL_VALUE_EXPR (decl));
      return GS_OK;
    }

  return GS_ALL_DONE;
}


/* Gimplify the COMPONENT_REF, ARRAY_REF, REALPART_EXPR or IMAGPART_EXPR
   node pointed to by 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 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.  */

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

  /* 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 (*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))
	    {
	      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_formal_tmp_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 (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_formal_tmp_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 (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_formal_tmp_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.
	     Temporary fix for gcc.c-torture/execute/20040313-1.c.
	     Gimplify non-constant array indices into a temporary
	     variable.
	     FIXME - The real fix is to gimplify post-modify
	     expressions into a minimal gimple lvalue.  However, that
	     exposes bugs in alias analysis.  The alias analyzer does
	     not handle &PTR->FIELD very well.  Will fix after the
	     branch is merged into mainline (dnovillo 2004-05-03).  */
	  if (!is_gimple_min_invariant (TREE_OPERAND (t, 1)))
	    {
	      tret = gimplify_expr (&TREE_OPERAND (t, 1), pre_p, post_p,
				    is_gimple_formal_tmp_reg, 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);
    }

  tret = gimplify_expr (p, pre_p, post_p, is_gimple_min_lval, fallback);
  ret = MIN (ret, tret);

  /* 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, tree *pre_p, tree *post_p,
			bool want_value)
{
  enum tree_code code;
  tree lhs, lvalue, rhs, t1;
  bool postfix;
  enum tree_code arith_code;
  enum gimplify_status ret;

  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;

  /* 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.  */
  if (postfix)
    {
      ret = gimplify_expr (&lhs, pre_p, post_p, is_gimple_val, fb_rvalue);
      if (ret == GS_ERROR)
	return ret;
    }

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

  if (postfix)
    {
      gimplify_and_add (t1, post_p);
      *expr_p = lhs;
      return GS_ALL_DONE;
    }
  else
    {
      *expr_p = 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);
}

/* Subroutine of gimplify_call_expr:  Gimplify a single argument.  */

static enum gimplify_status
gimplify_arg (tree *expr_p, tree *pre_p)
{
  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 (*expr_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 (expr_p);

  /* 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 (expr_p, pre_p, NULL, test, fb);
}

/* Gimplify the CALL_EXPR node pointed to by EXPR_P.  PRE_P points to the
   list where side effects that must happen before *EXPR_P should be stored.
   WANT_VALUE is true if the result of the call is desired.  */

static enum gimplify_status
gimplify_call_expr (tree *expr_p, tree *pre_p, bool want_value)
{
  tree decl;
  tree arglist;
  enum gimplify_status ret;

  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