gcc/c-family/c-semantics.c

   1 /* This file contains subroutine used by the C front-end to construct GENERIC.
   2    Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2007, 2008
   3    Free Software Foundation, Inc.
   4    Written by Benjamin Chelf (chelf@codesourcery.com).
   5
   6 This file is part of GCC.
   7
   8 GCC is free software; you can redistribute it and/or modify it under
   9 the terms of the GNU General Public License as published by the Free
  10 Software Foundation; either version 3, or (at your option) any later
  11 version.
  12
  13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  15 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  16 for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with GCC; see the file COPYING3.  If not see
  20 <http://www.gnu.org/licenses/>.  */
  21
  22 #include "config.h"
  23 #include "system.h"
  24 #include "coretypes.h"
  25 #include "tm.h"
  26 #include "tree.h"
  27 #include "function.h"
  28 #include "splay-tree.h"
  29 #include "c-common.h"
  30 #include "toplev.h"
  31 #include "flags.h"
  32 #include "output.h"
  33 #include "tree-iterator.h"
  34
  35 /* Create an empty statement tree rooted at T.  */
  36
  37 tree
  38 push_stmt_list (void)
  39 {
  40   tree t;
  41   t = alloc_stmt_list ();
  42   TREE_CHAIN (t) = cur_stmt_list;
  43   cur_stmt_list = t;
  44   return t;
  45 }
  46
  47 /* Finish the statement tree rooted at T.  */
  48
  49 tree
  50 pop_stmt_list (tree t)
  51 {
  52   tree u = cur_stmt_list, chain;
  53
  54   /* Pop statement lists until we reach the target level.  The extra
  55      nestings will be due to outstanding cleanups.  */
  56   while (1)
  57     {
  58       chain = TREE_CHAIN (u);
  59       TREE_CHAIN (u) = NULL_TREE;
  60       if (chain)
  61         STATEMENT_LIST_HAS_LABEL (chain) |= STATEMENT_LIST_HAS_LABEL (u);
  62       if (t == u)
  63         break;
  64       u = chain;
  65     }
  66   cur_stmt_list = chain;
  67
  68   /* If the statement list is completely empty, just return it.  This is
  69      just as good small as build_empty_stmt, with the advantage that
  70      statement lists are merged when they appended to one another.  So
  71      using the STATEMENT_LIST avoids pathological buildup of EMPTY_STMT_P
  72      statements.  */
  73   if (TREE_SIDE_EFFECTS (t))
  74     {
  75       tree_stmt_iterator i = tsi_start (t);
  76
  77       /* If the statement list contained exactly one statement, then
  78          extract it immediately.  */
  79       if (tsi_one_before_end_p (i))
  80         {
  81           u = tsi_stmt (i);
  82           tsi_delink (&i);
  83           free_stmt_list (t);
  84           t = u;
  85         }
  86     }
  87
  88   return t;
  89 }
  90
  91 /* Build a generic statement based on the given type of node and
  92    arguments. Similar to `build_nt', except that we set
  93    EXPR_LOCATION to LOC. */
  94 /* ??? This should be obsolete with the lineno_stmt productions
  95    in the grammar.  */
  96
  97 tree
  98 build_stmt (location_t loc, enum tree_code code, ...)
  99 {
 100   tree ret;
 101   int length, i;
 102   va_list p;
 103   bool side_effects;
 104
 105   /* This function cannot be used to construct variably-sized nodes.  */
 106   gcc_assert (TREE_CODE_CLASS (code) != tcc_vl_exp);
 107
 108   va_start (p, code);
 109
 110   ret = make_node (code);
 111   TREE_TYPE (ret) = void_type_node;
 112   length = TREE_CODE_LENGTH (code);
 113   SET_EXPR_LOCATION (ret, loc);
 114
 115   /* TREE_SIDE_EFFECTS will already be set for statements with
 116      implicit side effects.  Here we make sure it is set for other
 117      expressions by checking whether the parameters have side
 118      effects.  */
 119
 120   side_effects = false;
 121   for (i = 0; i < length; i++)
 122     {
 123       tree t = va_arg (p, tree);
 124       if (t && !TYPE_P (t))
 125         side_effects |= TREE_SIDE_EFFECTS (t);
 126       TREE_OPERAND (ret, i) = t;
 127     }
 128
 129   TREE_SIDE_EFFECTS (ret) |= side_effects;
 130
 131   va_end (p);
 132   return ret;
 133 }
 134
 135 /* Create a CASE_LABEL_EXPR tree node and return it.  */
 136
 137 tree
 138 build_case_label (location_t loc,
 139                   tree low_value, tree high_value, tree label_decl)
 140 {
 141   return build_stmt (loc, CASE_LABEL_EXPR, low_value, high_value, label_decl);
 142 }