gcc/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 /* In order for the format checking to accept the C frontend
  31    diagnostic framework extensions, you must define this token before
  32    including toplev.h.  */
  33 #define GCC_DIAG_STYLE __gcc_cdiag__
  34 #include "toplev.h"
  35 #include "flags.h"
  36 #include "output.h"
  37 #include "tree-iterator.h"
  38
  39 /* Create an empty statement tree rooted at T.  */
  40
  41 tree
  42 push_stmt_list (void)
  43 {
  44   tree t;
  45   t = alloc_stmt_list ();
  46   TREE_CHAIN (t) = cur_stmt_list;
  47   cur_stmt_list = t;
  48   return t;
  49 }
  50
  51 /* Finish the statement tree rooted at T.  */
  52
  53 tree
  54 pop_stmt_list (tree t)
  55 {
  56   tree u = cur_stmt_list, chain;
  57
  58   /* Pop statement lists until we reach the target level.  The extra
  59      nestings will be due to outstanding cleanups.  */
  60   while (1)
  61     {
  62       chain = TREE_CHAIN (u);
  63       TREE_CHAIN (u) = NULL_TREE;
  64       if (chain)
  65         STATEMENT_LIST_HAS_LABEL (chain) |= STATEMENT_LIST_HAS_LABEL (u);
  66       if (t == u)
  67         break;
  68       u = chain;
  69     }
  70   cur_stmt_list = chain;
  71
  72   /* If the statement list is completely empty, just return it.  This is
  73      just as good small as build_empty_stmt, with the advantage that
  74      statement lists are merged when they appended to one another.  So
  75      using the STATEMENT_LIST avoids pathological buildup of EMPTY_STMT_P
  76      statements.  */
  77   if (TREE_SIDE_EFFECTS (t))
  78     {
  79       tree_stmt_iterator i = tsi_start (t);
  80
  81       /* If the statement list contained exactly one statement, then
  82          extract it immediately.  */
  83       if (tsi_one_before_end_p (i))
  84         {
  85           u = tsi_stmt (i);
  86           tsi_delink (&i);
  87           free_stmt_list (t);
  88           t = u;
  89         }
  90     }
  91
  92   return t;
  93 }
  94
  95 /* Build a generic statement based on the given type of node and
  96    arguments. Similar to `build_nt', except that we set
  97    EXPR_LOCATION to LOC. */
  98 /* ??? This should be obsolete with the lineno_stmt productions
  99    in the grammar.  */
 100
 101 tree
 102 build_stmt (location_t loc, enum tree_code code, ...)
 103 {
 104   tree ret;
 105   int length, i;
 106   va_list p;
 107   bool side_effects;
 108
 109   /* This function cannot be used to construct variably-sized nodes.  */
 110   gcc_assert (TREE_CODE_CLASS (code) != tcc_vl_exp);
 111
 112   va_start (p, code);
 113
 114   ret = make_node (code);
 115   TREE_TYPE (ret) = void_type_node;
 116   length = TREE_CODE_LENGTH (code);
 117   SET_EXPR_LOCATION (ret, loc);
 118
 119   /* TREE_SIDE_EFFECTS will already be set for statements with
 120      implicit side effects.  Here we make sure it is set for other
 121      expressions by checking whether the parameters have side
 122      effects.  */
 123
 124   side_effects = false;
 125   for (i = 0; i < length; i++)
 126     {
 127       tree t = va_arg (p, tree);
 128       if (t && !TYPE_P (t))
 129         side_effects |= TREE_SIDE_EFFECTS (t);
 130       TREE_OPERAND (ret, i) = t;
 131     }
 132
 133   TREE_SIDE_EFFECTS (ret) |= side_effects;
 134
 135   va_end (p);
 136   return ret;
 137 }
 138
 139 /* Create a CASE_LABEL_EXPR tree node and return it.  */
 140
 141 tree
 142 build_case_label (location_t loc,
 143                   tree low_value, tree high_value, tree label_decl)
 144 {
 145   return build_stmt (loc, CASE_LABEL_EXPR, low_value, high_value, label_decl);
 146 }