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 "varray.h"
  30 #include "c-common.h"
  31 #include "except.h"
  32 /* In order for the format checking to accept the C frontend
  33    diagnostic framework extensions, you must define this token before
  34    including toplev.h.  */
  35 #define GCC_DIAG_STYLE __gcc_cdiag__
  36 #include "toplev.h"
  37 #include "flags.h"
  38 #include "ggc.h"
  39 #include "rtl.h"
  40 #include "output.h"
  41 #include "timevar.h"
  42 #include "predict.h"
  43 #include "tree-inline.h"
  44 #include "gimple.h"
  45 #include "tree-iterator.h"
  46 #include "langhooks.h"
  47
  48 /* Create an empty statement tree rooted at T.  */
  49
  50 tree
  51 push_stmt_list (void)
  52 {
  53   tree t;
  54   t = alloc_stmt_list ();
  55   TREE_CHAIN (t) = cur_stmt_list;
  56   cur_stmt_list = t;
  57   return t;
  58 }
  59
  60 /* Finish the statement tree rooted at T.  */
  61
  62 tree
  63 pop_stmt_list (tree t)
  64 {
  65   tree u = cur_stmt_list, chain;
  66
  67   /* Pop statement lists until we reach the target level.  The extra
  68      nestings will be due to outstanding cleanups.  */
  69   while (1)
  70     {
  71       chain = TREE_CHAIN (u);
  72       TREE_CHAIN (u) = NULL_TREE;
  73       if (t == u)
  74         break;
  75       u = chain;
  76     }
  77   cur_stmt_list = chain;
  78
  79   /* If the statement list is completely empty, just return it.  This is
  80      just as good small as build_empty_stmt, with the advantage that
  81      statement lists are merged when they appended to one another.  So
  82      using the STATEMENT_LIST avoids pathological buildup of EMPTY_STMT_P
  83      statements.  */
  84   if (TREE_SIDE_EFFECTS (t))
  85     {
  86       tree_stmt_iterator i = tsi_start (t);
  87
  88       /* If the statement list contained exactly one statement, then
  89          extract it immediately.  */
  90       if (tsi_one_before_end_p (i))
  91         {
  92           u = tsi_stmt (i);
  93           tsi_delink (&i);
  94           free_stmt_list (t);
  95           t = u;
  96         }
  97     }
  98
  99   return t;
 100 }
 101
 102 /* Build a generic statement based on the given type of node and
 103    arguments. Similar to `build_nt', except that we set
 104    EXPR_LOCATION to be the current source location.  */
 105 /* ??? This should be obsolete with the lineno_stmt productions
 106    in the grammar.  */
 107
 108 tree
 109 build_stmt (enum tree_code code, ...)
 110 {
 111   tree ret;
 112   int length, i;
 113   va_list p;
 114   bool side_effects;
 115
 116   /* This function cannot be used to construct variably-sized nodes.  */
 117   gcc_assert (TREE_CODE_CLASS (code) != tcc_vl_exp);
 118
 119   va_start (p, code);
 120
 121   ret = make_node (code);
 122   TREE_TYPE (ret) = void_type_node;
 123   length = TREE_CODE_LENGTH (code);
 124   SET_EXPR_LOCATION (ret, input_location);
 125
 126   /* TREE_SIDE_EFFECTS will already be set for statements with
 127      implicit side effects.  Here we make sure it is set for other
 128      expressions by checking whether the parameters have side
 129      effects.  */
 130
 131   side_effects = false;
 132   for (i = 0; i < length; i++)
 133     {
 134       tree t = va_arg (p, tree);
 135       if (t && !TYPE_P (t))
 136         side_effects |= TREE_SIDE_EFFECTS (t);
 137       TREE_OPERAND (ret, i) = t;
 138     }
 139
 140   TREE_SIDE_EFFECTS (ret) |= side_effects;
 141
 142   va_end (p);
 143   return ret;
 144 }
 145
 146 /* Create a CASE_LABEL_EXPR tree node and return it.  */
 147
 148 tree
 149 build_case_label (tree low_value, tree high_value, tree label_decl)
 150 {
 151   return build_stmt (CASE_LABEL_EXPR, low_value, high_value, label_decl);
 152 }