gcc/lists.c

   1 /* List management for the GNU C-Compiler expander.
   2    Copyright (C) 1987, 88, 92-97, 1998, 1999 Free Software Foundation, Inc.
   3
   4 This file is part of GNU CC.
   5
   6 GNU CC is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU CC is distributed in the hope that it will be useful,
  12 but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 GNU General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU CC; see the file COPYING.  If not, write to
  18 the Free Software Foundation, 59 Temple Place - Suite 330,
  19 Boston, MA 02111-1307, USA.  */
  20
  21 #include "config.h"
  22 #include "system.h"
  23 #include "toplev.h"
  24 #include "rtl.h"
  25 #include "ggc.h"
  26
  27 static void free_list PARAMS ((rtx *, rtx *));
  28 static void zap_lists PARAMS ((void *));
  29
  30 /* Functions for maintaining cache-able lists of EXPR_LIST and INSN_LISTs.  */
  31
  32 /* An INSN_LIST containing all INSN_LISTs allocated but currently unused.  */
  33 static rtx unused_insn_list;
  34
  35 /* An EXPR_LIST containing all EXPR_LISTs allocated but currently unused.  */
  36 static rtx unused_expr_list;
  37
  38
  39 /* This function will free an entire list of either EXPR_LIST or INSN_LIST
  40    nodes. This is to be used only only lists that consist exclusively of
  41    nodes of one type only.  This is only called by free_EXPR_LIST_list
  42    and free_INSN_LIST_list.  */
  43 static void
  44 free_list (listp, unused_listp)
  45      rtx *listp, *unused_listp;
  46 {
  47   register rtx link, prev_link;
  48
  49   prev_link = *listp;
  50   link = XEXP (prev_link, 1);
  51
  52   while (link)
  53     {
  54       prev_link = link;
  55       link = XEXP (link, 1);
  56     }
  57
  58   XEXP (prev_link, 1) = *unused_listp;
  59   *unused_listp = *listp;
  60   *listp = 0;
  61 }
  62
  63 /* This call is used in place of a gen_rtx_INSN_LIST. If there is a cached
  64    node available, we'll use it, otherwise a call to gen_rtx_INSN_LIST
  65    is made.  */
  66 rtx
  67 alloc_INSN_LIST (val, next)
  68      rtx val, next;
  69 {
  70   rtx r;
  71
  72   if (unused_insn_list)
  73     {
  74       r = unused_insn_list;
  75       unused_insn_list = XEXP (r, 1);
  76       XEXP (r, 0) = val;
  77       XEXP (r, 1) = next;
  78       PUT_REG_NOTE_KIND (r, VOIDmode);
  79     }
  80   else
  81     r = gen_rtx_INSN_LIST (VOIDmode, val, next);
  82
  83   return r;
  84 }
  85
  86 /* This call is used in place of a gen_rtx_EXPR_LIST. If there is a cached
  87    node available, we'll use it, otherwise a call to gen_rtx_EXPR_LIST
  88    is made.  */
  89 rtx
  90 alloc_EXPR_LIST (kind, val, next)
  91      int kind;
  92      rtx val, next;
  93 {
  94   rtx r;
  95
  96   if (unused_expr_list)
  97     {
  98       r = unused_expr_list;
  99       unused_expr_list = XEXP (r, 1);
 100       XEXP (r, 0) = val;
 101       XEXP (r, 1) = next;
 102       PUT_REG_NOTE_KIND (r, kind);
 103     }
 104   else
 105     r = gen_rtx_EXPR_LIST (kind, val, next);
 106
 107   return r;
 108 }
 109
 110 /* This function will initialize the EXPR_LIST and INSN_LIST caches.  */
 111
 112 static void
 113 zap_lists (dummy)
 114      void *dummy ATTRIBUTE_UNUSED;
 115 {
 116   unused_expr_list = NULL;
 117   unused_insn_list = NULL;
 118 }
 119
 120 void
 121 init_EXPR_INSN_LIST_cache ()
 122 {
 123   if (ggc_p)
 124     {
 125       static int initialized;
 126       if (!initialized)
 127         {
 128           initialized = 1;
 129           ggc_add_root (&unused_expr_list, 1, 1, zap_lists);
 130         }
 131
 132       /* No need to squish the lists across functions with GC enabled.  */
 133     }
 134   else
 135     {
 136       unused_expr_list = NULL;
 137       unused_insn_list = NULL;
 138     }
 139 }
 140
 141 /* This function will free up an entire list of EXPR_LIST nodes.  */
 142 void
 143 free_EXPR_LIST_list (listp)
 144      rtx *listp;
 145 {
 146   if (*listp == 0)
 147     return;
 148   free_list (listp, &unused_expr_list);
 149 }
 150
 151 /* This function will free up an entire list of INSN_LIST nodes.  */
 152 void
 153 free_INSN_LIST_list (listp)
 154      rtx *listp;
 155 {
 156   if (*listp == 0)
 157     return;
 158   free_list (listp, &unused_insn_list);
 159 }
 160
 161 /* This function will free up an individual EXPR_LIST node.  */
 162 void
 163 free_EXPR_LIST_node (ptr)
 164      rtx ptr;
 165 {
 166   XEXP (ptr, 1) = unused_expr_list;
 167   unused_expr_list = ptr;
 168 }
 169
 170 /* This function will free up an individual INSN_LIST node.  */
 171 void
 172 free_INSN_LIST_node (ptr)
 173      rtx ptr;
 174 {
 175   XEXP (ptr, 1) = unused_insn_list;
 176   unused_insn_list = ptr;
 177 }