gcc/lists.c

   1 /* List management for the GNU C-Compiler expander.
   2    Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
   3    1999 Free Software Foundation, Inc.
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify it under
   8 the terms of the GNU General Public License as published by the Free
   9 Software Foundation; either version 2, or (at your option) any later
  10 version.
  11
  12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15 for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GCC; see the file COPYING.  If not, write to the Free
  19 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
  20 02111-1307, USA.  */
  21
  22 #include "config.h"
  23 #include "system.h"
  24 #include "toplev.h"
  25 #include "rtl.h"
  26 #include "ggc.h"
  27
  28 static void free_list PARAMS ((rtx *, rtx *));
  29 static void zap_lists PARAMS ((void *));
  30
  31 /* Functions for maintaining cache-able lists of EXPR_LIST and INSN_LISTs.  */
  32
  33 /* An INSN_LIST containing all INSN_LISTs allocated but currently unused.  */
  34 static rtx unused_insn_list;
  35
  36 /* An EXPR_LIST containing all EXPR_LISTs allocated but currently unused.  */
  37 static rtx unused_expr_list;
  38
  39
  40 /* This function will free an entire list of either EXPR_LIST or INSN_LIST
  41    nodes. This is to be used only only lists that consist exclusively of
  42    nodes of one type only.  This is only called by free_EXPR_LIST_list
  43    and free_INSN_LIST_list.  */
  44 static void
  45 free_list (listp, unused_listp)
  46      rtx *listp, *unused_listp;
  47 {
  48   rtx link, prev_link;
  49
  50   prev_link = *listp;
  51   link = XEXP (prev_link, 1);
  52
  53   while (link)
  54     {
  55       prev_link = link;
  56       link = XEXP (link, 1);
  57     }
  58
  59   XEXP (prev_link, 1) = *unused_listp;
  60   *unused_listp = *listp;
  61   *listp = 0;
  62 }
  63
  64 /* This call is used in place of a gen_rtx_INSN_LIST. If there is a cached
  65    node available, we'll use it, otherwise a call to gen_rtx_INSN_LIST
  66    is made.  */
  67 rtx
  68 alloc_INSN_LIST (val, next)
  69      rtx val, next;
  70 {
  71   rtx r;
  72
  73   if (unused_insn_list)
  74     {
  75       r = unused_insn_list;
  76       unused_insn_list = XEXP (r, 1);
  77       XEXP (r, 0) = val;
  78       XEXP (r, 1) = next;
  79       PUT_REG_NOTE_KIND (r, VOIDmode);
  80     }
  81   else
  82     r = gen_rtx_INSN_LIST (VOIDmode, val, next);
  83
  84   return r;
  85 }
  86
  87 /* This call is used in place of a gen_rtx_EXPR_LIST. If there is a cached
  88    node available, we'll use it, otherwise a call to gen_rtx_EXPR_LIST
  89    is made.  */
  90 rtx
  91 alloc_EXPR_LIST (kind, val, next)
  92      int kind;
  93      rtx val, next;
  94 {
  95   rtx r;
  96
  97   if (unused_expr_list)
  98     {
  99       r = unused_expr_list;
 100       unused_expr_list = XEXP (r, 1);
 101       XEXP (r, 0) = val;
 102       XEXP (r, 1) = next;
 103       PUT_REG_NOTE_KIND (r, kind);
 104     }
 105   else
 106     r = gen_rtx_EXPR_LIST (kind, val, next);
 107
 108   return r;
 109 }
 110
 111 /* This function will initialize the EXPR_LIST and INSN_LIST caches.  */
 112
 113 static void
 114 zap_lists (dummy)
 115      void *dummy ATTRIBUTE_UNUSED;
 116 {
 117   unused_expr_list = NULL;
 118   unused_insn_list = NULL;
 119 }
 120
 121 void
 122 init_EXPR_INSN_LIST_cache ()
 123 {
 124   ggc_add_root (&unused_expr_list, 1, 1, zap_lists);
 125 }
 126
 127 /* This function will free up an entire list of EXPR_LIST nodes.  */
 128 void
 129 free_EXPR_LIST_list (listp)
 130      rtx *listp;
 131 {
 132   if (*listp == 0)
 133     return;
 134   free_list (listp, &unused_expr_list);
 135 }
 136
 137 /* This function will free up an entire list of INSN_LIST nodes.  */
 138 void
 139 free_INSN_LIST_list (listp)
 140      rtx *listp;
 141 {
 142   if (*listp == 0)
 143     return;
 144   free_list (listp, &unused_insn_list);
 145 }
 146
 147 /* This function will free up an individual EXPR_LIST node.  */
 148 void
 149 free_EXPR_LIST_node (ptr)
 150      rtx ptr;
 151 {
 152   XEXP (ptr, 1) = unused_expr_list;
 153   unused_expr_list = ptr;
 154 }
 155
 156 /* This function will free up an individual INSN_LIST node.  */
 157 void
 158 free_INSN_LIST_node (ptr)
 159      rtx ptr;
 160 {
 161   XEXP (ptr, 1) = unused_insn_list;
 162   unused_insn_list = ptr;
 163 }