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
5This file is part of GCC.
6
7GCC is free software; you can redistribute it and/or modify it under
8the terms of the GNU General Public License as published by the Free
9Software Foundation; either version 2, or (at your option) any later
10version.
11
12GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13WARRANTY; without even the implied warranty of MERCHANTABILITY or
14FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
15for more details.
16
17You should have received a copy of the GNU General Public License
18along with GCC; see the file COPYING.  If not, write to the Free
19Software Foundation, 59 Temple Place - Suite 330, Boston, MA
2002111-1307, USA.  */
21
22#include "config.h"
23#include "system.h"
24#include "toplev.h"
25#include "rtl.h"
26#include "ggc.h"
27
28static void free_list PARAMS ((rtx *, rtx *));
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.  */
33static GTY ((deletable (""))) rtx unused_insn_list;
34
35/* An EXPR_LIST containing all EXPR_LISTs allocated but currently unused.  */
36static GTY ((deletable (""))) 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 on 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.  */
43static void
44free_list (listp, unused_listp)
45     rtx *listp, *unused_listp;
46{
47  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.  */
66rtx
67alloc_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.  */
89rtx
90alloc_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 free up an entire list of EXPR_LIST nodes.  */
111void
112free_EXPR_LIST_list (listp)
113     rtx *listp;
114{
115  if (*listp == 0)
116    return;
117  free_list (listp, &unused_expr_list);
118}
119
120/* This function will free up an entire list of INSN_LIST nodes.  */
121void
122free_INSN_LIST_list (listp)
123     rtx *listp;
124{
125  if (*listp == 0)
126    return;
127  free_list (listp, &unused_insn_list);
128}
129
130/* This function will free up an individual EXPR_LIST node.  */
131void
132free_EXPR_LIST_node (ptr)
133     rtx ptr;
134{
135  XEXP (ptr, 1) = unused_expr_list;
136  unused_expr_list = ptr;
137}
138
139/* This function will free up an individual INSN_LIST node.  */
140void
141free_INSN_LIST_node (ptr)
142     rtx ptr;
143{
144  XEXP (ptr, 1) = unused_insn_list;
145  unused_insn_list = ptr;
146}
147
148#include "gt-lists.h"
149