1/* List management for the GCC expander.
2   Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
3   1999, 2003, 2004 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, 51 Franklin Street, Fifth Floor, Boston, MA
2002110-1301, USA.  */
21
22#include "config.h"
23#include "system.h"
24#include "coretypes.h"
25#include "tm.h"
26#include "toplev.h"
27#include "rtl.h"
28#include "ggc.h"
29
30static void free_list (rtx *, rtx *);
31
32/* Functions for maintaining cache-able lists of EXPR_LIST and INSN_LISTs.  */
33
34/* An INSN_LIST containing all INSN_LISTs allocated but currently unused.  */
35static GTY ((deletable)) rtx unused_insn_list;
36
37/* An EXPR_LIST containing all EXPR_LISTs allocated but currently unused.  */
38static GTY ((deletable)) rtx unused_expr_list;
39
40
41/* This function will free an entire list of either EXPR_LIST or INSN_LIST
42   nodes. This is to be used only on lists that consist exclusively of
43   nodes of one type only.  This is only called by free_EXPR_LIST_list
44   and free_INSN_LIST_list.  */
45static void
46free_list (rtx *listp, rtx *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.  */
67rtx
68alloc_INSN_LIST (rtx val, rtx 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 (int kind, rtx val, rtx next)
91{
92  rtx r;
93
94  if (unused_expr_list)
95    {
96      r = unused_expr_list;
97      unused_expr_list = XEXP (r, 1);
98      XEXP (r, 0) = val;
99      XEXP (r, 1) = next;
100      PUT_REG_NOTE_KIND (r, kind);
101    }
102  else
103    r = gen_rtx_EXPR_LIST (kind, val, next);
104
105  return r;
106}
107
108/* This function will free up an entire list of EXPR_LIST nodes.  */
109void
110free_EXPR_LIST_list (rtx *listp)
111{
112  if (*listp == 0)
113    return;
114  free_list (listp, &unused_expr_list);
115}
116
117/* This function will free up an entire list of INSN_LIST nodes.  */
118void
119free_INSN_LIST_list (rtx *listp)
120{
121  if (*listp == 0)
122    return;
123  free_list (listp, &unused_insn_list);
124}
125
126/* This function will free up an individual EXPR_LIST node.  */
127void
128free_EXPR_LIST_node (rtx ptr)
129{
130  XEXP (ptr, 1) = unused_expr_list;
131  unused_expr_list = ptr;
132}
133
134/* This function will free up an individual INSN_LIST node.  */
135void
136free_INSN_LIST_node (rtx ptr)
137{
138  XEXP (ptr, 1) = unused_insn_list;
139  unused_insn_list = ptr;
140}
141
142#include "gt-lists.h"
143