1/* CGEN generic disassembler support code.
2   Copyright (C) 1996-2017 Free Software Foundation, Inc.
3
4   This file is part of libopcodes.
5
6   This library 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 3, or (at your option)
9   any later version.
10
11   It is distributed in the hope that it will be useful, but WITHOUT
12   ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
13   or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
14   License for more details.
15
16   You should have received a copy of the GNU General Public License along
17   with this program; if not, write to the Free Software Foundation, Inc.,
18   51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA.  */
19
20#include "sysdep.h"
21#include <stdio.h>
22#include "ansidecl.h"
23#include "libiberty.h"
24#include "bfd.h"
25#include "symcat.h"
26#include "opcode/cgen.h"
27
28static CGEN_INSN_LIST *  hash_insn_array        (CGEN_CPU_DESC, const CGEN_INSN *, int, int, CGEN_INSN_LIST **, CGEN_INSN_LIST *);
29static CGEN_INSN_LIST *  hash_insn_list         (CGEN_CPU_DESC, const CGEN_INSN_LIST *, CGEN_INSN_LIST **, CGEN_INSN_LIST *);
30static void              build_dis_hash_table   (CGEN_CPU_DESC);
31static int		 count_decodable_bits   (const CGEN_INSN *);
32static void		 add_insn_to_hash_chain (CGEN_INSN_LIST *,
33						 const CGEN_INSN *,
34						 CGEN_INSN_LIST **,
35						 unsigned int);
36
37/* Return the number of decodable bits in this insn.  */
38static int
39count_decodable_bits (const CGEN_INSN *insn)
40{
41  unsigned mask = CGEN_INSN_BASE_MASK (insn);
42  int bits = 0;
43  unsigned m;
44
45  for (m = 1; m != 0; m <<= 1)
46    {
47      if (mask & m)
48	++bits;
49    }
50  return bits;
51}
52
53/* Add an instruction to the hash chain.  */
54static void
55add_insn_to_hash_chain (CGEN_INSN_LIST *hentbuf,
56			const CGEN_INSN *insn,
57			CGEN_INSN_LIST **htable,
58			unsigned int hash)
59{
60  CGEN_INSN_LIST *current_buf;
61  CGEN_INSN_LIST *previous_buf;
62  int insn_decodable_bits;
63
64  /* Add insns sorted by the number of decodable bits, in decreasing order.
65     This ensures that any insn which is a special case of another will be
66     checked first.  */
67  insn_decodable_bits = count_decodable_bits (insn);
68  previous_buf = NULL;
69  for (current_buf = htable[hash]; current_buf != NULL;
70       current_buf = current_buf->next)
71    {
72      int current_decodable_bits = count_decodable_bits (current_buf->insn);
73      if (insn_decodable_bits >= current_decodable_bits)
74	break;
75      previous_buf = current_buf;
76    }
77
78  /* Now insert the new insn.  */
79  hentbuf->insn = insn;
80  hentbuf->next = current_buf;
81  if (previous_buf == NULL)
82    htable[hash] = hentbuf;
83  else
84    previous_buf->next = hentbuf;
85}
86
87/* Subroutine of build_dis_hash_table to add INSNS to the hash table.
88
89   COUNT is the number of elements in INSNS.
90   ENTSIZE is sizeof (CGEN_IBASE) for the target.
91   ??? No longer used but leave in for now.
92   HTABLE points to the hash table.
93   HENTBUF is a pointer to sufficiently large buffer of hash entries.
94   The result is a pointer to the next entry to use.
95
96   The table is scanned backwards as additions are made to the front of the
97   list and we want earlier ones to be prefered.  */
98
99static CGEN_INSN_LIST *
100hash_insn_array (CGEN_CPU_DESC cd,
101		 const CGEN_INSN * insns,
102		 int count,
103		 int entsize ATTRIBUTE_UNUSED,
104		 CGEN_INSN_LIST ** htable,
105		 CGEN_INSN_LIST * hentbuf)
106{
107  int big_p = CGEN_CPU_INSN_ENDIAN (cd) == CGEN_ENDIAN_BIG;
108  int i;
109
110  for (i = count - 1; i >= 0; --i, ++hentbuf)
111    {
112      unsigned int hash;
113      char buf [4];
114      unsigned long value;
115      const CGEN_INSN *insn = &insns[i];
116
117      if (! (* cd->dis_hash_p) (insn))
118	continue;
119
120      /* We don't know whether the target uses the buffer or the base insn
121	 to hash on, so set both up.  */
122
123      value = CGEN_INSN_BASE_VALUE (insn);
124      bfd_put_bits ((bfd_vma) value,
125		    buf,
126		    CGEN_INSN_MASK_BITSIZE (insn),
127		    big_p);
128      hash = (* cd->dis_hash) (buf, value);
129      add_insn_to_hash_chain (hentbuf, insn, htable, hash);
130    }
131
132  return hentbuf;
133}
134
135/* Subroutine of build_dis_hash_table to add INSNS to the hash table.
136   This function is identical to hash_insn_array except the insns are
137   in a list.  */
138
139static CGEN_INSN_LIST *
140hash_insn_list (CGEN_CPU_DESC cd,
141		const CGEN_INSN_LIST *insns,
142		CGEN_INSN_LIST **htable,
143		CGEN_INSN_LIST *hentbuf)
144{
145  int big_p = CGEN_CPU_INSN_ENDIAN (cd) == CGEN_ENDIAN_BIG;
146  const CGEN_INSN_LIST *ilist;
147
148  for (ilist = insns; ilist != NULL; ilist = ilist->next, ++ hentbuf)
149    {
150      unsigned int hash;
151      char buf[4];
152      unsigned long value;
153
154      if (! (* cd->dis_hash_p) (ilist->insn))
155	continue;
156
157      /* We don't know whether the target uses the buffer or the base insn
158	 to hash on, so set both up.  */
159
160      value = CGEN_INSN_BASE_VALUE (ilist->insn);
161      bfd_put_bits((bfd_vma) value,
162		   buf,
163		   CGEN_INSN_MASK_BITSIZE (ilist->insn),
164		   big_p);
165      hash = (* cd->dis_hash) (buf, value);
166      add_insn_to_hash_chain (hentbuf, ilist->insn, htable, hash);
167    }
168
169  return hentbuf;
170}
171
172/* Build the disassembler instruction hash table.  */
173
174static void
175build_dis_hash_table (CGEN_CPU_DESC cd)
176{
177  int count = cgen_insn_count (cd) + cgen_macro_insn_count (cd);
178  CGEN_INSN_TABLE *insn_table = & cd->insn_table;
179  CGEN_INSN_TABLE *macro_insn_table = & cd->macro_insn_table;
180  unsigned int hash_size = cd->dis_hash_size;
181  CGEN_INSN_LIST *hash_entry_buf;
182  CGEN_INSN_LIST **dis_hash_table;
183  CGEN_INSN_LIST *dis_hash_table_entries;
184
185  /* The space allocated for the hash table consists of two parts:
186     the hash table and the hash lists.  */
187
188  dis_hash_table = (CGEN_INSN_LIST **)
189    xmalloc (hash_size * sizeof (CGEN_INSN_LIST *));
190  memset (dis_hash_table, 0, hash_size * sizeof (CGEN_INSN_LIST *));
191  dis_hash_table_entries = hash_entry_buf = (CGEN_INSN_LIST *)
192    xmalloc (count * sizeof (CGEN_INSN_LIST));
193
194  /* Add compiled in insns.
195     Don't include the first one as it is a reserved entry.  */
196  /* ??? It was the end of all hash chains, and also the special
197     "invalid insn" marker.  May be able to do it differently now.  */
198
199  hash_entry_buf = hash_insn_array (cd,
200				    insn_table->init_entries + 1,
201				    insn_table->num_init_entries - 1,
202				    insn_table->entry_size,
203				    dis_hash_table, hash_entry_buf);
204
205  /* Add compiled in macro-insns.  */
206
207  hash_entry_buf = hash_insn_array (cd, macro_insn_table->init_entries,
208				    macro_insn_table->num_init_entries,
209				    macro_insn_table->entry_size,
210				    dis_hash_table, hash_entry_buf);
211
212  /* Add runtime added insns.
213     Later added insns will be prefered over earlier ones.  */
214
215  hash_entry_buf = hash_insn_list (cd, insn_table->new_entries,
216				   dis_hash_table, hash_entry_buf);
217
218  /* Add runtime added macro-insns.  */
219
220  hash_insn_list (cd, macro_insn_table->new_entries,
221		  dis_hash_table, hash_entry_buf);
222
223  cd->dis_hash_table = dis_hash_table;
224  cd->dis_hash_table_entries = dis_hash_table_entries;
225}
226
227/* Return the first entry in the hash list for INSN.  */
228
229CGEN_INSN_LIST *
230cgen_dis_lookup_insn (CGEN_CPU_DESC cd, const char * buf, CGEN_INSN_INT value)
231{
232  unsigned int hash;
233
234  if (cd->dis_hash_table == NULL)
235    build_dis_hash_table (cd);
236
237  hash = (* cd->dis_hash) (buf, value);
238
239  return cd->dis_hash_table[hash];
240}
241