data-streamer-in.c revision 1.5 
1/* Routines for restoring various data types from a file stream.  This deals
2   with various data types like strings, integers, enums, etc.
3
4   Copyright (C) 2011-2016 Free Software Foundation, Inc.
5   Contributed by Diego Novillo <dnovillo@google.com>
6
7This file is part of GCC.
8
9GCC is free software; you can redistribute it and/or modify it under
10the terms of the GNU General Public License as published by the Free
11Software Foundation; either version 3, or (at your option) any later
12version.
13
14GCC is distributed in the hope that it will be useful, but WITHOUT ANY
15WARRANTY; without even the implied warranty of MERCHANTABILITY or
16FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
17for more details.
18
19You should have received a copy of the GNU General Public License
20along with GCC; see the file COPYING3.  If not see
21<http://www.gnu.org/licenses/>.  */
22
23#include "config.h"
24#include "system.h"
25#include "coretypes.h"
26#include "backend.h"
27#include "tree.h"
28#include "gimple.h"
29#include "cgraph.h"
30#include "data-streamer.h"
31
32/* Read a string from the string table in DATA_IN using input block
33   IB.  Write the length to RLEN.  */
34
35static const char *
36string_for_index (struct data_in *data_in, unsigned int loc, unsigned int *rlen)
37{
38  unsigned int len;
39  const char *result;
40
41  if (!loc)
42    {
43      *rlen = 0;
44      return NULL;
45    }
46
47  /* Get the string stored at location LOC in DATA_IN->STRINGS.  */
48  lto_input_block str_tab (data_in->strings, loc - 1, data_in->strings_len, NULL);
49  len = streamer_read_uhwi (&str_tab);
50  *rlen = len;
51
52  if (str_tab.p + len > data_in->strings_len)
53    internal_error ("bytecode stream: string too long for the string table");
54
55  result = (const char *)(data_in->strings + str_tab.p);
56
57  return result;
58}
59
60
61/* Read a string from the string table in DATA_IN using input block
62   IB.  Write the length to RLEN.  */
63
64const char *
65streamer_read_indexed_string (struct data_in *data_in,
66			      struct lto_input_block *ib, unsigned int *rlen)
67{
68  return string_for_index (data_in, streamer_read_uhwi (ib), rlen);
69}
70
71
72/* Read a NULL terminated string from the string table in DATA_IN.  */
73
74const char *
75streamer_read_string (struct data_in *data_in, struct lto_input_block *ib)
76{
77  unsigned int len;
78  const char *ptr;
79
80  ptr = streamer_read_indexed_string (data_in, ib, &len);
81  if (!ptr)
82    return NULL;
83  if (ptr[len - 1] != '\0')
84    internal_error ("bytecode stream: found non-null terminated string");
85
86  return ptr;
87}
88
89
90/* Read a string from the string table in DATA_IN using the bitpack BP.
91   Write the length to RLEN.  */
92
93const char *
94bp_unpack_indexed_string (struct data_in *data_in,
95			  struct bitpack_d *bp, unsigned int *rlen)
96{
97  return string_for_index (data_in, bp_unpack_var_len_unsigned (bp), rlen);
98}
99
100
101/* Read a NULL terminated string from the string table in DATA_IN.  */
102
103const char *
104bp_unpack_string (struct data_in *data_in, struct bitpack_d *bp)
105{
106  unsigned int len;
107  const char *ptr;
108
109  ptr = bp_unpack_indexed_string (data_in, bp, &len);
110  if (!ptr)
111    return NULL;
112  if (ptr[len - 1] != '\0')
113    internal_error ("bytecode stream: found non-null terminated string");
114
115  return ptr;
116}
117
118
119/* Read an unsigned HOST_WIDE_INT number from IB.  */
120
121unsigned HOST_WIDE_INT
122streamer_read_uhwi (struct lto_input_block *ib)
123{
124  unsigned HOST_WIDE_INT result;
125  int shift;
126  unsigned HOST_WIDE_INT byte;
127  unsigned int p = ib->p;
128  unsigned int len = ib->len;
129
130  const char *data = ib->data;
131  result = data[p++];
132  if ((result & 0x80) != 0)
133    {
134      result &= 0x7f;
135      shift = 7;
136      do
137	{
138	  byte = data[p++];
139	  result |= (byte & 0x7f) << shift;
140	  shift += 7;
141	}
142      while ((byte & 0x80) != 0);
143    }
144
145  /* We check for section overrun after the fact for performance reason.  */
146  if (p > len)
147    lto_section_overrun (ib);
148
149  ib->p = p;
150  return result;
151}
152
153
154/* Read a HOST_WIDE_INT number from IB.  */
155
156HOST_WIDE_INT
157streamer_read_hwi (struct lto_input_block *ib)
158{
159  HOST_WIDE_INT result = 0;
160  int shift = 0;
161  unsigned HOST_WIDE_INT byte;
162
163  while (true)
164    {
165      byte = streamer_read_uchar (ib);
166      result |= (byte & 0x7f) << shift;
167      shift += 7;
168      if ((byte & 0x80) == 0)
169	{
170	  if ((shift < HOST_BITS_PER_WIDE_INT) && (byte & 0x40))
171	    result |= - (HOST_WIDE_INT_1U << shift);
172
173	  return result;
174	}
175    }
176}
177
178/* Read gcov_type value from IB.  */
179
180gcov_type
181streamer_read_gcov_count (struct lto_input_block *ib)
182{
183  gcov_type ret = streamer_read_hwi (ib);
184  return ret;
185}
186