gcc/data-streamer-in.c

   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 2011 Free Software Foundation, Inc.
   5    Contributed by Diego Novillo <dnovillo@google.com>
   6
   7 This file is part of GCC.
   8
   9 GCC is free software; you can redistribute it and/or modify it under
  10 the terms of the GNU General Public License as published by the Free
  11 Software Foundation; either version 3, or (at your option) any later
  12 version.
  13
  14 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  15 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  16 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  17 for more details.
  18
  19 You should have received a copy of the GNU General Public License
  20 along 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 "diagnostic.h"
  27 #include "data-streamer.h"
  28
  29 /* Read a string from the string table in DATA_IN using input block
  30    IB.  Write the length to RLEN.  */
  31
  32 const char *
  33 string_for_index (struct data_in *data_in, unsigned int loc, unsigned int *rlen)
  34 {
  35   struct lto_input_block str_tab;
  36   unsigned int len;
  37   const char *result;
  38
  39   if (!loc)
  40     {
  41       *rlen = 0;
  42       return NULL;
  43     }
  44
  45   /* Get the string stored at location LOC in DATA_IN->STRINGS.  */
  46   LTO_INIT_INPUT_BLOCK (str_tab, data_in->strings, loc - 1,
  47                         data_in->strings_len);
  48   len = streamer_read_uhwi (&str_tab);
  49   *rlen = len;
  50
  51   if (str_tab.p + len > data_in->strings_len)
  52     internal_error ("bytecode stream: string too long for the string table");
  53
  54   result = (const char *)(data_in->strings + str_tab.p);
  55
  56   return result;
  57 }
  58
  59
  60 /* Read a string from the string table in DATA_IN using input block
  61    IB.  Write the length to RLEN.  */
  62
  63 const char *
  64 streamer_read_indexed_string (struct data_in *data_in,
  65                               struct lto_input_block *ib, unsigned int *rlen)
  66 {
  67   return string_for_index (data_in, streamer_read_uhwi (ib), rlen);
  68 }
  69
  70
  71 /* Read a NULL terminated string from the string table in DATA_IN.  */
  72
  73 const char *
  74 streamer_read_string (struct data_in *data_in, struct lto_input_block *ib)
  75 {
  76   unsigned int len;
  77   const char *ptr;
  78
  79   ptr = streamer_read_indexed_string (data_in, ib, &len);
  80   if (!ptr)
  81     return NULL;
  82   if (ptr[len - 1] != '\0')
  83     internal_error ("bytecode stream: found non-null terminated string");
  84
  85   return ptr;
  86 }
  87
  88
  89 /* Read an unsigned HOST_WIDE_INT number from IB.  */
  90
  91 unsigned HOST_WIDE_INT
  92 streamer_read_uhwi (struct lto_input_block *ib)
  93 {
  94   unsigned HOST_WIDE_INT result = 0;
  95   int shift = 0;
  96   unsigned HOST_WIDE_INT byte;
  97
  98   while (true)
  99     {
 100       byte = streamer_read_uchar (ib);
 101       result |= (byte & 0x7f) << shift;
 102       shift += 7;
 103       if ((byte & 0x80) == 0)
 104         return result;
 105     }
 106 }
 107
 108
 109 /* Read a HOST_WIDE_INT number from IB.  */
 110
 111 HOST_WIDE_INT
 112 streamer_read_hwi (struct lto_input_block *ib)
 113 {
 114   HOST_WIDE_INT result = 0;
 115   int shift = 0;
 116   unsigned HOST_WIDE_INT byte;
 117
 118   while (true)
 119     {
 120       byte = streamer_read_uchar (ib);
 121       result |= (byte & 0x7f) << shift;
 122       shift += 7;
 123       if ((byte & 0x80) == 0)
 124         {
 125           if ((shift < HOST_BITS_PER_WIDE_INT) && (byte & 0x40))
 126             result |= - ((HOST_WIDE_INT)1 << shift);
 127
 128           return result;
 129         }
 130     }
 131 }