1 | /* OSF/rose half-pic support functions. |
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2 | Copyright (C) 1992 Free Software Foundation, Inc. |
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3 | |
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4 | This file is part of GNU CC. |
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5 | |
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6 | GNU CC is free software; you can redistribute it and/or modify |
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7 | it under the terms of the GNU General Public License as published by |
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8 | the Free Software Foundation; either version 2, or (at your option) |
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9 | any later version. |
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10 | |
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11 | GNU CC is distributed in the hope that it will be useful, |
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12 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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14 | GNU General Public License for more details. |
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15 | |
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16 | You should have received a copy of the GNU General Public License |
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17 | along with GNU CC; see the file COPYING. If not, write to |
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18 | the Free Software Foundation, 59 Temple Place - Suite 330, |
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19 | Boston, MA 02111-1307, USA. */ |
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20 | |
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21 | /* The OSF/rose half-pic model assumes that the non-library code does |
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22 | not need to have full PIC (position independent code), but rather, |
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23 | that pointers to external references are put into the data section |
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24 | and dereferenced as normal pointers. References to static data does |
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25 | not need to be PIC-ized. |
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26 | |
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27 | Another optimization is to have the compiler know what symbols are |
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28 | in the shared libraries, and to only lay down the pointers to |
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29 | things which in the library proper. */ |
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30 | |
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31 | #include "config.h" |
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32 | |
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33 | #ifdef HALF_PIC_INIT |
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34 | |
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35 | #include "tree.h" |
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36 | #include "rtl.h" |
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37 | #include <stdio.h> |
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38 | #include "obstack.h" |
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39 | |
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40 | #define obstack_chunk_alloc xmalloc |
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41 | #define obstack_chunk_free free |
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42 | |
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43 | extern char *xmalloc (); |
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44 | extern void free (); |
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45 | extern rtx eliminate_constant_term (); |
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46 | extern void assemble_name (); |
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47 | extern void output_addr_const (); |
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48 | |
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49 | int flag_half_pic = 0; /* Global half-pic flag. */ |
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50 | int half_pic_number_ptrs = 0; /* # distinct pointers found */ |
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51 | int half_pic_number_refs = 0; /* # half-pic references */ |
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52 | int (*ptr_half_pic_address_p)() = half_pic_address_p; |
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53 | |
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54 | /* Obstack to hold generated pic names. */ |
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55 | static struct obstack half_pic_obstack; |
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56 | |
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57 | /* List of pointers created to pic references. */ |
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58 | |
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59 | struct all_refs { |
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60 | struct all_refs *hash_next; /* next name in hash chain */ |
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61 | struct all_refs *next; /* next name created */ |
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62 | int external_p; /* name is an external reference */ |
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63 | int pointer_p; /* pointer created. */ |
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64 | char *ref_name; /* reference name to ptr to real_name */ |
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65 | int ref_len; /* reference name length */ |
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66 | char *real_name; /* real function/data name */ |
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67 | int real_len; /* strlen (real_name) */ |
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68 | }; |
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69 | |
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70 | static struct all_refs *half_pic_names; |
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71 | |
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72 | static char *half_pic_prefix; |
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73 | static int half_pic_prefix_len; |
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74 | |
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75 | |
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76 | /* Return the hash bucket of a name or NULL. The hash chain is |
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77 | organized as a self reorganizing circularly linked chain. It is |
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78 | assumed that any name passed to use will never be reallocated. For |
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79 | names in SYMBOL_REF's this is true, because the names are allocated |
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80 | on the permanent obstack. */ |
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81 | |
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82 | #ifndef MAX_HASH_TABLE |
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83 | #define MAX_HASH_TABLE 1009 |
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84 | #endif |
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85 | |
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86 | #define HASHBITS 30 |
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87 | |
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88 | static struct all_refs * |
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89 | half_pic_hash (name, len, create_p) |
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90 | char *name; /* name to hash */ |
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91 | int len; /* length of the name (or 0 to call strlen) */ |
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92 | int create_p; /* != 0 to create new hash bucket if new */ |
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93 | { |
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94 | static struct all_refs *hash_table[MAX_HASH_TABLE]; |
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95 | static struct all_refs zero_all_refs; |
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96 | |
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97 | unsigned char *uname; |
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98 | int hash; |
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99 | int i; |
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100 | int ch; |
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101 | struct all_refs *first; |
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102 | struct all_refs *ptr; |
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103 | |
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104 | if (len == 0) |
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105 | len = strlen (name); |
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106 | |
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107 | /* Compute hash code */ |
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108 | uname = (unsigned char *)name; |
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109 | ch = uname[0]; |
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110 | hash = len * 613 + ch; |
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111 | for (i = 1; i < len; i += 2) |
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112 | hash = (hash * 613) + uname[i]; |
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113 | |
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114 | hash &= (1 << HASHBITS) - 1; |
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115 | hash %= MAX_HASH_TABLE; |
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116 | |
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117 | /* See if the name is in the hash table. */ |
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118 | ptr = first = hash_table[hash]; |
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119 | if (ptr) |
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120 | { |
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121 | do |
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122 | { |
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123 | if (len == ptr->real_len |
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124 | && ch == *(ptr->real_name) |
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125 | && !strcmp (name, ptr->real_name)) |
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126 | { |
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127 | hash_table[hash] = ptr; |
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128 | return ptr; |
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129 | } |
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130 | |
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131 | ptr = ptr->hash_next; |
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132 | } |
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133 | while (ptr != first); |
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134 | } |
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135 | |
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136 | /* name not in hash table. */ |
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137 | if (!create_p) |
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138 | return (struct all_refs *)0; |
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139 | |
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140 | ptr = (struct all_refs *) obstack_alloc (&half_pic_obstack, sizeof (struct all_refs)); |
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141 | *ptr = zero_all_refs; |
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142 | |
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143 | ptr->real_name = name; |
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144 | ptr->real_len = len; |
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145 | |
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146 | /* Update circular links. */ |
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147 | if (first == (struct all_refs *)0) |
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148 | ptr->hash_next = ptr; |
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149 | |
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150 | else |
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151 | { |
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152 | ptr->hash_next = first->hash_next; |
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153 | first->hash_next = ptr; |
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154 | } |
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155 | |
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156 | hash_table[hash] = ptr; |
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157 | return ptr; |
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158 | } |
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159 | |
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160 | |
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161 | /* Do any half-pic initializations. */ |
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162 | |
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163 | void |
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164 | half_pic_init () |
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165 | { |
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166 | flag_half_pic = TRUE; |
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167 | half_pic_prefix = HALF_PIC_PREFIX; |
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168 | half_pic_prefix_len = strlen (half_pic_prefix); |
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169 | obstack_init (&half_pic_obstack); |
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170 | } |
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171 | |
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172 | |
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173 | /* Write out all pointers to pic references. */ |
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174 | |
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175 | void |
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176 | half_pic_finish (stream) |
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177 | FILE *stream; |
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178 | { |
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179 | struct all_refs *p = half_pic_names; |
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180 | |
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181 | if (!p) |
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182 | return; |
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183 | |
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184 | data_section (); |
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185 | for (; p != 0; p = p->next) |
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186 | { |
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187 | /* Emit the pointer if used. */ |
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188 | if (p->pointer_p) |
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189 | { |
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190 | ASM_OUTPUT_LABEL (stream, p->ref_name); |
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191 | ASM_OUTPUT_INT (stream, gen_rtx (SYMBOL_REF, Pmode, p->real_name)); |
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192 | } |
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193 | } |
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194 | } |
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195 | |
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196 | |
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197 | /* Encode in a declaration whether or not it is half-pic. */ |
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198 | |
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199 | void |
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200 | half_pic_encode (decl) |
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201 | tree decl; |
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202 | { |
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203 | enum tree_code code = TREE_CODE (decl); |
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204 | tree asm_name; |
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205 | struct all_refs *ptr; |
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206 | |
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207 | if (!flag_half_pic) |
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208 | return; |
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209 | |
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210 | if (code != VAR_DECL && code != FUNCTION_DECL) |
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211 | return; |
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212 | |
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213 | asm_name = DECL_ASSEMBLER_NAME (decl); |
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214 | |
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215 | if (!asm_name) |
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216 | return; |
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217 | |
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218 | #ifdef HALF_PIC_DEBUG |
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219 | if (HALF_PIC_DEBUG) |
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220 | { |
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221 | if (HALF_PIC_DEBUG) |
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222 | fprintf (stderr, "\n========== Half_pic_encode %.*s\n", |
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223 | IDENTIFIER_LENGTH (asm_name), |
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224 | IDENTIFIER_POINTER (asm_name)); |
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225 | debug_tree (decl); |
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226 | } |
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227 | #endif |
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228 | |
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229 | /* If this is not an external reference, it can't be half-pic. */ |
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230 | if (!DECL_EXTERNAL (decl) && (code != VAR_DECL || !TREE_PUBLIC (decl))) |
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231 | return; |
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232 | |
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233 | ptr = half_pic_hash (IDENTIFIER_POINTER (asm_name), |
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234 | IDENTIFIER_LENGTH (asm_name), |
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235 | TRUE); |
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236 | |
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237 | ptr->external_p = TRUE; |
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238 | |
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239 | #ifdef HALF_PIC_DEBUG |
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240 | if (HALF_PIC_DEBUG) |
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241 | fprintf (stderr, "\n%.*s is half-pic\n", |
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242 | IDENTIFIER_LENGTH (asm_name), |
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243 | IDENTIFIER_POINTER (asm_name)); |
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244 | #endif |
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245 | } |
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246 | |
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247 | |
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248 | /* Mark that an object is now local, and no longer needs half-pic. */ |
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249 | |
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250 | void |
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251 | half_pic_declare (name) |
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252 | char *name; |
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253 | { |
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254 | struct all_refs *ptr; |
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255 | |
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256 | if (!flag_half_pic) |
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257 | return; |
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258 | |
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259 | ptr = half_pic_hash (name, 0, FALSE); |
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260 | if (!ptr) |
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261 | return; |
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262 | |
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263 | ptr->external_p = FALSE; |
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264 | |
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265 | #ifdef HALF_PIC_DEBUG |
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266 | if (HALF_PIC_DEBUG) |
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267 | fprintf (stderr, "\n========== Half_pic_declare %s\n", name); |
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268 | #endif |
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269 | } |
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270 | |
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271 | |
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272 | /* Mark that an object is explicitly external. */ |
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273 | |
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274 | void |
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275 | half_pic_external (name) |
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276 | char *name; |
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277 | { |
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278 | struct all_refs *ptr; |
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279 | |
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280 | if (!flag_half_pic) |
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281 | return; |
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282 | |
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283 | ptr = half_pic_hash (name, 0, TRUE); |
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284 | if (!ptr) |
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285 | return; |
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286 | |
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287 | ptr->external_p = TRUE; |
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288 | |
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289 | #ifdef HALF_PIC_DEBUG |
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290 | if (HALF_PIC_DEBUG) |
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291 | fprintf (stderr, "\n========== Half_pic_external %s\n", name); |
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292 | #endif |
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293 | } |
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294 | |
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295 | |
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296 | /* Return whether an address is half-pic. */ |
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297 | |
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298 | int |
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299 | half_pic_address_p (addr) |
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300 | rtx addr; |
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301 | { |
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302 | char *name; |
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303 | int len; |
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304 | struct all_refs *ptr; |
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305 | |
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306 | if (!flag_half_pic) |
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307 | return FALSE; |
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308 | |
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309 | switch (GET_CODE (addr)) |
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310 | { |
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311 | default: |
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312 | break; |
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313 | |
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314 | case CONST: |
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315 | { |
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316 | rtx offset = const0_rtx; |
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317 | addr = eliminate_constant_term (XEXP (addr, 0), &offset); |
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318 | if (GET_CODE (addr) != SYMBOL_REF) |
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319 | return FALSE; |
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320 | } |
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321 | /* fall through */ |
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322 | |
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323 | case SYMBOL_REF: |
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324 | name = XSTR (addr, 0); |
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325 | |
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326 | #ifdef HALF_PIC_DEBUG |
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327 | if (HALF_PIC_DEBUG) |
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328 | fprintf (stderr, "\n========== Half_pic_address_p %s\n", name); |
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329 | #endif |
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330 | |
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331 | /* If this is a label, it will have a '*' in front of it. */ |
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332 | if (name[0] == '*') |
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333 | return FALSE; |
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334 | |
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335 | /* If this is a reference to the actual half-pic pointer, it |
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336 | is obviously not half-pic. */ |
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337 | |
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338 | len = strlen (name); |
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339 | if (len > half_pic_prefix_len |
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340 | && half_pic_prefix[0] == name[0] |
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341 | && !strncmp (name, half_pic_prefix, half_pic_prefix_len)) |
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342 | return FALSE; |
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343 | |
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344 | ptr = half_pic_hash (name, len, FALSE); |
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345 | if (ptr == (struct all_refs *)0) |
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346 | return FALSE; |
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347 | |
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348 | if (ptr->external_p) |
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349 | { |
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350 | #ifdef HALF_PIC_DEBUG |
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351 | if (HALF_PIC_DEBUG) |
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352 | fprintf (stderr, "%s is half-pic\n", name); |
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353 | #endif |
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354 | return TRUE; |
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355 | } |
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356 | } |
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357 | |
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358 | return FALSE; |
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359 | } |
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360 | |
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361 | |
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362 | /* Return the name of the pointer to the PIC function, allocating |
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363 | it if need be. */ |
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364 | |
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365 | struct rtx_def * |
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366 | half_pic_ptr (operand) |
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367 | rtx operand; |
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368 | { |
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369 | char *name; |
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370 | struct all_refs *p; |
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371 | int len; |
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372 | |
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373 | if (GET_CODE (operand) != SYMBOL_REF) |
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374 | return operand; |
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375 | |
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376 | name = XSTR (operand, 0); |
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377 | len = strlen (name); |
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378 | p = half_pic_hash (name, len, FALSE); |
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379 | if (p == (struct all_refs *)0 || !p->external_p) |
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380 | return operand; |
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381 | |
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382 | if (!p->pointer_p) |
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383 | { /* first time, create pointer */ |
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384 | obstack_grow (&half_pic_obstack, half_pic_prefix, half_pic_prefix_len); |
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385 | obstack_grow (&half_pic_obstack, name, len+1); |
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386 | |
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387 | p->next = half_pic_names; |
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388 | p->ref_name = (char *) obstack_finish (&half_pic_obstack); |
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389 | p->ref_len = len + half_pic_prefix_len; |
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390 | p->pointer_p = TRUE; |
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391 | |
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392 | half_pic_names = p; |
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393 | half_pic_number_ptrs++; |
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394 | } |
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395 | |
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396 | half_pic_number_refs++; |
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397 | return gen_rtx (SYMBOL_REF, Pmode, p->ref_name); |
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398 | } |
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399 | |
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400 | #endif /* HALF_PIC_INIT */ |
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