1 /* The IGEN simulator generator for GDB, the GNU Debugger. 2 3 Copyright 2002, 2007, 2008, 2009, 2010, 2011 Free Software Foundation, Inc. 4 5 Contributed by Andrew Cagney. 6 7 This file is part of GDB. 8 9 This program is free software; you can redistribute it and/or modify 10 it under the terms of the GNU General Public License as published by 11 the Free Software Foundation; either version 3 of the License, or 12 (at your option) any later version. 13 14 This program is distributed in the hope that it will be useful, 15 but WITHOUT ANY WARRANTY; without even the implied warranty of 16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 17 GNU General Public License for more details. 18 19 You should have received a copy of the GNU General Public License 20 along with this program. If not, see <http://www.gnu.org/licenses/>. */ 21 22 23 /* Instruction decode table: 24 25 <decode-rule> ::= 26 { <option> } 27 ":" [ <first> ] 28 ":" [ <last> ] 29 ":" [ <force-first> ] 30 ":" [ <force-last> ] 31 ":" [ <constant-field-names> ] 32 ":" [ <word-nr> ] 33 ":" [ <format-names> ] 34 ":" [ <model-names> ] 35 ":" [ <constant> ] 36 ":" [ <path> { "," <path> } ] 37 { ":" <special-mask> 38 ":" [ "!" ] <special-value> 39 ":" <word-nr> } 40 <nl> 41 ; 42 43 44 <path> ::= <int> "," <int> ;; 45 46 <option> ::= 47 <reserved-options> 48 | <code-options> 49 | <optimize-options> 50 | <decode-options> 51 | <constant> 52 | <search-options> 53 ; 54 55 <reserved-options> ::= "zero-reserved" ; 56 <gen-options> ::= "array" | "switch" | "padded-switch" | "goto-switch" ; 57 <optimize-options> ::= "duplicate" | "combine" 58 <decode-options> ::= "normal" | "boolean" ; 59 <search-options> ::= "constants" | "variables" | "mixed" 60 61 Ignore the below: 62 63 64 The instruction decode table contains rules that dictate how igen 65 is going to firstly break down the opcode table and secondly 66 67 The table that follows is used by gen to construct a decision tree 68 that can identify each possible instruction. Gen then outputs this 69 decision tree as (according to config) a table or switch statement 70 as the function idecode. 71 72 In parallel to this, as mentioned above, WITH_EXPANDED_SEMANTICS 73 determines of the semantic functions themselves should be expanded 74 in a similar way. 75 76 <first> 77 <last> 78 79 Range of bits (within the instruction) that should be searched for 80 an instruction field. Within such ranges, gen looks for opcodes 81 (constants), registers (strings) and reserved bits (slash) and 82 according to the rules that follows includes or excludes them from 83 a possible instruction field. 84 85 <force_first> 86 <force_last> 87 88 If an instruction field was found, enlarge the field size so that 89 it is forced to at least include bits starting from <force_first> 90 (<force_last>). To stop this occuring, use <force_first> = <last> 91 + 1 and <force_last> = <first> - 1. 92 93 <force_reserved> 94 95 Treat `/' (reserved) fields as a constant (zero) instead of 96 variable when looking for an instruction field. 97 98 <force_expansion> 99 100 Treat any contained register (string) fields as constant when 101 determining the instruction field. For the instruction decode (and 102 controled by IDECODE_EXPAND_SEMANTICS) this forces the expansion of 103 what would otherwize be non constant bits of an instruction. 104 105 <use_switch> 106 107 Should this table be expanded using a switch statement (val 1) and 108 if so, should it be padded with entries so as to force the compiler 109 to generate a jump table (val 2). Or a branch table (val 3). 110 111 <special_mask> 112 <special_value> 113 <special_rule> 114 <special_constant> 115 116 Special rule to fine tune how specific (or groups) of instructions 117 are expanded. The applicability of the rule is determined by 118 119 <special_mask> != 0 && (instruction> & <special_mask>) == <special_value> 120 121 Where <instruction> is obtained by looking only at constant fields 122 with in an instructions spec. When determining an expansion, the 123 rule is only considered when a node contains a single instruction. 124 <special_rule> can be any of: 125 126 0: for this instruction, expand by earlier rules 127 1: expand bits <force_low> .. <force_hi> only 128 2: boolean expansion of only zero/non-zero cases 129 3: boolean expansion of equality of special constant 130 131 */ 132 133 134 typedef enum 135 { 136 normal_decode_rule, 137 boolean_rule, 138 } 139 decode_special_type; 140 141 142 typedef enum 143 { 144 invalid_gen, 145 array_gen, 146 switch_gen, 147 padded_switch_gen, 148 goto_switch_gen, 149 } 150 decode_gen_type; 151 152 153 enum 154 { 155 decode_cond_mask_field, 156 decode_cond_value_field, 157 decode_cond_word_nr_field, 158 nr_decode_cond_fields, 159 }; 160 161 typedef struct _decode_path decode_path; 162 struct _decode_path 163 { 164 int opcode_nr; 165 decode_path *parent; 166 }; 167 168 typedef struct _decode_path_list decode_path_list; 169 struct _decode_path_list 170 { 171 decode_path *path; 172 decode_path_list *next; 173 }; 174 175 176 typedef struct _decode_cond decode_cond; 177 struct _decode_cond 178 { 179 int word_nr; 180 int mask[max_insn_bit_size]; 181 int value[max_insn_bit_size]; 182 int is_equal; 183 decode_cond *next; 184 }; 185 186 typedef enum 187 { 188 decode_find_mixed, 189 decode_find_constants, 190 decode_find_strings, 191 } 192 decode_search_type; 193 194 enum 195 { 196 decode_options_field, 197 decode_first_field, 198 decode_last_field, 199 decode_force_first_field, 200 decode_force_last_field, 201 decode_constant_field_names_field, 202 decode_word_nr_field, 203 decode_format_names_field, 204 decode_model_names_field, 205 decode_paths_field, 206 nr_decode_fields, 207 min_nr_decode_fields = decode_last_field + 1, 208 }; 209 210 211 typedef struct _decode_table decode_table; 212 struct _decode_table 213 { 214 line_ref *line; 215 decode_special_type type; 216 decode_gen_type gen; 217 decode_search_type search; 218 int first; 219 int last; 220 int force_first; 221 int force_last; 222 filter *constant_field_names; 223 int word_nr; 224 /* if a boolean */ 225 unsigned constant; 226 /* options */ 227 int with_zero_reserved; 228 int with_duplicates; 229 int with_combine; 230 /* conditions on the rule being applied */ 231 decode_path_list *paths; 232 filter *format_names; 233 filter *model_names; 234 decode_cond *conditions; 235 decode_table *next; 236 }; 237 238 239 extern decode_table *load_decode_table (char *file_name); 240 241 extern int decode_table_max_word_nr (decode_table *rule); 242 243 extern void dump_decode_rule 244 (lf *file, char *prefix, decode_table *rule, char *suffix); 245