| 1 | /* frags.c - manage frags - |
| 2 | Copyright 1987, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, |
| 3 | 1999, 2000 |
| 4 | Free Software Foundation, Inc. |
| 5 | |
| 6 | This file is part of GAS, the GNU Assembler. |
| 7 | |
| 8 | GAS is free software; you can redistribute it and/or modify |
| 9 | it under the terms of the GNU General Public License as published by |
| 10 | the Free Software Foundation; either version 2, or (at your option) |
| 11 | any later version. |
| 12 | |
| 13 | GAS is distributed in the hope that it will be useful, |
| 14 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 15 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 16 | GNU General Public License for more details. |
| 17 | |
| 18 | You should have received a copy of the GNU General Public License |
| 19 | along with GAS; see the file COPYING. If not, write to the Free |
| 20 | Software Foundation, 59 Temple Place - Suite 330, Boston, MA |
| 21 | 02111-1307, USA. */ |
| 22 | |
| 23 | #include "as.h" |
| 24 | #include "subsegs.h" |
| 25 | #include "obstack.h" |
| 26 | |
| 27 | extern fragS zero_address_frag; |
| 28 | extern fragS bss_address_frag; |
| 29 | \f |
| 30 | /* Initialization for frag routines. */ |
| 31 | |
| 32 | void |
| 33 | frag_init () |
| 34 | { |
| 35 | zero_address_frag.fr_type = rs_fill; |
| 36 | bss_address_frag.fr_type = rs_fill; |
| 37 | } |
| 38 | \f |
| 39 | /* Allocate a frag on the specified obstack. |
| 40 | Call this routine from everywhere else, so that all the weird alignment |
| 41 | hackery can be done in just one place. */ |
| 42 | |
| 43 | fragS * |
| 44 | frag_alloc (ob) |
| 45 | struct obstack *ob; |
| 46 | { |
| 47 | fragS *ptr; |
| 48 | int oalign; |
| 49 | |
| 50 | (void) obstack_alloc (ob, 0); |
| 51 | oalign = obstack_alignment_mask (ob); |
| 52 | obstack_alignment_mask (ob) = 0; |
| 53 | ptr = (fragS *) obstack_alloc (ob, SIZEOF_STRUCT_FRAG); |
| 54 | obstack_alignment_mask (ob) = oalign; |
| 55 | memset (ptr, 0, SIZEOF_STRUCT_FRAG); |
| 56 | return ptr; |
| 57 | } |
| 58 | \f |
| 59 | /* Try to augment current frag by nchars chars. |
| 60 | If there is no room, close of the current frag with a ".fill 0" |
| 61 | and begin a new frag. Unless the new frag has nchars chars available |
| 62 | do not return. Do not set up any fields of *now_frag. */ |
| 63 | |
| 64 | void |
| 65 | frag_grow (nchars) |
| 66 | unsigned int nchars; |
| 67 | { |
| 68 | if (obstack_room (&frchain_now->frch_obstack) < nchars) |
| 69 | { |
| 70 | unsigned int n; |
| 71 | long oldc; |
| 72 | |
| 73 | frag_wane (frag_now); |
| 74 | frag_new (0); |
| 75 | oldc = frchain_now->frch_obstack.chunk_size; |
| 76 | frchain_now->frch_obstack.chunk_size = 2 * nchars + SIZEOF_STRUCT_FRAG; |
| 77 | if (frchain_now->frch_obstack.chunk_size > 0) |
| 78 | while ((n = obstack_room (&frchain_now->frch_obstack)) < nchars |
| 79 | && (unsigned long) frchain_now->frch_obstack.chunk_size > nchars) |
| 80 | { |
| 81 | frag_wane (frag_now); |
| 82 | frag_new (0); |
| 83 | } |
| 84 | frchain_now->frch_obstack.chunk_size = oldc; |
| 85 | } |
| 86 | if (obstack_room (&frchain_now->frch_obstack) < nchars) |
| 87 | as_fatal (_("can't extend frag %u chars"), nchars); |
| 88 | } |
| 89 | \f |
| 90 | /* Call this to close off a completed frag, and start up a new (empty) |
| 91 | frag, in the same subsegment as the old frag. |
| 92 | [frchain_now remains the same but frag_now is updated.] |
| 93 | Because this calculates the correct value of fr_fix by |
| 94 | looking at the obstack 'frags', it needs to know how many |
| 95 | characters at the end of the old frag belong to the maximal |
| 96 | variable part; The rest must belong to fr_fix. |
| 97 | It doesn't actually set up the old frag's fr_var. You may have |
| 98 | set fr_var == 1, but allocated 10 chars to the end of the frag; |
| 99 | In this case you pass old_frags_var_max_size == 10. |
| 100 | In fact, you may use fr_var for something totally unrelated to the |
| 101 | size of the variable part of the frag; None of the generic frag |
| 102 | handling code makes use of fr_var. |
| 103 | |
| 104 | Make a new frag, initialising some components. Link new frag at end |
| 105 | of frchain_now. */ |
| 106 | |
| 107 | void |
| 108 | frag_new (old_frags_var_max_size) |
| 109 | /* Number of chars (already allocated on obstack frags) in |
| 110 | variable_length part of frag. */ |
| 111 | int old_frags_var_max_size; |
| 112 | { |
| 113 | fragS *former_last_fragP; |
| 114 | frchainS *frchP; |
| 115 | |
| 116 | assert (frchain_now->frch_last == frag_now); |
| 117 | |
| 118 | /* Fix up old frag's fr_fix. */ |
| 119 | frag_now->fr_fix = frag_now_fix_octets () - old_frags_var_max_size; |
| 120 | /* Make sure its type is valid. */ |
| 121 | assert (frag_now->fr_type != 0); |
| 122 | |
| 123 | /* This will align the obstack so the next struct we allocate on it |
| 124 | will begin at a correct boundary. */ |
| 125 | obstack_finish (&frchain_now->frch_obstack); |
| 126 | frchP = frchain_now; |
| 127 | know (frchP); |
| 128 | former_last_fragP = frchP->frch_last; |
| 129 | assert (former_last_fragP != 0); |
| 130 | assert (former_last_fragP == frag_now); |
| 131 | frag_now = frag_alloc (&frchP->frch_obstack); |
| 132 | |
| 133 | as_where (&frag_now->fr_file, &frag_now->fr_line); |
| 134 | |
| 135 | /* Generally, frag_now->points to an address rounded up to next |
| 136 | alignment. However, characters will add to obstack frags |
| 137 | IMMEDIATELY after the struct frag, even if they are not starting |
| 138 | at an alignment address. */ |
| 139 | former_last_fragP->fr_next = frag_now; |
| 140 | frchP->frch_last = frag_now; |
| 141 | |
| 142 | #ifndef NO_LISTING |
| 143 | { |
| 144 | extern struct list_info_struct *listing_tail; |
| 145 | frag_now->line = listing_tail; |
| 146 | } |
| 147 | #endif |
| 148 | |
| 149 | assert (frchain_now->frch_last == frag_now); |
| 150 | |
| 151 | frag_now->fr_next = NULL; |
| 152 | } |
| 153 | \f |
| 154 | /* Start a new frag unless we have n more chars of room in the current frag. |
| 155 | Close off the old frag with a .fill 0. |
| 156 | |
| 157 | Return the address of the 1st char to write into. Advance |
| 158 | frag_now_growth past the new chars. */ |
| 159 | |
| 160 | char * |
| 161 | frag_more (nchars) |
| 162 | int nchars; |
| 163 | { |
| 164 | register char *retval; |
| 165 | |
| 166 | if (now_seg == absolute_section) |
| 167 | { |
| 168 | as_bad (_("attempt to allocate data in absolute section")); |
| 169 | subseg_set (text_section, 0); |
| 170 | } |
| 171 | |
| 172 | if (mri_common_symbol != NULL) |
| 173 | { |
| 174 | as_bad (_("attempt to allocate data in common section")); |
| 175 | mri_common_symbol = NULL; |
| 176 | } |
| 177 | |
| 178 | frag_grow (nchars); |
| 179 | retval = obstack_next_free (&frchain_now->frch_obstack); |
| 180 | obstack_blank_fast (&frchain_now->frch_obstack, nchars); |
| 181 | return (retval); |
| 182 | } |
| 183 | \f |
| 184 | /* Start a new frag unless we have max_chars more chars of room in the |
| 185 | current frag. Close off the old frag with a .fill 0. |
| 186 | |
| 187 | Set up a machine_dependent relaxable frag, then start a new frag. |
| 188 | Return the address of the 1st char of the var part of the old frag |
| 189 | to write into. */ |
| 190 | |
| 191 | char * |
| 192 | frag_var (type, max_chars, var, subtype, symbol, offset, opcode) |
| 193 | relax_stateT type; |
| 194 | int max_chars; |
| 195 | int var; |
| 196 | relax_substateT subtype; |
| 197 | symbolS *symbol; |
| 198 | offsetT offset; |
| 199 | char *opcode; |
| 200 | { |
| 201 | register char *retval; |
| 202 | |
| 203 | frag_grow (max_chars); |
| 204 | retval = obstack_next_free (&frchain_now->frch_obstack); |
| 205 | obstack_blank_fast (&frchain_now->frch_obstack, max_chars); |
| 206 | frag_now->fr_var = var; |
| 207 | frag_now->fr_type = type; |
| 208 | frag_now->fr_subtype = subtype; |
| 209 | frag_now->fr_symbol = symbol; |
| 210 | frag_now->fr_offset = offset; |
| 211 | frag_now->fr_opcode = opcode; |
| 212 | #ifdef USING_CGEN |
| 213 | frag_now->fr_cgen.insn = 0; |
| 214 | frag_now->fr_cgen.opindex = 0; |
| 215 | frag_now->fr_cgen.opinfo = 0; |
| 216 | #endif |
| 217 | #ifdef TC_FRAG_INIT |
| 218 | TC_FRAG_INIT (frag_now); |
| 219 | #endif |
| 220 | as_where (&frag_now->fr_file, &frag_now->fr_line); |
| 221 | frag_new (max_chars); |
| 222 | return (retval); |
| 223 | } |
| 224 | \f |
| 225 | /* OVE: This variant of frag_var assumes that space for the tail has been |
| 226 | allocated by caller. |
| 227 | No call to frag_grow is done. */ |
| 228 | |
| 229 | char * |
| 230 | frag_variant (type, max_chars, var, subtype, symbol, offset, opcode) |
| 231 | relax_stateT type; |
| 232 | int max_chars; |
| 233 | int var; |
| 234 | relax_substateT subtype; |
| 235 | symbolS *symbol; |
| 236 | offsetT offset; |
| 237 | char *opcode; |
| 238 | { |
| 239 | register char *retval; |
| 240 | |
| 241 | retval = obstack_next_free (&frchain_now->frch_obstack); |
| 242 | frag_now->fr_var = var; |
| 243 | frag_now->fr_type = type; |
| 244 | frag_now->fr_subtype = subtype; |
| 245 | frag_now->fr_symbol = symbol; |
| 246 | frag_now->fr_offset = offset; |
| 247 | frag_now->fr_opcode = opcode; |
| 248 | #ifdef USING_CGEN |
| 249 | frag_now->fr_cgen.insn = 0; |
| 250 | frag_now->fr_cgen.opindex = 0; |
| 251 | frag_now->fr_cgen.opinfo = 0; |
| 252 | #endif |
| 253 | #ifdef TC_FRAG_INIT |
| 254 | TC_FRAG_INIT (frag_now); |
| 255 | #endif |
| 256 | as_where (&frag_now->fr_file, &frag_now->fr_line); |
| 257 | frag_new (max_chars); |
| 258 | return (retval); |
| 259 | } |
| 260 | \f |
| 261 | /* Reduce the variable end of a frag to a harmless state. */ |
| 262 | |
| 263 | void |
| 264 | frag_wane (fragP) |
| 265 | register fragS *fragP; |
| 266 | { |
| 267 | fragP->fr_type = rs_fill; |
| 268 | fragP->fr_offset = 0; |
| 269 | fragP->fr_var = 0; |
| 270 | } |
| 271 | \f |
| 272 | /* Make an alignment frag. The size of this frag will be adjusted to |
| 273 | force the next frag to have the appropriate alignment. ALIGNMENT |
| 274 | is the power of two to which to align. FILL_CHARACTER is the |
| 275 | character to use to fill in any bytes which are skipped. MAX is |
| 276 | the maximum number of characters to skip when doing the alignment, |
| 277 | or 0 if there is no maximum. */ |
| 278 | |
| 279 | void |
| 280 | frag_align (alignment, fill_character, max) |
| 281 | int alignment; |
| 282 | int fill_character; |
| 283 | int max; |
| 284 | { |
| 285 | if (now_seg == absolute_section) |
| 286 | { |
| 287 | addressT new_off; |
| 288 | addressT mask; |
| 289 | |
| 290 | mask = (~(addressT) 0) << alignment; |
| 291 | new_off = (abs_section_offset + ~mask) & mask; |
| 292 | if (max == 0 || new_off - abs_section_offset <= (addressT) max) |
| 293 | abs_section_offset = new_off; |
| 294 | } |
| 295 | else |
| 296 | { |
| 297 | char *p; |
| 298 | |
| 299 | p = frag_var (rs_align, 1, 1, (relax_substateT) max, |
| 300 | (symbolS *) 0, (offsetT) alignment, (char *) 0); |
| 301 | *p = fill_character; |
| 302 | } |
| 303 | } |
| 304 | |
| 305 | /* Make an alignment frag like frag_align, but fill with a repeating |
| 306 | pattern rather than a single byte. ALIGNMENT is the power of two |
| 307 | to which to align. FILL_PATTERN is the fill pattern to repeat in |
| 308 | the bytes which are skipped. N_FILL is the number of bytes in |
| 309 | FILL_PATTERN. MAX is the maximum number of characters to skip when |
| 310 | doing the alignment, or 0 if there is no maximum. */ |
| 311 | |
| 312 | void |
| 313 | frag_align_pattern (alignment, fill_pattern, n_fill, max) |
| 314 | int alignment; |
| 315 | const char *fill_pattern; |
| 316 | int n_fill; |
| 317 | int max; |
| 318 | { |
| 319 | char *p; |
| 320 | |
| 321 | p = frag_var (rs_align, n_fill, n_fill, (relax_substateT) max, |
| 322 | (symbolS *) 0, (offsetT) alignment, (char *) 0); |
| 323 | memcpy (p, fill_pattern, n_fill); |
| 324 | } |
| 325 | |
| 326 | /* The NOP_OPCODE is for the alignment fill value. Fill it with a nop |
| 327 | instruction so that the disassembler does not choke on it. */ |
| 328 | #ifndef NOP_OPCODE |
| 329 | #define NOP_OPCODE 0x00 |
| 330 | #endif |
| 331 | |
| 332 | /* Use this to restrict the amount of memory allocated for representing |
| 333 | the alignment code. Needs to be large enough to hold any fixed sized |
| 334 | prologue plus the replicating portion. */ |
| 335 | #ifndef MAX_MEM_FOR_RS_ALIGN_CODE |
| 336 | /* Assume that if HANDLE_ALIGN is not defined then no special action |
| 337 | is required to code fill, which means that we get just repeat the |
| 338 | one NOP_OPCODE byte. */ |
| 339 | # ifndef HANDLE_ALIGN |
| 340 | # define MAX_MEM_FOR_RS_ALIGN_CODE 1 |
| 341 | # else |
| 342 | # define MAX_MEM_FOR_RS_ALIGN_CODE ((1 << alignment) - 1) |
| 343 | # endif |
| 344 | #endif |
| 345 | |
| 346 | void |
| 347 | frag_align_code (alignment, max) |
| 348 | int alignment; |
| 349 | int max; |
| 350 | { |
| 351 | char *p; |
| 352 | |
| 353 | p = frag_var (rs_align_code, MAX_MEM_FOR_RS_ALIGN_CODE, 1, |
| 354 | (relax_substateT) max, (symbolS *) 0, |
| 355 | (offsetT) alignment, (char *) 0); |
| 356 | *p = NOP_OPCODE; |
| 357 | } |
| 358 | |
| 359 | addressT |
| 360 | frag_now_fix_octets () |
| 361 | { |
| 362 | if (now_seg == absolute_section) |
| 363 | return abs_section_offset; |
| 364 | |
| 365 | return ((char *) obstack_next_free (&frchain_now->frch_obstack) |
| 366 | - frag_now->fr_literal); |
| 367 | } |
| 368 | |
| 369 | addressT |
| 370 | frag_now_fix () |
| 371 | { |
| 372 | return frag_now_fix_octets () / OCTETS_PER_BYTE; |
| 373 | } |
| 374 | |
| 375 | void |
| 376 | frag_append_1_char (datum) |
| 377 | int datum; |
| 378 | { |
| 379 | if (obstack_room (&frchain_now->frch_obstack) <= 1) |
| 380 | { |
| 381 | frag_wane (frag_now); |
| 382 | frag_new (0); |
| 383 | } |
| 384 | obstack_1grow (&frchain_now->frch_obstack, datum); |
| 385 | } |