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1 | /* GAS interface for targets using CGEN: Cpu tools GENerator. |
2 | Copyright (C) 1996, 1997 Free Software Foundation, Inc. | |
3 | ||
4 | This file is part of GAS, the GNU Assembler. | |
5 | ||
6 | GAS is free software; you can redistribute it and/or modify | |
7 | it under the terms of the GNU General Public License as published by | |
8 | the Free Software Foundation; either version 2, or (at your option) | |
9 | any later version. | |
10 | ||
11 | GAS is distributed in the hope that it will be useful, | |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | GNU General Public License for more details. | |
15 | ||
16 | You should have received a copy of the GNU General Public License | |
17 | along with GAS; see the file COPYING. If not, write to the Free Software | |
18 | Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ | |
19 | ||
20 | #include "ansidecl.h" | |
21 | #include "bfd.h" | |
22 | #include "cgen-opc.h" | |
23 | #include "as.h" | |
24 | #include "subsegs.h" | |
25 | ||
26 | /* Callback to insert a register into the symbol table. | |
27 | A target may choose to let GAS parse the registers. | |
28 | ??? Not currently used. */ | |
29 | ||
30 | void | |
31 | cgen_asm_record_register (name, number) | |
32 | char *name; | |
33 | int number; | |
34 | { | |
35 | /* Use symbol_create here instead of symbol_new so we don't try to | |
36 | output registers into the object file's symbol table. */ | |
37 | symbol_table_insert (symbol_create (name, reg_section, | |
38 | number, &zero_address_frag)); | |
39 | } | |
40 | ||
41 | /* We need to keep a list of fixups. We can't simply generate them as | |
42 | we go, because that would require us to first create the frag, and | |
43 | that would screw up references to ``.''. | |
44 | ||
45 | This is used by cpu's with simple operands. It keeps knowledge of what | |
46 | an `expressionS' is and what a `fixup' is out of CGEN which for the time | |
47 | being is preferable. | |
48 | ||
49 | OPINDEX is the index in the operand table. | |
50 | OPINFO is something the caller chooses to help in reloc determination. */ | |
51 | ||
52 | struct fixup | |
53 | { | |
54 | int opindex; | |
55 | int opinfo; | |
56 | expressionS exp; | |
57 | }; | |
58 | ||
59 | #define MAX_FIXUPS 5 | |
60 | ||
61 | static struct fixup fixups[MAX_FIXUPS]; | |
62 | static int num_fixups; | |
63 | ||
64 | void | |
65 | cgen_asm_init_parse () | |
66 | { | |
67 | num_fixups = 0; | |
68 | } | |
69 | ||
70 | /* Queue a fixup. */ | |
71 | ||
72 | void | |
73 | cgen_queue_fixup (opindex, opinfo, expP) | |
74 | int opindex; | |
75 | expressionS *expP; | |
76 | { | |
77 | /* We need to generate a fixup for this expression. */ | |
78 | if (num_fixups >= MAX_FIXUPS) | |
79 | as_fatal ("too many fixups"); | |
80 | fixups[num_fixups].exp = *expP; | |
81 | fixups[num_fixups].opindex = opindex; | |
82 | fixups[num_fixups].opinfo = opinfo; | |
83 | ++num_fixups; | |
84 | } | |
85 | ||
86 | /* Default routine to record a fixup. | |
87 | This is a cover function to fix_new. | |
88 | It exists because we record INSN with the fixup. | |
89 | ||
90 | FRAG and WHERE are their respective arguments to fix_new_exp. | |
91 | LENGTH is in bits. | |
92 | OPINFO is something the caller chooses to help in reloc determination. | |
93 | ||
94 | At this point we do not use a bfd_reloc_code_real_type for | |
95 | operands residing in the insn, but instead just use the | |
96 | operand index. This lets us easily handle fixups for any | |
97 | operand type. We pick a BFD reloc type in md_apply_fix. */ | |
98 | ||
99 | fixS * | |
100 | cgen_record_fixup (frag, where, insn, length, operand, opinfo, symbol, offset) | |
101 | fragS *frag; | |
102 | int where; | |
103 | const struct cgen_insn *insn; | |
104 | int length; | |
105 | const struct cgen_operand *operand; | |
106 | int opinfo; | |
107 | symbolS *symbol; | |
108 | offsetT offset; | |
109 | { | |
110 | fixS *fixP; | |
111 | ||
112 | /* It may seem strange to use operand->attrs and not insn->attrs here, | |
113 | but it is the operand that has a pc relative relocation. */ | |
114 | ||
115 | fixP = fix_new (frag, where, length / 8, symbol, offset, | |
116 | CGEN_OPERAND_ATTR (operand, CGEN_OPERAND_PCREL_ADDR) != 0, | |
117 | (bfd_reloc_code_real_type) ((int) BFD_RELOC_UNUSED + CGEN_OPERAND_INDEX (operand))); | |
118 | fixP->tc_fix_data.insn = (PTR) insn; | |
119 | fixP->tc_fix_data.opinfo = opinfo; | |
120 | ||
121 | return fixP; | |
122 | } | |
123 | ||
124 | /* Default routine to record a fixup given an expression. | |
125 | This is a cover function to fix_new_exp. | |
126 | It exists because we record INSN with the fixup. | |
127 | ||
128 | FRAG and WHERE are their respective arguments to fix_new_exp. | |
129 | LENGTH is in bits. | |
130 | OPINFO is something the caller chooses to help in reloc determination. | |
131 | ||
132 | At this point we do not use a bfd_reloc_code_real_type for | |
133 | operands residing in the insn, but instead just use the | |
134 | operand index. This lets us easily handle fixups for any | |
135 | operand type. We pick a BFD reloc type in md_apply_fix. */ | |
136 | ||
137 | fixS * | |
138 | cgen_record_fixup_exp (frag, where, insn, length, operand, opinfo, exp) | |
139 | fragS *frag; | |
140 | int where; | |
141 | const struct cgen_insn *insn; | |
142 | int length; | |
143 | const struct cgen_operand *operand; | |
144 | int opinfo; | |
145 | expressionS *exp; | |
146 | { | |
147 | fixS *fixP; | |
148 | ||
149 | /* It may seem strange to use operand->attrs and not insn->attrs here, | |
150 | but it is the operand that has a pc relative relocation. */ | |
151 | ||
152 | fixP = fix_new_exp (frag, where, length / 8, exp, | |
153 | CGEN_OPERAND_ATTR (operand, CGEN_OPERAND_PCREL_ADDR) != 0, | |
154 | (bfd_reloc_code_real_type) ((int) BFD_RELOC_UNUSED + CGEN_OPERAND_INDEX (operand))); | |
155 | fixP->tc_fix_data.insn = (PTR) insn; | |
156 | fixP->tc_fix_data.opinfo = opinfo; | |
157 | ||
158 | return fixP; | |
159 | } | |
160 | ||
161 | /* Callback for cgen interface. Parse the expression at *STRP. | |
162 | The result is an error message or NULL for success (in which case | |
163 | *STRP is advanced past the parsed text). | |
164 | An enum cgen_asm_result is stored in RESULTP. | |
165 | OPINFO is something the caller chooses to help in reloc determination. | |
166 | The resulting value is stored in VALUEP. */ | |
167 | ||
168 | const char * | |
169 | cgen_asm_parse_operand (strP, opindex, opinfo, resultP, valueP) | |
170 | const char **strP; | |
171 | int opindex; | |
172 | int opinfo; | |
173 | enum cgen_asm_result *resultP; | |
174 | bfd_vma *valueP; | |
175 | { | |
176 | char *hold; | |
177 | const char *errmsg = NULL; | |
178 | expressionS exp; | |
179 | ||
180 | hold = input_line_pointer; | |
181 | input_line_pointer = (char *) *strP; | |
182 | expression (&exp); | |
183 | *strP = input_line_pointer; | |
184 | input_line_pointer = hold; | |
185 | ||
186 | switch (exp.X_op) | |
187 | { | |
188 | case O_illegal : | |
189 | errmsg = "illegal operand"; | |
190 | *resultP = CGEN_ASM_ERROR; | |
191 | break; | |
192 | case O_absent : | |
193 | errmsg = "missing operand"; | |
194 | *resultP = CGEN_ASM_ERROR; | |
195 | break; | |
196 | case O_constant : | |
197 | *valueP = exp.X_add_number; | |
198 | *resultP = CGEN_ASM_NUMBER; | |
199 | break; | |
200 | case O_register : | |
201 | *valueP = exp.X_add_number; | |
202 | *resultP = CGEN_ASM_REGISTER; | |
203 | break; | |
204 | default : | |
205 | cgen_queue_fixup (opindex, opinfo, &exp); | |
206 | *valueP = 0; | |
207 | *resultP = CGEN_ASM_QUEUED; | |
208 | break; | |
209 | } | |
210 | ||
211 | return errmsg; | |
212 | } | |
213 | ||
214 | /* Finish assembling instruction INSN. | |
215 | BUF contains what we've built up so far. | |
216 | LENGTH is the size of the insn in bits. */ | |
217 | ||
218 | void | |
219 | cgen_asm_finish_insn (insn, buf, length) | |
220 | const struct cgen_insn *insn; | |
221 | cgen_insn_t *buf; | |
222 | unsigned int length; | |
223 | { | |
224 | int i, relax_operand; | |
225 | char *f; | |
226 | unsigned int byte_len = length / 8; | |
227 | ||
228 | /* ??? Target foo issues various warnings here, so one might want to provide | |
229 | a hook here. However, our caller is defined in tc-foo.c so there | |
230 | shouldn't be a need for a hook. */ | |
231 | ||
232 | /* Write out the instruction. | |
233 | It is important to fetch enough space in one call to `frag_more'. | |
234 | We use (f - frag_now->fr_literal) to compute where we are and we | |
235 | don't want frag_now to change between calls. | |
236 | ||
237 | Relaxable instructions: We need to ensure we allocate enough | |
238 | space for the largest insn. */ | |
239 | ||
240 | if (CGEN_INSN_ATTR (insn, CGEN_INSN_RELAX) != 0) | |
241 | abort (); /* These currently shouldn't get here. */ | |
242 | ||
243 | /* Is there a relaxable insn with the relaxable operand needing a fixup? */ | |
244 | ||
245 | relax_operand = -1; | |
246 | if (CGEN_INSN_ATTR (insn, CGEN_INSN_RELAXABLE) != 0) | |
247 | { | |
248 | /* Scan the fixups for the operand affected by relaxing | |
249 | (i.e. the branch address). */ | |
250 | ||
251 | for (i = 0; i < num_fixups; ++i) | |
252 | { | |
253 | if (CGEN_OPERAND_ATTR (& CGEN_SYM (operand_table) [fixups[i].opindex], | |
254 | CGEN_OPERAND_RELAX) != 0) | |
255 | { | |
256 | relax_operand = i; | |
257 | break; | |
258 | } | |
259 | } | |
260 | } | |
261 | ||
262 | if (relax_operand != -1) | |
263 | { | |
264 | int max_len; | |
265 | fragS *old_frag; | |
266 | ||
267 | #ifdef TC_CGEN_MAX_RELAX | |
268 | max_len = TC_CGEN_MAX_RELAX (insn, byte_len); | |
269 | #else | |
270 | max_len = CGEN_MAX_INSN_SIZE; | |
271 | #endif | |
272 | /* Ensure variable part and fixed part are in same fragment. */ | |
273 | /* FIXME: Having to do this seems like a hack. */ | |
274 | frag_grow (max_len); | |
275 | /* Allocate space for the fixed part. */ | |
276 | f = frag_more (byte_len); | |
277 | /* Create a relaxable fragment for this instruction. */ | |
278 | old_frag = frag_now; | |
279 | frag_var (rs_machine_dependent, | |
280 | max_len - byte_len /* max chars */, | |
281 | 0 /* variable part already allocated */, | |
282 | /* FIXME: When we machine generate the relax table, | |
283 | machine generate a macro to compute subtype. */ | |
284 | 1 /* subtype */, | |
285 | fixups[relax_operand].exp.X_add_symbol, | |
286 | fixups[relax_operand].exp.X_add_number, | |
287 | f); | |
288 | /* Record the operand number with the fragment so md_convert_frag | |
289 | can use cgen_md_record_fixup to record the appropriate reloc. */ | |
290 | /* FIXME: fr_targ.cgen is used pending deciding whether to | |
291 | allow a target to add members to fragS. For more info | |
292 | see the comment above fr_targ in as.h. */ | |
293 | old_frag->fr_targ.cgen.insn = insn; | |
294 | old_frag->fr_targ.cgen.opindex = fixups[relax_operand].opindex; | |
295 | old_frag->fr_targ.cgen.opinfo = fixups[relax_operand].opinfo; | |
296 | } | |
297 | else | |
298 | f = frag_more (byte_len); | |
299 | ||
300 | /* If we're recording insns as numbers (rather than a string of bytes), | |
301 | target byte order handling is deferred until now. */ | |
302 | #if 0 /*def CGEN_INT_INSN*/ | |
303 | switch (length) | |
304 | { | |
305 | case 16: | |
306 | if (cgen_big_endian_p) | |
307 | bfd_putb16 ((bfd_vma) *buf, f); | |
308 | else | |
309 | bfd_putl16 ((bfd_vma) *buf, f); | |
310 | break; | |
311 | case 32: | |
312 | if (cgen_big_endian_p) | |
313 | bfd_putb32 ((bfd_vma) *buf, f); | |
314 | else | |
315 | bfd_putl32 ((bfd_vma) *buf, f); | |
316 | break; | |
317 | default: | |
318 | abort (); | |
319 | } | |
320 | #else | |
321 | memcpy (f, buf, byte_len); | |
322 | #endif | |
323 | ||
324 | /* Create any fixups. */ | |
325 | for (i = 0; i < num_fixups; ++i) | |
326 | { | |
327 | /* Don't create fixups for these. That's done during relaxation. | |
328 | We don't need to test for CGEN_INSN_RELAX as they can't get here | |
329 | (see above). */ | |
330 | if (CGEN_INSN_ATTR (insn, CGEN_INSN_RELAXABLE) != 0 | |
331 | && CGEN_OPERAND_ATTR (& CGEN_SYM (operand_table) [fixups[i].opindex], | |
332 | CGEN_OPERAND_RELAX) != 0) | |
333 | continue; | |
334 | ||
335 | #ifndef md_cgen_record_fixup_exp | |
336 | #define md_cgen_record_fixup_exp cgen_record_fixup_exp | |
337 | #endif | |
338 | ||
339 | md_cgen_record_fixup_exp (frag_now, f - frag_now->fr_literal, | |
340 | insn, length, | |
341 | & CGEN_SYM (operand_table) [fixups[i].opindex], | |
342 | fixups[i].opinfo, | |
343 | &fixups[i].exp); | |
344 | } | |
345 | } | |
346 | ||
347 | /* Apply a fixup to the object code. This is called for all the | |
348 | fixups we generated by the call to fix_new_exp, above. In the call | |
349 | above we used a reloc code which was the largest legal reloc code | |
350 | plus the operand index. Here we undo that to recover the operand | |
351 | index. At this point all symbol values should be fully resolved, | |
352 | and we attempt to completely resolve the reloc. If we can not do | |
353 | that, we determine the correct reloc code and put it back in the fixup. */ | |
354 | ||
355 | /* FIXME: This function handles some of the fixups and bfd_install_relocation | |
356 | handles the rest. bfd_install_relocation (or some other bfd function) | |
357 | should handle them all. */ | |
358 | ||
359 | int | |
360 | cgen_md_apply_fix3 (fixP, valueP, seg) | |
361 | fixS *fixP; | |
362 | valueT *valueP; | |
363 | segT seg; | |
364 | { | |
365 | char *where = fixP->fx_frag->fr_literal + fixP->fx_where; | |
366 | valueT value; | |
367 | ||
368 | /* FIXME FIXME FIXME: The value we are passed in *valuep includes | |
369 | the symbol values. Since we are using BFD_ASSEMBLER, if we are | |
370 | doing this relocation the code in write.c is going to call | |
371 | bfd_install_relocation, which is also going to use the symbol | |
372 | value. That means that if the reloc is fully resolved we want to | |
373 | use *valuep since bfd_install_relocation is not being used. | |
374 | However, if the reloc is not fully resolved we do not want to use | |
375 | *valuep, and must use fx_offset instead. However, if the reloc | |
376 | is PC relative, we do want to use *valuep since it includes the | |
377 | result of md_pcrel_from. This is confusing. */ | |
378 | ||
379 | if (fixP->fx_addsy == (symbolS *) NULL) | |
380 | { | |
381 | value = *valueP; | |
382 | fixP->fx_done = 1; | |
383 | } | |
384 | else if (fixP->fx_pcrel) | |
385 | value = *valueP; | |
386 | else | |
387 | { | |
388 | value = fixP->fx_offset; | |
389 | if (fixP->fx_subsy != (symbolS *) NULL) | |
390 | { | |
391 | if (S_GET_SEGMENT (fixP->fx_subsy) == absolute_section) | |
392 | value -= S_GET_VALUE (fixP->fx_subsy); | |
393 | else | |
394 | { | |
395 | /* We don't actually support subtracting a symbol. */ | |
396 | as_bad_where (fixP->fx_file, fixP->fx_line, | |
397 | "expression too complex"); | |
398 | } | |
399 | } | |
400 | } | |
401 | ||
402 | if ((int) fixP->fx_r_type >= (int) BFD_RELOC_UNUSED) | |
403 | { | |
404 | int opindex = (int) fixP->fx_r_type - (int) BFD_RELOC_UNUSED; | |
405 | const struct cgen_operand *operand = & CGEN_SYM (operand_table) [opindex]; | |
406 | const char *errmsg; | |
407 | bfd_reloc_code_real_type reloc_type; | |
408 | struct cgen_fields fields; | |
409 | const struct cgen_insn *insn = (struct cgen_insn *) fixP->tc_fix_data.insn; | |
410 | ||
411 | /* If the reloc has been fully resolved finish the operand here. */ | |
412 | /* FIXME: This duplicates the capabilities of code in BFD. */ | |
413 | if (fixP->fx_done | |
414 | /* FIXME: If partial_inplace isn't set bfd_install_relocation won't | |
415 | finish the job. Testing for pcrel is a temporary hack. */ | |
416 | || fixP->fx_pcrel) | |
417 | { | |
418 | /* This may seem like overkill, and using bfd_install_relocation or | |
419 | some such may be preferable, but this is simple. */ | |
420 | CGEN_FIELDS_BITSIZE (&fields) = CGEN_INSN_BITSIZE (insn); | |
421 | CGEN_SYM (set_operand) (opindex, &value, &fields); | |
422 | errmsg = CGEN_SYM (validate_operand) (opindex, &fields); | |
423 | if (errmsg) | |
424 | as_warn_where (fixP->fx_file, fixP->fx_line, "%s\n", errmsg); | |
425 | CGEN_SYM (insert_operand) (opindex, &fields, where); | |
426 | } | |
427 | ||
428 | if (fixP->fx_done) | |
429 | return 1; | |
430 | ||
431 | /* The operand isn't fully resolved. Determine a BFD reloc value | |
432 | based on the operand information and leave it to | |
433 | bfd_install_relocation. Note that this doesn't work when | |
434 | partial_inplace == false. */ | |
435 | ||
436 | reloc_type = CGEN_SYM (lookup_reloc) (insn, operand, fixP); | |
437 | if (reloc_type != BFD_RELOC_NONE) | |
438 | { | |
439 | fixP->fx_r_type = reloc_type; | |
440 | } | |
441 | else | |
442 | { | |
443 | as_bad_where (fixP->fx_file, fixP->fx_line, | |
444 | "unresolved expression that must be resolved"); | |
445 | fixP->fx_done = 1; | |
446 | return 1; | |
447 | } | |
448 | } | |
449 | else if (fixP->fx_done) | |
450 | { | |
451 | /* We're finished with this fixup. Install it because | |
452 | bfd_install_relocation won't be called to do it. */ | |
453 | switch (fixP->fx_r_type) | |
454 | { | |
455 | case BFD_RELOC_8: | |
456 | md_number_to_chars (where, value, 1); | |
457 | break; | |
458 | case BFD_RELOC_16: | |
459 | md_number_to_chars (where, value, 2); | |
460 | break; | |
461 | case BFD_RELOC_32: | |
462 | md_number_to_chars (where, value, 4); | |
463 | break; | |
464 | /* FIXME: later add support for 64 bits. */ | |
465 | default: | |
466 | abort (); | |
467 | } | |
468 | } | |
469 | else | |
470 | { | |
471 | /* bfd_install_relocation will be called to finish things up. */ | |
472 | } | |
473 | ||
474 | /* Tuck `value' away for use by tc_gen_reloc. | |
475 | See the comment describing fx_addnumber in write.h. | |
476 | This field is misnamed (or misused :-). */ | |
477 | fixP->fx_addnumber = value; | |
478 | ||
479 | return 1; | |
480 | } | |
481 | ||
482 | /* Translate internal representation of relocation info to BFD target format. | |
483 | ||
484 | FIXME: To what extent can we get all relevant targets to use this? */ | |
485 | ||
486 | arelent * | |
487 | cgen_tc_gen_reloc (section, fixP) | |
488 | asection *section; | |
489 | fixS *fixP; | |
490 | { | |
491 | arelent *reloc; | |
492 | ||
493 | reloc = (arelent *) bfd_alloc_by_size_t (stdoutput, sizeof (arelent)); | |
494 | ||
495 | reloc->howto = bfd_reloc_type_lookup (stdoutput, fixP->fx_r_type); | |
496 | if (reloc->howto == (reloc_howto_type *) NULL) | |
497 | { | |
498 | as_bad_where (fixP->fx_file, fixP->fx_line, | |
499 | "internal error: can't export reloc type %d (`%s')", | |
500 | fixP->fx_r_type, bfd_get_reloc_code_name (fixP->fx_r_type)); | |
501 | return NULL; | |
502 | } | |
503 | ||
504 | assert (!fixP->fx_pcrel == !reloc->howto->pc_relative); | |
505 | ||
506 | reloc->sym_ptr_ptr = &fixP->fx_addsy->bsym; | |
507 | reloc->address = fixP->fx_frag->fr_address + fixP->fx_where; | |
508 | reloc->addend = fixP->fx_addnumber; | |
509 | ||
510 | return reloc; | |
511 | } |