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64e81171 WJ |
1 | /* Find a variable's value in memory, for GDB, the GNU debugger. |
2 | Copyright (C) 1986, 1987, 1989 Free Software Foundation, Inc. | |
3 | ||
4 | This file is part of GDB. | |
5 | ||
6 | GDB 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 1, or (at your option) | |
9 | any later version. | |
10 | ||
11 | GDB 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 GDB; see the file COPYING. If not, write to | |
18 | the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */ | |
19 | ||
20 | #include "defs.h" | |
21 | #include "param.h" | |
22 | #include "symtab.h" | |
23 | #include "frame.h" | |
24 | #include "value.h" | |
25 | ||
26 | CORE_ADDR read_register (); | |
27 | ||
28 | /* Return the address in which frame FRAME's value of register REGNUM | |
29 | has been saved in memory. Or return zero if it has not been saved. | |
30 | If REGNUM specifies the SP, the value we return is actually | |
31 | the SP value, not an address where it was saved. */ | |
32 | ||
33 | CORE_ADDR | |
34 | find_saved_register (frame, regnum) | |
35 | FRAME frame; | |
36 | int regnum; | |
37 | { | |
38 | struct frame_info *fi; | |
39 | struct frame_saved_regs saved_regs; | |
40 | ||
41 | register FRAME frame1 = 0; | |
42 | register CORE_ADDR addr = 0; | |
43 | ||
44 | #ifdef HAVE_REGISTER_WINDOWS | |
45 | /* We assume that a register in a register window will only be saved | |
46 | in one place (since the name changes and disappears as you go | |
47 | towards inner frames), so we only call get_frame_saved_regs on | |
48 | the current frame. This is directly in contradiction to the | |
49 | usage below, which assumes that registers used in a frame must be | |
50 | saved in a lower (more interior) frame. This change is a result | |
51 | of working on a register window machine; get_frame_saved_regs | |
52 | always returns the registers saved within a frame, within the | |
53 | context (register namespace) of that frame. */ | |
54 | ||
55 | /* However, note that we don't want this to return anything if | |
56 | nothing is saved (if there's a frame inside of this one). Also, | |
57 | callers to this routine asking for the stack pointer want the | |
58 | stack pointer saved for *this* frame; this is returned from the | |
59 | next frame. */ | |
60 | ||
61 | ||
62 | if (REGISTER_IN_WINDOW_P(regnum)) | |
63 | { | |
64 | frame1 = get_next_frame (frame); | |
65 | if (!frame1) return 0; /* Registers of this frame are | |
66 | active. */ | |
67 | ||
68 | /* Get the SP from the next frame in; it will be this | |
69 | current frame. */ | |
70 | if (regnum != SP_REGNUM) | |
71 | frame1 = frame; | |
72 | ||
73 | fi = get_frame_info (frame1); | |
74 | get_frame_saved_regs (fi, &saved_regs); | |
75 | return (saved_regs.regs[regnum] ? | |
76 | saved_regs.regs[regnum] : 0); | |
77 | } | |
78 | #endif /* HAVE_REGISTER_WINDOWS */ | |
79 | ||
80 | /* Note that this next routine assumes that registers used in | |
81 | frame x will be saved only in the frame that x calls and | |
82 | frames interior to it. This is not true on the sparc, but the | |
83 | above macro takes care of it, so we should be all right. */ | |
84 | while (1) | |
85 | { | |
86 | QUIT; | |
87 | frame1 = get_prev_frame (frame1); | |
88 | if (frame1 == 0 || frame1 == frame) | |
89 | break; | |
90 | fi = get_frame_info (frame1); | |
91 | get_frame_saved_regs (fi, &saved_regs); | |
92 | if (saved_regs.regs[regnum]) | |
93 | addr = saved_regs.regs[regnum]; | |
94 | } | |
95 | ||
96 | return addr; | |
97 | } | |
98 | ||
99 | /* Copy the bytes of register REGNUM, relative to the current stack frame, | |
100 | into our memory at MYADDR. | |
101 | The number of bytes copied is REGISTER_RAW_SIZE (REGNUM). */ | |
102 | ||
103 | void | |
104 | read_relative_register_raw_bytes (regnum, myaddr) | |
105 | int regnum; | |
106 | char *myaddr; | |
107 | { | |
108 | register CORE_ADDR addr; | |
109 | ||
110 | if (regnum == FP_REGNUM) | |
111 | { | |
112 | bcopy (&FRAME_FP(selected_frame), myaddr, sizeof (CORE_ADDR)); | |
113 | return; | |
114 | } | |
115 | ||
116 | addr = find_saved_register (selected_frame, regnum); | |
117 | ||
118 | if (addr) | |
119 | { | |
120 | if (regnum == SP_REGNUM) | |
121 | { | |
122 | CORE_ADDR buffer = addr; | |
123 | bcopy (&buffer, myaddr, sizeof (CORE_ADDR)); | |
124 | } | |
125 | else | |
126 | read_memory (addr, myaddr, REGISTER_RAW_SIZE (regnum)); | |
127 | return; | |
128 | } | |
129 | read_register_bytes (REGISTER_BYTE (regnum), | |
130 | myaddr, REGISTER_RAW_SIZE (regnum)); | |
131 | } | |
132 | ||
133 | /* Return a `value' with the contents of register REGNUM | |
134 | in its virtual format, with the type specified by | |
135 | REGISTER_VIRTUAL_TYPE. */ | |
136 | ||
137 | value | |
138 | value_of_register (regnum) | |
139 | int regnum; | |
140 | { | |
141 | register CORE_ADDR addr; | |
142 | register value val; | |
143 | char raw_buffer[MAX_REGISTER_RAW_SIZE]; | |
144 | char virtual_buffer[MAX_REGISTER_VIRTUAL_SIZE]; | |
145 | ||
146 | if (! (have_inferior_p () || have_core_file_p ())) | |
147 | error ("Can't get value of register without inferior or core file"); | |
148 | ||
149 | addr = find_saved_register (selected_frame, regnum); | |
150 | if (addr) | |
151 | { | |
152 | if (regnum == SP_REGNUM) | |
153 | return value_from_long (builtin_type_int, (LONGEST) addr); | |
154 | read_memory (addr, raw_buffer, REGISTER_RAW_SIZE (regnum)); | |
155 | } | |
156 | else | |
157 | read_register_bytes (REGISTER_BYTE (regnum), raw_buffer, | |
158 | REGISTER_RAW_SIZE (regnum)); | |
159 | ||
160 | REGISTER_CONVERT_TO_VIRTUAL (regnum, raw_buffer, virtual_buffer); | |
161 | val = allocate_value (REGISTER_VIRTUAL_TYPE (regnum)); | |
162 | bcopy (virtual_buffer, VALUE_CONTENTS (val), REGISTER_VIRTUAL_SIZE (regnum)); | |
163 | VALUE_LVAL (val) = addr ? lval_memory : lval_register; | |
164 | VALUE_ADDRESS (val) = addr ? addr : REGISTER_BYTE (regnum); | |
165 | VALUE_REGNO (val) = regnum; | |
166 | return val; | |
167 | } | |
168 | \f | |
169 | /* Low level examining and depositing of registers. | |
170 | ||
171 | Note that you must call `fetch_registers' once | |
172 | before examining or depositing any registers. */ | |
173 | ||
174 | char registers[REGISTER_BYTES]; | |
175 | ||
176 | /* Copy LEN bytes of consecutive data from registers | |
177 | starting with the REGBYTE'th byte of register data | |
178 | into memory at MYADDR. */ | |
179 | ||
180 | void | |
181 | read_register_bytes (regbyte, myaddr, len) | |
182 | int regbyte; | |
183 | char *myaddr; | |
184 | int len; | |
185 | { | |
186 | bcopy (®isters[regbyte], myaddr, len); | |
187 | } | |
188 | ||
189 | /* Copy LEN bytes of consecutive data from memory at MYADDR | |
190 | into registers starting with the REGBYTE'th byte of register data. */ | |
191 | ||
192 | void | |
193 | write_register_bytes (regbyte, myaddr, len) | |
194 | int regbyte; | |
195 | char *myaddr; | |
196 | int len; | |
197 | { | |
198 | bcopy (myaddr, ®isters[regbyte], len); | |
199 | if (have_inferior_p ()) | |
200 | store_inferior_registers (-1); | |
201 | } | |
202 | ||
203 | /* Return the contents of register REGNO, | |
204 | regarding it as an integer. */ | |
205 | ||
206 | CORE_ADDR | |
207 | read_register (regno) | |
208 | int regno; | |
209 | { | |
210 | /* This loses when REGISTER_RAW_SIZE (regno) != sizeof (int) */ | |
211 | return *(int *) ®isters[REGISTER_BYTE (regno)]; | |
212 | } | |
213 | ||
214 | /* Store VALUE in the register number REGNO, regarded as an integer. */ | |
215 | ||
216 | void | |
217 | write_register (regno, val) | |
218 | int regno, val; | |
219 | { | |
220 | /* This loses when REGISTER_RAW_SIZE (regno) != sizeof (int) */ | |
221 | #if defined(sun4) | |
222 | /* This is a no-op on a Sun 4. */ | |
223 | if (regno == 0) | |
224 | return; | |
225 | #endif | |
226 | ||
227 | *(int *) ®isters[REGISTER_BYTE (regno)] = val; | |
228 | ||
229 | if (have_inferior_p ()) | |
230 | store_inferior_registers (regno); | |
231 | } | |
232 | ||
233 | /* Record that register REGNO contains VAL. | |
234 | This is used when the value is obtained from the inferior or core dump, | |
235 | so there is no need to store the value there. */ | |
236 | ||
237 | void | |
238 | supply_register (regno, val) | |
239 | int regno; | |
240 | char *val; | |
241 | { | |
242 | bcopy (val, ®isters[REGISTER_BYTE (regno)], REGISTER_RAW_SIZE (regno)); | |
243 | } | |
244 | \f | |
245 | /* Given a struct symbol for a variable, | |
246 | and a stack frame id, read the value of the variable | |
247 | and return a (pointer to a) struct value containing the value. */ | |
248 | ||
249 | value | |
250 | read_var_value (var, frame) | |
251 | register struct symbol *var; | |
252 | FRAME frame; | |
253 | { | |
254 | register value v; | |
255 | ||
256 | struct frame_info *fi; | |
257 | ||
258 | struct type *type = SYMBOL_TYPE (var); | |
259 | register CORE_ADDR addr = 0; | |
260 | int val = SYMBOL_VALUE (var); | |
261 | register int len; | |
262 | ||
263 | v = allocate_value (type); | |
264 | VALUE_LVAL (v) = lval_memory; /* The most likely possibility. */ | |
265 | len = TYPE_LENGTH (type); | |
266 | ||
267 | if (frame == 0) frame = selected_frame; | |
268 | ||
269 | switch (SYMBOL_CLASS (var)) | |
270 | { | |
271 | case LOC_CONST: | |
272 | case LOC_LABEL: | |
273 | bcopy (&val, VALUE_CONTENTS (v), len); | |
274 | VALUE_LVAL (v) = not_lval; | |
275 | return v; | |
276 | ||
277 | case LOC_CONST_BYTES: | |
278 | bcopy (val, VALUE_CONTENTS (v), len); | |
279 | VALUE_LVAL (v) = not_lval; | |
280 | return v; | |
281 | ||
282 | case LOC_STATIC: | |
283 | addr = val; | |
284 | break; | |
285 | ||
286 | /* Nonzero if a struct which is located in a register or a LOC_ARG | |
287 | really contains | |
288 | the address of the struct, not the struct itself. GCC_P is nonzero | |
289 | if the function was compiled with GCC. */ | |
290 | #if !defined (REG_STRUCT_HAS_ADDR) | |
291 | #define REG_STRUCT_HAS_ADDR(gcc_p) 0 | |
292 | #endif | |
293 | ||
294 | case LOC_ARG: | |
295 | fi = get_frame_info (frame); | |
296 | addr = val + FRAME_ARGS_ADDRESS (fi); | |
297 | break; | |
298 | ||
299 | case LOC_REF_ARG: | |
300 | fi = get_frame_info (frame); | |
301 | addr = val + FRAME_ARGS_ADDRESS (fi); | |
302 | addr = read_memory_integer (addr, sizeof (CORE_ADDR)); | |
303 | break; | |
304 | ||
305 | case LOC_LOCAL: | |
306 | fi = get_frame_info (frame); | |
307 | addr = val + FRAME_LOCALS_ADDRESS (fi); | |
308 | break; | |
309 | ||
310 | case LOC_TYPEDEF: | |
311 | error ("Cannot look up value of a typedef"); | |
312 | ||
313 | case LOC_BLOCK: | |
314 | VALUE_ADDRESS (v) = BLOCK_START (SYMBOL_BLOCK_VALUE (var)); | |
315 | return v; | |
316 | ||
317 | case LOC_REGISTER: | |
318 | case LOC_REGPARM: | |
319 | { | |
320 | struct block *b = get_frame_block (frame); | |
321 | ||
322 | v = value_from_register (type, val, frame); | |
323 | ||
324 | if (REG_STRUCT_HAS_ADDR(b->gcc_compile_flag) | |
325 | && TYPE_CODE (type) == TYPE_CODE_STRUCT) | |
326 | addr = *(CORE_ADDR *)VALUE_CONTENTS (v); | |
327 | else | |
328 | return v; | |
329 | } | |
330 | } | |
331 | ||
332 | read_memory (addr, VALUE_CONTENTS (v), len); | |
333 | VALUE_ADDRESS (v) = addr; | |
334 | return v; | |
335 | } | |
336 | ||
337 | /* Return a value of type TYPE, stored in register REGNUM, in frame | |
338 | FRAME. */ | |
339 | ||
340 | value | |
341 | value_from_register (type, regnum, frame) | |
342 | struct type *type; | |
343 | int regnum; | |
344 | FRAME frame; | |
345 | { | |
346 | char raw_buffer [MAX_REGISTER_RAW_SIZE]; | |
347 | char virtual_buffer[MAX_REGISTER_VIRTUAL_SIZE]; | |
348 | CORE_ADDR addr; | |
349 | value v = allocate_value (type); | |
350 | int len = TYPE_LENGTH (type); | |
351 | char *value_bytes = 0; | |
352 | int value_bytes_copied = 0; | |
353 | int num_storage_locs; | |
354 | ||
355 | VALUE_REGNO (v) = regnum; | |
356 | ||
357 | num_storage_locs = (len > REGISTER_VIRTUAL_SIZE (regnum) ? | |
358 | ((len - 1) / REGISTER_RAW_SIZE (regnum)) + 1 : | |
359 | 1); | |
360 | ||
361 | if (num_storage_locs > 1) | |
362 | { | |
363 | /* Value spread across multiple storage locations. */ | |
364 | ||
365 | int local_regnum; | |
366 | int mem_stor = 0, reg_stor = 0; | |
367 | int mem_tracking = 1; | |
368 | CORE_ADDR last_addr = 0; | |
369 | ||
370 | value_bytes = (char *) alloca (len + MAX_REGISTER_RAW_SIZE); | |
371 | ||
372 | /* Copy all of the data out, whereever it may be. */ | |
373 | ||
374 | for (local_regnum = regnum; | |
375 | value_bytes_copied < len; | |
376 | (value_bytes_copied += REGISTER_RAW_SIZE (local_regnum), | |
377 | ++local_regnum)) | |
378 | { | |
379 | int register_index = local_regnum - regnum; | |
380 | addr = find_saved_register (frame, local_regnum); | |
381 | if (addr == 0) | |
382 | { | |
383 | read_register_bytes (REGISTER_BYTE (local_regnum), | |
384 | value_bytes + value_bytes_copied, | |
385 | REGISTER_RAW_SIZE (local_regnum)); | |
386 | reg_stor++; | |
387 | } | |
388 | else | |
389 | { | |
390 | read_memory (addr, value_bytes + value_bytes_copied, | |
391 | REGISTER_RAW_SIZE (local_regnum)); | |
392 | mem_stor++; | |
393 | mem_tracking = | |
394 | (mem_tracking | |
395 | && (regnum == local_regnum | |
396 | || addr == last_addr)); | |
397 | } | |
398 | last_addr = addr; | |
399 | } | |
400 | ||
401 | if ((reg_stor && mem_stor) | |
402 | || (mem_stor && !mem_tracking)) | |
403 | /* Mixed storage; all of the hassle we just went through was | |
404 | for some good purpose. */ | |
405 | { | |
406 | VALUE_LVAL (v) = lval_reg_frame_relative; | |
407 | VALUE_FRAME (v) = FRAME_FP (frame); | |
408 | VALUE_FRAME_REGNUM (v) = regnum; | |
409 | } | |
410 | else if (mem_stor) | |
411 | { | |
412 | VALUE_LVAL (v) = lval_memory; | |
413 | VALUE_ADDRESS (v) = find_saved_register (frame, regnum); | |
414 | } | |
415 | else if (reg_stor) | |
416 | { | |
417 | VALUE_LVAL (v) = lval_register; | |
418 | VALUE_ADDRESS (v) = REGISTER_BYTE (regnum); | |
419 | } | |
420 | else | |
421 | fatal ("value_from_register: Value not stored anywhere!"); | |
422 | ||
423 | /* Any structure stored in more than one register will always be | |
424 | an inegral number of registers. Otherwise, you'd need to do | |
425 | some fiddling with the last register copied here for little | |
426 | endian machines. */ | |
427 | ||
428 | /* Copy into the contents section of the value. */ | |
429 | bcopy (value_bytes, VALUE_CONTENTS (v), len); | |
430 | ||
431 | return v; | |
432 | } | |
433 | ||
434 | /* Data is completely contained within a single register. Locate the | |
435 | register's contents in a real register or in core; | |
436 | read the data in raw format. */ | |
437 | ||
438 | addr = find_saved_register (frame, regnum); | |
439 | if (addr == 0) | |
440 | { | |
441 | /* Value is really in a register. */ | |
442 | ||
443 | VALUE_LVAL (v) = lval_register; | |
444 | VALUE_ADDRESS (v) = REGISTER_BYTE (regnum); | |
445 | ||
446 | read_register_bytes (REGISTER_BYTE (regnum), | |
447 | raw_buffer, REGISTER_RAW_SIZE (regnum)); | |
448 | } | |
449 | else | |
450 | { | |
451 | /* Value was in a register that has been saved in memory. */ | |
452 | ||
453 | read_memory (addr, raw_buffer, REGISTER_RAW_SIZE (regnum)); | |
454 | VALUE_LVAL (v) = lval_memory; | |
455 | VALUE_ADDRESS (v) = addr; | |
456 | } | |
457 | ||
458 | /* Convert the raw contents to virtual contents. | |
459 | (Just copy them if the formats are the same.) */ | |
460 | ||
461 | REGISTER_CONVERT_TO_VIRTUAL (regnum, raw_buffer, virtual_buffer); | |
462 | ||
463 | if (REGISTER_CONVERTIBLE (regnum)) | |
464 | { | |
465 | /* When the raw and virtual formats differ, the virtual format | |
466 | corresponds to a specific data type. If we want that type, | |
467 | copy the data into the value. | |
468 | Otherwise, do a type-conversion. */ | |
469 | ||
470 | if (type != REGISTER_VIRTUAL_TYPE (regnum)) | |
471 | { | |
472 | /* eg a variable of type `float' in a 68881 register | |
473 | with raw type `extended' and virtual type `double'. | |
474 | Fetch it as a `double' and then convert to `float'. */ | |
475 | v = allocate_value (REGISTER_VIRTUAL_TYPE (regnum)); | |
476 | bcopy (virtual_buffer, VALUE_CONTENTS (v), len); | |
477 | v = value_cast (type, v); | |
478 | } | |
479 | else | |
480 | bcopy (virtual_buffer, VALUE_CONTENTS (v), len); | |
481 | } | |
482 | else | |
483 | { | |
484 | /* Raw and virtual formats are the same for this register. */ | |
485 | ||
486 | #ifdef BYTES_BIG_ENDIAN | |
487 | if (len < REGISTER_RAW_SIZE (regnum)) | |
488 | { | |
489 | /* Big-endian, and we want less than full size. */ | |
490 | VALUE_OFFSET (v) = REGISTER_RAW_SIZE (regnum) - len; | |
491 | } | |
492 | #endif | |
493 | ||
494 | bcopy (virtual_buffer + VALUE_OFFSET (v), | |
495 | VALUE_CONTENTS (v), len); | |
496 | } | |
497 | ||
498 | return v; | |
499 | } | |
500 | \f | |
501 | /* Given a struct symbol for a variable, | |
502 | and a stack frame id, | |
503 | return a (pointer to a) struct value containing the variable's address. */ | |
504 | ||
505 | value | |
506 | locate_var_value (var, frame) | |
507 | register struct symbol *var; | |
508 | FRAME frame; | |
509 | { | |
510 | register CORE_ADDR addr = 0; | |
511 | int val = SYMBOL_VALUE (var); | |
512 | struct frame_info *fi; | |
513 | struct type *type = SYMBOL_TYPE (var); | |
514 | struct type *result_type; | |
515 | ||
516 | if (frame == 0) frame = selected_frame; | |
517 | ||
518 | switch (SYMBOL_CLASS (var)) | |
519 | { | |
520 | case LOC_CONST: | |
521 | case LOC_CONST_BYTES: | |
522 | error ("Address requested for identifier \"%s\" which is a constant.", | |
523 | SYMBOL_NAME (var)); | |
524 | ||
525 | case LOC_REGISTER: | |
526 | case LOC_REGPARM: | |
527 | addr = find_saved_register (frame, val); | |
528 | if (addr != 0) | |
529 | { | |
530 | int len = TYPE_LENGTH (type); | |
531 | #ifdef BYTES_BIG_ENDIAN | |
532 | if (len < REGISTER_RAW_SIZE (val)) | |
533 | /* Big-endian, and we want less than full size. */ | |
534 | addr += REGISTER_RAW_SIZE (val) - len; | |
535 | #endif | |
536 | break; | |
537 | } | |
538 | error ("Address requested for identifier \"%s\" which is in a register.", | |
539 | SYMBOL_NAME (var)); | |
540 | ||
541 | case LOC_STATIC: | |
542 | case LOC_LABEL: | |
543 | addr = val; | |
544 | break; | |
545 | ||
546 | case LOC_ARG: | |
547 | fi = get_frame_info (frame); | |
548 | addr = val + FRAME_ARGS_ADDRESS (fi); | |
549 | break; | |
550 | ||
551 | case LOC_REF_ARG: | |
552 | fi = get_frame_info (frame); | |
553 | addr = val + FRAME_ARGS_ADDRESS (fi); | |
554 | addr = read_memory_integer (addr, sizeof (CORE_ADDR)); | |
555 | break; | |
556 | ||
557 | case LOC_LOCAL: | |
558 | fi = get_frame_info (frame); | |
559 | addr = val + FRAME_LOCALS_ADDRESS (fi); | |
560 | break; | |
561 | ||
562 | case LOC_TYPEDEF: | |
563 | error ("Address requested for identifier \"%s\" which is a typedef.", | |
564 | SYMBOL_NAME (var)); | |
565 | ||
566 | case LOC_BLOCK: | |
567 | addr = BLOCK_START (SYMBOL_BLOCK_VALUE (var)); | |
568 | break; | |
569 | } | |
570 | ||
571 | /* Address of an array is of the type of address of it's elements. */ | |
572 | result_type = | |
573 | lookup_pointer_type (TYPE_CODE (type) == TYPE_CODE_ARRAY ? | |
574 | TYPE_TARGET_TYPE (type) : type); | |
575 | ||
576 | return value_cast (result_type, | |
577 | value_from_long (builtin_type_long, (LONGEST) addr)); | |
578 | } | |
579 |