Commit | Line | Data |
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4c2df51b | 1 | /* DWARF 2 location expression support for GDB. |
feb13ab0 | 2 | |
4c38e0a4 JB |
3 | Copyright (C) 2003, 2005, 2007, 2008, 2009, 2010 |
4 | Free Software Foundation, Inc. | |
feb13ab0 | 5 | |
4c2df51b DJ |
6 | Contributed by Daniel Jacobowitz, MontaVista Software, Inc. |
7 | ||
8 | This file is part of GDB. | |
9 | ||
10 | This program is free software; you can redistribute it and/or modify | |
11 | it under the terms of the GNU General Public License as published by | |
a9762ec7 JB |
12 | the Free Software Foundation; either version 3 of the License, or |
13 | (at your option) any later version. | |
4c2df51b | 14 | |
a9762ec7 JB |
15 | This program is distributed in the hope that it will be useful, |
16 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
17 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
18 | GNU General Public License for more details. | |
4c2df51b DJ |
19 | |
20 | You should have received a copy of the GNU General Public License | |
a9762ec7 | 21 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ |
4c2df51b DJ |
22 | |
23 | #include "defs.h" | |
24 | #include "ui-out.h" | |
25 | #include "value.h" | |
26 | #include "frame.h" | |
27 | #include "gdbcore.h" | |
28 | #include "target.h" | |
29 | #include "inferior.h" | |
a55cc764 DJ |
30 | #include "ax.h" |
31 | #include "ax-gdb.h" | |
e4adbba9 | 32 | #include "regcache.h" |
c3228f12 | 33 | #include "objfiles.h" |
93ad78a7 | 34 | #include "exceptions.h" |
edb3359d | 35 | #include "block.h" |
4c2df51b | 36 | |
fa8f86ff | 37 | #include "dwarf2.h" |
4c2df51b DJ |
38 | #include "dwarf2expr.h" |
39 | #include "dwarf2loc.h" | |
e7802207 | 40 | #include "dwarf2-frame.h" |
4c2df51b DJ |
41 | |
42 | #include "gdb_string.h" | |
eff4f95e | 43 | #include "gdb_assert.h" |
4c2df51b | 44 | |
0936ad1d SS |
45 | static void |
46 | dwarf_expr_frame_base_1 (struct symbol *framefunc, CORE_ADDR pc, | |
47 | gdb_byte **start, size_t *length); | |
48 | ||
0d53c4c4 DJ |
49 | /* A helper function for dealing with location lists. Given a |
50 | symbol baton (BATON) and a pc value (PC), find the appropriate | |
51 | location expression, set *LOCEXPR_LENGTH, and return a pointer | |
52 | to the beginning of the expression. Returns NULL on failure. | |
53 | ||
54 | For now, only return the first matching location expression; there | |
55 | can be more than one in the list. */ | |
56 | ||
852483bc | 57 | static gdb_byte * |
0d53c4c4 | 58 | find_location_expression (struct dwarf2_loclist_baton *baton, |
b6b08ebf | 59 | size_t *locexpr_length, CORE_ADDR pc) |
0d53c4c4 | 60 | { |
0d53c4c4 | 61 | CORE_ADDR low, high; |
852483bc MK |
62 | gdb_byte *loc_ptr, *buf_end; |
63 | int length; | |
ae0d2f24 | 64 | struct objfile *objfile = dwarf2_per_cu_objfile (baton->per_cu); |
f7fd4728 | 65 | struct gdbarch *gdbarch = get_objfile_arch (objfile); |
e17a4113 | 66 | enum bfd_endian byte_order = gdbarch_byte_order (gdbarch); |
ae0d2f24 | 67 | unsigned int addr_size = dwarf2_per_cu_addr_size (baton->per_cu); |
0d53c4c4 | 68 | CORE_ADDR base_mask = ~(~(CORE_ADDR)1 << (addr_size * 8 - 1)); |
8edfa926 | 69 | /* Adjust base_address for relocatable objects. */ |
ae0d2f24 UW |
70 | CORE_ADDR base_offset = ANOFFSET (objfile->section_offsets, |
71 | SECT_OFF_TEXT (objfile)); | |
8edfa926 | 72 | CORE_ADDR base_address = baton->base_address + base_offset; |
0d53c4c4 DJ |
73 | |
74 | loc_ptr = baton->data; | |
75 | buf_end = baton->data + baton->size; | |
76 | ||
77 | while (1) | |
78 | { | |
b5758fe4 UW |
79 | if (buf_end - loc_ptr < 2 * addr_size) |
80 | error (_("find_location_expression: Corrupted DWARF expression.")); | |
0d53c4c4 | 81 | |
b5758fe4 UW |
82 | low = extract_unsigned_integer (loc_ptr, addr_size, byte_order); |
83 | loc_ptr += addr_size; | |
0d53c4c4 DJ |
84 | |
85 | /* A base-address-selection entry. */ | |
b5758fe4 | 86 | if (low == base_mask) |
0d53c4c4 | 87 | { |
b5758fe4 UW |
88 | base_address = dwarf2_read_address (gdbarch, |
89 | loc_ptr, buf_end, addr_size); | |
90 | loc_ptr += addr_size; | |
0d53c4c4 DJ |
91 | continue; |
92 | } | |
93 | ||
b5758fe4 UW |
94 | high = extract_unsigned_integer (loc_ptr, addr_size, byte_order); |
95 | loc_ptr += addr_size; | |
96 | ||
97 | /* An end-of-list entry. */ | |
98 | if (low == 0 && high == 0) | |
99 | return NULL; | |
100 | ||
0d53c4c4 DJ |
101 | /* Otherwise, a location expression entry. */ |
102 | low += base_address; | |
103 | high += base_address; | |
104 | ||
e17a4113 | 105 | length = extract_unsigned_integer (loc_ptr, 2, byte_order); |
0d53c4c4 DJ |
106 | loc_ptr += 2; |
107 | ||
108 | if (pc >= low && pc < high) | |
109 | { | |
110 | *locexpr_length = length; | |
111 | return loc_ptr; | |
112 | } | |
113 | ||
114 | loc_ptr += length; | |
115 | } | |
116 | } | |
117 | ||
4c2df51b DJ |
118 | /* This is the baton used when performing dwarf2 expression |
119 | evaluation. */ | |
120 | struct dwarf_expr_baton | |
121 | { | |
122 | struct frame_info *frame; | |
123 | struct objfile *objfile; | |
124 | }; | |
125 | ||
126 | /* Helper functions for dwarf2_evaluate_loc_desc. */ | |
127 | ||
4bc9efe1 | 128 | /* Using the frame specified in BATON, return the value of register |
0b2b0195 | 129 | REGNUM, treated as a pointer. */ |
4c2df51b | 130 | static CORE_ADDR |
61fbb938 | 131 | dwarf_expr_read_reg (void *baton, int dwarf_regnum) |
4c2df51b | 132 | { |
4c2df51b | 133 | struct dwarf_expr_baton *debaton = (struct dwarf_expr_baton *) baton; |
5e2b427d | 134 | struct gdbarch *gdbarch = get_frame_arch (debaton->frame); |
e5192dd8 | 135 | CORE_ADDR result; |
0b2b0195 | 136 | int regnum; |
e4adbba9 | 137 | |
5e2b427d UW |
138 | regnum = gdbarch_dwarf2_reg_to_regnum (gdbarch, dwarf_regnum); |
139 | result = address_from_register (builtin_type (gdbarch)->builtin_data_ptr, | |
0b2b0195 | 140 | regnum, debaton->frame); |
4c2df51b DJ |
141 | return result; |
142 | } | |
143 | ||
144 | /* Read memory at ADDR (length LEN) into BUF. */ | |
145 | ||
146 | static void | |
852483bc | 147 | dwarf_expr_read_mem (void *baton, gdb_byte *buf, CORE_ADDR addr, size_t len) |
4c2df51b DJ |
148 | { |
149 | read_memory (addr, buf, len); | |
150 | } | |
151 | ||
152 | /* Using the frame specified in BATON, find the location expression | |
153 | describing the frame base. Return a pointer to it in START and | |
154 | its length in LENGTH. */ | |
155 | static void | |
852483bc | 156 | dwarf_expr_frame_base (void *baton, gdb_byte **start, size_t * length) |
4c2df51b | 157 | { |
da62e633 AC |
158 | /* FIXME: cagney/2003-03-26: This code should be using |
159 | get_frame_base_address(), and then implement a dwarf2 specific | |
160 | this_base method. */ | |
4c2df51b | 161 | struct symbol *framefunc; |
4c2df51b | 162 | struct dwarf_expr_baton *debaton = (struct dwarf_expr_baton *) baton; |
0d53c4c4 | 163 | |
edb3359d DJ |
164 | /* Use block_linkage_function, which returns a real (not inlined) |
165 | function, instead of get_frame_function, which may return an | |
166 | inlined function. */ | |
167 | framefunc = block_linkage_function (get_frame_block (debaton->frame, NULL)); | |
0d53c4c4 | 168 | |
eff4f95e JG |
169 | /* If we found a frame-relative symbol then it was certainly within |
170 | some function associated with a frame. If we can't find the frame, | |
171 | something has gone wrong. */ | |
172 | gdb_assert (framefunc != NULL); | |
173 | ||
0936ad1d SS |
174 | dwarf_expr_frame_base_1 (framefunc, |
175 | get_frame_address_in_block (debaton->frame), | |
176 | start, length); | |
177 | } | |
178 | ||
179 | static void | |
180 | dwarf_expr_frame_base_1 (struct symbol *framefunc, CORE_ADDR pc, | |
181 | gdb_byte **start, size_t *length) | |
182 | { | |
edb3359d DJ |
183 | if (SYMBOL_LOCATION_BATON (framefunc) == NULL) |
184 | *start = NULL; | |
185 | else if (SYMBOL_COMPUTED_OPS (framefunc) == &dwarf2_loclist_funcs) | |
0d53c4c4 DJ |
186 | { |
187 | struct dwarf2_loclist_baton *symbaton; | |
22c6caba | 188 | |
0d53c4c4 | 189 | symbaton = SYMBOL_LOCATION_BATON (framefunc); |
0936ad1d | 190 | *start = find_location_expression (symbaton, length, pc); |
0d53c4c4 DJ |
191 | } |
192 | else | |
193 | { | |
194 | struct dwarf2_locexpr_baton *symbaton; | |
195 | symbaton = SYMBOL_LOCATION_BATON (framefunc); | |
ebd3bcc1 JK |
196 | if (symbaton != NULL) |
197 | { | |
198 | *length = symbaton->size; | |
199 | *start = symbaton->data; | |
200 | } | |
201 | else | |
202 | *start = NULL; | |
0d53c4c4 DJ |
203 | } |
204 | ||
205 | if (*start == NULL) | |
8a3fe4f8 | 206 | error (_("Could not find the frame base for \"%s\"."), |
0d53c4c4 | 207 | SYMBOL_NATURAL_NAME (framefunc)); |
4c2df51b DJ |
208 | } |
209 | ||
e7802207 TT |
210 | /* Helper function for dwarf2_evaluate_loc_desc. Computes the CFA for |
211 | the frame in BATON. */ | |
212 | ||
213 | static CORE_ADDR | |
214 | dwarf_expr_frame_cfa (void *baton) | |
215 | { | |
216 | struct dwarf_expr_baton *debaton = (struct dwarf_expr_baton *) baton; | |
217 | return dwarf2_frame_cfa (debaton->frame); | |
218 | } | |
219 | ||
4c2df51b DJ |
220 | /* Using the objfile specified in BATON, find the address for the |
221 | current thread's thread-local storage with offset OFFSET. */ | |
222 | static CORE_ADDR | |
223 | dwarf_expr_tls_address (void *baton, CORE_ADDR offset) | |
224 | { | |
225 | struct dwarf_expr_baton *debaton = (struct dwarf_expr_baton *) baton; | |
4c2df51b | 226 | |
9e35dae4 | 227 | return target_translate_tls_address (debaton->objfile, offset); |
4c2df51b DJ |
228 | } |
229 | ||
052b9502 NF |
230 | struct piece_closure |
231 | { | |
232 | /* The number of pieces used to describe this variable. */ | |
233 | int n_pieces; | |
234 | ||
cec03d70 TT |
235 | /* The architecture, used only for DWARF_VALUE_STACK. */ |
236 | struct gdbarch *arch; | |
237 | ||
052b9502 NF |
238 | /* The pieces themselves. */ |
239 | struct dwarf_expr_piece *pieces; | |
240 | }; | |
241 | ||
242 | /* Allocate a closure for a value formed from separately-described | |
243 | PIECES. */ | |
244 | ||
245 | static struct piece_closure * | |
cec03d70 TT |
246 | allocate_piece_closure (int n_pieces, struct dwarf_expr_piece *pieces, |
247 | struct gdbarch *arch) | |
052b9502 NF |
248 | { |
249 | struct piece_closure *c = XZALLOC (struct piece_closure); | |
250 | ||
251 | c->n_pieces = n_pieces; | |
cec03d70 | 252 | c->arch = arch; |
052b9502 NF |
253 | c->pieces = XCALLOC (n_pieces, struct dwarf_expr_piece); |
254 | ||
255 | memcpy (c->pieces, pieces, n_pieces * sizeof (struct dwarf_expr_piece)); | |
256 | ||
257 | return c; | |
258 | } | |
259 | ||
260 | static void | |
261 | read_pieced_value (struct value *v) | |
262 | { | |
263 | int i; | |
264 | long offset = 0; | |
265 | gdb_byte *contents; | |
266 | struct piece_closure *c = (struct piece_closure *) value_computed_closure (v); | |
267 | struct frame_info *frame = frame_find_by_id (VALUE_FRAME_ID (v)); | |
268 | ||
269 | contents = value_contents_raw (v); | |
270 | for (i = 0; i < c->n_pieces; i++) | |
271 | { | |
272 | struct dwarf_expr_piece *p = &c->pieces[i]; | |
cec03d70 | 273 | switch (p->location) |
052b9502 | 274 | { |
cec03d70 TT |
275 | case DWARF_VALUE_REGISTER: |
276 | { | |
277 | struct gdbarch *arch = get_frame_arch (frame); | |
cec03d70 | 278 | int gdb_regnum = gdbarch_dwarf2_reg_to_regnum (arch, |
44353522 | 279 | p->v.expr.value); |
dcbf108f UW |
280 | int reg_offset = 0; |
281 | ||
282 | if (gdbarch_byte_order (arch) == BFD_ENDIAN_BIG | |
283 | && p->size < register_size (arch, gdb_regnum)) | |
284 | /* Big-endian, and we want less than full size. */ | |
285 | reg_offset = register_size (arch, gdb_regnum) - p->size; | |
286 | ||
287 | get_frame_register_bytes (frame, gdb_regnum, reg_offset, p->size, | |
288 | contents + offset); | |
cec03d70 TT |
289 | } |
290 | break; | |
291 | ||
292 | case DWARF_VALUE_MEMORY: | |
44353522 DE |
293 | if (p->v.expr.in_stack_memory) |
294 | read_stack (p->v.expr.value, contents + offset, p->size); | |
295 | else | |
296 | read_memory (p->v.expr.value, contents + offset, p->size); | |
cec03d70 TT |
297 | break; |
298 | ||
299 | case DWARF_VALUE_STACK: | |
300 | { | |
301 | gdb_byte bytes[sizeof (ULONGEST)]; | |
302 | size_t n; | |
303 | int addr_size = gdbarch_addr_bit (c->arch) / 8; | |
304 | store_unsigned_integer (bytes, addr_size, | |
305 | gdbarch_byte_order (c->arch), | |
44353522 | 306 | p->v.expr.value); |
cec03d70 TT |
307 | n = p->size; |
308 | if (n > addr_size) | |
309 | n = addr_size; | |
310 | memcpy (contents + offset, bytes, n); | |
311 | } | |
312 | break; | |
313 | ||
314 | case DWARF_VALUE_LITERAL: | |
315 | { | |
316 | size_t n = p->size; | |
317 | if (n > p->v.literal.length) | |
318 | n = p->v.literal.length; | |
319 | memcpy (contents + offset, p->v.literal.data, n); | |
320 | } | |
321 | break; | |
322 | ||
323 | default: | |
324 | internal_error (__FILE__, __LINE__, _("invalid location type")); | |
052b9502 NF |
325 | } |
326 | offset += p->size; | |
327 | } | |
328 | } | |
329 | ||
330 | static void | |
331 | write_pieced_value (struct value *to, struct value *from) | |
332 | { | |
333 | int i; | |
334 | long offset = 0; | |
335 | gdb_byte *contents; | |
336 | struct piece_closure *c = (struct piece_closure *) value_computed_closure (to); | |
337 | struct frame_info *frame = frame_find_by_id (VALUE_FRAME_ID (to)); | |
338 | ||
339 | if (frame == NULL) | |
340 | { | |
341 | set_value_optimized_out (to, 1); | |
342 | return; | |
343 | } | |
344 | ||
345 | contents = value_contents_raw (from); | |
346 | for (i = 0; i < c->n_pieces; i++) | |
347 | { | |
348 | struct dwarf_expr_piece *p = &c->pieces[i]; | |
cec03d70 | 349 | switch (p->location) |
052b9502 | 350 | { |
cec03d70 TT |
351 | case DWARF_VALUE_REGISTER: |
352 | { | |
353 | struct gdbarch *arch = get_frame_arch (frame); | |
44353522 | 354 | int gdb_regnum = gdbarch_dwarf2_reg_to_regnum (arch, p->v.expr.value); |
dcbf108f UW |
355 | int reg_offset = 0; |
356 | ||
357 | if (gdbarch_byte_order (arch) == BFD_ENDIAN_BIG | |
358 | && p->size < register_size (arch, gdb_regnum)) | |
359 | /* Big-endian, and we want less than full size. */ | |
360 | reg_offset = register_size (arch, gdb_regnum) - p->size; | |
361 | ||
362 | put_frame_register_bytes (frame, gdb_regnum, reg_offset, p->size, | |
363 | contents + offset); | |
cec03d70 TT |
364 | } |
365 | break; | |
366 | case DWARF_VALUE_MEMORY: | |
44353522 | 367 | write_memory (p->v.expr.value, contents + offset, p->size); |
cec03d70 TT |
368 | break; |
369 | default: | |
370 | set_value_optimized_out (to, 1); | |
371 | return; | |
052b9502 NF |
372 | } |
373 | offset += p->size; | |
374 | } | |
375 | } | |
376 | ||
377 | static void * | |
378 | copy_pieced_value_closure (struct value *v) | |
379 | { | |
380 | struct piece_closure *c = (struct piece_closure *) value_computed_closure (v); | |
381 | ||
cec03d70 | 382 | return allocate_piece_closure (c->n_pieces, c->pieces, c->arch); |
052b9502 NF |
383 | } |
384 | ||
385 | static void | |
386 | free_pieced_value_closure (struct value *v) | |
387 | { | |
388 | struct piece_closure *c = (struct piece_closure *) value_computed_closure (v); | |
389 | ||
390 | xfree (c->pieces); | |
391 | xfree (c); | |
392 | } | |
393 | ||
394 | /* Functions for accessing a variable described by DW_OP_piece. */ | |
395 | static struct lval_funcs pieced_value_funcs = { | |
396 | read_pieced_value, | |
397 | write_pieced_value, | |
398 | copy_pieced_value_closure, | |
399 | free_pieced_value_closure | |
400 | }; | |
401 | ||
4c2df51b DJ |
402 | /* Evaluate a location description, starting at DATA and with length |
403 | SIZE, to find the current location of variable VAR in the context | |
404 | of FRAME. */ | |
405 | static struct value * | |
406 | dwarf2_evaluate_loc_desc (struct symbol *var, struct frame_info *frame, | |
852483bc | 407 | gdb_byte *data, unsigned short size, |
ae0d2f24 | 408 | struct dwarf2_per_cu_data *per_cu) |
4c2df51b | 409 | { |
4c2df51b DJ |
410 | struct value *retval; |
411 | struct dwarf_expr_baton baton; | |
412 | struct dwarf_expr_context *ctx; | |
4a227398 | 413 | struct cleanup *old_chain; |
4c2df51b | 414 | |
0d53c4c4 DJ |
415 | if (size == 0) |
416 | { | |
417 | retval = allocate_value (SYMBOL_TYPE (var)); | |
418 | VALUE_LVAL (retval) = not_lval; | |
feb13ab0 | 419 | set_value_optimized_out (retval, 1); |
10fb19b6 | 420 | return retval; |
0d53c4c4 DJ |
421 | } |
422 | ||
4c2df51b | 423 | baton.frame = frame; |
ae0d2f24 | 424 | baton.objfile = dwarf2_per_cu_objfile (per_cu); |
4c2df51b DJ |
425 | |
426 | ctx = new_dwarf_expr_context (); | |
4a227398 TT |
427 | old_chain = make_cleanup_free_dwarf_expr_context (ctx); |
428 | ||
f7fd4728 | 429 | ctx->gdbarch = get_objfile_arch (baton.objfile); |
ae0d2f24 | 430 | ctx->addr_size = dwarf2_per_cu_addr_size (per_cu); |
4c2df51b DJ |
431 | ctx->baton = &baton; |
432 | ctx->read_reg = dwarf_expr_read_reg; | |
433 | ctx->read_mem = dwarf_expr_read_mem; | |
434 | ctx->get_frame_base = dwarf_expr_frame_base; | |
e7802207 | 435 | ctx->get_frame_cfa = dwarf_expr_frame_cfa; |
4c2df51b DJ |
436 | ctx->get_tls_address = dwarf_expr_tls_address; |
437 | ||
438 | dwarf_expr_eval (ctx, data, size); | |
87808bd6 JB |
439 | if (ctx->num_pieces > 0) |
440 | { | |
052b9502 NF |
441 | struct piece_closure *c; |
442 | struct frame_id frame_id = get_frame_id (frame); | |
443 | ||
cec03d70 | 444 | c = allocate_piece_closure (ctx->num_pieces, ctx->pieces, ctx->gdbarch); |
052b9502 NF |
445 | retval = allocate_computed_value (SYMBOL_TYPE (var), |
446 | &pieced_value_funcs, | |
447 | c); | |
448 | VALUE_FRAME_ID (retval) = frame_id; | |
87808bd6 | 449 | } |
4c2df51b DJ |
450 | else |
451 | { | |
cec03d70 TT |
452 | switch (ctx->location) |
453 | { | |
454 | case DWARF_VALUE_REGISTER: | |
455 | { | |
456 | struct gdbarch *arch = get_frame_arch (frame); | |
457 | CORE_ADDR dwarf_regnum = dwarf_expr_fetch (ctx, 0); | |
458 | int gdb_regnum = gdbarch_dwarf2_reg_to_regnum (arch, dwarf_regnum); | |
459 | retval = value_from_register (SYMBOL_TYPE (var), gdb_regnum, frame); | |
460 | } | |
461 | break; | |
462 | ||
463 | case DWARF_VALUE_MEMORY: | |
464 | { | |
465 | CORE_ADDR address = dwarf_expr_fetch (ctx, 0); | |
44353522 | 466 | int in_stack_memory = dwarf_expr_fetch_in_stack_memory (ctx, 0); |
cec03d70 TT |
467 | |
468 | retval = allocate_value (SYMBOL_TYPE (var)); | |
469 | VALUE_LVAL (retval) = lval_memory; | |
470 | set_value_lazy (retval, 1); | |
44353522 DE |
471 | if (in_stack_memory) |
472 | set_value_stack (retval, 1); | |
cec03d70 TT |
473 | set_value_address (retval, address); |
474 | } | |
475 | break; | |
476 | ||
477 | case DWARF_VALUE_STACK: | |
478 | { | |
479 | gdb_byte bytes[sizeof (ULONGEST)]; | |
480 | ULONGEST value = (ULONGEST) dwarf_expr_fetch (ctx, 0); | |
481 | bfd_byte *contents; | |
482 | size_t n = ctx->addr_size; | |
483 | ||
484 | store_unsigned_integer (bytes, ctx->addr_size, | |
485 | gdbarch_byte_order (ctx->gdbarch), | |
486 | value); | |
487 | retval = allocate_value (SYMBOL_TYPE (var)); | |
488 | contents = value_contents_raw (retval); | |
489 | if (n > TYPE_LENGTH (SYMBOL_TYPE (var))) | |
490 | n = TYPE_LENGTH (SYMBOL_TYPE (var)); | |
491 | memcpy (contents, bytes, n); | |
492 | } | |
493 | break; | |
494 | ||
495 | case DWARF_VALUE_LITERAL: | |
496 | { | |
497 | bfd_byte *contents; | |
498 | size_t n = ctx->len; | |
499 | ||
500 | retval = allocate_value (SYMBOL_TYPE (var)); | |
501 | contents = value_contents_raw (retval); | |
502 | if (n > TYPE_LENGTH (SYMBOL_TYPE (var))) | |
503 | n = TYPE_LENGTH (SYMBOL_TYPE (var)); | |
504 | memcpy (contents, ctx->data, n); | |
505 | } | |
506 | break; | |
507 | ||
508 | default: | |
509 | internal_error (__FILE__, __LINE__, _("invalid location type")); | |
510 | } | |
4c2df51b DJ |
511 | } |
512 | ||
42be36b3 CT |
513 | set_value_initialized (retval, ctx->initialized); |
514 | ||
4a227398 | 515 | do_cleanups (old_chain); |
4c2df51b DJ |
516 | |
517 | return retval; | |
518 | } | |
4c2df51b DJ |
519 | \f |
520 | /* Helper functions and baton for dwarf2_loc_desc_needs_frame. */ | |
521 | ||
522 | struct needs_frame_baton | |
523 | { | |
524 | int needs_frame; | |
525 | }; | |
526 | ||
527 | /* Reads from registers do require a frame. */ | |
528 | static CORE_ADDR | |
61fbb938 | 529 | needs_frame_read_reg (void *baton, int regnum) |
4c2df51b DJ |
530 | { |
531 | struct needs_frame_baton *nf_baton = baton; | |
532 | nf_baton->needs_frame = 1; | |
533 | return 1; | |
534 | } | |
535 | ||
536 | /* Reads from memory do not require a frame. */ | |
537 | static void | |
852483bc | 538 | needs_frame_read_mem (void *baton, gdb_byte *buf, CORE_ADDR addr, size_t len) |
4c2df51b DJ |
539 | { |
540 | memset (buf, 0, len); | |
541 | } | |
542 | ||
543 | /* Frame-relative accesses do require a frame. */ | |
544 | static void | |
852483bc | 545 | needs_frame_frame_base (void *baton, gdb_byte **start, size_t * length) |
4c2df51b | 546 | { |
852483bc | 547 | static gdb_byte lit0 = DW_OP_lit0; |
4c2df51b DJ |
548 | struct needs_frame_baton *nf_baton = baton; |
549 | ||
550 | *start = &lit0; | |
551 | *length = 1; | |
552 | ||
553 | nf_baton->needs_frame = 1; | |
554 | } | |
555 | ||
e7802207 TT |
556 | /* CFA accesses require a frame. */ |
557 | ||
558 | static CORE_ADDR | |
559 | needs_frame_frame_cfa (void *baton) | |
560 | { | |
561 | struct needs_frame_baton *nf_baton = baton; | |
562 | nf_baton->needs_frame = 1; | |
563 | return 1; | |
564 | } | |
565 | ||
4c2df51b DJ |
566 | /* Thread-local accesses do require a frame. */ |
567 | static CORE_ADDR | |
568 | needs_frame_tls_address (void *baton, CORE_ADDR offset) | |
569 | { | |
570 | struct needs_frame_baton *nf_baton = baton; | |
571 | nf_baton->needs_frame = 1; | |
572 | return 1; | |
573 | } | |
574 | ||
575 | /* Return non-zero iff the location expression at DATA (length SIZE) | |
576 | requires a frame to evaluate. */ | |
577 | ||
578 | static int | |
ae0d2f24 UW |
579 | dwarf2_loc_desc_needs_frame (gdb_byte *data, unsigned short size, |
580 | struct dwarf2_per_cu_data *per_cu) | |
4c2df51b DJ |
581 | { |
582 | struct needs_frame_baton baton; | |
583 | struct dwarf_expr_context *ctx; | |
f630a401 | 584 | int in_reg; |
4a227398 | 585 | struct cleanup *old_chain; |
4c2df51b DJ |
586 | |
587 | baton.needs_frame = 0; | |
588 | ||
589 | ctx = new_dwarf_expr_context (); | |
4a227398 TT |
590 | old_chain = make_cleanup_free_dwarf_expr_context (ctx); |
591 | ||
f7fd4728 | 592 | ctx->gdbarch = get_objfile_arch (dwarf2_per_cu_objfile (per_cu)); |
ae0d2f24 | 593 | ctx->addr_size = dwarf2_per_cu_addr_size (per_cu); |
4c2df51b DJ |
594 | ctx->baton = &baton; |
595 | ctx->read_reg = needs_frame_read_reg; | |
596 | ctx->read_mem = needs_frame_read_mem; | |
597 | ctx->get_frame_base = needs_frame_frame_base; | |
e7802207 | 598 | ctx->get_frame_cfa = needs_frame_frame_cfa; |
4c2df51b DJ |
599 | ctx->get_tls_address = needs_frame_tls_address; |
600 | ||
601 | dwarf_expr_eval (ctx, data, size); | |
602 | ||
cec03d70 | 603 | in_reg = ctx->location == DWARF_VALUE_REGISTER; |
f630a401 | 604 | |
87808bd6 JB |
605 | if (ctx->num_pieces > 0) |
606 | { | |
607 | int i; | |
608 | ||
609 | /* If the location has several pieces, and any of them are in | |
610 | registers, then we will need a frame to fetch them from. */ | |
611 | for (i = 0; i < ctx->num_pieces; i++) | |
cec03d70 | 612 | if (ctx->pieces[i].location == DWARF_VALUE_REGISTER) |
87808bd6 JB |
613 | in_reg = 1; |
614 | } | |
615 | ||
4a227398 | 616 | do_cleanups (old_chain); |
4c2df51b | 617 | |
f630a401 | 618 | return baton.needs_frame || in_reg; |
4c2df51b DJ |
619 | } |
620 | ||
0d53c4c4 | 621 | static void |
505e835d UW |
622 | dwarf2_tracepoint_var_ref (struct symbol *symbol, struct gdbarch *gdbarch, |
623 | struct agent_expr *ax, struct axs_value *value, | |
624 | gdb_byte *data, int size) | |
0d53c4c4 DJ |
625 | { |
626 | if (size == 0) | |
8a3fe4f8 | 627 | error (_("Symbol \"%s\" has been optimized out."), |
0d53c4c4 DJ |
628 | SYMBOL_PRINT_NAME (symbol)); |
629 | ||
630 | if (size == 1 | |
631 | && data[0] >= DW_OP_reg0 | |
632 | && data[0] <= DW_OP_reg31) | |
633 | { | |
634 | value->kind = axs_lvalue_register; | |
635 | value->u.reg = data[0] - DW_OP_reg0; | |
636 | } | |
637 | else if (data[0] == DW_OP_regx) | |
638 | { | |
639 | ULONGEST reg; | |
640 | read_uleb128 (data + 1, data + size, ®); | |
641 | value->kind = axs_lvalue_register; | |
642 | value->u.reg = reg; | |
643 | } | |
644 | else if (data[0] == DW_OP_fbreg) | |
645 | { | |
0936ad1d SS |
646 | struct block *b; |
647 | struct symbol *framefunc; | |
648 | int frame_reg = 0; | |
0d53c4c4 | 649 | LONGEST frame_offset; |
852483bc | 650 | gdb_byte *buf_end; |
0936ad1d SS |
651 | gdb_byte *base_data; |
652 | size_t base_size; | |
653 | LONGEST base_offset = 0; | |
654 | ||
655 | b = block_for_pc (ax->scope); | |
656 | ||
657 | if (!b) | |
658 | error (_("No block found for address")); | |
659 | ||
660 | framefunc = block_linkage_function (b); | |
661 | ||
662 | if (!framefunc) | |
663 | error (_("No function found for block")); | |
664 | ||
665 | dwarf_expr_frame_base_1 (framefunc, ax->scope, | |
666 | &base_data, &base_size); | |
667 | ||
668 | if (base_data[0] >= DW_OP_breg0 | |
669 | && base_data[0] <= DW_OP_breg31) | |
670 | { | |
671 | frame_reg = base_data[0] - DW_OP_breg0; | |
672 | buf_end = read_sleb128 (base_data + 1, base_data + base_size, &base_offset); | |
673 | if (buf_end != base_data + base_size) | |
674 | error (_("Unexpected opcode after DW_OP_breg%u for symbol \"%s\"."), | |
675 | frame_reg, SYMBOL_PRINT_NAME (symbol)); | |
676 | } | |
677 | else | |
678 | { | |
679 | /* We don't know what to do with the frame base expression, | |
680 | so we can't trace this variable; give up. */ | |
681 | error (_("Cannot generate expression to collect symbol \"%s\"; DWARF 2 encoding not handled"), | |
682 | SYMBOL_PRINT_NAME (symbol)); | |
683 | } | |
0d53c4c4 DJ |
684 | |
685 | buf_end = read_sleb128 (data + 1, data + size, &frame_offset); | |
686 | if (buf_end != data + size) | |
8a3fe4f8 | 687 | error (_("Unexpected opcode after DW_OP_fbreg for symbol \"%s\"."), |
0d53c4c4 | 688 | SYMBOL_PRINT_NAME (symbol)); |
4c2df51b | 689 | |
0d53c4c4 | 690 | ax_reg (ax, frame_reg); |
0936ad1d | 691 | ax_const_l (ax, base_offset + frame_offset); |
0d53c4c4 | 692 | ax_simple (ax, aop_add); |
4c2df51b | 693 | |
9c238357 RC |
694 | value->kind = axs_lvalue_memory; |
695 | } | |
696 | else if (data[0] >= DW_OP_breg0 | |
697 | && data[0] <= DW_OP_breg31) | |
698 | { | |
699 | unsigned int reg; | |
700 | LONGEST offset; | |
701 | gdb_byte *buf_end; | |
702 | ||
703 | reg = data[0] - DW_OP_breg0; | |
704 | buf_end = read_sleb128 (data + 1, data + size, &offset); | |
705 | if (buf_end != data + size) | |
706 | error (_("Unexpected opcode after DW_OP_breg%u for symbol \"%s\"."), | |
707 | reg, SYMBOL_PRINT_NAME (symbol)); | |
708 | ||
709 | ax_reg (ax, reg); | |
710 | ax_const_l (ax, offset); | |
0d53c4c4 | 711 | ax_simple (ax, aop_add); |
9c238357 | 712 | |
0d53c4c4 DJ |
713 | value->kind = axs_lvalue_memory; |
714 | } | |
715 | else | |
9c238357 RC |
716 | error (_("Unsupported DWARF opcode 0x%x in the location of \"%s\"."), |
717 | data[0], SYMBOL_PRINT_NAME (symbol)); | |
0d53c4c4 | 718 | } |
4c2df51b DJ |
719 | \f |
720 | /* Return the value of SYMBOL in FRAME using the DWARF-2 expression | |
721 | evaluator to calculate the location. */ | |
722 | static struct value * | |
723 | locexpr_read_variable (struct symbol *symbol, struct frame_info *frame) | |
724 | { | |
725 | struct dwarf2_locexpr_baton *dlbaton = SYMBOL_LOCATION_BATON (symbol); | |
726 | struct value *val; | |
727 | val = dwarf2_evaluate_loc_desc (symbol, frame, dlbaton->data, dlbaton->size, | |
ae0d2f24 | 728 | dlbaton->per_cu); |
4c2df51b DJ |
729 | |
730 | return val; | |
731 | } | |
732 | ||
733 | /* Return non-zero iff we need a frame to evaluate SYMBOL. */ | |
734 | static int | |
735 | locexpr_read_needs_frame (struct symbol *symbol) | |
736 | { | |
737 | struct dwarf2_locexpr_baton *dlbaton = SYMBOL_LOCATION_BATON (symbol); | |
ae0d2f24 UW |
738 | return dwarf2_loc_desc_needs_frame (dlbaton->data, dlbaton->size, |
739 | dlbaton->per_cu); | |
4c2df51b DJ |
740 | } |
741 | ||
742 | /* Print a natural-language description of SYMBOL to STREAM. */ | |
743 | static int | |
744 | locexpr_describe_location (struct symbol *symbol, struct ui_file *stream) | |
745 | { | |
746 | /* FIXME: be more extensive. */ | |
747 | struct dwarf2_locexpr_baton *dlbaton = SYMBOL_LOCATION_BATON (symbol); | |
ae0d2f24 | 748 | int addr_size = dwarf2_per_cu_addr_size (dlbaton->per_cu); |
4c2df51b DJ |
749 | |
750 | if (dlbaton->size == 1 | |
751 | && dlbaton->data[0] >= DW_OP_reg0 | |
752 | && dlbaton->data[0] <= DW_OP_reg31) | |
753 | { | |
5e2b427d UW |
754 | struct objfile *objfile = dwarf2_per_cu_objfile (dlbaton->per_cu); |
755 | struct gdbarch *gdbarch = get_objfile_arch (objfile); | |
756 | int regno = gdbarch_dwarf2_reg_to_regnum (gdbarch, | |
757 | dlbaton->data[0] - DW_OP_reg0); | |
4c2df51b | 758 | fprintf_filtered (stream, |
c9f4d572 | 759 | "a variable in register %s", |
5e2b427d | 760 | gdbarch_register_name (gdbarch, regno)); |
4c2df51b DJ |
761 | return 1; |
762 | } | |
763 | ||
c3228f12 EZ |
764 | /* The location expression for a TLS variable looks like this (on a |
765 | 64-bit LE machine): | |
766 | ||
767 | DW_AT_location : 10 byte block: 3 4 0 0 0 0 0 0 0 e0 | |
768 | (DW_OP_addr: 4; DW_OP_GNU_push_tls_address) | |
769 | ||
770 | 0x3 is the encoding for DW_OP_addr, which has an operand as long | |
771 | as the size of an address on the target machine (here is 8 | |
772 | bytes). 0xe0 is the encoding for DW_OP_GNU_push_tls_address. | |
773 | The operand represents the offset at which the variable is within | |
774 | the thread local storage. */ | |
775 | ||
776 | if (dlbaton->size > 1 | |
777 | && dlbaton->data[dlbaton->size - 1] == DW_OP_GNU_push_tls_address) | |
778 | if (dlbaton->data[0] == DW_OP_addr) | |
779 | { | |
ae0d2f24 | 780 | struct objfile *objfile = dwarf2_per_cu_objfile (dlbaton->per_cu); |
f7fd4728 UW |
781 | struct gdbarch *gdbarch = get_objfile_arch (objfile); |
782 | CORE_ADDR offset = dwarf2_read_address (gdbarch, | |
783 | &dlbaton->data[1], | |
c193f044 | 784 | &dlbaton->data[dlbaton->size - 1], |
ae0d2f24 | 785 | addr_size); |
c3228f12 | 786 | fprintf_filtered (stream, |
32ffcbed | 787 | "a thread-local variable at offset %s in the " |
c3228f12 | 788 | "thread-local storage for `%s'", |
5af949e3 | 789 | paddress (gdbarch, offset), objfile->name); |
c3228f12 EZ |
790 | return 1; |
791 | } | |
792 | ||
793 | ||
4c2df51b DJ |
794 | fprintf_filtered (stream, |
795 | "a variable with complex or multiple locations (DWARF2)"); | |
796 | return 1; | |
797 | } | |
798 | ||
a55cc764 DJ |
799 | |
800 | /* Describe the location of SYMBOL as an agent value in VALUE, generating | |
801 | any necessary bytecode in AX. | |
802 | ||
803 | NOTE drow/2003-02-26: This function is extremely minimal, because | |
804 | doing it correctly is extremely complicated and there is no | |
805 | publicly available stub with tracepoint support for me to test | |
806 | against. When there is one this function should be revisited. */ | |
807 | ||
0d53c4c4 | 808 | static void |
505e835d UW |
809 | locexpr_tracepoint_var_ref (struct symbol *symbol, struct gdbarch *gdbarch, |
810 | struct agent_expr *ax, struct axs_value *value) | |
a55cc764 DJ |
811 | { |
812 | struct dwarf2_locexpr_baton *dlbaton = SYMBOL_LOCATION_BATON (symbol); | |
813 | ||
505e835d UW |
814 | dwarf2_tracepoint_var_ref (symbol, gdbarch, ax, value, |
815 | dlbaton->data, dlbaton->size); | |
a55cc764 DJ |
816 | } |
817 | ||
4c2df51b DJ |
818 | /* The set of location functions used with the DWARF-2 expression |
819 | evaluator. */ | |
768a979c | 820 | const struct symbol_computed_ops dwarf2_locexpr_funcs = { |
4c2df51b DJ |
821 | locexpr_read_variable, |
822 | locexpr_read_needs_frame, | |
823 | locexpr_describe_location, | |
a55cc764 | 824 | locexpr_tracepoint_var_ref |
4c2df51b | 825 | }; |
0d53c4c4 DJ |
826 | |
827 | ||
828 | /* Wrapper functions for location lists. These generally find | |
829 | the appropriate location expression and call something above. */ | |
830 | ||
831 | /* Return the value of SYMBOL in FRAME using the DWARF-2 expression | |
832 | evaluator to calculate the location. */ | |
833 | static struct value * | |
834 | loclist_read_variable (struct symbol *symbol, struct frame_info *frame) | |
835 | { | |
836 | struct dwarf2_loclist_baton *dlbaton = SYMBOL_LOCATION_BATON (symbol); | |
837 | struct value *val; | |
852483bc | 838 | gdb_byte *data; |
b6b08ebf | 839 | size_t size; |
0d53c4c4 DJ |
840 | |
841 | data = find_location_expression (dlbaton, &size, | |
22c6caba JW |
842 | frame ? get_frame_address_in_block (frame) |
843 | : 0); | |
0d53c4c4 | 844 | if (data == NULL) |
806048c6 DJ |
845 | { |
846 | val = allocate_value (SYMBOL_TYPE (symbol)); | |
847 | VALUE_LVAL (val) = not_lval; | |
848 | set_value_optimized_out (val, 1); | |
849 | } | |
850 | else | |
851 | val = dwarf2_evaluate_loc_desc (symbol, frame, data, size, | |
ae0d2f24 | 852 | dlbaton->per_cu); |
0d53c4c4 DJ |
853 | |
854 | return val; | |
855 | } | |
856 | ||
857 | /* Return non-zero iff we need a frame to evaluate SYMBOL. */ | |
858 | static int | |
859 | loclist_read_needs_frame (struct symbol *symbol) | |
860 | { | |
861 | /* If there's a location list, then assume we need to have a frame | |
862 | to choose the appropriate location expression. With tracking of | |
863 | global variables this is not necessarily true, but such tracking | |
864 | is disabled in GCC at the moment until we figure out how to | |
865 | represent it. */ | |
866 | ||
867 | return 1; | |
868 | } | |
869 | ||
870 | /* Print a natural-language description of SYMBOL to STREAM. */ | |
871 | static int | |
872 | loclist_describe_location (struct symbol *symbol, struct ui_file *stream) | |
873 | { | |
874 | /* FIXME: Could print the entire list of locations. */ | |
875 | fprintf_filtered (stream, "a variable with multiple locations"); | |
876 | return 1; | |
877 | } | |
878 | ||
879 | /* Describe the location of SYMBOL as an agent value in VALUE, generating | |
880 | any necessary bytecode in AX. */ | |
881 | static void | |
505e835d UW |
882 | loclist_tracepoint_var_ref (struct symbol *symbol, struct gdbarch *gdbarch, |
883 | struct agent_expr *ax, struct axs_value *value) | |
0d53c4c4 DJ |
884 | { |
885 | struct dwarf2_loclist_baton *dlbaton = SYMBOL_LOCATION_BATON (symbol); | |
852483bc | 886 | gdb_byte *data; |
b6b08ebf | 887 | size_t size; |
0d53c4c4 DJ |
888 | |
889 | data = find_location_expression (dlbaton, &size, ax->scope); | |
890 | if (data == NULL) | |
8a3fe4f8 | 891 | error (_("Variable \"%s\" is not available."), SYMBOL_NATURAL_NAME (symbol)); |
0d53c4c4 | 892 | |
505e835d | 893 | dwarf2_tracepoint_var_ref (symbol, gdbarch, ax, value, data, size); |
0d53c4c4 DJ |
894 | } |
895 | ||
896 | /* The set of location functions used with the DWARF-2 expression | |
897 | evaluator and location lists. */ | |
768a979c | 898 | const struct symbol_computed_ops dwarf2_loclist_funcs = { |
0d53c4c4 DJ |
899 | loclist_read_variable, |
900 | loclist_read_needs_frame, | |
901 | loclist_describe_location, | |
902 | loclist_tracepoint_var_ref | |
903 | }; |