Commit | Line | Data |
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4c2df51b | 1 | /* DWARF 2 location expression support for GDB. |
feb13ab0 | 2 | |
6aba47ca | 3 | Copyright (C) 2003, 2005, 2007 Free Software Foundation, Inc. |
feb13ab0 | 4 | |
4c2df51b DJ |
5 | Contributed by Daniel Jacobowitz, MontaVista Software, Inc. |
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 2 of the License, or (at | |
12 | your option) any later version. | |
13 | ||
14 | This program is distributed in the hope that it will be useful, but | |
15 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
16 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
17 | 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, write to the Free Software | |
197e01b6 EZ |
21 | Foundation, Inc., 51 Franklin Street, Fifth Floor, |
22 | Boston, MA 02110-1301, USA. */ | |
4c2df51b DJ |
23 | |
24 | #include "defs.h" | |
25 | #include "ui-out.h" | |
26 | #include "value.h" | |
27 | #include "frame.h" | |
28 | #include "gdbcore.h" | |
29 | #include "target.h" | |
30 | #include "inferior.h" | |
a55cc764 DJ |
31 | #include "ax.h" |
32 | #include "ax-gdb.h" | |
e4adbba9 | 33 | #include "regcache.h" |
c3228f12 | 34 | #include "objfiles.h" |
93ad78a7 | 35 | #include "exceptions.h" |
4c2df51b DJ |
36 | |
37 | #include "elf/dwarf2.h" | |
38 | #include "dwarf2expr.h" | |
39 | #include "dwarf2loc.h" | |
40 | ||
41 | #include "gdb_string.h" | |
42 | ||
43 | #ifndef DWARF2_REG_TO_REGNUM | |
44 | #define DWARF2_REG_TO_REGNUM(REG) (REG) | |
45 | #endif | |
46 | ||
0d53c4c4 DJ |
47 | /* A helper function for dealing with location lists. Given a |
48 | symbol baton (BATON) and a pc value (PC), find the appropriate | |
49 | location expression, set *LOCEXPR_LENGTH, and return a pointer | |
50 | to the beginning of the expression. Returns NULL on failure. | |
51 | ||
52 | For now, only return the first matching location expression; there | |
53 | can be more than one in the list. */ | |
54 | ||
852483bc | 55 | static gdb_byte * |
0d53c4c4 | 56 | find_location_expression (struct dwarf2_loclist_baton *baton, |
b6b08ebf | 57 | size_t *locexpr_length, CORE_ADDR pc) |
0d53c4c4 | 58 | { |
0d53c4c4 | 59 | CORE_ADDR low, high; |
852483bc MK |
60 | gdb_byte *loc_ptr, *buf_end; |
61 | int length; | |
62 | unsigned int addr_size = TARGET_ADDR_BIT / TARGET_CHAR_BIT; | |
0d53c4c4 | 63 | CORE_ADDR base_mask = ~(~(CORE_ADDR)1 << (addr_size * 8 - 1)); |
8edfa926 BM |
64 | /* Adjust base_address for relocatable objects. */ |
65 | CORE_ADDR base_offset = ANOFFSET (baton->objfile->section_offsets, | |
66 | SECT_OFF_TEXT (baton->objfile)); | |
67 | CORE_ADDR base_address = baton->base_address + base_offset; | |
0d53c4c4 DJ |
68 | |
69 | loc_ptr = baton->data; | |
70 | buf_end = baton->data + baton->size; | |
71 | ||
72 | while (1) | |
73 | { | |
74 | low = dwarf2_read_address (loc_ptr, buf_end, &length); | |
75 | loc_ptr += length; | |
76 | high = dwarf2_read_address (loc_ptr, buf_end, &length); | |
77 | loc_ptr += length; | |
78 | ||
79 | /* An end-of-list entry. */ | |
80 | if (low == 0 && high == 0) | |
81 | return NULL; | |
82 | ||
83 | /* A base-address-selection entry. */ | |
84 | if ((low & base_mask) == base_mask) | |
85 | { | |
86 | base_address = high; | |
87 | continue; | |
88 | } | |
89 | ||
90 | /* Otherwise, a location expression entry. */ | |
91 | low += base_address; | |
92 | high += base_address; | |
93 | ||
94 | length = extract_unsigned_integer (loc_ptr, 2); | |
95 | loc_ptr += 2; | |
96 | ||
97 | if (pc >= low && pc < high) | |
98 | { | |
99 | *locexpr_length = length; | |
100 | return loc_ptr; | |
101 | } | |
102 | ||
103 | loc_ptr += length; | |
104 | } | |
105 | } | |
106 | ||
4c2df51b DJ |
107 | /* This is the baton used when performing dwarf2 expression |
108 | evaluation. */ | |
109 | struct dwarf_expr_baton | |
110 | { | |
111 | struct frame_info *frame; | |
112 | struct objfile *objfile; | |
113 | }; | |
114 | ||
115 | /* Helper functions for dwarf2_evaluate_loc_desc. */ | |
116 | ||
4bc9efe1 | 117 | /* Using the frame specified in BATON, return the value of register |
0b2b0195 | 118 | REGNUM, treated as a pointer. */ |
4c2df51b | 119 | static CORE_ADDR |
61fbb938 | 120 | dwarf_expr_read_reg (void *baton, int dwarf_regnum) |
4c2df51b | 121 | { |
4c2df51b | 122 | struct dwarf_expr_baton *debaton = (struct dwarf_expr_baton *) baton; |
e5192dd8 | 123 | CORE_ADDR result; |
0b2b0195 | 124 | int regnum; |
e4adbba9 DJ |
125 | |
126 | regnum = DWARF2_REG_TO_REGNUM (dwarf_regnum); | |
0b2b0195 UW |
127 | result = address_from_register (builtin_type_void_data_ptr, |
128 | regnum, debaton->frame); | |
4c2df51b DJ |
129 | return result; |
130 | } | |
131 | ||
132 | /* Read memory at ADDR (length LEN) into BUF. */ | |
133 | ||
134 | static void | |
852483bc | 135 | dwarf_expr_read_mem (void *baton, gdb_byte *buf, CORE_ADDR addr, size_t len) |
4c2df51b DJ |
136 | { |
137 | read_memory (addr, buf, len); | |
138 | } | |
139 | ||
140 | /* Using the frame specified in BATON, find the location expression | |
141 | describing the frame base. Return a pointer to it in START and | |
142 | its length in LENGTH. */ | |
143 | static void | |
852483bc | 144 | dwarf_expr_frame_base (void *baton, gdb_byte **start, size_t * length) |
4c2df51b | 145 | { |
da62e633 AC |
146 | /* FIXME: cagney/2003-03-26: This code should be using |
147 | get_frame_base_address(), and then implement a dwarf2 specific | |
148 | this_base method. */ | |
4c2df51b | 149 | struct symbol *framefunc; |
4c2df51b | 150 | struct dwarf_expr_baton *debaton = (struct dwarf_expr_baton *) baton; |
0d53c4c4 | 151 | |
4c2df51b | 152 | framefunc = get_frame_function (debaton->frame); |
0d53c4c4 | 153 | |
a67af2b9 | 154 | if (SYMBOL_OPS (framefunc) == &dwarf2_loclist_funcs) |
0d53c4c4 DJ |
155 | { |
156 | struct dwarf2_loclist_baton *symbaton; | |
22c6caba JW |
157 | struct frame_info *frame = debaton->frame; |
158 | ||
0d53c4c4 DJ |
159 | symbaton = SYMBOL_LOCATION_BATON (framefunc); |
160 | *start = find_location_expression (symbaton, length, | |
22c6caba | 161 | get_frame_address_in_block (frame)); |
0d53c4c4 DJ |
162 | } |
163 | else | |
164 | { | |
165 | struct dwarf2_locexpr_baton *symbaton; | |
166 | symbaton = SYMBOL_LOCATION_BATON (framefunc); | |
167 | *length = symbaton->size; | |
168 | *start = symbaton->data; | |
169 | } | |
170 | ||
171 | if (*start == NULL) | |
8a3fe4f8 | 172 | error (_("Could not find the frame base for \"%s\"."), |
0d53c4c4 | 173 | SYMBOL_NATURAL_NAME (framefunc)); |
4c2df51b DJ |
174 | } |
175 | ||
176 | /* Using the objfile specified in BATON, find the address for the | |
177 | current thread's thread-local storage with offset OFFSET. */ | |
178 | static CORE_ADDR | |
179 | dwarf_expr_tls_address (void *baton, CORE_ADDR offset) | |
180 | { | |
181 | struct dwarf_expr_baton *debaton = (struct dwarf_expr_baton *) baton; | |
4c2df51b | 182 | |
9e35dae4 | 183 | return target_translate_tls_address (debaton->objfile, offset); |
4c2df51b DJ |
184 | } |
185 | ||
186 | /* Evaluate a location description, starting at DATA and with length | |
187 | SIZE, to find the current location of variable VAR in the context | |
188 | of FRAME. */ | |
189 | static struct value * | |
190 | dwarf2_evaluate_loc_desc (struct symbol *var, struct frame_info *frame, | |
852483bc | 191 | gdb_byte *data, unsigned short size, |
4c2df51b DJ |
192 | struct objfile *objfile) |
193 | { | |
87808bd6 | 194 | struct gdbarch *arch = get_frame_arch (frame); |
4c2df51b DJ |
195 | struct value *retval; |
196 | struct dwarf_expr_baton baton; | |
197 | struct dwarf_expr_context *ctx; | |
198 | ||
0d53c4c4 DJ |
199 | if (size == 0) |
200 | { | |
201 | retval = allocate_value (SYMBOL_TYPE (var)); | |
202 | VALUE_LVAL (retval) = not_lval; | |
feb13ab0 | 203 | set_value_optimized_out (retval, 1); |
10fb19b6 | 204 | return retval; |
0d53c4c4 DJ |
205 | } |
206 | ||
4c2df51b DJ |
207 | baton.frame = frame; |
208 | baton.objfile = objfile; | |
209 | ||
210 | ctx = new_dwarf_expr_context (); | |
211 | ctx->baton = &baton; | |
212 | ctx->read_reg = dwarf_expr_read_reg; | |
213 | ctx->read_mem = dwarf_expr_read_mem; | |
214 | ctx->get_frame_base = dwarf_expr_frame_base; | |
215 | ctx->get_tls_address = dwarf_expr_tls_address; | |
216 | ||
217 | dwarf_expr_eval (ctx, data, size); | |
87808bd6 JB |
218 | if (ctx->num_pieces > 0) |
219 | { | |
23572eca EZ |
220 | int i; |
221 | long offset = 0; | |
222 | bfd_byte *contents; | |
223 | ||
224 | retval = allocate_value (SYMBOL_TYPE (var)); | |
225 | contents = value_contents_raw (retval); | |
226 | for (i = 0; i < ctx->num_pieces; i++) | |
227 | { | |
228 | struct dwarf_expr_piece *p = &ctx->pieces[i]; | |
229 | if (p->in_reg) | |
230 | { | |
231 | bfd_byte regval[MAX_REGISTER_SIZE]; | |
232 | int gdb_regnum = DWARF2_REG_TO_REGNUM (p->value); | |
233 | get_frame_register (frame, gdb_regnum, regval); | |
234 | memcpy (contents + offset, regval, p->size); | |
235 | } | |
236 | else /* In memory? */ | |
237 | { | |
238 | read_memory (p->value, contents + offset, p->size); | |
239 | } | |
240 | offset += p->size; | |
241 | } | |
87808bd6 JB |
242 | } |
243 | else if (ctx->in_reg) | |
051caad9 | 244 | { |
5ca2e327 JB |
245 | CORE_ADDR dwarf_regnum = dwarf_expr_fetch (ctx, 0); |
246 | int gdb_regnum = DWARF2_REG_TO_REGNUM (dwarf_regnum); | |
247 | retval = value_from_register (SYMBOL_TYPE (var), gdb_regnum, frame); | |
051caad9 | 248 | } |
4c2df51b DJ |
249 | else |
250 | { | |
5ca2e327 JB |
251 | CORE_ADDR address = dwarf_expr_fetch (ctx, 0); |
252 | ||
61fbb938 | 253 | retval = allocate_value (SYMBOL_TYPE (var)); |
4c2df51b | 254 | VALUE_LVAL (retval) = lval_memory; |
dfa52d88 | 255 | set_value_lazy (retval, 1); |
5ca2e327 | 256 | VALUE_ADDRESS (retval) = address; |
4c2df51b DJ |
257 | } |
258 | ||
42be36b3 CT |
259 | set_value_initialized (retval, ctx->initialized); |
260 | ||
4c2df51b DJ |
261 | free_dwarf_expr_context (ctx); |
262 | ||
263 | return retval; | |
264 | } | |
265 | ||
266 | ||
267 | ||
268 | ||
269 | \f | |
270 | /* Helper functions and baton for dwarf2_loc_desc_needs_frame. */ | |
271 | ||
272 | struct needs_frame_baton | |
273 | { | |
274 | int needs_frame; | |
275 | }; | |
276 | ||
277 | /* Reads from registers do require a frame. */ | |
278 | static CORE_ADDR | |
61fbb938 | 279 | needs_frame_read_reg (void *baton, int regnum) |
4c2df51b DJ |
280 | { |
281 | struct needs_frame_baton *nf_baton = baton; | |
282 | nf_baton->needs_frame = 1; | |
283 | return 1; | |
284 | } | |
285 | ||
286 | /* Reads from memory do not require a frame. */ | |
287 | static void | |
852483bc | 288 | needs_frame_read_mem (void *baton, gdb_byte *buf, CORE_ADDR addr, size_t len) |
4c2df51b DJ |
289 | { |
290 | memset (buf, 0, len); | |
291 | } | |
292 | ||
293 | /* Frame-relative accesses do require a frame. */ | |
294 | static void | |
852483bc | 295 | needs_frame_frame_base (void *baton, gdb_byte **start, size_t * length) |
4c2df51b | 296 | { |
852483bc | 297 | static gdb_byte lit0 = DW_OP_lit0; |
4c2df51b DJ |
298 | struct needs_frame_baton *nf_baton = baton; |
299 | ||
300 | *start = &lit0; | |
301 | *length = 1; | |
302 | ||
303 | nf_baton->needs_frame = 1; | |
304 | } | |
305 | ||
306 | /* Thread-local accesses do require a frame. */ | |
307 | static CORE_ADDR | |
308 | needs_frame_tls_address (void *baton, CORE_ADDR offset) | |
309 | { | |
310 | struct needs_frame_baton *nf_baton = baton; | |
311 | nf_baton->needs_frame = 1; | |
312 | return 1; | |
313 | } | |
314 | ||
315 | /* Return non-zero iff the location expression at DATA (length SIZE) | |
316 | requires a frame to evaluate. */ | |
317 | ||
318 | static int | |
852483bc | 319 | dwarf2_loc_desc_needs_frame (gdb_byte *data, unsigned short size) |
4c2df51b DJ |
320 | { |
321 | struct needs_frame_baton baton; | |
322 | struct dwarf_expr_context *ctx; | |
f630a401 | 323 | int in_reg; |
4c2df51b DJ |
324 | |
325 | baton.needs_frame = 0; | |
326 | ||
327 | ctx = new_dwarf_expr_context (); | |
328 | ctx->baton = &baton; | |
329 | ctx->read_reg = needs_frame_read_reg; | |
330 | ctx->read_mem = needs_frame_read_mem; | |
331 | ctx->get_frame_base = needs_frame_frame_base; | |
332 | ctx->get_tls_address = needs_frame_tls_address; | |
333 | ||
334 | dwarf_expr_eval (ctx, data, size); | |
335 | ||
f630a401 DJ |
336 | in_reg = ctx->in_reg; |
337 | ||
87808bd6 JB |
338 | if (ctx->num_pieces > 0) |
339 | { | |
340 | int i; | |
341 | ||
342 | /* If the location has several pieces, and any of them are in | |
343 | registers, then we will need a frame to fetch them from. */ | |
344 | for (i = 0; i < ctx->num_pieces; i++) | |
345 | if (ctx->pieces[i].in_reg) | |
346 | in_reg = 1; | |
347 | } | |
348 | ||
4c2df51b DJ |
349 | free_dwarf_expr_context (ctx); |
350 | ||
f630a401 | 351 | return baton.needs_frame || in_reg; |
4c2df51b DJ |
352 | } |
353 | ||
0d53c4c4 | 354 | static void |
852483bc MK |
355 | dwarf2_tracepoint_var_ref (struct symbol *symbol, struct agent_expr *ax, |
356 | struct axs_value *value, gdb_byte *data, | |
0d53c4c4 DJ |
357 | int size) |
358 | { | |
359 | if (size == 0) | |
8a3fe4f8 | 360 | error (_("Symbol \"%s\" has been optimized out."), |
0d53c4c4 DJ |
361 | SYMBOL_PRINT_NAME (symbol)); |
362 | ||
363 | if (size == 1 | |
364 | && data[0] >= DW_OP_reg0 | |
365 | && data[0] <= DW_OP_reg31) | |
366 | { | |
367 | value->kind = axs_lvalue_register; | |
368 | value->u.reg = data[0] - DW_OP_reg0; | |
369 | } | |
370 | else if (data[0] == DW_OP_regx) | |
371 | { | |
372 | ULONGEST reg; | |
373 | read_uleb128 (data + 1, data + size, ®); | |
374 | value->kind = axs_lvalue_register; | |
375 | value->u.reg = reg; | |
376 | } | |
377 | else if (data[0] == DW_OP_fbreg) | |
378 | { | |
379 | /* And this is worse than just minimal; we should honor the frame base | |
380 | as above. */ | |
381 | int frame_reg; | |
382 | LONGEST frame_offset; | |
852483bc | 383 | gdb_byte *buf_end; |
0d53c4c4 DJ |
384 | |
385 | buf_end = read_sleb128 (data + 1, data + size, &frame_offset); | |
386 | if (buf_end != data + size) | |
8a3fe4f8 | 387 | error (_("Unexpected opcode after DW_OP_fbreg for symbol \"%s\"."), |
0d53c4c4 | 388 | SYMBOL_PRINT_NAME (symbol)); |
4c2df51b | 389 | |
0d53c4c4 DJ |
390 | TARGET_VIRTUAL_FRAME_POINTER (ax->scope, &frame_reg, &frame_offset); |
391 | ax_reg (ax, frame_reg); | |
392 | ax_const_l (ax, frame_offset); | |
393 | ax_simple (ax, aop_add); | |
4c2df51b | 394 | |
9c238357 RC |
395 | value->kind = axs_lvalue_memory; |
396 | } | |
397 | else if (data[0] >= DW_OP_breg0 | |
398 | && data[0] <= DW_OP_breg31) | |
399 | { | |
400 | unsigned int reg; | |
401 | LONGEST offset; | |
402 | gdb_byte *buf_end; | |
403 | ||
404 | reg = data[0] - DW_OP_breg0; | |
405 | buf_end = read_sleb128 (data + 1, data + size, &offset); | |
406 | if (buf_end != data + size) | |
407 | error (_("Unexpected opcode after DW_OP_breg%u for symbol \"%s\"."), | |
408 | reg, SYMBOL_PRINT_NAME (symbol)); | |
409 | ||
410 | ax_reg (ax, reg); | |
411 | ax_const_l (ax, offset); | |
0d53c4c4 | 412 | ax_simple (ax, aop_add); |
9c238357 | 413 | |
0d53c4c4 DJ |
414 | value->kind = axs_lvalue_memory; |
415 | } | |
416 | else | |
9c238357 RC |
417 | error (_("Unsupported DWARF opcode 0x%x in the location of \"%s\"."), |
418 | data[0], SYMBOL_PRINT_NAME (symbol)); | |
0d53c4c4 | 419 | } |
4c2df51b DJ |
420 | \f |
421 | /* Return the value of SYMBOL in FRAME using the DWARF-2 expression | |
422 | evaluator to calculate the location. */ | |
423 | static struct value * | |
424 | locexpr_read_variable (struct symbol *symbol, struct frame_info *frame) | |
425 | { | |
426 | struct dwarf2_locexpr_baton *dlbaton = SYMBOL_LOCATION_BATON (symbol); | |
427 | struct value *val; | |
428 | val = dwarf2_evaluate_loc_desc (symbol, frame, dlbaton->data, dlbaton->size, | |
429 | dlbaton->objfile); | |
430 | ||
431 | return val; | |
432 | } | |
433 | ||
434 | /* Return non-zero iff we need a frame to evaluate SYMBOL. */ | |
435 | static int | |
436 | locexpr_read_needs_frame (struct symbol *symbol) | |
437 | { | |
438 | struct dwarf2_locexpr_baton *dlbaton = SYMBOL_LOCATION_BATON (symbol); | |
439 | return dwarf2_loc_desc_needs_frame (dlbaton->data, dlbaton->size); | |
440 | } | |
441 | ||
442 | /* Print a natural-language description of SYMBOL to STREAM. */ | |
443 | static int | |
444 | locexpr_describe_location (struct symbol *symbol, struct ui_file *stream) | |
445 | { | |
446 | /* FIXME: be more extensive. */ | |
447 | struct dwarf2_locexpr_baton *dlbaton = SYMBOL_LOCATION_BATON (symbol); | |
448 | ||
449 | if (dlbaton->size == 1 | |
450 | && dlbaton->data[0] >= DW_OP_reg0 | |
451 | && dlbaton->data[0] <= DW_OP_reg31) | |
452 | { | |
453 | int regno = DWARF2_REG_TO_REGNUM (dlbaton->data[0] - DW_OP_reg0); | |
454 | fprintf_filtered (stream, | |
455 | "a variable in register %s", REGISTER_NAME (regno)); | |
456 | return 1; | |
457 | } | |
458 | ||
c3228f12 EZ |
459 | /* The location expression for a TLS variable looks like this (on a |
460 | 64-bit LE machine): | |
461 | ||
462 | DW_AT_location : 10 byte block: 3 4 0 0 0 0 0 0 0 e0 | |
463 | (DW_OP_addr: 4; DW_OP_GNU_push_tls_address) | |
464 | ||
465 | 0x3 is the encoding for DW_OP_addr, which has an operand as long | |
466 | as the size of an address on the target machine (here is 8 | |
467 | bytes). 0xe0 is the encoding for DW_OP_GNU_push_tls_address. | |
468 | The operand represents the offset at which the variable is within | |
469 | the thread local storage. */ | |
470 | ||
471 | if (dlbaton->size > 1 | |
472 | && dlbaton->data[dlbaton->size - 1] == DW_OP_GNU_push_tls_address) | |
473 | if (dlbaton->data[0] == DW_OP_addr) | |
474 | { | |
475 | int bytes_read; | |
476 | CORE_ADDR offset = dwarf2_read_address (&dlbaton->data[1], | |
c193f044 | 477 | &dlbaton->data[dlbaton->size - 1], |
c3228f12 EZ |
478 | &bytes_read); |
479 | fprintf_filtered (stream, | |
32ffcbed | 480 | "a thread-local variable at offset %s in the " |
c3228f12 EZ |
481 | "thread-local storage for `%s'", |
482 | paddr_nz (offset), dlbaton->objfile->name); | |
483 | return 1; | |
484 | } | |
485 | ||
486 | ||
4c2df51b DJ |
487 | fprintf_filtered (stream, |
488 | "a variable with complex or multiple locations (DWARF2)"); | |
489 | return 1; | |
490 | } | |
491 | ||
a55cc764 DJ |
492 | |
493 | /* Describe the location of SYMBOL as an agent value in VALUE, generating | |
494 | any necessary bytecode in AX. | |
495 | ||
496 | NOTE drow/2003-02-26: This function is extremely minimal, because | |
497 | doing it correctly is extremely complicated and there is no | |
498 | publicly available stub with tracepoint support for me to test | |
499 | against. When there is one this function should be revisited. */ | |
500 | ||
0d53c4c4 | 501 | static void |
a55cc764 DJ |
502 | locexpr_tracepoint_var_ref (struct symbol * symbol, struct agent_expr * ax, |
503 | struct axs_value * value) | |
504 | { | |
505 | struct dwarf2_locexpr_baton *dlbaton = SYMBOL_LOCATION_BATON (symbol); | |
506 | ||
0d53c4c4 | 507 | dwarf2_tracepoint_var_ref (symbol, ax, value, dlbaton->data, dlbaton->size); |
a55cc764 DJ |
508 | } |
509 | ||
4c2df51b DJ |
510 | /* The set of location functions used with the DWARF-2 expression |
511 | evaluator. */ | |
a67af2b9 | 512 | const struct symbol_ops dwarf2_locexpr_funcs = { |
4c2df51b DJ |
513 | locexpr_read_variable, |
514 | locexpr_read_needs_frame, | |
515 | locexpr_describe_location, | |
a55cc764 | 516 | locexpr_tracepoint_var_ref |
4c2df51b | 517 | }; |
0d53c4c4 DJ |
518 | |
519 | ||
520 | /* Wrapper functions for location lists. These generally find | |
521 | the appropriate location expression and call something above. */ | |
522 | ||
523 | /* Return the value of SYMBOL in FRAME using the DWARF-2 expression | |
524 | evaluator to calculate the location. */ | |
525 | static struct value * | |
526 | loclist_read_variable (struct symbol *symbol, struct frame_info *frame) | |
527 | { | |
528 | struct dwarf2_loclist_baton *dlbaton = SYMBOL_LOCATION_BATON (symbol); | |
529 | struct value *val; | |
852483bc | 530 | gdb_byte *data; |
b6b08ebf | 531 | size_t size; |
0d53c4c4 DJ |
532 | |
533 | data = find_location_expression (dlbaton, &size, | |
22c6caba JW |
534 | frame ? get_frame_address_in_block (frame) |
535 | : 0); | |
0d53c4c4 | 536 | if (data == NULL) |
806048c6 DJ |
537 | { |
538 | val = allocate_value (SYMBOL_TYPE (symbol)); | |
539 | VALUE_LVAL (val) = not_lval; | |
540 | set_value_optimized_out (val, 1); | |
541 | } | |
542 | else | |
543 | val = dwarf2_evaluate_loc_desc (symbol, frame, data, size, | |
544 | dlbaton->objfile); | |
0d53c4c4 DJ |
545 | |
546 | return val; | |
547 | } | |
548 | ||
549 | /* Return non-zero iff we need a frame to evaluate SYMBOL. */ | |
550 | static int | |
551 | loclist_read_needs_frame (struct symbol *symbol) | |
552 | { | |
553 | /* If there's a location list, then assume we need to have a frame | |
554 | to choose the appropriate location expression. With tracking of | |
555 | global variables this is not necessarily true, but such tracking | |
556 | is disabled in GCC at the moment until we figure out how to | |
557 | represent it. */ | |
558 | ||
559 | return 1; | |
560 | } | |
561 | ||
562 | /* Print a natural-language description of SYMBOL to STREAM. */ | |
563 | static int | |
564 | loclist_describe_location (struct symbol *symbol, struct ui_file *stream) | |
565 | { | |
566 | /* FIXME: Could print the entire list of locations. */ | |
567 | fprintf_filtered (stream, "a variable with multiple locations"); | |
568 | return 1; | |
569 | } | |
570 | ||
571 | /* Describe the location of SYMBOL as an agent value in VALUE, generating | |
572 | any necessary bytecode in AX. */ | |
573 | static void | |
574 | loclist_tracepoint_var_ref (struct symbol * symbol, struct agent_expr * ax, | |
575 | struct axs_value * value) | |
576 | { | |
577 | struct dwarf2_loclist_baton *dlbaton = SYMBOL_LOCATION_BATON (symbol); | |
852483bc | 578 | gdb_byte *data; |
b6b08ebf | 579 | size_t size; |
0d53c4c4 DJ |
580 | |
581 | data = find_location_expression (dlbaton, &size, ax->scope); | |
582 | if (data == NULL) | |
8a3fe4f8 | 583 | error (_("Variable \"%s\" is not available."), SYMBOL_NATURAL_NAME (symbol)); |
0d53c4c4 DJ |
584 | |
585 | dwarf2_tracepoint_var_ref (symbol, ax, value, data, size); | |
586 | } | |
587 | ||
588 | /* The set of location functions used with the DWARF-2 expression | |
589 | evaluator and location lists. */ | |
a67af2b9 | 590 | const struct symbol_ops dwarf2_loclist_funcs = { |
0d53c4c4 DJ |
591 | loclist_read_variable, |
592 | loclist_read_needs_frame, | |
593 | loclist_describe_location, | |
594 | loclist_tracepoint_var_ref | |
595 | }; |