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852483bc MK |
1 | /* DWARF 2 Expression Evaluator. |
2 | ||
618f726f | 3 | Copyright (C) 2001-2016 Free Software Foundation, Inc. |
852483bc MK |
4 | |
5 | Contributed by Daniel Berlin <dan@dberlin.org>. | |
6 | ||
4c2df51b DJ |
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 | |
a9762ec7 | 11 | the Free Software Foundation; either version 3 of the License, or |
4c2df51b DJ |
12 | (at your option) any later version. |
13 | ||
14 | This program is distributed in the hope that it will be useful, | |
15 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
16 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
17 | GNU General Public License for more details. | |
18 | ||
19 | You should have received a copy of the GNU General Public License | |
a9762ec7 | 20 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ |
4c2df51b DJ |
21 | |
22 | #if !defined (DWARF2EXPR_H) | |
23 | #define DWARF2EXPR_H | |
24 | ||
f664829e | 25 | #include "leb128.h" |
836bf454 | 26 | #include "gdbtypes.h" |
f664829e | 27 | |
cec03d70 TT |
28 | /* The location of a value. */ |
29 | enum dwarf_value_location | |
30 | { | |
44353522 DE |
31 | /* The piece is in memory. |
32 | The value on the dwarf stack is its address. */ | |
cec03d70 | 33 | DWARF_VALUE_MEMORY, |
44353522 DE |
34 | |
35 | /* The piece is in a register. | |
36 | The value on the dwarf stack is the register number. */ | |
cec03d70 | 37 | DWARF_VALUE_REGISTER, |
44353522 DE |
38 | |
39 | /* The piece is on the dwarf stack. */ | |
cec03d70 | 40 | DWARF_VALUE_STACK, |
44353522 | 41 | |
cec03d70 | 42 | /* The piece is a literal. */ |
cb826367 TT |
43 | DWARF_VALUE_LITERAL, |
44 | ||
45 | /* The piece was optimized out. */ | |
8cf6f0b1 TT |
46 | DWARF_VALUE_OPTIMIZED_OUT, |
47 | ||
48 | /* The piece is an implicit pointer. */ | |
49 | DWARF_VALUE_IMPLICIT_POINTER | |
cec03d70 TT |
50 | }; |
51 | ||
44353522 DE |
52 | /* The dwarf expression stack. */ |
53 | ||
54 | struct dwarf_stack_value | |
55 | { | |
8a9b8146 | 56 | struct value *value; |
44353522 DE |
57 | |
58 | /* Non-zero if the piece is in memory and is known to be | |
59 | on the program's stack. It is always ok to set this to zero. | |
60 | This is used, for example, to optimize memory access from the target. | |
61 | It can vastly speed up backtraces on long latency connections when | |
62 | "set stack-cache on". */ | |
63 | int in_stack_memory; | |
64 | }; | |
65 | ||
4c2df51b DJ |
66 | /* The expression evaluator works with a dwarf_expr_context, describing |
67 | its current state and its callbacks. */ | |
68 | struct dwarf_expr_context | |
69 | { | |
718b9626 TT |
70 | dwarf_expr_context (); |
71 | ~dwarf_expr_context (); | |
72 | ||
595d2e30 TT |
73 | void push_address (CORE_ADDR value, int in_stack_memory); |
74 | void eval (const gdb_byte *addr, size_t len); | |
75 | struct value *fetch (int n); | |
76 | CORE_ADDR fetch_address (int n); | |
77 | int fetch_in_stack_memory (int n); | |
78 | ||
4c2df51b | 79 | /* The stack of values, allocated with xmalloc. */ |
44353522 | 80 | struct dwarf_stack_value *stack; |
4c2df51b DJ |
81 | |
82 | /* The number of values currently pushed on the stack, and the | |
83 | number of elements allocated to the stack. */ | |
84 | int stack_len, stack_allocated; | |
85 | ||
f7fd4728 UW |
86 | /* Target architecture to use for address operations. */ |
87 | struct gdbarch *gdbarch; | |
88 | ||
ae0d2f24 UW |
89 | /* Target address size in bytes. */ |
90 | int addr_size; | |
91 | ||
181cebd4 JK |
92 | /* DW_FORM_ref_addr size in bytes. If -1 DWARF is executed from a frame |
93 | context and operations depending on DW_FORM_ref_addr are not allowed. */ | |
94 | int ref_addr_size; | |
95 | ||
49f6c839 | 96 | /* Offset used to relocate DW_OP_addr and DW_OP_GNU_addr_index arguments. */ |
ac56253d TT |
97 | CORE_ADDR offset; |
98 | ||
4c2df51b DJ |
99 | /* The current depth of dwarf expression recursion, via DW_OP_call*, |
100 | DW_OP_fbreg, DW_OP_push_object_address, etc., and the maximum | |
101 | depth we'll tolerate before raising an error. */ | |
102 | int recursion_depth, max_recursion_depth; | |
103 | ||
cec03d70 TT |
104 | /* Location of the value. */ |
105 | enum dwarf_value_location location; | |
106 | ||
766062f6 | 107 | /* For DWARF_VALUE_LITERAL, the current literal value's length and |
8cf6f0b1 | 108 | data. For DWARF_VALUE_IMPLICIT_POINTER, LEN is the offset of the |
8b9737bf | 109 | target DIE of sect_offset kind. */ |
cec03d70 | 110 | ULONGEST len; |
0d45f56e | 111 | const gdb_byte *data; |
87808bd6 | 112 | |
42be36b3 CT |
113 | /* Initialization status of variable: Non-zero if variable has been |
114 | initialized; zero otherwise. */ | |
115 | int initialized; | |
116 | ||
87808bd6 JB |
117 | /* An array of pieces. PIECES points to its first element; |
118 | NUM_PIECES is its length. | |
119 | ||
120 | Each time DW_OP_piece is executed, we add a new element to the | |
121 | end of this array, recording the current top of the stack, the | |
cec03d70 | 122 | current location, and the size given as the operand to |
44353522 | 123 | DW_OP_piece. We then pop the top value from the stack, reset the |
cec03d70 | 124 | location, and resume evaluation. |
87808bd6 JB |
125 | |
126 | The Dwarf spec doesn't say whether DW_OP_piece pops the top value | |
127 | from the stack. We do, ensuring that clients of this interface | |
128 | expecting to see a value left on the top of the stack (say, code | |
129 | evaluating frame base expressions or CFA's specified with | |
130 | DW_CFA_def_cfa_expression) will get an error if the expression | |
131 | actually marks all the values it computes as pieces. | |
132 | ||
133 | If an expression never uses DW_OP_piece, num_pieces will be zero. | |
134 | (It would be nice to present these cases as expressions yielding | |
cec03d70 TT |
135 | a single piece, so that callers need not distinguish between the |
136 | no-DW_OP_piece and one-DW_OP_piece cases. But expressions with | |
137 | no DW_OP_piece operations have no value to place in a piece's | |
138 | 'size' field; the size comes from the surrounding data. So the | |
139 | two cases need to be handled separately.) */ | |
87808bd6 JB |
140 | int num_pieces; |
141 | struct dwarf_expr_piece *pieces; | |
595d2e30 | 142 | |
192ca6d8 TT |
143 | /* Return the value of register number REGNUM (a DWARF register number), |
144 | read as an address. */ | |
145 | virtual CORE_ADDR read_addr_from_reg (int regnum) = 0; | |
146 | ||
147 | /* Return a value of type TYPE, stored in register number REGNUM | |
148 | of the frame associated to the given BATON. | |
149 | ||
150 | REGNUM is a DWARF register number. */ | |
151 | virtual struct value *get_reg_value (struct type *type, int regnum) = 0; | |
152 | ||
153 | /* Read LENGTH bytes at ADDR into BUF. */ | |
154 | virtual void read_mem (gdb_byte *buf, CORE_ADDR addr, size_t length) = 0; | |
155 | ||
156 | /* Return the location expression for the frame base attribute, in | |
157 | START and LENGTH. The result must be live until the current | |
158 | expression evaluation is complete. */ | |
159 | virtual void get_frame_base (const gdb_byte **start, size_t *length) | |
160 | { | |
161 | error (_("%s is invalid in this context"), "DW_OP_fbreg"); | |
162 | } | |
163 | ||
164 | /* Return the CFA for the frame. */ | |
165 | virtual CORE_ADDR get_frame_cfa () | |
166 | { | |
167 | error (_("%s is invalid in this context"), "DW_OP_call_frame_cfa"); | |
168 | } | |
169 | ||
170 | /* Return the PC for the frame. */ | |
171 | virtual CORE_ADDR get_frame_pc () | |
172 | { | |
173 | error (_("%s is invalid in this context"), "DW_OP_GNU_implicit_pointer"); | |
174 | } | |
175 | ||
176 | /* Return the thread-local storage address for | |
177 | DW_OP_GNU_push_tls_address or DW_OP_form_tls_address. */ | |
178 | virtual CORE_ADDR get_tls_address (CORE_ADDR offset) | |
179 | { | |
180 | error (_("%s is invalid in this context"), "DW_OP_form_tls_address"); | |
181 | } | |
182 | ||
183 | /* Execute DW_AT_location expression for the DWARF expression | |
184 | subroutine in the DIE at DIE_OFFSET in the CU. Do not touch | |
185 | STACK while it being passed to and returned from the called DWARF | |
186 | subroutine. */ | |
187 | virtual void dwarf_call (cu_offset die_offset) | |
188 | { | |
189 | error (_("%s is invalid in this context"), "DW_OP_call*"); | |
190 | } | |
191 | ||
192 | /* Return the base type given by the indicated DIE. This can throw | |
193 | an exception if the DIE is invalid or does not represent a base | |
194 | type. If can also be NULL in the special case where the | |
195 | callbacks are not performing evaluation, and thus it is | |
196 | meaningful to substitute a stub type of the correct size. */ | |
197 | virtual struct type *impl_get_base_type (cu_offset die) | |
198 | { | |
199 | /* Anything will do. */ | |
200 | return builtin_type (this->gdbarch)->builtin_int; | |
201 | } | |
202 | ||
203 | /* Push on DWARF stack an entry evaluated for DW_TAG_GNU_call_site's | |
204 | parameter matching KIND and KIND_U at the caller of specified BATON. | |
205 | If DEREF_SIZE is not -1 then use DW_AT_GNU_call_site_data_value instead of | |
206 | DW_AT_GNU_call_site_value. */ | |
207 | virtual void push_dwarf_reg_entry_value (enum call_site_parameter_kind kind, | |
208 | union call_site_parameter_u kind_u, | |
209 | int deref_size) | |
210 | { | |
211 | internal_error (__FILE__, __LINE__, | |
212 | _("Support for DW_OP_GNU_entry_value is unimplemented")); | |
213 | } | |
214 | ||
215 | /* Return the address indexed by DW_OP_GNU_addr_index. | |
216 | This can throw an exception if the index is out of range. */ | |
217 | virtual CORE_ADDR get_addr_index (unsigned int index) | |
218 | { | |
219 | error (_("%s is invalid in this context"), "DW_OP_GNU_addr_index"); | |
220 | } | |
221 | ||
222 | /* Return the `object address' for DW_OP_push_object_address. */ | |
223 | virtual CORE_ADDR get_object_address () | |
224 | { | |
225 | internal_error (__FILE__, __LINE__, | |
226 | _("Support for DW_OP_push_object_address " | |
227 | "is unimplemented")); | |
228 | } | |
229 | ||
595d2e30 TT |
230 | private: |
231 | ||
232 | struct type *address_type () const; | |
233 | void grow_stack (size_t need); | |
234 | void push (struct value *value, int in_stack_memory); | |
235 | int stack_empty_p () const; | |
236 | void add_piece (ULONGEST size, ULONGEST offset); | |
237 | struct type *get_base_type (cu_offset die, int size); | |
238 | void execute_stack_op (const gdb_byte *op_ptr, const gdb_byte *op_end); | |
239 | void pop (); | |
87808bd6 JB |
240 | }; |
241 | ||
242 | ||
d3b1e874 | 243 | /* A piece of an object, as recorded by DW_OP_piece or DW_OP_bit_piece. */ |
87808bd6 JB |
244 | struct dwarf_expr_piece |
245 | { | |
cec03d70 TT |
246 | enum dwarf_value_location location; |
247 | ||
248 | union | |
249 | { | |
44353522 DE |
250 | struct |
251 | { | |
f2c7657e UW |
252 | /* This piece's address, for DWARF_VALUE_MEMORY pieces. */ |
253 | CORE_ADDR addr; | |
44353522 DE |
254 | /* Non-zero if the piece is known to be in memory and on |
255 | the program's stack. */ | |
256 | int in_stack_memory; | |
f2c7657e UW |
257 | } mem; |
258 | ||
8a9b8146 TT |
259 | /* The piece's register number, for DWARF_VALUE_REGISTER pieces. */ |
260 | int regno; | |
261 | ||
262 | /* The piece's literal value, for DWARF_VALUE_STACK pieces. */ | |
263 | struct value *value; | |
cec03d70 TT |
264 | |
265 | struct | |
266 | { | |
f2c7657e UW |
267 | /* A pointer to the data making up this piece, |
268 | for DWARF_VALUE_LITERAL pieces. */ | |
0d45f56e | 269 | const gdb_byte *data; |
cec03d70 TT |
270 | /* The length of the available data. */ |
271 | ULONGEST length; | |
272 | } literal; | |
8cf6f0b1 TT |
273 | |
274 | /* Used for DWARF_VALUE_IMPLICIT_POINTER. */ | |
275 | struct | |
276 | { | |
277 | /* The referent DIE from DW_OP_GNU_implicit_pointer. */ | |
8b9737bf | 278 | sect_offset die; |
8cf6f0b1 TT |
279 | /* The byte offset into the resulting data. */ |
280 | LONGEST offset; | |
281 | } ptr; | |
cec03d70 | 282 | } v; |
87808bd6 | 283 | |
d3b1e874 | 284 | /* The length of the piece, in bits. */ |
87808bd6 | 285 | ULONGEST size; |
d3b1e874 TT |
286 | /* The piece offset, in bits. */ |
287 | ULONGEST offset; | |
4c2df51b DJ |
288 | }; |
289 | ||
3cf03773 TT |
290 | void dwarf_expr_require_composition (const gdb_byte *, const gdb_byte *, |
291 | const char *); | |
292 | ||
8e3b41a9 | 293 | int dwarf_block_to_dwarf_reg (const gdb_byte *buf, const gdb_byte *buf_end); |
523f3620 | 294 | |
a471c594 JK |
295 | int dwarf_block_to_dwarf_reg_deref (const gdb_byte *buf, |
296 | const gdb_byte *buf_end, | |
297 | CORE_ADDR *deref_size_return); | |
298 | ||
e18b2753 JK |
299 | int dwarf_block_to_fb_offset (const gdb_byte *buf, const gdb_byte *buf_end, |
300 | CORE_ADDR *fb_offset_return); | |
301 | ||
302 | int dwarf_block_to_sp_offset (struct gdbarch *gdbarch, const gdb_byte *buf, | |
303 | const gdb_byte *buf_end, | |
304 | CORE_ADDR *sp_offset_return); | |
305 | ||
f664829e DE |
306 | /* Wrappers around the leb128 reader routines to simplify them for our |
307 | purposes. */ | |
308 | ||
309 | static inline const gdb_byte * | |
310 | gdb_read_uleb128 (const gdb_byte *buf, const gdb_byte *buf_end, | |
9fccedf7 | 311 | uint64_t *r) |
f664829e | 312 | { |
9fccedf7 | 313 | size_t bytes_read = read_uleb128_to_uint64 (buf, buf_end, r); |
f664829e DE |
314 | |
315 | if (bytes_read == 0) | |
316 | return NULL; | |
317 | return buf + bytes_read; | |
318 | } | |
319 | ||
320 | static inline const gdb_byte * | |
321 | gdb_read_sleb128 (const gdb_byte *buf, const gdb_byte *buf_end, | |
9fccedf7 | 322 | int64_t *r) |
f664829e | 323 | { |
9fccedf7 | 324 | size_t bytes_read = read_sleb128_to_int64 (buf, buf_end, r); |
f664829e DE |
325 | |
326 | if (bytes_read == 0) | |
327 | return NULL; | |
328 | return buf + bytes_read; | |
329 | } | |
330 | ||
331 | static inline const gdb_byte * | |
332 | gdb_skip_leb128 (const gdb_byte *buf, const gdb_byte *buf_end) | |
333 | { | |
334 | size_t bytes_read = skip_leb128 (buf, buf_end); | |
335 | ||
336 | if (bytes_read == 0) | |
337 | return NULL; | |
338 | return buf + bytes_read; | |
339 | } | |
340 | ||
341 | extern const gdb_byte *safe_read_uleb128 (const gdb_byte *buf, | |
342 | const gdb_byte *buf_end, | |
9fccedf7 | 343 | uint64_t *r); |
f664829e DE |
344 | |
345 | extern const gdb_byte *safe_read_sleb128 (const gdb_byte *buf, | |
346 | const gdb_byte *buf_end, | |
9fccedf7 | 347 | int64_t *r); |
f664829e DE |
348 | |
349 | extern const gdb_byte *safe_skip_leb128 (const gdb_byte *buf, | |
350 | const gdb_byte *buf_end); | |
351 | ||
852483bc | 352 | #endif /* dwarf2expr.h */ |