1 /* DWARF 2 Expression Evaluator.
3 Copyright (C) 2001-2003, 2005, 2007-2012 Free Software Foundation,
6 Contributed by Daniel Berlin <dan@dberlin.org>.
8 This file is part of GDB.
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
12 the Free Software Foundation; either version 3 of the License, or
13 (at your option) any later version.
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.
20 You should have received a copy of the GNU General Public License
21 along with this program. If not, see <http://www.gnu.org/licenses/>. */
23 #if !defined (DWARF2EXPR_H)
29 struct dwarf_expr_context
;
31 /* Virtual method table for struct dwarf_expr_context below. */
33 struct dwarf_expr_context_funcs
35 /* Return the value of register number REGNUM. */
36 CORE_ADDR (*read_reg
) (void *baton
, int regnum
);
38 /* Read LENGTH bytes at ADDR into BUF. */
39 void (*read_mem
) (void *baton
, gdb_byte
*buf
, CORE_ADDR addr
, size_t length
);
41 /* Return the location expression for the frame base attribute, in
42 START and LENGTH. The result must be live until the current
43 expression evaluation is complete. */
44 void (*get_frame_base
) (void *baton
, const gdb_byte
**start
, size_t *length
);
46 /* Return the CFA for the frame. */
47 CORE_ADDR (*get_frame_cfa
) (void *baton
);
49 /* Return the PC for the frame. */
50 CORE_ADDR (*get_frame_pc
) (void *baton
);
52 /* Return the thread-local storage address for
53 DW_OP_GNU_push_tls_address. */
54 CORE_ADDR (*get_tls_address
) (void *baton
, CORE_ADDR offset
);
56 /* Execute DW_AT_location expression for the DWARF expression subroutine in
57 the DIE at DIE_OFFSET in the CU from CTX. Do not touch STACK while it
58 being passed to and returned from the called DWARF subroutine. */
59 void (*dwarf_call
) (struct dwarf_expr_context
*ctx
, cu_offset die_offset
);
61 /* Return the base type given by the indicated DIE. This can throw
62 an exception if the DIE is invalid or does not represent a base
63 type. If can also be NULL in the special case where the
64 callbacks are not performing evaluation, and thus it is
65 meaningful to substitute a stub type of the correct size. */
66 struct type
*(*get_base_type
) (struct dwarf_expr_context
*ctx
, cu_offset die
);
68 /* Push on DWARF stack an entry evaluated for DW_TAG_GNU_call_site's
69 parameter matching KIND and KIND_U at the caller of specified BATON.
70 If DEREF_SIZE is not -1 then use DW_AT_GNU_call_site_data_value instead of
71 DW_AT_GNU_call_site_value. */
72 void (*push_dwarf_reg_entry_value
) (struct dwarf_expr_context
*ctx
,
73 enum call_site_parameter_kind kind
,
74 union call_site_parameter_u kind_u
,
77 /* Return the address indexed by DW_OP_GNU_addr_index.
78 This can throw an exception if the index is out of range. */
79 CORE_ADDR (*get_addr_index
) (void *baton
, unsigned int index
);
82 /* Not yet implemented. */
84 /* Return the `object address' for DW_OP_push_object_address. */
85 CORE_ADDR (*get_object_address
) (void *baton
);
89 /* The location of a value. */
90 enum dwarf_value_location
92 /* The piece is in memory.
93 The value on the dwarf stack is its address. */
96 /* The piece is in a register.
97 The value on the dwarf stack is the register number. */
100 /* The piece is on the dwarf stack. */
103 /* The piece is a literal. */
106 /* The piece was optimized out. */
107 DWARF_VALUE_OPTIMIZED_OUT
,
109 /* The piece is an implicit pointer. */
110 DWARF_VALUE_IMPLICIT_POINTER
113 /* The dwarf expression stack. */
115 struct dwarf_stack_value
119 /* Non-zero if the piece is in memory and is known to be
120 on the program's stack. It is always ok to set this to zero.
121 This is used, for example, to optimize memory access from the target.
122 It can vastly speed up backtraces on long latency connections when
123 "set stack-cache on". */
127 /* The expression evaluator works with a dwarf_expr_context, describing
128 its current state and its callbacks. */
129 struct dwarf_expr_context
131 /* The stack of values, allocated with xmalloc. */
132 struct dwarf_stack_value
*stack
;
134 /* The number of values currently pushed on the stack, and the
135 number of elements allocated to the stack. */
136 int stack_len
, stack_allocated
;
138 /* Target architecture to use for address operations. */
139 struct gdbarch
*gdbarch
;
141 /* Target address size in bytes. */
144 /* DW_FORM_ref_addr size in bytes. If -1 DWARF is executed from a frame
145 context and operations depending on DW_FORM_ref_addr are not allowed. */
148 /* Offset used to relocate DW_OP_addr and DW_OP_GNU_addr_index arguments. */
151 /* An opaque argument provided by the caller, which will be passed
152 to all of the callback functions. */
155 /* Callback functions. */
156 const struct dwarf_expr_context_funcs
*funcs
;
158 /* The current depth of dwarf expression recursion, via DW_OP_call*,
159 DW_OP_fbreg, DW_OP_push_object_address, etc., and the maximum
160 depth we'll tolerate before raising an error. */
161 int recursion_depth
, max_recursion_depth
;
163 /* Location of the value. */
164 enum dwarf_value_location location
;
166 /* For DWARF_VALUE_LITERAL, the current literal value's length and
167 data. For DWARF_VALUE_IMPLICIT_POINTER, LEN is the offset of the
168 target DIE of cu_offset kind. */
170 const gdb_byte
*data
;
172 /* Initialization status of variable: Non-zero if variable has been
173 initialized; zero otherwise. */
176 /* An array of pieces. PIECES points to its first element;
177 NUM_PIECES is its length.
179 Each time DW_OP_piece is executed, we add a new element to the
180 end of this array, recording the current top of the stack, the
181 current location, and the size given as the operand to
182 DW_OP_piece. We then pop the top value from the stack, reset the
183 location, and resume evaluation.
185 The Dwarf spec doesn't say whether DW_OP_piece pops the top value
186 from the stack. We do, ensuring that clients of this interface
187 expecting to see a value left on the top of the stack (say, code
188 evaluating frame base expressions or CFA's specified with
189 DW_CFA_def_cfa_expression) will get an error if the expression
190 actually marks all the values it computes as pieces.
192 If an expression never uses DW_OP_piece, num_pieces will be zero.
193 (It would be nice to present these cases as expressions yielding
194 a single piece, so that callers need not distinguish between the
195 no-DW_OP_piece and one-DW_OP_piece cases. But expressions with
196 no DW_OP_piece operations have no value to place in a piece's
197 'size' field; the size comes from the surrounding data. So the
198 two cases need to be handled separately.) */
200 struct dwarf_expr_piece
*pieces
;
204 /* A piece of an object, as recorded by DW_OP_piece or DW_OP_bit_piece. */
205 struct dwarf_expr_piece
207 enum dwarf_value_location location
;
213 /* This piece's address, for DWARF_VALUE_MEMORY pieces. */
215 /* Non-zero if the piece is known to be in memory and on
216 the program's stack. */
220 /* The piece's register number, for DWARF_VALUE_REGISTER pieces. */
223 /* The piece's literal value, for DWARF_VALUE_STACK pieces. */
228 /* A pointer to the data making up this piece,
229 for DWARF_VALUE_LITERAL pieces. */
230 const gdb_byte
*data
;
231 /* The length of the available data. */
235 /* Used for DWARF_VALUE_IMPLICIT_POINTER. */
238 /* The referent DIE from DW_OP_GNU_implicit_pointer. */
240 /* The byte offset into the resulting data. */
245 /* The length of the piece, in bits. */
247 /* The piece offset, in bits. */
251 struct dwarf_expr_context
*new_dwarf_expr_context (void);
252 void free_dwarf_expr_context (struct dwarf_expr_context
*ctx
);
254 make_cleanup_free_dwarf_expr_context (struct dwarf_expr_context
*ctx
);
256 void dwarf_expr_push_address (struct dwarf_expr_context
*ctx
,
258 int in_stack_memory
);
259 void dwarf_expr_eval (struct dwarf_expr_context
*ctx
, const gdb_byte
*addr
,
261 struct value
*dwarf_expr_fetch (struct dwarf_expr_context
*ctx
, int n
);
262 CORE_ADDR
dwarf_expr_fetch_address (struct dwarf_expr_context
*ctx
, int n
);
263 int dwarf_expr_fetch_in_stack_memory (struct dwarf_expr_context
*ctx
, int n
);
265 void dwarf_expr_require_composition (const gdb_byte
*, const gdb_byte
*,
268 /* Stub dwarf_expr_context_funcs implementations. */
270 void ctx_no_get_frame_base (void *baton
, const gdb_byte
**start
,
272 CORE_ADDR
ctx_no_get_frame_cfa (void *baton
);
273 CORE_ADDR
ctx_no_get_frame_pc (void *baton
);
274 CORE_ADDR
ctx_no_get_tls_address (void *baton
, CORE_ADDR offset
);
275 void ctx_no_dwarf_call (struct dwarf_expr_context
*ctx
, cu_offset die_offset
);
276 struct type
*ctx_no_get_base_type (struct dwarf_expr_context
*ctx
,
278 void ctx_no_push_dwarf_reg_entry_value (struct dwarf_expr_context
*ctx
,
279 enum call_site_parameter_kind kind
,
280 union call_site_parameter_u kind_u
,
282 CORE_ADDR
ctx_no_get_addr_index (void *baton
, unsigned int index
);
284 int dwarf_block_to_dwarf_reg (const gdb_byte
*buf
, const gdb_byte
*buf_end
);
286 int dwarf_block_to_dwarf_reg_deref (const gdb_byte
*buf
,
287 const gdb_byte
*buf_end
,
288 CORE_ADDR
*deref_size_return
);
290 int dwarf_block_to_fb_offset (const gdb_byte
*buf
, const gdb_byte
*buf_end
,
291 CORE_ADDR
*fb_offset_return
);
293 int dwarf_block_to_sp_offset (struct gdbarch
*gdbarch
, const gdb_byte
*buf
,
294 const gdb_byte
*buf_end
,
295 CORE_ADDR
*sp_offset_return
);
297 /* Wrappers around the leb128 reader routines to simplify them for our
300 static inline const gdb_byte
*
301 gdb_read_uleb128 (const gdb_byte
*buf
, const gdb_byte
*buf_end
,
304 size_t bytes_read
= read_uleb128_to_uint64 (buf
, buf_end
, r
);
308 return buf
+ bytes_read
;
311 static inline const gdb_byte
*
312 gdb_read_sleb128 (const gdb_byte
*buf
, const gdb_byte
*buf_end
,
315 size_t bytes_read
= read_sleb128_to_int64 (buf
, buf_end
, r
);
319 return buf
+ bytes_read
;
322 static inline const gdb_byte
*
323 gdb_skip_leb128 (const gdb_byte
*buf
, const gdb_byte
*buf_end
)
325 size_t bytes_read
= skip_leb128 (buf
, buf_end
);
329 return buf
+ bytes_read
;
332 extern const gdb_byte
*safe_read_uleb128 (const gdb_byte
*buf
,
333 const gdb_byte
*buf_end
,
336 extern const gdb_byte
*safe_read_sleb128 (const gdb_byte
*buf
,
337 const gdb_byte
*buf_end
,
340 extern const gdb_byte
*safe_skip_leb128 (const gdb_byte
*buf
,
341 const gdb_byte
*buf_end
);
343 #endif /* dwarf2expr.h */