1 /* DWARF 2 Expression Evaluator.
3 Copyright (C) 2001, 2002, 2003, 2005, 2007, 2008, 2009, 2010, 2011
4 Free Software Foundation, Inc.
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)
26 /* The location of a value. */
27 enum dwarf_value_location
29 /* The piece is in memory.
30 The value on the dwarf stack is its address. */
33 /* The piece is in a register.
34 The value on the dwarf stack is the register number. */
37 /* The piece is on the dwarf stack. */
40 /* The piece is a literal. */
43 /* The piece was optimized out. */
44 DWARF_VALUE_OPTIMIZED_OUT,
46 /* The piece is an implicit pointer. */
47 DWARF_VALUE_IMPLICIT_POINTER
50 /* The dwarf expression stack. */
52 struct dwarf_stack_value
56 /* Non-zero if the piece is in memory and is known to be
57 on the program's stack. It is always ok to set this to zero.
58 This is used, for example, to optimize memory access from the target.
59 It can vastly speed up backtraces on long latency connections when
60 "set stack-cache on". */
64 /* The expression evaluator works with a dwarf_expr_context, describing
65 its current state and its callbacks. */
66 struct dwarf_expr_context
68 /* The stack of values, allocated with xmalloc. */
69 struct dwarf_stack_value *stack;
71 /* The number of values currently pushed on the stack, and the
72 number of elements allocated to the stack. */
73 int stack_len, stack_allocated;
75 /* Target architecture to use for address operations. */
76 struct gdbarch *gdbarch;
78 /* Target address size in bytes. */
81 /* Offset used to relocate DW_OP_addr argument. */
84 /* An opaque argument provided by the caller, which will be passed
85 to all of the callback functions. */
88 /* Return the value of register number REGNUM. */
89 CORE_ADDR (*read_reg) (void *baton, int regnum);
91 /* Read LENGTH bytes at ADDR into BUF. */
92 void (*read_mem) (void *baton, gdb_byte *buf, CORE_ADDR addr, size_t length);
94 /* Return the location expression for the frame base attribute, in
95 START and LENGTH. The result must be live until the current
96 expression evaluation is complete. */
97 void (*get_frame_base) (void *baton, const gdb_byte **start, size_t *length);
99 /* Return the CFA for the frame. */
100 CORE_ADDR (*get_frame_cfa) (void *baton);
102 /* Return the PC for the frame. */
103 CORE_ADDR (*get_frame_pc) (void *baton);
105 /* Return the thread-local storage address for
106 DW_OP_GNU_push_tls_address. */
107 CORE_ADDR (*get_tls_address) (void *baton, CORE_ADDR offset);
109 /* Execute DW_AT_location expression for the DWARF expression subroutine in
110 the DIE at DIE_OFFSET in the CU from CTX. Do not touch STACK while it
111 being passed to and returned from the called DWARF subroutine. */
112 void (*dwarf_call) (struct dwarf_expr_context *ctx, size_t die_offset);
115 /* Not yet implemented. */
117 /* Return the `object address' for DW_OP_push_object_address. */
118 CORE_ADDR (*get_object_address) (void *baton);
121 /* The current depth of dwarf expression recursion, via DW_OP_call*,
122 DW_OP_fbreg, DW_OP_push_object_address, etc., and the maximum
123 depth we'll tolerate before raising an error. */
124 int recursion_depth, max_recursion_depth;
126 /* Location of the value. */
127 enum dwarf_value_location location;
129 /* For DWARF_VALUE_LITERAL, a the current literal value's length and
130 data. For DWARF_VALUE_IMPLICIT_POINTER, LEN is the offset of the
133 const gdb_byte *data;
135 /* Initialization status of variable: Non-zero if variable has been
136 initialized; zero otherwise. */
139 /* An array of pieces. PIECES points to its first element;
140 NUM_PIECES is its length.
142 Each time DW_OP_piece is executed, we add a new element to the
143 end of this array, recording the current top of the stack, the
144 current location, and the size given as the operand to
145 DW_OP_piece. We then pop the top value from the stack, reset the
146 location, and resume evaluation.
148 The Dwarf spec doesn't say whether DW_OP_piece pops the top value
149 from the stack. We do, ensuring that clients of this interface
150 expecting to see a value left on the top of the stack (say, code
151 evaluating frame base expressions or CFA's specified with
152 DW_CFA_def_cfa_expression) will get an error if the expression
153 actually marks all the values it computes as pieces.
155 If an expression never uses DW_OP_piece, num_pieces will be zero.
156 (It would be nice to present these cases as expressions yielding
157 a single piece, so that callers need not distinguish between the
158 no-DW_OP_piece and one-DW_OP_piece cases. But expressions with
159 no DW_OP_piece operations have no value to place in a piece's
160 'size' field; the size comes from the surrounding data. So the
161 two cases need to be handled separately.) */
163 struct dwarf_expr_piece *pieces;
167 /* A piece of an object, as recorded by DW_OP_piece or DW_OP_bit_piece. */
168 struct dwarf_expr_piece
170 enum dwarf_value_location location;
176 /* This piece's address, for DWARF_VALUE_MEMORY pieces. */
178 /* Non-zero if the piece is known to be in memory and on
179 the program's stack. */
183 /* The piece's register number or literal value, for
184 DWARF_VALUE_REGISTER or DWARF_VALUE_STACK pieces. */
189 /* A pointer to the data making up this piece,
190 for DWARF_VALUE_LITERAL pieces. */
191 const gdb_byte *data;
192 /* The length of the available data. */
196 /* Used for DWARF_VALUE_IMPLICIT_POINTER. */
199 /* The referent DIE from DW_OP_GNU_implicit_pointer. */
201 /* The byte offset into the resulting data. */
206 /* The length of the piece, in bits. */
208 /* The piece offset, in bits. */
212 struct dwarf_expr_context *new_dwarf_expr_context (void);
213 void free_dwarf_expr_context (struct dwarf_expr_context *ctx);
215 make_cleanup_free_dwarf_expr_context (struct dwarf_expr_context *ctx);
217 void dwarf_expr_push (struct dwarf_expr_context *ctx, ULONGEST value,
218 int in_stack_memory);
219 void dwarf_expr_pop (struct dwarf_expr_context *ctx);
220 void dwarf_expr_eval (struct dwarf_expr_context *ctx, const gdb_byte *addr,
222 ULONGEST dwarf_expr_fetch (struct dwarf_expr_context *ctx, int n);
223 CORE_ADDR dwarf_expr_fetch_address (struct dwarf_expr_context *ctx, int n);
224 int dwarf_expr_fetch_in_stack_memory (struct dwarf_expr_context *ctx, int n);
227 const gdb_byte *read_uleb128 (const gdb_byte *buf, const gdb_byte *buf_end,
229 const gdb_byte *read_sleb128 (const gdb_byte *buf, const gdb_byte *buf_end,
232 const char *dwarf_stack_op_name (unsigned int);
234 void dwarf_expr_require_composition (const gdb_byte *, const gdb_byte *,
237 #endif /* dwarf2expr.h */