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852483bc MK |
1 | /* DWARF 2 Expression Evaluator. |
2 | ||
9b254dd1 DJ |
3 | Copyright (C) 2001, 2002, 2003, 2005, 2007, 2008 |
4 | Free Software Foundation, Inc. | |
852483bc MK |
5 | |
6 | Contributed by Daniel Berlin <dan@dberlin.org>. | |
7 | ||
4c2df51b DJ |
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 | 12 | the Free Software Foundation; either version 3 of the License, or |
4c2df51b DJ |
13 | (at your option) any later version. |
14 | ||
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. | |
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 | #if !defined (DWARF2EXPR_H) | |
24 | #define DWARF2EXPR_H | |
25 | ||
26 | /* The expression evaluator works with a dwarf_expr_context, describing | |
27 | its current state and its callbacks. */ | |
28 | struct dwarf_expr_context | |
29 | { | |
30 | /* The stack of values, allocated with xmalloc. */ | |
31 | CORE_ADDR *stack; | |
32 | ||
33 | /* The number of values currently pushed on the stack, and the | |
34 | number of elements allocated to the stack. */ | |
35 | int stack_len, stack_allocated; | |
36 | ||
37 | /* An opaque argument provided by the caller, which will be passed | |
38 | to all of the callback functions. */ | |
39 | void *baton; | |
40 | ||
61fbb938 DJ |
41 | /* Return the value of register number REGNUM. */ |
42 | CORE_ADDR (*read_reg) (void *baton, int regnum); | |
4c2df51b DJ |
43 | |
44 | /* Read LENGTH bytes at ADDR into BUF. */ | |
852483bc | 45 | void (*read_mem) (void *baton, gdb_byte *buf, CORE_ADDR addr, size_t length); |
4c2df51b DJ |
46 | |
47 | /* Return the location expression for the frame base attribute, in | |
48 | START and LENGTH. The result must be live until the current | |
49 | expression evaluation is complete. */ | |
852483bc | 50 | void (*get_frame_base) (void *baton, gdb_byte **start, size_t *length); |
4c2df51b DJ |
51 | |
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); | |
55 | ||
56 | #if 0 | |
57 | /* Not yet implemented. */ | |
58 | ||
59 | /* Return the location expression for the dwarf expression | |
60 | subroutine in the die at OFFSET in the current compilation unit. | |
61 | The result must be live until the current expression evaluation | |
62 | is complete. */ | |
63 | unsigned char *(*get_subr) (void *baton, off_t offset, size_t *length); | |
64 | ||
65 | /* Return the `object address' for DW_OP_push_object_address. */ | |
66 | CORE_ADDR (*get_object_address) (void *baton); | |
67 | #endif | |
68 | ||
69 | /* The current depth of dwarf expression recursion, via DW_OP_call*, | |
70 | DW_OP_fbreg, DW_OP_push_object_address, etc., and the maximum | |
71 | depth we'll tolerate before raising an error. */ | |
72 | int recursion_depth, max_recursion_depth; | |
73 | ||
74 | /* Non-zero if the result is in a register. The register number | |
61fbb938 | 75 | will be on the expression stack. */ |
4c2df51b | 76 | int in_reg; |
87808bd6 | 77 | |
42be36b3 CT |
78 | /* Initialization status of variable: Non-zero if variable has been |
79 | initialized; zero otherwise. */ | |
80 | int initialized; | |
81 | ||
87808bd6 JB |
82 | /* An array of pieces. PIECES points to its first element; |
83 | NUM_PIECES is its length. | |
84 | ||
85 | Each time DW_OP_piece is executed, we add a new element to the | |
86 | end of this array, recording the current top of the stack, the | |
87 | current in_reg flag, and the size given as the operand to | |
88 | DW_OP_piece. We then pop the top value from the stack, clear the | |
89 | in_reg flag, and resume evaluation. | |
90 | ||
91 | The Dwarf spec doesn't say whether DW_OP_piece pops the top value | |
92 | from the stack. We do, ensuring that clients of this interface | |
93 | expecting to see a value left on the top of the stack (say, code | |
94 | evaluating frame base expressions or CFA's specified with | |
95 | DW_CFA_def_cfa_expression) will get an error if the expression | |
96 | actually marks all the values it computes as pieces. | |
97 | ||
98 | If an expression never uses DW_OP_piece, num_pieces will be zero. | |
99 | (It would be nice to present these cases as expressions yielding | |
100 | a single piece, with in_reg clear, so that callers need not | |
101 | distinguish between the no-DW_OP_piece and one-DW_OP_piece cases. | |
102 | But expressions with no DW_OP_piece operations have no value to | |
103 | place in a piece's 'size' field; the size comes from the | |
104 | surrounding data. So the two cases need to be handled | |
105 | separately.) */ | |
106 | int num_pieces; | |
107 | struct dwarf_expr_piece *pieces; | |
108 | }; | |
109 | ||
110 | ||
111 | /* A piece of an object, as recorded by DW_OP_piece. */ | |
112 | struct dwarf_expr_piece | |
113 | { | |
114 | /* If IN_REG is zero, then the piece is in memory, and VALUE is its address. | |
115 | If IN_REG is non-zero, then the piece is in a register, and VALUE | |
116 | is the register number. */ | |
117 | int in_reg; | |
118 | ||
119 | /* This piece's address or register number. */ | |
120 | CORE_ADDR value; | |
121 | ||
122 | /* The length of the piece, in bytes. */ | |
123 | ULONGEST size; | |
4c2df51b DJ |
124 | }; |
125 | ||
b9362cc7 | 126 | struct dwarf_expr_context *new_dwarf_expr_context (void); |
4c2df51b DJ |
127 | void free_dwarf_expr_context (struct dwarf_expr_context *ctx); |
128 | ||
129 | void dwarf_expr_push (struct dwarf_expr_context *ctx, CORE_ADDR value); | |
130 | void dwarf_expr_pop (struct dwarf_expr_context *ctx); | |
131 | void dwarf_expr_eval (struct dwarf_expr_context *ctx, unsigned char *addr, | |
132 | size_t len); | |
133 | CORE_ADDR dwarf_expr_fetch (struct dwarf_expr_context *ctx, int n); | |
134 | ||
a55cc764 | 135 | |
852483bc MK |
136 | gdb_byte *read_uleb128 (gdb_byte *buf, gdb_byte *buf_end, ULONGEST * r); |
137 | gdb_byte *read_sleb128 (gdb_byte *buf, gdb_byte *buf_end, LONGEST * r); | |
138 | CORE_ADDR dwarf2_read_address (gdb_byte *buf, gdb_byte *buf_end, | |
0d53c4c4 | 139 | int *bytes_read); |
a55cc764 | 140 | |
852483bc | 141 | #endif /* dwarf2expr.h */ |