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1 | /* DWARF 2 Expression Evaluator. |
2 | ||
6aba47ca | 3 | Copyright (C) 2001, 2002, 2003, 2005, 2007 Free Software Foundation, Inc. |
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4 | |
5 | Contributed by Daniel Berlin <dan@dberlin.org>. | |
6 | ||
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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/>. */ |
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21 | |
22 | #if !defined (DWARF2EXPR_H) | |
23 | #define DWARF2EXPR_H | |
24 | ||
25 | /* The expression evaluator works with a dwarf_expr_context, describing | |
26 | its current state and its callbacks. */ | |
27 | struct dwarf_expr_context | |
28 | { | |
29 | /* The stack of values, allocated with xmalloc. */ | |
30 | CORE_ADDR *stack; | |
31 | ||
32 | /* The number of values currently pushed on the stack, and the | |
33 | number of elements allocated to the stack. */ | |
34 | int stack_len, stack_allocated; | |
35 | ||
36 | /* An opaque argument provided by the caller, which will be passed | |
37 | to all of the callback functions. */ | |
38 | void *baton; | |
39 | ||
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40 | /* Return the value of register number REGNUM. */ |
41 | CORE_ADDR (*read_reg) (void *baton, int regnum); | |
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42 | |
43 | /* Read LENGTH bytes at ADDR into BUF. */ | |
852483bc | 44 | void (*read_mem) (void *baton, gdb_byte *buf, CORE_ADDR addr, size_t length); |
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45 | |
46 | /* Return the location expression for the frame base attribute, in | |
47 | START and LENGTH. The result must be live until the current | |
48 | expression evaluation is complete. */ | |
852483bc | 49 | void (*get_frame_base) (void *baton, gdb_byte **start, size_t *length); |
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50 | |
51 | /* Return the thread-local storage address for | |
52 | DW_OP_GNU_push_tls_address. */ | |
53 | CORE_ADDR (*get_tls_address) (void *baton, CORE_ADDR offset); | |
54 | ||
55 | #if 0 | |
56 | /* Not yet implemented. */ | |
57 | ||
58 | /* Return the location expression for the dwarf expression | |
59 | subroutine in the die at OFFSET in the current compilation unit. | |
60 | The result must be live until the current expression evaluation | |
61 | is complete. */ | |
62 | unsigned char *(*get_subr) (void *baton, off_t offset, size_t *length); | |
63 | ||
64 | /* Return the `object address' for DW_OP_push_object_address. */ | |
65 | CORE_ADDR (*get_object_address) (void *baton); | |
66 | #endif | |
67 | ||
68 | /* The current depth of dwarf expression recursion, via DW_OP_call*, | |
69 | DW_OP_fbreg, DW_OP_push_object_address, etc., and the maximum | |
70 | depth we'll tolerate before raising an error. */ | |
71 | int recursion_depth, max_recursion_depth; | |
72 | ||
73 | /* Non-zero if the result is in a register. The register number | |
61fbb938 | 74 | will be on the expression stack. */ |
4c2df51b | 75 | int in_reg; |
87808bd6 | 76 | |
42be36b3 CT |
77 | /* Initialization status of variable: Non-zero if variable has been |
78 | initialized; zero otherwise. */ | |
79 | int initialized; | |
80 | ||
87808bd6 JB |
81 | /* An array of pieces. PIECES points to its first element; |
82 | NUM_PIECES is its length. | |
83 | ||
84 | Each time DW_OP_piece is executed, we add a new element to the | |
85 | end of this array, recording the current top of the stack, the | |
86 | current in_reg flag, and the size given as the operand to | |
87 | DW_OP_piece. We then pop the top value from the stack, clear the | |
88 | in_reg flag, and resume evaluation. | |
89 | ||
90 | The Dwarf spec doesn't say whether DW_OP_piece pops the top value | |
91 | from the stack. We do, ensuring that clients of this interface | |
92 | expecting to see a value left on the top of the stack (say, code | |
93 | evaluating frame base expressions or CFA's specified with | |
94 | DW_CFA_def_cfa_expression) will get an error if the expression | |
95 | actually marks all the values it computes as pieces. | |
96 | ||
97 | If an expression never uses DW_OP_piece, num_pieces will be zero. | |
98 | (It would be nice to present these cases as expressions yielding | |
99 | a single piece, with in_reg clear, so that callers need not | |
100 | distinguish between the no-DW_OP_piece and one-DW_OP_piece cases. | |
101 | But expressions with no DW_OP_piece operations have no value to | |
102 | place in a piece's 'size' field; the size comes from the | |
103 | surrounding data. So the two cases need to be handled | |
104 | separately.) */ | |
105 | int num_pieces; | |
106 | struct dwarf_expr_piece *pieces; | |
107 | }; | |
108 | ||
109 | ||
110 | /* A piece of an object, as recorded by DW_OP_piece. */ | |
111 | struct dwarf_expr_piece | |
112 | { | |
113 | /* If IN_REG is zero, then the piece is in memory, and VALUE is its address. | |
114 | If IN_REG is non-zero, then the piece is in a register, and VALUE | |
115 | is the register number. */ | |
116 | int in_reg; | |
117 | ||
118 | /* This piece's address or register number. */ | |
119 | CORE_ADDR value; | |
120 | ||
121 | /* The length of the piece, in bytes. */ | |
122 | ULONGEST size; | |
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123 | }; |
124 | ||
b9362cc7 | 125 | struct dwarf_expr_context *new_dwarf_expr_context (void); |
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126 | void free_dwarf_expr_context (struct dwarf_expr_context *ctx); |
127 | ||
128 | void dwarf_expr_push (struct dwarf_expr_context *ctx, CORE_ADDR value); | |
129 | void dwarf_expr_pop (struct dwarf_expr_context *ctx); | |
130 | void dwarf_expr_eval (struct dwarf_expr_context *ctx, unsigned char *addr, | |
131 | size_t len); | |
132 | CORE_ADDR dwarf_expr_fetch (struct dwarf_expr_context *ctx, int n); | |
133 | ||
a55cc764 | 134 | |
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135 | gdb_byte *read_uleb128 (gdb_byte *buf, gdb_byte *buf_end, ULONGEST * r); |
136 | gdb_byte *read_sleb128 (gdb_byte *buf, gdb_byte *buf_end, LONGEST * r); | |
137 | CORE_ADDR dwarf2_read_address (gdb_byte *buf, gdb_byte *buf_end, | |
0d53c4c4 | 138 | int *bytes_read); |
a55cc764 | 139 | |
852483bc | 140 | #endif /* dwarf2expr.h */ |