1 /* DWARF 2 Expression Evaluator.
3 Copyright (C) 2001, 2002, 2003, 2005, 2007 Free Software Foundation, Inc.
5 Contributed by Daniel Berlin <dan@dberlin.org>.
7 This file is part of GDB.
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
11 the Free Software Foundation; either version 3 of the License, or
12 (at your option) any later version.
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.
19 You should have received a copy of the GNU General Public License
20 along with this program. If not, see <http://www.gnu.org/licenses/>. */
22 #if !defined (DWARF2EXPR_H)
25 /* The expression evaluator works with a dwarf_expr_context, describing
26 its current state and its callbacks. */
27 struct dwarf_expr_context
29 /* The stack of values, allocated with xmalloc. */
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
;
36 /* An opaque argument provided by the caller, which will be passed
37 to all of the callback functions. */
40 /* Return the value of register number REGNUM. */
41 CORE_ADDR (*read_reg
) (void *baton
, int regnum
);
43 /* Read LENGTH bytes at ADDR into BUF. */
44 void (*read_mem
) (void *baton
, gdb_byte
*buf
, CORE_ADDR addr
, size_t length
);
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. */
49 void (*get_frame_base
) (void *baton
, gdb_byte
**start
, size_t *length
);
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
);
56 /* Not yet implemented. */
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
62 unsigned char *(*get_subr
) (void *baton
, off_t offset
, size_t *length
);
64 /* Return the `object address' for DW_OP_push_object_address. */
65 CORE_ADDR (*get_object_address
) (void *baton
);
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
;
73 /* Non-zero if the result is in a register. The register number
74 will be on the expression stack. */
77 /* Initialization status of variable: Non-zero if variable has been
78 initialized; zero otherwise. */
81 /* An array of pieces. PIECES points to its first element;
82 NUM_PIECES is its length.
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.
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.
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
106 struct dwarf_expr_piece
*pieces
;
110 /* A piece of an object, as recorded by DW_OP_piece. */
111 struct dwarf_expr_piece
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. */
118 /* This piece's address or register number. */
121 /* The length of the piece, in bytes. */
125 struct dwarf_expr_context
*new_dwarf_expr_context (void);
126 void free_dwarf_expr_context (struct dwarf_expr_context
*ctx
);
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
,
132 CORE_ADDR
dwarf_expr_fetch (struct dwarf_expr_context
*ctx
, int n
);
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
,
140 #endif /* dwarf2expr.h */
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