1 /* DWARF 2 Expression Evaluator.
3 Copyright (C) 2001, 2002, 2003, 2005, 2007, 2008
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 expression evaluator works with a dwarf_expr_context, describing
27 its current state and its callbacks. */
28 struct dwarf_expr_context
30 /* The stack of values, allocated with xmalloc. */
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
;
37 /* An opaque argument provided by the caller, which will be passed
38 to all of the callback functions. */
41 /* Return the value of register number REGNUM. */
42 CORE_ADDR (*read_reg
) (void *baton
, int regnum
);
44 /* Read LENGTH bytes at ADDR into BUF. */
45 void (*read_mem
) (void *baton
, gdb_byte
*buf
, CORE_ADDR addr
, size_t length
);
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. */
50 void (*get_frame_base
) (void *baton
, gdb_byte
**start
, size_t *length
);
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
);
57 /* Not yet implemented. */
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
63 unsigned char *(*get_subr
) (void *baton
, off_t offset
, size_t *length
);
65 /* Return the `object address' for DW_OP_push_object_address. */
66 CORE_ADDR (*get_object_address
) (void *baton
);
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
;
74 /* Non-zero if the result is in a register. The register number
75 will be on the expression stack. */
78 /* Initialization status of variable: Non-zero if variable has been
79 initialized; zero otherwise. */
82 /* An array of pieces. PIECES points to its first element;
83 NUM_PIECES is its length.
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.
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.
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
107 struct dwarf_expr_piece
*pieces
;
111 /* A piece of an object, as recorded by DW_OP_piece. */
112 struct dwarf_expr_piece
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. */
119 /* This piece's address or register number. */
122 /* The length of the piece, in bytes. */
126 struct dwarf_expr_context
*new_dwarf_expr_context (void);
127 void free_dwarf_expr_context (struct dwarf_expr_context
*ctx
);
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
,
133 CORE_ADDR
dwarf_expr_fetch (struct dwarf_expr_context
*ctx
, int n
);
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
,
141 #endif /* dwarf2expr.h */
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