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 /* Target architecture to use for address operations. */
38 struct gdbarch
*gdbarch
;
40 /* Target address size in bytes. */
43 /* An opaque argument provided by the caller, which will be passed
44 to all of the callback functions. */
47 /* Return the value of register number REGNUM. */
48 CORE_ADDR (*read_reg
) (void *baton
, int regnum
);
50 /* Read LENGTH bytes at ADDR into BUF. */
51 void (*read_mem
) (void *baton
, gdb_byte
*buf
, CORE_ADDR addr
, size_t length
);
53 /* Return the location expression for the frame base attribute, in
54 START and LENGTH. The result must be live until the current
55 expression evaluation is complete. */
56 void (*get_frame_base
) (void *baton
, gdb_byte
**start
, size_t *length
);
58 /* Return the thread-local storage address for
59 DW_OP_GNU_push_tls_address. */
60 CORE_ADDR (*get_tls_address
) (void *baton
, CORE_ADDR offset
);
63 /* Not yet implemented. */
65 /* Return the location expression for the dwarf expression
66 subroutine in the die at OFFSET in the current compilation unit.
67 The result must be live until the current expression evaluation
69 unsigned char *(*get_subr
) (void *baton
, off_t offset
, size_t *length
);
71 /* Return the `object address' for DW_OP_push_object_address. */
72 CORE_ADDR (*get_object_address
) (void *baton
);
75 /* The current depth of dwarf expression recursion, via DW_OP_call*,
76 DW_OP_fbreg, DW_OP_push_object_address, etc., and the maximum
77 depth we'll tolerate before raising an error. */
78 int recursion_depth
, max_recursion_depth
;
80 /* Non-zero if the result is in a register. The register number
81 will be on the expression stack. */
84 /* Initialization status of variable: Non-zero if variable has been
85 initialized; zero otherwise. */
88 /* An array of pieces. PIECES points to its first element;
89 NUM_PIECES is its length.
91 Each time DW_OP_piece is executed, we add a new element to the
92 end of this array, recording the current top of the stack, the
93 current in_reg flag, and the size given as the operand to
94 DW_OP_piece. We then pop the top value from the stack, clear the
95 in_reg flag, and resume evaluation.
97 The Dwarf spec doesn't say whether DW_OP_piece pops the top value
98 from the stack. We do, ensuring that clients of this interface
99 expecting to see a value left on the top of the stack (say, code
100 evaluating frame base expressions or CFA's specified with
101 DW_CFA_def_cfa_expression) will get an error if the expression
102 actually marks all the values it computes as pieces.
104 If an expression never uses DW_OP_piece, num_pieces will be zero.
105 (It would be nice to present these cases as expressions yielding
106 a single piece, with in_reg clear, so that callers need not
107 distinguish between the no-DW_OP_piece and one-DW_OP_piece cases.
108 But expressions with no DW_OP_piece operations have no value to
109 place in a piece's 'size' field; the size comes from the
110 surrounding data. So the two cases need to be handled
113 struct dwarf_expr_piece
*pieces
;
117 /* A piece of an object, as recorded by DW_OP_piece. */
118 struct dwarf_expr_piece
120 /* If IN_REG is zero, then the piece is in memory, and VALUE is its address.
121 If IN_REG is non-zero, then the piece is in a register, and VALUE
122 is the register number. */
125 /* This piece's address or register number. */
128 /* The length of the piece, in bytes. */
132 struct dwarf_expr_context
*new_dwarf_expr_context (void);
133 void free_dwarf_expr_context (struct dwarf_expr_context
*ctx
);
135 void dwarf_expr_push (struct dwarf_expr_context
*ctx
, CORE_ADDR value
);
136 void dwarf_expr_pop (struct dwarf_expr_context
*ctx
);
137 void dwarf_expr_eval (struct dwarf_expr_context
*ctx
, unsigned char *addr
,
139 CORE_ADDR
dwarf_expr_fetch (struct dwarf_expr_context
*ctx
, int n
);
142 gdb_byte
*read_uleb128 (gdb_byte
*buf
, gdb_byte
*buf_end
, ULONGEST
* r
);
143 gdb_byte
*read_sleb128 (gdb_byte
*buf
, gdb_byte
*buf_end
, LONGEST
* r
);
144 CORE_ADDR
dwarf2_read_address (struct gdbarch
*gdbarch
, gdb_byte
*buf
,
145 gdb_byte
*buf_end
, int addr_size
);
147 #endif /* dwarf2expr.h */
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