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