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 2 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, write to the Free Software
21 Foundation, Inc., 51 Franklin Street, Fifth Floor,
22 Boston, MA 02110-1301, USA. */
24 #if !defined (DWARF2EXPR_H)
27 /* The expression evaluator works with a dwarf_expr_context, describing
28 its current state and its callbacks. */
29 struct dwarf_expr_context
31 /* The stack of values, allocated with xmalloc. */
34 /* The number of values currently pushed on the stack, and the
35 number of elements allocated to the stack. */
36 int stack_len
, stack_allocated
;
38 /* An opaque argument provided by the caller, which will be passed
39 to all of the callback functions. */
42 /* Return the value of register number REGNUM. */
43 CORE_ADDR (*read_reg
) (void *baton
, int regnum
);
45 /* Read LENGTH bytes at ADDR into BUF. */
46 void (*read_mem
) (void *baton
, gdb_byte
*buf
, CORE_ADDR addr
, size_t length
);
48 /* Return the location expression for the frame base attribute, in
49 START and LENGTH. The result must be live until the current
50 expression evaluation is complete. */
51 void (*get_frame_base
) (void *baton
, gdb_byte
**start
, size_t *length
);
53 /* Return the thread-local storage address for
54 DW_OP_GNU_push_tls_address. */
55 CORE_ADDR (*get_tls_address
) (void *baton
, CORE_ADDR offset
);
58 /* Not yet implemented. */
60 /* Return the location expression for the dwarf expression
61 subroutine in the die at OFFSET in the current compilation unit.
62 The result must be live until the current expression evaluation
64 unsigned char *(*get_subr
) (void *baton
, off_t offset
, size_t *length
);
66 /* Return the `object address' for DW_OP_push_object_address. */
67 CORE_ADDR (*get_object_address
) (void *baton
);
70 /* The current depth of dwarf expression recursion, via DW_OP_call*,
71 DW_OP_fbreg, DW_OP_push_object_address, etc., and the maximum
72 depth we'll tolerate before raising an error. */
73 int recursion_depth
, max_recursion_depth
;
75 /* Non-zero if the result is in a register. The register number
76 will be on the expression stack. */
79 /* Initialization status of variable: Non-zero if variable has been
80 initialized; zero otherwise. */
83 /* An array of pieces. PIECES points to its first element;
84 NUM_PIECES is its length.
86 Each time DW_OP_piece is executed, we add a new element to the
87 end of this array, recording the current top of the stack, the
88 current in_reg flag, and the size given as the operand to
89 DW_OP_piece. We then pop the top value from the stack, clear the
90 in_reg flag, and resume evaluation.
92 The Dwarf spec doesn't say whether DW_OP_piece pops the top value
93 from the stack. We do, ensuring that clients of this interface
94 expecting to see a value left on the top of the stack (say, code
95 evaluating frame base expressions or CFA's specified with
96 DW_CFA_def_cfa_expression) will get an error if the expression
97 actually marks all the values it computes as pieces.
99 If an expression never uses DW_OP_piece, num_pieces will be zero.
100 (It would be nice to present these cases as expressions yielding
101 a single piece, with in_reg clear, so that callers need not
102 distinguish between the no-DW_OP_piece and one-DW_OP_piece cases.
103 But expressions with no DW_OP_piece operations have no value to
104 place in a piece's 'size' field; the size comes from the
105 surrounding data. So the two cases need to be handled
108 struct dwarf_expr_piece
*pieces
;
112 /* A piece of an object, as recorded by DW_OP_piece. */
113 struct dwarf_expr_piece
115 /* If IN_REG is zero, then the piece is in memory, and VALUE is its address.
116 If IN_REG is non-zero, then the piece is in a register, and VALUE
117 is the register number. */
120 /* This piece's address or register number. */
123 /* The length of the piece, in bytes. */
127 struct dwarf_expr_context
*new_dwarf_expr_context (void);
128 void free_dwarf_expr_context (struct dwarf_expr_context
*ctx
);
130 void dwarf_expr_push (struct dwarf_expr_context
*ctx
, CORE_ADDR value
);
131 void dwarf_expr_pop (struct dwarf_expr_context
*ctx
);
132 void dwarf_expr_eval (struct dwarf_expr_context
*ctx
, unsigned char *addr
,
134 CORE_ADDR
dwarf_expr_fetch (struct dwarf_expr_context
*ctx
, int n
);
137 gdb_byte
*read_uleb128 (gdb_byte
*buf
, gdb_byte
*buf_end
, ULONGEST
* r
);
138 gdb_byte
*read_sleb128 (gdb_byte
*buf
, gdb_byte
*buf_end
, LONGEST
* r
);
139 CORE_ADDR
dwarf2_read_address (gdb_byte
*buf
, gdb_byte
*buf_end
,
142 #endif /* dwarf2expr.h */
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