1 /* DWARF 2 Expression Evaluator.
3 Copyright (C) 2001, 2002, 2003, 2005, 2007, 2008, 2009, 2010
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 location of a value. */
27 enum dwarf_value_location
29 /* The piece is in memory.
30 The value on the dwarf stack is its address. */
33 /* The piece is in a register.
34 The value on the dwarf stack is the register number. */
37 /* The piece is on the dwarf stack. */
40 /* The piece is a literal. */
43 /* The piece was optimized out. */
44 DWARF_VALUE_OPTIMIZED_OUT
47 /* The dwarf expression stack. */
49 struct dwarf_stack_value
53 /* Non-zero if the piece is in memory and is known to be
54 on the program's stack. It is always ok to set this to zero.
55 This is used, for example, to optimize memory access from the target.
56 It can vastly speed up backtraces on long latency connections when
57 "set stack-cache on". */
61 /* The expression evaluator works with a dwarf_expr_context, describing
62 its current state and its callbacks. */
63 struct dwarf_expr_context
65 /* The stack of values, allocated with xmalloc. */
66 struct dwarf_stack_value *stack;
68 /* The number of values currently pushed on the stack, and the
69 number of elements allocated to the stack. */
70 int stack_len, stack_allocated;
72 /* Target architecture to use for address operations. */
73 struct gdbarch *gdbarch;
75 /* Target address size in bytes. */
78 /* An opaque argument provided by the caller, which will be passed
79 to all of the callback functions. */
82 /* Return the value of register number REGNUM. */
83 CORE_ADDR (*read_reg) (void *baton, int regnum);
85 /* Read LENGTH bytes at ADDR into BUF. */
86 void (*read_mem) (void *baton, gdb_byte *buf, CORE_ADDR addr, size_t length);
88 /* Return the location expression for the frame base attribute, in
89 START and LENGTH. The result must be live until the current
90 expression evaluation is complete. */
91 void (*get_frame_base) (void *baton, gdb_byte **start, size_t *length);
93 /* Return the CFA for the frame. */
94 CORE_ADDR (*get_frame_cfa) (void *baton);
96 /* Return the thread-local storage address for
97 DW_OP_GNU_push_tls_address. */
98 CORE_ADDR (*get_tls_address) (void *baton, CORE_ADDR offset);
101 /* Not yet implemented. */
103 /* Return the location expression for the dwarf expression
104 subroutine in the die at OFFSET in the current compilation unit.
105 The result must be live until the current expression evaluation
107 unsigned char *(*get_subr) (void *baton, off_t offset, size_t *length);
109 /* Return the `object address' for DW_OP_push_object_address. */
110 CORE_ADDR (*get_object_address) (void *baton);
113 /* The current depth of dwarf expression recursion, via DW_OP_call*,
114 DW_OP_fbreg, DW_OP_push_object_address, etc., and the maximum
115 depth we'll tolerate before raising an error. */
116 int recursion_depth, max_recursion_depth;
118 /* Location of the value. */
119 enum dwarf_value_location location;
121 /* For VALUE_LITERAL, a the current literal value's length and
126 /* Initialization status of variable: Non-zero if variable has been
127 initialized; zero otherwise. */
130 /* An array of pieces. PIECES points to its first element;
131 NUM_PIECES is its length.
133 Each time DW_OP_piece is executed, we add a new element to the
134 end of this array, recording the current top of the stack, the
135 current location, and the size given as the operand to
136 DW_OP_piece. We then pop the top value from the stack, reset the
137 location, and resume evaluation.
139 The Dwarf spec doesn't say whether DW_OP_piece pops the top value
140 from the stack. We do, ensuring that clients of this interface
141 expecting to see a value left on the top of the stack (say, code
142 evaluating frame base expressions or CFA's specified with
143 DW_CFA_def_cfa_expression) will get an error if the expression
144 actually marks all the values it computes as pieces.
146 If an expression never uses DW_OP_piece, num_pieces will be zero.
147 (It would be nice to present these cases as expressions yielding
148 a single piece, so that callers need not distinguish between the
149 no-DW_OP_piece and one-DW_OP_piece cases. But expressions with
150 no DW_OP_piece operations have no value to place in a piece's
151 'size' field; the size comes from the surrounding data. So the
152 two cases need to be handled separately.) */
154 struct dwarf_expr_piece *pieces;
158 /* A piece of an object, as recorded by DW_OP_piece. */
159 struct dwarf_expr_piece
161 enum dwarf_value_location location;
167 /* This piece's address or register number. */
169 /* Non-zero if the piece is known to be in memory and on
170 the program's stack. */
176 /* A pointer to the data making up this piece, for literal
179 /* The length of the available data. */
184 /* The length of the piece, in bytes. */
188 struct dwarf_expr_context *new_dwarf_expr_context (void);
189 void free_dwarf_expr_context (struct dwarf_expr_context *ctx);
191 make_cleanup_free_dwarf_expr_context (struct dwarf_expr_context *ctx);
193 void dwarf_expr_push (struct dwarf_expr_context *ctx, CORE_ADDR value,
194 int in_stack_memory);
195 void dwarf_expr_pop (struct dwarf_expr_context *ctx);
196 void dwarf_expr_eval (struct dwarf_expr_context *ctx, unsigned char *addr,
198 CORE_ADDR dwarf_expr_fetch (struct dwarf_expr_context *ctx, int n);
199 int dwarf_expr_fetch_in_stack_memory (struct dwarf_expr_context *ctx, int n);
202 gdb_byte *read_uleb128 (gdb_byte *buf, gdb_byte *buf_end, ULONGEST * r);
203 gdb_byte *read_sleb128 (gdb_byte *buf, gdb_byte *buf_end, LONGEST * r);
204 CORE_ADDR dwarf2_read_address (struct gdbarch *gdbarch, gdb_byte *buf,
205 gdb_byte *buf_end, int addr_size);
207 #endif /* dwarf2expr.h */