1 /* DWARF 2 Expression Evaluator.
3 Copyright (C) 2001, 2002, 2003, 2005, 2007, 2008, 2009
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. */
31 /* The piece is in a register. */
33 /* The piece is on the stack. */
35 /* The piece is a literal. */
39 /* The expression evaluator works with a dwarf_expr_context, describing
40 its current state and its callbacks. */
41 struct dwarf_expr_context
43 /* The stack of values, allocated with xmalloc. */
46 /* The number of values currently pushed on the stack, and the
47 number of elements allocated to the stack. */
48 int stack_len, stack_allocated;
50 /* Target architecture to use for address operations. */
51 struct gdbarch *gdbarch;
53 /* Target address size in bytes. */
56 /* An opaque argument provided by the caller, which will be passed
57 to all of the callback functions. */
60 /* Return the value of register number REGNUM. */
61 CORE_ADDR (*read_reg) (void *baton, int regnum);
63 /* Read LENGTH bytes at ADDR into BUF. */
64 void (*read_mem) (void *baton, gdb_byte *buf, CORE_ADDR addr, size_t length);
66 /* Return the location expression for the frame base attribute, in
67 START and LENGTH. The result must be live until the current
68 expression evaluation is complete. */
69 void (*get_frame_base) (void *baton, gdb_byte **start, size_t *length);
71 /* Return the CFA for the frame. */
72 CORE_ADDR (*get_frame_cfa) (void *baton);
74 /* Return the thread-local storage address for
75 DW_OP_GNU_push_tls_address. */
76 CORE_ADDR (*get_tls_address) (void *baton, CORE_ADDR offset);
79 /* Not yet implemented. */
81 /* Return the location expression for the dwarf expression
82 subroutine in the die at OFFSET in the current compilation unit.
83 The result must be live until the current expression evaluation
85 unsigned char *(*get_subr) (void *baton, off_t offset, size_t *length);
87 /* Return the `object address' for DW_OP_push_object_address. */
88 CORE_ADDR (*get_object_address) (void *baton);
91 /* The current depth of dwarf expression recursion, via DW_OP_call*,
92 DW_OP_fbreg, DW_OP_push_object_address, etc., and the maximum
93 depth we'll tolerate before raising an error. */
94 int recursion_depth, max_recursion_depth;
96 /* Location of the value. */
97 enum dwarf_value_location location;
99 /* For VALUE_LITERAL, a the current literal value's length and
104 /* Initialization status of variable: Non-zero if variable has been
105 initialized; zero otherwise. */
108 /* An array of pieces. PIECES points to its first element;
109 NUM_PIECES is its length.
111 Each time DW_OP_piece is executed, we add a new element to the
112 end of this array, recording the current top of the stack, the
113 current location, and the size given as the operand to
114 DW_OP_piece. We then pop the top value from the stack, rest the
115 location, and resume evaluation.
117 The Dwarf spec doesn't say whether DW_OP_piece pops the top value
118 from the stack. We do, ensuring that clients of this interface
119 expecting to see a value left on the top of the stack (say, code
120 evaluating frame base expressions or CFA's specified with
121 DW_CFA_def_cfa_expression) will get an error if the expression
122 actually marks all the values it computes as pieces.
124 If an expression never uses DW_OP_piece, num_pieces will be zero.
125 (It would be nice to present these cases as expressions yielding
126 a single piece, so that callers need not distinguish between the
127 no-DW_OP_piece and one-DW_OP_piece cases. But expressions with
128 no DW_OP_piece operations have no value to place in a piece's
129 'size' field; the size comes from the surrounding data. So the
130 two cases need to be handled separately.) */
132 struct dwarf_expr_piece *pieces;
136 /* A piece of an object, as recorded by DW_OP_piece. */
137 struct dwarf_expr_piece
139 enum dwarf_value_location location;
143 /* This piece's address or register number. */
148 /* A pointer to the data making up this piece, for literal
151 /* The length of the available data. */
156 /* The length of the piece, in bytes. */
160 struct dwarf_expr_context *new_dwarf_expr_context (void);
161 void free_dwarf_expr_context (struct dwarf_expr_context *ctx);
163 make_cleanup_free_dwarf_expr_context (struct dwarf_expr_context *ctx);
165 void dwarf_expr_push (struct dwarf_expr_context *ctx, CORE_ADDR value);
166 void dwarf_expr_pop (struct dwarf_expr_context *ctx);
167 void dwarf_expr_eval (struct dwarf_expr_context *ctx, unsigned char *addr,
169 CORE_ADDR dwarf_expr_fetch (struct dwarf_expr_context *ctx, int n);
172 gdb_byte *read_uleb128 (gdb_byte *buf, gdb_byte *buf_end, ULONGEST * r);
173 gdb_byte *read_sleb128 (gdb_byte *buf, gdb_byte *buf_end, LONGEST * r);
174 CORE_ADDR dwarf2_read_address (struct gdbarch *gdbarch, gdb_byte *buf,
175 gdb_byte *buf_end, int addr_size);
177 #endif /* dwarf2expr.h */