| 1 | /* DWARF 2 Expression Evaluator. |
| 2 | |
| 3 | Copyright (C) 2001, 2002, 2003, 2005, 2007, 2008 |
| 4 | Free Software Foundation, Inc. |
| 5 | |
| 6 | Contributed by Daniel Berlin <dan@dberlin.org>. |
| 7 | |
| 8 | This file is part of GDB. |
| 9 | |
| 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. |
| 14 | |
| 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. |
| 19 | |
| 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/>. */ |
| 22 | |
| 23 | #if !defined (DWARF2EXPR_H) |
| 24 | #define DWARF2EXPR_H |
| 25 | |
| 26 | /* The expression evaluator works with a dwarf_expr_context, describing |
| 27 | its current state and its callbacks. */ |
| 28 | struct dwarf_expr_context |
| 29 | { |
| 30 | /* The stack of values, allocated with xmalloc. */ |
| 31 | CORE_ADDR *stack; |
| 32 | |
| 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; |
| 36 | |
| 37 | /* An opaque argument provided by the caller, which will be passed |
| 38 | to all of the callback functions. */ |
| 39 | void *baton; |
| 40 | |
| 41 | /* Return the value of register number REGNUM. */ |
| 42 | CORE_ADDR (*read_reg) (void *baton, int regnum); |
| 43 | |
| 44 | /* Read LENGTH bytes at ADDR into BUF. */ |
| 45 | void (*read_mem) (void *baton, gdb_byte *buf, CORE_ADDR addr, size_t length); |
| 46 | |
| 47 | /* Return the location expression for the frame base attribute, in |
| 48 | START and LENGTH. The result must be live until the current |
| 49 | expression evaluation is complete. */ |
| 50 | void (*get_frame_base) (void *baton, gdb_byte **start, size_t *length); |
| 51 | |
| 52 | /* Return the thread-local storage address for |
| 53 | DW_OP_GNU_push_tls_address. */ |
| 54 | CORE_ADDR (*get_tls_address) (void *baton, CORE_ADDR offset); |
| 55 | |
| 56 | #if 0 |
| 57 | /* Not yet implemented. */ |
| 58 | |
| 59 | /* Return the location expression for the dwarf expression |
| 60 | subroutine in the die at OFFSET in the current compilation unit. |
| 61 | The result must be live until the current expression evaluation |
| 62 | is complete. */ |
| 63 | unsigned char *(*get_subr) (void *baton, off_t offset, size_t *length); |
| 64 | |
| 65 | /* Return the `object address' for DW_OP_push_object_address. */ |
| 66 | CORE_ADDR (*get_object_address) (void *baton); |
| 67 | #endif |
| 68 | |
| 69 | /* The current depth of dwarf expression recursion, via DW_OP_call*, |
| 70 | DW_OP_fbreg, DW_OP_push_object_address, etc., and the maximum |
| 71 | depth we'll tolerate before raising an error. */ |
| 72 | int recursion_depth, max_recursion_depth; |
| 73 | |
| 74 | /* Non-zero if the result is in a register. The register number |
| 75 | will be on the expression stack. */ |
| 76 | int in_reg; |
| 77 | |
| 78 | /* Initialization status of variable: Non-zero if variable has been |
| 79 | initialized; zero otherwise. */ |
| 80 | int initialized; |
| 81 | |
| 82 | /* An array of pieces. PIECES points to its first element; |
| 83 | NUM_PIECES is its length. |
| 84 | |
| 85 | Each time DW_OP_piece is executed, we add a new element to the |
| 86 | end of this array, recording the current top of the stack, the |
| 87 | current in_reg flag, and the size given as the operand to |
| 88 | DW_OP_piece. We then pop the top value from the stack, clear the |
| 89 | in_reg flag, and resume evaluation. |
| 90 | |
| 91 | The Dwarf spec doesn't say whether DW_OP_piece pops the top value |
| 92 | from the stack. We do, ensuring that clients of this interface |
| 93 | expecting to see a value left on the top of the stack (say, code |
| 94 | evaluating frame base expressions or CFA's specified with |
| 95 | DW_CFA_def_cfa_expression) will get an error if the expression |
| 96 | actually marks all the values it computes as pieces. |
| 97 | |
| 98 | If an expression never uses DW_OP_piece, num_pieces will be zero. |
| 99 | (It would be nice to present these cases as expressions yielding |
| 100 | a single piece, with in_reg clear, so that callers need not |
| 101 | distinguish between the no-DW_OP_piece and one-DW_OP_piece cases. |
| 102 | But expressions with no DW_OP_piece operations have no value to |
| 103 | place in a piece's 'size' field; the size comes from the |
| 104 | surrounding data. So the two cases need to be handled |
| 105 | separately.) */ |
| 106 | int num_pieces; |
| 107 | struct dwarf_expr_piece *pieces; |
| 108 | }; |
| 109 | |
| 110 | |
| 111 | /* A piece of an object, as recorded by DW_OP_piece. */ |
| 112 | struct dwarf_expr_piece |
| 113 | { |
| 114 | /* If IN_REG is zero, then the piece is in memory, and VALUE is its address. |
| 115 | If IN_REG is non-zero, then the piece is in a register, and VALUE |
| 116 | is the register number. */ |
| 117 | int in_reg; |
| 118 | |
| 119 | /* This piece's address or register number. */ |
| 120 | CORE_ADDR value; |
| 121 | |
| 122 | /* The length of the piece, in bytes. */ |
| 123 | ULONGEST size; |
| 124 | }; |
| 125 | |
| 126 | struct dwarf_expr_context *new_dwarf_expr_context (void); |
| 127 | void free_dwarf_expr_context (struct dwarf_expr_context *ctx); |
| 128 | |
| 129 | void dwarf_expr_push (struct dwarf_expr_context *ctx, CORE_ADDR value); |
| 130 | void dwarf_expr_pop (struct dwarf_expr_context *ctx); |
| 131 | void dwarf_expr_eval (struct dwarf_expr_context *ctx, unsigned char *addr, |
| 132 | size_t len); |
| 133 | CORE_ADDR dwarf_expr_fetch (struct dwarf_expr_context *ctx, int n); |
| 134 | |
| 135 | |
| 136 | gdb_byte *read_uleb128 (gdb_byte *buf, gdb_byte *buf_end, ULONGEST * r); |
| 137 | gdb_byte *read_sleb128 (gdb_byte *buf, gdb_byte *buf_end, LONGEST * r); |
| 138 | CORE_ADDR dwarf2_read_address (gdb_byte *buf, gdb_byte *buf_end, |
| 139 | int *bytes_read); |
| 140 | |
| 141 | #endif /* dwarf2expr.h */ |