1 /* Dwarf2 Expression Evaluator 2 Copyright 2001, 2002, 2003 Free Software Foundation, Inc. 3 Contributed by Daniel Berlin ([email protected]) 4 This file is part of GDB. 5 6 This program is free software; you can redistribute it and/or modify 7 it under the terms of the GNU General Public License as published by 8 the Free Software Foundation; either version 2 of the License, or 9 (at your option) any later version. 10 11 This program is distributed in the hope that it will be useful, 12 but WITHOUT ANY WARRANTY; without even the implied warranty of 13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 GNU General Public License for more details. 15 16 You should have received a copy of the GNU General Public License 17 along with this program; if not, write to the Free Software 18 Foundation, Inc., 59 Temple Place - Suite 330, 19 Boston, MA 02111-1307, USA. */ 20 21 #if !defined (DWARF2EXPR_H) 22 #define DWARF2EXPR_H 23 24 /* The expression evaluator works with a dwarf_expr_context, describing 25 its current state and its callbacks. */ 26 struct dwarf_expr_context 27 { 28 /* The stack of values, allocated with xmalloc. */ 29 CORE_ADDR *stack; 30 31 /* The number of values currently pushed on the stack, and the 32 number of elements allocated to the stack. */ 33 int stack_len, stack_allocated; 34 35 /* An opaque argument provided by the caller, which will be passed 36 to all of the callback functions. */ 37 void *baton; 38 39 /* Return the value of register number REGNUM. */ 40 CORE_ADDR (*read_reg) (void *baton, int regnum); 41 42 /* Read LENGTH bytes at ADDR into BUF. */ 43 void (*read_mem) (void *baton, char *buf, CORE_ADDR addr, 44 size_t length); 45 46 /* Return the location expression for the frame base attribute, in 47 START and LENGTH. The result must be live until the current 48 expression evaluation is complete. */ 49 void (*get_frame_base) (void *baton, unsigned char **start, 50 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 /* Initialization status of variable: Non-zero if variable has been 78 initialized; zero otherwise. */ 79 int initialized; 80 81 /* An array of pieces. PIECES points to its first element; 82 NUM_PIECES is its length. 83 84 Each time DW_OP_piece is executed, we add a new element to the 85 end of this array, recording the current top of the stack, the 86 current in_reg flag, and the size given as the operand to 87 DW_OP_piece. We then pop the top value from the stack, clear the 88 in_reg flag, and resume evaluation. 89 90 The Dwarf spec doesn't say whether DW_OP_piece pops the top value 91 from the stack. We do, ensuring that clients of this interface 92 expecting to see a value left on the top of the stack (say, code 93 evaluating frame base expressions or CFA's specified with 94 DW_CFA_def_cfa_expression) will get an error if the expression 95 actually marks all the values it computes as pieces. 96 97 If an expression never uses DW_OP_piece, num_pieces will be zero. 98 (It would be nice to present these cases as expressions yielding 99 a single piece, with in_reg clear, so that callers need not 100 distinguish between the no-DW_OP_piece and one-DW_OP_piece cases. 101 But expressions with no DW_OP_piece operations have no value to 102 place in a piece's 'size' field; the size comes from the 103 surrounding data. So the two cases need to be handled 104 separately.) */ 105 int num_pieces; 106 struct dwarf_expr_piece *pieces; 107 }; 108 109 /* A piece of an object, as recorded by DW_OP_piece or DW_OP_bit_piece. */ 110 struct dwarf_expr_piece 111 { 112 /* If IN_REG is zero, then the piece is in memory, and VALUE is its address. 113 If IN_REG is non-zero, then the piece is in a register, and VALUE 114 is the register number. */ 115 int in_reg; 116 117 /* This piece's address or register number. */ 118 CORE_ADDR value; 119 120 /* The length of the piece, in bytes. */ 121 ULONGEST size; 122 }; 123 124 struct dwarf_expr_context *new_dwarf_expr_context (void); 125 void free_dwarf_expr_context (struct dwarf_expr_context *ctx); 126 127 void dwarf_expr_push (struct dwarf_expr_context *ctx, CORE_ADDR value); 128 void dwarf_expr_pop (struct dwarf_expr_context *ctx); 129 void dwarf_expr_eval (struct dwarf_expr_context *ctx, unsigned char *addr, 130 size_t len); 131 CORE_ADDR dwarf_expr_fetch (struct dwarf_expr_context *ctx, int n); 132 133 134 unsigned char *read_uleb128 (unsigned char *buf, unsigned char *buf_end, 135 ULONGEST * r); 136 unsigned char *read_sleb128 (unsigned char *buf, unsigned char *buf_end, 137 LONGEST * r); 138 CORE_ADDR dwarf2_read_address (unsigned char *buf, unsigned char *buf_end, 139 int *bytes_read); 140 141 #endif 142