1 /* DWARF 2 location expression support for GDB. 2 3 Copyright (C) 2003-2020 Free Software Foundation, Inc. 4 5 This file is part of GDB. 6 7 This program is free software; you can redistribute it and/or modify 8 it under the terms of the GNU General Public License as published by 9 the Free Software Foundation; either version 3 of the License, or 10 (at your option) any later version. 11 12 This program is distributed in the hope that it will be useful, 13 but WITHOUT ANY WARRANTY; without even the implied warranty of 14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15 GNU General Public License for more details. 16 17 You should have received a copy of the GNU General Public License 18 along with this program. If not, see <http://www.gnu.org/licenses/>. */ 19 20 #if !defined (DWARF2LOC_H) 21 #define DWARF2LOC_H 22 23 #include "dwarf2/expr.h" 24 25 struct symbol_computed_ops; 26 struct dwarf2_per_objfile; 27 struct dwarf2_per_cu_data; 28 struct dwarf2_loclist_baton; 29 struct agent_expr; 30 struct axs_value; 31 32 /* This header is private to the DWARF-2 reader. It is shared between 33 dwarf2read.c and dwarf2loc.c. */ 34 35 /* `set debug entry-values' setting. */ 36 extern unsigned int entry_values_debug; 37 38 /* Find a particular location expression from a location list. */ 39 const gdb_byte *dwarf2_find_location_expression 40 (struct dwarf2_loclist_baton *baton, 41 size_t *locexpr_length, 42 CORE_ADDR pc); 43 44 /* Find the frame base information for FRAMEFUNC at PC. START is an 45 out parameter which is set to point to the DWARF expression to 46 compute. LENGTH is an out parameter which is set to the length of 47 the DWARF expression. This throws an exception on error or if an 48 expression is not found; the returned length will never be 49 zero. */ 50 51 extern void func_get_frame_base_dwarf_block (struct symbol *framefunc, 52 CORE_ADDR pc, 53 const gdb_byte **start, 54 size_t *length); 55 56 /* Evaluate a location description, starting at DATA and with length 57 SIZE, to find the current location of variable of TYPE in the context 58 of FRAME. */ 59 60 struct value *dwarf2_evaluate_loc_desc (struct type *type, 61 struct frame_info *frame, 62 const gdb_byte *data, 63 size_t size, 64 dwarf2_per_cu_data *per_cu, 65 dwarf2_per_objfile *per_objfile); 66 67 /* A chain of addresses that might be needed to resolve a dynamic 68 property. */ 69 70 struct property_addr_info 71 { 72 /* The type of the object whose dynamic properties, if any, are 73 being resolved. */ 74 struct type *type; 75 76 /* If not NULL, a buffer containing the object's value. */ 77 gdb::array_view<const gdb_byte> valaddr; 78 79 /* The address of that object. */ 80 CORE_ADDR addr; 81 82 /* If not NULL, a pointer to the info for the object containing 83 the object described by this node. */ 84 struct property_addr_info *next; 85 }; 86 87 /* Converts a dynamic property into a static one. FRAME is the frame in which 88 the property is evaluated; if NULL, the selected frame (if any) is used 89 instead. 90 91 ADDR_STACK is the stack of addresses that might be needed to evaluate the 92 property. When evaluating a property that is not related to a type, it can 93 be NULL. 94 95 Returns true if PROP could be converted and the static value is passed 96 back into VALUE, otherwise returns false. 97 98 If PUSH_INITIAL_VALUE is true, then the top value of ADDR_STACK 99 will be pushed before evaluating a location expression. */ 100 101 bool dwarf2_evaluate_property (const struct dynamic_prop *prop, 102 struct frame_info *frame, 103 const struct property_addr_info *addr_stack, 104 CORE_ADDR *value, 105 bool push_initial_value = false); 106 107 /* A helper for the compiler interface that compiles a single dynamic 108 property to C code. 109 110 STREAM is where the C code is to be written. 111 RESULT_NAME is the name of the generated variable. 112 GDBARCH is the architecture to use. 113 REGISTERS_USED is a bit-vector that is filled to note which 114 registers are required by the generated expression. 115 PROP is the property for which code is generated. 116 ADDRESS is the address at which the property is considered to be 117 evaluated. 118 SYM the originating symbol, used for error reporting. */ 119 120 void dwarf2_compile_property_to_c (string_file *stream, 121 const char *result_name, 122 struct gdbarch *gdbarch, 123 unsigned char *registers_used, 124 const struct dynamic_prop *prop, 125 CORE_ADDR address, 126 struct symbol *sym); 127 128 /* The symbol location baton types used by the DWARF-2 reader (i.e. 129 SYMBOL_LOCATION_BATON for a LOC_COMPUTED symbol). "struct 130 dwarf2_locexpr_baton" is for a symbol with a single location 131 expression; "struct dwarf2_loclist_baton" is for a symbol with a 132 location list. */ 133 134 struct dwarf2_locexpr_baton 135 { 136 /* Pointer to the start of the location expression. Valid only if SIZE is 137 not zero. */ 138 const gdb_byte *data; 139 140 /* Length of the location expression. For optimized out expressions it is 141 zero. */ 142 size_t size; 143 144 /* When true this location expression is a reference and actually 145 describes the address at which the value of the attribute can be 146 found. When false the expression provides the value of the attribute 147 directly. */ 148 bool is_reference; 149 150 /* The objfile that was used when creating this. */ 151 dwarf2_per_objfile *per_objfile; 152 153 /* The compilation unit containing the symbol whose location 154 we're computing. */ 155 struct dwarf2_per_cu_data *per_cu; 156 }; 157 158 struct dwarf2_loclist_baton 159 { 160 /* The initial base address for the location list, based on the compilation 161 unit. */ 162 CORE_ADDR base_address; 163 164 /* Pointer to the start of the location list. */ 165 const gdb_byte *data; 166 167 /* Length of the location list. */ 168 size_t size; 169 170 /* The objfile that was used when creating this. */ 171 dwarf2_per_objfile *per_objfile; 172 173 /* The compilation unit containing the symbol whose location 174 we're computing. */ 175 struct dwarf2_per_cu_data *per_cu; 176 177 /* Non-zero if the location list lives in .debug_loc.dwo. 178 The format of entries in this section are different. */ 179 unsigned char from_dwo; 180 }; 181 182 /* The baton used when a dynamic property is an offset to a parent 183 type. This can be used, for instance, then the bound of an array 184 inside a record is determined by the value of another field inside 185 that record. */ 186 187 struct dwarf2_offset_baton 188 { 189 /* The offset from the parent type where the value of the property 190 is stored. In the example provided above, this would be the offset 191 of the field being used as the array bound. */ 192 LONGEST offset; 193 194 /* The type of the object whose property is dynamic. In the example 195 provided above, this would the array's index type. */ 196 struct type *type; 197 }; 198 199 /* A dynamic property is either expressed as a single location expression 200 or a location list. If the property is an indirection, pointing to 201 another die, keep track of the targeted type in PROPERTY_TYPE. 202 Alternatively, if the property location gives the property value 203 directly then it will have PROPERTY_TYPE. */ 204 205 struct dwarf2_property_baton 206 { 207 /* If the property is an indirection, we need to evaluate the location 208 in the context of the type PROPERTY_TYPE. If the property is supplied 209 by value then it will be of PROPERTY_TYPE. This field should never be 210 NULL. */ 211 struct type *property_type; 212 union 213 { 214 /* Location expression either evaluated in the context of 215 PROPERTY_TYPE, or a value of type PROPERTY_TYPE. */ 216 struct dwarf2_locexpr_baton locexpr; 217 218 /* Location list to be evaluated in the context of PROPERTY_TYPE. */ 219 struct dwarf2_loclist_baton loclist; 220 221 /* The location is an offset to PROPERTY_TYPE. */ 222 struct dwarf2_offset_baton offset_info; 223 }; 224 }; 225 226 extern const struct symbol_computed_ops dwarf2_locexpr_funcs; 227 extern const struct symbol_computed_ops dwarf2_loclist_funcs; 228 229 extern const struct symbol_block_ops dwarf2_block_frame_base_locexpr_funcs; 230 extern const struct symbol_block_ops dwarf2_block_frame_base_loclist_funcs; 231 232 /* Determined tail calls for constructing virtual tail call frames. */ 233 234 struct call_site_chain 235 { 236 /* Initially CALLERS == CALLEES == LENGTH. For partially ambiguous result 237 CALLERS + CALLEES < LENGTH. */ 238 int callers, callees, length; 239 240 /* Variably sized array with LENGTH elements. Later [0..CALLERS-1] contain 241 top (GDB "prev") sites and [LENGTH-CALLEES..LENGTH-1] contain bottom 242 (GDB "next") sites. One is interested primarily in the PC field. */ 243 struct call_site *call_site[1]; 244 }; 245 246 struct call_site_stuff; 247 extern gdb::unique_xmalloc_ptr<call_site_chain> call_site_find_chain 248 (struct gdbarch *gdbarch, CORE_ADDR caller_pc, CORE_ADDR callee_pc); 249 250 /* A helper function to convert a DWARF register to an arch register. 251 ARCH is the architecture. 252 DWARF_REG is the register. 253 If DWARF_REG is bad then a complaint is issued and -1 is returned. 254 Note: Some targets get this wrong. */ 255 256 extern int dwarf_reg_to_regnum (struct gdbarch *arch, int dwarf_reg); 257 258 /* A wrapper on dwarf_reg_to_regnum to throw an exception if the 259 DWARF register cannot be translated to an architecture register. 260 This takes a ULONGEST instead of an int because some callers actually have 261 a ULONGEST. Negative values passed as ints will still be flagged as 262 invalid. */ 263 264 extern int dwarf_reg_to_regnum_or_error (struct gdbarch *arch, 265 ULONGEST dwarf_reg); 266 267 #endif /* dwarf2loc.h */ 268