gdb/dwarf2loc.h

   1 /* DWARF 2 location expression support for GDB.
   2
   3    Copyright (C) 2003-2018 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 "dwarf2expr.h"
  24
  25 struct symbol_computed_ops;
  26 struct 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 /* Return the OBJFILE associated with the compilation unit CU.  If CU
  39    came from a separate debuginfo file, then the master objfile is
  40    returned.  */
  41 struct objfile *dwarf2_per_cu_objfile (struct dwarf2_per_cu_data *cu);
  42
  43 /* Return the address size given in the compilation unit header for CU.  */
  44 int dwarf2_per_cu_addr_size (struct dwarf2_per_cu_data *cu);
  45
  46 /* Return the DW_FORM_ref_addr size given in the compilation unit header for
  47    CU.  */
  48 int dwarf2_per_cu_ref_addr_size (struct dwarf2_per_cu_data *cu);
  49
  50 /* Return the offset size given in the compilation unit header for CU.  */
  51 int dwarf2_per_cu_offset_size (struct dwarf2_per_cu_data *cu);
  52
  53 /* Return the text offset of the CU.  The returned offset comes from
  54    this CU's objfile.  If this objfile came from a separate debuginfo
  55    file, then the offset may be different from the corresponding
  56    offset in the parent objfile.  */
  57 CORE_ADDR dwarf2_per_cu_text_offset (struct dwarf2_per_cu_data *cu);
  58
  59 short dwarf2_version (struct dwarf2_per_cu_data *per_cu);
  60
  61 /* Find a particular location expression from a location list.  */
  62 const gdb_byte *dwarf2_find_location_expression
  63   (struct dwarf2_loclist_baton *baton,
  64    size_t *locexpr_length,
  65    CORE_ADDR pc);
  66
  67 struct dwarf2_locexpr_baton dwarf2_fetch_die_loc_sect_off
  68   (sect_offset offset_in_cu, struct dwarf2_per_cu_data *per_cu,
  69    CORE_ADDR (*get_frame_pc) (void *baton),
  70    void *baton, bool resolve_abstract_p = false);
  71
  72 struct dwarf2_locexpr_baton dwarf2_fetch_die_loc_cu_off
  73   (cu_offset offset_in_cu, struct dwarf2_per_cu_data *per_cu,
  74    CORE_ADDR (*get_frame_pc) (void *baton),
  75    void *baton);
  76
  77 extern const gdb_byte *dwarf2_fetch_constant_bytes (sect_offset,
  78                                                     struct dwarf2_per_cu_data *,
  79                                                     struct obstack *,
  80                                                     LONGEST *);
  81
  82 struct type *dwarf2_fetch_die_type_sect_off (sect_offset,
  83                                              struct dwarf2_per_cu_data *);
  84
  85 struct type *dwarf2_get_die_type (cu_offset die_offset,
  86                                   struct dwarf2_per_cu_data *per_cu);
  87
  88 /* Find the frame base information for FRAMEFUNC at PC.  START is an
  89    out parameter which is set to point to the DWARF expression to
  90    compute.  LENGTH is an out parameter which is set to the length of
  91    the DWARF expression.  This throws an exception on error or if an
  92    expression is not found; the returned length will never be
  93    zero.  */
  94
  95 extern void func_get_frame_base_dwarf_block (struct symbol *framefunc,
  96                                              CORE_ADDR pc,
  97                                              const gdb_byte **start,
  98                                              size_t *length);
  99
 100 /* Evaluate a location description, starting at DATA and with length
 101    SIZE, to find the current location of variable of TYPE in the context
 102    of FRAME.  */
 103
 104 struct value *dwarf2_evaluate_loc_desc (struct type *type,
 105                                         struct frame_info *frame,
 106                                         const gdb_byte *data,
 107                                         size_t size,
 108                                         struct dwarf2_per_cu_data *per_cu);
 109
 110 /* A chain of addresses that might be needed to resolve a dynamic
 111    property.  */
 112
 113 struct property_addr_info
 114 {
 115   /* The type of the object whose dynamic properties, if any, are
 116      being resolved.  */
 117   struct type *type;
 118
 119   /* If not NULL, a buffer containing the object's value.  */
 120   const gdb_byte *valaddr;
 121
 122   /* The address of that object.  */
 123   CORE_ADDR addr;
 124
 125   /* If not NULL, a pointer to the info for the object containing
 126      the object described by this node.  */
 127   struct property_addr_info *next;
 128 };
 129
 130 /* Converts a dynamic property into a static one.  FRAME is the frame in which
 131    the property is evaluated; if NULL, the selected frame (if any) is used
 132    instead.
 133
 134    ADDR_STACK is the stack of addresses that might be needed to evaluate the
 135    property. When evaluating a property that is not related to a type, it can
 136    be NULL.
 137
 138    Returns 1 if PROP could be converted and the static value is passed back
 139    into VALUE, otherwise returns 0.  */
 140
 141 int dwarf2_evaluate_property (const struct dynamic_prop *prop,
 142                               struct frame_info *frame,
 143                               struct property_addr_info *addr_stack,
 144                               CORE_ADDR *value);
 145
 146 /* A helper for the compiler interface that compiles a single dynamic
 147    property to C code.
 148
 149    STREAM is where the C code is to be written.
 150    RESULT_NAME is the name of the generated variable.
 151    GDBARCH is the architecture to use.
 152    REGISTERS_USED is a bit-vector that is filled to note which
 153    registers are required by the generated expression.
 154    PROP is the property for which code is generated.
 155    ADDRESS is the address at which the property is considered to be
 156    evaluated.
 157    SYM the originating symbol, used for error reporting.  */
 158
 159 void dwarf2_compile_property_to_c (string_file *stream,
 160                                    const char *result_name,
 161                                    struct gdbarch *gdbarch,
 162                                    unsigned char *registers_used,
 163                                    const struct dynamic_prop *prop,
 164                                    CORE_ADDR address,
 165                                    struct symbol *sym);
 166
 167 CORE_ADDR dwarf2_read_addr_index (struct dwarf2_per_cu_data *per_cu,
 168                                   unsigned int addr_index);
 169
 170 /* The symbol location baton types used by the DWARF-2 reader (i.e.
 171    SYMBOL_LOCATION_BATON for a LOC_COMPUTED symbol).  "struct
 172    dwarf2_locexpr_baton" is for a symbol with a single location
 173    expression; "struct dwarf2_loclist_baton" is for a symbol with a
 174    location list.  */
 175
 176 struct dwarf2_locexpr_baton
 177 {
 178   /* Pointer to the start of the location expression.  Valid only if SIZE is
 179      not zero.  */
 180   const gdb_byte *data;
 181
 182   /* Length of the location expression.  For optimized out expressions it is
 183      zero.  */
 184   size_t size;
 185
 186   /* The compilation unit containing the symbol whose location
 187      we're computing.  */
 188   struct dwarf2_per_cu_data *per_cu;
 189 };
 190
 191 struct dwarf2_loclist_baton
 192 {
 193   /* The initial base address for the location list, based on the compilation
 194      unit.  */
 195   CORE_ADDR base_address;
 196
 197   /* Pointer to the start of the location list.  */
 198   const gdb_byte *data;
 199
 200   /* Length of the location list.  */
 201   size_t size;
 202
 203   /* The compilation unit containing the symbol whose location
 204      we're computing.  */
 205   struct dwarf2_per_cu_data *per_cu;
 206
 207   /* Non-zero if the location list lives in .debug_loc.dwo.
 208      The format of entries in this section are different.  */
 209   unsigned char from_dwo;
 210 };
 211
 212 /* The baton used when a dynamic property is an offset to a parent
 213    type.  This can be used, for instance, then the bound of an array
 214    inside a record is determined by the value of another field inside
 215    that record.  */
 216
 217 struct dwarf2_offset_baton
 218 {
 219   /* The offset from the parent type where the value of the property
 220      is stored.  In the example provided above, this would be the offset
 221      of the field being used as the array bound.  */
 222   LONGEST offset;
 223
 224   /* The type of the object whose property is dynamic.  In the example
 225      provided above, this would the the array's index type.  */
 226   struct type *type;
 227 };
 228
 229 /* A dynamic property is either expressed as a single location expression
 230    or a location list.  If the property is an indirection, pointing to
 231    another die, keep track of the targeted type in REFERENCED_TYPE.  */
 232
 233 struct dwarf2_property_baton
 234 {
 235   /* If the property is an indirection, we need to evaluate the location
 236      in the context of the type REFERENCED_TYPE.
 237      If NULL, the location is the actual value of the property.  */
 238   struct type *referenced_type;
 239   union
 240   {
 241     /* Location expression.  */
 242     struct dwarf2_locexpr_baton locexpr;
 243
 244     /* Location list to be evaluated in the context of REFERENCED_TYPE.  */
 245     struct dwarf2_loclist_baton loclist;
 246
 247     /* The location is an offset to REFERENCED_TYPE.  */
 248     struct dwarf2_offset_baton offset_info;
 249   };
 250 };
 251
 252 extern const struct symbol_computed_ops dwarf2_locexpr_funcs;
 253 extern const struct symbol_computed_ops dwarf2_loclist_funcs;
 254
 255 extern const struct symbol_block_ops dwarf2_block_frame_base_locexpr_funcs;
 256 extern const struct symbol_block_ops dwarf2_block_frame_base_loclist_funcs;
 257
 258 /* Compile a DWARF location expression to an agent expression.
 259
 260    EXPR is the agent expression we are building.
 261    LOC is the agent value we modify.
 262    ARCH is the architecture.
 263    ADDR_SIZE is the size of addresses, in bytes.
 264    OP_PTR is the start of the location expression.
 265    OP_END is one past the last byte of the location expression.
 266
 267    This will throw an exception for various kinds of errors -- for
 268    example, if the expression cannot be compiled, or if the expression
 269    is invalid.  */
 270
 271 extern void dwarf2_compile_expr_to_ax (struct agent_expr *expr,
 272                                        struct axs_value *loc,
 273                                        unsigned int addr_size,
 274                                        const gdb_byte *op_ptr,
 275                                        const gdb_byte *op_end,
 276                                        struct dwarf2_per_cu_data *per_cu);
 277
 278 /* Determined tail calls for constructing virtual tail call frames.  */
 279
 280 struct call_site_chain
 281   {
 282     /* Initially CALLERS == CALLEES == LENGTH.  For partially ambiguous result
 283        CALLERS + CALLEES < LENGTH.  */
 284     int callers, callees, length;
 285
 286     /* Variably sized array with LENGTH elements.  Later [0..CALLERS-1] contain
 287        top (GDB "prev") sites and [LENGTH-CALLEES..LENGTH-1] contain bottom
 288        (GDB "next") sites.  One is interested primarily in the PC field.  */
 289     struct call_site *call_site[1];
 290   };
 291
 292 struct call_site_stuff;
 293 extern struct call_site_chain *call_site_find_chain (struct gdbarch *gdbarch,
 294                                                      CORE_ADDR caller_pc,
 295                                                      CORE_ADDR callee_pc);
 296
 297 /* A helper function to convert a DWARF register to an arch register.
 298    ARCH is the architecture.
 299    DWARF_REG is the register.
 300    If DWARF_REG is bad then a complaint is issued and -1 is returned.
 301    Note: Some targets get this wrong.  */
 302
 303 extern int dwarf_reg_to_regnum (struct gdbarch *arch, int dwarf_reg);
 304
 305 /* A wrapper on dwarf_reg_to_regnum to throw an exception if the
 306    DWARF register cannot be translated to an architecture register.
 307    This takes a ULONGEST instead of an int because some callers actually have
 308    a ULONGEST.  Negative values passed as ints will still be flagged as
 309    invalid.  */
 310
 311 extern int dwarf_reg_to_regnum_or_error (struct gdbarch *arch,
 312                                          ULONGEST dwarf_reg);
 313
 314 #endif /* dwarf2loc.h */