gdb/dwarf2loc.h

   1 /* DWARF 2 location expression support for GDB.
   2
   3    Copyright (C) 2003-2017 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);
  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_get_die_type (cu_offset die_offset,
  83                                   struct dwarf2_per_cu_data *per_cu);
  84
  85 /* Find the frame base information for FRAMEFUNC at PC.  START is an
  86    out parameter which is set to point to the DWARF expression to
  87    compute.  LENGTH is an out parameter which is set to the length of
  88    the DWARF expression.  This throws an exception on error or if an
  89    expression is not found; the returned length will never be
  90    zero.  */
  91
  92 extern void func_get_frame_base_dwarf_block (struct symbol *framefunc,
  93                                              CORE_ADDR pc,
  94                                              const gdb_byte **start,
  95                                              size_t *length);
  96
  97 /* Evaluate a location description, starting at DATA and with length
  98    SIZE, to find the current location of variable of TYPE in the context
  99    of FRAME.  */
 100
 101 struct value *dwarf2_evaluate_loc_desc (struct type *type,
 102                                         struct frame_info *frame,
 103                                         const gdb_byte *data,
 104                                         size_t size,
 105                                         struct dwarf2_per_cu_data *per_cu);
 106
 107 /* A chain of addresses that might be needed to resolve a dynamic
 108    property.  */
 109
 110 struct property_addr_info
 111 {
 112   /* The type of the object whose dynamic properties, if any, are
 113      being resolved.  */
 114   struct type *type;
 115
 116   /* If not NULL, a buffer containing the object's value.  */
 117   const gdb_byte *valaddr;
 118
 119   /* The address of that object.  */
 120   CORE_ADDR addr;
 121
 122   /* If not NULL, a pointer to the info for the object containing
 123      the object described by this node.  */
 124   struct property_addr_info *next;
 125 };
 126
 127 /* Converts a dynamic property into a static one.  FRAME is the frame in which
 128    the property is evaluated; if NULL, the selected frame (if any) is used
 129    instead.
 130
 131    ADDR_STACK is the stack of addresses that might be needed to evaluate the
 132    property. When evaluating a property that is not related to a type, it can
 133    be NULL.
 134
 135    Returns 1 if PROP could be converted and the static value is passed back
 136    into VALUE, otherwise returns 0.  */
 137
 138 int dwarf2_evaluate_property (const struct dynamic_prop *prop,
 139                               struct frame_info *frame,
 140                               struct property_addr_info *addr_stack,
 141                               CORE_ADDR *value);
 142
 143 /* A helper for the compiler interface that compiles a single dynamic
 144    property to C code.
 145
 146    STREAM is where the C code is to be written.
 147    RESULT_NAME is the name of the generated variable.
 148    GDBARCH is the architecture to use.
 149    REGISTERS_USED is a bit-vector that is filled to note which
 150    registers are required by the generated expression.
 151    PROP is the property for which code is generated.
 152    ADDRESS is the address at which the property is considered to be
 153    evaluated.
 154    SYM the originating symbol, used for error reporting.  */
 155
 156 void dwarf2_compile_property_to_c (string_file &stream,
 157                                    const char *result_name,
 158                                    struct gdbarch *gdbarch,
 159                                    unsigned char *registers_used,
 160                                    const struct dynamic_prop *prop,
 161                                    CORE_ADDR address,
 162                                    struct symbol *sym);
 163
 164 CORE_ADDR dwarf2_read_addr_index (struct dwarf2_per_cu_data *per_cu,
 165                                   unsigned int addr_index);
 166
 167 /* The symbol location baton types used by the DWARF-2 reader (i.e.
 168    SYMBOL_LOCATION_BATON for a LOC_COMPUTED symbol).  "struct
 169    dwarf2_locexpr_baton" is for a symbol with a single location
 170    expression; "struct dwarf2_loclist_baton" is for a symbol with a
 171    location list.  */
 172
 173 struct dwarf2_locexpr_baton
 174 {
 175   /* Pointer to the start of the location expression.  Valid only if SIZE is
 176      not zero.  */
 177   const gdb_byte *data;
 178
 179   /* Length of the location expression.  For optimized out expressions it is
 180      zero.  */
 181   size_t size;
 182
 183   /* The compilation unit containing the symbol whose location
 184      we're computing.  */
 185   struct dwarf2_per_cu_data *per_cu;
 186 };
 187
 188 struct dwarf2_loclist_baton
 189 {
 190   /* The initial base address for the location list, based on the compilation
 191      unit.  */
 192   CORE_ADDR base_address;
 193
 194   /* Pointer to the start of the location list.  */
 195   const gdb_byte *data;
 196
 197   /* Length of the location list.  */
 198   size_t size;
 199
 200   /* The compilation unit containing the symbol whose location
 201      we're computing.  */
 202   struct dwarf2_per_cu_data *per_cu;
 203
 204   /* Non-zero if the location list lives in .debug_loc.dwo.
 205      The format of entries in this section are different.  */
 206   unsigned char from_dwo;
 207 };
 208
 209 /* The baton used when a dynamic property is an offset to a parent
 210    type.  This can be used, for instance, then the bound of an array
 211    inside a record is determined by the value of another field inside
 212    that record.  */
 213
 214 struct dwarf2_offset_baton
 215 {
 216   /* The offset from the parent type where the value of the property
 217      is stored.  In the example provided above, this would be the offset
 218      of the field being used as the array bound.  */
 219   LONGEST offset;
 220
 221   /* The type of the object whose property is dynamic.  In the example
 222      provided above, this would the the array's index type.  */
 223   struct type *type;
 224 };
 225
 226 /* A dynamic property is either expressed as a single location expression
 227    or a location list.  If the property is an indirection, pointing to
 228    another die, keep track of the targeted type in REFERENCED_TYPE.  */
 229
 230 struct dwarf2_property_baton
 231 {
 232   /* If the property is an indirection, we need to evaluate the location
 233      in the context of the type REFERENCED_TYPE.
 234      If NULL, the location is the actual value of the property.  */
 235   struct type *referenced_type;
 236   union
 237   {
 238     /* Location expression.  */
 239     struct dwarf2_locexpr_baton locexpr;
 240
 241     /* Location list to be evaluated in the context of REFERENCED_TYPE.  */
 242     struct dwarf2_loclist_baton loclist;
 243
 244     /* The location is an offset to REFERENCED_TYPE.  */
 245     struct dwarf2_offset_baton offset_info;
 246   };
 247 };
 248
 249 extern const struct symbol_computed_ops dwarf2_locexpr_funcs;
 250 extern const struct symbol_computed_ops dwarf2_loclist_funcs;
 251
 252 extern const struct symbol_block_ops dwarf2_block_frame_base_locexpr_funcs;
 253 extern const struct symbol_block_ops dwarf2_block_frame_base_loclist_funcs;
 254
 255 /* Compile a DWARF location expression to an agent expression.
 256
 257    EXPR is the agent expression we are building.
 258    LOC is the agent value we modify.
 259    ARCH is the architecture.
 260    ADDR_SIZE is the size of addresses, in bytes.
 261    OP_PTR is the start of the location expression.
 262    OP_END is one past the last byte of the location expression.
 263
 264    This will throw an exception for various kinds of errors -- for
 265    example, if the expression cannot be compiled, or if the expression
 266    is invalid.  */
 267
 268 extern void dwarf2_compile_expr_to_ax (struct agent_expr *expr,
 269                                        struct axs_value *loc,
 270                                        struct gdbarch *arch,
 271                                        unsigned int addr_size,
 272                                        const gdb_byte *op_ptr,
 273                                        const gdb_byte *op_end,
 274                                        struct dwarf2_per_cu_data *per_cu);
 275
 276 /* Determined tail calls for constructing virtual tail call frames.  */
 277
 278 struct call_site_chain
 279   {
 280     /* Initially CALLERS == CALLEES == LENGTH.  For partially ambiguous result
 281        CALLERS + CALLEES < LENGTH.  */
 282     int callers, callees, length;
 283
 284     /* Variably sized array with LENGTH elements.  Later [0..CALLERS-1] contain
 285        top (GDB "prev") sites and [LENGTH-CALLEES..LENGTH-1] contain bottom
 286        (GDB "next") sites.  One is interested primarily in the PC field.  */
 287     struct call_site *call_site[1];
 288   };
 289
 290 struct call_site_stuff;
 291 extern struct call_site_chain *call_site_find_chain (struct gdbarch *gdbarch,
 292                                                      CORE_ADDR caller_pc,
 293                                                      CORE_ADDR callee_pc);
 294
 295 /* A helper function to convert a DWARF register to an arch register.
 296    ARCH is the architecture.
 297    DWARF_REG is the register.
 298    If DWARF_REG is bad then a complaint is issued and -1 is returned.
 299    Note: Some targets get this wrong.  */
 300
 301 extern int dwarf_reg_to_regnum (struct gdbarch *arch, int dwarf_reg);
 302
 303 /* A wrapper on dwarf_reg_to_regnum to throw an exception if the
 304    DWARF register cannot be translated to an architecture register.
 305    This takes a ULONGEST instead of an int because some callers actually have
 306    a ULONGEST.  Negative values passed as ints will still be flagged as
 307    invalid.  */
 308
 309 extern int dwarf_reg_to_regnum_or_error (struct gdbarch *arch,
 310                                          ULONGEST dwarf_reg);
 311
 312 #endif /* dwarf2loc.h */