gdb/dwarf2loc.h

   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 "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 true if PROP could be converted and the static value is passed
 139    back into VALUE, otherwise returns false.  */
 140
 141 bool 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   /* When true this location expression is a reference and actually
 187      describes the address at which the value of the attribute can be
 188      found.  When false the expression provides the value of the attribute
 189      directly.  */
 190   bool is_reference;
 191
 192   /* The compilation unit containing the symbol whose location
 193      we're computing.  */
 194   struct dwarf2_per_cu_data *per_cu;
 195 };
 196
 197 struct dwarf2_loclist_baton
 198 {
 199   /* The initial base address for the location list, based on the compilation
 200      unit.  */
 201   CORE_ADDR base_address;
 202
 203   /* Pointer to the start of the location list.  */
 204   const gdb_byte *data;
 205
 206   /* Length of the location list.  */
 207   size_t size;
 208
 209   /* The compilation unit containing the symbol whose location
 210      we're computing.  */
 211   struct dwarf2_per_cu_data *per_cu;
 212
 213   /* Non-zero if the location list lives in .debug_loc.dwo.
 214      The format of entries in this section are different.  */
 215   unsigned char from_dwo;
 216 };
 217
 218 /* The baton used when a dynamic property is an offset to a parent
 219    type.  This can be used, for instance, then the bound of an array
 220    inside a record is determined by the value of another field inside
 221    that record.  */
 222
 223 struct dwarf2_offset_baton
 224 {
 225   /* The offset from the parent type where the value of the property
 226      is stored.  In the example provided above, this would be the offset
 227      of the field being used as the array bound.  */
 228   LONGEST offset;
 229
 230   /* The type of the object whose property is dynamic.  In the example
 231      provided above, this would the array's index type.  */
 232   struct type *type;
 233 };
 234
 235 /* A dynamic property is either expressed as a single location expression
 236    or a location list.  If the property is an indirection, pointing to
 237    another die, keep track of the targeted type in PROPERTY_TYPE.
 238    Alternatively, if the property location gives the property value
 239    directly then it will have PROPERTY_TYPE.  */
 240
 241 struct dwarf2_property_baton
 242 {
 243   /* If the property is an indirection, we need to evaluate the location
 244      in the context of the type PROPERTY_TYPE.  If the property is supplied
 245      by value then it will be of PROPERTY_TYPE.  This field should never be
 246      NULL.  */
 247   struct type *property_type;
 248   union
 249   {
 250     /* Location expression either evaluated in the context of
 251        PROPERTY_TYPE, or a value of type PROPERTY_TYPE.  */
 252     struct dwarf2_locexpr_baton locexpr;
 253
 254     /* Location list to be evaluated in the context of PROPERTY_TYPE.  */
 255     struct dwarf2_loclist_baton loclist;
 256
 257     /* The location is an offset to PROPERTY_TYPE.  */
 258     struct dwarf2_offset_baton offset_info;
 259   };
 260 };
 261
 262 extern const struct symbol_computed_ops dwarf2_locexpr_funcs;
 263 extern const struct symbol_computed_ops dwarf2_loclist_funcs;
 264
 265 extern const struct symbol_block_ops dwarf2_block_frame_base_locexpr_funcs;
 266 extern const struct symbol_block_ops dwarf2_block_frame_base_loclist_funcs;
 267
 268 /* Compile a DWARF location expression to an agent expression.
 269
 270    EXPR is the agent expression we are building.
 271    LOC is the agent value we modify.
 272    ARCH is the architecture.
 273    ADDR_SIZE is the size of addresses, in bytes.
 274    OP_PTR is the start of the location expression.
 275    OP_END is one past the last byte of the location expression.
 276
 277    This will throw an exception for various kinds of errors -- for
 278    example, if the expression cannot be compiled, or if the expression
 279    is invalid.  */
 280
 281 extern void dwarf2_compile_expr_to_ax (struct agent_expr *expr,
 282                                        struct axs_value *loc,
 283                                        unsigned int addr_size,
 284                                        const gdb_byte *op_ptr,
 285                                        const gdb_byte *op_end,
 286                                        struct dwarf2_per_cu_data *per_cu);
 287
 288 /* Determined tail calls for constructing virtual tail call frames.  */
 289
 290 struct call_site_chain
 291   {
 292     /* Initially CALLERS == CALLEES == LENGTH.  For partially ambiguous result
 293        CALLERS + CALLEES < LENGTH.  */
 294     int callers, callees, length;
 295
 296     /* Variably sized array with LENGTH elements.  Later [0..CALLERS-1] contain
 297        top (GDB "prev") sites and [LENGTH-CALLEES..LENGTH-1] contain bottom
 298        (GDB "next") sites.  One is interested primarily in the PC field.  */
 299     struct call_site *call_site[1];
 300   };
 301
 302 struct call_site_stuff;
 303 extern struct call_site_chain *call_site_find_chain (struct gdbarch *gdbarch,
 304                                                      CORE_ADDR caller_pc,
 305                                                      CORE_ADDR callee_pc);
 306
 307 /* A helper function to convert a DWARF register to an arch register.
 308    ARCH is the architecture.
 309    DWARF_REG is the register.
 310    If DWARF_REG is bad then a complaint is issued and -1 is returned.
 311    Note: Some targets get this wrong.  */
 312
 313 extern int dwarf_reg_to_regnum (struct gdbarch *arch, int dwarf_reg);
 314
 315 /* A wrapper on dwarf_reg_to_regnum to throw an exception if the
 316    DWARF register cannot be translated to an architecture register.
 317    This takes a ULONGEST instead of an int because some callers actually have
 318    a ULONGEST.  Negative values passed as ints will still be flagged as
 319    invalid.  */
 320
 321 extern int dwarf_reg_to_regnum_or_error (struct gdbarch *arch,
 322                                          ULONGEST dwarf_reg);
 323
 324 #endif /* dwarf2loc.h */