gdb/dwarf2/loc.h

   1 /* DWARF 2 location expression support for GDB.
   2
   3    Copyright (C) 2003-2024 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 #ifndef GDB_DWARF2_LOC_H
  21 #define GDB_DWARF2_LOC_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   (const dwarf2_loclist_baton *baton,
  41    size_t *locexpr_length,
  42    CORE_ADDR pc,
  43    bool at_entry = false);
  44
  45 /* Find the frame base information for FRAMEFUNC at PC.  START is an
  46    out parameter which is set to point to the DWARF expression to
  47    compute.  LENGTH is an out parameter which is set to the length of
  48    the DWARF expression.  This throws an exception on error or if an
  49    expression is not found; the returned length will never be
  50    zero.  */
  51
  52 extern void func_get_frame_base_dwarf_block (struct symbol *framefunc,
  53                                              CORE_ADDR pc,
  54                                              const gdb_byte **start,
  55                                              size_t *length);
  56
  57 /* A helper function to find the definition of NAME and compute its
  58    value.  Returns nullptr if the name is not found.  */
  59
  60 value *compute_var_value (const char *name);
  61
  62 /* Fetch call_site_parameter from caller matching KIND and KIND_U.
  63    FRAME is for callee.
  64
  65    Function always returns non-NULL, it throws NO_ENTRY_VALUE_ERROR
  66    otherwise.  */
  67
  68 call_site_parameter *dwarf_expr_reg_to_entry_parameter
  69   (const frame_info_ptr &frame, call_site_parameter_kind kind,
  70    call_site_parameter_u kind_u, dwarf2_per_cu_data **per_cu_return,
  71    dwarf2_per_objfile **per_objfile_return);
  72
  73
  74 /* Evaluate a location description, starting at DATA and with length
  75    SIZE, to find the current location of variable of TYPE in the context
  76    of FRAME.  AS_LVAL defines if the resulting struct value is expected to
  77    be a value or a location description.  */
  78
  79 value *dwarf2_evaluate_loc_desc (type *type, const frame_info_ptr &frame,
  80                                  const gdb_byte *data, size_t size,
  81                                  dwarf2_per_cu_data *per_cu,
  82                                  dwarf2_per_objfile *per_objfile,
  83                                  bool as_lval = true);
  84
  85 /* A chain of addresses that might be needed to resolve a dynamic
  86    property.  */
  87
  88 struct property_addr_info
  89 {
  90   /* The type of the object whose dynamic properties, if any, are
  91      being resolved.  */
  92   struct type *type;
  93
  94   /* If not NULL, a buffer containing the object's value.  */
  95   gdb::array_view<const gdb_byte> valaddr;
  96
  97   /* The address of that object.  */
  98   CORE_ADDR addr;
  99
 100   /* If not NULL, a pointer to the info for the object containing
 101      the object described by this node.  */
 102   struct property_addr_info *next;
 103 };
 104
 105 /* Converts a dynamic property into a static one.  FRAME is the frame in which
 106    the property is evaluated; if NULL, the selected frame (if any) is used
 107    instead.
 108
 109    ADDR_STACK is the stack of addresses that might be needed to evaluate the
 110    property. When evaluating a property that is not related to a type, it can
 111    be NULL.
 112
 113    Returns true if PROP could be converted and the static value is passed
 114    back into VALUE, otherwise returns false.
 115
 116    Any values in PUSH_VALUES will be pushed before evaluating the location
 117    expression, PUSH_VALUES[0] will be pushed first, then PUSH_VALUES[1],
 118    etc.  This means the during evaluation PUSH_VALUES[0] will be at the
 119    bottom of the stack.  */
 120
 121 bool dwarf2_evaluate_property (const struct dynamic_prop *prop,
 122                                const frame_info_ptr &frame,
 123                                const property_addr_info *addr_stack,
 124                                CORE_ADDR *value,
 125                                gdb::array_view<CORE_ADDR> push_values = {});
 126
 127 /* A helper for the compiler interface that compiles a single dynamic
 128    property to C code.
 129
 130    STREAM is where the C code is to be written.
 131    RESULT_NAME is the name of the generated variable.
 132    GDBARCH is the architecture to use.
 133    REGISTERS_USED is a bit-vector that is filled to note which
 134    registers are required by the generated expression.
 135    PROP is the property for which code is generated.
 136    ADDRESS is the address at which the property is considered to be
 137    evaluated.
 138    SYM the originating symbol, used for error reporting.  */
 139
 140 void dwarf2_compile_property_to_c (string_file *stream,
 141                                    const char *result_name,
 142                                    struct gdbarch *gdbarch,
 143                                    std::vector<bool> &registers_used,
 144                                    const struct dynamic_prop *prop,
 145                                    CORE_ADDR address,
 146                                    struct symbol *sym);
 147
 148 /* The symbol location baton types used by the DWARF-2 reader (i.e.
 149    SYMBOL_LOCATION_BATON for a LOC_COMPUTED symbol).  "struct
 150    dwarf2_locexpr_baton" is for a symbol with a single location
 151    expression; "struct dwarf2_loclist_baton" is for a symbol with a
 152    location list.  */
 153
 154 struct dwarf2_locexpr_baton
 155 {
 156   /* Pointer to the start of the location expression.  Valid only if SIZE is
 157      not zero.  */
 158   const gdb_byte *data;
 159
 160   /* Length of the location expression.  For optimized out expressions it is
 161      zero.  */
 162   size_t size;
 163
 164   /* When true this location expression is a reference and actually
 165      describes the address at which the value of the attribute can be
 166      found.  When false the expression provides the value of the attribute
 167      directly.  */
 168   bool is_reference;
 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
 178 struct dwarf2_loclist_baton
 179 {
 180   /* The initial base address for the location list, based on the compilation
 181      unit.  */
 182   unrelocated_addr base_address;
 183
 184   /* Pointer to the start of the location list.  */
 185   const gdb_byte *data;
 186
 187   /* Length of the location list.  */
 188   size_t size;
 189
 190   /* The objfile that was used when creating this.  */
 191   dwarf2_per_objfile *per_objfile;
 192
 193   /* The compilation unit containing the symbol whose location
 194      we're computing.  */
 195   struct dwarf2_per_cu_data *per_cu;
 196
 197   /* Non-zero if the location list lives in .debug_loc.dwo.
 198      The format of entries in this section are different.  */
 199   unsigned char from_dwo;
 200 };
 201
 202 /* The baton used when a dynamic property is an offset to a parent
 203    type.  This can be used, for instance, then the bound of an array
 204    inside a record is determined by the value of another field inside
 205    that record.  */
 206
 207 struct dwarf2_offset_baton
 208 {
 209   /* The offset from the parent type where the value of the property
 210      is stored.  In the example provided above, this would be the offset
 211      of the field being used as the array bound.  */
 212   LONGEST offset;
 213
 214   /* The type of the object whose property is dynamic.  In the example
 215      provided above, this would the array's index type.  */
 216   struct type *type;
 217 };
 218
 219 /* A dynamic property is either expressed as a single location expression
 220    or a location list.  If the property is an indirection, pointing to
 221    another die, keep track of the targeted type in PROPERTY_TYPE.
 222    Alternatively, if the property location gives the property value
 223    directly then it will have PROPERTY_TYPE.  */
 224
 225 struct dwarf2_property_baton
 226 {
 227   /* If the property is an indirection, we need to evaluate the location
 228      in the context of the type PROPERTY_TYPE.  If the property is supplied
 229      by value then it will be of PROPERTY_TYPE.  This field should never be
 230      NULL.  */
 231   struct type *property_type;
 232   union
 233   {
 234     /* Location expression either evaluated in the context of
 235        PROPERTY_TYPE, or a value of type PROPERTY_TYPE.  */
 236     struct dwarf2_locexpr_baton locexpr;
 237
 238     /* Location list to be evaluated in the context of PROPERTY_TYPE.  */
 239     struct dwarf2_loclist_baton loclist;
 240
 241     /* The location is an offset to PROPERTY_TYPE.  */
 242     struct dwarf2_offset_baton offset_info;
 243   };
 244 };
 245
 246 extern const struct symbol_computed_ops dwarf2_locexpr_funcs;
 247 extern const struct symbol_computed_ops dwarf2_loclist_funcs;
 248 extern const struct symbol_computed_ops ada_imported_funcs;
 249
 250 extern const struct symbol_block_ops dwarf2_block_frame_base_locexpr_funcs;
 251 extern const struct symbol_block_ops dwarf2_block_frame_base_loclist_funcs;
 252 extern const struct symbol_block_ops ada_function_alias_funcs;
 253
 254 /* Determined tail calls for constructing virtual tail call frames.  */
 255
 256 struct call_site_chain
 257   {
 258     /* Initially CALLERS == CALLEES == LENGTH.  For partially ambiguous result
 259        CALLERS + CALLEES < LENGTH.  */
 260     int callers, callees, length;
 261
 262     /* Variably sized array with LENGTH elements.  Later [0..CALLERS-1] contain
 263        top (GDB "prev") sites and [LENGTH-CALLEES..LENGTH-1] contain bottom
 264        (GDB "next") sites.  One is interested primarily in the PC field.  */
 265     struct call_site *call_site[1];
 266   };
 267
 268 extern gdb::unique_xmalloc_ptr<call_site_chain> call_site_find_chain
 269   (struct gdbarch *gdbarch, CORE_ADDR caller_pc, CORE_ADDR callee_pc);
 270
 271 /* A helper function to convert a DWARF register to an arch register.
 272    ARCH is the architecture.
 273    DWARF_REG is the register.
 274    If DWARF_REG is bad then a complaint is issued and -1 is returned.
 275    Note: Some targets get this wrong.  */
 276
 277 extern int dwarf_reg_to_regnum (struct gdbarch *arch, int dwarf_reg);
 278
 279 /* A wrapper on dwarf_reg_to_regnum to throw an exception if the
 280    DWARF register cannot be translated to an architecture register.
 281    This takes a ULONGEST instead of an int because some callers actually have
 282    a ULONGEST.  Negative values passed as ints will still be flagged as
 283    invalid.  */
 284
 285 extern int dwarf_reg_to_regnum_or_error (struct gdbarch *arch,
 286                                          ULONGEST dwarf_reg);
 287
 288 /* Helper function which throws an error if a synthetic pointer is
 289    invalid.  */
 290
 291 extern void invalid_synthetic_pointer ();
 292
 293 /* Fetch the value pointed to by a synthetic pointer.  */
 294
 295 extern struct value *indirect_synthetic_pointer
 296   (sect_offset die, LONGEST byte_offset, dwarf2_per_cu_data *per_cu,
 297    dwarf2_per_objfile *per_objfile, const frame_info_ptr &frame,
 298    struct type *type, bool resolve_abstract_p = false);
 299
 300 /* Read parameter of TYPE at (callee) FRAME's function entry.  KIND and KIND_U
 301    are used to match DW_AT_location at the caller's
 302    DW_TAG_call_site_parameter.
 303
 304    Function always returns non-NULL value.  It throws NO_ENTRY_VALUE_ERROR if
 305    it cannot resolve the parameter for any reason.  */
 306
 307 extern struct value *value_of_dwarf_reg_entry (struct type *type,
 308                                                const frame_info_ptr &frame,
 309                                                enum call_site_parameter_kind kind,
 310                                                union call_site_parameter_u kind_u);
 311 #endif /* GDB_DWARF2_LOC_H */