gdb/dwarf2/loc.h

   1 /* DWARF 2 location expression support for GDB.
   2
   3    Copyright (C) 2003-2021 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 /* A helper function to find the definition of NAME and compute its
  57    value.  Returns nullptr if the name is not found.  */
  58
  59 value *compute_var_value (const char *name);
  60
  61 /* Fetch call_site_parameter from caller matching KIND and KIND_U.
  62    FRAME is for callee.
  63
  64    Function always returns non-NULL, it throws NO_ENTRY_VALUE_ERROR
  65    otherwise.  */
  66
  67 struct call_site_parameter *dwarf_expr_reg_to_entry_parameter
  68   (struct frame_info *frame, enum call_site_parameter_kind kind,
  69    union call_site_parameter_u kind_u, dwarf2_per_cu_data **per_cu_return,
  70    dwarf2_per_objfile **per_objfile_return);
  71
  72
  73 /* Evaluate a location description, starting at DATA and with length
  74    SIZE, to find the current location of variable of TYPE in the context
  75    of FRAME.  */
  76
  77 struct value *dwarf2_evaluate_loc_desc (struct type *type,
  78                                         struct frame_info *frame,
  79                                         const gdb_byte *data,
  80                                         size_t size,
  81                                         dwarf2_per_cu_data *per_cu,
  82                                         dwarf2_per_objfile *per_objfile);
  83
  84 /* A chain of addresses that might be needed to resolve a dynamic
  85    property.  */
  86
  87 struct property_addr_info
  88 {
  89   /* The type of the object whose dynamic properties, if any, are
  90      being resolved.  */
  91   struct type *type;
  92
  93   /* If not NULL, a buffer containing the object's value.  */
  94   gdb::array_view<const gdb_byte> valaddr;
  95
  96   /* The address of that object.  */
  97   CORE_ADDR addr;
  98
  99   /* If not NULL, a pointer to the info for the object containing
 100      the object described by this node.  */
 101   struct property_addr_info *next;
 102 };
 103
 104 /* Converts a dynamic property into a static one.  FRAME is the frame in which
 105    the property is evaluated; if NULL, the selected frame (if any) is used
 106    instead.
 107
 108    ADDR_STACK is the stack of addresses that might be needed to evaluate the
 109    property. When evaluating a property that is not related to a type, it can
 110    be NULL.
 111
 112    Returns true if PROP could be converted and the static value is passed
 113    back into VALUE, otherwise returns false.
 114
 115    If PUSH_INITIAL_VALUE is true, then the top value of ADDR_STACK
 116    will be pushed before evaluating a location expression.  */
 117
 118 bool dwarf2_evaluate_property (const struct dynamic_prop *prop,
 119                                struct frame_info *frame,
 120                                const struct property_addr_info *addr_stack,
 121                                CORE_ADDR *value,
 122                                bool push_initial_value = false);
 123
 124 /* A helper for the compiler interface that compiles a single dynamic
 125    property to C code.
 126
 127    STREAM is where the C code is to be written.
 128    RESULT_NAME is the name of the generated variable.
 129    GDBARCH is the architecture to use.
 130    REGISTERS_USED is a bit-vector that is filled to note which
 131    registers are required by the generated expression.
 132    PROP is the property for which code is generated.
 133    ADDRESS is the address at which the property is considered to be
 134    evaluated.
 135    SYM the originating symbol, used for error reporting.  */
 136
 137 void dwarf2_compile_property_to_c (string_file *stream,
 138                                    const char *result_name,
 139                                    struct gdbarch *gdbarch,
 140                                    std::vector<bool> &registers_used,
 141                                    const struct dynamic_prop *prop,
 142                                    CORE_ADDR address,
 143                                    struct symbol *sym);
 144
 145 /* The symbol location baton types used by the DWARF-2 reader (i.e.
 146    SYMBOL_LOCATION_BATON for a LOC_COMPUTED symbol).  "struct
 147    dwarf2_locexpr_baton" is for a symbol with a single location
 148    expression; "struct dwarf2_loclist_baton" is for a symbol with a
 149    location list.  */
 150
 151 struct dwarf2_locexpr_baton
 152 {
 153   /* Pointer to the start of the location expression.  Valid only if SIZE is
 154      not zero.  */
 155   const gdb_byte *data;
 156
 157   /* Length of the location expression.  For optimized out expressions it is
 158      zero.  */
 159   size_t size;
 160
 161   /* When true this location expression is a reference and actually
 162      describes the address at which the value of the attribute can be
 163      found.  When false the expression provides the value of the attribute
 164      directly.  */
 165   bool is_reference;
 166
 167   /* The objfile that was used when creating this.  */
 168   dwarf2_per_objfile *per_objfile;
 169
 170   /* The compilation unit containing the symbol whose location
 171      we're computing.  */
 172   struct dwarf2_per_cu_data *per_cu;
 173 };
 174
 175 struct dwarf2_loclist_baton
 176 {
 177   /* The initial base address for the location list, based on the compilation
 178      unit.  */
 179   CORE_ADDR base_address;
 180
 181   /* Pointer to the start of the location list.  */
 182   const gdb_byte *data;
 183
 184   /* Length of the location list.  */
 185   size_t size;
 186
 187   /* The objfile that was used when creating this.  */
 188   dwarf2_per_objfile *per_objfile;
 189
 190   /* The compilation unit containing the symbol whose location
 191      we're computing.  */
 192   struct dwarf2_per_cu_data *per_cu;
 193
 194   /* Non-zero if the location list lives in .debug_loc.dwo.
 195      The format of entries in this section are different.  */
 196   unsigned char from_dwo;
 197 };
 198
 199 /* The baton used when a dynamic property is an offset to a parent
 200    type.  This can be used, for instance, then the bound of an array
 201    inside a record is determined by the value of another field inside
 202    that record.  */
 203
 204 struct dwarf2_offset_baton
 205 {
 206   /* The offset from the parent type where the value of the property
 207      is stored.  In the example provided above, this would be the offset
 208      of the field being used as the array bound.  */
 209   LONGEST offset;
 210
 211   /* The type of the object whose property is dynamic.  In the example
 212      provided above, this would the array's index type.  */
 213   struct type *type;
 214 };
 215
 216 /* A dynamic property is either expressed as a single location expression
 217    or a location list.  If the property is an indirection, pointing to
 218    another die, keep track of the targeted type in PROPERTY_TYPE.
 219    Alternatively, if the property location gives the property value
 220    directly then it will have PROPERTY_TYPE.  */
 221
 222 struct dwarf2_property_baton
 223 {
 224   /* If the property is an indirection, we need to evaluate the location
 225      in the context of the type PROPERTY_TYPE.  If the property is supplied
 226      by value then it will be of PROPERTY_TYPE.  This field should never be
 227      NULL.  */
 228   struct type *property_type;
 229   union
 230   {
 231     /* Location expression either evaluated in the context of
 232        PROPERTY_TYPE, or a value of type PROPERTY_TYPE.  */
 233     struct dwarf2_locexpr_baton locexpr;
 234
 235     /* Location list to be evaluated in the context of PROPERTY_TYPE.  */
 236     struct dwarf2_loclist_baton loclist;
 237
 238     /* The location is an offset to PROPERTY_TYPE.  */
 239     struct dwarf2_offset_baton offset_info;
 240   };
 241 };
 242
 243 extern const struct symbol_computed_ops dwarf2_locexpr_funcs;
 244 extern const struct symbol_computed_ops dwarf2_loclist_funcs;
 245
 246 extern const struct symbol_block_ops dwarf2_block_frame_base_locexpr_funcs;
 247 extern const struct symbol_block_ops dwarf2_block_frame_base_loclist_funcs;
 248
 249 /* Determined tail calls for constructing virtual tail call frames.  */
 250
 251 struct call_site_chain
 252   {
 253     /* Initially CALLERS == CALLEES == LENGTH.  For partially ambiguous result
 254        CALLERS + CALLEES < LENGTH.  */
 255     int callers, callees, length;
 256
 257     /* Variably sized array with LENGTH elements.  Later [0..CALLERS-1] contain
 258        top (GDB "prev") sites and [LENGTH-CALLEES..LENGTH-1] contain bottom
 259        (GDB "next") sites.  One is interested primarily in the PC field.  */
 260     struct call_site *call_site[1];
 261   };
 262
 263 extern gdb::unique_xmalloc_ptr<call_site_chain> call_site_find_chain
 264   (struct gdbarch *gdbarch, CORE_ADDR caller_pc, CORE_ADDR callee_pc);
 265
 266 /* A helper function to convert a DWARF register to an arch register.
 267    ARCH is the architecture.
 268    DWARF_REG is the register.
 269    If DWARF_REG is bad then a complaint is issued and -1 is returned.
 270    Note: Some targets get this wrong.  */
 271
 272 extern int dwarf_reg_to_regnum (struct gdbarch *arch, int dwarf_reg);
 273
 274 /* A wrapper on dwarf_reg_to_regnum to throw an exception if the
 275    DWARF register cannot be translated to an architecture register.
 276    This takes a ULONGEST instead of an int because some callers actually have
 277    a ULONGEST.  Negative values passed as ints will still be flagged as
 278    invalid.  */
 279
 280 extern int dwarf_reg_to_regnum_or_error (struct gdbarch *arch,
 281                                          ULONGEST dwarf_reg);
 282
 283 /* Fetch the value pointed to by a synthetic pointer.  */
 284
 285 extern struct value *indirect_synthetic_pointer
 286   (sect_offset die, LONGEST byte_offset, dwarf2_per_cu_data *per_cu,
 287    dwarf2_per_objfile *per_objfile, struct frame_info *frame,
 288    struct type *type, bool resolve_abstract_p = false);
 289
 290 #endif /* dwarf2loc.h */