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.  AS_LVAL defines if the resulting struct value is expected to
  76    be a value or a location description.  */
  77
  78 struct value *dwarf2_evaluate_loc_desc (struct type *type,
  79                                         struct frame_info *frame,
  80                                         const gdb_byte *data,
  81                                         size_t size,
  82                                         dwarf2_per_cu_data *per_cu,
  83                                         dwarf2_per_objfile *per_objfile,
  84                                         bool as_lval = true);
  85
  86 /* A chain of addresses that might be needed to resolve a dynamic
  87    property.  */
  88
  89 struct property_addr_info
  90 {
  91   /* The type of the object whose dynamic properties, if any, are
  92      being resolved.  */
  93   struct type *type;
  94
  95   /* If not NULL, a buffer containing the object's value.  */
  96   gdb::array_view<const gdb_byte> valaddr;
  97
  98   /* The address of that object.  */
  99   CORE_ADDR addr;
 100
 101   /* If not NULL, a pointer to the info for the object containing
 102      the object described by this node.  */
 103   struct property_addr_info *next;
 104 };
 105
 106 /* Converts a dynamic property into a static one.  FRAME is the frame in which
 107    the property is evaluated; if NULL, the selected frame (if any) is used
 108    instead.
 109
 110    ADDR_STACK is the stack of addresses that might be needed to evaluate the
 111    property. When evaluating a property that is not related to a type, it can
 112    be NULL.
 113
 114    Returns true if PROP could be converted and the static value is passed
 115    back into VALUE, otherwise returns false.
 116
 117    If PUSH_INITIAL_VALUE is true, then the top value of ADDR_STACK
 118    will be pushed before evaluating a location expression.  */
 119
 120 bool dwarf2_evaluate_property (const struct dynamic_prop *prop,
 121                                struct frame_info *frame,
 122                                const struct property_addr_info *addr_stack,
 123                                CORE_ADDR *value,
 124                                bool push_initial_value = false);
 125
 126 /* A helper for the compiler interface that compiles a single dynamic
 127    property to C code.
 128
 129    STREAM is where the C code is to be written.
 130    RESULT_NAME is the name of the generated variable.
 131    GDBARCH is the architecture to use.
 132    REGISTERS_USED is a bit-vector that is filled to note which
 133    registers are required by the generated expression.
 134    PROP is the property for which code is generated.
 135    ADDRESS is the address at which the property is considered to be
 136    evaluated.
 137    SYM the originating symbol, used for error reporting.  */
 138
 139 void dwarf2_compile_property_to_c (string_file *stream,
 140                                    const char *result_name,
 141                                    struct gdbarch *gdbarch,
 142                                    std::vector<bool> &registers_used,
 143                                    const struct dynamic_prop *prop,
 144                                    CORE_ADDR address,
 145                                    struct symbol *sym);
 146
 147 /* The symbol location baton types used by the DWARF-2 reader (i.e.
 148    SYMBOL_LOCATION_BATON for a LOC_COMPUTED symbol).  "struct
 149    dwarf2_locexpr_baton" is for a symbol with a single location
 150    expression; "struct dwarf2_loclist_baton" is for a symbol with a
 151    location list.  */
 152
 153 struct dwarf2_locexpr_baton
 154 {
 155   /* Pointer to the start of the location expression.  Valid only if SIZE is
 156      not zero.  */
 157   const gdb_byte *data;
 158
 159   /* Length of the location expression.  For optimized out expressions it is
 160      zero.  */
 161   size_t size;
 162
 163   /* When true this location expression is a reference and actually
 164      describes the address at which the value of the attribute can be
 165      found.  When false the expression provides the value of the attribute
 166      directly.  */
 167   bool is_reference;
 168
 169   /* The objfile that was used when creating this.  */
 170   dwarf2_per_objfile *per_objfile;
 171
 172   /* The compilation unit containing the symbol whose location
 173      we're computing.  */
 174   struct dwarf2_per_cu_data *per_cu;
 175 };
 176
 177 struct dwarf2_loclist_baton
 178 {
 179   /* The initial base address for the location list, based on the compilation
 180      unit.  */
 181   CORE_ADDR base_address;
 182
 183   /* Pointer to the start of the location list.  */
 184   const gdb_byte *data;
 185
 186   /* Length of the location list.  */
 187   size_t size;
 188
 189   /* The objfile that was used when creating this.  */
 190   dwarf2_per_objfile *per_objfile;
 191
 192   /* The compilation unit containing the symbol whose location
 193      we're computing.  */
 194   struct dwarf2_per_cu_data *per_cu;
 195
 196   /* Non-zero if the location list lives in .debug_loc.dwo.
 197      The format of entries in this section are different.  */
 198   unsigned char from_dwo;
 199 };
 200
 201 /* The baton used when a dynamic property is an offset to a parent
 202    type.  This can be used, for instance, then the bound of an array
 203    inside a record is determined by the value of another field inside
 204    that record.  */
 205
 206 struct dwarf2_offset_baton
 207 {
 208   /* The offset from the parent type where the value of the property
 209      is stored.  In the example provided above, this would be the offset
 210      of the field being used as the array bound.  */
 211   LONGEST offset;
 212
 213   /* The type of the object whose property is dynamic.  In the example
 214      provided above, this would the array's index type.  */
 215   struct type *type;
 216 };
 217
 218 /* A dynamic property is either expressed as a single location expression
 219    or a location list.  If the property is an indirection, pointing to
 220    another die, keep track of the targeted type in PROPERTY_TYPE.
 221    Alternatively, if the property location gives the property value
 222    directly then it will have PROPERTY_TYPE.  */
 223
 224 struct dwarf2_property_baton
 225 {
 226   /* If the property is an indirection, we need to evaluate the location
 227      in the context of the type PROPERTY_TYPE.  If the property is supplied
 228      by value then it will be of PROPERTY_TYPE.  This field should never be
 229      NULL.  */
 230   struct type *property_type;
 231   union
 232   {
 233     /* Location expression either evaluated in the context of
 234        PROPERTY_TYPE, or a value of type PROPERTY_TYPE.  */
 235     struct dwarf2_locexpr_baton locexpr;
 236
 237     /* Location list to be evaluated in the context of PROPERTY_TYPE.  */
 238     struct dwarf2_loclist_baton loclist;
 239
 240     /* The location is an offset to PROPERTY_TYPE.  */
 241     struct dwarf2_offset_baton offset_info;
 242   };
 243 };
 244
 245 extern const struct symbol_computed_ops dwarf2_locexpr_funcs;
 246 extern const struct symbol_computed_ops dwarf2_loclist_funcs;
 247
 248 extern const struct symbol_block_ops dwarf2_block_frame_base_locexpr_funcs;
 249 extern const struct symbol_block_ops dwarf2_block_frame_base_loclist_funcs;
 250
 251 /* Determined tail calls for constructing virtual tail call frames.  */
 252
 253 struct call_site_chain
 254   {
 255     /* Initially CALLERS == CALLEES == LENGTH.  For partially ambiguous result
 256        CALLERS + CALLEES < LENGTH.  */
 257     int callers, callees, length;
 258
 259     /* Variably sized array with LENGTH elements.  Later [0..CALLERS-1] contain
 260        top (GDB "prev") sites and [LENGTH-CALLEES..LENGTH-1] contain bottom
 261        (GDB "next") sites.  One is interested primarily in the PC field.  */
 262     struct call_site *call_site[1];
 263   };
 264
 265 extern gdb::unique_xmalloc_ptr<call_site_chain> call_site_find_chain
 266   (struct gdbarch *gdbarch, CORE_ADDR caller_pc, CORE_ADDR callee_pc);
 267
 268 /* A helper function to convert a DWARF register to an arch register.
 269    ARCH is the architecture.
 270    DWARF_REG is the register.
 271    If DWARF_REG is bad then a complaint is issued and -1 is returned.
 272    Note: Some targets get this wrong.  */
 273
 274 extern int dwarf_reg_to_regnum (struct gdbarch *arch, int dwarf_reg);
 275
 276 /* A wrapper on dwarf_reg_to_regnum to throw an exception if the
 277    DWARF register cannot be translated to an architecture register.
 278    This takes a ULONGEST instead of an int because some callers actually have
 279    a ULONGEST.  Negative values passed as ints will still be flagged as
 280    invalid.  */
 281
 282 extern int dwarf_reg_to_regnum_or_error (struct gdbarch *arch,
 283                                          ULONGEST dwarf_reg);
 284
 285 /* Helper function which throws an error if a synthetic pointer is
 286    invalid.  */
 287
 288 extern void invalid_synthetic_pointer ();
 289
 290 /* Fetch the value pointed to by a synthetic pointer.  */
 291
 292 extern struct value *indirect_synthetic_pointer
 293   (sect_offset die, LONGEST byte_offset, dwarf2_per_cu_data *per_cu,
 294    dwarf2_per_objfile *per_objfile, struct frame_info *frame,
 295    struct type *type, bool resolve_abstract_p = false);
 296
 297 #endif /* dwarf2loc.h */