gdb/dwarf2/loc.h

   1 /* DWARF 2 location expression support for GDB.
   2
   3    Copyright (C) 2003-2022 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    Any values in PUSH_VALUES will be pushed before evaluating the location
 118    expression, PUSH_VALUES[0] will be pushed first, then PUSH_VALUES[1],
 119    etc.  This means the during evaluation PUSH_VALUES[0] will be at the
 120    bottom of the stack.  */
 121
 122 bool dwarf2_evaluate_property (const struct dynamic_prop *prop,
 123                                struct frame_info *frame,
 124                                const struct property_addr_info *addr_stack,
 125                                CORE_ADDR *value,
 126                                gdb::array_view<CORE_ADDR> push_values = {});
 127
 128 /* A helper for the compiler interface that compiles a single dynamic
 129    property to C code.
 130
 131    STREAM is where the C code is to be written.
 132    RESULT_NAME is the name of the generated variable.
 133    GDBARCH is the architecture to use.
 134    REGISTERS_USED is a bit-vector that is filled to note which
 135    registers are required by the generated expression.
 136    PROP is the property for which code is generated.
 137    ADDRESS is the address at which the property is considered to be
 138    evaluated.
 139    SYM the originating symbol, used for error reporting.  */
 140
 141 void dwarf2_compile_property_to_c (string_file *stream,
 142                                    const char *result_name,
 143                                    struct gdbarch *gdbarch,
 144                                    std::vector<bool> &registers_used,
 145                                    const struct dynamic_prop *prop,
 146                                    CORE_ADDR address,
 147                                    struct symbol *sym);
 148
 149 /* The symbol location baton types used by the DWARF-2 reader (i.e.
 150    SYMBOL_LOCATION_BATON for a LOC_COMPUTED symbol).  "struct
 151    dwarf2_locexpr_baton" is for a symbol with a single location
 152    expression; "struct dwarf2_loclist_baton" is for a symbol with a
 153    location list.  */
 154
 155 struct dwarf2_locexpr_baton
 156 {
 157   /* Pointer to the start of the location expression.  Valid only if SIZE is
 158      not zero.  */
 159   const gdb_byte *data;
 160
 161   /* Length of the location expression.  For optimized out expressions it is
 162      zero.  */
 163   size_t size;
 164
 165   /* When true this location expression is a reference and actually
 166      describes the address at which the value of the attribute can be
 167      found.  When false the expression provides the value of the attribute
 168      directly.  */
 169   bool is_reference;
 170
 171   /* The objfile that was used when creating this.  */
 172   dwarf2_per_objfile *per_objfile;
 173
 174   /* The compilation unit containing the symbol whose location
 175      we're computing.  */
 176   struct dwarf2_per_cu_data *per_cu;
 177 };
 178
 179 struct dwarf2_loclist_baton
 180 {
 181   /* The initial base address for the location list, based on the compilation
 182      unit.  */
 183   CORE_ADDR base_address;
 184
 185   /* Pointer to the start of the location list.  */
 186   const gdb_byte *data;
 187
 188   /* Length of the location list.  */
 189   size_t size;
 190
 191   /* The objfile that was used when creating this.  */
 192   dwarf2_per_objfile *per_objfile;
 193
 194   /* The compilation unit containing the symbol whose location
 195      we're computing.  */
 196   struct dwarf2_per_cu_data *per_cu;
 197
 198   /* Non-zero if the location list lives in .debug_loc.dwo.
 199      The format of entries in this section are different.  */
 200   unsigned char from_dwo;
 201 };
 202
 203 /* The baton used when a dynamic property is an offset to a parent
 204    type.  This can be used, for instance, then the bound of an array
 205    inside a record is determined by the value of another field inside
 206    that record.  */
 207
 208 struct dwarf2_offset_baton
 209 {
 210   /* The offset from the parent type where the value of the property
 211      is stored.  In the example provided above, this would be the offset
 212      of the field being used as the array bound.  */
 213   LONGEST offset;
 214
 215   /* The type of the object whose property is dynamic.  In the example
 216      provided above, this would the array's index type.  */
 217   struct type *type;
 218 };
 219
 220 /* A dynamic property is either expressed as a single location expression
 221    or a location list.  If the property is an indirection, pointing to
 222    another die, keep track of the targeted type in PROPERTY_TYPE.
 223    Alternatively, if the property location gives the property value
 224    directly then it will have PROPERTY_TYPE.  */
 225
 226 struct dwarf2_property_baton
 227 {
 228   /* If the property is an indirection, we need to evaluate the location
 229      in the context of the type PROPERTY_TYPE.  If the property is supplied
 230      by value then it will be of PROPERTY_TYPE.  This field should never be
 231      NULL.  */
 232   struct type *property_type;
 233   union
 234   {
 235     /* Location expression either evaluated in the context of
 236        PROPERTY_TYPE, or a value of type PROPERTY_TYPE.  */
 237     struct dwarf2_locexpr_baton locexpr;
 238
 239     /* Location list to be evaluated in the context of PROPERTY_TYPE.  */
 240     struct dwarf2_loclist_baton loclist;
 241
 242     /* The location is an offset to PROPERTY_TYPE.  */
 243     struct dwarf2_offset_baton offset_info;
 244   };
 245 };
 246
 247 extern const struct symbol_computed_ops dwarf2_locexpr_funcs;
 248 extern const struct symbol_computed_ops dwarf2_loclist_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
 253 /* Determined tail calls for constructing virtual tail call frames.  */
 254
 255 struct call_site_chain
 256   {
 257     /* Initially CALLERS == CALLEES == LENGTH.  For partially ambiguous result
 258        CALLERS + CALLEES < LENGTH.  */
 259     int callers, callees, length;
 260
 261     /* Variably sized array with LENGTH elements.  Later [0..CALLERS-1] contain
 262        top (GDB "prev") sites and [LENGTH-CALLEES..LENGTH-1] contain bottom
 263        (GDB "next") sites.  One is interested primarily in the PC field.  */
 264     struct call_site *call_site[1];
 265   };
 266
 267 extern gdb::unique_xmalloc_ptr<call_site_chain> call_site_find_chain
 268   (struct gdbarch *gdbarch, CORE_ADDR caller_pc, CORE_ADDR callee_pc);
 269
 270 /* A helper function to convert a DWARF register to an arch register.
 271    ARCH is the architecture.
 272    DWARF_REG is the register.
 273    If DWARF_REG is bad then a complaint is issued and -1 is returned.
 274    Note: Some targets get this wrong.  */
 275
 276 extern int dwarf_reg_to_regnum (struct gdbarch *arch, int dwarf_reg);
 277
 278 /* A wrapper on dwarf_reg_to_regnum to throw an exception if the
 279    DWARF register cannot be translated to an architecture register.
 280    This takes a ULONGEST instead of an int because some callers actually have
 281    a ULONGEST.  Negative values passed as ints will still be flagged as
 282    invalid.  */
 283
 284 extern int dwarf_reg_to_regnum_or_error (struct gdbarch *arch,
 285                                          ULONGEST dwarf_reg);
 286
 287 /* Helper function which throws an error if a synthetic pointer is
 288    invalid.  */
 289
 290 extern void invalid_synthetic_pointer ();
 291
 292 /* Fetch the value pointed to by a synthetic pointer.  */
 293
 294 extern struct value *indirect_synthetic_pointer
 295   (sect_offset die, LONGEST byte_offset, dwarf2_per_cu_data *per_cu,
 296    dwarf2_per_objfile *per_objfile, struct frame_info *frame,
 297    struct type *type, bool resolve_abstract_p = false);
 298
 299 #endif /* DWARF2LOC_H */