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