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