gdb/dwarf2/loc.h

   1 /* DWARF 2 location expression support for GDB.
   2
   3    Copyright (C) 2003-2020 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 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                                         struct dwarf2_per_cu_data *per_cu);
  65
  66 /* A chain of addresses that might be needed to resolve a dynamic
  67    property.  */
  68
  69 struct property_addr_info
  70 {
  71   /* The type of the object whose dynamic properties, if any, are
  72      being resolved.  */
  73   struct type *type;
  74
  75   /* If not NULL, a buffer containing the object's value.  */
  76   gdb::array_view<const gdb_byte> valaddr;
  77
  78   /* The address of that object.  */
  79   CORE_ADDR addr;
  80
  81   /* If not NULL, a pointer to the info for the object containing
  82      the object described by this node.  */
  83   struct property_addr_info *next;
  84 };
  85
  86 /* Converts a dynamic property into a static one.  FRAME is the frame in which
  87    the property is evaluated; if NULL, the selected frame (if any) is used
  88    instead.
  89
  90    ADDR_STACK is the stack of addresses that might be needed to evaluate the
  91    property. When evaluating a property that is not related to a type, it can
  92    be NULL.
  93
  94    Returns true if PROP could be converted and the static value is passed
  95    back into VALUE, otherwise returns false.
  96
  97    If PUSH_INITIAL_VALUE is true, then the top value of ADDR_STACK
  98    will be pushed before evaluating a location expression.  */
  99
 100 bool dwarf2_evaluate_property (const struct dynamic_prop *prop,
 101                                struct frame_info *frame,
 102                                const struct property_addr_info *addr_stack,
 103                                CORE_ADDR *value,
 104                                bool push_initial_value = false);
 105
 106 /* A helper for the compiler interface that compiles a single dynamic
 107    property to C code.
 108
 109    STREAM is where the C code is to be written.
 110    RESULT_NAME is the name of the generated variable.
 111    GDBARCH is the architecture to use.
 112    REGISTERS_USED is a bit-vector that is filled to note which
 113    registers are required by the generated expression.
 114    PROP is the property for which code is generated.
 115    ADDRESS is the address at which the property is considered to be
 116    evaluated.
 117    SYM the originating symbol, used for error reporting.  */
 118
 119 void dwarf2_compile_property_to_c (string_file *stream,
 120                                    const char *result_name,
 121                                    struct gdbarch *gdbarch,
 122                                    unsigned char *registers_used,
 123                                    const struct dynamic_prop *prop,
 124                                    CORE_ADDR address,
 125                                    struct symbol *sym);
 126
 127 /* The symbol location baton types used by the DWARF-2 reader (i.e.
 128    SYMBOL_LOCATION_BATON for a LOC_COMPUTED symbol).  "struct
 129    dwarf2_locexpr_baton" is for a symbol with a single location
 130    expression; "struct dwarf2_loclist_baton" is for a symbol with a
 131    location list.  */
 132
 133 struct dwarf2_locexpr_baton
 134 {
 135   /* Pointer to the start of the location expression.  Valid only if SIZE is
 136      not zero.  */
 137   const gdb_byte *data;
 138
 139   /* Length of the location expression.  For optimized out expressions it is
 140      zero.  */
 141   size_t size;
 142
 143   /* When true this location expression is a reference and actually
 144      describes the address at which the value of the attribute can be
 145      found.  When false the expression provides the value of the attribute
 146      directly.  */
 147   bool is_reference;
 148
 149   /* The compilation unit containing the symbol whose location
 150      we're computing.  */
 151   struct dwarf2_per_cu_data *per_cu;
 152 };
 153
 154 struct dwarf2_loclist_baton
 155 {
 156   /* The initial base address for the location list, based on the compilation
 157      unit.  */
 158   CORE_ADDR base_address;
 159
 160   /* Pointer to the start of the location list.  */
 161   const gdb_byte *data;
 162
 163   /* Length of the location list.  */
 164   size_t size;
 165
 166   /* The compilation unit containing the symbol whose location
 167      we're computing.  */
 168   struct dwarf2_per_cu_data *per_cu;
 169
 170   /* Non-zero if the location list lives in .debug_loc.dwo.
 171      The format of entries in this section are different.  */
 172   unsigned char from_dwo;
 173 };
 174
 175 /* The baton used when a dynamic property is an offset to a parent
 176    type.  This can be used, for instance, then the bound of an array
 177    inside a record is determined by the value of another field inside
 178    that record.  */
 179
 180 struct dwarf2_offset_baton
 181 {
 182   /* The offset from the parent type where the value of the property
 183      is stored.  In the example provided above, this would be the offset
 184      of the field being used as the array bound.  */
 185   LONGEST offset;
 186
 187   /* The type of the object whose property is dynamic.  In the example
 188      provided above, this would the array's index type.  */
 189   struct type *type;
 190 };
 191
 192 /* A dynamic property is either expressed as a single location expression
 193    or a location list.  If the property is an indirection, pointing to
 194    another die, keep track of the targeted type in PROPERTY_TYPE.
 195    Alternatively, if the property location gives the property value
 196    directly then it will have PROPERTY_TYPE.  */
 197
 198 struct dwarf2_property_baton
 199 {
 200   /* If the property is an indirection, we need to evaluate the location
 201      in the context of the type PROPERTY_TYPE.  If the property is supplied
 202      by value then it will be of PROPERTY_TYPE.  This field should never be
 203      NULL.  */
 204   struct type *property_type;
 205   union
 206   {
 207     /* Location expression either evaluated in the context of
 208        PROPERTY_TYPE, or a value of type PROPERTY_TYPE.  */
 209     struct dwarf2_locexpr_baton locexpr;
 210
 211     /* Location list to be evaluated in the context of PROPERTY_TYPE.  */
 212     struct dwarf2_loclist_baton loclist;
 213
 214     /* The location is an offset to PROPERTY_TYPE.  */
 215     struct dwarf2_offset_baton offset_info;
 216   };
 217 };
 218
 219 extern const struct symbol_computed_ops dwarf2_locexpr_funcs;
 220 extern const struct symbol_computed_ops dwarf2_loclist_funcs;
 221
 222 extern const struct symbol_block_ops dwarf2_block_frame_base_locexpr_funcs;
 223 extern const struct symbol_block_ops dwarf2_block_frame_base_loclist_funcs;
 224
 225 /* Determined tail calls for constructing virtual tail call frames.  */
 226
 227 struct call_site_chain
 228   {
 229     /* Initially CALLERS == CALLEES == LENGTH.  For partially ambiguous result
 230        CALLERS + CALLEES < LENGTH.  */
 231     int callers, callees, length;
 232
 233     /* Variably sized array with LENGTH elements.  Later [0..CALLERS-1] contain
 234        top (GDB "prev") sites and [LENGTH-CALLEES..LENGTH-1] contain bottom
 235        (GDB "next") sites.  One is interested primarily in the PC field.  */
 236     struct call_site *call_site[1];
 237   };
 238
 239 struct call_site_stuff;
 240 extern gdb::unique_xmalloc_ptr<call_site_chain> call_site_find_chain
 241   (struct gdbarch *gdbarch, CORE_ADDR caller_pc, CORE_ADDR callee_pc);
 242
 243 /* A helper function to convert a DWARF register to an arch register.
 244    ARCH is the architecture.
 245    DWARF_REG is the register.
 246    If DWARF_REG is bad then a complaint is issued and -1 is returned.
 247    Note: Some targets get this wrong.  */
 248
 249 extern int dwarf_reg_to_regnum (struct gdbarch *arch, int dwarf_reg);
 250
 251 /* A wrapper on dwarf_reg_to_regnum to throw an exception if the
 252    DWARF register cannot be translated to an architecture register.
 253    This takes a ULONGEST instead of an int because some callers actually have
 254    a ULONGEST.  Negative values passed as ints will still be flagged as
 255    invalid.  */
 256
 257 extern int dwarf_reg_to_regnum_or_error (struct gdbarch *arch,
 258                                          ULONGEST dwarf_reg);
 259
 260 #endif /* dwarf2loc.h */