gdb/dwarf2/attribute.h

   1 /* DWARF attributes
   2
   3    Copyright (C) 1994-2021 Free Software Foundation, Inc.
   4
   5    Adapted by Gary Funck (gary@intrepid.com), Intrepid Technology,
   6    Inc.  with support from Florida State University (under contract
   7    with the Ada Joint Program Office), and Silicon Graphics, Inc.
   8    Initial contribution by Brent Benson, Harris Computer Systems, Inc.,
   9    based on Fred Fish's (Cygnus Support) implementation of DWARF 1
  10    support.
  11
  12    This file is part of GDB.
  13
  14    This program is free software; you can redistribute it and/or modify
  15    it under the terms of the GNU General Public License as published by
  16    the Free Software Foundation; either version 3 of the License, or
  17    (at your option) any later version.
  18
  19    This program is distributed in the hope that it will be useful,
  20    but WITHOUT ANY WARRANTY; without even the implied warranty of
  21    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22    GNU General Public License for more details.
  23
  24    You should have received a copy of the GNU General Public License
  25    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  26
  27 #ifndef GDB_DWARF2_ATTRIBUTE_H
  28 #define GDB_DWARF2_ATTRIBUTE_H
  29
  30 #include "dwarf2.h"
  31 #include "gdbtypes.h"
  32 #include "gdbsupport/gdb_optional.h"
  33
  34 /* Blocks are a bunch of untyped bytes.  */
  35 struct dwarf_block
  36 {
  37   size_t size;
  38
  39   /* Valid only if SIZE is not zero.  */
  40   const gdb_byte *data;
  41 };
  42
  43 /* Attributes have a name and a value.  */
  44 struct attribute
  45 {
  46   /* Read the given attribute value as an address, taking the
  47      attribute's form into account.  */
  48   CORE_ADDR as_address () const;
  49
  50   /* If the attribute has a string form, return the string value;
  51      otherwise return NULL.  */
  52   const char *as_string () const;
  53
  54   /* Return the block value.  The attribute must have block form.  */
  55   dwarf_block *as_block () const
  56   {
  57     gdb_assert (form_is_block ());
  58     return u.blk;
  59   }
  60
  61   /* Return the signature.  The attribute must have signature
  62      form.  */
  63   ULONGEST as_signature () const
  64   {
  65     gdb_assert (form == DW_FORM_ref_sig8);
  66     return u.signature;
  67   }
  68
  69   /* Return the signed value.  The attribute must have the appropriate
  70      form.  */
  71   LONGEST as_signed () const
  72   {
  73     gdb_assert (form_is_signed ());
  74     return u.snd;
  75   }
  76
  77   /* Return the unsigned value, but only for attributes requiring
  78      reprocessing.  */
  79   ULONGEST as_unsigned_reprocess () const
  80   {
  81     gdb_assert (form_requires_reprocessing ());
  82     gdb_assert (requires_reprocessing);
  83     return u.unsnd;
  84   }
  85
  86   /* Return the unsigned value.  Requires that the form be an unsigned
  87      form, and that reprocessing not be needed.  */
  88   ULONGEST as_unsigned () const
  89   {
  90     gdb_assert (form_is_unsigned ());
  91     gdb_assert (!requires_reprocessing);
  92     return u.unsnd;
  93   }
  94
  95   /* Return true if the value is nonnegative.  Requires that that
  96      reprocessing not be needed.  */
  97   bool is_nonnegative () const
  98   {
  99     if (form_is_unsigned ())
 100       return true;
 101     if (form_is_signed ())
 102       return as_signed () >= 0;
 103     return false;
 104   }
 105
 106   /* Return the nonnegative value.  Requires that that reprocessing not be
 107      needed.  */
 108   ULONGEST as_nonnegative () const
 109   {
 110     if (form_is_unsigned ())
 111       return as_unsigned ();
 112     if (form_is_signed ())
 113       return (ULONGEST)as_signed ();
 114     gdb_assert (false);
 115   }
 116
 117   /* Return non-zero if ATTR's value is a section offset --- classes
 118      lineptr, loclistptr, macptr or rangelistptr --- or zero, otherwise.
 119      You may use the as_unsigned method to retrieve such offsets.
 120
 121      Section 7.5.4, "Attribute Encodings", explains that no attribute
 122      may have a value that belongs to more than one of these classes; it
 123      would be ambiguous if we did, because we use the same forms for all
 124      of them.  */
 125
 126   bool form_is_section_offset () const;
 127
 128   /* Return non-zero if ATTR's value falls in the 'constant' class, or
 129      zero otherwise.  When this function returns true, you can apply
 130      the constant_value method to it.
 131
 132      However, note that for some attributes you must check
 133      attr_form_is_section_offset before using this test.  DW_FORM_data4
 134      and DW_FORM_data8 are members of both the constant class, and of
 135      the classes that contain offsets into other debug sections
 136      (lineptr, loclistptr, macptr or rangelistptr).  The DWARF spec says
 137      that, if an attribute's can be either a constant or one of the
 138      section offset classes, DW_FORM_data4 and DW_FORM_data8 should be
 139      taken as section offsets, not constants.
 140
 141      DW_FORM_data16 is not considered as constant_value cannot handle
 142      that.  */
 143
 144   bool form_is_constant () const;
 145
 146   /* The address is always stored already as sect_offset; despite for
 147      the forms besides DW_FORM_ref_addr it is stored as cu_offset in
 148      the DWARF file.  */
 149
 150   bool form_is_ref () const
 151   {
 152     return (form == DW_FORM_ref_addr
 153             || form == DW_FORM_ref1
 154             || form == DW_FORM_ref2
 155             || form == DW_FORM_ref4
 156             || form == DW_FORM_ref8
 157             || form == DW_FORM_ref_udata
 158             || form == DW_FORM_GNU_ref_alt);
 159   }
 160
 161   /* Check if the attribute's form is a DW_FORM_block*
 162      if so return true else false.  */
 163
 164   bool form_is_block () const;
 165
 166   /* Check if the attribute's form is a string form.  */
 167   bool form_is_string () const;
 168
 169   /* Check if the attribute's form is an unsigned integer form.  */
 170   bool form_is_unsigned () const;
 171
 172   /* Check if the attribute's form is a signed integer form.  */
 173   bool form_is_signed () const;
 174
 175   /* Check if the attribute's form is a form that requires
 176      "reprocessing".  */
 177   bool form_requires_reprocessing () const;
 178
 179   /* Return DIE offset of this attribute.  Return 0 with complaint if
 180      the attribute is not of the required kind.  */
 181
 182   sect_offset get_ref_die_offset () const
 183   {
 184     if (form_is_ref ())
 185       return (sect_offset) u.unsnd;
 186     get_ref_die_offset_complaint ();
 187     return {};
 188   }
 189
 190   /* Return the constant value held by this attribute.  Return
 191      DEFAULT_VALUE if the value held by the attribute is not
 192      constant.  */
 193
 194   LONGEST constant_value (int default_value) const;
 195
 196   /* Return true if this attribute holds a canonical string.  In some
 197      cases, like C++ names, gdb will rewrite the name of a DIE to a
 198      canonical form.  This makes lookups robust when a name can be
 199      spelled different ways (e.g., "signed" or "signed int").  This
 200      flag indicates whether the value has been canonicalized.  */
 201   bool canonical_string_p () const
 202   {
 203     gdb_assert (form_is_string ());
 204     return string_is_canonical;
 205   }
 206
 207   /* Initialize this attribute to hold a non-canonical string
 208      value.  */
 209   void set_string_noncanonical (const char *str)
 210   {
 211     gdb_assert (form_is_string ());
 212     u.str = str;
 213     string_is_canonical = 0;
 214     requires_reprocessing = 0;
 215   }
 216
 217   /* Set the canonical string value for this attribute.  */
 218   void set_string_canonical (const char *str)
 219   {
 220     gdb_assert (form_is_string ());
 221     u.str = str;
 222     string_is_canonical = 1;
 223   }
 224
 225   /* Set the block value for this attribute.  */
 226   void set_block (dwarf_block *blk)
 227   {
 228     gdb_assert (form_is_block ());
 229     u.blk = blk;
 230   }
 231
 232   /* Set the signature value for this attribute.  */
 233   void set_signature (ULONGEST signature)
 234   {
 235     gdb_assert (form == DW_FORM_ref_sig8);
 236     u.signature = signature;
 237   }
 238
 239   /* Set this attribute to a signed integer.  */
 240   void set_signed (LONGEST snd)
 241   {
 242     gdb_assert (form == DW_FORM_sdata || form == DW_FORM_implicit_const);
 243     u.snd = snd;
 244   }
 245
 246   /* Set this attribute to an unsigned integer.  */
 247   void set_unsigned (ULONGEST unsnd)
 248   {
 249     gdb_assert (form_is_unsigned ());
 250     u.unsnd = unsnd;
 251     requires_reprocessing = 0;
 252   }
 253
 254   /* Temporarily set this attribute to an unsigned integer.  This is
 255      used only for those forms that require reprocessing.  */
 256   void set_unsigned_reprocess (ULONGEST unsnd)
 257   {
 258     gdb_assert (form_requires_reprocessing ());
 259     u.unsnd = unsnd;
 260     requires_reprocessing = 1;
 261   }
 262
 263   /* Set this attribute to an address.  */
 264   void set_address (CORE_ADDR addr)
 265   {
 266     gdb_assert (form == DW_FORM_addr
 267                 || ((form == DW_FORM_addrx
 268                      || form == DW_FORM_GNU_addr_index)
 269                     && requires_reprocessing));
 270     u.addr = addr;
 271     requires_reprocessing = 0;
 272   }
 273
 274   /* True if this attribute requires reprocessing.  */
 275   bool requires_reprocessing_p () const
 276   {
 277     return requires_reprocessing;
 278   }
 279
 280   /* Return the value as one of the recognized enum
 281      dwarf_defaulted_attribute constants according to DWARF5 spec,
 282      Table 7.24.  If the value is incorrect, or if this attribute has
 283      the wrong form, then a complaint is issued and DW_DEFAULTED_no is
 284      returned.  */
 285   dwarf_defaulted_attribute defaulted () const;
 286
 287   /* Return the attribute's value as a dwarf_virtuality_attribute
 288      constant according to DWARF spec.  An unrecognized value will
 289      issue a complaint and return DW_VIRTUALITY_none.  */
 290   dwarf_virtuality_attribute as_virtuality () const;
 291
 292   /* Return the attribute's value as a boolean.  An unrecognized form
 293      will issue a complaint and return false.  */
 294   bool as_boolean () const;
 295
 296   ENUM_BITFIELD(dwarf_attribute) name : 15;
 297
 298   /* A boolean that is used for forms that require reprocessing.  A
 299      form may require data not directly available in the attribute.
 300      E.g., DW_FORM_strx requires the corresponding
 301      DW_AT_str_offsets_base.  In this case, the processing for the
 302      attribute must be done in two passes.  In the first past, this
 303      flag is set and the value is an unsigned.  In the second pass,
 304      the unsigned value is turned into the correct value for the form,
 305      and this flag is cleared.  This flag is unused for other
 306      forms.  */
 307   unsigned int requires_reprocessing : 1;
 308
 309   ENUM_BITFIELD(dwarf_form) form : 15;
 310
 311   /* Has u.str already been updated by dwarf2_canonicalize_name?  This
 312      field should be in u.str but it is kept here for better struct
 313      attribute alignment.  */
 314   unsigned int string_is_canonical : 1;
 315
 316   union
 317     {
 318       const char *str;
 319       struct dwarf_block *blk;
 320       ULONGEST unsnd;
 321       LONGEST snd;
 322       CORE_ADDR addr;
 323       ULONGEST signature;
 324     }
 325   u;
 326
 327 private:
 328
 329   /* Used by get_ref_die_offset to issue a complaint.  */
 330
 331   void get_ref_die_offset_complaint () const;
 332 };
 333
 334 #endif /* GDB_DWARF2_ATTRIBUTE_H */