1 \chapter{Data Representation}
2 \label{datarep:datarepresentation}
4 This section describes the binary representation of the
5 debugging information entry itself, of the attribute types
6 and of other fundamental elements described above.
9 \section{Vendor Extensibility}
10 \label{datarep:vendorextensibility}
12 To reserve a portion of the DWARF name space and ranges of
13 enumeration values for use for vendor specific extensions,
14 special labels are reserved for tag names, attribute names,
15 base type encodings, location operations, language names,
16 calling conventions and call frame instructions.
18 The labels denoting the beginning and end of the reserved
19 value range for vendor specific extensions consist of the
20 appropriate prefix (DW\-\_TAG, DW\-\_AT, DW\-\_END, DW\-\_ATE, DW\-\_OP,
21 DW\-\_LANG, DW\-\_LNE, DW\-\_CC or DW\-\_CFA respectively) followed by
22 \_lo\_user or \_hi\_user.
23 \textit{For example, for entry tags, the special
24 labels are \livetarg{chap:DWTAGlouser}{DW\-\_TAG\-\_lo\-\_user} and
25 \livetarg{chap:DWTAGhiuser}{DW\-\_TAG\-\_hi\-\_user}.}
27 range between prefix\_lo\_user and prefix\_hi\_user inclusive,
28 are reserved for vendor specific extensions. Vendors may
29 use values in this range without conflicting with current or
30 future system\dash defined values. All other values are reserved
31 for use by the system.
33 \textit{There may also be codes for vendor specific extensions
34 between the number of standard line number opcodes and
35 the first special line number opcode. However, since the
36 number of standard opcodes varies with the DWARF version,
37 the range for extensions is also version dependent. Thus,
38 DW\-\_LNS\-\_lo\-\_user and DW\-\_LNS\-\_hi\-\_user symbols are not defined.}
40 Vendor defined tags, attributes, base type encodings, location
41 atoms, language names, line number actions, calling conventions
42 and call frame instructions, conventionally use the form
43 prefix\_vendor\_id\_name, where vendor\_id is some identifying
44 character sequence chosen so as to avoid conflicts with
47 To ensure that extensions added by one vendor may be safely
48 ignored by consumers that do not understand those extensions,
49 the following rules should be followed:
52 \item New attributes should be added in such a way that a
53 debugger may recognize the format of a new attribute value
54 without knowing the content of that attribute value.
56 \item The semantics of any new attributes should not alter
57 the semantics of previously existing attributes.
59 \item The semantics of any new tags should not conflict with
60 the semantics of previously existing tags.
62 \item Do not add any new forms of attribute value.
67 \section{Reserved Values}
68 \label{datarep:reservedvalues}
69 \subsection{Error Values}
70 \label{datarep:errorvalues}
72 As a convenience for consumers of DWARF information, the value
73 0 is reserved in the encodings for attribute names, attribute
74 forms, base type encodings, location operations, languages,
75 line number program opcodes, macro information entries and tag
76 names to represent an error condition or unknown value. DWARF
77 does not specify names for these reserved values, since they
78 do not represent valid encodings for the given type and should
79 not appear in DWARF debugging information.
82 \subsection{Initial Length Values}
83 \label{datarep:initiallengthvalues}
85 An initial length field is one of the length fields that occur
86 at the beginning of those DWARF sections that have a header
87 (.debug\_aranges, .debug\_info, .debug\_types, .debug\_line,
88 .debug\_pubnames, and .debug\_pubtypes) or the length field
89 that occurs at the beginning of the CIE and FDE structures
90 in the .debug\_frame section.
92 In an initial length field, the values 0xfffffff0 through
93 0xffffffff are reserved by DWARF to indicate some form of
94 extension relative to DWARF Version 2; such values must not
95 be interpreted as a length field. The use of one such value,
96 0xffffffff, is defined below
97 (see Section \refersec{datarep:32bitand64bitdwarfformats});
99 the other values is reserved for possible future extensions.
103 \section{Executable Objects and Shared Objects}
104 \label{datarep:executableobjectsandsharedobjects}
106 The relocated addresses in the debugging information for an
107 executable object are virtual addresses and the relocated
108 addresses in the debugging information for a shared object
109 are offsets relative to the start of the lowest region of
110 memory loaded from that shared object.
112 \textit{This requirement makes the debugging information for
113 shared objects position independent. Virtual addresses in a
114 shared object may be calculated by adding the offset to the
115 base address at which the object was attached. This offset
116 is available in the run\dash time linker’s data structures.}
120 \section{32-Bit and 64-Bit DWARF Formats}
121 \label{datarep:32bitand64bitdwarfformats}
123 There are two closely related file formats. In the 32\dash bit DWARF
124 format, all values that represent lengths of DWARF sections
125 and offsets relative to the beginning of DWARF sections are
126 represented using 32\dash bits. In the 64\dash bit DWARF format, all
127 values that represent lengths of DWARF sections and offsets
128 relative to the beginning of DWARF sections are represented
129 using 64\dash bits. A special convention applies to the initial
130 length field of certain DWARF sections, as well as the CIE and
131 FDE structures, so that the 32\dash bit and 64\dash bit DWARF formats
132 can coexist and be distinguished within a single linked object.
134 The differences between the 32\dash\ and 64\dash bit
136 detailed in the following:
139 \begin{enumerate}[1.]
141 \item In the 32\dash bit DWARF format, an initial length field
142 (see Section \refersec{datarep:initiallengthvalues})
143 is an unsigned 32\dash bit integer (which
144 must be less than 0xfffffff0); in the 64\dash bit DWARF format,
145 an initial length field is 96 bits in size, and has two parts:
147 \item The first 32\dash bits have the value 0xffffffff.
149 \item The following 64\dash bits contain the actual length
150 represented as an unsigned 64\dash bit integer.
153 \textit{This representation allows a DWARF consumer to dynamically
154 detect that a DWARF section contribution is using the 64\dash bit
155 format and to adapt its processing accordingly.}
157 \item Section offset and section length fields that occur
158 in the headers of DWARF sections (other than initial length
159 fields) are listed following. In the 32\dash bit DWARF format these
160 are 32\dash bit unsigned integer values; in the 64\dash bit DWARF format,
161 they are 64\dash bit unsigned integer values.
165 Section &Name & Role \\ \hline
166 .debug\_ranges & debug\_info\_offset & offset in .debug\_info \\
167 .debug\_frame/CIE & CIE\_id & CIE distinguished value \\
168 .debug\_frame/FDE & CIE\_pointer & offset in .debug\_frame \\
169 .debug\_info & debug\_abbrev\_offset & offset in .debug\_abbrev \\
170 .debug\_line & header\_length & length of header itself \\
171 .debug\_pubnames & debug\_info\_offset & offset in .debug\_info \\
172 & debug\_info\_length & length of .debug\_info \\
174 .debug\_pubtypes & debug\_info\_offset & offset in .debug\_info \\
175 & debug\_info\_length & length of .debug\_info \\
177 .debug\_types & debug\_abbrev\_offset & offset in .debug\_info \\
178 & type\_offset & offset in of .debug\_types \\
183 \textit{The CIE\_id field in a CIE structure must be 64 bits because
184 it overlays the CIE\_pointer in a FDE structure; this implicit
185 union must be accessed to distinguish whether a CIE or FDE is
186 present, consequently, these two fields must exactly overlay
187 each other (both offset and size).}
189 \item Within the body of the .debug\_info or .debug\_types
190 section, certain forms of attribute value depend on the choice
191 of DWARF format as follows. For the 32\dash bit DWARF format,
192 the value is a 32\dash bit unsigned integer; for the 64\dash bit DWARF
193 format, the value is a 64\dash bit unsigned integer.
196 Form & Role \\ \hline
197 \livelink{chap:DWFORMrefaddr}{DW\-\_FORM\-\_ref\-\_addr}& offset in .debug\_info \\
198 \livetarg{chap:DWFORMsecoffset}{DW\-\_FORM\-\_sec\-\_offset}& offset in a section other than .debug\_info or .debug\_str \\
199 \livelink{chap:DWFORMstrp}{DW\-\_FORM\-\_strp}&offset in .debug\_str \\
200 \livelink{chap:DWOPcallref}{DW\-\_OP\-\_call\-\_ref}&offset in .debug\_info \\
204 \item Within the body of the .debug\_pubnames and
205 .debug\_pubtypes sections, the representation of the first field
206 of each tuple (which represents an offset in the .debug\_info
207 section) depends on the DWARF format as follows: in the
208 32\dash bit DWARF format, this field is a 32\dash bit unsigned integer;
209 in the 64\dash bit DWARF format, it is a 64\dash bit unsigned integer.
214 The 32\dash bit and 64\dash bit DWARF format conventions must not be
215 intermixed within a single compilation unit.
217 \textit{Attribute values and section header fields that represent
218 addresses in the target program are not affected by these
221 A DWARF consumer that supports the 64\dash bit DWARF format must
222 support executables in which some compilation units use the
223 32\dash bit format and others use the 64\dash bit format provided that
224 the combination links correctly (that is, provided that there
225 are no link\dash time errors due to truncation or overflow). (An
226 implementation is not required to guarantee detection and
227 reporting of all such errors.)
229 \textit{It is expected that DWARF producing compilers will not use
230 the 64\dash bit format by default. In most cases, the division of
231 even very large applications into a number of executable and
232 shared objects will suffice to assure that the DWARF sections
233 within each individual linked object are less than 4 GBytes
234 in size. However, for those cases where needed, the 64\dash bit
235 format allows the unusual case to be handled as well. Even
236 in this case, it is expected that only application supplied
237 objects will need to be compiled using the 64\dash bit format;
238 separate 32\dash bit format versions of system supplied shared
239 executable libraries can still be used.}
243 \section{Format of Debugging Information}
244 \label{datarep:formatofdebugginginformation}
246 For each compilation unit compiled with a DWARF producer,
247 a contribution is made to the .debug\_info section of
248 the object file. Each such contribution consists of a
249 compilation unit header
250 (see Section \refersec{datarep:compilationunitheader})
252 single \livelink{chap:DWTAGcompileunit}{DW\-\_TAG\-\_compile\-\_unit} or \livelink{chap:DWTAGpartialunit}{DW\-\_TAG\-\_partial\-\_unit} debugging
253 information entry, together with its children.
255 For each type defined in a compilation unit, a contribution may
256 be made to the .debug\_types section of the object file. Each
257 such contribution consists of a type unit header
258 (see Section \refersec{datarep:typeunitheader})
259 followed by a \livelink{chap:DWTAGtypeunit}{DW\-\_TAG\-\_type\-\_unit} entry, together with
262 Each debugging information entry begins with a code that
263 represents an entry in a separate abbreviations table. This
264 code is followed directly by a series of attribute values.
266 The appropriate entry in the abbreviations table guides the
267 interpretation of the information contained directly in the
268 .debug\_info or .debug\_types section.
270 Multiple debugging information entries may share the same
271 abbreviation table entry. Each compilation unit is associated
272 with a particular abbreviation table, but multiple compilation
273 units may share the same table.
274 \subsection{Unit Headers}
275 \label{datarep:unitheaders}
277 \subsubsection{Compilation Unit Header}
278 \label{datarep:compilationunitheader}
280 \begin{enumerate}[1.]
282 \item unit\_length (initial length) \\
283 A 4\dash byte or 12\dash byte unsigned integer representing the length
284 of the .debug\_info contribution for that compilation unit,
285 not including the length field itself. In the 32\dash bit DWARF
286 format, this is a 4\dash byte unsigned integer (which must be less
287 than 0xfffffff0); in the 64\dash bit DWARF format, this consists
288 of the 4\dash byte value 0xffffffff followed by an 8\dash byte unsigned
289 integer that gives the actual length
290 (see Section \refersec{datarep:32bitand64bitdwarfformats}).
292 \item version (uhalf)
293 A 2\dash byte unsigned integer representing the version of the
294 DWARF information for the compilation unit
295 (see Appendix \refersec{app:dwarfsectionversionnumbersinformative}).
296 The value in this field is 4.
298 \item debug\_abbrev\_offset (section offset) \\
299 A 4\dash byte or 8\dash byte unsigned offset into the .debug\_abbrev
300 section. This offset associates the compilation unit with a
301 particular set of debugging information entry abbreviations. In
302 the 32\dash bit DWARF format, this is a 4\dash byte unsigned length;
303 in the 64\dash bit DWARF format, this is an 8\dash byte unsigned length
304 (see Section \refersec{datarep:32bitand64bitdwarfformats}).
306 \item address\_size (ubyte) \\
307 A 1\dash byte unsigned integer representing the size in bytes of
308 an address on the target architecture. If the system uses
309 segmented addressing, this value represents the size of the
310 offset portion of an address.
317 \subsubsection{Type Unit Header}
318 \label{datarep:typeunitheader}
320 The header for the series of debugging information entries
321 contributing to the description of a type that has been
322 placed in its own type unit, within the .debug\_types section,
323 consists of the following information:
325 \begin{enumerate}[1.]
327 \item unit\_length (initial length) \\
328 A 4\dash byte or 12\dash byte unsigned integer representing the length
329 of the .debug\_types contribution for that compilation unit,
330 not including the length field itself. In the 32\dash bit DWARF
331 format, this is a 4\dash byte unsigned integer (which must be
332 less than 0xfffffff0); in the 64\dash bit DWARF format, this
333 consists of the 4\dash byte value 0xffffffff followed by an
334 8\dash byte unsigned integer that gives the actual length
335 (see Section \refersec{datarep:32bitand64bitdwarfformats}).
337 \item version (uhalf)
338 A 2\dash byte unsigned integer representing the version of the
339 DWARF information for the compilation unit
340 (see Appendix \refersec{app:dwarfsectionversionnumbersinformative}).
341 The value in this field is 4.
343 \item debug\_abbrev\_offset (section offset) \\
344 A 4\dash byte or 8\dash byte unsigned offset into the .debug\_abbrev
345 section. This offset associates the compilation unit with a
346 particular set of debugging information entry abbreviations. In
347 the 32\dash bit DWARF format, this is a 4\dash byte unsigned length;
348 in the 64\dash bit DWARF format, this is an 8\dash byte unsigned length
349 (see Section \refersec{datarep:32bitand64bitdwarfformats}).
351 \item address\_size (ubyte) \\
352 A 1\dash byte unsigned integer representing the size in bytes of
353 an address on the target architecture. If the system uses
354 segmented addressing, this value represents the size of the
355 offset portion of an address.
358 \item type\_signature (8\dash byte unsigned integer) \\
359 A 64\dash bit unique signature of the type described in this type
362 \textit{An attribute that refers(using \livelink{chap:DWFORMrefsig8}{DW\-\_FORM\-\_ref\-\_sig8}) to
363 the primary type contained in this type unit uses this value.}
366 \item type\_offset (section offset) \\
367 A 4\dash byte or 8\dash byte unsigned offset relative to the beginning
368 of the type unit header. This offset refers to the debugging
369 information entry that describes the type. Because the type
370 may be nested inside a namespace or other structures, and may
371 contain references to other types that have not been placed in
372 separate type units, it is not necessarily either the first or
373 the only entry in the type unit. In the 32\dash bit DWARF format,
374 this is a 4\dash byte unsigned length; in the 64\dash bit DWARF format,
375 this is an 8\dash byte unsigned length
376 (see Section \refersec{datarep:32bitand64bitdwarfformats}).
380 \subsection{Debugging Information Entry}
381 \label{datarep:debugginginformationentry}
383 Each debugging information entry begins with an unsigned LEB128
384 number containing the abbreviation code for the entry. This
385 code represents an entry within the abbreviations table
386 associated with the compilation unit containing this entry. The
387 abbreviation code is followed by a series of attribute values.
389 On some architectures, there are alignment constraints on
390 section boundaries. To make it easier to pad debugging
391 information sections to satisfy such constraints, the
392 abbreviation code 0 is reserved. Debugging information entries
393 consisting of only the abbreviation code 0 are considered
396 \subsection{Abbreviations Tables}
397 \label{datarep:abbreviationstables}
399 The abbreviations tables for all compilation units
400 are contained in a separate object file section called
401 .debug\_abbrev. As mentioned before, multiple compilation
402 units may share the same abbreviations table.
404 The abbreviations table for a single compilation unit consists
405 of a series of abbreviation declarations. Each declaration
406 specifies the tag and attributes for a particular form of
407 debugging information entry. Each declaration begins with
408 an unsigned LEB128 number representing the abbreviation
409 code itself. It is this code that appears at the beginning
410 of a debugging information entry in the .debug\_info or
411 .debug\_types section. As described above, the abbreviation
412 code 0 is reserved for null debugging information entries. The
413 abbreviation code is followed by another unsigned LEB128
414 number that encodes the entry’s tag. The encodings for the
415 tag names are given in
416 Table \refersec{tab:tagencodings}.
418 Following the tag encoding is a 1\dash byte value that determines
419 whether a debugging information entry using this abbreviation
420 has child entries or not. If the value is
421 \livetarg{chap:DWCHILDRENyes}{DW\-\_CHILDREN\-\_yes},
422 the next physically succeeding entry of any debugging
423 information entry using this abbreviation is the first
424 child of that entry. If the 1\dash byte value following the
425 abbreviation’s tag encoding is
426 \livetarg{chap:DWCHILDRENno}{DW\-\_CHILDREN\-\_no}, the next
427 physically succeeding entry of any debugging information entry
428 using this abbreviation is a sibling of that entry. (Either
429 the first child or sibling entries may be null entries). The
430 encodings for the child determination byte are given in
431 Table \refersec{tab:childdeterminationencodings}
433 Section \refersec{chap:relationshipofdebugginginformationentries},
435 sibling entries is terminated by a null entry.)
437 Finally, the child encoding is followed by a series of
438 attribute specifications. Each attribute specification
439 consists of two parts. The first part is an unsigned LEB128
440 number representing the attribute’s name. The second part
441 is an unsigned LEB128 number representing the attribute’s
442 form. The series of attribute specifications ends with an
443 entry containing 0 for the name and 0 for the form.
446 \livetarg{chap:DWFORMindirect}{DW\-\_FORM\-\_indirect} is a special case. For
447 attributes with this form, the attribute value itself in the
448 .debug\_info or .debug\_types section begins with an unsigned
449 LEB128 number that represents its form. This allows producers
450 to choose forms for particular attributes dynamically,
451 without having to add a new entry to the abbreviations table.
453 The abbreviations for a given compilation unit end with an
454 entry consisting of a 0 byte for the abbreviation code.
457 Appendix \refersec{app:compilationunitsandabbreviationstableexample}
458 for a depiction of the organization of the
459 debugging information.
461 \subsection{Attribute Encodings}
462 \label{datarep:attributeencodings}
464 The encodings for the attribute names are given in
465 Table \refersec{tab:attributeencodings}.
467 The attribute form governs how the value of the attribute is
468 encoded. There are nine classes of form, listed below. Each
469 class is a set of forms which have related representations
470 and which are given a common interpretation according to the
471 attribute in which the form is used.
473 Form \livelink{chap:DWFORMsecoffset}{DW\-\_FORM\-\_sec\-\_offset} is a member of more than one class,
474 namely \livelink{chap:lineptr}{lineptr}, \livelink{chap:loclistptr}{loclistptr}, \livelink{chap:macptr}{macptr} or \livelink{chap:rangelistptr}{rangelistptr}; the list
475 of classes allowed by the applicable attribute in
476 Table \refersec{tab:attributeencodings}
477 determines the class of the form.
479 \textit{In DWARF V3 the forms \livelink{chap:DWFORMdata4}{DW\-\_FORM\-\_data4} and \livelink{chap:DWFORMdata8}{DW\-\_FORM\-\_data8} were
480 members of either class constant or one of the classes \livelink{chap:lineptr}{lineptr},
481 \livelink{chap:loclistptr}{loclistptr}, \livelink{chap:macptr}{macptr} or \livelink{chap:rangelistptr}{rangelistptr}, depending on context. In
482 DWARF V4 \livelink{chap:DWFORMdata4}{DW\-\_FORM\-\_data4} and \livelink{chap:DWFORMdata8}{DW\-\_FORM\-\_data8} are members of class
483 constant in all cases. The new \livelink{chap:DWFORMsecoffset}{DW\-\_FORM\-\_sec\-\_offset} replaces
484 their usage for the other classes.}
486 Each possible form belongs to one or more of the following classes:
490 Represented as an object of appropriate size to hold an
491 address on the target machine
492 (\livetarg{chap:DWFORMaddr}{DW\-\_FORM\-\_addr}). The size is
493 encoded in the compilation unit header
494 (see Section \refersec{datarep:compilationunitheader}).
495 This address is relocatable in a relocatable object file and
496 is relocated in an executable file or shared object.
499 Blocks come in four forms:
501 \begin{myindentpara}{1cm}
502 A 1\dash byte length followed by 0 to 255 contiguous information
503 bytes (\livetarg{chap:DWFORMblock1}{DW\-\_FORM\-\_block1}).
506 \begin{myindentpara}{1cm}
507 A 2\dash byte length followed by 0 to 65,535 contiguous information
508 bytes (\livetarg{chap:DWFORMblock2}{DW\-\_FORM\-\_block2}).
512 \begin{myindentpara}{1cm}
513 A 4\dash byte length followed by 0 to 4,294,967,295 contiguous
514 information bytes (\livetarg{chap:DWFORMblock4}{DW\-\_FORM\-\_block4}).
518 \begin{myindentpara}{1cm}
519 An unsigned LEB128 length followed by the number of bytes
520 specified by the length (\livetarg{chap:DWFORMblock}{DW\-\_FORM\-\_block}).
523 In all forms, the length is the number of information bytes
524 that follow. The information bytes may contain any mixture
525 of relocated (or relocatable) addresses, references to other
526 debugging information entries or data bytes.
529 There are six forms of constants. There are fixed length
530 constant data forms for one, two, four and eight byte values
532 \livetarg{chap:DWFORMdata1}{DW\-\_FORM\-\_data1},
533 \livetarg{chap:DWFORMdata2}{DW\-\_FORM\-\_data2},
534 \livetarg{chap:DWFORMdata4}{DW\-\_FORM\-\_data4},
535 and \livetarg{chap:DWFORMdata8}{DW\-\_FORM\-\_data8}).
536 There are also variable length constant
537 data forms encoded using LEB128 numbers (see below). Both
538 signed (\livetarg{chap:DWFORMsdata}{DW\-\_FORM\-\_sdata}) and unsigned
539 (\livetarg{chap:DWFORMudata}{DW\-\_FORM\-\_udata}) variable
540 length constants are available
542 The data in \livelink{chap:DWFORMdata1}{DW\-\_FORM\-\_data1},
543 \livelink{chap:DWFORMdata2}{DW\-\_FORM\-\_data2},
544 \livelink{chap:DWFORMdata4}{DW\-\_FORM\-\_data4} and
545 \livelink{chap:DWFORMdata8}{DW\-\_FORM\-\_data8}
546 can be anything. Depending on context, it may
547 be a signed integer, an unsigned integer, a floating\dash point
548 constant, or anything else. A consumer must use context to
549 know how to interpret the bits, which if they are target
550 machine data (such as an integer or floating point constant)
551 will be in target machine byte\dash order.
553 \textit{If one of the \livetarg{chap:DWFORMdata}{DW\-\_FORM\-\_data}<n> forms is used to represent a
554 signed or unsigned integer, it can be hard for a consumer
555 to discover the context necessary to determine which
556 interpretation is intended. Producers are therefore strongly
557 encouraged to use \livelink{chap:DWFORMsdata}{DW\-\_FORM\-\_sdata} or
558 \livelink{chap:DWFORMudata}{DW\-\_FORM\-\_udata} for signed and
559 unsigned integers respectively, rather than
560 \livelink{chap:DWFORMdata}{DW\-\_FORM\-\_data} \textless n \textgreater.}
563 \item \livelink{chap:exprloc}{exprloc} \\
564 This is an unsigned LEB128 length followed by the
565 number of information bytes specified by the length
566 (\livetarg{chap:DWFORMexprloc}{DW\-\_FORM\-\_exprloc}).
567 The information bytes contain a DWARF
569 (see Section \refersec{chap:dwarfexpressions})
570 or location description
571 (see Section \refersec{chap:locationdescriptions}).
574 A flag is represented explicitly as a single byte of data
575 (\livetarg{chap:DWFORMflag}{DW\-\_FORM\-\_flag}) or
576 implicitly (\livetarg{chap:DWFORMflagpresent}{DW\-\_FORM\-\_flag\-\_present}). In the
577 first case, if the flag has value zero, it indicates the
578 absence of the attribute; if the flag has a non\dash zero value,
579 it indicates the presence of the attribute. In the second
580 case, the attribute is implicitly indicated as present, and
581 no value is encoded in the debugging information entry itself.
583 \item \livelink{chap:lineptr}{lineptr} \\
584 This is an offset into the .debug\_line section
585 (\livelink{chap:DWFORMsecoffset}{DW\-\_FORM\-\_sec\-\_offset}). It consists of an offset from the
586 beginning of the .debug\_line section to the first byte of
587 the data making up the line number list for the compilation
589 It is relocatable in a relocatable object file, and
590 relocated in an executable or shared object. In the 32\dash bit
591 DWARF format, this offset is a 4\dash byte unsigned value;
592 in the 64\dash bit DWARF format, it is an 8\dash byte unsigned value
593 (see Section \refersec{datarep:32bitand64bitdwarfformats}).
596 \item \livelink{chap:loclistptr}{loclistptr} \\
597 This is an offset into the .debug\_loc section
598 (\livelink{chap:DWFORMsecoffset}{DW\-\_FORM\-\_sec\-\_offset}). It consists of an offset from the
599 beginning of the .debug\_loc section to the first byte of
600 the data making up the location list for the compilation
602 It is relocatable in a relocatable object file, and
603 relocated in an executable or shared object. In the 32\dash bit
604 DWARF format, this offset is a 4\dash byte unsigned value;
605 in the 64\dash bit DWARF format, it is an 8\dash byte unsigned value
606 (see Section \refersec{datarep:32bitand64bitdwarfformats}).
609 \item \livelink{chap:macptr}{macptr} \\
610 This is an offset into the .debug\_macinfo section
611 (\livelink{chap:DWFORMsecoffset}{DW\-\_FORM\-\_sec\-\_offset}). It consists of an offset from the
612 beginning of the .debug\_macinfo section to the first byte of
613 the data making up the macro information list for the compilation
615 It is relocatable in a relocatable object file, and
616 relocated in an executable or shared object. In the 32\dash bit
617 DWARF format, this offset is a 4\dash byte unsigned value;
618 in the 64\dash bit DWARF format, it is an 8\dash byte unsigned value
619 (see Section \refersec{datarep:32bitand64bitdwarfformats}).
621 \item \livelink{chap:rangelistptr}{rangelistptr} \\
622 This is an offset into the .debug\_ranges section
623 (\livelink{chap:DWFORMsecoffset}{DW\-\_FORM\-\_sec\-\_offset}).
625 offset from the beginning of the .debug\_ranges section
626 to the beginning of the non\dash contiguous address ranges
627 information for the referencing entity.
629 a relocatable object file, and relocated in an executable or
630 shared object. In the 32\dash bit DWARF format, this offset
631 is a 4\dash byte unsigned value; in the 64\dash bit DWARF
632 format, it is an 8\dash byte unsigned value (see Section
633 \refersec{datarep:32bitand64bitdwarfformats}).
636 \textit{Because classes \livelink{chap:lineptr}{lineptr}, \livelink{chap:loclistptr}{loclistptr}, \livelink{chap:macptr}{macptr} and \livelink{chap:rangelistptr}{rangelistptr}
637 share a common representation, it is not possible for an
638 attribute to allow more than one of these classes}
643 There are three types of reference.
645 The first type of reference can identify any debugging
646 information entry within the containing unit. This type of
647 reference is an offset from the first byte of the compilation
648 header for the compilation unit containing the reference. There
649 are five forms for this type of reference. There are fixed
650 length forms for one, two, four and eight byte offsets
651 (respectively, \livetarg{chap:DWFORMref1}{DW\-\_FORM\-\_ref1},
652 \livetarg{chap:DWFORMref2}{DW\-\_FORM\-\_ref2},
653 \livetarg{chap:DWFORMref4}{DW\-\_FORM\-\_ref4},
654 and \livetarg{chap:DWFORMref8}{DW\-\_FORM\-\_ref8}).
655 There is also an unsigned variable
656 length offset encoded form that uses unsigned LEB128 numbers
657 (\livetarg{chap:DWFORMrefudata}{DW\-\_FORM\-\_ref\-\_udata}).
658 Because this type of reference is within
659 the containing compilation unit no relocation of the value
662 The second type of reference can identify any debugging
663 information entry within a .debug\_info section; in particular,
664 it may refer to an entry in a different compilation unit
665 from the unit containing the reference, and may refer to an
666 entry in a different shared object. This type of reference
667 (\livetarg{chap:DWFORMrefaddr}{DW\-\_FORM\-\_ref\-\_addr}) is an offset from the beginning of the
668 .debug\_info section of the target executable or shared object;
669 it is relocatable in a relocatable object file and frequently
670 relocated in an executable file or shared object. For
671 references from one shared object or static executable file
672 to another, the relocation and identification of the target
673 object must be performed by the consumer. In the 32\dash bit DWARF
674 format, this offset is a 4\dash byte unsigned value;
675 in the 64\dash bit DWARF format, it is an 8\dash byte
677 (see Section \refersec{datarep:32bitand64bitdwarfformats}).
679 A debugging information entry that may be referenced by
680 another compilation unit using \livelink{chap:DWFORMrefaddr}{DW\-\_FORM\-\_ref\-\_addr} must have a
681 global symbolic name.
683 For a reference from one executable or shared object to
684 another, the reference is resolved by the debugger to identify
685 the shared object or executable and the offset into that
686 object’s .debug\_info section in the same fashion as the run
687 time loader, either when the debug information is first read,
688 or when the reference is used.
690 The third type of reference can identify any debugging
691 information type entry that has been placed in its own
692 type unit. This type of
693 reference (\livetarg{chap:DWFORMrefsig8}{DW\-\_FORM\-\_ref\-\_sig8}) is the
694 64\dash bit type signature
695 (see Section \refersec{datarep:typesignaturecomputation})
699 The use of compilation unit relative references will reduce the
700 number of link\dash time relocations and so speed up linking. The
701 use of the second and third type of reference allows for the
702 sharing of information, such as types, across compilation
705 A reference to any kind of compilation unit identifies the
706 debugging information entry for that unit, not the preceding
710 A string is a sequence of contiguous non\dash null bytes followed by
711 one null byte. A string may be represented immediately in the
712 debugging information entry itself
713 (\livetarg{chap:DWFORMstring}{DW\-\_FORM\-\_string}), or may
714 be represented as an offset into a string table contained in
715 the .debug\_str section of the object file
716 (\livetarg{chap:DWFORMstrp}{DW\-\_FORM\-\_strp}). In
717 the 32\dash bit DWARF format, the representation of a
718 \livelink{chap:DWFORMstrp}{DW\-\_FORM\-\_strp}
719 value is a 4\dash byte unsigned offset; in the 64\dash bit DWARF format,
720 it is an 8\dash byte unsigned offset
721 (see Section \refersec{datarep:32bitand64bitdwarfformats}).
723 If the \livelink{chap:DWATuseUTF8}{DW\-\_AT\-\_use\-\_UTF8} attribute is specified for the
724 compilation unit entry, string values are encoded using the
725 UTF\dash 8 (Unicode Transformation Format\dash 8) from the Universal
726 Character Set standard (ISO/IEC 10646\dash 1:1993). Otherwise,
727 the string representation is unspecified.
729 The Unicode Standard Version 3 is fully compatible with
730 ISO/IEC 10646\dash 1:1993. It contains all the same characters
731 and encoding points as ISO/IEC 10646, as well as additional
732 information about the characters and their use.
734 Earlier versions of DWARF did not specify the representation
735 of strings; for compatibility, this version also does
736 not. However, the UTF\dash 8 representation is strongly recommended.
740 In no case does an attribute use one of the classes \livelink{chap:lineptr}{lineptr},
741 \livelink{chap:loclistptr}{loclistptr}, \livelink{chap:macptr}{macptr} or \livelink{chap:rangelistptr}{rangelistptr} to point into either the
742 .debug\_info or .debug\_str section.
744 The form encodings are listed in
745 Table \refersec{tab:attributeformencodings}.
748 \setlength{\extrarowheight}{0.1cm}
749 \begin{longtable}{l|l}
750 \caption{Tag encodings} \label{tab:tagencodings} \\
751 \hline \\ \bfseries Tag name&\bfseries Value\\ \hline
753 \bfseries Tag name&\bfseries Value \\ \hline
755 \hline \emph{Continued on next page}
759 \livelink{chap:DWTAGarraytype}{DW\-\_TAG\-\_array\-\_type} &0x01 \\
760 \livelink{chap:DWTAGclasstype}{DW\-\_TAG\-\_class\-\_type}&0x02 \\
761 \livelink{chap:DWTAGentrypoint}{DW\-\_TAG\-\_entry\-\_point}&0x03 \\
762 \livelink{chap:DWTAGenumerationtype}{DW\-\_TAG\-\_enumeration\-\_type}&0x04 \\
763 \livelink{chap:DWTAGformalparameter}{DW\-\_TAG\-\_formal\-\_parameter}&0x05 \\
764 \livelink{chap:DWTAGimporteddeclaration}{DW\-\_TAG\-\_imported\-\_declaration}&0x08 \\
765 \livelink{chap:DWTAGlabel}{DW\-\_TAG\-\_label}&0x0a \\
766 \livelink{chap:DWTAGlexicalblock}{DW\-\_TAG\-\_lexical\-\_block}&0x0b \\
767 \livelink{chap:DWTAGmember}{DW\-\_TAG\-\_member}&0x0d \\
768 \livelink{chap:DWTAGpointertype}{DW\-\_TAG\-\_pointer\-\_type}&0x0f \\
769 \livelink{chap:DWTAGreferencetype}{DW\-\_TAG\-\_reference\-\_type}&0x10 \\
770 \livelink{chap:DWTAGcompileunit}{DW\-\_TAG\-\_compile\-\_unit}&0x11 \\
771 \livelink{chap:DWTAGstringtype}{DW\-\_TAG\-\_string\-\_type}&0x12 \\
772 \livelink{chap:DWTAGstructuretype}{DW\-\_TAG\-\_structure\-\_type}&0x13 \\
773 \livelink{chap:DWTAGsubroutinetype}{DW\-\_TAG\-\_subroutine\-\_type}&0x15 \\
774 \livelink{chap:DWTAGtypedef}{DW\-\_TAG\-\_typedef}&0x16 \\
775 \livelink{chap:DWTAGuniontype}{DW\-\_TAG\-\_union\-\_type}&0x17 \\
776 \livelink{chap:DWTAGunspecifiedparameters}{DW\-\_TAG\-\_unspecified\-\_parameters}&0x18 \\
777 \livelink{chap:DWTAGvariant}{DW\-\_TAG\-\_variant}&0x19 \\
778 \livelink{chap:DWTAGcommonblock}{DW\-\_TAG\-\_common\-\_block}&0x1a \\
779 \livelink{chap:DWTAGcommoninclusion}{DW\-\_TAG\-\_common\-\_inclusion}&0x1b \\
780 \livelink{chap:DWTAGinheritance}{DW\-\_TAG\-\_inheritance}&0x1c \\
781 \livelink{chap:DWTAGinlinedsubroutine}{DW\-\_TAG\-\_inlined\-\_subroutine}&0x1d \\
782 \livelink{chap:DWTAGmodule}{DW\-\_TAG\-\_module}&0x1e \\
783 \livelink{chap:DWTAGptrtomembertype}{DW\-\_TAG\-\_ptr\-\_to\-\_member\-\_type}&0x1f \\
784 \livelink{chap:DWTAGsettype}{DW\-\_TAG\-\_set\-\_type}&0x20 \\
785 \livelink{chap:DWTAGsubrangetype}{DW\-\_TAG\-\_subrange\-\_type}&0x21 \\
786 \livelink{chap:DWTAGwithstmt}{DW\-\_TAG\-\_with\-\_stmt}&0x22 \\
787 \livelink{chap:DWTAGaccessdeclaration}{DW\-\_TAG\-\_access\-\_declaration}&0x23 \\
788 \livelink{chap:DWTAGbasetype}{DW\-\_TAG\-\_base\-\_type}&0x24 \\
789 \livelink{chap:DWTAGcatchblock}{DW\-\_TAG\-\_catch\-\_block}&0x25 \\
790 \livelink{chap:DWTAGconsttype}{DW\-\_TAG\-\_const\-\_type}&0x26 \\
791 \livelink{chap:DWTAGconstant}{DW\-\_TAG\-\_constant}&0x27 \\
792 \livelink{chap:DWTAGenumerator}{DW\-\_TAG\-\_enumerator}&0x28 \\
793 \livelink{chap:DWTAGfiletype}{DW\-\_TAG\-\_file\-\_type}&0x29 \\
794 \livelink{chap:DWTAGfriend}{DW\-\_TAG\-\_friend}&0x2a \\
795 \livelink{chap:DWTAGnamelist}{DW\-\_TAG\-\_namelist}&0x2b \\
796 \livelink{chap:DWTAGnamelistitem}{DW\-\_TAG\-\_namelist\-\_item}&0x2c \\
797 \livelink{chap:DWTAGpackedtype}{DW\-\_TAG\-\_packed\-\_type}&0x2d \\
798 \livelink{chap:DWTAGsubprogram}{DW\-\_TAG\-\_subprogram}&0x2e \\
799 \livelink{chap:DWTAGtemplatetypeparameter}{DW\-\_TAG\-\_template\-\_type\-\_parameter}&0x2f \\
800 \livelink{chap:DWTAGtemplatevalueparameter}{DW\-\_TAG\-\_template\-\_value\-\_parameter}&0x30 \\
801 \livelink{chap:DWTAGthrowntype}{DW\-\_TAG\-\_thrown\-\_type}&0x31 \\
802 \livelink{chap:DWTAGtryblock}{DW\-\_TAG\-\_try\-\_block}&0x32 \\
803 \livelink{chap:DWTAGvariantpart}{DW\-\_TAG\-\_variant\-\_part}&0x33 \\
804 \livelink{chap:DWTAGvariable}{DW\-\_TAG\-\_variable}&0x34 \\
805 \livelink{chap:DWTAGvolatiletype}{DW\-\_TAG\-\_volatile\-\_type}&0x35 \\
806 \livelink{chap:DWTAGdwarfprocedure}{DW\-\_TAG\-\_dwarf\-\_procedure}&0x36 \\
807 \livelink{chap:DWTAGrestricttype}{DW\-\_TAG\-\_restrict\-\_type}&0x37 \\
808 \livelink{chap:DWTAGinterfacetype}{DW\-\_TAG\-\_interface\-\_type}&0x38 \\
809 \livelink{chap:DWTAGnamespace}{DW\-\_TAG\-\_namespace}&0x39 \\
810 \livelink{chap:DWTAGimportedmodule}{DW\-\_TAG\-\_imported\-\_module}&0x3a \\
811 \livelink{chap:DWTAGunspecifiedtype}{DW\-\_TAG\-\_unspecified\-\_type}&0x3b \\
812 \livelink{chap:DWTAGpartialunit}{DW\-\_TAG\-\_partial\-\_unit}&0x3c \\
813 \livelink{chap:DWTAGimportedunit}{DW\-\_TAG\-\_imported\-\_unit}&0x3d \\
814 \livelink{chap:DWTAGcondition}{DW\-\_TAG\-\_condition}&0x3f \\
815 \livelink{chap:DWTAGsharedtype}{DW\-\_TAG\-\_shared\-\_type}&0x40 \\
816 \livelink{chap:DWTAGtypeunit}{DW\-\_TAG\-\_type\-\_unit} \ddag &0x41 \\
817 \livelink{chap:DWTAGrvaluereferencetype}{DW\-\_TAG\-\_rvalue\-\_reference\-\_type} \ddag &0x42 \\
818 \livelink{chap:DWTAGtemplatealias}{DW\-\_TAG\-\_template\-\_alias} \ddag &0x43 \\
819 \livelink{chap:DWTAGlouser}{DW\-\_TAG\-\_lo\-\_user}&0x4080 \\
820 \livelink{chap:DWTAGhiuser}{DW\-\_TAG\-\_hi\-\_user}&0xffff \\
822 \ddag TAG new in DWARF Version 4
828 \setlength{\extrarowheight}{0.1cm}
829 \caption{Child determination encodings}
830 \label{tab:childdeterminationencodings}
831 \begin{tabular}{l|l} \hline
832 Child determination name& Value\\ \hline
833 \livelink{chap:DWCHILDRENno}{DW\-\_CHILDREN\-\_no}&0x00 \\
834 \livelink{chap:DWCHILDRENyes}{DW\-\_CHILDREN\-\_yes}&0x01 \\ \hline
840 \setlength{\extrarowheight}{0.1cm}
841 \begin{longtable}{l|l|l}
842 \caption{Attribute encodings} \label{tab:attributeencodings} \\
843 \hline \\ \bfseries Attribute name&\bfseries Value &\bfseries Classes \\ \hline
845 \bfseries Attribute name&\bfseries Value &\bfseries Classes\\ \hline
847 \hline \emph{Continued on next page}
851 \livelink{chap:DWATsibling}{DW\-\_AT\-\_sibling}&0x01&reference \\
852 \livelink{chap:DWATlocation}{DW\-\_AT\-\_location}&0x02&\livelink{chap:exprloc}{exprloc}, \livelink{chap:loclistptr}{loclistptr} \\
853 \livelink{chap:DWATname}{DW\-\_AT\-\_name}&0x03&string \\
854 \livelink{chap:DWATordering}{DW\-\_AT\-\_ordering}&0x09&constant \\
855 \livelink{chap:DWATbytesize}{DW\-\_AT\-\_byte\-\_size}&0x0b&constant, \livelink{chap:exprloc}{exprloc}, reference \\
856 \livelink{chap:DWATbitoffset}{DW\-\_AT\-\_bit\-\_offset}&0x0c&constant, \livelink{chap:exprloc}{exprloc}, reference \\
857 \livelink{chap:DWATbitsize}{DW\-\_AT\-\_bit\-\_size}&0x0d&constant, \livelink{chap:exprloc}{exprloc}, reference \\
858 \livelink{chap:DWATstmtlist}{DW\-\_AT\-\_stmt\-\_list}&0x10&\livelink{chap:lineptr}{lineptr} \\
859 \livelink{chap:DWATlowpc}{DW\-\_AT\-\_low\-\_pc}&0x11&address \\
860 \livelink{chap:DWAThighpc}{DW\-\_AT\-\_high\-\_pc}&0x12&address, constant \\
861 \livelink{chap:DWATlanguage}{DW\-\_AT\-\_language}&0x13&constant \\
862 \livelink{chap:DWATdiscr}{DW\-\_AT\-\_discr}&0x15&reference \\
863 \livelink{chap:DWATdiscrvalue}{DW\-\_AT\-\_discr\-\_value}&0x16&constant \\
864 \livelink{chap:DWATvisibility}{DW\-\_AT\-\_visibility}&0x17&constant \\
865 \livelink{chap:DWATimport}{DW\-\_AT\-\_import}&0x18&reference \\
866 \livelink{chap:DWATstringlength}{DW\-\_AT\-\_string\-\_length}&0x19&\livelink{chap:exprloc}{exprloc}, \livelink{chap:loclistptr}{loclistptr} \\
867 \livelink{chap:DWATcommonreference}{DW\-\_AT\-\_common\-\_reference}&0x1a&reference \\
868 \livelink{chap:DWATcompdir}{DW\-\_AT\-\_comp\-\_dir}&0x1b&string \\
869 \livelink{chap:DWATconstvalue}{DW\-\_AT\-\_const\-\_value}&0x1c&block, constant, string \\
870 \livelink{chap:DWATcontainingtype}{DW\-\_AT\-\_containing\-\_type}&0x1d&reference \\
871 \livelink{chap:DWATdefaultvalue}{DW\-\_AT\-\_default\-\_value}&0x1e&reference \\
872 \livelink{chap:DWATinline}{DW\-\_AT\-\_inline}&0x20&constant \\
873 \livelink{chap:DWATisoptional}{DW\-\_AT\-\_is\-\_optional}&0x21&flag \\
874 \livelink{chap:DWATlowerbound}{DW\-\_AT\-\_lower\-\_bound}&0x22&constant, \livelink{chap:exprloc}{exprloc}, reference \\
875 \livelink{chap:DWATproducer}{DW\-\_AT\-\_producer}&0x25&string \\
876 \livelink{chap:DWATprototyped}{DW\-\_AT\-\_prototyped}&0x27&flag \\
877 \livelink{chap:DWATreturnaddr}{DW\-\_AT\-\_return\-\_addr}&0x2a&\livelink{chap:exprloc}{exprloc}, \livelink{chap:loclistptr}{loclistptr} \\
878 % FIXME: lower case , not Constant
879 \livelink{chap:DWATstartscope}{DW\-\_AT\-\_start\-\_scope}&0x2c&Constant, \livelink{chap:rangelistptr}{rangelistptr} \\
880 \livelink{chap:DWATbitstride}{DW\-\_AT\-\_bit\-\_stride}&0x2e&constant, \livelink{chap:exprloc}{exprloc}, reference \\
881 \livelink{chap:DWATupperbound}{DW\-\_AT\-\_upper\-\_bound}&0x2f&constant, \livelink{chap:exprloc}{exprloc}, reference \\
882 \livelink{chap:DWATabstractorigin}{DW\-\_AT\-\_abstract\-\_origin}&0x31&reference \\
883 \livelink{chap:DWATaccessibility}{DW\-\_AT\-\_accessibility}&0x32&constant \\
884 \livelink{chap:DWATaddressclass}{DW\-\_AT\-\_address\-\_class}&0x33&constant \\
885 \livelink{chap:DWATartificial}{DW\-\_AT\-\_artificial}&0x34&flag \\
886 \livelink{chap:DWATbasetypes}{DW\-\_AT\-\_base\-\_types}&0x35&reference \\
887 \livelink{chap:DWATcallingconvention}{DW\-\_AT\-\_calling\-\_convention}&0x36&constant \\
888 \livelink{chap:DWATcount}{DW\-\_AT\-\_count}&0x37&constant, \livelink{chap:exprloc}{exprloc}, reference \\
889 \livelink{chap:DWATdatamemberlocation}{DW\-\_AT\-\_data\-\_member\-\_location}&0x38&constant, \livelink{chap:exprloc}{exprloc}, \livelink{chap:loclistptr}{loclistptr} \\
890 \livelink{chap:DWATdeclcolumn}{DW\-\_AT\-\_decl\-\_column}&0x39&constant \\
891 \livelink{chap:DWATdeclfile}{DW\-\_AT\-\_decl\-\_file}&0x3a&constant \\
892 \livelink{chap:DWATdeclline}{DW\-\_AT\-\_decl\-\_line}&0x3b&constant \\
893 \livelink{chap:DWATdeclaration}{DW\-\_AT\-\_declaration}&0x3c&flag \\
894 \livelink{chap:DWATdiscrlist}{DW\-\_AT\-\_discr\-\_list}&0x3d&block \\
895 \livelink{chap:DWATencoding}{DW\-\_AT\-\_encoding}&0x3e&constant \\
896 \livelink{chap:DWATexternal}{DW\-\_AT\-\_external}&0x3f&flag \\
897 \livelink{chap:DWATframebase}{DW\-\_AT\-\_frame\-\_base}&0x40&\livelink{chap:exprloc}{exprloc}, \livelink{chap:loclistptr}{loclistptr} \\
898 \livelink{chap:DWATfriend}{DW\-\_AT\-\_friend}&0x41&reference \\
899 \livelink{chap:DWATidentifiercase}{DW\-\_AT\-\_identifier\-\_case}&0x42&constant \\
900 \livelink{chap:DWATmacroinfo}{DW\-\_AT\-\_macro\-\_info}&0x43&\livelink{chap:macptr}{macptr} \\
901 \livelink{chap:DWATnamelistitem}{DW\-\_AT\-\_namelist\-\_item}&0x44&reference \\
902 \livelink{chap:DWATpriority}{DW\-\_AT\-\_priority}&0x45&reference \\
903 \livelink{chap:DWATsegment}{DW\-\_AT\-\_segment}&0x46&\livelink{chap:exprloc}{exprloc}, \livelink{chap:loclistptr}{loclistptr} \\
904 \livelink{chap:DWATspecification}{DW\-\_AT\-\_specification}&0x47&reference \\
905 \livelink{chap:DWATstaticlink}{DW\-\_AT\-\_static\-\_link}&0x48&\livelink{chap:exprloc}{exprloc}, \livelink{chap:loclistptr}{loclistptr} \\
906 \livelink{chap:DWATtype}{DW\-\_AT\-\_type}&0x49&reference \\
907 \livelink{chap:DWATuselocation}{DW\-\_AT\-\_use\-\_location}&0x4a&\livelink{chap:exprloc}{exprloc}, \livelink{chap:loclistptr}{loclistptr} \\
908 \livelink{chap:DWATvariableparameter}{DW\-\_AT\-\_variable\-\_parameter}&0x4b&flag \\
909 \livelink{chap:DWATvirtuality}{DW\-\_AT\-\_virtuality}&0x4c&constant \\
910 \livelink{chap:DWATvtableelemlocation}{DW\-\_AT\-\_vtable\-\_elem\-\_location}&0x4d&\livelink{chap:exprloc}{exprloc}, \livelink{chap:loclistptr}{loclistptr} \\
913 \livelink{chap:DWATallocated}{DW\-\_AT\-\_allocated}&0x4e&constant, \livelink{chap:exprloc}{exprloc}, reference \\
914 \livelink{chap:DWATassociated}{DW\-\_AT\-\_associated}&0x4f&constant, \livelink{chap:exprloc}{exprloc}, reference \\
915 \livelink{chap:DWATdatalocation}{DW\-\_AT\-\_data\-\_location}&0x50&\livelink{chap:exprloc}{exprloc} \\
916 \livelink{chap:DWATbytestride}{DW\-\_AT\-\_byte\-\_stride}&0x51&constant, \livelink{chap:exprloc}{exprloc}, reference \\
917 \livelink{chap:DWATentrypc}{DW\-\_AT\-\_entry\-\_pc}&0x52&address \\
918 \livelink{chap:DWATuseUTF8}{DW\-\_AT\-\_use\-\_UTF8}&0x53&flag \\
919 \livelink{chap:DWATextension}{DW\-\_AT\-\_extension}&0x54&reference \\
920 \livelink{chap:DWATranges}{DW\-\_AT\-\_ranges}&0x55&\livelink{chap:rangelistptr}{rangelistptr} \\
921 \livelink{chap:DWATtrampoline}{DW\-\_AT\-\_trampoline}&0x56&address, flag, reference, string \\
922 \livelink{chap:DWATcallcolumn}{DW\-\_AT\-\_call\-\_column}&0x57&constant \\
923 \livelink{chap:DWATcallfile}{DW\-\_AT\-\_call\-\_file}&0x58&constant \\
924 \livelink{chap:DWATcallline}{DW\-\_AT\-\_call\-\_line}&0x59&constant \\
925 \livelink{chap:DWATdescription}{DW\-\_AT\-\_description}&0x5a&string \\
926 \livelink{chap:DWATbinaryscale}{DW\-\_AT\-\_binary\-\_scale}&0x5b&constant \\
927 \livelink{chap:DWATdecimalscale}{DW\-\_AT\-\_decimal\-\_scale}&0x5c&constant \\
928 \livelink{chap:DWATsmall}{DW\-\_AT\-\_small} &0x5d&reference \\
929 \livelink{chap:DWATdecimalsign}{DW\-\_AT\-\_decimal\-\_sign}&0x5e&constant \\
930 \livelink{chap:DWATdigitcount}{DW\-\_AT\-\_digit\-\_count}&0x5f&constant \\
931 \livelink{chap:DWATpicturestring}{DW\-\_AT\-\_picture\-\_string}&0x60&string \\
932 \livelink{chap:DWATmutable}{DW\-\_AT\-\_mutable}&0x61&flag \\
935 \livelink{chap:DWATthreadsscaled}{DW\-\_AT\-\_threads\-\_scaled}&0x62&flag \\
936 \livelink{chap:DWATexplicit}{DW\-\_AT\-\_explicit}&0x63&flag \\
937 \livelink{chap:DWATobjectpointer}{DW\-\_AT\-\_object\-\_pointer}&0x64&reference \\
938 \livelink{chap:DWATendianity}{DW\-\_AT\-\_endianity}&0x65&constant \\
939 \livelink{chap:DWATelemental}{DW\-\_AT\-\_elemental}&0x66&flag \\
940 \livelink{chap:DWATpure}{DW\-\_AT\-\_pure}&0x67&flag \\
941 \livelink{chap:DWATrecursive}{DW\-\_AT\-\_recursive}&0x68&flag \\
942 \livelink{chap:DWATsignature}{DW\-\_AT\-\_signature} \ddag &0x69&reference \\
943 \livelink{chap:DWATmainsubprogram}{DW\-\_AT\-\_main\-\_subprogram} \ddag &0x6a&flag \\
944 \livelink{chap:DWATdatabitoffset}{DW\-\_AT\-\_data\-\_bit\-\_offset} \ddag &0x6b&constant \\
945 \livelink{chap:DWATconstexpr}{DW\-\_AT\-\_const\-\_expr} \ddag &0x6c&flag \\
946 \livelink{chap:DWATenumclass}{DW\-\_AT\-\_enum\-\_class} \ddag &0x6d&flag \\
947 \livelink{chap:DWATlinkagename}{DW\-\_AT\-\_linkage\-\_name} \ddag &0x6e&string \\
948 \livetarg{chap:DWATlouser}{DW\-\_AT\-\_lo\-\_user}&0x2000 & --- \\
949 \livetarg{chap:DWAThiuser}{DW\-\_AT\-\_hi\-\_user}&0x3fff& --- \\
952 \ddag Attribute new in DWARF Version 4
956 \setlength{\extrarowheight}{0.1cm}
957 \begin{longtable}{l|l|l}
958 \caption{Attribute form encodings} \label{tab:attributeformencodings} \\
959 \hline \\ \bfseries Form name&\bfseries Value &\bfseries Classes \\ \hline
961 \bfseries Form name&\bfseries Value &\bfseries Classes\\ \hline
963 \hline \emph{Continued on next page}
967 \livelink{chap:DWFORMaddr}{DW\-\_FORM\-\_addr}&0x01&address \\
968 \livelink{chap:DWFORMblock2}{DW\-\_FORM\-\_block2}&0x03&block \\
969 \livelink{chap:DWFORMblock4}{DW\-\_FORM\-\_block4}&0x04&block \\
970 \livelink{chap:DWFORMdata2}{DW\-\_FORM\-\_data2}&0x05&constant \\
971 \livelink{chap:DWFORMdata4}{DW\-\_FORM\-\_data4}&0x06&constant \\
972 \livelink{chap:DWFORMdata8}{DW\-\_FORM\-\_data8}&0x07&constant \\
973 \livelink{chap:DWFORMstring}{DW\-\_FORM\-\_string}&0x08&string \\
974 \livelink{chap:DWFORMblock}{DW\-\_FORM\-\_block}&0x09&block \\
975 \livelink{chap:DWFORMblock1}{DW\-\_FORM\-\_block1}&0x0a&block \\
976 \livelink{chap:DWFORMdata1}{DW\-\_FORM\-\_data1}&0x0b&constant \\
977 \livelink{chap:DWFORMflag}{DW\-\_FORM\-\_flag}&0x0c&flag \\
978 \livelink{chap:DWFORMsdata}{DW\-\_FORM\-\_sdata}&0x0d&constant \\
979 \livelink{chap:DWFORMstrp}{DW\-\_FORM\-\_strp}&0x0e&string \\
980 \livelink{chap:DWFORMudata}{DW\-\_FORM\-\_udata}&0x0f&constant \\
981 \livelink{chap:DWFORMrefaddr}{DW\-\_FORM\-\_ref\-\_addr}&0x10&reference \\
982 \livelink{chap:DWFORMref1}{DW\-\_FORM\-\_ref1}&0x11&reference \\
983 \livelink{chap:DWFORMref2}{DW\-\_FORM\-\_ref2}&0x12&reference \\
984 \livelink{chap:DWFORMref4}{DW\-\_FORM\-\_ref4}&0x13&reference \\
985 \livelink{chap:DWFORMref8}{DW\-\_FORM\-\_ref8}&0x14&reference \\
986 \livelink{chap:DWFORMrefudata}{DW\-\_FORM\-\_ref\-\_udata}&0x15&reference \\
987 \livelink{chap:DWFORMindirect}{DW\-\_FORM\-\_indirect}&0x16&(see Section \refersec{datarep:abbreviationstables}) \\
988 \livelink{chap:DWFORMsecoffset}{DW\-\_FORM\-\_sec\-\_offset} \ddag &0x17&\livelink{chap:lineptr}{lineptr}, \livelink{chap:loclistptr}{loclistptr}, \livelink{chap:macptr}{macptr}, \livelink{chap:rangelistptr}{rangelistptr} \\
989 \livelink{chap:DWFORMexprloc}{DW\-\_FORM\-\_exprloc} \ddag &0x18&\livelink{chap:exprloc}{exprloc} \\
990 \livelink{chap:DWFORMflagpresent}{DW\-\_FORM\-\_flag\-\_present} \ddag &0x19&flag \\
991 \livelink{chap:DWFORMrefsig8}{DW\-\_FORM\-\_ref\-\_sig8} \ddag &0x20&reference \\
994 \ddag FORM new in DWARF Version 4
997 \section{Variable Length Data}
998 \label{datarep:variablelengthdata}
999 Integers may be encoded using ``Little Endian Base 128''
1000 (LEB128) numbers. LEB128 is a scheme for encoding integers
1001 densely that exploits the assumption that most integers are
1004 This encoding is equally suitable whether the target machine
1005 architecture represents data in big\dash\ endian or little\dash endian
1006 order. It is ``little\dash endian'' only in the sense that it
1007 avoids using space to represent the ``big'' end of an
1008 unsigned integer, when the big end is all zeroes or sign
1011 Unsigned LEB128 (ULEB128) numbers are encoded as follows:
1012 start at the low order end of an unsigned integer and chop
1013 it into 7\dash bit chunks. Place each chunk into the low order 7
1014 bits of a byte. Typically, several of the high order bytes
1015 will be zero; discard them. Emit the remaining bytes in a
1016 stream, starting with the low order byte; set the high order
1017 bit on each byte except the last emitted byte. The high bit
1018 of zero on the last byte indicates to the decoder that it
1019 has encountered the last byte.
1021 The integer zero is a special case, consisting of a single
1024 Table \refersec{tab:examplesofunsignedleb128encodings}
1025 gives some examples of unsigned LEB128 numbers. The
1026 0x80 in each case is the high order bit of the byte, indicating
1027 that an additional byte follows.
1030 The encoding for signed, two’s complement LEB128 (SLEB128)
1031 numbers is similar, except that the criterion for discarding
1032 high order bytes is not whether they are zero, but whether
1033 they consist entirely of sign extension bits. Consider the
1034 32\dash bit integer -2. The three high level bytes of the number
1035 are sign extension, thus LEB128 would represent it as a single
1036 byte containing the low order 7 bits, with the high order
1037 bit cleared to indicate the end of the byte stream. Note
1038 that there is nothing within the LEB128 representation that
1039 indicates whether an encoded number is signed or unsigned. The
1040 decoder must know what type of number to expect.
1041 Table \refersec{tab:examplesofunsignedleb128encodings}
1042 gives some examples of unsigned LEB128 numbers and
1043 Table \refersec{tab:examplesofsignedleb128encodings}
1044 gives some examples of signed LEB128 numbers.
1046 Appendix \refersec{app:variablelengthdataencodingdecodinginformative}
1047 gives algorithms for encoding and decoding these forms.
1051 \setlength{\extrarowheight}{0.1cm}
1052 \begin{longtable}{l|l|l}
1053 \caption{Examples of unsigned LEB32 encodings} \label{tab:examplesofunsignedleb128encodings} \\
1054 \hline \\ \bfseries Number&\bfseries First byte &\bfseries Second byte \\ \hline
1056 \bfseries Number&\bfseries First Byte &\bfseries Second byte\\ \hline
1058 \hline \emph{Continued on next page}
1064 128& 0 + 0x80 & 1 \\
1065 129& 1 + 0x80 & 1 \\
1066 130& 2 + 0x80 & 1 \\
1067 12857& 57 + 0x80 & 100 \\
1075 \setlength{\extrarowheight}{0.1cm}
1076 \begin{longtable}{l|l|l}
1077 \caption{Examples of signed LEB32 encodings} \label{tab:examplesofsignedleb128encodings} \\
1078 \hline \\ \bfseries Number&\bfseries First byte &\bfseries Second byte \\ \hline
1080 \bfseries Number&\bfseries First Byte &\bfseries Second byte\\ \hline
1082 \hline \emph{Continued on next page}
1088 127& 127 + 0x80 & 0 \\
1089 -127& 1 + 0x80 & 0x7f \\
1090 128& 0 + 0x80 & 1 \\
1091 -128& 0 + 0x80 & 0x7f \\
1092 129& 1 + 0x80 & 1 \\
1093 -129& -x7f + 0x80 & 0xtc \\
1100 \section{DWARF Expressions and Location Descriptions}
1101 \label{datarep:dwarfexpressionsandlocationdescriptions}
1102 \subsection{DWARF Expressions}
1103 \label{datarep:dwarfexpressions}
1105 A DWARF expression is stored in a block of contiguous
1106 bytes. The bytes form a sequence of operations. Each operation
1107 is a 1\dash byte code that identifies that operation, followed by
1108 zero or more bytes of additional data. The encodings for the
1109 operations are described in
1110 Table \refersec{tab:dwarfoperationencodings}.
1113 \setlength{\extrarowheight}{0.1cm}
1114 \begin{longtable}{l|l|l|l}
1115 \caption{DWARF operation encodings} \label{tab:dwarfoperationencodings} \\
1116 \hline \\ & &\bfseries No. of &\\
1117 \bfseries Operation&\bfseries Code &\bfseries Operands &\bfseries Notes\\ \hline
1119 & &\bfseries No. of &\\
1120 \bfseries Operation&\bfseries Code &\bfseries Operands &\bfseries Notes\\ \hline
1122 \hline \emph{Continued on next page}
1127 \livelink{chap:DWOPaddr}{DW\-\_OP\-\_addr}&0x03&1 & constant address \\
1128 & & &(size target specific) \\
1130 \livelink{chap:DWOPderef}{DW\-\_OP\-\_deref}&0x06&0 & \\
1133 \livelink{chap:DWOPconst1u}{DW\-\_OP\-\_const1u}&0x08&1&1\dash byte constant \\
1134 \livelink{chap:DWOPconst1s}{DW\-\_OP\-\_const1s}&0x09&1&1\dash byte constant \\
1135 \livelink{chap:DWOPconst2u}{DW\-\_OP\-\_const2u}&0x0a&1&2\dash byte constant \\
1136 \livelink{chap:DWOPconst2s}{DW\-\_OP\-\_const2s}&0x0b&1&2\dash byte constant \\
1137 \livelink{chap:DWOPconst4u}{DW\-\_OP\-\_const4u}&0x0c&1&4\dash byte constant \\
1138 \livelink{chap:DWOPconst4s}{DW\-\_OP\-\_const4s}&0x0d&1&4\dash byte constant \\
1139 \livelink{chap:DWOPconst8u}{DW\-\_OP\-\_const8u}&0x0e&1&8\dash byte constant \\
1140 \livelink{chap:DWOPconst8s}{DW\-\_OP\-\_const8s}&0x0f&1&8\dash byte constant \\
1141 \livelink{chap:DWOPconstu}{DW\-\_OP\-\_constu}&0x10&1&ULEB128 constant \\
1142 \livelink{chap:DWOPconsts}{DW\-\_OP\-\_consts}&0x11&1&SLEB128 constant \\
1143 \livelink{chap:DWOPdup}{DW\-\_OP\-\_dup}&0x12&0 & \\
1144 \livelink{chap:DWOPdrop}{DW\-\_OP\-\_drop}&0x13&0 & \\
1145 \livelink{chap:DWOPover}{DW\-\_OP\-\_over}&0x14&0 & \\
1146 \livelink{chap:DWOPpick}{DW\-\_OP\-\_pick}&0x15&1&1\dash byte stack index \\
1147 \livelink{chap:DWOPswap}{DW\-\_OP\-\_swap}&0x16&0 & \\
1148 \livelink{chap:DWOProt}{DW\-\_OP\-\_rot}&0x17&0 & \\
1149 \livelink{chap:DWOPxderef}{DW\-\_OP\-\_xderef}&0x18&0 & \\
1150 \livelink{chap:DWOPabs}{DW\-\_OP\-\_abs}&0x19&0 & \\
1151 \livelink{chap:DWOPand}{DW\-\_OP\-\_and}&0x1a&0 & \\
1152 \livelink{chap:DWOPdiv}{DW\-\_OP\-\_div}&0x1b&0 & \\
1156 \livelink{chap:DWOPminus}{DW\-\_OP\-\_minus}&0x1c&0 & \\
1157 \livelink{chap:DWOPmod}{DW\-\_OP\-\_mod}&0x1d&0 & \\
1158 \livelink{chap:DWOPmul}{DW\-\_OP\-\_mul}&0x1e&0 & \\
1159 \livelink{chap:DWOPneg}{DW\-\_OP\-\_neg}&0x1f&0 & \\
1160 \livelink{chap:DWOPnot}{DW\-\_OP\-\_not}&0x20&0 & \\
1161 \livelink{chap:DWOPor}{DW\-\_OP\-\_or}&0x21&0 & \\
1162 \livelink{chap:DWOPplus}{DW\-\_OP\-\_plus}&0x22&0 & \\
1163 \livelink{chap:DWOPplusuconst}{DW\-\_OP\-\_plus\-\_uconst}&0x23&1&ULEB128 addend \\
1164 \livelink{chap:DWOPshl}{DW\-\_OP\-\_shl}&0x24&0 & \\
1165 \livelink{chap:DWOPshr}{DW\-\_OP\-\_shr}&0x25&0 & \\
1166 \livelink{chap:DWOPshra}{DW\-\_OP\-\_shra}&0x26&0 & \\
1167 \livelink{chap:DWOPxor}{DW\-\_OP\-\_xor}&0x27&0 & \\
1168 \livelink{chap:DWOPskip}{DW\-\_OP\-\_skip}&0x2f&1&signed 2\dash byte constant \\
1169 \livelink{chap:DWOPbra}{DW\-\_OP\-\_bra}&0x28&1 & signed 2\dash byte constant \\
1170 \livelink{chap:DWOPeq}{DW\-\_OP\-\_eq}&0x29&0 & \\
1171 \livelink{chap:DWOPge}{DW\-\_OP\-\_ge}&0x2a&0 & \\
1172 \livelink{chap:DWOPgt}{DW\-\_OP\-\_gt}&0x2b&0 & \\
1173 \livelink{chap:DWOPle}{DW\-\_OP\-\_le}&0x2c&0 & \\
1174 \livelink{chap:DWOPlt}{DW\-\_OP\-\_lt}&0x2d&0 & \\
1175 \livelink{chap:DWOPne}{DW\-\_OP\-\_ne}&0x2e&0 & \\ \hline
1179 \livelink{chap:DWOPlit0}{DW\-\_OP\-\_lit0}&0x30 & 0 & \\
1181 \livelink{chap:DWOPlit1}{DW\-\_OP\-\_lit1}&0x31 & 0& literals 0 .. 31 = \\
1182 \ldots & & & (\livelink{chap:DWOPlit0}{DW\-\_OP\-\_lit0} + literal) \\
1183 \livelink{chap:DWOPlit31}{DW\-\_OP\-\_lit31}&0x4f & 0 & \\ \hline
1185 \livelink{chap:DWOPreg0}{DW\-\_OP\-\_reg0} & 0x50 & 0 & \\
1186 \livelink{chap:DWOPreg1}{DW\-\_OP\-\_reg1} & 0x51 & 0® 0 .. 31 = \\
1187 \ldots & & & (\livelink{chap:DWOPreg0}{DW\-\_OP\-\_reg0} + regnum) \\
1188 \livelink{chap:DWOPreg31}{DW\-\_OP\-\_reg31} & 0x6f & 0 & \\ \hline
1190 \livelink{chap:DWOPbreg0}{DW\-\_OP\-\_breg0} & 0x70 &1 & SLEB128 offset \\
1191 \livelink{chap:DWOPbreg1}{DW\-\_OP\-\_breg1} & 0x71 & 1 &base register 0 .. 31 = \\
1192 ... & & &(\livelink{chap:DWOPbreg0}{DW\-\_OP\-\_breg0} + regnum) \\
1193 \livelink{chap:DWOPbreg31}{DW\-\_OP\-\_breg31} & 0x8f & 1 & \\ \hline
1195 \livelink{chap:DWOPregx}{DW\-\_OP\-\_regx} & 0x90 &1&ULEB128 register \\
1196 \livelink{chap:DWOPfbreg}{DW\-\_OP\-\_fbreg} & 0x91&1&SLEB128 offset \\
1197 \livelink{chap:DWOPbregx}{DW\-\_OP\-\_bregx} & 0x92&2 &ULEB128 register followed \\
1198 & & & by SLEB128 offset \\
1199 \livelink{chap:DWOPpiece}{DW\-\_OP\-\_piece} & 0x93 &1& ULEB128 size of piece addressed \\
1200 \livelink{chap:DWOPderefsize}{DW\-\_OP\-\_deref\-\_size} & 0x94 &1& 1-byte size of data retrieved \\
1201 \livelink{chap:DWOPxderefsize}{DW\-\_OP\-\_xderef\-\_size} & 0x95&1&1-byte size of data retrieved \\
1202 \livelink{chap:DWOPnop}{DW\-\_OP\-\_nop} & 0x96 &0& \\
1205 \livelink{chap:DWOPpushobjectaddress}{DW\-\_OP\-\_push\-\_object\-\_address}&0x97&0 & \\
1206 \livelink{chap:DWOPcall2}{DW\-\_OP\-\_call2}&0x98&1& 2\dash byte offset of DIE \\
1207 \livelink{chap:DWOPcall4}{DW\-\_OP\-\_call4}&0x99&1& 4\dash byte offset of DIE \\
1208 \livelink{chap:DWOPcallref}{DW\-\_OP\-\_call\-\_ref}&0x9a&1& 4\dash\ or 8\dash byte\\
1209 &&& offset of DIE \\
1210 \livelink{chap:DWOPformtlsaddress}{DW\-\_OP\-\_form\-\_tls\-\_address}&0x9b &0& \\
1211 \livelink{chap:DWOPcallframecfa}{DW\-\_OP\-\_call\-\_frame\-\_cfa} &0x9c &0& \\
1212 \livelink{chap:DWOPbitpiece}{DW\-\_OP\-\_bit\-\_piece}&0x9d &2&ULEB128 size followed by \\
1214 \livelink{chap:DWOPimplicitvalue}{DW\-\_OP\-\_implicit\-\_value}&0x9e &2&ULEB128 size followed by \\
1215 &&&block of that size\\
1216 \livelink{chap:DWOPstackvalue}{DW\-\_OP\-\_stack\-\_value} &0x9f &0& \\
1217 \livetarg{chap:DWOPlouser}{DW\-\_OP\-\_lo\-\_user} &0xe0 && \\
1218 \livetarg{chap:DWOPhiuser}{DW\-\_OP\-\_hi\-\_user} &0xff && \\
1224 \subsection{Location Descriptions}
1225 \label{datarep:locationdescriptions}
1227 A location description is used to compute the
1228 location of a variable or other entity.
1230 \subsection{Location Lists}
1231 \label{datarep:locationlists}
1233 Each entry in a location list is either a location list entry,
1234 a base address selection entry, or an end of list entry.
1236 A location list entry consists of two address offsets followed
1237 by a 2\dash byte length, followed by a block of contiguous bytes
1238 that contains a DWARF location description. The length
1239 specifies the number of bytes in that block. The two offsets
1240 are the same size as an address on the target machine.
1242 A base address selection entry and an end of list entry each
1243 consist of two (constant or relocated) address offsets. The two
1244 offsets are the same size as an address on the target machine.
1246 For a location list to be specified, the base address of
1247 the corresponding compilation unit must be defined
1248 (see Section \refersec{chap:normalandpartialcompilationunitentries}).
1250 \section{Base Type Attribute Encodings}
1251 \label{datarep:basetypeattributeencodings}
1253 The encodings of the constants used in the \livelink{chap:DWATencoding}{DW\-\_AT\-\_encoding}
1254 attribute are given in
1255 Table \refersec{tab:basetypeencodingvalues}
1258 \setlength{\extrarowheight}{0.1cm}
1259 \begin{longtable}{l|c}
1260 \caption{Base type encoding values} \label{tab:basetypeencodingvalues} \\
1261 \hline \\ \bfseries Base type encoding code name&\bfseries Value \\ \hline
1263 \bfseries Base type encoding code name&\bfseries Value\\ \hline
1265 \hline \emph{Continued on next page}
1270 \livelink{chap:DWATEaddress}{DW\-\_ATE\-\_address}&0x01 \\
1271 \livelink{chap:DWATEboolean}{DW\-\_ATE\-\_boolean}&0x02 \\
1272 \livelink{chap:DWATEcomplexfloat}{DW\-\_ATE\-\_complex\-\_float}&0x03 \\
1273 \livelink{chap:DWATEfloat}{DW\-\_ATE\-\_float}&0x04 \\
1274 \livelink{chap:DWATEsigned}{DW\-\_ATE\-\_signed}&0x05 \\
1275 \livelink{chap:DWATEsignedchar}{DW\-\_ATE\-\_signed\-\_char}&0x06 \\
1276 \livelink{chap:DWATEunsigned}{DW\-\_ATE\-\_unsigned}&0x07 \\
1277 \livelink{chap:DWATEunsignedchar}{DW\-\_ATE\-\_unsigned\-\_char}&0x08 \\
1278 \livelink{chap:DWATEimaginaryfloat}{DW\-\_ATE\-\_imaginary\-\_float}&0x09 \\
1279 \livelink{chap:DWATEpackeddecimal}{DW\-\_ATE\-\_packed\-\_decimal}&0x0a \\
1280 \livelink{chap:DWATEnumericstring}{DW\-\_ATE\-\_numeric\-\_string}&0x0b \\
1281 \livelink{chap:DWATEedited}{DW\-\_ATE\-\_edited}&0x0c \\
1282 \livelink{chap:DWATEsignedfixed}{DW\-\_ATE\-\_signed\-\_fixed}&0x0d \\
1283 \livelink{chap:DWATEunsignedfixed}{DW\-\_ATE\-\_unsigned\-\_fixed}&0x0e \\
1284 \livelink{chap:DWATEdecimalfloat}{DW\-\_ATE\-\_decimal\-\_float} & 0x0f \\
1285 \livelink{chap:DWATEUTF}{DW\-\_ATE\-\_UTF} \ddag & 0x10 \\
1286 \livetarg{chap:DWATElouser}{DW\-\_ATE\-\_lo\-\_user} & 0x80 \\
1287 \livetarg{chap:DWATEhiuser}{DW\-\_ATE\-\_hi\-\_user} & 0xff \\
1290 \ddag Base type encoding new in DWARF Version 4
1294 The encodings of the constants used in the
1295 \livelink{chap:DWATdecimalsign}{DW\-\_AT\-\_decimal\-\_sign} attribute
1297 Table \refersec{tab:decimalsignencodings}.
1301 \setlength{\extrarowheight}{0.1cm}
1302 \begin{longtable}{l|c}
1303 \caption{Decimal sign encodings} \label{tab:decimalsignencodings} \\
1304 \hline \\ \bfseries Decimal sign code name&\bfseries Value \\ \hline
1306 \bfseries Decimal sign code name&\bfseries Value\\ \hline
1308 \hline \emph{Continued on next page}
1313 DW\-\_DS\-\_unsigned & 0x01 \\
1314 DW\-\_DS\-\_leading\-\_overpunch & 0x02 \\
1315 DW\-\_DS\-\_trailing\-\_overpunch & 0x03 \\
1316 DW\-\_DS\-\_leading\-\_separate & 0x04 \\
1317 DW\-\_DS\-\_trailing\-\_separate & 0x05 \\
1322 The encodings of the constants used in the
1323 \livelink{chap:DWATendianity}{DW\-\_AT\-\_endianity} attribute are given in
1324 Table \refersec{tab:endianityencodings}.
1327 \setlength{\extrarowheight}{0.1cm}
1328 \begin{longtable}{l|c}
1329 \caption{Endianity encodings} \label{tab:endianityencodings}\\
1330 \hline \\ \bfseries Endian code name&\bfseries Value \\ \hline
1332 \bfseries Endian code name&\bfseries Value\\ \hline
1334 \hline \emph{Continued on next page}
1339 DW\-\_END\-\_default & 0x00 \\
1340 DW\-\_END\-\_big & 0x01 \\
1341 DW\-\_END\-\_little & 0x02 \\
1342 DW\-\_END\-\_lo\-\_user & 0x40 \\
1343 DW\-\_END\-\_hi\-\_user & 0xff \\
1348 \section{Accessibility Codes}
1349 \label{datarep:accessibilitycodes}
1350 The encodings of the constants used in the \livelink{chap:DWATaccessibility}{DW\-\_AT\-\_accessibility}
1351 attribute are given in
1352 Table \refersec{tab:accessibilityencodings}.
1355 \setlength{\extrarowheight}{0.1cm}
1356 \begin{longtable}{l|c}
1357 \caption{Accessibility encodings} \label{tab:accessibilityencodings}\\
1358 \hline \\ \bfseries Accessibility code name&\bfseries Value \\ \hline
1360 \bfseries Accessibility code name&\bfseries Value\\ \hline
1362 \hline \emph{Continued on next page}
1367 \livelink{chap:DWACCESSpublic}{DW\-\_ACCESS\-\_public}&0x01 \\
1368 \livelink{chap:DWACCESSprotected}{DW\-\_ACCESS\-\_protected}&0x02 \\
1369 \livelink{chap:DWACCESSprivate}{DW\-\_ACCESS\-\_private}&0x03 \\
1375 \section{Visibility Codes}
1376 \label{datarep:visibilitycodes}
1377 The encodings of the constants used in the
1378 \livelink{chap:DWATvisibility}{DW\-\_AT\-\_visibility} attribute are given in
1379 Table \refersec{tab:visibilityencodings}.
1382 \setlength{\extrarowheight}{0.1cm}
1383 \begin{longtable}{l|c}
1384 \caption{Visibility encodings} \label{tab:visibilityencodings}\\
1385 \hline \\ \bfseries Visiibility code name&\bfseries Value \\ \hline
1387 \bfseries Visibility code name&\bfseries Value\\ \hline
1389 \hline \emph{Continued on next page}
1394 DW\-\_VIS\-\_local&0x01 \\
1395 DW\-\_VIS\-\_exported&0x02 \\
1396 DW\-\_VIS\-\_qualified&0x03 \\
1401 \section{Virtuality Codes}
1402 \label{datarep:vitualitycodes}
1404 The encodings of the constants used in the
1405 \livelink{chap:DWATvirtuality}{DW\-\_AT\-\_virtuality} attribute are given in
1406 Table \refersec{tab:virtualityencodings}.
1409 \setlength{\extrarowheight}{0.1cm}
1410 \begin{longtable}{l|c}
1411 \caption{Virtuality encodings} \label{tab:virtualityencodings}\\
1412 \hline \\ \bfseries Virtuality code name&\bfseries Value \\ \hline
1414 \bfseries Virtuality code name&\bfseries Value\\ \hline
1416 \hline \emph{Continued on next page}
1421 DW\-\_VIRTUALITY\-\_none&0x00 \\
1422 DW\-\_VIRTUALITY\-\_virtual&0x01 \\
1423 DW\-\_VIRTUALITY\-\_pure\-\_virtual&0x02 \\
1431 DW\-\_VIRTUALITY\-\_none is equivalent to the absence of the
1432 \livelink{chap:DWATvirtuality}{DW\-\_AT\-\_virtuality}
1435 \section{Source Languages}
1436 \label{datarep:sourcelanguages}
1438 The encodings of the constants used in the \livelink{chap:DWATlanguage}{DW\-\_AT\-\_language}
1439 attribute are given in
1440 Table \refersec{tab:languageencodings}.
1442 % If we don't force a following space it looks odd
1444 and their associated values are reserved, but the
1445 languages they represent are not well supported.
1446 Table \refersec{tab:languageencodings}
1447 also shows the default lower bound, if any, assumed for
1448 an omitted \livelink{chap:DWATlowerbound}{DW\-\_AT\-\_lower\-\_bound} attribute in the context of a
1449 \livelink{chap:DWTAGsubrangetype}{DW\-\_TAG\-\_subrange\-\_type} debugging information entry for each
1453 \setlength{\extrarowheight}{0.1cm}
1454 \begin{longtable}{l|c|c}
1455 \caption{Language encodings} \label{tab:languageencodings}\\
1456 \hline \\ \bfseries Language name&\bfseries Value &\bfseries Default Lower Bound \\ \hline
1458 \bfseries Language name&\bfseries Value &\bfseries Default Lower Bound\\ \hline
1460 \hline \emph{Continued on next page}
1465 DW\-\_LANG\-\_C89&0x0001&0 \\
1466 DW\-\_LANG\-\_C&0x0002&0 \\
1467 DW\-\_LANG\-\_Ada83 \dag &0x0003&1 \\
1468 DW\-\_LANG\-\_C\-\_plus\-\_plus &0x0004&0 \\
1469 DW\-\_LANG\-\_Cobol74 \dag &0x0005&1 \\
1470 DW\-\_LANG\-\_Cobol85 \dag &0x0006&1 \\
1471 DW\-\_LANG\-\_Fortran77&0x0007&1 \\
1472 DW\-\_LANG\-\_Fortran90&0x0008&1 \\
1473 DW\-\_LANG\-\_Pascal83&0x0009&1 \\
1474 DW\-\_LANG\-\_Modula2&0x000a&1 \\
1475 DW\-\_LANG\-\_Java&0x000b&0 \\
1476 DW\-\_LANG\-\_C99&0x000c&0 \\
1477 DW\-\_LANG\-\_Ada95 \dag &0x000d&1 \\
1478 DW\-\_LANG\-\_Fortran95 &0x000e&1 \\
1479 DW\-\_LANG\-\_PLI \dag &0x000f&1 \\
1480 DW\-\_LANG\-\_ObjC&0x0010&0 \\
1481 DW\-\_LANG\-\_ObjC\-\_plus\-\_plus&0x0011&0 \\
1482 DW\-\_LANG\-\_UPC&0x0012&0 \\
1483 DW\-\_LANG\-\_D&0x0013&0 \\
1484 DW\-\_LANG\-\_Python \dag &0x0014&0 \\
1485 DW\-\_LANG\-\_lo\-\_user&0x8000 & \\
1486 DW\-\_LANG\-\_hi\-\_user&0xffff & \\
1492 \section{Address Class Encodings}
1493 \label{datarep:addressclassencodings}
1495 The value of the common address class encoding
1496 \livelink{chap:DWADDRnone}{DW\-\_ADDR\-\_none} is 0.
1499 \section{Identifier Case}
1500 \label{datarep:identifiercase}
1502 The encodings of the constants used in the
1503 \livelink{chap:DWATidentifiercase}{DW\-\_AT\-\_identifier\-\_case} attribute are given in
1504 Table \refersec{tab:identifiercaseencodings}.
1507 \setlength{\extrarowheight}{0.1cm}
1508 \begin{longtable}{l|c}
1509 \caption{Identifier case encodings} \label{tab:identifiercaseencodings}\\
1510 \hline \\ \bfseries Identifier case name&\bfseries Value \\ \hline
1512 \bfseries Identifier case name&\bfseries Value\\ \hline
1514 \hline \emph{Continued on next page}
1518 DW\-\_ID\-\_case\-\_sensitive&0x00 \\
1519 DW\-\_ID\-\_up\-\_case&0x01 \\
1520 DW\-\_ID\-\_down\-\_case&0x02 \\
1521 DW\-\_ID\-\_case\-\_insensitive&0x03 \\
1525 \section{Calling Convention Encodings}
1526 \label{datarep:callingconventionencodings}
1527 The encodings of the constants used in the
1528 \livelink{chap:DWATcallingconvention}{DW\-\_AT\-\_calling\-\_convention} attribute are given in
1529 Table \refersec{tab:callingconventionencodings}.
1532 \setlength{\extrarowheight}{0.1cm}
1533 \begin{longtable}{l|c}
1534 \caption{Calling convention encodings} \label{tab:callingconventionencodings}\\
1535 \hline \\ \bfseries Calling Convention name&\bfseries Value \\ \hline
1537 \bfseries Calling Convention name&\bfseries Value\\ \hline
1539 \hline \emph{Continued on next page}
1544 \livelink{chap:DWCCnormal}{DW\-\_CC\-\_normal}&0x01 \\
1545 \livelink{chap:DWCCprogram}{DW\-\_CC\-\_program}&0x02 \\
1546 \livelink{chap:DWCCnocall}{DW\-\_CC\-\_nocall}&0x03 \\
1547 \livetarg{chap:DWCClouser}{DW\-\_CC\-\_lo\-\_user}&0x40 \\
1548 \livetarg{chap:DWCChiuser}{DW\-\_CC\-\_hi\-\_user}&0xff \\
1553 \section{Inline Codes}
1554 \label{datarep:inlinecodes}
1556 The encodings of the constants used in the
1557 \livelink{chap:DWATinline}{DW\-\_AT\-\_inline} attribute are given in
1558 Table \refersec{tab:inlineencodings}.
1561 \setlength{\extrarowheight}{0.1cm}
1562 \begin{longtable}{l|c}
1563 \caption{Inline encodings} \label{tab:inlineencodings}\\
1564 \hline \\ \bfseries Iline Code name&\bfseries Value \\ \hline
1566 \bfseries Iline Code name&\bfseries Value\\ \hline
1568 \hline \emph{Continued on next page}
1573 DW\-\_INL\-\_not\-\_inlined&0x00 \\
1574 DW\-\_INL\-\_inlined&0x01 \\
1575 DW\-\_INL\-\_declared\-\_not\-\_inlined&0x02 \\
1576 DW\-\_INL\-\_declared\-\_inlined&0x03 \\
1581 % this clearpage is ugly, but the following table came
1582 % out oddly without it.
1584 \section{Array Ordering}
1585 \label{datarep:arrayordering}
1587 The encodings of the constants used in the
1588 \livelink{chap:DWATordering}{DW\-\_AT\-\_ordering} attribute are given in
1589 Table \refersec{tab:orderingencodings}.
1592 \setlength{\extrarowheight}{0.1cm}
1593 \begin{longtable}{l|c}
1594 \caption{Ordering encodings} \label{tab:orderingencodings}\\
1595 \hline \\ \bfseries Ordering name&\bfseries Value \\ \hline
1597 \bfseries Ordering name&\bfseries Value\\ \hline
1599 \hline \emph{Continued on next page}
1604 DW\-\_ORD\-\_row\-\_major&0x00 \\
1605 DW\-\_ORD\-\_col\-\_major&0x01 \\
1611 \section{Discriminant Lists}
1612 \label{datarep:discriminantlists}
1614 The descriptors used in the
1615 \livelink{chap:DWATdiscrlist}{DW\-\_AT\-\_discr\-\_list} attribute are
1616 encoded as 1\dash byte constants. The
1617 defined values are given in
1618 Table \refersec{tab:discriminantdescriptorencodings}.
1620 % Odd that the 'Name' field captalized here, it is not caps elsewhere.
1622 \setlength{\extrarowheight}{0.1cm}
1623 \begin{longtable}{l|c}
1624 \caption{Discriminant descriptor encodings} \label{tab:discriminantdescriptorencodings}\\
1625 \hline \\ \bfseries Descriptor Name&\bfseries Value \\ \hline
1627 \bfseries Descriptor Name&\bfseries Value\\ \hline
1629 \hline \emph{Continued on next page}
1634 DW\-\_DSC\-\_label&0x00 \\
1635 DW\-\_DSC\-\_range&0x01 \\
1640 \section{Name Lookup Tables}
1641 \label{datarep:namelookuptables}
1643 Each set of entries in the table of global names contained
1644 in the .debug\_pubnames and .debug\_pubtypes sections begins
1645 with a header consisting of:
1648 \begin{enumerate}[1.]
1649 \item unit\_length (initial length) \\
1650 A 4\dash byte or 12\dash byte unsigned integer representing the length
1651 of the .debug\_info contribution for that compilation unit,
1652 not including the length field itself. In the 32\dash bit DWARF
1653 format, this is a 4\dash byte unsigned integer (which must be less
1654 than 0xfffffff0); in the 64\dash bit DWARF format, this consists
1655 of the 4\dash byte value 0xffffffff followed by an 8\dash byte unsigned
1656 integer that gives the actual length
1657 (see Section \refersec{datarep:32bitand64bitdwarfformats}).
1659 \item version (uhalf)
1660 A 2\dash byte unsigned integer representing the version of the
1661 DWARF information for the compilation unit
1662 (see Appendix \refersec{app:dwarfsectionversionnumbersinformative}).
1663 The value in this field is 4.
1665 % Some say unsigned offset this just says offset: FIXME
1666 \item debug\_info\_offset (section offset) \\
1667 A 4\dash byte or 8\dash byte offset into the .debug\_info
1668 section of the compilation unit header.
1670 the 32\dash bit DWARF format, this is a 4\dash byte unsigned offset;
1671 in the 64\dash bit DWARF format, this is an 8\dash byte unsigned offsets
1672 (see Section \refersec{datarep:32bitand64bitdwarfformats}).
1674 \item debug\_info\_length (section length) \\
1675 A 4\dash byte or 8\dash byte length containing the size in bytes of the
1676 contents of the .debug\_info section generated to represent
1677 this compilation unit. In the 32\dash bit DWARF format, this is
1678 a 4\dash byte unsigned length; in the 64\dash bit DWARF format, this
1679 is an 8-byte unsigned length
1680 (see Section \refersec{datarep:32bitand64bitdwarfformats}).
1685 This header is followed by a series of tuples. Each tuple
1686 consists of a 4\dash byte or 8\dash byte offset followed by a string
1687 of non\dash null bytes terminated by one null byte.
1689 DWARF format, this is a 4\dash byte offset; in the 64\dash bit DWARF
1690 format, it is an 8\dash byte offset.
1691 Each set is terminated by an
1692 offset containing the value 0.
1695 \section{Address Range Table}
1696 \label{datarep:addrssrangetable}
1698 Each set of entries in the table of address ranges contained
1699 in the .debug\_aranges section begins with a header containing:
1701 \begin{enumerate}[1.]
1702 % FIXME The unit length text is not fully consistent across
1705 \item unit\_length (initial length) \\
1706 A 4-byte or 12-byte length containing the length of the
1707 set of entries for this compilation unit, not including the
1708 length field itself. In the 32-bit DWARF format, this is a
1709 4-byte unsigned integer (which must be less than 0xfffffff0);
1710 in the 64-bit DWARF format, this consists of the 4-byte value
1711 0xffffffff followed by an 8-byte unsigned integer that gives
1713 (see Section \refersec{datarep:32bitand64bitdwarfformats}).
1715 \item version (uhalf) \\
1716 A 2\dash byte version identifier containing the value 2
1717 (see Appendix \refersec{app:dwarfsectionversionnumbersinformative}).
1719 \item debug\_info\_offset (section offset) \\
1720 A 4\dash byte or 8\dash byte offset into the .debug\_info section of
1721 the compilation unit header. In the 32\dash bit DWARF format,
1722 this is a 4\dash byte unsigned offset; in the 64\dash bit DWARF format,
1723 this is an 8\dash byte unsigned offset
1724 (see Section \refersec{datarep:32bitand64bitdwarfformats}).
1726 \item address\_size (ubyte) \\
1727 A 1\dash byte unsigned integer containing the size in bytes of an
1728 address (or the offset portion of an address for segmented
1729 addressing) on the target system.
1731 \item segment\_size (ubyte) \\
1732 A 1\dash byte unsigned integer containing the size in bytes of a
1733 segment selector on the target system.
1737 This header is followed by a series of tuples. Each tuple
1738 consists of a segment, an address and a length.
1740 size is given by the segment\_size field of the header; the
1741 address and length size are each given by the address\_size
1742 field of the header.
1743 The first tuple following the header in
1744 each set begins at an offset that is a multiple of the size
1745 of a single tuple (that is, the size of a segment selector
1746 plus twice the size of an address).
1747 The header is padded, if
1748 necessary, to that boundary. Each set of tuples is terminated
1749 by a 0 for the segment, a 0 for the address and 0 for the
1750 length. If the segment\_size field in the header is zero,
1751 the segment selectors are omitted from all tuples, including
1752 the terminating tuple.
1755 \section{Line Number Information}
1756 \label{datarep:linenumberinformation}
1758 The version number in the line number program header is 4
1759 (see Appendix \refersec{app:dwarfsectionversionnumbersinformative}).
1761 The boolean values ``true'' and ``false''
1762 used by the line number information program are encoded
1763 as a single byte containing the value 0
1764 for ``false,'' and a non-zero value for ``true.''
1766 The encodings for the standard opcodes are given in
1767 Table \refersec{tab:linenumberstandardopcodeencodings}.
1769 % Odd that the 'Name' field captalized here, it is not caps elsewhere.
1771 \setlength{\extrarowheight}{0.1cm}
1772 \begin{longtable}{l|c}
1773 \caption{Line Number Standard Opcode encodings} \label{tab:linenumberstandardopcodeencodings}\\
1774 \hline \\ \bfseries Opcode Name&\bfseries Value \\ \hline
1776 \bfseries Opcode Name&\bfseries Value\\ \hline
1778 \hline \emph{Continued on next page}
1783 DW\-\_LNS\-\_copy&0x01 \\
1784 DW\-\_LNS\-\_advance\-\_pc&0x02 \\
1785 DW\-\_LNS\-\_advance\-\_line&0x03 \\
1786 DW\-\_LNS\-\_set\-\_file&0x04 \\
1787 DW\-\_LNS\-\_set\-\_column&0x05 \\
1788 DW\-\_LNS\-\_negate\-\_stmt&0x06 \\
1789 DW\-\_LNS\-\_set\-\_basic\-\_block&0x07 \\
1790 DW\-\_LNS\-\_const\-\_add\-\_pc*0x08 \\
1791 DW\-\_LNS\-\_fixed\-\_advance\-\_pc&0x09 \\
1792 DW\-\_LNS\-\_set\-\_prologue\-\_end&0x0a \\
1793 DW\-\_LNS\-\_set\-\_epilogue\-\_begin&0x0b \\
1794 DW\-\_LNS\-\_set\-\_isa&0x0c \\
1800 The encodings for the extended opcodes are given in
1801 Table \refersec{tab:linenumberextendedopcodeencodings}.
1804 \setlength{\extrarowheight}{0.1cm}
1805 \begin{longtable}{l|c}
1806 \caption{Line Number Extended Opcode encodings} \label{tab:linenumberextendedopcodeencodings}\\
1807 \hline \\ \bfseries Opcode Name&\bfseries Value \\ \hline
1809 \bfseries Opcode Name&\bfseries Value\\ \hline
1811 \hline \emph{Continued on next page}
1816 DW\-\_LNE\-\_end\-\_sequence&0x01 \\
1817 DW\-\_LNE\-\_set\-\_address&0x02\\
1818 DW\-\_LNE\-\_define\-\_file&0x03\\
1819 DW\-\_LNE\-\_set\-\_discriminator \ddag &0x04 \\
1820 DW\-\_LNE\-\_lo\-\_user&0x80 \\
1821 DW\-\_LNE\-\_hi\-\_user&0xff \\
1824 \ddag Extended opcode new in DWARF Version 4.
1827 \section{Macro Information}
1828 \label{datarep:macroinformation}
1830 The source line numbers and source file indices encoded in the
1831 macro information section are represented as unsigned LEB128
1832 numbers as are the constants in a DW\-\_MACINFO\-\_vendor\-\_ext entry.
1834 The macinfo type is encoded as a single byte.
1835 The encodings are given in
1836 Table \refersec{tab:macinfotypeencodings}.
1840 \setlength{\extrarowheight}{0.1cm}
1841 \begin{longtable}{l|c}
1842 \caption{Macinfo Type Encodings} \label{tab:macinfotypeencodings}\\
1843 \hline \\ \bfseries Macinfo Type Name&\bfseries Value \\ \hline
1845 \bfseries Macinfo Type Name&\bfseries Value\\ \hline
1847 \hline \emph{Continued on next page}
1852 DW\-\_MACINFO\-\_define&0x01 \\
1853 DW\-\_MACINFO\-\_undef&0x02 \\
1854 DW\-\_MACINFO\-\_start\-\_file&0x03 \\
1855 DW\-\_MACINFO\-\_end\-\_file&0x04 \\
1856 DW\-\_MACINFO\-\_vendor\-\_ext&0xff \\
1861 \section{Call Frame Information}
1862 \label{datarep:callframeinformation}
1864 In the 32\dash bit DWARF format, the value of the CIE id in the
1865 CIE header is 0xffffffff; in the 64\dash bit DWARF format, the
1866 value is 0xffffffffffffffff.
1868 The value of the CIE version number is 4
1869 (see Appendix \refersec{app:dwarfsectionversionnumbersinformative}).
1871 Call frame instructions are encoded in one or more bytes. The
1872 primary opcode is encoded in the high order two bits of
1873 the first byte (that is, opcode = byte >> 6). An operand
1874 or extended opcode may be encoded in the low order 6
1875 bits. Additional operands are encoded in subsequent bytes.
1876 The instructions and their encodings are presented in
1877 Table \refersec{tab:callframeinstructionencodings}.
1880 \setlength{\extrarowheight}{0.1cm}
1881 \begin{longtable}{l|c|c|l|l}
1882 \caption{Call frame instruction encodings} \label{tab:callframeinstructionencodings} \\
1883 \hline \\ &\bfseries High 2 &\bfseries Low 6 & & \\
1884 \bfseries Instruction&\bfseries Bits &\bfseries Bits &\bfseries Operand 1 &\bfseries Operand 2\\ \hline
1886 & \bfseries High 2 &\bfseries Low 6 & &\\
1887 \bfseries Instruction&\bfseries Bits &\bfseries Bits &\bfseries Operand 1 &\bfseries Operand 2\\ \hline
1889 \hline \emph{Continued on next page}
1894 \livelink{chap:DWCFAadvanceloc}{DW\-\_CFA\-\_advance\-\_loc}&0x1&delta & \\
1895 \livelink{chap:DWCFAoffset}{DW\-\_CFA\-\_offset}&0x2®ister&ULEB128 offset \\
1896 \livelink{chap:DWCFArestore}{DW\-\_CFA\-\_restore}&0x3®ister & & \\
1897 \livelink{chap:DWCFAnop}{DW\-\_CFA\-\_nop}&0&0 & & \\
1898 \livelink{chap:DWCFAsetloc}{DW\-\_CFA\-\_set\-\_loc}&0&0x01&address & \\
1899 \livelink{chap:DWCFAadvanceloc1}{DW\-\_CFA\-\_advance\-\_loc1}&0&0x02&1\dash byte delta & \\
1900 \livelink{chap:DWCFAadvanceloc2}{DW\-\_CFA\-\_advance\-\_loc2}&0&0x03&2\dash byte delta & \\
1901 \livelink{chap:DWCFAadvanceloc4}{DW\-\_CFA\-\_advance\-\_loc4}&0&0x04&4\dash byte delta & \\
1902 \livelink{chap:DWCFAoffsetextended}{DW\-\_CFA\-\_offset\-\_extended}&0&0x05&ULEB128 register&ULEB128 offset \\
1903 \livelink{chap:DWCFArestoreextended}{DW\-\_CFA\-\_restore\-\_extended}&0&0x06&ULEB128 register & \\
1904 \livelink{chap:DWCFAundefined}{DW\-\_CFA\-\_undefined}&0&0x07&ULEB128 register & \\
1905 \livelink{chap:DWCFAsamevalue}{DW\-\_CFA\-\_same\-\_value}&0&0x08 &ULEB128 register & \\
1906 \livelink{chap:DWCFAregister}{DW\-\_CFA\-\_register}&0&0x09&ULEB128 register &ULEB128 offset \\
1907 \livelink{chap:DWCFArememberstate}{DW\-\_CFA\-\_remember\-\_state}&0&0x0a & & \\
1908 \livelink{chap:DWCFArestorestate}{DW\-\_CFA\-\_restore\-\_state}&0&0x0b & & \\
1909 \livelink{chap:DWCFAdefcfa}{DW\-\_CFA\-\_def\-\_cfa}&0&0x0c &ULEB128 register&ULEB128 offset \\
1910 \livelink{chap:DWCFAdefcfaregister}{DW\-\_CFA\-\_def\-\_cfa\-\_register}&0&0x0d&ULEB128 register & \\
1911 \livelink{chap:DWCFAdefcfaoffset}{DW\-\_CFA\-\_def\-\_cfa\-\_offset}&0&0x0e &ULEB128 offset & \\
1912 \livelink{chap:DWCFAdefcfaexpression}{DW\-\_CFA\-\_def\-\_cfa\-\_expression}&0&0x0f &BLOCK \\
1913 \livelink{chap:DWCFAexpression}{DW\-\_CFA\-\_expression}&0&0x10&ULEB128 register & BLOCK \\
1915 \livelink{chap:DWCFAoffsetextendedsf}{DW\-\_CFA\-\_offset\-\_extended\-\_sf}&0&0x11&ULEB128 register&SLEB128 offset \\
1916 \livelink{chap:DWCFAdefcfasf}{DW\-\_CFA\-\_def\-\_cfa\-\_sf}&0&0x12&ULEB128 register&SLEB128 offset \\
1917 \livelink{chap:DWCFAdefcfaoffsetsf}{DW\-\_CFA\-\_def\-\_cfa\-\_offset\-\_sf}&0&0x13&SLEB128 offset & \\
1918 \livelink{chap:DWCFAvaloffset}{DW\-\_CFA\-\_val\-\_offset}&0&0x14&ULEB128&ULEB128 \\
1919 \livelink{chap:DWCFAvaloffsetsf}{DW\-\_CFA\-\_val\-\_offset\-\_sf}&0&0x15&ULEB128&SLEB128 \\
1920 \livelink{chap:DWCFAvalexpression}{DW\-\_CFA\-\_val\-\_expression}&0&0x16&ULEB128&BLOCK \\
1921 \livetarg{chap:DWCFAlouser}{DW\-\_CFA\-\_lo\-\_user}&0&0x1c & & \\
1922 \livetarg{chap:DWCFAhiuser}{DW\-\_CFA\-\_hi\-\_user}&0&0x3f & & \\
1926 \section{Non-continguous Address Ranges}
1927 \label{datarep:noncontiguousaddressranges}
1929 Each entry in a range list
1930 (see Section \refersec{chap:noncontiguousaddressranges})
1932 range list entry, a base address selection entry, or an end
1935 A range list entry consists of two relative addresses. The
1936 addresses are the same size as addresses on the target machine.
1938 A base address selection entry and an end of list entry each
1939 consist of two (constant or relocated) addresses. The two
1940 addresses are the same size as addresses on the target machine.
1942 For a range list to be specified, the base address of the
1943 corresponding compilation unit must be defined
1944 (see Section \refersec{chap:normalandpartialcompilationunitentries}).
1947 \section{Dependencies and Constraints}
1948 \label{datarep:dependenciesandconstraints}
1950 The debugging information in this format is intended to
1951 exist in the .debug\_abbrev, .debug\_aranges, .debug\_frame,
1952 .debug\_info, .debug\_line, .debug\_loc, .debug\_macinfo,
1953 .debug\_pubnames, .debug\_pubtypes, .debug\_ranges, .debug\_str
1954 and .debug\_types sections of an object file, or equivalent
1955 separate file or database. The information is not
1956 word\dash aligned. Consequently: •
1959 \item For the 32\dash bit DWARF format and a target architecture with
1960 32\dash bit addresses, an assembler or compiler must provide a way
1961 to produce 2\dash byte and 4\dash byte quantities without alignment
1962 restrictions, and the linker must be able to relocate a
1963 4\dash byte address or section offset that occurs at an arbitrary
1966 \item For the 32\dash bit DWARF format and a target architecture with
1967 64\dash bit addresses, an assembler or compiler must provide a
1968 way to produce 2\dash byte, 4\dash byte and 8\dash byte quantities without
1969 alignment restrictions, and the linker must be able to relocate
1970 an 8\dash byte address or 4\dash byte section offset that occurs at an
1971 arbitrary alignment.
1973 \item For the 64\dash bit DWARF format and a target architecture with
1974 32\dash bit addresses, an assembler or compiler must provide a
1975 way to produce 2\dash byte, 4\dash byte and 8\dash byte quantities without
1976 alignment restrictions, and the linker must be able to relocate
1977 a 4\dash byte address or 8\dash byte section offset that occurs at an
1978 arbitrary alignment.
1980 \textit{It is expected that this will be required only for very large
1981 32\dash bit programs or by those architectures which support
1982 a mix of 32\dash bit and 64\dash bit code and data within the same
1985 \item For the 64\dash bit DWARF format and a target architecture with
1986 64\dash bit addresses, an assembler or compiler must provide a
1987 way to produce 2\dash byte, 4\dash byte and 8\dash byte quantities without
1988 alignment restrictions, and the linker must be able to
1989 relocate an 8\dash byte address or section offset that occurs at
1990 an arbitrary alignment.
1993 \section{Integer Representation Names}
1994 \label{datarep:integerrepresentationnames}
1996 The sizes of the integers used in the lookup by name, lookup
1997 by address, line number and call frame information sections
1999 Table 41 \refersec{tab:integerrepresentationnames}.
2002 \setlength{\extrarowheight}{0.1cm}
2003 \begin{longtable}{c|l}
2004 \caption{Integer Representation Names} \label{tab:integerrepresentationnames}\\
2005 \hline \\ \bfseries Representation Name&\bfseries Representation \\ \hline
2007 \bfseries Representation Name&\bfseries Representation\\ \hline
2009 \hline \emph{Continued on next page}
2014 sbyte& signed, 1\dash byte integer \\
2015 ubyte&unsigned, 1\dash byte integer \\
2016 uhalf&unsigned, 2\dash byte integer \\
2017 uword&unsigned, 4\dash byte integer \\
2022 \section{Type Signature Computation}
2023 \label{datarep:typesignaturecomputation}
2025 A type signature is computed only by the DWARF producer;
2026 it is used by a DWARF consumer to resolve type references to
2027 the type definitions that are contained in type units.
2029 The type signature for a type T0 is formed from the MD5
2030 hash of a flattened description of the type. The flattened
2031 description of the type is a byte sequence derived from the
2032 DWARF encoding of the type as follows:
2034 \begin{enumerate}[1.]
2036 \item Start with an empty sequence S and a list V of visited
2037 types, where V is initialized to a list containing the type
2038 T0 as its single element. Elements in V are indexed from 1,
2041 \item If the debugging information entry represents a type that
2042 is nested inside another type or a namespace, append to S
2043 the type’s context as follows: For each surrounding type
2044 or namespace, beginning with the outermost such construct,
2045 append the letter 'C', the DWARF tag of the construct, and
2046 the name (taken from the \livelink{chap:DWATname}{DW\-\_AT\-\_name} attribute) of the type
2047 or namespace (including its trailing null byte).
2049 \item Append to S the letter 'D', followed by the DWARF tag of
2050 the debugging information entry.
2052 \item For each of the following attributes that are present in
2053 the debugging information entry, in the order listed below,
2054 append to S a marker letter (see below), the DWARF attribute
2055 code, and the attribute value.
2058 \item \livelink{chap:DWATname}{DW\-\_AT\-\_name}
2059 \item \livelink{chap:DWATaccessibility}{DW\-\_AT\-\_accessibility}
2060 \item \livelink{chap:DWATaddressclass}{DW\-\_AT\-\_address\-\_class}
2061 \item \livelink{chap:DWATallocated}{DW\-\_AT\-\_allocated}
2062 \item \livelink{chap:DWATartificial}{DW\-\_AT\-\_artificial}
2063 \item \livelink{chap:DWATassociated}{DW\-\_AT\-\_associated}
2064 \item \livelink{chap:DWATbinaryscale}{DW\-\_AT\-\_binary\-\_scale}
2065 \item \livelink{chap:DWATbitoffset}{DW\-\_AT\-\_bit\-\_offset}
2066 \item \livelink{chap:DWATbitsize}{DW\-\_AT\-\_bit\-\_size}
2067 \item \livelink{chap:DWATbitstride}{DW\-\_AT\-\_bit\-\_stride}
2068 \item \livelink{chap:DWATbytesize}{DW\-\_AT\-\_byte\-\_size}
2069 \item \livelink{chap:DWATbytestride}{DW\-\_AT\-\_byte\-\_stride}
2070 \item \livelink{chap:DWATconstexpr}{DW\-\_AT\-\_const\-\_expr}
2071 \item \livelink{chap:DWATconstvalue}{DW\-\_AT\-\_const\-\_value}
2072 \item \livelink{chap:DWATcontainingtype}{DW\-\_AT\-\_containing\-\_type}
2073 \item \livelink{chap:DWATcount}{DW\-\_AT\-\_count}
2074 \item \livelink{chap:DWATdatabitoffset}{DW\-\_AT\-\_data\-\_bit\-\_offset}
2075 \item \livelink{chap:DWATdatalocation}{DW\-\_AT\-\_data\-\_location}
2076 \item \livelink{chap:DWATdatamemberlocation}{DW\-\_AT\-\_data\-\_member\-\_location}
2077 \item \livelink{chap:DWATdecimalscale}{DW\-\_AT\-\_decimal\-\_scale}
2078 \item \livelink{chap:DWATdecimalsign}{DW\-\_AT\-\_decimal\-\_sign}
2079 \item \livelink{chap:DWATdefaultvalue}{DW\-\_AT\-\_default\-\_value}
2080 \item \livelink{chap:DWATdigitcount}{DW\-\_AT\-\_digit\-\_count}
2081 \item \livelink{chap:DWATdiscr}{DW\-\_AT\-\_discr}
2082 \item \livelink{chap:DWATdiscrlist}{DW\-\_AT\-\_discr\-\_list}
2083 \item \livelink{chap:DWATdiscrvalue}{DW\-\_AT\-\_discr\-\_value}
2084 \item \livelink{chap:DWATencoding}{DW\-\_AT\-\_encoding}
2085 \item \livelink{chap:DWATenumclass}{DW\-\_AT\-\_enum\-\_class}
2086 \item \livelink{chap:DWATendianity}{DW\-\_AT\-\_endianity}
2087 \item \livelink{chap:DWATexplicit}{DW\-\_AT\-\_explicit}
2088 \item \livelink{chap:DWATisoptional}{DW\-\_AT\-\_is\-\_optional}
2089 \item \livelink{chap:DWATlocation}{DW\-\_AT\-\_location}
2090 \item \livelink{chap:DWATlowerbound}{DW\-\_AT\-\_lower\-\_bound}
2091 \item \livelink{chap:DWATmutable}{DW\-\_AT\-\_mutable}
2092 \item \livelink{chap:DWATordering}{DW\-\_AT\-\_ordering}
2093 \item \livelink{chap:DWATpicturestring}{DW\-\_AT\-\_picture\-\_string}
2094 \item \livelink{chap:DWATprototyped}{DW\-\_AT\-\_prototyped}
2095 \item \livelink{chap:DWATsmall}{DW\-\_AT\-\_small}
2096 \item \livelink{chap:DWATsegment}{DW\-\_AT\-\_segment}
2097 \item \livelink{chap:DWATstringlength}{DW\-\_AT\-\_string\-\_length}
2098 \item \livelink{chap:DWATthreadsscaled}{DW\-\_AT\-\_threads\-\_scaled}
2099 \item \livelink{chap:DWATupperbound}{DW\-\_AT\-\_upper\-\_bound}
2100 \item \livelink{chap:DWATuselocation}{DW\-\_AT\-\_use\-\_location}
2101 \item \livelink{chap:DWATuseUTF8}{DW\-\_AT\-\_use\-\_UTF8}
2102 \item \livelink{chap:DWATvariableparameter}{DW\-\_AT\-\_variable\-\_parameter}
2103 \item \livelink{chap:DWATvirtuality}{DW\-\_AT\-\_virtuality}
2104 \item \livelink{chap:DWATvisibility}{DW\-\_AT\-\_visibility}
2105 \item \livelink{chap:DWATvtableelemlocation}{DW\-\_AT\-\_vtable\-\_elem\-\_location}
2108 Note that except for the initial \livelink{chap:DWATname}{DW\-\_AT\-\_name} attribute,
2109 attributes are appended in order according to the alphabetical
2110 spelling of their identifier.
2112 If an implementation defines any vendor-specific attributes,
2113 any such attributes that are essential to the definition of
2114 the type should also be included at the end of the above list,
2115 in their own alphabetical suborder.
2117 An attribute that refers to another type entry T is processed
2118 as follows: (a) If T is in the list V at some V[x], use the
2119 letter 'R' as the marker and use the unsigned LEB128 encoding
2120 of x as the attribute value; otherwise, (b) use the letter 'T'
2121 as the marker, process the type T recursively by performing
2122 Steps 2 through 7, and use the result as the attribute value.
2124 Other attribute values use the letter 'A' as the marker, and
2125 the value consists of the form code (encoded as an unsigned
2126 LEB128 value) followed by the encoding of the value according
2127 to the form code. To ensure reproducibility of the signature,
2128 the set of forms used in the signature computation is limited
2129 to the following: \livelink{chap:DWFORMsdata}{DW\-\_FORM\-\_sdata},
2130 \livelink{chap:DWFORMflag}{DW\-\_FORM\-\_flag},
2131 \livelink{chap:DWFORMstring}{DW\-\_FORM\-\_string},
2132 and \livelink{chap:DWFORMblock}{DW\-\_FORM\-\_block}.
2134 \item If the tag in Step 3 is one of \livelink{chap:DWTAGpointertype}{DW\-\_TAG\-\_pointer\-\_type},
2135 \livelink{chap:DWTAGreferencetype}{DW\-\_TAG\-\_reference\-\_type},
2136 \livelink{chap:DWTAGrvaluereferencetype}{DW\-\_TAG\-\_rvalue\-\_reference\-\_type},
2137 \livelink{chap:DWTAGptrtomembertype}{DW\-\_TAG\-\_ptr\-\_to\-\_member\-\_type},
2138 or \livelink{chap:DWTAGfriend}{DW\-\_TAG\-\_friend}, and the referenced
2139 type (via the \livelink{chap:DWATtype}{DW\-\_AT\-\_type} or
2140 \livelink{chap:DWATfriend}{DW\-\_AT\-\_friend} attribute) has a
2141 \livelink{chap:DWATname}{DW\-\_AT\-\_name} attribute, append to S the letter 'N', the DWARF
2142 attribute code (\livelink{chap:DWATtype}{DW\-\_AT\-\_type} or
2143 \livelink{chap:DWATfriend}{DW\-\_AT\-\_friend}), the context of
2144 the type (according to the method in Step 2), the letter 'E',
2145 and the name of the type. For \livelink{chap:DWTAGfriend}{DW\-\_TAG\-\_friend}, if the referenced
2146 entry is a \livelink{chap:DWTAGsubprogram}{DW\-\_TAG\-\_subprogram}, the context is omitted and the
2147 name to be used is the ABI-specific name of the subprogram
2148 (e.g., the mangled linker name).
2151 \item 6.If the tag in Step 3 is not one of \livelink{chap:DWTAGpointertype}{DW\-\_TAG\-\_pointer\-\_type},
2152 \livelink{chap:DWTAGreferencetype}{DW\-\_TAG\-\_reference\-\_type},
2153 \livelink{chap:DWTAGrvaluereferencetype}{DW\-\_TAG\-\_rvalue\-\_reference\-\_type},
2154 \livelink{chap:DWTAGptrtomembertype}{DW\-\_TAG\-\_ptr\-\_to\-\_member\-\_type}, or
2155 \livelink{chap:DWTAGfriend}{DW\-\_TAG\-\_friend}, but has
2156 a \livelink{chap:DWATtype}{DW\-\_AT\-\_type} attribute, or if the referenced type (via
2157 the \livelink{chap:DWATtype}{DW\-\_AT\-\_type} or
2158 \livelink{chap:DWATfriend}{DW\-\_AT\-\_friend} attribute) does not have a
2159 \livelink{chap:DWATname}{DW\-\_AT\-\_name} attribute, the attribute is processed according to
2160 the method in Step 4 for an attribute that refers to another
2164 \item Visit each child C of the debugging information
2165 entry as follows: If C is a nested type entry or a member
2166 function entry, and has a \livelink{chap:DWATname}{DW\-\_AT\-\_name} attribute, append to
2167 S the letter 'S', the tag of C, and its name; otherwise,
2168 process C recursively by performing Steps 3 through 7,
2169 appending the result to S. Following the last child (or if
2170 there are no children), append a zero byte.
2175 For the purposes of this algorithm, if a debugging information
2177 \livelink{chap:DWATspecification}{DW\-\_AT\-\_specification}
2178 attribute that refers to
2179 another entry D (which has a
2180 \livelink{chap:DWATdeclaration}{DW\-\_AT\-\_declaration}
2182 then S inherits the attributes and children of D, and S is
2183 processed as if those attributes and children were present in
2184 the entry S. Exception: if a particular attribute is found in
2185 both S and D, the attribute in S is used and the corresponding
2186 one in D is ignored.
2188 DWARF tag and attribute codes are appended to the sequence
2189 as unsigned LEB128 values, using the values defined earlier
2192 \textit{A grammar describing this computation may be found in
2193 Appendix \refersec{app:typesignaturecomputationgrammar}.
2196 \textit{An attribute that refers to another type entry should
2197 be recursively processed or replaced with the name of the
2198 referent (in Step 4, 5 or 6). If neither treatment applies to
2199 an attribute that references another type entry, the entry
2200 that contains that attribute should not be considered for a
2201 separate type unit.}
2203 \textit{If a debugging information entry contains an attribute from
2204 the list above that would require an unsupported form, that
2205 entry should not be considered for a separate type unit.}
2207 \textit{A type should be considered for a separate type unit only
2208 if all of the type entries that it contains or refers to in
2209 Steps 6 and 7 can themselves each be considered for a separate
2212 Where the DWARF producer may reasonably choose two or more
2213 different forms for a given attribute, it should choose
2214 the simplest possible form in computing the signature. (For
2215 example, a constant value should be preferred to a location
2216 expression when possible.)
2218 Once the string S has been formed from the DWARF encoding,
2219 an MD5 hash is computed for the string and the lower 64 bits
2220 are taken as the type signature.
2222 \textit{The string S is intended to be a flattened representation of
2223 the type that uniquely identifies that type (i.e., a different
2224 type is highly unlikely to produce the same string).}
2226 \textit{A debugging information entry should not be placed in a
2227 separate type unit if any of the following apply:}
2231 \item \textit{The entry has an attribute whose value is a location
2232 expression, and the location expression contains a reference to
2233 another debugging information entry (e.g., a \livelink{chap:DWOPcallref}{DW\-\_OP\-\_call\-\_ref}
2234 operator), as it is unlikely that the entry will remain
2235 identical across compilation units.}
2237 \item \textit{The entry has an attribute whose value refers
2238 to a code location or a location list.}
2240 \item \textit{The entry has an attribute whose value refers
2241 to another debugging information entry that does not represent
2246 \textit{Certain attributes are not included in the type signature:}
2249 \item \textit{The \livelink{chap:DWATdeclaration}{DW\-\_AT\-\_declaration} attribute is not included because it
2250 indicates that the debugging information entry represents an
2251 incomplete declaration, and incomplete declarations should
2252 not be placed in separate type units.}
2254 \item \textit{The \livelink{chap:DWATdescription}{DW\-\_AT\-\_description} attribute is not included because
2255 it does not provide any information unique to the defining
2256 declaration of the type.}
2258 \item \textit{The \livelink{chap:DWATdeclfile}{DW\-\_AT\-\_decl\-\_file}, \livelink{chap:DWATdeclline}{DW\-\_AT\-\_decl\-\_line}, and
2259 \livelink{chap:DWATdeclcolumn}{DW\-\_AT\-\_decl\-\_column} attributes are not included because they
2260 may vary from one source file to the next, and would prevent
2261 two otherwise identical type declarations from producing the