debugging information entry itself, of the attribute types
and of other fundamental elements described above.
-
\section{Vendor Extensibility}
\label{datarep:vendorextensibility}
\addtoindexx{vendor extensibility}
base type encodings, location operations, language names,
calling conventions and call frame instructions.
-The labels denoting the beginning and end of the reserved
-\hypertarget{chap:DWXXXlohiuser}{}
-value range for vendor specific extensions consist of the
+The labels denoting the beginning and end of the
+\hypertarget{chap:DWXXXlohiuser}{reserved value range}
+for vendor specific extensions consist of the
appropriate prefix
-(\DWATlouserMARK{}\DWAThiuserMARK{} DW\_AT,
-\DWATElouserMARK{}\DWATEhiuserMARK{} DW\_ATE,
-\DWCClouserMARK{}\DWCChiuserMARK{} DW\_CC,
-\DWCFAlouserMARK{}\DWCFAhiuserMARK{} DW\_CFA
-\DWENDlouserMARK{}\DWENDhiuserMARK{} DW\_END,
-\DWLANGlouserMARK{}\DWLANGhiuserMARK{} DW\_LANG,
-\DWLNElouserMARK{}\DWLNEhiuserMARK{} DW\_LNE,
-\DWMACROlouserMARK{}\DWMACROhiuserMARK{}DW\_MACRO,
-\DWOPlouserMARK{}\DWOPhiuserMARK{} DW\_OP or
-\DWTAGlouserMARK{}\DWTAGhiuserMARK{} DW\_TAG,
-respectively) followed by
-\_lo\_user or \_hi\_user.
+(\DWATlouserMARK{}\DWAThiuserMARK{}DW\_AT,
+\DWATElouserMARK{}\DWATEhiuserMARK{}DW\_ATE,
+\DWCClouserMARK{}\DWCChiuserMARK{}DW\_CC,
+\DWCFAlouserMARK{}\DWCFAhiuserMARK{}DW\_CFA,
+\DWENDlouserMARK{}\DWENDhiuserMARK{}DW\_END,
+\DWIDXlouserMARK{}\DWIDXhiuserMARK{}DW\_IDX,
+\DWLANGlouserMARK{}\DWLANGhiuserMARK{}DW\_LANG,
+\DWLNCTlouserMARK{}\DWLNCThiuserMARK{}DW\_LNCT,
+\DWLNElouserMARK{}\DWLNEhiuserMARK{}DW\_LNE,
+\DWMACROlouserMARK{}\DWMACROhiuserMARK{}DW\_MACRO,
+\DWOPlouserMARK{}\DWOPhiuserMARK{}DW\_OP or
+\DWTAGlouserMARK{}\DWTAGhiuserMARK{}DW\_TAG)
+followed by \_lo\_user or \_hi\_user.
Values in the range between \textit{prefix}\_lo\_user
and \textit{prefix}\_hi\_user inclusive,
are reserved for vendor specific extensions. Vendors may
future system\dash defined values. All other values are reserved
for use by the system.
-\textit{For example, for DIE tags, the special
-labels are \DWTAGlouserNAME{} and \DWTAGhiuserNAME.}
+\textit{For example, for debugging information entry
+tags, the special labels are \DWTAGlouserNAME{} and \DWTAGhiuserNAME.}
\textit{There may also be codes for vendor specific extensions
between the number of standard line number opcodes and
number of standard opcodes varies with the DWARF version,
the range for extensions is also version dependent. Thus,
\DWLNSlouserTARG{} and
-\DWLNShiuserTARG{} symbols are not defined.
-}
+\DWLNShiuserTARG{} symbols are not defined.}
Vendor defined tags, attributes, base type encodings, location
atoms, language names, line number actions, calling conventions
To ensure that extensions added by one vendor may be safely
ignored by consumers that do not understand those extensions,
-the following rules should be followed:
+the following rules must be followed:
\begin{enumerate}[1. ]
-\item New attributes should be added in such a way that a
+\item New attributes are added in such a way that a
debugger may recognize the format of a new attribute value
without knowing the content of that attribute value.
-\item The semantics of any new attributes should not alter
+\item The semantics of any new attributes do not alter
the semantics of previously existing attributes.
-\item The semantics of any new tags should not conflict with
+\item The semantics of any new tags do not conflict with
the semantics of previously existing tags.
-\item Do not add any new forms of attribute value.
+\item New forms of attribute value are not added.
\end{enumerate}
forms, base type encodings, location operations, languages,
line number program opcodes, macro information entries and tag
names to represent an error condition or unknown value. DWARF
-does not specify names for these reserved values, since they
-do not represent valid encodings for the given type and should
+does not specify names for these reserved values, because they
+do not represent valid encodings for the given type and do
not appear in DWARF debugging information.
\wffffffff are reserved by DWARF to indicate some form of
extension relative to \DWARFVersionII; such values must not
be interpreted as a length field. The use of one such value,
-\xffffffff, is defined below
-(see Section \refersec{datarep:32bitand64bitdwarfformats});
+\xffffffff, is defined in
+Section \refersec{datarep:32bitand64bitdwarfformats});
the use of
the other values is reserved for possible future extensions.
-
\section{Relocatable, Split, Executable, Shared and Package Object Files}
\label{datarep:executableobjectsandsharedobjects}
within the virtual address space of the program, and require
relocation.
+\item A DWARF expression may contain a \DWOPaddr{} (see Section
+\refersec{chap:literalencodings}) which contains a location within
+the virtual address space of the program, and require relocation.
+
+\needlines{4}
\item Debugging information entries may have attributes with the form
\DWFORMsecoffset{} (see Section \refersec{datarep:attributeencodings}).
These attributes refer to
debugging information in other debugging information sections within
the object file, and must be relocated during the linking process.
-Exception: attributes whose values are relative to a base offset given
-by \DWATrangesbase{} do not need relocation.
-
-\item Debugging information entries may have attributes with the form
-\DWFORMrefone, \DWFORMreftwo, \DWFORMreffour, \DWFORMrefeight, or
-\DWFORMrefudata{} (see Section \refersec{datarep:attributeencodings}).
-These attributes refer to other
-debugging information entries within the same compilation unit, and
-are relative to the beginning of the current compilation unit. These
-values do not need relocation.
+\par
+However, if a \DWATrangesbase{} attribute is present, the offset in
+a \DWATranges{} attribute (which uses form \DWFORMsecoffset) is
+relative to the given base offset--no relocation is involved.
\item Debugging information entries may have attributes with the form
\DWFORMrefaddr{} (see Section \refersec{datarep:attributeencodings}).
These attributes refer to strings in
the \dotdebugstr{} section. These values require relocation.
-\item Entries in the \dotdebugloc{}, \dotdebugranges{}, and \dotdebugaranges{}
+\item Entries in the \dotdebugaddr, \dotdebugloc{}, \dotdebugranges{}
+and \dotdebugaranges{}
sections contain references to locations within the virtual address
space of the program, and require relocation.
opcode is a reference to a location within the virtual address space
of the program, and requires relocation.
- The \dotdebugstroffsets{} section contains a list of string offsets,
+\item The \dotdebugstroffsets{} section contains a list of string offsets,
each of which is an offset of a string in the \dotdebugstr{} section. Each
of these offsets requires relocation. Depending on the implementation,
these relocations may be implicit (that is, the producer may not need to
emit any explicit relocation information for these offsets).
+
+\item The \HFNdebuginfooffset{} field in the \dotdebugaranges{} header and
+the list of compilation units following the \dotdebugnames{} header contain
+references to the \dotdebuginfo{} section. These references require relocation
+so that after linking they refer to the correct contribution in the combined
+\dotdebuginfo{} section in the executable file.
+
+\item Frame descriptor entries in the \dotdebugframe{} section
+(see Section \refersec{chap:structureofcallframeinformation}) contain an
+\HFNinitiallocation{} field value within the virtual address
+space of the program and require relocation.
+
\end{itemize}
+\needlines{4}
+\textit{Note that operands of classes
+\CLASSconstant{} and
+\CLASSflag{} do not require relocation. Attribute operands that use
+forms \DWFORMstring{},
+\DWFORMrefone, \DWFORMreftwo, \DWFORMreffour, \DWFORMrefeight, or
+\DWFORMrefudata{} also do not need relocation.}
+
\subsection{Split DWARF Object Files}
\label{datarep:splitdwarfobjectfiles}
\addtoindexx{split DWARF object file}
A DWARF producer may partition the debugging
information such that the majority of the debugging
information can remain in individual object files without
-being processed by the linker. The first partition contains
+being processed by the linker.
+
+\textit{This reduces link time by reducing the amount of information
+the linker must process.}
+
+\needlines{6}
+\subsubsection{First Partition (with Skeleton Unit)}
+The first partition contains
debugging information that must still be processed by the linker,
and includes the following:
\begin{itemize}
the skeleton compilation unit uses the \DWFORMstrx{} form.
\end{itemize}
The attributes contained in the skeleton compilation
-unit can be used by a DWARF consumer to find the object file
-or DWARF object file that contains the second partition.
+unit can be used by a DWARF consumer to find the
+DWARF object file that contains the second partition.
+\subsubsection{Second Partition (Unlinked or in a \texttt{.dwo} File)}
The second partition contains the debugging information that
does not need to be processed by the linker. These sections
may be left in the object files and ignored by the linker
-(that is, not combined and copied to the executable object), or
+(that is, not combined and copied to the executable object file), or
they may be placed by the producer in a separate DWARF object
file. This partition includes the following:
\begin{itemize}
\item
The full compilation unit, in the \dotdebuginfodwo{} section.
-Attributes in debugging information entries may refer to
-machine addresses indirectly using the \DWFORMaddrx{} form,
-and location expressions may do so using the \DWOPaddrx{} and
-\DWOPconstx{} forms. Attributes may refer to range table
-entries with an offset relative to a base offset in the
-range table for the compilation unit.
+\begin{itemize}
+\bbeb
+\item
+Attributes contained in the full compilation unit
+may refer to machine addresses indirectly using the \DWFORMaddrx{}
+form, which accesses the table of addresses specified by the
+\DWATaddrbase{} attribute in the associated skeleton unit.
+Location descriptions may similarly do so using the \DWOPaddrx{} and
+\DWOPconstx{} operations.
+
+\item
+\DWATranges{} attributes contained in the full compilation unit
+may refer to range table entries with a \DWFORMsecoffset{} offset
+relative to the base offset specified by the \DWATrangesbase{}
+attribute in the associated skeleton unit.
+\end{itemize}
\item Separate type units, in the \dotdebuginfodwo{} section.
Except where noted otherwise, all references in this document
to a debugging information section (for example, \dotdebuginfo),
-applies also to the corresponding split DWARF section (for example,
+apply also to the corresponding split DWARF section (for example,
\dotdebuginfodwo).
+\needlines{4}
+Split DWARF object files do not get linked with any other files,
+therefore references between sections must not make use of
+normal object file relocation information. As a result, symbolic
+references within or between sections are not possible.
+
\subsection{Executable Objects}
\label{chap:executableobjects}
The relocated addresses in the debugging information for an
executable object are virtual addresses.
+The sections containing the debugging information are typically
+not loaded as part of the memory image of the program (in ELF
+terminology, the sections are not "allocatable" and are not part
+of a loadable segment). Therefore, the debugging information
+sections described in this document are typically linked as if
+they were each to be loaded at virtual address 0, and references
+within the debugging information always implicitly indicate which
+section a particular offset refers to. (For example, a reference
+of form \DWFORMsecoffset{} may refer to one of several sections,
+depending on the class allowed by a particular attribute of a
+debugging information entry, as shown in
+Table \refersec{tab:attributeencodings}.)
+
+\needlines{6}
\subsection{Shared Object Files}
-\label{datarep:sharedobject Files}
+\label{datarep:sharedobjectfiles}
The relocated
addresses in the debugging information for a shared object file
are offsets relative to the start of the lowest region of
base address at which the object file was attached. This offset
is available in the run\dash time linker\textquoteright s data structures.}
+As with executable objects, the sections containing debugging
+information are typically not loaded as part of the memory image
+of the shared object, and are typically linked as if they were
+each to be loaded at virtual address 0.
+
\subsection{DWARF Package Files}
\label{datarep:dwarfpackagefiles}
\textit{Using \splitDWARFobjectfile{s} allows the developer to compile,
application, and is given the same name with a \doublequote{\texttt{.dwp}}
extension.\addtoindexx{\texttt{.dwp} file extension}}
+\needlines{4}
A DWARF package file is itself an object file, using the
\addtoindexx{package files}
\addtoindexx{DWARF package files}
-same object file format (including byte order) as the
+same object file format (including \byteorder) as the
corresponding application binary. It consists only of a file
-header, section table, a number of DWARF debug information
+header, a section table, a number of DWARF debug information
sections, and two index sections.
-\needlines{5}
+\needlines{10}
Each DWARF package file contains no more than one of each of the
following sections, copied from a set of object or DWARF object
files, and combined, section by section:
The string table section in \dotdebugstrdwo{} contains all the
strings referenced from DWARF attributes using the form
\DWFORMstrx. Any attribute in a compilation unit or a type
-unit using this form will refer to an entry in that unit's
+unit using this form refers to an entry in that unit's
contribution to the \dotdebugstroffsetsdwo{} section, which in turn
-will provide the offset of a string in the \dotdebugstrdwo{}
+provides the offset of a string in the \dotdebugstrdwo{}
section.
The DWARF package file also contains two index sections that
provide a fast way to locate debug information by compilation
-unit signature (\DWATdwoid) for compilation units, or by type
+unit ID
+\bbeb
+for compilation units, or by type
signature for type units:
\begin{alltt}
\dotdebugcuindex
\subsubsection{The Compilation Unit (CU) Index Section}
The \dotdebugcuindex{} section is a hashed lookup table that maps a
-compilation unit signature to a set of contributions in the
+compilation unit ID to a set of contributions in the
various debug information sections. Each contribution is stored
as an offset within its corresponding section and a size.
-Each compilation unit set may contain contributions from the
+Each \compunitset{} may contain contributions from the
following sections:
\begin{alltt}
\dotdebuginfodwo{} (required)
\dotdebugmacrodwo
\end{alltt}
-\textit{Note that a set is not able to represent \dotdebugmacinfo{}
+\textit{Note that a \compunitset{} is not able to represent \dotdebugmacinfo{}
information from \DWARFVersionIV{} or earlier formats.}
\subsubsection{The Type Unit (TU) Index Section}
information sections. Each contribution is stored as an offset
within its corresponding section and a size.
-Each type unit set may contain contributions from the following
+Each \typeunitset{} may contain contributions from the following
sections:
\begin{alltt}
\dotdebuginfodwo{} (required)
\end{alltt}
\subsubsection{Format of the CU and TU Index Sections}
-Both index sections have the same format, and serve to map a
-64-bit signature to a set of contributions to the debug sections.
-Each section begins with a header, followed by a hash table of
+Both index sections have the same format, and serve to map an
+8-byte signature to a set of contributions to the debug sections.
+Each index section begins with a header, followed by a hash table of
signatures, a parallel table of indexes, a table of offsets, and
a table of sizes. The index sections are aligned at 8-byte
-boundaries in the file.
+boundaries in the DWARF package file.
\needlines{6}
The index section header contains the following fields:
\begin{enumerate}[1. ]
\item \texttt{version} (\HFTuhalf) \\
-A version number
+A version number.
\addtoindexx{version number!CU index information}
\addtoindexx{version number!TU index information}
-(see Appendix \refersec{app:dwarfsectionversionnumbersinformative}).
This number is specific to the CU and TU index information
and is independent of the DWARF version number.
The version number is \versiondotdebugcuindex.
\item \textit{padding} (\HFTuhalf) \\
-Reserved to DWARF.
-
-\item \texttt{column\_count} (\HFTuword) \\
-The number of columns in the table of section counts that follows.
-For brevity, the contents of this field is referred to as $C$ below.
+Reserved to DWARF (must be zero).
+\item \texttt{section\_count} (\HFTuword) \\
+The number of entries in the table of section counts that follows.
+For brevity, the contents of this field is referred to as $N$ below.
\item \texttt{unit\_count} (\HFTuword) \\
The number of compilation units or type units in the index.
\hspace{0.3cm}$2^k\ \ >\ \ 3*U/2$
The hash table begins at offset 16 in the section, and consists
-of an array of $S$ 64-bit slots. Each slot contains a 64-bit
+of an array of $S$ 8-byte slots. Each slot contains a 64-bit
signature.
-% (using the byte order of the application binary).
+% (using the \byteorder{} of the application binary).
The parallel table of indices begins immediately after the hash table
(at offset \mbox{$16 + 8 * S$} from the beginning of the section), and
-consists of an array of $S$ 32-bit slots,
+consists of an array of $S$ 4-byte slots,
% (using the byte order of the application binary),
corresponding 1-1 with slots in the hash
table. Each entry in the parallel table contains a row index into
entry and the parallel table entry. While 0 is a valid hash
value, the row index in a used slot will always be non-zero.
-Given a 64-bit compilation unit signature or a type signature $X$,
+Given an 8-byte compilation unit ID or type signature $X$,
an entry in the hash table is located as follows:
\begin{enumerate}[1. ]
-\item Calculate a primary hash $H = X\ \&\ MASK(k)$, where $MASK(k)$ is a
- mask with the low-order $k$ bits all set to 1.
-
-\item Calculate a secondary hash $H' = (((X>>32)\ \&\ MASK(k))\ |\ 1)$.
-
+\item Define $REP(X)$ to be the value of $X$ interpreted as an
+ unsigned 64-bit integer in the target byte order.
+\item Calculate a primary hash $H = REP(X)\ \&\ MASK(k)$, where
+ $MASK(k)$ is a mask with the low-order $k$ bits all set to 1.
+\item Calculate a secondary hash $H' = (((REP(X)>>32)\ \&\ MASK(k))\ |\ 1)$.
\item If the hash table entry at index $H$ matches the signature, use
- that entry. If the hash table entry at index $H$ is unused (all
- zeroes), terminate the search: the signature is not present
- in the table.
-
-\item Let $H = (H + H')\ modulo\ S$. Repeat at Step 3.
+ that entry. If the hash table entry at index $H$ is unused (all
+ zeroes), terminate the search: the signature is not present
+ in the table.
+\item Let $H = (H + H')\ modulo\ S$. Repeat at Step 4.
\end{enumerate}
Because $S > U$, and $H'$ and $S$ are relatively prime, the search is
\needlines{4}
The table of offsets begins immediately following the parallel
table (at offset \mbox{$16 + 12 * S$} from the beginning of the section).
-The table is a two-dimensional array of 32-bit words,
-%(using the byte order of the application binary),
-with $C$ columns and $U + 1$
+The table is a two-dimensional array of 4-byte words,
+%(using the byte order of the application binary),
+with $N$ sections and $U + 1$
rows, in row-major order. Each row in the array is indexed
starting from 0. The first row provides a key to the columns:
each column in this row provides a section identifier for a debug
refer to that section. The section identifiers are shown in
Table \referfol{tab:dwarfpackagefilesectionidentifierencodings}.
+\textit{Not all sections listed in the table need be included.}
+
\needlines{12}
\begin{centering}
\setlength{\extrarowheight}{0.1cm}
\end{longtable}
\end{centering}
-The offsets provided by the CU and TU index sections are the base
-offsets for the contributions made by each CU or TU to the
+The offsets provided by the CU and TU index sections are the
+base offsets for the contributions made by each CU or TU to the
corresponding section in the package file. Each CU and TU header
-contains an \texttt{abbrev\_offset} field, used to find the abbreviations
+contains a \HFNdebugabbrevoffset{} field, used to find the abbreviations
table for that CU or TU within the contribution to the
-\dotdebugabbrevdwo{} section for that CU or TU, and should be
+\dotdebugabbrevdwo{} section for that CU or TU, and are
interpreted as relative to the base offset given in the index
section. Likewise, offsets into \dotdebuglinedwo{} from
-\DWATstmtlist{} attributes should be interpreted as relative to
+\DWATstmtlist{} attributes are interpreted as relative to
the base offset for \dotdebuglinedwo{}, and offsets into other debug
-sections obtained from DWARF attributes should also be
+sections obtained from DWARF attributes are also
interpreted as relative to the corresponding base offset.
The table of sizes begins immediately following the table of
offsets, and provides the sizes of the contributions made by each
CU or TU to the corresponding section in the package file. Like
-the table of offsets, it is a two-dimensional array of 32-bit
-words, with $C$ columns and $U$ rows, in row-major order. Each row in
+the table of offsets, it is a two-dimensional array of 4-byte
+words, with $N$
+entries and $U$ rows, in row-major order. Each row in
the array is indexed starting from 1 (row 0 of the table of
offsets also serves as the key for the table of sizes).
+For an example, see Figure \refersec{fig:examplecuindexsection}.
+
\subsection{DWARF Supplementary Object Files}
\label{datarep:dwarfsupplemetaryobjectfiles}
-In order to minimize the size of debugging information, it is possible
-to move duplicate debug information entries, strings and macro entries from
-several executables or shared object files into a separate
-\addtoindexi{\textit{supplementary object file}}{supplementary object file} by some
-post-linking utility; the moved entries and strings can be then referenced
-from the debugging information of each of those executable or shared object files.
+In order to minimize the size of debugging information,
+it is possible to move duplicate debug information entries,
+strings and macro entries from several executables or shared
+object files into a separate
+\addtoindexi{\textit{supplementary object file}}{supplementary object file}
+by some post-linking utility; the moved entries and strings can
+then be referenced
+from the debugging information of each of those executable or
+shared object files.
+
+This facilitates distribution of separate consolidated debug files in
+a simple manner.
\needlines{4}
A DWARF \addtoindex{supplementary object file} is itself an object file,
using the same object
-file format, byte order, and size as the corresponding application executables
+file format, \byteorder{}, and size as the corresponding application executables
or shared libraries. It consists only of a file header, section table, and
a number of DWARF debug information sections. Both the
\addtoindex{supplementary object file}
\item \texttt{version} (\HFTuhalf) \\
\addttindexx{version}
A 2-byte unsigned integer representing the version of the DWARF
-information for the compilation unit (see Appendix G). The
-value in this field is \versiondotdebugsup.
+information for the compilation unit.
+
+The value in this field is \versiondotdebugsup.
\item \texttt{is\_supplementary} (\HFTubyte) \\
\addttindexx{is\_supplementary}
\item \texttt{sup\_checksum\_len} (unsigned LEB128) \\
\addttindexx{sup\_checksum\_len}
Length of the following \addttindex{sup\_checksum} field;
-his value can be 0 if no checksum is provided.
-
+this value can be 0 if no checksum is provided.
\item \texttt{sup\_checksum} (array of \HFTubyte) \\
\addttindexx{sup\_checksum}
-Some checksum or cryptographic hash function of the \dotdebuginfo{},
-\dotdebugstr{} and \dotdebugmacro{} sections of the
-\addtoindex{supplementary object file}, or some unique identifier
-which the implementation can choose to verify that the supplementary
-section object file matches what the debug information in the executable
-or shared object file expects.
+An implementation-defined integer constant value that
+provides unique identification of the supplementary file.
+
\end{enumerate}
Debug information entries that refer to an executable's or shared
-object's addresses must \emph{not} be moved to supplementary files (the
-addesses will likely not be the same). Similarly,
-entries referenced from within location expressions or using loclistptr
+object's addresses must \emph{not} be moved to supplementary files
+(the addesses will likely not be the same). Similarly,
+entries referenced from within location descriptions or using loclistptr
form attributes must not be moved to a \addtoindex{supplementary object file}.
Executable or shared object file compilation units can use
attributes to refer to them and \DWFORMstrpsup{} form attributes to
refer to strings that are used by debug information of multiple
executables or shared object files. Within the \addtoindex{supplementary object file}'s
-debugging sections, form \DWFORMrefsup{} or \DWFORMstrpsup{} should
-not be used, and all reference forms referring to some other sections
+debugging sections, form \DWFORMrefsup{} or \DWFORMstrpsup{} are
+not used, and all reference forms referring to some other sections
refer to the local sections in the \addtoindex{supplementary object file}.
-In macro information, \DWMACROdefineindirectsup{} or
-\DWMACROundefindirectsup{} opcodes can refer to strings in the
+In macro information, \DWMACROdefinesup{} or
+\DWMACROundefsup{} opcodes can refer to strings in the
\dotdebugstr{} section of the \addtoindex{supplementary object file},
-or \DWMACROtransparentincludesup{}
+or \DWMACROimportsup{}
can refer to \dotdebugmacro{} section entries. Within the
\dotdebugmacro{} section of a \addtoindex{supplementary object file},
-\DWMACROdefineindirect{} and \DWMACROundefindirect{}
-opcodes refer to the local \dotdebugstr{} section, not the one in
+\DWMACROdefinestrp{} and \DWMACROundefstrp{}
+opcodes refer to the local \dotdebugstr{} section in that
+supplementary file, not the one in
the executable or shared object file.
\hypertarget{datarep:xxbitdwffmt}{}
\addtoindexx{32-bit DWARF format}
\addtoindexx{64-bit DWARF format}
-There are two closely related file formats. In the 32-bit DWARF
+There are two closely-related DWARF
+formats. In the 32-bit DWARF
format, all values that represent lengths of DWARF sections
and offsets relative to the beginning of DWARF sections are
-represented using 32-bits. In the 64-bit DWARF format, all
+represented using four bytes. In the 64-bit DWARF format, all
values that represent lengths of DWARF sections and offsets
relative to the beginning of DWARF sections are represented
-using 64-bits. A special convention applies to the initial
+using eight bytes. A special convention applies to the initial
length field of certain DWARF sections, as well as the CIE and
FDE structures, so that the 32-bit and 64-bit DWARF formats
can coexist and be distinguished within a single linked object.
+Except where noted otherwise, all references in this document
+to a debugging information section (for example, \dotdebuginfo),
+apply also to the corresponding split DWARF section (for example,
+\dotdebuginfodwo).
+
The differences between the 32- and 64-bit DWARF formats are
detailed in the following:
\begin{enumerate}[1. ]
\addtoindex{initial length} field (see
\addtoindexx{initial length!encoding}
Section \ref{datarep:initiallengthvalues} on page \pageref{datarep:initiallengthvalues})
-is an unsigned 32-bit integer (which
+is an unsigned 4-byte integer (which
must be less than \xfffffffzero); in the 64-bit DWARF format,
-an \addtoindex{initial length} field is 96 bits in size,
+an \addtoindex{initial length} field is 12 bytes in size,
and has two parts:
\begin{itemize}
-\item The first 32-bits have the value \xffffffff.
+\item The first four bytes have the value \xffffffff.
-\item The following 64-bits contain the actual length
-represented as an unsigned 64-bit integer.
+\item The following eight bytes contain the actual length
+represented as an unsigned 8-byte integer.
\end{itemize}
\textit{This representation allows a DWARF consumer to dynamically
format and to adapt its processing accordingly.}
\needlines{4}
-\item Section offset and section length
-\hypertarget{datarep:sectionoffsetlength}{}
+\item \hypertarget{datarep:sectionoffsetlength}{}
+Section offset and section length
\addtoindexx{section length!use in headers}
fields that occur
\addtoindexx{section offset!use in headers}
in the headers of DWARF sections (other than initial length
\addtoindexx{initial length}
fields) are listed following. In the 32-bit DWARF format these
-are 32-bit unsigned integer values; in the 64-bit DWARF format,
-they are 64-bit unsigned integer values.
+are 4-byte unsigned integer values; in the 64-bit DWARF format,
+they are 8-byte unsigned integer values.
\begin{center}
\begin{tabular}{lll}
\item Within the body of the \dotdebuginfo{}
section, certain forms of attribute value depend on the choice
of DWARF format as follows. For the 32-bit DWARF format,
-the value is a 32-bit unsigned integer; for the 64-bit DWARF
-format, the value is a 64-bit unsigned integer.
+the value is a 4-byte unsigned integer; for the 64-bit DWARF
+format, the value is an 8-byte unsigned integer.
\begin{center}
\begin{tabular}{lp{6cm}}
Form & Role \\ \hline
\needlines{5}
\item Within the body of the \dotdebugline{} section, certain forms of content
description depend on the choice of DWARF format as follows: for the
-32-bit DWARF format, the value is a 32-bit unsigned integer; for the
-64-bit DWARF format, the value is a 64-bit unsigned integer.
+32-bit DWARF format, the value is a 4-byte unsigned integer; for the
+64-bit DWARF format, the value is a 8-byte unsigned integer.
\begin{center}
\begin{tabular}{lp{6cm}}
Form & Role \\ \hline
(TUs), which represents an offset in the
\dotdebuginfo{}
section, depends on the DWARF format as follows: in the
-32-bit DWARF format, each entry is a 32-bit unsigned integer;
-in the 64-bit DWARF format, it is a 64-bit unsigned integer.
+32-bit DWARF format, each entry is a 4-byte unsigned integer;
+in the 64-bit DWARF format, it is a 8-byte unsigned integer.
\needlines{4}
-\item In the body of the \dotdebugstroffsets{} and \dotdebugstroffsetsdwo{}
+\item In the body of the \dotdebugstroffsets{}
sections, the size of entries in the body depend on the DWARF
-format as follows: in the 32-bit DWARF format, entries are 32-bit
+format as follows: in the 32-bit DWARF format, entries are 4-byte
unsigned integer values; in the 64-bit DWARF format, they are
-64-bit unsigned integers.
+8-byte unsigned integers.
\item In the body of the \dotdebugaddr{}, \dotdebugloc{} and \dotdebugranges{}
sections, the contents of the address size fields depends on the
executable libraries can still be used.}
-
\section{Format of Debugging Information}
\label{datarep:formatofdebugginginformation}
section of the object file. Each
such contribution consists of a
\addtoindex{type unit} header
-(see Section \refersec{datarep:typeunitheader})
+(see Section \refersec{datarep:typeunitheaders})
followed by a \DWTAGtypeunit{} entry, together with
its children.
\endlastfoot
\DWUTcompileTARG~\ddag &0x01 \\
\DWUTtypeTARG~\ddag &0x02 \\
-\DWUTpartialTARG~\ddag &0x03 \\ \hline
+\DWUTpartialTARG~\ddag &0x03 \\
+\bb
+\DWUTskeletonTARG~\ddag &0x04 \\
+\DWUTsplitcompileTARG~\ddag &0x05 \\
+\DWUTsplittypeTARG~\ddag &0x06 \\
+\DWUTlouserTARG~\ddag &0x80 \\
+\DWUThiuserTARG~\ddag &\xff
+\eb
+\\
+\hline
\end{longtable}
\end{centering}
+\bb
+\textit{All unit headers in a compilation have the same size.
+Some header types include padding bytes to achieve this.}
+\eb
+
+
\needlines{5}
-\subsubsection{Compilation Unit Header}
+\subsubsection{Compilation and Partial Unit Headers}
\label{datarep:compilationunitheader}
\begin{enumerate}[1. ]
\item \texttt{version} (\HFTuhalf) \\
\addttindexx{version}
+\addtoindexx{version number!compilation unit}
A 2-byte unsigned integer representing the version of the
-DWARF information for the compilation unit \addtoindexx{version number!compilation unit}
-(see Appendix \refersec{app:dwarfsectionversionnumbersinformative}).
+DWARF information for the compilation unit.
+
The value in this field is \versiondotdebuginfo.
+\textit{See also Appendix \refersec{app:dwarfsectionversionnumbersinformative}
+for a summary of all version numbers that apply to DWARF sections.}
+
\needlines{4}
\item \texttt{unit\_type} (\HFTubyte) \\
\addttindexx{unit\_type}
A 1-byte unsigned integer identifying this unit as a compilation unit.
The value of this field is
-\DWUTcompile{} for a {normal compilation} unit or
-\DWUTpartial{} for a {partial compilation} unit
-(see Section \refersec{chap:normalandpartialcompilationunitentries}).
+\DWUTcompile{} for a full compilation unit or
+\DWUTpartial{} for a partial compilation unit
+(see Section \refersec{chap:fullandpartialcompilationunitentries}).
\textit{This field is new in \DWARFVersionV.}
\needlines{4}
-\item \addttindex{debug\_abbrev\_offset} (\livelink{datarep:sectionoffsetlength}{section offset}) \\
-\addttindexx{debug\_abbrev\_offset}
+\item \texttt{address\_size} (\HFTubyte) \\
+\addttindexx{address\_size}
+A 1-byte unsigned integer representing the size in bytes of
+an address on the target architecture. If the system uses
+\addtoindexx{address space!segmented}
+segmented addressing, this value represents the size of the
+offset portion of an address.
+
+\item \HFNdebugabbrevoffset{} (\livelink{datarep:sectionoffsetlength}{section offset}) \\
A
\addtoindexx{section offset!in .debug\_info header}
4-byte or 8-byte unsigned offset into the
in the \sixtyfourbitdwarfformat, this is an 8-byte unsigned length
(see Section \refersec{datarep:32bitand64bitdwarfformats}).
+\bb
+\item \HFNunitpaddingONE{} (8 bytes) \\
+Reserved to DWARF (must be zero).
+
+\needlines{4}
+\item \HFNunitpaddingTWO{} (4 or 8 bytes) \\
+Reserved to DWARF (must be zero). In the \thirtytwobitdwarfformat,
+this is 4 bytes in length; in the \sixtyfourbitdwarfformat this
+is 8 bytes in length.
+\eb
+\end{enumerate}
+
+\needlines{8}
+\bb
+\subsubsection{Skeleton and Split Compilation Unit Headers}
+\label{datarep:skeletonandfullcompilationunitheaders}
+\begin{enumerate}[1. ]
+
+\item \texttt{unit\_length} (\livelink{datarep:initiallengthvalues}{initial length}) \\
+\addttindexx{unit\_length}
+A 4-byte or 12-byte
+\addtoindexx{initial length}
+unsigned integer representing the length
+of the \dotdebuginfo{}
+contribution for that compilation unit,
+not including the length field itself. In the \thirtytwobitdwarfformat,
+this is a 4-byte unsigned integer (which must be less
+than \xfffffffzero); in the \sixtyfourbitdwarfformat, this consists
+of the 4-byte value \wffffffff followed by an 8-byte unsigned
+integer that gives the actual length
+(see Section \refersec{datarep:32bitand64bitdwarfformats}).
+
+\item \texttt{version} (\HFTuhalf) \\
+\addttindexx{version}
+\addtoindexx{version number!compilation unit}
+A 2-byte unsigned integer representing the version of the
+DWARF information for the compilation unit.
+
+The value in this field is \versiondotdebuginfo.
+
+\textit{See also Appendix \refersec{app:dwarfsectionversionnumbersinformative}
+for a summary of all version numbers that apply to DWARF sections.}
+
+\needlines{4}
+\item \texttt{unit\_type} (\HFTubyte) \\
+\addttindexx{unit\_type}
+A 1-byte unsigned integer identifying this unit as a compilation unit.
+The value of this field is
+\DWUTskeleton{} for a skeleton compilation unit or
+\DWUTsplitcompile{} for a split compilation unit
+(see Section \refersec{chap:skeletoncompilationunitentries}).
+
+\textit{This field is new in \DWARFVersionV.}
+
+\needlines{4}
\item \texttt{address\_size} (\HFTubyte) \\
\addttindexx{address\_size}
A 1-byte unsigned integer representing the size in bytes of
segmented addressing, this value represents the size of the
offset portion of an address.
-\end{enumerate}
+\item \HFNdebugabbrevoffset{} (\livelink{datarep:sectionoffsetlength}{section offset}) \\
+A
+\addtoindexx{section offset!in .debug\_info header}
+4-byte or 8-byte unsigned offset into the
+\dotdebugabbrev{}
+section. This offset associates the compilation unit with a
+particular set of debugging information entry abbreviations. In
+the \thirtytwobitdwarfformat, this is a 4-byte unsigned length;
+in the \sixtyfourbitdwarfformat, this is an 8-byte unsigned length
+(see Section \refersec{datarep:32bitand64bitdwarfformats}).
-\subsubsection{Type Unit Header}
-\label{datarep:typeunitheader}
+\needlines{6}
+\item \HFNdwoid{} (unit ID) \\
+An 8-byte implementation-defined integer constant value,
+known as the compilation unit ID, that provides
+unique identification of a skeleton compilation
+unit and its associated split compilation unit in
+the object file named in the \DWATdwoname{} attribute
+of the skeleton compilation.
+\needlines{4}
+\item \HFNunitpaddingTWO{} (4 or 8 bytes) \\
+Reserved to DWARF (must be zero). In the \thirtytwobitdwarfformat,
+this is 4 bytes in length; in the \sixtyfourbitdwarfformat this
+is 8 bytes in length.
+\eb
+\end{enumerate}
+
+\needlines{8}
+\subsubsection{Type Unit Headers}
+\label{datarep:typeunitheaders}
The header for the series of debugging information entries
contributing to the description of a type that has been
placed in its own \addtoindex{type unit}, within the
\dotdebuginfo{} section,
consists of the following information:
\begin{enumerate}[1. ]
-
\item \texttt{unit\_length} (\livelink{datarep:initiallengthvalues}{initial length}) \\
\addttindexx{unit\_length}
A 4-byte or 12-byte unsigned integer
\needlines{4}
\item \texttt{version} (\HFTuhalf) \\
\addttindexx{version}
+\addtoindexx{version number!type unit}
A 2-byte unsigned integer representing the version of the
-DWARF information for the
-type unit\addtoindexx{version number!type unit}
-(see Appendix \refersec{app:dwarfsectionversionnumbersinformative}).
+DWARF information for the type unit.
+
The value in this field is \versiondotdebuginfo.
\item \texttt{unit\_type} (\HFTubyte) \\
\addttindexx{unit\_type}
A 1-byte unsigned integer identifying this unit as a type unit.
-The value of this field is \DWUTtype{} for a type unit
-(see Section \refersec{chap:typeunitentries}).
+The value of this field is \DWUTtype{} for a
+\bb
+non-split
+\eb
+type unit
+(see Section \refersec{chap:typeunitentries})
+\bb
+or \DWUTsplittype{} for a split type unit.
+\eb
\textit{This field is new in \DWARFVersionV.}
-\needlines{4}
-\item \addttindex{debug\_abbrev\_offset} (\livelink{datarep:sectionoffsetlength}{section offset}) \\
-\addttindexx{debug\_abbrev\_offset}
-A
-\addtoindexx{section offset!in .debug\_info header}
-4-byte or 8-byte unsigned offset into the
-\dotdebugabbrev{}
-section. This offset associates the type unit with a
-particular set of debugging information entry abbreviations. In
-the \thirtytwobitdwarfformat, this is a 4-byte unsigned length;
-in the \sixtyfourbitdwarfformat, this is an 8-byte unsigned length
-(see Section \refersec{datarep:32bitand64bitdwarfformats}).
-
\needlines{4}
\item \texttt{address\_size} (\HFTubyte) \\
\addttindexx{address\_size}
segmented addressing, this value represents the size of the
offset portion of an address.
+\needlines{6}
+\item \HFNdebugabbrevoffset{} (\livelink{datarep:sectionoffsetlength}{section offset}) \\
+A
+\addtoindexx{section offset!in .debug\_info header}
+4-byte or 8-byte unsigned offset into the
+\dotdebugabbrev{}
+section. This offset associates the type unit with a
+particular set of debugging information entry abbreviations. In
+the \thirtytwobitdwarfformat, this is a 4-byte unsigned length;
+in the \sixtyfourbitdwarfformat, this is an 8-byte unsigned length
+(see Section \refersec{datarep:32bitand64bitdwarfformats}).
+
\item \texttt{type\_signature} (8-byte unsigned integer) \\
\addttindexx{type\_signature}
\addtoindexx{type signature}
-A 64-bit unique signature (see Section
+A unique 8-byte signature (see Section
\refersec{datarep:typesignaturecomputation})
of the type described in this type
unit.
the primary type contained in this
\addtoindex{type unit} uses this value.}
+\needlines{8}
\item \texttt{type\_offset} (\livelink{datarep:sectionoffsetlength}{section offset}) \\
\addttindexx{type\_offset}
A 4-byte or 8-byte unsigned offset
tag names are given in
Table \refersec{tab:tagencodings}.
+\needlines{6}
\begin{centering}
\setlength{\extrarowheight}{0.1cm}
\begin{longtable}{l|c}
- \hline
\caption{Tag encodings} \label{tab:tagencodings} \\
\hline \bfseries Tag name&\bfseries Value\\ \hline
\endfirsthead
\DWTAGunspecifiedtype&0x3b \\
\DWTAGpartialunit&0x3c \\
\DWTAGimportedunit&0x3d \\
+\bb
+\textit{Reserved}&0x3e\footnote{Code 0x3e is reserved to allow backward compatible support of the
+DW\_TAG\_mutable\_type DIE that was defined (only) in \DWARFVersionIII.}
+\eb
+\\
\DWTAGcondition&\xiiif \\
\DWTAGsharedtype&0x40 \\
\DWTAGtypeunit & 0x41 \\
\DWTAGatomictype~\ddag & 0x47 \\
\DWTAGcallsite~\ddag & 0x48 \\
\DWTAGcallsiteparameter~\ddag & 0x49 \\
+\bb
+\DWTAGskeletonunit~\ddag & 0x4a
+\eb
+\\
\DWTAGlouser&0x4080 \\
\DWTAGhiuser&\xffff \\
\end{longtable}
\end{centering}
+\needlines{8}
Following the tag encoding is a 1-byte value that determines
whether a debugging information entry using this abbreviation
has child entries or not. If the value is
The series of attribute specifications ends with an
entry containing 0 for the name and 0 for the form.
+\needlines{4}
The attribute form
\DWFORMindirectTARG{} is a special case. For
attributes with this form, the attribute value itself in the
\livelink{chap:classreference}{reference}
\addtoindexx{byte size attribute} \\
\textit{Reserved}&0x0c\footnote{Code 0x0c is reserved to allow backward compatible support of the
- DW\_AT\_bit\_offset \mbox{attribute} which was
- defined in \DWARFVersionIII{} and earlier.}
+ DW\_AT\_bit\_offset \mbox{attribute} which was
+ defined in \DWARFVersionIII{} and earlier.}
&\livelink{chap:classconstant}{constant},
\livelink{chap:classexprloc}{exprloc},
\livelink{chap:classreference}{reference}
\addtoindexx{friend attribute} \\
\DWATidentifiercase&0x42&\livelink{chap:classconstant}{constant}
\addtoindexx{identifier case attribute} \\
-\DWATmacroinfo\footnote{\raggedright Not used in \DWARFVersionV.
- Reserved for compatibility and coexistence
- with prior DWARF versions.}
- &0x43&\livelink{chap:classmacptr}{macptr}
+\textit{Reserved}&0x43\footnote{Code 0x43 is reserved to allow backward compatible support of the
+ DW\_AT\_macro\_info \mbox{attribute} which was
+ defined in \DWARFVersionIV{} and earlier.}
+ &\livelink{chap:classmacptr}{macptr}
\addtoindexx{macro information attribute (legacy)!encoding} \\
\DWATnamelistitem&0x44&\livelink{chap:classreference}{reference}
\addtoindexx{name list item attribute} \\
\livelink{chap:classexprloc}{exprloc}
\addtoindexx{rank attribute} \\
\DWATstroffsetsbase~\ddag&0x72&
- \livelinki{chap:classstring}{stroffsetsptr}{stroffsetsptr class}
+ \livelinki{chap:classstroffsetsptr}{stroffsetsptr}{stroffsetsptr class}
\addtoindexx{string offsets base!encoding} \\
\DWATaddrbase~\ddag &0x73&
\livelinki{chap:classaddrptr}{addrptr}{addrptr class}
\DWATrangesbase~\ddag&0x74&
\livelinki{chap:classrangelistptr}{rangelistptr}{rangelistptr class}
\addtoindexx{ranges base!encoding} \\
-\DWATdwoid~\ddag &0x75&
- \livelink{chap:classconstant}{constant}
- \addtoindexx{split DWARF object file id!encoding} \\
+\bb
+\textit{Reserved} &0x75& \textit{Unused}
+\eb
+\\
\DWATdwoname~\ddag &0x76&
\livelink{chap:classstring}{string}
\addtoindexx{split DWARF object file name!encoding} \\
\livelink{chap:classflag}{flag} \\
\DWATrvaluereference~\ddag &0x78&
\livelink{chap:classflag}{flag} \\
-\DWATmacros~\ddag &0x79&\livelink{chap:classmacptr}{macptr}
+\DWATmacros~\ddag &0x79&\livelink{chap:classmacptr}{macptr}
\addtoindexx{macro information attribute} \\
\DWATcallallcalls~\ddag &0x7a&\CLASSflag
\addtoindexx{all calls summary attribute} \\
Table \refersec{tab:attributeencodings}
determines the class of the form.
+\needlines{4}
+In the form descriptions that follow, some forms are said
+to depend in part on the value of an attribute of the
+\definition{\associatedcompilationunit}:
+\begin{itemize}
+\item
+In the case of a \splitDWARFobjectfile{}, the associated
+compilation unit is the skeleton compilation unit corresponding
+to the containing unit.
+\item Otherwise, the associated compilation unit
+is the containing unit.
+\end{itemize}
\needlines{4}
-Each possible form belongs to one or more of the following classes:
+Each possible form belongs to one or more of the following classes
+(see Table \refersec{tab:classesofattributevalue} for a summary of
+the purpose and general usage of each class):
\begin{itemize}
\item \livelinki{chap:classaddress}{address}{address class} \\
index into an array of addresses in the \dotdebugaddr{} section.
The index is relative to the value of the \DWATaddrbase{} attribute
of the associated compilation unit.
+
\end{itemize}
\needlines{5}
\item \livelink{chap:classblock}{block} \\
\livetarg{datarep:classblock}{}
Blocks come in four forms:
-
-\begin{myindentpara}{1cm}
+\begin{itemize}
+\item
A 1-byte length followed by 0 to 255 contiguous information
bytes (\DWFORMblockoneTARG).
-\end{myindentpara}
-\begin{myindentpara}{1cm}
+\item
A 2-byte length followed by 0 to 65,535 contiguous information
bytes (\DWFORMblocktwoTARG).
-\end{myindentpara}
-\begin{myindentpara}{1cm}
+\item
A 4-byte length followed by 0 to 4,294,967,295 contiguous
information bytes (\DWFORMblockfourTARG).
-\end{myindentpara}
-\begin{myindentpara}{1cm}
+\item
An unsigned LEB128\addtoindexx{LEB128!unsigned}
length followed by the number of bytes
specified by the length (\DWFORMblockTARG).
-\end{myindentpara}
+\end{itemize}
In all forms, the length is the number of information bytes
that follow. The information bytes may contain any mixture
\DWFORMdatafourTARG,
\DWFORMdataeightTARG{} and
\DWFORMdatasixteenTARG).
-There are also variable length constant
-data forms encoded using LEB128 numbers (see below).
-Both signed (\DWFORMsdataTARG) and unsigned
-(\DWFORMudataTARG) variable length constants are available.
+There are variable length constant
+data forms encoded using
+signed LEB128 numbers (\DWFORMsdataTARG) and unsigned
+LEB128 numbers (\DWFORMudataTARG).
There is also an implicit constant (\DWFORMimplicitconst),
whose value is provided as part of the abbreviation
declaration.
constant, or anything else. A consumer must use context to
know how to interpret the bits, which if they are target
machine data (such as an integer or floating-point constant)
-will be in target machine byte\dash order.
+will be in target machine \byteorder.
\textit{If one of the \DWFORMdataTARG\textless n\textgreater
forms is used to represent a
or location description
(see Section \refersec{chap:locationdescriptions}).
+\needlines{4}
\item \livelinki{chap:classflag}{flag}{flag class} \\
\livetarg{datarep:classflag}{}
A flag \addtoindexx{flag class}
implicitly (\DWFORMflagpresentTARG).
In the
first case, if the \nolink{flag} has value zero, it indicates the
-absence of the attribute; if the \nolink{flag} has a non\dash zero value,
+absence of the attribute; if the \nolink{flag} has a non-zero value,
it indicates the presence of the attribute. In the second
case, the attribute is implicitly indicated as present, and
no value is encoded in the debugging information entry itself.
+\needlines{4}
\item \livelinki{chap:classlineptr}{lineptr}{lineptr class} \\
\livetarg{datarep:classlineptr}{}
This is an offset into
It consists of an
offset from the beginning of the
\dotdebugranges{} section
-to the beginning of the non\dash contiguous address ranges
+to the beginning of the non-contiguous address ranges
information for the referencing entity.
It is relocatable in
a relocatable object file, and relocated in an executable or
-shared object file. In the \thirtytwobitdwarfformat, this offset
+shared object file.
+However, if a \DWATrangesbase{} attribute applies, the offset
+is relative to the base offset given by \DWATrangesbase.
+In the \thirtytwobitdwarfformat, this offset
is a 4-byte unsigned value; in the 64-bit DWARF
format, it is an 8-byte unsigned value (see Section
\refersec{datarep:32bitand64bitdwarfformats}).
share a common representation, it is not possible for an
attribute to allow more than one of these classes}
-
+\needlines{4}
\begin{itemize}
\item \livelinki{chap:classreference}{reference}{reference class} \\
\livetarg{datarep:classreference}{}
\addtoindex{type unit}. This type of
reference (\DWFORMrefsigeightTARG) is the
\addtoindexx{type signature}
-64-bit type signature
+8-byte type signature
(see Section \refersec{datarep:typesignaturecomputation})
that was computed for the type.
it is an 8-byte unsigned offset
(see Section \refersec{datarep:32bitand64bitdwarfformats}).
-\needlines{4}
+\needlines{6}
\item as an indirect offset into the string table using an
index into a table of offsets contained in the
\dotdebugstroffsets{} section of the object file (\DWFORMstrxTARG).
referencing entity. It is relocatable in
a relocatable object file, and relocated in an executable or
shared object file. In the \thirtytwobitdwarfformat, this offset
-is a 4-byte unsigned value; in the 64-bit DWARF
-format, it is an 8-byte unsigned value (see Section
+is a 4-byte unsigned value; in the \sixtyfourbitdwarfformat,
+it is an 8-byte unsigned value (see Section
\refersec{datarep:32bitand64bitdwarfformats}).
\textit{This class is new in \DWARFVersionV.}
\label{datarep:variablelengthdata}
\addtoindexx{variable length data|see {LEB128}}
Integers may be
-\addtoindexx{Little Endian Base 128|see{LEB128}}
-encoded using \doublequote{Little Endian Base 128}
+\addtoindexx{Little-Endian Base 128|see{LEB128}}
+encoded using \doublequote{Little-Endian Base 128}
\addtoindexx{little-endian encoding|see{endian attribute}}
(LEB128) numbers.
\addtoindexx{LEB128}
small in magnitude.
\textit{This encoding is equally suitable whether the target machine
-architecture represents data in big\dash\ endian or little\dash endian
-order. It is \doublequote{little\dash endian} only in the sense that it
+architecture represents data in big-endian or little-endian
+\byteorder. It is \doublequote{little-endian} only in the sense that it
avoids using space to represent the \doublequote{big} end of an
unsigned integer, when the big end is all zeroes or sign
extension bits.}
that an additional byte follows.
-The encoding for signed, two\textquoteright s complement LEB128
+The encoding for signed, two\textquoteright{s} complement LEB128
(\addtoindex{SLEB128}) \addtoindexx{LEB128!signed, encoding as}
numbers is similar, except that the criterion for discarding
high order bytes is not whether they are zero, but whether
they consist entirely of sign extension bits. Consider the
-32-bit integer -2. The three high level bytes of the number
+4-byte integer -2. The three high level bytes of the number
are sign extension, thus LEB128 would represent it as a single
byte containing the low order 7 bits, with the high order
bit cleared to indicate the end of the byte stream. Note
For a \addtoindex{location list} to be specified, the base address of
\addtoindexx{base address selection entry!in location list}
the corresponding compilation unit must be defined
-(see Section \refersec{chap:normalandpartialcompilationunitentries}).
+(see Section \refersec{chap:fullandpartialcompilationunitentries}).
\subsubsection{Location List Entries in Split Objects}
\label{datarep:locationlistentriesinsplitobjects}
\section{Base Type Attribute Encodings}
\label{datarep:basetypeattributeencodings}
-The encodings of the
-\hypertarget{chap:DWATencodingencodingofbasetype}{}
-constants used in
-\addtoindexx{encoding attribute}
-the
-\DWATencoding{}
-attribute are given in
+The\hypertarget{chap:DWATencodingencodingofbasetype}{}
+encodings of the constants used in the
+\DWATencodingDEFN{} attribute\addtoindexx{encoding attribute}
+are given in
Table \refersec{tab:basetypeencodingvalues}
\begin{centering}
\end{longtable}
\end{centering}
-\needlines{4}
+\vspace*{1cm}
The encodings of the constants used in the
\DWATdecimalsign{} attribute
are given in
\endfirsthead
\bfseries Decimal sign code name&\bfseries Value\\ \hline
\endhead
- \hline \emph{Continued on next page}
-\endfoot
+% \hline \emph{Continued on next page}
+%\endfoot
\hline
\endlastfoot
-
-\DWDSunsigned{} & 0x01 \\
-\DWDSleadingoverpunch{} & 0x02 \\
+\DWDSunsigned{} & 0x01 \\
+\DWDSleadingoverpunch{} & 0x02 \\
\DWDStrailingoverpunch{} & 0x03 \\
-\DWDSleadingseparate{} & 0x04 \\
-\DWDStrailingseparate{} & 0x05 \\
-
+\DWDSleadingseparate{} & 0x04 \\
+\DWDStrailingseparate{} & 0x05 \\
\end{longtable}
\end{centering}
\DWLANGCeightynine &0x0001 &0 \addtoindexx{C:1989 (ISO)} \\
\DWLANGC{} &0x0002 &0 \addtoindexx{C!non-standard} \\
\DWLANGAdaeightythree{} \dag &0x0003 &1 \addtoindexx{Ada:1983 (ISO)} \\
-\DWLANGCplusplus{} &0x0004 &0 \addtoindexx{C++:1998 (ISO)} \\
+\DWLANGCplusplus{} &0x0004 &0 \addtoindexx{C++98 (ISO)} \\
\DWLANGCobolseventyfour{} \dag &0x0005 &1 \addtoindexx{COBOL:1974 (ISO)} \\
\DWLANGCoboleightyfive{} \dag &0x0006 &1 \addtoindexx{COBOL:1985 (ISO)} \\
\DWLANGFortranseventyseven &0x0007 &1 \addtoindexx{FORTRAN:1977 (ISO)} \\
\DWLANGGo{} \dag \ddag &0x0016 &0 \addtoindexx{Go}\\
\DWLANGModulathree{} \dag \ddag &0x0017 &1 \addtoindexx{Modula-3}\\
\DWLANGHaskell{} \dag \ddag &0x0018 &0 \addtoindexx{Haskell}\\
-\DWLANGCpluspluszerothree{} \ddag &0x0019 &0 \addtoindexx{C++:2003 (ISO)}\\
-\DWLANGCpluspluseleven{} \ddag &0x001a &0 \addtoindexx{C++:2011 (ISO)}\\
+\DWLANGCpluspluszerothree{} \ddag &0x0019 &0 \addtoindexx{C++03 (ISO)}\\
+\DWLANGCpluspluseleven{} \ddag &0x001a &0 \addtoindexx{C++11 (ISO)} \\
\DWLANGOCaml{} \ddag &0x001b &0 \addtoindexx{OCaml}\\
\DWLANGRust{} \ddag &0x001c &0 \addtoindexx{Rust}\\
\DWLANGCeleven{} \ddag &0x001d &0 \addtoindexx{C:2011 (ISO)}\\
\DWLANGSwift{} \ddag &0x001e &0 \addtoindexx{Swift} \\
\DWLANGJulia{} \ddag &0x001f &1 \addtoindexx{Julia} \\
\DWLANGDylan{} \ddag &0x0020 &0 \addtoindexx{Dylan} \\
-\DWLANGCplusplusfourteen{}~\ddag &0x0021 &0 \addtoindexx{C++:2014 (ISO)} \\
+\DWLANGCplusplusfourteen{}~\ddag &0x0021 &0 \addtoindexx{C++14 (ISO)} \\
\DWLANGFortranzerothree{}~\ddag &0x0022 &1 \addtoindexx{Fortran:2004 (ISO)} \\
\DWLANGFortranzeroeight{}~\ddag &0x0023 &1 \addtoindexx{Fortran:2010 (ISO)} \\
+\bb
+\DWLANGRenderScript{}~\ddag &0x0024 &0 \addtoindexx{RenderScript Kernel Language}
+\eb
+\\
\DWLANGlouser{} &0x8000 & \\
\DWLANGhiuser{} &\xffff & \\
\needlines{6}
\section{Name Index Table}
\label{datarep:nameindextable}
-Each name index table in the \dotdebugnames{} section
-begins with a header consisting of:
-\begin{enumerate}[1. ]
-\item \texttt{unit\_length} (\livelink{datarep:initiallengthvalues}{initial length}) \\
-\addttindexx{unit\_length}
-A 4-byte or 12-byte initial length field that
-contains the size in bytes of this contribution to the \dotdebugnames{}
-section, not including the length field itself
-(see Section \refersec{datarep:initiallengthvalues}).
-
-\item \texttt{version} (\HFTuhalf) \\
-A 2-byte version number\addtoindexx{version number!name index table}
-(see Appendix \refersec{app:dwarfsectionversionnumbersinformative}).
-This number is specific to the name index table and is
-independent of the DWARF version number.
-
-The value in this field is \versiondotdebugnames.
-
-\item padding (\HFTuhalf) \\
-
-\item \texttt{comp\_unit\_count} (\HFTuword) \\
-The number of CUs in the CU list.
-
-\item \texttt{local\_type\_unit\_count} (\HFTuword) \\
-The number of TUs in the first TU list.
-
-\item \texttt{foreign\_type\_unit\_count} (\HFTuword) \\
-The number of TUs in the second TU list.
-
-\item \texttt{bucket\_count} (\HFTuword) \\
-The number of hash buckets in the hash lookup table.
-If there is no hash lookup table, this field contains 0.
-
-\item \texttt{name\_count} (\HFTuword) \\
-The number of unique names in the index.
-
-\item \texttt{abbrev\_table\_size} (\HFTuword) \\
-The size in bytes of the abbreviations table.
-
-\item \texttt{augmentation\_string\_size} (\HFTuword) \\
-The size in bytes of the augmentation string. This value should be
-rounded up to a multiple of 4.
-
-\item \texttt{augmentation\_string} (\HFTaugstring) \\
-A vendor-specific augmentation string, which provides additional
-information about the contents of this index. If provided, the string
-should begin with a 4-character vendor ID. The remainder of the
-string is meant to be read by a cooperating consumer, and its
-contents and interpretation are not specified here. The
-string should be padded with null characters to a multiple of
-four bytes in length.
-
-\end{enumerate}
+The \addtoindexi{version number}{version number!name index table}
+in the name index table header is \versiondotdebugnames{}.
The name index attributes and their encodings are listed in Table \referfol{datarep:indexattributeencodings}.
\setlength{\extrarowheight}{0.1cm}
\begin{longtable}{l|c|l}
\caption{Name index attribute encodings} \label{datarep:indexattributeencodings}\\
- \hline \bfseries Attribute name&\bfseries Value &\bfseries Form/Class \\ \hline
+ \hline \bfseries Attribute name &\bfseries Value &\bfseries Form/Class \\ \hline
\endfirsthead
- \bfseries Attribute name&\bfseries Value &\bfseries Form/Class \\ \hline
+ \bfseries Attribute name &\bfseries Value &\bfseries Form/Class \\ \hline
\endhead
\hline \emph{Continued on next page}
\endfoot
\hline
- \ddag \ \textit{New in \DWARFVersionV}
+ \ddag~\textit{New in \DWARFVersionV}
\endlastfoot
\DWIDXcompileunit~\ddag & 1 & \CLASSconstant \\
\DWIDXtypeunit~\ddag & 2 & \CLASSconstant \\
\item version (\HFTuhalf) \\
A 2-byte version identifier representing the version of the
-DWARF information for the address range table
-(see Appendix \refersec{app:dwarfsectionversionnumbersinformative}).
+DWARF information for the address range table.
This value in this field \addtoindexx{version number!address range table} is 2.
\label{datarep:linenumberinformation}
The \addtoindexi{version number}{version number!line number information}
-in the line number program header is \versiondotdebugline{}
-(see Appendix \refersec{app:dwarfsectionversionnumbersinformative}).
+in the line number program header is \versiondotdebugline{}.
The boolean values \doublequote{true} and \doublequote{false}
used by the line number information program are encoded
\section{Macro Information}
\label{datarep:macroinformation}
The \addtoindexi{version number}{version number!macro information}
-in the macro information header is \versiondotdebugmacro{}
-(see Appendix \refersec{app:dwarfsectionversionnumbersinformative}).
+in the macro information header is \versiondotdebugmacro{}.
The source line numbers and source file indices encoded in the
macro information section are represented as
\hline \ddag~\textit{New in DWARF Version 5}
\endlastfoot
-\DWMACROdefine~\ddag &0x01 \\
-\DWMACROundef~\ddag &0x02 \\
-\DWMACROstartfile~\ddag &0x03 \\
-\DWMACROendfile~\ddag &0x04 \\
-\DWMACROdefineindirect~\ddag &0x05 \\
-\DWMACROundefindirect~\ddag &0x06 \\
-\DWMACROtransparentinclude~\ddag &0x07 \\
-\DWMACROdefineindirectsup~\ddag &0x08 \\
-\DWMACROundefindirectsup~\ddag &0x09 \\
-\DWMACROtransparentincludesup~\ddag&0x0a \\
-\DWMACROdefineindirectx~\ddag &0x0b \\
-\DWMACROundefindirectx~\ddag &0x0c \\
-\DWMACROlouser~\ddag &0xe0 \\
-\DWMACROhiuser~\ddag &\xff \\
+\DWMACROdefine~\ddag &0x01 \\
+\DWMACROundef~\ddag &0x02 \\
+\DWMACROstartfile~\ddag &0x03 \\
+\DWMACROendfile~\ddag &0x04 \\
+\DWMACROdefinestrp~\ddag &0x05 \\
+\DWMACROundefstrp~\ddag &0x06 \\
+\DWMACROimport~\ddag &0x07 \\
+\DWMACROdefinesup~\ddag &0x08 \\
+\DWMACROundefsup~\ddag &0x09 \\
+\DWMACROimportsup~\ddag &0x0a \\
+\DWMACROdefinestrx~\ddag &0x0b \\
+\DWMACROundefstrx~\ddag &0x0c \\
+\DWMACROlouser~\ddag &0xe0 \\
+\DWMACROhiuser~\ddag &\xff \\
\end{longtable}
\end{centering}
value is \xffffffffffffffff.
The value of the CIE \addtoindexi{version number}{version number!call frame information}
-is 4 (see Appendix \refersec{app:dwarfsectionversionnumbersinformative}).
+is \versiondotdebugframe.
Call frame instructions are encoded in one or more bytes. The
primary opcode is encoded in the high order two bits of
For a \addtoindex{range list} to be specified, the base address of the
\addtoindexx{base address selection entry!in range list}
corresponding compilation unit must be defined
-(see Section \refersec{chap:normalandpartialcompilationunitentries}).
+(see Section \refersec{chap:fullandpartialcompilationunitentries}).
\needlines{6}
\section{String Offsets Table}
%\needlines{4}
\item \texttt{version} (\HFTuhalf) \\
+\addtoindexx{version number!string offsets table}
A 2-byte version identifier containing the value
-\versiondotdebugstroffsets{}
-(see Appendix \refersec{app:dwarfsectionversionnumbersinformative}).
+\versiondotdebugstroffsets{}.
-\item \texttt{padding} (\HFTuhalf) \\
+\item \textit{padding} (\HFTuhalf) \\
+Reserved to DWARF (must be zero).
\end{enumerate}
This header is followed by a series of string table offsets
\needlines{4}
\item \texttt{version} (\HFTuhalf) \\
+\addtoindexx{version number!address table}
A 2-byte version identifier containing the value
-\versiondotdebugaddr{}
-(see Appendix \refersec{app:dwarfsectionversionnumbersinformative}).
+\versiondotdebugaddr{}.
\needlines{4}
\item \texttt{address\_size} (\HFTubyte) \\
\needlines{4}
\item \texttt{version} (\HFTuhalf) \\
+\addtoindexx{version number!range list table}
A 2-byte version identifier containing the value
-\versiondotdebugranges{}
-(see Appendix \refersec{app:dwarfsectionversionnumbersinformative}).
+\versiondotdebugranges{}.
\needlines{4}
\item \texttt{address\_size} (\HFTubyte) \\
following the header. The entries are referenced by a byte
offset relative to this base address.
-
+\needlines{12}
\section{Location List Table}
\label{datarep:locationlisttable}
Each set of entries in the location list table contained in the
\needlines{4}
\item \texttt{version} (\HFTuhalf) \\
+\addtoindexx{version number!location list table}
A 2-byte version identifier containing the value
-\versiondotdebugloc{}
-(see Appendix \refersec{app:dwarfsectionversionnumbersinformative}).
+\versiondotdebugloc{}.
\needlines{5}
\item \texttt{address\_size} (\HFTubyte) \\
\section{Type Signature Computation}
\label{datarep:typesignaturecomputation}
-A type signature is computed only by the DWARF producer;
-\addtoindexx{type signature!computation}
-it is used by a DWARF consumer to resolve type references to
-the type definitions that are contained in
-\addtoindexx{type unit}
-type units.
+A \addtoindex{type signature} is used by a DWARF consumer
+to resolve type references to the type definitions that
+are contained in \addtoindex{type unit}s (see Section
+\refersec{chap:typeunitentries}).
+
+\textit{A type signature is computed only by a DWARF producer;
+\addtoindexx{type signature!computation} a consumer need
+\bb
+only
+\eb
+compare two type signatures to check for equality.}
\needlines{4}
The type signature for a type T0 is formed from the
\MDfive{}\footnote{\livetarg{def:MDfive}{MD5} Message Digest Algorithm,
R.L. Rivest, RFC 1321, April 1992}
-hash of a flattened description of the type. The flattened
+digest of a flattened description of the type. The flattened
description of the type is a byte sequence derived from the
DWARF encoding of the type as follows:
\begin{enumerate}[1. ]
\DWATdiscrlist,
\DWATdiscrvalue,
\DWATencoding,
-\DWATenumclass,
\DWATendianity,
+\DWATenumclass,
\DWATexplicit,
\DWATisoptional,
\DWATlocation,
If an implementation defines any vendor-specific attributes,
any such attributes that are essential to the definition of
-the type should also be included at the end of the above list,
+the type are also included at the end of the above list,
in their own alphabetical suborder.
An attribute that refers to another type entry T is processed
-as follows: (a) If T is in the list V at some V[x], use the
+as follows:
+\begin{enumerate}[ a)]
+\item
+\bb
+If
+\eb
+T is in the list V at some V[x], use the
letter 'R' as the marker and use the unsigned LEB128\addtoindexx{LEB128!unsigned}
-encoding of x as the attribute value; otherwise, (b) use the letter 'T'
+encoding of x as the attribute value.
+
+\item
+\bb
+Otherwise, append type T to the list V, then
+\eb
+use the letter 'T'
as the marker, process the type T recursively by performing
Steps 2 through 7, and use the result as the attribute value.
+\end{enumerate}
+\needlines{4}
Other attribute values use the letter 'A' as the marker, and
the value consists of the form code (encoded as an unsigned
LEB128 value) followed by the encoding of the value according
\DWFORMexprloc,
and \DWFORMblock.
-\needlines{4}
\item If the tag in Step 3 is one of \DWTAGpointertype,
\DWTAGreferencetype,
\DWTAGrvaluereferencetype,
name to be used is the ABI-specific name of the subprogram
(for example, the mangled linker name).
-
+\needlines{6}
\item If the tag in Step 3 is not one of \DWTAGpointertype,
\DWTAGreferencetype,
\DWTAGrvaluereferencetype,
Appendix \refersec{app:typesignaturecomputationgrammar}.
}
-\textit{An attribute that refers to another type entry should
-be recursively processed or replaced with the name of the
+\textit{An attribute that refers to another type entry is
+recursively processed or replaced with the name of the
referent (in Step 4, 5 or 6). If neither treatment applies to
an attribute that references another type entry, the entry
-that contains that attribute should not be considered for a
+that contains that attribute is not suitable for a
separate \addtoindex{type unit}.}
\textit{If a debugging information entry contains an attribute from
the list above that would require an unsupported form, that
-entry should not be considered for a separate
+entry is not suitable for a separate
\addtoindex{type unit}.}
-\textit{A type should be considered for a separate
+\textit{A type is suitable for a separate
\addtoindex{type unit} only
if all of the type entries that it contains or refers to in
-Steps 6 and 7 can themselves each be considered for a separate
+Steps 6 and 7 are themselves suitable for a separate
\addtoindex{type unit}.}
\needlines{4}
expression when possible.)
Once the string S has been formed from the DWARF encoding,
-an \MDfive{} hash is computed for the string and the
-least significant 64 bits are taken as the type signature.
+an 16-byte \MDfive{} digest is computed for the string and the
+last eight bytes are taken as the type signature.
\textit{The string S is intended to be a flattened representation of
the type that uniquely identifies that type (that is, a different
type is highly unlikely to produce the same string).}
\needlines{6}
-\textit{A debugging information entry should not be placed in a
+\textit{A debugging information entry is not be placed in a
separate \addtoindex{type unit}
if any of the following apply:}
\begin{itemize}
\item \textit{The entry has an attribute whose value is a location
-expression, and the location expression contains a reference to
+description, and the location description
+contains a reference to
another debugging information entry (for example, a \DWOPcallref{}
operator), as it is unlikely that the entry will remain
identical across compilation units.}
\DWATdeclcolumn{} attributes are not included because they
may vary from one source file to the next, and would prevent
two otherwise identical type declarations from producing the
-same \MDfive{} hash.}
+same \MDfive{} digest.}
\item \textit{The \DWATobjectpointer{} attribute is not included
because the information it provides is not necessary for the
encoding the type to allow for cases where a complete definition
of the type might not be available in all compilation units.}
-\needlines{4}
+%\needlines{4}
\textit{If a type definition contains the definition of a member function,
it cannot be moved as is into a type unit, because the member function
contains attributes that are unique to that compilation unit.
-Such a type definition can be moved to a type unit by rewriting the DIE tree,
+Such a type definition can be moved to a type unit by rewriting the
+debugging information entry tree,
moving the member function declaration into a separate declaration tree,
and replacing the function definition in the type with a non-defining
declaration of the function (as if the function had been defined out of
line).}
-An example that illustrates the computation of an \MDfive{} hash may be found in
+An example that illustrates the computation of an \MDfive{} digest may be found in
Appendix \refersec{app:usingtypeunits}.
\section{Name Table Hash Function}
The hash function used for hashing name strings in the accelerated
access name index table (see Section \refersec{chap:acceleratedaccess})
is defined in \addtoindex{C} as shown in
-Figure \referfol{fig:nametablehashfunctiondefinition}.\footnote{
-This hash function is sometimes informally known as the
-"\addtoindex{TJB hash function}" or the "\addtoindex{Berstein hash function}"
+Figure \referfol{fig:nametablehashfunctiondefinition}.\footnoteRR{
+This hash function is sometimes known as the
+"\addtoindex{Bernstein hash function}" or the
+"\addtoindex{DJB hash function}"
(see, for example,
\hrefself{http://en.wikipedia.org/wiki/List\_of\_hash\_functions} or
\hrefself{http://stackoverflow.com/questions/10696223/reason-for-5381-number-in-djb-hash-function)}.}
-\begin{figure}[here]
+\begin{figure}[ht]
\begin{lstlisting}
-unsigned long \* must be a 32-bit integer type *\
+uint32_t /* must be a 32-bit integer type */
hash(unsigned char *str)
{
- unsigned long hash = 5381;
+ uint32_t hash = 5381;
int c;
while (c = *str++)
DWARF Git Projects / dwarf-doc.git / blobdiff