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This is stabs.info, produced by Makeinfo version 3.12f from
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This is stabs.info, produced by makeinfo version 4.0 from
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./stabs.texinfo.
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./stabs.texinfo.
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START-INFO-DIR-ENTRY
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START-INFO-DIR-ENTRY
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* Stabs: (stabs). The "stabs" debugging information format.
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* Stabs: (stabs). The "stabs" debugging information format.
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END-INFO-DIR-ENTRY
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END-INFO-DIR-ENTRY
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the University of California at Berkeley, for the `pdx' Pascal
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the University of California at Berkeley, for the `pdx' Pascal
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debugger; the format has spread widely since then.
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debugger; the format has spread widely since then.
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This document is one of the few published sources of documentation on
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This document is one of the few published sources of documentation on
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stabs. It is believed to be comprehensive for stabs used by C. The
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stabs. It is believed to be comprehensive for stabs used by C. The
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lists of symbol descriptors (*note Symbol Descriptors::.) and type
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lists of symbol descriptors (*note Symbol Descriptors::) and type
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descriptors (*note Type Descriptors::.) are believed to be completely
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descriptors (*note Type Descriptors::) are believed to be completely
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comprehensive. Stabs for COBOL-specific features and for variant
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comprehensive. Stabs for COBOL-specific features and for variant
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records (used by Pascal and Modula-2) are poorly documented here.
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records (used by Pascal and Modula-2) are poorly documented here.
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Other sources of information on stabs are `Dbx and Dbxtool
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Other sources of information on stabs are `Dbx and Dbxtool
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Interfaces', 2nd edition, by Sun, 1988, and `AIX Version 3.2 Files
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Interfaces', 2nd edition, by Sun, 1988, and `AIX Version 3.2 Files
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The overall format of the string field for most stab types is:
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The overall format of the string field for most stab types is:
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"NAME:SYMBOL-DESCRIPTOR TYPE-INFORMATION"
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"NAME:SYMBOL-DESCRIPTOR TYPE-INFORMATION"
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NAME is the name of the symbol represented by the stab; it can
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NAME is the name of the symbol represented by the stab; it can
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contain a pair of colons (*note Nested Symbols::.). NAME can be
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contain a pair of colons (*note Nested Symbols::). NAME can be
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omitted, which means the stab represents an unnamed object. For
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omitted, which means the stab represents an unnamed object. For
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example, `:t10=*2' defines type 10 as a pointer to type 2, but does not
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example, `:t10=*2' defines type 10 as a pointer to type 2, but does not
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give the type a name. Omitting the NAME field is supported by AIX dbx
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give the type a name. Omitting the NAME field is supported by AIX dbx
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and GDB after about version 4.8, but not other debuggers. GCC
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and GDB after about version 4.8, but not other debuggers. GCC
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sometimes uses a single space as the name instead of omitting the name
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sometimes uses a single space as the name instead of omitting the name
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Line 208... |
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There is an AIX extension for type attributes. Following the `='
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There is an AIX extension for type attributes. Following the `='
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are any number of type attributes. Each one starts with `@' and ends
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are any number of type attributes. Each one starts with `@' and ends
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with `;'. Debuggers, including AIX's dbx and GDB 4.10, skip any type
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with `;'. Debuggers, including AIX's dbx and GDB 4.10, skip any type
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attributes they do not recognize. GDB 4.9 and other versions of dbx
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attributes they do not recognize. GDB 4.9 and other versions of dbx
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may not do this. Because of a conflict with C++ (*note Cplusplus::.),
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may not do this. Because of a conflict with C++ (*note Cplusplus::),
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new attributes should not be defined which begin with a digit, `(', or
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new attributes should not be defined which begin with a digit, `(', or
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`-'; GDB may be unable to distinguish those from the C++ type
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`-'; GDB may be unable to distinguish those from the C++ type
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descriptor `@'. The attributes are:
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descriptor `@'. The attributes are:
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`aBOUNDARY'
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`aBOUNDARY'
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Line 469... |
============
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============
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An `N_SLINE' symbol represents the start of a source line. The desc
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An `N_SLINE' symbol represents the start of a source line. The desc
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field contains the line number and the value contains the code address
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field contains the line number and the value contains the code address
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for the start of that source line. On most machines the address is
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for the start of that source line. On most machines the address is
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absolute; for stabs in sections (*note Stab Sections::.), it is
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absolute; for stabs in sections (*note Stab Sections::), it is relative
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relative to the function in which the `N_SLINE' symbol occurs.
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to the function in which the `N_SLINE' symbol occurs.
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GNU documents `N_DSLINE' and `N_BSLINE' symbols for line numbers in
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GNU documents `N_DSLINE' and `N_BSLINE' symbols for line numbers in
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the data or bss segments, respectively. They are identical to
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the data or bss segments, respectively. They are identical to
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`N_SLINE' but are relocated differently by the linker. They were
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`N_SLINE' but are relocated differently by the linker. They were
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intended to be used to describe the source location of a variable
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intended to be used to describe the source location of a variable
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| Line 490... |
Line 490... |
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XCOFF does not use stabs for line numbers. Instead, it uses COFF
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XCOFF does not use stabs for line numbers. Instead, it uses COFF
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line numbers (which are outside the scope of this document). Standard
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line numbers (which are outside the scope of this document). Standard
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COFF line numbers cannot deal with include files, but in XCOFF this is
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COFF line numbers cannot deal with include files, but in XCOFF this is
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fixed with the `C_BINCL' method of marking include files (*note Include
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fixed with the `C_BINCL' method of marking include files (*note Include
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Files::.).
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Files::).
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File: stabs.info, Node: Procedures, Next: Nested Procedures, Prev: Line Numbers, Up: Program Structure
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File: stabs.info, Node: Procedures, Next: Nested Procedures, Prev: Line Numbers, Up: Program Structure
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Procedures
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Procedures
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Line 544... |
are being passed, whose types and number may vary (`...' in ANSI C).
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are being passed, whose types and number may vary (`...' in ANSI C).
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GDB has tolerated this extension (parsed the syntax, if not necessarily
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GDB has tolerated this extension (parsed the syntax, if not necessarily
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used the information) since at least version 4.8; I don't know whether
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used the information) since at least version 4.8; I don't know whether
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all versions of dbx tolerate it. The argument types given here are not
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all versions of dbx tolerate it. The argument types given here are not
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redundant with the symbols for the formal parameters (*note
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redundant with the symbols for the formal parameters (*note
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Parameters::.); they are the types of the arguments as they are passed,
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Parameters::); they are the types of the arguments as they are passed,
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before any conversions might take place. For example, if a C function
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before any conversions might take place. For example, if a C function
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which is declared without a prototype takes a `float' argument, the
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which is declared without a prototype takes a `float' argument, the
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value is passed as a `double' but then converted to a `float'.
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value is passed as a `double' but then converted to a `float'.
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Debuggers need to use the types given in the arguments when printing
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Debuggers need to use the types given in the arguments when printing
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values, but when calling the function they need to use the types given
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values, but when calling the function they need to use the types given
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Line 561... |
where the function is defined was also compiled with debugging symbols.
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where the function is defined was also compiled with debugging symbols.
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As an extension the Solaris compiler uses symbol descriptor `P'
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As an extension the Solaris compiler uses symbol descriptor `P'
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followed by the return type of the function, followed by the arguments,
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followed by the return type of the function, followed by the arguments,
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each preceded by `;', as in a stab with symbol descriptor `f' or `F'.
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each preceded by `;', as in a stab with symbol descriptor `f' or `F'.
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This use of symbol descriptor `P' can be distinguished from its use for
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This use of symbol descriptor `P' can be distinguished from its use for
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register parameters (*note Register Parameters::.) by the fact that it
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register parameters (*note Register Parameters::) by the fact that it
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has symbol type `N_FUN'.
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has symbol type `N_FUN'.
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The AIX documentation also defines symbol descriptor `J' as an
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The AIX documentation also defines symbol descriptor `J' as an
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internal function. I assume this means a function nested within another
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internal function. I assume this means a function nested within another
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function. It also says symbol descriptor `m' is a module in Modula-2
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function. It also says symbol descriptor `m' is a module in Modula-2
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Line 651... |
machine, and Sun `acc' compilers, put the variables after the `N_LBRAC'
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machine, and Sun `acc' compilers, put the variables after the `N_LBRAC'
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symbol. The values of the `N_LBRAC' and `N_RBRAC' symbols are the
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symbol. The values of the `N_LBRAC' and `N_RBRAC' symbols are the
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start and end addresses of the code of the block, respectively. For
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start and end addresses of the code of the block, respectively. For
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most machines, they are relative to the starting address of this source
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most machines, they are relative to the starting address of this source
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file. For the Gould NP1, they are absolute. For stabs in sections
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file. For the Gould NP1, they are absolute. For stabs in sections
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(*note Stab Sections::.), they are relative to the function in which
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(*note Stab Sections::), they are relative to the function in which
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they occur.
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they occur.
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The `N_LBRAC' and `N_RBRAC' stabs that describe the block scope of a
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The `N_LBRAC' and `N_RBRAC' stabs that describe the block scope of a
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procedure are located after the `N_FUN' stab that represents the
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procedure are located after the `N_FUN' stab that represents the
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procedure itself.
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procedure itself.
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Line 703... |
Character constant. VALUE is the numeric value of the constant.
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Character constant. VALUE is the numeric value of the constant.
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`e TYPE-INFORMATION , VALUE'
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`e TYPE-INFORMATION , VALUE'
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Constant whose value can be represented as integral.
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Constant whose value can be represented as integral.
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TYPE-INFORMATION is the type of the constant, as it would appear
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TYPE-INFORMATION is the type of the constant, as it would appear
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after a symbol descriptor (*note String Field::.). VALUE is the
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after a symbol descriptor (*note String Field::). VALUE is the
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numeric value of the constant. GDB 4.9 does not actually get the
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numeric value of the constant. GDB 4.9 does not actually get the
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right value if VALUE does not fit in a host `int', but it does not
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right value if VALUE does not fit in a host `int', but it does not
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do anything violent, and future debuggers could be extended to
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do anything violent, and future debuggers could be extended to
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accept integers of any size (whether unsigned or not). This
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accept integers of any size (whether unsigned or not). This
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constant type is usually documented as being only for enumeration
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constant type is usually documented as being only for enumeration
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| Line 732... |
Line 732... |
`\'' or `"' (in which case `"' characters within the string are
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`\'' or `"' (in which case `"' characters within the string are
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represented as `\"').
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represented as `\"').
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`S TYPE-INFORMATION , ELEMENTS , BITS , PATTERN'
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`S TYPE-INFORMATION , ELEMENTS , BITS , PATTERN'
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Set constant. TYPE-INFORMATION is the type of the constant, as it
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Set constant. TYPE-INFORMATION is the type of the constant, as it
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would appear after a symbol descriptor (*note String Field::.).
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would appear after a symbol descriptor (*note String Field::).
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ELEMENTS is the number of elements in the set (does this means how
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ELEMENTS is the number of elements in the set (does this means how
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many bits of PATTERN are actually used, which would be redundant
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many bits of PATTERN are actually used, which would be redundant
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with the type, or perhaps the number of bits set in PATTERN? I
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with the type, or perhaps the number of bits set in PATTERN? I
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don't get it), BITS is the number of bits in the constant (meaning
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don't get it), BITS is the number of bits in the constant (meaning
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it specifies the length of PATTERN, I think), and PATTERN is a
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it specifies the length of PATTERN, I think), and PATTERN is a
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Line 780... |
==========================================
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==========================================
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If a variable's scope is local to a function and its lifetime is
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If a variable's scope is local to a function and its lifetime is
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only as long as that function executes (C calls such variables
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only as long as that function executes (C calls such variables
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"automatic"), it can be allocated in a register (*note Register
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"automatic"), it can be allocated in a register (*note Register
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Variables::.) or on the stack.
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Variables::) or on the stack.
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Each variable allocated on the stack has a stab with the symbol
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Each variable allocated on the stack has a stab with the symbol
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descriptor omitted. Since type information should begin with a digit,
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descriptor omitted. Since type information should begin with a digit,
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`-', or `(', only those characters precluded from being used for symbol
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`-', or `(', only those characters precluded from being used for symbol
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descriptors. However, the Acorn RISC machine (ARM) is said to get this
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descriptors. However, the Acorn RISC machine (ARM) is said to get this
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Line 824... |
================
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================
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A variable whose scope is not specific to just one source file is
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A variable whose scope is not specific to just one source file is
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represented by the `G' symbol descriptor. These stabs use the `N_GSYM'
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represented by the `G' symbol descriptor. These stabs use the `N_GSYM'
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stab type (C_GSYM for XCOFF). The type information for the stab (*note
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stab type (C_GSYM for XCOFF). The type information for the stab (*note
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String Field::.) gives the type of the variable.
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String Field::) gives the type of the variable.
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For example, the following source code:
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For example, the following source code:
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char g_foo = 'c';
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char g_foo = 'c';
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| Line 1084... |
Line 1084... |
descriptor `i' is supposed to deal with this case (it is said to mean
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descriptor `i' is supposed to deal with this case (it is said to mean
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"value parameter by reference, indirect access"; I don't know the
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"value parameter by reference, indirect access"; I don't know the
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source for this information), but I don't know details or what
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source for this information), but I don't know details or what
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compilers or debuggers use it, if any (not GDB or GCC). It is not
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compilers or debuggers use it, if any (not GDB or GCC). It is not
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clear to me whether this case needs to be dealt with differently than
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clear to me whether this case needs to be dealt with differently than
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parameters passed by reference (*note Reference Parameters::.).
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parameters passed by reference (*note Reference Parameters::).
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File: stabs.info, Node: Local Variable Parameters, Next: Reference Parameters, Prev: Register Parameters, Up: Parameters
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File: stabs.info, Node: Local Variable Parameters, Next: Reference Parameters, Prev: Register Parameters, Up: Parameters
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Storing Parameters as Local Variables
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Storing Parameters as Local Variables
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| Line 1119... |
Line 1119... |
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.stabs "f:p13",160,0,3,8 # 160 is `N_PSYM', here 13 is `double'
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.stabs "f:p13",160,0,3,8 # 160 is `N_PSYM', here 13 is `double'
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.stabs "f:r12",64,0,3,0 # 64 is `N_RSYM', here 12 is `float'
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.stabs "f:r12",64,0,3,0 # 64 is `N_RSYM', here 12 is `float'
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In both stabs 3 is the line number where `f' is declared (*note Line
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In both stabs 3 is the line number where `f' is declared (*note Line
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Numbers::.).
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Numbers::).
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GCC, at least on the 960, has another solution to the same problem.
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GCC, at least on the 960, has another solution to the same problem.
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It uses a single `p' symbol descriptor for an argument which is stored
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It uses a single `p' symbol descriptor for an argument which is stored
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as a local variable but uses `N_LSYM' instead of `N_PSYM'. In this
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as a local variable but uses `N_LSYM' instead of `N_PSYM'. In this
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case, the value of the symbol is an offset relative to the local
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case, the value of the symbol is an offset relative to the local
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