@ifinfo
This document describes the stabs debugging symbol tables.
-Copyright 1992, 93, 94, 95, 97, 1998 Free Software Foundation, Inc.
+Copyright 1992,1993,1994,1995,1997,1998,2000,2001
+ Free Software Foundation, Inc.
Contributed by Cygnus Support. Written by Julia Menapace, Jim Kingdon,
and David MacKenzie.
-Permission is granted to make and distribute verbatim copies of
-this manual provided the copyright notice and this permission notice
-are preserved on all copies.
-
-@ignore
-Permission is granted to process this file through Tex and print the
-results, provided the printed document carries copying permission
-notice identical to this one except for the removal of this paragraph
-(this paragraph not being relevant to the printed manual).
-
-@end ignore
-Permission is granted to copy or distribute modified versions of this
-manual under the terms of the GPL (for which purpose this text may be
-regarded as a program in the language TeX).
+Permission is granted to copy, distribute and/or modify this document
+under the terms of the GNU Free Documentation License, Version 1.1 or
+any later version published by the Free Software Foundation; with no
+Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
+Texts. A copy of the license is included in the section entitled ``GNU
+Free Documentation License''.
@end ifinfo
@setchapternewpage odd
@end tex
@vskip 0pt plus 1filll
-Copyright @copyright{} 1992, 93, 94, 95, 97, 1998 Free Software Foundation, Inc.
+Copyright @copyright{} 1992,1993,1994,1995,1997,1998,2000,2001 Free Software Foundation, Inc.
Contributed by Cygnus Support.
-Permission is granted to make and distribute verbatim copies of
-this manual provided the copyright notice and this permission notice
-are preserved on all copies.
-
+Permission is granted to copy, distribute and/or modify this document
+under the terms of the GNU Free Documentation License, Version 1.1 or
+any later version published by the Free Software Foundation; with no
+Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
+Texts. A copy of the license is included in the section entitled ``GNU
+Free Documentation License''.
@end titlepage
@ifinfo
* Symbol Descriptors:: Table of symbol descriptors
* Type Descriptors:: Table of type descriptors
* Expanded Reference:: Reference information by stab type
-* Questions:: Questions and anomolies
+* Questions:: Questions and anomalies
* Stab Sections:: In some object file formats, stabs are
in sections.
* Symbol Types Index:: Index of symbolic stab symbol type names.
+* GNU Free Documentation License:: The license for this documentation
@end menu
@end ifinfo
+@c TeX can handle the contents at the start but makeinfo 3.12 can not
+@iftex
+@contents
+@end iftex
@node Overview
@chapter Overview of Stabs
additionally permit a @var{type-number} to be a pair
(@var{file-number},@var{filetype-number}) (the parentheses appear in the
string, and serve to distinguish the two cases). The @var{file-number}
-is a number starting with 1 which is incremented for each seperate
-source file in the compilation (e.g., in C, each header file gets a
-different number). The @var{filetype-number} is a number starting with
+is 0 for the base source file, 1 for the first included file, 2 for the
+next, and so on. The @var{filetype-number} is a number starting with
1 which is incremented for each new type defined in the file.
(Separating the file number and the type number permits the
@code{N_BINCL} optimization to succeed more often; see @ref{Include
or a bitstring instead of a set. It doesn't change the layout of the
data being represented, but does enable the debugger to know which type
it is.
+
+@item V
+Indicate that this type is a vector instead of an array. The only
+major difference between vectors and arrays is that vectors are
+passed by value instead of by reference (vector coprocessor extension).
+
@end table
All of this can make the string field quite long. All versions of GDB,
If the linker detects that two source files have identical stabs between
an @code{N_BINCL} and @code{N_EINCL} pair (as will generally be the case
for a header file), then it only puts out the stabs once. Each
-additional occurance is replaced by an @code{N_EXCL} symbol. I believe
+additional occurrence is replaced by an @code{N_EXCL} symbol. I believe
the GNU linker and the Sun (both SunOS4 and Solaris) linker are the only
ones which supports this feature.
.stabn 224,0,0,LBE2 # @r{224 is N_RBRAC}
@end example
-@xref{Procedures} for more information on the @code{N_FUN} stab, and
+See @ref{Procedures} for more information on the @code{N_FUN} stab, and
@ref{Block Structure} for more information on the @code{N_LBRAC} and
@code{N_RBRAC} stabs.
would need to know about the type---in some cases they merely specify
enough information to distinguish the type from other types.
-The traditional way to define builtin types is convolunted, so new ways
+The traditional way to define builtin types is convoluted, so new ways
have been invented to describe them. Sun's @code{acc} uses special
builtin type descriptors (@samp{b} and @samp{R}), and IBM uses negative
type numbers. GDB accepts all three ways, as of version 4.8; dbx just
formats. The following sections describe each of these formats.
@menu
-* Traditional Builtin Types:: Put on your seatbelts and prepare for kludgery
+* Traditional Builtin Types:: Put on your seat belts and prepare for kludgery
* Builtin Type Descriptors:: Builtin types with special type descriptors
* Negative Type Numbers:: Builtin types using negative type numbers
@end menu
These are for complex numbers. A comment in the GDB source describes
them as Fortran @code{complex}, @code{double complex}, and
@code{complex*16}, respectively, but what does that mean? (i.e., Single
-precision? Double precison?).
+precision? Double precision?).
@item 6 (NF_LDOUBLE)
Long double. This should probably only be used for Sun format
the argument list.
@item a @var{register-number}
-The bound is pased by reference in register number
+The bound is passed by reference in register number
@var{register-number}.
@item t @var{register-number}
The following source code declares a structure tag and defines an
instance of the structure in global scope. Then a @code{typedef} equates the
-structure tag with a new type. Seperate stabs are generated for the
+structure tag with a new type. Separate stabs are generated for the
structure tag, the structure @code{typedef}, and the structure instance. The
-stabs for the tag and the @code{typedef} are emited when the definitions are
+stabs for the tag and the @code{typedef} are emitted when the definitions are
encountered. Since the structure elements are not initialized, the
stab and code for the structure variable itself is located at the end
of the program in the bss section.
Following the @samp{s} type descriptor is the number of bytes the
structure occupies, followed by a description of each structure element.
-The structure element descriptions are of the form @var{name:type, bit
-offset from the start of the struct, number of bits in the element}.
+The structure element descriptions are of the form
+@samp{@var{name}:@var{type}, @var{bit offset from the start of the
+struct}, @var{number of bits in the element}}.
@c FIXME: phony line break. Can probably be fixed by using an example
@c with fewer fields.
element description is a simple type reference. The other two structure
elements are new types. In this case there is a type definition
embedded after the @samp{@var{name}:}. The type definition for the
-array element looks just like a type definition for a standalone array.
+array element looks just like a type definition for a stand-alone array.
The @code{s_next} field is a pointer to the same kind of structure that
the field is an element of. So the definition of structure type 16
contains a type definition for an element which is a pointer to type 16.
the procedure in which it is defined. The stab type is @code{N_LSYM}. This
would seem to imply that the union type is file scope, like the struct
type @code{s_tag}. This is not true. The contents and position of the stab
-for @code{u_type} do not convey any infomation about its procedure local
+for @code{u_type} do not convey any information about its procedure local
scope.
@c FIXME: phony line break. Can probably be fixed by using an example
descriptor @samp{u}, following the @samp{23=} of the type definition,
narrows it down to a union type definition. Following the @samp{u} is
the number of bytes in the union. After that is a list of union element
-descriptions. Their format is @var{name:type, bit offset into the
-union, number of bytes for the element;}.
+descriptions. Their format is @samp{@var{name}:@var{type}, @var{bit
+offset into the union}, @var{number of bytes for the element};}.
The stab for the union variable is:
* Protections::
* Method Modifiers::
* Virtual Methods::
-* Inheritence::
+* Inheritance::
* Virtual Base Classes::
* Static Members::
@end menu
A stab describing a C++ class type is similar in format to a stab
describing a C struct, with each class member shown as a field in the
structure. The part of the struct format describing fields is
-expanded to include extra information relevent to C++ class members.
+expanded to include extra information relevant to C++ class members.
In addition, if the class has multiple base classes or virtual
functions the struct format outside of the field parts is also
augmented.
occur in the @var{operator-name} string.
The next part of the method description represents the arguments to the
-method, preceeded by a colon and ending with a semi-colon. The types of
+method, preceded by a colon and ending with a semi-colon. The types of
the arguments are expressed in the same way argument types are expressed
in C++ name mangling. In this example an @code{int} and a @code{char}
map to @samp{ic}.
@c GDB. But gpcompare.texi doesn't seem to be in the FSF GCC.
@example
-.stabs "name:symbol_desriptor(global function)return_type(int)",
+.stabs "name:symbol_descriptor(global function)return_type(int)",
N_FUN, NIL, NIL, code_addr_of_method_start
.stabs "Ameth__5baseAic:F1",36,0,0,_Ameth__5baseAic
Here is the stab for the @code{this} pointer implicit argument. The
name of the @code{this} pointer is always @code{this}. Type 19, the
@code{this} pointer is defined as a pointer to type 20, @code{baseA},
-but a stab defining @code{baseA} has not yet been emited. Since the
-compiler knows it will be emited shortly, here it just outputs a cross
+but a stab defining @code{baseA} has not yet been emitted. Since the
+compiler knows it will be emitted shortly, here it just outputs a cross
reference to the undefined symbol, by prefixing the symbol name with
@samp{xs}.
@node Member Type Descriptor
@section The @samp{@@} Type Descriptor
-The @samp{@@} type descriptor is for a member (class and variable) type.
-It is followed by type information for the offset basetype, a comma, and
-type information for the type of the field being pointed to. (FIXME:
-this is acknowledged to be gibberish. Can anyone say what really goes
-here?).
+The @samp{@@} type descriptor is used together with the @samp{*} type
+descriptor for a pointer-to-non-static-member-data type. It is followed
+by type information for the class (or union), a comma, and type
+information for the member data.
+
+The following C++ source:
+
+@smallexample
+typedef int A::*int_in_a;
+@end smallexample
+
+generates the following stab:
+
+@smallexample
+.stabs "int_in_a:t20=*21=@@19,1",128,0,0,0
+@end smallexample
Note that there is a conflict between this and type attributes
(@pxref{String Field}); both use type descriptor @samp{@@}.
@section Protections
In the simple class definition shown above all member data and
-functions were publicly accessable. The example that follows
-contrasts public, protected and privately accessable fields and shows
+functions were publicly accessible. The example that follows
+contrasts public, protected and privately accessible fields and shows
how these protections are encoded in C++ stabs.
If the character following the @samp{@var{field-name}:} part of the
(@samp{2}) and offset and size @samp{,32,8;}. The @code{pub} field has
type float (@samp{12}), and offset and size @samp{,64,32;}.
-Protections for member functions are signified by one digit embeded in
+Protections for member functions are signified by one digit embedded in
the field part of the stab describing the method. The digit is 0 if
private, 1 if protected and 2 if public. Consider the C++ class
definition below:
meth_name::type_def(22)=sym_desc(method)returning(int);
:args(int);protection(private)modifier(normal)virtual(no);
meth_name::type_def(23)=sym_desc(method)returning(char);
- :args(char);protection(protected)modifier(normal)virual(no);
+ :args(char);protection(protected)modifier(normal)virtual(no);
meth_name::type_def(24)=sym_desc(method)returning(float);
:args(float);protection(public)modifier(normal)virtual(no);;",
N_LSYM,NIL,NIL,NIL
meth_name(VolatileMeth)::type_def(22)=sym_desc(method)
returning(char);:arg(char);protection(public)modifier(volatile)virt(no)
meth_name(ConstVolMeth)::type_def(23)=sym_desc(method)
- returning(float);:arg(float);protection(public)modifer(const volatile)
+ returning(float);:arg(float);protection(public)modifier(const volatile)
virtual(no);;", @dots{}
@end display
semi-colon.
The second number is a type reference to the first base class in the
-inheritence hierarchy defining the virtual member function. In this
+inheritance hierarchy defining the virtual member function. In this
case the class stab describes a base class so the virtual function is
not overriding any other definition of the method. Therefore the
reference is to the type number of the class that the stab is
For classes containing virtual functions the very last section of the
string part of the stab holds a type reference to the first base
-class. This is preceeded by @samp{~%} and followed by a final semi-colon.
+class. This is preceded by @samp{~%} and followed by a final semi-colon.
@display
.stabs "class_name(A):type_def(20)=sym_desc(struct)struct_bytes(8)
A_virt::23=##1;:i;2A*-2147483647;20;;;~%20;",128,0,0,0
@end example
-@node Inheritence
-@section Inheritence
+@node Inheritance
+@section Inheritance
Stabs describing C++ derived classes include additional sections that
-describe the inheritence hierarchy of the class. A derived class stab
+describe the inheritance hierarchy of the class. A derived class stab
also encodes the number of base classes. For each base class it tells
-if the base class is virtual or not, and if the inheritence is private
+if the base class is virtual or not, and if the inheritance is private
or public. It also gives the offset into the object of the portion of
the object corresponding to each base class.
-This additional information is embeded in the class stab following the
+This additional information is embedded in the class stab following the
number of bytes in the struct. First the number of base classes
appears bracketed by an exclamation point and a comma.
Then for each base type there repeats a series: a virtual character, a
-visibilty character, a number, a comma, another number, and a
+visibility character, a number, a comma, another number, and a
semi-colon.
The virtual character is @samp{1} if the base class is virtual and
@display
.stabs "derived_class_name:symbol_descriptors(struct tag&type)=
type_descriptor(struct)struct_bytes(32)!num_bases(3),
- base_virtual(no)inheritence_public(no)base_offset(0),
+ base_virtual(no)inheritance_public(no)base_offset(0),
base_class_type_ref(A);
- base_virtual(yes)inheritence_public(no)base_offset(NIL),
+ base_virtual(yes)inheritance_public(no)base_offset(NIL),
base_class_type_ref(B);
- base_virtual(no)inheritence_public(yes)base_offset(64),
+ base_virtual(no)inheritance_public(yes)base_offset(64),
base_class_type_ref(C); @dots{}
@end display
A derived class object consists of a concatenation in memory of the data
areas defined by each base class, starting with the leftmost and ending
with the rightmost in the list of base classes. The exception to this
-rule is for virtual inheritence. In the example above, class @code{D}
+rule is for virtual inheritance. In the example above, class @code{D}
inherits virtually from base class @code{B}. This means that an
instance of a @code{D} object will not contain its own @code{B} part but
merely a pointer to a @code{B} part, known as a virtual base pointer.
Variable on the stack; see @ref{Stack Variables}.
@item :
-C++ nested symbol; see @xref{Nested Symbols}
+C++ nested symbol; see @xref{Nested Symbols}.
@item a
Parameter passed by reference in register; see @ref{Reference Parameters}.
@item b
Pascal space type (AIX); see @ref{Miscellaneous Types}. Builtin integer
type (Sun); see @ref{Builtin Type Descriptors}. Const and volatile
-qualfied type (OS9000).
+qualified type (OS9000).
@item B
Volatile-qualified type; see @ref{Miscellaneous Types}.
structures, unions, and enums (symbol descriptor @samp{T}) and typedefs
(symbol descriptor @samp{t}) defined at file scope from types defined locally
to a procedure or other more local scope. They all use the @code{N_LSYM}
-stab type. Types defined at procedure scope are emited after the
+stab type. Types defined at procedure scope are emitted after the
@code{N_RBRAC} of the preceding function and before the code of the
procedure in which they are defined. This is exactly the same as
types defined in the source file between the two procedure bodies.
-GDB overcompensates by placing all types in block #1, the block for
+GDB over-compensates by placing all types in block #1, the block for
symbols of file scope. This is true for default, @samp{-ansi} and
@samp{-traditional} compiler options. (Bugs gcc/1063, gdb/1066.)
solves the problem of having to associate the ELF and stab symbols.
However, no one has yet designed or implemented such a scheme.
+@include fdl.texi
+
@node Symbol Types Index
@unnumbered Symbol Types Index
@printindex fn
+@c TeX can handle the contents at the start but makeinfo 3.12 can not
+@ifinfo
@contents
+@end ifinfo
+@ifhtml
+@contents
+@end ifhtml
+
@bye
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