* stabs.texinfo (Symbol descriptors): Re-do using @table and @xref.
(Parameters): Rewrite. (xcoff-differences, Sun-differences): Minor changes.
This commit is contained in:
Jim Kingdon
parent
57dfb584ef
commit
497e44a5f8
2 changed files with 89 additions and 57 deletions
|
|
@ -1,3 +1,9 @@
|
|||
Sun Apr 18 09:47:45 1993 Jim Kingdon (kingdon@cygnus.com)
|
||||
|
||||
* stabs.texinfo (Symbol descriptors): Re-do using @table and @xref.
|
||||
(Parameters): Rewrite.
|
||||
(xcoff-differences, Sun-differences): Minor changes.
|
||||
|
||||
Thu Apr 15 02:35:24 1993 John Gilmore (gnu@cacophony.cygnus.com)
|
||||
|
||||
* stabs.texinfo: Minor cleanup.
|
||||
|
|
|
|||
|
|
@ -983,56 +983,58 @@ The stab for @code{s_flap} is located just before the @code{N_LBRAC} for
|
|||
@node Parameters
|
||||
@section Parameters
|
||||
|
||||
@table @strong
|
||||
@item Directive:
|
||||
@code{.stabs}
|
||||
@item Type:
|
||||
@code{N_PSYM}
|
||||
@item Symbol Descriptor:
|
||||
@code{p}
|
||||
@end table
|
||||
The symbol descriptor @samp{p} is used to refer to parameters which are
|
||||
in the arglist. They follow the symbol that represents the procedure
|
||||
itself. The value of the symbol is the offset relative to the argument
|
||||
list.
|
||||
|
||||
Procedure parameters are represented by the N_PSYM stab type. The
|
||||
following source lines show the parameters of the main routine.
|
||||
If the parameter is passed in a register, or is allocated as a local
|
||||
variable rather than an argument (the latter distinction is important
|
||||
for machines in which the argument list offset is relative to something
|
||||
different from a local variable offset), then the traditional way to do
|
||||
this is to provide two symbols for each argument:
|
||||
|
||||
@example
|
||||
.stabs "arg:p1" . . .
|
||||
.stabs "arg:r1" . . .
|
||||
@end example
|
||||
|
||||
Debuggers are expected to use the second one to find the value, and the
|
||||
first one to know that it is an argument.
|
||||
|
||||
Because this is kind of ugly, some compilers use symbol descriptor @samp{P}
|
||||
or @samp{R} to indicate an argument which is in a register. The symbol
|
||||
value is the register number. @samp{P} and @samp{R} mean the same
|
||||
thing, the difference is that @samp{P} is a GNU invention and @samp{R}
|
||||
is an IBM (xcoff) invention. As of version 4.9, GDB should handle
|
||||
either one.
|
||||
|
||||
There is no symbol descriptor analogous to @samp{P} for local variables.
|
||||
Some compilers are said to use the pair of symbols approach described
|
||||
above, but I don't know which ones. On the intel 960, the type of the
|
||||
variable indicates whether a @samp{p} symbol's value is an the argument
|
||||
list offset or a local variable offset.
|
||||
|
||||
As a simple example, the code
|
||||
|
||||
@example
|
||||
17 main (argc, argv)
|
||||
18 int argc;
|
||||
19 char* argv[];
|
||||
19 char **argv;
|
||||
20 @{
|
||||
@end example
|
||||
|
||||
The N_PSYM stabs describing parameters to a function directly follow
|
||||
the N_FUN stab that represents the procedure itself. The N_FUN stab
|
||||
immediately follows the code of the procedure it describes. Following
|
||||
the N_PSYM parameter stabs are any N_LSYM stabs representing local
|
||||
variables.
|
||||
produces the stabs
|
||||
|
||||
@example
|
||||
@exdent <36> N_FUN - describing the procedure main
|
||||
|
||||
94 .stabs "main:F1",36,0,0,_main
|
||||
|
||||
@exdent <160> N_PSYM - parameters
|
||||
@exdent .stabs "name:sym_desc(value_param)type_ref(int)", N_PSYM,
|
||||
@exdent NIL, NIL, frame_ptr_offset
|
||||
|
||||
95 .stabs "argc:p1",160,0,0,68
|
||||
|
||||
@exdent <160> N_PSYM - parameter
|
||||
@exdent .stabs "name:sym_desc(value_param)type_def(20)=ptr_to type_def(21)=
|
||||
@exdent ptr_to type_ref(char)
|
||||
|
||||
94 .stabs "main:F1",36,0,0,_main ; 36 is N_FUN
|
||||
95 .stabs "argc:p1",160,0,0,68 ; 160 is N_PSYM
|
||||
96 .stabs "argv:p20=*21=*2",160,0,0,72
|
||||
@end example
|
||||
|
||||
The type definition of argv is interesting because it defines two new
|
||||
types in terms of an existing one. The ``array'' argv is really a
|
||||
pointer, according to C language rules, since it is declared as a
|
||||
parameter. Its element type is character pointers. Thus the type of
|
||||
argv is ptr to ptr to char. The stab for argv contains nested
|
||||
type_definitions. Type 21 is ptr to type 2 (char) and argv (type 20)
|
||||
is ptr to type 21.
|
||||
The type definition of argv is interesting because it contains several
|
||||
type definitions. Type 21 is ptr to type 2 (char) and argv (type 20) is
|
||||
ptr to type 21.
|
||||
|
||||
@node Aggregate Types
|
||||
@chapter Aggregate Types
|
||||
|
|
@ -2417,20 +2419,43 @@ n_type n_type name used to describe
|
|||
@node Symbol descriptors
|
||||
@section Table C: Symbol descriptors
|
||||
|
||||
@example
|
||||
descriptor meaning
|
||||
-------------------------------------------------
|
||||
(empty) local variable
|
||||
f local function
|
||||
F global function
|
||||
G global variable
|
||||
p value parameter
|
||||
r register variable
|
||||
S static global variable
|
||||
t type name
|
||||
T enumeration, struct or type tag
|
||||
V static local variable
|
||||
@end example
|
||||
@table @code
|
||||
@item (empty)
|
||||
Local variable, @xref{Automatic variables}.
|
||||
|
||||
@item f
|
||||
Local function, @xref{Procedures}.
|
||||
|
||||
@item F
|
||||
Global function, @xref{Procedures}.
|
||||
|
||||
@item t
|
||||
Type name, @xref{Typedefs}.
|
||||
|
||||
@item T
|
||||
enumeration, struct or union tag, @xref{Unions}.
|
||||
|
||||
@item G
|
||||
Global variable, @xref{Global Variables}.
|
||||
|
||||
@item r
|
||||
Register variable, @xref{Register variables}.
|
||||
|
||||
@item S
|
||||
Static file scope variable @xref{Initialized statics},
|
||||
@xref{Un-initialized static variables}.
|
||||
|
||||
@item V
|
||||
Static procedure scope variable @xref{Initialized statics},
|
||||
@xref{Un-initialized static variables}.
|
||||
|
||||
@item p
|
||||
Argument list parameter @xref{Parameters}.
|
||||
|
||||
@item P
|
||||
@item R
|
||||
Register parameter @xref{Parameters}.
|
||||
@end table
|
||||
|
||||
@node Type Descriptors
|
||||
@section Table D: Type Descriptors
|
||||
|
|
@ -3019,7 +3044,10 @@ dbx?
|
|||
@node xcoff-differences
|
||||
@appendix Differences between GNU stabs in a.out and GNU stabs in xcoff
|
||||
|
||||
(The AIX/RS6000 native object file format is xcoff with stabs)
|
||||
@c FIXME: Merge *all* these into the main body of the document.
|
||||
(The AIX/RS6000 native object file format is xcoff with stabs). This
|
||||
appendix only covers those differences which are not covered in the main
|
||||
body of this document.
|
||||
|
||||
@itemize @bullet
|
||||
@item
|
||||
|
|
@ -3081,10 +3109,6 @@ the end marked with .ei "filename"
|
|||
@item
|
||||
If the xcoff stab is a N_FUN (C_FUN) then follow the string field with
|
||||
,. instead of just ,
|
||||
|
||||
@item
|
||||
The symbol descriptor for register parameters is P for a.out and R for
|
||||
xcoff.
|
||||
@end itemize
|
||||
|
||||
|
||||
|
|
@ -3136,6 +3160,8 @@ N_LENG unknown
|
|||
@node Sun-differences
|
||||
@appendix Differences between GNU stabs and Sun native stabs.
|
||||
|
||||
@c FIXME: Merge all this stuff into the main body of the document.
|
||||
|
||||
@itemize @bullet
|
||||
@item
|
||||
GNU C stabs define *all* types, file or procedure scope, as
|
||||
|
|
@ -3144,7 +3170,7 @@ N_LSYM. Sun doc talks about using N_GSYM too.
|
|||
@item
|
||||
Stabs describing block scopes, N_LBRAC and N_RBRAC are supposed to
|
||||
contain the nesting level of the block in the desc field, re Sun doc.
|
||||
GNU stabs always have 0 in that field.
|
||||
GNU stabs always have 0 in that field. dbx seems not to care.
|
||||
|
||||
@item
|
||||
Sun C stabs use type number pairs in the format (a,b) where a is a
|
||||
|
|
|
|||
Loading…
Add table
Reference in a new issue