as: Stab
7.90 '.stabd, .stabn, .stabs'
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There are three directives that begin '.stab'. All emit symbols (
Symbols), for use by symbolic debuggers. The symbols are not entered
in the 'as' hash table: they cannot be referenced elsewhere in the
source file. Up to five fields are required:
STRING
This is the symbol's name. It may contain any character except
'\000', so is more general than ordinary symbol names. Some
debuggers used to code arbitrarily complex structures into symbol
names using this field.
TYPE
An absolute expression. The symbol's type is set to the low 8 bits
of this expression. Any bit pattern is permitted, but 'ld' and
debuggers choke on silly bit patterns.
OTHER
An absolute expression. The symbol's "other" attribute is set to
the low 8 bits of this expression.
DESC
An absolute expression. The symbol's descriptor is set to the low
16 bits of this expression.
VALUE
An absolute expression which becomes the symbol's value.
If a warning is detected while reading a '.stabd', '.stabn', or
'.stabs' statement, the symbol has probably already been created; you
get a half-formed symbol in your object file. This is compatible with
earlier assemblers!
'.stabd TYPE , OTHER , DESC'
The "name" of the symbol generated is not even an empty string. It
is a null pointer, for compatibility. Older assemblers used a null
pointer so they didn't waste space in object files with empty
strings.
The symbol's value is set to the location counter, relocatably.
When your program is linked, the value of this symbol is the
address of the location counter when the '.stabd' was assembled.
'.stabn TYPE , OTHER , DESC , VALUE'
The name of the symbol is set to the empty string '""'.
'.stabs STRING , TYPE , OTHER , DESC , VALUE'
All five fields are specified.