This section describes the stabs support for macro define and undefine information, supported on some systems. (e.g., with -g3 -gstabs when using GCC).
A #define macro-name macro-body is represented with
an N_MAC_DEFINE stab with a string field of
macro-name macro-body.
An #undef macro-name is represented with an
N_MAC_UNDEF stabs with a string field of simply
macro-name.
For both N_MAC_DEFINE and N_MAC_UNDEF, the desc field is
the line number within the file where the corresponding #define
or #undef occurred.
For example, the following C code:
#define NONE 42
#define TWO(a, b) (a + (a) + 2 * b)
#define ONE(c) (c + 19)
main(int argc, char *argv[])
{
func(NONE, TWO(10, 11));
func(NONE, ONE(23));
#undef ONE
#define ONE(c) (c + 23)
func(NONE, ONE(-23));
return (0);
}
int global;
func(int arg1, int arg2)
{
global = arg1 + arg2;
}
produces the following stabs (as well as many others):
.stabs "NONE 42",54,0,1,0
.stabs "TWO(a,b) (a + (a) + 2 * b)",54,0,2,0
.stabs "ONE(c) (c + 19)",54,0,3,0
.stabs "ONE",58,0,10,0
.stabs "ONE(c) (c + 23)",54,0,11,0
NOTE: In the above example, 54 is N_MAC_DEFINE and
58 is N_MAC_UNDEF.