Hi all,
The -g1 option is described in the GCC manual as follows:
"Request debugging information and also use level to specify how much
information. The default level is 2.
...
Level 1 produces minimal information, enough for making backtraces in
parts of the program that you don’t plan to debug. This includes
descriptions of functions and external variables, and line number
tables, but no information about local variables."
From that description, I assumed that variables with external linkage
will have a debugging information present. I tried using -g1 option with
DWARF format, using a simple file that has just one line:
int foo;
When compiled with `gcc -c -O2 -gdwarf-4 -g1`, it does not produce the
Debugging Information Entry (DIE) for this variable, despite that
variable having an external linkage. It does produce a DIE for it with
the default debugging level (-g2). I tried various versions of GCC, from
7.1.0 to 9.2.0, all behave in the same way. I also tried adding an
__attribute__((externally_visible)) to that variable, but still got no
DIE is generated for it.
Am I missing something? Or is it a bug in GCC?
Here is an example using GCC 9.2 that comes with Ubuntu 19.10:
aneyman@supox:/tmp$ cat foo.c
int foo __attribute__((externally_visible));
aneyman@supox:/tmp$ gcc -c -O2 -gdwarf -g1 foo.c
aneyman@supox:/tmp$ readelf -wi foo.o
aneyman@supox:/tmp$ gcc -c -O2 -gdwarf -g2 foo.c
aneyman@supox:/tmp$ readelf -wi foo.o
...
<1><1d>: Abbrev Number: 2 (DW_TAG_variable)
<1e> DW_AT_name : foo
Regards,
Alexey.
