[Bug target/46072] AIX linker chokes on debug info for uninitialized static variables

["michael.haubenwallner at salomon dot at" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46072

--- Comment #4 from Michael Haubenwallner <michael.haubenwallner at salomon dot at> 2011-01-25 12:52:22 UTC ---
What exactly is the difference for gcc between not initializing a static
variable and initializing it to zero?

This is the difference in the generated assembler file:

  $ cat mytest.c
static int myvar;

int main(void)
{
    return myvar;
}

#if defined(IVAL)
static int myvar = IVAL;
#endif

For the compilation:

  $ gcc -g mytest.c -DIVAL=0
(success)
  $ gcc -g mytest.c
ld: 0711-593 SEVERE ERROR: Symbol C_BSTAT (entry 29) in object
/tmp//cc26KLXk.o:
        The symbol refers to a csect with symbol number 0, which was not
        found. The new symbol cannot be associated with a csect and
        is being ignored.
collect2: ld returned 12 exit status
(fail)

For the analysis:

  $ gcc -g -S mytest.c -o mytestu.s
  $ gcc -g -S mytest.c -o mytest0.s -DIVAL=0
  $ diff -u mytestu.s mytest0.s 
--- mytestu.s   2011-01-25 13:39:43.000000000 +0100
+++ mytest0.s   2011-01-25 13:40:01.000000000 +0100
@@ -42,7 +42,7 @@
        .byte 31
        .align 2
  FE..main:
-       .bs     _mytest.bss_
+       .bs     _mytest.rw_[RW]
        .stabx  "myvar:S-1",myvar,133,0
        .es
  _section_.text:

Both gcc-4.5.1 and gcc-4.2.4 do make this difference.