Bug#165992: gcc: __builtin_return_address doesn't work properly

[gsstark@mit.edu]

Package: gcc
Version: 2:2.95.4-17
Severity: normal

The following program illustrates that __builtin_return_address seg faults when
you reach the top of the stack rather than returning 0 as it is specified in
the gcc manual. 

I see the same behaviour with both gcc 2.95 and gcc 3.0.


#include <stdio.h>

int main () {a();}
a() {b();}
b() {c();}
c()
{
  printf("%d: %p\n", 0, __builtin_return_address(0));
  printf("%d: %p\n", 1, __builtin_return_address(1));
  printf("%d: %p\n", 2, __builtin_return_address(2));
  printf("%d: %p\n", 3, __builtin_return_address(3));
  printf("%d: %p\n", 4, __builtin_return_address(4));
  printf("%d: %p\n", 5, __builtin_return_address(5));
}


(gdb) run
Starting program: /tmp/a.out 
0: 0x804840f
1: 0x80483ff
2: 0x80483ef
3: 0x400450bf
4: 0x8048331
(no debugging symbols found)...(no debugging symbols found)...
Program received signal SIGSEGV, Segmentation fault.
0x080484ae in c ()
(gdb) bt
#0  0x080484ae in c ()
#1  0x0804840f in b ()
#2  0x080483ff in a ()
#3  0x080483ef in main ()
#4  0x400450bf in __libc_start_main () from /lib/libc.so.6


-- System Information
Debian Release: testing/unstable
Kernel Version: Linux stark.dyndns.tv 2.4.19 #6 Tue Sep 10 22:08:51 EDT 2002 i686 unknown unknown GNU/Linux

Versions of the packages gcc depends on:
ii  cpp            2.95.4-17      The GNU C preprocessor.
ii  cpp-2.95       2.95.4-12      The GNU C preprocessor.
ii  gcc-2.95       2.95.4-12      The GNU C compiler.