[Bug rtl-optimization/25609] New: too agressive printf optimization

[drepper at redhat dot com]

At least glibc's printf, maybe others as well, print (null) in for code like

  printf ("%s", NULL)

gcc doesn't consider this when optimizing code where the pointer passed for a
%s format specifier can be NULL.  Example:

#include <stdio.h>
int
main (int argc, char *argv[])
{
  printf ("%s\n", argc > 1 ? argv[1] : NULL);
  return 0;
}

Compiling and running this code (I use gcc 4.0.2) will result in a program
which crashes because the printf is transformed into a puts() call and puts()
does not allow NULL pointers.

There should at least be a mode in which gcc does not perform the
transformation if it cannot be sure the pointer is not NULL.  The default for
Linux and maybe other platforms should be to not perform this optimization if
the pointer can be NULL.


-- 
           Summary: too agressive printf optimization
           Product: gcc
           Version: 4.0.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: rtl-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: drepper at redhat dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25609