[Bug middle-end/58387] New: wrong code at -Os and above on x86_64-linux-gnu (both 32-bit and 64-bit modes)

[su at cs dot ucdavis.edu]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58387

            Bug ID: 58387
           Summary: wrong code at -Os and above on x86_64-linux-gnu (both
                    32-bit and 64-bit modes)
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
          Assignee: unassigned at gcc dot gnu.org
          Reporter: su at cs dot ucdavis.edu

The current gcc trunk produces wrong code for the attached testcase on
x86_64-linux-gnu when compiled at -Os and above in both 32-bit and 64-bit
modes. 

It is a regression from 4.8.x.  

$ gcc-trunk -v
Using built-in specs.
COLLECT_GCC=gcc-trunk
COLLECT_LTO_WRAPPER=/usr/local/gcc-trunk/libexec/gcc/x86_64-unknown-linux-gnu/4.9.0/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: ../gcc-trunk/configure
--enable-languages=c,c++,objc,obj-c++,fortran,lto
--with-gmp=/usr/local/gcc-trunk --with-mpfr=/usr/local/gcc-trunk
--with-mpc=/usr/local/gcc-trunk --with-cloog=/usr/local/gcc-trunk
--prefix=/usr/local/gcc-trunk
Thread model: posix
gcc version 4.9.0 20130910 (experimental) [trunk revision 202421] (GCC) 
$ gcc-trunk -O1 small.c
$ a.out
$ gcc-4.8 -O2 small.c
$ a.out
$ gcc-trunk -Os small.c
$ a.out
0
$ 


---------------------------------

int printf (const char *, ...);

int a = -1; 

int main ()
{
  int b = a == 0 ? 0 : -a;
  if (b < 1)
    printf ("%d\n", 0);
  return 0;
}