[Bug c/42006] New: Termination problem with -O2 and -O3

[chenyang at cs dot utah dot edu]

Using r154087, the code below never terminates with -O2 and -O3. 

y...@yang-working:~$ svngcc -O2 -o small2 small.c
y...@yang-working:~$ ./small2
1
1
...
y...@yang-working:~$ ./small1
1
2
exit!
y...@yang-working:~$ cat small.c
#include <stdio.h>

static int
my_add(int si1, int si2)
{
    return (si1 > (50-si2)) ? si1 : (si1 + si2);
}

static unsigned int
my_shift(unsigned int left, int right)
{
  return  (right > 100) ? left : (left >> right);
}

static int func_4(unsigned int p_6)
{
    for (p_6 = 1; p_6 < 3; p_6 = my_add(p_6, 1))
    {
            printf ("%d\n", p_6);
            if (my_shift(p_6, p_6))
            {
                return 0;
            }
    }
    return 0;
}

int main(void)
{
    func_4(0);
    printf("exit!\n");
    return 0;
}

y...@yang-working:~$ svngcc -v
Using built-in specs.
COLLECT_GCC=svngcc
COLLECT_LTO_WRAPPER=/home/yang/compilers/libexec/gcc/i686-pc-linux-gnu/4.5.0/lto-wrapper
Target: i686-pc-linux-gnu
Configured with: ../configure --enable-lto --prefix=/home/yang/compilers
--program-prefix=svn --enable-languages=c,c++
--with-libelf=/home/yang/compilers : (reconfigured) ../configure --enable-lto
--prefix=/home/yang/compilers --program-prefix=svn
--with-libelf=/home/yang/compilers --enable-languages=c,lto,c++ --no-create
--no-recursion : (reconfigured) ../configure --enable-lto
--prefix=/home/yang/compilers --program-prefix=svn
--with-libelf=/home/yang/compilers --enable-languages=c,c++,lto --no-create
--no-recursion : (reconfigured) ../configure --enable-lto
--prefix=/home/yang/compilers --program-prefix=svn
--with-libelf=/home/yang/compilers --enable-languages=c,c++,lto --no-create
--no-recursion : (reconfigured) ../configure --enable-lto
--prefix=/home/yang/compilers --program-prefix=svn
--with-libelf=/home/yang/compilers --enable-languages=c,c++,lto --no-create
--no-recursion
Thread model: posix
gcc version 4.5.0 20091110 (experimental) (GCC)


-- 
           Summary: Termination problem with -O2 and -O3
           Product: gcc
           Version: 4.5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: chenyang at cs dot utah dot edu
 GCC build triplet: i686-pc-linux-gnu
  GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i686-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42006