[Bug tree-optimization/61452] New: hang at -O1 and -Os on x86_64-linux-gnu

["su at cs dot ucdavis.edu" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61452

            Bug ID: 61452
           Summary: hang at -O1 and -Os on x86_64-linux-gnu
           Product: gcc
           Version: 4.10.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: su at cs dot ucdavis.edu

The following (valid) code causes gcc trunk (as well gcc 4.8 and 4.9) to hang
at -O1 and -Os (but not at -O0, -O2, and -O3). 

This is a regression from 4.7.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/4.10.0/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: ../gcc-trunk/configure --prefix=/usr/local/gcc-trunk
--enable-languages=c,c++ --disable-werror --enable-multilib
Thread model: posix
gcc version 4.10.0 20140608 (experimental) [trunk revision 211353] (GCC) 
$ 
$ gcc-trunk -O0 small.c; a.out
$ gcc-trunk -O2 small.c; a.out
$ gcc-4.7.3 -O1 small.c; a.out
$ gcc-4.7.3 -Os small.c; a.out
$ 
$ timeout -s 9 30 gcc-trunk -O1 small.c
Killed
$ 


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


int a, b;
short c, d;
char e, f;

int
fn1 (int p1, char p2)
{
  return p1 || p2 ? 0 : p2;
}

void
fn2 ()
{
  for (; a;)
    {
      int g;
      g = c = e;
      for (; a;)
    b = fn1 (g = d = e, g);
      f = g; 
    }
}

int
main ()
{
  fn2 (); 
  return 0;
}