[Bug tree-optimization/60733] New: ICE by LTO on valid code at -O3 on x86_64-linux-gnu

[su at cs dot ucdavis.edu]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60733

            Bug ID: 60733
           Summary: ICE by LTO on valid code at -O3 on x86_64-linux-gnu
           Product: gcc
           Version: 4.9.0
            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 code causes an ICE when compiled with the current gcc trunk at
-O3 using LTO on x86_64-linux-gnu (in both 32-bit and 64-bit modes). 

This 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 --prefix=/usr/local/gcc-trunk
--enable-languages=c,c++ --disable-werror --enable-multilib
Thread model: posix
gcc version 4.9.0 20140401 (experimental) [trunk revision 208971] (GCC) 
$ 
$ gcc-trunk -O3 small.c; a.out
$ gcc-4.8 -flto -O3 small.c; a.out
$ 
$ gcc-trunk -flto -O3 small.c
small.c: In function ‘main’:
small.c:12:1: error: definition in block 10 follows the use
 main ()
 ^
for SSA_NAME: _83 in statement:
slsr_184 = _83 * 65535;
small.c:12:1: internal compiler error: verify_ssa failed
0xa4b70b verify_ssa(bool)
    ../../gcc-trunk/gcc/tree-ssa.c:1096
0x7ee4fc execute_function_todo
    ../../gcc-trunk/gcc/passes.c:1854
0x7eee53 execute_todo
    ../../gcc-trunk/gcc/passes.c:1887
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <http://gcc.gnu.org/bugs.html> for instructions.
lto-wrapper: gcc-trunk returned 1 exit status
/usr/bin/ld: fatal error: lto-wrapper failed
collect2: error: ld returned 1 exit status
$ 


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


int a, d, e, f, g, h, i, j, k, l;

unsigned short b;

short
fn1 (int p1, int p2)
{
  return p1 * p2;
}

int
main ()
{
  for (; a; a--)
    {
      int m = 0;
      if (h)
    {
      for (; i;)
        {
          h++;
          e = 0;
          for (;;)
        ;
        }
      for (; m != -6; m--)
        {
          int n[] = {};
          k = fn1 (b--, d);
          for (g = 0; g; g = 1)
        ;
          l = e ? n[0] : 0;
          f ^= 1;
        }
      j = 0;
      for (;;)
        ;
    }
    }
  d = 0;
  return 0;
}