[Bug tree-optimization/70985] New: ICE on valid code at -O3 on x86_64-linux-gnu: verify_gimple failed

[su at cs dot ucdavis.edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70985

            Bug ID: 70985
           Summary: ICE on valid code at -O3 on x86_64-linux-gnu:
                    verify_gimple failed
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: su at cs dot ucdavis.edu
  Target Milestone: ---

The following code causes an ICE when compiled with the current gcc trunk at
-O3 on x86_64-linux-gnu in both 32-bit and 64-bit modes.

$ gcc-trunk -v
Using built-in specs.
COLLECT_GCC=gcc-trunk
COLLECT_LTO_WRAPPER=/usr/local/gcc-trunk/libexec/gcc/x86_64-pc-linux-gnu/7.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc-source-trunk/configure --enable-languages=c,c++,lto
--prefix=/usr/local/gcc-trunk --disable-bootstrap
Thread model: posix
gcc version 7.0.0 20160506 (experimental) [trunk revision 235952] (GCC) 
$ 
$ gcc-trunk -O2 -c small.c
$     
$ gcc-trunk -O3 -c small.c
small.c: In function ‘fn2’:
small.c:15:1: error: invalid operand in unary operation
 fn2 ()
 ^~~
# VUSE <.MEM_8(D)>
a_f0_lsm0.8_15 = (<unnamed-signed:24>) MEM[(struct  *)&a];
small.c:15:1: internal compiler error: verify_gimple failed
0xbfa87f verify_gimple_in_cfg(function*, bool)
        ../../gcc-source-trunk/gcc/tree-cfg.c:5166
0xae9152 execute_function_todo
        ../../gcc-source-trunk/gcc/passes.c:1968
0xae9b2b execute_todo
        ../../gcc-source-trunk/gcc/passes.c:2020
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.
$ 


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


struct
{
  int f0:24;
} a, c, d;

int b;

int
fn1 ()
{
  return 0;
}

void
fn2 ()
{
  int e;
  if (b) 
    for (; e;)
      {
        d = c;
        if (fn1 (b))
          b = a.f0;
      }
}