[Bug tree-optimization/59388] New: ICE on valid code at -O1 and above on x86_64-linux-gnu

[su at cs dot ucdavis.edu]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59388

            Bug ID: 59388
           Summary: ICE on valid code at -O1 and above 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
-O1 and above on x86_64-linux-gnu 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 --prefix=/usr/local/gcc-trunk
--enable-languages=c,c++ --disable-werror --enable-multilib
Thread model: posix
gcc version 4.9.0 20131204 (experimental) [trunk revision 205673] (GCC) 
$ 
$ gcc-trunk -O0 small.c; a.out
$ gcc-4.8 -O1 small.c; a.out
$ 
$ gcc-trunk -O1 small.c
small.c: In function ‘main’:
small.c:9:1: error: definition in block 2 follows the use
 main () 
 ^
for SSA_NAME: _2 in statement:
_8 = _2;
small.c:9:1: internal compiler error: verify_ssa failed
0xb56fcc verify_ssa(bool)
    ../../gcc-trunk/gcc/tree-ssa.c:1096
0x8fa8be execute_function_todo
    ../../gcc-trunk/gcc/passes.c:1844
0x8fb2b3 execute_todo
    ../../gcc-trunk/gcc/passes.c:1877
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.
$ 


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


int a;

struct
{
  unsigned int f:1;
} b;

int 
main () 
{ 
  a = (0 < b.f) | b.f; 
  return a; 
}