[Bug c++/71616] New: ICE on valid C++ code at -O1 and above on x86_64-linux-gnu: in binds_to_current_def_p, at symtab.c:2232

[su at cs dot ucdavis.edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71616

            Bug ID: 71616
           Summary: ICE on valid C++ code at -O1 and above on
                    x86_64-linux-gnu: in binds_to_current_def_p, at
                    symtab.c:2232
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: su at cs dot ucdavis.edu
  Target Milestone: ---

The following C++ 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.  

This is a regression from 6.1.x. 


$ g++-trunk -v
Using built-in specs.
COLLECT_GCC=g++-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 20160621 (experimental) [trunk revision 237650] (GCC) 
$ 
$ g++-trunk -O0 -c small.cpp
$ g++-6.1 -O1 -c small.cpp
$ 
$ g++-trunk -O1 -c small.cpp
_ZL21__gthrw_pthread_equalv/1 (int __gthrw_pthread_equal()) @0x7f9c64d75170
  Type: function definition analyzed alias transparent_alias weakref
  Visibility: weak
  References: pthread_equal/0 (alias)
  Referring: 
  Availability: available
  First run: 0
  Function flags: process
  Called by: _Z3foov/2 (1.00 per call) (can throw external) 
  Calls: 
small.cpp: In function ‘int pthread_equal()’:
small.cpp:10:1: internal compiler error: in binds_to_current_def_p, at
symtab.c:2232
 }
 ^
0x9ad798 symtab_node::binds_to_current_def_p(symtab_node*)
        ../../gcc-source-trunk/gcc/symtab.c:2232
0x9b6b29 set_const_flag_1
        ../../gcc-source-trunk/gcc/cgraph.c:2500
0x9b6a3c set_const_flag_1
        ../../gcc-source-trunk/gcc/cgraph.c:2531
0x9b6d9f cgraph_node::set_const_flag(bool, bool)
        ../../gcc-source-trunk/gcc/cgraph.c:2562
0x14e2a41 execute
        ../../gcc-source-trunk/gcc/ipa-pure-const.c:1829
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.
$ 


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


extern "C" __inline __attribute__ ((__gnu_inline__)) 
int pthread_equal () {}

static __typeof pthread_equal __gthrw_pthread_equal 
__attribute__ ((__weakref__ ("pthread_equal")));

void foo () 
{
  __gthrw_pthread_equal ();
}