[Bug tree-optimization/68326] New: ICE at -O3 on x86_64-linux-gnu in set_value_range, at tree-vrp.c:380

[su at cs dot ucdavis.edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68326

            Bug ID: 68326
           Summary: ICE at -O3 on x86_64-linux-gnu in set_value_range, at
                    tree-vrp.c:380
           Product: gcc
           Version: 6.0
            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.

It is a regression from 5.2.x.


$ 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/6.0.0/lto-wrapper
Target: x86_64-pc-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 6.0.0 20151112 (experimental) [trunk revision 230270] (GCC) 
$ 
$ gcc-trunk -O2 -c small.c
small.c: In function ‘fn2’:
small.c:12:27: warning: iteration 2147483638 invokes undefined behavior
[-Waggressive-loop-optimizations]
         for (e = -10; e; e--)
                           ^

small.c:12:9: note: within this loop
         for (e = -10; e; e--)
         ^

$ gcc-5.2 -O3 -c small.c
$ gcc-5.2 -O2 -c small.c
small.c: In function ‘fn2’:
small.c:12:27: warning: iteration 2147483638u invokes undefined behavior
[-Waggressive-loop-optimizations]
         for (e = -10; e; e--)
                           ^
small.c:12:9: note: containing loop
         for (e = -10; e; e--)
         ^
$ 
$ gcc-trunk -O3 -c small.c
small.c: In function ‘fn2’:
small.c:6:1: internal compiler error: in set_value_range, at tree-vrp.c:380
 fn2 ()
 ^

0xd5af36 set_value_range
        ../../gcc-trunk/gcc/tree-vrp.c:379
0xd6e5a1 adjust_range_with_scev
        ../../gcc-trunk/gcc/tree-vrp.c:4334
0xd6e5a1 vrp_visit_phi_node
        ../../gcc-trunk/gcc/tree-vrp.c:8853
0xc8f415 simulate_stmt
        ../../gcc-trunk/gcc/tree-ssa-propagate.c:327
0xc8f723 process_ssa_edge_worklist
        ../../gcc-trunk/gcc/tree-ssa-propagate.c:456
0xc90f2e ssa_propagate(ssa_prop_result (*)(gimple*, edge_def**, tree_node**),
ssa_prop_result (*)(gphi*))
        ../../gcc-trunk/gcc/tree-ssa-propagate.c:937
0xd6862c execute_vrp
        ../../gcc-trunk/gcc/tree-vrp.c:10315
0xd6862c execute
        ../../gcc-trunk/gcc/tree-vrp.c:10395
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 c, d, e, f, g, h;

short fn1 () { }

void
fn2 ()
{
  unsigned int i = 4294967286;
  if (g)
    for (;;)
      {
        for (e = -10; e; e--)
          for (h = 1; h; h = fn1 ())
            {
              if (f)
                {
                  d = fn1 ();
                  if (d)
                    continue;
                }
              i = e;
            }
        break;
      }
  if (0)
    ;
  c = i;
}