[Bug middle-end/68870] New: ICE on valid code at -O1, -O2 and -O3 on x86_64-linux-gnu

[su at cs dot ucdavis.edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68870

            Bug ID: 68870
           Summary: ICE on valid code at -O1, -O2 and -O3 on
                    x86_64-linux-gnu
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
          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
-O1, -O2 and -O3 on x86_64-linux-gnu in both 32-bit and 64-bit modes.

It is a regression from 5.3.x.

It looks identical to PR 68570, which has been fixed. 


$ 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 20151211 (experimental) [trunk revision 231553] (GCC) 
$ 
$ gcc-trunk -O0 -c small.c
$ gcc-5.3 -O1 -c small.c
$ 
$ gcc-trunk -O1 -c small.c
small.c: In function ‘fn1’:
small.c:9:1: internal compiler error: Segmentation fault
 fn1 ()
 ^~~

0xaf8b2f crash_signal
        ../../gcc-trunk/gcc/toplev.c:334
0xe56a14 gimple_truth_valued_p(tree_node*, tree_node* (*)(tree_node*))
        /tmp/objdir/gcc/gimple-match.c:162
0xec4c49 gimple_simplify_NE_EXPR
        /tmp/objdir/gcc/gimple-match.c:47934
0xe5c559 gimple_simplify
        /tmp/objdir/gcc/gimple-match.c:52197
0xe5ef1d gimple_resimplify2(gimple**, code_helper*, tree_node*, tree_node**,
tree_node* (*)(tree_node*))
        ../../gcc-trunk/gcc/gimple-match-head.c:159
0xecb538 gimple_simplify(gimple*, code_helper*, tree_node**, gimple**,
tree_node* (*)(tree_node*), tree_node* (*)(tree_node*))
        ../../gcc-trunk/gcc/gimple-match-head.c:748
0xb3f90f cleanup_control_expr_graph
        ../../gcc-trunk/gcc/tree-cfgcleanup.c:101
0xb3f90f cleanup_control_flow_bb
        ../../gcc-trunk/gcc/tree-cfgcleanup.c:200
0xb40ecd cleanup_tree_cfg_1
        ../../gcc-trunk/gcc/tree-cfgcleanup.c:673
0xb40ecd cleanup_tree_cfg_noloop
        ../../gcc-trunk/gcc/tree-cfgcleanup.c:737
0xb40ecd cleanup_tree_cfg()
        ../../gcc-trunk/gcc/tree-cfgcleanup.c:788
0xa2cba4 execute_function_todo
        ../../gcc-trunk/gcc/passes.c:1911
0xa2d5fb execute_todo
        ../../gcc-trunk/gcc/passes.c:2010
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 printf (const char *, ...);

int a, f, g;
char b, d;
short c;
static short e;

char
fn1 ()
{
  for (; b; b++)
    {
      int h = 5;
      for (a = 0; a < 1; a++)
        {
          for (d = 0; d < 1; d++)
            for (c = 0; c < 1; c++)
              for (; e >= 0;)
                return 5;
          if (f)
            h = 0;
        }
      if (h)
        printf ("%d", 0);
    }
  return g;
}