[Bug tree-optimization/70115] New: gcc ICE at -O2 (seg fault) and above on valid code on x86_64-linux-gnu

[helloqirun at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70115

            Bug ID: 70115
           Summary: gcc ICE at -O2 (seg fault) and above on valid code on
                    x86_64-linux-gnu
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: helloqirun at gmail dot com
  Target Milestone: ---

The following valid code causes an ICE when compiled with the current gcc trunk
at -O2 and above on x86_64-linux-gnu in both 32-bit and 64-bit modes.

It also crashes gcc-5.X and 4.8. But 4.9 and 4.6 work fine.


$ gcc-trunk -v
Using built-in specs.
COLLECT_GCC=gcc-trunk
COLLECT_LTO_WRAPPER=/home/absozero/trunk/root-gcc/libexec/gcc/x86_64-pc-linux-gnu/6.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc/configure --prefix=/home/absozero/trunk/root-gcc
--enable-languages=c,c++ --disable-werror --enable-multilib
Thread model: posix
gcc version 6.0.0 20160306 (experimental) [trunk revision 234013] (GCC)


$ gcc-trunk -O2 abc.c
abc.c: In function 'main':
abc.c:3:5: internal compiler error: Segmentation fault
 int main() {
     ^~~~
0xb5a3cf crash_signal
        ../../gcc/gcc/toplev.c:335
0x89d0cb contains_struct_check(tree_node*, tree_node_structure_enum, char
const*, int, char const*)
        ../../gcc/gcc/tree.h:3119
0x89d0cb fold_comparison
        ../../gcc/gcc/fold-const.c:8433
0x8826da fold_binary_loc(unsigned int, tree_code, tree_node*, tree_node*,
tree_node*)
        ../../gcc/gcc/fold-const.c:11113
0x8a0714 fold(tree_node*)
        ../../gcc/gcc/fold-const.c:12113
0xcb14b8 simplify_replace_tree
        ../../gcc/gcc/tree-ssa-loop-niter.c:1798
0xcb315c substitute_in_loop_info(loop*, tree_node*, tree_node*)
        ../../gcc/gcc/tree-ssa-loop-niter.c:4293
0xb96a17 replace_uses_by(tree_node*, tree_node*)
        ../../gcc/gcc/tree-cfg.c:1871
0xb97317 gimple_merge_blocks
        ../../gcc/gcc/tree-cfg.c:1938
0x7589b5 merge_blocks(basic_block_def*, basic_block_def*)
        ../../gcc/gcc/cfghooks.c:774
0xba0593 cleanup_tree_cfg_bb
        ../../gcc/gcc/tree-cfgcleanup.c:660
0xba0f56 cleanup_tree_cfg_1
        ../../gcc/gcc/tree-cfgcleanup.c:726
0xba0f56 cleanup_tree_cfg_noloop
        ../../gcc/gcc/tree-cfgcleanup.c:761
0xba0f56 cleanup_tree_cfg()
        ../../gcc/gcc/tree-cfgcleanup.c:812
0xc95459 tree_unroll_loops_completely(bool, bool)
        ../../gcc/gcc/tree-ssa-loop-ivcanon.c:1369
0xc956d3 execute
        ../../gcc/gcc/tree-ssa-loop-ivcanon.c:1528
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.


$ cat abc.c
typedef int size_t;
char a;
int main() {
  size_t b, c;
  for (;;) {
    b = 0;
    for (; c;)
      ;
    for (; b < sizeof(long); b++)
      ;
    for (; b < c; b++)
      a++;
    for (; c < b; c++)
      ;
  }
}