[Bug tree-optimization/79186] New: ICE on valid code at -O2 and -O3 on x86_64-linux-gnu: Segmentation fault (in VRP)

[su at cs dot ucdavis.edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79186

            Bug ID: 79186
           Summary: ICE on valid code at -O2 and -O3 on x86_64-linux-gnu:
                    Segmentation fault (in VRP)
           Product: gcc
           Version: unknown
            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: ---

It seems to be a recent regression. 

$ 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/7.0.1/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 7.0.1 20170122 (experimental) [trunk revision 244756] (GCC)
$
$ gcc-trunk -Os small.c
$
$ gcc-trunk -O2 small.c
small.c: In function ‘main’:
small.c:4:5: internal compiler error: Segmentation fault
 int main ()
     ^~~~
0xc0cdcf crash_signal
        ../../gcc-source-trunk/gcc/toplev.c:333
0xc61d17 ssa_default_def(function*, tree_node*)
        ../../gcc-source-trunk/gcc/tree-dfa.c:305
0xc64400 get_or_create_ssa_default_def(function*, tree_node*)
        ../../gcc-source-trunk/gcc/tree-dfa.c:362
0xca2dff maybe_replace_use
        ../../gcc-source-trunk/gcc/tree-into-ssa.c:1771
0xca2dff rewrite_update_stmt
        ../../gcc-source-trunk/gcc/tree-into-ssa.c:1966
0xca2dff rewrite_update_dom_walker::before_dom_children(basic_block_def*)
        ../../gcc-source-trunk/gcc/tree-into-ssa.c:2146
0x130db86 dom_walker::walk(basic_block_def*)
        ../../gcc-source-trunk/gcc/domwalk.c:265
0xc9c099 rewrite_blocks
        ../../gcc-source-trunk/gcc/tree-into-ssa.c:2210
0xca4544 update_ssa(unsigned int)
        ../../gcc-source-trunk/gcc/tree-into-ssa.c:3385
0xeb6e55 insert_range_assertions
        ../../gcc-source-trunk/gcc/tree-vrp.c:6558
0xeb6e55 execute_vrp
        ../../gcc-source-trunk/gcc/tree-vrp.c:11278
0xeb6e55 execute
        ../../gcc-source-trunk/gcc/tree-vrp.c:11376
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, b;
unsigned char c, d, e;

int main ()
{ 
  if (b || !a)
    { 
      c = a;
      if (!c && !a)
        d = 0;
      e = -a;
    }
  return 0;
}