[Bug tree-optimization/91162] New: [9/10 Regression] ICE: tree check: expected class 'type', have 'exceptional' (error_mark) in useless_type_conversion_p, at gimple-expr.c:86 (error: invalid 'PHI' argument)

[asolokha at gmx dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91162

            Bug ID: 91162
           Summary: [9/10 Regression] ICE: tree check: expected class
                    'type', have 'exceptional' (error_mark) in
                    useless_type_conversion_p, at gimple-expr.c:86 (error:
                    invalid 'PHI' argument)
           Product: gcc
           Version: 10.0
            Status: UNCONFIRMED
          Keywords: ice-on-valid-code
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: asolokha at gmx dot com
  Target Milestone: ---
            Target: x86_64-unknown-linux-gnu

gcc-10.0.0-alpha20190707 snapshot (r273184) ICEs when compiling the following
testcase w/ -O1 -ftree-parallelize-loops=2 -fno-tree-dominator-opts --param
parloops-min-per-thread=30:

void
zf (__int128 ct)
{
  __int128 *rk = &ct;

  if (0)
    {
      int jj;

 t9:
      for (jj = 0; jj < 60; ++jj)
        {
        }

      __builtin_unreachable ();
    }

  while (*rk < 1)
    ++*rk;

  goto t9;
}

% x86_64-unknown-linux-gnu-gcc-10.0.0-alpha20190707 -O1
-ftree-parallelize-loops=2 -fno-tree-dominator-opts --param
parloops-min-per-thread=30 -c qv6ltsdb.c              
qv6ltsdb.c: In function 'zf':
qv6ltsdb.c:2:1: error: invalid 'PHI' argument
    2 | zf (__int128 ct)
      | ^~
_51
during GIMPLE pass: ompexpssa
qv6ltsdb.c:2:1: internal compiler error: tree check: expected class 'type',
have 'exceptional' (error_mark) in useless_type_conversion_p, at
gimple-expr.c:86
0x70656e tree_class_check_failed(tree_node const*, tree_code_class, char
const*, int, char const*)
       
/var/tmp/portage/sys-devel/gcc-10.0.0_alpha20190707/work/gcc-10-20190707/gcc/tree.c:9950
0x61d053 tree_class_check(tree_node*, tree_code_class, char const*, int, char
const*)
       
/var/tmp/portage/sys-devel/gcc-10.0.0_alpha20190707/work/gcc-10-20190707/gcc/tree.h:3340
0x61d053 useless_type_conversion_p(tree_node*, tree_node*)
       
/var/tmp/portage/sys-devel/gcc-10.0.0_alpha20190707/work/gcc-10-20190707/gcc/gimple-expr.c:86
0xd94001 verify_gimple_phi
       
/var/tmp/portage/sys-devel/gcc-10.0.0_alpha20190707/work/gcc-10-20190707/gcc/tree-cfg.c:4978
0xd94001 verify_gimple_in_cfg(function*, bool)
       
/var/tmp/portage/sys-devel/gcc-10.0.0_alpha20190707/work/gcc-10-20190707/gcc/tree-cfg.c:5307
0xc6e519 execute_function_todo
       
/var/tmp/portage/sys-devel/gcc-10.0.0_alpha20190707/work/gcc-10-20190707/gcc/passes.c:1963
0xc6f2c6 execute_todo
       
/var/tmp/portage/sys-devel/gcc-10.0.0_alpha20190707/work/gcc-10-20190707/gcc/passes.c:2017