[Bug middle-end/101586] New: ICE:in clear_padding_type, at gimple-fold.c:4783 with call to __builtin_clear_padding for C++

[qinzhao at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101586

            Bug ID: 101586
           Summary: ICE:in clear_padding_type, at gimple-fold.c:4783 with
                    call to __builtin_clear_padding for C++
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
          Assignee: unassigned at gcc dot gnu.org
          Reporter: qinzhao at gcc dot gnu.org
  Target Milestone: ---

gcc12 failed with the following small testing case:

namespace std {
inline namespace __cxx11 {}
typedef char string;
namespace __cxx11 {
template <typename _CharT, typename = _CharT, typename = _CharT>
class basic_stringstream;
}
typedef basic_stringstream<char> stringstream;
template <typename _CharT, typename> class basic_ios {
  typedef _CharT char_type;
  char_type _M_fill;
};
template <typename _CharT, typename _Traits>
class basic_istream : virtual basic_ios<_CharT, _Traits> {};
template <typename _CharT, typename _Traits>
class basic_iostream : basic_istream<_CharT, _Traits> {};
namespace __cxx11 {
template <typename _CharT, typename _Traits, typename>
class basic_stringstream : basic_iostream<_CharT, _Traits> {};
} // namespace __cxx11
} // namespace std
class cMessage {
  std::string info() const;
};
std::string cMessage::info() const 
{ 
  std::stringstream out;
  __builtin_clear_padding (&out);
}

compiled with g++ -std=c++03 -m64, and got:

tf.c: In member function ‘std::string cMessage::info() const’:
tf.c:29:1: warning: no return statement in function returning non-void
[-Wreturn-type]
   29 | }
      | ^
during GIMPLE pass: lower
tf.c:25:13: internal compiler error: in clear_padding_type, at
gimple-fold.c:4783
   25 | std::string cMessage::info() const
      |             ^~~~~~~~
0x10e2037 clear_padding_type
        ../../latest-gcc-2/gcc/gimple-fold.c:4783
0x10e1fae clear_padding_type
        ../../latest-gcc-2/gcc/gimple-fold.c:4779
0x10e1fae clear_padding_type
        ../../latest-gcc-2/gcc/gimple-fold.c:4779
0x10e3216 gimple_fold_builtin_clear_padding
        ../../latest-gcc-2/gcc/gimple-fold.c:4981
0x10e39f5 gimple_fold_builtin
        ../../latest-gcc-2/gcc/gimple-fold.c:5155
0x10e5c95 gimple_fold_call
        ../../latest-gcc-2/gcc/gimple-fold.c:5563
0x10e916c fold_stmt_1
        ../../latest-gcc-2/gcc/gimple-fold.c:6265
0x10e94eb fold_stmt(gimple_stmt_iterator*)
        ../../latest-gcc-2/gcc/gimple-fold.c:6361
0x253052f lower_stmt
        ../../latest-gcc-2/gcc/gimple-low.c:388
0x2530093 lower_sequence
        ../../latest-gcc-2/gcc/gimple-low.c:217
0x253025e lower_stmt
        ../../latest-gcc-2/gcc/gimple-low.c:286
0x2530093 lower_sequence
        ../../latest-gcc-2/gcc/gimple-low.c:217
0x25309b0 lower_gimple_bind
        ../../latest-gcc-2/gcc/gimple-low.c:473
0x252fc89 lower_function_body
        ../../latest-gcc-2/gcc/gimple-low.c:110
0x252ffdc execute
        ../../latest-gcc-2/gcc/gimple-low.c:195
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.
ubuntu@qinzhao-ubuntu-x86:~/Bugs/uninit/bug_1$ 


This testing case is Reduced from CPU2017 benchmark and has been modified a
little bit (by adding the call to __builtin_clear_padding).