[Bug target/80382] ICE with error: unrecognizable insn

["bergner at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80382

--- Comment #9 from Peter Bergner <bergner at gcc dot gnu.org> ---
It seems you can call creduce multiple times and see some reduction.  Here's a
reduced test case:

bergner@pike:~/gcc/BUGS/PR80382$ cat bug.ii
namespace a {
typedef enum {} b;
template <typename c> struct g {
  c d;
  g(c) {}
  b f;
  void i() {
    c a;
    __atomic_load(&d, &a, f);
  }
};
}
namespace ad {
using a::g;
}
using ad::g;
class k {
  int *ak;
  int h;
};
class l {
public:
  template <typename j> l(j);
};
class m {
public:
  m() : as(k()), au(1) { as.i(); }
  g<k> as;
  l au;
};
enum av : int;
class n {
public:
  n(int, av);
};
class G {
  G();
  bool ay;
  m e;
  n bf;
};
enum av : int { bg };
int bh();
G::G() : bf(bh(), bg) {}
bergner@pike:~/gcc/BUGS/PR80382$
/home/bergner/gcc/build/gcc-fsf-mainline-pr80382-debug/gcc/xg++
-B/home/bergner/gcc/build/gcc-fsf-mainline-pr80382-debug/gcc -O3 -std=c++11
-mtune=power8 -mcpu=power8 -mno-lra -S bug.ii
bug.ii: In constructor ‘G::G()’:
bug.ii:44:24: error: unrecognizable insn:
 G::G() : bf(bh(), bg) {}
                        ^
(insn 12 11 13 2 (set (reg:PTI 165)
        (unspec:PTI [
                (mem/v:TI (plus:DI (reg/f:DI 161 [ this ])
                        (const_int 8 [0x8])) [-1  S16 A128])
            ] UNSPEC_LSQ)) "bug.ii":9 -1
     (nil))
bug.ii:44:24: internal compiler error: in extract_insn, at recog.c:2311
0x110c3cf7 _fatal_insn(char const*, rtx_def const*, char const*, int, char
const*)
        /home/bergner/gcc/gcc-fsf-mainline-pr80382/gcc/rtl-error.c:108
0x110c3d6b _fatal_insn_not_found(rtx_def const*, char const*, int, char const*)
        /home/bergner/gcc/gcc-fsf-mainline-pr80382/gcc/rtl-error.c:116
0x1104ac5b extract_insn(rtx_insn*)
        /home/bergner/gcc/gcc-fsf-mainline-pr80382/gcc/recog.c:2311
0x10c0063f instantiate_virtual_regs_in_insn
        /home/bergner/gcc/gcc-fsf-mainline-pr80382/gcc/function.c:1589
0x10c0260f instantiate_virtual_regs
        /home/bergner/gcc/gcc-fsf-mainline-pr80382/gcc/function.c:1957
0x10c027af execute
        /home/bergner/gcc/gcc-fsf-mainline-pr80382/gcc/function.c:2006
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.