[Bug tree-optimization/86858] New: gcc ICE at -O3 in as_a, at is-a.h:197

[helloqirun at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86858

            Bug ID: 86858
           Summary: gcc ICE at -O3 in as_a, at is-a.h:197
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: helloqirun at gmail dot com
  Target Milestone: ---

It appears to be a recent regression. gcc-8.1 compiles at -O3.

$ 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/9.0.0/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 9.0.0 20180804 (experimental) [trunk revision 263307] (GCC)


$ gcc-trunk -O3 abc.c
during GIMPLE pass: vect
abc.c: In function ‘h’:
abc.c:3:6: internal compiler error: in as_a, at is-a.h:197
 void h() {
      ^
0x6e2143 gphi* as_a<gphi*, gimple>(gimple*)
        ../../gcc/gcc/is-a.h:197
0x6e2143 vect_is_simple_reduction
        ../../gcc/gcc/tree-vect-loop.c:2859
0xef63b2 vect_force_simple_reduction(_loop_vec_info*, _stmt_vec_info*, bool*,
bool)
        ../../gcc/gcc/tree-vect-loop.c:3277
0xef63b2 vect_analyze_scalar_cycles_1
        ../../gcc/gcc/tree-vect-loop.c:560
0xf01e0f vect_analyze_scalar_cycles
        ../../gcc/gcc/tree-vect-loop.c:648
0xf01e0f vect_analyze_loop_2
        ../../gcc/gcc/tree-vect-loop.c:1855
0xf01e0f vect_analyze_loop(loop*, _loop_vec_info*, vec_info_shared*)
        ../../gcc/gcc/tree-vect-loop.c:2315
0xf1d8b0 try_vectorize_loop_1
        ../../gcc/gcc/tree-vectorizer.c:867
0xf1e6c5 vectorize_loops()
        ../../gcc/gcc/tree-vectorizer.c:1069
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.


$ cat abc.c
int a, b, c, d;
char(e)(char f, char g) { return f + g; }
void h() {
  for (; c; ++c) {
    d = 0;
    for (; d != 8; d = e(d, 3)) {
      a = b && a;
      b = c;
    }
  }
}