Reproducer:
extern unsigned long long int arr_86[];
extern unsigned long long int arr_87[][15];

void test(bool a, unsigned short c[][15], unsigned char d[]) {
    for (short h = 0; h < 10; h++)
        for (char i = 0; i < 15; i += 2) {
            arr_86[0] = d[0];
            arr_87[h][0] = a ? c[h][i] : 0;
        }
}

Error:
>$ g++ -c -O3 -march=skylake-avx512 func.cpp
during GIMPLE pass: vect
func.cpp: In function ‘void test(bool, short unsigned int (*)[15], unsigned char*)’:
func.cpp:4:6: internal compiler error: in vect_slp_analyze_node_operations, at tree-vect-slp.c:3764
    4 | void test(bool a, unsigned short c[][15], unsigned char d[]) {
      |      ^~~~
0x886a4d vect_slp_analyze_node_operations
	gcc_src/gcc/tree-vect-slp.c:3764
0x1425a73 vect_slp_analyze_node_operations
	gcc_src/gcc/tree-vect-slp.c:3719
0x1425a73 vect_slp_analyze_node_operations
	gcc_src/gcc/tree-vect-slp.c:3719
0x1425a73 vect_slp_analyze_node_operations
	gcc_src/gcc/tree-vect-slp.c:3719
0x1427101 vect_slp_analyze_operations(vec_info*)
	gcc_src/gcc/tree-vect-slp.c:3914
0x1404939 vect_analyze_loop_2
	gcc_src/gcc/tree-vect-loop.c:2391
0x1404939 vect_analyze_loop(loop*, vec_info_shared*)
	gcc_src/gcc/tree-vect-loop.c:2929
0x14311f4 try_vectorize_loop_1
	gcc_src/gcc/tree-vectorizer.c:1008
0x1431c59 vectorize_loops()
	gcc_src/gcc/tree-vectorizer.c:1242
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.

gcc version 11.0.0 20201214 (22a90217305ee8c116bbc12c8d07abe7ca0ff61d)